公交车调度

本文利用多目标优化方法建立了公交车调度的数学模型.首先通过数据分析,并考虑到方案的可操作性,将一天划分为早高峰前,早高峰,早高峰和晚高峰之间,晚高峰及晚高峰后5个时段;引入车辆的平均满载率,乘客的等待抱怨程度及拥挤抱怨程度作为三个目标函数,建立了三目标优化模型;通过加权,将三个目标函数合并为一个目标函数.运用MATLAB数学软件计算出了上行、下行各个时段发车的时间间隔:上行各时段时间间隔分别为5、2、4、3、15,下行各时段时间间隔分别为10、2、5、3、8(单位:分钟);所需总车辆数为52辆,共发车534次,公交公司的平均满载率为82.094%,抱怨顾客的百分比为0.91%.通过模型检验得出所求模型较为稳定.最后,通过对原始数据的分析和处理,得出在进入和离开乘客高峰时期,局部缩短采集数据时间间隔是改善调度方案的有效方法.     

公交车系统调度模型构建

首先,我们将一天的时间分成了不同的多个时间段。然后,在每个时间段内,我们考虑到公交车公司和乘客两方面的利益,引入了公交车载客的平均满载率、乘客的等待时间和拥挤程度这3个目标函数来衡量公交车公司的利益和乘客的满意度。为求解该目标规划,我们采用了加权系数法,引入了加权因子,使多目标函数转化成单一目标的模型。同时也可以由求得的行车计划得到了公车站交所需的最小车辆数。     

基于候车与乘车满意度的公交车调度优化模型

本文讨论公交车调度的数学建模问题.我们根据各个时刻、各个站点上、下车乘客人数的历史数据与随机特征,计算乘客到达速率、离站速率的期望值.基于效用函数理论,我们从两方面考虑乘客满意度,即由候车时间确定的候车满意度和由拥挤度确定的乘车满意度.以极大化总的加权满意度为目标,我们构建了公交车调度的混合整数规划问题.最后给出了求解这个问题的可能方法.     

复合材料序列图像的分层次配准

在复合材料图像三维重构技术中,为了避免直接运用基于特征点的整体配准陷入局部极优,采用分层次的配准方法.首先使用不变矩计算出上下层图像中最相似的颗粒轮廓,然后使用主轴的配准方法完成上下层图像的初步配准,以大幅度减少特征点配准中的优化搜索范围.在计算出轮廓曲线上特征点的基础上,应用最大熵原理和lagrange乘子将点集之间的匹配转化为一个能量函数,再使用最小二乘法计算出使该能量函数值最小的空间变换,得到配准的最优解,从而实现了序列图像的整体精确配准.实验结果表明,本文提出的分层次的配准方法极大地降低了配准过程陷入局部极优的概率,具有较强的鲁棒性和较高的配准精度.     

一类改进的GOM(1,1)模型及其应用

本文考虑非负递减序列的建模预测问题.考虑到灰作用量会随着时间和空间的变化而发展变化,将灰作用量近似看作为时间的线性函数从而构建了灰作用量优化的GOM(1,1)模型.结合灰色预测模型数据序列的非齐次指数特性,利用积分推导出GOM(1,1)模型的最优化背景值.以原始序列和模拟序列的平均相对误差平方和最小为原则,确定最优的时...     

公交车调度问题的研究

本题为带软时间窗的单线路单车型的公交调度问题,针对其多目标、多变量的动态特点,我们为满足不同的实际需求建立两个多目标规划模型:双车场模型和单车场模型.双车场模型的主要目标是使运客能力与运输需求(实际客运量)达到最优匹配,单车场模型的主要目标是使乘客的平均不方便程度和公交公司的成本达最小,其目的都是为了兼顾乘客与公司双方的利益.两个模型的主体都是采用时间步长法,模拟实际的运营过程,从而得出符合实际要求的调度方案:静态调度和动态调度方案.     

客货邮融合下城乡客运车辆调度双层优化方法

为了健全县乡村三级物流配送体系，补齐农村寄递物流基础设施短板，客货邮融合模式应运而生。客货邮融合主要借助客运车辆进行实施，但由于农村地区客运车辆存在发车频次少等情况，使得客货邮融合在实施过程中面临着客运车辆运营成本高及快递配送时间长等问题。针对营运成本及客货配送问题，通过考虑客货邮融合下的城乡客运车辆调度优化，构建车辆协调调度的双层规划模型，可以实现车队规模优化，并改善农村地区快递末端配送时效性。上层规划模型以乘客与货件总旅行时间为目标，下层规划模型以车队规模为目标。利用逆差函数将下层目标转化为模型的约束条件，在确定车队规模的基础上求解双层规划模型的最优解。通过算例分析，比较客货邮融合和客货分离两种情况在总旅行时间上的差异，结果表明考虑客货邮融合可以有效改善不同车队规模情况下的乘客与货件的总旅行时间。     

考虑电量消耗的车辆调度优化研究

基于电动汽车电量消耗特性,考虑电动车里程、载重、顾客服务时间窗等约束,建立以配送总成本最小为目标的电动车调度优化问题模型;利用自然数编码的遗传算法,求解出电动车的配送路线以及车辆的充电计划,再结合枚举法,在配送中心运营时间内以10 min为时间间隔,计算出配送车辆惩罚成本最小时的最优发车时刻。最后结合算例,验证该模型和方法的有效性、正确性。     

基于改进粒子群算法的电梯优化调度研究

针对上班高峰期多台电梯调度的问题,建立了反映整个电梯服务系统特征的数学模型,以达到最小化乘客的平均等待时间即候梯时间为调度目标,在此基础上,利用改进粒子群算法对电梯相应的服务楼层分区方案进行迭代寻优,同时满足最小化电梯平均运行时间和载客人数的要求,使所有电梯发挥其最高效的作用.在模型的求解过程中采用非线性方程的数值解法进行求解,并通过Matlab编程最终得到电梯相应服务楼层的优化调度方案.这两者的结合在仿真中取得了有效的成果,证明了这一调度方法的实用性和有效性.     

对于公交汽车调度问题的求解

为了根据所给的客流量及运营情况排出公交车调度时刻表,并尽可能地满足乘客与公交公司双方的利益,我们建立了基于图形分析的模型一和基于计算机模拟的模型二,并在模型扩展中运用已建的计算机模拟系统对所得的结果和我们对于优化调度方案的想法进行分析和评价.公交车辆调度所要处理的数据量是巨大的,所以如何有效地重组、利用已知数据是我们建立模型一的突破口.我们首先对数据进行处理,得到了各站在各个时刻等待上车的人数曲线Di(t)与净上车人数曲线Bi(t).平移Di(t)与Bi(t),平移的距离就是起始站到各站的时间.经过适当叠加后我们得到了D(t)与B(t)两根新的曲线,在tj-1至tj时段内对D(t)、B(t)进行积分得到值的分别是累计乘上tj发出班车的总人数和tj发出班车在全程内的最大车上人数,前者与收益有关,后者和汽车载客量有关.这样,所有和制定发车表有关的信息都被包涵在了两根曲线D(t)、B(t)中,而时刻表的制定更是简单地转化成了沿时间轴对B(t)包围的面积进行划分,划分直线的间距就是发车间距.为了满足双方的利益,我们建立了效用函数来保护双方的利益,比如在惩罚函数的监督下使公司发车间隔严格按照给定的要求;而公司也会尽量增加发车间隔以增加车辆满载率.由此制定的方案是能够让双方都满意的.结合程序,公司只需输入题中给出的数据便可得到最佳汽车调度表,包括共需车辆数、起始时刻两头车辆分配和发车时刻表,具有很强的可操作性.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...