Keputusan Pembangunan Pusat Distribusi yang Berkelanjutan dalam Rantai Pasokan

Rantai pasokan merupakan sebuah jaringan yang mengelola pengadaan bahan baku, transformasi bahan baku ke produk antara dan akhir, dan distribusi produk akhir ke pengecer atau pelanggan. Menentukan lokasi fasilitas (pusat) distribusi dalam rantai pasokan dengan kendala pemenuhan pasar memungkinkan Perusahaan lebih dekat kepada pelanggan, dan memberikan keuntungan kompetitif. Mengurangi waktu transportasi dan penggunaan minyak, biaya tenaga kerja dan peralatan merupakan faktor utama untuk membantu Perusahaan untuk mengurangi emisi karbon dan meningkatkan profitabilitas mereka. Dalam paper ini kami mengusulkan sebuah pendekatan MINLP untuk menyelesaikan model optimisasi untuk memutuskan pusat distribusi berbasis pertimbangan lingkungan

The Complexity of Safety Stock Placement in General-Network Supply Chains

We consider the optimization problem of safety stock placement in a supply chain, as formulated in [1]. We prove that this problem is NP-Hard for supply chains modeled as general acyclic networks. Thus, we do not expect to find a polynomial-time algorithm for safety stock placement for a general-network supply chain.Singapore-MIT Alliance (SMA

An enhanced approximation mathematical model inventorying items in a multi-echelon system under a continuous review policy with probabilistic demand and lead-time

An inventory system attempts to balance between overstock and understock to reduce the total cost and achieve customer demand in a timely manner. The inventory system is like a hidden entity in a supply chain, where a large complete network synchronizes a series of interrelated processes for a manufacturer, in order to transform raw materials into final products and distribute them to customers. The optimality of inventory and allocation policies in a supply chain for a cement industry is still unknown for many types of multi-echelon inventory systems. In multi-echelon networks, complexity exists when the inventory issues appear in multiple tiers and whose performances are significantly affected by the demand and lead-time. Hence, the objective of this research is to develop an enhanced approximation mathematical model in a multi-echelon inventory system under a continuous review policy subject to probabilistic demand and lead-time. The probability distribution function of demand during lead-time is established by developing a new Simulation Model of Demand During Lead-Time (SMDDL) using simulation procedures. The model is able to forecast future demand and demand during lead-time. The obtained demand during lead-time is used to develop a Serial Multi-echelon Inventory (SMEI) model by deriving the inventory cost function to compute performance measures of the cement inventory system. Based on the performance measures, a modified distribution multi-echelon inventory (DMEI) model with the First Come First Serve (FCFS) rule (DMEI-FCFS) is derived to determine the best expected waiting time and expected number of retailers in the system based on a mean arrival rate and a mean service rate. This research established five new distribution functions for the demand during lead-time. The distribution functions improve the performance measures, which contribute in reducing the expected waiting time in the system. Overall, the approximation model provides accurate time span to overcome shortage of cement inventory, which in turn fulfil customer satisfaction

Keputusan Pembangunan Pusat Distribusi yang Berkelanjutan dalam Rantai Pasokan

Rantai pasokan merupakan sebuah jaringan yang mengelola pengadaan bahan baku, transformasi bahan baku ke produk antara dan akhir, dan distribusi produk akhir ke pengecer atau pelanggan. Menentukan lokasi fasilitas (pusat) distribusi dalam rantai pasokan dengan kendala pemenuhan pasar memungkinkan perusahaan lebih dekat kepada pelanggan, dan memberikan keuntungan kompetitif. Mengurangi waktu transportasi dan penggunaan minyak, biaya tenaga kerja dan peralatan merupakan faktor utama untuk membantu perusahaan untuk mengurangi emisi karbon dan meningkatkan profitabilitas mereka. Dalam paper ini kami mengusulkan sebuah pendekatan MINLP untuk menyelesaikan model optimisasi untuk memutuskan pusat distribusi berbasis pertimbangan lingkungan. Kata kunci : rantai pasokan, pusat distribusi, keberlanjutan, MINLP, modelin

Optimizing safety stock placement in general network supply chains

Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2004.Includes bibliographical references (p. 207-214).The amount of safety stock to hold at each stage in a supply chain is an important problem for a manufacturing company that faces uncertain demand and needs to provide a high level of service to its customers. The amount of stock held should be small to minimize holding and storage costs while retaining the ability to serve customers on time and satisfy most, if not all, of the demand. This thesis analyzes this problem by utilizing the framework of deterministic service time models and provides an algorithm for safety stock placement in general-network supply chains. We first show that the general problem is NP-hard. Next, we develop several conditions that characterize an optimal solution of the general-network problem. We find that we can identify all possible candidates for the optimal service times for a stage by constructing paths from the stage to each other stage in the supply chain. We use this construct, namely these paths, as the basis for a branch and bound algorithm for the general-network problem. To generate the lower bounds, we create and solve a spanning-tree relaxation of the general-network problem. We provide a polynomial algorithm to solve these spanning tree problems. We perform a set of computational experiments to assess the performance of the general-network algorithm and to determine how to set various parameters for the algorithm. In addition to the general network case, we consider two-layer network problems. We develop a specialized branch and bound algorithm for these problems and show computationally that it is more efficient than the general-network algorithm applied to the two-layer networks.by Ekaterina Lesnaia.Ph.D

Implications of additive manufacturing on complexity management within supply chains in a production environment.

This dissertation focuses on developing a generic framework for using additive manufacturing as an appropriate production method to address the management of complexity in supply chains. While several drivers such as changing customer demand patterns and intensifying global competition increase product complexity, the available number of product variants and related processes within the supply chain itself increase costs and dilute scale effects. Several concepts and tools like mass customization, modularization, and product platforms have been developed in the past decades, but most of them focus on the product structure. Currently, there is no comprehensive tool set developed in the field of complexity management that incorporates all aspects of supply chain performance (costs, service, quality, and lead time) and evaluates the impacts of additive manufacturing to manage the complexity in the supply chain. This dissertation was developed primarily to address this research gap. The literature review in this dissertation provides in-depth reviews on specific topics in the field of additive manufacturing production technology, supply chain management, complexity management, and complexity management in supply chains through additive manufacturing. The dissertation presents the development of a framework for supply chain performance and complexity measurement with a focus on costs and performance depending on production technology. This framework will be the basis for measuring the impacts of additive manufacturing on supply chain performance and level of complexity, by using modeling and reconfiguring supply chain models, and applying complexity management tools in conjunction with additive manufacturing. Based on the findings, a generic framework is developed to identify when and how to apply additive manufacturing to enhance complexity management capabilities in supply chains. Two case studies will be used to show an application field, where additive manufacturing would require additional time, while another case study suggests the usage of additive manufacturing in the context of supply chain complexity: A case study of a control panel supply chain will provide an overview of the implications of substituting an injection molding production technology with an additive manufacturing technology on the supply chain and its complexity. Another case study of teeth aligners shows how additive manufacturing helps to improve supply chain complexity by substituting plaster tools with an additive manufacturing technology