远程油门在粉粒物料运输车上的使用

针对原粉粒物料运输车未配备远程电子油门系统使用不便的问题,介绍了加装了远程油门系统的粉粒物料运输车的使用方法,并为远程油门设计加装了定速装置,可以任意调整发动机转速且能实现任意转速定速功能,为今后类似的设计提供了参考。     

Economies of density and factor substitution in Dublin city bus services — a translog approach

The primary aim of the paper is to determine a short‐run cost function for Dublin City Bus Services (DCS), using a translog approach. The results show that there are significant economies of density in the transit operation. The results also indicate that the structure of DCS is characterised by a homothetic production function and that partial elasticities of substitution are non‐unitary.     

Stop-and-go traffic analysis: Theoretical properties,environmental impacts and oscillation mitigation

This study aims (i) to analyze theoretical properties of a recently proposed describing-function (DF) based approach (Li and Ouyang, 2011; Li et al., 2012) for traffic oscillation quantification, (ii) to adapt it for estimating fuel consumption and emission from traffic oscillation and (iii) to explore vehicle control strategies of smoothing traffic with advanced technologies. The DF approach was developed to predict traffic oscillation propagation across a platoon of vehicles following each other by a nonlinear car-following law with only the leading vehicle’s input. We first simplify the DF approach and prove a set of properties (e.g., existence and uniqueness of its solution) that assure its prediction is always consistent with observed traffic oscillation patterns. Then we integrate the DF approach with existing estimation models of fuel consumption and emission to analytically predict environmental impacts (i.e., unit-distance fuel consumption and emission) from traffic oscillation. The prediction results by the DF approach are validated with both computer simulation and field measurements. Further, we explore how to utilize advantageous features of emerging sensing, communication and control technologies, such as fast response and information sharing, to smooth traffic oscillation and reduce its environmental impacts. We extend the studied car-following law to incorporate these features and apply the DF approach to demonstrate how these features can help dampen the growth of oscillation and environmental impact measurements. For information sharing, we convert the corresponding extended car-following law into a new fixed point problem and propose a simple bisecting based algorithm to efficiently solve it. Numerical experiments show that these new car-following control strategies can effectively suppress development of oscillation amplitude and consequently mitigate fuel consumption and emission.     

Spectral and time‐frequency analyses of freeway traffic flow

This paper uses spectral and time‐frequency analyses to treat three macroscopic traffic characteristics, namely, time mean speed, volume and occupancy as stochastic processes. Spectral and time‐frequency analyses are performed to characterize power spectral density (PSD), cross‐PSD, autocorrelation and cross‐correlation of these characteristics using TransGuide traffic data collected from four different freeways. It is found that low‐frequency components dominate the PSDs of speed, volume and occupancy at all times. The magnitude of PSDs decreases dramatically as frequency increases and remains almost at a constant level in high‐frequency regimes. A power law is found to exist, which describes the relationship between the frequency and the PSD of traffic characteristics. It is also found that speed can be properly modeled by a narrowband low‐pass stochastic process in a low‐frequency regime and by a nonzero mean white noise in a high‐frequency regime. Strong periodicities and synchronization are both shown in traffic flow. A variety of frequencies can be excited by congestion, and there is no dominant frequency found in stop‐and‐go traffic. Copyright © 2013 John Wiley & Sons, Ltd.     

城市轨道交通电气系统网络负荷建模方法研究

城市轨道交通电气系统网络存在分散性、时变性、随机性、多样性和非连续性等多种特性。介绍了几种常用的经典负荷模型结构。针对该电气系统网络系统的特点,采用带有反馈模拟云数据生成器,应用隶属度函数与经典负荷模型相结合理论,提出一种基于窗函数的负荷模型建模方法,并对该方法进行了仿真验证。     

具有特色建筑空间的徐家棚车站设计技术探讨

为解决越江大盾构区间引起的大型换乘车站建筑功能复杂多样、使用标准高、结构型式复杂变化的问题,结合已运营的具有特殊建筑空间设计的武汉地铁8号线徐家棚站,全面探讨车站换乘方式、建筑方案、使用功能、空间效果、工程风险、结构受力等问题,并提出合理可行的工程设计创新措施; 借助提升空间、增大柱跨、通透中庭、特色装修及不同层次空间布局,打造车站高大上的空间效果; 采取合理的支撑体系及止水方案,确保长江一级阶地高承压含水层条件下的超深超大基坑的安全; 采取底板设置抗拔桩、板墙节点加腋、临时传力体系和梁柱转换体系措施,解决车站大跨度、大中庭结构设计及开孔多等结构受力问题; 创新Y型扶梯柱和悬吊天桥通道,节约站台公共空间。     

三体船侧体布局及型线优化设计研究

采用分层次优化,首先以总阻力最小为优化目标对某三体船侧体横向和纵向的相对位置进行了优化研究,得到阻力性能最优的三体船侧体布局方案;然后基于侧体最优布局,进行型线优化,最终完成三体船的侧体布局和型线的序列优化。结果表明,所采用的三体船侧体布局及型线优化方法具有可行性,可为三体船船型设计提供参考依据。     

淤泥质港口航道适航密度确定方法的改进

根据浮泥层中船舶航行时船体边壁带动附近浮泥作剪切流动的物理过程与浮泥在缓坡上的重力流之间的相似性,提出以船体边壁附近浮泥层流态转换条件来定义适航密度,以避免现行方法的不确定性,并提出了相应的计算方法。计算表明,适航密度与航行速度和浮泥层厚度有关。在通常航速和0.5~1.5 m浮泥层厚度条件下连云港航道的适航密度约为1.25~1.35g/cm~3。     

东中国海波浪分布特征研究

以美国国家环境预报中心(NCEP)再分析气象资料作为驱动风场条件,运用第三代海浪模式WAM的第四版本(WAMC4)在西北太平洋海域建立二级嵌套波浪模型,利用连云港、冷家沙现场观测波浪资料对模型进行了验证,检验了该模型在东中国海波浪研究中的适用性针对东中国海进行了连续60年(1950—2909)的波浪后报模拟,在此基础上开展了东中国海波浪时空分布特征研究.结果表明:四季的平均有效波高等值线与岸线形状基本保持一致,且由南向北逐渐递减;有效波高分布的季节差异显著,冬季浪高最大,其次为秋季,春季、夏季最小。通过对比分析平均波浪要素和5%累积频率波浪要素的定量关系发现,在渤海范围内,5%累积频率有效波高与平均有效波高之比约为2.75,黄海与东海大部该比值则分别约为2.50和2.35,而5%累积频率平均周期与平均周期的比值在整个东中国海范围内约为1.45。     

船体外板自动展开程序

在船舶结构设计中,外板展开图的信息是船舶设计建造的关键,它的精准性直接影响船舶的建造质量。利用Auto LISP语言编制的外板自动展开程序功能,阐述了按水线、纵剖线和边舱展开及自由展开几种外板展开模式的原理和实现方法,并就程序编制和使用过程中的注意事项作了技术说明。实践证明,该程序的应用提高了外板展开图的绘制精度,保证了图纸质量。