基于Project 2003的关键链启发式算法

介绍了关键链项目管理的基本方法;针对资源受限项目调度问题,提出了资源冲突时的资源分配原则;以项目工期最小化为目标,以Proiect 2003为辅助工具,提出了一个确定关键链的启发式算法,即在找出关键路径的基础上,从后往前遍历,对发生资源冲突的活动,依资源分配原则修改紧前关系,然后再确定关键链,进而得到了基于关键链项目管理方法的项目调度算法.对算法进行了验证,结果表明算法是有效的.     

基于混合智能算法的多资源约束项目优化调度

 基于关键链项目管理(critical chain project management,CCPM),利用一种混合智能优化算法求解多资源约束项目调度问题,解决传统调度优化算法的不足,提高这类问题的求解质量.首先利用一类启发式算法识别项目关键链,并设置缓冲区尺寸,以项目总工期和在制品库存为优化目标建立数学模型,设计一种混合智能优化算法求解,并对项目问题库中的j30hrs.sm问题和某生产型项目进行实验分析,得到优化的结果.实验表明,采用混合智能算法求解这类问题能得到明显优于一般调度优化算法的结果.     

基于活动重心定理的关键链识别法

针对关键链识别这一关键链调度理论的基本问题,建立了以活动重心为优先规则的两阶段关键链识别启发式求解方法。并运用数理统计学假设检验方法,以Patterson110问题集为样本,将新构建的算法与三种基于较好优先规则的启发式算法进行了比较,统计数据说明论文构建的迭代重心法有一定的先进性,同时极大地简化了关键链的识别过程。     

基于人员-任务-资源匹配度的产品设计项目静态调度

设计人员和技术资源的特点使得产品设计项目优化调度建模及求解的复杂性大大增加。首先对产品设计项目中的三大主要要素的属性进行了深入地分析,并提出了任务-人员-资源匹配度的评价指标和计算方法;其次,借助多模式资源受限问题的思想,将设计人员和技术资源分别考虑,并将设计人员、技术资源和设计任务三者的匹配度以及技术资源强度引入到调度模型中,建立了针对产品设计项目的多模式资源受限调度数学模型;最后,设计了一种双层单亲遗传算法,实现了对模型的求解,得到了工期最短目标下最优的任务、设计人员、技术资源调度方案。案例分析结果表明,基于人员-任务-资源匹配度的多模式优化调度模型充分体现了设计项目的特点,有利于人力资源和技术资源的优化配置。     

基于混沌粒子群的资源受限项目调度问题

鉴于基本粒子群算法易陷入局部最优,提出一种将混沌算法嵌入基本粒子群的混沌粒子群算法,并将其用于求解典型的资源受限项目调度问题。采用基于优先值的粒子编码方式和串行调度方案,分别用基本粒子群算法和混沌粒子群算法对实例求解。并且比较了2种算法求解多资源受限项目调度问题的性能。结果表明:混沌粒子群算法在距最优值的平均偏差和达到最优值的次数百分比等性能上要优于基本的粒子群算法,并且混沌粒子群具有更好的收敛性。但是,混沌粒子群算法在计算达到最优工期的平均时间上略比基本粒子群算法逊色。     

考虑降低碳排放的废钢铁再制造等待时间受限生产调度研究

针对工件等待时间受限的废钢铁再制造生产调度问题,在碳排放约束下构建了等待时间受限的废钢铁再制造生产调度模型,并设计遗传算法进行了求解.最后结合算例,比较分析了碳排放对生产调度的影响,并得出:废钢铁再制造过程产生的碳排放量与设备空转时间呈显著的正相关关系;工件等待时间受限作为约束其主要作用在于避免重调度,对于减少makespan和碳排放量影响不大.     

多资源作业车间的混合自适应GA优化调度

针对多资源约束的车间调度问题,将启发式算法和自适应GA优化方法结合起来,提出了混合自适应GA方法,建立了多资源约束的车间优化调度模型.根据启发式调度算法中优先规则对调度目标的影响,设计了新的编码规则.采用正弦函数作为自适应因子,使得交叉概率和变异概率随群体的适应度自动改变,提高了运算的效率,克服了启发式算法和普通GA的缺陷.通过实例仿真并与其他算法比较结果表明,混合自适应GA算法可以很好的解决作业车间在机床、刀具等多种生产资源约束下的优化调度,并在评价指标上较其他算法更优.     

基于优先规则的模糊资源受限多项目调度

在分析国内外相关研究现状的基础上,结合资源受限多项目调度问题的特点,针对多项目中各个工序资源参数的不确定性,通过对工程项目工序资源需求量的模糊表示,建立了模糊资源受限多项目调度模型,并运用基于优先规则的启发式算法对所建立的模型进行调度计算,最后通过算例验证模型的有效性和可行性,以实现多项目资源的优化配置。     

基于多智能体技术解决多项目资源受限调度问题的方法研究

在对单项目资源受限调度问题进行分析的基础上,进一步研究多项目资源受限调度问题,并给出基于多智能体技术的调度算法,同时采用多种策略对整个项目运行情况进行监控与调整,以解决跨企业项目中的生产规划与资源调度问题。     

基于约束和邻域的炼钢连铸重调度算法

针对机器故障扰动,研究了炼钢连铸重调度问题及其求解算法。通过将机器故障映射为资源约束,建立了基于动态约束满足的炼钢连铸重调度模型,模型以最大化连浇量与调度方案相似度为目标。针对问题的模型及其特点,采用约束满足和邻域搜索相结合的混合算法对其进行了求解。仿真实验表明本文提出的模型和算法是有效的。     

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.……     

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.     

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.     

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 ...