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为分析单叶片螺旋钢桩在砂土地层竖向抗压承载特征,结合单叶片螺旋钢桩现场静载试验进行有限元软件模拟。将数值计算结果与现场实测数据进行对比分析,验证其数值计算结果的可靠性,其次采用该有限元软件分别模拟不同相对密实度砂土中几何参数不同的单叶片螺旋钢桩静载试验而得到不同荷载-位移曲线,同时将螺旋叶片直径的5%位移值对应荷载作为桩极限承载力。考虑砂土相对密实度,钢桩埋深,螺旋叶片直径,中心钢轴4个参数变化对单叶片螺旋钢桩极限承载力影响。结果表明:单叶片螺旋钢桩桩周土层的相对密实度和桩埋深是影响承载力的主要参数,螺旋钢桩叶片直径影响次之,钢轴直径的影响最小;同时,单叶片螺旋钢桩极限承载力增量百分比在松砂中最大,中密砂次之,密砂最小。 相似文献
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介绍了机载相控阵雷达的主要工作方式,分析了机载相控阵雷达战术性能飞行验证的参数,讨论了机载相控阵雷达战术性能飞行检验的统计科目和统计方法,对机载相控阵雷达战术性能飞行检验中的数据处理进行了简要的探讨,为飞行试验方案的设计和相关标准的建立打下基础。 相似文献
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This paper introduces a relocation model for free-floating Carsharing (FFCS) systems with conventional and electric vehicles (EVs). In case of imbalances caused by one-way trips, the approach recommends profit maximizing vehicle relocations. Unlike existing approaches, two types of relocations are distinguished: inter zone relocations moving vehicles between defined macroscopic zones of the operating area and intra zone relocations moving vehicles within such zones. Relocations are combined with the unplugging and recharging of EVs and the refueling of conventional vehicles. In addition, remaining pure service trips are suggested. A historical data analysis and zone categorization module enables the calculation of target vehicle distributions. Unlike existing approaches, macroscopic optimization steps are supplemented by microscopic rule-based steps. This enables relocation recommendations on the individual vehicle level with the exact GPS coordinates of the relocation end positions. The approach is practice-ready with low computational times even for large-scale scenarios.To assess the impact of relocations on the system’s operation, the model is applied to a FFCS system in Munich, Germany within three real world field tests. Test three shows the highest degree of automation and represents the final version of the model. Its evaluation shows very promising results. Most importantly, the profit is increased by 5.8% and the sales per vehicle by up to 10%. The mean idle time per trip end is decreased by 4%. 相似文献
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This paper shows the results of a comparative fleet test the main objective of which was to measure the influence of Low Viscosity Oils (LVO) over the fuel consumption and CO2 emissions of urban buses. To perform this test, 39 urban buses, classified into candidate and reference groups depending on the engine oil viscosity, covered a 60,000 km mileage corresponding to two rounds of standard Oil Drain Interval (ODI). In the same way, for 9 buses of the 39 buses, the effect of differential LVO over fuel consumption and their interaction with engine LVO was assessed during the second ODI.Test results confirm that the use of LVO could reduce fuel consumption, hence CO2 emissions. However, special attention should be taken prior to its implementation in a fleet, particularly if the vehicles are powered by engines with high mechanical and thermal stresses during vehicle operation because this could lead to friction loss increase, loss of the potential fuel consumption reduction of LVO and, in the worst scenario, higher rates of engine wear. 相似文献
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针对目前铁路隧道超挖普遍较大的问题,从现场存在的钻孔质量不高、爆破装药结构不规范、封堵工艺落实不到位等方面进行分析,研究控制铁路隧道超挖的工艺措施。经现场多次试验证明,在周边眼采取PVC管材间隔装药及封堵水炮泥等一系列优化措施后,隧道超挖控制取得良好效果,在节约炸药单耗的同时,最大限度减少喷射混凝土超耗,降低施工成本、加快施工进度,同时也可避免因超挖太大给施工带来的危险。 相似文献
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