Necessary thickness of randomly oriented armor for meteoroid protection
Determination of armor thickness necessary for meteoroid protection
Miller, C. D.↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Digital filtering of random digits
Digital simulation of linear filter, investigating noise and rounding errors effects on decoding signals from lunar and interplanetary probes
Jennings, G.↗
Random differential equations in control theory
Control processes and optimization problems solutions by stochastic differential equations, discussing dynamic models and programming, linear filtering and optimal feedback
Wonham, W. M.↗
Peak structural response to nonstationary random excitations
Study establishes distribution function of peak response values, based on frequency interpretation. Excitations considered include impact loading on landing gears and aircraft gust loading. Because of relative severity of excitations, prediction of fatigue and maximum response characteristics is important part of task of structural analysis and design.
Shinozuka, M.↗
On-line analysis of random vibrations
Measuring device, Randomdec, provides continuous on-line signatures representative of system free vibration curve. Selected points on curve are used in control and failure detection systems. Apparatus applied to both linear and nonlinear systems under nonstationary vibratory states.
Cole, H. A., Jr.↗
Failure detection of a space shuttle wing flutter model by random decrement
On-line monitoring of characteristic structural response of space shuttle wing flutter model for failure detection and repair
Cole, H. A., Jr.↗
Two stochastic models for simulation of correlated random processes
Mathematical models for simulation of correlated stochastic processes with stationary Gaussian properties
Hoshiya, M.↗
The Response of Shells to Distributed Random Loads Using NASTRAN
Dynamic response of cylindrical shell excited by simulated turbulent boundary layer pressure field determined by NASTRAN
Jones, G. K.↗
Sound radiation from random quadrupole source distributions in axial flow fans
Inlet turbulence interaction with rotor potential flow as noise source in axial flow fans, developing expression for sound power radiated
Chandrashekhara, N.↗
Performance limitations of an inertial aircraft lateral guidance system subject to random gusts
Inertial aircraft lateral guidance system limitations in stochastic gust environment, comparing configurations using aileron or differential spoilers
Mackinnon, D.↗
Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations. Phase 5C: Development of experimental methods
Test equipment which was built and the calibration tests are described. The test equipment consists of a two-bladed rotor of 16-in. diameter, the blades of which are elastically hinged in flapping. The feathering shaft of the blades can be harmonically rotated with the help of a cam mechanism located inside the hollow rotor shaft. The frequency range measured in the rotating system can be adjusted between 0 and 80 cps and the rotor speed between 0 and 40 cps. The test equipment is for measuring the flapping response of the blades to harmonic feathering excitation.
Hohenemser, K. H.↗
Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations. Phase 6-B: Experiments with progressing/regressing forced rotor flapping modes
A two bladed 16-inch hingeless rotor model was built and tested outside and inside a 24 by 24 inch wind tunnel test section at collective pitch settings up to 5 deg and rotor advance ratios up to .4. The rotor model has a simple eccentric mechanism to provide progressing or regressing cyclic pitch excitation. The flapping responses were compared to analytically determined responses which included flap-bending elasticity but excluded rotor wake effects. Substantial systematic deviations of the measured responses from the computed responses were found, which were interpreted as the effects of interaction of the blades with a rotating asymmetrical wake.
Hohenemser, K. H.↗
Fokker-Planck equations for charged-particle transport in random fields.
The Fokker-Planck equations for charged-particle dynamics are rederived, extending somewhat the elegant discussion of Hasselmann and Wibberenz. It is shown that the usual results are obtae and the conclusions in many cases are correct over a very broad range in energy. In particular, the rate for pitch-angle scattering may be accurately given down to energies much lower than previously thought. Recent claims that these Fokker-Planck equations are in general incorrect are thus shown to be in error.
Jokipii, J. R.↗
Nonlinear filtering for random signals in statistically unknown noise.
Natural and effective formulation of the filtering problem involved in satellite orbit determination, aircraft navigation, and missile tracking. The problem arises because the environment of the sensor keeps changing from time to time, and it is quite impractical and sometimes impossible to collect the statistical data of the noise incurred in the observation. Computable filtering equations are deduced. The idea of invariant imbedding along with stochastic differential calculus is used to derive differential equations for the optimal estimate.
Loo, J. T.↗
Random gravitational encounters and the evolution of spherical systems. III - Halo.
The accumulation of stars in the halo of a spherical stellar system, together with the escape of stars from the system, result from stellar encounters within a dense central core. The resultant halo structure is studied both analytically and numerically for an isolated system. On the assumption that conditions in the central core remain constant with time, a simple steady-state solution is obtained for the outermost halo, or 'fringe', defined as the region from which stars may escape after a few additional orbits through the central core of the system. In this steady-state solution the density in phase space, obtained from a simple integral equation for the fringe region, is found to vary nearly linearly with the total energy of a star per unit mass for energies which are less than the energy of escape.
Spitzer, L., Jr.↗
Monte Carlo studies of the relaxation of vector end-to-end length in random-coil polymer chains.
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Kranbuehl, D. E.↗
Photography of random motion with a holographic camera
Three-dimensional system uses two additional mirrors and path compensators. It is essentially three mutually-orthogonal one-dimensional systems with common focus. Laser beam is split into four parts, three of which are object beams; and fourth is reference beam. Size of each ellipse depends on magnitude of velocity vectors.
Kurtz, R. L.↗
Incomplete state feedback for systems with parameter uncertainty and random disturbances
A unified design philosophy is presented for limited state feedback control problems with parameter uncertainty for both deterministic and stochastic problems. Two approaches are considered: linear compensator for the deterministic problem with parameter uncertainty, and for the single input-single output system with parameter uncertainty, a model on order equal to that of the system less the number of zeroes. The limitations of these approaches are discussed along with suggestions for further research.
Basuthakur, S.↗