(美)伍兹·霍尔海洋研究中心载人深潜器计划探究暨(美)新概念ALVIN号载人深潜器关键技术浅析

文章较为详细地介绍了美国伍兹霍尔海洋学研究所（WHOI）目前在建的新概念ALVIN号载人深潜器研制项目,该项目经过了美国科研机构认真详实的凋研论证而立项,新概念ALVIN号的研制对确保美国在深海研究及深海技术方面处于领先地位有着重大意义。文中介绍了新ALVIN号的主要技术性能、关键技术、建造费用、建造计划等内容。     

六轴弹性架悬高速机车牵引杆布置方式

为了开发中国运行速度为200km.h-1的2C0轴式单杆牵引高速机车转向架,研究了牵引杆布置方式对机车运行安全性的影响。采用多体动力学软件SIMPACK建立了2C0轴式弹性架悬机车整车动力学模型,在惰行、牵引和制动工况下,分析了单牵引杆由转向架向车体端部和中部牵引时,机车的直线运行性能和曲线通过性能。分析结果表明:牵引杆布置方式对机车动力学性能影响不显著,建议采用牵引杆端部牵引的方案,以简化机车车体的设计与制造。采用牵引杆端部牵引的机车可安全通过R400m和R1600m的S形曲线;通过R400m小半径曲线时,机车惰行运行的轮对横向力大于牵引和制动工况的横向力,制动工况的轮重减载率较大;通过R2800m大半径曲线时,机车牵引和惰行的轮对横向力大小相当,大于制动工况的横向力。     

A reference-dependent user equilibrium model for activity-travel scheduling

Existing user equilibrium models of activity-travel scheduling generally fall short in representing travelers’ decision-making processes. The majority have either implicitly or explicitly assumed that travelers follow the principle of utility maximization. This assumption ignores the fact that individuals may be loss–averse when making activity-travel decisions. Allowing for the situation that travelers possess accurate information of the urban-transportation system due to modern technologies, studies on reference-dependent decision-making under near-perfect information are receiving increasing attention. In view of traveler heterogeneity, individuals can be divided into multiple classes according to their reference points. In this paper, we propose a reference-dependent multi-class user equilibrium model for activity-travel scheduling, which can be reformulated as a variational inequality problem. Moreover, comparative analyses are conducted on the equilibrium states between utility-maximization (no reference) and reference-dependency of exogenous and endogenous references. A numerical example regarding combined departure-time and mode choice for commuting is conducted to illustrate the proposed model. The simulated results indicate that reference points and loss aversion attitudes have significant effects on the choice of departure time and mode.     

汽车金属部件防腐原理与措施

汽车金属部件的腐蚀是不可避免的,必须进行有效的防护。本文从金属部件腐蚀的原理入手,针对斑状腐蚀、局部腐蚀、缝隙腐蚀、受载下的腐蚀四种常见的腐蚀类型,深入分析了腐蚀的原因,然后提出了汽车金属部件防腐蚀的策略,最后系统研究了各种防腐蚀的措施,包括优化防腐设计并改善腐蚀环境、材料替换、改善涂覆和增强电化学防护等方面。通过这些分析和研究,以期达到改善现有车辆金属部件的防腐措施、提高金属部件的防腐性能的目的。     

双曲抛物面薄壳屋盖的制作与设计

为了方便双曲抛物面薄壳屋盖的制作,采用数学建模的方法对双曲抛物面薄壳屋盖进行理论计算,得到了直母线钢筋数以及直母线钢筋在空间的位置、锚固面方程以及与直母线交点、直母线之间的交点和直母线与锚固面的法线之间夹角的数学表达式。利用Matlab软件经过实例计算验证了其有效性,为今后双曲薄壳屋盖的制作提供了理论依据。     

基于邻域极值数的协同粒子群优化算法

提出了一种基于邻域极值数的协同粒子群优化算法。该算法将种群分为若干个独立进化的子种群。根据邻域极值数确定各子种群的生存状态。根据子种群的生存状态对子种群实施相应的控制操作,提高子种群的搜索能力,实现子种群之间的信息共享,共同进化。测试结果表明基于邻域极值数的协同粒子群优化算法是一种高效稳健的全局优化算法。     

基于转速波动控制的整车启动抖动优化

对某三缸发动机车型存在整车启动抖动大的问题进行分析,发现启动抖动在转速波动上升过程中产生,与转速波动的大小存在相关性.通过研究起动机、燃烧激励、双质量飞轮等因素对启动工况下转速波动的影响,分析其与整车启动抖动大小的相关性,并通过提高起动机启动转速、降低燃烧激励所产生的缸压及降低双质量飞轮第二惯量等对策,降低了转速波动,...     

混凝土自锚式悬索桥主缆锚固区应力分析

混凝土自锚式悬索桥主梁通常采用预应力混凝土结构,在强大的索力和预应力、支反力的共同作用下,主缆锚固区的受力状况十分复杂。针对主缆锚固区的受力状况进行研究,对优化锚固区的细部构造和预应力钢束布置均有重要意义。该文以张家港镇山大桥为例,运用有限元方法对主缆锚固区进行空间应力分析,总结了此类桥梁主缆锚固区的受力特点。     

新型等离子体水下臭氧发生器特性研究

针对现有臭氧发生装置的不足,提出了一种采用倍压整流回路在水下产生臭氧的新型等离子体水下臭氧发生器。阐述了水下臭氧发生器的工作原理,并利用该装置对鱼池水进行试验研究。通过理论和试验相结合的方法系统的研究了该臭氧发生器的特性。研究表明:电容C2上产生接近或超过2倍电源电压幅值的高压;处理水中臭氧含量增加,对鱼池水处理效果明显,为设计出性能优良的臭氧发生装置提供了理论依据。     

Multi-state supernetwork framework for the two-person joint travel problem

Most travel behavior studies on route and mode choice focus only on an individual level. This paper adopts the concept of multi-state supernetworks to model the two-person joint travel problem (JTP). Travel is differentiated in terms of activity-vehicle-joint states, i.e. travel separately or jointly with which transport mode and with which activities conducted. In each state, route choice can be addressed given the state information and travel preference parameters. The joint travel pattern space is represented as a multi-state supernetwork, which is constructed by assigning the individual and joint networks to all possible states and connecting them via transfer links at joints where individuals can meet or depart. Besides route choice, the choices of where and when to meet, and which transport mode(s) to use can all be explicitly represented in a consistent fashion. A joint path through the supernetwork corresponds to a specific joint travel pattern. Then, JTP is reduced to an optimization problem to find the joint path with the minimum disutility. Three standard shortest path algorithm variants are proposed to find the optimal under different scenarios. The proposed framework further indicates the feasibility of multi-state supernetworks for addressing high dimensional problems and contributes to the design of a next generation of joint routing systems.