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Modelagem e controle linear de um sistema de levitação de imã permanente. / Modeling and linear control of a permanent magnet levitation system.Izaias José Botelho 08 February 2008 (has links)
O objetivo deste trabalho é apresentar um novo tipo de sistema de levitação baseado na força de interação magnética entre uma bobina de núcleo não-magnético e um imã permanente, em casos de simetria axial entre os dispositivos, nos moldes do problema 23 proposto no TEAM Workshop. Este tema é bastante atual e vários métodos têm sido estudados e propostos em razão da complexidade na determinação precisa das forças sobre os imãs permanentes imersos em um campo magnético em um circuito magnético aberto. O primeiro grande desafio deste trabalho é obter uma expressão analítica para esta força de interação magnética em casos de simetria axial usando o método de cargas magnéticas ligadas. Para tal, algumas hipóteses simplificadoras foram adotadas como considerar o campo magnético gerado pela bobina aproximadamente uniforme em toda a face do imã permanente e assumir que a magnetização do imã é constante e independente da variação de sua distância para a bobina. Pretende-se aproveitar o sistema implementado neste trabalho como bancada experimental no Laboratório de Controle da Universidade de São Paulo. Foi projetado um controlador PID através de ferramentas gráficas obedecendo a alguns critérios de desempenho, tanto no domínio do tempo como no domínio da freqüência. Uma vez sintonizado, foi utilizado o toolbox Real-Time Windows Target do Simulink e a placa de aquisição PCI 6221 (da National Instruments) para controlar em tempo real a planta de levitação em malha fechada. Os resultados experimentais foram muito satisfatórios de modo que o modelo analítico foi considerado válido. O sistema apresentou boas características como, por exemplo, um bom acompanhamento do sinal de referência, mesmo em grandes excursões, erro de regime nulo, levitação estável em distâncias relativamente grandes e uma boa estabilidade radial. O uso de dois sensores Hall mostrou-se eficiente na determinação da posição do imã permanente. / The objective of this work is to present a new kind of levitation system based on the interaction force between a non-magnetic core coil and a permanent magnet, in the case of axial symmetry between devices, as proposed by TEAM Workshop problem 23. This theme is very current and various methods have been studied and proposed in face of the complexity in determining precisely the force over permanent magnets immersed in a magnetic field in an open magnetic circuit. The first big challenge of this work is to obtain an analytical expression for this interaction magnetic force in the case of axial symmetry using the equivalent magnetic charge method. For this, some simplifying hypothesis have been adopted like considering the magnetic field created by the coil approximately uniform over all the permanent magnets face and assuming that magnets magnetization is constant and independent of the variation of its distance to the coil. The system implemented in this work is intended to be used as an experimental bench for the Laboratory of Control of Sao Paulo University. A PID controller was projected by means of graphical tools according to some criteria for performance, both in the field of time as in the frequency domain. Once tuned, the toolbox Real-Time Windows Target of Simulink and the PCI-6221 acquisition board (of National Instruments) were used to control in real time the levitation plant in closed loop. The experimental results were very satisfactory so that the analytical model was considered valid. The system showed good characteristics as, for instance, a good tracking of reference signal, even in large excursions of it, null stationary error, stable levitation at relatively big gaps and a good radial stability. The use of two Hall-effect sensors proved to be efficient in the determination of permanent magnets position.
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Time-window optimization for a constellation of earth observation satelliteOberholzer, Christiaan Vermaak 02 1900 (has links)
Thesis (M.Com.(quantitative Management)) / Satellite Scheduling Problems (SSP) are NP-hard and constraint programming and
metaheuristics solution methods yield mixed results. This study investigates a new version of
the SSP, the Satellite Constellation Time-Window Optimization Problem (SCoTWOP),
involving commercial satellite constellations that provide frequent earth coverage.
The SCoTWOP is related to the dual of the Vehicle Routing Problem with Multiple Timewindows,
suggesting binary solution vectors representing an activation of time-windows.
This representation fitted well with the MatLab® Genetic Algorithm and Direct Search
Toolbox subsequently used to experiment with genetic algorithms, tabu search, and simulated
annealing as SCoTWOP solution methods. The genetic algorithm was most successful and in
some instances activated all 250 imaging time-windows, a number that is typical for a
constellation of six satellites. / Quantitative Management
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Time-window optimization for a constellation of earth observation satelliteOberholzer, Christiaan Vermaak 02 1900 (has links)
Thesis (M.Com.(quantitative Management)) / Satellite Scheduling Problems (SSP) are NP-hard and constraint programming and
metaheuristics solution methods yield mixed results. This study investigates a new version of
the SSP, the Satellite Constellation Time-Window Optimization Problem (SCoTWOP),
involving commercial satellite constellations that provide frequent earth coverage.
The SCoTWOP is related to the dual of the Vehicle Routing Problem with Multiple Timewindows,
suggesting binary solution vectors representing an activation of time-windows.
This representation fitted well with the MatLab® Genetic Algorithm and Direct Search
Toolbox subsequently used to experiment with genetic algorithms, tabu search, and simulated
annealing as SCoTWOP solution methods. The genetic algorithm was most successful and in
some instances activated all 250 imaging time-windows, a number that is typical for a
constellation of six satellites. / Quantitative Management
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Problema de roteamento de veículos com frota mista, janelas de tempo e custos escalonados. / Fleet size and mix vehicle routing problem with time windows and scaled costs.Manguino, João Luiz Veiga 18 February 2013 (has links)
O tema de roteamento de veículos é de grande importância na literatura e tem sido amplamente estudada pela sua importância para muitas indústrias. Com a evolução na literatura, mais características foram adicionadas para torná-lo mais próximo de situações reais. Alinhado com esta tendência, este trabalho aborda o problema de roteamento de veículos quando há a terceirização da frota que realiza as entregas. Uma forma de cobrança do frete é por meio de custos escalonados, que são calculados de acordo com o tipo de veículo e a distância percorrida, com valores fixos para cada faixa de distância. Embora seja uma forma comum de trabalho na indústria, nenhum trabalho focado nesta característica foi encontrado na literatura. Este problema é o problema de roteamento de veículos com frota mista, janelas de tempo e custos escalonados (FSMVRPTWSC). Ao abordar este problema, este trabalho apresenta um modelo de programação linear inteira mista que é avaliado em um cenário real da indústria. Além disso, três heurísticas de inserção sequencial são propostas para lidar com problemas maiores. Estes métodos são examinados por meio de testes computacionais em 168 problemas de referência gerados para este problema. Os experimentos numéricos mostram que os métodos são robustos e eficientes, apresentando um bom desempenho em conjuntos de problemas com diversas características. / The theme of vehicle routing is of great importance in the literature and has been widely studied for its relevance to many industries and, throughout the literature, more characteristics have been added to make it closer to real situations. Aligned with this trend, this paper addresses the vehicle routing problem when there is outsourcing of the fleet that delivers goods. One form of freight charging is by scaled costs, which are calculated according to the type of vehicle and the distance traveled, with fixed values for each distance range. Though it is a common form of work in the industry, no work focused on this characteristic was found in the literature. This problem is the fleet size and mix vehicle routing problem with time windows and scaled costs (FSMVRPTWSC). In approaching this problem, this paper presents a mixed integer linear programming model that is evaluated under a real situation scenario. Furthermore, three sequential insertion heuristics are proposed in order to deal with larger problems. These methods are examined through a computational comparative study in 168 benchmark problems generated for this problem. The numerical experiments show that the methods are robust and efficient, performing well in different problem sets.
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Ordonnancement cyclique multi-produits des lignes de traitement de surface : Méthodes exactes et approchées / Exact and heuristic appoaches for solving multi-parts cyclic hoist schelduling problemsEl Amraoui, Adnen 12 July 2011 (has links)
Cette thèse s’intéresse au fonctionnement cyclique multi-produits des ateliers de traitement de surface, et au problème d’ordonnancement associé (HSP), caractérisé par des contraintes fortes et atypiques, dont certaines sont liées aux ressources de transport. Dans le cas de productions en grandes séries, une commande cyclique de ces systèmes est particulièrement adaptée, permettant notamment de réduire la combinatoire de résolution, et sous réserve que les ratios de produits soient connus à l’avance. Notre objectif est de trouver le meilleur ordonnancement des tâches de traitement et de transport en un temps raisonnable. Pour cela, nous proposons une première approche, basée sur un modèle linéaire et une méthode de résolution arborescente de type séparation et évaluation. Nous présentons des modélisations pour différentes extensions du problème dit de base et nous fournissons des exemples illustratifs et des résultats sur des benchmarks. Par la suite et compte tenu de l’analyse de la littérature relative aux ordonnancements cycliques mono-produit et multi-produits, nous proposons tout d’abord une heuristique dédiée au cas multi-produits étudié, et basée sur un algorithme de liste. Avec ce dernier, nous obtenons un ordonnancement cyclique dont le degré du cycle n’est pas fixé au préalable. Enfin, nous présentons une deuxième modélisation approchée sous la forme d’un algorithme génétique pour résoudre un HSP 2-cyclique. Ces différents modèles sont validés par des tests sur des benchmarks de la littérature pour lesquels nous avons obtenus des résultats prometteurs. Nous terminons par une analyse critique des avantages et inconvénients des modèles élaborés et par quelques propositions de perspectives pour ce travail. / In this thesis, we study the Cyclic Hoist Scheduling Problem (CHSP) in automated electroplating lines, when a mass production must be achieved. The CHSP is characterized by specific constraints related to processing and transport resources. To solve it in a multi-parts context, we first elaborate a 2-degree cyclic model and an associated branch and bound algorithm. Then we extend it to more complex configurations. Then, we develop a dedicated heuristic to find a feasible repetitive sequence of hoist moves that minimizes the cycle time, without a priori fixing the cycle degree. Comparisons with existing algorithms are presented to show the efficiency of the proposed heuristic. To reduce the cycle time, we integrate in the general heuristic an algorithm with a set of Minimum Part Set (MPS) configurations’. This one allows us to find the best order in which jobs should be introduced into the line. Finally, we describe a genetic algorithm approach to find a schedule which can reach the optimal 2-cycle. We finally discuss the interest of those various models, based on the promising results obtained and we provide some perspectives which could be explored.
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Cyclic Hoist Scheduling Problems in Classical and Sustainabl / Ordonnancement cyclique des ressources de transport dans les ateliers de traitement de surface, dans des contextes traditionnel et durableLei, Weidong 08 December 2014 (has links)
Les ateliers de traitement de surface automatisés, qui utilisent des robots de manutention commandés par ordinateur pour le transport de la pièce, ont été largement mis en place dans différents types d'entreprises industrielles, en raison de ses nombreux avantages par rapport à un mode de production manuel, tels que : une plus grande productivité, une meilleure qualité des produits, et l’impact sur les rythmes de travail. Notre recherche porte sur trois types de problèmes d'ordonnancement associés à ces systèmes, appelés Hoist Scheduling Problems, caractérisés par des contraintes de fenêtres de temps de traitement: (I) un problème à une seule ressource de transport où l’objectif est de minimiser le temps de cycle; (II) un problème bi-objectif avec une seule ressource de transport où il faut minimiser le temps de cycle et la consommation de ressources de traitement (et par conséquent le coût de production); et (III) un problème d'ordonnancement cyclique mono-objectif mais multi-robots.En raison de la NP-complétude des problèmes étudiés et de nombreux avantages de les outils de type quantum-inspired evolutionary algorithm (QEA), nous proposons d'abord un QEA hybride comprenant un mécanisme de décodage amélioré et une procédure réparation dédiée pour trouver le meilleur temps de cycle pour le premier problème. Après cela, afin d'améliorer à la fois la performance économique et environnementale qui constituent deux des trois piliers de la stratégie de développement durable de nos jours déployée dans de nombreuses industries, nous formulons un modèle mathématique bi-objectif pour le deuxième problème en utilisant la méthode de l'intervalle interdit. Ensuite, nous proposons un QEA bi-objectif couplé avec une procédure de recherche locale pour minimiser simultanément le temps de cycle et les coûts de production, en générant un ensemble de solutions Pareto-optimales pour ce problème. Quant au troisième problème, nous constatons que la plupart des approches utilisées dans les recherches actuelles, telles que la programmation entière mixte (MIP), peuvent conduire à l’obtention d’une solution non optimale en raison de la prise en compte courante d’une hypothèse limitant l’exploration de l’espace de recherche et relative aux mouvements en charge des robots. Par conséquent, nous proposons une approche de MIP améliorée qui peut garantir l'optimalité des solutions obtenues pour ce problème, en relaxant l'hypothèse mentionnée ci-dessus.Pour chaque problème, une étude expérimentale a été menée sur des cas industriels ainsi que sur des instances générées aléatoirement. Les résultats obtenus montrent que l’efficacité des algorithmes d'ordonnancement proposés, ce qui justifie les choix que nous avons faits. / Automated treatment surface facilities, which employ computer-controlled hoists for part transportation, have been extensively established in various kinds of industrial companies, because of its numerous advantages over manual system, such as higher productivity, better product quality, and reduced labor intensity. Our research investigates three typical hoist scheduling problems with processing time windows in treatment surface facilities, which are: (I) cyclic single-hoist scheduling problem to minimize the cycle time; (II) cyclic single-hoist scheduling problem to minimize the cycle time and processing resource consumption (and consequently production cost); and (III) cyclic multi-hoist scheduling problem to minimize the cycle time.Due to the NP-completeness of the studied problems and numerous advantages of quantum-inspired evolutionary algorithm (QEA), we first propose a hybrid QEA with improved decoding mechanism and repairing procedure to find the best cycle time for the first problem. After that, to enhance with both the economic and environmental performance, which constitute two of the three pillars of the sustainable strategy nowadays deployed in many industries, we formulate a bi-objective mathematical model for the second problem by using the method of prohibited interval. Then we propose a bi-objective QEA with local search procedure to simultaneously minimize the cycle time and production cost, and we find a set of Pareto-optimal solutions for this problem. As for the third problem, we find that most existing approaches, such as mixed integer programming (MIP) approach, may identify a non-optimal solution to be an optimal one due to an assumption related to the loaded hoist moves which is made in many existing researches. Consequently, we propose an improved MIP approach for this problem by relaxing the above-mentioned assumption. Our approach can guarantee the optimality of its obtained solutions.For each problem, experimental study on industrial instances and random instances has been conducted. Computational results demonstrate that the proposed scheduling algorithms are effective and justify the choices we made.
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Shared Mobility Optimization in Large Scale Transportation Networks: Methodology and ApplicationsJanuary 2018 (has links)
abstract: Optimization of on-demand transportation systems and ride-sharing services involves solving a class of complex vehicle routing problems with pickup and delivery with time windows (VRPPDTW). Previous research has made a number of important contributions to the challenging pickup and delivery problem along different formulation or solution approaches. However, there are a number of modeling and algorithmic challenges for a large-scale deployment of a vehicle routing and scheduling algorithm, especially for regional networks with various road capacity and traffic delay constraints on freeway bottlenecks and signal timing on urban streets. The main thrust of this research is constructing hyper-networks to implicitly impose complicated constraints of a vehicle routing problem (VRP) into the model within the network construction. This research introduces a new methodology based on hyper-networks to solve the very important vehicle routing problem for the case of generic ride-sharing problem. Then, the idea of hyper-networks is applied for (1) solving the pickup and delivery problem with synchronized transfers, (2) computing resource hyper-prisms for sustainable transportation planning in the field of time-geography, and (3) providing an integrated framework that fully captures the interactions between supply and demand dimensions of travel to model the implications of advanced technologies and mobility services on traveler behavior. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2018
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Análise da aplicação de modelos de otimização linear na solução de problemas de dimensionamento de lotes e sequenciamento da produção de bebidas. / Analysis of the application of linear optimization models to solution lot sizing and scheduling problems in beverage industry.Noble Ramos, Victor Mario 24 November 2017 (has links)
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Previous issue date: 2017-11-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / This dissertation adresses the general integrated lot sizing and scheduling problem for non-alcoholic beverage production with synchronization between stages and operating time windows for scheduling preventive maintenances.
The problem is characterized by having two interdependent synchronized stages. In the first stage, machines (tanks) can supply several filling lines at the same time in the second stage, where the final items are packed. Production sequence-dependent times and costs exist.
The review of the related literature indicates that existing models refer, generally, to particular cases of the general problem adressed here, the most common cases are the dedication of tanks to the lines, and disregarding the perishability of syrups and the possibility of scheduling preventive maintenances.
A mathematical model for the general problem, called SMMRPM, has been proposed and applied in several instances to show the adherence and flexibility of the model to represent practical cases that can be found in reality. For the case of the dedication of tanks to lines, the model was compared with the dedicated model F1 (FERREIRA et al, 2012).
The results indicate that the SMMRPM model is flexible and adherent to represent practical scenarios in which other models are not applicable, for example the possibility of scheduling preventive maintenance and consideration of perishability are differential of the proposal. In the plans obtained, it was shown that it is important to include these considerations that significantly affect the productive plans. In the case of dedication, compared to the dedicated model, the formulation SMMRPM achieves production plans, on average, 52.63 \% less costly than F1. / Nesta dissertação de mestrado é pesquisado o problema geral integrado de dimensionamento e sequenciamento de lotes da produção de bebidas não alcoólicas com sincronia ente os estágios e janelas de tempo de operação para programação de manutenções preventivas.
O problema é caracterizado por ter dois estágios sincronizados e dependentes entre si. As máquinas do primeiro estágio (tanques) podem suprir ao mesmo tempo várias linhas de envase no segundo estágio, onde são envasados os itens finais. Existem tempos e custos de setup dependentes da sequência de produção.
A revisão da literatura relacionada indica que modelos existentes referem-se, em geral, a casos particulares do problema geral aqui tratado, sendo que os casos mais comuns são a dedicação de tanques à linhas, e desconsideração da perecibilidade dos xaropes e da possibilidade de programar manutenções preventivas.
Foi proposto um modelo matemático para o problema geral, denominado SMMRPM, e aplicado em diversas instâncias a fim de mostrar a aderência e a flexibilidade do modelo para representar casos práticos que podem ser achados na realidade. Para o caso da dedicação de tanques a linhas, o modelo foi comparado com o modelo dedicado F1 (FERREIRA et al, 2012).
Os resultados indicam que o modelo SMMRPM é flexível e aderente para representar cenários práticos em que outros modelos não são aplicáveis, por exemplo a possibilidade de programar manutenções preventivas e consideração da perecibilidade são diferenciais da proposta. Nos planos obtidos foi mostrada a importância da inclusão destas considerações que afetam significativamente os planos produtivos. No caso da dedicação, comparado com o modelo dedicado, a formulação SMMRPM consegue planos de produção, em média, 52.63 % menos custosos que o F1. / Demanda Social
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Problema de roteamento de veículos com frota mista, janelas de tempo e custos escalonados. / Fleet size and mix vehicle routing problem with time windows and scaled costs.João Luiz Veiga Manguino 18 February 2013 (has links)
O tema de roteamento de veículos é de grande importância na literatura e tem sido amplamente estudada pela sua importância para muitas indústrias. Com a evolução na literatura, mais características foram adicionadas para torná-lo mais próximo de situações reais. Alinhado com esta tendência, este trabalho aborda o problema de roteamento de veículos quando há a terceirização da frota que realiza as entregas. Uma forma de cobrança do frete é por meio de custos escalonados, que são calculados de acordo com o tipo de veículo e a distância percorrida, com valores fixos para cada faixa de distância. Embora seja uma forma comum de trabalho na indústria, nenhum trabalho focado nesta característica foi encontrado na literatura. Este problema é o problema de roteamento de veículos com frota mista, janelas de tempo e custos escalonados (FSMVRPTWSC). Ao abordar este problema, este trabalho apresenta um modelo de programação linear inteira mista que é avaliado em um cenário real da indústria. Além disso, três heurísticas de inserção sequencial são propostas para lidar com problemas maiores. Estes métodos são examinados por meio de testes computacionais em 168 problemas de referência gerados para este problema. Os experimentos numéricos mostram que os métodos são robustos e eficientes, apresentando um bom desempenho em conjuntos de problemas com diversas características. / The theme of vehicle routing is of great importance in the literature and has been widely studied for its relevance to many industries and, throughout the literature, more characteristics have been added to make it closer to real situations. Aligned with this trend, this paper addresses the vehicle routing problem when there is outsourcing of the fleet that delivers goods. One form of freight charging is by scaled costs, which are calculated according to the type of vehicle and the distance traveled, with fixed values for each distance range. Though it is a common form of work in the industry, no work focused on this characteristic was found in the literature. This problem is the fleet size and mix vehicle routing problem with time windows and scaled costs (FSMVRPTWSC). In approaching this problem, this paper presents a mixed integer linear programming model that is evaluated under a real situation scenario. Furthermore, three sequential insertion heuristics are proposed in order to deal with larger problems. These methods are examined through a computational comparative study in 168 benchmark problems generated for this problem. The numerical experiments show that the methods are robust and efficient, performing well in different problem sets.
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Algorithm Construction for Efficient Scheduling of Advanced Health Care at HomeAfroze, Tonima, Rosén Gardell, Moa January 2015 (has links)
Providing advanced health care at home rather than in a hospital creates a greater quality of life for patients and their families. It also lowers the risk of hospital-acquired infections and accelerates recovery. The overall cost of care per patient is decreased. Manual scheduling of patient visits by health care professionals (HCPs) has become a bottleneck for increased patient capacity at SABH, a ward providing advanced pediatric health care at home (“Sjukhusansluten Avancerad Barnsjukvård i Hemmet” in Swedish), since many parameters need to be taken into account during scheduling. This thesis aims to increase the efficiency of SABH’s daily scheduling of personnel and resources by designing an automated scheduler that constructs a daily schedule and incorporates changes in it when needed in order to remove scheduling as a limitation for increased patient capacity. Requirements on a feasible schedule are identified in cooperation with SABH and literature is investigated about similar areas where the scheduling process has been automated. The scheduling is formulated as a computerized problem and investigated from the perspective of theoretical computer science. We show that the scheduling problem is NP-hard and can therefore not be expected to be solved optimally. The algorithm for scheduling the visits minimizes violations of time windows and travel times, and maximizes person continuity and workload balancing. The algorithm constructs an initial solution that fulfills time constraints using a greedy approach and then uses local search, simulated annealing, and tabu search to iteratively improve the solution. We present an exact rescheduling algorithm that incorporates additional visits after the original schedule has been set. The scheduling algorithm was implemented and tested on real data from SABH. Although we found the algorithm to be efficient, automatic transfer of data from the patient journal system is an imperative for the scheduler to be adopted. / Barn som får avancerad sjukvård hemma istället för på sjukhus tillfrisknar ofta snabbare och risken för vårdrelaterade infektioner minskar. Barnen och deras familjer blir mer välmående av att få vistas i sin hemmiljö. På Astrid Lingrens barnsjukhus i Stockholm erbjuds avancerad hemsjukvård av avdelningen Sjukhusansluten Avancerad Barnsjukvård i Hemmet (SABH). För att schemalägga när patienterna ska besökas av sjukvårdspersonalen behöver många olika faktorer beaktas, detta sker idag helt manuellt. Den manuella schemaläggningen utgör en naturlig begränsning av SABHs patientkapacitet. Denna uppsats syftar till att effektivisera schemaläggningsprocessen hos SABH genom att föreslå en automatiserad lösning som hanterar koordinering av personal och resurser och dem förändringar som behöver göras i schemat under dagen, för att få bort schemaläggningsprocessen som ett hinder mot ökad patientkapacitet. Krav på schemaläggningen identifieras i diskussion med SABH och genom att studera litteratur kring liknande områden där schemaläggning lösts automatiserat. Vi formulerar schemaläggningen som ett datologiskt problem och analyserar det med utgångspunkt i teoretisk datalogi. Vi visar att problemet är NP-svårt och därför inte kan förväntas lösas optimalt inom rimlig tid. Vår lösning approximerar istället fram ett rimligt svar, där fokus hos algoritmen är att patienterna ska besökas de tider de behöver, personalens restider ska vara så korta som möjligt samtidigt som arbetsbördan hos personalen ska vara så lika fördelad som möjligt och patienterna ska, i den mån det är möjligt, få vård av samma personal. Med en girig algoritm konstrueras ett initialt schema som uppfyller de grundläggande kraven, detta schema förbättras med lokalsökning, simulated annealing och tabusökning. En exakt lösning framställs för uppdatering av schemat. Algoritmen för att lägga ett dagligt schema (utan uppdateringar) implementerades och testades med riktigt data från SABH. Vår algoritm visade sig vara effektiv, men för att kunna göra hela schemaläggningsprocessen effektiv behöver den integreras med journalsystemet.
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