published_or_final_version / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy

by Ng So-ying Gloria. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1982

退貨産品在國民經濟中發揮重要作用，近些年來在工業界和學術界引起廣泛關注。由于受到退貨産品的巨大經濟潛能驅動以及迫于相關法律的強大壓力，企業開始積極整合現有供應鏈流程和産品退貨流程，但是在這個過程中生産計劃和庫存管理運營遇到了前所未有的挑戰。本論文分析了可修護單壹産品的多周期庫存系統管理問題，其中該庫存系統包含隨機的新産品需求和産品保修需求。所探討的系統還包含了以下特征： i. 産品供應源的完美替換。新訂購産品和維修後的退貨産品並無二異。ii. 需求優先級。在單個周期內，新産品需求優先級高于保修需求。iii. 新産品訂購和退貨産品維修特性。兩項流程交付時間都假設爲零。在每個周期中，維修退貨産品過程涉及且考慮維修損失。我們探尋到了所考察系統的最優庫存補貨和處理控制策略。 / Product returns play an important role in the economy and have attracted more and more attention both from industry and academia in the past few years. Motivated by enormous economic potential of and dramatic legislation pressure on product returns, companies today actively integrate product-return processes with their existing forward supply-chain processes, but must confront the considerable challenge of production planning and inventory control problems compared to traditional problems without returns and repairs. / This thesis analyzes a multi-period single-item repairable inventory system with stochastic new and warranty demands. The system investigated has the following features: i. perfect substitution of supply sources. Newly-procured items are indistinguishable from items repaired from repairable warranty returns. ii. demand priority. New demand has higher priority than warranty demand within a period and thus needs to be satisfied first. iii. properties on the processes of purchasing and repairing. We assume zero lead-time for both processes. Further we capture the "repair loss" in repairing returns in each period. We identify the optimal inventory replenishment and disposal policies for the investigated system. / Detailed summary in vernacular field only. / Lin, Yizhong. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 80-87). / Abstracts also in Chinese.

published_or_final_version / abstract / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy

by Lo Kin Wing, Andy. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leave 60). / ABSTRACT --- p.iii / TABLE OF CONTENT --- p.iv / CHAPTER / Chapter I --- INTRODUCTION --- p.1 / Chapter II --- RESEARCH OBJECTIVES AND METHODOLOGY --- p.4 / Chapter III --- IMPORTANCE OF TRIMS MANAGEMENT SYSTEM IN GARMENT MANUFACUTRING --- p.10 / Chapter IV --- CURRENT TRIMS MANAGEMENT SYSTEM --- p.19 / Chapter V --- PROPOSED TRIMS MANAGEMENT SYSTEM --- p.32 / Chapter VI --- COST / BENEFIT ANALYSIS --- p.40 / APPENDIX / PROPOSED DATA FLOW DIAGRAM --- p.44 / FILE LAYOUT --- p.45 / BIBlLIOGRAPHY --- p.60

The objective of this research project was to identify the limitations associated with schedule-based Material Requirements Planning (SBMRP) and to present a knowledge-based expert system (KBES) approach to solve these problems. In SBMRP, the basic strategy is to use backward or forward scheduling based on an arbitrary dispatching rule, such as First-In First-Out. One of the SBMRP weak points is that it does not use such job information as slack times, due dates, and processing times, information which otherwise is important to good scheduling decisions. In addition, the backward scheduling method produces a better schedule than the forward scheduling method in terms of holding and late costs. Dependent upon job characteristics, this may or may not be true and should be tested. This study focused on the means to overcome these two weak points by the use of a KBES. Heuristic rules were developed through an experiment-based knowledge acquisition process to generate better schedules, rather than relying solely upon forward or backward scheduling. Scheduling performance was measured, based on the minimization of the sums of holding and late costs. Due to complexities of the problem, heuristic methods were used rather than analytic methods. In particular, five loading rules were selected, based upon their close relationship to selected job characteristics, including processing times and due dates. Combined loading methods (CLMs) were developed to obtain better performance, derived by combining the two existing SBMRP scheduling strategies with five loading heuristic rules. This resulted in the generation of 10 CLMs for further evaluation. Since this study proposed a new approach, an expert human scheduler was not available. To overcome this problem, knowledge acqusition through computer experimentation (KACE) was utilized, based upon an architecture of five components: job generator, scheduler, evaluator, rule generator (an extended version of ID3), and the KBES. The first three components were used to generate a large number of examples required by the rule generator to derive knowledge. This derived knowledge was incorporated into the KBES. Experimental results indicated that the KBES outperformed the two existing SBMRP methods. Based on sensitivity analysis, the KBES exhibited robust performance with regard to every job parameter except number of parts. As the number of parts was increased, KBES performance was subject to degradation since the possibility of interactions or conflicts between parts tended to increase, resulting in shifting the threshold ratio of total available time to total processing time. Thus, it is strongly recommended that a new KBES capable of accommodating 30 parts or more should be developed using the KACE method. / Graduation date: 1991

Presently there is a trend in manufacturing system design from stand-alone, automatic operations to Computer Integrated Manufacturing (CIM). The success of the integration depends largely on the performance of system control software. This document presents research in the design and implementation of a shop control system, for a CIM facility, using a new method called the three-layer integrated approach. Two basic techniques used in this research are expert systems and object-oriented programming. The CIM system at VPI is an automated manufacturing and assembly system. In designing the control system for this CIM facility, the design of products, production facilities, and overall system must be taken into account. In order to manage this complex system, a control system called the “shop controller” has been developed using C++, an object-oriented programming language. In addition, three real-time simulators for the cell controllers have been developed for testing and debugging the production rules of the expert system. The basic approach taken for the shop control system has several advantages: applied intelligence, program efficiency, reusability of code, and ease of maintenance. Moreover, this approach has a new feature—modularity, which is the result of combining expert systems and object-oriented programming. / Master of Science

Thesis. 1979. Ph.D.--Massachusetts Institute of Technology. Alfred P. Sloan School of Management. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY / Bibliography: p. 336-338. / Ph.D.