Дисертації з теми "Constrained cutting"
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Oberholzer, Jan Adriaan. "Implementing artificial intelligence search methods to solve constrained two-dimensional guillotine-cut cutting stock problems / by Jan Adriaan Oberholzer." Thesis, North-West University, 2003. http://hdl.handle.net/10394/392.
Повний текст джерелаThesis (Ph.D. (Computer Science))--North-West University, Potchefstroom Campus, 2004.
Cardozo, Arteaga Carmen. "Optimisation of power system security with high share of variable renewables : Consideration of the primary reserve deployment dynamics on a Frequency Constrained Unit Commitment model." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC024/document.
Повний текст джерелаThe Unit Commitment problem (UC) is a family of optimisation models for determining the optimal short-term generation schedule to supply electric power demand with a defined risk level. The UC objective function is given by the operational costs over the optimisation horizon. The constraints include, among others, technical, operational and security limits. Traditionally, the security constraints are given by the requirement of a certain volume of on-line spare capacity, which is called the reserve and is meant to handle uncertainty, while preventing the interruption of power supply. It is commonly specified following a static reliability criterion, such as the N-1 rule.Nevertheless, in small systems the fixed, and a priori defined, reserve constraint could entail a violation of the N-1 criterion, although the reserve constraint was met. More recently, the increasing share of variable generation from renewable sources (V-RES), such as wind and solar, may lead to UC solutions that no longer ensure system security. Therefore, different impact mitigation techniques have been proposed in literature, which include the revision of UC models to provide a better representation of the system dynamics. This subfamily of UC models is formally defined in this work as the frequency constrained UC problem (FCUC), and aims to keep the frequency above a certain threshold, following pre-defined contingencies, by adding enhanced security constraints. In this work this topic is addressed in four parts.The first part identifies the main challenge of formulating the FCUC problem. Indeed, the frequency minimum, also called the frequency nadir, constraint is strongly non-linear on the decision variables of the UC model. Moreover, the behaviour of the frequency nadir regarding the binary decision variables is hard to approximate by analytical functions. Thus, a sequential simulation approach is proposed, based on a classic UC model and a reduced order model of the primary frequency response. The potential benefits of a smarter allocation of the primary reserve is revealed.The second part of this work investigates the impact of V-RES sources on the primary frequency response. The underlying processes that lead to the increase of the Under-Frequency Load Shedding (UFLS) risk are thoroughly discussed. The need of formulating more accurate FCUC models is highlighted.The third part of this work examines the cost/benefit and limitation of FCUC models based on indirect constraints over certain dynamic parameters of the generating units. A methodology is proposed that assesses the effectiveness and optimality of some existing V-RES impact mitigation techniques, such as the increase of the primary reserve requirement, the prescription of an inertia requirement, the authorisation of V-RES dispatch-down or the consideration of fast non-synchronous providers of frequency regulation services. This study showed the need for new methods to properly handle the frequency nadir constraint in order to ensure optimality, without compromising the optimisation problem’s tractability.The fourth part of this work offers a new formulation of the FCUC problem following a Bender’s decomposition approach. This method is based on the decomposition of an optimisation problem into two stages: the master and the slave problems. Here, the master problem deals with the generating unit states and the slave problem handles the frequency nadir constraints through a cutting plane model. Simulation results showed that the more accurate representation of the frequency nadir in the slave problem reduces the risk of UFLS and the security cost, with respect to other FCUC models, such as those based on inertia constraints. In addition, the optimality of the global solution is guaranteed; although the convergence of the master problem is slow, due to the well-known tailing off effect of cutting plane methods
Soberanis, Policarpio Antonio. "Risk optimization with p-order conic constraints." Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/437.
Повний текст джерелаVitor, Fabio Torres. "Improving the solution time of integer programs by merging knapsack constraints with cover inequalities." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/19226.
Повний текст джерелаDepartment of Industrial and Manufacturing Systems Engineering
Todd Easton
Integer Programming is used to solve numerous optimization problems. This class of mathematical models aims to maximize or minimize a cost function restricted to some constraints and the solution must be integer. One class of widely studied Integer Program (IP) is the Multiple Knapsack Problem (MKP). Unfortunately, both IPs and MKPs are NP-hard, potentially requiring an exponential time to solve these problems. Utilization of cutting planes is one common method to improve the solution time of IPs. A cutting plane is a valid inequality that cuts off a portion of the linear relaxation space. This thesis presents a new class of cutting planes referred to as merged knapsack cover inequalities (MKCI). These valid inequalities combine information from a cover inequality with a knapsack constraint to generate stronger inequalities. Merged knapsack cover inequalities are generated by the Merging Knapsack Cover Algorithm (MKCA), which runs in linear time. These inequalities may be improved by the Exact Improvement Through Dynamic Programming Algorithm (EITDPA) in order to make them stronger inequalities. Theoretical results have demonstrated that this new class of cutting planes may cut off some space of the linear relaxation region. A computational study was performed to determine whether implementation of merged knapsack cover inequalities is computationally effective. Results demonstrated that MKCIs decrease solution time an average of 8% and decrease the number of ticks in CPLEX, a commercial IP solver, approximately 4% when implemented in appropriate instances.
Yahiaoui, Ala-Eddine. "Selective vehicle routing problem : cluster and synchronization constraints." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2449/document.
Повний текст джерелаThe Vehicle Routing Problem (VRP) is a family of Combinatorial Optimization Problems generally used to solve different issues related to transportation systems and logistics. In this thesis, we focused our attention on a variant of the VRP called the Team Orienteering Problem (TOP). In this family of problems, it is a priory impossible to visit all the customers due to travel time limitation on vehicles. Instead, a profit is associated with each customer to represent its value and it is collected once the customer is visited by one of the available vehicles. The objective function is then to maximize the total collected profit with respect to the maximum travel time. Firstly, we introduced a new generalization for the TOP that we called the Clustered TOP (CluTOP). In this variant, the customers are grouped into subsets called clusters to which we associate profits. To solve this variant, we proposed an exact scheme based on the cutting plane approach with additional valid inequalities and pre-processing techniques. We also designed a heuristic method based on the order first-cluster second approach for the CluTOP. This Hybrid Heuristic combines between an ANLS heuristic that explores the solutions space and a splitting procedure that explores the giant tours search space. In addition, the splitting procedure is enhanced by local search procedure in order to enhance its coverage of search space. The second problem treated in this work is called the Synchronized Team Orienteering Problem with Time Windows (STOPTW). This variant was initially proposed in order to model scenarios related to asset protection during escaped wildfires. It considers the case of a heterogeneous fleet of vehicles along with time windows and synchronized visits. To solve this problem, we proposed a heuristic method based on the GRASP×ILS approach that led to a very outstanding results compared to the literature. The last variant of the TOP tackled in this thesis called the Set Orienteering Problem (SOP). Customers in this variant are grouped into subsets called clusters. Each cluster is associated with a profit which is gained if at least one customer is served by the single available vehicle. We proposed a Branch-and-Cut with two separation procedures to separate subtours elimination constraints. We also proposed a Memetic Algorithm with an optimal splitting procedure based on dynamic programming
Carvalho, Alexandre Augusto Martins. "Proposta metodologica para racionalização de ociosidade fabril /." Guaratinguetá, 2019. http://hdl.handle.net/11449/182420.
Повний текст джерелаResumo: Ambientes industriais são altamente competitivos. Fatores como a agilidade, a flexibilidade, a prestação de serviços, a qualidade e preços são as vantagens competitivas procuradas pelas organizações. Neste cenário, as otimizações propostas que abordam tais fatores são de particular interesse para o planejamento de processos. O procedimento proposto tratado é o resultado líquido direto e o aumento da competitividade no mercado de uma determinada empresa, visando que sua estrutura financeira seja a mais saudável possível. Este trabalho tem como objetivo auxiliar e desenvolver um procedimento padrão de verificação do nível de rentabilidade de uma empresa e ainda, se esta empresa tem a probabilidade de tornar-se mais rentável. Tal procedimento visa atingir um segundo objetivo no sentido de maximizar os recursos já existentes na própria organização. O aspecto chave desta pesquisa diz respeito à utilização de máquina com tempos ociosos e plena utilização de todos os sistemas disponíveis de fábrica. Quando a ociosidade destas máquinas utilizadas em pleno processo produtivo, é possível concluir como resultado das aplicações realizadas, uma maximização dos recursos propiciando o melhor resultado da organização. Esta ociosidade quando não apurada com a devida acurácia é lançada indevidamente nos custos dos produtos, fazendo com que a empresa possa perder competitividade
Abstract: Industrial environments are highly competitive. Factors such as agility, flexibility, service delivery, quality and prices are the competitive advantages sought by organizations. In this scenario, the proposed optimizations that address such factors are of particular interest for process planning. The proposed procedure is the direct net result and the increase of the competitiveness in the market of a certain company, aiming that its financial structure is as healthy as possible. This work aims to assist and develop a standard procedure for verifying the level of profitability of a company and still, if this company has the probability of becoming more profitable. This procedure aims to achieve a second objective in order to maximize resources already existing in the organization itself. The key aspect of this research concerns the use of idling machines and full utilization of all the systems available from the factory. When the idleness of these machines used in full productive process, it is possible to conclude as a result of the applications made, a maximization of the resources propitiating the best result of the organization. This idleness when not verified with the correct accuracy is improperly thrown into the costs of the products, causing the company to lose competitiveness
Doutor
Hellman, Fredrik. "Towards the Solution of Large-Scale and Stochastic Traffic Network Design Problems." Thesis, Uppsala University, Department of Information Technology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-130013.
Повний текст джерелаThis thesis investigates the second-best toll pricing and capacity expansion problems when stated as mathematical programs with equilibrium constraints (MPEC). Three main questions are rised: First, whether conventional descent methods give sufficiently good solutions, or whether global solution methods are to prefer. Second, how the performance of the considered solution methods scale with network size. Third, how a discretized stochastic mathematical program with equilibrium constraints (SMPEC) formulation of a stochastic network design problem can be practically solved. An attempt to answer these questions is done through a series ofnumerical experiments.
The traffic system is modeled using the Wardrop’s principle for user behavior, separable cost functions of BPR- and TU71-type. Also elastic demand is considered for some problem instances.
Two already developed method approaches are considered: implicit programming and a cutting constraint algorithm. For the implicit programming approach, several methods—both local and global—are applied and for the traffic assignment problem an implementation of the disaggregate simplicial decomposition (DSD) method is used. Regarding the first question concerning local and global methods, our results don’t give a clear answer.
The results from numerical experiments of both approaches on networks of different sizes shows that the implicit programming approach has potential to solve large-scale problems, while the cutting constraint algorithm scales worse with network size.
Also for the stochastic extension of the network design problem, the numerical experiments indicate that implicit programming is a good approach to the problem.
Further, a number of theorems providing sufficient conditions for strong regularity of the traffic assignment solution mapping for OD connectors and BPR cost functions are given.
Abrantes, Ricardo Luiz de Andrade. "Problemas de corte com sobras aproveitáveis e eliminação de simetrias." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/45/45134/tde-16122012-183550/.
Повний текст джерелаIn this work we study two variations of the packing problem where identical rectangular items must be packed into a polyhedron. One of the variations consists in finding the largest amount of rectangular items that can fit in a polyhedron. The other one consists in finding a minimal area polyhedron of a certain type that packs a set of rectangular identical items. We present some symmetry-breaking constraints that reduce the computational effort in solving those problems through a branch-&-bound method. We also studied the cutting stock problem where there are some items to be cut from a set of rectangular objects and we need to satisfy the demand of items to be cut minimizing the cost of the used objects and, among the different ways of doing this, we want that which maximize the usable leftovers. Loosely speaking,usable leftovers can be understood as rectangular regions in an object that has the width and the height greater than or equal to the ones of a reference item. These leftovers can be seen as leftovers from a cutting process that will become items in a new cutting process. We present bilevel programming models to two variations of this problem with usable leftovers: the two-stage cutting stock problem of rectangular items and the non-guillotine cutting stock problem of rectangular items. In order to solve the proposed models we present also MIP reformulations of these bilevel programming problem models. We also developed some symmetry breaking constraints in order to accelerate the solving process of those models. The developed models were computationally programmed and we were able to solve small instances of the proposed problems
Hokama, Pedro Henrique Del Bianco 1986. "O problema do caixeiro viajante com restrições de empacotamento tridimensional." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/275722.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
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Resumo: Nesta dissertação de mestrado apresentamos um método exato para o Problema do Caixeiro Viajante com Restrições de Empacotamento Tridimensional, que combina o Problema do Caixeiro Viajante o Problema de Empacotamento Tridimensional com Restrição de Ordem. Neste problema, um veículo deve partir carregado de um depósito e entregar caixas em pontos pré-definidos para seus clientes. Cada cliente tem um conjunto de caixas que deve receber e o objetivo é minimizar o custo de deslocamento do veículo. As caixas devem ser retiradas a partir da porta do contêiner do veículo e a remoção das caixas de um cliente não podem ser obstruídas pelas caixas a serem descarregadas posteriormente. Propomos uma abordagem exata baseada em branch-and-cut para buscar uma rota de custo mínimo. Apresentamos algumas adaptações de algoritmos da literatura e uma formulação em Programação por Restrições para encontrar um empacotamento que obedece restrições de ordem. Realizamos testes computacionais em instâncias geradas aleatoriamente e comparamos resultados com os algoritmos adaptados da literatura. Os resultados foram bastante satisfatórios resolvendo instâncias de tamanho médio em tempo computacional aceitável na prática
Abstract: We present an exact method for the Traveling Salesman Problem with Three-dimensional Loading Constraints. This problem combines the Traveling Salesman Problem, and the Three- Dimensional Packing Problem With Loading Constraints. In this problem, a vehicle must be loaded at the depot and deliver boxes to the customers. Every customer has a set of boxes that should receive and our goal is to minimize the travel cost of the vehicle. Unloading is done through a single side of the container and items from an unloading customer must not be blocked by items to be delivered later. We propose exact and heuristic branch-and-cut algorithm to find a minimum cost route. Adaptations of algorithms from the literature and a Constraint Programming formulation is presented to find a packing that consider unloading contraints. We performed computational tests on instances randomly generated and compared results with the algorithms adapted from literature. The results were quite satisfactory resolving several instances in reasonable computational time
Mestrado
Ciência da Computação
Mestre em Ciência da Computação
Mesyagutov, Marat. "Exact Approaches for Higher-Dimensional Orthogonal Packing and Related Problems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-137905.
Повний текст джерелаEs werden NP-schwere höherdimensionale orthogonale Packungsprobleme betrachtet. Wir untersuchen ihre logische Struktur genauer und zeigen, dass sie sich in Probleme kleinerer Dimension mit einer speziellen Nachbarschaftsstruktur zerlegen lassen. Dies beeinflusst die Modellierung des Packungsprozesses, die ihreseits zu drei neuen Lösungsansätzen führt. Unter Beachtung dieser Zerlegung modellieren wir die Probleme kleinerer Dimension in einer einzigen positionsindizierten Formulierung mit Nichtüberlappungsungleichungen, die als Bindungsbedingungen dienen. Damit entwickeln wir ein neues Modell der ganzzahligen linearen Optimierung und unterziehen dies einer Polyederanalyse. Weiterhin geben wir allgemeine Nichtüberlappungs- und Dichtheitsungleichungen an und beweisen unter geeigneten Annahmen ihre facettendefinierende Eigenschaft für die konvexe Hülle der ganzzahligen Lösungen. Basierend auf dem vorgeschlagenen Modell und den starken Ungleichungen entwickeln wir einen neuen Branch-and-Cut-Algorithmus. Jedes Problem kleinerer Dimension ist eine Relaxation des höherdimensionalen Problems. Darüber hinaus besitzt es Anwendungen in verschiedenen Bereichen, wie zum Beispiel im Scheduling. Für die Behandlung der Probleme kleinerer Dimension setzen wir das Gilmore-Gomory-Modell ein, das eine Dantzig-Wolfe-Dekomposition der positionsindizierten Formulierung ist. Um eine Nachbarschaftsstruktur zu erhalten, muss die Basismatrix der optimalen Lösung die consecutive-1’s-Eigenschaft erfüllen. Für die Konstruktion solcher Matrizen entwickeln wir neue Branch-and-Price-Algorithmen, die sich durch Strategien zur Enumeration von partiellen Lösungen unterscheiden. Wir beweisen auch einige Charakteristiken von partiellen Lösungen, die das Hilfsproblem der Spaltengenerierung verschärfen. Für die nichtlineare Modellierung der höherdimensionalen Packungsprobleme untersuchen wir moderne Ansätze des Constraint Programming, modifizieren diese und schlagen neue Dichotomie- und Überschneidungsstrategien für die Verzweigung vor. Für die Verstärkung der Constraint Propagation stellen wir neue Ablehnungskriterien vor. Wir nutzen dabei 1D Relaxationen mit Intervallen und verbotenen Paaren, erweiterte Streifen-Relaxation, 2D Scheiben-Relaxation und 1D Scheiben-Streifen-Relaxation mit verbotenen Paaren. Alle vorgestellten Kriterien basieren auf Relaxationen durch Probleme kleinerer Dimension, die wir weiter durch die LP-Relaxation des Gilmore-Gomory-Modells abschwächen. Wir schließen mit Umsetzungsfragen und numerischen Experimenten aller vorgeschlagenen Ansätze
Melega, Gislaine Mara [UNESP]. "Problema integrado de dimensionamento de lotes e corte de estoque: modelagem matemática e métodos de solução." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150002.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Nesta tese, estamos interessados em tratar de maneira integrada dois conhecidos problemas da literatura. Esta integração é referida na literatura como problema integrado de dimensionamento de lotes e corte de estoque. A ideia consiste em considerar simultaneamente, as decisões relacionadas com ambos os problemas, de modo a capturar a interdependência entre estas decisões e, assim, obter uma melhor solução global. Propõe-se um modelo matemático geral para o problema integrado de dimensionamento de lotes e corte de estoque (GILSCS), que considera vários níveis de integração e nos permite classificar a literatura, em termos de modelos matemáticos, dos problemas integrados. A classificação é organizada a partir de dois principais aspectos de integração que são: a integração através dos períodos de tempo e a integração entre os níveis de produção. Em um horizonte de planejamento que considera vários períodos, o estoque fornece uma ligação entre os períodos. Esta integração, por períodos de tempo, constitui o primeiro tipo de integração. O problema geral também considera a produção em diferentes níveis: objetos são fabricados ou comprados e então são cortados para produzir peças menores e estas, por sua vez, constituem componentes para a produção dos produtos finais. A integração entre os diferentes níveis de produção consiste no segundo tipo de integração. A revisão da literatura também possibilita direcionar interessantes áreas para pesquisas futuras. O comportamento da solução para este tipo de problema, com três níveis e vários períodos, é estudado a partir do desenvolvimento de métodos de solução considerando abordagens que superam as dificuldades do problema, que consistem no alto número de padrões de corte, estruturas em vários níveis (multiestágios) e variáveis binárias de preparo. Os métodos de solução propostos para o problema GILSCS são baseados em duas abordagens conhecidas da literatura, usadas com sucesso para resolver os problemas separadamente, que são o procedimento de geração de colunas e heurísticas de decomposição do tipo relax-and-fix. Estas estratégias e suas variações são combinadas à um pacote de otimização em um estudo computacional com dados gerados aleatoriamente. Uma revisão da literatura, em termos de métodos de solução, para o problema integrado também é apresentada. Outras contribuições desta tese consistem em propor diferentes modelos matemáticos para o problema integrado, combinando modelos alternativos para cada um dos problemas separadamente. Neste estudo, o objetivo é comparar e avaliar, com um extensivo estudo computacional, a qualidade e o impacto das diferentes formulações. O outro trabalho trata de uma aplicação do problema integrado em um indústria de móveis de pequeno porte, em que restrições específicas do ambiente industrial são abordadas, como estoque de segurança e ciclos da serra. A solução obtida pelo modelo proposto é comparada com uma simulação da prática da empresa.
In this thesis, the subject of interest is in treating, in an integrated way, two wellknown problems in the literature. This integration is referred in the literature as the integrated lot-sizing and cutting stock problem. The basic idea is to consider, simultaneously, the decisions related to both problems so as to capture the interdependency between these decisions in order to obtain a better global solution. We propose a mathematical model for a general integrated lot-sizing and cutting stock (GILSCS) problem. This model considers multiple dimensions of integration and enables us to classify the current literature, in terms of mathematical models, in this field. The main classification of the literature is organized around two types of integration. In a planning horizon which consists of multiple periods, the inventory provides a link between the periods. This integration across time periods constitutes the first type of integration. The general problem also considers the production in different levels: objects are fabricated or purchased and then, they are cut to produce the pieces which are then assembled as components in the production of final products. The integration between these production levels constitutes the second type of integration. The literature review also enables us to point out interesting areas for future research. The behavior of a solution to this type of problem, with three levels of production and several time periods, is studied considering the development of solution approaches that overcome the difficulties of the problem, which are the high number of cutting patterns, multi-level structures and the binary values of the setup variables. The solution methods proposed to the GILSCS problem are based on two known strategies from the literature which are used successfully to solve the problems separately, which are the column generation procedure and decomposition heuristics based on relax-and-fix procedure. These strategies and their variations are combined into an optimization package in a computational study with randomly generated data. A literature review, in terms of solution methods, to the integrated problem, is also presented. Other contributions of this thesis consist of proposing different mathematical models for the integrated problem combining alternative models for each one of the problems separately. In this study, the aim is to compare and evaluate, with an extensive computational study, the quality and the impact of these dfifferent formulations. Another study is an application of the integrated problem in a small furniture factory, in which specific constraints related to the industrial environment are addressed, such as, safety stock level constraints and saw cycles constraints. The solution obtained from the proposed model is compared to a simulation of the common practice in the company.
FAPESP: 2012/20631-2
Yang, Ching-Hang, and 楊靖航. "An Exact Algorithm for Constrained Two-Dimensional Cutting Problems." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/16368522931165429755.
Повний текст джерела明志科技大學
工業工程與管理研究所
99
The two-dimensional cutting stock problem consists of cutting a rectangular plate into specified smaller rectangular pieces, so that the objective function is optimized. This problem is also classified as NP-hard. In practical, raw material utilization has always been an important factor for the cutting industry, therefore, efficient use of the minimum quantity of raw plate in cutting while meet the requirements of the smaller pieces has become more important. In this research, we have developed an integer nonlinear programming formulation for optimizing the layout of the smaller pieces on the raw plate while the required quantity for the raw plate is minimized. Test problems have been optimally solved by a branch and bound method in LINGO solver. The results show that our formulation outperformed others in getting the optimal solution, also can provide the exact coordinates for the smaller pieces on the raw plates in order to cut the plates with ease.
Hegde, Abhijit. "Mechanics of cutting in granular media." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5828.
Повний текст джерелаIISc, DBT
Chien, Shang-bin, and 簡尚彬. "Improved Constraint Handling in Optimization of Steel Bar Cutting Plan." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/12120752119134800024.
Повний текст джерела國立臺灣科技大學
營建工程系
97
For many years, the construction industry has been regarded as one of the main developed industries in Taiwan. Since the construction market has been under recession in recent years, many construction companies face a decrease in profit due to not well-planned cost control. Therefore, contractors have seen the cost control as an important task. As the technology changes day by day, it is desired that the cost control may be improved using advanced optimization techniques. The purpose of this research is to minimize the total cost of cutting steel bar, in other words, to increase the return value of used and unused raw steel bar, and reduce the cost by cutting frequency reduction. For existing of the past algorithms , a cutting plan that violates the constraints was often encountered, and this resulted in waste of calculation resources. An improved Genetic Algorithm was firstly presented in this research so as to minimize the number of constraints. In order to handle infeasible solutions properly, the coded system of chromosome of steel bar cutting will be changed, and two models of solutions of cutting steel bar will also be brought up in this research. One model is to continuously search until the feasible solutions are found, and the other one is to apply the penalty strategy to handle the non-feasible solutions. Both models adopted the theory of tournament selection. As to verify the quality and efficiency of the solutions, the proposed models were tested in practical cases, and the results indicated that they are able to produce good cutting plans correctly and efficiently. Moreover, the models are also able to meet the requirements of construction operations because they generate the best solutions within the time constraints, and then retrench the human resource and upgrade the construction quality.
Shi-XianSue and 蘇士賢. "Machining Path Planning with Physical Constraints Based on Spline Curve and Its Application for Laser Cutting." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7sskme.
Повний текст джерелаPicard, Paul. "Do visual quality objectives necessarily constrain timber harvest levels? : subtitle exploring the potential of partial cutting." Thesis, 2002. http://hdl.handle.net/2429/13378.
Повний текст джерелаYu-ChiehTsai and 蔡妤潔. "Combining Cutting Plane Method and Local Search to Solve a Two-Echelon Repairable Inventory System Problem Subject to Service Level Constraints." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/49997681980815168047.
Повний текст джерела國立成功大學
工業與資訊管理學系
103
We address a two-echelon spare parts repairable inventory system consisting of a central repair warehouse and some regional depots. The objective is to determine an (S-1, S) pair that minimizes a cost function, defined only in terms of holding costs, subject to the constraint that the average response time to each customer is below a threshold level. To avoid the mistakes resulting from the approximation and implausible assumptions in traditional methods, we propose an algorithm based on simulation instead of queueing theory. The R&S procedure can be used to solve simulation optimization problems for which the number of feasible solution is small, and thus we propose a simulation algorithm which combines the cutting plane method, the feasible check procedure and the feasible direction approach.
Riaz, Muhammad Waqas. "Two-Echelon Supply Chain Design for Spare Parts with Time Constraints." Thesis, 2013. http://hdl.handle.net/10012/7914.
Повний текст джерелаMesyagutov, Marat. "Exact Approaches for Higher-Dimensional Orthogonal Packing and Related Problems." Doctoral thesis, 2013. https://tud.qucosa.de/id/qucosa%3A27750.
Повний текст джерелаEs werden NP-schwere höherdimensionale orthogonale Packungsprobleme betrachtet. Wir untersuchen ihre logische Struktur genauer und zeigen, dass sie sich in Probleme kleinerer Dimension mit einer speziellen Nachbarschaftsstruktur zerlegen lassen. Dies beeinflusst die Modellierung des Packungsprozesses, die ihreseits zu drei neuen Lösungsansätzen führt. Unter Beachtung dieser Zerlegung modellieren wir die Probleme kleinerer Dimension in einer einzigen positionsindizierten Formulierung mit Nichtüberlappungsungleichungen, die als Bindungsbedingungen dienen. Damit entwickeln wir ein neues Modell der ganzzahligen linearen Optimierung und unterziehen dies einer Polyederanalyse. Weiterhin geben wir allgemeine Nichtüberlappungs- und Dichtheitsungleichungen an und beweisen unter geeigneten Annahmen ihre facettendefinierende Eigenschaft für die konvexe Hülle der ganzzahligen Lösungen. Basierend auf dem vorgeschlagenen Modell und den starken Ungleichungen entwickeln wir einen neuen Branch-and-Cut-Algorithmus. Jedes Problem kleinerer Dimension ist eine Relaxation des höherdimensionalen Problems. Darüber hinaus besitzt es Anwendungen in verschiedenen Bereichen, wie zum Beispiel im Scheduling. Für die Behandlung der Probleme kleinerer Dimension setzen wir das Gilmore-Gomory-Modell ein, das eine Dantzig-Wolfe-Dekomposition der positionsindizierten Formulierung ist. Um eine Nachbarschaftsstruktur zu erhalten, muss die Basismatrix der optimalen Lösung die consecutive-1’s-Eigenschaft erfüllen. Für die Konstruktion solcher Matrizen entwickeln wir neue Branch-and-Price-Algorithmen, die sich durch Strategien zur Enumeration von partiellen Lösungen unterscheiden. Wir beweisen auch einige Charakteristiken von partiellen Lösungen, die das Hilfsproblem der Spaltengenerierung verschärfen. Für die nichtlineare Modellierung der höherdimensionalen Packungsprobleme untersuchen wir moderne Ansätze des Constraint Programming, modifizieren diese und schlagen neue Dichotomie- und Überschneidungsstrategien für die Verzweigung vor. Für die Verstärkung der Constraint Propagation stellen wir neue Ablehnungskriterien vor. Wir nutzen dabei 1D Relaxationen mit Intervallen und verbotenen Paaren, erweiterte Streifen-Relaxation, 2D Scheiben-Relaxation und 1D Scheiben-Streifen-Relaxation mit verbotenen Paaren. Alle vorgestellten Kriterien basieren auf Relaxationen durch Probleme kleinerer Dimension, die wir weiter durch die LP-Relaxation des Gilmore-Gomory-Modells abschwächen. Wir schließen mit Umsetzungsfragen und numerischen Experimenten aller vorgeschlagenen Ansätze.