干湿交替条件下膨胀围岩隧道的力学性态研究

以广西南宁膨胀土为围岩材料,制作室内膨胀围岩隧道物理模型。通过对隧道模型进行干湿循环试验,得出围岩在吸水及失水条件下的围岩应力-时间关系曲线及衬砌应变-时间关系曲线。试验认为在吸水过程中大部分测点的围岩压力都经历了增长、减小、不同速率的再增长3个阶段。衬砌变形则经历缓慢增长、急剧增长、急剧减小、微增长4个阶段;在失水过程中,从整体上可以将围岩压力变化分为两部分,即围岩失水收缩致使衬砌和围岩的接触压力下降导致围岩应力值减小以及土体收缩产生收缩应力导致应力监测值增大。并分析这种变化规律的形成机理,证明时间效应和空间效应的存在。为今后膨胀围岩隧道的结构设计和施工优化提供一定的理论参考。     

A new estimation approach for the multiple discrete–continuous probit (MDCP) choice model

This paper develops a blueprint (complete with matrix notation) to apply Bhat’s (2011) Maximum Approximate Composite Marginal Likelihood (MACML) inference approach for the estimation of cross-sectional as well as panel multiple discrete–continuous probit (MDCP) models. A simulation exercise is undertaken to evaluate the ability of the proposed approach to recover parameters from a cross-sectional MDCP model. The results show that the MACML approach does very well in recovering parameters, as well as appears to accurately capture the curvature of the Hessian of the log-likelihood function. The paper also demonstrates the application of the proposed approach through a study of individuals’ recreational (i.e., long distance leisure) choice among alternative destination locations and the number of trips to each recreational destination location, using data drawn from the 2004 to 2005 Michigan statewide household travel survey.     

Assessing the performance of SpeedInfo radar traffic sensors

Traffic speed is a crucial input for real-time traffic management applications. Operating agencies typically deploy their own sensors to collect the measurements, e.g., loop detectors. Recently, SpeedInfo emerged with a different paradigm for traffic speed collection: instead of selling hardware to operating agencies, at each link the company deploys its own Doppler radar in a self-contained wireless unit to measure traffic speeds and then sells the speed data. This study uses well-tuned loop detector-based speed measurements to evaluate 15 of the Doppler radar sensors over several months while the two traffic data collection systems were operating concurrently. The extended study period includes potentially challenging and transient conditions for the radar sensors: both recurrent (rush hour congestion and late night low flow) and nonrecurrent (incidents and precipitation). The analysis took a broad overview, comparing speed measurements from the radar sensors against the concurrent loop detector data and then explicitly looked for any anomalous pattern in the radar data such as latency and system outages. The work found the radar measurements are generally good, but also identified several points that should be considered before deployment, including latency, different biases in free flow and congestion, vulnerability to precipitation, and sensitivity to mounting angle.     

基于径向基函数网络的社会消费品总额预测模型

利用BP、RBF神经网络自适应学习法模型,对社会消费品总额进行了预测和研究,结果表明用RBF网络自适应学习法所建立的模型经过训练后,可得到较精确的预测结果,并具有较强的应用性。     

列车运行自动调整研究回顾与展望

描述列车运行自动调整问题,回顾国内外研究进展,分析该技术的应用现状,并展望该技术未来发展的若干方向。     

频谱分析的一类新算法

本文指出可替代ＦＦＩ法的一类频谱分析新算法，它们以功率谱形式给出，文中给出一个构造算创并与同类算法作了比较。     

浅谈目标管理在汽运企业的应用

从制定科学的目标管理体系、建立完整的目标控制系统、采取有效的保证措施等几个方面阐述了目标管理方法在汽运企业的应用。     

THE CHANGES OF CHILDREN′S BEHAVIOR PROBLEMS IN XI′AN DURING FIVE YEARS FROM 1988 TO 1993

ＢｙｕｓｉｎｇＣＢＣＬ（ＣｈｉｌｄＢｅｈａｖｉｏｒＣｈｅｃｋｌｉｓｔ）ｏｆＸｉ′ａｎｎｏｒｍ，ｔｈｅｃｈｉｌｄｒｅｎ＇ｓｂｅｈａｖｉｏｒｐｒｏｂｌｅｍｓｉｎＸｉ′ａｎｈａｖｅｂｅｅｎｉｎｖｅｓｔｉｇａｔｅｄａｎｄｃｏｍｐａｒｅｄｗｉｔｈｔｈｅｒｅｓｕｌｔｓｏｂｔａｉｎｅｄｂｅｆｏｒｅ１９９３，ｔｈｅｐｏｓｉｔｉｖｅｒｅｓｕｌｔｓｐｒｏｖｉｄｅｓｃｉｅｎｔｉｆｉｃｂａｓｉｓｆｏｒｄｉａｇｎｏｓｉｓａｎｄｒｅｆｅｒｅｎｃｅｆｏｒｔｅａｃｈｅｒｓ．ＭＡＴＥＲＩＡＬＳＡＮＤＭＥＴＨＯＤＳＴｈｅｐｕｐｉｌ…     

Transportation agencies experiences with decision support systems for airport ground access planning

This article reports on a field investigation into the ways that transportation agencies use quantitative and qualitative information for making strategic decisions regarding airport ground access. The study analyzes the value of this information for planning airport ground access improvements at seven major international airport sites.The major finding of the research is that quantitative modeling for strategic decision support is very difficult, costly and time consuming. Modelers are confident that the models are accurate and reliable but executives generally lack confidence in the results. Transportation officials believe that the information supplied is flawed by a number of defects that minimize its value for strategic decision makers. The information defects described in this article provide an analysis of the structural difficulty of using quantitative modeling for transportation problems of strategic importance. To date, qualitative information is not frequently used, but some transportation agencies are considering its application to designing transportation services. Although this study is limited to airport ground access, the authors feel that this evidence, in conjunction with the evidence from other studies in the transportation area, dictates a need for wariness in the development of decision support systems for transportation planners. Developers of decision support systems for transportation planners must be aware of modeling costs and defects and consider how to improve the timeliness, relevance and credibility of information quantitative models provide transportation executives. Fundamentally it is important to recognize that decision makers tend, either singularly or in concert with other individuals or groups, to be the champions of a long-term vision for the community. When modeling produces inconsistent or wide ranging results that contradict their position, decision makers may not only discard modeling activities, but lose confidence in the models altogether. As a consequence, transportation planners are faced with the challenge of how to improve quantitative modeling. The most reliable and effective means for improvement is incorporation of qualitative techniques which provide greater understanding of customer perceptions and human behavior.     

基于时间序列法的舰船运动预报实验研究

采用线性自回归AR模型、具有首前波观测量的ARMA模型以及非线性自回归NAR模型三种方法分别对舰船运动进行预报,将得到的预报结果与实验测量结果进行验证比较,并对最佳预报模式进行讨论.