32,306 research outputs found

    Hubble Space Telescope meteoroid-debris protection analysis

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    A system level failure could occur if the Hubble Space Telescope's (ST) capability to operate as a facility on-orbit is critically reduced or when a significant reduction in the quality of science data is registered. Failure could occur if a meteoroid/debris impact damages a component of a major support subsystem or if a meteoroid/debris penetration causes straylight contamination in the light shield, forward shell, aft shroud, or through the aperture door. The ST was analyzed to find the probability of no critical penetration. This probability value was found to be 92.25% for a two-year service life. A straylight leakage repair technique was recommended for the aft shroud, the region found most likely to be critically penetrated. Fozar tape and multilayer insulation blankets are suggested as posible repair materials

    Clearwing Moths Captured by Ultraviolet Light Traps in Southern Ohio (Lepidoptera: Sesiidae)

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    Trapping with ultraviolet light in mixed-oak forests of Lawrence and Vinton Counties, Ohio in 1995 and 1996 yielded 46 Synanthedon acerni and four Synanthedon arkansasensis, a clearwing moth record new for the state

    Saying Hello World with GReTL - A Solution to the TTC 2011 Instructive Case

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    This paper discusses the GReTL solution of the TTC 2011 Hello World case. The submitted solution covers all tasks including the optional ones.Comment: In Proceedings TTC 2011, arXiv:1111.440

    Geometric programming prediction of design trends for OMV protective structures

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    The global optimization trends of protective honeycomb structural designs for spacecraft subject to hypervelocity meteroid and space debris are presented. This nonlinear problem is first formulated for weight minimization of the orbital maneuvering vehicle (OMV) using a generic monomial predictor. Five problem formulations are considered, each dependent on the selection of independent design variables. Each case is optimized by considering the dual geometric programming problem. The dual variables are solved for in terms of the generic estimated exponents of the monomial predictor. The primal variables are then solved for by conversion. Finally, parametric design trends are developed for ranges of the estimated regression parameters. Results specify nonmonotonic relationships for the optimal first and second sheet mass per unit areas in terms of the estimated exponents

    Weight estimation techniques for composite airplanes in general aviation industry

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    Currently available weight estimation methods for general aviation airplanes were investigated. New equations with explicit material properties were developed for the weight estimation of aircraft components such as wing, fuselage and empennage. Regression analysis was applied to the basic equations for a data base of twelve airplanes to determine the coefficients. The resulting equations can be used to predict the component weights of either metallic or composite airplanes

    THERMTRAJ: A FORTRAN program to compute the trajectory and gas film temperatures of zero pressure balloons

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    A FORTRAN computer program called THERMTRAJ is presented which can be used to compute the trajectory of high altitude scientific zero pressure balloons from launch through all subsequent phases of the balloon flight. In addition, balloon gas and film temperatures can be computed at every point of the flight. The program has the ability to account for ballasting, changes in cloud cover, variable atmospheric temperature profiles, and both unconditional valving and scheduled valving of the balloon gas. The program was verified for an extensive range of balloon sizes (from 0.5 to 41.47 million cubic feet). Instructions on program usage, listing of the program source deck, input data and printed and plotted output for a verification case are included

    Solution to the Equations of the Moment Expansions

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    We develop a formula for matching a Taylor series about the origin and an asymptotic exponential expansion for large values of the coordinate. We test it on the expansion of the generating functions for the moments and connected moments of the Hamiltonian operator. In the former case the formula produces the energies and overlaps for the Rayleigh-Ritz method in the Krylov space. We choose the harmonic oscillator and a strongly anharmonic oscillator as illustrative examples for numerical test. Our results reveal some features of the connected-moments expansion that were overlooked in earlier studies and applications of the approach

    Leadership and capability development and deployment in the New Zealand State Service

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    This article describes the design during 2013 of a model and implementation principles of a leadership and capability development and deployment (LCDD) model for the state services system. In this process, an initial prototype model was developed to describe a desired future state. It was informed by the best traditions of state services leadership development, together with models used by the world’s best companies, such as Procter & Gamble, for leadership development (Filipkowski and Donlon, 2013). The model was then enhanced based on our research in other jurisdictions, including Australia, Singapore and the United Kingdom, and co-creation with stakeholders. This is further discussed in the article. Dr Mike Pratt is Professor of Leadership and Sustainability at the University of Waikato, and a professional director and business adviser. Dr Murray Horn is a former Secretary to the Treasury of New Zealand and bank chief executive, and a professional director and business adviser
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