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文章介绍了道路平面交叉口竖向设计的原则和一般形式,阐述了常用的交叉口竖向设计方法及适用性,并结合工程设计实例,对比分析了两套拟定交叉口竖向设计方案的优缺点,得出最优方案,为今后城市道路交叉口竖向设计提供参考。 相似文献
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大多数城市中,公交车普遍存在可靠性不高的现象,提出可靠的公交这一理念,分析公交运行可靠性的影响因素,给出改进措施,保证公交在线路运行上的优先性,达到准点可靠,提高公交效率的目的。 相似文献
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3Cr13电加热道岔融雪弹性卡在使用中发生断裂,分析断裂弹性卡化学成分,对其断口进行宏观和微观观察,结果表明断裂的原因为腐蚀性介质环境和交变应力共同作用下形成的多源疲劳和应力腐蚀。提出优化弹性卡结构、使用偏碱性防腐涂料对3Cr13弹性卡进行表面处理的应对措施。 相似文献
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The effectiveness of transit-based emergency evacuation highly depends on the location of pick-up facilities, resource allocation, and management. These facilities themselves are often subject to service disruptions during or after the emergency. This paper proposes a reliable emergency facility location model that determines both pre-emergency facility location planning and the evacuation operations afterwards, while facilities are subject to the risk of disruptions. We analyze how evacuation resource availability leverages individual evacuees’ response to service disruptions, and show how equilibrium of the evacuee arrival process could be reached at a functioning pick-up facility. Based on this equilibrium, an optimal resource allocation strategy is found to balance the tradeoff between the evacuees’ risks and the evacuation agency’s operation costs. This leads to the development of a compact polynomial-size linear integer programming formulation that minimizes the total expected system cost from both pre-emergency planning (e.g., facility set-up) and the evacuation operations (e.g., fleet management, transportation, and exposure to hazardous surroundings) across an exponential number of possible disruption scenarios. We also show how the model can be flexibly used to plan not only pre-disaster evacuation but also post-disaster rescue actions. Numerical experiments and an empirical case study for three coastal cities in the State of Mississippi (Biloxi, Gulfport, and D’lberville) are conducted to study the performance of the proposed models and to draw managerial insights. 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(9):719-736
The increasing popularity of sport utility/light-duty vehicles has prompted the investigation of active roll management systems to reduce vehicle body roll. To minimize vehicle body roll and improve passenger comfort, one emerging solution is an active torsion bar control system. The validation of automotive safety systems requires analytical evaluation and laboratory testing prior to implementation on an actual vehicle. In this article, a computer simulation tool and accompanying hardware-in-the-loop test environment are presented for active torsion bar systems to study component configurations and performance limits. The numerical simulation illustrates that the hydraulic cylinder extension limits the active torsion system’s ability to provide body roll angle reduction under various driving conditions. To compare the control system’s time constant and body roll minimization capabilities for different hydraulic valve assemblies and equivalent hose lengths, an experimental test stand was created. For a typical hydraulic pressure and hose diameter, the equivalent hose length was not a key design variable that impacted the system response time. However, the servo-valve offered a quicker transient response and smoother steady-state behavior than the solenoid poppet actuators that may increase occupant safety and comfort. 相似文献
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《铁道标准设计通讯》2016,(9):42-48
在线路纵断面的设计中引入节能坡设计理念,对优化线路纵断面设计、降低牵引能耗值和节省运营支出具有重要意义。根据高速铁路的特点,提出高速铁路进站节能坡的设计方法和计算算法,给出计算流程,确定各影响参数的约束条件。开发进站节能坡设计程序模块,实现多参数化的进站节能坡设计。在此基础上,采用计算机仿真分析方法,对车站坡段坡度、车站中心至节能坡变坡点距离、动车组编组质量、进站制动力使用系数、节能坡进入初始速度5个主要影响因素进行计算和仿真分析,确定各因素对进站节能坡的影响程度,为进站节能坡的设计提供参考和依据。 相似文献
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Transit agencies frequently upgrade rail tracks to bring the system to a state of good repair (SGR) and to improve the speed and reliability of urban rail transit service. For safety during construction, agencies establish slow zones in which trains must reduce speed. Slow zones create delays and schedule disruptions that result in customer dissatisfaction and discontinued use of transit, either temporarily or permanently. While transit agencies are understandably concerned about the possible negative effects of slow zones, empirical research has not specifically examined the relationship between slow zones and ridership. This paper partially fills that gap. Using data collected from the Chicago Transit Authority (CTA) Customer Experience Survey, CTA Slow Zone Maps, and, the Automatic Fare Collection System (AFC), it examines whether recurring service delays due to slow zones affect transit rider behavior and if the transit loyalty programs, such as smart card systems, increase or decrease rider defections. Findings suggest that slow zones increase headway deviation which reduces ridership. Smart card customers are more sensitive to slow zones as they are more likely to stop using transit as a result of delay. The findings of this paper have two major policy implications for transit agencies: (1) loyalty card users, often the most reliable source of revenue, are most at risk for defection during construction and (2) it is critical to minimize construction disruptions and delays in the long run by maintaining state of good repair. The results of this paper can likely be used as the basis for supporting immediate funding requests to bring the system to an acceptable state of good repair as well as stimulating ideas about funding reform for transit. 相似文献