JaSkel: a java skeleton-based framework for structured cluster and grid computing

This paper presents JaSkel, a skeleton-based framework to develop parallel and grid applications. The framework provides a set of Java abstract classes as a skeleton catalogue, which implements recurring parallel interaction paradigms. This approach aims to improve code efficiency and portability. It also helps to structure scalable applications through the refinement and composition of skeletons. Evaluation results show that using the provided skeletons do contribute to improve both application development time and execution performanceFundação para a Ciência e a Tecnologia (FCT) - PPC-VM Project(POSI/CHS/47158/2002); Project SeARCH (contract REEQ/443/2001)

Study of the leaching process of precious metals from waste electrical and electronic equipment

The development of modern society is anchored in the advancement of technology, and as a collateral consequence, waste from electrical and electronic equipment (WEEE) is increasing rapidly. This alarming trend poses a serious concern for the depletion of our planet's resources, as the extraction of elements such as metals from the Earth's crust intensifies, pollution and stress on ecosystems increases. Nevertheless, WEEE still hold significant potential, particularly in recycling valuable elements like precious metals and base metals. Recycling these materials can offer substantial economic and environmental benefits, making it a crucial aspect in the circular economy. Common processes for metal recovery from WEEE often rely on classic establish techniques such as pyrometallurgy, which raises concerns about energy consumption and pollution, or classic hydrometallurgy, using aggressive solvents harmful to humans and the environment leading stakeholders to seek alternatives, more eco-friendly lixiviants to ensure sustainable and responsible metal recovery. The work intended to shed some light in the leaching ability of more sustainable agents on printed circuit boards (PCB) and compare their efficiency in the leaching process with classical approaches. Silver recovery from Printed Circuit Boards (PCBs) using thiourea, thiosulfate and sulfuric acid as leaching agents, was studied to compare the effectiveness of alternative leaching agents and validate the methodology. Quantification was performed by Inductively Coupled Plasma-Atomic Emission Spectroscopy and AAS atomic absorption spectroscopy. Sulfuric acid as predicted was the most effective lixiviant (99,7% yield) followed by Ammonium thiosulfate (72,5% yield) on silver powder samples. In PCBs and complex samples, the use of thiosulfate and thiourea solutions for silver extraction, under the tested conditions, did not show promising results, requiring more studies

Agent based approaches for smart charging strategy for electric vehicles

This paper presents an agent process simulation to control and monitor the Electric Vehicle charging process, using existing power distribution limitations and microgeneration capacity. The goal is to simulate the consumers’ energy consumption and their unexpected behavior, using past experience and taking into account distribution network and home power limitation to find an intelligent charging pattern. This paper proposes a novel approach for this problem based on an agent-based simulation platform where stochastic process is adopted to perform unexpected user behavior. This simulation tool can be used to determine the capability of the actual electrical distribution network for supply energy to the final consumers and for charge the bank of batteries of electrical vehicles, which can occur simultaneously.Fundação para a Ciência e a Tecnologia (FCT) - Project MIT-PT/EDAM-SMS/0030/2008.MIT-Portugal Progra

A note on the evaluation of a storage system using an elementary renewal equation

We consider a storage system where a stock of k units is replaced instantaneously, when needed. A Poisson type stochastic demand is admitted. It is verified that the expected present value function of the replenishment cost of the storage system satisfies a defective renewal equation for which an asymptotic expansion is proposed

Resources dynamics from the point of view of the regenerated ornstein-uhlenbeck model

We consider the problem of assessing resources dynamics in the context of an economic system subject to Gaussian consumption and deterministic productivity. A discrete time recursive equation is presented to justify the use of the Ornstein-Uhlenbeck diffusion process. Under assumptions about regeneration of the process, we observe the system equilibrium as to what concerns resources depreciation or accumulatio

Shortcut fusion rules for the derivation of circular and higher-order programs

Functional programs often combine separate parts using intermediate data structures for communicating results. Programs so defined are modular, easier to understand and maintain, but suffer from inefficiencies due to the generation of those gluing data structures. To eliminate such redundant data structures, some program transformation techniques have been proposed. One such technique is shortcut fusion, and has been studied in the context of both pure and monadic functional programs. In this paper, we study several shortcut fusion extensions, so that, alternatively, circular or higher-order programs are derived. These extensions are also provided for effect-free programs and monadic ones. Our work results in a set of generic calculation rules, that are widely applicable, and whose correctness is formally established.Fundação para a Ciência e a Tecnologi

Métodos estatísticos para recuperação de informação

É abordado o problema dos modelos de recuperação de informação, sob o ponto de vista estatístico, no sentido de estabelecer relações entre os diferentes algoritmos e apresentar uma visão unificada dos diferentes modelos com base em métodos estatísticos. É proposta uma notação comum para os mesmos conceitos apresentados por modelos diferentes evitando-se assim a grande diversidade das notações existentes, identificando-se os requisitos para um índice flexível capaz de fornecer matéria-prima para todos os modelos de pesquisa com base nas propriedades estatísticas dos documentos.info:eu-repo/semantics/publishedVersio

Combinação de métodos para pesquisa de informação

Pretende-se investigar diversos caminhos para combinar métodos de pesquisa por forma a melhorar o desempenho dos sistemas, oferecendo uma nova perspectiva da investigação dos sistemas de pesquisa, à descoberta da melhor estratégia, propondo um método de combinação baseado na combinação de três modelos: Textual, ligações e de classificação.info:eu-repo/semantics/publishedVersio

Efeitos da exposição a radiação eletromagnética na função testicular e reprodutiva

A infertilidade constitui um problema grave na sociedade moderna, e o aumento da sua prevalência surge da interação complexa entre um conjunto de fatores sociais, comportamentais e biológicos. Um em cada 6 casais tem dificuldades em conceber uma gestação, e em cerca de 50% dos casais afetados o fator masculino constitui agente causal, quer primário quer associado a condições femininas. Considerando a fertilidade masculina, é um facto que a incidência de espermatogénese irregular está a aumentar devido a fatores ambientais e relacionados com o estilo de vida. De entre estes fatores, destaca-se o crescente uso de telemóveis, cujo número de utilizadores continua a aumentar a nível global. O aumento exponencial na utilização de telemóveis é acompanhado por uma preocupação crescente em relação aos seus possíveis efeitos prejudiciais na saúde humana. Vários autores defendem que a radiação eletromagnética emitida pelos telemóveis, e respetivas antenas, pode prejudicar a fertilidade. O sistema reprodutor masculino é altamente complexo e sensível a fatores intrínsecos e extrínsecos, e a radiação eletromagnética emitida pelos telemóveis pode ter efeitos nefastos na espermatogénese, reduzindo a fertilidade masculina. O objetivo da presente tese é realizar uma revisão sistemática da literatura sobre os mecanismos fisiopatológicos envolvidos nos efeitos das radiações eletromagnéticas emitidas pelos telemóveis na estrutura e função testicular, através da análise de estudos realizados em modelos humanos e animais. Nos estudos em humanos baseados na comparação dos parâmetros do esperma entre homens que usam telemóvel e homens que não usam, destacaram-se a redução na mobilidade (principalmente nos espermatozoides rapidamente progressivos), e a alteração da morfologia. Nos estudos em humanos assentes na confrontação dos parâmetros do esperma entre amostras expostas às radiações eletromagnéticas dos telemóveis e amostras de controlo, ambas provenientes do mesmo indivíduo, evidenciaram-se a diminuição na mobilidade, a quebra na viabilidade e o aumento na produção de espécies reativas de oxigénio. Nos estudos em animais sobressaíram a diminuição da mobilidade, o decréscimo na concentração do esperma e o incremento na geração de espécies reativas de oxigénio. No cômputo dos estudos em modelos humanos e modelos animais, destaca-se a mobilidade dos espermatozoides, que constituiu a característica negativamente afetada de forma mais consistente pelas radiações eletromagnéticas dos telemóveis. Mais estudos devem ser realizados, e estes devem reunir entre si uma maior homogeneidade, de forma que os dados obtidos sejam mais consistentes e fiáveis, no intuito de revelar a real influência das radiações eletromagnéticas dos telemóveis na fertilidade masculina.Infertility is a serious problem in modern society, and the increase in its prevalence arises from the complex interaction between a range of social, behavioral and biological factors. One in six couples has difficulty to conceive, and in about 50% of affected couples the male factor is the causal agent, either primary or associated with female conditions. Considering male fertility, it is a fact that the incidence of irregular spermatogenesis is increasing due to environmental and lifestyle related factors. Among these factors stands out the growing use of mobile phones whose number of users continues to increase globally. The exponential increase in mobile phone use is accompanied by a growing concern over its possible adverse effects on human health. Several authors argue that electromagnetic radiation emitted by mobile phones and their antennas, can impair fertility. The male reproductive system is highly complex and sensitive to intrinsic and extrinsic factors, and electromagnetic radiation emitted by mobile phones can have deleterious effects on spermatogenesis, reducing male fertility. The aim of this study is to conduct a systematic literature review on the pathophysiological mechanisms involved in the effects of electromagnetic radiation emitted by mobile phones in testicular structure and function, through analysis of studies in human and animal models. In human studies based on a comparison of sperm parameters between men that use mobile phone and men who do not use, the main alterations were the decreased mobility (especially in rapidly progressive spermatozoa) and the altered morphology. In human studies based on a comparison of sperm parameters between sperm samples exposed to electromagnetic radiation from mobile phones and control samples, both from the same individual, the main alterations were the decreased mobility, the declined viability and the increased production of reactive oxygen species. In animal studies the main alterations were the decreased mobility, the decreased sperm concentration and the increased generation of reactive oxygen species. Considering all human and animal studies, sperm mobility was the most consistently affected parameter by the mobile phone electromagnetic radiation. More studies are needed, and these should be more homogeneous to obtained more consistent and reliable data, in order to reveal the real influence of mobile phone electromagnetic radiation on male fertility