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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Integrated knowledge-based hierarchical modelling of manufacturing organizations

Jiao, Hong January 1991 (has links)
The objective of this thesis is to research into an integrated knowledge-based simulation method, which combines the capability of knowledge based simulation and a structured analysis method, for the design and analysis of complex and hierarchical manufacturing organizations. This means manufacturing organizations analysed according to this methodology can manage the tactical and operational planning as well as the direct operation of shop floor.
2

Grid reliability assessment for short-term planning

Dogan, Gamze 10 September 2018 (has links) (PDF)
With the increasing amount of renewable and difficult-to-forecast generation units, Transmission System Operators (TSO) face new challenges to operate the grid properly. The deterministic N-1 criterion is currently used to assess grid reliability. This criterion states that the loss of an active component should not trigger the violation of operational constraints. It has been chosen in the conventional context of electricity in which large units produced power transmitted to the consumer through the transmission and the distribution systems. The renewable energy sources, the distributed generations, and the liberalization of the electricity market led to a revolution in power systems. Renewable energies present intrinsic variability and limited predictability. Those variables are thus subject to forecasting errors. Distributed generations changed the structure of the power system to include smaller productions dispersed in the grid. The competitive electricity market led the consumers to react to electricity prices. The load is thus now subject to higher forecasting errors. An increasing share of the power system’s variables is thus now subject to errors that are likely to affect the operations and the planning of the grid. The N-1 criterion reaches limitations in considering the new characteristics of the power system. To account for this evolution, TSOs have to make a shift in paradigm. They must go from the N-1 criterion to a reliability-based approach, with risk management and integration of errors on forecasted values. This amounts to going from deterministic to probabilistic approaches capable of quantifying this risk.The purpose of this research project is to develop the basis of an industrial tool. The method considers thus the barriers to the use of a probabilistic method for grid planning. TSOs are indeed reluctant to give up the N-1 criterion. They fear that a probabilistic method would be too difficult to understand and apply and that the related computational time would be too long for the operational planning.The method proposed in this research project aims at overcoming those barriers. The method sets the basis of a decision support tool for the planners to make sound decisions. It is thus not a black-box and the planners are included in the assessment. The method is based on the current work of the planners and widens it to englobe probabilistic considerations. It offers thus a smooth evolution from a deterministic to a probabilistic method which will ease the industrial development of the tool using it. The method is called Discrete Forecast ERrors Scenarios method: DIFERS. It has been developed to be consistent with the operational planning in terms of time constraints and available information. It relies on three evolutions from the deterministic N-1 criterion: 1. Include possible variations from the best estimate of the forecasts.2. Enlarge the contingency list to higher N-k events.3. Consider the impact and the probability of the events to compute their risk.The contingency list evolves thus toward a risk-based classification of events. The planners’ work aims then at proposing actions to decrease the risk to an acceptable level. The first step of DIFERS is performed off-line to relax the time constraints. It aims at evaluating the contingency list for a set of situations. It performs an assessment on the most probable events, considering a larger group than the N-1 criterion. The assessment focuses on N-1 and nearby N-2 events. The nearby events have been selected based on a distance criterion defined in terms of number of components in the smallest path from one component to another. Some random N-3 and N-4 events are also analyzed to assess the evolution of the risk with regard to the number of failing components. Continuous variables are represented by their probability density functions (PDFs), which represent the variation range for the set of situations considered. Those PDFs are discretized to limit the computational time. The assessment of the contingencies is performed on each combination of those discrete points. The second step uses the contingency list developed in step 1 to assess the risk related to a specific situation: a grid plan. The PDFs used in this step represent the forecasting errors on the continuous variables for the grid plan considered. They are also discretized and each combination is tested with the events of the contingency list. At the end of the assessment, indicators are computed and provided to the planner. The planner can then propose actions to be tested by the tool to see their impact on the reliability indicators. The assessment stops once the reliability target is met.The final step aims at updating the information computed in step 2 with newly acquired forecasts. As real-time is closer, those forecasts are more reliable. The method has been tested on a plausible scenario and on a simplified version of the Belgian grid. The load and the offshore wind production have been considered as input variables for this implementations. The results show that there is an interest in evolving toward a risk-based assessment to capture the new characteristics of the evolving context of electricity supply. The implementation of the DIFERS method should continue on several scenarios. It should integrate all continuous variables such as solar and onshore productions. Moreover, all real-life considerations on the input variables, such as correlations, should be included to represent the power system as best as possible.This research project has been conducted in collaboration with the Belgian TSO Elia and it has been financed by the Doctiris grant of Innoviris. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished
3

Controlling / Controlling

Murza, Jozef January 2010 (has links)
Enterprise-wide planning process, comparing the plan with reality, evaluating deviations and reporting are the most important aspects of corporate governance in the current period. Controller assigned irreplaceable function of initiator, coordinator and methodology in the entire planning process. Part of planning is the preparation of operational plans and budgets, which are the central theme of this work. This work covers applications controlling methods and tools for portfolio of managed projects (companies providing rental of commercial space). The nature and importance of controlling, controlling selected methods and analysis is explained in the theoretical part. In the second, practical part was, after the analysis of costs and revenues, prepared a model of corporate budget and its component parts
4

Analýza faktorů úspěšnosti podniku / Analysis of factors critical to the success of a company

Němeček, Přemysl January 2011 (has links)
Growing competitiveness in energy sector, uncertainty about economic growth and increasing regulation all lead to diminishing growing potential for a energy company. It is a challenge for business management and business planning to search, create and explore company's potential. Therefore planning process in the studied energy company E.ON is analysed as a management tool for implementation of company strategy. The strategy itself is analysed in order to evaluate mid-term planning in E.ON. The subplans, financial indicators and key performance indicators are evaluated. New system of key performance indicators is designed.
5

A Study of Operational Planning for Assistive Technology Platform

Yu, Yen-hsing 17 August 2011 (has links)
For persons with disabilities, their impairments lead to many inconveniences in their daily life. Luckily, assistive technology devices can help compensate functional limitations and enable them to participate in the activities of daily life. In 2010, there were 126,693 disabilities in the Kaohsiung area. Subsidies provided by Kaohsiung city government and Kaohsiung county government reach respectively NT$39,145,000 and NT$ 25,489,000 in 2010. Nevertheless, such great amount of money invested does not work as it has been expected. There appear to remain a number of barriers. One such example would be that persons with disabilities lack the knowledge about assistive technology, so they do not know where to ask for help in the first place. On the other hand, lack of consideration for the needs of a person with disability result in them getting inappropriate assistive technology devices. These problems deserve the attention of government and related associations. This research aims to solve the problems between the supply and demand of assistive technology devices or services. It reviews and studies papers concerning the same issue in an attempt to create a new service platform. This platform is created according to information and suggestion gathered from experts of this field and voice from users of assistive devices. Their voices and assessments provide valuable direction to shape this new platform. This research assesses the possibility of this new assistive technology service platform from several aspects, including its political, legislative, supplying, and demanding dimensions. The purpose of this study is to reorganize diverse resources to provide a more convenient information-gathering method and to offer a complete service for disabilities people.
6

Modélisation et optimisation multi-niveaux du transport forestier / A bi-level decision model for timber transport planning

Moad, Kamel 29 June 2016 (has links)
Cette thèse est une contribution à la modélisation, la planification et l’optimisation du transport pour l’approvisionnement en bois de forêt des industries de première transformation. Dans ce domaine, les aléas climatiques (mise au sol des bois par les tempêtes), sanitaires (attaques bactériologiques et fongiques des bois) et commerciaux (variabilité et exigence croissante des marchés) poussent les divers acteurs du secteur (entrepreneurs et exploitants forestiers, transporteurs) à revoir l’organisation de la filière logistique d’approvisionnement, afin d’améliorer la qualité de service (adéquation offre-demande) et de diminuer les coûts.L’objectif principal de cette thèse était de proposer un modèle de pilotage améliorant la performance du transport forestier, en respectant les contraintes et les pratiques du secteur.Les résultats établissent une démarche de planification hiérarchique des activités de transport à deux niveaux de décision, tactique et opérationnel. Au niveau tactique, une optimisation multi-périodes permet de répondre aux commandes en minimisant l’activité globale de transport, sous contrainte de capacité agrégée des moyens de transport accessibles. Ce niveau permet de mettre en oeuvre des politiques de lissage de charge et d’organisation de sous-traitance ou de partenariats entre acteurs de transport. Au niveau opérationnel, les plans tactiques alloués à chaque transporteur sont désagrégés, pour permettre une optimisation des tournées des flottes, sous contrainte des capacités physiques de ces flottes.Les modèles d’optimisation de chaque niveau sont formalisés en programmation linéaire mixte avec variables binaires. L’applicabilité des modèles a été testée en utilisant un jeu de données industrielles en région Aquitaine et a montré des améliorations significatives d’exploitation des capacités de transport par rapport aux pratiques actuelles.Les modèles de décision ont été conçus pour s’adapter à tout contexte organisationnel, partenarial ou non : la production du plan tactique possède un caractère générique sans présomption de l’organisation, celle-ci étant prise en compte, dans un deuxième temps, au niveau de l’optimisation opérationnelle du plan de transport de chaque acteur. / The present manuscript tackles the supply chain forest transportation problem in the context of forestry primary industry. In this context, several risks may affect the forest supply chain: the unpredictable weather conditions (tree falling provoked by major storms); sanitary emergencies (tree pest and diseases); and, diverse commercial circumstances (the variability of market demands). The aforementioned issues motivate the diverse forest sector protagonists (entrepreneurs, forest operators and drivers) to seek support for improving their logistic operations. The aim of this effort is to improve the service quality (offer-demand agreement) diminishing in this way the total costs. Therefore, the main goal of this thesis is the proposal of a novel management model which improves forest-to-mill transport performance. At the same time, the proposed model accounts for the forest sector manners and constraints. The contribution of this thesis is threefold: first a transportation model is developed, later on the transport planning is managed, and finally an optimization procedure is proposed.The thesis results propose a hierarchical planning for the forestry transportation. Two decision levels are suggested: tactic and operational. At a tactic level, a multi-period optimization is considered. The multi-period optimization strategy meets the customer supply demands while minimizes the global transportation activity. Such strategy takes into account the restrictions of the total available transportation means. Moreover, at this level the activity balancing politics may be developed, as well as subcontractors coordination between transport companies. On the other hand, at the operational level, the tactic planning assigned for each transporter is divided so an optimization of the fleet’s transport assignation is done considering the vehicles constraints.The decision process is modelled as a Mixed Linear Programming formulation. The application considers a data set coming from the industry settled at the Aquitaine region in France. The results have shown a significant improvement on the transport capabilities with respect to the conventional transport practices.It is worth to mention that the decision models were designed such that they may be adapted to different context either collaborative or not. In both cases, the tactic planning has a generic purpose, in other words, it is independent of the kind of organization involved, whereas specific organizations are taken into account when planning actors’ activities at the operational level.
7

La gestion de crise tsunami dans la Caraïbe : contribution géographique aux dispositifs d’alerte et d'évacuation des populations / Tsunami crisis management in the Caribbean : a geographical contribution to warning and evacuation procedures

Péroche, Mathieu 14 October 2016 (has links)
Le contexte géodynamique du bassin de la Caraïbe, du fait notamment de la présence de zones de subduction et de nombreux édifices volcaniques, est favorable à la génération de tsunamis. La connaissance historique de ce phénomène dans la région, associée à de récents résultats de simulation numérique, confirme ce fort potentiel. Les amplitudes de vagues modélisées à l’approche des côtes avoisinent les 10 m pour certains scénarios. L’aléa tsunami est une menace pour l’ensemble du littoral des territoires du bassin de la Caraïbe. Les enjeux humains, structurels et stratégiques, concentrés massivement sur ce littoral, sont particulièrement exposés à ce phénomène, notamment aux Antilles où le risque associé est très élevé. Aujourd’hui, un système de surveillance et de détection des tsunamis à l’échelle régionale assure la diffusion de messages d’information en cas d’événement. Néanmoins, il n’existe pas de dispositifs pour guider localement les autorités dans leurs prises de décisions pour mettre en sécurité des populations, ou bien ils restent très généralistes, notamment pour les territoires français. Afin d’anticiper ce besoin, nous avons accompagné la planification opérationnelle de la gestion des crises pour les phases d’alerte et d’évacuation temporaire des populations à terre et de la mise en sécurité des navires en mer. Cette démarche, engagée à différentes échelles, repose sur une approche géographique et intégrée de la gestion de crise tsunami, à l’interface des connaissances entre le domaine scientifique et opérationnel. Notre expertise scientifique a débouché sur l’élaboration de documents opérationnels pour le traitement des avis de tsunami dans le domaine terrestre et maritime et a permis d’établir une méthode de planification des évacuations pédestre. La méthode proposée est en cours d’application sur 60 communes littorales dans les Antilles Françaises. / The geo-dynamics of the Caribbean Sea area, particularly due to the presence of subduction zones and numerous volcanic faults is prone to the generation of tsunami's. Historical knowledge of this phenomenon in the region, coupled with recent modeling results, confirms this potential. The amplitudes of the modeled waves approaching the coast came close to 10m in some scenarios. The tsunami is a threat to the entire coastline of the Caribbean Sea. Human, structural and strategic installations, which are focused heavily on the coast, are particularly vulnerable to this phenomenon, especially in the Caribbean where the associated risk is very high. Today, at a regional level, a tsunami warning system is effective. However, there are no plans to guide the local authorities in their decision making to keep their population safe. At best they are very general, notably in the Antilles. So that we can anticipate their needs, we accompanied the operational planning of crisis management for the alert phases and the temporary evacuation of people on land and the security procedures for ships at sea. This initiative, undertaken on different levels, based on a geographical and integrated approach to the management of tsunami crisis, is at the interface of knowledge between scientific and operational domain. Our scientific expertise has led to the development of operational documents for the application of the tsunami warning on land and sea. It has helped to establish a method of pedestrian evacuation planning. The proposed method is already being implicated in 60 coastal municipalities in the French Antilles.
8

Plánování výkonnosti procesů / Process performance planning

Stoy, Tomáš January 2011 (has links)
This thesis deals with the operational planning of production at DT – Výhybkárna a strojírna, a.s., specifically evaluating impacts of the passage of an exceptional order on manufacturing process. Aim is to analyze the current state of process management, to evaluate the impact of additional interventions into the processes and to quantify the costs associated with this intervention in the planned production. All with the minimum cost and maximum efficiency at a given quality. The goal is achieved by simulating of inserting an exceptional order in the enterprise information system.
9

Lot Sizing at the Operational Planning and Shop Floor Scheduling Levels of the Decision Hierarchy of Various Production Systems

Chen, Ming 07 December 2007 (has links)
The research work presented in this dissertation relates to lot sizing and its applications in the areas of operational planning and shop floor scheduling and control. Lot sizing enables a proper loading of requisite number of jobs on the machines in order to optimize the performance of an underlying production system. We address lot sizing problems that are encountered at the order entry level as well as those that are faced at the time of distributing the jobs from one machine to another and those that arise before shipping the jobs (orders) to customers. There are different issues and performance measures involved during each of these scenarios, which make the lot sizing problems encountered in these scenarios different from one another. We present algorithms and relevant theoretical analyses for each of the lot sizing problems considered, and also, present results of numerical experimentation to depict their effectiveness We first study the lot sizing problem encountered while transferring jobs from one machine to another. A lot of the jobs is to be split into smaller lots (called sublots) such that the lot is processed on multiple machines in an overlapping manner, a process which is known in the literature as lot streaming. Two lot streaming problems, FL2/n/C and FLm/1/C, are investigated in Chapter 2. FL2/n/C involves a two-machine flow shop in which multiple lots are to be processed. The objective is to minimize the combined cost of makespan and material handling (the latter is proportional to the number of sublots). A dynamic programming-based methodology is developed to determine the optimal sublot sizes and the number of sublots for each lot while assuming a known sequence in which to process the lots. We designate this problem as LSP-DP. This methodology is, then, extended to determine an optimal sequence in which to process the lots in conjunction with the number of sublots and sublot sizes for each lot. We designate this problem as LSSP-DP. Three multidimensional heuristic search procedures (denoted as LSSP-Greedy, LSSP-Cyclic and LSSP-ZP) are proposed for this problem in order to obtain good-quality solutions in a reasonable amount of computational time. Our experimentation reveals that both lot streaming and lot sequencing generate significant benefits, if used alone. However, for the objective of minimizing total handling and makespan cost, lot streaming is more beneficial than lot sequencing. The combined use of lot streaming and sequencing, expectedly, results in the largest improvement over an initial random solution. LSP-DP is found to be very efficient, and so are the three LSSP heuristics, all of which are able to generate near-optimal solutions. On the average, LSSP-Greedy generates the best solutions among the three, and LSSP-Cyclic requires the least time. FLm/1/C deals with the streaming of a single lot over multiple machines in a flow shop. The objective is a unified cost function that comprises of contributions due to makespan, mean flow time, work-in-process, transfer time and setup time. The distinctive features of our problem pertain to the inclusion of sublot-attached setup time and the fact that idling among the sublots of a lot is permitted. A solution procedure that relies on an approximation equation to determine sublot size is developed for this problem for equal-size sublots. The approximation avoids the need for numerical computations, and enables the procedure to run in polynomial time. Our experimentation shows that this solution procedure performs quite well and frequently generates the optimal solution. Since the objective function involves multiple criteria, we further study the marginal cost ratios of various pairs of the criteria, and propose cost sensitivity indices to help in estimating the impact of marginal cost values on the number of sublots obtained. The lot sizing problem addressed in Chapter 3 is motivated by a real-life setting associated with semiconductor manufacturing. We first investigate the integration of lot sizing (at the operational planning level) and dispatching (at the scheduling and control level) in this environment. Such an integration is achieved by forming a closed-loop control system between lot sizing and dispatching. It works as follows: lot sizing module determines lot sizes (loading quota) for each processing buffer based on the current buffer status via a detailed linear programming model. The loading quotas are then used by the dispatching module as a general guideline for dispatching lots on the shop floor. A dispatching rule called "largest-remaining-quota-first" (LRQ) is designed to drive the buffer status to its desired level as prescribed by the lot sizing module. Once the buffer status is changed or a certain amount of time has passed, loading quotas are updated by the lot sizing module. Our experimentation, using the simulation of a real-life wafer fab, reveals that the proposed approach outperforms the existing practice (which is based on "first-in-first-out" (FIFO) model and an ad-hoc lot sizing method). Significant improvements are obtained in both mean values and standard deviations of the performance metrics, which include finished-goods inventory, backlog, throughput and work-in-process. The integration of lot sizing and dispatching focuses on the design of an overall production system architecture. Another lot sizing problem that we present in Chapter 3 deals with input control (or workload control) that complements this architecture. Input control policies are responsible for feeding the production system with the right amount of work and at the right time, and are usually divided into "push" or "pull" categories. We develop a two-phase input control methodology to improve system throughput and the average cycle time of the lots. In phase 1, appropriate operational lot sizes are determined with regard to weekly demand, so as to keep the lot start rate at the desired level. In phase 2, a "pull" policy, termed CONLOAD, is applied to keep the bottleneck's workload at a target level by releasing new lots into the system whenever the workload level is below the desired level. Since the operators are found to be the bottleneck of the system in our preliminary investigation, the "operator workload" is used as system workload in this study. Using throughput and cycle time as the performance metrics, it is shown that this two-phase CONLOAD methodology achieves significant improvement over the existing CONWIP-like policy. Furthermore, a reference table for the target operator workload is established with varying weekly demand and lot start rate. The last lot sizing problem that we address has to do with the integration of production and shipping operations of a make-to-order manufacturer. The objective is to minimize the total cost of shipping and inventory (from manufacturer's perspective) as well as the cost of earliness and tardiness of an order (from customer's perspective). An integer programming (IP) model is developed that captures the key features of this problem, including production and delivery lead times, multiple distinct capacitated machines and arbitrary processing route, among others. By utilizing the generalized upper bound (GUB) structure of this IP model, we are able to generate a simplified first-level RLT (Reformulation Linearization Technique) relaxation that guarantees the integrity of one set of GUB variables when it is solved as a linear programming (LP) problem. This allows us to obtain a tighter lower bound at a node of a branch-and-bound procedure. The GUB-based RLT relaxation is complemented by a GUB identification procedure to identify the set of GUB variables that, once restricted to integer values, would result in the largest increment in the objective value. The tightening procedure described above leads to the development of a RLT-based branch-and-bound algorithm. Our experimentation shows that this algorithm is able to search the branch-and-bound tree more efficiently, and hence, generates better solutions in a given amount of time. / Ph. D.
10

The impact of real time shop floor information on operational decision making

Vermaak, Martin 29 June 2011 (has links)
The concept of Operational decision making is not new, but in the context of Enterprise Resource Planning implementation as is the case at PFK Electronics (PTY) Ltd., it becomes part of what ERP process that makes organisations more competitive and profitable as Wallace and Kremzar (2001) comment, "Effective forecasting, planning, and scheduling is fundamental to productivity and ERP is a fundamental way to achieve it. Properly implementing ERP will give you a competitive advantage and help you run your business more effectively, efficiently and responsively." The Operational decision making process that forms part of the research question is a process known as Sales and Operational Planning process (SOP's). The research paper is looking at how Real Time Shop floor information can impact on the decision making process, as Wallace and Kremzar (2001 : 165) state that this is the most important element in making ERP systems work. The study looks at what information is required to make effective decisions in the SOP's process and how the respondents perceive information quality, its value and the impact on decision making in the SOP's process. The research sought to further investigate a diverse demographic population, the behavioural culture within the organisation and their perception on having this information in real time directly from the shop floor. Data was collected via a survey questionnaire and an interview process which also required the review of organisational documentation where available. The research aimed to investigate what information Operations (SOP's) need to make effective decisions to meet the organisational strategic objectives and to determine the best means of obtaining and communicating the information to managers. Developing this further the research was then broken down into three objectives: • To investigate 'what' information sales and operations managers need in order to make effective decisions that will have an impact on them meeting strategic performance objectives. • To evaluate 'how' real time shop floor information can improve the decision making process in Operations in meeting strategic objectives; by understanding the types and methods used in decision making and the significance of time on information. • To recommend suitable Information Communication Technology (ICT) systems to obtain and communicate information to managers effectively within operations. During this process time constraints were of a concern, which manifested in objective three not being able to be completed to the satisfaction of the researcher. However the research process, which included the survey and interviews of respondents, the researcher felt that respondents where honest and open in expressing their views which adds to the validity and reliability of the research. The results showed that there was a clear understanding of the topic amongst the respondents. It showed that the respondents had a good understanding of information and its importance in meeting strategic objectives by making better decisions. It became clear that ERP was generally working well but that timeliness of information was the biggest obstacle in meeting strategic objectives in balancing supply and demand. The research identified the information necessary for the SOP's process to be effective and it also showed the impact of having real time shop floor information available to the decision making process. It also showed that there would be other benefits as performance could also be improved by having real time performance indicators that are used to set the pace and common goal. The report also identified some cultural differences between PFK electronics culture and NUMSA unionised employees culture and the impact it has on relationships and communication. The report concludes with the research question being answered and with a recommendation that the single most important means of improving operational effectiveness is going to be to improve the quality of information used in decision making. The research has shown that getting this information in 'real time' or as close as possible to real time is the best means of improving the quality of information and its impact on management decisions. It is further recommended to investigate the implementation of systems such as Manufacturing Execution Systems to link the shop floor directly into the current ERP system and lastly to find a means of bridging the cultural differences between NUMSA unionised employees and PFK behavioural culture. / Graduate School of Business Leadership / M.B.A.

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