针摆行星传动中复合齿形摆线轮等效代换齿廓的研究

提出了采用完整的短幅外摆线的等距曲线作为摆线轮齿廓，来等效代换针摆行星传动中复合齿形摆线轮齿廓的理论，并给出了求解等效齿廓参数的数学模型、计算方法和求解实例。     

Open registry tanker operations: a comparative cost analysis

The pull of economic gravity on traditional tanker operators towards open registries has been caused primarily by the need to be cost‐competitive in a market which itself is competitive. By using transcendental logarithmic cost functions to model the cost structures of open and traditional tanker operations, this study highlights the general structure of the production technology of tanker services, the cost differentials between the two flag groupings and provides insights into the comparative statics effects of their production functions in the form of elasticities of factor substitution and demand, and scale economies.     

柴油-天然气双燃料发动机的性能研究

在高压共轨电控柴油发动机的基础上,研发了柴油-天然气双燃料发动机。该发动机在原机电控系统保持不变的情况下,增加了一套双燃料电控系统,使其可以在纯柴油和柴油天然气双燃料两种模式下工作。在柴油天然气双燃料模式下,以少量的柴油引燃适量的天然气进行混合燃烧,达到与原机相同的功率及扭矩输出,天然气对柴油的平均替代率达85%以上,提高了该发动机的经济性。     

Discretionary activity time allocation of individuals between in-home and out-of-home and between weekdays and weekends

This paper formulates a model for the allocation of total weekly discretionary time of individuals between in-home and out- of-home locations and between weekdays and the weekend. The model formulation takes the form of a continuous utility-maximizing resource allocation problem. The formulation is applied to an empirical analysis using data drawn from a 1985 time-use survey conducted in the Netherlands. This survey gathered time-use information from individuals over a period of one week and also collected detailed household-personal socio-demographic data. The empirical analysis uses household socio-demographics, individual socio-demographics, and work-related characteristics as the explanatory variables. Among the explanatory variables, age of the individual and work duration during the weekdays appear to be the most important determinants of discretionary time allocation.     

Applying a semantic information Petri Net modeling method to AUV systems design

This paper informally introduces colored object-oriented Petri Nets(COOPN) with the application of the AUV system. According to the characteristic of the AUV system's running environment,the object-oriented method is used in this paper not only to dispart system modules but also construct the refined running model of AUV system,then the colored Petri Net method is used to establish hierarchically detailed model in order to get the performance analyzing information of the system. After analyzing the model implementation,the errors of architecture designing and function realization can be found. If the errors can be modified on time,the experiment time in the pool can be reduced and the cost can be saved.     

挤压镁合金汽车仪表板横梁骨架的设计与分析

为实现汽车轻量化,对钢制仪表板横梁骨架总成进行了镁合金替代设计。依据制造工艺将镁合金仪表板横梁骨架按挤压件和冲压件分别设计,并确定了镁合金材料及连接工艺;建立镁合金仪表板横梁骨架总成的有限元模型,进行模态对比分析和碰撞侵入量分析;建立仪表板横梁管材的弯曲仿真模型,模拟管坯的弯曲成形。结果表明镁合金替代设计满足仪表板横梁的轻量化、整体模态、碰撞安全以及可制造性的要求。     

Is telecommuting cheaper than travel? An examination of interaction costs in a business setting

This paper presents an analysis of telecommunications and travel costs for typical business meetings. It is contribution to the debate on the substitutability of telecommunications for travel. An underlying assumption which supports the substitution hypothesis is that the cost of traversing distance through the use of telecommunication is lower than the cost of travelling.This paper addresses the relative cost of telecommunications and travel in conducting interactions. Three factors are assumed to determine these costs: distance, duration of interaction and number of participants. The analysis assumes that cost alone affects choice, and ignores other communication qualities.The relationship between telecommunication and travel costs was tested quantitatively through a case study of typical business meetings in the U.S., based on data from 1988. The results show that travel costs are lower than telecommunication costs for shorter distances, and that the relationship between telecommunications and travel costs differs substantially as a function of number of participants and meeting duration. Because of ongoing rapid changes in the costs of both of these interaction modes, the complex competition between them will continue. The implications of the findings for location decisions and policy-making are discussed.     

高铁开通后出行方式替代与诱发交通需求实证总结

自高速铁路(High-speed Rail,HSR,以下简称"高铁")开始运营以来,尽管已历经近50年的发展并且在全球范围内拥有17 166 km里程,但是对于高铁需求量的本质仍然所知甚少。诸多信息表明,全球高铁建设项目在期望可达性、经济及环境效益以及对高铁预测需求量相对匮乏的跟踪记录方面存在明显的空白。针对出行方式替代与诱发交通需求的影响,本文旨在填补高铁开通后需求方面的空白,从而助力未来的高铁系统规划研究过程。目前在高铁需求方面没有足够的实证,并且现有实证严重受到线路具体特征影响,尽管存在方法的局限,但是呈现出的实证可促使高铁成为一种性能更优的交通工具。研究表明,在高铁运营后的最初几年,只有10%~20%的需求量是诱发交通需求,其余均来自于出行方式替代。在多数情况下,大部分高铁乘客之前使用传统铁路出行,从航空、小汽车以及长途客车转移至高铁的乘客量比例较低。