Combining Geographic Information Systems for Transportation and Mixed Integer Linear Programming in Facility Location-Allocation Problems

In this study, we aimed to assess the solution quality for location-allocation problems from facilities generated by the software TransCAD®?, a Geographic Information System for Transportation (GIS-T). Such facilities were obtained after using two routines together: Facility Location and Transportation Problem, when compared with optimal solutions from exact mathematical models, based on Mixed Integer Linear Programming (MILP), developed externally for the GIS. The models were applied to three simulations: the first one proposes opening factories and customer allocation in the state of Sao Paulo, Brazil;the second involves a wholesaler and a study of location and allocation of distribution centres for retail customers;and the third one involves the location of day-care centers and allocation of demand (0 - 3 years old children). The results showed that when considering facility capacity, the MILP optimising model presents results up to 37% better than the GIS and proposes different locations to open new facilities.

Tracing surface seawater mixing and nutrient transport by^(222)Rn on the northern coast of Beibu Gulf,China

The transport and diffusion of substances in seawater are limited by the mixing motion of water bodies,while the main forms of mixing in offshore water bodies are advection and eddy diffusion.The eddy diffusion process of water indicates the possible transport direction of dissolved substances.However,the complex environment in the coastal zone makes it difficult to quantitatively assess the water diffusion process.^(222)Rn is a useful tool to trace the diffusion process of water bodies.However,studies on the^(222)Rn distribution and its behavior in the Beibu Gulf are scarce.In this study,the activity distribution characteristics of^(222)Rn in surface seawater of the Guangxi shelf area of the Beibu Gulf were measured.Based on the one-dimensional,steady-state model,the vorticity diffusion coefficient of^(222)Rn in the horizontal direction was calculated as(0.42−2.13)×10^(8) m^(2)/d,and the offshore fluxes of^(222)Rn under the influence of water mixing were calculated as 2.00×10^(12) Bq/d.Correspondingly,the horizontal transport fluxes of silicate,phosphate,nitrite and nitrate were 6.28×10^(−3)mol/(m^(2)·d),0.10×10^(−3)mol/(m^(2)·d),0.20×10^(−3)mol/(m^(2)·d)and 4.15×10^(−3)mol/(m^(2)·d),respectively.These results indicate that the study of eddy current diffusion in offshore marine water facilitates a deeper understanding of the water mixing process and nutrient transport and migration.

A mixed stochastic user equilibrium model considering influence of advanced traveller information systems in degradable transport network

Advanced traveler information systems （ATIS） can not only improve drivers＇ accessibility to the more accurate route travel time information, but also can improve drivers＇ adaptability to the stochastic network capacity degradations. In this paper, a mixed stochastic user equilibrium model was proposed to describe the interactive route choice behaviors between ATIS equipped and unequipped drivers on a degradable transport network. In the proposed model the information accessibility of equipped drivers was reflected by lower degree of uncertainty in their stochastic equilibrium flow distributions, and their behavioral adaptability was captured by multiple equilibrium behaviors over the stochastic network state set. The mixed equilibrium model was formulated as a fixed point problem defined in the mixed route flows, and its solution was achieved by executing an iterative algorithm. Numerical experiments were provided to verify the properties of the mixed network equilibrium model and the efficiency of the iterative algorithm.

Electrifying Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) for focalized heating in oxygen transport membranes

Industry decarbonization requires the development of highly efficient and flexible technologies relying on renewable energy resources,especially biomass and solar/wind electricity.In the case of pure oxygen production,oxygen transport membranes(OTMs)appear as an alternative technology for the cryogenic distillation of air,the industrially-established process of producing oxygen.Moreover,OTMs could provide oxygen from different sources(air,water,CO_(2),etc.),and they are more flexible in adapting to current processes,producing oxygen at 700^(-1)000℃.Furthermore,OTMs can be integrated into catalytic membrane reactors,providing new pathways for different processes.The first part of this study was focused on electrification on a traditional OTM material(Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)),imposing different electric currents/voltages along a capillary membrane.Thanks to the emerging Joule effect,the membrane-surface temperature and the associated O_(2) permeation flux could be adjusted.Here,the OTM is electrically and locally heated and reaches 900℃on the surface,whereas the surrounding of the membrane was maintained at 650℃.The O_(2)permeation flux reached for the electrified membranes was~3.7 NmL min^(-1)cm^(-2),corresponding to the flux obtained with an OTM non-electrified at 900℃.The influence of depositing a porous Ce_(0.8)Tb_(0.2)O_(2-δ) catalytic/protective layer on the outer membrane surface revealed that lower surface temperatures(830℃)were detected at the same imposed electric power.Finally,the electrification concept was demonstrated in a catalytic membrane reactor(CMR)where the oxidative dehydrogenation of ethane(ODHE)was carried out.ODHE reaction is very sensitive to temperature,and here,we demonstrate an improvement of the ethylene yield by reaching moderate temperatures in the reaction chamber while the O_(2) injection into the reaction can be easily fine-tuned.

Discharge mode and particle transport in radio frequency capacitively coupled Ar/O_(2) plasma discharges

Simulations are conducted on capacitively coupled Ar/O_(2)mixed gas discharges employing a one-dimensional fluid coupled with an electron Monte Carlo(MC)model.The research explores the impact of different O_(2)ratio and pressures on the discharge characteristics of Ar/O_(2)plasma.At a fixed Ar/O_(2)gas ratio,with the increasing pressure,higher ion densities,as well as a slight increase in electron density in the bulk region can be observed.The discharge remains dominated by the drift-ambipolar(DA)mode,and the flux of O(3P)at the electrode increases with the increasing pressure due to higher background gas density,while the fluxes of O(1D)and Ardecrease due to the pronounced loss rate.With the increasing proportion of O_(2),a change in the dominant discharge mode from a mode to DA mode can be detected,and the O_(2)-associated charged particle densities are significantly increased.However,Ar+density shows a trend of increasing and then decreasing,while for neutral fluxes at the electrode,Arflux decreases,and O(3P)flux increases with the reduced Ar gas proportion,while trends in O(1D)flux show slight differences.The evolution of the densities of the charged particle and the neutral fluxes under different discharge parameters are discussed in detail using the ionization characteristics as well as the transport properties.Hopefully,more comprehensive understanding of Ar/O_(2)discharge characteristics in this work will provide a valuable reference for the industry.

Process-Functional Model of Transportation Mix Concrete

The paper proposes a process-functional model of transportation mix concrete, which is a structured description of a means of transportation technology mix concrete road at the level of the production process. Range of activities related to the transportation of concrete mixtures is presented in the form of hierarchically nested processes that are coordinated on the basis of general systems theory. The model is described in a strict sequence: process chain→process step→process link, and all built technological chains consist of indivisible units.

Path Selection of Multimodal Transport Based on Multi-Objective Mixed Integer Programming

Based on “One Belt and One Road”, this paper studies the path selection of multimodal transport by using the method of multi-objective mixed integer programming. Therefore, this paper studies the factors of transportation time, transportation cost and transportation safety performance, and establishes a mathematical model. In addition, the method of multi-objective mixed integer programming is used to comprehensively consider the different emphasis and differences of customers on cargo transportation. Then we use planning tools of Microsoft Excel to solve path selection and to determine whether the chosen path is economical and reliable. Finally, a relatively complex road network is built as an example to verify the accuracy of this planning method.

Studies on Transport Properties of Fe³⁺: Li₂O-K₂O-CdO-B₂O₃Glass System: An Evidence of Mixed Alkali Effect

The glasses of the type (30 一 x)Li2O 一 xK2O 一 10CdO 一 59B2O3 doped with 1 mol% of Fe2O3 were prepared by melt quench technique and their non-crystallinility has been established by XRD studies. The glasses were investigated for room temperature density and electrical conductivity in the temperature range 300 - 523 K and in the frequency range 102 to 105 Hz. The frequency and temperature dependence of conductivity as dielectric constant are presented.

基于Mixed Logit模型的私家车通勤出行时间价值

假定时间参数为常数,费用参数服从对数正态分布,建立了出行路径选择的MixedLogit模型。利用大连市私家车出行者出行意向调查数据对该模型进行了150次仿真实验。结果表明:各个参数的t检验值均比较显著,模型的优度比也较高,参数的估计值具有很强的集中性。采用150次仿真结果的平均值作为私家车出行者通勤出行时间价值分布函数的参数估计值,得到该分布函数服从参数为2.73和1.09的对数正态分布。这一分布函数可以作为实施和评价道路拥挤收费项目的依据。

基于Mixed Logit模型的路线选择行为量化分析

为了探讨路况信息动态变化对出行路线选择行为的影响程度,采用正交试验法设计出行意愿调查问卷,针对有驾车经验的出行者进行调查。假定时间参数和费用参数为常数、费用参数服从正态分布和对数正态分布,分别建立了出行路线选择的Logit模型和Mixed Logit模型,并对解释变量影响路线改变倾向进行了量化分析。结果表明,Mixed Logit模型的最大似然值、优度比和命中率都高于Logit模型。出行者对行程时间和时间信息动态变化的敏感程度十分接近,敏感度最高的是出行费用。个人属性中的年龄、驾龄和收入是影响路线选择行为的最显著因素。

基于GRA与SVM-mixed的货运量预测方法

铁路货运量与其影响因素之间关系复杂,单一核函数支持向量机(SVM)难以进行准确描述,而且各因素对铁路货运量的影响程度具有差异性,若忽略这种差异性,将难以获得理想的铁路货运量预测结果.为此,本文提出一种基于灰色关联分析(GRA)与混合核函数支持向量机(SVM-mixed)的铁路货运量预测方法.该方法采用灰色关联分析确定各影响因素的权重,再将赋予权重的影响因素作为输入变量,构建多项式核函数与径向基核函数线性组合的SVM-mixed预测模型.针对SVM-mixed参数难以确定问题,采用果蝇优化算法(FOA)选择SVM-mixed最优参数.基于中国铁路货运量的实例分析表明,该方法可有效提高铁路货运量的预测精度,为准确预测铁路货运量提供了一种新途径.

Recent advances in Pb-Sn mixed perovskite solar cells

Organic-inorganic hybrid lead-tin perovskite solar cells(Pb-Sn PSCs)have attracted much attention because of their advantages of low toxicity,variable bandgap,and feasibility for all-perovskite tandem solar cells,and the current power conversion efficiency(PCE)has exceeded 23%.However,due to the rambunctious crystallization process,easily oxidized Sn(Ⅱ)and inadequate energy level arrangement,there are many defects in perovskite films resulting in serious carrier recombination,which makes PCE still lag Pb-based PSCs.The quality of perovskite films is an important factor affecting the overall device performance.The selection and optimization of transport layers not only determines the interface energy level arrangement but also affects the carrier transport.In this paper,the research progress in improving performance of Pb-Sn PSCs in recent years is reviewed from aspects of perovskite layer and transport layers.The profound understanding of different promotion methods is summarized as well.These results have certain guiding significance for the future development and commercial application of Pb-Sn PSCs.

基于面板数据Mixed logit模型的自动驾驶选择行为分析

为准确把握自动驾驶环境下出行方式选择规律,引入面板数据Mixed logit模型分析在自动驾驶环境下表征出行者个体社会经济属性的年龄、收入、受教育程度等变量和表征出行方式特性的出行成本、等待时间、在途时间等变量对出行方式选择行为影响作用机理。利用新加坡自动驾驶出行意愿调研获得150位受访者在7个不同情景的1050个选择意愿有效样本数据,构建自动驾驶环境下出行选择行为模型。结果显示:模型卡方检验p值小于0.000说明模型具有较好的适用性;参数估计结果显示人群中不同个体对出行成本、等待时间、出行时间存在较强异质性;边际效应分析显示随着年龄增大选择自动驾驶、公交和步行出行概率增大选择网约车概率降低,当出行成本、出行时间、等待时间增加一倍将使选择自动驾驶出行概率降低近4.0%。

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.

Mixing of miscible shear-thinning fluids in a lid-driven cavity

The concentration and velocity fields of two refractive index matched miscible shear-thinning fluids in a lid-driven cavity were investigated by using planar laser-induced fluorescence and particle image velocimetry,as well by computational fluid dynamics.Quantitative analyses show that the results obtained by flow simulations with the species transport model are in good agreement with the experimental results.The effects of different parameters were studied by using the intensity of segregation.For two fluids with the same rheological parameters,the relative amounts of liquids H_(1)/H and the power-law index n dominate the mixing process while the Reynolds number Re plays a marginal role.As for two fluids with density difference,buoyancy has significant influence on the mixing process.The dimensionless group Ar/Re(redefined such as to include shear thinning behavior)is proposed for assessing the effect of buoyancy and rheological properties on the mixing of miscible shear-thinning fluids.

A Preliminary Study of Just-in-Time Methods for a Seamless Public Transportation Information Framework

A seamless multimodal transit system has been a goal for transportation planners and users. Owing to the developments of advanced public transportation and telecom technologies such as automatic vehicle location (AVL) and real-time passenger information system, key just-in-time (JIT) concepts can now be realized in process design and coordinated scheduling to shape a seamless multimodal transit system. JIT refers to a production system that times both movements of goods during production and delivery from suppliers together. It meets the same logic for seamless multimodal services. Therefore, this study innovatively analyzes possible public transportation technologies for JIT uses;moreover, to layout the possible application frame-work of a transportation technology based JIT multimodal transit system for main station area in Taipei city. With this innovative framework, multimodal transit services can deliver to the right place at right time.

考虑CAV与公交车比的混合交通流特性

为探究网联环境下汽车和公交车组成的混合交通流特性,考虑驾驶员行为改进Gipps安全距离规则,结合美国path实验室提出的自适应巡航(Adaptive Cruise Control,ACC)、协同自适应巡航(Cooperative Adaptive Cruise Control,CACC)跟驰模型加速度定义,构建异质流元胞自动机模型。通过数值仿真实验,分析网联自动驾驶车辆(Connected Autonomous Vehicles,CAV)与公交车辆混入比例对交通流通行能力、行驶速度、道路拥堵的影响。结果表明:随着CAV比例的提高,道路通行能力增大,临界密度增大;当道路上车辆组成仅为CAV车辆时,通行能力提升2.45倍、临界密度提高2.84倍;当CAV比例为0.5,随着公交车比例的增加,道路随机多发的轻微拥堵明显减少,通行能力、平均行驶速度略微减小。网联车能有效提高道路通行能力和行驶速度、减少拥堵,且随着公交车比例的提高,网联公交车更易形成队列,使道路拥堵得到明显改善。

高速公路客货混行交通流元胞传输模型

针对客货混行引发的交通流稳定性下降、交通安全风险增加以及运行效率降低等问题,构建一个多车道客货混行交通流元胞传输模型,从宏观角度研究不同货车渗透率下的高速公路客货混行交通流特性.首先,利用微观车辆跟驰模型,分析均质小汽车和货车交通流的基本图特征,提出不同货车渗透率下的客货混行交通流基本图模型.然后,采用具体参数表征换道、有限加速度造成的道路交通容量下降效应,刻画客货混行交通流中货车对直行和换道流量的影响,采用Logit模型计算多因素影响下的换道交通流量,构建多车道客货混行交通流元胞传输模型.最后,通过高速公路多场景仿真实验验证模型的有效性.研究结果表明:所提出的模型可准确模拟高速公路上的客货混行交通流演变过程;货车渗透率是影响混行交通运行的关键因素,在交通事件导致车道数减少时,货车渗透率超过0.6会导致交通拥堵难以消散.研究成果可为高速公路客货混行交通流特性研究提供分析工具,为客货混行下的交通管理和疏导策略制定提供理论方法.

智能网联环境下信号交叉口车辆轨迹重构模型

车辆轨迹数据提供了大量的时空交通流信息,可用于各类交通研究.传统车辆轨迹模型多以人工驾驶环境为研究对象,普遍未考虑由常规车(RV)、网联人工驾驶车(CV)以及智能网联车(CAV)组成的混合交通流的影响.为解决该问题,构建智能网联环境下信号交叉口全样本车辆轨迹重构模型.首先,介绍并分析智能网联环境下城市道路交叉口处车辆组成及排队通过情况;然后,构建城市道路混合交通流轨迹数量估计模型,并针对前后车的排队情况提出虚拟车的概念,用于估计不同车辆的交通状态;最后,设计数值仿真实验分析交通流密度和网联车渗透率对模型的影响,并基于NGSIM数据进行实例验证.结果表明:轨迹重构模型的数量误差和位置误差均随着交通流密度和网联车渗透率的增大而减小,如交通流密度由20 veh/km增大至50 veh/km的过程中,模型数量误差和位置误差均呈现下降趋势,且最大误差分别不超过6.88%和8.02 m;与网联人工驾驶车渗透率相比,智能网联车的渗透率对模型结果影响更大.

考虑CAV自主停车行为的混合交通均衡配流模型

为了评估网联自动驾驶汽车(CAV)的自主停车行为对交通系统效率的影响,建立了CAV通勤流、人工驾驶汽车(HDV)通勤流、CAV自主停车流3类交通流混行下的交通均衡配流模型.通过引入CAV停车需求内生变量,考虑CAV对路段通行能力的提升效应,从而定量描述CAV停车需求分布以及3类交通流在路段上混行的拥挤效应.分别采用用户均衡、随机用户均衡原则描述CAV、HDV出行者的路径选择行为,采用Logit离散选择模型描述自主停车CAV的停车场选择行为,由此建立多用户混合交通均衡条件以及等价的变分不等式(VI)模型.由于模型中CAV自主停车需求为未知的内生变量,提出一种改进的相继加权平均法求解该模型.最后,通过算例验证了混合交通均衡配流模型及求解算法的有效性.