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951.
从柴油发动机的发展历程入手,重点介绍柴油发动机的压缩点火特性、机械特性,及典型柴油系统:柱塞式喷射泵系统和共轨式喷射系统;探析新型柴油发动机的特性。 相似文献
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针对水泥土搅拌桩的粉喷和湿喷两种工艺,分别进行了施工后不同龄期的桩身载荷试验,通过桩顶、桩间土的应力观测以及载荷试验测斜观测,对水泥土搅拌桩加固软土地基的效果进行分析,并对两种工艺的加固效果进行了对比。结果表明,在饱和软土地区,复合地基承载力粉喷桩明显高于湿喷桩,其成桩及加固效果前者好于后者。 相似文献
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动力锥贯入仪经过不断完善和改进,已经形成了较成熟的仪器设备、试验方法、分析方法等,是一种轻便、快捷、可靠的路基和基层材料现场强度检测工具,在路基现场检测中得到了较广泛的应用。对动力锥贯入仪的发展历史、研究现状、仪器设备、试验程序、计算分析、工程应用等方面进行了比较全面的叙述,以便为动力锥贯入仪的推广应用提供参考。 相似文献
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以控制桩帽间土体沉降量在工后沉降量标准范围内为目标,提出带帽控沉疏桩复合地基设计的思路和方法.采用调整桩体中心间距或桩帽尺寸等措施,以改变复合桩土应力比来进行带帽控沉疏桩复合地基设计.基于弹性理论和等沉面思想,不考虑复合桩体自身压缩变形量,简化了带帽刚性桩复合地基复合桩土应力比隐式计算公式,得到了按桩帽间土体沉降计算模... 相似文献
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In a general traffic network under some widely used assumptions, this paper proves that the level of service, represented by the volume-capacity (v/c) ratio, offered by a profit-maximizing private firm on a private toll road is independent of another competitor’s choice of capacity and toll rate for another private toll road. The v/c ratio will be the same as the one provided by a centralized welfare-maximizing traffic authority. Moreover, the ratio remains the same even in a regulated market where the authority imposes a cap for the generalized travel cost on the private toll road. 相似文献
960.
Anthony D. Patire Michael J. Cassidy 《Transportation Research Part B: Methodological》2011,45(4):656-666
A mechanism is unveiled by which congestion forms on a 3-lane, uphill expressway segment, and causes reductions in output flow. Vehicular lane-changing (LC) is key to the mechanism, particularly LC induced by speed disturbances (SDs) that periodically arise in the expressway’s median and center lanes. Early in the rush, when flow was relatively low in the shoulder lane, drivers readily migrated toward that lane to escape the oncoming SDs. The shoulder lane thus acted as a ‘release valve’ for the high vehicular accumulations created by the SDs, such that forced vehicular decelerations were short-lived. The release valve failed only later in the rush, when flow increased in the shoulder lane in response to rising demand. LC induced by the SDs thereafter became disruptive: the decelerations they imposed spread laterally, and a persistent queue formed in all lanes. Long-run output flow dropped each day by 4-11% once the queue engulfed the base of the incline, and impeded vehicle ascent.Subtle details of this mechanism became visible by examining thousands of vehicle trajectories that were extracted from a series of eleven roadside video cameras. Though these trajectories were collected from only a single day, we suspect that the findings can be generalized to other days at the present site, and to other sites. This is because: (i) conspicuous features of the mechanism were repeatedly observed in loop detector data that were measured over many days at the site; (ii) these macroscopic features are consistent with observations previously made at other sites; and (iii) the more subtle details unveiled by the trajectories are compatible with a general theory of multi-lane traffic. 相似文献