γ射线管道测垢厚系统计

针对清洗管道过程中测量内垢厚的问题,介绍利用γ射线透射法测量管道垢厚的系统设计。该系统可测量多种管道内垢层厚度,系统样机主要由γ射线收发模块、信号预处理模块、单片机控制模块、上位机管理通讯模块等组成。通过实验,样机可准确测量管道内垢层厚度,为管道的清洗与检测提供了科学依据。     

Hybrid model for prediction of bus arrival times at next station

Effective prediction of bus arrival times is important to advanced traveler information systems (ATIS). Here a hybrid model, based on support vector machine (SVM) and Kalman filtering technique, is presented to predict bus arrival times. In the model, the SVM model predicts the baseline travel times on the basic of historical trips occurring data at given time‐of‐day, weather conditions, route segment, the travel times on the current segment, and the latest travel times on the predicted segment; the Kalman filtering‐based dynamic algorithm uses the latest bus arrival information, together with estimated baseline travel times, to predict arrival times at the next point. The predicted bus arrival times are examined by data of bus no. 7 in a satellite town of Dalian in China. Results show that the hybrid model proposed in this paper is feasible and applicable in bus arrival time forecasting area, and generally provides better performance than artificial neural network (ANN)–based methods. Copyright © 2010 John Wiley & Sons, Ltd.     

新形势下路桥企业青年员工思想存在的问题及对策

文章针在当前路桥企业青年员工思想状况以及存在的问题,提出做好青年员工思想政治工作的看法和对策,为新形势下企业如何做好青年员工思想政治工作,提供参考。     

A time-use activity-pattern recognition model for activity-based travel demand modeling

This study develops a new comprehensive pattern recognition modeling framework that leverages activity data to derive clusters of homogeneous daily activity patterns, for use in activity-based travel demand modeling. The pattern recognition model is applied to time use data from the large Halifax STAR household travel diary survey. Several machine learning techniques not previously employed in travel behavior analysis are used within the pattern recognition modeling framework. Pattern complexity of activity sequences in the dataset was recognized using the FCM algorithm, and resulted in identification of twelve unique clusters of homogeneous daily activity patterns. We then analysed inter-dependencies in each identified cluster and characterized the cluster memberships through their socio-demographic attributes using the CART classifier. Based on the socio-demographic characteristics of individuals we were able to correctly identify which cluster individuals belonged to, and also predict various information related to their activities, such as start time, duration, travel distance, and travel mode, for use in activity-based travel demand modeling. To execute the pattern recognition model, the 24-h activity patterns are split into 288 three dimensional 5 min intervals. Each interval includes information on activity types, duration, start time, location, and travel mode if applicable. Results from aggregated statistical evaluation and Kolmogorov–Smirnov tests indicate that there is heterogeneous diversity among identified clusters in terms of temporal distribution, and substantial differences in a variety of socio-demographic variables. The homogeneous clusters identified in this study may be used to more accurately predict the scheduling behavior of specific population groups in activity-based modeling, and hence to improve prediction of the times and locations of their travel demands. Finally, the results of this study are expected to be implemented within the activity-based travel demand model, Scheduler for Activities, Locations, and Travel (SALT).

     

快速公交系统站台停靠时间模型研究

快速公交系统停靠站台停车延误是影响快速公交运行车速的关键因素之一,因此构建快速公交系统站台停靠时间模型是提升快速公交服务水平的基础理论研究。本文选取盐城BRT-1号线的起始站、中途站、客流离散站等三类站点为研究对象,综合运用数理统计法与数据挖掘法,构建快速公交系统站台停靠时间模型,并对该模型的合理性进行了检验。研究表明:盐城市BRT-1号线三类站台的快速公交车辆停靠时间与上下车乘客人数呈线性关系,即快速公交车辆停靠时间与上下车乘客人数的检验参数R2均大于0.8。     

开口加劲肋正交异性钢桥面铺装力学分析

文章以开口加劲肋正交异性钢桥面铺装体系作为研究对象,建立了包括桥面板和铺装的整体三维有限元分析模型,研究了荷载作用下铺装层的力学特性。分析表明,横向拉应力是开口加劲肋正交异性钢桥面铺装设计的一个重要控制指标;开口加劲肋正交异性钢桥面铺装层间剪应力较大,在铺装结构设计时应注意选择具有较强抗剪强度的粘结材料;开口加劲肋正交异性钢桥面铺装对车辆荷载的应力应变响应具有很强的局部效应。     

管道疲劳寿命的可靠性分析

针对管道的疲劳失效分析,以概率论为基础,结合确定性的疲劳断裂力学估算方法,推导了管道的疲劳裂纹扩展寿命的计算公式.考虑到主要评定参数:初始裂纹尺寸、工况载荷、断裂韧性、机械强度、系数等的不确定性和随机性,应用蒙特卡罗模拟法对这些具有某种特定分布的随机变量进行了随机抽样计算.并利用数值积分法编制了计算机程序,求出在一定可靠度和置信度下的疲劳寿命,并与理论计算方法求得的疲劳寿命进行了比较.还比较了不同初始裂纹尺寸和断裂韧性对疲劳寿命的影响,并给出了算例.分析结果表明:蒙特卡罗模拟法真实地反映评定参数客观存在的不确定性,克服了确定性评定方法的缺点,具有良好的工程指导意义.     

基于壅塞理论的CNG加气管流量计算分析

为了计算CNG加气系统的高压胶管的流量,以气体动力学为基础,建立等截面一维定常绝热摩擦流动的数学模型.利用VC+ +语言编制界面计算程序对模型进行编程求解,对壅塞状态和非壅塞状态下流量以及出口压力进行计算和拟合.当天然气汽车储瓶内的压力小于临界压力时,加气流量最大,且与胶管两端的压差无关,并计算出最大流量与胶管管长的关...     

基于TBM工法的隧洞工程进度定量分析——以引红济石隧洞工程TBM段为例

文章结合QTBM理论,对引红济石隧洞工程前期的开挖进度数据进行了分析统计,结果表明:该工区TBM在Ⅲ类、Ⅳ类围岩中掘进速率较为稳定,而在V类围岩中掘进速率较低;同时,获得了适合该工区的岩体品质参数以及TBM净掘进速率、平均使用率等相关参数;并据此对该工程TBM待开挖段的工程进度进行预测,预测表明剩余6600m的开挖尚需...     

大洪山生态文化旅游区空间发展模式研究

文章针对近域旅游区主导旅游资源相似和相异并存的特点,提出旅游区＂整合-竞合＂发展模式（3C模式）,并以大洪山生态文化旅游区组织与规划为例,提出基于游客行为的旅游线路组织模式及相应的旅游公路网布局结构与交通设计理念。