A multiobjective model for maximizing fleet availability under the presence of flight and maintenance requirements

Every aircraft, military or civilian, must be grounded for maintenance after it has completed a certain number of flight hours since its last maintenance check. In this paper, we address the problem of deciding which available aircraft should fly and for how long, and which grounded aircraft should perform maintenance operations, in a group of aircraft that comprise a combat unit. The objective is to achieve maximum availability of the unit over the planning horizon. We develop a multiobjective optimization model for this problem, and we illustrate its application and solution on a real life instance drawn from the Hellenic Air Force. We also propose two heuristic approaches for solving large scale instances of the problem. We conclude with a discussion that gives insight into the behavior of the model and of the heuristics, based on the analysis of the results obtained.     

基于风险网络的轨道交通车辆风险评价

针对轨道交通车辆系统的风险网络和关键部件风险评价开展研究，以系统部件和部件连接关系作为节点和边，建立了风险网络模型，分析了节点固有风险的影响因素和计算方法.根据节点之间故障传播概率得到边的作用强度和路径风险.对节点固有风险和路径风险进行分析，得到节点综合风险，并通过幂法对节点综合风险进行求解，从而识别部件对系统的影响程度.以转向架系统为例进行综合风险计算，结果表明：部件固有风险大小不能完全决定综合风险大小，还与部件连接关系和作用强度相关；与实际经验得出的关键部件综合风险排序对比，利用本文方法得到的关键部件排序一致性与其他方法相比有明显提升.     

基于感知能力的微观交通流动力学建模与仿真

基于驾驶员驾驶行为感知能力，提出了一种新的微观交通流动力学模型. 通过理论分析和数值模拟，对新模型的性能进行了详细的研究分析. 通过理论分析，基于线性稳定性理论，得到了新模型的稳定性条件. 通过数值模拟，深入分析了各参数对密度波和迟滞环的影响，进而对交通流稳定性的影响. 仿真算例结果表明：驾驶员感知能力对交通流稳定性有显著影响，车头距离变化信息可有效增强交通流的稳定性，对stop-and-go 交通拥堵有显著抑制作用，但不可避免的感知缓冲时间会破坏交通稳定性，进而产生严重的stop-and-go 交通拥堵；密度波和迟滞环的数值仿真结果与理论分析结果吻合得很好，验证了理论分析结果.     

Integrated coastal water monitoring

Geographical Information Systems (GIS) are important took for environmental monitoring and management. However, their limitations in dealing with complex, dynamic, and mission‐critical situations call for alternative approaches. Integrating GIS with dynamic simulation models offers one such solution. Numerical models that simulate physical, chemical, and biological processes greatly increase our understanding of the environment. Many of these models use refined forecast information to accurately predict processes that help in monitoring and managing the environment. Integrating these models with GIS offers new functionalities. The present research couples the MIKE21 comprehensive modeling system for two‐dimensional free surface flows with the spatial analysis strengths of the ArcView GIS. The southern coastal water system of Singapore serves as the study area. The aim is to develop a comprehensive software system that provides support for both environmental managers and land‐use planners in making their decisions.     

汽车玻璃升降器失效控制技术

随着经济社会的持续快速发展,汽车玻璃升降器构造技术迎来了前所未有的重大发展机遇,如何采取有效控制技术方法,全面提升汽车玻璃升降器运行效果,成为业内广泛关注的焦点课题之一。基于此,本文首先介绍了汽车玻璃升降器的基本组成与原理,分析了汽车玻璃升降器的失效分析与处理技术,并结合相关实践经验,分别从严格执行玻璃升降器技术规范要求等多个角度与方面,探讨了优化汽车玻璃升降器失效控制效果的有效策略,阐述了个人对此的几点浅见,望对汽车玻璃升降器失效控制实践有所裨益。     

An ABS control logic based on wheel force measurement

The paper presents an anti-lock braking system (ABS) control logic based on the measurement of the longitudinal forces at the hub bearings. The availability of force information allows to design a logic that does not rely on the estimation of the tyre–road friction coefficient, since it continuously tries to exploit the maximum longitudinal tyre force.

The logic is designed by means of computer simulation and then tested on a specific hardware in the loop test bench: the experimental results confirm that measured wheel force can lead to a significant improvement of the ABS performances in terms of stopping distance also in the presence of road with variable friction coefficient.     

系统效能通用评估工具研究

基于数据库和算法集成,设计了一套具有良好通用性、灵活性、可扩展性的系统效能评估工具,并以此工具为基础,针对不同的评估需求、数据量和应用环境提出对应的解决方案.     

移动模架造桥机在苏通大桥引桥PC连续梁的应用

介绍了苏通北引桥完全自行式移动模架系统的一般构造及工作原理。重点分析了移动模架系统施工过程中箱梁底板线形控制要点及箱梁悬臂段受力特点，针对悬臂端箱梁底板横向应力水平过高的特点，揭示了原因，提出了工程措施并在实桥中应用。     

基于认知地图的地铁空间导视系统优化分析

在认知心理学理论背景下,分析了乘客进入地铁地下空间的心理行为及感受。通过地铁导视系统与认知地图的搭建,剖析完善的地铁空间认知元素,并以此为设计对象,对地铁导视系统中乘客方向感缺失等问题作出一些具体分析与优化。     

Intermodal and international freight network modeling

The authors describe the development and application of a single, integrated digital representation of a multimodal and transcontinental freight transportation network. The network was constructed to support the simulation of some five million origin to destination freight shipments reported as part of the 1997 United States Commodity Flow Survey. The paper focuses on the routing of the tens of thousands of intermodal freight movements reported in this survey. Routings involve different combinations of truck, rail and water transportation. Geographic information systems (GIS) technology was invaluable in the cost-effective construction and maintenance of this network and in the subsequent validation of mode sequences and route selections. However, computationally efficient routing of intermodal freight shipments was found to be most efficiently accomplished outside the GIS. Selection of appropriate intermodal routes required procedures for linking freight origins and destinations to the transportation network, procedures for modeling intermodal terminal transfers and inter-carrier interlining practices, and a procedure for generating multimodal impedance functions to reflect the relative costs of alternative, survey reported mode sequences.