摩托车油耗试验新国家标准学习与研究

GB 15744—2008《摩托车燃油消耗量限值及测量方法》和GB 16486—2008《轻便摩托车燃油消耗量限值及测量方法》2项新国家标准已经出版发行,今年7月1日正式实施。新国标中试验方法、数据处理、油耗限值与老国标相比变化较大,新标准试验方法和数据处理更科学、细致和严格,同时试验技术难度加大,成本提高。     

绿色标准助推绿色造船

从标准先行的角度介绍了绿色制造定义、绿色设计标准、材料选用标准、绿色制造、工艺、焊接、涂装标准,并提出了绿色造船标准框架。     

长衡客运专线速度目标值的选择

根据长衡客运专线所处位置和在路网中的作用,研究确定不同速度目标值采用的标准,以及确定长衡客运专线速度目标值应考虑的要素。     

制订铁路环境噪声标准的基本方法

按照ISO及UIC关于制订环境噪声标准应遵循的“应基于各国经济、技术和人们对环境的要求不同,制订对应的标准限值,该限值可以给出一个最高极限值来满足环境保护的要求,再另设一个严格的、完全能符合人们环境要求的理想值”准则,目前,国内外通常采用社会调查法来了解社会各相关方对环境噪声的要求,将声级与烦恼度的关系用“高烦恼”来表示所受烦恼的程度,并将调查结果作为制订标准的参考依据。     

青藏铁路格拉段工费标准及降效系数的初探

分析了现行铁路工程工费标准及降效系数等有关规定有青藏铁路格拉段工程的适用性，并采用类比分析法及实际测算法等不同方法，对工费标准及降效系数进行了初步探讨。     

牵引供电系统标准化系列化的必要性及可行性

在参照国外铁路牵引供电系统标准化、系列化的基础上,对我国目前铁路牵引供电系统标准化、系列化的现状和标准不统一造成的影响进行了分析,并对加快我国牵引供电系统标准化、系列化的必要性和可行性作了阐述,提出一些可行的建议.     

北美航线——海上丝绸之路的最远端

北美航线是近代以广州为起点的海上丝绸之路的一部分,开端于美国独立后不久的1784年美国商船“中国皇后号”中国广州之旅．通过北美航线,美国商人以北美的人参、皮货交换中国的茶叶、丝绸和瓷器,在大洋彼岸的这两个国家互通有无、平等相处了整整60年光景．并通过分析北美航线的开端、繁盛和衰落,古为今用,说明了“北美航线”的历史作用．     

最大偏应力屈服准则在π平面上图形的形状、方位

根据塑性力学原理,首先建立π平面与主应力空间的关系模型,然后根据最大偏应力屈服准则在π平面上的表达式,推导并验证最大偏应力屈服准则在π平面上图形的形状和方位,目的在于明确拉伸情况下,最大偏应力屈服准则在π平面上的形状、方位。     

Urban travel time reliability at different traffic conditions

The decision making of travelers for route choice and departure time choice depends on the expected travel time and its reliability. A common understanding of reliability is that it is related to several statistical properties of the travel time distribution, especially to the standard deviation of the travel time and also to the skewness. For an important corridor in Changsha (P.R. China) the travel time reliability has been evaluated and a linear model is proposed for the relationship between travel time, standard deviation, skewness, and some other traffic characteristics. Statistical analysis is done for both simulation data from a delay distribution model and for real life data from automated number plate recognition (ANPR) cameras. ANPR data give unbiased travel time data, which is more representative than probe vehicles. The relationship between the mean travel time and its standard deviation is verified with an analytical model for travel time distributions as well as with the ANPR travel times. Average travel time and the standard deviation are linearly correlated for single links as well as corridors. Other influence factors are related to skewness and travel time standard deviations, such as vehicle density and degree of saturation. Skewness appears to be less well to explain from traffic characteristics than the standard deviation is.     

A stochastic analysis of highway capacity: Empirical evidence and implications

This paper presents a stochastic characterization of highway capacity and explores its implications on ramp metering control at the corridor level. The stochastic variation of highway capacity is captured through a Space–Time Autoregressive Integrated Moving Average (STARIMA) model. It is identified following a Seasonal STARIMA model (0, 0, 2₃) × (0, 1, 0)₂, which indicates that the capacities of adjacent locations are spatially–temporally correlated. Hourly capacity patterns further verify the stochastic nature of highway capacity. The goal of this paper is to study (1) how to take advantage of the extra information, such as capacity variation, and (2) what benefits can be gained from stochastic capacity modeling. The implication of stochastic capacity is investigated through a ramp metering case study. A mean–standard deviation formulation of capacity is proposed to achieve the trade-off between traffic operation efficiency and robustness. Following that, a modified stochastic capacity-constraint ZONE ramp metering scheme embedded cell transmission model algorithm is introduced. The numerical experiment suggests that considering capacity variation information would alleviate the spillback effect and improve throughput. Monte Carlo simulation further supports this argument. This study helps verify and characterize the stochastic nature of capacity, validates the benefits of using capacity variation information, and thus enhances the necessity of implementing stochastic capacity in traffic operation.