80 resultados para System failures (Engineering)

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The development of an offshore field demands knowledge of many experts to choose the different components of an offshore production system. All the specialized parts of this knowledge are intrinsically related. The aim of this paper is to use Fuzzy Sets and knowledge-based systems to describe and formalize the phases of development of an offshore production system project, in order to share and to manage the required knowledge for carrying out a project, while at the same time proposing alternatives for the oil field configuration.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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To date, different techniques of navigation for mobile robots have been developed. However, the experimentation of these techniques is not a trivial task because usually it is not possible to reuse the developed control software due to system incompabilities. This paper proposes a software platform that provides means for creating reusable software modules through the standardization of software interfaces, which represent the various robot modules. © 2012 ICROS.

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In this work a switching feedback controller for stick-slip compensation of a 2-DOF mass-spring-belt system which interacts with an energy source of limited power supply (non-ideal case) is developed. The system presents an oscillatory behavior due to the stick-slip friction. As the system equilibrium for a conventional feedback controller is not the origin, a switching control law combining a state feedback term and a discontinuous term is proposed to regulate the position of the mass. The problem of tracking a desired periodic trajectory is also considered. The feedback system is robust with respect to the friction force that is assumed to be within known upper and lower bounds.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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A new methodology for tree seedling production (Aquaforest system) based on a continuous floating subirrigation system was developed and tested using creeks with different nutrient levels. Eucalyptus grandis seedlings were produced in water from polluted and clean creeks, and compared to conventional tree nursery production. The growth variables analyzed in the seedling phase were: survival, height, diameter, shoot and root dry weight, leaf area, and root/shoot ratio. Water and substrate were analyzed, as well as leaf nutritional status. Plant survival was 100% in all treatments. Height and diameter were greater in the higher nutrient water treatment. Leaf area and dry weight of plants produced in the higher nutrient water treatment were similar to those of the control. The results showed that polluted water can represent a good nutrient source. The preliminary results show that the Aquaforest system can be a viable alternative for tree seedling production. (C) 2004 Elsevier B.V. All rights reserved.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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In this paper is proposed the use of biogas generated in the Wastewater Treatment Plant of a Dairy industry. The objective is to apply a thermoeconomic analysis to the supplementary cold water production of an absorption refrigeration system (NH3 + H2O) by the burning of such gas. The exergoeconomic analysis is carried out to allow a comparison between an absorption refrigeration system and of an equivalent compression refrigeration system that uses NH3 as work fluid. The proposed exergoeconomic model uses functional diagrams and allows one to obtain the exergetic incremental functions for each component individually and for the system as a whole. The model minimizes the exergetic manufacturing cost (EMC) which represents the cost of supplementary cold water production at 1degreesC (exergetic base) needed for this dairy's cold storage. As a conclusion, the absorption refrigeration system is better than compression refrigeration system, when the biogas cost is not considered. 2004 Elsevier Ltd. All rights reserved.

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In this paper, a thermoeconomic analysis method based on the first and second law of thermodynamics and applied to an evaporative cooling system coupled to an adsorption dehumidifier, is presented. The main objective is the use of a method called exergetic manufacturing cost (EMC) applied to a system that operates in three different conditions to minimize the operation costs. Basic parameters are the RIP ratio (reactivation air/process air) and the reactivation air temperature. Results of this work show that the minimum reactivation temperature and the minimum RIP ratio corresponds to the smaller EMC. This result can be corroborated through an energetic analysis. It is noted that this case is also the one corresponding to smaller energy loss. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

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In the minimization of tool switches problem we seek a sequence to process a set of jobs so that the number of tool switches required is minimized. In this work different variations of a heuristic based on partial ordered job sequences are implemented and evaluated. All variations adopt a depth first strategy of the enumeration tree. The computational test results indicate that good results can be obtained by a variation which keeps the best three branches at each node of the enumeration tree, and randomly choose, among all active nodes, the next node to branch when backtracking.

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This paper describes a method of identifying morphological attributes that classify wear particles in relation to the wear process from which they originate and permit the automatic identification without human expertise. The method is based on the use of Multi Layer Perceptron (MLP) for analysis of specific types of microscopic wear particles. The classification of the wear particles was performed according to their morphological attributes of size and aspect ratio, among others. (C) 2010 Journal of Mechanical Engineering. All rights reserved.

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The hydrodynamic characterization and the performance evaluation of an aerobic three phase fluidized bed reactor in wastewater fish culture treatment are presented in this report. The objective of this study was to evaluate the organic matter, nitrogen and phosphorous removal efficiency in a physical and biological wastewater treatment system of an intensive Nile Tilapia laboratory production with recirculation. The treatment system comprised of a conventional sedimentation basin operated at a hydraulic detention time HDT of 2.94 h and an aerobic three phase airlift fluidized bed reactor AAFBR operated at an 11.9 min HDT. Granular activated carbon was used as support media with density of 1.64 g/cm(3) and effective size of 0.34 mm in an 80 g/L constant concentration. Mean removal efficiencies of BOD, COD, phosphorous, total ammonia nitrogen and total nitrogen were 47%, 77%, 38%, 27% and 24%, respectively. The evaluated system proved an effective alternative for water reuse in the recirculation system capable of maintaining water quality characteristics within the recommended values for fish farming and met the Brazilian standards for final effluent discharges with exception of phosphorous values. (C) 2011 Elsevier B.V. All rights reserved.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)