栅格翼空化干扰水动力建模研究

对水下超空泡栅格翼水动力进行了研究.分析了叶片数、叶片间距、叶片厚度、叶片攻角和空化数对栅格翼水动力的影响.揭示了叶片间隙中的空泡流动对水动力的干扰机理.建立了超空泡栅格翼水动力数学模型,并用实验结果进行了验证.最后基于模型解释了实验中发现的栅格翼水动力变化规律.     

一种提高风能利用率的风力发电机控制策略

在变速恒频风力发电机组的各类并网逆变器控制策略中,零d轴电流控制和空间矢量脉宽调制(SVPWM)以能够提高风能利用系数和稳定逆变器输出电压的优势得到了广泛的应用.在理论研究阶段需要对其进行仿真,然而在Matlab/Simulink中并没有可以实现上述功能的并网仿真模型.因此推导了变速恒频风力发电机组及控制策略的数学模型,并在Matlab/Simulink中完成搭建、当风速恒定不变时,对发电系统的运行情况进行了仿真.结果表明,零d轴电流控制与SVPWM的结合,既提高了风能利用系数,又有效地提高了逆变器的输出电压,保证当电网电压升高时不影响发电系统向电网输送功率的效率.     

频散可控格式的一种推广形式及其在爆轰波马赫反射中应用

频散可控格式是高精度捕捉激波的新格式.对原有频散可控格式(DCD)进行了推广,给出了适用于网格点排列不规则情况下的DCD格式,使其具有更广泛的适应性,在此基础上构造了在非结构三角形网格下的DCD格式.用一些典型算例对推广后的DCD格式进行检验,结果表明该格式是合理和可靠的,并能够较好地保留原有DCD格式的二阶精度.把推广后的DCD格式和具有8种组分和20个化学反应的基元反应模型相结合,对氢氧爆轰波在直管道中的传播问题及楔面上马赫反射问题进行计算,计算结果和实验结果比较表明,在非结构三角形网格下的DCD格式能够有效地捕捉爆轰波,在爆轰波阵面上不会产生振荡或是抹平间断现象.     

Studies on the Gold-Coated Electrode with Grid

Introduction Thin-layer spectroelectrochemical method has many unique advantages, therefore this method has been widely applied and developed. Recently light transparent thinlayer spectroelectrochemical cells with various types of structures have been reported at home and abroad with gold or platinum minigrids as the working electrode in most of     

复合材料三角形网格加筋圆锥壳体位移型稳定性方程及其总体稳定性分析

本文采用Donnell型扁壳理论,首先利用最小势能原理和广义平均筋条刚度法推导出用位移分量表示的复合材料三角形网格加筋叠层圆锥壳体的稳定性方程,考虑了蒙皮最一般的拉弯与拉扭耦合关系和加筋筋条的偏心效应,并讨论了该方程的基本性质.根据外压实验观察结果,通过选取适当的位移分量表达式,并运用Galerkin法分析了在均布外压作用下复合材料三角形网格加筋叠层圆锥壳体总体稳定性,得到了临界载荷的解析表达式,并对某一类C/E复合材料三角形内网格加筋圆锥壳体的临界外压进行了计算,所得理论值与实验结果很好地吻合.最后,讨论了有关参数对临界载荷的影响.本文所建立的新方程和所得结果对于航空航天结构非常有用.     

平面斜激波固壁反射的镶嵌网格解法

镶嵌网格法是自适应网格法的一种。本文提出的镶嵌网格法以Ni的二阶有限体积法为基础,用密度一阶差分作为察觉激波的特征参数,给出网格局部加密(一分为四)的原则,构造了较节省存贮的数据结构。用于平面斜激波固壁反射的计算结果表明:镶嵌网格对激波的分辨能力不仅比粗网格强得多,而且也稍好于细网格;计算时间仅为细网格的一半稍多些.可见,此方法对解决计算效率和精度的矛盾是有利的。     

The axial symmetrical edge problems for thin-walled shells of revolution

In this paper, the uniformly valid asymptotic solutions for the axial symmetrical edge problems of thin-walled shells of revolution in bending are given.     

Bending of corner-supported rectangular plate under concentrated load

In this paper the solution for the bending of corner-supported rectangular plate under concentrated load at any point (α/2, η) of the middle line of the plate is given by means of a conception called modified simply supported edges and the method of superposition. Some numerical example is presented. The solution obtained by this method checks very nicely with what was obtained by G.T. Shih^[3] by means of spline finite element method when η=d/2. This shows that this method of solution is satisfactory.     

Decentralized Interaction and Co-Adaptation in the Repeated Prisoner&2018;s Dilemma

A Prisoner&2018;s dilemma that is repeated indefinitely has many equilibria; the problem of selecting among these is often approached using evolutionary models. The background of this paper is a number of earlier studies in which a specific type of evolutionary model, a genetic algorithm (GA), was used to investigate which behavior survives under selective pressure. However, that normative instrument searches for equilibria that may never be attainable. Furthermore, it aims for optimization and, accordingly, says what people should do to be successful in repeated prisoner&2018;s dilemma (RPD) type situations. In the current paper, I employ simulation to find out what people would do, whether this makes them successful or not. Using a replication of Miller&2018;s (1988) GA study for comparison, a model is simulated in which the population is spatially distributed across a torus. The agents only interact with their neighbors and locally adapt their strategy to what they perceive to be successful behavior among those neighbors. Although centralized GA-evolution may lead to somewhat better performance, this goes at the cost of a large increase in required computations while a population with decentralized interactions and co-adaptation is almost as successful and, additionally, endogenously learns a more efficient scheme for adaptation. Finally, when the agents&2018; perceptive capabilities are limited even further, so that they can only perceive how their neighbors are doing against themselves, rather than against all those neighbors&2018; opponents&2014;which essentially removes reputation as a source of information&2014;cooperation breaks down.     

Unstructured Adaptive Grid Flow Simulations of Inert and Reactive Gas Mixtures

Unstructured adaptive grid flow simulation is applied to the calculation of high-speed compressible flows of inert and reactive gas mixtures. In the present case, the flowfield is simulated using the 2-D Euler equations, which are discretized in a cell-centered finite volume procedure on unstructured triangular meshes. Interface fluxes are calculated by a Liou flux vector splitting scheme which has been adapted to an unstructured grid context by the authors. Physicochemical properties are functions of the local mixture composition, temperature, and pressure, which are computed using the CHEMKIN-II subroutines. Computational results are presented for the case of premixed hydrogen–air supersonic flow over a 2-D wedge. In such a configuration, combustion may be triggered behind the oblique shock wave and transition to an oblique detonation wave is eventually obtained. It is shown that the solution adaptive procedure implemented is able to correctly define the important wave fronts. A parametric analysis of the influence of the adaptation parameters on the computed solution is performed.