异种材料填充开圆孔矩形薄板应力集中的弹性分析

通过对孔内填充异种材料矩形板的应力—应变分析,导出了求解应力集中系数的精确公式,并根据该问题的特点和材料弹性常数变化对应力集中现象影响的规律,给出了应力集中系数计算的简化公式.通过与有限元结果的比较证明了本文精确公式与简化公式的精度和可靠性.     

线控转向系统故障检测及容错控制协同设计

为解决线控转向系统故障可能导致车辆失控的问题,提出一种故障检测及容错控制协同设计方法。首先,建立了包含线控转向系统加性故障的车辆动力学模型;其次,联合车辆动力学模型及故障检测/容错控制器,建立跟踪误差闭环控制系统;然后,求解满足闭环系统H∞性能的线性矩阵不等式,得到故障检测/容错控制器参数;最后,基于dSPACE Full-Size HIL进行硬件在环仿真测试。结果表明,该方法可快速检测出转向系统故障,同时实现了车辆的容错控制。     

动态输出反馈实时网络控制系统稳定性分析

研究了以实时以太网作为控制网络的系统稳定性。针对线性时不变被控对象,基于Ethernet/IP实时工业以太网,建立动态输出反馈实时网络控制系统模型,给出了系统渐进稳定的充分条件。仿真算例说明分析方法和结果是有效可行的。     

Prediction of slamming pressure considering fluid-structure interaction. Part II: Derivation of empirical formulations

This is Part II in a series of papers. Part I [1] investigated the slamming responses of flexible flat stiffened steel and aluminum plates using the nonlinear explicit finite element code LS-Dyna with the Multi-Material Arbitrary Lagrangian-Eulerian (MMALE) solver. Subsequently, a simplified finite element FSI model of water hitting structures that is realistically close to the slamming phenomenon occurring on the bottom part of offshore structures was proposed. The proposed FSI methodology presented in Part I was verified by comparison with the relevant test data. It was evident that the use of the proposed numerical method presented in Part I was very effective for a benchmarking investigation of slamming load considering the hydroelastic effect. However, the method required much effort in terms of computation time and power analysis resources. The present study, Part II, aimed, as an alternative to the FSI analysis approach, to develop empirical formulae for prediction of slamming loads acting on deformable flat stiffened plates used in marine applications. This paper begins by describing the limitations of the existing approaches based on theoretical, experimental and even numerical studies conducted in the past for estimation of slamming loads. Next, it presents, based on the simulation methodology developed in Part I, rigorous parametric studies that had been performed on actual scantlings of marine-seagoing structures. The effects of structural geometry and water impact velocity on slamming pressure are then investigated in detail. Subsequently, the parametric results are analyzed and utilized to derive empirical formulations for the prediction of slamming loads acting on flat stiffened plates of marine structures. The accuracy and reliability of the proposed formulations are established by comparison with the results of the test and other existing formulations. The proposed formulations are expected to be used for the purposes of the design without any time-consuming FSI analysis of advanced and optimal structures that are robust to slamming.     

复合材料薄壁杆件非线性扭转分析

考虑几何非线性的影响，建立了在拉、压、弯、扭组合变形下复合材料薄壁杆件理论．重点对杆件进行非线性扭转分析，由给出的等效本构方程和总势能泛函，根据最小势能原理导出了所给问题的平衡控制方程和相应边界条件．讨论了该方程和边界条件的求解．     

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研究了向量交通网络平衡问题，引入了一个新的弱平衡原理，将向量交通网络平衡问题转化成一个变分不等式问题．     

基于广义变分原理的铁路无缝道岔计算理论

在继承现有试验成果的基础上，将广义变分原理应用于铁路无缝道岔结构体系的分析，提出了一种新的铁路无缝道岔计算理论，建立了较为完善的计算模型，在假设钢轨纵向位移函数的基础上，计算了无缝道岔结构体系各部分的能量，通过广义变分法建立了结构体系的平衡方程，编制了计算程序，分析了固定辙叉无缝道岔钢轨温度力与位移。     

移动荷载作用下连续粘弹性基础支承无限长梁的有限元分析

把无限长梁、连续粘弹性基础和移动荷载视为一个系统，并将该系统进行有限单元离散，梁单元的弯曲形函数采用Hermitian三次方插值函数，利用弹性系统动力学总势能不变值原理，得到单元的刚度矩阵、质量矩阵、阻尼矩阵和节点荷载列阵，建立该系统的振动方程组；再用Wilsonθ法求解该振动方程组，得到梁中点的位移时程曲线。举例分析了基础的粘弹性特性和梁的抗弯刚度对梁动力响应的影响。计算结果表明：增大基础的弹性系数、阻尼系数和梁的抗弯刚度都有利于减小梁的动力响应。     

石油产品管道运输定量研究

成品油管道运输计划和调度是具有多约束的复杂问题,包括炼油厂的生产进度、市场需求、相邻油品的规格等都需考虑。另外,炼油厂和分销中心现有库存量和库存能力以及管道中的输油量等也要详细分析。文中对该领域的定量研究文献进行了梳理、综述,对未来研究趋势做了分析展望,以便研究人员作进一步研究。     

Comparative analysis of three user equilibrium models under stochastic demand

Recent empirical studies on the value of time and reliability reveal that travel time variability plays an important role on travelers' route choice decision process. It can be considered as a risk to travelers making a trip. Therefore, travelers are not only interested in saving their travel time but also in reducing their risk. Typically, risk can be represented by two different aspects: acceptable risk and unacceptable risk. Acceptable risk refers to the reliability aspect of acceptable travel time, which is defined as the average travel time plus the acceptable additional time (or buffer time) needed to ensure more frequent on‐time arrivals, while unacceptable risk refers to the unreliability aspect of unacceptable late arrivals (though infrequent) that have a travel time excessively higher than the acceptable travel time. Most research in the network equilibrium based approach to modeling travel time variability ignores the unreliability aspect of unacceptable late arrivals. This paper examines the effects of both reliability and unreliability aspects in a network equilibrium framework. Specifically, the traditional user equilibrium model, the demand driven travel time reliability‐based user equilibrium model, and the α‐reliable mean‐excess travel time user equilibrium model are considered in the investigation under an uncertain environment due to stochastic travel demand. Numerical results are presented to examine how these models handle risk under travel time variability.