人工航道对波浪传播规律的影响

波浪在传播过程中,遇到建筑物和地形变化时,会发生绕射与折射,对波浪的传播、变形具有显著的影响。作者建立了基于Boussinesq方程的波浪数学模型。采用所建立的数学模型对双突堤条件下有、无航道时港内的波浪分布分别进行了数值计算,并将上述两种条件下的波浪分布情况进行了比较。结果表明,开挖航道对波浪的传播变形影响较大,不能用纯绕射来代替波浪的折、绕射联合作用。     

矩阵方程AX-XB=C的一般解

在控制论、线性统计等领域中会涉及到线性矩阵方程AX-XB=C,当该矩阵方程满足相容性条件时,可利用矩阵的Kronecker积理论给出该矩阵方程的广义逆形式的解。     

基于SEM的雾霾天气对大学生交通出行影响研究

大学生群体是较为特殊的群体,几乎不拥有私家车,多采用公共交通出行,且多为弹性出 行,更易受到雾霾等外部因素的影响。鉴于此,针对大学生群体,研究雾霾天气下影响其出行的关键因素以及雾霾天气对其出行各方面（如出行时间、出行次数等） 的影响及影响程度。在大学 生问卷调查的基础上,运用计划行为理论,建立结构方程模型,研究雾霾天气下大学生出行行为特征。运用AMOS21.0 及SPSS20.0 软件,对结构方程模型进行实证分析及检验拟合。研究结果表明：雾霾天气下,出行者的心理状况和对雾霾天气的敏感程度是影响大学生出行的关键因素;雾霾天气会导致出行者出行行为的改变,其中对出行时间的影响最大,其次是出行次数,对出行方式的影响最小。     

Three-dimensional numerical wave tank simulations on fully nonlinear wave–current–body interactions

A finite-difference scheme and a marker-and-cell (MAC) method are used for numerical wave tank (NWT) simulations to investigate the characteristics of nonlinear wave motions and their interactions with a stationary three-dimensional body in the presence of steady uniform currents. The Navier–Stokes (NS) equation is solved in the computational domain, and the boundary values are updated at each time-step by a finite-difference time-marching scheme in the frame of a rectangular coordinate system. The fully nonlinear kinematic free-surface condition is satisfied by the marker–density function technique developed for two fluid layers. The incident waves are generated from the inflow boundary by prescribing a velocity profile resembling the motions of a flexible flap wavemaker, and the outgoing waves are numerically dissipated inside an artificial damping zone located at the end of the tank. Using the NS–MAC NWT, nonlinear wave and current interactions around a stationary vertical truncated circular cylinder are studied, and the results are compared with the experimental results of Mercier and Niedzwecki, a time-domain NWT based on linear potential theory, a fully nonlinear NWT, and a second-order diffraction computation. Received: July 3, 2001 / Accepted: September 25, 2001     

利用二维缓流扰动基本方程探讨渠道涌波影响因素

运用水流运动基本方程,探讨了发生涌波的小扰动椭圆型方程条件,推导了求解椭圆型方程的方法及流动过程的扰动要素,为研究渠系交叉建筑物进口段涌波提供了一定的理论依据。     

色散方程两层稳定的偏心隐格式

利用组合差商法对色散方程ut=auxxx的初边值问题,构造了两组带参数两层四点偏心隐式差分格式PL2,PR2,其截断误差为ο(τ h2),稳定性随参数变化而变化。特殊的,若令某个节点前的系数为0,则得到二阶的半显格式。最后的数例既验证了理论分析的正确性,也说明了特取参数可以增强格式应用的灵活性。     

火箭发动机推力室粘性流场数值模拟及实验

用时间相关法的显式格式,结合k-ε方程湍流模型求解氢氧火箭发动机燃烧室中的粘性化学反应流动,化学反应采用9种组分,5个主要反应的有限速率的化学反应模型,得到了流动参数与组分的质量分数在燃烧室中的分布情况.其结果同理论分析的结果相一致,对火箭发动机燃烧室的压力和推力室的推力在启动段、关机段进行了计算机数值仿真,并与该火箭发动机热试车参数进行了比较,仿真的结果与火箭发动机热试车试验结果非常一致,验证了仿真模型的正确性和运用数值模拟方法取代部分实际热试车试验的可行性及可信性.     

The Hamilton–Jacobi partial differential equation and the three representations of traffic flow

This paper applies the theory of Hamilton–Jacobi partial differential equations to the case of first-order traffic flow models. The traffic flow surface is analyzed with respect to the three 2-dimensional coordinate systems arising in the space of vehicle number, time and distance. In each case, the solution to the initial and boundary value problems are presented. Explicit solution methods and examples are shown for the triangular flow-density diagram case. This unveils new models and shows how a number of existing models are cast as special cases.     

模糊微分方程的数值解法

将传统的欧拉差分格式引入到求解模糊微分方程中,给出了模糊微分方程的欧拉差分格式与局部截断误差估计.