分布式现场总线控制在铁路信号系统中的应用

利用光纤网络通信技术,采用现场总线分布式控制结构,将信号控制系统的执行层延伸到铁路现场的最前端,实现了对室外现场设备的驱动和采集。     

多功能车辆总线网络中网络节点的设计研究

多功能车辆总线(MVB)是分布式工业控制系统的一种应用形式,其核心部分是网络节点.提出构建一个MVB网络节点的设计方法.采用时序转换机制实现网络节点中上位机Host CPU和网络接口单元(NIU)之间信息的传输,并在实验室条件下进行了仿真试验.试验结果验证了设计的可行性、通用性.     

基于CAN总线网络技术的分布式全自动可控顶控制系统

基于CAN总线网络技术的分布式全自动驼峰可控顶控制系统,是驼峰自动化的发展方向。本文主要介绍了分布式控制系统设计的软件、硬件要点,及控制对象和设计依据。     

基于Web的数据管理系统研究

为适应信号动态检测数据管理需要,应用数据库技术、互联网技术,设计开发了基于Web的全路信号动态检测数据管理系统,面向不同的用户,实现了以B／S方式对信号设备台账的数据库管理和各类检测数据的上传、下栽、实时发布、存储、统计、查询等功能。介绍了系统的基本组成、功能、数据库设计和系统可扩展性、开放式体系结构的构建方法。     

构建全省网管通信网络平台

为适应电信管理网络向集中管理、集中维护方向发展的趋势,建立数据通信网为现有各分散的网管系统(如电话交换网管、传输网管、支撑网管等)提供一个统一的数据通信网络平台。各网管系统的信息都可以在此数据通信网上进行传递,使数据通信网成为一个真正的综合数据通信网。其网络结构是采用以省为中心,辐射地、市的广域网络,形成双星形网络结构。     

Measuring the influence of bus service quality on the perception of users

Encouraging the use of public transport is a key policy goal in many countries. Therefore, public transport should offer the level of quality that accommodates the demands of current users, and importantly, the desires of potential users. This study investigates the influence of the perceived quality of bus service on the perception of both current and potential users. The study draws upon data from 512 questionnaires distributed across Belfast City in the UK. The study utilises a binary logistic regression model to quantify the relationships between the perceived quality of 29 bus indicators (independent) and the perceptions of users towards the overall bus service (dependent). Eleven significant indicators are reported to have significant influence on the perception of users. These indicators are utilised to propose scenarios for optimising the quality of bus service with the perceptions of current and potential users.     

Integrated optimization of bus priority operations in connected vehicle environment

Most previous works associated with transit signal priority merely focus on the optimization of signal timings, ignoring both bus speed and dwell time at bus stops. This paper presents a novel approach to optimize the holding time at bus stops, signal timings, and bus speed to provide priority to buses at isolated intersections. The objective of the proposed model is to minimize the weighted average vehicle delays of the intersection, which includes both bus delay and impact on nearby intersection traffic, ensuring that buses clear these intersections without being stopped by a red light. A set of formulations are developed to explicitly capture the interaction between bus speed, bus holding time, and transit priority signal timings. Experimental analysis is used to show that the proposed model has minimal negative impacts on general traffic and outperforms the no priority, signal priority only, and signal priority with holding control strategies (no bus speed adjustment) in terms of reducing average bus delays and stops. A sensitivity analysis further demonstrates the potential of the proposed approach to be applied to bus priority control systems in real‐time under different traffic demands, bus stop locations, and maximum speed limits. Copyright © 2016 John Wiley & Sons, Ltd.     

The influence of bus service satisfaction on university students' mode choice

The purpose of this study was to determine the relationship between bus service satisfaction and the transport mode of choice among university students in Qatar. The degree of bus service satisfaction was collected directly from questionnaire surveys, in which university students were asked questions in relation to their satisfaction with the bus service they used and their transport mode of choice. These questions were categorized into three factors according to confirmatory factor analysis: service at bus stops, service of busses, and service of drivers. Furthermore, the students were asked which mode of transport they used given the choice between public and private transport. This study presents a structural equation model to determine how much bus service satisfaction affects people's decisions about their transport mode. The results from the analysis showed that three key factors—namely, service at bus stops, service of busses, and service of bus drivers—were strongly correlated to the mode of choice. In particular, the bus stop was strongly associated with ease of use, shade, cleanliness, safety, and crowdedness level, while the bus itself influenced reliability, travel time, and frequency. Complying with traffic laws and the driver's attitude were also important contributors to the level of bus service satisfaction. Ultimately, this study will be beneficial for policy/decision‐makers. It will allow them to determine what needs to be accomplished to encourage people to use public transportation. Copyright © 2016 John Wiley & Sons, Ltd.     

A Comparative Study of Three Multivariate Short-Term Freeway Traffic Flow Forecasting Methods With Missing Data

Short-term traffic flow forecasting is a critical function in advanced traffic management systems (ATMS) and advanced traveler information systems (ATIS). Accurate forecasting results are useful to indicate future traffic conditions and assist traffic managers in seeking solutions to congestion problems on urban freeways and surface streets. There is new research interest in short-term traffic flow forecasting due to recent developments in intelligent transportation systems (ITS) technologies. Previous research involves technologies in multiple areas, and a significant number of forecasting methods exist in the literature. However, most studies used univariate forecasting methods, and they have limited forecasting abilities when part of the data is missing or erroneous. While the historical average (HA) method is often applied to deal with this issue, the forecasting accuracy cannot be guaranteed. This article makes use of the spatial relationship of traffic flow at nearby locations and builds up two multivariate forecasting approaches: the vector autoregression (VAR) and the general regression neural network (GRNN) based forecasting models. Traffic data collected from U.S. Highway 290 in Houston, TX, were used to test the model performance. Comparison of performances of the three models (HA, VAR, and GRNN) in different missing ratios and forecasting time intervals indicates that the accuracy of the VAR model is more sensitive to the missing ratio, while on average the GRNN model gives more robust and accurate forecasting with missing data, particularly when the missing data ratio is high.     

质量比较仪校准的信息化应用

为规范质量比较仪市场,全国质量密度计量技术委员会制定了《JJF1326-2011质量比较仪校准规范》。本文通过调研市场上现有质量比较仪型号,研发数据采集分析软件, 以实现校准过程的数据采集分析的信息化操作。该项目可以减少校准过程中人员的工作量和操作误差,以提高校准结果的准确性和可靠性。该项目适用于现有市场中50余种型号的质量比较仪校准,可推广应用于砝码校准以及其他质量测量的信息化操作。