基于N-S方程的航行船舶辐射问题数值模拟

基于N-S(Navier-Stokes)方程,进行了航行船舶辐射问题的数值模拟,包括强制垂荡和强制纵摇的模拟.计算了船舶垂荡和纵摇的附加质量和阻尼.数值模拟中,控制方程--BANS(Reynolds Averaged Navier-Stokes)方程和连续性方程使用有限体积法离散,非线性自由面采用VOF方法处理.文中给出了以不同航速前进的船舶强制垂荡和纵摇的力与力矩,以及船舶垂荡和纵摇的附加质量系数和阻尼系数,并与DUT(Delft University of Technology)的试验数据进行了比较,二者吻合良好.     

扰动微分方程在优化约束问题中的应用

研究了扰动微分方程在优化约束问题中的应用，指出对某些类型的奇解扰动后不存在部分变量收敛到优化约束问题的可行点。     

测定后张预应力摩阻损失的新方法

从后张预应力摩阻损失计算的基本原理出发,给出一种可有效测定摩擦系数肌局部偏差影响系数k和锚固端摩阻损失率的新方法。该方法以实测预应力筋伸长量和千斤顶张拉力为已知条件,通过非线性方程组的数值计算求解,得到待求的参数。该方法不需要使用应力传感器,不改变预应力筋的受力状态,仅用施工现场常用量具和设备就能进行测试,测试过程简单易行,对后张预应力体系的施工与检测有重要参考价值。     

Impacts of impression changes on freeway driver intention to adopt electronic toll collection service

This paper proposes conceptual frameworks incorporating technology acceptance model, theory of planned behavior and three additional constructs – impression changes, attitude of government, and risk to investigate the factors affecting freeway driver intention to adopt electronic toll collection service for both users and nonusers of electronic toll collection. The proposed frameworks are unique because of the incorporation of media and word-of-mouth effects to represent the impression changes, respectively. The respondents were specifically asked about their impressions of electronic toll collection related policies and strategies spread through media and word-of-mouth before and after electronic toll collection operation. Estimated results obtained from structural equations modeling validate that impression changes in both media and word-of-mouth exhibit significant direct or indirect effects on freeway driver intention to adopt electronic toll collection service. Corresponding strategies to enhance electronic toll collection adoption rate are then proposed accordingly.     

《基础会计》课程中会计事项对会计等式的影响

在《基础会计》课程的教学中,六大会计要素及会计等式是众多学生普遍反应的难点之一,学生难以理解的地方主要在于企业的会计事项对会计等式的影响。一般教材中认为影响会计等式的会计事项类型只有九项,这与企业实际发生的会计事项有所不同。本文主要就六大会计要素的变动对会计等式的影响作详细的分析,以解决这一难点问题。     

An approximate method for the surge response of the tension leg platform

The solution for the Duffing equation in anonlinear vibration problem is studied in this paper. Clearly,in the case of the perturb parameter being a larger value, thetraditional perturbation method is no longer valid but theHomotopy Perturbation Method （HPM） is applicable usually.HPM is used to solve the weak and strong nonlineardifferential equations for finding the perturbed frequency ofthe response. The obtained frequencies via HPM and theapproximate method have good accordance for weak andstrong nonlinear differential equations. Additionally, thecalculated responses by use of the approximate method arecompared with the responses obtained from the Numericalmethod in the time history of the response and phase plane.The results represent ~ood accordance between them.     

Tractor–semitrailer model for vehicles carrying liquids

This article presents a model for solving solid–fluid interactions in vehicles carrying liquids. A tractor–semitrailer model is developed by incorporating suspension systems and tire dynamics. Owing to the solid–fluid interaction, equations of motion for the vehicle system are coupled. To simplify the complicated solution procedure, the coupled equations are solved separately using two different codes. Each code is analyzed separately; but as the parameters of the two codes depend on each other, the codes must be connected at the end of each time step. To determine the dynamic behavior of the system, different braking moments are applied. As the braking moments increase, braking time decreases. However, it turns out that increasing the braking moment to more than a certain level produces no significant results. It is also shown that vehicles carrying fluids need a greater amount of braking moments in comparison to vehicles carrying solids during braking. In addition, as the level of the fluid inside the tanker increases, from one-third to two-third of the tanker’s volume, the sloshing forces applied to the tanker’s walls increase. It was also concluded that the strategy used in this article to solve for the solid–fluid interaction by incorporating vehicle dynamic effects represents an effective method for determining the dynamic behavior of vehicles carrying fluids in other critical maneuvers.     

Euler方程解的间断面的虚拟区域方法

用高分辨率激波捕捉格式求解Euler方程时,不可避免地会用到间断面两侧的点,从而在间断面附近发生数值耗散,降低分辨率.此文应用一种虚拟区域,将LevelSet方法与高分辨率激波捕捉方法结合起来求解Euler方程,不使用间断面两侧的点,从而提高了分辨率.通过激波管问题的数值实验,可以看到这种方法的优越性.     

动感赛车运动控制装备的模拟实验分析

基于科学有效的3D动画-玩家-赛车运动机构的交互机制和接口方法,借助于Solidworks和ADAMS两个软件实现了对动感赛车的建模和虚拟样机的建立.对动感赛车在不同虚拟路况下实行不同的运行方式,建立其运动学方程,并进行了运动学的分析研究,确定主要实验参数,完成动感赛车运动控制平台的模拟实验与数据分析.     

Time-machine in perfect fluid cosmologies

This letter investigates the time-machine problem in perfect fluid cosmologies. It solves the Einstein's field equations with the energy-momentum tensors for perfect fluid and constructs a class of time-machine solutions,by which the time-machine problem in the perfect fluid cosmologies is solved.