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research on the Long Time Swelling Properties of Poly (vinyl alcohol)/Hydroxylapatite Composite Hydrogel

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Journal of Bionic Engineering 2009年第1期6卷 22-28页

作者： De-kun Zhang~(1,3), Da-gang Wang~2, Jun-jie Duan~(1,3), Shi-rong Ge~(2,3)1. School of Materials Science and Engineering, china University of Mining and technology, Xuzhou 221116, P. R. china2. School of mechanical and electrical Engineering, china University of Mining and technology, Xuzhou 221116, P. R. china3. Biotribology Center, National Key Laboratory of Tribology, Tsinghua University, beijing 100083, P. R. china [a]School of Materials Science and Engineering China University of Mining and Technology Xuzhou 221116 P. R. China [b]School of Mechanical and Electrical Engineering China University of Mining and Technology Xuzhou 221116 P. R. China [c]Biotribology Center National Key Laboratory of Tribology Tsinghua University Beijing 100083 P. R. China

Poly(vinyl alcohol)/hydroxylapatite(PVA/HA)composite hydrogel was prepared by repeated freezing and *** water loss properties of the resultant hydrogel were investigated by using optical *** time immersion tests of PVA/HA composite hydrogel were carried out in the diluted calf serum solution to study the change laws of swelling properties with the freezing-thawing cycles and HA *** micro-morphologies of PVA/HA composite hydrogel after long time immersion were observed by means of the high-accuracy 3D *** results show that the swelling process of PVA/HA composite hydrogel is the converse process of its water *** time swelling ratio curves of PVA/HA composite hydrogel in the calf serum solution are manifested as four stages of quick increase,decrease,slow decrease and stable balance,and its equilibrium swelling ratio decreases with the increase of freezing-thawing cycles and HA *** is revealed that the network structure of the composite hydrogel immersed for a long period is significantly improved with the increase of HA content. Perfect network structures of PVA/HA composite hydrogel as well as full and equilibrium tissues after swelling equilibrium are obtained when the HA content is 3% and the number of freezing-thawing cycles is 7.

关键词： poly (vinyl alcohol) hydroxyapatite composite hydrogel swelling property morphology

Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

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Progress in Natural Science:Materials International 2005年第5期15卷 453-457页

作者： LI Chensha1*, WANG Dazhi1, ZHANG Baoyou2, WANG Xiaofeng1, CAO Maosheng3 and LIANG Ji1(1. Department of mechanical Engineering, Tsinghua University, beijing 100084, china 2. Center for Analysis and Measurement, Harbin institute of technology, Harbin 150001, china 3. School of Material Science and Engineering, Tsinghua University, beijing 100084, china) Department of mechanical Engineering Tsinghua University Beijing 100084 China Center for Analysis and Measurement Harbin Institute of Technology Harbin 150001 China School of Material Science and Engineering Tsinghua University Beijing 100084 China

Polarizable electrodes of electric double layer capacitor (EDLCs) were made from carbon nanotubes. Effects of different binders, which are phenolic resin (PF) and polytetrafluoroethylene (PTFE), on the properties of polarizable electrodes are studied. Results indicate that the microstructure, pore size distribution and specific capacitance of the electrodes with PTFE binder are superior to those electrodes with PF binder after carbonization. The suitable binder (PTFE) for carbon nanotubes electrodes is proposed.

关键词： carbon nanotubes electric double-layer capacitors phenolic resin polytetrafluoroethylene.

Dynamics analysis and experiment on the fishtailing type of valveless piezoelectric pump with rectangular vibrator

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Science china(Technological Sciences) 2010年第12期53卷 3241-3247页

作者： HUANG Yi1, ZHANG JianHui1, HU XiaoQi1, XIA QiXiao2, HUANG WeiQing1 & ZHAO ChunSheng1 1 Department of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, china 2 Department of mechanical and electrical Engineering, beijing Union University, beijing 100020, china 1. Department of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Department of Mechanical and Electrical Engineering Beijing Union University Beijing 100020 China

In recent years, the research and development of piezoelectric pumps have become an increasingly popular topic. Minimization, structure simplification and stronger output become the focus of piezoelectric pumps’ research due to its possible application in MEMS technology. The valveless fishtailing piezoelectric pump, neither a volumetric nor a rotating pump, was invented according to the bionics of fish swimming. With assumption that the head of the fish is fixed while its tail is swinging, fluid would flow toward the end of the tail, achieving the function of a valveless pump. This type of pumps creates a new branch for the piezoelectric pump research, which is proposed for the first time in this paper. The relationship between the flow rates and vibrating frequencies was derived from the interaction between the vibrator and fluid. Numerical simulations with FEM software were conducted to study the first and second vibration modes of the piezoelectric vibrator. The results showed that the maximum amplitude of the vibrator was 0.9 mm at the frequency of 76 Hz for the first vibration mode, while the maximum amplitude of the vibrator was 0.22 mm at the frequency of 781 Hz for the second vibration mode. Experiments were conducted with the Doppler laser vibration measurement system, and the results were compared to those of the FEM simulation. It was shown that in the first vibration mode the piezoelectric vibrator reached its maximum amplitude of about 0.9 mm at the driving frequency of 49 Hz, which gives the flow rate of 2.0 mL/min, in the second vibration mode, the maximum amplitude was about 0.25 mm at the frequency of 460 Hz with the flow rate being 6.4 mL/min.

关键词： piezoelectric pump valveless fishtailing rectangular vibrator dynamics analysis experiment

Optimization of Processing Parameters for Laser Powder Deposition using Finite Element Method

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Journal of Wuhan University of technology(Materials Science) 2010年第5期25卷 832-837页

作者：付垚 State Key Laboratory of Non-ferrous Metals and Processes General Research Institute for Non-ferrous Metals

In order to investigate the effects of powder materials and processing parameters on thermal and stress field during laser powder deposition （LPD）, a finite element model was developed with the help of ANSYS software. The finite element model was verified by the comparison between the experimental results and computed results. Then LPD processes with different powder materials and processing parameters were simulated by using the FE model. The results show that less difference of thermal conductivity and thermal expansion coefficient between powder material and substrate material produces lower residual stress; higher laser power, laser scanning speed and smaller laser beam diameter can lead higher peak temperature and higher residual stress. The research opens up a way to rational selection of the powder materials and processing parameters for ensured quality.

关键词： laser powder deposition thermal field stress field powder material processing parameters

Implementation of Heat Treatment Process Simulation with Object-Oriented Method

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Journal of Shanghai Jiaotong university(Science) 2000年第1期5卷 253-262页

作者： Yongping Yu, Yuzhen Niu, Jian Li, Changyong Guo, Ning Gao, Weidong Qiang, Wei Wang 1.beijing research institute of mechanical and electrical technology, beijing 100083, china 2.The Science and technology Ministry of china, beijing 100823, china 3.The S

In this paper, mathematical models and FEA formulation for implementing heat treatment process simulation were given out. The various coupling effects were treated. The object-oriented methodology of developing heat treatment simulation was explored. The framework of simulating programs was outlined. The main C++ classes were developed, some important member functions were implemented. The present research work shows that using object-oriented method can greatly reduce the amount of coding. The programs are clear in conception, easy to test, modify and expand. By using the methodology introduced in this paper, one heat treatment process three dimensional simulation tool was developed.

关键词： Heat Treatment Phase Transformation Stress Field Temperature Field Object-Oriented Programming

Effects of Solution Treatment on the Microstructure and mechanical Properties of Al-16.9Si-4.5Cu-0.15Mg Alloy

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稀有金属材料与工程 2011年第S3期40卷 73-77页

作者： Zhang Xun, Zhang Zhifeng, Xu Jun General research institute for Non-ferrous Metals (GRINM), beijing 100088, china Gen Res Inst Nonferrous Met GRINM Nonferrous Met Proc Div Beijing 100088 Peoples R China

In this paper, the microstructure and mechanical properties of Al-Si-Cu-Mg casting alloy under different solution conditions were investigated by optical metallographic and mechanical property test. The results show that the cast alloys were composed of α-Al, primary Si, eutectic Si, Al2Cu and Al7Cu2Fe phases. Three changes took place during solution treatment: Firstly, with the increase of solution temperature and the solution holding time extension, more and more Al2Cu phase was dissolved into the matrix; Secondly, with the increase of solution temperature and the solution holding time extension, morphology of eutectic Si, Al7Cu2Fe and other insoluble phases changed into more round; Thirdly, at the fixed solution temperature, if the solution time extended too long, it would cause grains, eutectic Si and other insoluble phases aggregated and coarsened. About mechanical properties, when the solution time was fixed, the hardness, tensile strength and the yield strength of the Al-Si-Cu-Mg alloy treated by T6 enhanced while the solution temperature increasing, and when the solution temperature was fixed, the ultimate tensile strength and the elongation of the Al-Si-Cu-Mg alloy treated by T6 increased at first and then decreased while the solution time increasing, but the hardness of the alloys affected less by the solution time.

关键词： Al-Si-Cu-Mg alloy solution treatment microstructure mechanical properties

Implantable CMOS neuro-stimulus chip for visual prosthesis

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Science china(Information Sciences) 2011年第4期54卷 898-908页

作者： ZHANG Xu 1,PEI WeiHua 1,HUANG BeiJu 1,WANG ShuJing 1,GUAN Ning 1,GUO Kai 1,WANG Yu 1,GUI Qiang 1,CHEN Jin 1,WANG Kai 2,WU HuiJuan 2,LI XiaoXin 2,LI Kai 3 & CHEN HongDa 1 1 State Key Laboratory on Integrated Optoelectronics,institute of Semiconductors,Chinese Academy of Sciences,beijing 100083,china 2 Department of Ophthalmology,People’s Hospital of Peking University,beijing 100044,china 3 Department of Epidemiology and Biostatistics,Health Science Center,Peking University,beijing 100083,china 1. State Key Laboratory on Integrated Optoelectronics Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China2. Department of Ophthalmology People’s Hospital of Peking University Beijing 100044 China3. Department of Epidemiology and Biostatistics Health Science Center Peking University Beijing 100083 China

A prototype chip with 2×2 pixels for implanting in blind patients affected by outer retinal degeneration is presented in this *** visual prosthesis chip imitates the degenerated photoreceptor cells,senses the incident light and stimulates the remaining healthy layers of retina or optic *** pixel integrates photodiode and stimulus pulse generator,converting the illumination on the eyes into 3-bit resolution bi-phasic current ***-chip charge cancellation modules are used to discharge each electrode site for tissue *** prototype chip is designed and fabricated in 0.18-μm N-well CMOS (complementary metal oxide semiconductor) 1P6M Mix-signal process,with a ±2.5 V dual voltage *** functionality of the fabricated chip is demonstrated on anesthetized *** responses in visual cortex are successfully evoked by the neuro-stimulus chip through an on-board trigger interface and flexible electrode.

关键词： biomedical microelectronics visual prosthesis functional electrical stimulation acute animal ex- periment electrical evoked potential (EEP) test

Low cycle fatigue behavior of high strength gun steels

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Journal of University of Science and technology beijing 2004年第3期11卷 268-272页

作者： Maoqiu Wang Han Dong Qi Wang Changgang Fan Division of Structural Materials, Central Iron & Steel research institute, beijing 100081, china Div. of Structural Mat. Central Iron and Steel Res. Inst. Beijing 100081 China

The low cycle fatigue (LCF) behavior of two high strength steels, withnominal chemical compositions (mass fraction, %) of 0.40C-1.5Cr-3Ni-0.4Mo-0.2V (PCrNi3MoV) and0.25C-3Cr-3Mo-0.8Ni-0.1Nb (25Cr3Mo3NiNb), was investigated by using the smooth bar specimenssubjected to strained-controlled push-pull loading. It is found that both steels show cyclicsoftening, but 25Cr3Mo3NiNb steel has a lower tendency to cyclic softening. 25Cr3Mo3NiNb steel hashigher fatigue ductility, and its transition fatigue life is almost three times that of PCrNi3MoV.25Cr3Mo3NiNb steel also shows higher LCF life either at a given total strain amplitude above 0.5% orat any given plastic strain amplitude, despite its lower monotonic tensile strength than that ofPCrNi3MoV. It also means that 25Cr3Mo3NiNb steel can endure higher total strain amplitude andplastic strain amplitude at a given number of reversals to failure within 10~4. 25Cr3Mo3NiNb steelis expected to be a good gun steel with high LCF properties because only several thousand firingsare required for gun barrel in most cases.

关键词： high strength steel low cycle fatigue mechanical property

PARAMETER IDENTIFICATION OF THERMAL VISCOPLASTIC MODEL CONSIDERING DYNAMIC RECRYSTALLIZATION

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PARAMETER IDENTIFICATION OF THERMAL VISCOPLASTIC MODEL CONSI...