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Characteristic analysis of unsteady viscous flow around a cavitating propeller

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Science china(Technological Sciences) 2010年第7期53卷 1983-1992页

作者： ZHU ZhiFeng1, 2, FANG ShiLang1 & WANG XiaoYan1 1 key laboratory of underwater acoustic signal processing of ministry of education, southeast university, nanjing 210096, china 2 School of Electrical Engineering and Information, Anhui university of Technology, Maanshan 243002, china key laboratory of underwater acoustic signal processing of ministry of education Southeast University School of Electrical Engineering and Information Anhui University of Technology

Based on viscous multiphase flow theory, this paper presents some recent validation results with a hybrid grid and sliding mesh solving Unsteady Navier-Stokes (N-S) and Bubble Dynamics equations as applied to prediction of pressure, velocity and vapor volume fraction in the wake in an uniform inflow. Comparable to experimental results, numerical predictions of sheet cavitation, tip vortex cavitation and hub vortex cavitation are in agreement with the corresponding experimental data, the same as numerical predictions of pressure in wake. Tip vortex cavitation is the most important to generate the pressure fluctuation within the near wake. The characteristics such as blade and shaft rate frequency of propeller pressure in wake coincide with its geometric model and parameters. With increasing distance from propeller disk, the pressure signals at blade frequency de-crease. The process of attenuation becomes fast with the decreased advance coefficient and cavitation number.

关键词： cavitating flow RANS propeller sliding mesh multiphase flow

Effects of Meat and Phosphate Level on Water-Holding Capacity and Texture of Emulsion-Type Sausage During Storage

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Agricultural Sciences in china 2009年第12期8卷 1475-1481页

作者： WANG Peng,XU Xing-lian and ZHOU Guang-hong key laboratory of Meat processing and Quality Control,ministry of education/nanjing Agricultural university,nanjing 210095,P.R.china key laboratory of Meat processing and Quality Control Ministry of Education/Nanjing Agricultural University Nanjing 210095 P.R. China

This paper was designed to verify the influence of phosphate on water-holding capacity （WHC） and texture of emulsiontype sausage prepared with pre-rigor meat, ageing meat or frozen meat. Pre-rigor pork, ageing pork and frozen pork were pre-blended with five levels of phosphate and made into emulsion-type sausage. The yield, hardness and total expressible fluid （TEF） were measured with texture profile analysis machine and pressiometer when emulsion-type sausage was produced. Meanwhile, hardness and purge loss （PL） were measured during 30 d storage. As emusion-type sausage made by pre-rigor meat, higher yield and relatively stable hardness could be found. It indicated that increasing of phosphate level caused an alleviatable effects in increasing of hardness when emulsion-type sausage made by pre-rigor meat, but opposite effects made by ageing meat or frozen meat. The distribution of PL of emulsion-type sausage was found to be affected by phosphate addition. Significant decrease of PL could not be obtained by increasing of phosphate level during storage. Pre-rigor meat improved WHC and texture of emulsion-type sausage. Problem of WHC and texture of emulsiontype sausage during storage could not be resolved by single use of phosphate at relatively higher level （3%） of NaCl.

关键词： meat emulsion-type sausage water-holding capacity texture

Silicon-based microelectrode arrays for stimulation and signal recording of in vitro cultured neurons

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Science china(Information Sciences) 2011年第10期54卷 2199-2208页

作者： PAN HaiXian 1,L XiaoYing 1 ,WANG ZhiGong 2,REN TianLing 3,FANG Tao 1,ZHANG Jie 1,ZHOU ChangJian 3 & WANG LiGang 3 1 State key laboratory of Bioelectronics,southeast university,nanjing 210096,china 2 Institute of RF-& OE-ICs,southeast university,nanjing 210096,china 3 Institute of Microelectronics,Tsinghua university,Beijing 100084,china State key laboratory of Bioelectronics Southeast University Nanjing China Institute of RF-& OE-ICs Southeast University Nanjing China Institute of Microelectronics Tsinghua University Beijing China

Microelectrode arrays (MEAs) for stimulation and signal recording of in vitro cultured neurons are *** MEA is composed of 60 independent electrodes with 59 working ones and one reference *** electrodes are divided into 30 *** each pair of electrodes,four independent states can be realized to define the accessing modes of neurons cultured on the surface of the electrodes.A total MEA covers an area of 10 mm×10 *** are fabricated in a silicon-based semiconductor *** implemented MEA is bonded on a specially designed printed-circuit-board (PCB) and surrounded by a culture *** impedance measurement has been made to verify the electrical characteristics of *** surface was modified to enhance the biocompatibility.A series of PC12 cells culture experiments validates the effectiveness of the *** extracellular signal recording experiment with acetylcholine (Ach) as a stimulant has been carried out,and the results show the feasibility of MEAs for extracellular action potential *** electrical stimulation and recording experiments have been carried out *** indicate that MEAs can be used for extracellular stimulation,recording,simultaneous stimulation and recording,and isolation of PC12 cells network cultured in vitro.

关键词： microelectrode arrays (MEAs) extracellular recording stimulation and recording neurons net-work in vitro

Preparation of nanoparticles with an environment-friendly approach

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Journal of Environmental Sciences 2009年第6期21卷 727-730页

作者： YAO Kefu,PENG Zhen,FAN Xiaolin key laboratory of Advanced Materials processing Technology,ministry of education of china,Department of Mechanical Engineering,Tsinghua university,Beijing 100084,china. key laboratory of Advanced Materials processing Technology Ministry of Education of China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

Developing various approaches for preparing high performance materials has long been topics and tasks both for scientists and for engineers. Despite that many methods have been developed for preparing nanomaterials, developing simple and environment-friendly ways for preparing nanomaterials is very attractive. Here a simple approach of synthesizing Fe3O4 nanoparticles by arc-discharge submerging in water was reported. The results showed that by this method Fe3O4 nanoparticles can be synthesized at large scale. The as-prepared Fe3O4 nanoparticles exhibited uniform spherical shape and their diameters varied with arc-discharging parameters. The experimental results showed that the size of the synthesized Fe3O4 nanoparticles can be controlled through adjusting the processing parameters. Since no vacuum system has been used, the synthesizing process is greatly simplified. In addition, only cheap deionized water and industrial iron bar are used and no pollution or harmful byproducts are found in the synthesis process. It indicated that the present approach is a simple, low-cost and environment-friendly one for preparing nanoparticles.

关键词： nanoparticles preparation approach Fe3O4

Influence of Alternative Magnetic Field on the Diffusion of Al and Mg

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Journal of Materials Science & Technology 2004年第4期20卷 457-459页

作者： Xiaotao LIU, Jianzhong CUI, Yanhui GUO, Xiaoming WU and Jun ZHANGThe key laboratory of Electromagnetic processing of Materials, ministry of education, Northeastern university, Shenyang 110004, china Mat. Electromagnetic Proc. Lab. Northeastern Univ. Shenyang 110004 China

The influence of an alternative magnetic field on the diffusion of Al and Mg in AI-Mg diffusion couple is studied. The diffusion zone is composed of two intermediate phases, namelyβ and γ phase. Thickness of each intermediate phase is examined. The results show that the alternative magnetic field increases the thicknesses of βand γ phase zone and the layer growth ofβ and γphase obeys the parabolic rate law. The growth rate of the β and γ phase are increased with the application of the alternative magnetic field. This change is manifested through a change in the frequency factor k0 and not through a change in the activation energy Q. The frequency factor k0 for intermediate phase growth with an alternative magnetic field is 39.95 cm2/s for 7 phase and 2.84×10-4 cm2/s for β phase compared with those without the magnetic field is 22.4 cm2/s for 7 phase and 1.53×10-4 cm2/s for β phase.

关键词： Alternative magnetic field Al-Mg Couple Intermediate phase Thickness Diffusion

Tissue P systems with cell separation: attacking the partition problem

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Science china(Information Sciences) 2011年第2期54卷 293-304页

作者： ZHANG XingYi1, WANG Shuo2, NIU YunYun2 & PAN LinQiang2 1key Lab of Intelligent Computing and signal processing of ministry of education, School of Computer Science and Technology, Anhui university, Hefei 230039, china 2Image processing and Intelligent Control key laboratory of education ministry of china, Department of Control Science and Engineering, Huazhong university of Science and Technology, Wuhan 430074, china key Lab of Intelligent Computing and signal processing Ministry of Education School of Computer Science and Technology Anhui University Image processing and Intelligent Control key laboratory Education Ministry of China Department of Control Science

Tissue P systems are distributed parallel and non-deterministic computing models in the framework of membrane computing, which are inspired by intercellular communication and cooperation between neurons. Recently, cell separation is introduced into tissue P systems, which enables systems to generate an exponential workspace in a polynomial time. In this work, the computational power of tissue P systems with cell separation is investigated. Specifically, a uniform family of tissue P systems with cell separation is constructed for effciently solving a well-known NP-complete problem, the partition problem.

关键词： membrane computing tissue P system cell separation partition problem

Effects of solidification parameters on microstructure and mechanical properties of continuous columnar-grained Cu-Al-Ni alloy

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Progress in Natural Science:Materials International 2011年第5期21卷 368-374页

作者： Zhen WANG,Xue-feng LIU,Jian-xin XIE key laboratory for Advanced Materials processing,ministry of education, university of Science and Technology Beijing,Beijing 100083,china key laboratory for Advanced Materials processing Ministry of Education University of Science and Technology Beijing Beijing 100083 China

Effects of melt temperature and casting speed on microstructure and mechanical properties of Cu-14%Al-3.8%Ni(mass fraction) alloy wires fabricated by continuous unidirectional solidification technology were *** was found that the average size of columnar grain in the alloy decreased and grain boundary turned clear and straight with increasing the casting speed at a given melt *** the melt temperature was up to 1 280℃,theβ1phase gradually transformed into lozenged and lanciformγ’1martensite,as well as parallel-sided plateβ’*** alloy with numerous coarsely dendriticγ2phase has poor mechanical properties due to the difficulty of stress-induced martensitic *** the amount of theγ2phase reduced and the coarse dendriteγ2phase evolved into the fine square particles,the elongation of the alloy increased gradually with a decrease in tensile ***,the plasticity of the alloy could also be improved by increasing the amount and size of martensites,particularly the lanciformγ’*** the alloy was almost composed of coarse lanciformγ’1martensite,the tensile strength and elongation of the alloy could be up to 772 MPa and 18.9%,respectively,and the tensile curve consisted of three transformation platforms.

关键词： shape memory alloy continuous unidirectional solidification columnar grain martensitic transformation

ULTRASONIC SEPARATION OF MICRO-SIZED INCLUSIONS IN MOLTEN METAL

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Acta Metallurgica Sinica(English Letters) 2001年第5期14卷 375-379页

作者： X.Q. Bai and J.C. He key laboratory of National education ministry for Electromagnetic processing of Materials, Northeastern university, Shenyang 110004, china key laboratory of National education ministry for Electromagnetic processing of Materials Northeastern University

The coagulation time and position of micro-sized non-metallic inclusions in molten metal during ultrasonic separation process were investigated, and the motion course of micro-sized non-metallic inclusions in an ultrasonic standing wave field was numerically simulated. The results of theoretical analysis and numerical simulation show that the movement of inclusions depends on the balance between the acoustic radiation force, effective buoyancy force and viscous drag force. It is presented that micro-sized inclusions, agglomerated at antinode-planes may be removed further with horizon tal ultrasound.``

关键词： ultrasound molten metal micro-sized non-metallic inclusion numerical simulation process parameter

Effects of Pre-Ageing Treatment on Subsequent Artificial Ageing Characteristics of an Al-1.01Mg-0.68Si-1.78Cu Alloy

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Journal of Materials Science & Technology 2010年第2期26卷 141-145页

作者： Lizi He , Haitao Zhang and Jianzhong Cui key Lab of Electromagnetic processing of Materials, ministry of education, Northeastern university, Shenyang 110004, china key Lab of Electromagnetic processing of Materials Ministry of Education Northeastern University

The influences of pre-ageing temperature and natural ageing time on subsequent artificial age hardening behavior and precipitation sequence of new type Al-1.01Mg-0.O8Si-l.78Cu alloy were investigated by hardness test, differential scanning calorimetry （DSC） test and transmission electronic microscopy （TEM） observations. When pre-ageing temperature is 20℃ （natural ageing）, the peak hardness of subsequent artificial aged alloy is lower than that of T6 treated alloy （negative effect）, while a positive effect appears when pre-ageing temperature is above 80℃. The size of needlelike /3-precipitate in subsequent artificial aged alloy is much coarser when pre-ageing temperature is 20℃, which causes a decrease in peak-hardness. The positive effect occurs again when natural ageing time is longer than 3 weeks. There are seven exothermic peaks in DSC curve of as-quenched alloy, while the number and height of exothermic peak decrease with increasing pre-ageing temperature and natural ageing time.

关键词： Al-Mg-Si-Cu alloy Pre-ageing treatment Age hardening Differential scanning calorimetry (DSC) curve