65,741 research outputs found
Design method for adsorption beds
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
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
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
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
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
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
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?
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
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
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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