A evolução da tecnologia da informação, tanto em hardware quanto em software, na última década, proporcionou ao mundo globalizado mudanças significativas na Gestão das organizações privadas e governamentais, permitindo a integração do fluxo de informações de operação ao fluxo de informações de gestão dos processos de produção, através de uma linguagem de programação específica como o CAD e CAM. Como resultado desse processo de evolução, a partir da década de 90, surgiram os Sistemas Integrados de Gestão (ERP - Enterprise Resource Planning) os quais passaram a incorporar os processos de negócio das empresas induzindo-as a mudanças significativas no ambiente de operação, desde os procedimentos mais simples até os mais complexos. É nesse contexto que pesquisadores e profissionais envolvidos com a implantação de tais sistemas constataram que o custo de aquisição, incluindo investimentos em inovações tecnológicas e treinamento, necessários à operação desses sistemas, por si só não garantiu o custo benefício e o retorno dos investimentos realizados, resultados esses não compatíveis com as expectativas geradas no período de implantação, causando em alguns casos perda de eficiência e frustração por parte dos usuários desses sistemas. Tal evidência induziu o autor do presente trabalho ao objetivo geral de elucidar as causas dos insucessos, partindo para a pesquisa descritiva de diferentes empresas, de segmentos distintos, que implantaram os sistemas ERP de diferentes fornecedores disponíveis no mercado. A pesquisa descritiva de campo permitiu esclarecer no âmbito de operação dessas empresas as suas peculiaridades quanto à estrutura do departamento de planejamento e controle da produção e sua integração com suas técnicas auxiliares. Nesse contexto foi possível avaliar a implantação desses sistemas pelas unidades produtivas pesquisadas que tiveram o objetivo de garantir ganhos significativos quanto à redução do tempo de resposta ao atendimento das necessidades dos clientes, com a possibilidade do apontamento de indicadores de desempenho mais precisos, direcionando a pesquisa para a avaliação do papel do PCP como agente facilitador do processo de implantação e como responsável pela aderência ou não desses sistemas ao sistema produtivo. Logo, um estudo mais aprofundado dos conceitos elucidados na literatura quanto aos tempos de processo e, conseqüentemente, aos tempos de resposta de todo o processo de fabricação, enfatizou a necessidade de se estudar a evolução do processo de manufatura ao longo das últimas décadas. A condução da pesquisa ao estudo das fases inerentes ao processo de evolução da manufatura nas últimas décadas, apontou para a divisão do processo de evolução em quatro fases: 1. Manufatura em Massa; 2. Manufatura Enxuta; 3. Manufatura Ágil; 4. Manufatura Responsiva. Nesse cenário, um dos objetivos específicos do trabalho é o de apontar as deficiências dos sistemas ERP em operação nas empresas que tiveram como meta reduções significativas de tempo de processo, com base no estudo das fases descritas, das técnicas auxiliares do PCP e da relação da função tempo com o contexto atual, além dos sistemas de gestão integrada. A revisão bibliográfica detalhada e cinco estudos de caso aqui apresentados formam o corpo deste trabalho. / The evolution of the technology of information, both in hardware and software, during the last decade, have provided to the globalized world significant changes in the Management of private and governmental organizations, allowing the integration of the flow of information of operation with the flow of information of production management processes, by means of specific programming language as CAD and CAM. As a result of this cycle of evolution, which started in the 90\'s, the ERP - Enterprise Resource Planning - was incorporated to the processes of business in companies leading them to significant changes in the operation environment, from the most simple to the most complex procedures. It is in this context that researchers and professionals, involved with the implantation of such systems, had evidenced that the acquisition cost, including investments in technological innovations and training so necessary to the systems operation, did not guarantee the cost benefits and the return of the investments. These results were not compatible with the expectations generated in the implantation period causing, in some cases, loss of efficiency and frustration on the part of the users of these systems. Such evidences lead the author of the present paper to the general objective of elucidating the causes of the failures. The work started from the descriptive research of different companies of distinct segments, which had implanted ERP systems of different available suppliers in the market. The descriptive field research allowed the clarifying of some peculiarities in the scope of operation of the companies as to the structure of their planning department and production control and the integration with supporting techniques. In this context it was possible to evaluate the implantation of these systems, in the considered productive units, which had aimed at guaranteeing significant profits as to the reduction of time of response to customer needs, with the possibility of pointing to more precise performance indicators, thus directing the research to the evaluation of the role of PCP as a facilitator agent in the implantation process and as a responsible one for the observance or not of these systems to the productive scheme. As a result, a broaden study of the concepts, focused on the specific literature, referring to the time of processing and, consequently, to the time of response of all the manufacturing procedures, emphasized the necessity of studying the evolution of the manufacturing process during the last decades. The conduction of the research to the study of inherent phases of the evolution process of manufacturing in the last decades, pointed to the division of the of evolution process in four phases: 1. Mass Manufacturing; 2. Lean Manufacturing (just in time); 3. Agile Manufacturing; 4. Responsive Manufacturing. In this scenario, one of the specific targets of this work is to spot the deficiencies of ERP systems currently in use in the companies which had as a goal significant reductions of processing time, based on the study of the mentioned paradigms, the PCP supporting techniques, and the relation of the function time with the current context, besides the systems of integrated management. The detailed bibliographical revision and five case studies, herein presented, compose the corpus of this work.

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

Ngo-Tai Fong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 158-168). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Manufacturing Systems: An Overview --- p.1 / Chapter 1.2 --- Previous Research --- p.3 / Chapter 1.3 --- Motivation --- p.5 / Chapter 1.4 --- Outline of the Thesis --- p.8 / Chapter 2 --- Preliminaries --- p.11 / Chapter 2.1 --- Problem Formulation: Deterministic Production Planning --- p.11 / Chapter 2.2 --- Markov Chain --- p.15 / Chapter 2.3 --- Problem Formulation: Stochastic Production Planning --- p.18 / Chapter 2.4 --- Some Lemmas --- p.24 / Chapter 3 --- Open-Loop Production Planning in Stochastic Flowshops --- p.26 / Chapter 3.1 --- Introduction --- p.26 / Chapter 3.2 --- Limiting Problem --- p.29 / Chapter 3.3 --- Weak-Lipschitz Continuity --- p.34 / Chapter 3.4 --- Constraint Domain Approximation --- p.41 / Chapter 3.5 --- Asymptotic Analysis: Initial States in Sε --- p.47 / Chapter 3.6 --- Asymptotic Analysis: Initial States in S \ Sε --- p.61 / Chapter 3.7 --- Concluding Remarks --- p.70 / Chapter 4 --- Feedback Production Planning in Deterministic Flowshops --- p.72 / Chapter 4.1 --- Introduction --- p.72 / Chapter 4.2 --- Assumptions --- p.75 / Chapter 4.3 --- Optimal Feedback Controls --- p.76 / Chapter 4.3.1 --- The Case c1 < c2+ --- p.78 / Chapter 4.3.2 --- The Case c1 ≥ c2+ --- p.83 / Chapter 4.4 --- Concluding Remarks --- p.88 / Chapter 5 --- Feedback Production Planning in Stochastic Flowshops --- p.90 / Chapter 5.1 --- Introduction --- p.90 / Chapter 5.2 --- Original and Limiting Problems --- p.91 / Chapter 5.3 --- Asymptotic Optimal Feedback Controls for pε --- p.97 / Chapter 5.3.1 --- The Case c1 < c2+ --- p.97 / Chapter 5.3.2 --- The Case c1 ≥ c2+ --- p.118 / Chapter 5.4 --- Concluding Remarks --- p.124 / Chapter 6 --- Computational Evaluation of Hierarchical Controls --- p.126 / Chapter 6.1 --- Introduction --- p.126 / Chapter 6.2 --- The Problem and Control Policies under Consideration --- p.128 / Chapter 6.2.1 --- The Problem --- p.128 / Chapter 6.2.2 --- Hierarchical Control (HC) --- p.131 / Chapter 6.2.3 --- Kanban Control (KC) --- p.133 / Chapter 6.2.4 --- Two-Boundary Control (TBC) --- p.137 / Chapter 6.2.5 --- "Similarities and Differences between HC, KC, and TBC" --- p.141 / Chapter 6.3 --- Computational Results --- p.142 / Chapter 6.4 --- Comparison of HC with Other Polices --- p.145 / Chapter 6.5 --- Concluding Remarks --- p.151 / Chapter 7 --- Conclusions and Future Research --- p.153 / Bibliography --- p.158

by Chu Kwok-Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 91-93). / Abstracts in English and Chinese. / List of Figures --- p.vii / List of Tables --- p.viii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Literature Review --- p.4 / Chapter 1.2.1 --- Ordinary Dispatching Policies --- p.5 / Chapter 1.2.2 --- Setup-oriented Dispatching Policies --- p.7 / Chapter 1.3 --- Organization of Thesis --- p.10 / Chapter 2 --- Slack Based Policies --- p.11 / Chapter 2.1 --- Definition of Slack --- p.12 / Chapter 2.2 --- Least Slack Policy (LS) --- p.13 / Chapter 2.3 --- Least Weighted Slack Policy (LWS) --- p.15 / Chapter 2.3.1 --- Definition of Weighted Slack --- p.15 / Chapter 2.3.2 --- Policy Mechanism and Discussion --- p.15 / Chapter 2.4 --- Least Mean Slack Policy (LMS) --- p.16 / Chapter 2.4.1 --- Batch Size and Its Lower Bound --- p.16 / Chapter 2.4.2 --- Policy Mechanism and Discussion --- p.17 / Chapter 2.5 --- Least Weighted Mean Slack Policy (LWMS) --- p.18 / Chapter 2.5.1 --- Definition of Weighted Mean Slack --- p.18 / Chapter 2.5.2 --- Policy Mechanism and Discussion --- p.18 / Chapter 2.6 --- Illustrative Example --- p.21 / Chapter 2.7 --- Due-date Window Expansion --- p.24 / Chapter 2.7.1 --- Due-date Window --- p.24 / Chapter 2.7.2 --- LWMS Policy: Due Date Window Expansion --- p.25 / Chapter 3 --- Simulation Study --- p.27 / Chapter 3.1 --- Models Description --- p.27 / Chapter 3.1.1 --- Two-Machines-Two-Products Model --- p.27 / Chapter 3.1.2 --- Assembly Lines Model --- p.29 / Chapter 3.1.3 --- Micro-Chips Testing Model --- p.31 / Chapter 3.2 --- Simulation Experiment Description --- p.32 / Chapter 4 --- Simulation Result and Analysis --- p.38 / Chapter 4.1 --- Simulation Result --- p.39 / Chapter 4.1.1 --- Two-Machines-Two-Products Model --- p.39 / Chapter 4.1.2 --- Assembly Lines Model --- p.39 / Chapter 4.1.3 --- Micro-Chips Testing Model --- p.43 / Chapter 4.2 --- Statistical Analysis --- p.44 / Chapter 4.2.1 --- Significance of Weighted Factor and Batch Size --- p.44 / Chapter 4.2.2 --- Comparison Among Different Policies --- p.46 / Chapter 4.3 --- Discussion of Results --- p.50 / Chapter 5 --- An Experimental Implementation and Conclusion Remarks --- p.51 / Chapter A --- Reducing MCT and SDCT by LS policy --- p.55 / Chapter A.1 --- Reducing Variance of Lateness --- p.55 / Chapter A.2 --- Reducing Variance of Cycle Time --- p.56 / Chapter A.3 --- Reducing Mean Cycle Time --- p.56 / Chapter B --- Complete Simulation Result --- p.58 / Chapter B.1 --- Two-Machines-Two-Products Model --- p.58 / Chapter B.1.1 --- "Wip, Batch Size and Throughput" --- p.58 / Chapter B.1.2 --- MCT and SDCT --- p.62 / Chapter B.1.3 --- Machine Utilization --- p.66 / Chapter B.2 --- Assembly Lines Model --- p.68 / Chapter B.2.1 --- "WIP, Batch Size and Throughput" --- p.68 / Chapter B.2.2 --- MCT and SDCT --- p.70 / Chapter B.2.3 --- Machine Utilization --- p.73 / Chapter B.3 --- Micro-Chips Testing Model --- p.82 / Chapter B.3.1 --- "WIP, Throughput, MCT and SDCT" --- p.82 / Chapter B.3.2 --- Machine Utilization --- p.84 / Chapter C --- MANOVA studies on Weighted Factor and Batch Size --- p.86 / Chapter C.1 --- Two-Machines-Two-Products Model --- p.86 / Chapter C.1.1 --- Least Weighted Slack Policy --- p.86 / Chapter C.1.2 --- Least Mean Slack Policy --- p.87 / Chapter C.1.3 --- Least Weighted Mean Slack Policy --- p.87 / Chapter C.2 --- Assembly Lines Model --- p.88 / Chapter C.2.1 --- Least Weighted Slack Policy --- p.88 / Chapter C.2.2 --- Least Mean Slack Policy --- p.88 / Chapter C.2.3 --- Least Weighted Mean Slack Policy --- p.89 / Chapter C.3 --- Micro-Chips Testing Model --- p.89 / Chapter C.3.1 --- Least Weighted Slack Policy --- p.89 / Chapter C.3.2 --- Least Mean Slack Policy --- p.90 / Chapter C.3.3 --- Least Weighted Mean Slack Policy --- p.90 / Bibliography --- p.91

O controle de perdas tem sido apontado como uma das principais estratégias para melhoria do desempenho e para redução de custos de sistemas de produção. Entretanto, apesar de sua importância, este é um tema pouco abordado na literatura sobre gestão da construção, principalmente no que se refere a sistemas de controle da produção. Alguns estudos recentes chamaram a atenção para a existência de uma perda típica do setor, denominada de making-do, a qual pode ser definida como a redução de desempenho do sistema produtivo devido à execução de atividades em condições subótimas. Este tipo de perda ainda tem sido apontada como uma das causas fundamentais de problemas da qualidade, e de outras perdas, tais como retrabalho e trabalho em progresso. Falhas na análise de restrições realizadas no planejamento de médio prazo têm sido apontadas como a principal razão para o surgimento de perdas por making-do, pois na ausência dos requisitos necessários para execução das atividades normalmente as equipes realizam improvisações, que podem afetar o desempenho da produção. O presente trabalho propõe um método de controle integrado produção e qualidade que permita mensurar perdas por making-do e também a ocorrência de pacotes de trabalho informais. Este método está dividido em três módulos: (a) identificação de perdas por making-do; (b) identificação de pacotes informais; e (c) controle integrado produção e qualidade. O desenvolvimento da pesquisa foi dividido nas seguintes etapas: (a) compreensão do problema; (b) estruturação do método; (c) consolidação do método; (d) avaliação dos resultados e proposição do método final. Como principais contribuições do trabalho, além do próprio método proposto, o estudo propõe uma conceitualização de perdas por making-do, retrabalho e falta de terminalidade. Ainda, os resultados demonstram a existência de uma forte relação entre as perdas por making-do, a execução de pacotes informais e o aumento do trabalho em progresso. / Waste control has been pointed out as one of the key strategies for improving the performance and reducing costs of production systems. However, despite its importance, this is a topic poorly discussed in the construction management literature, especially in relation to production control systems. Some recent studies have called the attention for a type of waste that is typical of the construction sector, named making-do, which can be defined as a loss in performance due to the execution of activities in sub-optimal conditions. It has been suggested that this type of waste is one of the root causes of quality failures, and also of other types of waste, such as rework and work in progress. Failures in constraint analysis at the medium term planning level have been pointed out a major cause of makingdo waste, as the crews tend to improvise when faced with the lack of prerequisites for the execution of tasks, which may affect the production performance. This research work proposes a method for integrated production and quality control, which enables the measurement making-do waste and also the occurrence of informal work packages This method is divided into three modules: (a) identification of making-do waste; (b) identification of informal work packages; and (c) integrated and production and quality control. The development of this research work was divided into the following stages: (a) understanding the problem; (b) structuring the method; (c) consolidating the method; (d) evaluation of results and proposition of the final version of the method. As main contributions, besides the integrated control method, this investigation proposes a conceptualization for three categories of waste: making-do, rework, and unfinished work. Moreover, the results indicate that there is a strong relationship making-do waste, the execution of informal packages and the increase of work in progress.

Submitted by admin tede (tede@pucgoias.edu.br) on 2017-10-09T12:07:31Z No. of bitstreams: 1 Bianca Marcelo Mamede.pdf: 2670645 bytes, checksum: da945ec531f92927e420ca490396ffed (MD5) / Made available in DSpace on 2017-10-09T12:07:31Z (GMT). No. of bitstreams: 1 Bianca Marcelo Mamede.pdf: 2670645 bytes, checksum: da945ec531f92927e420ca490396ffed (MD5) Previous issue date: 2017-05-18 / The CONWIP production management method overcomes in productive systems because it eliminates waste and enhances the productive process’ performance. Maketo- stock production systems need to reduce stocks in order to enhance the performance of their productive processes. However, the application of CONWIP is sparse in MTS systems industrial reality. Hence a research has been done, through computational simulations and modelling methodology, with the aim to compare the operational results of a real productive MTS system with the results that a CONWIP method managed system would generate. The CONWIP hás held the demand by reducing the excess production presented by MTS, using 71% less inputs and reducing the processing stocks (WIP) by 85%. Considering the Factory Physics laws, the CONWIP performance was better when compared to MTS for enhancing the resources usage, reducing the processing time variability and eliminating the waste. This work hás contributed to reduce CONWIP performance analysis through computational simulation and modelling studies absence in literature. / O método de gerenciamento da produção CONWIP sobresai em sistemas produtivos jobbing por eliminar desperdícios e aprimorar o desempenho do processo produtivo. Sistemas de produção make-to-stock (MTS) necessitam reduzir estoques de modo a aprimorar o desempenho de seus processos produtivos. Entretanto a aplicação do CONWIP é escassa na realidade industrial de sistemas MTS. Nesse contexto foi realizada uma pesquisa, através da metodologia de modelagem e simulação computacional, com o objetivo de comparar os resultados operacionais de um sistema produtivo MTS real com os resultados que geraria ao ser gerenciado pelo método CONWIP. O CONWIP atendeu a demanda reduzindo a produção em excesso apresentada pelo MTS, utilizando 71% menos insumos e reduzindo o nível de estoques em processo (WIP) em 85%. Considerando as leis da Ciência da Fábrica o desempenho do CONWIP foi melhor, comparado ao MTS por ter aprimorado a utilização dos recursos, reduzido a variabilidade dos tempos de processamento e eliminado desperdícios. Este trabalho contribuiu para diminuir a ausência de estudos na literatura com análises do desempenho do CONWIP através da modelagem e simulação computacional.

Chen, Jiayi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 86-94). / Abstract also in Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Introduction --- p.1 / Chapter 1.1 --- Introduction to the Capacitated Lot Sizing (CLS )problem --- p.1 / Chapter 1.2 --- Our contributions --- p.2 / Chapter 1.3 --- Organization of the thesis --- p.4 / Literature Review --- p.5 / Chapter 2.1 --- Research in CLS problem --- p.5 / Chapter 2.1.1 --- Reviews in CLS problems --- p.8 / Chapter 2.1.2 --- Approaches and methods to solve the traditional CLS problems --- p.9 / Chapter 2.1.3 --- Research on Fixed-Charge-Transportation-typed models for CLS problems --- p.13 / Chapter 2.2 --- Research in Genetic Algorithm (GA) --- p.15 / Chapter 2.3 --- Conclusion --- p.17 / Problem Description and Formulation --- p.18 / Chapter 3.1 --- The formulation --- p.18 / Chapter 3.2 --- Comparison with the traditional formulation --- p.24 / Chapter 3.3 --- Conclusion --- p.28 / Description of the Heuristic --- p.29 / Chapter 4.1 --- Initialization --- p.32 / Chapter 4.1.1 --- Setup string generation --- p.32 / Chapter 4.1.2 --- Transportation problem --- p.35 / Chapter 4.1.3 --- Consistency test --- p.47 / Chapter 4.2 --- Selection --- p.50 / Chapter 4.3 --- Crossover --- p.50 / Chapter 4.4 --- Mutation --- p.52 / Chapter 4.5 --- Evaluation --- p.53 / Chapter 4.6 --- Termination --- p.54 / Chapter 4.7 --- Conclusion --- p.54 / Design of Experiments and Computational Results --- p.56 / Chapter 5.1 --- Design of experiments --- p.57 / Chapter 5.2 --- Discussion of lower bound procedures --- p.63 / Chapter 5.3 --- Computational results --- p.65 / Chapter 5.3.1 --- CLS problems with setup times --- p.65 / Chapter 5.3.2 --- CLS problems without setup times --- p.77 / Chapter 5.4 --- Conclusion --- p.82 / Conclusion --- p.83 / Bibliography --- p.86

El presente proyecto de investigación se basa en la búsqueda de la mejora continua en el proceso de planeamiento y control de la producción en una empresa de la industria metalmecánica del Perú la cual ha ido creciendo rápidamente. Sin embargo, debido a los constantes cambios del mercado, se identifica que la demanda actual que maneja este sector es flexible. Para el cumplimiento de dicha demanda, las empresas han tenido que realizar una reestructuración del método de fabricación de sus productos. Sin embargo, algunas empresas aún siguen trabajando con el mismo método de fabricación para el cumplimiento de demanda constante. Un ejemplo, es la empresa Metalurgia del Fierro y del Cobre S.R. L. El problema actual que la empresa presenta es el incremento de pedidos atrasados, causando así una baja facturación durante el mes. Para la solución, se analizó que la causa principal es la mala planificación de la producción, debido a que la empresa no ha tenido un análisis previo de la demanda durante los años anteriores, esto tiene como causas que la parte operativa de la empresa tenga tiempos no estandarizados, constantes paradas de máquinas y la falta de stock de insumos. Para la solución de estas causas se propone las siguientes metodologías: Desarrollo de pronósticos basados la herramienta de suavización exponencial doble y la creación de un sistema de planificación y control de la producción bajo pedido y proponiendo la incorporación de nuevos procedimientos basados en la herramienta MRP II. / This research project is based on the search for continuous improvement in the process of planning and control of production in a company of the metalworking industry in Peru, which has been growing rapidly. However, due to the constant market changes, the current demand that manages this sector is flexible. To meet this demand, companies have had to restructure the manufacturing method of their products. However, some companies are still working with the same manufacturing method to meet constant demand. For example, it is the company Metalurgia del Fierro y del Cobre S.R. L. The current problem that the company presents is the increase in backorders, thus causing low turnover during the month. For the solution, the main cause was analyzed is the poor production planning, because the company has not had a previous analysis of the demand during the previous years, this has as causes that the operational part of the company has times not Standardized, constant machine shutdowns and lack of stock of inputs. For the solution of these causes, the following methodologies are proposed: Development of the specified double exponential smoothing method and the creation of a planning and control production system and proposing the incorporation of new specific procedures in the MRP II tool. / Tesis

The principal objective of this study was to investigate process simulation and optimization of an existing offshore natural gas process which needed profitability improvements. Optimization was done using two alternative approaches: a global approach (response surface methodology) or a local approach (successive quadratic programming). The global approach was characterized by process performance at selected case study points throughout the feasible operating region and made use of global information, while the local approach was characterized by numerical iterative computation driven by local information in the neighborhood of a single point in the design space. A Box-Behnken design was used as a second-order response surface design for the estimation of correlation between process simulator design variables and an economic objective function, and the estimation model was then optimized. In the local approach, a process simulator (ASPEN PLUS) with optimization capabilities was used. From the investigation, three major design variables were identified that had significant effects on the objective function of maximum product sales value. The three variables were: the compression ratio of the Production Compressor, the heat duty of the Gas/Gas Exchanger, and the compression ratio of the Expander. The results indicated that profitability of the offshore natural gas process could be improved by greatly (about 60%) increasing the production of raw condensate, even though this meant slightly lower (about 4%) sales of natural gas as a main product. The improvement found, however, was only 7% when the design variables were limited by currently installed equipment. The global approach was found to converge more consistently because once the global quadratic model was calculated, convergence to its unique optimum was simple. On the other hand the local approach had non-unique termination points due to the small effects of some design variables. The global approach provided better engineering insight since the effects of each design variable could be easily calculated from the quadratic model. However, the global approach was less efficient in terms of engineering manpower because of the time required to identify the quadratic model. / Graduation date: 1995

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