Browsing by Issue Date, starting with "2011-10"
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- Educação e Diversidade Cultural: Notas de Antropologia da EducaçãoPublication . Vieira, Ricardo
- Problematiche di Modellazione nella Valutazione Sismica delle Strutture EsistentiPublication . Sousa, Romain; Bianchi, F.; Nascimbene, Roberto; Pinho, RuiProblemi di modellazione per l’analisi sismica delle strutture esistenti Molti edifici in c.a. del patrimonio edilizio esistente sono stati progettati per i soli carichi verticali, presentando un’inadeguata resistenza ai carichi laterali e scarsi dettagli costruttivi. Inoltre, il concetto di regolarità in pianta e in elevazione, tipico di una buona progettazione sismica, spesso è stato trascurato. Per valutare il comportamento sismico di tali edifici, alcune recenti normative in materia sismica - quali l’EC8 e le NTC08 - hanno introdotto diverse prescrizioni sulle tipologie di analisi, le distribuzioni di carico, l’eccentricità accidentale, ecc., lasciando, però, ai progettisti piena autonomia a proposito delle strategie di modellazione (es. impalcati, tamponamenti verticali, tipologia di elementi finiti, masse, ecc.). L’obiettivo del presente lavoro è quello di stimare, tramite l’esecuzione di analisi non-lineari (statiche e dinamiche) per un edificio reale, l’influenza di tali strategie nella valutazione sismica delle strutture, al fine di fornire indicazioni sull’importanza di ogni scelta progettuale.
- A divulgação da informação socialmente responsável nos estabelecimentos hoteleiros portuguesesPublication . Ferraz, Francisco António Vaz Guedes Delgado; Schön, Michael; Vázquez, Dolores GallardoAs organizações têm vindo a manifestar uma maior consciência a nível económico, social e ambiental, procurando minimizar problemas com que a sociedade se debate de uma forma sistemática, numa lógica de sustentabilidade e de longo prazo. Para esse efeito, procuram desenvolver um conjunto de iniciativas que implica a adopção de comportamentos coerentes e transparentes com objectivos de criação de valor, não apenas para a organização mas também para com todos aqueles com os quais a mesma se relaciona. Nesta óptica, a divulgação da sua actuação socialmente responsável, assume um papel importante como instrumento de Marketing Relacional com os seus Stakeholders, uma vez que numa perspectiva de longo prazo potenciará vantagens competitivas às organizações que as fomentem. Neste documento, pretende-se efectuar uma análise sobre a divulgação da diversa informação sobre Responsabilidade Social no sector Turístico Português baseando-se a mesma num estudo empírico realizado aos estabelecimentos hoteleiros classificados de três a cinco estrelas.
- Preparation and Characterization of Films Based on Alginate and Aloe VeraPublication . Brás Pereira, Rúben Filipe; Tojeira, Ana; Barroso de Moura Cipreste Vaz, Daniela; Mendes, Ausenda; Bartolo, Paulo; Mendes, AusendaSodium alginate films with aloe vera extract were prepared by the casting/solvent evaporation technique. The resulting films were characterized by differential scanning calorimetry, Fourier transform-infrared spectroscopy, scanning electron microscopy, and mechanical and water absorption tests. The in vitro degradation of the films was also investigated over 14 days. Results show that aloe vera contributes to both enhancing the thermal and mechanical properties of the films and decreasing the weight loss during in vitro degradation.
- An instantaneous regulation for the wired and wireless super-resonant convertersPublication . Valtchev, Stanimir; Medeiros, Rui; Valtchev, Svilen S.; Klaassens, BenThe paper develops further the method presented in [12], [14], based on energy balance in the resonant tank. This method allows a stable operation of the switches and a higher efficiency of any Series Loaded Series Resonant (SLSR) power converter, especially when contactless energy transfer is concerned. The strategy is based on guaranteeing the correct portion of energy transported by the resonant tank to the load. The portion has to vary corresponding to the error signal taken from the output voltage and remains unchanged if the error signal from the output is at its minimum. In a certain way this method is similar to the Current Mode Control of the classical power converters.
- An iterative pilot-data aided estimator for OFDM-based relay-assisted systemsPublication . Neves, D.; Ribeiro, Carlos; Silva, A.; Gameiro, A.We propose and assess a pilot-data aided channel estimation scheme for realistic relay-assisted scenarios designed for the downlink SFBC OFDM-based systems. We consider that both the base station and the relay node are equipped with an antenna array whereas the user terminal is a single antenna device. The relay protocol considered is equalise-and-forward. The channel estimation method iteratively uses the information carried by the pilots and data to improve the estimate of the equivalent channels for the path Base Station - Relay Node - User Terminal. The MMSE criterion is used in the design of the estimator for both the pilot-based and data-aided iterations. The results show the benefits of cooperation in terms of MSE and also show that the proposed scheme allows, with a single data iteration, a reduction of the number of pilots when compared with non-data-aided schemes.
- Genetic and local search algorithms applied to balanced communication networksPublication . Bernardino, Eugénia; Moreira Bernardino, Anabela; Sánchez-Pérez, Juan M.; Gómez-Pulido, Juan A.; Vega-Rodríguez, Miguel A.In this paper we describe the application of different heuristics to optimise large communication networks. We use Iterated Local Search (ILS), Tabu Search (TS), Simulated Annealing (SA) and Genetic Algorithm (GA) to minimise the link cost to form balanced communication networks. This paper makes a comparison among the effectiveness of ILS, TS, SA and GA on solving large communication networks. Simulation results verify the effectiveness of these algorithms.
- Using a hybrid honey bees mating optimisation algorithm for solving SONET/SDH design problemsPublication . Moreira Bernardino, Anabela; Bernardino, Eugénia; Sánchez-Pérez, Juan M.; Gómez-Pulido, Juan A.; Vega-Rodríguez, Miguel A.In this paper we propose a hybrid Honey Bees Mating Optimisation (HBMO) algorithm to solve two problems that arise in the design of optical telecommunication networks known as SONET/SDH Ring Assignment Problem (SRAP) and Intraring Synchronous Optical Network Design Problem (IDP). In SRAP the objective is to minimise the number of rings. In IDP the objective is to minimise the number of Add-Drop Multiplexers (ADMs). Both problems are subject to a ring capacity constraint. HBMO algorithm simulates the mating process of real honey bees. We apply a hybridisation of HBMO to solve these two combinatorial optimisation problems. The feasibility of Hybrid HBMO is demonstrated and compared with the solutions obtained by other algorithms from literature.