蝶形布置油码头平面设计要点

对港口工程设计中常见的蝶形布置油码头进行研究。结合国内外规范要求,采用对比分析法解析码头长度、系缆墩位置和靠船墩位置3个要点。其中,因为船体平直段相对船中的不对称,靠船墩位置是最为重要的设计内容。系缆墩位置不合理,只会影响缆绳受力均匀性和船舶运动量;而靠船墩位置不合理,会导致设计船型范围内的船舶无法安全靠泊。因此,结合某海外5万~30万t油码头,阐述靠船墩位置设计关键点,供港口工程设计人员参考。     

The relationship between transportation vulnerability,school attendance,and free transportation to an afterschool program for youth

Transportation - Transportation vulnerability, defined as lack of access to transportation resulting in financial, social, or health consequences, reduces quality of life. While research has...     

A simulation‐based reliability assessment approach for congested transit network

This paper is an attempt to develop a generic simulation‐based approach to assess transit service reliability, taking into account interaction between network performance and passengers' route choice behaviour. Three types of reliability, say, system wide travel time reliability, schedule reliability and direct boarding waiting‐time reliability are defined from perspectives of the community or transit administration, the operator and passengers. A Monte Carlo simulation approach with a stochastic user equilibrium transit assignment model embedded is proposed to quantify these three reliability measures of transit service. A simple transit network with a bus rapid transit (BRT) corridor is analysed as a case study where the impacts of BRT components on transit service reliability are evaluated preliminarily.     

Is DOC the main source of organic matter remineralization in the ocean water column?

Recent interpretations of carbon flux data and deep-sea processes have led to a reconsideration of the role of dissolved organic carbon (DOC) in supporting water column remineralization and other mid-water biogeochemical transformations (Suzuki et al., 1985; Cho and Azam, 1988; Karl et al., 1988; Christensen et al., 1989; Naqvi and Shailaja, 1993). To date, there have been no direct comparisons of particulate carbon flux data with water column metabolic rates. Here, for the first time, particulate carbon flux and respiratory electron transport activity (from which metabolic CO₂ production is derived), have been monitored simultaneously for one year in the same area of the northwestern Mediterranean Sea. In the aphotic layer (200–1000 m), particulate organic carbon (POC) can support only 20% of the overall organic matter remineralization. Remineralization rates are consistent with recent calculations of DOC exported from the euphotic layer in this area, confirming the vital importance of DOC in maintaining deep-water metabolism. This finding would apply to other regions of mesotrophic and oligotrophic production and thus affect our understanding of carbon recycling in the water column, new production and O₂ utilization.     

New approaches to transportation forecasting models

In 1992, the Federal Highway Administration awarded small research contracts to four teams of transportation researchers to design alternative approaches for improving the urban travel demand forecasting process. The purpose of these contracts was to enable each research team to explain how transportation planning models could and should be improved to meet the new forecasting requirements brought on by recent legislation, to address the impacts of new transportation technology, and to exploit the travel behavior theories and methodologies that have developed over the past two decades.This paper presents a summary and synthesis of the ideas which emerged from the four research reports. Its purpose is to identify common themes suggested by several of the research teams, to point out what appear to be critical elements missing from some approaches, and to combine the best aspects of the four approaches into a research plan for improving the current generation of travel demand models.Abbreviations CAAA Clean Air Act Amendments - FHWA Federal Highway Administration - GIS Geographic Information System - IIA Independence of Irrelevant Alternatives - IT Information Technology - IVHS Intelligent Vehicle Highway System - SUE Stochastic User Equilibrium - TCM Transportation Control Measures - UTPS Urban Transportation Planning System - VMT Vehicle Miles of Travel The paper was prepared as a report for the Federal Highway Administration.     

The effects of chord length and boundary conditions on the static strength of a tubular T-joint under brace compression loading

Non-linear finite element analysis is used to assess the static collapse strength of a sample tubular T-joint configuration subjected to compressive brace loading. Two series of models are used to assess the effects of varying the chord length L, one series having simply supported chord ends and the other having fixed chord ends. It is shown that chord length and boundary conditions can have a significant influence on static collapse loads. The results are discussed in the light of current design procedures.     

IEC列车通信网络

国际电工委员会（ＩＥＣ）和国际铁路联盟（ＵＩＣ）为铁路车辆之间和车辆内互相联接的可编程设备制定了一项标准——《列车通信网络》（ＴＣＮ），其目的是有利于铁路运用部门、装配厂和设备供应商实现世界范围的车辆间的相互操作和插入式设备的联接。文章介绍了ＴＣＮ的体系结构，包括绞线式列车总线（ＷＴＢ）和多功能车辆总线（ＭＶＢ）的功能、技术参数、公共协议及网络管理，并对ＴＣＮ原型的开发、试验验证情况和标准草案工作进程作了简要的说明。     

柴油机气缸盖机械变形和应力的精确三维分析

本文在分析了国内外大量气缸盖结构分析算例特点的基础上,对16V240ZJ柴油机气缸盖的机械应力用三维有限元法在微机上进行了比较全面细致的计算,在计算模型中,对气缸盖各部分结构都不作替代简化;在边界条件的处理方面,计入了气缸套的弹性,并与刚性支承边界条件计算结果进行了比较,计算求得的位移和应力分布规律与实测完全一致,最大位移误差6.5％,最大压应力误差7.4％。     

Prediction of ship brittle fracture casualty rates by a probabilistic method

It has been proposed that grade A should be replaced with a tougher steel for ship construction. This recommendation is not supported by casualty statistics. Brittle fractures have decreased from once every 10 ship years at the time of the Liberty ships, to once every 100 ship years in the 1950s, and now stand at around once every 10,000 ship years. The authors have developed a probabilistic fracture mechanics approach indexed to the Charpy 27 Joule temperature, T_27J. This is used here to analyse the Liberty ship failures. Comparison with a databank of T_27J values for grade A steel spanning 1920 to 1995 suggests that the Liberty ship steel was unusually brittle. The probability analysis shows good agreement between predicted and observed fracture casualty rates for the Liberty ships and helps explain why brittle fractures are now uncommon in grade A steel ships.