140 research outputs found

    Cell for electrolysis of water vapor

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    Electrolytic cells regenerate oxygen from the water vapor in the air of closed-loop life-support system and remove water vapor from air circulated through them. Water is converted into oxygen and hydrogen; the oxygen is returned to the air, the hydrogen is vented or used elsewhere

    Instrumentation, control and data management for the MIST (Modular Integrated Utility System) Facility

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    An appendix providing the technical data required for computerized control and/or monitoring of selected MIST subsystems is presented. Specific computerized functions to be performed are as follows: (1) Control of the MIST heating load simulator and monitoring of the diesel engine generators' cooling system; (2) Control of the MIST heating load simulator and MIST heating subsystem including the heating load simulator; and (3) Control of the MIST air conditioning load simulator subsystem and the MIST air conditioning subsystem, including cold thermal storage and condenser water flows

    EXP-Crowd: A Gamified Crowdsourcing Framework for Explainability

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    The spread of AI and black-box machine learning models made it necessary to explain their behavior. Consequently, the research field of Explainable AI was born. The main objective of an Explainable AI system is to be understood by a human as the final beneficiary of the model. In our research, we frame the explainability problem from the crowds point of view and engage both users and AI researchers through a gamified crowdsourcing framework. We research whether it's possible to improve the crowds understanding of black-box models and the quality of the crowdsourced content by engaging users in a set of gamified activities through a gamified crowdsourcing framework named EXP-Crowd. While users engage in such activities, AI researchers organize and share AI- and explainability-related knowledge to educate users. We present the preliminary design of a game with a purpose (G.W.A.P.) to collect features describing real-world entities which can be used for explainability purposes. Future works will concretise and improve the current design of the framework to cover specific explainability-related needs

    Hydrogen storage in MgH2 matrices: A study of Mg-MgH2 interface using CPMD code on ENEA-GRID

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    The remarkable ability of magnesium to store significant quantities of hydrogen, in the form (MgH2), has fostered intense research efforts in the last years in view of its future applications where light and safe hydrogen-storage media are needed. However, further research is needed since Mg has a high operation temperature and slow absorption kinetics that prevent for the moment the use in practical applications. To improve and optimize the performances of this material a detailed knowledge of the hydrogen diffusion mechanism at the atomic level is needed. Experiments can only provide indirect evidences of the atomic rearrangement during the desorption process. For these reasons a detailed computational study of MgH2 is invoked to characterize the dynamics of hydrogen during desorption. Further insights are gained by characterizing the Mg-MgH2 interface which is supposed to play a major role in the hydrogen diffusion during absorption and desorption cycles. By means of accurate ab initio molecular dynamics simulations based on the density-functional theory with norm-conserving pseudopotentials and plane-wave expansion (CPMD code) an interface is designed and studied. Extensive electronic structure calculations are used to characterize the equilibrium properties and the behavior of the surfaces in terms of total energy considerations and atomic diffusion

    Vibrational Properties of Nanoscale Materials: From Nanoparticles to Nanocrystalline Materials

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    The vibrational density of states (VDOS) of nanoclusters and nanocrystalline materials are derived from molecular-dynamics simulations using empirical tight-binding potentials. The results show that the VDOS inside nanoclusters can be understood as that of the corresponding bulk system compressed by the capillary pressure. At the surface of the nanoparticles the VDOS exhibits a strong enhancement at low energies and shows structures similar to that found near flat crystalline surfaces. For the nanocrystalline materials an increased VDOS is found at high and low phonon energies, in agreement with experimental findings. The individual VDOS contributions from the grain centers, grain boundaries, and internal surfaces show that, in the nanocrystalline materials, the VDOS enhancements are mainly caused by the grain-boundary contributions and that surface atoms play only a minor role. Although capillary pressures are also present inside the grains of nanocrystalline materials, their effect on the VDOS is different than in the cluster case which is probably due to the inter-grain coupling of the modes via the grain-boundaries.Comment: 10 pages, 7 figures, accepted for publication in Phys. Rev.

    The SEEMP Approach to Semantic Interoperability for E-Employment

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    SEEMP is a European Project that promotes increased partnership between labour market actors and the development of closer relations between private and public employment services, making optimal use of the various actors’ specific characteristics, thus providing job-seekers and employers with better services. The need for a flexible collaboration gives rise to the issue of interoperability in both data exchange and share of services. SEEMP proposes a solution that relies on the concepts of services and semantics in order to provide a meaningful service-based communication among labour market actors requiring a minimal shared commitment

    VARIAÇÃO ESPACIAL DE SULFETOS VOLÁTEIS ACIDIFICADOS E BIODISPONIBILIDADE DE METAIS EXTRAÍDOS SIMULTANEAMENTE EM SEDIMENTOS AO NORTE DA BAÍA DE TODOS OS SANTOS, BAHIA.

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    A distribuição espacial de sulfetos volatilizáveis em ácido (SVA) e metais (Cd, Cu, Pb, Ni e Zn) extraídos simultaneamente (MES) no substrato lamoso do sedimento de manguezal na porção norte da Baía de Todos os Santos (Bahia-Brasil) foram estudados em oito estações sob possível efeito urbano, industrial e portuário. O SVA foi extraído do sedimento anaeróbio com ácido clorídrico 1 mol L-1, a frio, enquanto os metais extraídos simultaneamente (MES) bivalentes são liberados. Não houve diferença estatística entre as estações. A razão MES/SVA, correlacionaram-se com as frações granulométricas, matéria orgânica (3.5%), carbono orgânico total (2.4%), nitrogênio total (0.25%), metais (mg Kg-1): Cd, Cu, Pb, Ni e Zn.  Comparando-se com valores de referência internacionais estão abaixo dos limites estabelecidos, mesmo em outras regiões do Brasil. Os valores < 1 para a relação [MES]/[SVA], sugere a não disponibilidade desses metais, o que indicam a ausência de efeitos adversos à biota
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