Spatial competition and regulatory change in the grain handling and transportation system in western Canada

The grain handling and transportation system (GHTS) has been a defining component of the western Canadian economy since the early part of the last century. Only two major railways serve the grain handling industry, so the potential for the exercise of market power in transportation appears to be significant. In fact, spatially oriented regulations applicable to railways exist in Canada to mitigate this, but to date they have not often been used by shippers. While the reasons for this are not completely clear, we suggest that the regulations are now inadequate for the current state of the GHTS. Using a unique data set from the year 2000, we assess the effect on the grain handling industry of modifications to these regulations, and find that significant gains for shippers from these modifications are possible. These gains are computed to be on the order of C$10–15 million per year for grain shippers alone. We would like to thank conference and presentation participants (Transportation Research Board, Canadian Agricultural Economics Society, University of British Columbia, University of Leeds and California State University, Long Beach) as well as the anonymous reviewers who commented on the earlier versions of this paper. We would also like to acknowledge support from the Saskatchewan Department of Highways.     

多层次模糊综合评定在测绘质量管理中的运用

阐述了用模糊数学的计算方法来评定测绘产品的质量优良等级的方法,并进一步结合Excel的计算功能,实现产品质量评定的科学化.     

大型输水弯管结构有限元分析

弯管结构是输水管道工程中实现高低管道连接的重要部分,其结构形式和受力都比较特殊。结合一具体工程,对大型弯管结构的计算方法进行了讨论,并建立有限元模型对其应力进行了计算分析,给出了相应的结论和建议以指导设计。     

卧式室外型空调器及其应用

本文简要介绍卧式空调器的构造特点，提出了在设计选用中应注意的问题及采取的相应措施。     

工程机械新型全液压转向系统

本文给出一种工程机械新型全液压转向系统，能实验运输行驶，小回转半径，斜行等多种工况。     

作为场所的上海里弄解读

尝试从空间设计的角度去探索和分析里弄场所中空间与事件的相互作用,对发生在空间中的活动进行定量的分析,得出定性的结果,并对作为场所的上海里弄存在的必要性进行探讨,对里弄场所延续的可能性提出展望。     

Dynamic analysis of viscoelastic structures using incremental finite element method

This paper presents an efficient and accurate incremental finite element procedure, without involving any integral transformations, to deal with practical viscoelastic structures with complicated geometries subjected to dynamic loadings. The numerical error induced from the approximate inversion technique used is thus avoided. Based on the Hamilton's variational principle, an incremental functional is derived for each time increment and the inertia terms are retained in the analysis to estimate the transient viscoelastic behaviours. To model the specific stress-strain-time constitutive behaviours of viscoelastic materials, the Norton type time hardening rule is employed. In the present computation procedure, the change of creep strains is regarded as increments of fictitious body forces at the nodal points for the next time increment.

To evaluate the accuracy and the versatility of the solution technique developed in this work, several examples are given.     

不同地基条件下桅杆基础的设计分析

本文结合桅杆基础的特点,阐述了在不同地基条件下桅杆基础的设计。着重介绍了桅杆基础设计中关于基础类型的选取、荷载与抗力的取值以及浮容重等问题。     

基于CT试验的混凝土破损机理生态学研究

本文引入数学生态学种群的概念，在整个CT标尺范围内，以100等间距考察了混凝土圆柱试件第一扫描断面σ=9．87MPa时的CT图像，获取和分析了40个种群的个体数量和空间位置信息。在此基础上，确定了骨料种群、砂浆种群和孔隙或裂纹种群分区界限值，最终实现了混凝土骨料、砂浆和裂纹3个种群的提取，并对上述各种群的空间演化信息和CT数演化信息进行了分析，总结了混凝土的破损机理。     

Decomposing regional productivity growth using an aggregate production frontier

The main contribution of this paper is the implementation of a new model which combines the two parametric approaches most commonly used in the productivity literature: fixed effects and stochastic frontiers. This allows us to discuss whether it is better to use average or frontier functions to estimate regional productivity. The empirical section uses panel data of Spanish regions over the period 1980–1995. Additionally, we calculate and decompose total factor productivity growth for the Spanish regions.