不同衬底上低温生长GaN形貌的AFM观察

　Aim　To study the relationship between the substrate temperature and the morphology and properties of GaN. Methods Applying the hydride chemical vapor deposition method, GaN films were deposited on different kinds of substrates, including sapphire, Si(111),Si(100),GaAs and GaP(111) both on the P face and the Ga face. The growth was performed at low temperatures of below 700℃. XRD, Hall measurement, cathodoluminescence (CL) and atomic force microscopy (AFM) were used to characterise the film properties. Results It was found that the temperature and the nature of substrate materials influence the layer morphology. Conclusion The analysis shows that no apparent relationship exists between the optical properties and layer morphology.     

燃料空气炸药近区抛散过程的研究

　Aim　To study fuel dispersion in fuel air explosive(FAE) and computational ways of fuel dispersion velocity in the near area. Methods The dispersion process of fuel in FAE was analyzed by the use of results measured with KODAK EKTAPRO EM Motion Analyzer and setting up mechanical models. Results Computational methods for fuel dispersion velocity in the acceleration stage is given and taken as a base for the study of fuel dispersion in the intermediate and the far area. Conclusion When the fuel flow velocity is higher than that of the explosion gas in the center cavity, the fuel divides with the explosion gas and its velocity of flow reaches a maximum. The acceleration stage ends at that time. The fuel dispersion velocity at this time is the initial conditions for numeral analyses of dispersion process in the intermediate and far areas.     

风险分析的尖点突变模型

　Aim　To assess simultaneously various risk states of a system. Methods Using the catastrophe and fuzzy theory, the energy and uncertainty in a system are set as two control variables and the function of the system is used as the state variable for analysis. Results and Conclusion A risk analysis model named the cusp model is presented. Various states regarding the safety of the system such as the accident state, no-accident state and miss state can be represented at will on the cusp model.     

基于DA算法的二维离散余弦逆变换的ASIC设计

　Aim　To present an ASIC design of DA-based 2-D IDCT. Methods In the design of 1-D IDCT is utilized a Chen-based fast IDCT algorithm, and multiplier accumulators based on distributed algorithm contributes in reducing the hardware amount and in enhancing the speed performance. Results and Conclusion VHDL simulation, synthesis and layout design of system are implemented. This 2-D IDCT ASIC design owns best timing performance when compared with other better designs internationally. Results of design prove to be excellent.     

节理岩体弹塑性动态有限元分析

　Aim　To study the elastic-plastic dynamical constitutive relations about a jointed rock mass under explosion load and its computer simulation. Methods Stress history is taken into account and stresses will follow changes in time during a period of explosion load. According to the principle of static force balance, the corresponding nodal concentrated force is calculated and the nodal displacement is counted. The elastic-plastic dynamic finite element equations are thus obtained. Results A finite element method is given for a jointed rock mass under explosion load. Conclusion The problem of large plastic deformation for jointed rock mass on blasting was efficiently resolved through dynamic finite element analysis and the range of damages by blasting simulated, and this pushes forward the problem to engineering practice.     

用于车辆传动的金属材料的疲劳试验及统计方法

　Aim　To improve the efficiency of fatigue material tests and relevant statistical treatment of test data. Methods Least square approach and other special treatments were used. Results and Conclusion The concepts of each phase in fatigue tests and statistical treatment are clarified. The method proposed leads to three important properties. Reduced number of specimens brings to the advantage of lowering test expenditures. The whole test procedure has more flexibility for there is no need to conduct many tests at the same stress level as in traditional cases.     

极性反转瞬态电场的数值算法及应用

　Aim　To analyze the transient speciality of nonlinear, anisotropic, AC+DC coupling electric field, and to compare the withstand-voltage strength of different insulation structures. Methods The transient process of polarity reversal is analyzed, considering the anisotropic property of oil-immersed press-board, a new finite element model based on Galerkin method is presented and verified. The model developed is applied to calculate the electric field distribution in four typical winding end structures of the converter transformer. Results The whole-ring structure possesses the best insulation characteristics. Conclusion By introducing reasonable insulation components, insulation strength with the same surrounding sizes can be improved more than 30%.     

矿井通风网络分析的遗传算法

　Aim　To determine the global optimal solution for a mine ventilation network under given network topology and airway characteristics. Methods The genetic algorithm was used to find the global optimal solution of the network. Results A modified genetic algorithm is presented with its characteristics and principle. Instead of working on the conventional bit by bit operation, both the crossover and mutation operators are handled in real values by the proposed algorithms. To prevent the system from turning into a premature problem, the elitists from two groups of possible solutions are selected to reproduce the new populations. Conclusion The simulation results show that the method outperforms the conventional nonlinear programming approach whether from the viewpoint of the number of iterations required to find the optimum solutions or from the final solutions obtained.     

动态系统的自适应模糊神经网络控制

　Aim　To build an adaptive fuzzy neural controller and simulate it. Methods Fuzzy logic and back propagation(BP) algorithm are combined to utilize their advantages while avoiding the disadvantages. Results and Conclusion Simulation results of the third-order plant with disturbances and dead times show the validity of the presented controller. The presented controller can control cases that preceding controllers were unable to control.     

约束系统特性对乘员碰撞响应影响的仿真研究

　Aim　To study the influence of restraint system performance upon the occupant's response during impact, and provide a scientific base for occupant restraint system design. Methods In the light of basic theory of multibody system dynamics and impact dynamics on the basis of classical theory of impact, R-W method is adopted to construct the vehicle-occupant system model consisting of fourteen rigid bodies, thirty seven DOFs and slip joints for the simulation. A software named SVC3D(3-dimensional simulation of vehicle crash) is developed in the FORTRAN language. Results The results of simulation have a good coincidence with those of tests and the restraint system with low elongation webbing and equipped with pretensioner provides better restraint effect for the occupant. Conclusion The model of vehicle-occupant multibody system and SVC3D are suitable for use. Occupant should be belted with low elongation webbing to a certain degree and occupant restraint system should be equipped with pretensioner.     

Effect of Thermal Treatment on the PA 6 in the Blends

目的研究热处理条件对尼龙６及其在线性低密度聚乙烯共混物中的结晶非晶态样品的结晶熔融行为．方法采用ＤＳＣ技术探讨退火温度、退火时间、ＤＳＣ扫描速率以及连续多步退火等因素与尼龙６组分的熔融行为的相互关系．结果与结论存在一个临界ＤＳＣ扫描速率,对尼龙６的中间熔融峰有较大的影响．在尼龙６的熔点温度附近退火后,尼龙６的主熔融峰向高温方向移动．短时间退火处理对纯尼龙６的熔融行为比对共混物中尼龙６的影响大,与聚乙烯共混使得尼龙６的熔融峰的峰高明显降低。尼龙６的熔融行为与聚乙烯、相容剂和热处理条件都有关     

由非晶态结晶的尼龙6 及其共混物的熔融行为

目的研究尼龙6及其与线性低密度聚乙烯共混物的非晶样品的熔融行为. 方法采用DSC技术探讨了退火温度、退火时间、DSC扫描速率、以及连续多步退火等因素与冰水淬火样品中的尼龙6组分的熔融峰间的相互关系. 结果与结论上述因素对尼龙6组分的熔融行为有较大的影响,共混使尼龙6的结晶度和结晶完善度降低,随退火时间的延长结晶度提高. 与纯尼龙6相比,共混物中高温熔融峰的峰高明显降低.     

Melting Behavior of PA6 and PA6/PE Blends Crystallized from Amorphous State

目的研究尼龙６及其与线性低密度聚乙烯共混物的非晶样品的熔融行为．方法采用ＤＳＣ技术探讨了退火温度、退火时间、ＤＳＣ扫描速率、以及连续多步退火等因素与冰水淬火样品中的尼龙６组分的熔融峰间的相互关系．结果与结论上述因素对尼龙６组分的熔融行为有较大的影响,共混使尼龙６的结晶度和结晶完善度降低,随退火时间的延长结晶度提高．与纯尼龙６相比,共混物中高温熔融峰的峰高明显降低．     

Isothermal crystallization kinetics and melting behavior of poe-g-mah compatibilized PA11/POE blends

A new Nylon 11(PA11)/polyethylene-octene(POE) blends compatibilized by maleic anhydride grafted mixture polyethyleneocten(POE-g-MAH) was prepared through melt blending method.The isothermal crystallization kinetics and melting behaviors of PA11/POE blends were investigated in detail by differential scanning calorimetry(DSC) and polarized optical microscope.The n values of PA11 blending with POE or POE-g-MAH are almost similar with pure PA11,which indicates that the effect of POE and POE-g-MAH on nucleation and growth of PA11 crystal is slight.The overall crystallization rate of PA11/POE blends are higher than ones of pure PA11 at the same crystallization temperatures,but they decrease significantly when POE-g-MAH is added into PA11/POE blends.DSC heating curves of both PA11 and its blends exhibit two melting peaks,but the two melting peak become weaker when POE-g-MAH is add into PA11/POE blend systems.And the spherulite size is reduced significantly by the addition of POE-g-MAH compared with pure PA11 and PA11/POE blends.     

PA6/66/1010三元共聚酰胺流变性能

将PA6/PA66/PA1010按一定的比例混合进行共聚,制得低熔点共聚酰胺。对制得的低熔点共聚酰胺进行流变分析,与PA6的流变曲线进行比较。实验结果表明:共聚物的流变曲线与PA6的相似,都表现出切力变稀的行为。与PA6相比,共聚物的流变曲线表现出更明显的切力变稀行为。在同样的高出熔点45℃的条件下,在同样的剪切速率下,共聚物表现出更大的表观粘度。     

尼龙6／聚丙烯共混物结构与性能研究

采用FT－IR,SEM,DSC和力学性能测试研究了力化学方法制备的聚丙烯接枝马来酸酐（PP－g-MAH）对尼龙6（PA6）／聚丙烯（PP）共混体系的增容作用。结果表明,在共混过程中,PA6与PP－g-MAH之间发生了相互作用,使增容共混体系的力学性能明显优于未增容体系,增容体系分散相（PP相）粒度明显低于未增容体系,熔融粘度高于未增容体系,增容共混体系PP和PA6的熔点和结晶度低于未增容体系。     

尼龙6/聚丙烯共混物结构与性能研究

采用FTIR, SEM, DSC 和力学性能测试研究了力化学方法制备的聚丙烯接枝马来酸酐(PPgMAH)对尼龙6(PA6)/聚丙烯(PP)共混体系的增容作用.结果表明,在共混过程中,PA6与PPgMAH之间发生了相互作用,使增容共混体系的力学性能明显优于未增容体系,增容体系分散相(PP相)粒度明显低于未增容体系,熔融粘度高于未增容体系,增容共混体系PP和PA6的熔点和结晶度低于未增容体系.     

热致聚酰胺液晶与尼龙6复合材料的相容性

采用共溶剂法制备了实验室自行合成的热致液晶聚酰胺(TLCP)与尼龙6(PA6)的复合材料。通过乌氏黏度计、DSC、FT-IR以及SEM等方法分析了复合材料的相容性。加入TLCP后,共混物的特性黏度增加,熔点下降,熔融焓降低;红外图谱证实了TLCP与PA6之间存在分子间氢键作用;SEM的结果表明,当w(TLCP)≥5%时,两相界面模糊,当w(TL-CP)=40%时,共混物呈均相体系,无相分离。以上结果均证实,在不添加第三相增容剂的情况下,引入分子间氢键的作用可以制备出具有良好相容性的PA6/TLCP复合材料。     

成核剂对生物降解聚乳酸结晶行为的影响

采用DSC和POM对聚乳酸及聚乳酸／成核剂体系的结晶行为进行了研究。结果表明,一定温度范围下,等温结晶后的各样品在熔融时,均出现两个熔融峰。含滑石粉的样品出现两个熔融峰所需温度要比其它样品所需温度约低10℃。3种成核剂都有利于提高聚乳酸的结晶速度和结晶度,其中滑石粉的效果最显著。在125℃时滑石粉的加入使得t1／2从7．78min缩短到3．33min,tmax从7．84min缩短到3．18min;相同保温时间时（130℃,10min）,结晶度约提高了19％。而戍核剂对改变聚乳酸等温结晶过程的成核机理和生长方式无明显影响。     

尼龙6与苯乙烯-马来酸酐共聚物接枝反应研究

通过研究溶液接枝反应制备了尼龙6（PA6）与苯乙烯-马来酸酐（SMA）共聚物（PA6-g-SMA），研究了SMA/尼龙6质量比、反应温度、反应时间对产物接枝率及熔点的影响。结果表明，产物的接枝率受反应温度的影响较大，其熔点随接枝率的升高而降低；接枝率为5.12%，熔点为193.5℃。