Order fulfillment in online retailing : what goes where

Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2005.Includes bibliographical references (p. 139-146).We present three problems motivated by order fulfillment in online retailing. First, we focus on one warehouse or fulfillment center. To optimize the storage space and labor, an e-tailer splits the warehouse into two regions with different storage densities. One is for picking customer orders and the other to hold a reserve stock that replenishes the picking area. Consequently, the warehouse is a two-stage serial system. We investigate an inventory system where demand is stochastic by minimizing the total expected inventory- related costs subject to a space constraint. We develop an approximate model for a periodic review, nested ordering policy. Furthermore, we extend the formulation to account for shipping delays and advance order information. We report on tests of the model with data from a major e-tailer. Second, we focus on the entire network of warehouses and customers. When a customer order occurs, the e-tailer assigns the order to one or more of its warehouses and/or drop- shippers, so as to minimize procurement and transportation costs, based on the available current information. However, this assignment is necessarily myopic as it cannot account for any subsequent customer orders or future inventory replenishments.(cont.) We examine the benefits from periodically re-evaluating these real-time assignments. We construct near- optimal heuristics for the re-assignment for a large set of customer orders by minimizing the total number of shipments. Finally, we present saving opportunities by testing the heuristics on order data from a major e-tailer. Third, we focus on the inventory allocation among warehouses for low-demand SKUs. A large e-tailer strategically stocks inventory for SKUs with low demand. The motivations are to provide a wide range of selections and faster customer fulfillment service. We assume the e-tailer has the technological capability to manage and control the inventory globally: all warehouses act as one to serve the global demand simultaneously. The e-tailer will utilize its entire inventory, regardless of location, to serve demand. Given we stock certain units of system inventory, we allocate inventory to warehouses by minimizing outbound transportation costs. We analyze a few simple cases and present a methodology for more general problems.by Ping Josephine Xu.Ph.D

Supply Chain

Traditionally supply chain management has meant factories, assembly lines, warehouses, transportation vehicles, and time sheets. Modern supply chain management is a highly complex, multidimensional problem set with virtually endless number of variables for optimization. An Internet enabled supply chain may have just-in-time delivery, precise inventory visibility, and up-to-the-minute distribution-tracking capabilities. Technology advances have enabled supply chains to become strategic weapons that can help avoid disasters, lower costs, and make money. From internal enterprise processes to external business transactions with suppliers, transporters, channels and end-users marks the wide range of challenges researchers have to handle. The aim of this book is at revealing and illustrating this diversity in terms of scientific and theoretical fundamentals, prevailing concepts as well as current practical applications

Analysis and design of manufacturing systems with multiple-loop structures

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 281-284).Kanban means card or token. A kanban-controlled production system is one where the flow of material is controlled by the presence or absence of a kanban, and where kanbans travel in the system according to certain rules. The study of kanban-controlled production systems can be traced back to the Toyota Production System in the 1950s. The classic kanban-controlled system was designed to realize Just-In-Time (JIT) production. Kanban-controlled production systems, though pervasively used in industry and studied for decades, are not well understood quantitatively yet. The essence of kanban-controlled production systems is to use single or multiple closed loops to provide information flow feedback using kanbans. By doing this, the systems keep tight controls over inventory levels, while providing satisfactory production rates. The goal of this research is to study the behavior of the class of manufacturing systems with multiple closed loop structures and explore the applications in design and operational control of production systems using multiple-kanban loops. To do so, stochastic mathematical models and effcient analytical methods for evaluating the performance of systems with complex structures are required.(cont.) In this thesis, we present an assembly/disassembly network model which integrates the control information flows with material flows. Blocking and starvation properties due to machine failures in a system are analyzed by establishing an effcient underlying graph model of the system. Based on the mathematical model and blocking and starvation properties, effcient and accurate algorithms are developed for evaluating the performance of systems with arbitrary multiple-loop structures. We study the behavior of multiple-loop structures and develop intuition for optimal design and operational control using multiple-kanban loops. Some practical guidelines for the design and control of production systems using multiple-kanban loops are provided at the end.by Zhenyu Zhang.Ph.D

Optimal Reconfiguration of Complex Production Lines for Profit Maximization via Simulation Modeling

With the recent trend of re-shoring, transferring manufacturing systems from a workforce-intensive to a capital-intensive production environment becomes more common. One challenge multinational manufacturing companies may face in such an endeavor is reconfiguration of the transferred manufacturing system according to the availability of better machinery in the capital-intensive environment. In this dissertation, based on a real-life problem, I develop several simulation optimization methods for the problem of production line reconfiguration. The case is a reverse transfer of manufacturing system/technology, i.e. transfer from a workforce-intensive environment to a capital-intensive one. I investigate the performances of nine different simulation optimization approaches based on the real-life case in automotive industry to illustrate their relative strengths under different parameter scenarios. I also create a test-bed problem to determine the specifications of these methods, and further analyze their performances. Numerical results may guide the practitioners facing similar challenges in choosing a suitable solution approach depending on the problem size and solution time availability

Analysis and Preliminary Design of an Advanced Technology Transport Flight Control System

The analysis and preliminary design of an advanced technology transport aircraft flight control system using avionics and flight control concepts appropriate to the 1980-1985 time period are discussed. Specifically, the techniques and requirements of the flight control system were established, a number of candidate configurations were defined, and an evaluation of these configurations was performed to establish a recommended approach. Candidate configurations based on redundant integration of various sensor types, computational methods, servo actuator arrangements and data-transfer techniques were defined to the functional module and piece-part level. Life-cycle costs, for the flight control configurations, as determined in an operational environment model for 200 aircraft over a 15-year service life, were the basis of the optimum configuration selection tradeoff. The recommended system concept is a quad digital computer configuration utilizing a small microprocessor for input/output control, a hexad skewed set of conventional sensors for body rate and body acceleration, and triple integrated actuators

Truth, objectivity and subjectivity in accounting

The central thesis defended here is that we can have truth and objectivity in accounting. We do not contend that this potential is presently realized: On the contrary, we argue that certain contradictions immanent to capitalism give rise in late modernity to crisis tendencies in financial accounting as a way of knowing - epistemological crisis. We do contend that accounting's tendencies to epistemological crises can, at least in theory, be overcome. We begin to defend this view by considering accounting as an essentially descriptive activity. The account given by the philosopher Donald Davidson of the very possibility of knowledge is used to justify the view that intersubjectivity is all the foundation we need, or can have, for objectivity, and to defend out claim that we can have accounting knowledge, that is, true accounts/descriptions of an objective and intersubjectively accessible public world. The defence here is against those theorists, including those inspired by certain strands of the phenomenological, (post)structuralist and hermeneutic traditions, who would deny the possibility of any such objectivity in accounting. Using an analysis of the history and debate surrounding the issue of accounting for deferred tax in the United Kingdom (UK), we endeavour to locate accounting in terms of the dichotomy the philosopher Bernard Williams draws between science and ethics. We find that the descriptive and normative are inextricably entangled in accounting concepts in much the same way as they are entangled in thick ethical concepts such as 'chastity' or 'courage'. We recognise that the descriptive aspect of accounting can not be neatly distinguished from the normative and dealt with separately. Furthermore, following Williams, we argue that difficulties associated with the objective validation of the normative dimension of thick accounting concepts renders knowledge held under them vulnerable to destruction by reflection

A Bayesian Audit Assurance Model with Application to the Component Materiality Problem in Group Audits

Groot, T.L.C.M. [Promotor

Earth resources technology satellite operations control center and data processing facility. Book 2 - Systems studies Final report

Systems analysis for ERTS NASA Data Processing Facility system and subsystem