船舶轨迹异常检测方法研究进展

近年来,异常检测技术在分析和利用船舶轨迹数据中扮演着越来越重要的角色,已经成为航海领域的一个热点研究方向。船舶轨迹的异常检测旨在利用相关的异常检测算法,研究船舶个体或群体的行为特征,发现隐藏在其中的船舶异常行为模式或船位。主要从船舶位置和行为方面分析了船舶异常行为的概念和分类,综述了船舶轨迹异常检测的方法,评述了各方法在船舶轨迹异常检测中应用的优点和不足,讨论了船舶轨迹异常检测存在的问题和面临的挑战。     

Essential tools for food safety surveillance in catering services: On-site inspections and control of high risk cross-contamination surfaces

The aim of this study was to assess the routine food safety procedures carried out in catering services so as to provide a useful monitoring program for managers based on the relevant deviations detected in the observational survey and activities carried out in 15 catering services located in Navarra (region of northern Spain). The main hygiene standards, food handler practices and compliance with the HACCP system were evaluated by means of visual inspections (checklist), monitoring of critical control points (food storage and food processing temperatures, total polar compounds) and microbiological analysis of food-contact and hand-contact surfaces. While general high scores were obtained in the observational survey (73.3% above 36 points), none of the evaluated services had obtained the maximum rate of 48 points. The mayor deficiencies were related to the presence of dirty uniforms, improper hand washing or use of gloves, incorrect disinfection of vegetables and the missing records of stated critical points (temperatures and polar compounds in oil). The performed monitoring activities confirmed the safety of frying oil in all the kitchens, despite the fact that only 33% of them applied scientific methods to measure polar compounds. By contrast, holding temperatures were unsatisfactory in 77% of cold dishes and in 19% of hot meals. Despite the fact that 77% of food contact surfaces were considered acceptable (<4 CFU/cm²), high levels of total mesophilic microorganisms and Enterobacteriaceae were detected in hand-contact surfaces such as aprons and handles. The periodic visual supervision focusing on hygienic practices and the microbiological surveillance of surfaces of high risk for cross-contamination should provide valuable information for improving the knowledge, attitudes and practices of food handlers regarding food safety.     

Integrated planning and scheduling under production uncertainties: Bi-level model formulation and hybrid solution method

We propose a novel method for integrating planning and scheduling problems under production uncertainties. The integrated problem is formulated into a bi-level program. The planning problem is solved in the upper level, while the scheduling problems in the planning periods are solved under uncertainties in the lower level. The planning and scheduling problems are linked via service level constraints. To solve the integrated problem, a hybrid method is developed, which iterates between a mixed-integer linear programming solver for the planning problem and an agent-based reactive scheduling method. If the service level constraints are not met, a cutting plane constraint is generated by the agent-based scheduling method and appended to the planning problem which is solved to determine new production quantities. The hybrid method returns an optimality gap for validating the solution quality. The proposed method is demonstrated by two complicated problems which are solved efficiently with small gaps less than 1%.     

Variable and adaptive neighbourhood search algorithms for rail rapid transit timetabling problem

Supplying affordable and efficient transportation services to the users is one of the main tasks of the public transport systems. In this study, the objective is the minimization of the total and maximum waiting time of the passengers through optimization of the train timetables for urban rail transit systems. For this purpose, mixed-integer linear and non-linear programming models are developed which could solve the small to medium-sized test instances optimally. In order to tackle large instances, adaptive and variable neighbourhood search algorithms are designed based on different novel solution encoding schemes and decoding approaches. The effectiveness of the proposed models and solution methods are illustrated through the application to the Tehran intercity underground rail lines in IRAN. The outcomes demonstrate that the variable neighbourhood search algorithm outperforms the adaptive step-size neighbourhood search method in the different scenarios of the real case. Furthermore, the generated headway for the period of study result in a significant reduction in total waiting time of the passengers compared with the current baseline timetables.     

基于McWiLL的大范围多类型数据传输系统设计

为解决大面积范围内数量众多的灌溉机井水泵传感器网络中多种类型数据实时传输的难题,建立了基于McWiLL宽带无线接入技术的新型传感器网络。对该传感器网络各部分功能设计和网络规划进行了研究,并建立了小规模的实验网络;对该试验网络的覆盖范围、数据传输延时进行了测试,并与基于GPRS（Gerner-alPacketRadioService）的传感器网络进行了对比分析。结果表明,该传感器网络能采集并传输多种媒体数据、平均数据传输延时较GPRS网络缩短20％,最大数据传输延时缩短为GPRS网络的1／3,单基站网络覆盖范围约16km,很好地满足了设计需求。     

轨道交通系统接运公交线路生成的启发式算法

为探讨轨道交通接运公交线路的最优布设方案,兼顾乘客和公交运营企业的利益,提出了一种启发式算法。算法以乘客延误最小化和公交线路行驶时间最短为基础,给出了接运公交线路的具体生成示例。以北京地铁5号线宋家庄站和刘家窑站的接运公交线路布设方案为例进行分析,将生成方案与遗传算法进行了对比。结果表明：提出的启发式算法比遗传算法更加...     

基于BP神经网络与马尔可夫链的城市轨道交通周边房地产价格的组合预测方法

为解决先验数据有限且存在大量不确定因素情况下,城市轨道交通周边房地产价格的预测问题,提出一种基于BP神经网络与马尔可夫链的组合预测模型。首先,采用BP神经网络,使用较少量的样本数据完成城市轨道交通周边房地产价格曲线的粗略拟合;在此基础上,借助马尔可夫链进行系统状态划分,缩小预测区间以提高预测精确度;最后,运用基于BP神经网络与马尔可夫链的组合模型,对北京市轨道交通13号线周边房地产价格进行了预测分析。计算结果表明,该模型具有较高的精度和可靠性。     

信号交叉口处自行车交通流的跟驰行为

首先对自行车的跟驰行为进行描述,并通过视频实验对信号交叉口自行车流的相关参数进行采集和分析。在此基础上,综合考虑自行车流运行过程中相对距离、相对速度、前车加速度、横向干扰和骑车人属性等因素对后车加速度的影响,先后构建了具有三种不同BP网络结构的跟驰模型。通过对不同BP网络训练误差的比较分析,提出了一种可以较好地反映信号交叉口处自行车群内前后车之间刺激-反应关系的跟驰模型。这对于分析混合交通流的微观运行特性,开展与混合交通相关的微观模拟等研究具有一定借鉴意义。     

Standard Analysis for Transfer Delay in CTCS-3

According to the standard for the GSM for railway (GSM-R) wireless systems in China train control system level 3 (CTCS-3),the control data transfer delay should be no larger than 500ms with greater than 99％ probability.Coverage of both non-redundant networks and intercross redundant networks and cases of single Mobile terminals (MTs) and redundant MTs on one train are considered,and the corresponding vehicle-ground communication models,delay models,and fault models are constructed.The simulation results confirm that the transfer delay can meet the standard requirements under all cases.In particular,the probability is greater than 99.996％ for redundant MTs and networks,and the standard of transfer delay in CTCS-3 will be improved inevitably.