5 resultados para Restricciones de selección

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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The present work begins with a review of the literature on bit selection methods for oil well drilling. A proposal for the structure and organization of a drilling database and a knowledge base, is described. Previous studies formed the principal elements in the process of selection of drills for proposed drilling. The procedure was implemented as a computer system for the selection of tricone bits. A drilling bit database for three different Brazilian sedimentary basins was obtained for several wells drilled, and knowledge was collected from drilling engineers from different fields both electronically and also by means of interviews. It can be concluded that the selection process showed good results based on tests, which were carried out.

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This paper presents a new approach for solving constraint optimization problems (COP) based on the philosophy of lexicographical goal programming. A two-phase methodology for solving COP using a multi-objective strategy is used. In the first phase, the objective function is completely disregarded and the entire search effort is directed towards finding a single feasible solution. In the second phase, the problem is treated as a bi-objective optimization problem, turning the constraint optimization into a two-objective optimization. The two resulting objectives are the original objective function and the constraint violation degree. In the first phase a methodology based on progressive hardening of soft constraints is proposed in order to find feasible solutions. The performance of the proposed methodology was tested on 11 well-known benchmark functions.

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Reliability is a key aspect in power system design and planning. Maintaining a reliable power system is a very important issue for their design and operation. Under the new competitive framework of the electricity sector, power systems find ever more and more strained to operate near their limits. Under this new scenario, it is crucial for the system operator to use tools that facilitate an energy dispatch that minimizes possible power cuts. This paper presents a mathematical model to calculate an energy dispatch that considers security constraints (single contingencies in transmission lines and transformers). The model involves pool markets and fixed bilateral contracts. Traditional methodologies that include security constraints are usually based in multistage dispatch processes. In this case, we propose a single-stage model that avoids the economic inefficiencies which result when conventional multi-stage dispatch approaches are applied. The proposed model includes an AC representation of the transport system and allows calculating the cost overruns incurred in due to reliability restrictions. We found that complying with fixed bilateral contracts, when they go above certain levels, might lead to congestion problems in transmission lines.

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The indexing is a kind of description whose aim is to establish concepts expressed in a document and representing them according to a documentary language. There are elements that can contribute to a more complete selection of terms that will represent the document, like the observation of its textual structure and the context where the indexing professional acts. The analysis of the book textual structure can be carried out in a way that facilitates the indexing, as the professional can foresee the parts of the text where he localizes and identifies the more representative terms of the textual content. In such a way, it is intended to comprehend and inquire, with the applying of Verbal Protocol, the use that São Paulo libraries indexers do from the textual structure during the determination of subjects in such a way as to obtain the disclosure of their procedures, difficulties and restrictions through the externalization of thoughts during the recording of the indexing task. From the data analysis, it was possible to find out that the right hand page, the back of the title page, the chapters and other parts of the book s structure provided the greater number of terms, becoming the most important ones for the indexing task.

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The status epilepticus (SE) is characterized by a series of crises which occur without recovery of consciousness or a single seizure lasting more than 30 minutes and can damage the central nervous system and systemic. The duration and frequency of attacks are directly related to patient prognosis. Whether seizures occur often and are longer, increase the risk of neurological and systemic complications. Child population has a higher frequency of seizures and it is associated with a lower threshold of immature brain to trigger these episodes. Aim: To determine the safest drugs prescribed for children in SE, their doses and schedules. A bibliographic survey was performed in electronic databases. Methods: The scientific health descriptors used for search was: “status epilecticus” and “anticonvulsivants” and “child”. Results: This strategy identified 396 manuscripts, of whom four were considered eligible for the study, after the assessment by floating reading and criteria. Of these, two were randomized trials and two descriptive. The studies address the use of oral midazolam, rectal diazepam and intravenous lorazepam. Conclusions: All investigated drugs were effective in treat in status epilepticus. Lorazepam is highlight, since it has fewer secondary effects and, as an alternative to the intravenous, oral midazolam. However, there is a need for further studies to demonstrate the efficacy and safety in the use of drugs in children.