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Preparation and crystallization control of nanoparticle hydroxyapatlte

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Journal of University of Science and Technology Beijing 2004年第5期11卷 449-454页

作者： LianfengGuo WenguangZhang ChengtaoWang schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghai200030China

Nanoparticle hydroxyapatite was prepared by a wet chemical precipitationmethod. The effects of different synthesis conditions, i.e. contents of reagents (0.2, 0.5 and 0.8mol/L), reaction temperatures (20, 37, 55 and 75 deg C) and reaction time (0-24 h), were studiedbased on crystallization process analysis and the effects of washing methods (with water or alcohol)were also studied. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD),transmission electron microscopy (TEM), electron diffraction (ED) and inductively coupled plasmaspectroscopy (ICP) were used to characterize the powders. Chemical analysis shows that the purity ofthe precipitated hydroxyapatite largely depends on reaction time. X-ray diffraction and TEMmicrographs results show that reaction temperature is a key factor affecting crystallinity,morphology and particle size. Degree of supersaturation and stirring also affects thecrystallization. Particles are in a shape of short rod and have a size of 20-40 nm in length at 20deg C and 37 deg C, but acicular morphology and a size of 150-170 nm in length at 75 deg C.Particles are monocrystalline at 20 deg C and 37 deg C, and are poly-crystalline at 55 deg C and 75deg C. The results show that stoichiometry hydroxyapatite with controlled particle size, morphologyand crystallinity can be obtained by carefully controlling the reaction conditions.

关键词： precipitation hydroxyapatite crystallization nanoparticle biomaterial

CONTINUOUS WAVELET TRANSFORM OF TURBULENT BOUNDARY LAYER FLOW

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Journal of Hydrodynamics 2005年第3期17卷 358-361页

作者： LIUYing-zheng KEFeng CHENHan-ping schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghai200030China

The spatio-temporal characteristics of the velocity fluctuations in a fully-developed turbulent boundary layer flow was investigated using hotwire. A low-speed wind tunnel was established. The experimental data was extensively analyzed in terms of continuous wavelet transform coefficients and their auto-correlation. The results yielded a potential wealth of information on inherent characteristics of coherent structures embedded in turbulent boundary layer flow. Spatial and temporal variations of the low- and high- frequency motions were revealed.

关键词： turbulent boundary layer continuous wavelet transform coherent structure

Microstructure Evolution and Cracking Control of 316L Stainless Steel Manufactured by Multi-layer Laser Cladding

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材料热处理学报 2004年第5B期25卷 1013-1016页

作者： SONGJian-li DENGQi-lin HUDe-jin SUNKang-kai ZHOUGuang-cai schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghaiChina schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghaiChina／／SchoolofMaterialScienceandEngineeringTaiyuanHeavyMachineryInstituteTaiyuanChina

Multi-layer laser cladding manufacturing is a newly developed rapid manufacturing technology. It is a powerful tool for direct fabrication of three-dimensional fully dense metal components and part repairing. In this paper, the microstructure evolution and properties of 316L stainless steel deposited with this technology was investigated, compact components with properties similar to the as-cast and wrought annealed material was obtained. Cracking was eliminated by introducing of supersonic vibration and application of parameter adjustment technologies.

关键词：激光包覆显微结构 316L不锈钢裂纹控制

FRACTAL CHARACTERISTICS OF AERODYNAMIC FIELD AT OUTLET OF LOW-NO_x COAXIAL SWIRLING BURNER

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Journal of Hydrodynamics 2004年第1期16卷 67-73页

作者： WUJiang TIANFeng-guo ZHANGMing-chuan SONGYu-bao GAOMao YINBin schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghai200240China／DepartmentofPowerEngineeringShanghaiUniversityofElectricPowerShanghai200090China schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghai200240China

The primary wind of a low-NO_x coaxial swirling burner was visualized byusing glycol as smog tracer. The information of the visual flow field was input into a computerthrough image-capturing card with CCD camera as the image-capturing element. The boundary of thevisual zone, i. e. , the interface of the primary wind and secondary wind was obtained by imageprocessing. The fractal dimension (FD) of the boundary was examined and found to vary from 1. 10 to1. 40 with S_1, S_2 and ζ_1 . It is concluded that when FD is small, the complex level of theinterface is low, and mixture between the primary and secondary wind is weak near the exit of theburner at the initial phase of combustion resulting in stratified flow; when FD is big, mixturebecomes strong near the exit of the burner. It is showed that the flow with FD ranging from 1.10 to1. 20 is stratified flow, which is benefical to reduce NO_x yield and the flow with FD from 1. 25 to1. 40 is mixed flow, producing much NO_x. The mechanism of the forming of stratified flow and mixedflow was theoretically analyzed. The corresponding S_1 , S_2 and ζ_1 of these flows were given.

关键词： low-NO_x burner aerodynamic field visual experiment image processing fractal characteristics stratified flow

HC-PM COUPLING MODEL FOR PARTICULATE MATTER EMISSION OF DIESEL ENGINES

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Chinese Journal of Mechanical Engineering 2005年第2期18卷 297-301页

作者： TanPiqiang LuJiaxiang DengKangyao schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghai200030China

A rapid, phenomenological model that predicts paniculate matter (PM) emissionof diesel engines is developed and formulated. The model is a chemical equilibrium compositionmodel, and is based on the formation mechanisms of PM and unburned hydrocarbon (HC) emissions ofdiesel engines. It can evaluate the emission concentration of PM via the emission concentration ofHC. To validate the model, experiments are carried out in two research diesel engines. Comparisonsof the model results with the experimental data show good agreement. The model can be used toevaluate the concentration of PM emission of diesel engines under lack of PM measuring instruments.In addition, the model is useful for computer simulations of diesel engines, as well as electroniccontrol unit (ECU) designs for electronically controlled diesel engines.

关键词： Diesel engine Particulate matter Modeling Hydrocarbon

INTERFERENCE-FREE TOOL POSTURE GENERATION FOR 5-AXIS NC MILLING FREE-FORM SURFACES WITH CYLINDRICAL MILL

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Chinese Journal of Mechanical Engineering 2004年第3期17卷 381-384页

作者： ChenLiping ChenYan HuDejin schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghai200030China SchoolofEnergyandPowerEngineering Xi＇anJiaotongUniversityXi＇an710049China schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghai200030China

The 5-axis NC machining offers the potential of efficient and accuratemachining. However, the present CAM system for 5-axis control is still an unsolved problem due tointerference between tool and surrounding objects. A new method is presented. There are two steps inthis procedure. First, it detects the interference by calculating the shortest distance between thetool-axis and the surrounding surfaces. Then upon the maximum gouging, the interference-free toolposture for 5-axis NC cylindrical milling free-form surfaces is obtained by adjusting tool. Thevalidity of the proposed method has been confirmed by machining an impeller.

关键词： NC machining Interference avoidance Computer aided manufacturing

OPTIMIZATION APPROACH FOR HYBRID ELECTRIC VEHICLE POWERTRAIN DESIGN

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Chinese Journal of Mechanical Engineering 2005年第1期18卷 30-36页

作者： ZhuZhengli ZhangJianwu YinChengliang schoolofmechanicalandpowerengineering ShanghaiJiaotongUniversityShanghai200030China

According to bench test results of fuel economy and engine emission for thereal power-train system of EQ7200HEV car. a 3-D performance map oriented quasi-linear model isdeveloped for the configuration of the powertrain components such as internal combustion engine,traction electric motor, transmission, main retarder and energy storage unit. A genetic algorithmbased on optimization procedure is proposed and applied for parametric optimization of the keycomponents by consideration of requirements of some driving cycles. Through comparison of numericalresults obtained by the genetic algorithm with those by traditional optimization methods, it isshown that the present approach is quite effective and efficient in emission reduction and fueleconomy for the design of the hybrid electric car powertrain.

关键词： Hybrid electric vehicle(HEV) Powertrain Components sizing Optimization Genetic algorithm

LOCATORS OPTIMIZATION FOR MEASURING FIXTURE DESIGN

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Chinese Journal of Mechanical Engineering 2004年第3期17卷 332-335页

作者： WangJian ZhouJiangqi LinZhongqin BodyManufacturingTechnologyCenter SchoolofMechanicalandPowerEngineeringShanghaiJiaotongUniversityShanghai200030China

'N-2-1' principle is widely recognized in the fixture design for deformablesheet metal workpieces, where N, the locators on primary datum, is the key to sheet metal fixturedesign. However, little research is done on how to determine the positions and the number of Nlocators. In practice, the N locators are frequently designed from experience, which is oftenunsatisfactory for achieving the precision requirement in fixture design. A new method to lay outthe N locators for measuring fixture of deformable sheet metal workpiece is presented, given thefixed number of A'. Finite-element method is used to model and analysis the deformation of differentlocator layouts. A knowledge based genetic algorithm (KBGA) is applied to identify the optimumlocator layout for measuring fixture design. An example of a door outer is used to verify theoptimization approach.

关键词： Compliant part Optimization Genetic algorithm Measuring fixture

MODEL IMPROVEMENT AND EXPERIMENT VALIDATION OF PNEUMATIC ARTIFICIAL MUSCLES

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Chinese Journal of Mechanical Engineering 2004年第1期17卷 36-39页

作者： ZhouAiguo ShiGuanglin ZhongTingxiu InstituteofMechatronics SchoolofMechanicalandPowerEngineeringShanghaiJiaotongUniversityShanghai200030China

According to the deficiency of the present model of pneumatic artificialmuscles (PAM), a serial model is built up based on the PAM's essential working principle with theelastic theory, it is validated by the quasi-static and dynamic experiment results, which are gainedfrom two experiment systems. The experiment results and the simulation results illustrate that theserial model has made a great success compared with Chou's model, which can describe the forcecharacteristics of PAM more precisely. A compensation item considering the braid's elasticity andthe coulomb damp is attached to the serial model based on the analysis of the experiment results.The dynamic experiment proves that the viscous damp of the PAM could be ignored in order to simplifythe model of PAM. Finally, an improved serial model of PAM is obtained.

关键词： Pneumatic artificial muscles Serial model Quasi-static Dynamic Compensation