A multi-echelon production–inventory system with supply disruption

The article investigates an integrated multi-layer supply chain model consisting of supplier, manufacturer and retailer while supply disruption, machine breakdown, safety stock, maintenance breakdown occur simultaneously. At beginning of the production, manufacturer keeps some raw materials in stock received from second supplier at high price, as safety stock due to supply disruption of first supplier. Corrective maintenance is done immediately to restore its normal stage when machine breakdown occurs. Stock out situations at manufacturer and retailer are considered due to disruption of production for machine breakdown. The integrated expected costs of the chain in centralized (collaborating) and decentralized (Stakelberg approach) system are compared. A numerical example and its sensitivity analysis are provided to test feasibility of the model.     

开关电源高频变压器超声波测量装置设计

高频变压器是开关电源的核心元器件,在开关电源高频的趋势中,如何测量高频变压器的高频噪音成为业界所面临的棘手问题。提出一种开关电源高频变压器超声波测量装置,可以精确、便捷地测量超出人耳听觉范围的超声波,并通过微处理器处理分析测量信息后,在显示屏中得到所选定高频噪音频率段的平均功率等级。     

New trends on e-Procurement applying semantic technologies: Current status and future challenges

The present paper introduces and reviews existing technology and research works in the field of e-Procurement. More specifically this survey aims to collect those relevant approaches that have tackled the challenge of delivering more advanced and intelligent e-Procurement management systems due to its relevance in the industry to afford more timely, adaptable and flexible decisions in purchasing processes. Although existing tools and techniques have demonstrated their ability to manage e-Procurement processes as a part of a supply management system there is a lack of interoperability among tools, tangled dependencies between processes or difficulties to exploit existing data and information to name a few that are preventing a proper use of the new dynamic and data-based environment. On the other hand semantic-based technologies emerge to provide the adequate building blocks to represent domain-knowledge and elevate the meaning of information resources through a common and shared data model (RDF) with a formal query language (SPARQL) and accessible via the Internet Protocols. In this sense the Linked Data effort has gained momentum to apply the principles of the aforementioned initiative to boost the re-use of information and data across different tools and processes. That is why authors review both existing open issues in the context e-Procurement with special focus on public procurement and semantic-based approaches to address them. To do so a preliminary research study is conducted to assess the state of the art in the context of e-Procurement and semantic-based systems. Afterwards main drawbacks of existing e-Procurement systems are presented to narrow down in semantic-based approaches applied to this field. Once the current status in both areas is reviewed, authors purpose the use and creation of an e-Procurement index to evaluate the quality of service of procurement systems. In this light the Analytical Hierarchy Process (AHP) method is used to set up an initial weight for each indicator in the index and to perform a first comparison between traditional and semantic-based approaches. Finally some discussion, conclusions and future challenges are also outlined.     

供应链环境下安全的RFID认证方案

供应链环境下RFID安全认证方案不仅要保证各节点的隐私安全,还应该满足供应链管理需求。针对现有方案存在不能同时兼顾两者的不足,提出一种基于"双重签名"的认证方案。标签的认证信息先后采用访问密钥和认证密钥进行双重签名生成,只有同时具备这两个密钥才能识别标签身份。该方案既可以实现标签在供应链内的安全传递,又能方便供应链的管理。分析表明,该方案较现有方案优势明显。     

多Agent的供应链分布式仿真系统设计与实现

供应链是由供应商、制造商、仓库、配送中心和渠道商等构成的物流网络。并且供应链已经为社会带来了巨大的经济效益,本文就多Agent的供应链分布式仿真系统设计做了详细的研究,以便其能够很快的得到实现。     

对辽河坳陷陆上基岩油气藏高效勘探的认识

近年来潜山勘探已成为辽河坳陷陆上主要勘探目标之一。在了解了辽河坳陷陆上由"潜山勘探"向"基岩勘探"的理念转变及辽河坳陷陆上基岩成藏具有的得天独厚的有利条件的同时,通过对基岩的研究与勘探实践,建立完善了辽河坳陷陆上四种类型的基岩成藏模式。     

煤炭运输路径选择与运输效率的关系模型仿真

在煤炭运输路径优化选择问题的研究中,煤炭运输网络在雨雪、泥石流、地震等突发事件下会发生路线的重新选择,选择路线过程带有波动性与随机性,受主观人为因素影响较大.传统的煤炭运输供应链路径选择与运输效率的关系模型建立方法无法对瞬时变化的路线选择进行自适应调整,无法建立包含路线突变情况的约束条件,建立的模型准确性较低.提出基于关联模糊理论的煤炭运输供应链路径选择与运输效率的关系模型建立方法,塑造可量化的煤炭运输供应链网络演化模型,依据供应链网络鲁棒性新测度,根据小范围供应链效率和连同图大小运算网络中单个节点的运输效率,将量化后的鲁棒性与效率的关系划分成两个独立的特征子空间以及非特征子空间,准确描述两者关系.仿真结果表明,在不同的干扰环境下新建模型能够较好地表述煤炭供应链路径选择与效率的关系.     

Stochastic integer programming models for reducing wastages and shortages of blood products at hospitals

Major challenges in the management of the blood supply chain are related to the shortage and wastage of the blood products. Given the perishable characteristics of this product, storing an excessive number of blood units on inventory could result on the wastage of this limited resource. On the other hand, having shortages may result in cancellations of critical health related activities and as a result a potential increase on fatality rates at hospitals.This paper presents integer programming models to minimize the total cost, shortage and wastage levels of blood products at a hospital within a planning horizon. The primary focus is on the red blood cells and the platelet components of the whole blood cells. The stochastic and deterministic models included consider uncertain demand rates, demand for two types of patients, and crossmatch-to-transfusion ratio. Results show wastage rates decreasing from 19.9% to 2.57% on average. In addition, the shortages and total cost are reduced 91.43% and 20.7% respectively for a given capacity increases. Computational results are included and discussed.     

直流稳压电源轻松做

电源是电路的核心,是电子电路制作过程中必不可少的设备。一个好的直流稳压电源能让电路制作事半功倍,效果显著。一般直流稳压电源由变压器、整流、滤波、稳压等几个部分组成。本文介绍了一种简单实用的直流稳压电源的制作。     

不确定需求和配送时间窗约束下的供应链优化

供应链中生产配送的协调对于生鲜食品有重要作用.为解决不确定需求下生鲜食品的生产配送联合决策问题,考虑生鲜食品的送达需满足零售商的硬时间窗;同时商品一旦送达就会产生腐坏,而供小于需也有缺货成本.研究构建了一种数学模型来考虑生鲜食品的生产配送,采用改进的蚁群算法求车辆路径问题,迭代解带入目标函数,再采用Nelder-Mead单纯形法求生产调度,从而得到总优化成本.结果表明,采用集成决策时,供应链中生产和配送成本有较大幅度下降,但同时车辆启动成本的存在会使目标成本出现转折点.实验结果表明了模型的正确性和算法的良好性能.