Incorporating inventory control decisions into a strategic distribution network design model with stochastic demand

In this paper, we propose a simultaneous approach to incorporate inventory control decisions––such as economic order quantity and safety stock decisions––into typical facility location models, which are used to solve the distribution network design problem. A simultaneous model is developed considering a stochastic demand, modeling also the risk pooling phenomenon. We present a non-linear-mixed-integer model and a heuristic solution approach, based on Lagrangian relaxation and the sub-gradient method. In a numerical application, we found that the potential cost reduction, compared to the traditional approach, increases when the holding costs and/or the variability of demand are higher.     

Incorporating location,routing and inventory decisions in supply chain network design

This paper for the first time presents a novel model to simultaneously optimize location, allocation, capacity, inventory, and routing decisions in a stochastic supply chain system. Each customer’s demand is uncertain and follows a normal distribution, and each distribution center maintains a certain amount of safety stock. To solve the model, first we present an exact solution method by casting the problem as a mixed integer convex program, and then we establish a heuristic method based on a hybridization of Tabu Search and Simulated Annealing. The results show that the proposed heuristic is considerably efficient and effective for a broad range of problem sizes.     

Fulfillment source allocation,inventory transshipment,and customer order transfer in e-tailing

We consider an inventory fulfillment-allocation and transshipment problem in an e-tailing environment. For a typical e-tailer, each customer demand is fulfilled from the closest fulfillment center if there are enough inventories. Otherwise, the e-tailer would transship stock from a nearby facility or transfer the customer order so it is fulfilled from another facility, depending on the economics of transportation. We develop a mixed-integer programming model to help e-tailers optimally fulfill customer orders while minimizing logistics costs. We propose a Benders decomposition-based approach to efficiently find optimal solutions. Our computational results demonstrate the importance of considering inventory transshipments in online deliveries.     

Cost adjustment for single item pooling models using a dynamic failure rate: A calculation for the aircraft industry

This paper presents an analytical model for cost estimation in a single-item, multi-hub (S-1,S) inventory policy-pooling model for high-value spare parts in the aviation industry. The model extends existing, static pooling models by implementing a dynamic failure rate, using a maintenance free operating period (MFOP) as a measurement technique to increase availability of aircraft components. The gained results through a dynamic failure rate show significant effects for a reduction of total costs of ownership and achieving a better operational stock planning, which is demonstrated in a numerical application.     

Cost allocation in spare parts inventory pooling

In this paper we present the use of game theoretic models to analyse the cost allocation problem in the context of repairable spare parts pooling. Two situations are studied. In the first situation, all pooling members fully cooperate without having self-interest. We use the core concept from cooperative game theory as the basis for designing a fair cost allocation. In the second situation, competition exists as each member has an interest in maximizing his own benefit. Using the concept of Nash equilibrium, we show that the cost allocation policy influences the companies in making their inventory decisions.     

Cost adjustment for single item pooling models using a dynamic failure rate: A calculation for the aircraft industry

This paper presents an analytical model for cost estimation in a single-item, multi-hub (S-1,S) inventory policy-pooling model for high-value spare parts in the aviation industry. The model extends existing, static pooling models by implementing a dynamic failure rate, using a maintenance free operating period (MFOP) as a measurement technique to increase availability of aircraft components. The gained results through a dynamic failure rate show significant effects for a reduction of total costs of ownership and achieving a better operational stock planning, which is demonstrated in a numerical application.     

Hybrid approaches based on SARIMA and artificial neural networks for inspection time series forecasting

In this paper, the number of goods subject to inspection at European Border Inspections Post are predicted using a hybrid two-step procedure. A hybridization methodology based on integrating the data obtained from autoregressive integrated moving averages (SARIMA) model in the artificial neural network model (ANN) to predict the number of inspections is proposed. Several hybrid approaches are compared and the results indicate that the hybrid models outperform either of the models used separately. This methodology may become a powerful decision-making tool at other inspection facilities of international seaports or airports.     

和谐型机车车轮车轴综合探伤技术体系的研究

论述建立和谐型大功率机车车轮车轴综合探伤体系的必要性,分析和谐型大功率机车轮对探伤要求,研究和谐型大功率机车轮对缺陷综合检测体系技术,提出了在日常动态检测、定期在线检测和定期落轮检测三个层次上建立和谐机车轮对综合检测体系,以保障机车走行部运行安全.     

The impact of control strategies on the management of returnable transport items

This research examines the impact of different control strategies on the management of returnable transport items (RTIs) in closed-loop supply chains. A simulation model is developed based on an empirical case and is used to explore different scenarios. The results suggest that the choice of control strategy has a significant impact on investments and operating costs, and that RTI shrinkage can be controlled either through the use of tracking systems, or choice of control strategy. Moreover, a simulation-based method for estimating the fleet size required to operate the system for the different strategies is presented.     

Consolidation effects and inventory portfolios

This paper presents a formal analysis of the consolidation effect in a wider perspective. While demonstrating that the stock saving structure depends on the interaction between the coefficient of variation of demand and the ratio between inventory ordering and holding costs, this research indicates that the ratio between the standard deviations of lead time at potential facilities is the key variable for consolidation. Sensitivity analyses are also performed to address common managerial issues, which can arise during the consolidation decision, such as the impact on total costs and the assumption of uncorrelated demands.     

着眼治理安全质量隐患提升铁路客站建设项目管理水平

为全面提高铁路客站建设管理质量和水平,近期铁路展开在建高铁车站质量安全督导和检查。回顾近几年铁路客站建设取得的成就,针对在建高铁客站质量安全督导和检查的情况,分析当前铁路客站建设在安全质量工作方面亟待解决的问题,结合铁路客站建设项目管理切身体会,提出提升客站建设项目管理水平的针对性建议。     

A two-echelon inventory allocation and distribution center location analysis

The optimization of locations for distribution centers is influenced by the demand for individual products. Lower demand products are often more effectively held in more centralized locations than higher demand products. This paper presents a model for optimizing the location of inventory for individual products in a multi-product two-echelon inventory system and the integration of those decisions into the location analysis for distribution centers. A realistic application of the analysis process is discussed.     

Reliable product-service supply chains for repairable products

A mathematical model is developed for integrated flow planning in forward and after-sales supply chains of a company supplying repairable product-warranty packages to markets. Ignoring their interactions, these two supply chains are usually planned separately in literature. We consider demand- and supply-side variations in pre- and after-sales demands and qualified outflow of the SCs’ facilities. We show that to neutralize the impact of variations, orders should be amplified by moving from the downstream to the upstream of chains. Results of an example from the gear industry show what interdependencies exist between the company’s retail price, service levels, and warranty strategies.     

铁路机车检修修制改革方案探讨

武威南机务段为解决运输任务增长与机车配属不足的矛盾,推行了机车检修修制改革。新修制改为一、二级检修及小修三级修程,并对其执行情况及所取得的成绩作了介绍,最后指出新修制尚存在的问题及其进一步的发展方向。     

Optimizing inventory decisions in a multi-stage multi-customer supply chain: A note

In this paper, we propose an n-stage-multi-customer supply chain inventory model where there is a company that can supply products to several customers. We formulate the model for the simplest inventory coordination mechanism which is referred to as the same cycle time for all companies in the supply chain. We conclude that it is possible to use an algebraic approach to optimize the supply chain model without the use of differential calculus.     

Design and analysis of a two-stage security screening and inspection system

Security inspections are becoming a commonplace activity in locations ranging from airports to museums and shopping malls. Theses inspections can result in significant operational costs to a facility and to entry delays for the individuals being inspected. In this paper we focus specifically on passenger inspections at US airports. We consider a two-stage inspection system in which we are able to control the service rate of the first inspector. The relationship between the inspection service rate and accuracy is assumed described by a known speed and accuracy operating characteristic curve. Using a queuing model we derive the optimal design for the passenger security inspection operation at a given arrival rate, and also evaluate the utility of any investments in inspection rate improvement. The primary performance metric for the security inspection system is the average waiting time of the arriving entities or passengers. The optimal result specifies the number of inspectors at each stage, the service rate of the first inspector, and the total system cost. Numerical results with an example system are presented.     

基于库存理论的铁路始发直达运输产品设计

将库存理论运用到铁路始发直达运输产品设计,能够有效实现运输服务组织成本与库存成本的有机统一。为实现库存成本在铁路始发直达运输中的加载,在考虑周期非完整情况下的库存成本的同时,将铁路运输和库存成本纳入同一目标函数,在装卸车地库存能力约束下,构建基于库存理论的铁路始发直达运输产品设计模型,确定成本最小的铁路始发直达运输产品设计方案。以赤峰地区至山东省煤炭运输网络为例,设计方案有效降低了成本,有助于吸引客户选择铁路运输,以及辅助铁路运营单位研究调整始发直达运输产品方案。     

基VMI的供应链利润模型研究

研究了供应链管理环境下新的库存策略。建立了基于VMI的有初始库存、允许库存短缺、缺货需补充、补充具有延时的供应链利润模型，并对该模型进行了供应链总的库存相关成本及供应商的库存相关成本分析。     

统一授信存货质押下第三方物流选择研究

选择合适的第三方物流是统一授信模式存货质押业务顺利开展的关键环节.在对国内外存货质押研究现状进行分析的基础上,从市场竞争力、监管技术水平、品牌与信誉及地域交通4个方面构建统一授信存货质押下第三方物流选择的评价指标体系,建立了层次分析法与灰色评价相结合的多层次灰色评价模型,研究银行开展统一授信存货质押业务中如何选择第三方物流,并通过案例说明模型的有效性.