燃气轮机应用于车用动力装置的可行性分析研究

本文描述了燃气轮机的当前发展现状,重点阐述了其应用于车辆的具体方式,以及相应的优势和劣势,并介绍了采用陶瓷材料的燃气轮机以及新型的燃气轮机混合动力汽车,分析了其应用可行性,提出了提高燃气轮机燃油经济性的有效措施。文章最后对车用燃气轮机的前景进行了展望,为科学研究及工程应用提供了必要的理论依据。     

公路隧道减震模型试验及数值模拟

文章以嘎隆拉隧道洞口段为原型,拟定了相似关系,选取了围岩和衬砌的相似材料,制作了公路隧道减震试验模型。在试验模型中设置了减震层,选择了振动台模型试验测点的布置位置,制定了加载制度,进行了振动台加载试验;分析了试验结果,并与有限元分析结果进行了对比,定义了减震率;从应力和应变两方面分析了减震层的动力特性及减震效果,得出减震层的设置对隧道减震能起到一定的作用。     

杨伯让:阔笔泼洒,织就绝美画卷

千年的铁树开花了千年的铁树开花了,青海人心眼里笑了。西部大开发传红了,青海的好机遇到了。公路设施发展了,青海的模样儿俊了。经济大发展有望了,富裕的好日子来了。——青海省交通史志编审委员会办公室主任李生禄,2004年秋朴实淳厚——这便是记者见到青海省交通厅党委书记、厅长杨伯让的第一印象。办公室的书柜覆满整面墙壁,手机和办公室电话此起彼伏。听身边的人说,他事事亲力亲为,办公室的文件资料都是自己整理收拾;     

TBM盘形滚刀的质量控制及其检测维修技术

文章在消化引进技术的基础上,对盘形滚刀的损坏规律进行了深入的分析,对如何提高盘形滚刀的寿命、降低刀具消耗进行了深入的研究,实践中取得了很好的成果,提高了掘进速度,降低了掘进成本,形成了技术经济性能优良的盘形滚刀检测维修技术。其研究成果可供TBM施工单位参考。     

国际物流统计核算的基本情况及国内外比较

本文系统梳理了国内外物流业统计核算的基本情况,总结了国际物流统计核算的主要特点,并与我国情况进行了对比分析,借鉴了相关经验,提出了发展方向。     

关于我国物联网发展的思考

本文首先分析了物联网的相关概念,界定了物联网的定义;在此基础上,提出了我国物联网的建设目标,给出了中国物联网基本架构,提出并分析了统一建设和分级建设两种物联网解析系统的建设策略;最后,给出了中国物联网的发展途径和建设进程。     

天然气管道氮气置换技术研究

针对新建或需要检修的天然气管道,介绍了其投产前用氮气置换空气的几种方法,阐述了它们的工作原理与实施步骤,对比分析了它们的优缺点,从而得出各种方法的适用场合,同时,探讨并总结了氮气置换过程中注氮温度、注氮压力、注氮点、注氮量、天然气推进速度等操作参数的确定方法,得出了相应的结论,为确保天然气管道的安全投产奠定了基础.针对置换工艺与操作参数最优化的确定方法,提出了意见和建议.     

高速铁路缩小区域差距的传导机制分析

高速铁路加速了要素、资源的流动性,拓展了市场半径,区域经济更加一体化,对缩小区域差距构建了要素流通和配置机制;高速铁路增强了区域开放程度,为各区域快速增长创造条件,为拓展我国空间发展结构铺平道路;高速铁路拉动了旅游等现代服务业产群的发展,促进了消费,带动了滞后区域的人力资本水平跃迁。     

顺序输送在东黄复线中的应用

介绍了顺序输送的特点 ,分析了顺序输送混油产生的机理 ,给出了混油量的计算公式 ,对影响混油量的因素进行了分析 ,介绍了混油的切割方法 ,对顺序输送管道的水力特性进行了分析。     

船舶节能在压载水系统方面的探索

文章介绍了压载水的危害,讨论了压载水管理的优缺点,分析了Ballast-Free系统及其环保节能的优点,最后对Ballast-Free的设计做了展望。     

Vehicle detection grammars with partial occlusion handling for traffic surveillance

Traffic surveillance is an important topic in intelligent transportation systems (ITS). Robust vehicle detection is one challenging problem for complex traffic surveillance. In this paper, we propose an efficient vehicle detection method by designing vehicle detection grammars and handling partial occlusion. The grammar model is implemented by novel detection grammars, including structure, deformation and pairwise SVM grammars. First, the vehicle is divided into its constitute parts, called semantic parts, which can represent the vehicle effectively. To increase the robustness of part detection, the semantic parts are represented by their detection score maps. The semantic parts are further divided into sub-parts automatically. The two-layer division of the vehicle is modeled into a grammar model. Then, the grammar model is trained by a designed training procedure to get ideal grammar parameters, including appearance models and grammar productions. After that, vehicle detection is executed by a designed detection procedure with respect to the grammar model. Finally, the issue of vehicle occlusion is handled by designing and training specific grammars. The strategy adopted by our method is first to divide the vehicle into the semantic parts and sub-parts, then to train the grammar productions for semantic parts and sub-parts by introducing novel pairwise SVM grammars and finally to detect the vehicle by applying the trained grammars. Experiments in practical urban scenarios are carried out for complex traffic surveillance. It can be shown that our method adapts to partial occlusion and various challenging cases.     

An investigation of the reliability of real-time information for route choice decisions in a congested traffic system

This paper investigates the reliability of information on prevailing trip times on the links of a network as a basis for route choice decisions by individual drivers. It considers a type of information strategy in which no attempt is made by some central controller or coordinating entity to predict what the travel times on each link would be by the time it is reached by a driver that is presently at a given location. A specially modified model combining traffic simulation and path assignment capabilities is used to analyze the reliability of the real-time information supplied to the drivers. This is accomplished by comparing the supplied travel times (at the link and path levels) to the actual trip times experienced in the network after the information has been given. In addition, the quality of the decisions made by drivers on the basis of this information (under alternative path switching rules) is evaluated ex-post by comparing the actually experienced travel time (given the decision made) to the time that the driver would have experienced without the real-time information. Results of a series of simulation experiments under recurrent congestion conditions are discussed, illustrating the interactions between information reliability and user response.     

The use of the bicycle

The rediscovery of the bicycle by the public, by politicians and by professional urban transportation planners as a mode of transport which is perfectly in harmony with the goals of environmental protection, energy saving and personal fitness has stimulated this empirical study on the actual use of the bicycle by various population groups for obligatory and discretionary trip purposes. The influence on bicycle usage of such factors as age, education, car availability, residential density and town size, topography and time of year is analysed in this paper for selected population groups. For housewives from motorized households logit‐models were designed and calibrated to model their modal choice for shopping trips with special references to the bicycle. From the empirical results, the groups with the largest potentials for cycling are identified and the extent to which the potentials could be activated by specific policies is discussed. The research is based on a large sample held to be representative for the Federal Republic of Germany in 1976 and is supplemented by more recent surveys in selected German cities conducted by SOCIALDATA Munich.     

含甲醇污水缓蚀阻垢试验研究

油气田产出的污水,矿化度一般较高,油分和机械杂质含量都较高,经絮凝剂除掉悬浮颗粒后还具有结垢和腐蚀的倾向。文中对华北石油局采气厂的污水进行了阻垢试验和缓蚀试验,经过对几组不同的阻垢剂和缓蚀剂的实验效果的对比,选出了适合水质特点的阻垢剂和缓蚀剂,并对相关的影响因素进行了分析,得出添加浓度大于20 mg/L的IMC-50缓蚀剂,投加量为20～30 mg/L的乙二胺四乙酸盐（EDTA）作防垢剂,可取得较好效果。     

不同本构模型对浅埋暗挖隧道施工引起地层扰动分析

为了研究不同本构模型对浅埋暗挖隧道施工引起地层扰动的影响,本文基于FLAC3D软件,将莫尔库伦(Mohr-Coulomb,MC)本构模型以及Peck公式计算隧道开挖引起的地表处地层沉降进行对比,结果表明,与Peck公式的计算结果相比,MC模型的计算结果在隧道中心线处的沉降量较小,且在远离隧道中心处的地层出现明显隆起。在此基础上,分析了发生隆起的原因,提出由于隧道下方的回弹土体受到刚度较大的衬砌的约束,从而引起地面产生隆起的假设,并在降低支护结构的刚度条件下,证明了该假设的准确性。通过进一步采用MC模型和修正剑桥(Modified Cam Clay,MCC)本构模型进行对比计算分析,发现MCC模型计算在地表各处的沉降量与Peck公式计算结果基本吻合,均大于MC模型的预测,而且MCC模型能避免地表非真实隆起的产生。可见,相较于MC模型,MCC模型更适于软土地层浅埋暗挖隧道的地表沉降预测。     

输气站场管道振动原因分析

输气站场管道异常振动会造成管系疲劳失效,给安全生产造成巨大的隐患。文中从振源方面将管道振动分为机械导致的振动和流体导致的振动,并对其进行原因分析。研究表明:机械导致的振动通常为转动设备本体设计不合理或安装质量问题导致的振动传递给管道;流体导致的振动通常是管内气流脉动引起的气柱共振或机械共振。利用研究结果对某输气站场管道振动原因进行分析,发现是气流脉动产生的机械共振所导致,建议在设计天然气站场工艺时要尽量避免流场的剧烈、频繁变化,以减少或避免流致振动。     

Platoons of connected vehicles can double throughput in urban roads

Intersections are the bottlenecks of the urban road system because an intersection’s capacity is only a fraction of the maximum flows that the roads connecting to the intersection can carry. This capacity can be increased if vehicles cross the intersections in platoons rather than one by one as they do today. Platoon formation is enabled by connected vehicle technology. This paper assesses the potential mobility benefits of platooning. It argues that saturation flow rates, and hence intersection capacity, can be doubled or tripled by platooning. The argument is supported by the analysis of three queuing models and by the simulation of a road network with 16 intersections and 73 links. The queuing analysis and the simulations reveal that a signalized network with fixed time control will support an increase in demand by a factor of (say) two or three if all saturation flows are increased by the same factor, with no change in the control. Furthermore, despite the increased demand vehicles will experience the same delay and travel time. The same scaling improvement is achieved when the fixed time control is replaced by the max pressure adaptive control. Part of the capacity increase can alternatively be used to reduce queue lengths and the associated queuing delay by decreasing the cycle time. Impediments to the control of connected vehicles to achieve platooning at intersections appear to be small.     

装配式输油管线的抗碾压能力分析

敷设在地面的输油管线可能受到行进车辆的碾压和其他物体的碰撞冲击,使管线破坏而失去使用功能。因此,研究管道在静、动载荷下的强度有着重要的实际意义。采用ANSYS及LS-DYNA软件对装配式输油管线建立了有限元模型,进行了静、动态弹塑性有限元数值计算,得到了其可承受的最大载荷和相应的变形。计算结果表明：过载碾压会使管子产生局部的凹陷;管线的承载能力随管子的壁厚增加而提高;管子在高速冲击碾压下会产生较大的变形,冲击的动变形大于静载下的变形,而震荡的动应力小于稳定静载下的静应力。     

Application of Lagrangian relaxation approach to α-reliable path finding in stochastic networks with correlated link travel times

This study investigates the important problem of determining a reliable path in a stochastic network with correlated link travel times. First, the distribution of path travel time is quantified by using trip records from GPS probe vehicles. Second, the spatial correlation of link travel time is explicitly considered by using a correlation coefficient matrix, which is incorporated into the α-reliable path problem by Cholesky decomposition. Third, the Lagrangian relaxation based framework is used to handle the α-reliable path problem, by which the intractable problem with a non-linear and non-additive structure can be decomposed into several easy-to-solve problems. Finally, the path-finding performance of this approach is tested on a real-world network. The results show that 15 iterations of calculation can yield a small relative gap between upper and lower bounds of the optimal solution and the average running time is about 5 s for most OD settings. The applicability of α-reliable path finding is validated by a case study.