智能润滑技术在船舶智能化发展中的应用

船舶智能化已成为船舶行业未来发展的必然趋势。针对传统船舶润滑系统的使用和维护现状,提出智能润滑技术,并以智能润滑技术为基础设计出智能润滑装置。通过\"在线监测、智能净化、故障预警\"的智能润滑技术替代\"离线检测、定期换油、事后维修\"的传统润滑模式,实现船舶润滑系统的智能管理,全天候保证润滑系统的高质量油品品质,降低设备故障率,从而保障船机安全性,提高船舶润滑系统的可靠性和智能化程度。     

地铁车辆直线电机气隙在线检测系统结构

气隙在线检测系统是集数据采集、分析、处理与实时通信于一体的计算机测量系统。作为直线电机地铁车辆的维护设备之一,当车辆通过系统时,其可以实现自动辨别车号、计算车速、记录轴数、测量气隙高度等功能,并通过计算机内部设备的判别模型,对超限数据进行报警。     

铁路基层站段网络培训系统的构建

以洛阳火车站职工培训为背景,介绍了网络培训系统的总体结构和功能特点。该系统综合应用了网络通信技术、分布式技术、旁路采集技术和数据同步传送技术等,实现了企业职工网络培训,具有直播课堂、点播课件、网络考试、非正常行车计算机仿真模拟和教学管理等功能,大大提高了职工培训效率。     

1300MPa级在线热处理钢轨使用性能研究

对铺设在北京、太原、上海和郑州铁路局的半径为300~500 m曲线上的60 kg.m-1PG4在线热处理钢轨的使用性能进行跟踪观测,研究提高重载小半径曲线钢轨的使用寿命。研究结果表明,60 kg.m-1PG4在线热处理钢轨硬度高、耐磨性能好;在使用初期,钢轨磨耗少,钢轨表面容易出现剥离掉块,此时如果采用液体润滑,会加剧钢轨表面的剥离掉块;钢轨的磨耗主要出现在曲线的圆缓或缓圆部位,当钢轨磨耗到一定程度后,侧磨加快,如果采用正确的固体润滑方法,可使钢轨的侧磨得到有效地控制,且钢轨不会出现严重的剥离掉块;PG4在线热处理钢轨的综合使用性能良好,耐磨性能比U75V热处理钢轨提高1倍以上,适合在钢轨磨耗严重的重载铁路小半径曲线上使用;对钢轨实施预防性打磨、设置适当的欠超高、采用1∶20的轨底坡等改善轮轨匹配关系降低接触应力的措施,均对提高重载铁路曲线区段上钢轨的使用寿命具有重要的作用。     

The impact of advance purchase deadlines on airline consumers’ search and purchase behaviors

Airlines frequently use advance purchase ticket deadlines to segment consumers. Few empirical studies have investigated how individuals respond to advance purchase deadlines and price uncertainties induced by these deadlines. We model the number of searches (and purchases) for specific search and departure dates using an instrumental variable approach that corrects for price endogeneity. Results show that search and purchase behaviors vary by search day of week, days from departure, lowest offered fares, variation in lowest offered fares across competitors, and market distance. After controlling for the presence of web bots, we find that the number of consumer searches increases just prior to an advance purchase deadline. This increase can be explained by consumers switching their desired departure dates by one or two days to avoid higher fares that occur immediately after an advance purchase deadline has passed. This reallocation of demand has significant practical implications for the airline industry because the majority of revenue management and scheduling decision support systems currently do not incorporate these behaviors.     

Analyzing high speed rail passengers’ train choices based on new online booking data in China

This study explores two nonparametric machine learning methods, namely support vector regression (SVR) and artificial neural networks (ANN), for understanding and predicting high-speed rail (HSR) travelers’ choices of ticket purchase timings, train types, and travel classes, using ticket sales data. In the train choice literature, discrete choice analysis is the predominant approach and many variants of logit models have been developed. Alternatively, emerging travel choice studies adopt non-utility-based methods, especially nonparametric machine learning methods including SVR and ANN, because (1) those methods do not rely on assumptions on the relations between choices and explanatory variables or any prior knowledge of the underlying relations; (2) they have superb capabilities of iteratively identifying patterns and extracting rules from data. This paper thus contributes to the HSR train choice literature by applying and comparing SVR and ANN with a real-world case study of the Shanghai-Beijing HSR market in China. A new normalized metric capturing both the load factor and the booking lead time is proposed as the target variable and several train service attributes, such as day of week, departure time, travel time, fare, are identified as input variables. Computational results demonstrate that both SVR and ANN can predict the train choice behavior with high accuracy, outperforming the linear regression approach. Potential applications of this study, such as rail pricing reform, have also been identified.     

基于 PEST 分析的纯电动汽车作为网约车竞争环境研究 ——以三四五线城市为例

网约车合法化后,具有运营成本低、环境友好等优点的纯电动车进入网约车市场。但 在三四五线城市,纯电动网约车的渗透率比较低。为了推动纯电动汽车进一步进入网约车市 场,基于网约车市场和纯电动车特点,借助政治、经济、社会、技术（Politics Economy Society Technology, PEST）分析法从政策、经济、社会和技术四个宏观环境对纯电动车作为网约车在三四五线城市竞争环境进行分析,研究制约纯电动网约车在三四五线城市发展的宏观因素,并针对性提出纯电动网约车的发展建议及措施,即地方政府通过制定宽松政策和合理规划充电设施鼓励纯电动汽车的使用;网约车平台采取降低挂靠费用、差异化服务价格等措施,引 导驾驶员和客户使用纯电动网约车,从而提高纯电动汽车在三四五线城市网约车中的渗透率。     

AMT 手动挡锁挡控制策略研究

为实现纯电动商用车机械式自动变速箱（AMT）适应复杂行驶工况,可通过整车控制器（VCU）控制变速箱进行手动挡锁挡控制。通过使用比例积分（PI）调节的控制方式对电机扭矩进行限制,从而将驱动电机的转速控制在限值之内。然后基于控制器局域网（CAN）标定协议（CCP）进行在线标定,截取相应的报文数据进行分析,验证其功能。试验结果显示,文章的控制方法能够实现车辆的手动挡锁挡功能,电机转速波动范围在±20 r/min 之内,且车身无抖动现象,具有较好的驾驶平顺性。