延性系数确定方法的探讨

对于没有明显屈服点ΔY的结构体系(或材料),可以采用模拟屈服过程法确定其延性系数。同时,提出了屈服过程比P,延性区间系数着,以及假想“屈服平台”的概念,并且尝试应用于工程设计中。     

建立整数型轨道状态最优综合维修计划模型

为实现高效的轨道不平顺养护维修,建立最优养护维修计划模型和采用大型养路机械进行作业是十分重要的。本文以养护维修时间为决策变量,以年度轨道不平顺平均值最小为目标函数,在考虑了一系列约束函数的情况下,建立了整数型轨道状态最优综合维修计划模型。该模型能有效利用现场的养护资源,从安全和舒适的角度出发来制定养护计划,该模型的建立从理论上解决了轨道不平顺状态计算机辅助决策系统的关键问题。     

PMM tests in a circulating water channel and nonlinear analysis

As a result of frequent marine disasters leading to the loss of human life and pollution of vast areas of the ocean, ship manoeuvrability has become a very important characteristic of ship design. Among several recent experimental techniques to determine ship manoeuvrability, the most popular is captive model testing using a planar motion mechanism (PMM). This article describes some tests, analyses, and results of PMM tests in a circulating water channel (CWC) using a model of a training ship. The hydrodynamic forces and moments acting on a model of the training ship Shioji Maru in pure yawing motion were measured, and hydrodynamic derivatives were obtained using two different methods of analysis: singular value decomposition (a least-squares fit method) and Fourier analysis. Derivatives obtained from the tests were used to simulate the turning trajectory of the actual ship, and these were compared with the results of sea trials. The results indicate that both methods of analysis yield fairly similar derivatives. The simulation results were also found to be a close match with the trial results. Received: February 7, 2002 / Accepted: May 14, 2002 Address correspondence to: K. Shoji (shoji@ipc.tosho-u.ac.jp)     

世界银行贷款项目“卫津路拓宽工程”的经济效益计算

本市以天津城市主干道卫津路拓宽改造工程为例，论述城市道路经济效益计算方法。按全天高峰小时、非高峰小时，分别计算机动车和非机动车的运营成本、时间价值及事故费用，采用有、无项目对比法．进行经济效益计算。经济效益中以车辆行程时间延误与路口时间延误的节约作为主要效益。     

钢筋混凝土桥柱新配筋方式研究

该文结合轴心抗压试验,介绍了钢筋混凝土桥柱的配筋方式,可供类似结构设计借鉴参考。     

Performance estimation model of a torque converter part I: Correlation between the internal flow field and energy loss coefficient

The objective of this paper is to improve the performance estimation model of the internal flow field of a torque converter. Compared with performance experiment results, the converter based on the one-dimensional model does not satisfy the performance requirements demanded in practice. Therefore, we need to develop more predictable and reliable performance estimation models. In order to obtain shape information on three-dimensional blade geometry, a process of reverse engineering conducts a torque converter assembly, impeller, turbine and stator. In addition, a CFD simulation including mesh generation and post-processing was carried out to extract equivalent parameters from the internal flow field. The internal flow field can be explained by analyze the correlation between a performance estimation model and CFD analysis. The equivalent performance model adopts the variation of energy loss coefficients for a given operating condition according to the application of a changing energy loss coefficient by the least mean squares method. The estimated equivalent model improves the agreement in performance between experiments and the theoretical model. This model can reduce the error to within about 3 percent. Furthermore, this procedure for predicted performance achieves eminence in the estimation of the capacity factor.     

论企业核心竞争力的战略定位与战略模式

从企业现代竞争理论三个阶段的演变看,正是由于主流企业战略管理理论的不足才促使了企业核心竞争力理论的迅速兴起,核心竞争力的战略选择成为企业战略制定的关键问题。企业可以从经营业务战略、目标行业战略、市场竞争战略与资源组合战略四方面进行核心竞争力战略定位,确立以客户价值为中心的核心竞争力战略模式。     

天然气发动机冷却系统校核

商要:发动机冷却系统的作用是使发动机的温度在所有工况下均保持在适当的范围内。冷却系统不仅要防止发动机过热,也要防止发动机过冷。本文主要是对某重卡车型的发动机冷却系统进行了校核计算,为整个车型的匹配计算提供数据支持。     

现有世界文化遗产桥梁的核心价值及中国古桥申遗的思考

中国古代桥梁具有极高的技术成就,然而迄今为止,我国尚没有古桥被列入世界文化遗产,因此开展中国古桥申报世界文化遗产的研究非常必要。为了加快我国古桥申遗的进程、促进我国古桥的保护与传承,从世界遗产的相关定义与要求出发,介绍被列入世界文化遗产桥梁的特点,对我国古代桥梁的价值与技术成就进行讨论。根据世界文化遗产入选的条件,我国的古代石拱桥和木拱桥最具有申遗实力。依据桥梁作为功能性结构、技术复杂结构的特点,在此基础上提出中国古代桥梁申报世界文化遗产应聚集核心技术内容的研究,突出其核心价值和技术成就。     

基于Shapley值法的港口冷链物流投资分析方法

从客户的角度出发,旨在建立一套与投资额度、客户满意程度相关联的港口冷链物流投资分析方法,为决策者在财务分析之外提供另一个分析视角。将港口冷链物流划分为冷藏存储、冷藏加工、冷藏运输、客户服务4个环节。首先利用层次分析法确定各个环节在整条供应链的权重,然后引入效用理论确定各个环节投资产生的效用,通过Shapley值法实现了各个环节在整条供应链权重和各个环节投资效用的有机结合,使得发展瓶颈随投资的变动而改变,从而更加符合实际情况。通过实例分析,此方法能够充分考虑投资效用的影响,也能够减少专家打分等定性方法产生的主观偏差。