19,459 research outputs found

    Analysis and evaluation in the production process and equipment area of the low-cost solar array project

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    The attributes of the various metallization processes were investigated. It is shown that several metallization process sequences will lead to adequate metallization for large area, high performance solar cells at a metallization add on price in the range of 6.to12.msquared,or4to6. to 12. m squared, or 4 to .8/W(peak), assuming 15% efficiency. Conduction layer formation by thick film silver or by tin or tin/lead solder leads to metallization add-on prices significantly above the $6. to 12/m squared range c.) The wet chemical processes of electroless and electrolytic plating for strike/barrier layer and conduction layer formation, respectively, seem to be most cost effective

    Visible and ultraviolet reflectance and luminescence from various Saudi Arabian and Indiana limestone rocks

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    Visible and ultraviolet reflectance and luminescence for natural limeston

    Analysis and Evaluation of Processes and Equipment in Tasks 2 and 4 of the Low-cost Solar Array Project

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    The significant economic data for the current production multiblade wafering and inner diameter slicing processes were tabulated and compared to data on the experimental and projected multiblade slurry, STC ID diamond coated blade, multiwire slurry and crystal systems fixed abrasive multiwire slicing methods. Cost calculations were performed for current production processes and for 1982 and 1986 projected wafering techniques

    Feasibility of multi-satellite occultation /refraction/ measurements for meteorology Final report

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    Radio refraction and occultation techniques for atmospheric density measurements between multiple satellite

    Radar exploration of Venus

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    Spacecraft radar systems for exploration of Venu

    Experimental investigation of hypersonic buzz on a high cross-range shuttle configuration

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    A wind tunnel investigation has been conducted to determine the nature of an unsteady hypersonic flow phenomenon, often referred to as hypersonic buzz, on a 1:100 scale model representative of a high cross-range shuttle configuration. The tests, conducted in helium at a nominal Mach number of 17.5, were specifically directed at obtaining a better understanding of the character of the hypersonic flow field in the vicinity of a deflected control surface. Power spectral densities and root mean squared values of surface pressure fluctuations are presented along with observations made from high speed motion pictures, schlieren and oil flow photographs. Flap deflections of 0, 20, 30, 35, 40 and 60 deg were tested at various angles of attack from 0 deg to 37 deg. It is quite clear from these tests that, under certain conditions, extremely unstable hypersonic flow patterns are formed

    Kodaira-Spencer formality of products of complex manifolds

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    We shall say that a complex manifold XX is emph{Kodaira-Spencer formal} if its Kodaira-Spencer differential graded Lie algebra AX0,∗(ThetaX)A^{0,*}_X(Theta_X) is formal; if this happen, then the deformation theory of XX is completely determined by the graded Lie algebra H∗(X,ThetaX)H^*(X,Theta_X) and the base space of the semiuniversal deformation is a quadratic singularity.. Determine when a complex manifold is Kodaira-Spencer formal is generally difficult and we actually know only a limited class of cases where this happen. Among such examples we have Riemann surfaces, projective spaces, holomorphic Poisson manifolds with surjective anchor map H∗(X,OmegaX1)oH∗(X,ThetaX)H^*(X,Omega^1_X) o H^*(X,Theta_X) and every compact K"{a}hler manifold with trivial or torsion canonical bundle. In this short note we investigate the behavior of this property under finite products. Let X,YX,Y be compact complex manifolds; we prove that whenever XX and YY are K"{a}hler, then XimesYX imes Y is Kodaira-Spencer formal if and only if the same holds for XX and YY. A revisit of a classical example by Douady shows that the above result fails if the K"{a}hler assumption is droppe

    Buneman instability in a magnetized current-carrying plasma with velocity shear

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    Buneman instability is often driven in magnetic reconnection. Understanding how velocity shear in the beams driving the Buneman instability affects the growth and saturation of waves is relevant to turbulence, heating, and diffusion in magnetic reconnection. Using a Mathieu-equation analysis for weak cosine velocity shear together with Vlasov simulations, the effects of shear on the kinetic Buneman instability are studied in a plasma consisting of strongly magnetized electrons and cold unmagnetized ions. In the linearly unstable phase, shear enhances the coupling between oblique waves and the sheared electron beam, resulting in a wider range of unstable eigenmodes with common lower growth rates. The wave couplings generate new features of the electric fields in space, which can persist into the nonlinear phase when electron holes form. Lower hybrid instabilities simultaneously occur at k∥/k⊥∼me/mik_{\shortparallel}/k_{\perp} \sim \sqrt{m_e/m_i} with a much lower growth rate, and are not affected by the velocity shear.Comment: Accepted by Physics of Plasm
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