Absence behaviour, turnover and disability: A study among city bus drivers in the Netherlands

Absenteeism, turnover and disability, and relationships between them have been studied among city bus drivers in the Netherlands. The theoretical framework for the study was a cumulative process model of work and health. Absenteeism among these drivers was two to three times as high as the national average, while the risk of disablement was more than twice as high as the risk for male Dutch civil servants in general. Bus drivers who had to leave their job for medical reasons did so at a younger age than other groups of civil servants. The main conditions leading to disablement related to the back, tendons and joints (35%), mental disorders (35%) and cardiovascular diseases (12%). It was shown that long-term absenteeism is a strong precursor of future disability. The research suggests a work-related process of progressive deterioration of health and well-being over a reasonably long period of time. Driving city buses seems to be an occupation with high risks for health and well-being.     

基于PXI总线的虚拟数字示波器软件设计

提出了一种基于PXI总线的虚拟数字存储示波器实现方法。介绍了示波器数据采集板原理和底层驱动程序开发过程。结合设计的虚拟示波器面板,阐述在各种用户控制命令和状态下,数据的采集、处理以及波形和测量结果的显示等示波器功能的实现。     

城市公交专用道设置方式解析

建设公交专用道可以保证公交车辆优先通行，从而有效提高道路的人流量。城市公交专用道是城市道路系统的一部分，其通行能力受道路横断面、交叉口入口道以及停靠站设置形式的影响，考虑这几方面的因素，讨论了城市公交专用道设置方法的有关问题，分析了不同公交专用道的设置形式与交通运行状况的关系，并将不同公交停靠站形式进行了对比分析。     

AFC系统车站网络控制实现方式及其发展趋势

该文介绍AFC系统车站网络控制的3种实现方式并进行比较。作为计算机网络技术的发展主流,以太网车站网络控制的实现方式在城市轨道交通网络AFC系统中的应用将不断深入。     

Compressed Natural Gas Bus Safety: A Quantitative Risk Assessment

This study assesses the fire safety risks associated with compressed natural gas (CNG) vehicle systems, comprising primarily a typical school bus and supporting fuel infrastructure. The study determines the sensitivity of the results to variations in component failure rates and consequences of fire events. The components and subsystems that contribute most to fire safety risk are determined. Finally, the results are compared to fire risks of the present generation of diesel-fueled school buses. Direct computation of the safety risks associated with diesel-powered vehicles is possible because these are mature technologies for which historical performance data are available. Because of limited experience, fatal accident data for CNG bus fleets are minimal. Therefore, this study uses the probabilistic risk assessment (PRA) approach to model and predict fire safety risk of CNG buses. Generic failure data, engineering judgments, and assumptions are used in this study. This study predicts the mean fire fatality risk for typical CNG buses as approximately 0.23 fatalities per 100-million miles for all people involved, including bus passengers. The study estimates mean values of 0.16 fatalities per 100-million miles for bus passengers only. Based on historical data, diesel school bus mean fire fatality risk is 0.091 and 0.0007 per 100-million miles for all people and bus passengers, respectively. One can therefore conclude that CNG buses are more prone to fire fatality risk by 2.5 times that of diesel buses, with the bus passengers being more at risk by over two orders of magnitude. The study estimates a mean fire risk frequency of 2.2 x 10(-5) fatalities/bus per year. The 5% and 95% uncertainty bounds are 9.1 x 10(-6) and 4.0 x 10(-5), respectively. The risk result was found to be affected most by failure rates of pressure relief valves, CNG cylinders, and fuel piping.     

分层总线式群集系统设计

给出了一种基于通信效率和群集度比(T_e/I_l)构建有限层总线式松耦合并行系统的一般模型,并详细描述下一个6×6群系统的设计思想和实现过程,工作结果将指导这类系统的集成。     

江苏农村校车管理运营的问题与对策研究

江苏省农村校车管理运营存在很多问题,结合江苏省农村具体情况,研究确立符合江苏省农村校车特点与规律的管理思想,运用全寿命周期管理理论可以建立符合江苏农村校车实际情况的运营管理模式;从法律、市场准入、职能部门建立、教育布局与校车需求分析、运营模式的确定、营运安全监管等六个方面探讨校车运营模式的构建,可以提高江苏省农村校车的安全规范和管理水平。     

一种DCON协议通信的快速处理方法

DCON是一种基于RS-485网络的应用层协议,广泛应用于计算机监控系统中.本文在NET Framework 4.0环境下实现了可靠的数据传输,同时根据DCON的特性引入了协议的快速处理方法,可以有效提高计算机监控系统的可靠性和灵敏度.     

Wavelet‐Based Testing for Serial Correlation of Unknown Form in Panel Models

Wavelet analysis is a new mathematical method developed as a unified field of science over the last decade or so. As a spatially adaptive analytic tool, wavelets are useful for capturing serial correlation where the spectrum has peaks or kinks, as can arise from persistent dependence, seasonality, and other kinds of periodicity. This paper proposes a new class of generally applicable wavelet‐based tests for serial correlation of unknown form in the estimated residuals of a panel regression model, where error components can be one‐way or two‐way, individual and time effects can be fixed or random, and regressors may contain lagged dependent variables or deterministic/stochastic trending variables. Our tests are applicable to unbalanced heterogenous panel data. They have a convenient null limit N(0,1) distribution. No formulation of an alternative model is required, and our tests are consistent against serial correlation of unknown form even in the presence of substantial inhomogeneity in serial correlation across individuals. This is in contrast to existing serial correlation tests for panel models, which ignore inhomogeneity in serial correlation across individuals by assuming a common alternative, and thus have no power against the alternatives where the average of serial correlations among individuals is close to zero. We propose and justify a data‐driven method to choose the smoothing parameter—the finest scale in wavelet spectral estimation, making the tests completely operational in practice. The data‐driven finest scale automatically converges to zero under the null hypothesis of no serial correlation and diverges to infinity as the sample size increases under the alternative, ensuring the consistency of our tests. Simulation shows that our tests perform well in small and finite samples relative to some existing tests.     

我国客车行业的发展战略与实施策略

通过对我国客车产业的现状以及竞争环境的分析,总结产业中存在的问题和不足,同时归纳客车生产企业已具备的优势和面临的机遇,由此提出发展战略制订的指导原则,指出实现成本领先和差异化两种基本竞争战略的思路和途径。