294,648 research outputs found
Computational structural mechanics: A new activity at the NASA Langley Research Center
Complex structures considered for the late 1980's and early 1990's include composite primary aircraft structures and the space station. These structures are much more difficult to analyze than today's structures and necessitate a major upgrade in computerized structural analysis technology. A major research activity in computational structural mechanics (CSM) was initiated. The objective of the CSM activity is develop advanced structural analysis technology that will exploit modern and emerging computers such as computers with vector and/or parallel processing capabilities. The three main research activities underway in CSM include: (1) structural analysis methods development; (2) a software testbed for evaluating the methods; and (3) numerical techniques for parallel processing computers. The motivation and objectives of the CSM activity are presented and CSM activity is described. The current CSM research thrusts, and near and long term CSM research thrusts are outlined
Execution environment for intelligent real-time control systems
Modern telerobot control technology requires the integration of symbolic and non-symbolic programming techniques, different models of parallel computations, and various programming paradigms. The Multigraph Architecture, which has been developed for the implementation of intelligent real-time control systems is described. The layered architecture includes specific computational models, integrated execution environment and various high-level tools. A special feature of the architecture is the tight coupling between the symbolic and non-symbolic computations. It supports not only a data interface, but also the integration of the control structures in a parallel computing environment
Predictive wind turbine simulation with an adaptive lattice Boltzmann method for moving boundaries
Operating horizontal axis wind turbines create large-scale turbulent wake structures that affect the power output of downwind turbines considerably. The computational prediction of this phenomenon is challenging as efficient low dissipation schemes are necessary that represent the vorticity production by the moving structures accurately and that are able to transport wakes without significant artificial decay over distances of several rotor diameters. We have developed a parallel adaptive lattice Boltzmann method for large eddy simulation of turbulent weakly compressible flows with embedded moving structures that considers these requirements rather naturally and enables first principle simulations of wake-turbine interaction phenomena at reasonable computational costs. The paper describes the employed computational techniques and presents validation simulations for the Mexnext benchmark experiments as well as simulations of the wake propagation in the Scaled Wind Farm Technology (SWIFT) array consisting of three Vestas V27 turbines in triangular arrangement
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Metamaterial window glass for adaptable energy efficiency
textA computational analysis of a metamaterial window design is presented for the purpose of increasing the energy efficiency of buildings in seasonal or cold climates. Commercial low-emissivity windows use nanometer-scale Ag films to reflect infrared energy, while retaining most transmission of optical wavelengths for functionality. An opportunity exists to further increase efficiency through a variable emissivity implementation of Ag thin-film structures. 3-D finite-difference time-domain simulations predict non-linear absorption of near-infrared energy, providing the means to capture a substantial portion of solar energy during cold periods. The effect of various configuration parameters is quantified, with prediction of the net sustainability advantage. Metamaterial window glass technology can be realized as a modification to current, commercial low-emissivity windows through the application of nano-manufactured films, creating the opportunity for both new and after-market sustainable construction.Mechanical Engineerin
Multiscale simulations of topological transformations in magnetic Skyrmions
Magnetic Skyrmions belong to the most interesting spin structures for the
development of future information technology as they have been predicted to be
topologically protected. To quantify their stability, we use an innovative
multiscale approach to simulating spin dynamics based on the
Landau-Lifshitz-Gilbert equation. The multiscale approach overcomes the
micromagnetic limitations that have hindered realistic studies using
conventional techniques. We first demonstrate how the stability of a Skyrmion
is influenced by the refinement of the computational mesh and reveal that
conventionally employed traditional micromagnetic simulations are inadequate
for this task. Furthermore, we determine the stability quantitatively using our
multiscale approach. As a key operation for devices, the process of
annihilating a Skyrmion by exciting it with a spin polarized current pulse is
analyzed, showing that Skyrmions can be reliably deleted by designing the pulse
shape
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