一种少自由度并联机器人雅克比分析的新方法

提出一种对称少自由度并联机器人雅克比方阵的建立方法.利用螺旋理论分析单个支链的结构,找出动平台对驱动关节的映射系数,根据不同的输入选取,对映射系数进行组合,去除映射系数矩阵中非独立运动参数对应的列,得到满秩的映射系数矩阵.对映射系数矩阵求逆,得到对称少自由度并联机器人的雅克比方阵,说明了运动输入与运动输出之间的对应关系,并得到实例验证.     

基于旅客选择行为的高速铁路平行车次定价策略

考虑运行在同一OD上的高速铁路平行车次,现行高铁票价固定,即不能反应平行车次间的差异化,也无法与旅客需求状况相适应,最终造成平行车次间上座率的失衡和收入的损失.鉴于此,本文借鉴多产品定价的思想,利用MNL模型来描述旅客购票过程的选择行为,并以平行车次的整体收入最大化为目标提出了3种定价策略.最后以京沪高铁为案例背景,对旅客购票过程的最优票价路径及3种定价策略的效率进行了分析.结果表明,3种定价策略均能有效提高售票收入,且差别动态定价策略表现最优.本文研究内容为高速铁路平行车次的定价决策提供了科学依据.     

半挂汽车列车弯道行驶横向稳定性分析

为了进一步研究半挂汽车列车弯道行驶横向稳定性,运用动力学理论以及虚拟样机仿真软件ADAMS,建立了具有21自由度的半挂汽车列车虚拟样机,通过将稳态转向试验和转向盘角阶跃输入试验所得仿真结果与实车试验所得曲线相比较进行仿真模型的校验,分析了半挂汽车列车在弯道行驶极限工况下有关参数与时间的变化关系曲线,并分析极限工况所产生的原因。     

城市地铁穿越软流塑地层段的设计施工技术

软流塑地段围岩自稳能力极差,易坍塌,严重时可能发生突水涌泥现象,地层加固难度较大。通过已经成功修建的工程实例重点剖析城市地铁在穿越软流塑地层时的设计施工技术,重点对洞内注浆加固、软弱围岩仰拱超前、水平旋喷加固、冻结加固法等施工辅助工法进行介绍和比选。同时对软流塑淤泥质粉质黏土地层进行劈裂注浆的原理、可行性、加固范围与扩散半行、注浆压力、注浆量、浆体材料和配比、注浆效果等进行了研究。     

Preservation of the NBUCA Class of Life Distributions

Introduction As is well known, lifetime distributions can beclassified by stochastic ordering. Recently, Ahmad etal.[1]defined a new aging class, namely, NBUCA(new better than used in increasing convex average),based upon the increasing convex average order. Inthe theory of economics, this order is known as weakthird-order stochastic dominance[2]. Under the as-sumption that the elements are independent andidentically distributed (i.i.d.), the preservationproperties of this class under convo…     

CLUSTER OF WORKSTATIONS BASED ON DYNAMIC LOAD BALANCING FOR PARALLEL TREE COMPUTATION DEPTH-FIRST-SEARCH

IntroductionWith the advantages of the high- speed net-works,cluster of workstations achieve the samescalable parallelism as the current MPPs( Massive-ly Parallel Processors) .But there are many factorssuch as load imbalance,synchronization and com-munication that inhibit good performance in thesesystems.These issues are central to the develop-ment of many parallel applications. Load balanceproblem is a serious impediment to achieving goodperformance in parallel processing the issue of load…     

Modeling household activity–travel interactions as parallel constrained choices

The daily activity-travel patterns of individuals often include interactions with other household members, which we observe in the form of joint activity participation and shared rides. Explicit representation of joint activity patterns is a widespread deficiency in extant travel forecasting models and remains a relatively under-developed area of travel behavior research. In this paper, we identify several spatially defined tour patterns found in weekday household survey data that describe this form of interpersonal decision-making. Using pairs of household decision makers as our subjects, we develop a structural discrete choice model that predicts the separate, parallel choices of full-day tour patterns by both persons, subject to the higher level constraint imposed by their joint selection of one of several spatial interaction patterns, one of which may be no interaction. We apply this model to the household survey data, drawing inferences from the household and person attributes that prove to be significant predictors of pattern choices, such as commitment to work schedules, auto availability, commuting distance and the presence of children in the household. Parameterization of an importance function in the models shows that in making joint activity-travel decisions significantly greater emphasis is placed on the individual utilities of workers relative to non-workers and on the utilities of women in households with very young children. The model and methods are prototypes for tour-based travel forecasting systems that seek to represent the complex interaction between household members in an integrated model structure.     

一种新型环型局部网络的研究

本文提出了一种基于后补路径算法策略的单环双向局部网络。获得令牌的主控站可以选择最短的路径方向发送数据报文,同时沿相反方向传送含有主节点路径信息的控制报文,使得上述路径以外的各站在一定区间并行地传输报文。从而提高了通道利用率、吞吐量和网络可靠性。文中给出了性能模拟分析。     

大连低地板有轨电车的动力学性能

介绍国内第1列低地板有轨电车的结构，比较了独立车轮与传统轮对的异同，对独立车轮转向架试运行情况进行了分析，通过试验证明其走行部具有较好的稳定性、平稳性和曲线通过等动力学性能，最后结合走行部的关键结构分析了该车的动力学特点及仿真结果。