基于安全库存策略的提高订单及时率方法研究

电脑供应链中的各种不确定因素使得非核心零部件中间商经常需要依靠大量备货或加急生产来满足客户需求。而当非核心零部件中间商不愿为此备货时,交货延迟的发生比例不可避免地会较高。针对此问题,本文提出了一种基于安全库存策略的提高订单及时率减少交货延迟的方法。此方法首先对电脑生产商的需求量进行估计,在综合考虑影响订单及时率的各类确定性和随机性因素的条件下,推导得到最优安全库存因子;然后,根据电脑生产商需求估计量与安全库存因子,计算出安全库存,如果电脑生产商需求量小于安全库存量,则使用安全库存直接交货,否则,向供应商追加订货后一并交货;最后,给出了该方法的年平均库存衡量公式。实证计算结果表明,与传统的面向订单生产方法(MTO)相比,本文方法可以使电脑零部件中间商的库存周转速度加快5~6倍,单位库存持有成本降至原来的14%,订单交货准时率提升至80%左右。     

面向订单的生产计划与调度的综合优化

研究了一个多订单环境下的生产计划与调度集成优化问题,以实现准时生产为目标,综合考虑产品装配结构约束的订单任务计划与订单产品零部件的加工调度,采用直接面向客户订单的工序调度模式建立了计划和调度的综合优化整数规划模型.设计了带精英策略的蚁群算法作为该数学模型的求解方法,并通过对比试验为该算法选取最佳的搜索参数.实例仿真结果表明,所建模型的正确性以及蚁群算法求解该问题的可行性和有效性.     

基于DBR系统的敏捷供应链协同机制

基于单一生产系统内部DBR生产计划与控制系统的实现机制,通过对其应用范围的进一步扩展,提出了供应链管理环境下DBR系统运作的六条基本原理,构建了供应链环境下DBR系统的基本框架,从计划、缓冲与控制机制三个方面对其实现机制进行了探讨.提出了支持DBR系统运作的供应链协同计划与控制模型,该模型基于单一节点企业内部DBR系统和供应链DBR系统的共同运作,通过面向订单对象的分布式生产控制模式和电子看板,实现供应链系统的协同计划与控制.     

面向供应链的ATP系统分析与计算

一个先进的ATP订单承诺系统可以帮助企业有效增加客户订单承诺和履行的准确性,缩短订单交货期,进而提高客户满意度和企业核心竞争力.设计了一个面向供应链的ATP系统(SC-ATP).与传统的ATP系统相比,其包含了三个核心模块ATP、CTP和PTP.首先分析了上述三个模块的相互之间的逻辑关系及各模块的计算方法,然后重点研究了双向CTP承诺算法的设计,并用具体的算例进行了验证.SC-ATP系统通过充分利用整个供应链的库存和空闲生产能力等信息完成客户提出的紧急订单承诺过程,可以确保承诺的准确性与可靠性.     

基于柔性组合策略的订单配置模型

随着社会消费量的不断增加,资源变得越发紧缺,对客户订单的柔性承诺以实现企业效益的最大化问题已成为供应链中每个企业考虑的关键问题.通过提出替代和二次交付相组合的订单配置策略,建立面向按订单装配型供应链(Assemble-to-Order Supply Chain)的柔性订单配置模型,研究多工厂多客户的供需环境下如何快速履...     

考虑排产约束的汽车零部件出库订单排序优化北大核心CSSCI

针对TPL仓库面向汽车零部件企业的产前物料拣选和配送作业环节,研究了JIT生产模式下配送送达时间限定和生产线缓冲库容量有限条件下的出库作业拣选订单排序的优化模型及算法。在分析现有拣选订单排序模式的基础上,提出了融合现有模式优点的新作业模式,建立了该模式下拣选订单排序优化模型,并针对这一整数组合优化模型,设计了一套基于贪心理论的算法对其进行求解。通过实际案例分析表明,该模型及算法可以达到减少拣选作业空余时间、提高作业效率、降低作业成本的目的。     

MRPⅡ中生产计划与控制的缺陷分析及改进

分析了制造资源计划的生产计划与控制模型不适合"按订单生产"的因素,如"同类项归并"、"事后性能力约束"等.结合按订单生产方式的特点,提出了一种如何接收订单和计划生产的方法.根据订单产品的物料清单、工艺路线,结合工作中心的能力计划,预估能满足客户需求的程度,来安排自身的生产和外协,以提高对客户需求的响应能力.在此基础上,提出了一个面向客户订单的生产计划与控制系统框架.     

考虑排产约束的汽车零部件出库订单排序优化

针对TPL仓库面向汽车零部件企业的产前物料拣选和配送作业环节,研究了JIT生产模式下配送送达时间限定和生产线缓冲库容量有限条件下的出库作业拣选订单排序的优化模型及算法。在分析现有拣选订单排序模式的基础上,提出了融合现有模式优点的新作业模式,建立了该模式下拣选订单排序优化模型,并针对这一整数组合优化模型,设计了一套基于贪心理论的算法对其进行求解。通过实际案例分析表明,该模型及算法可以达到减少拣选作业空余时间、提高作业效率、降低作业成本的目的。     

共享供应链产品质量水平与及时交货率决策研究

共享供应链是企业资源有效分享的新业态,如何在保证产品质量的同时,通过共享平台提高及时交货率是企业在共享经济下面临的新问题。本文针对一个由共享平台、共享工厂和中小零售商构成的共享供应链,考虑平常期、忙期和闲期三种情形,引入惩罚机制,探讨不同时期共享平台的定价选择决策,以及最优的产品质量和及时交货投入水平,提高共享供应链利润。结果表明:平台在不同时期有不同的定价策略;适当提高惩罚成本,能有效地提升工厂的质量和及时交货水平,进而提高供应链整体利润;在忙期可通过提高惩罚成本,降低平台佣金率来提升工厂及时交货率。     

基于物流能力约束的整车物流计划

基于时间竞争的敏捷供应链环境中,汽车整车物流必须按照客户订单对交货期、交货地点等的要求进行快速响应和准时配送.整车运输能力作为物流要素能力之一,由于其特殊性已成为整车物流的瓶颈,对物流绩效和供应链绩效形成重要影响.从压缩订单响应时间角度出发,在以整车运输能力为约束的条件下,提出了汽车整车物流准时配送计划问题,参照并行多机提前/拖期问题的研究方法,设计了一种制定整车物流配送计划的启发式算法,最后通过算例证明所提算法的可行性.     

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.……     

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.     

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 ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.