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Variability of travel times on the United States freight rail network is high due to large network demands relative to infrastructure capacity, especially when traffic is heterogeneous. Variable runtimes pose significant operational challenges if the nature of runtime variability is not predictable. To address this issue, this article proposes a data-driven approach to predict estimated times of arrival (ETAs) of individual freight trains, based on the properties of the train, the properties of the network, and the properties of potentially conflicting traffic on the network. The ETA prediction problem from an origin to a destination is posed as a machine learning regression problem and solved using support vector regression trained and cross validated on over two years of detailed historical data for a 140 mile section of track located primarily in Tennessee, USA. The article presents the data used in this problem and details on feature engineering and construction for predictions made across the full route. It also highlights findings on the dominant sources of runtime variability and the most predictive factors for ETA. Improvement results for ETA exceed 21% over a baseline prediction method at some locations and average 14% across the study area. 相似文献
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采用对隧道洞室周边及开挖面的土体施加由盾构机引起的各种荷载的方法模拟盾构施工,通过变化注浆压力及推进力研究盾构施工对周边土体及单桩基础的影响.增加注浆压力是减小盾构推进对周围土体影响的最有效的措施.当注浆压力足够大,推进力、盾尾脱离及浆液硬化对土体的影响程度相同.若使隧道顶点的沉降及隧道底部土体的回弹减小相同的数量,底部注浆孔的压力要大于顶部注浆孔的压力.当推进力大于临界值时,推进力对隧道周边土体的影响明显增加.隧道周边及地表处各点的位移变化主要发生在盾构机通过这些点所在位置时,衬砌生成后,随后的开挖步对其影响很小.桩侧隧道洞室衬砌生成后,随后开挖步施加的注浆压力可以明显减小桩顶沉降,注浆压力越大,桩顶最终沉降越小.推进力对桩顶沉降影响不明显.盾构施工引起的桩顶和桩底的沉降始终相同,即桩整体下沉.桩顶无荷载及桩顶施加工作荷载时,开挖引起的桩顶沉降相同;桩顶施加极限荷载时,开挖引起的桩顶沉降明显增加. 相似文献
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电动汽车电池剩余使用寿命预测是当下电池研究领域的热点内容,现有电池剩余使用寿命预测模型大多基于单一预测指标,预测精度较低,模型的泛化性能较差。本文通过实车数据构建了GM-LSTM的Stacking融合模型,实现电动汽车电池剩余使用寿命的准确预测。首先根据电池剩余使用寿命影响因素,提取车辆真实的运行参数和环境参数,基于随机森林算法筛选最优特征集合作为模型输入,其次选择差分整合移动平均自回归算法对所选特征进行惯性延伸,克服数据时间维度上的限制,最后基于数据特点,分别建立灰色预测模型和长短时记忆神经网络模型实现电池剩余使用寿命预测,并通过Stacking模型融合进一步降低预测误差。结果表明:模型融合
后平均相对误差为1.6%,平均绝对误差为0.013,能够稳定可靠的实现电动汽车电池剩余使用寿命预测。 相似文献
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针对珊瑚礁岩土复杂工程特性所带来的钢管桩沉桩收锤标准难确定、沉桩施工高程难统一等难题,研究了珊瑚礁岩土地区钢管桩沉桩规律。采用统计分析方法对钢管桩在珊瑚礁岩土中的终锤贯入度、沉桩锤击总数以及入土深度进行对比。结合现场试验测试和可打性分析,指出打入式钢管桩易穿透珊瑚礁岩土、所需锤击总数偏少的主要原因是受珊瑚礁岩土软硬分布和土颗粒破碎影响。研究结果表明:钢管桩可以穿透高标贯击数(100击以上)的珊瑚礁岩土;常规的工程设计施工经验直接应用于珊瑚礁岩土容易造成较大的偏差,应通过现场载荷试验校核。 相似文献
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分析了承载13吨的转向驱动桥轮边结构,校核了轮毂轴承、半轴等关键零部件的强度,计算了转向驱动桥桥壳的应力,完备了大吨位汽车起重机转向驱动桥的设计资料,为其它类型的工程机械转向驱动桥设计提供了可借鉴的模式。 相似文献
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Railway systems must increase their performance and economic competitiveness to remain an effective and efficient transport mode. Energy efficiency goals are one of the main drivers for the future evolution of planning and operations of transport systems. An opportunity to improve energy efficiency together with reliability and feasibility of railway systems come from the huge amount of data being currently collected and available in the future. The hidden potential in large sets of data for improving energy efficiency can be fully exploited through novel, data-driven approaches. This paper discusses the relation of those future approaches with the current state of the art and challenges, highlighting natural advantages and possible weak points. We identify dimensions within the current literature describing the suitability of current approaches to embrace the data revolution, and the possible enhancements resulting from that. We refer to practical test cases based on real on-board monitoring of electric trains in Switzerland to identify current and future challenges in improving energy efficiency of train operations. We conclude with a discussion and a roadmap on the introduction of data-driven approaches for improving energy efficiency of railway systems. 相似文献
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自组网路由协议可依驱动方式分为表驱动和按需驱动,这两种驱动方式的路由协议各有其优缺点.对这两类路由协议的路由发现延迟、路由开销、网络吞吐量等性能进行了对比分析,并结合短波自组网在网络中心战体系中所处的层次和主要应用对性能的需求,分析了适应于短波自组网的路由驱动方式. 相似文献