双线铁路隧道双块式无碴轨道整体道床曲线段施工快速测量技术

无碴轨道整体道床测量作为无碴轨道施工的关键工序,通过引进国外无碴道床施工测量技术、设备进行消化、吸收和再创新。实现轨道的高平顺、精确的几何线性参数以及达到快速施工测量的目的。结合温—福铁路飞鸾隧道无碴整体道床施工测量实践,介绍测量人员、设备配置情况及采用简易的轨排架粗调测量控制方法,确定固定的测量流程与轨检小车相结合、无碴轨道施工测量控制过程及其注意事项。既确保了长大隧道无碴轨道精度要求,又实现快速施工的目的。     

在南京地铁洞外平面首级控制网复测中的应用

介绍了将GPS静态测量技术应用于地铁首级控制测量中,能够达到高精度、高效益、大大提高作业效率及降低劳动强度等目的,对整条地铁线路的正确贯通提供了强有力的保障。     

An investigation of tour generation models combining two waves of household travel surveys through pooled models

This paper presents a study that examines two waves of travel survey data through a pooled model structure. The pooled model structure provides a means to take advantage of multiple data sources which will lead to a better estimate and understanding of travel behavior. In particular, it accounts for the difference in data variance and therefore allows for the comparison of the true impacts of the model parameters on travelers’ tour-making behavior. Larger variance is found in the 1998 data than in the 2010 data. Comparison between model parameters reveals significant behavioral changes among several socio-economic and demographic groups. In terms of common variables, the magnitude of the coefficient values has generally decreased, which conforms to the overall decreasing trend in traveling. Overall, the model equality tests indicate that the models developed based on the two data sources do not have equal taste parameters, thus the transferability hypothesis is rejected. The results of this study are expected to have implications for the application of models based on cross-sectional data, especially over long time periods.     

长江口水域高精度水文测量四维无缝基准的建立及应用

在宽阔的潮汐河段,由于潮汐和地形的影响,大范围的同步水文测验的精度和可靠性受到了很大的限制。为了得到高精度的水文测量成果,使同步观测资料和时间序列资料具备良好的可比性,需要建立高精度的平面基准、高程基准和速度基准。理论和实践表明,建立大范围内的高精度的GNSS(global navigation satellite system)控制网,基于RTK(real-time kinematic)测量方式进行三维水深测量、基于RTK的速度参考进行流量测量,是在大范围条件下开展高精度同步水文观测的有效途径。     

Behavior of taxi customers in hailing vacant taxis: a nested logit model for policy analysis

This study models and examines the taxi customers' preferences for hailing vacant taxis on streets. A stated preference survey was conducted to randomly select and interview 1242 taxi customers at taxi stands and pedestrians on streets, who had experiences of taking taxis recently, about their choices under different given hypothetical scenarios. In total, 4968 observations were collected and used for developing the discrete choice models for the analysis. To account for the potential correlations among alternatives, two nested logit models are developed, calibrated, and compared with a standard multinomial logit model in the investigation. The results of likelihood ratio test demonstrate that one of the developed nested logit models is better than the standard multinomial logit model to describe the search behavior of taxi customers. The model results also show that the walking time to and the waiting time at the location for hailing taxis, the extra travel time to the destination because of local circulation for finding a way from the pickup location heading to a passenger's destination, as well as the taxi customers' perceptions for walking to and waiting at taxi stands were found as significant factors to influence their decisions. In addition, the results of market segmentation analysis illustrate the variations in taxi‐search strategies of taxi customers in different districts and regions. Some policy implications on introducing more taxi stands and improving the utilization rates of taxi stands are also discussed. We believe that the proposed models, findings, and discussion are useful for developing micro‐simulation models to evaluate the performance of road traffic networks with taxi services and developing simulation‐based optimization models to answer policy questions related to taxi services. Copyright © 2015 John Wiley & Sons, Ltd.     

Port Decision Maker Perceptions on the Effectiveness of Climate Adaptation Actions

Effective adaptation to climate change impacts is rapidly becoming an important research topic. Hitherto, the perceptions and attitudes of stakeholders on climate adaptation actions are under researched, partly due to the emphasis on physical and engineering aspects during the adaptation planning process. Building on such considerations, the paper explores the perceptions of port decision makers on the effectiveness of climate adaptation actions. The findings suggest that while port decision makers are aware of potential climate change impacts and feel that more adaptation actions should be undertaken, they are skeptical about their effectiveness and value. This is complemented by a regional analysis on the results, suggesting that more tailor-made adaptation measures suited to local circumstances should be developed. The study illustrates the complexity of climate adaptation planning and of involving port decision makers under the current planning paradigm.     

地铁屏蔽门风压实测研究

将风洞动态测压技术应用于地铁屏蔽门风压测试,进行国内首次地铁屏蔽门风压现场实测,确定各种工况下屏蔽门上的风压大小和规律.重点介绍了测试方法并选择性地对测试结果进行分析.     

舰船空气采样感烟探测技术的应用研究

介绍了空气采样感烟火灾探测技术的工作原理和特点,结合舰船消防系统火灾探测技术现状和探测保护部位的特殊性,设计了舰船典型机电舱室的空气采样感烟探测报警系统,通过建立陆上燃烧室模拟实船机电舱室保护区进行了火灾探测对比试验。     

珠江口水域地质调查作业水上风险管理

由于珠江口水域的特殊性和复杂性,在该水域开展地质调查作业使得水上交通风险增大,如何在特定的水域实施特定的作业工艺时采取相应的安全保障措施,具有较强的实践指导意义。笔者通过珠江口实际案例分析开展通航安全保障性探讨,针对珠江口水域通航环境进行水上交通风险分析。从涉及到的作业施工方、作业水域周围过往船舶以及海事管理等其他保障服务部门诸方面,在分析地质调查作业整体系统与外界环境进行相关风险耦合后存在的风险基础上,提出针对性的通航安全保障性措施建议,以此来降低发生水上交通事故的风险概率,并为类似的水上地质调查项目开展通航安全评估提供参考。     

基于PC机的雷达图像信号采集与显示系统

提出了一种基于PC机的雷达图像信号采集与显示系统的实现方法。整个系统设计包括硬件电路设计、固件设计以及上位机软件编程。采用CPLD作为硬件采集电路的核心元件,控制外围电路采集雷达图像信号到采集卡上的缓冲区中。采集卡使用2片双口RAM构成双缓冲区结构,当1块缓冲区完成1条扫描线数据存储后,数据会通过PCI总线被取走。软件设计则分为驱动程序以及应用程序设计2部分。驱动程序收到CPLD取数据信号后,会将采集到的雷达图像数据从采集卡上的缓冲区复制到应用程序缓冲区中等待处理。最终,应用程序将缓冲区中数据取出,进行各种处理后,将最终的雷达图像在PC机显示器上进行显示。