21,569 research outputs found

    Electron beam parallel X-ray generator

    Get PDF
    Broad X ray source produces a highly collimated beam of low energy X rays - a beam with 2 to 5 arc minutes of divergence at energies between 1 and 6 keV in less than 5 feet. The X ray beam is generated by electron bombardment of a target from a large area electron gun

    Optimizations of Human Restraint Systems for Short-Period Acceleration

    Get PDF
    A restraint system's main function is to restrain its occupant when his vehicle is subjected to acceleration. If the restraint system is rigid and well-fitting (to eliminate slack) then it will transmit the vehicle acceleration to its occupant without modifying it in any way. Few present-day restraint systems are stiff enough to give this one-to-one transmission characteristic, and depending upon their dynamic characteristics and the nature of the vehicle's acceleration-time history, they will either magnify or attenuate the acceleration. Obviously an optimum restraint system will give maximum attenuation of an input acceleration. In the general case of an arbitrary acceleration input, a computer must be used to determine the optimum dynamic characteristics for the restraint system. Analytical solutions can be obtained for certain simple cases, however, and these cases are considered in this paper, after the concept of dynamic models of the human body is introduced. The paper concludes with a description of an analog computer specially developed for the Air Force to handle completely general mechanical restraint optimization programs of this type, where the acceleration input may be any arbitrary function of time

    Development of lithium diffused radiation resistant solar cells Final report

    Get PDF
    Fabrication and analysis of lithium diffused radiation resistant solar cell

    Part specification solar cells, silicon N-on-P solderless low temperature operation for Jupiter missions

    Get PDF
    The requirements for 10 ohm cm N-ON-P, silicon solar cells, for use on solar panel assemblies for space flight applications are specified

    Development and pilot line production of lithium doped silicon solar cells

    Get PDF
    Scaling up the BCl3 without O2 diffusion beyond 30 to 40 cells was investigated by using a 100 cell capacity diffusion boat which held the cells vertically. Sheet resistances and I-V curves were uniform with 10 to 20 cells spaced along the entire boat, so the quantity was increased to 40 and then 60 cells per diffusion. There was no change in cell output and uniformity going from 20 to 40 cells per diffusion; however only half the lithium cells fabricated from slices diffused in the 60 cell diffusion had efficiencies of 11% or better. Although uniform sheet resistances and I-V characteristic curves were obtained with up to 60 cells in the BCl3 with O2 diffusion, the short circuit currents were approximately 15% lower than the anticipated 135 to 140 mA. Consequently, work on this diffusion process has been aimed solely at increasing the short circuit current. The diffusion temperature was lowered from 1055 to 1000 and 950 C, and at each of these temperatures variations in diffusion time were investigated. At 1000 C short circuit currents were approximately 10 mA higher, 130 rather than 120 mA average

    Development of lithium diffused radiation resistant solar cells Third quarterly report

    Get PDF
    Development of boron diffusion process to diffuse large quantities of stress-free, high efficiency, radiation resistant solar cell

    Development of lithium diffused radiation resistant solar cells, part 1 Final report, 17 Jun. 1969 - 19 Jun. 1970

    Get PDF
    Development of lithium diffused radiation resistant solar cell

    A lower bound to the spectral threshold in curved tubes

    Full text link
    We consider the Laplacian in curved tubes of arbitrary cross-section rotating together with the Frenet frame along curves in Euclidean spaces of arbitrary dimension, subject to Dirichlet boundary conditions on the cylindrical surface and Neumann conditions at the ends of the tube. We prove that the spectral threshold of the Laplacian is estimated from below by the lowest eigenvalue of the Dirichlet Laplacian in a torus determined by the geometry of the tube.Comment: LaTeX, 13 pages; to appear in R. Soc. Lond. Proc. Ser. A Math. Phys. Eng. Sc

    Promoting green issues and sustainability in UK higher education libraries

    Get PDF
    Climate change affects us all. Individually and collectively, we must reduce our carbon footprint to protect the future of the planet. But how can higher education libraries contribute? In April of 2007, a request was made to SCONUL libraries – via LIS-SCONUL – for information on library green initiatives that they were taking forward. The responses highlighted that there is growing interest in the issue and that sustainability issues are beginning to be taken very seriously. This is partially driven by the greater awareness of the need to reduce carbon emissions throughout society. Specifically within higher education, it is also a result of encouragement by funding bodies, such as the Higher Education Funding Council for England (HEFCE) (see http://www.hefce. ac.uk/lgm/sustain/), through pressure from groups such as People and Planet and their ‘green league’ of higher education institutions (http:// peopleandplanet.org/gogreen/greenleague2007), and through rewards for excellence such as the Times Higher Education and Higher Education Academy Awards for an outstanding contribution by a higher education institution to sustainable development. Library staff are often active in wider institutional sustainability initiatives and can act as ‘champions’ for environmental issues and initiatives. Most of the libraries that responded to the request for information have aligned their green initiatives/ policies with those of their host organisation. Some libraries have participated in a wider institutional initiative to apply for the environmental management standard, ISO 14001. However, there are many specific ways that libraries can become more environmentally friendly and can make a difference

    The gender and access to health services study: final report

    Get PDF
    Men and women frequently think and behave differently. To observe this is not to suggest anything so absurdly simple as that there are only male and female ways of being; behaviours and thought processes vary according to numerous other factors besides gender. That this is very generally the case however, does mean that there are broad - and often broadly predictable - differences in the way men and women engage with the world. Most commercial organisations understand this very well and plan accordingly. Many public authorities recognise it too and take these differences into account when developing and providing services. For historical reasons however the NHS has rarely done so. It is widely known that there are differences between men and women in the incidence and prevalence of most health conditions. Sometimes there are clear biological reasons for these differences but often there are not. Where biology offers little or no enlightenment, other questions need to be asked: · Do men and women behave in ways that predispose them to particular health conditions to different degrees? · Do men and women use health services with different degrees of effectiveness? · Do men and women receive differerent kinds of service from the NHS? The answer is – yes, these things happen frequently. This is sometimes to the disadvantage of one sex and sometimes to the disadvantage of the other. Sometimes it is to the disadvantage of both. And when these things happen, health outcomes are often affected. This report looks at the reasons why gender is such an important and fundamental determinant of health status and considers the ways in which gender inequalities can be tackled within the present legislative and policy framework. It also brings together the knowledge and evidence in relation to six specific areas of health concerns
    corecore