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Cyclic Scheduling ProblemsKampmeyer, Thomas 13 July 2006 (has links)
For classical non-cyclic scheduling problems, we are given a set of operations,each of which has to be processed exactly once. The aim is to minimize or maximizea given objective function such as makespan or sum of all (weighted) completion times for a given set of constraints. The set of constraints is usually given by precedence constraints between the operations. In contrast to these problems, for cyclic scheduling problems we are given a set of operations, each of which has to be processed infinitely often. Such types of scheduling problems arise in different application areas like compiler design, manufacturing, digital signal processing, railway scheduling, timetabling, etc. The problem is to find a periodic schedule which minimizes a given objective function. There exist two objective functions which are important in this area of cyclic scheduling. The objective which is considered throughout this work is to minimize the time difference between two succeeding occurrences of one operation for a given set of constraints. This time difference is called cycle time. In this thesis, we develop a general framework to model and to describe cyclic scheduling problems with resource constraints. Furthermore, we extend the model to describe blocking constraints for cyclic scheduling problems. In order to solve the problem, we develop a local search approach.
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Fult språk och språknormer - attityder till fult språk i skolanHjertström, Adam, Zelander, Emilie January 2011 (has links)
Fula ord kan definieras på flera olika sätt. I vårt arbete syftar vi till svordomar, könsord och kraftuttryck. Syftet med vår studie är att undersöka hur språknormer påverkar lärare och elevers användande av fula ord i skolan. Studien är genomförd på ett antal skolor i södra Sverige. Genom enkätundersökning och intervjuer med lärare, fritidspedagoger och elever har vi fått fram ett resultat som visar hur språknormer är knutet till identitet, att normerna är svåra att förhålla sig till, samt att de normer som förekommer i skolan är gamla normer som existerat i flera generationer. Resultatet har lett oss fram till tre slutsatser:-En lärare eller elevs förhållningsätt till språknormerna är ett hjälpmedel i formandet av identiteten.-Normerna kring fula ord är starka nog att skapa eller upprätthålla ett förbud.-De normer som råder i skolan påverkar i allra högsta grad användandet av fult språk, men varken lärare eller elever tycks veta med säkerhet varför specifika normer råder och hur man ska förhålla sig till dem.De teorier vi har förankrat vår studie i rör språksociologi, språkförändring, språkliga normer och attityder, samt tabu.
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Optimization of Quality in Home Care / Optimering av kvalitet ihemtjänstCronsioe, Carl January 2017 (has links)
As the older population grows larger there is a growing need to provide health care at home. This services are generally done without operational research. As more people will require home care there will be a need to increase the efficiency of the service while keeping the quality high. The purpose of this thesis is to investigate how we can use operation research in home care as well as define how we can model the quality and use those quality parameters in order to offer the best possible service. The model uses VRP with Time windows in order to schedule the routes and incorporates service requirements at the customers. A solution is obtained by first constructing an initial solution that fulfills the duration constraint. Then it uses a local search with a dynamic insertion heuristic to improve on the solution. Tabu search is used as a meta-heuristic to prevent the solution the get stuck in a local minima. The solver is used in order to optimize the quality parameters. The result obtained can be used to help home care providers to determine the level of quality they can supply with a limited budget / När den äldre befolkningen blir större växer behovet av att tillhandahålla vård i hemmet. Denna tjänst använder i allmänhet inte systemteori. Eftersom fler människor kommer att behöva hemtjänst kommer det att finnas behov av att öka effektiviteten samtidigt som kvaliteten hålls hög. Syftet med denna avhandling är att undersöka hur vi kan använda systemteori och optimering inom hemtjänst samt definiera hur vi kan modellera kvaliteten och använda dessa kvalitetsparametrar för att erbjuda bästa möjliga service. Modellen använder VRP med Time windows för att schemalägga rutterna och inkorporerar servicebehov hos kunderna. En lösning erhålles genom att först bygga en initial lösning. Sedan använder den en lokal sökning med en dynamisk heuristisk för att förbättra lösningen. Tabu search används som en meta-heuristik för att förhindra att lösningen fastnar i lokala minima. Algoritmen används för att optimera kvalitetsparametrarna. Resultatet kan användas för att hjälpa leverantörer av hemtjänst att bestämma vilken kvalitetsnivå de kan leverera med en begränsad budget
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Det gömda könet – fittan, vaginan och snippan. En studie om diskursiva problem runt kvinnans kön i SverigePersson, Johanna, Godusevic, Emina January 2014 (has links)
In Sweden today it is problematic to talk about the woman's sex. Many women are embarrassed over their sex, nor do they have particularly strong knowledge of their sex or its functions. Language difficulties also contribute to problems for Swedish women when they come in contact with a professional who works with the female sex. In our study we have researched which denomination is most commonly used for the female sex and also how the public sees the word “fitta”. We have researched if the female body is a linguistic taboo and how this is shown in the meeting between women with problems and professionals. Our results have revealed that “underliv”, “slida” and “vagina” is the most common names, and this may be because these terms are primarily used in the medical discourses. The word “fitta” is problematic because the negative contexts it occurs in hampers the use of the word in its proper sense. Our conclusion is that the female sex is probably not a linguistic taboo, but it is very charged and difficult to talk about which is confirmed by our informants and respondents. This makes it complicated for both the professionals as well as for those patients seeking help. We think that the linguistic problems around the woman's gender shouldn't exist and instead should be allowed to be something nice and beautiful that no one should be ashamed of. We see it as a right to be able to talk about the woman's sex unabashedly.
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Méthodes heuristiques pour résoudre un problème d'horaire de projets avec contraintes sur les ressourcesBeaulieu, Catherine January 2002 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Influence of Customer Locations on Heuristics and Solutions for the Vehicle Routing ProblemTilashalski, Melissa Christine 07 July 2023 (has links)
The vehicle routing problem (VRP) determines preferred vehicle routes to visit multiple customer locations from a depot location based on a defined objective function. The VRP is an NP-hard network optimization problem that is challenging to solve to optimality. Over the past 60 years, multitudes of heuristics and metaheuristics have been developed in order to minimize the computational burden of solving the VRP. In order to compare the performance of VRP heuristics, researchers have developed bench-marking datasets. These datasets, however, lack properties found in industry datasets.
In this dissertation, we explore how properties of industry datasets influence VRP heuristics and objective functions. In Chapter 2, we quantify and compare features of bench-marking and industry datasets. In order to determine if these features influence heuristic performance, we conduct extensive computational runs on three heuristics, Tabu Search, Genetic Algorithm, and Clarke-Wright Savings Procedure, on standard and industry datasets. In Chapter 3, we derive worst-case analysis on how VRP objective functions and metrics relate to one another. These bounds depend on properties of customer locations. These bounds illustrate how customer locations can influence how different routes behave for different routing metrics. Finally, in Chapter 4, we improve two VRP heuristics, Clarke-Wright Saving Procedure and Hybrid Genetic Search Algorithm, by developing new enhancements to the algorithms. These enhancements rely on certain properties of the datasets in order to perform well. Thus, these heuristics perform better on specific VRP dataset types. / Doctor of Philosophy / The vehicle routing problem (VRP) creates vehicle routes that have the shortest travel distance. The routes determine how vehicles should visit multipl customer locations, to deliver or pickup goods, and return to a depot location. While explaining what the VRP entails is simple, the VRP is actually very difficult for even the most sophisticated algorithms on the best computers to solve. Over the past 60 years, many algorithms have been developed in order to more easily and quickly solve the VRP. In order to compare the performance of VRP algorithms, researchers have developed bench-marking datasets. However, these datasets lack properties of datasets found in industry. In this dissertation, we look to connect the disconnect between industry and bench-marking datasets by 1) comparing feature differences between these two types of datasets, 2) determining if differences in datasets imply differences in algorithm performance, 3) proving how problem differences influence VRP routes, and 4) enhancing existing VRP algorithms to perform better on specific VRP dataset types.
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HUMAN-CENTERED TIME-PRESSURED DECISION MAKING IN DYNAMIC COMPLEX SYSTEMSGanapathy, Subhashini 14 July 2006 (has links)
No description available.
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Simulation-optimization in real-time decision makingZhang, Xuemei January 1997 (has links)
No description available.
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A Probabilistic Study of 3-SATISFIABILITYAytemiz, Tevfik 06 July 2001 (has links)
Discrete optimization problems are defined by a finite set of solutions together with an objective function value assigned to each solution. Local search algorithms provide useful tools for addressing a wide variety of intractable discrete optimization problems. Each such algorithm offers a distinct set of rules to intelligently exploit the solution space with the hope of finding an optimal/near optimal solution using a reasonable amount of computing time.
This research studies and analyses randomly generated instances of 3-SATISFIABILITY to gain insights into the structure of the underlying solution space. Two random variables are defined and analyzed to assess the probability that a fixed solution will be assigned a particular objective function value in a randomly generated instance of 3-SATISFIABILITY. Then, a random vector is defined and analyzed to investigate how the solutions in the solution space are distributed over their objective function values. These results are then used to define a stopping criterion for local search algorithms applied to MAX 3-SATISFIABILITY.
This research also analyses and compares the effectiveness of two local search algorithms, tabu search and random restart local search, on MAX 3-SATISFIABILITY. Computational results with tabu search and random restart local search on randomly generated instances of 3-SATISFIABILITY are reported. These results suggest that, given a limited computing budget, tabu search offers an effective alternative to random restart local search. On the other hand, these two algorithms yield similar results in terms of the best solution found. The computational results also suggest that for randomly generated instances of 3-SATISFIABILITY (of the same size), the globally optimal solution objective function values are typically concentrated over a narrow range. / Ph. D.
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A Complete & Practical Approach to Ensure the Legality of a Signal Transmitted by a Cognitive RadioCowhig, Patrick Carpenter 24 October 2006 (has links)
The computational power and algorithms needed to create a cognitive radio are quickly becoming available. There are many advantages to having a radio operated by cognitive engine, and so cognitive radios are likely to become very popular in the future. One of the main difficulties associated with the cognitive radio is ensuring the signal transmitted will follow all FCC rules. The work presented in this thesis provides a methodology to guarantee that all signals will be legal and valid. The first part to achieving this is a practical and easy to use software testing program based on the tabu search algorithm that tests the software off-line. The primary purpose of the software testing program is to find most of the errors, specially structural errors, while the radio is not in use so that it does not affect the performance of the system. The software testing program does not provide a complete assurance that no errors exist, so to supplement this deficit, a built-in self-test (BIST) is employed. The BIST is designed with two parts, one that is embedded into the cognitive engine and one that is placed into the radio's API. These two systems ensure that all signals transmitted by the cognitive radio will follow FCC rules while consuming a minimal amount of computational power.
The software testing approach based on the tabu search is shown to be a viable method to test software with improved results over previous methods. Also, the software BIST demonstrated its ability to find errors in the signal production and is dem to only require an insignificant amount of computational power. Overall, the methods presented in this paper provide a complete and practical approach to assure the FCC of the legality of all signals in order to obtain a license for the product. / Master of Science
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