865 resultados para Facility location reformulation
Resumo:
O desenvolvimento das redes de estradas rurais, especialmente em áreas montanhosas, é a intervenção chave para melhorar a acessibilidade às localidades e aos serviços públicos, cobrindo o maior número de localidades e de serviços públicos, otimizando os escassos recursos disponíveis em países em desenvolvimento. Este estudo explora diferentes modelos de organização de redes de estradas rurais considerando a construção de novas ligações ou o melhoramento de estradas existentes. Um método, baseado na cobertura da rede de estradas rurais, é utilizado para identificar os pontos nodais que formam a rede rural base numa específica região, a qual cobrirá um conjunto dos serviços públicos e de localidades. O modelo assenta numa rede rural de estradas típica ("backbone" e "branch") das regiões montanhosas do Nepal. Os modelos propostos fornecem um conjunto de possibilidades de ligações a estabelecer ou a melhorar e oferece soluções para diferentes níveis de orçamento, que otimizam os custos de transporte na rede, considerando diferentes tipos de pavimento (em solo, granular ou asfáltico). Foi realizado separadamente um modelo dedicado a análises multi-objetivo para resolver problemas de melhoramento de ligações dentro da rede considerando dois objectivos, minimizar os custos de operação para o utilizador e maximizar a população coberta pela rede de estradas, considerando ligações pavimentadas e não pavimentadas (em solo, granular ou asfáltico) dentro de um determinado limite orçamental. O modelo dá ao decisor (DM) diferentes alternativas eficientes para que este possa tomar uma decisão final. Estes modelos, desenvolvidos para redes de estradas rurais, são também aplicáveis a outras redes de infraestruturas rurais, tais como, de fornecimento de água, de eletricidade e de telecomunicações. A implementação dos modelos nas redes de estradas rurais dos distritos de Gorkha e Lamjung do Nepal permitiu confirmara sua aplicabilidade. Verifica-se que os modelos propostos são mais práticos e realísticos no estudo de soluções de melhoramento e de desenvolvimento de redes de estradas rurais em regiões montanhosas de países em desenvolvimento.
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Esta tese apresenta um sistema de localização baseado exclusivamente em ultrassons, não necessitando de recorrer a qualquer outra tecnologia. Este sistema de localização foi concebido para poder operar em ambientes onde qualquer outra tecnologia não pode ser utilizada ou o seu uso está condicionado, como são exemplo aplicações subaquáticas ou ambientes hospitalares. O sistema de localização proposto faz uso de uma rede de faróis fixos permitindo que estações móveis se localizem. Devido à necessidade de transmissão de dados e medição de distâncias foi desenvolvido um pulso de ultrassons robusto a ecos que permite realizar ambas as tarefas com sucesso. O sistema de localização permite que as estações móveis se localizem escutando apenas a informação em pulsos de ultrassons enviados pelos faróis usando para tal um algoritmo baseado em diferenças de tempo de chegada. Desta forma a privacidade dos utilizadores é garantida e o sistema torna-se completamente independente do número de utilizadores. Por forma a facilitar a implementação da rede de faróis apenas será necessário determinar manualmente a posição de alguns dos faróis, designados por faróis âncora. Estes irão permitir que os restantes faróis, completamente autónomos, se possam localizar através de um algoritmo iterativo de localização baseado na minimização de uma função de custo. Para que este sistema possa funcionar como previsto será necessário que os faróis possam sincronizar os seus relógios e medir a distância entre eles. Para tal, esta tese propõe um protocolo de sincronização de relógio que permite também obter as medidas de distância entre os faróis trocando somente três mensagens de ultrassons. Adicionalmente, o sistema de localização permite que faróis danificados possam ser substituídos sem comprometer a operabilidade da rede reduzindo a complexidade na manutenção. Para além do mencionado, foi igualmente implementado um simulador de ultrassons para ambientes fechados, o qual provou ser bastante preciso e uma ferramenta de elevado valor para simular o comportamento do sistema de localização sobre condições controladas.
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The position of an item influences its evaluation, with research consistently finding that items occupying central locations are preferred and have a higher subjective value. The current study investigated whether this centre-stage effect (CSE) is a result of bottom-up gaze allocation to the central item, and whether it is affected by item valence. Participants (n=50) were presented with three images of artistic paintings in a row and asked to choose the image they preferred. Eye movements were recorded for a subset of participants (n=22). On each trial the three artworks were either similar but different, or were identical and with positive valence, or were identical and with negative valence. The results showed a centre-stage effect, with artworks in the centre of the row preferred, but only when they were identical and of positive valence. Significantly greater gaze allocation to the central and left artwork was not mirrored by equivalent increases in preference choices. Regression analyses showed that when the artworks were positive and identical the participants’ last fixation predicted preference for the central art-work, whereas the fixation duration predicted preference if the images were different. Overall the result showed that item valence, rather than level of gaze allocation, influences the CSE, which is incompatible with the bottom-up gaze explanation. We propose that the centre stage heuristic, which specifies that the best items are in the middle, is able to explain these findings and the centre-stage effect.
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The use of smartphones and tablets as become almost banal in these days. Smartphones, besides serving their main purpose of making and receiving calls, come to be one of the main equipments to obtain information from the Internet, using the commonly installed browsers or through the use of dedicated applications. Furthermore, several other devices are also very frequent to the majority of the modern smartphones and tablets in the market (e.g., GPS - Global Positioning System). This devices give the current systems a very high potential of usage. One example of applicability, comes from the wish to find and navigate to events or activities which are or will soon be occurring near the user. The LifeSpeeder platform is one of the first applications in the mobile equipment market of applications which take into consideration exactly what we have just outlined, i.e., a mobile and desktop application which allows the users to locate events according with their preferences and to get help navigating to them. In this paper we briefly describe the LifeSpeeder's front and back-end. © 2014 Springer International Publishing.
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This document shows the operations per year for airports in South Carolina broken down by air taxi, local, itin, military and totals.
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Les personnes atteintes de démence sévère, résidant dans un centre d’hébergement et de soins de longue durée (CHSLD) et approchant la fin de leur vie, ne reçoivent pas systématiquement des soins palliatifs, malgré que ce niveau de soins soit le plus approprié. La plupart de ces personnes reçoivent également un grand nombre de médicaments dont les effets indésirables peuvent contribuer à des souffrances évitables. Une approche axée sur les soins palliatifs serait possiblement associée à une réduction de la charge médicamenteuse et, du même coup, à une prescription plus appropriée. Les objectifs de ce projet de recherche étaient de décrire l’usage des médicaments chez les résidents atteints de démence sévère en CHSLD, de comparer leur usage de médicaments à des critères de pertinence et d’évaluer si la mise en œuvre d’une approche axée sur les soins palliatifs était associée aux médicaments prescrits. Cette étude décrit l’usage des médicaments chez 215 sujets atteints de démence sévère et en fin de vie qui ont participé à une étude d’intervention quasi expérimentale menée dans quatre CHSLD du Québec sur la mise en œuvre d’une approche axée sur les soins palliatifs. L’utilisation des médicaments a été comparée à trois listes de critères pertinents publiés, soit ceux de Holmes, Rancourt et Kröger, en utilisant des statistiques descriptives. Les analyses sur l’usage de 412 médicaments différents chez 120 sujets du groupe expérimental et 95 sujets du groupe témoin ont montré que cette approche axée sur les soins palliatifs n’est pas associée à une prescription plus appropriée des médicaments chez ces personnes particulièrement vulnérables.
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Tese de doutoramento, Estudos de Literatura e de Cultura (Estudos Ingleses), Universidade de Lisboa, Faculdade de Letras, 2014
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Allergies to grass pollen are the number one cause of outdoor hay fever. The human immune system reacts with symptoms to allergens from pollen. Objective: We investigated the natural variability in release of the major group 5 allergen from grass pollen across Europe. Methods: Airborne pollen and allergens were simultaneously collected daily with a volumetric spore trap and a high-volume cascade impactor at 10 sites across Europe for 3 consecutive years. Group 5 allergen was determined with a Phl p 5 specific ELISA in two fractions of ambient air: Particulate Matter (PM) >10μm and 10μm>PM>2.5μm. Mediator release by ambient air was determined in FcεR1-humanized basophils. Origin of pollen was modeled and condensed to pollen potency maps. Results: On average grass pollen released 2.3 pg Phl p 5/pollen. Allergen release per pollen (potency) varied substantially, ranging from 0 to 9 pg Phl p 5/pollen (5 to 95% percentile). The main variation was locally day-to-day. Average potency maps across Europe varied between years. Mediator release from basophilic granulocytes correlated better with allergen/m3 (r2=0.80, p<0.001) than with pollen/m3 (r2=0.61, p<0.001). In addition, pollen released different amounts of allergen in the nonpollen bearing fraction of ambient air depending on humidity. Conclusion: Across Europe, the same amount of pollen released substantially different amounts of group 5 grass pollen allergen. This variation in allergen release is on top of variations in pollen counts. Molecular aerobiology, i.e. determining allergen in ambient air, may be a valuable addition to pollen counting.
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This paper presents a novel technique for the design of narrow-band sigma-delta modulators with an embedded tunable centre frequency mechanism. This method demonstrates that the use of sum filters combined with a fractional delayer provide the flexibility of tuning the noise shaping band for any desired variable centre frequency input signal.
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This paper proposes a computationally efficient methodology for the optimal location and sizing of static and switched shunt capacitors in large distribution systems. The problem is formulated as the maximization of the savings produced by the reduction in energy losses and the avoided costs due to investment deferral in the expansion of the network. The proposed method selects the nodes to be compensated, as well as the optimal capacitor ratings and their operational characteristics, i.e. fixed or switched. After an appropriate linearization, the optimization problem was formulated as a large-scale mixed-integer linear problem, suitable for being solved by means of a widespread commercial package. Results of the proposed optimizing method are compared with another recent methodology reported in the literature using two test cases: a 15-bus and a 33-bus distribution network. For the both cases tested, the proposed methodology delivers better solutions indicated by higher loss savings, which are achieved with lower amounts of capacitive compensation. The proposed method has also been applied for compensating to an actual large distribution network served by AES-Venezuela in the metropolitan area of Caracas. A convergence time of about 4 seconds after 22298 iterations demonstrates the ability of the proposed methodology for efficiently handling large-scale compensation problems.
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Distributed generation unlike centralized electrical generation aims to generate electrical energy on small scale as near as possible to load centers, interchanging electric power with the network. This work presents a probabilistic methodology conceived to assist the electric system planning engineers in the selection of the distributed generation location, taking into account the hourly load changes or the daily load cycle. The hourly load centers, for each of the different hourly load scenarios, are calculated deterministically. These location points, properly weighted according to their load magnitude, are used to calculate the best fit probability distribution. This distribution is used to determine the maximum likelihood perimeter of the area where each source distributed generation point should preferably be located by the planning engineers. This takes into account, for example, the availability and the cost of the land lots, which are factors of special relevance in urban areas, as well as several obstacles important for the final selection of the candidates of the distributed generation points. The proposed methodology has been applied to a real case, assuming three different bivariate probability distributions: the Gaussian distribution, a bivariate version of Freund’s exponential distribution and the Weibull probability distribution. The methodology algorithm has been programmed in MATLAB. Results are presented and discussed for the application of the methodology to a realistic case and demonstrate the ability of the proposed methodology for efficiently handling the determination of the best location of the distributed generation and their corresponding distribution networks.
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Fingerprinting is an indoor location technique, based on wireless networks, where data stored during the offline phase is compared with data collected by the mobile device during the online phase. In most of the real-life scenarios, the mobile node used throughout the offline phase is different from the mobile nodes that will be used during the online phase. This means that there might be very significant differences between the Received Signal Strength values acquired by the mobile node and the ones stored in the Fingerprinting Map. As a consequence, this difference between RSS values might contribute to increase the location estimation error. One possible solution to minimize these differences is to adapt the RSS values, acquired during the online phase, before sending them to the Location Estimation Algorithm. Also the internal parameters of the Location Estimation Algorithms, for example the weights of the Weighted k-Nearest Neighbour, might need to be tuned for every type of terminal. This paper focuses both approaches, using Direct Search optimization methods to adapt the Received Signal Strength and to tune the Location Estimation Algorithm parameters. As a result it was possible to decrease the location estimation error originally obtained without any calibration procedure.
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The current ubiquitous network access and increase in network bandwidth are driving the sales of mobile location-aware user devices and, consequently, the development of context-aware applications, namely location-based services. The goal of this project is to provide consumers of location-based services with a richer end-user experience by means of service composition, personalization, device adaptation and continuity of service. Our approach relies on a multi-agent system composed of proxy agents that act as mediators and providers of personalization meta-services, device adaptation and continuity of service for consumers of pre-existing location-based services. These proxy agents, which have Web services interfaces to ensure a high level of interoperability, perform service composition and take in consideration the preferences of the users, the limitations of the user devices, making the usage of different types of devices seamless for the end-user. To validate and evaluate the performance of this approach, use cases were defined, tests were conducted and results gathered which demonstrated that the initial goals were successfully fulfilled.