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Enzymatic Synthesis of Glutathione Based on Energy Regeneration System
Xing ZHANG, Xiangwei CUI, Zonglin LI, Zhimin LI
$v.latestStateEn , doi: 10.14135/j.cnki.1006-3080.20190806001
[Abstract](0) [FullText HTML](0) [PDF 0KB](0)
EPR-Detectable and pH-Responsive Drug-Loaded Micelles: Preparation and in vitro Evaluation
Zhaodong WANG, Lulu SHI, Hongli ZHAO, Yayun HONG, Lifang ZHOU, Minbo LAN
, doi: 10.14135/j.cnki.1006-3080.20180725001
[Abstract](4617) [FullText HTML](1395) [PDF 1015KB](0)
Apparatus for Electrical Urethral Heater Using in Prostate Cryoablation
Hongli ZHAO, Bin QIAN, Binkai XU, Minbo LAN
, doi: 10.14135/j.cnki.1006-3080.20180830004
[Abstract](5087) [FullText HTML](1105) [PDF 1289KB](0)
Approximate Solution of Global Optimization Problem Based on Dimensionality Reduction
Dandan CHEN, Wei WANG, Yifan XU
, doi: 10.14135/j.cnki.1006-3080.2018071700
[Abstract](4965) [FullText HTML](1328) [PDF 622KB](3)
A Testis-Specific Expression Cre Recombinase in Transgenic Micel by Kap147/Kpn Hybrid Promoter
Fei LIU, Jun MENG, Liqiang FAN
, doi: 10.14135/j.cnki.1006-3080.20180830001
[Abstract](5157) [FullText HTML](1482) [PDF 1154KB](2)
Distributed ADS-B Passive Positioning Anti-Spoofing Method Based on Opportunity Reference Source
Xiaodong MA, Weina YUAN, Xiaofeng LING
, doi: 10.14135/j.cnki.1006-3080.20181115001
[Abstract](5238) [FullText HTML](1428) [PDF 1021KB](2)
Detection and Research on Blockade Events of Nanopore Current Based on Fuzzy C -Means and SLIC
Zhou SHENG, Bingyong YAN, Jiale ZHOU, Huifeng WANG
, doi: 10.14135/j.cnki.1006-3080.20181206002
[Abstract](4786) [FullText HTML](1299) [PDF 1857KB](1)
Motor Bearing Fault Diagnosis Method Based on Integrated Learning Probabilistic Neural Network
Xixi ZHANG, Xingsheng GU
, doi: 10.14135/j.cnki.1006-3080.20181206001
[Abstract](5044) [FullText HTML](1243) [PDF 1195KB](1)
Numerical Simulation of the Gas-Solid Two-Phase Flow Characteristics in the Industrial Grade MIP Riser Reactor
Miao YU, Feng QIAN, Guihua HU, Jian LONG, Tianyue LI
, doi: 10.14135/j.cnki.1006-3080.20180913003
[Abstract](5261) [FullText HTML](1437) [PDF 1286KB](4)
Ant Colony-Based Delay-Aware Routing Protocol for VehicularAd Hoc Networks
Xiang JI, Huiqun YU, Guisheng FAN, Huaiying SUN
, doi: 10.14135/j.cnki.1006-3080.20181116001
[Abstract](5357) [FullText HTML](1051) [PDF 915KB](5)
Effects of N2/CO2 on the Reaction Zone and Structure Characteristics of the CH4/O2 Diffusion Flame
Jiabao YANG, Lei HE, Huiwen ZHU, Qinghua GUO, Yan GONG, Guangsuo YU
, doi: 10.14135/j.cnki.1006-3080.20180928002
[Abstract](5038) [FullText HTML](1478) [PDF 790KB](2)
Synthesis of Hydrogenated Bisphenol A Polycarbonate via Melt Transesterification
Wenfang LU, Ming ZHANG, Guozhang WU
, doi: 10.14135/j.cnki.1006-3080.20181209002
[Abstract](4929) [FullText HTML](1211) [PDF 1046KB](6)
Progress on Si-Rhodamine Fluorescent Probes
Yongkang YAO, Junma TANG, Qin YANG, Yang FU, Yiyuan PENG, Zhiqian GUO
, doi: 10.14135/j.cnki.1006-3080.20180711001
[Abstract](4993) [FullText HTML](1240) [PDF 1029KB](8)
Effect and Mechanism of Glycerol Addition on Spiramycin I Fermentation
Peipei LIANG, Shuhong GAO, Kaiya YAO, Ling-ling SUN, Zhi-yong ZHANG, Shen LAI
, doi: 10.14135/j.cnki.1006-3080.20181228001
[Abstract](5037) [FullText HTML](1244) [PDF 784KB](23)
Whole-Set Orders Scheduling Problem in Flexible Job Shop
Zhenhao XU, Chang ZHOU, Lingbo ZHANG, Xingsheng GU
, doi: 10.14135/j.cnki.1006-3080.20181109001
[Abstract](7109) [FullText HTML](1733) [PDF 928KB](5)
Optimal Scheduling of Air Separation Units on Equipment Start-up/Shut-down and Load Dispatch
Qianqian ZHAO, Jun ZHAO, Zuhua XU, Xi CHEN, Zhijiang SHAO, Haizhong QIN
, doi: 10.14135/j.cnki.1006-3080.20181015005
[Abstract](3757) [FullText HTML](999) [PDF 928KB](1)
Design and Evaluation of Peptide Blockers Targeting PD-1
Lina QUAN, Yanyan DIAO, Qiao LI, Wenjie LI, Lili ZHU, Honglin LI
, doi: 10.14135/j.cnki.1006-3080.20181126003
[Abstract](4290) [FullText HTML](911) [PDF 832KB](3)
Chemical Rheological Behavior of New High Temperature Resistant Silicon-Containing Arylethyleneacetylene Resin
Jian DENG, Shifeng DENG, Xintong YOU, Xiaoyi ZHOU
, doi: 10.14135/j.cnki.1006-3080.20181214001
[Abstract](7009) [FullText HTML](3709) [PDF 819KB](3)
Synthesis of pH-Responsive Polymer and Its Application in Oil/Water Separation
Yaping SONG, Lin JIN, Xinyue GUAN, Chaofeng WANG, Xinxin LI
, doi: 10.14135/j.cnki.1006-3080.20181214002
[Abstract](4656) [FullText HTML](1292) [PDF 1562KB](1)
Ionic Liquid Modified Triptycene Material for Removing Anionic Dyes from Aqueous Solutions
Fangyuan YU, Li ZHOU, Yan HE, Changjun PENG, Honglai LIU
, doi: 10.14135/j.cnki.1006-3080.20190104001
[Abstract](4673) [FullText HTML](1301) [PDF 1241KB](5)
Simulation of HI Concentration Distillation in Hydrogen Production of Iodine Sulfur Cycle
Jun WANG, Xiuhui HUANG, Guomin CUI
, doi: 10.14135/j.cnki.1006-3080.
[Abstract](5900) [FullText HTML](1620) [PDF 911KB](4)
Influences of the Size and Stability of Cu Crystallite on Hydrogenation of Ethyl Acetate for Preparation of Ethanol
Xiangqing ZHAO, Yan HUANG, Weiyi ZHANG, Zhi YUE, Zhenmin CHENG
, doi: 10.14135/j.cnki.1006-3080.20181212004
[Abstract](4662) [FullText HTML](624) [PDF 929KB](3)
Preparation of Pd/CeZrOx-Al2O3/Cordierite Monolithic Catalysts and Their Catalytic Performance for Catalytic Combustion of Propane
Yu-jie JIANG, Yang-long GUO, Wang-cheng ZHAN,    , Yun GUO, Li WANG, Yun-song WANG
, doi: 10.14135/j.cnki.1006-3080.20181007001
[Abstract](3705) [FullText HTML](915) [PDF 827KB](1)
A Dynamic Multi-output Prediction Model of the Hydrogen Network in a Real-World Refinery Based on XGBoost Model
Ning WANG, Cuiwen CAO
, doi: 10.14135/j.cnki.1006-3080.3080
[Abstract](3889) [FullText HTML](787) [PDF 610KB](1)
Influences of Intramolecular Weak Interactions on Conjugation
Rong ZHANG, Ying ZHOU, Qifan YAN
, doi: 10.14135/j.cnki.1006-3080.20180902001
[Abstract](4540) [FullText HTML](1136) [PDF 1182KB](2)
Preparation and Drug Delivery of Graphene Oxide Decorated Hollow Magnetic Nanoparticles
Hongxia YIN, Yuxiang YANG, Yan HUANG, Yi ZHAO, Chaoying NI
, doi: 10.14135/j.cnki.1006-3080.20180926001
[Abstract](4687) [FullText HTML](1317) [PDF 1898KB](2)
Effects of Pump Chamber and Wear Ring on Simulation Error of Miniature Super-low Specific Speed Centrifugal Pump
Jin ZHOU, Gai-lan XING, Shao-ping ZHOU
, doi: 10.14135/j.cnki.1006-3080.2018121101
[Abstract](4494) [FullText HTML](992) [PDF 1424KB](1)
Removal of Ca2+ And Mg2+ from Dilute Hydrochloric Acid by Nanofiltration Membrane
Qiuhua CUI, Zhenliang XU, Helin PAN, Shuting LI, Yuwei YE
, doi: 10.14135/j.cnki.1006-3080.20181128001
[Abstract](3874) [FullText HTML](1084) [PDF 929KB](3)
Core/shell-Structured Fe3O4@C/PVDF Flexible Films with Improved Dielectric Properties
Qiang LIU, Jun QIAN, Zhipeng CHENG, Wenjuan KOU, Qixin ZHUANG
, doi: 10.14135/j.cnki.1006-3080.20190218002
[Abstract](5013) [FullText HTML](1290) [PDF 1920KB](3)
Approximation Algorithm of Arrangement Graph Reliability in Parallel System
Zhongbao Yu, Fangming Shao
, doi: 10.14135/j.cnki.1006-3080.20180531001
[Abstract](3655) [FullText HTML](339) [PDF 617KB](4)
Influence of Polyvinylpyrrolidone with Different Molecular Weights on the Dispersion of Multiwalled Carbon Nanotubes
Xu SHANG, Xiwei JING, Jian XU, Baicun ZHENG, Weiguang GONG
, doi: 10.14135/j.cnki.1006-3080.20180820002
[Abstract](7652) [FullText HTML](1437) [PDF 1131KB](13)
Numerical Simulation in Premixed High-Speed Jet Flame Reactor
Dongying CAI, Yuelin WANG, Xianjian DUAN, Dan HU, Yubing LI, Yanjie HU
, doi: 10.14135/j.cnki.1006-3080.20190221004
[Abstract](4376) [FullText HTML](1244) [PDF 843KB](1)
An Approximation Algorithm for The Parallel Three-Stage Flowshop Scheduling
Yi-lin CAO, Wei YU
, doi: 10.14135/j.cnki.1006-3080.20180206001
[Abstract](4886) [FullText HTML](1503) [PDF 595KB](2)
Macroscopic Photo-Responsive Behaviors of Self-assemblies Constructed by Photo-Responsive Small Molecules and Surfactants
Jie SHUAI, Jiajie HU, Yan TU, Yazhuo SHANG, HongLai LIU
, doi: 10.14135/j.cnki.1006-3080.20190821001
[Abstract](4280) [FullText HTML](880) [PDF 1448KB](2)
A New Method Based on Scaled Particle Swarm Optimisation to Reduce the PAPR of FBMC System
Tong WENG, Weina YUAN
, doi: 10.14135/j.cnki.1006-3080.20190731002
[Abstract](4298) [FullText HTML](1043) [PDF 840KB](1)
Combinational Photodynamic Therapy and Chemotherapy Based on an Amphiphilic pH-Responsive Porphyrin-Containing Block Copolymer
Chao XIAO, Jia TIAN, Feng LIU, Xianyang Zhang, Tinghu Wang, Liren Xv, Hansha Gu, Weian ZHANG
, doi: 10.14135/j.cnki.1006-3080.20190128001
[Abstract](4655) [FullText HTML](1612) [PDF 1192KB](2)
Preparation of Manganese Oxide Coating Zeolite Catalyst for Catalytic Oxidation of Toluene
Feiyang DING, Yuan XUE, Ling ZHANG, Chunzhong LI
, doi: 10.14135/j.cnki.1006-3080.20190329002
[Abstract](5756) [FullText HTML](1361) [PDF 772KB](10)
Influence of Epoxidized Ethylene Propylene Diene Rubber on Nonisothermal Crystallization Kinetics of PBT/GF Composite
Bo LIU, Meng jingzi ZONG, Zhi hong LIU, Wei WU
, doi: 10.14135/j.cnki.1006-3080.20190116004
[Abstract](4412) [FullText HTML](1429) [PDF 994KB](1)
Computer Simulation on Drug Loading Efficiency of Polymeric Prodrug
Xueli LUO, Meidong LANG
, doi: 10.14135/j.cnki.1006-3080.20190514001
[Abstract](4433) [FullText HTML](1085) [PDF 1340KB](2)
Investigation on Process Characteristics in Hydrothermal Liquefaction of Municipal Sewage Sludge
Yiqiu Zhang, Shiyong Wu, Youqing Wu, Sheng Huang, Jinsheng Gao
, doi: 10.14135/j.cnki.1006-3080.20190107001
[Abstract](4666) [FullText HTML](1133) [PDF 860KB](6)
Distributed Optimal Power Flow Analysis of Partitioned Micro-grid Based Multi-agent
Lanping CHEN, Yugang NIU
, doi: 10.14135/j.cnki.1006-3080.20190523004
[Abstract](5018) [FullText HTML](1357) [PDF 852KB](1)
Deep Learning Based Key Object Detection and Extraction for Driving Scene
Xueqin ZHANG, Yifan WEI
, doi: 10.14135/j.cnki.1006-3080.20181023002
[Abstract](4819) [FullText HTML](1269) [PDF 774KB](10)
Differential Evolution Algorithm with Competition Mechanism for Simultaneous Synthesis of Heat Exchanger Network withNo Split Streams
Peng CHEN, Na LUO
, doi: 10.14135/j.cnki.1006-3080.20181015004
[Abstract](5958) [FullText HTML](1604) [PDF 784KB](3)
Dynamic Process Quality Monitoring Based on T-TSNPR
Zheng LYU, Jian YANG, Hongbo SHI, Shuai TAN
, doi: 10.14135/j.cnki.1006-3080.20181114003
[Abstract](4856) [FullText HTML](1294) [PDF 859KB](2)
Effect of Propargyloxy Side Groups on the Cure Reaction and Properties of Novolac-Type Cyanate Ester
Qian XU, Qiaolong YUAN, Farong HUANG
, doi: 10.14135/j.cnki.1006-3080.20190321004
[Abstract](6557) [FullText HTML](1717) [PDF 1834KB](7)
Analysis of Multi-scale Turbulent Mixing Character of Cracking Coil with Twisted Tape
Dehong BAI, Yuan ZONG, Ling ZHAO
, doi: 10.14135/j.cnki.1006-3080.20190315003
[Abstract](6647) [FullText HTML](1461) [PDF 1289KB](3)
Selectivity Towards β-Me Elimination of Metallocene Catalysts in Catalytic Propylene Polymerization
Lingyun XIAO, Haiyan MA
, doi: 10.14135/j.cnki.1006-3080.20190329005
[Abstract](5491) [FullText HTML](1399) [PDF 861KB](5)
Facial Action Unit Recognition Algorithm Based on Deep Learning
Dexun WANG, Huiqun YU, Guisheng FAN
, doi: 10.14135/j.cnki.1006-3080.20190107003
[Abstract](4820) [FullText HTML](1499) [PDF 681KB](4)
Robust Extreme Learning Machine Based on p-Power Welsch Loss
Jianting CHEN, Zhencheng YE, Hui CHENG
, doi: 10.14135/j.cnki.1006-3080.20181209001
[Abstract](5151) [FullText HTML](1385) [PDF 1015KB](1)
Fume Hood Window State Recognition Method Based on Few Shot Deep Learning
Zhenwei MA, Gaoqi HE, Yubo YUAN
, doi: 10.14135/j.cnki.1006-3080.20190412004
[Abstract](4588) [FullText HTML](1096) [PDF 801KB](3)
Emotion Recognition Algorithm Based on Temporal Convolution Network
Zhenzhen SONG, Lanlan CHEN, Xiaoguang LOU
, doi: 10.14135/j.cnki.1006-3080.20190508001
[Abstract](5117) [FullText HTML](1515) [PDF 913KB](3)
A Reverse Learning Behavior Particle Swarm Optimization for Large-Scale Task Scheduling in Cloud Computing Environment
Zhaolin LAI, Xiang FENG, Huiqun YU
, doi: 10.14135/j.cnki.1006-3080.20190218001
[Abstract](5147) [FullText HTML](1507) [PDF 1044KB](10)
Strawberry Image Segmentation Based on Deeply Supervised Saliency Detection
Wenxiu QIAN, Qing CHANG, Hui XIANG, Wenbin KANG
, doi: 10.14135/j.cnki.1006-3080.20181205004
[Abstract](5174) [FullText HTML](1549) [PDF 1054KB](16)
Following Controller for Autonomous Vehicle Platooning
Qi YANG, Shirong LIU
, doi: 10.14135/j.cnki.1006-3080.20190118001
[Abstract](5485) [FullText HTML](1869) [PDF 1316KB](9)
Multi-feature Non-contact Deception Detection Technology
Jiangping WEI, Jiajun LIN, Ning CHEN
, doi: 10.14135/j.cnki.1006-3080.20190619002
[Abstract](4735) [FullText HTML](1383) [PDF 827KB](5)
Night-Vision Colorization Based on Category-Oriented Color Lookup Tables
Weiwen ZHANG, Xiaojing GU, Xingsheng GU
, doi: 10.14135/j.cnki.1006-3080.20181018005
[Abstract](5640) [FullText HTML](1382) [PDF 943KB](4)
Synthesis of a Novel Cobalt Selenide/Carbon Composites withC-PAN Coating and Application in Li-Ion Battery
Xiao CHEN, Haining YU, Nan ZHENG, Chuanpeng XU, Guangyu JIANG, Yongsheng LI
, doi: 10.14135/j.cnki.1006-3080.20190307001
[Abstract](6363) [FullText HTML](2027) [PDF 1107KB](4)
Performance and membrane fouling of produced water from shale gas treated by MBR system with salt-tolerant bacteria
yan Jin, Yong-hong Zhang, Xingfu Song, Wei Lian, Hua He, Jian-guo Yu
, doi: 10.14135/j.cnki.1006-3080.20190606001
[Abstract](5201) [FullText HTML](1545) [PDF 892KB](2)
Identification and Research on Characteristics of a Salt-tolerant Bacteria for Shale Gas Produced Water Treatment
Yan JIN, Yonghong ZHANG, Xingfu SONG, Wei LIAN, Hua HE, Jianguo YU
, doi: 10.14135/j.cnki.1006-3080.20190603001
[Abstract](4926) [FullText HTML](1404) [PDF 1041KB](2)
Integrated Quality Monitoring Method Based on Multiple Data Structure
Min XUE, Jian YANG, Shuai TAN, Hongbo SHI
, doi: 10.14135/j.cnki.1006-3080.20180821002
[Abstract](6501) [FullText HTML](1618) [PDF 697KB](4)
Structure and Properties of Recycled Polyamide 6/Carbon Fiber Composites Modified by Chain Extension
Wei WANG, Jianfeng DING, Zhean XIA, Xinxin LI
, doi: 10.14135/j.cnki.1006-3080.20190512002
[Abstract](4771) [FullText HTML](1047) [PDF 1172KB](1)
Surrogate Model of Catalytic Reforming Process Based on a New Adaptive Sampling Algorithm
Jianchao ZHANG, Wenli DU, Shui QIN
, doi: 10.14135/j.cnki.1006-3080.20180915001
[Abstract](7018) [FullText HTML](1754) [PDF 1046KB](6)
Multi-information Fusion Flame Detection Based on Ohta Color Space
Jiali LIU, Jiongyao YE
, doi: 10.14135/j.cnki.1006-3080.20180910001
[Abstract](4888) [FullText HTML](1410) [PDF 812KB](1)
Synthesis and Properties of Benzoxazole Polymers Containing Electron-Donating Triphenylamine Groups
Xuan ZHONG, Yufei WANG, Qing HUANG, Xin GUO, Jiaqi MENG, Xinxin LI
, doi: 10.14135/j.cnki.1006-3080.20190329006
[Abstract](7801) [FullText HTML](2047) [PDF 949KB](9)
Adsorption Removal of Antibiotics from Aqueous Solutions by a Triazine-Functionalized Covalent Organic Framework Material
Zhen TIAN, Shuhao AN, Helin PAN, Ting XU, Changjun PENG
, doi: 10.14135/j.cnki.1006-3080.20190428005
[Abstract](5672) [FullText HTML](1462) [PDF 1323KB](8)
Multi-objective Evolutionary Algorithm with Adaptive Neighborhood Based on Event Triggering
Xuewu WANG, Zelong XIA, Xingsheng GU
, doi: 10.14135/j.cnki.1006-3080.20181120005
[Abstract](4645) [FullText HTML](1190) [PDF 1248KB](7)
Effects of Soybean Oil on Streptomyces Cyaneogriseus ssp. Noncyanogenus Fermentation
Jia-Yun XUE, Ming-Xia ZHAO, Ze-Jian WANG, Hui-Jie SUN, Yong-Hong WANG, Ju CHU, Ying-Ping ZHUANG
$v.latestStateEn , doi: 10.14135/j.cnki.1006-3080.20190428002
[Abstract](6202) [FullText HTML](1602) [PDF 1066KB](30)
A Short Text Clustering Method which Combining Topic Model and Paragraph Vector
Yuhe RAO, Zhihao LING
$v.latestStateEn , doi: 10.14135/j.cnki.1006-3080.20190430001
[Abstract](6007) [FullText HTML](1599) [PDF 803KB](14)
Clustering Analysis and Research on the Blockages of Digitally Encoded DNA Carrier Based on VAE
Zixuan WEI, Jiale ZHOU
$v.latestStateEn , doi: 10.14135/j.cnki.1006-3080.20190424001
[Abstract](4845) [FullText HTML](1199) [PDF 930KB](9)
Synthesis of a Novel Cobalt Selenide/Carbon Composites with C-PAN Coating and Application in Li-Ion Battery
Xiao CHEN, Haining YU, Nan ZHENG, Chuanpeng XU, Guangyu JIANG, Yongsheng LI
$v.latestStateEn , doi: 10.14135/j.cnki.1006-3080.20190307001
[Abstract](909) [FullText HTML](239) [PDF 1116KB](8)
Mussel-Inspired High-Performance Adhesive Hydrogels Constructed through Charge Interaction
Bowei BI, Qixia HUA, Xuening SHEN, Yongkang PAN, Songchao TANG, Yuan YAO
$v.latestStateEn , doi: 10.14135/j.cnki.1006-3080.20190409003
[Abstract](5765) [FullText HTML](2004) [PDF 836KB](19)
Improving Protein Stability of Amino Acid Polymers during Lyophilization
Bing LI, Zihao CONG, Ximian XIAO, Yueming WU, Runhui LIU
$v.latestStateEn , doi: 10.14135/j.cnki.1006-3080.20190422001
[Abstract](5819) [FullText HTML](1632) [PDF 1030KB](9)
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).

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Enzymatic Synthesis of Glutathione Based on Energy Regeneration System
Xing ZHANG, Xiangwei CUI, Zonglin LI, Zhimin LI
, doi: 10.14135/j.cnki.1006-3080.20190806001
[Abstract](0) [FullText HTML](0) [PDF 0KB](0)
Abstract:
Glutathione (GSH), one of the thiol short peptide in organisms, is widely used in medicine, food additive, health care and cosmetic industries. In this study, a two-enzyme cascade consisting of bifunctional glutathione synthetase (GshF) and polyphosphate kinase (PPK) was constructed for ATP-regenerating synthesis of GSH. As the catalytic substrate of PPK, polyphosphate (polyP) was used to provide energy in the reaction. The efficient soluble expressions of GshF and PPK were obtained when induced at the low temperature of 18 ℃. After purification, the two enzymes were coupled together to synthesize GSH in one pot. It was found that high concentration of MgCl2 inhibited the production of GSH due to the chelation with polyP. The optimal concentration ratio of polyP to MgCl2 was 30∶45 (mmol/L∶mmol/L). At 0.5 mmol/L ADP, the reaction achieved the highest efficiency for GSH synthesis. The optimal temperature for the two-enzyme reaction was 45 ℃, achieving a high yield of 78% based on added L-cysteine. The optimal temperature for GSH synthesis was relatively high, because the activities of GshF and PPK could increase with the increased temperature. The enzyme ratio in the system was further investigated. The production of GSH was improved at higher concentration of PPK, indicating the ATP-regenerating reaction was a limiting step in the reaction. At the optimal ratio of 4 g/L PPK and 1 g/L GshF, the titer of GSH reached 58 ± 3.3 mmol/L with a productivity of 19.3 ± 1.1 mmol/L/h at 3 h, which achieved the reported highest production of GSH. Using the low-cost substrate of polyP to supply energy, the efficient cascade reaction provided a potential application for large-scale enzymatic production of GSH.
EPR-Detectable and pH-Responsive Drug-Loaded Micelles: Preparation and in vitro Evaluation
Zhaodong WANG, Lulu SHI, Hongli ZHAO, Yayun HONG, Lifang ZHOU, Minbo LAN
, doi: 10.14135/j.cnki.1006-3080.20180725001
[Abstract](4617) [FullText HTML](1395) [PDF 1015KB](0)
Abstract:
pH-Responsive micelles (PA-pH-TEMPO) modified by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was prepared via polymerization of acetylene using Schiff base as acid responsive group. The structure of the PA-pH-TEMPO was characterized by 1H nuclear magnetic resonance (1H-NMR), Fourier transform infrared (FT-IR) and electron paramagnetic resonance (EPR), respectively. Furthermore, doxorubicin (DOX), model anticancer drug, was encapsulated in the PA-pH-TEMPO to form DOX-loaded micelles (DOX@PA-pH-TEMPO) through a membrane dialysis method. The results of the experiments showed that the PA-pH-TEMPO had no significant cytotoxicity against L929 and HeLa cells. And the drug loading content and drug entrapment efficiency of the DOX@PA-pH-TEMPO micelles were determined to be 2.58% and 32.09%, respectively. The DOX@PA-pH-TEMPO micelles exhibited obvious pH responsiveness and sustained release properties, and showed a strong inhibitory effect on HeLa cells. The in vitro cellular uptake experiments of PA-pH-TEMPO and DOX@PA-pH-TEMPO demonstrated that HeLa cells showed good uptake against these materials, and an obvious EPR signal could be detected.
Apparatus for Electrical Urethral Heater Using in Prostate Cryoablation
Hongli ZHAO, Bin QIAN, Binkai XU, Minbo LAN
, doi: 10.14135/j.cnki.1006-3080.20180830004
[Abstract](5087) [FullText HTML](1105) [PDF 1289KB](0)
Abstract:
Extremely low temperature will generate around the urethra during cryosurgery, which could probably result in cryoinjury in urethra. However, the urethral warmer (heated by water) existing in the current market is lacking of offering a precise control over the temperature, which gives rise to post complications in prostate. In this paper, an electrical protective urethral heater was reformed from standard urethral catheter with the aim to assist doctors’ operation for an effective therapy. A sophisticated temperature controller was used to regulate the heating behavior of the urethral heater. The impact of different heating powers on the temperature of the wall of urethra was studied, which was simulated and tested in vitro and compared with urethral warmer. During the trials in vitro, the lowest temperature at the surface of urethral heater is higher than the sub-lethal temperature (−22 ℃) under the heating power of 9 W and two cryoprobes after cryoablation for 30 min. Therefore, urethral heater is an effective way to protect urethra from cryoinjury.
Approximate Solution of Global Optimization Problem Based on Dimensionality Reduction
Dandan CHEN, Wei WANG, Yifan XU
, doi: 10.14135/j.cnki.1006-3080.2018071700
[Abstract](4965) [FullText HTML](1328) [PDF 622KB](3)
Abstract:
The idea of dimensionality reduction is to develop a n-variable objective function onto an α-dense curve which is subsequently transformed into a one-variable function. It can be proved that the global optima of the univariate function can approximate global optima of the original problem. The approximation degree of the approximate solution depends on the density of the n-dimensional space filled by the curve. When the point on the α-dense curve is in the feasible domain, an approximate solution with sufficient accuracy can be obtained. In some cases, the reducing dimension technology is combined with other algorithms with the aim to explore a new way towards the global optimization. When α-dense curve h is constructed in the feasible set X, a n-dimensional function can be approximated by a one-dimensional function. With increase in the numbers of independent variables, solving the global optima of multivariate function turns to be more complicated and needs more calculations. In order to minimize computational complexity, length of the α-dense curve was computed to obtain general classes of reducing transformations having minimal properties, and the properties of dimensionality reduction need to be investigated. A global optimization approximation algorithm based on dimensionality reduction method was proposed to solve the nonlinear global optimization problem with box constraints. Firstly, a new reduction transformation was constructed on the interval [0, π ], and the density of the α-dense curve was given. Secondly, the amount of calculation according to the approximate algorithm was estimated from the length of the α-dense curve and the proof was given. Thirdly, a theoretical algorithm was proposed. Finally, the results of numerical experiments were listed to show the effectiveness of the algorithm.
A Testis-Specific Expression Cre Recombinase in Transgenic Micel by Kap147/Kpn Hybrid Promoter
Fei LIU, Jun MENG, Liqiang FAN
, doi: 10.14135/j.cnki.1006-3080.20180830001
[Abstract](5157) [FullText HTML](1482) [PDF 1154KB](2)
Abstract:
Gene targeting technology has been widely applied to gene function analysis. In order to precisely study gene function in specific tissues and during a specific developmental period, tissue specific or inducible promoter driven Cre recombinase to guide gene knockout or silence are often used. To study the in vitro and in vivo functions of the hybrid promoter Kap147/Kpn and to facilitate the study of gene function using Cre/loxp system, the transgenic mice of Cre recombinase guided by the heterozygous promoter Kap147/Kpn were constructed. Co-transfection assay, in-vitro cell culture experiments and dihydrotestosterone induction confirmed Kap147/Kpn promoter is cell specific and androgen inducible. Reverse transcription PCR and fluorescence quantitative PCR confirmed the testis-specific Cre gene expression in the offspring Cre-F0-2 and kidney-specific Cre gene expression in the offsprings of Cre-F0-1 and Cre-F0-6. In addition, fluorescence quantitative PCR assay showed that the amount of Cre mRNA in adult mice of Cre-F0-2 offsprings was 20−30 times higher than that in the newborn or senile mice, which is in accordance with the amount of androgen in mice, suggesting that the activity of Kap147/Kpn chimeric promoter is probably regulated by androgen. Hormone induction experiment showed that 15 mg/(kg·d) DHT accelerated the expression of Cre mRNA of about 1.7-fold in testis, and 100 mg/(kg·d) CAP reduced the expression by about 50%, which thereby demonstrates that the Kap147/Kpn hybrid promoter is androgen inducible in Cre-F0-2 transgenic mice. Upon breeding the Kap147/Kpn-Cre mice (Cre-F0-2) with double-fluorescent Cre reporter mouse (B6.129 (Cg)-Gt (ROSA) 26Sor), frozen sections from male double transgenic mice showed bright green fluorescence only in testis where Cre recombinase specifically expressed. This model mouse Cre-F0-2 with tissue specific Cre recombinase in the testis would provide a novel useful tool for studying the physiological significance of genes expressed in the testis.
Distributed ADS-B Passive Positioning Anti-Spoofing Method Based on Opportunity Reference Source
Xiaodong MA, Weina YUAN, Xiaofeng LING
, doi: 10.14135/j.cnki.1006-3080.20181115001
[Abstract](5238) [FullText HTML](1428) [PDF 1021KB](2)
Abstract:
Automatic dependent surveillance-broadcast (ADS-B) are facing an increasingly serious malicious spoofing problem. Multi station passive time difference of arrival (TDOA) location ADS-B anti-spoofing method is an effective method for identifying and locating spoofing source. However, in the existing TDOA location methods, there also exist some shortcomings, e.g., high time synchronization cost between stations, vulnerable to global navigation satellite system (GNSS) regional interference, etc. Aiming at the above problems, this paper proposes a new distributed passive location ADS-B anti-spoofing method based on opportunity reference source. By dynamically selecting some trusted ADS-B targets as opportunity reference sources, this proposed method can realize multi station synchronization, and effectively overcome the bottleneck problem of some existing TDOA Location methods. It is shown from the simulation results that by optimizing the ADS-B opportunistic reference source in the presence of a large number of ADS-B real sources and spoofing sources, the proposed method can not only accurately identify false ADS-B message, but also achieve accurate inter-station synchronization. Moreover, via the accurate inter-station synchronization, the spoofing source can be accurately located.
Detection and Research on Blockade Events of Nanopore Current Based on Fuzzy C -Means and SLIC
Zhou SHENG, Bingyong YAN, Jiale ZHOU, Huifeng WANG
, doi: 10.14135/j.cnki.1006-3080.20181206002
[Abstract](4786) [FullText HTML](1299) [PDF 1857KB](1)
Abstract:
The analysis of nanopore signal depends on the exact extraction of short and multi-level blockade events. In this paper, a new method based on grayscale is proposed to detect short and multi-level events from signal automatically. In order to reduce the interferences of noise and avoid the distortion of events via the low-pass filter, the wavelet decomposition is used to achieve the denoising of signal. And then, the denoised signal is used to generate the grayscale in which the color of blockage events differs from that of baseline. The blockade events can be extract from the grayscale by thresholding the grayscale. Short-events extracted by threshold often have shorter length. To deal with this problem, this paper utilizes fuzzy C-means(FCM) to recover the extracted short events. Compared with second-order differential method (DBC) and full width half maximum (FWHM) , the FCM can recover the short event more precisely. Multi-level events are processed by converted to grayscale without thresholding. The pixels from different levels are different and these pixels with the same level are similar. These similar pixels can be regarded as one superpixel. By counting the number of different superpixels, we can obtain the levels of the multi-level events. To get the different superpixel from the grayscale automatically, this paper introduces simple linear iterative clustering (SLIC) to split the graysacle into several superpixels. Meanwhile, we can also obtain the starting point, ending point, and the average pixel value from split superpixels. Since SLIC is sensitive to the number of cluster centers, the number of cluster center may be different for different multi-level events. To avoid this shortcoming, we set the number of cluster center as 10 to cover the most cases of multi-level events. After getting the over-splite superpixels, we utilize superpixel fusion to connect two adjacent superpixels belonging to the same level by comparing the average pixel value of each superpixel. It is shown from the simulation that the SLIC superpixel fusion can obtain the accurate number of superpixels that is the same as the one of multi-level events.
Motor Bearing Fault Diagnosis Method Based on Integrated Learning Probabilistic Neural Network
Xixi ZHANG, Xingsheng GU
, doi: 10.14135/j.cnki.1006-3080.20181206001
[Abstract](5044) [FullText HTML](1243) [PDF 1195KB](1)
Abstract:
As an important driving equipment, motor has been widely applied in industrial production. Rolling bearing is one of the most important parts of the motor. Once a fault occurs, the production process will be seriously affected. So, the diagnosis of motor bearing fault has great significance for ensuring the safe and normal production. In this paper, the probabilistic neural network (PNN) is introduced to achieve the fault classification of motor bearing. In order to deal with the shortcoming that the smoothed factor of PNN is usually artificially set from experience or repeated attempt, we propose an adaptive probabilistic neural network (SPNN) based on sine cosine algorithm (SCA). It is noted that PNN will get the fixed recognition results for the same training set and test set, which may reduce the generalization ability of PNN to some extent. Hence, this paper proposes an AdaBoost-based integrated learning model (ASPNN) via using SPNN as a weak classifier. Moreover, the output results of the strong classifier are obtained by means of the linear combination of the output probability of SPNN. Finally, the proposed ASPNN model is applied to the fault diagnosis of motor bearing. At the same time, the comparison experiments are also made on PNN, SPNN, and multi-classification Support Vector Machine (SVM) via classifying motor bearing faults. It is shown from the experimental results that the proposed ASPNN method can attain better performance than PNN, SPNN and MSVM for the diagnosis of motor bearing faults.
Numerical Simulation of the Gas-Solid Two-Phase Flow Characteristics in the Industrial Grade MIP Riser Reactor
Miao YU, Feng QIAN, Guihua HU, Jian LONG, Tianyue LI
, doi: 10.14135/j.cnki.1006-3080.20180913003
[Abstract](5261) [FullText HTML](1437) [PDF 1286KB](4)
Abstract:
Maximizing iso-paraffins (MIP) process utilizes the technique of linking two reaction zones in series to effectively improve the gasoline quality. Aiming at the fluid catalytic cracking (FCC) riser reactor in MIP process, this paper considers the three-dimensional cold simulation problem of the flow behavior of gas-solid two-phase flow in reactor via Eulerian-Eulerian two-fluid model. The computational fluid dynamic (CFD) simulation is used to analyze the gas-solid flow characteristics of three zones in the riser reactor of MIP process, i.e., the pre-lifting zone, the first reaction zone, and the second reaction zone, which was made via the velocity distribution at different elevations, respectively. Moreover, the comparison with the flow characteristics inside the rector is also made according to different ratios of catalyst to feed oil, i.e., 6, 7 and 8, respectively. It is shown from the simulation results that there exist typical non-uniform flow characteristics inside the riser reactor of MIP process. The flow in the pre-lifting zone shows a typical ring-core distribution. The maximum axial velocity of catalyst occurs in the region of about one quarter and three quarters of the radius in the first reaction. The second reaction zone has the same distribution characteristics as the first one, but the velocity of the second reaction zone is lower than that of the first one. As the ratio of catalyst to feed oil increases, both the axial velocity of the catalyst particles and the solid phase volume fraction increase.
Ant Colony-Based Delay-Aware Routing Protocol for VehicularAd Hoc Networks
Xiang JI, Huiqun YU, Guisheng FAN, Huaiying SUN
, doi: 10.14135/j.cnki.1006-3080.20181116001
[Abstract](5357) [FullText HTML](1051) [PDF 915KB](5)
Abstract:
As the foundation for intelligent transportation system (ITS), vehicular ad hoc network (VANET) has been receiving more and more attentions in recent years. Due to the high mobility and uneven spatial distribution of vehicles in vehicular networks, network topology changes frequently, which makes the routing links easy to break. Hence, how to design the reliable and efficient routing protocols for VANET is becoming a challenging task. To deal with this problem, this paper proposes an ant colony optimization (ACO) based delay-aware routing protocol (ACDAP) for urban VANETs. Firstly, according to urban road topology, the data forwarding process are divided into straight road mode and intersection mode. In the straight road mode, packets are transmitted along the road by means of greedy strategy. While in the intersection mode, some special nodes, named as bridge nodes, are selected at the junctions to connect the partition networks over road segments. These bridge nodes are responsible for launching small control packets termed as ants. Meanwhile, these bridge nodes calculate the weights of segments by using a delay-aware method that is designed according to the pheromone updating mechanism and the exploration of the optimal path in ant colony algorithms. These weights can well reflect the connectivity of segment networks. Based on the calculated weight for each road segment, a reactive routing scheme is proposed to obtain the optimal route with high network connectivity. Finally, the real urban vehicular scenario is simulated via the NS2 simulation platform, and the comparison between the ACDAP with several routing protocols including GPSR, GSR and VACO is made, from which it is shown that the proposed ACDAP protocol in this work outperforms the conventional protocols in terms of in both data packet delivery rate (PDR) and end-to-end delay (E2ED).
Effects of N2/CO2 on the Reaction Zone and Structure Characteristics of the CH4/O2 Diffusion Flame
Jiabao YANG, Lei HE, Huiwen ZHU, Qinghua GUO, Yan GONG, Guangsuo YU
, doi: 10.14135/j.cnki.1006-3080.20180928002
[Abstract](5038) [FullText HTML](1478) [PDF 790KB](2)
Abstract:
Based on the experimental platform of diffusion flame, the two-dimensional OH* distribution in the methane/oxygen co-flow diffusion flames was obtained by a UV imaging system, and a Abel deconvolution algorithm was performed as well. According to the variation of the distribution characteristics of OH*, the effects of the contents of N2 and CO2 on the flame reaction zone and structural characteristics were investigated. Additionally, the differences in the flame reaction zone and structural characteristics between the N2-diluted flame and the CO2-diluted flame were further compared. The results show that the flame turns to be thinner with increase in the diluent content. The CO2-diluted flame presents a narrower flame front than that of the N2-diluted flame under the same conditions, and the OH* chemiluminescence intensity is significantly lower. When more dilution is added into oxidant, the position of the OH* peak intensity slightly move toward flame downstream, until the dilution content reaches a certain critical value. Afterwards, it suddenly moves to the region near the outlet of the nozzle and finally tends to a constant. The increase in the diluent content in the oxidant leads to the change of dominant reaction for the OH* formation, resulting in a displacement of the flame core reaction zone. With an increase in the diluent content, the axial height of the flame reaction zone does not increase continuously, in contrast, it starts to decrease upon increasing to a certain range. Compared with the N2 diluted flame, the reaction mechanism transformation has more impacts on the axial height of the flame reaction zone in the CO2 diluted flame.
Synthesis of Hydrogenated Bisphenol A Polycarbonate via Melt Transesterification
Wenfang LU, Ming ZHANG, Guozhang WU
, doi: 10.14135/j.cnki.1006-3080.20181209002
[Abstract](4929) [FullText HTML](1211) [PDF 1046KB](6)
Abstract:
Application of traditional polycarbonates are forbidden in some fields due to the fact that bisphenol A (BPA) is not UV-resistant and it is usually regarded as an exogenous estrogen. As a result, the development of alternative polycarbonates has attracted wide attention. Here hydrogenated bisphenol A (HBPA) polycarbonate was successfully synthesized by melt polycondensation between HBPA and diphenyl carbonate (DPC). The influences of factors, such as the types and concentrations of catalysts, monomer ratio, transesterification time and temperature, on the molecular weight, molecular structure, thermal properties and appearance of the products were investigated. The results show that, as a secondary alcohol bearing weak alkalinity, HBPA is difficult to dissociate into nucleophile, which leads to a lower reactivity compared with BPA. And an alkaline catalyst with strong coordination ability, such as LiCl, exhibits high catalytic activity. With an addition of the catalyst of 0.01% (molar fraction), the molar ratio of DPC to HBPA at 1.01∶1, transesterification reaction time for 2.0 h, and the polycondensation temperature at 250 ℃, the number average molecular weight of the synthesized HBPA polycarbonate is 1.12×104 with Tg of 160 ℃, showing good color property.
Progress on Si-Rhodamine Fluorescent Probes
Yongkang YAO, Junma TANG, Qin YANG, Yang FU, Yiyuan PENG, Zhiqian GUO
, doi: 10.14135/j.cnki.1006-3080.20180711001
[Abstract](4993) [FullText HTML](1240) [PDF 1029KB](8)
Abstract:
Rhodamine dyes are widely used as fluorescent probes owing to their high absorption coefficient and broad fluorescence in the visible region of electromagnetic spectrum, high fluorescence quantum yield and photostability. A great interest in the development of new synthetic procedures for preparation of rhodamine derivatives has arisen in recent years because the probe must be covalently linked to another (bio)molecule or surface for most applications. To date, the emission wavelength of rhodamine dyes is always short, and falls behind than 600 nm, which restricts the practical application of rhodamines in living systems due to the serious background fluorescence interference. In this critical review the strategies for modification of rhodamine dyes and a discussion on the variety of applications of these new derivatives as fluorescent probes are given. Upon replacing the oxygen bridge atom by silicon, the resulting Si-rhodamines have been developed as novel near-infrared (NIR) fluorescent cores with remaining the key advantages of conventional rhodamine chromophore, and also generating the bathochromic shift in their emission wavelengths to NIR region. Based on the essential properties of Si-rhodamine, this paper mainly focuses on the principle of the red shift in the emission wavelength, the regulation of fluorescence wavelength and fluorescence quantum yield, and the design mechanism and application of Si-rhodamine fluorescent probes.
Effect and Mechanism of Glycerol Addition on Spiramycin I Fermentation
Peipei LIANG, Shuhong GAO, Kaiya YAO, Ling-ling SUN, Zhi-yong ZHANG, Shen LAI
, doi: 10.14135/j.cnki.1006-3080.20181228001
[Abstract](5037) [FullText HTML](1244) [PDF 784KB](23)
Abstract:
Spiramycin is a 16-membered macrolide antibiotic which is produced by Streptomyces ambofaciens. It is widely used in human medicine beacause of its activity against bacteria. Several impurities were easily accumulated in spiramycin-fermentation broth, especially impurity D, in which the forosamine sugar is replaced by mycarose. To improve the yield of spiramycin I and reduce the content of impurity D, the effect of glycerol addition on the fermentation of Streptomyces ambofaciens was studied and the possible mechanism was analyzed. In this study, HPLC was used to determine the fermentation titer of spiramycin I and the content of impurity. The adding of glycerol with a final concentration of 0.4% at 24 h can increase the spiramycin I titer by 17.12%, and decrease the content of impurity D by 21.39% in shake flask fermentation. The results of fermentation obtanined in a 15 L bioreactor showed that the addition of glycerol at 15 h could promote spiramycin I production wFglyith a final titer of 23314 U/mL, 27.2% higher than control (18329 U/mL), and the final impurity D content was 8.84%, 26.3% lower than control (11.99%). The level of genes transcription related to synthesis of spiramycin I was investigated by real-time PCR. The transcription analysis showed that the polyketide synthase gene srm10 (for lactone ring synthesis), aminotransferase gene srm20 (for forosamine synthesis) and methyltransferase gene srm33 (for mycarose synthesis) were increased for almost 3−5 folds in the early stage of fermentation. This study indicates that the addition of glycerol in the early stage of fermentation can promote the transcription of genes involved in lactone ring and glycosyl synthesis, leading to increase in the titer of spiramycin I and the decrease in content of impurity D.
Whole-Set Orders Scheduling Problem in Flexible Job Shop
Zhenhao XU, Chang ZHOU, Lingbo ZHANG, Xingsheng GU
, doi: 10.14135/j.cnki.1006-3080.20181109001
[Abstract](7109) [FullText HTML](1733) [PDF 928KB](5)
Abstract:
With the technological development of manufacturing industry, the requirement of customer is moving toward diversity, small-scale, or even single-piece production. Customized production is mainly suitable for the aircraft and ship manufacturing industry. Conversely, the production method oriented to whole-set orders is having a more and more wide applications. However, up to now, there have been few related works on this issue of whole-set orders, due to the special nature of the flexible job shop and the complexity of the whole-set orders scheduling. To this end, this paper proposes a new scheduling model under flexible job shop environment so as to maximize the whole-set ratio of weighted orders. Meanwhile, the three distinctive characteristics are analyzed. In order to find the global optimal solution, a new neighborhood structure is proposed according to the characteristics of the whole-set orders scheduling model. A novel max-min ant algorithm with a neighborhood structure (MMAS-NS) is constructed based on the basic max-min ant system (MMAS), which can improve the objective by reducing and eliminating bottlenecks of delivery time for orders and workpieces. The influence of each parameter on the performance of algorithms is analyzed by orthogonal experiments, which also verifies the effectiveness of new neighborhood structure. Finally, the comparison with other novel meta-heuristic algorithms, e.g., imperialist competitive algorithm, is made, from which it is shown that that the proposed MMAS-NS algorithm in this work can effectively improve the whole-set ratio of weighted order.
Optimal Scheduling of Air Separation Units on Equipment Start-up/Shut-down and Load Dispatch
Qianqian ZHAO, Jun ZHAO, Zuhua XU, Xi CHEN, Zhijiang SHAO, Haizhong QIN
, doi: 10.14135/j.cnki.1006-3080.20181015005
[Abstract](3757) [FullText HTML](999) [PDF 928KB](1)
Abstract:
In the air separation system, the air separation equipment may provide continuous oxygen, nitrogen and argon for steel plants through the pipe network. However, the frequent fluctuation of gas demand that often happen in steel plants will arise the imbalance of supply and demand and result in the res ource waste and economic loss. At the present stage, the air separation production scheduling mainly rely on the experience of operators, which cannot efficiently deal with the changes in the market and production process. Therefore, it is necessary to use mathematical models and computers to assist the production scheduling of air separation systems. In this paper, we introduce the Resource Task Network as a modeling method to describe the available equipment and the flow direction of material flow unit in the air separation system. By means of historical data and prior knowledge, we establish a mixed integer programming model for the production process. This model, composed of oxygen, nitrogen and argon pipe networks, contains the material conservation in the production process and the capacity constraints of equipment such as liquefier, gasifier and compressor. The objective of model optimization is to maximize profits, which may be efficiently solved by using SCIP. Finally, a case study of steel plant in China is performed to verify the feasibility of the proposed model. Under different demand scenarios, the production process is optimized to make decisions on the start-up and shut-down of equipment and the load dispatch of air separation device group. he research results are of great significance to the production scheduling of air separation system.
Design and Evaluation of Peptide Blockers Targeting PD-1
Lina QUAN, Yanyan DIAO, Qiao LI, Wenjie LI, Lili ZHU, Honglin LI
, doi: 10.14135/j.cnki.1006-3080.20181126003
[Abstract](4290) [FullText HTML](911) [PDF 832KB](3)
Abstract:
Currently cancer immunotherapy is one of the most popular cancer treatments. Programmed death receptor 1 /programmed death ligand-1 (PD-1/PD-L1) signaling pathway is an important immune checkpoint. Blocking the PD-1/PD-L1 signaling pathway can reactivate the exhausted T cells and enhance the immune response. Therefore, the PD-1/PD-L1 pathway has become one of the new targets in the development of anticancer drug. The monoclonal antibodies (mAbs) targeting the PD-1/PD-L1 pathway have showed remarkable clinical efficacy in various malignancies. Several mAbs targeting PD-1 (nivolumab and pembrolizumab) and PD-L1 (atezolizumab, avelumab and durvalumab) have been approved by Food and Drug Administration (FDA) for cancer therapy. However, the disadvantages of antibody drugs, such as high production cost, low stability and immunogenicity, limit their clinical applications. Therefore, discovery of low-molecular-weight blockers that disrupting the PD-1/PD-L1 pathway may provide alternatives for addressing these issues. In this study, we used the E.coli expression system to express the extracellular domain of PD-1 and obtained the recombinant PD-1 after the refolding and purification process. We designed one peptide P5-1 by computer-aided drug design, which showed a KD value of 0.21 μmol/L with PD-1. The Surface Plasmon Resonance (SPR) competitive binding assay indicated that the peptide P5-1 could block the interaction between PD-1 and PD-L1. Subsequently, we assessed the effect of the peptide P5-1 on IL-2 production of Jurkat T cells. The addition of IFN-γ pretreated BxPC-3 cells led to significant decrease in the Jurkat T cells production of IL-2, while the addition of the peptide P5-1 could restore the IL-2 production. These results suggest that the peptide P5-1 can restore the suppressed function of Jurkat T cells by blocking the interaction between PD-1 and PD-L1. Our study provided a basis on developing peptide blockers targeting PD-1 as durg candidates for cancer immunotherapy.
Chemical Rheological Behavior of New High Temperature Resistant Silicon-Containing Arylethyleneacetylene Resin
Jian DENG, Shifeng DENG, Xintong YOU, Xiaoyi ZHOU
, doi: 10.14135/j.cnki.1006-3080.20181214001
[Abstract](7009) [FullText HTML](3709) [PDF 819KB](3)
Abstract:
Zinc powder catalyzed synthesis of silicon-containing arylethyleneacetylene resin (PSEA) is liquid at room temperature, showing excellent heat resistance property, glorious dielectric property, as well as outstanding processing performance, which is thus widely used in the field of Aeronautics & Astronautics. Resin transfer molding (RTM) is a material processing method which could let the flow of low viscosity (less than 500 mPa·s) resin impregnated reinforcement material, and make it cured and formed in a closed cavity. RTM process is extensively used in the aerospace and automotive industries due to th low porosity, good mechanical properties, high dimensional stability advantages of the resulting products. Such a RTM process is applicable to PSEA resin, in this work the chemical rheological behavior of PSEA resin was investigated. The relationship between gelation time (tgel) and the corresponding temperature was studied by small plate knife within a temperature range of 423 K~463 K during the gelation and curing. Furthermore, the gelation equation model was established, and the model theoretical results were in good consistent with the experimental data. The relationship between rheological characteristics and temperature of PSEA resin was investigated by rotating viscometer and plate rheometer. The experimental results show that the resin has a long low viscosity (less than 500 mPa·s) retention period in the temperature range of 373~403 K, and retention time is longer than 4 h, which make the resin easy to process and meet the requirements of the RTM process. On the basis of the relationship between resin viscosity, time and temperature, the Dual-Arrhenius viscosity equation model was established, and the theoretical results of the equation model were in good agreement with the experimental data, providing scientific theoretical fundamentals for the preparation of composite materials by resin RTM molding.
Synthesis of pH-Responsive Polymer and Its Application in Oil/Water Separation
Yaping SONG, Lin JIN, Xinyue GUAN, Chaofeng WANG, Xinxin LI
, doi: 10.14135/j.cnki.1006-3080.20181214002
[Abstract](4656) [FullText HTML](1292) [PDF 1562KB](1)
Abstract:
The poly (dimethylaminoethyl methacrylate-co-hydroxyethyl methacrylate-co-dodecyl methacrylate, DMAEMA-co-HEMA-co-DMA) was synthesized by free radical polymerization. Then stainless steel meshes with different apertures were coated with the polymer or polymer/SiO2 through impregnation, leading to the pH-responsive oil-water-separation film. The topological structure and wettability of the meshes were analyzed by scanning electron microscope(SEM) and contact angle(CA) test, respectively. The distribution of elements were characterized by X-ray photoelectron spectroscopy(XPS). Furthermore, the oil/water separation capacity of the meshes was tested. The results demonstrated that the surfaces of the meshes turned to be smoother after the coating with the polymers, while they became very rough in case SiO2 was added into the coating. Besides, the surface wettability varied with pH, which is consistent with the XPS results. Under acidic condition, the coated surfaces were hydrophilic. But as the media was neutral/slightly alkaline, the surface became hydrophobic. Such change was related to the binding states of nitrogen. The -N- in PDMAEMA was protonated under acidic condition so that the chain stretched and the hydrophilicity was increased. Furthermore, the addition of SiO2 made the mesh superhydrophilic under acidic condition and superhydrophobic under neutral/slightly alkaline condition, which can be ascribed to the enhancement of surface roughness. But when the media was highly alkaline, the wettability of the surface was very unstable due to the chemical reaction of SiO2 under this condition. Oil/water separation experiments showed that the presence of SiO2 and polymer enabled the meshes with good capacity for the effective separation of oil and water, and additionally endowed the meshes with a good stability. Meanwhile, when the mass fraction of SiO2 was 3%, the results collected from infrared oil measurment showed that the meshes presented good separation capacity for oil-in-water emulsion, and the efficiency was more than 99%. Such results were further confirmed by DLS tests.
Ionic Liquid Modified Triptycene Material for Removing Anionic Dyes from Aqueous Solutions
Fangyuan YU, Li ZHOU, Yan HE, Changjun PENG, Honglai LIU
, doi: 10.14135/j.cnki.1006-3080.20190104001
[Abstract](4673) [FullText HTML](1301) [PDF 1241KB](5)
Abstract:
Organic dyes, especially the cationic dyes of methyl orange (MO) and Acid Green 25 (AG25), have been emerged as harmful pollutants. Developing new materials for efficient adsorption and removal of organic dyes is thus of great significance. The design of POPs with both good porosity and task-specific functionalization is still a critical challenge. In this work, an amino-containing imidazolium ionic liquid (3-propylamine-1-methylimidazolium trifluoromethanesulfonimide salt) was chemically grafted onto a triptycene-based porous polymer. The ionic liquid modified porous material (TPP-IL) was characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), Fourier transform infrared(FT-IR), thermo-gravimetric analysis(TGA), elemental analysis (EA), 13C nuclear magnetic resonance (13C NMR) and nitrogen adsorption-desorption isotherms. The results showed that TPP-IL displayed a rough, irregular morphology; porous organic polymer that is amorphous in nature. The novel polymer showed high Brunauer-Emmett-Teller surface area (of up to 781.1 m2·g−1), porosity, and physicochemical stability. The resulting polymer materials were then used as solid adsorbent for removing organic dyes. It was found that TPP-IL showed higher adsorption capacity against the anionic dyes of Acid Green 25 and Methyl Orange. The adsorption process could be described by a Langmuir isotherm adsorption model. Moreover, the experimental data fitted quasi-secondary kinetic model very well. At room temperature, the maximum adsorption capacities of TPP-IL against AG25 and MO were 571.7 and 501.9 mg.g−1, respectively, which were about 1.5 times higher than that of unmodified adsorbent TPP. Furthermore, TPP-IL exhibited an excellent recyclability. Theoretical calculations showed that TPP-IL adsorption of AG25 and MO mainly relied on electrostatic attraction, as well as hydrogen bonding interactions. Therefore, it is believed that TPP-IL with hierarchical porous structures, high surface areas, and physicochemical stability is a promising candidate for the purification and treatment of dyes in solutions.
Simulation of HI Concentration Distillation in Hydrogen Production of Iodine Sulfur Cycle
Jun WANG, Xiuhui HUANG, Guomin CUI
, doi: 10.14135/j.cnki.1006-3080.
[Abstract](5900) [FullText HTML](1620) [PDF 911KB](4)
Abstract:
In the hydrogen production of iodine-sulfur cycle, a distillation problem of HI concentration separation was considered to analyze. The NRTL model was used to modify the liquid non-ideal of the ternary mixture of HI-I2-H2O system, the two groups of NRTLs were obtained by fitting the binary gas-liquid equilibrium experiment data of H2O-HI, H2O-I2 and HI-I2 model of binary interaction parameters. The comparison between the H2O-HI vapor-liquid equilibrium phase diagram was predicted by the obtained binary interaction parameters and the experimental data showed that the prediction results were in good agreement with the experimental data, and the accuracy and reliability of the obtained binary interaction parameters were verified. The optimized operating conditions were obtained by systematic analysis and simulation of the HI rectification column by means of simulation software Aspen Plus. As the number of trays increases, the Q/m of the reboiler heat load per unit mass fraction decreases overall, but when the number of trays increases more than 13, the Q/m decreases slowly, then the 13th was the most suitable tray. As the reflux ratio increases, the Q/m of the reboiler heat load per unit mass fraction increases uniformly at a constant rate. When the reflux ratio is 1.3, the mass fraction of HI distilled has reached 0.96. After that, as the reflux ratio increases, the HI distillate increase is not obvious. Considering that the reflux ratio is too large, the operating cost and equipment cost will also be increased, so the best reflux ratio was 1.3. The HI mass fraction in the feed needs to be optimized by a specific simulation to obtain an optimum value, and the HI mass fraction and energy consumption of the discharge are not monotonous. The discussion of the number of plates, reflux ratio and feed composition on the separation conditions provides the theoretical basis and basis for the further study of industrial iodine sulfur cycle hydrogen production process.
Influences of the Size and Stability of Cu Crystallite on Hydrogenation of Ethyl Acetate for Preparation of Ethanol
Xiangqing ZHAO, Yan HUANG, Weiyi ZHANG, Zhi YUE, Zhenmin CHENG
, doi: 10.14135/j.cnki.1006-3080.20181212004
[Abstract](4662) [FullText HTML](624) [PDF 929KB](3)
Abstract:
Hydrogenation of ethyl acetate (EA) is a promising route for the synthesis of ethanol (EtOH), but the involved catalysts have a series of problems, such as low hydrogenation activity, easy sintering at high temperature, and poor stability. Therefore, it’s necessary to develop catalysts with high catalytic efficiency and stability for the hydrogenation of EA to prepare EtOH. Rare earth elements have abundant energy level structure and unique 4f orbital, and their oxides modified catalysts generally have high adsorption selectivity, excellent thermal stability and other advantages. In this paper, the Cu/SiO2 catalysts modified by different rare earth elements (Y, La, Ce and Pr) were prepared by co-precipitation method, and characterized by XRD, TEM, BET, H2-TPR, NH3-TPD and XPS. The effects of the modifications on Cu/SiO2 with different rare earth elements (Y, La, Ce and Pr) on the catalytic performances for hydrogenation of EA were investigated in a fixed bed reactor. The experimental results show that the modifications with rare earth elements (Y, La, Ce and Pr) can reduce the crystallite size of copper in the catalyst, thereby accelerating the dispersion of copper active components and increasing the pore size of the catalyst, by which the catalyst is easier to be reduced, and its surface acidity is tunable. As a result, the catalytic activity of the Cu/SiO2 catalyst for the hydrogenation is significantly increased. Furthermore, Y-modified Cu/SiO2 catalyst showed the highest hydrogenation activity due to the smallest copper crystallite size, the highest copper dispersion, the largest pore diameter, and the suitable surface acidity and molar ratio of n(Cu0)/n(Cu0+Cu+). Under the reaction conditions of 250 ℃, 2.0 MPa, WHSV of 5.0 h−1 and the molar ratio of H2 to EA of 5.0, the conversion of EA could reach 96.3% with a selectivity of EtOH of 99.1%. Also, Y-modified Cu/SiO2 catalyst showed excellent stability and resistance to sintering.
Preparation of Pd/CeZrOx-Al2O3/Cordierite Monolithic Catalysts and Their Catalytic Performance for Catalytic Combustion of Propane
Yu-jie JIANG, Yang-long GUO, Wang-cheng ZHAN,    , Yun GUO, Li WANG, Yun-song WANG
, doi: 10.14135/j.cnki.1006-3080.20181007001
[Abstract](3705) [FullText HTML](915) [PDF 827KB](1)
Abstract:
As volatile organic compounds (VOCs) are harmful to environment and human health, the purification of VOCs in the atmosphere has become more and more urgent. Among the various purification technologies for VOCs emission, catalytic combustion is considered to be the most effective one. Besides, cordierite ceramic carriers are widely used in industrial catalysis due to their high thermal stability and comparable hardness. Pseudo-boehmite, alumina modified by rare earths, and cerium-zirconium composite oxides were used as raw materials to prepare a slurry, in which alumina sol was acted as the binder. The optimum solid content of aluminum sol has been studied in previous studies. The emulsifier was used to obtain uniformly mixed slurry which was coated on a cordierite honeycomb ceramic carrier. CeZrOx-Al2O3/Cordierite scaffolds were prepared by vacuum extraction method. The effects of pH value, the solid content of slurry, and the emulsifying time on the coating performance were investigated. When pH value of slurry is 3.62, the solid content of slurry is 38%, and the emulsifying time is 30 min, the washcoat showed the best coating performance with a high loading capacity of 127 g·L-1 and a low weight loss of 0.2%. Then Pd/CeZrOx-Al2O3/Cordierite monolithic catalysts were prepared by the incipient wetness impregnation method, and their catalytic performances for the catalytic combustion of propane were investigated. The catalysts were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Pd/CeZrOx-Al2O3/Cordierite monolithic catalyst (Pd loading of 2.0 g·L-1) exhibited the best catalytic performance for the catalytic combustion of propane (T50 of 318 °C and T90 of 350 °C) among the studied catalysts, showing good industrial application prospects.
A Dynamic Multi-output Prediction Model of the Hydrogen Network in a Real-World Refinery Based on XGBoost Model
Ning WANG, Cuiwen CAO
, doi: 10.14135/j.cnki.1006-3080.3080
[Abstract](3889) [FullText HTML](787) [PDF 610KB](1)
Abstract:
In recent years, the demand for hydrogen in refineries has been greatly increased. Rationally allocating the balance between hydrogen supply and consumption, and efficiently utilizing current hydrogen resources have important theoretical and practical industrial benefits. Research has demonstrated that XGBoost model showed excellent performance in many fields, but it has not been applied to hydrogen network industrial engineering. In this paper, a dynamic multi-output prediction model of the hydrogen network in a real-world refinery based on XGBoost model is studied. The dynamic multi-output prediction is carried out using the dynamic data of two indexes of the minimum fresh hydrogen consumption and the minimum hydrogen surplus. The fresh hydrogen refers to high purity hydrogen, and the dynamic data is obtained by solving linear model in our patent. The performance of the model is evaluated, with the aim to have a better reflection on the actual situation of the prediction error and to measure the deviation between the predicted and the true values. The MAE (mean absolute error) and the RMSPE (root-mean-square percent error) are selected as evaluation criteria; the prediction results are compared with those of BP (back propagation) neural network model, and good prediction results have been obtained. Finally, the influences of five types of operational parameter features on the output indexes are analyzed. The five types of operational parameter features are characterized by four reactor temperatures and recycle hydrogen, respectively. The diagram of the feature importance scores on the two output indexes is obtained. Based on the analysis of the diagram, the features that have the highest impact on the two output indexes of the model are obtained.
Influences of Intramolecular Weak Interactions on Conjugation
Rong ZHANG, Ying ZHOU, Qifan YAN
, doi: 10.14135/j.cnki.1006-3080.20180902001
[Abstract](4540) [FullText HTML](1136) [PDF 1182KB](2)
Abstract:
Organic π-conjugated compounds have been receiving great research attention due to their wide optoelectronic applications. Previous studies on tuning single molecular photoelectric properties of organic π-conjugated compounds focused on developing new π- skeletons and introducing electron-donating and withdrawing substituents. However, the influences of intramolecular weak interaction on the optoelectrical properties of organic π-conjugated compounds are lacking of study. Herein, we designed and synthesized compounds 1~6 and 7~12 via Buchwald-Hartwig/Suzuki coupling reactions, with [2,2]paracyclophane (cyclophane), triptycene, and 9,9’-spirobifluorene (spirofluorene) as the linking units, two electron-rich diphenylamino or electron-deficient naphthalimide as the substituents. In compounds 1~6 and 7~12, the two electron-rich/electron-deficient centers interact with each other via homo-conjugation, cross-conjugation, π-π stacking, and π-direct conjugation. Photophysical and electrochemical measurements revealed that at neutral state, interactions (conjugation-effect) created by homo-conjugation in spirofluorene was lower than those created by direct π-conjugation, but was stronger than those created by cross-conjugation in spirofluorene, homo-conjugation in triptycene, and π-π stacking in cyclophane. When electron-rich compounds 1~6 lost one electron, converting into a monocation, conjugation effect decreases in the following order: Direct π-conjugation, homo-conjugation in spirofluorene, homo-conjugation in triptycene, cross-conjugation in spirofluorene. All these results demonstrated that optoelectronic properties of π-conjugated organic molecules can be tuned by the intramolecular weak interactions.
Preparation and Drug Delivery of Graphene Oxide Decorated Hollow Magnetic Nanoparticles
Hongxia YIN, Yuxiang YANG, Yan HUANG, Yi ZHAO, Chaoying NI
, doi: 10.14135/j.cnki.1006-3080.20180926001
[Abstract](4687) [FullText HTML](1317) [PDF 1898KB](2)
Abstract:
A mesoporous shell structure was synthesized using carbon spheres and cetyltrimethylammonium bromide (CTAB) as dual templates, and hollow magnetic nanoparticles (HMNPs) were subsequently prepared by etching. Hollow magnetic nanoparticles functionalized by graphene oxide (HMNPs-GO) were synthesized via the functionalization of HMNPs with NH2 groups and the activation of carboxyl groups of graphene oxide by N-ethyl-NO-(3-(dimethylamino)propyl) carbodiimide/N-hydroxysucinimide (EDC/NHS). HMNPs and HMNPs-GO were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Upon the investigations on the adsorption isotherm of HMNPs-GO, it was found that the adsorption of GA by HMNPs-GO was mainly attributed to the π-π accumulation between each other and was refer to Freundlich adsorption. The diffusion mechanism and release kinetics of GA in HMNPs-GO were studied based on Bhaskar model, quasi-level, and quasi-second-order kinetic model, respectively. The release of GA showed a pH dependence in HMNPs-GO, and the sustained release at different pH followed the quasi-second-order dynamics model.
Effects of Pump Chamber and Wear Ring on Simulation Error of Miniature Super-low Specific Speed Centrifugal Pump
Jin ZHOU, Gai-lan XING, Shao-ping ZHOU
, doi: 10.14135/j.cnki.1006-3080.2018121101
[Abstract](4494) [FullText HTML](992) [PDF 1424KB](1)
Abstract:
The cost of numerical simulation can be reduced by properly simplifying the physical model of the pumps, but unreasonable simplification may lead to lager simulation error. In order to study the effects of pump chamber and wear ring on simulation error of a miniature super-low specific speed centrifugal pump, numerical simulation had been carried out by Fluent based on the whole flow field model and non-whole flow field model. To verify the accuracy of numerical simulation, the external characteristic experiment also had been carried out on a miniature pump special test rig. The causes of simulation error were analyzed by comparing the simulation results with the experiment results. It is observed that the simulation error of the whole flow field model is 11.6% lower than that of the non-whole flow field model. The whole flow field model can simulate the hump phenomenon of head curve, the jet-wake phenomenon at impeller outlet and the asymmetric flow field distribution in volute. The non-whole flow field model cannot simulate the disk friction loss in pump chamber, which leads to a large error in power and efficiency simulation. The non-whole flow field model cannot simulate the leakage from wear ring, which makes the simulation value of the fluxes through impeller lower than the actual value, resulting in a large error in internal flow distribution simulation.
Removal of Ca2+ And Mg2+ from Dilute Hydrochloric Acid by Nanofiltration Membrane
Qiuhua CUI, Zhenliang XU, Helin PAN, Shuting LI, Yuwei YE
, doi: 10.14135/j.cnki.1006-3080.20181128001
[Abstract](3874) [FullText HTML](1084) [PDF 929KB](3)
Abstract:
In order to solve the problem of social resource recovery and environmental protection pressure at present, the diluted hydrochloric acid containing calcium and magnesium ions is treated by the NF technique to realize the reuse of the diluted hydrochloric acid. The effects of process conditions such as operation time, salt content, salt species, metal ion contaning ratio, operating pressure, flow rate and liquid temperature on Ca2+ and Mg2+ ion removal rate and membrane flux were discussed. At the same time, the performance of single-component and two-component inorganic salt pure water solutions and acidic solutions were compared, and the effects of Ca2+ and Mg2+ ion removal were studied. The results showed that the removal rate of Ca2+ was 80~90% and Mg2+ was 90~100% in the 3% dilute hydrochloric acid solutions with salt content of 300 ppm, 2 000 ppm and 3 000 ppm. Nanofiltration membrane suitable operating conditions for the pressure of 0.4 Mpa, temperature 30 ℃, the maximum flow 396 L/h. Compared with aqueous solution at the same time, acidic conditions more effictive to Ca2+ and Mg2+removal, and increase about 25%. Therefore, the nanofiltration membrane can be applied to the purification and reuse of acid solution.
Core/shell-Structured Fe3O4@C/PVDF Flexible Films with Improved Dielectric Properties
Qiang LIU, Jun QIAN, Zhipeng CHENG, Wenjuan KOU, Qixin ZHUANG
, doi: 10.14135/j.cnki.1006-3080.20190218002
[Abstract](5013) [FullText HTML](1290) [PDF 1920KB](3)
Abstract:
The carbon shell was coated on the surface of ferroferric oxide via high temperature carbonization to form the core-shell structure of Fe3O4@C. Compared with the single structured filler particles, the core-shell structure of Fe3O4@C was more uniform and more compatible with the organic matrix. Thus, the Fe3O4@C/PVDF flexible film with high dielectric constant and low dielectric loss was obtained. Carbon shell plays a key role in improving the dielectric properties of materials. The carbon shell can not only be used as a transition layer between the Fe3O4 core and the PVDF matrix, but also strengthen the interfacial polarization of the material. The improvement of the dielectric properties of the materials is mainly based on percolation theory and interfacial polarization theory. According to the experiment, the percolation threshold of Fe3O4@C was 12%. During the experiment, it is necessary to accurately control the amount of added filler. At this packing ratio, the film was filled with countless microcapacitors and the dielectric constant of the material was increased rapidly. At the same time, the interfacial polarization of the electric dipole between different interfaces further enhanced the dielectric properties of the material. Compared with pure PVDF, Carbon Fiber/PVDF and GO/PVDF, the Fe3O4@C/PVDF flexible film prepared in this paper has a higher dielectric constant of 115 (normal temperature, 1 kHz) and lower dielectric loss of 0.063. Meanwhile, compared with pure PVDF, its tensile strength was increased from 42.3 MPa to 76.6 MPa, and the Young's modulus was increased from 1.3 GPa to 2.0 GPa. Thus, the prepared materials can be used as a flexible film with high dielectric in electronic components and other fields.
Approximation Algorithm of Arrangement Graph Reliability in Parallel System
Zhongbao Yu, Fangming Shao
, doi: 10.14135/j.cnki.1006-3080.20180531001
[Abstract](3655) [FullText HTML](339) [PDF 617KB](4)
Abstract:
In parallel system, the arrangement graphs An,k has good properties such as symmetry, small diameter, and high fault tolerance. Subsystem reliability is defined as the probability that there is still a normal operating subsystem when the system has faults. It is usually used to measure the system health status, and the calculation of subsystem reliability is an NP-hard problem. This paper discusses the robustness of the reliability of the subgraphs and the approximate algorithm of reliability. Further, the Monte Carlo algorithm for arrangement graphs is constructed. The simulation results show that the constructed Monte Carlo algorithm is much better than the known approximation algorithm. In particular, the error of Monte Carlo approximation of A3,2 subgraph reliability is less than 1%.
Influence of Polyvinylpyrrolidone with Different Molecular Weights on the Dispersion of Multiwalled Carbon Nanotubes
Xu SHANG, Xiwei JING, Jian XU, Baicun ZHENG, Weiguang GONG
, doi: 10.14135/j.cnki.1006-3080.20180820002
[Abstract](7652) [FullText HTML](1437) [PDF 1131KB](13)
Abstract:
The influences of PVP with different molecular weights on the rheological properties and stability of multi-walled carbon nanotubes (MWCNTs) slurry and the electrical conductivity of modified MWCNTs (P-MWCNTs) were systemically investigated with the aim to elucidating the governing dispersing mechanism. The results showed that the PVP with medium molecular weights (PVPK25 and PVPK30) made the MWCNTs disperse uniformly, and the MWCNTs particle size was 190 nm. As a result, the MWCNTs slurry showed lower viscosity and better stability, which led the slurry to evolving from shear-thinning fluid to nearly Newtonian fluid. Moreover, the P-MWCNTs modified by PVPK25 and PVPK30 also displayed lower electrical conductivity, to be 1/100 of the original carbon nanotube. The mechanism of adsorption of PVP on MWCNTs was investigated by Raman, TG and SEM. It was found that the wavenumber migration of the G peak was 10 cm−1, and the 2D was 5 cm−1, indicating that PVP with medium molecular weights had stronger π-π interaction with MWCNTs. The adsorption amount of PVPK25 and PVPK30 were higher than that of low molecular weights (PVPK17) and high molecular weights (PVPK90) which can generate stronger steric hindrance repulsive force. SEM results directly indicated that the MWCNTs modified by PVPK30 were dispersed homogenously, while some MWCNTs aggregates were observed for the samples modified by PVPK17 and PVPK90. The dispersion of MWCNTs was ascribed to the π-π interaction and the adsorption amount, leading to that the PVP with moderate molecular weights presented the best dispersibility. This study can not only further the understanding of the influences of PVP molecular weights on the dispersion behavior of carbon nanotubes, but also provide guidance for preparing conductive slurry composed of carbon nanotube.
Numerical Simulation in Premixed High-Speed Jet Flame Reactor
Dongying CAI, Yuelin WANG, Xianjian DUAN, Dan HU, Yubing LI, Yanjie HU
, doi: 10.14135/j.cnki.1006-3080.20190221004
[Abstract](4376) [FullText HTML](1244) [PDF 843KB](1)
Abstract:
Gas phase combustion synthesis technology is a well-known chemical manufacturing technique for preparing nanomaterials. Nevertheless, the chemical reaction of precursors and nucleation, growth, sintering, agglomeration of the nanoparticles makes the whole combustion reaction zone be complicated. Flame chamber is the core equipment, and the structure affects the flow field parameters, ultimately determining the morphologies, structures and properties of the final products. In this work, three-dimensional geometric models of premixed high-speed jet flame reactors were developed, the combustion simulations were carried out using realize k-ε turbulence model, Eddy Dissipation Concept (EDC), discrete phase model. Additionally, a 19-step detailed reaction mechanism of H2 was used for the temperature profile, velocity field and the particles residence time in high-temperature region. The effects of temperature, velocity and the reaction rate of H2 combustion under different outlet diameters of the burner center duct were systematically investigated. The simulation results indicate that increasing the diameter of the outlet of burner center duct leads to significant increase in the length of the high temperature region, and the attenuation of the central jet velocity drops off in the different scales of flame reactors. SiO2 nanoparticles were selected as discrete source in different scales of flame reactor, as well as for the study of residence time and backmixing in high temperature flame region. The results show that the residence time of the nanoparticles in the high temperature flame region is obviously increased, and the back-mixing phenomenon is aggravated. Together with the calculations, these results supply useful references for regulation and control of nucleation growth process of nanoparticles and provide theoretical fundamentals for industrial flame reactor design.
An Approximation Algorithm for The Parallel Three-Stage Flowshop Scheduling
Yi-lin CAO, Wei YU
, doi: 10.14135/j.cnki.1006-3080.20180206001
[Abstract](4886) [FullText HTML](1503) [PDF 595KB](2)
Abstract:
In this paper, we study the problem that schedules n three-stage jobs on m three-stage flowshops with the objective of minimizing the makespan. When m is fixed, the problem is NP-hard; When m is arbitrary larger than 2, the problem is strongly NP-hard. For this problem, the present work is divided into three situations for discussion: in case one, we gave an approximate ratio of (7/3-1/3m); in case two, we gave an approximate ratio of three; while in case three, there was an approximate ratio of (23/6-1/3m); finaly we gave an approximation algorithm with a worst case ratio of (23/6-1/3m)
Macroscopic Photo-Responsive Behaviors of Self-assemblies Constructed by Photo-Responsive Small Molecules and Surfactants
Jie SHUAI, Jiajie HU, Yan TU, Yazhuo SHANG, HongLai LIU
, doi: 10.14135/j.cnki.1006-3080.20190821001
[Abstract](4280) [FullText HTML](880) [PDF 1448KB](2)
Abstract:
In this paper, halogen-free surface active ionic liquid (SAIL), 1-butyl-3-methylimidazolium alkyl sulfate ([C4mim][C12SO4]), was synthesized through ion exchange reaction. The photo responsive system of Gemini12-3-12/[C4mim][C12SO4]/trans-OMCA/H2O was constructed by mixing [C4mim][C12SO4] and Gemini surfactant 12-3-12·2Br- (Gemini12-3-12) together and introduce photosensitive molecules trans-o-methoxy cinnamate (trans-OMCA) at the same time. The photo-responsive behaviors of aqueous two-phase system (ATPS), specific single-phase system and anisotropic phase system in Gemini12-3-12/[C4mim][C12SO4]/trans-OMCA/H2O mixed system have been studied by TEM, UV-vis and dynamic light scattering (DLS). The results have shown that the mixed system displays good photo responsiveness. For the aqueous two-phase system in which spherical micelle and wormlike micelle coexist, UV irradiation for a certain period of time will promote the fusion of spherical micelle phase and wormlike micelle phase into a single wormlike micelle phase. For the single-phase vesicle system, it will be separated into a two-phase system of spherical micelle and wormlike micelle after UV irradiation for a certain period of time, and the system will gradually merge into a single wormlike micelle phase after prolonging the UV irradiation time. The anisotropic system will turn into isotropic one after a certain time of UV irradiation. It is obvious that the macro phase behaviors of the system can be tuned by UV irradiation and the system realizes the photo induced phase separation and photo induced phase combination.
A New Method Based on Scaled Particle Swarm Optimisation to Reduce the PAPR of FBMC System
Tong WENG, Weina YUAN
, doi: 10.14135/j.cnki.1006-3080.20190731002
[Abstract](4298) [FullText HTML](1043) [PDF 840KB](1)
Abstract:
Partial transfer sequence (PTS) is one of the effective methods for filter bank multicarrier (FBMC) to reduce peak-to-average power ratio (PAPR). However, PTS method selects the optimal phase factor by exhaustive search, there is a high computational complexity. In order to overcome this shortcoming, this paper presents a new method based on PTS method. First, This method proposes an odd-partial transfer sequence(OPTS) segmentation method based on the traditional PTS segmentation method, this method uses staggered segmentation method for odd subblocks and random segmentation method for even subblocks, the method combines the advantages of staggered segmentation and random segmentation, not only improves the PAPR performance of the system, but also reduces the computational complexity. Second, this paper proposes a scaled particle swarm optimization (SPSO) algorithm, which introduces the scaling factor into the traditional PSO algorithm. The existing particle swarm optimization (PSO) algorithm has a slow convergence rate in the iteration process, and is prone to fall into local optimal in high-dimensional space, which also has the problem of particle optimization. The main goal of the proposed PSO algorithm is to use the scaling factor to control the particle speed, and to obtain good PAPR performance with lower computational complexity and faster convergence speed. The addition of SPSO algorithm on the basis of OPTS will slightly increase PAPR value, but have better performance in terms of complexity and significantly improve the spectrum utilization. Simulation results show the effectiveness of the new method.
Combinational Photodynamic Therapy and Chemotherapy Based on an Amphiphilic pH-Responsive Porphyrin-Containing Block Copolymer
Chao XIAO, Jia TIAN, Feng LIU, Xianyang Zhang, Tinghu Wang, Liren Xv, Hansha Gu, Weian ZHANG
, doi: 10.14135/j.cnki.1006-3080.20190128001
[Abstract](4655) [FullText HTML](1612) [PDF 1192KB](2)
Abstract:
Nowadays, photodynamic therapy (PDT) has become one of the promising and important cancer therapies. 5, 10, 15, 20-Tetraphenyl porphyrin (TPP) is a unique and promising photosensitizer which can convert triplet oxygen (3O2) into singlet oxygen (1O2) after laser illumination, which can be used to kill cancer cells. Due to the strong hydrophobicity of porphyrin molecules, porphyrins always need the physical encapsulation by different vehicles. However, the general physical encapsulation not only makes it difficult to quantify the loaded porphyrin content accurately, but also causes aggregation effects after the intracellular release, leading to a compromised PDT effect. Herein, we developed a NIR-triggered pH-responsive amphiphilic block copolymer as to serve as photosensitizer and drug delivery system (DDS) for the combination of PDT therapy and chemotherapy. The well-defined block copolymer was composed of hydrophilic poly (ethylene glycol) (PEG) block, hydrophobic poly((diisopropylamino)ethyl methacrylate) (PDPA) block and a TPP unit at the junction point between PEG and PDPA. Such a copolymer was synthesized by the combination of RAFT polymerization and click chemistry. The amphiphilic pH-responsive block copolymer (PEG-PDPA-TPP) can self-assemble into spherical micelles in aqueous solution and perform as a perfect drug release platform. It is worthy to notice that the well-designed chemical structure of PEG-PDPA-TPP with TPP at the junction point leads to a relatively regular arrangement of TPP moieties between the hydrophobic and hydrophilic blocks instead of aggregating together, which can reduce the aggregation-induced quenching effect of the photosensitizers, thereby increasing the quantum yield of singlet oxygen. Meanwhile, the Doxorubicin (DOX)-loaded PEG-PDPA-TPP nanoparticles will dissociate under weak acidic conditions and release the drug after entering the cells by endocytosis. Therefore, this pH-responsive TPP-containing block copolymer provides a new strategy for cancer treatment.
Preparation of Manganese Oxide Coating Zeolite Catalyst for Catalytic Oxidation of Toluene
Feiyang DING, Yuan XUE, Ling ZHANG, Chunzhong LI
, doi: 10.14135/j.cnki.1006-3080.20190329002
[Abstract](5756) [FullText HTML](1361) [PDF 772KB](10)
Abstract:
Volatile organic compounds (VOCs), which include benzene, toluene and xylene, are harmful to both human health and the environment. It is important to control and reduce the release of VOCs. Transition-metal oxides have been widely studied due to their low cost and relative high activity for catalyzing VOCs. In this work, manganese oxide was used to coat zeolite molecular sieve, producing the composite by a one-step redox reaction between potassium permanganate and manganese nitrate. By introducing a template agent, the reaction temperature and concentration are optimized to modulate the structure and properties of manganese oxide, producing a layered porous structure that sets free the pore of the zeolite molecular sieve thoroughly. The large special surface area of zeolite molecular sieve facilitates the adsorption of VOCs and the manganese oxide coating promotes the catalytic oxidation of VOCs. Our results show that the use of different reaction temperature and catalyst concentration leads to a change of the morphology of manganese oxide the specific surface area of the composite, the ratio of lattice oxygen to adsorbed oxygen. And the Mn3+/Mn4+ ratio in manganese oxide catalyst. The special surface area of the composite, coating amount, the ratio of lattice oxygen to adsorbed oxygen and Mn3+/Mn4+ together impact the catalytic performance of the composite. An appropriate amount of manganese oxide coated molecular sieve catalyst prepared under ice bath shows the best catalytic performance for toluene (200 ppm); the toluene conversion reaches 90% at 256 °C.
Influence of Epoxidized Ethylene Propylene Diene Rubber on Nonisothermal Crystallization Kinetics of PBT/GF Composite
Bo LIU, Meng jingzi ZONG, Zhi hong LIU, Wei WU
, doi: 10.14135/j.cnki.1006-3080.20190116004
[Abstract](4412) [FullText HTML](1429) [PDF 994KB](1)
Abstract:
Poly(butylene terephthalate) (PBT), a semicrystalline polymer belonging to polyester family, is widely used in engineering applications due to its versatile combination of mechanical and thermal properties, chemical resistance, and high rates of crystallization. The physical and mechanical properties of the product are directly related to the microstructure, which is determined by the extent of crystallization and influenced by the nonisothermal conditions set forth during practical processing. Therefore, the nonisothermal crystallization kinetics can be used to clarify the crystallization behavior and provide a theoretical basis for the formation of crystals. In this paper, the epoxidized ethylene propylene diene rubber (eEPDM) was first successfully prepared by the epoxidation of ethylene propylene diene rubber (EPDM) using t-butyl hydroperoxide as an oxidant and molybdenum oxide as a catalyst. The resulting rubber was characterized by fourier transform infrared spectroscopy (FT-IR) and 1H-nuclear magnetic resonance (1H-NMR). Then the PBT/Glass fiber (GF)/eEPDM composites with different eEPDM contents were prepared in a twin-screw extruder. The influence of eEPDM on the nonisothermal crystallization kinetics of PBT/GF was investigated using differential scanning calorimetry (DSC). The phase structure of PBT/GF/eEPDM was observed by scanning electron microscopy (SEM). Analysis of the crystallization data by Mozhishen model revealed that the presence of eEPDM could accelerate the nonisothermal crystallization rate of PBT in PBT/GF/eEPDM. The result was further proved by the effective activation energy calculated by Friedman method. The observation of SEM demonstrated that the interface performance was excellent between PBT, GF and eEPDM phases. Meanwhile, the mechanical properties of the specimens were evaluated.
Computer Simulation on Drug Loading Efficiency of Polymeric Prodrug
Xueli LUO, Meidong LANG
, doi: 10.14135/j.cnki.1006-3080.20190514001
[Abstract](4433) [FullText HTML](1085) [PDF 1340KB](2)
Abstract:
In order to explore the relationship between drug grafting ratio of polymeric prodrug and its drug loading efficiency, a model of polymeric prodrug: methoxy poly(ethylene glycol)-b-poly(ε-caprolactone-co-piperilactone-g-5-aminolevulinic acid) (mPEG-b-P(CL-co-APIL)) was designed. This polymeric prodrug was used as drug carrier of 5-Aminolevulinic acid (5-ALA), it would load drug both by method of chemical bonding and physical embedding. Molecular dynamics (MD) was utilized to calculate the compatibility of polymeric prodrug with 5-Aminolevulinic acid and H2O, and to predict the relationship between drug grafting ratio and drug loading. During the process of calculation, the Flory-Huggins interactional parameter was decomposed into van der Waals force components and electrostatic force components, so that the effect of 5-ALA grafting ratio on the polymeric prodrug carrier was analyzed. The dissipative particle dynamics simulation (DPD) was used to explore and observe the morphology of the drug-loaded micelles and observe the concentration state of the drug molecules. Computational simulation results showed that the compatibility between polymeric prodrug and 5-ALA was getting better with the drug grafting increased, so it can predict that the drug loading efficiency of polymeric drug would get better as the drug grafting ratio increases. And the DPD simulation showed that the polymeric prodrug would self-assemble into spherical micelles in H2O.The density distribution of drug molecules showed that the distribution in core of micelle was higher since the drug grafting ratio was higher. All the simulation results indicated that it’s feasible to improve drug loading efficiency by grafting drug molecule. The content of this research can provide some guide for the design and development of drug carriers.
Investigation on Process Characteristics in Hydrothermal Liquefaction of Municipal Sewage Sludge
Yiqiu Zhang, Shiyong Wu, Youqing Wu, Sheng Huang, Jinsheng Gao
, doi: 10.14135/j.cnki.1006-3080.20190107001
[Abstract](4666) [FullText HTML](1133) [PDF 860KB](6)
Abstract:
The effects of reaction temperature on hydrothermal liquefaction (HTL) process of municipal sewage sludge (MSS) and characteristics of liquefied products were investigated. The results showed that the bio-crude yield and asphaltene yield reached to be the highest level at 370 ℃, which were 26.82% and 27.73% respectively. The water recovery ratio and volume reduction ratio were also increased to the maximum value of 94.81% and 80.16%, respectively, indicating that improved effects in volume reduction of MSS were obtained after HTL process. The concentration of water-soluble organics dropped to 29.47 g/L, which demonstrated that higher reaction temperature would promote the decomposition of these water-soluble organics. The bio-crude was mainly composed of aliphatic acids, amines and aliphatic hydrocarbons, and the carbon chain length of aliphatic acids was located in between 16 and 18, which indicated that the properties of bio-crude were similar to that of diesel oil. The water-soluble organics were mainly composed of carboxylic acids, esters, amides and phenols while the existence of carboxylic acids would have detrimental influences on the growth of plants, the availability of soil nutrient and the biodiversity of environment. The gaseous products were mainly consisted of CO2 which could be explained by the decarboxylation taking place on the surface of MSS particles. The ash content of residual solids reached to the highest level (79.72%) at 370 ℃, which showed that a better extraction rate of organic matters in residual solids could be obtained by HTL process. During the HTL process, the energy recovery ratio of liquid bio-fuels was between 53.23 and 98.20% in the temperature range from 270 to 370 ℃, indicating that more than half heating value of the MSS could be recovered to be liquid bio-fuels upon a HTL treatment.
Distributed Optimal Power Flow Analysis of Partitioned Micro-grid Based Multi-agent
Lanping CHEN, Yugang NIU
, doi: 10.14135/j.cnki.1006-3080.20190523004
[Abstract](5018) [FullText HTML](1357) [PDF 852KB](1)
Abstract:
In this paper, a distributed coordination solution control strategy of partitioned micro-grid based multi-agent technology is proposed. The optimal power flow model is constructed by combining the power flow calculation and economic scheduling problems. The complex power system network is partitioned to achieve the balance among regions. The regional control error (ACE) is used to compensate the deviation of the frequency between the areas. Further, the optimal micro-grid power flow problem is solved by optimizing the hierarchical scheduling with two-level agents, i.e. Bus Agent and Regional Agent. Finally, the optimal micro-grid power flow distribution is derived and the safety, stability and economy optimal operation of micro-grid are achieved. It is shown that the multi-agent technology can complete the analysis on optimal power flow of the micro-grid and the distributed method can protect the internal information security of each regional power grid and solve the problem of excessive communication in the centralized optimization.
Deep Learning Based Key Object Detection and Extraction for Driving Scene
Xueqin ZHANG, Yifan WEI
, doi: 10.14135/j.cnki.1006-3080.20181023002
[Abstract](4819) [FullText HTML](1269) [PDF 774KB](10)
Abstract:
Object detection with object recognition and bounding box generation plays an important role in the visual perception of autonomous driving. With the rapid development of deep learning, a series of object detection algorithms based on deep convolution networks have been proposed. These vision-based algorithms have been widely used to deal with driving scenes or other complicated situations. In this paper, a novel detection algorithm, single shot multi-box detector(SSD)based on deep convolution network-visual geometry group network(VGG), is proposed to achieve target recognition, semantic annotation, and bounding box selection in driving scene. Moreover, an improved algorithm, termed as single shot multi-box detector with aspect ratio selection strategy(SSD_ARS), is also proposed for object detection in auto-driving. Momentum optimization is used in the gradient descent algorithm and the learning rate reduction strategy is optimized. Furthermore, the aspect ratio selection strategy is improved when generating the priori box. It is shown from the results on different selection strategies of aspect ratio when generating the priori box that the proposed algorithm in this work can effectively improve the accuracy of object detection, especially, the detection accuracy of small objects. Finally, the detection experiment of 9 significant object classes in the real driving scene is made, from which it is seen that that the proposed algorithm performs well at near and medium distances. Besides, it is also demonstrated via the experiment on driving video that the detection speed of the proposed algorithm in this work can meet the requirements of real-time detection.
Differential Evolution Algorithm with Competition Mechanism for Simultaneous Synthesis of Heat Exchanger Network withNo Split Streams
Peng CHEN, Na LUO
, doi: 10.14135/j.cnki.1006-3080.20181015004
[Abstract](5958) [FullText HTML](1604) [PDF 784KB](3)
Abstract:
Heat exchanger network synthesis is a typical mixed integer nonlinear programming problem with non-convex and nonlinear characteristics, whose optimization easily falls into local optimal. To deal with this difficulty, this paper proposes a differential evolution algorithm with competition mechanism, which is further applied in simultaneous synthesis of heat exchanger network. Firstly, Latin hypercube sampling method is used to generate initial individuals such that the diversity in the space of solutions can be ensured. And then, the competition mechanism is introduced to divide the evolutionary population into two groups, named as winner and loser. For the winner group, the opposition-based random search combined with greedy selection is conducted to achieve deeper optimization. For the loser group, they will learn from winner group to improve their quality. Moreover, an adaptive shrinking factor is introduced into the mutation operation of individuals for improving the global and local optimization. Comparing with other methods, the proposed method in this work can attain a better design of heat exchanger network via lower total annual cost, and can efficiently solve the synthesis problems of medium scale heat exchanger network.
Dynamic Process Quality Monitoring Based on T-TSNPR
Zheng LYU, Jian YANG, Hongbo SHI, Shuai TAN
, doi: 10.14135/j.cnki.1006-3080.20181114003
[Abstract](4856) [FullText HTML](1294) [PDF 859KB](2)
Abstract:
Quality monitoring has been a new research hot topic in recent years. The alarm should be issued only when the product quality is outside the normal range. However, the traditional neighborhood preserving embedding (NPE) may issue alarm to all faults, which inevitably results in lots of downtime and seriously affect the normal production. Aiming at the above problems, this paper proposes a total-time series neighborhood preserving regression (T-TSNPR) modeling approach. Firstly, by considering the influence of unrelated variables on feature extraction, the correlation analysis between process variables and quality variables is performed, and the contribution method is used to select the key variables. Secondly, in order to achieve the dimensionality reduction in dynamic process, the neighborhoods within certain timeframe are selected to constructs the localized constraining relationship between neighborhoods such that the quality-related information can be extracted through total projection regression. Thirdly, Hotelling’s T2 statistic is established for online quality monitoring. Finally, a numerical example and the Tennessee-Eastman Process are provided to verify the effectiveness of the proposed T-TSNPR algorithm.
Effect of Propargyloxy Side Groups on the Cure Reaction and Properties of Novolac-Type Cyanate Ester
Qian XU, Qiaolong YUAN, Farong HUANG
, doi: 10.14135/j.cnki.1006-3080.20190321004
[Abstract](6557) [FullText HTML](1717) [PDF 1834KB](7)
Abstract:
p-Propargyloxyphenyl side groups were grafted to the backbone of novolac-type cyanate ester (NCE) by diazo coupling reaction to obtain a new novolac resin (PPANC) with cyanate ester and propargyloxyphenyl side groups. The resins were characterized by 1H-NMR, FT-IR, UV-Vis and size exclusion chromatography (SEC). The thermal cure reaction of PPANC was studied by differential scanning calorimetry (DSC) and in situ monitoring Fourier-transition infrared. Furthermore, quartz fabrics (QF) reinforced PPANC composites were also molded using hot-press process. The thermal stability of the resins and the mechanical and dielectric properties of the composites were also studied. The results showed that the propargyloxyphenyl side groups in the prepared PPANC could promote the curing reaction of cyanate ester groups attached on NCE as facilitated by the acidic hydrogen of the terminal alkynyl groups. The curing temperature of the NCE resins decreased with the introduction of the propargyloxyphenyl groups, and further decreased with increase of the propargyloxyphenyl content. The thermal stability of the cured PPANC resins in nitrogen decreased with increase of the propargyloxyphenyl content. However, the temperature at 5% mass loss of the cured PPANC resins retained higher than 400 °C. The PPANC resin with a moderate propargyloxyphenyl content was reinforced by QF to form the composite which showed higher mechanical properties and lower dielectric properties than those of the composites of NCE and PPANC matrices. The flexural strength and modulus, and interlayer shear strength (SILS) of the QF/PPANC composite could reach 612 MPa and 26 GPa, and 52 MPa, respectively. The glass transition temperature of the QF/PPANC composites and QF/NCE composite were higher than 350 ℃. The dielectric constant and dissipation of the QF/PPANC composites were lower than 3.6 and 0.004, respectively. These values are lower than those of the QF/NCE composite in the frequency range of 1~106 Hz.
Analysis of Multi-scale Turbulent Mixing Character of Cracking Coil with Twisted Tape
Dehong BAI, Yuan ZONG, Ling ZHAO
, doi: 10.14135/j.cnki.1006-3080.20190315003
[Abstract](6647) [FullText HTML](1461) [PDF 1289KB](3)
Abstract:
Turbulent mixing enhancement of twisted tape for cracking process was studied. Meso- and micro-scale mixing performance was analyzed to reveal the close relationship between turbulent mixing and cracking reaction. Research method of computational fluid dynamics was used to conduct contrast simulations between bare coil and coil with twisted tape to present variations of transfer and cracking reaction characteristics. The simulation results show that by paying 5.31% more pressure drop than bare coil, turbulent kinetic energy at the ratio of axial distance to total length Z/L=0.228 in the downstream of twisted tape is increased by 39.6% while the overall averaged characteristic micro-mixing time is reduced to 1.72% of bare coil, indicating an effective meso- and micro-mixing enhancement. The intensified turbulent mixing promotes the uniformity of field profiles to improve synergy among temperature, species concentration and velocity distributions, resulting in enhanced heat and mass transfer performance. The Nu and Sh of cracking coil installed twisted tape are increased by 7.50% and 2.34% respectively compared with bare coil. While the overall olefin yield is improved by 5.88% and the averaged coil skin temperature is reduced by 24.01 K. The coking suppression effect can be attributed to the strong swirling flow induced by twisted tape, generating radial velocity component to accelerate fluid in the wall vicinity. Consequently, the residence time of fluid in the near wall region at the ratio of radial distance to cracking coil radius r/R=0.993 can be reduced by 53.01%. Furthermore, the enhanced turbulent mixing results in more homogenous radial field profiles, enlarging the molecular scale uniform mixed region by 5.29% to extend reactive zone, which is beneficial for olefin yield improvement.
Selectivity Towards β-Me Elimination of Metallocene Catalysts in Catalytic Propylene Polymerization
Lingyun XIAO, Haiyan MA
, doi: 10.14135/j.cnki.1006-3080.20190329005
[Abstract](5491) [FullText HTML](1399) [PDF 861KB](5)
Abstract:
In propylene polymerization catalyzed by transition metal complexes, chain transfer reactions exert crucial influence on the structures of terminal groups as well as molecular weights of the resultant polymers. Among the known chain transfer reactions, β-Methyl elimination (β-Me elimination) could lead to the production of ally-terminated polymer chain selectively, thus attracts great attention. Up to data, it is still a great challenge to achieve high β-Me elimination selectivity systematically during propylene polymerization process. In this work, a series of ethylene-bridged indenyl-fluorenyl complexes, {C2H4(5,6-cyclopenta-Ind)(Flu)}ZrCl2(C1), {C2H4 (5,6-cyclopenta-Ind)(2,7-tBu2-Flu)}ZrCl2(C2), {C2H4(3-Bn-5,6-cyclopenta-Ind) (2,7-tBu2-Flu)}ZrCl2(C3), {C2H4 (3-Bn-5,6-cyclopenta-Ind)(2,7-tBu2-Flu)}HfCl2(C4), were synthesized and characterized. Upon activation with methylaluminoxane (MAO), these complexes could catalyze the polymerization of propylene with moderate to high activities to produce propene oligomers or polymers with vinylidene or allyl-dominant chain ends. Complex C3 bearing a benzyl group at the 3- position of the indenyl ring showed significantly higher β-Me elimination selectivities (80-83%) at 40-100°C than the other zirconocene complexes C1 and C2, and meanwhile led to the formation of propene oligomers with significantly lower molecular weights than those obtained by the other zirconocene complexes (Mn = 800~3600), suggesting that the dominant β-Me elimination chain transfermode led to the decrease of molecular weights of resultant polymeric products. The hafnocene complex C4 also showed the highest β-Me elimination selectivity among these complexes (87%), however its activity were very low.
Facial Action Unit Recognition Algorithm Based on Deep Learning
Dexun WANG, Huiqun YU, Guisheng FAN
, doi: 10.14135/j.cnki.1006-3080.20190107003
[Abstract](4820) [FullText HTML](1499) [PDF 681KB](4)
Abstract:
Facial action unit recognition task is one of the most important aspects of understanding facial expressions, but because of the extremely unbalanced categories and the multi-label classification, it brings great difficulties to the algorithm design. In this paper, a face action unit recognition algorithm based on deep learning is designed for these problems. Firstly, based on the transfer learning theory and driven by the task of face recognition, some large-scale datasets are used to pre-train the convolutional network, making the model have the ability to extract abstract features of a face. Secondly, an objective function is designed to dynamically weigh the sample loss according to classification confidence, which makes the model focus more on optimizing the majority class. Finally, two related tasks including the multi-label co-occurrence relationship fitting and the face key-point regression are combined to jointly train the model and test it. The experimental results show that the proposed method can effectively improve the classification accuracy and F1-score on the relevant datasets CK+ and MMI.
Robust Extreme Learning Machine Based on p-Power Welsch Loss
Jianting CHEN, Zhencheng YE, Hui CHENG
, doi: 10.14135/j.cnki.1006-3080.20181209001
[Abstract](5151) [FullText HTML](1385) [PDF 1015KB](1)
Abstract:
Aiming at the problem that the conventional extreme learning machine (ELM) is sensitive to outliers, a robust extreme learning machine based on p-power Welsch loss is presented. The highlights of this proposed method are reflected in the following three aspects: Firstly the mean square error loss of the conventional ELM is replaced by the p-power Welsch loss, which improves the robustness of the algorithm. Secondly, l1 norm regularization is introduced into the objective function to reduce the complexity and improve the stability of the ELM network model. Finally a fast iterative shrinkage-thresholding algorithm (FISTA) is adopted to minimize the objective function, which improves the computational efficiency of the method. Performance comparisons of the method are presented using synthetic data and UCI datasets. The experimental results show that the proposed algorithm produces better robustness, better stability and lower training time.
Fume Hood Window State Recognition Method Based on Few Shot Deep Learning
Zhenwei MA, Gaoqi HE, Yubo YUAN
, doi: 10.14135/j.cnki.1006-3080.20190412004
[Abstract](4588) [FullText HTML](1096) [PDF 801KB](3)
Abstract:
In the chemical laboratory, the laboratory staff often forget to close the fume hood window in time when they leave, which cause potential safety hazards and waste of energy. Therefore, it is necessary to develop a methodology for fume hood window safety management. To the best of our knowledge, the related research about window state recognition is mainly through various electronic control systems but not suitable for fume hood window. In this paper, a novel method is proposed for fume hood window safety management based on computer vision with the advantages of non-contact and easy expansibility. First, the surveillance videos are preprocessed and fume hood window areas are extracted based on motion features and geometric priority, which can effectively reduce the influence of irrelevant area on window state recognition. Since there is no existing data set and limited by the number of fume hood windows in the laboratory, a new data set containing 400 window images are constructed. Then a new fume hood window state recognition method is proposed based on few-shot learning. Compared with the traditional few-shot learning dataset, fume hood window images have higher resolution which makes it difficult to extract effective features. To overcome this significant challenge, dilation convolution is applied to enlarge receptive field and inception layer with multi-scale dilation rate is constructed instead of traditional convolution layer. In order to avoid invalid window state detection when staff are in the laboratory, the moving foreground region extracted from the Gauss mixture model is used as the prior region of Yolov3(You only look once version 3) target detection which can reduce the occurrence of error staff recognition. In the experiment, the traditional machine learning algorithm and CNN(convolutional neural network) are selected as the comparison of proposed method. LBP(local binary pattern), PCA(principal component analysis), ColorHist(histogram of color) and HOG(histogram of oriented gradient) are selected as the features of machine learning methods from the aspects of texture, dimension reduction, color and shape. The experimental results show that the proposed method achieves 99.29% accuracy under normal illumination conditions, 17.20% higher than the best traditional HOG combined with Randomforest method and 10.95% higher than the convolution neural network. Under the condition of illumination change, the accuracy rate is 95.74%, which is less changed than that under normal illumination.
Emotion Recognition Algorithm Based on Temporal Convolution Network
Zhenzhen SONG, Lanlan CHEN, Xiaoguang LOU
, doi: 10.14135/j.cnki.1006-3080.20190508001
[Abstract](5117) [FullText HTML](1515) [PDF 913KB](3)
Abstract:
This paper uses EEG dataset DEAP for emotion recognition. Considering the time sequence characteristics of EEG signals, Temporal Convolution Network (TCN) is adopted as a deep learning approach to train and identify EEG data. TCN model is not only can grasp the characteristics of time series but also retain the parallel computing property of CNN, which could improve the computational efficiency while maintaining high identification accuracy. Firstly, wavelet packet transform is employed to decompose the raw signals into sub-frequency bands and then wavelet coefficient energy value are computed as the features. Wavelet packet analysis is an extension of wavelet analysis, the basic idea of which is to concentrate the information energy, find the order in the details, and filter out the rules to provide a more sophisticated analysis method for the signal. Then the extracted features are trained through the TCN network and Snapshot optimization idea is applied to save multiple models during the process of training. The principle of Snapshot optimization is to avoid local pole values by constantly resetting the learning rate. Finally, ensemble learning with the voting integration strategy is implemented to combine multiple machine learning models into an integrated model in order to improve recognition accuracy and enhance the robustness of the results. The experimental results show that the proposed method could achieve an average recognition accuracy of 95% and 93% for two-category and four-category identification tasks respectively, which presents a significant improvement compared with similar research and proves the feasibility and practicability of the proposed method.
A Reverse Learning Behavior Particle Swarm Optimization for Large-Scale Task Scheduling in Cloud Computing Environment
Zhaolin LAI, Xiang FENG, Huiqun YU
, doi: 10.14135/j.cnki.1006-3080.20190218001
[Abstract](5147) [FullText HTML](1507) [PDF 1044KB](10)
Abstract:
Aiming at the problem that traditional intelligent optimization algorithms are easy to fall into local optimal and premature convergence when solving the cloud computing task scheduling, a reverse learning behavior particle swarm optimization algorithm (RLPSO) is proposed in this paper. Firstly, a grouping strategy is used to divide the individuals into two different groups according to the gender of individuals, and the individuals in different groups perform different search behaviors. Such strategy increases the diversity of search mode, and it can help to enhance the search ability of the RLPSO algorithm. Secondly, the reverse learning mechanism and the mating mechanism are introduced to avoid the RLPSO algorithm falling into local optimum. For the reverse learning mechanism, individuals will reversely learn from the target individuals with a certain probability, and it increases the ability of algorithm to find a new potential better solution. For the mating mechanism, the worst individual in the swarm will be replaced by a new better individual, and the global search ability can be further enhanced. Thirdly, the convergence of the RLPSO algorithm is discussed in detail. We can prove that the RLPSO algorithm will converge to an equilibrium. Finally, the effectiveness of the RLPSO algorithm is validated by simulating. Moreover, the performance of the RLPSO algorithm is compared with four intelligent optimization algorithms which are light search algorithm (LSA), ant colony optimization algorithm (ACO), particle swarm optimization algorithm (PSO), and genetic algorithm (GA), respectively. The experimental results show that, the RLPSO algorithm exhibits better search performance than the four comparison algorithms in the problem of the total completion time of large-scale task scheduling.
Strawberry Image Segmentation Based on Deeply Supervised Saliency Detection
Wenxiu QIAN, Qing CHANG, Hui XIANG, Wenbin KANG
, doi: 10.14135/j.cnki.1006-3080.20181205004
[Abstract](5174) [FullText HTML](1549) [PDF 1054KB](16)
Abstract:
The development of strawberry picking robot and the information of strawberry growth status play an important role in the process of automated strawberry planting. The segmentation effect of strawberry image directly affects the real-time operation of strawberry picking robot and strawberry growth state analysis. This requires that the strawberry segmentation algorithm needs to be applied to different light and dark environments and has a good segmentation effect on strawberries of different maturity. Most of the current strawberry image segmentation algorithms study the segmentation of fixed background or fully mature strawberry objects, and it is impossible to achieve multi-level classification and covered detection of strawberries. In this paper, a strawberry image segmentation method combining salient region detection is proposed. Firstly, the contrast-limited adaptive histogram equalization processing method is used to increase the contrast between strawberry and background under different light intensities. Then, using the Holistically-Nested salient object detection with short connections algorithm, significant advantage of regional calibration based on thinning results of deep side output and detail advantage of shallow side output, resulting in dense and accurate salient areas. Finally, the salient area marks the foreground and background mask of the Grabcut, so as to achieve accurate segmentation of the strawberry image. The experimental data and analysis show that the strawberry with different maturity under different light and dark environments can obtain stable and accurate segmentation results.
Following Controller for Autonomous Vehicle Platooning
Qi YANG, Shirong LIU
, doi: 10.14135/j.cnki.1006-3080.20190118001
[Abstract](5485) [FullText HTML](1869) [PDF 1316KB](9)
Abstract:
In this paper, two types of vehicle platoon following controllers are designed according to the situation that the communication between vehicles is normal or is interrupted in the process of running. Laser range finder and monocular camera are used as vehicle sensors to collect information. Firstly, the physical characteristic information of obstacles in the environment is collected from the laser sensor. The DBSCAN algorithm is used for clustering the data obtained from laser sensor. The clustering result of obstacles in the environment is fitted to the physical shape with a minimum circumscribed rectangle, and the center point of which is taken as the center of each obstacle. Then the angle of the leader vehicle is obtained from visual sensor. The color distribution information of the preceding vehicle is pre-defined. So the Camshift algorithm can be used for calculating the relative angle between the preceding and the following vehicle in each frame of the picture. Finally, the information collected by two kinds of sensors is merged for the controller design. According to whether there is communication between the leader and follower or not, the paper proposes two different controllers based on Lyapunov function and fuzzy control logic respectively. When the communication between vehicles is normal, the Lyapunov-based controller design will be used. When there is no communication between vehicles, the controller based on fuzzy control strategy will be selected. If the vehicle does not resume communication within a certain period of time, it will move to a safety area waiting for repair. The validity of the proposed algorithms is confirmed by theoretical derivation and simulation in robot operating system (ROS).
Multi-feature Non-contact Deception Detection Technology
Jiangping WEI, Jiajun LIN, Ning CHEN
, doi: 10.14135/j.cnki.1006-3080.20190619002
[Abstract](4735) [FullText HTML](1383) [PDF 827KB](5)
Abstract:
The non-contact deception detection technology is of great significance in areas such as judicial. In order to improve the accuracy of deception detection model, this paper proposes a deception detection model based on multimodal fusion. With the support of this model, we only need to process the video and audio signals of the speaker to effectively complete the deception detection evaluation task. The heart rate reflects the emotional changes of the liar. We extract the feature of heart rate by the Photo-plethysmography method and the fully connected network. The video and text features are extracted through 3D-convolutional neural networks and Word2Vec+CNN, then these features are merged. The linear support vector machines are used to classify the fused features. The simulation experiment was carried out on the open source Real-life Trial dataset. Compared with the latest MLPH+C multi-modal model, the accuracy of the deception detection model proposed in this paper increased by 2.74%-23% in the three-mode. In order to evaluate whether the combination of different modal features can improve the performance of the deception detection model, we use the combination of features of each modality to conduct experiments. The accuracy of each category combination is over 70%.And the combination of text and heart rate features is 96.89%, especially the combination of text, video and heart rate reaches the highest accuracy of 98.88%,and the AUC values reached 0.9883.The accuracy of the three-mode prediction is better than the single-mode and dual-mode. The experimental results show that the multi-modal model proposed in this paper can effectively improve the correct rate of deception detection.
Night-Vision Colorization Based on Category-Oriented Color Lookup Tables
Weiwen ZHANG, Xiaojing GU, Xingsheng GU
, doi: 10.14135/j.cnki.1006-3080.20181018005
[Abstract](5640) [FullText HTML](1382) [PDF 943KB](4)
Abstract:
Due to the low illumination in the night, it is difficult to observe and identify the nighttime images exactly. To address this problem, we try to map the feature colors of different scenery to the nighttime images of visible and long-wave infrared bands such that the observers can analyze the images and speed up the reaction time. To this end, this paper presents a category-oriented color lookup tables night-vision colorization method by combining deep learning. Firstly, it utilizes the semantic segmentation via parallel fully convolutional network and the feature of two-way network at the end of the network to get the segmentation categories. And then, it colorizes the nighttime images by each category-oriented color lookup table to avoid the same color scheme and unnatural colors resulted from the global colorization like using single lookup table. In the post-processing stage, both the image normalization and the multispectral bilateral filtering will be adopted to smooth the colors and preserve the edges. The proposed method can fix the dual-band information, which is different from the other methods. By constructing the category-oriented color look-up table, the proposed method can obtain more stable results and much better material resolution. Moreover, the image contrast is enhanced and the thermal targets is highlighted by red such that it is much easier to detect. Besides, the proposed method can also be extended according to different environments and applications via the fixed category-oriented color lookup tables. Finally, by the comparison with other methods, such as global colorization by single lookup table, it is shown that the proposed method in this work can attain significant improvements in this area of night-vision colorization.
Synthesis of a Novel Cobalt Selenide/Carbon Composites withC-PAN Coating and Application in Li-Ion Battery
Xiao CHEN, Haining YU, Nan ZHENG, Chuanpeng XU, Guangyu JIANG, Yongsheng LI
, doi: 10.14135/j.cnki.1006-3080.20190307001
[Abstract](6363) [FullText HTML](2027) [PDF 1107KB](4)
Abstract:
Cobalt selenide is considered to be an ideal anode material for lithium-ion batteries because of its good lithium-ion insertion/extraction capability. However, the battery performance of cobalt selenide is limited by the large volumetric expansion upon cycling and its insulating nature. In this study, we produced CoSe2-C/C-PAN by coating CoSe2-C polyhedrons with polyacrylonitrile (PAN) in N2 atmosphere. The CoSe2-C polyhedrons were successfully synthesized using Co-based zeolitic imidazolate framework (ZIF-67) as precursor through a two-step method, which includes carbonization of ZIF-67 and a subsequent selenization. The resultant CoSe2-C/C-PAN showed high specific capacity and excellent cycling stability with an initial discharge capacity of 1 440 mA·h/g at 0.2 A/g and a reversible capacity of 653 mA·h/g at 1.0 A/g after 200 cycles as anode material of Li-ion battery. The excellent battery performance of CoSe2-C/C-PAN could be attributed to the synergistic effect of nanostructured CoSe2 and carbon materials, in which the nanostructured CoSe2 possesses high reactivity towards lithium-ions and the carbon can provide a continuous conductive matrix to facilitate the charge transfer and an effective buffering to mitigate the structural variation of CoSe2 during cycling. The significantly enhanced electrochemical performance of the composite could be ascribed to the improved electrical conductivity and structural stability of C-PAN.
Performance and membrane fouling of produced water from shale gas treated by MBR system with salt-tolerant bacteria
yan Jin, Yong-hong Zhang, Xingfu Song, Wei Lian, Hua He, Jian-guo Yu
, doi: 10.14135/j.cnki.1006-3080.20190606001
[Abstract](5201) [FullText HTML](1545) [PDF 892KB](2)
Abstract:
In this study, the salt-tolerant bacteria were used to degrade the organic matter and ammonia nitrogen in the shale field produced water. The degradation performance and membrane fouling characteristics of the anoxic reactor-membrane bioreactor (AR-MBR) and the separate MBR reactor were investigated. The difference between two reactors was that the AR-MBR system was provided with a filament filler to form an anoxic circumstance in front of the MBR reactor. The results showed that the degradation of the AR-MBR combined reaction system was better than that of the MBR reactor alone. The removal rates of TOC were 88% in AR-MBR and 80% in MBR, the removal rates of ammonia nitrogen were 90% and 75%, respectively.The transmembrane pressure(TMP) and the total membrane fouling rate of the AR-MBR was slower than that of the MBR reactor. The main reason was that the particle size of the floc in the AR-MBR reactor was larger than that in the MBR reactor, which was not easy to block the membrane pores. On the other hand, the soluble microbial products(SMP) and extracellular polymeric substances (EPS) content was lower in AR-MBR reactor than that of the MBR reactor, while the protein to polysaccharide concentration ratio (PN/PS) was higher, the reduction of fouling substance on membrane alleviated the membrane fouling phenomenon.
Identification and Research on Characteristics of a Salt-tolerant Bacteria for Shale Gas Produced Water Treatment
Yan JIN, Yonghong ZHANG, Xingfu SONG, Wei LIAN, Hua HE, Jianguo YU
, doi: 10.14135/j.cnki.1006-3080.20190603001
[Abstract](4926) [FullText HTML](1404) [PDF 1041KB](2)
Abstract:
In this study, a bacterial strain named 206BP, with efficient degradation for the organic matters in shale gas produced water, was isolated from high-salt wastewater and surrounding soil samples. Morphological observation, gram stain and 16SrDNA gene sequence analysis were used to identify the strain 206BP and the results showed that it belonged to the Bacillus genus as it had 99% similarity with Bacillus purgationiresistens and other orthologs. The diameters of the strain and spore were about 2.0 μm and 0.3-0.6 μm, respectively. Besides, it was confirmed the strain was Gram-positive, capable of producing urease for urealysisand hydrogen sulfide gas as well as hydrolyzing starch and reducing nitrate and nitrite. The growth of the strain 206BP was observed that it stayed at the lag phase in the first 5 h and enter the exponential growth phase in the period of 5-22 h, finally reaching the stationary phase after 24 h. Meanwhile, the effects of NaCl concentration, carbon source, nitrogen source and pH on growth characteristics were also investigated. The experimental results reflected the strain 206BP could grow well and was moderately salt-tolerant with 0-8w% NaCl. In addition, its optimum growth pH was in the range of 5-8 and the optimum carbon and nitrogen sources were glucose and urea, respetively. The bacterial concentration in the stationary phase of the growth curve could increase with more glucose while the stagnation period of the growth curve was prolonged as the glucose concentration exceeded 5000 mg·L−1. The added urea had a positive correlation with the strain 206BP growth but the promotion faded away with the urea concentration up to 50 mg·L−1.
Integrated Quality Monitoring Method Based on Multiple Data Structure
Min XUE, Jian YANG, Shuai TAN, Hongbo SHI
, doi: 10.14135/j.cnki.1006-3080.20180821002
[Abstract](6501) [FullText HTML](1618) [PDF 697KB](4)
Abstract:
The extraction method of different data structure features may affect the quality monitoring performance in industrial process. Hence, this paper proposes an integrated quality monitoring (E-MDSQM) method, which integrates the global and local structure features of the process data set method. Firstly, three basic models of partial least square (PLS), neighborhood preserving regression (NPR), and local principal component regression (LGPCR) are constructed to describe the global structure of the data, the local topology, and the local global hybrid structure information, respectively. And then, by introducing a new monitoring index, the genetic optimization algorithm is used to obtain the optimal weight, and the integration statistics are integrated, and the control limits are determined. Finally, the simulation via the Tennessee-Eastman process (TE) process is made to evaluate the monitoring effect of the integrated model and the comparisons with the three basic algorithms of PLS, NPR and LGPCR are also undergone. It is shown from these the experimental results that the integrated model can achieve better comprehensive effect.
Structure and Properties of Recycled Polyamide 6/Carbon Fiber Composites Modified by Chain Extension
Wei WANG, Jianfeng DING, Zhean XIA, Xinxin LI
, doi: 10.14135/j.cnki.1006-3080.20190512002
[Abstract](4771) [FullText HTML](1047) [PDF 1172KB](1)
Abstract:
The chain extender, styrene-maleic anhydride copolymer SMA-700, was compounded with recycled polyamide 6/carbon fiber composites (r-PA6/CF10) with a twin-screw extruder. The rheological properties, mechanical properties, morphology, crystalline structure, non-isothermal crystallization and subsequent melting behaviors of r-PA6/CF10 composites were investigated. The results show that SMA-700 has a remarkable chain extension effect on r-PA6/CF10 composites, and can significantly improve the processing performance of r-PA6/CF10. With increased content of SMA-700, the melt mass flow rate (MFR) of r-PA6/CF10 decreases gradually. Meanwhile, the apparent viscosity and melt pseudo-plasticity of r-PA6/CF10 will increase with the increased content of SMA-700. Mechanical tests show that incorporation of chain extender can simultaneously improve the tensile strength and flexural strength of r-PA6/CF10 composites. When the SMA-700 content is 1 wt%, the tensile strength of r-PA6/CF10 composites reaches its maximum level, which is 125.4 MPa. When the SMA-700 content is 2 wt%, the flexural strength reaches its maximum level, which is 182.3 MPa. The impact strength decreases with increased SMA-700 content. The scanning electron microscopy (SEM) indicates that there is no phase separation between SMA-700 and PA6 matrix, which means that SMA-700 and PA6 have good compatibility. Non-isothermal crystallization and subsequent melting behaviors charactered by differential scanning calorimetry (DSC) show that when the addition amount of SMA-700 is 1 wt%, the nucleation effect of SMA-700 may increase the crystallization rate and crystallinity of the PA6 matrix. However, with excessive amount of SMA-700, the crystallization rate and crystallinity of PA6 will both drop, and the perfection degree of α crystal form of PA6 will decrease at the same time.
Surrogate Model of Catalytic Reforming Process Based on a New Adaptive Sampling Algorithm
Jianchao ZHANG, Wenli DU, Shui QIN
, doi: 10.14135/j.cnki.1006-3080.20180915001
[Abstract](7018) [FullText HTML](1754) [PDF 1046KB](6)
Abstract:
Catalytic reforming unit is one of the most important devices in petroleum processing. However, because of its high dimensionality, complex mechanism, and complex working conditions, catalytic reforming unit is time-consuming for the optimization via direct using the mechanism model. Aiming at these shortcoming, researchers have proposes the concept of surrogate model, which can effectively approximate mechanism models. The surrogate model usually includes two steps: firstly, a series of sampling points are generated in the input space and the true response values are obtained; secondly, the corresponding surrogate model is established through the sampling point and its real response value. Apparently, the sampling strategy has direct impact on the speed and accuracy of surrogate model. Hence, this paper proposes a new adaptive sampling algorithm, termed as adaptive sampling algorithm-based nearest neighbor and Mahalanobis distance, ASA-NNMD. Through global exploration and local exploitation of sampling strategy, the proposed algorithm can obtain the sample point in the key information area. It is shown via seven test functions that the proposed ASA-NNMD can select sampling points of greater impact on the accuracy of surrogate model so that it can effectively improve the accuracy of surrogate model. Finally, the corresponding surrogate models is established for these key quality indexes of catalytic reforming process via four reactor inlet temperature, feed load, and hydrogen / oil ratio.
Multi-information Fusion Flame Detection Based on Ohta Color Space
Jiali LIU, Jiongyao YE
, doi: 10.14135/j.cnki.1006-3080.20180910001
[Abstract](4888) [FullText HTML](1410) [PDF 812KB](1)
Abstract:
Traditional fire detection methods are mostly based on sensors that evaluate and respond to fires by collecting information on smoke particles, flame temperature and relative humidity. However, the sensors must be placed near the flame to be used effectively. It cannot be used in scenes with extreme interference to the sensors. It is difficult to apply to large spaces, open spaces, and complex scenes. Moreover, It is difficult to confirm descriptive information such as fire location, flame size, and fire development status, and the its real-time performance and accuracy are low. Video flame detection is suitable for fire detection in complex physical environments, and has low cost, high detection rate and short response time. In order to prevent the occurrence of fires, the flame should be detected quickly and accurately. This paper analyzes the static and dynamic characteristics of the flame, proposes an algorithm based on Ohta color space detection and combination of saturation and Otsu threshold segmentation method, which can outline the likely region of flames in real time and accurately. The region is then featured by circularity, rectangularity, center-of-gravity-height coefficient, combining with LBP texture analysis, and finally judged by SVM. The experimental results show that the algorithm can accurately detect the flame, and the real-time performance and accuracy are effectively improved.
Synthesis and Properties of Benzoxazole Polymers Containing Electron-Donating Triphenylamine Groups
Xuan ZHONG, Yufei WANG, Qing HUANG, Xin GUO, Jiaqi MENG, Xinxin LI
, doi: 10.14135/j.cnki.1006-3080.20190329006
[Abstract](7801) [FullText HTML](2047) [PDF 949KB](9)
Abstract:
TPA-functionalized prepolymer (iPrTPA-PrePBO, tBuTPA-PrePBO) was synthesized by treating 4,4'-dicarbonylchloride-4''-isopropyltriphenylamine (iPrTPADC) and 4,4'-dicarbonyl chloride-4''-tertbutyltriphenylamine (tBuTPADC) with 4,6-di(tert-butyldimethylsilylamino)-1,3-di(tertbutyldimethylsiloxy)benzene (TBS-DAR), respectively. Then, a thermal cyclization reaction was carried out to obtain two benzoxazole polymers containing electron-donating triphenylamine groups (iPrTPA-PBO, tBuTPA-PBO). The prepolymers and benzoxazole polymers were characterized by nuclear magnetic resonance spectroscopy(1H-NMR) and Fourier transforminfrared spectroscopy (FT-IR). We also used thermogravimetry (TG), X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis) and Fluorescence spectroscopy to analyze the solubility, thermal and photophysical properties of the polymers. The results showed that the two prepolymers had excellent solubility in conventional solvents, and the polymer after thermal cyclization reaction also had moderate solubility in solvents with a high boiling point such as DMSO. The polymers existed in nitrogen atmosphere and air showed excellent thermal stability with a temperature above 500 ℃. Photophysical studies showed that polymers had higher fluorescence quantum yields than the conventional PBO with a similar band gap (~2.0 eV).
Adsorption Removal of Antibiotics from Aqueous Solutions by a Triazine-Functionalized Covalent Organic Framework Material
Zhen TIAN, Shuhao AN, Helin PAN, Ting XU, Changjun PENG
, doi: 10.14135/j.cnki.1006-3080.20190428005
[Abstract](5672) [FullText HTML](1462) [PDF 1323KB](8)
Abstract:
A novel triazine-functionalized crystalline polyimide covalent organic framework material named TF-COF was designed and prepared by condensation of 2,4,6-tris(4-aminobiphenyl)-1,3,5-triazine (TABT) and pyromellitic dianhydride (PMDA) under solvothermal conditions. The obtained TF-COF material was thoroughly characterized by FT-IR, 13C NMR, PXRD, TGA, SEM, TEM and BET and then used as solid adsorbent for water treatment. Because of its characteristics of crystalline structure, high specific surface area and good thermal stability, the TF-COF material exhibited excellent performance in removal of antibiotics from aqueous solutions. In the adsorption experiment, the adsorption selectivity of TF-COF for multiple antibiotics, as well as the effects of initial concentration, time and pH on adsorption, was studied. As a result, TF-COF had high adsorption capacity for four common antibiotics including tetracycline hydrochloride (TCH), doxycycline (DOX), ciprofloxacin hydrochloride monohydrate (CIPHM) and moxifloxacin hydrochloride (MXFH). Meanwhile, based on the fitting results of adsorption isotherms, the adsorption process of TCH and DOX on TF-COF accorded with Freundlich model and CIPHM and MXFH on TF-COF conformed to Langmuir model. Fitting through Langmuir model, the maximum adsorption capacity of TF-COF for TCH, DOX, CIPHM and MXFH was calculated for 518 mg·g-1, 625 mg·g-1, 227 mg·g-1 and 337 mg·g-1 at 25 °C, respectively. It was also found that the adsorption kinetic of four antibiotics on TF-COF could be described by pseudo-second-order kinetic model. Besides, TF-COF had the best adsorption effect for four antibiotics at pH=7. Furthermore, after five adsorption-desorption cycles, the adsorption effect of the material was basically unchanged, which indicated that TF-COF had good recycling performance.
Multi-objective Evolutionary Algorithm with Adaptive Neighborhood Based on Event Triggering
Xuewu WANG, Zelong XIA, Xingsheng GU
, doi: 10.14135/j.cnki.1006-3080.20181120005
[Abstract](4645) [FullText HTML](1190) [PDF 1248KB](7)
Abstract:
In order to improve the diversity and distribution of multi-objective algorithms, this paper proposes an adaptive neighborhood multi-objective evolutionary algorithm based on event triggering (MOEA/D-ET). By using the event triggering strategy to coordinate the global search and the local search, the proposed algorithm can converge to the Pareto frontier and attain better diversity. The grid method is adopted to achieve global optimization such that the grid coordinate system can quickly constrain the solution to the vicinity of the frontier surface and attain a good diversity, which can provide an effective guidance for local search. The adaptive neighborhood MOEA/D is used for local optimization and the search direction is optimized by the adaptive neighborhood. The number of weight vectors is enlarged for the small coverage area for increasing the search intensity such that it can jump out of the local minimum, improve the diversity of the solution, and make the solution more widely distributed in space. Three different levels of fixed neighborhood method and adaptive neighborhood method are compared via the ZDT1 problem, by which it is shown that the proposed adaptive neighborhood method can effectively improve the density of solution in the central region and make the distribution of the solution more uniform. Finally, the simulation via ZDT1-ZDT4, WFG1-WFG4, DTLZ1-DTLZ4, and DTLZ7 test functions is undergone, whose results are compared with four classic multi-objective algorithms and two new multi-objective algorithms including NSGA-III. It is shown from these simulation results that the proposed algorithm can attain better distribution in most tests than other test algorithms and has greater advantages in convergence and diversity.
Effects of Soybean Oil on Streptomyces Cyaneogriseus ssp. Noncyanogenus Fermentation
Jia-Yun XUE, Ming-Xia ZHAO, Ze-Jian WANG, Hui-Jie SUN, Yong-Hong WANG, Ju CHU, Ying-Ping ZHUANG
, doi: 10.14135/j.cnki.1006-3080.20190428002
[Abstract](6202) [FullText HTML](1602) [PDF 1066KB](30)
Abstract:
Nemadectin is a 16-membered macrocyclic lactones antibiotics produced by Streptomyces cyaneogriseus ssp. noncyanogenus (S. cyaneogriseus), which belongs to milbemycin subfamily. Moxidectin is chemically synthesized from nemadectin, which has broad application prospects on agricultural insecticides field because of its high efficiency, safety, environmentally friendly and so on. Therefore, many researches have paid more attention in the past few decades, and most of the researches were focused on genomic, chemical modification and pharmacological aspects, such as the global genome sequence ananlysis of S. cyaneogriseus, and toxicology of moxidectin on the animal deworming. However, hardly any researches focused on the fermentation technology of process optimization and regulation of nemadectin fermentation are scarce up to now. In this study, it was found that soybean oil had a positive effect nemadetin fermentation. The biomass of S. cyaneogriseus was effectively improved by adding soybean oil at start in 5 L fermentation (for about 29%), and the yield of nemadectin rised up to 1475 μg/mL, which was increased by 27.33%. Based on the analysis of the fermentation parameters, it was found that the primary metabolic activity of S. cyaneogriseus and the synthesis rate of nemadectin was greatly improved by the addition of soybean oil at the start of fermentation, resulting in a significant increase in the total yield of nemadectin.
A Short Text Clustering Method which Combining Topic Model and Paragraph Vector
Yuhe RAO, Zhihao LING
, doi: 10.14135/j.cnki.1006-3080.20190430001
[Abstract](6007) [FullText HTML](1599) [PDF 803KB](14)
Abstract:
Text clustering is an active topic in the domain of text information mining, and it has been widely used in information retrieval, search engines, etc. However, for short text, its high dimensionality and sparsity of features make short text clustering face many challenges. In order to overcome the sparsity and high dimensionality of short text, relevant scholars have done a lot of research, but in terms of how to further improve the quality of short text clustering, it is still to be further studied. Regarding this point, from the perspective of statistics and neural network algorithm, a short text clustering method based on Biterm topic model (BTM) and paragraph vector (PV) is proposed in this paper. This method mainly consists of two steps: 1) use the word-document-topic probability distribution, obtained by BTM, in combination with the local outlier factor and JS divergence, to achieve semantic splitting of the words in the entire set of texts; 2) Feed the resulted texts into vectorization model PV-DBOW (Distributed Bag of Words version of Paragraph Vector) and output paragraph vectors, whose combination with their corresponding document-topic probability distribution forms eigenvectors for text feature. The method enriches the amount of information carried by text features under the premise of ensuring a low feature dimension. The experimental results show that, the obtained eigenvectors have strengths in discriminative ability for short texts, and the proposed method improves the clustering effect of short texts, at the same time it can avoid the negative effects of sparseness in short texts.
Clustering Analysis and Research on the Blockages of Digitally Encoded DNA Carrier Based on VAE
Zixuan WEI, Jiale ZHOU
, doi: 10.14135/j.cnki.1006-3080.20190424001
[Abstract](4845) [FullText HTML](1199) [PDF 930KB](9)
Abstract:
Nanopore detection technology is an important technique in the field of single molecule detection. Feature extraction and transformation of nanopore blockade current is the key to classify signals and determine the analytes. As a framework of supervised learning, classification can only predict the known types of blockade current. Unsupervised learning is expected to achieve a distinction between the essential characteristics of the signal. Based on the blockade current of DNA carrier and the feature extraction of convolutional neural network, a clustering scheme applied to nanopore signals was proposed, which combines the improved deep embedded clustering with the variational auto-encoder to achieve the joint training of the feature transformation and clustering of the blockade current. In the original improved deep embedded clustering, the model utilizes an autoencoder to transform the input data to a new compressed representation, which reserves the crucial information of the input. Thus, the autoencoder can be replaced by a variational autoencoder to learn the parameters of a probability distribution representing the input data instead of just learning the compressed representation. The proposed clustering model was first applied to the case of 8 clustering centroids. Due to the symmetrical encoded DNA, like " 100” and " 001”, the case of 6 clustering centroids was further conducted to validate the proposed clustering model. The experiment results show that the approach can provide better clustering results for blockade current of DNA carrier. Compared with other clustering algorithms, the proposed method achieves a 29% boost at most and has better performance.
Synthesis of a Novel Cobalt Selenide/Carbon Composites with C-PAN Coating and Application in Li-Ion Battery
Xiao CHEN, Haining YU, Nan ZHENG, Chuanpeng XU, Guangyu JIANG, Yongsheng LI
, doi: 10.14135/j.cnki.1006-3080.20190307001
[Abstract](909) [FullText HTML](239) [PDF 1116KB](8)
Abstract:
Cobalt selenide is considered to be an ideal anode material for lithium-ion batteries because of its good lithium-ion insertion/extraction capability. However, due to large volumetric expansion upon cycling and insulating nature, the performance of cobalt selenide is limited. In this study, we obtained CoSe2-C/C-PAN by coating CoSe2-C polyhedrons with polyacrylonitrile (PAN) in N2 atmosphere. The CoSe2-C polyhedrons were successfully synthesized using Co-based zeolitic imidazolate framework (ZIF-67) as precursor through a two-step method, including carbonization of ZIF-67 and subsequent selenization. The resultant CoSe2-C/C-PAN presents high specific capacity and excellent cycling stability with an initial discharge capacity of 1 440 mAh/g at 0.2 A/g and a reversible capacity of 653 mAh/g at 1 A/g after 200 cycles as anode material of Li-ion battery. The excellent battery performance of CoSe2-C/C-PAN should be attributed to the synergistic effect of nanostructured CoSe2 and carbon materials, in which the nanostructured CoSe2 possesses high reactivity towards lithium-ions and the carbon can provide a continuous conductive matrix to facilitate the charge transfer and an effective buffering to mitigate the structure variation of CoSe2 during cycling. And such significantly enhanced electrochemical performance should be ascribed to the improved electrical conductivity and structure stability of C-PAN.
Mussel-Inspired High-Performance Adhesive Hydrogels Constructed through Charge Interaction
Bowei BI, Qixia HUA, Xuening SHEN, Yongkang PAN, Songchao TANG, Yuan YAO
, doi: 10.14135/j.cnki.1006-3080.20190409003
[Abstract](5765) [FullText HTML](2004) [PDF 836KB](19)
Abstract:
Inspired by the adhesion between mussels and rocks, a series of hydrogels composed of poly[3-(methacrylamido)propyl] trimethylammonium chloride polyacrylamide dopamine (PMPTCDMA) and poly vinyl benzenesulfonic acid sodium salt hydrate (PNaSS) based on charge interaction were prepared. Without introducing covalent bond or coordination bond, opposite charge interaction were adopted in this PNaSS/PMPTCDMA hydrogels system. The cationic polyelectrolyte, PMPTCDMA, simulating the proteins secreted by mussels, which similarly contained abundant positive charges and catechol residues. In addition, the anionic polyelectrolyte, PNaSS, which imitated the rocks with negative charged surfaces. The mechanical performance of the obtained PNaSS/PMPTCDMA hydrogels could be tuned with the content of catechol and water. The PNaSS/PMPTCDMA hydrogels exhibited high stretch performance and robust adhesion property. Before being soaked with saline, the hydrogels were transparent elastomer, however, after soaked, the hydrogels exhibited high tensile fracture stress, which could reach a maximum of 1.89 MPa. Besides, the hydrogels provided robust adhesion on glass slides with a shear strength which was up to 1.58 MPa. After being soaked with saline, the value could increase to 6.17 MPa, which was increased by 5 times, revealing a comparable performance to commercial adhesives. The mussel-inspired polyelectrolyte hydrogels were promising for the adhesion of devices underwater, or under humid environments.
Improving Protein Stability of Amino Acid Polymers during Lyophilization
Bing LI, Zihao CONG, Ximian XIAO, Yueming WU, Runhui LIU
, doi: 10.14135/j.cnki.1006-3080.20190422001
[Abstract](5819) [FullText HTML](1632) [PDF 1030KB](9)
Abstract:
Proteins are widely used as reagents in laboratories and as therapeutics for many different diseases. However, the native proteins are often aggregated and denatured under extreme conditions such as freezing, drying and dehydration, reducing bioavailability and therefore increasing the dose that is required. To protect the proteins under extreme conditions, we prepared two types of amino acid polymers, poly-(L-lysine) (PLL) and poly-L-glutamate (PLG) from the rapid ring-opening polymerization (ROP) of α-amino acid N-carboxyanhydride (NCA) using lithium hexamethyldisilazide (LiHMDS) as the initiator. β-galactosidase (β-Gal) was used as model protein to examine the protein protecting effect of synthesized amino acid polymers during lyophilization. The results indicated that PLL and PLG blending had significant protection effect on β-Gal during lyophilization and improved activity of the resulting protein from 38%, without using protecting agent during lyophilization, to 77% of the original protein activity. Our studies demonstrated that amino acid polymers could exert potent activity for protein stabilization. The easy operation of LiHMDS-initiated, moisture insensitive and rapid NCA polymerization implies great potential of this strategy to prepare amino acid polymers quickly for screening of protein stabilization and mechanism study.

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Recent Progress in the Development and Applications of Molecular Materials Based on Vibration-Induced Emission (VIE)
Weitao DOU, Xiaopeng HE
2019, 45(5): 685-696.   doi: 10.14135/j.cnki.1006-3080.20190624001
[Abstract](5853) [FullText HTML](1665) [PDF 3482KB](139)
Abstract:
Owing to the outstanding optical properties, fluorescent materials have become an important chemical tool for the advancement of modern science and technology. Fluorescence-based probes have also shown promise for a wide variety of biomedical applications. The development of new fluorescent probes relies on the exquisite design of high-performance emissive materials. However, traditional fluorescent dyes suffer from aggregation-caused quenching in aqueous solutions, lead to the production of false-positive and false-negative signals in biological systems. As a consequence, the development of emissive materials with an enhanced performance in aqueous media is a challenging task for both the academic and industrial communities. In particular, the organic fluorescence dyes developed to date generally emit a single fluorescence, which is easily interfered by the complexity of surrounding micro-environment. In the past few years, the development of the so-called ratiometric probes, which can exhibit two spectroscopically differentiated fluorescence emissions, has become a topical research area for the design of optical materials and sensors. Vibration-induced emission (VIE) is a new photophysical phenomenon originally coined by Tian’s group, which describes the unique fluorescence property of 9,14-dihydrodibenzo[a,c]phenazine derivatives that show a dual-fluorescence emission at ca. 600 nm and 460 nm corresponding to their free and restricted conformational state, respectively. By exquisitely tuning the vibrionic state of VIEgens, the effective development of state-of-the-art organic photoelectric materials, fluorescent probes and supramolecular organic gels has been possible. In this review, the synthesis and photophysical mechanisms of VIE-based compounds will be discussed. The successful use of VIEgens for the development of functional materials will be highlighted. A perspective on the future direction of how VIEgens can be used to construct chemical probes for biological studies and disease diagnosis is given.
Effect of Pore Structure and Surface Oxygen-Containing Groups of Activated Carbon Fiber on Formaldehyde Adsorption Performance
Weiyi YAO, Jitong WANG, Wenming QIAO, Licheng LING
2019, 45(5): 697-703.   doi: 10.14135/j.cnki.1006-3080.20180911002
[Abstract](5828) [FullText HTML](1378) [PDF 953KB](59)
Abstract:
With the increasing pollution of indoor air of formaldehyde, a simple and convenient adsorption technology is desired. Activated carbon fibers (ACF) is an excellent formaldehyde adsorbent material.Pitchactivated carbon fibers with different surface areas, pore size distribution and surface oxygen-containing groups were obtained by heat treatment and oxidative modification, and were applied to study the adsorption capacity of formaldehyde. The results indicated that P-ACF OG-5A with the smallest BET surface area and pore volume showed the highest adsorption capacity with a breakthrough capacity of 38.73 mg/g. Regression analysis showed that the formaldehyde breakthrough capacity was determined by the surface area and pore volume of ACF with pore size from 0.9 nm to 1.8 nm, instead of BET surface area and total pore volume. Secondly, the formaldehyde adsorption capacity of P-ACF OG-7A was greatly improved after the oxidative treatments by air, hydrogen peroxide and nitric acid. The oxidative treatment by nitric acid (65%) gave rise to the highest adsorption capacity with the breakthrough capacity of 58.21 mg/g, which is 2.5 times higher than that of the sample without treatment. The increased oxygen content in ACF enhanced the formaldehyde adsorption capacity. To further study the mechanism by which the formaldehyde adsorption capacity was increased, Boehm titration and regression analysis were used. The results showed that the numbers of acidic oxygen-containing groups (phenolic hydroxyl groups, lactone groups, carboxyl groups, etc.) in ACF were the main reason that led to the increase in formaldehyde adsorption capacity. The acidic oxygen-containing groups were mainly composed of hydrophilic groups like C= O, C−OH which could react with formaldehyde and enhance the formaldehyde adsorption capacity.
Simulation and Improvement of Separation Process for Aromatic Hydrocarbons Produced from Methanol Using Circulating Fluidized Bed Reactor
Dan ZHANG, Minbo YANG, Xiao FENG
2019, 45(5): 704-710.   doi: 10.14135/j.cnki.1006-3080.20180911004
[Abstract](5453) [FullText HTML](1621) [PDF 695KB](29)
Abstract:
Benzene, toluene, and xylene in aromatics are the essential raw materials in the petrochemical industry and can be used to synthesize the quantities of chemical products. In recent years, there have been increasingly demand for aromatics all over the world. Conventionally, benzene, toluene, and xylene are mainly produced from catalytic reforming oils and pyrolysis gasoline. However, China is short of crude oil reserves and has been the largest crude oil importer, which brings great challenge for the aromatics industry. Compared with the crude oil, coal reserves are relatively abundant in China. Therefore, it will be a favorable development direction to take coal as a breakthrough and develop the coal-based aromatics industry with Chinese characteristics, which has recently received great interest on the coal-based methanol to aromatics technologies in China. However, most of existing researches are theoretical and have a certain distance from practical application in industry. The separation process plays an important role in obtaining the qualified aromatics products, but it is energy intensive. Hence, it is necessary to improve the performance of the separation process. Based on the technology of methanol-to-aromatics with circulating fluidized bed reactor, this work establishes a full-flow simulation model for the downstream separation process via the Aspen HYSYS software. Sensitivity analysis is then performed on the amount of absorbent used in the methane absorber, which shows that the amount of absorbent can be reduced by 27.7% with little reduction in methane absorption. This work also achieves the integration of the heat exchanger network of the process such that the hot utility consumption can be reduced by 16.75% and the cold utility consumption is reduced by 11.89%. The proposed method in this work can provide theoretical support, optimization directions and recommendations for the methanol to aromatics process.
Characteristics and Kinetics Mechanism Function of Pyrolysis of Low-Grade Tobacco
Bingxiang LU, Dexiang ZHANG
2019, 45(5): 711-718.   doi: 10.14135/j.cnki.1006-3080.20180716007
[Abstract](5215) [FullText HTML](1517) [PDF 1014KB](17)
Abstract:
Biomass is considered to be a promising renewable energy source and has attracted increasing attentions from researchers. Biomass pyrolysis is a promising thermochemical conversion technology, which can generate pyrolysis oil, bio-char and pyrolysis gas. In this paper, the effects of pyrolysis temperature on the yield and composition of low-grade tobacco pyrolysis products were investigated on the basis of a fixed-bed tubular reactor. The weight loss behavior of low-grade tobacco was studied by thermogravimetric analyzer at different heating rates. The kinetics mechanism function was determined by Coats-Redfern and FWO integral method combined with double extrapolation method. The results showed that the yield of pyrolysis oil underwent an initial increase with increasing the temperature, reaching the maximum value of 26.93% at 400 ℃. Further increase in temperature led to a decrease in the yield of pyrolysis, a increase in the yield of pyrolysis gas, and continuous decrease in the yield of bio-char. Pyrolysis oil is mainly composed of ketones, phenols, furans and nitrogen-containing heterocycles compounds. Pyrolysis gas is mainly composed of CO and CO2. The pyrolysis process of low-grade tobacco can be divided into three stages: dehydration and drying stage; rapid pyrolysis stage; and carbonization stage. The main stage of pyrolysis can be divided into two sub-stages, the most probable mechanism function of the first sub-stage (T0Tmax) is D3 (Jander equation), while the most probable mechanism function of the second sub-stage (TmaxTf) is D4 (G-B equation).
Numerical Simulation of Convection Section of Ethylene Cracking Furnace Considering Evaporation Effect
Guihua HU, Jian LONG, Wenli DU
2019, 45(5): 719-727.   doi: 10.14135/j.cnki.1006-3080.20180913002
[Abstract](4633) [FullText HTML](1559) [PDF 1344KB](10)
Abstract:
Under the consideration of the effect of evaporation of the vaporizer, this paper utilizes the computational fluid dynamics (CFD) software, fluent, to numerically simulate the convection section of an ethylene cracking furnace. Moreover, the modeling of convection chamber and different tube sections are made, respectively, in which the flow of flue gas and oil gas adopts the standard k-ε turbulence model, the two-phase flow in the vaporizer adopts the volume of fluid (VOF) model, and the radiation heat transfer and the multi- components in the convection chamber adopt the discrete ordinates (DO) model and the species transport model, respectively. The simulation results are in agreement with the industrial data. And then, the heat transfer and flow in the convection section are analyzed. It is shown via these results that there exist two recirculation zones at the bottom of the convection chamber and the 90 degree corner of the cross section, which results in the residence time of the high temperature flue gas to increase here and yield a hot spot at the bottom of the mixture heater. This is not conducive to the long period operation of the cracking furnace. The results of the coupled calculation under the consideration of evaporation effect of the vaporizer will be more accurate. The heat absorption of the tubes is influenced by the position of the tubes, and the temperatures of tube skin and the oil gas at outlet in different tubes are different. These simulation results have reference significance for the design and operation optimization of the cracking furnace.
Synthesis and Mechanism of Electronic Calcium Carbonate
Yawen HOU, Xuemei CHEN
2019, 45(5): 728-735.   doi: 10.14135/j.cnki.1006-3080.20180806003
[Abstract](5750) [FullText HTML](1674) [PDF 1393KB](16)
Abstract:
With the breakthrough of electronic information industry, new requirements were proposed for the development of electronic information materials. As one of the raw materials of electronic components, calcium carbonate (CaCO3) has the characteristics of reducing the dependence of the dielectric constant on the temperature, changing the Curie temperature, improving the resistance to voltage and ferroelectric properties. CaCO3 with high purity, small particle size, uniform particle size distribution and calcite crystal type present excellent characteristics, and its preparation technology has attracted much attention. In this paper, electronic CaCO3 was prepared by decomposition reaction. The morphology and structure of CaCO3 were analyzed by scanning electron microscope, X-ray diffraction etc. Moreover, the effects of the key parameters, such as temperature and additive amount on the morphology of CaCO3, were discussed. The results showed that the nearly spherical CaCO3 with a particle size of 2.5 μm, uniform distribution particle size and purity of 99.86% was obtained when the decomposition reaction temperature was 30 ℃, the addition mass fraction of tartaric acid was 1.0% and the mole ratio of refined calcium chloride, ammonium bicarbonate and ammonia water was 1∶1∶1. The aim of addition of tartaric acid is to form calcium tartrate with calcium ion. The complexation and spatial structure of calcium tartrate promote the nucleation of calcium carbonate and inhibit its growth.
Effect of Electroless Nickel Plating on the Abrasion Resistance of Screen Printing Plate Film
Junlan LI, Junhao SHEN, Hong WANG, Gaimei PEI, Shiai XU
2019, 45(5): 736-741.   doi: 10.14135/j.cnki.1006-3080.20180719001
[Abstract](5492) [FullText HTML](1559) [PDF 937KB](11)
Abstract:
Screen printing is a versatile printing technique that can be used to print images on a wide variety of substrates using a plate which is of great significance to have its service life. The plate consists of a screen (supporting the photosensitive film), a screen frame (fixing the screen) and a UV-curing photosensitive film (forming a printing pattern). The screen printing plate film, including silk screen and photosensitive film, is easy to wear out due to the direct contact with squeegee and ink during the printing. Therefore, it is significant to improve the abrasion resistance of screen printing plate film by simple method. Here, screen printing plate film was treated with three different components of nickel plating solutions. Surface morphology and abrasion resistance of the treated films were investigated by methods of scanning electron microscope (SEM), atomic force microscope (AFM) and Taber abrasion testing machine. The results show that the surface morphology of the treated films has obvious changes, and the roughness and abrasion resistance are improved. The film with optimum abrasion resistance is treated with a two-component commercial nickel plating solution, which is attributed to the existence of hemispherical particle on the surface of films. Moreover, the effect of plating temperature on abrasion resistance of film is investigated, which indicating that the abrasion resistance of film increases with temperature. And the film treated at 40 ℃ has the best abrasion resistance, which increases by 36.6% compared with original film.
Effect of CMC on Rheological Properties and Dispersion Stability of Anode Slurry
Xiaomin XI, Xiwei JING, Jian XU, Weiguang GONG, Baicun ZHENG
2019, 45(5): 742-749.   doi: 10.14135/j.cnki.1006-3080.20180718003
[Abstract](5202) [FullText HTML](1366) [PDF 1359KB](9)
Abstract:
Lithium ion batteries have been widely used in many fields such as electronic products, electric vehicles and large-scale energy storage materials due to their excellent performances. Binder directly affects the electrochemical properties of the battery, including the rate capacity, charge and discharge cycle stability and so on. Compared with the PVDF binder, the aqueous binder, sodium carboxymethyl cellulose (CMC), has a better dispersion stabilizing effect on the graphite anode slurry, which could be ascribed to the presence of carboxyl group and hydroxyl group on its molecular chain. The electrostatic repulsion generated by the hydroxyl groups on CMC chains make the graphite disperse homogenously. Accordingly, the substitution degree (DS) which is closely related to the content of carboxyl and hydroxyl groups may have remarkable influences on the dispersion of graphite. The influences of substitution degree of CMC on the rheological properties, dispersion and stability of graphite anode slurry, as well as the pole piece electrical resistivity, were studied in this paper. The mechanism of CMC on graphite slurry was also analyzed by scanning electron microscope (SEM) and Zeta potential. The results showed that the viscosity and stability of graphite slurry were enhanced, while the pole piece electrical resistivity was decreased with the gradual increase in the CMC substitution degree, which could be explained by the stronger electrostatic repulsions as measured by Zeta potential tests. Meanwhile, the content of CMC had significant effects on the rheological properties, stability and the pole piece electrical resistivity of the graphite slurry. The slurry showed the best stability and dispersion, also the pole piece displayed the lowest electrical resistivity in case the dosage of CMC was 1.5%.
Synthesis and Nematicidal Activity of Azabicyclo[3.3.1]nonane-Thiadiazole Derivatives
Tianjiao YANG, Jiayi WANG, Gonghua SONG
2019, 45(5): 750-758.   doi: 10.14135/j.cnki.1006-3080.2018061400
[Abstract](6107) [FullText HTML](1828) [PDF 539KB](9)
Abstract:
Nematodes are crop pests which can cause serious loss in crop production and food crisis. Traditional nematicides, such as Carbamate, isothiocyanate and organophosphates, have largely inhibited the damages of nematodes on agriculture, but they also generate negative effects on both plants and human health, such as root harm and human poisoning. Hence developing novel nematicides with low toxicity and high nematicidal efficiency are extremely urgent. 5-HT(5-hydroxytryptamine) is an important monoamine neurotransmitter which plays important role in mammalian endocrine function as well as in the central and peripheral nervous system. 5-HT was also found to be an important substance which can control the physiological activities of nematodes including feeding, movement and reproduction. So far, some studies have been reported on the development of 5-HT receptor as potential target for nematicides. Based on the previous achievements performed in our group and the principles of drug development, MDL 72222, a typical 5-HT3 receptor antagonist which can significantly inhibit the swallowing function of the pharyngeal pump in caenorhabditis elegans, has a lethal effect on nematicides at certain doses. Upon changing the configuration or number of carbon atoms of the bridged ring and introducing the bioactive group thiadiazole into the structure of compound MDL 72222, 23 new 3-azabicyclo[3.3.1]nonane-thiadiazoles derivatives were designed and synthesized. All the involved compounds were characterized by 1H-NMR, 13C-NMR and HRMS. The in vivo bioactivity test was performed using the root-knot nematodes, and the commercial nematocidal agent Avermectin was used as the control product. The nematicidal activity against root-knot nematode was determined. Ten target compounds exhibited certain inhibitory activity against root-knot nematodes at a concentration of 40 mg/L. Notably, compound Z7 showed excellent nematicidal activity in the tube test.
Development of MoS2 Composites and Sensitive Detection of Amyloid β-Protein
Yawen CHENG, Weitao DOU, Guorong CHEN
2019, 45(5): 759-766.   doi: 10.14135/j.cnki.1006-3080.20180720001
[Abstract](7001) [FullText HTML](2287) [PDF 1123KB](13)
Abstract:
Amyloid beta peptide (Aβ) has been considered as the hallmark of Alzheimer’s disease which is neurodegenerative disease and affects many senior citizens. However, drug for the treatment or control of such a disease is still lacking, thus early detection and intervention are particularly important. So far, fluorescence diagnose technique has been developed as an important mean for the detection of Aβ, but there are still many disadvantages in the traditional fluorescence techniques, such as low sensitivity, large background interference, and complicated operation. To address these issues, we synthesized a series of dicyanomethylene- 4H-pyran (DCM-OH) derivatives which were self-assembled with molybdenum disulfide (MoS2) driven by π-π stacking interaction. The commercial products, resveratrol (Res) and thioflavine T (ThT), were used as the control group. The structures and purities of the three compounds were characterized by high resolution mass spectrometry (HRMS) and high performance liquid chromatography (HPLC). The morphologies and structures of the three composites were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The characterization results display that the three prepared composites are regular and uniform, and can be used to detect indicators of AD in vitro. Moreover, we tested the applicability of the three composites in the detection of Aβ (1−40) and Aβ (1−42) in solution. The results show that the composites are capable of detecting Aβ (1−40) and Aβ (1−42) sensitively. In addition, the composite DCM-OH/MoS2 was more sensitive for the detection of Aβ (1−42) with a LOD (Limit of Detection) of 6.8 nmol/L, which is 9.8 nmol/L for Aβ (1−42). Finally, we also tested the selectivity of the composite DCM-OH/MoS2 against other proteins, and found that it showed better selectivity for Aβ. The results demonstrate that the developed system shows certain biological application prospects.
Numerical Simulation of Mixing Time in Stirred Reactors Based on Mean Age Theory
Ao PAN, Minghui XIE, Jianye XIA, Yingping ZHUANG
2019, 45(5): 767-774.   doi: 10.14135/j.cnki.1006-3080.20180716001
[Abstract](5692) [FullText HTML](1615) [PDF 918KB](9)
Abstract:
A mixing time simulation method based on mean age theory is established. This method is suitable for industrial stirred reactors for computing their resource saving. The simulation process is as follows: simulation of the velocity field of bioreactor using computational fluid dynamics (CFD); simulation of the mean age distribution using CFD steady-state calculation; mixing time simulation through volume integration process performed on the histogram of the mean age distribution. To get accurate mixing time, three conditions are required: unstructured mesh element number should ensure that the power calculated by energy dissipation rate is exceed 80% of the power calculated by the torque; inlet flux should be two orders lower in magnitude than the impeller pumping flow rates; number of mean age groups should be more than 12 500 for Matlab post-processing. When the ratio of height to diameter of the reactor is lower than 1.5∶1, the simulation results are in good agreement with the experimental values, and the average error is within 10%. When the ratio is higher than 1.5∶1 with a Reynolds number less than 2.1×105, the differences between the simulation results and the experimental values become higher, and the error is 12%. Upon comparing the cases of the pitch blade turbine pumping down (PBTD) and the pitch blade turbine pumping up (PBTU), it is found that the simulation results of PBTD completely fall in the experimental data range, while the simulation results of PBTU are higher than the experimental values, the maximum error is up to 14%. In addition, many mixing time empirical formulas are absence of considering the volume factor. On the basis of the present work, it is found that N·θ number obtained by simulation is not affected by the scales of reactors.
Age and Growth of Swordtip Squids Based on Microstructure of Beaks
Jingyuan LIN, Bilin LIU, Liquan WANG
2019, 45(5): 775-782.   doi: 10.14135/j.cnki.1006-3080.2018051200
[Abstract](5036) [FullText HTML](1427) [PDF 715KB](5)
Abstract:
Swordtip squid (uroteuthis edulis) is an important kind of cephalopods in China. Insight into the law that governs its growth is a crucial research direction in the field of fishery biology. Because most of the cephalopods can only live for one year, researchers usually receive many difficulties during studying the age and growth of the Swordtip squids. Beaks, containing a lot of ecological information, are a kind of the most important hard tissues of the cephalopods. In this work, we first present a study on the relationships between the lengths of various parts of the beaks and the mantle length, body weight and age of the swordtip squids by regression analysis, respectively. The study is based on 32 samples collected from the March 23 in 2015 in the fishing areas of Pearl River Estuary. It was found that the lengths of various parts of the beaks showed logarithmically dependence on the mantle length. The relations between the body weights and the lengths of various parts of the beaks mainly fit a power law. The mantle length and body weight show a typical exponential growth as a function of the age; and the characteristic time τW for the growth of body weight is about one third of that, τL, for the growth of the mantle length. The age of the samples is ranged from 91 d to 268 d and the spawning time is between September and October. We further established the relation between the lengths of various parts of the beaks and the mantle length, body weight and age of the swordtip squids, respectively, by artificial neural networks. The precision of the prediction can be greatly improved as compared to the regression analysis.
A Novel Successive Interference Cancellation Algorithm Based on Asynchronous NOMA System
Pei SUN, Weina YUAN, Hua CHENG
2019, 45(5): 783-788.   doi: 10.14135/j.cnki.1006-3080.20180412008
[Abstract](5736) [FullText HTML](1702) [PDF 951KB](15)
Abstract:
As one of the key candidate technologies for 5G, the non-orthogonal multiple access technology (NOMA) employs the power domain reuse to raise the system throughput and frequency utilization effectively. Among the existing works about the NOMA system, it has been mostly assumed that the folding signal is completely synchronous. However, in the actual applications, the folding signal may not be completely synchronous due to the difference of users’ location and status. Aiming at the time-delay problem of folding signal transmission during different users, this paper proposes a new successive interference cancellation algorithm. Firstly, the superposed signals are asynchronously sampled and a series of constructional output data are obtained. And then, according to the overlap part of each adjacent symbol, a symbol is reconstructed by adopting a new successive interference cancellation strategy in the receiving terminal. It is shown from the results that the proposed method can obtain cleaner exceptional properties of the interference signal cancellation at the cost of adding complexity of signal reconstruction. Since this structure will result in the error expansion problem and affect the detection and reconstruction of all subsequent signals, it is more stringent for the requirement on the accuracy of each signal estimation and the channel estimation. Hence, this paper adopts the scalar Kalman filter algorithm to estimate the channel status information such that more accurate channel states in the time direction can be obtained. These can bring great improvement on the error detection performance of the entire signal detection such that the proposed algorithm in this paper is more applicable to the actual signal estimation.
Fine Grained Image Classification Using Low Dimensional Selective Convolutional Descriptors and GMM Mean-Only MAP Adaption
Bing XIE, Hongqing ZHU
2019, 45(5): 789-794.   doi: 10.14135/j.cnki.1006-3080.20180603001
[Abstract](6231) [FullText HTML](1640) [PDF 699KB](13)
Abstract:
Fine grained image classification is a challenging task in computer vision, whose aim is to recognize images that belong to the same basic category but not the same class or subcategory. This image classification is intractable for two reasons. The first one is that the images of the same class obtained from real world contain different environment, illumination, and postures. These differences will result in high intra-class variances. The other is that some classes under the same basic category look very similar to each other, which results in low inter-class differences. Traditional fine grained image classification approaches divide the input image into many overlapping patches. Thus, these patches may contain huge amount of redundant information. Local region descriptors extracted from these patches will require a lot of computation time. Recently, convolutional neural network (CNN) has been widely used in fine grained images classification and has shown its effectiveness when dealing with large amount of image. However, it is usually difficult for CNN to obtain the qualified annotations. Although the bounding box regression may reduce the influence of lacking annotations, it may inevitably contain background or noisy parts. Hence, this paper proposes a selective convolutional descriptor with mean only maximum a posterior adaption via GMM (SCD-MGMM), which can effectively deal with the shortcoming of intra-class and inter-class variances. Firstly, the convolutional features are chosen from entire images by using SCD approach so that the features extracted from a pertained VGG 16 model has stronger robustness to noise. Thus, the proposed SCD-MGMM can automatically locate the main object without any supervised information or extra fine grained images training. Besides, the proposed framework utilizes the mean only maximum a posterior adaption based on GMM (MGMM) to overcome the shortcoming that GMM requires a lot of observation data. Finally, this paper adopts a fast linear scoring technique to compute the log-likelihood. It has been shown from quantitative experiment results that the proposed method can attain better fine grained classification.
Tracking Gate Adjustment Algorithm of Sensitive to Flight Status
Han ZHAO, Jingjing ZHUGE, Jiajun LIN
2019, 45(5): 795-800.   doi: 10.14135/j.cnki.1006-3080.20180622003
[Abstract](4461) [FullText HTML](1148) [PDF 963KB](4)
Abstract:
It is quite difficult to achieve the maneuvering target tracking in clutter environment due to the uncertain measurement source and target flight status. The tracking accuracy of the maneuvering target is usually affected by various factors including the target flight status and clutter. Stronger maneuvering of the target or the excessive clutter interference may result in the loss of tracking and the low tracking accuracy. Tracking gate can determine whether the measurement trace comes from the target's decision threshold, and provides an effective tool for practical applications. When the target is maneuvering, the target may be lost if the tracking gate is not adjusted in time. An appropriate setting of tracking gate can reduce erroneous data associations and improve tracking accuracy. On the contrary, inappropriate tracking gate may result in the loss of follow-up or mis-following. Aiming at the above shortcomings, this paper proposes a flight status sensitive tracking gate adjustment algorithm (FSSTGAA) under the framework of IMM-PDA method. Although the traditional tracking gate design taking the error information as the trigger condition can effectively reduce the target loss rate, it cannot ensure the tracking accuracy. By analyzing the source and changing trend of the error rate according to the target flight status, the proposed FSSTGAA will dynamically adjust the tracking gate according to the error dynamic change rate when the tracking error is within the acceptable range. Finally, it is shown from simulation results that, compared with the traditional tracking gate adjustment algorithms, the proposed algorithm can effectively reduce the target loss rate and improve the tracking accuracy of maneuvering targets.
Single Image Super-Resolution Using a Two-Channel Convolutional Neural Networks
Qinjuan YAO, Jiajun LIN
2019, 45(5): 801-808.   doi: 10.14135/j.cnki.1006-3080.20180523002
[Abstract](5296) [FullText HTML](1700) [PDF 907KB](9)
Abstract:
In recent year, the convolution neural networks(CNNs) have been becoming a very important machine learning approach for computer vision and have made great progress in single image super-resolution(SISR). This paper propose a two-channel convolutional neural network for super-resolution(SR) problem. The shallow channel reconstructs the overall profile of the image and retains the original image information. The deep channel recovers the high-frequency texture feature of the image. Moreover, densely connected convolutional networks are introduced in deep channel to more efficiently recover the high-frequency information of image. In a typical feedforward CNN, some of high-frequency information may be lost in latter convolutional layers. The proposed dense connections with the previous convolutional layers can compensate for the loss and further strengthen the high-frequency information. Moreover, the proposed network connects each layer to other layer in a feedforward way so that each layer can obtain a feature map from all previous layers and map its own feature to all subsequent layers. To a certain extent, this may slow down the gradient dissipation in the training process. Different from the densely connected convolution networks in object recognition, we combine features through summation instead of concatenating them in order to better adapt the SR problem. Simultaneously, the fusion layers are used to synthesize the outputs of the two individual networks by adding additional convolution layers. Each individual network obtains a mapping from low resolution(LR) to SR space. Since the output of the two individual networks may have different context features, additional convolution layers are applied on these feature maps. By considering the difference of the structures of two networks, we add a convolutional layer after the sum of the two networks, taking the tanh as activation function. It is shown from simulation results that the proposed model can attain better performance in the subjective and objective aspects, compared with the state-of-the arts in most circumstances.
Text Classification Method Based on Normalized Document Frequency Feature Selection
Hongshan ZHAO, Guisheng FAN, Huiqun YU
2019, 45(5): 809-814.   doi: 10.14135/j.cnki.1006-3080.20180914005
[Abstract](7356) [FullText HTML](1609) [PDF 501KB](9)
Abstract:
Together with the continuous accumulation of text document, the text classification has received more and more attentions, since it can be used to automatically give a correct category mark for input text document. Feature selection is an important process of text classification, whose goal is to choose highly distinguishing features for improving the performance of a classifier. In this paper, we shall investigate the feature selection problem based on the filter that sorts the features by different feature selection metric and selects the features according to the sorting result. The traditional document frequency (DF) is a common feature selection metric via statistics, in which the number of documents containing feature is taken as the basis of selection, and the feature appearing in most documents will be thought to be important. However, this may result in that the features containing less category information are selected and the correlation of features and categories is ignored. Aiming at the above shortcoming, this paper proposes an improved feature ranking metric, termed as normalized document frequency (NDF). By taking the relativity between features and categories into account, this paper introduces two normalization factors, the number of documents based on category and the number of documents based on feature. The performance of NDF is compared with three well known feature ranking metrics including DF, odds ratio (OR), and chi squared (CHI) on news data set in different features dimensions using naive Bayes (NB) classifier. It is shown via these results that the NDF metric outperforms the three metrics in terms of Macro-F1 and the accuracy (ACC) by increasing 3.5%, 2.0%, and 3.4%, respectively. Therefore, the NDF metric can select valuable features that are more favorable for distinguishing text category and effectively improve the performance of text classification.
Weight-Based Multi-view Global and Local Structural Risk Minimization Classifier
Zhichao JIN, Daqi GAO, Changming ZHU, Zhe WANG
2019, 45(5): 815-822.   doi: 10.14135/j.cnki.1006-3080.20180704001
[Abstract](5169) [FullText HTML](1403) [PDF 610KB](11)
Abstract:
Minimizing empirical risk, i.e., training error, means that a classifier should have a high classification accuracy on label-known samples/training samples, while minimizing Vapnik-Chemonenkis (VC) dimension or complexity means that a classifier should have a low prediction error on label-unknown samples/test samples. Since structural risk includes empirical risk and complexity, it can be utilized to measure the effectiveness of a classifier. The structural risk minimization (SRM) means that a classifier should have better classification accuracy on training samples and better prediction performance on test samples simultaneously. Since a global space can be divided into several local ones, the minimization problem of structural risk has global and local minimization. In recent years, multi-view classifiers have been developed to process multi-view data sets composed of the samples with multiple views. Each view represents the information of data set from a certain field. However, traditional multi-view classifiers cannot minimize the structural risk fully due to ignoring the differences of views and features. Aiming at the above shortcoming, this paper proposes a weight-based multi-view global and local structural risk minimization classifier. This proposed classifier utilizes the weight of features and the weight of views so that the classifier can attain the consistence with the distribution of data set. It is shown from experiment results on three multi-view data sets, Mfeat, Reuters, and Corel that by introducing the weights of features and views, the corresponding multi-view classifier has better classification performance. Hence, the proposed method can enhance the performances of classifiers and effectively minimize structural risk.
Transient Simulation and the Minimum Reversal Time of High Temperature Air Combustion in Oil-Field Jacket Heater
Sui LI, Yuanhua WANG
2019, 45(5): 823-830.   doi: 10.14135/j.cnki.1006-3080.20180723008
[Abstract](4933) [FullText HTML](1373) [PDF 1275KB](4)
Abstract:
The reversal time of the high temperature air combustion is usually determined by engineering experience and the thermal characteristics of the regenerator, which often ignores the combustion in furnace. If the reversal time is too short, it will cause incomplete combustion, large fluctuation of furnace temperature and other problems. Therefore, it is necessary to analyze the minimum reversal time from the perspective of combustion in furnace. The commercial software Fluent was used to perform the transient simulation for analyzing the combustion process of high temperature air combustion system in oil-field jacket heater. Influences of the volume fraction of oxygen, load fluctuation and temperature of the heated air on combustion performance and reversal time were analyzed. The results show that the combustion in furnace can be divided into four processes: exhaust gases evacuation, flame reburning, flame diffusion and stable combustion. At the stage of exhaust gases evacuation, the high temperature gas is discharged out, which makes a rapid drop of temperature during the original combustion. At the same time, fresh gas gets in, so the temperature decreases at the original fume side. After about 0.2 s, the flame reburns at the original fume side, and the temperature in the furnace rises rapidly. Then the flame diffuses forward, and the temperature is increased and then is prone to be stable in the whole furnace. The mass fraction of NO shows a similar evolution as that of temperature change, and has a certain lag. The minimum reversal time should be no less than the stabilization time of temperature and the mass fraction of NO in the furnace. Reducing the volume fraction of oxygen and increasing the temperature of preheated air can stabilize the combustion and reduce the minimum reversal time. Load fluctuation has no obvious effect on the minimum reversal time. 15 s is the commendatory minimum reversal time of this kind of jacket heater.
Effect of Bearing Roller Machining Precision on the Dynamic Performance of High Speed Motorized Spindle
Wenli XIONG, Jiapeng YANG, Qi AN
2019, 45(5): 831-838.   doi: 10.14135/j.cnki.1006-3080.20180613002
[Abstract](5251) [FullText HTML](1549) [PDF 1538KB](7)
Abstract:
The present work established a mechanics model of angular contact ball bearings upon focusing on the high speed spindle. The model can calculate the contact load of every ball and bearing stiffness. A dynamic model of the rotor was developed as well in this work. The model can calculate the contact load of every ball with considering machining precision.With a concrete example, the paper studied the effects of roller precision on the axis trajectory of the bearing, the rotor critical speed, the first three order modes, the unbalanced response and the influences of the radial load on the unbalanced response. The numerical calculation results suggested that the axis of the bearing was an ellipse when all rollers had no size errors. With the decrease in the machining precision, the axis trajectory of the bearing was no longer an ellipse, and the amplitude fluctuation of axis motion trajectory was increased. When the precision and axial load were kept constant, the rotor unbalance response amplitude of shaft end was increased with the radial load. With the decrease in machining precision, the critical speed of the rotor was decreased, and the first three modes did not changed. When the rotor angular velocity stayed the same, the rotor unbalance response amplitude was increased with the decrease in radial load precisions. When the precision was the same, the rotor unbalance response amplitude was increased with the rotor angular velocity.