转向梯形驱动机构的运动分析及优化设计

转向梯形驱动机构的空间布置对汽车的操纵稳定性影响很大。本文以常见的非独立悬架结构为例,建立空间几何模型进行运动分析,提出同时满足"与前悬架运动协调"和"左右转向力均匀"两方面要求的转向梯形驱动机构优化设计方法。实践应用表明该方法可行。     

The cost of second best pricing and the value of risk premium

Private provision of public infrastructure (PPP) is meant to give incentives to increased efficiency in construction as well in operation and maintenance of the infrastructure e.g. within the transport sector. Efficiency is not only (private) economic efficiency, but also social efficiency e.g. social marginal cost pricing of use of the infrastructure.Is it possible to design contracts concerning payment mechanisms and financial instruments for transport infrastructure that will stimulate social efficiency and optimal allocation of risks between parties? The paper discusses whether different targets can be met and whether compromises may lead to acceptable second best solutions.PPP implies an opportunity to let the user-payment give desired incentives in the form of Social Marginal Cost Pricing (SMCP). A PPP project is a set of contracts and agreements between several parties, including the Government, the private contractor, subcontractors, banks and infrastructure users. These contracts should be designed to give the right incentives to the parties to achieve optimal risk allocation and utilising of resources.Long contract-periods are a common feature of PPPs. The paper examines the way that financial solutions should be designed to achieve the goals for the PPP-projects concerning economic and social efficiency. The expected size and variation of the income stream from the project will influence the loan conditions offered by banks concerning interest rates, guarantees and repayment and also the ability to attract investors. The balance between equity and loans again influences the conditions of the loans. An additional problem is asymmetric information between parties. The private contractor usually knows more about the task than the Government (hidden knowledge), and the Government cannot have full knowledge of the efforts of the contractor (hidden actions).     

灵敏度分析在铸件优化设计中的应用

在铸件设计时一般都是先经过拓扑优化然后再进行结构设计,但拓扑优化无法得到确定结构的最优尺寸,仅能得到给定边界条件下的基本形式,因此在拓扑优化后如何进行详细尺寸设计对设计者要求较高,有时会设计出很多方案进行强度验证,且这些方案往往不是最优方案。在拓扑优化分析完毕后再加入灵敏度优化技术,可以快速得到满足设计要求且重量最轻结构的详细尺寸,大大提高了设计效率。     

Comparison of direct and indirect methods for minimum lap time optimal control problems

Minimum lap time simulations are especially important in the design, optimisation and setup of race vehicles. Such problems usually come in different flavours, e.g. quasi-steady state models vs. full dynamic models and pre-defined (fixed) trajectory problems vs. free trajectory problems. This work is focused on full dynamic models with free trajectory. Practical solution techniques include direct methods (i.e. solution of an nonlinear programming problem problem, widespread approach) and indirect method (i.e. based on Pontryagin's principle, less common, yet quite efficient in some cases). In this contribution the performance of the direct and indirect methods are compared in a number of vehicle-related problems.     

沥青混合料最佳油石比确定方法试验研究

基于沥青混合料的力学强度、路用性能和微观结构及体积指标,用最大粘结力法、最大疲劳寿命法和沥青体积法设计沥青混合料的最佳油石比,并分析对比各方法的优缺点。     

基于时间窗的铁路空车调配优化模型及求解

针对以往铁路空车调配优化研究中对时效性考虑不足的现状,考虑到空车过早或过晚到达都会给铁路运输企业带来额外的费用支出,按照空车运输费用、积压库存费用及延误损失费用之和最小的原则,建立基于时间窗(规定时间段)和区段空车运输能力约束的空车供需平衡调配优化模型。以由3个空车供应站、4个空车需求站组成的铁路运输网络为例,按照线性整数规划求最小值问题,运用LINGO软件进行仿真求解,得到最优空车调配方案。     

Feeder-trunk or direct lines? Economies of density,transfer costs and transit structure in an urban context

A feeder-trunk scheme has been labeled as superior in urban areas due to the presence of economies of density (decreasing average operating cost) along the avenues served by trunk lines. We compare this structure against three types of direct lines structures (no transfers) to serve a stylized public transport network where several flows converge into a main avenue, simultaneously optimizing fleet and vehicle sizes considering both users’ and operators’ costs. The best structure is shown to depend not only on the total passenger volume but also on demand imbalance, demand dispersion in the origins and the length of the trunk line. The region where the feeder-trunk structure dominates depends largely on the value assigned to the pure transfer penalty.     

船用柴油机混合能源系统配置优化

考虑新能源的间歇性以及船舶电力系统负载的突变性和波动性,本文首先根据船舶航行中经纬度和海上环境的变化对新能源的参数进行修正,然后构造同时计及成本与使用寿命的船用柴油机混合能源系统优化配置目标函数,再利用人工蜂群算法进行优化,从而获得最佳的系统配置。船舶航行实测试验验证该方法的可行性,同时表明了它比陆地上传统方法具有更好的优化配置性能。     

旁通增压系统动态性能研究

用数值模拟方法对旁通增压系统的动态性能作了研究，着重考察了旁通阀以不同规律启闭时增压系统各主要参数的响应情况，探讨了当柴油机负荷突变时由于旁通阀响应滞后而可能出现的问题。本文的研究助于揭示该增压系统的动态特性，为柴油机的优化控制系统设计提供了依据。     

基于模糊神经网络的氢燃料汽车发动机最优控制模型

在试验研究的基础上，提出了氢发动机的优化控制策略，建立以点火提前角、喷氢提前角和喷氢量为控制变量，分别以动力性、经济性为性能指标泛函，以模糊神经网络为求解工具的最优控制模型。