考虑缺货的两阶段腐败一体化库存—路径模型

在一个生产商给多个零售商配送单一易腐品的供应链中,考虑了一体化库存路径决策问题,并且零售商为了减少库存和运输相关成本而采用缺货损失策略。产品使用同质车辆配送,而在运输及销售过程中产品具有不同的腐败速率(两阶段腐败)。通过构建数学模型以最小化包括生产、配送、腐败、库存、缺货成本在内的供应链总成本。针对供应链库存决策,用数学证明得到函数性质以确定零售商缺货时间、订货周期及生产商的生产周期。针对离散的路径决策,采用固定分区策略对零售商进行分组,在每个分组内采用遗传算法求解对应的运输策略。设计求解算法并编制matlab程序求解问题,结合数值算例和灵敏度分析说明了模型的有效性及相关管理启示。     

异质车辆配送可重复装货易腐品库存—路径模型

研究了易腐品的订货、配送和车辆选型一体化决策问题。在一个供应商供应单一产品给多个零售商的供应链中,产品在运输阶段存在腐败,采用运行温度、车辆相关成本和腐败率有差异的异质车辆进行配送,联合决策模型的目标是确定每个零售商的配送车辆类型、配送路径及配送周期使得总成本最小。通过建立数学模型,证明了给定车辆类型和行驶路径后,单一车辆存在最优配送周期,由此设计了改进的节约算法嵌套对车辆类型的遍历对问题进行求解,结合实际企业背景,通过数值算例说明了易腐品配送车辆的选型问题,并得出了对企业的管理启示。     

基于延时还款期的供应链协调策略研究

建立了需求率依赖于库存量的单一供应商与单一零售商供应链库存及协调决策模型,首先分别对渠道内双方目标函数的性质进行分析,得出分散决策时零售商的最优订货量,并证明了集中决策供应链存在唯一最优的订货批量.进一步,采用零售商非线性信用期成本的核算方式,给出了能够取得供应链协调的供应商全信用期补贴策略.通过分析协调后供应链内双方...     

不确定需求下的两周期电信供应链订货策略

以电信业为背景,在不确定需求下研究了两周期电信供应链的投资决策和订货策略.考虑供应商第1周期投资可以减小第2周期成本,建立了两周期二级供应链订货模型,分析了3种订货策略:集中式供应链订货策略、供应商占主导地位的订货策略和制造商占主导地位的订货策略.分别给出了不同订货策略下的最优订货量和收益分享比例,并比较了不同订货策略下的订货量.结果表明集中式决策下的订货量总是介于2种分散式决策下订货量之间,制造商对订货策略的选择不依赖于供应商的投资行为,而供应商对订货策略的选择依赖于投资所能减小的单位成本的大小.     

供应链订货与营销渠道协调的主从对策模型

研究了供应链订货与营销渠道的协调问题,考虑了零售商具有订货成本缩减和营销投资成本,建立了供应链订货与营销渠道协调的Stackelberg主从对策模型.这一模型中,主方零售商具有产品零售价格和投资决策权,从方供应商具有产品批发价格决策权.分析了零售商四种投资策略,针对每种投资策略下的协调模型进行了数值仿真,结果表明在零售商订货成本缩减和营销之间进行投资协调能够同时增加零售商和供应商利润.     

供应商共享POS信息时的信息挖掘策略与方法

提出了在供应链中充分利用共享的部分信息推知未共享信息的思路,建立了供应商充分利用共享的POS信息推测零售商需求预测方法和库存控制策略的模型,通过实例说明了模型的可行性和有效性,并对供应商准确拟合零售商订货策略的价值进行了探讨,提出了供应商利用前馈信息调节零售商订货行为的思路.     

周期可变下考虑多车型的库存路径优化研究

目的 研究基于供应商管理库存模式下，由一个供应商和多个零售商组成的二级供应链配送系统的库存路径优化问题，确定计划期内各配送周期的长度、数量，对供应链中库存策略与配送方案问题进行协调优化，使系统总成本最低。方法 考虑的成本包括库存持有成本、缺货成本和配送成本。为降低供应链系统的总成本，提出全新的周期可变策略。结果 采用遗传算法求解得出最佳方案。将不同策略的算例结果进行对比分析，结果表明周期可变策略与周期固定策略相比，系统总成本最低节约比例为1.7%，最高节约比例为42.3%。结论 通过对计划期内各配送周期的长度及数量进行划分调整可以有效地节约系统总成本，同时，采用多车型的配送方案明显优于采用同车型的配送方案。     

制造商回购转运和加急生产协调策略

针对由单一制造商和两个竞争性零售商组成的供应链系统,研究回购契约下,制造商分别提供一次订货和两次订货机会时,两零售商的最优订货决策和制造商的最优回购转运和加急生产策略问题,并建立了相应的决策模型。通过对模型的分析,给出了在2种情形下,制造商和两零售商的最优决策。对比研究发现,在回购契约下,当满足一定参数关系时,制造商允许零售商二次订货,并采用转运和加急生产策略时,供应链各主体的利润相对仅提供一次订货机会时能得到更明显的改善,供应链整体利润获得进一步提高,供应链实现更优协调。     

考虑批量订货成本的最优JIT订货与生产策略

由于增大单次订单量会降低企业订货灵活性,为此引入批量订货成本来衡量采购商从下达订单到收货期间所面临的与订货批量相关的风险成本。采购商通过综合权衡订货成本、运输成本、库存成本以及批量订货成本,从而得出合理的最优订货批量。基于由采购商和供应商组成的供应链,首先在JIT批量分解模式下,研究考虑批量订货成本后,集中式决策和分散式决策下的最优订货和生产策略。由于分散式决策下一方利益最大化时的最优决策常常是另一方无法接受的,进而分析了上下游企业间的不同议价能力,给出了双方均可接受的订货与生产策略。     

基于寄售的供应链批量协调问题研究

随着生产商柔性的提高,在基于寄售库存的供应链中,生产商和批发商的订货及库存持有成本发生了显著的变化,以此为背景,建立了一对一的供应链在寄售情形下的成本函数和批量模型,提出了当生产商的最优生产批量小于批发商的最优订货批量时,生产商可以通过按批发商的订货批量提供一定比例寄售,并转移部分获得收益给批发商的批量协调策略。算例分析表明,在一定条件下,该策略能够使生产商和批发商同时受益,从而使整个供应链实现帕累托优化。     

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.     

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...     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.……     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.