933 resultados para Goal Programming


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Two studies assessed the development of children's understanding of life as a biological goal of body functioning. In Study 1, 4-to-10-year-old children were given an interview consisting of a series of structured questions about the location and function of various body organs. Their responses were coded both for factual correctness and for appeals to the goal of maintaining life. The results showed a gradual increase in children's factual knowledge across this age range but an abrupt increase in appeals to life between the ages of 4 and 6. Analyses of the 4-year-olds' responses suggested that appeals to life were associated with increased knowledge of organ function, but not of organ location. Study 2 was designed to replicate the pattern found in Study I. A continuous sample of 4-to 5-year-old children was administered an abbreviated version of the interview from Study 1. Children's understanding of life as a biological goal was again found to be predictive of their knowledge of organ function, but not of organ location. These results indicate a reorganization in children's understanding of the body between the ages of 4 and 6, which coincides with children's discovery of 'life' as a biological goal for bodily function.

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A decision theory framework can be a powerful technique to derive optimal management decisions for endangered species. We built a spatially realistic stochastic metapopulation model for the Mount Lofty Ranges Southern Emu-wren (Stipiturus malachurus intermedius), a critically endangered Australian bird. Using diserete-time Markov,chains to describe the dynamics of a metapopulation and stochastic dynamic programming (SDP) to find optimal solutions, we evaluated the following different management decisions: enlarging existing patches, linking patches via corridors, and creating a new patch. This is the first application of SDP to optimal landscape reconstruction and one of the few times that landscape reconstruction dynamics have been integrated with population dynamics. SDP is a powerful tool that has advantages over standard Monte Carlo simulation methods because it can give the exact optimal strategy for every landscape configuration (combination of patch areas and presence of corridors) and pattern of metapopulation occupancy, as well as a trajectory of strategies. It is useful when a sequence of management actions can be performed over a given time horizon, as is the case for many endangered species recovery programs, where only fixed amounts of resources are available in each time step. However, it is generally limited by computational constraints to rather small networks of patches. The model shows that optimal metapopulation, management decisions depend greatly on the current state of the metapopulation,. and there is no strategy that is universally the best. The extinction probability over 30 yr for the optimal state-dependent management actions is 50-80% better than no management, whereas the best fixed state-independent sets of strategies are only 30% better than no management. This highlights the advantages of using a decision theory tool to investigate conservation strategies for metapopulations. It is clear from these results that the sequence of management actions is critical, and this can only be effectively derived from stochastic dynamic programming. The model illustrates the underlying difficulty in determining simple rules of thumb for the sequence of management actions for a metapopulation. This use of a decision theory framework extends the capacity of population viability analysis (PVA) to manage threatened species.

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Cropp and Gabric [Ecosystem adaptation: do ecosystems maximise resilience? Ecology. In press] used a simple phytoplanktonzooplankton-nutrient model and a genetic algorithm to determine the parameter values that would maximize the value of certain goal functions. These goal functions were to maximize biomass, maximize flux, maximize flux to biomass ratio, and maximize resilience. It was found that maximizing goal functions maximized resilience. The objective of this study was to investigate whether the Cropp and Gabric [Ecosystem adaptation: do ecosystems maximise resilience? Ecology. In press] result was indicative of a general ecosystem principle, or peculiar to the model and parameter ranges used. This study successfully replicated the Cropp and Gabric [Ecosystem adaptation: do ecosystems maximise resilience? Ecology. In press] experiment for a number of different model types, however, a different interpretation of the results is made. A new metric, concordance, was devised to describe the agreement between goal functions. It was found that resilience has the highest concordance of all goal functions trialled. for most model types. This implies that resilience offers a compromise between the established ecological goal functions. The parameter value range used is found to affect the parameter versus goal function relationships. Local maxima and minima affected the relationship between parameters and goal functions, and between goal functions. (C) 2003 Elsevier B.V. All rights reserved.

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O intuito inicial desta pesquisa foi acompanhar processos de trabalho à luz do referencial teórico da Ergologia e, portanto, concebendo o trabalho como relação dialética entre técnica e ação humana. O objetivo era cartografar o trabalho no processo de beneficiamento de granitos em uma organização de grande porte localizada no Espírito Santo e, após algum tempo em campo, o problema delineou- se do seguinte modo: como se constitui a competência industriosa no beneficiamento de granitos em uma organização de grande porte? A pesquisa justifica-se uma vez que, a despeito da relevância econômica, o cenário capixaba de rochas ornamentais apresenta problemas precários no que diz respeito à gestão. Para os Estudos Organizacionais, a relevância é reforçada pelo fato de aproximar desta área a abordagem ergológica e demarcar no debate sobre competência a noção de competência industriosa, ainda não explorada nesse campo de estudo. Para realização da pesquisa, foi praticada uma cartografia ergológica, a partir da articulação das pistas cartográficas com o referencial teórico-conceitual da Ergologia, sendo utilizadas como técnicas: observação participante durante 6 meses, com uma média de 3 visitas a campo por semana; 8 entrevistas semiestruturadas e em profundidade de cerca de 50 minutos cada com trabalhadores operacionais; uma entrevista com gerente de produção e outra com representante da área de Gestão de Pessoas; conversas com os demais trabalhadores, a fim de enriquecer o diário de campo; novas conversas e observações ao final da análise, para confrontação-validação com os trabalhadores. A sistematização dos procedimentos de análise pode ser assim descrita: a) leituras flutuantes com objetivo de fazer emergirem aspectos centrais relacionados às duas dimensões do trabalho, técnica e ação humana; b) leituras em profundidade com objetivo de fazer emergirem singularidades e especificidades relativas à dialética entre ambas; c) leituras em profundidade com objetivo de fazer emergirem aspectos relativos aos ingredientes da competência industriosa. A despeito da não delimitação de categorias analíticas e subcategorias, a partir da análise emergiram cinco eixos analíticos: 1) os procedimentos a serem empregados no processo de beneficiamento de granitos, englobando: as etapas do beneficiamento; as funções a serem desempenhadas e as tarefas a serem desenvolvidas; as normas regulamentadoras; os conhecimentos técnicos necessários para programação e operação de máquinas; a ordem de produção prescrita pelo setor comercial; 2) o trabalho real, diferenciado do trabalho como emprego de procedimentos pelo foco dado à ação humana no enfrentamento de situações reais, repletas de eventos e variabilidades, em todo o processo, englobando: preparo de carga; laminação; serrada; levigamento; resinagem; polimento-classificação; retoque; fechamento de pacote; ovada de contêiner; 3) diferentes modos de usos de si que, em tendência, são responsáveis pela constituição do agir em competência em cada etapa do processo, na dialética entre técnica e ação humana; 4) o modo como cada ingrediente da competência industriosa atua e se constitui, bem como sua concentração, em tendência, em cada etapa do processo, a partir dos tipos de usos de si que, também em tendência, são mais responsáveis pelo agir em competência, apresentando assim o perfil da competência industriosa no beneficiamento de granitos na empresa em análise; 5) dois possíveis fatores potencializadores dos ingredientes da competência industriosa, a saber, a transdução e os não-humanos. A partir de todo o exposto, as últimas considerações problematizam aspectos relativos ao debate sobre competências e práticas de gestão de pessoas a partir da competência compreendida da seguinte forma: mestria no ato de tirar partido do meio e de si para gerir situações de trabalho, em que a ação consiste na mobilização de recursos dificilmente perceptíveis e descritíveis, inerentes ao trabalhador, porém constituídos e manifestos por usos de si por si e pelos outros no e para o ato real de trabalho, marcadamente num nível infinitesimal, diante de situações que demandam aplicação de protocolos concomitante à gestão de variabilidades e eventos em parte inantecipáveis e inelimináveis.

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In this paper, the development of bidding strategies is investigated for a wind farm owner. The optimization model is characterized by making the analysis of scenarios. The proposed approach allows evaluating alternative production strategies in order to submit bids to the electricity market with the goal of maximizing profits. The problem is formulated as a linear programming problem. An application to a case study is presented

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This paper is on the problem of short-term hydro, scheduling, particularly concerning head-dependent cascaded hydro systems. We propose a novel mixed-integer quadratic programming approach, considering not only head-dependency, but also discontinuous operating regions and discharge ramping constraints. Thus, an enhanced short-term hydro scheduling is provided due to the more realistic modeling presented in this paper. Numerical results from two case studies, based on Portuguese cascaded hydro systems, illustrate the proficiency of the proposed approach.

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The use of distributed energy resources, based on natural intermittent power sources, like wind generation, in power systems imposes the development of new adequate operation management and control methodologies. A short-term Energy Resource Management (ERM) methodology performed in two phases is proposed in this paper. The first one addresses the day-ahead ERM scheduling and the second one deals with the five-minute ahead ERM scheduling. The ERM scheduling is a complex optimization problem due to the high quantity of variables and constraints. In this paper the main goal is to minimize the operation costs from the point of view of a virtual power player that manages the network and the existing resources. The optimization problem is solved by a deterministic mixedinteger non-linear programming approach. A case study considering a distribution network with 33 bus, 66 distributed generation, 32 loads with demand response contracts and 7 storage units and 1000 electric vehicles has been implemented in a simulator developed in the field of the presented work, in order to validate the proposed short-term ERM methodology considering the dynamic power system behavior.

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In recent years, power systems have experienced many changes in their paradigm. The introduction of new players in the management of distributed generation leads to the decentralization of control and decision-making, so that each player is able to play in the market environment. In the new context, it will be very relevant that aggregator players allow midsize, small and micro players to act in a competitive environment. In order to achieve their objectives, virtual power players and single players are required to optimize their energy resource management process. To achieve this, it is essential to have financial resources capable of providing access to appropriate decision support tools. As small players have difficulties in having access to such tools, it is necessary that these players can benefit from alternative methodologies to support their decisions. This paper presents a methodology, based on Artificial Neural Networks (ANN), and intended to support smaller players. In this case the present methodology uses a training set that is created using energy resource scheduling solutions obtained using a mixed-integer linear programming (MIP) approach as the reference optimization methodology. The trained network is used to obtain locational marginal prices in a distribution network. The main goal of the paper is to verify the accuracy of the ANN based approach. Moreover, the use of a single ANN is compared with the use of two or more ANN to forecast the locational marginal price.

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One of the most difficult problems that face researchers experimenting with complex systems in real world applications is the Facility Layout Design Problem. It relies with the design and location of production lines, machinery and equipment, inventory storage and shipping facilities. In this work it is intended to address this problem through the use of Constraint Logic Programming (CLP) technology. The use of Genetic Algorithms (GA) as optimisation technique in CLP environment is also an issue addressed. The approach aims the implementation of genetic algorithm operators following the CLP paradigm.

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This paper presents a methodology for distribution networks reconfiguration in outage presence in order to choose the reconfiguration that presents the lower power losses. The methodology is based on statistical failure and repair data of the distribution power system components and uses fuzzy-probabilistic modelling for system component outage parameters. Fuzzy membership functions of system component outage parameters are obtained by statistical records. A hybrid method of fuzzy set and Monte Carlo simulation based on the fuzzy-probabilistic models allows catching both randomness and fuzziness of component outage parameters. Once obtained the system states by Monte Carlo simulation, a logical programming algorithm is applied to get all possible reconfigurations for every system state. In order to evaluate the line flows and bus voltages and to identify if there is any overloading, and/or voltage violation a distribution power flow has been applied to select the feasible reconfiguration with lower power losses. To illustrate the application of the proposed methodology to a practical case, the paper includes a case study that considers a real distribution network.

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CoDeSys "Controller Development Systems" is a development environment for programming in the area of automation controllers. It is an open source solution completely in line with the international industrial standard IEC 61131-3. All five programming languages for application programming as defined in IEC 61131-3 are available in the development environment. These features give professionals greater flexibility with regard to programming and allow control engineers have the ability to program for many different applications in the languages in which they feel most comfortable. Over 200 manufacturers of devices from different industrial sectors offer intelligent automation devices with a CoDeSys programming interface. In 2006, version 3 was released with new updates and tools. One of the great innovations of the new version of CoDeSys is object oriented programming. Object oriented programming (OOP) offers great advantages to the user for example when wanting to reuse existing parts of the application or when working on one application with several developers. For this reuse can be prepared a source code with several well known parts and this is automatically generated where necessary in a project, users can improve then the time/cost/quality management. Until now in version 2 it was necessary to have hardware interface called “Eni-Server” to have access to the generated XML code. Another of the novelties of the new version is a tool called Export PLCopenXML. This tool makes it possible to export the open XML code without the need of specific hardware. This type of code has own requisites to be able to comply with the standard described above. With XML code and with the knowledge how it works it is possible to do component-oriented development of machines with modular programming in an easy way. Eplan Engineering Center (EEC) is a software tool developed by Mind8 GmbH & Co. KG that allows configuring and generating automation projects. Therefore it uses modules of PLC code. The EEC already has a library to generate code for CoDeSys version 2. For version 3 and the constant innovation of drivers by manufacturers, it is necessary to implement a new library in this software. Therefore it is important to study the XML export to be then able to design any type of machine. The purpose of this master thesis is to study the new version of the CoDeSys XML taking into account all aspects and impact on the existing CoDeSys V2 models and libraries in the company Harro Höfliger Verpackungsmaschinen GmbH. For achieve this goal a small sample named “Traffic light” in CoDeSys version 2 will be done and then, using the tools of the new version it there will be a project with version 3 and also the EEC implementation for the automatically generated code.

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This paper present a methodology to choose the distribution networks reconfiguration that presents the lower power losses. The proposed methodology is based on statistical failure and repair data of the distribution power system components and uses fuzzy-probabilistic modeling for system component outage parameters. The proposed hybrid method using fuzzy sets and Monte Carlo simulation based on the fuzzyprobabilistic models allows catching both randomness and fuzziness of component outage parameters. A logic programming algorithm is applied, once obtained the system states by Monte Carlo Simulation, to get all possible reconfigurations for each system state. To evaluate the line flows and bus voltages and to identify if there is any overloading, and/or voltage violation an AC load flow has been applied to select the feasible reconfiguration with lower power losses. To illustrate the application of the proposed methodology, the paper includes a case study that considers a 115 buses distribution network.

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In the energy management of the isolated operation of small power system, the economic scheduling of the generation units is a crucial problem. Applying right timing can maximize the performance of the supply. The optimal operation of a wind turbine, a solar unit, a fuel cell and a storage battery is searched by a mixed-integer linear programming implemented in General Algebraic Modeling Systems (GAMS). A Virtual Power Producer (VPP) can optimal operate the generation units, assured the good functioning of equipment, including the maintenance, operation cost and the generation measurement and control. A central control at system allows a VPP to manage the optimal generation and their load control. The application of methodology to a real case study in Budapest Tech, demonstrates the effectiveness of this method to solve the optimal isolated dispatch of the DC micro-grid renewable energy park. The problem has been converged in 0.09 s and 30 iterations.

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Electricity market players operating in a liberalized environment requires access to an adequate decision support tool, allowing them to consider all the business opportunities and take strategic decisions. Ancillary services represent a good negotiation opportunity that must be considered by market players. For this, decision support tools must include ancillary market simulation. This paper proposes two different methods (Linear Programming and Genetic Algorithm approaches) for ancillary services dispatch. The methodologies are implemented in MASCEM, a multi-agent based electricity market simulator. A test case concerning the dispatch of Regulation Down, Regulation Up, Spinning Reserve and Non-Spinning Reserve services is included in this paper.