65,741 research outputs found

    Design method for adsorption beds

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    Regenerable adsorption beds for long-term life support systems include synthetic geolite to remove carbon dioxide and silica gel to dehumidify the atmospheric gas prior to its passage through the geolite beds. Bed performance is evaluated from adsorption characteristics, heat and mass transfer, and pressure drop

    The community health apprentices project-the outcomes of an intermediate labour market project in the community health sector

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    This paper reports on the outcomes of the Community Health Apprentices Project, an intermediate labour market (ILM) project delivered in two neighbouring areas of Bradford, England. The project was illustrative of current UK policy in its attempt to both address unemployment and health inequalities. The aim of the paper is to improve understanding of the type and range of outcomes that can result from ILM projects based in the community health sector. A qualitative evaluation was undertaken and interviews were carried out with three groups of stakeholders: the community health apprentices, key informants in the placement organisations and the delivery partners. Findings show that both anticipated and unanticipated outcomes occurred in relation to increased skills for work, improved health and well-being and improved organisational capacity. While there are contextual factors which make this project unique, the findings illustrate the potential range of outcomes that can be achieved when social and emotional support is offered in tandem with work experience. The findings further highlight the organisational benefits of investing in local people to deliver community health work. The paper concludes that in order to build an evidence base for ILM approaches, a broader understanding of outcomes needs to be developed, taking into account social and health outcomes as well as economic indicators

    Hypersonic structures: An aerodynamicist's perspective, or one man's dream is another man's nightmare

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    The relationship between hypersonic aerodynamic and structural design is reviewed. The evolution of the hypersonic vehicle design is presented. Propulsion systems, structural materials, and fuels are emphasized

    A research program to reduce the interior noise in general aviation aircraft, index and summary

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    This report is an index of the published works from NASA Grant NSG 1301, entitled A Research Program to Reduce the Interior Noise in General Aviation Aircraft. Included are a list of all published reports and papers, a compilation of test specimen characteristics, and summaries of each published work

    Exchange Bias driven by Dzyaloshinskii-Moriya interactions

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    The exchange bias effect in compensated IrMn3/Co(111) system is studied using multiscale modeling from "ab initio" to atomistic calculations. We evaluate numerically the out-of-plane hysteresis loops of the bi-layer for different thickness of the ferromagnetic layer. The results show the existence of a perpendicular exchange bias field and an enhancement of the coercivity of the system. In order to elucidate the possible origin of the exchange bias, we analyze the hysteresis loops of a selected bi-layer by tuning the different contributions to the exchange interactions across the interface. Our results indicate that the exchange bias is primarily induced by the Dzyaloshinskii-Moriya interactions, while the coercivity is increased mainly due to a spin-flop mechanism

    Proca equations derived from first principles

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    Gersten has shown how Maxwell equations can be derived from first principles, similar to those which have been used to obtain the Dirac relativistic electron equation. We show how Proca equations can be also deduced from first principles, similar to those which have been used to find Dirac and Maxwell equations. Contrary to Maxwell equations, it is necessary to introduce a potential in order to transform a second order differential equation, as the Klein-Gordon equation, into a first order differential equation, like Proca equations.Comment: 6 page

    Single parameter testing application

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    Single parameter testing with growing exponential signals applied to servo loop controlling arm position on X-Y plotte

    Thermal infrared research: Where are we now?

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    The use of infrared temperatures in agriculture and hydrology is based on the energy balance equation which is used to estimate evapotranspiration and crop stress over small areas within a field as well as large areas. For its full utilization, this measurement must be combined with other spectral data collected at a time resolution sufficient to detect changes in the agricultural or hydrological systems and at a spatial resolution with enough detail to sample within individual fields. The most stringent requirement is that the data be readily available to the user. The spatial resolution necessary for IR measurements to be incorporated into evapotranspiration models to accurately estimate field and regional transpiration or measure crop stress; methods to estimate crop stress and yield over large areas and different cultivars within a species; the temporal resolution adequate for detecting crop stress or inclusion in evapotranspiration models; and ancillary parameters for estimating thermal IR measurements must be investigated

    Towards a bulk theory of flexoelectricity

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    Flexoelectricity is the linear response of polarization to a strain gradient. Here we address the simplest class of dielectrics, namely elemental cubic crystals, and we prove that therein there is no extrinsic (i.e. surface) contribution to flexoelectricity in the thermodynamic limit. The flexoelectric tensor is expressed as a bulk response of the solid, manifestly independent of surface configurations. Furthermore, we prove that the flexoelectric responses induced by a long-wavelength phonon and by a uniform strain gradient are identical.Comment: 5 pages, 1 figure (2 panels

    Local field effect as a function of pulse duration

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    In this note we give semiclassical consideration of the role of pulse duration in observation of local field effects in the regime of optical switching. We show that the main parameter governing local field influence is the ratio of peak Rabi frequency corresponding to medium inversion and Lorentz frequency of the medium. To obtain significant local field effect, this parameter should be near unity that is valid only for long enough pulses. We also discuss the role of relaxation and pulse shape in this processes.Comment: 4 pages, 3 figure
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