Orientation density and workspace analysis of a parallel stabilized platform testing system

An optimized workspace calculation method is proposed for parallel stabilized platform testing systems.This method refines the searched space progressively in order to approach the boundary of the workspace from both the inside and the outside of it.The orientation density is defined and used as an evaluation index to calculate the orientation workspace.The algorithm of the orientation density is embedded into the computer program of the workspace calculation.Then the workspaces of the testing system are solved.In the solution,the orientation density is regarded as a discrete function of the reachable workspace.As a result,the reachable workspace and the orientation workspace are represented in the same multidimensional graphs.Finally the useful workspace of the testing system is determined based on these results.This case study indicates that the calculation efficiency is enhanced by adopting the optimized method and the practicability of workspace study is improved by proposing the orientation density.

Time-and Frequency-Domain Analysis of Ice-Induced Displacement Responses Offshore Fixed Platforms

On the basis of ice- induced forced vibration model, ice- induced displacement responses of offshore fixed platforms are investigated in both time domain and frequency domain. The relationships of ice-induced displacement responses with ice breaking modes, ice acting directions and platform structures are analyzed and determined. The results lead to an important conclusion obtained for the first time that ice breaking frequency and the natural frequency of the first mode of the platform are the two main factors that dominate the degree of vibration. The present work provides a firm basis for both design and operation of fixed platforms against ice loading.

Integration of high-performance spin-orbit torque MRAM devices by 200-mm-wafer manufacturing platform

We demonstrate in-plane field-free-switching spin-orbit torque(SOT)magnetic tunnel junction(MTJ)devices that are capable of low switching current density,fast speed,high reliability,and,most importantly,manufactured uniformly by the 200-mm-wafer platform.The performance of the devices is systematically studied,including their magnetic properties,switch-ing behaviors,endurance and data retention.The successful integration of SOT devices within the 200-mm-wafer manufactur-ing platform provides a feasible way to industrialize SOT MRAMs.It is expected to obtain excellent performance of the devices by further optimizing the MTJ film stacks and the corresponding fabrication processes in the future.

Discussion on Cathodic Protection of HZ 21-1 Platform

The environmental conditions around the first offshore HZ 21- 1 steel wellhead platform in the South China Sea are characterized by deep water, frequent typhoons, rough waves, high water temperature, severely corrosive seawater, and thick fouling organism attachments. The design and effectiveness of galvanic anode protection system are presented, and several methods are described, which are the calculation method of the protective current density considering the variation of water depth, the method of determining protection parameters considering various factors, the arrangement of anodes based on potential distribution and current requirements at different water depths, and the method of anode installation. Finally the effect of the accuracy of selected cathodic protection parameters on the economic benefits of offshore projects is also discussed..

ComplexTrans-Global Rail-Road Transportation System Economical and Clustered Individual and Individualised Public Transport also Prevents the Spread of Covid 19

Land transport can no longer meet the requirements.European transport can be described by these words−crowded motorways and cities,dangerous emissions,ubiquitous traffic accidents,delays,expensive railways.Solutions are being sought to transfer a large part of passengers and especially freight transport to(high-speed)rail,and efforts are moving towards electromobility,car-sharing,5G-connectivity,autonomous driving,MaaS(Mobility as a Service)-coordinated transport or hyperloop-type solutions.However,all these solutions have additional challenges and limitations.Solutions are not being searched where they really exist-in the mutual adaptation of road and rail vehicles and their deep cooperation.The ComplexTrans project shows that simply adapting the dimensions and functions of road and rail vehicles can eliminate(or at least significantly reduce)all the problems of existing land transport.The main features of the ComplexTrans system are sufficient parking spaces,reduction of urban and non-urban congestion,electric vehicles with unlimited range and cheaper than standard cars,cheaper and more accessible battery charging,“autonomous ride”,solving the overlap between passenger and freight rail transport and making it self-financing,transferring intercity freight transport to rail,replacing part of continental air transport and many others.The cost-effective and clustered individual transport and individualised public transport of the ComplexTrans system also bring very significant reductions in the risk of transmission of covid-19 and other contagious diseases during transport.

Optimal Design of TMD Under Long-Term Nonstationary Wave Loading

Traditionally, the use of a tuned mass damper (TMD) is to improve the surviability of the primary structure under extraordinary loading environment while the design loading condition is described by either a harmonic function or a stationary random process that can be fully characterized by a power spectral density (PSD) function. Aiming at prolonging the fatigue life of an offshore platform, this study considers an optimal design of TMD for the platform under long-term nonstationary loading due to long-term random sea waves characterized by a probabilistic power spectral density (PPSD) function In principle, a PPSD could be derived based on numerous ordinary PSD functions; and each of them is treated as realization of the corresponding PPSD. This study provides a theoretical development for the optimal TMD design by minimizing the cost function to be the mean square value of the expected long term response. A numerical example is presented to illustrate the developed design procedure.

Probabilistic model for remain passenger queues at subway station platform

The remain passenger problem at subway station platform was defined initially,and the period variation of remain passenger queues at platform was investigated through arriving and boarding analyses.Taking remain passenger queues at platform as dynamic stochastic process,a new probabilistic queuing method was developed based on probabilistic theory and discrete time Markov chain theory.This model can calculate remain passenger queues while considering different directions.Considering the stable or variable train arriving period and different platform crossing types,a series of model deformation research was carried out.The probabilistic approach allows to capture the cyclic behavior of queues,measures the uncertainty of a queue state prediction by computing the evolution of its probability in time,and gives any temporal distribution of the arrivals.Compared with the actual data,the deviation of experimental results is less than 20%,which shows the efficiency of probabilistic approach clearly.

高速铁路列车乘客上下车策略分析及仿真模拟

为获得高速铁路列车乘客最优的上下车策略,选取CRH380AL型高速列车二等座车厢,构建乘客上下车策略仿真模型。针对不同的上下车策略,分析人员携带行李比例、上车人数的落座时间和过道密度,量化乘客上下车的效率和舒适度。结果表明:低密度时,乘客落座时间在双车门行策略和双车门倒金字塔策略下变化差异不明显。随着乘客人数和携带行李比例的增加,双车门倒金字塔策略的乘客落座时间最短。30人上车场景时,双车门倒金字塔策略车厢过道区域的最大密度和平均密度均为最低。在上下车人数为50人、携带行李比例为40%时,双车门倒金字塔策略的过道密度相较于双车门行策略和双车门斯蒂芬法策略较低,此时乘客舒适度较好。

基于核密度估计模型优化手术调度的设计与应用

目的针对现有手术患者转运平台转运流程中,手术状态节点变动存在人工操作依赖性和滞后性、手术衔接不高效的问题,改进手术患者转运平台的手术流转流程。方法结合集成蓝牙低能耗技术的智能手环、人员定位系统,运用核密度估计模型估算手术平均时长,从而改进手术患者转运平台的手术流转流程,并对模型的有效性进行验证。结果应用改进的手术转运平台后,首台延迟率、手术衔接时间较改进前下降6.2%、8.0 min,日均麻醉利用率和日间手术利用率较应用前提高了6.9%、6.4%,且差异均有统计学意义(P<0.01)。结论通过应用改进后的手术患者转运平台,手术室手术衔接效率更高,手术调度更加智能化,可有效提高手术室效率。

结合载客热点和POI的出租车停车位划定方法

针对出租车随意停靠造成城市交通拥堵甚至交通事故的问题,利用成都实际区域的出租车GPS(Global Position System)数据和爬取的POI(Point of Interest)数据,使用DBSCAN(Density-Based Spatial Clustering of Application with Noise)聚类算法对上下客点进行聚类,得到出租车的载客热点,根据POI的类型划定载客热点区域的类型,对出租车不同时间的出行需求进行分析,进而划分出出租车的固定停车区域。研究结果表明,出租车固定停车区域的设定与出行者的出行需求有关,即将固定停车区域设置在出行者出行需求多的区域,可以满足出行者的不同出行需求。结合出租车载客热点和爬取POI数据划定固定停车区域的方法具有较高的实用性,可为城市交通安全方面提供理论和现实意义。

面向地铁客流分析场景的弹性集群云平台架构设计及部署方案

[目的]在数字化技术迅速发展的当下,云技术被广泛应用在包括地铁系统在内的各行各业。出于对乘客出行安全的保障,实现大规模客流数据的实时获取和高效分析,需要提出面向客流分析场景的弹性集群云平台方案。[方法]分析了弹性集群云平台的核心功能需求,提出了弹性集群云平台的架构,阐述了弹性集群云平台的独特能力。针对不同发展阶段的地铁系统提出了2个弹性集群云平台部署方案,分析了各部署方案的优劣。以上海地铁为例,基于能力需求对比了部署方案的投资成本。分析了弹性集群云平台架构与地铁客流分析业务特征的匹配性。[结果及结论]地铁客流分析场景具有多系统并发、实时性高、数据量大等特点。弹性集群云平台能满足客流分析业务的多种需求。

北京某地铁交通枢纽换乘大厅客流密度计算模型

针对北京某地铁交通枢纽换乘大厅3个典型季节客流量进行了实测分析。结果表明:客流量不受室外气象条件、季节性影响,与工作时间及周围办公、居住人口规模密切相关;换乘大厅任一时刻在室人数等于该时刻进入的客流量级数与离开的客流量级数之差。根据客流密度特征,按工作日和周末分别建立了换乘大厅客流密度一元线性回归模型,并分段给出了客流密度拟合公式,利用实测数据验证了该模型的正确性。

基于非线性卡尔曼滤波的城市轨道交通客流密度短时预测方法

[目的]为应对大客流事件,需准确识别城市轨道交通对大客流时空分布状态及演化规律,有必要基于EKF(扩展卡尔曼滤波)和UKF(无迹卡尔曼滤波),对城市轨道交通客流密度进行短时预测。[方法]从车站和断面两个层面,介绍了自动售检票设备数据的处理方法,并划分了城市轨道交通车站及断面的舒适度等级。通过定义客流密度状态方程和量测方程,分别介绍了EKF模型和UKF模型的城市轨道交通客流密度短时预测计算方法。以国内某城市轨道交通网络化运营城市某条线路为案例,比较了EKF模型及UKF模型的预测精度。[结果及结论]算例结果表明,EKF模型及UKF模型均能通过实时采集当前时段车站自动售检票设备数据来预测下一时段的车站客流密度和断面客流密度,适用于城市轨道交通客流密度短时预测场景。相比于EKF模型,UKF模型全天分时段预测值更接近真实变化趋势,UKF模型预测值与真实值的散点分布更趋集中收敛;UKF模型的均方根误差、平均绝对误差及平均绝对百分比误差均相对更低,说明UKF模型预测精度相对更高。

基于乘客行为探讨大客流地铁车站站台宽度计算方法

[目的]根据GB 50157—2013《地铁设计规范》计算出的大客流地铁车站站台宽度偏小,难以消化巨量的客流压力,基于乘客在站台的行为特征提出一种新的站台宽度计算方法。[方法]介绍了现行站台宽度计算方法,并对其与大客流车站站台实际客流进行偏差分析;设置列车未到站和列车进站后两种工况,提出大客流车站站台宽度计算方法;以西安某大客流地铁车站为例,对所提站台宽度计算方法进行实例测算。[结果及结论]鉴于部分车站高峰时段与城市高峰时段不一致,站台宽度计算公式引入车站偏差系数,以车站高峰小时作为确定站台宽度的计算时段。若车站为换乘站,两股分支客流之间存在对向干扰,引入对向干扰系数。站台客流在列车到站后经历了4个阶段,第2阶段对站台占用需求最大,并呈“块”状静止和“线”形移动两种客流特征。与现行规范的站台宽度计算方法相比,所提站台宽度计算方法对大客流车站具有更好的适应性。

基于智能视频分析的铁路客运站运营态势感知技术及应用

人工监控铁路客运站极易出现视觉疲劳,降低时效性和准确性,为此提出一种基于智能视频分析的铁路客运站运营态势感知技术。该技术深度结合生产作业计划,基于AI人工智能算法,分别针对站台和候车厅提出站台异常行为检测模型和站厅客流运动态势分析模型。采用基于自适应特征金字塔的二级级联网络,提取站台上的游荡人员/行李并判断目标所处的位置及轨迹,实现站台越线、端部入侵、警戒区域徘徊、标准化作业、工作人员到岗等功能;采用基于跨域残差空间全卷积网络对远景的候车厅/通廊等场景自动生成人群热力密度图和移动态势图,对近景的进站口/检票口等场景自动评估排队及候检情况。根据站内的客流密度和异常态势,智能调配客运人员的作业计划,提高旅客出行体验和候车安全性。

大客流场景下列车时刻表与列车容量分配协同优化研究

为缓解城市轨道交通通勤线路中大客流车站及其下游车站的站台拥挤,降低候车乘客的聚集程度和安全风险,本文从时间和空间角度系统优化城市轨道交通列车容量资源配置。通过考虑时变客流需求和预留车厢策略,提出城轨列车时刻表与列车容量分配协同优化方法。具体地,通过引入列车发车时间、预留车厢数量和客流分配方案相关决策变量,以最小化预留车厢运营成本和站台乘客最大聚集数量为目标,建立列车时刻表与列车容量分配协同优化线性整数规划模型。其中,采用大M方法构建的客流分配约束能够满足乘客在时间和空间上的先到先服务原则。为验证所构建模型的有效性,设置4组数值算例进行对比实验,并采用优化求解器Gurobi求解。结果表明,相较于计划列车时刻表方案和两种单一优化策略方案,协同优化方案能够显著降低最大乘客聚集数量分别约为60%、52%和31%,降低乘客总等待时间分别约为29%、17%和29%。即协同优化方法能够均衡城轨列车容量的时空分布,从而有效降低站台候车乘客的聚集风险。

基于AnyLogic的地铁站台客流引导方式优化

为避免地铁车厢客流过度集中,引导站台乘客分散乘车,文章以地铁各车厢客流均衡为目标,以均衡度标准差为指标,综合考虑车厢现有人数、候车人数及预计下车人数,优化地铁站台客流引导方式。通过AnyLogic仿真软件,模拟广州地铁珠江新城5号线站台条件,对比了客流量范围在12万人/日~60万人/日条件下,不同引导方式对车厢乘客分布不均衡度的影响。结果表明,地铁站客流量达到24万人/日时,考虑预计下车人数的站台客流引导方式下的车厢客流均衡度标准差明显提升;与不考虑该站下车人数的引导方式相比,客流均衡度标准差提升幅度最大达到25.6%,相比人工引导方式的提升幅度达53.6%,有效提升了地铁精细化服务能力。

多相计量撬现场参数整定及单井计量测试

单井多相计量一直是油田迫切需要突破的问题,科氏力流量计以其较高的质量流量精度,实时提供含水率而广受欢迎。但受限于现场条件,作为含水率及体积流量换算的密度参数并不准确或无法提供。基于此阐述一种在油田现场对单井采出液就地进行油水分离及密度检测的方法。以现场实验获取的单井采出液原油,地层水水密度值作为基于科氏力多相计量撬的参数,进行所采样单井的计量测试实验,与平台现有高精度流量计及取样化验含水率数据比对,相对误差在±5%以内。

苏州北站扩建后客运量预测与总体定位研究

长三角一体化发展是国家重大战略,苏州北站作为长三角地区的重要交通枢纽,承担着联系虹桥商务区、协同苏浙的重要作用,因此,必须推进苏州北站扩容建设。对苏州北站的客运量、交通设施规模、站房规模等进行计算和规划,并将苏州北站与国内外典型枢纽进行对比。结果表明,2050年后苏州北站铁路到发量为26.9万人次/日,占比达到47.81%,枢纽对外客流日集散量约56.27万人次/日,远期高峰小时发送量达1万人,属于特大型车站。扩建后,苏州北站铁路相关用房面积为10万m^(2),K建筑面积为20万m^(2),规模与国内外大型交通枢纽站台规模接近,年发送量较高。

城市轨道交通网络系统效率评价指标改进

为提高城市轨道交通网络系统效率评价指标的可比性和完备性,引入有效行程速度和有效客流密度的概念,改进了网络系统效率评价指标,并以重庆市中心城区2017年和2019年运营的城市轨道交通线网为例验证了改进后评价指标的科学性和可操作性。研究表明:既有评价指标由于显著受到线网服务范围的影响,且未体现网络的投入产出效率,无法直接作为网络结构优化的目标函数;改进后的系统效率评价指标能够综合反映剔除线网服务范围影响后的网络结构性能和投入产出效率,且存在理论上的最优值;平衡网络中节点换乘时间和路段行程时间,并适度加密城市核心区域的轨道交通线路和站点,是持续提升网络系统效率的2个重要手段。