3,240 research outputs found

    Effect of motion cues during complex curved approach and landing tasks: A piloted simulation study

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    A piloted simulation study was conducted to examine the effect of motion cues using a high fidelity simulation of commercial aircraft during the performance of complex approach and landing tasks in the Microwave Landing System (MLS) signal environment. The data from these tests indicate that in a high complexity MLS approach task with moderate turbulence and wind, the pilot uses motion cues to improve path tracking performance. No significant differences in tracking accuracy were noted for the low and medium complexity tasks, regardless of the presence of motion cues. Higher control input rates were measured for all tasks when motion was used. Pilot eye scan, as measured by instrument dwell time, was faster when motion cues were used regardless of the complexity of the approach tasks. Pilot comments indicated a preference for motion. With motion cues, pilots appeared to work harder in all levels of task complexity and to improve tracking performance in the most complex approach task

    A locally adaptive time-stepping algorithm for\ud petroleum reservoir simulations

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    An algorithm for locally adapting the step-size for large scale finite volume simulations of multi-phase flow in petroleum reservoirs is suggested which allows for an “all-in-one” implicit calculation of behaviour over a very large time scale. Some numerical results for simple two-phase flow in one space dimension illustrate the promise of the algorithm, which has also been applied to very simple 3D cases. A description of the algorithm is presented here along with early results. Further development of the technique is hoped to facilitate useful scaling properties

    Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 127, April 1974

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    This special bibliography lists 279 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1974

    Design and implementation of a DSP based MPEG-1 audio encoder

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    The speed of current PCs enables them to decode and play an MPEG bitstream in real time. The encoding process, however, cannot be done in real-time. The purpose of this thesis is to produce a low-cost real-time Digital Signal Processor (DSP) implementation of an MPEG encoder. The DSP will provide an MPEG bitstream to the PC that can be saved to disk. The input to the DSP will be an analog audio signal. A codec provides the DSP with 16-bit samples of the signal. The DSP compresses these 16-bit samples using MPEG-1 layer 1 compression. Then it formats the compressed data to the correct MPEG-1 bitstream, and transmits it to the PC over its byte-wide host interface. On the PC side, a program receives the data from the DSP and saves the MPEG data to the disk. An MPEG-1 layer 1 player can play the resulting file

    Efficient Reordered Nonlinear Gauss-Seidel Solvers With Higher Order For Black-Oil Models

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    The fully implicit method is the most commonly used approach to solve black-oil problems in reservoir simulation. The method requires repeated linearization of large nonlinear systems and produces ill-condi\-tioned linear systems. We present a strategy to reduce computational time that relies on two key ideas: (\textit{i}) a sequential formulation that decouples flow and transport into separate subproblems, and (\textit{ii}) a highly efficient Gauss--Seidel solver for the transport problems. This solver uses intercell fluxes to reorder the grid cells according to their upstream neighbors, and groups cells that are mutually dependent because of counter-current flow into local clusters. The cells and local clusters can then be solved in sequence, starting from the inflow and moving gradually downstream, since each new cell or local cluster will only depend on upstream neighbors that have already been computed. Altogether, this gives optimal localization and control of the nonlinear solution process. This method has been successfully applied to real-field problems using the standard first-order finite volume discretization. Here, we extend the idea to first-order dG methods on fully unstructured grids. We also demonstrate proof of concept for the reordering idea by applying it to the full simulation model of the Norne oil field, using a prototype variant of the open-source OPM Flow simulator.Comment: Comput Geosci (2019

    Study and determination of an optimum design for space utilized lithium-doped solar cells, part 2

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    Lithium doped solar cell hardness to 1 MeV electron irradiatio
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