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This special bibliography includes research on reusable launch vehicles, aerospace planes, shuttle replacement, crew/cargo transfer vehicle, related Xcraft, orbital space plane, and next generation launch technology.
Topics: KALMAN FILTERS, ATTITUDE (INCLINATION), MATHEMATICAL MODELS, SPACECRAFT CONTROL, QUATERNIONS,...
A method for performing progressive damage modeling in composite materials and structures based on continuum level interfacial displacement discontinuities is presented. The proposed method enables the exponential evolution of the interfacial compliance, resulting in unloading of the tractions at the interface after delamination or failure occurs. In this paper, the proposed continuum displacement discontinuity model has been used to simulate failure within both isotropic and orthotropic...
Topics: NASA Technical Reports Server (NTRS), CRACK GEOMETRY, DAMAGE, DISCONTINUITY, DISPLACEMENT, FINITE...
PDC 8.0 includes an implementation of a new algorithm to detect and correct step discontinuities appearing in roughly one of every 20 stellar light curves during a given quarter. The majority of such discontinuities are believed to result from highenergy particles (either cosmic or solar in origin) striking the photometer and causing permanent local changes (typically 0.5%) in quantum efficiency, though a partial exponential recovery is often observed [1]. Since these features, dubbed sudden...
Topics: NASA Technical Reports Server (NTRS), TIME SERIES ANALYSIS, FLUX QUANTIZATION, DISCONTINUITY,...
The goal of this work is to develop an equivalent circuit model for a typical discontinuity in shielded suspended substrate line, in particular, the stepchange in width. This circuit model is needed for use in CAD analysis of microwave systems using the suspended stripline transmission mode.
Topics: Strip transmission lines, Electric circuits, Equivalent, Models, Microwaves., Suspendedmicrostrip...
If a disturbance in the supersonic solar wind reaches the heliospheric shock, a number of events ensue. First, the shock itself responds with inward or outward motion. Secondly, the disturbance propagates outward through the heliosheath as a sound or magnetoacoustic wave; eventually it reaches the heliopause and is (partially) reflected back toward the termination shock. The reflected wave can return to the shock, affecting the shock's motion, and be reflected yet again. The repetition of these...
Topics: NASA Technical Reports Server (NTRS), HELIOSPHERE, CAVITY RESONATORS, ACOUSTIC VELOCITY,...
A key step for some methods dealing with the reconstruction of a function with jump discontinuities is the accurate approximation of the jumps and their locations. Various methods have been suggested in the literature to obtain this valuable information. In the present paper, we develop an algorithm based on identities which determine the jumps of a 2(pi)periodic bounded nottoohighly oscillating function by the partial sums of its differentiated Fourier series. The algorithm enables one to...
Topics: NASA Technical Reports Server (NTRS), FOURIER SERIES, DISCONTINUITY, ALGORITHMS, ASYMPTOTIC SERIES,...
Simplified forms of the spacetime discontinuous Galerkin (DG) and discontinuous Galerkin leastsquares (DGLS) finite element method are developed and analyzed. The new formulations exploit simplifying properties of entropy endowed conservation law systems while retaining the favorable energy properties associated with symmetric variable formulations.
Topics: NASA Technical Reports Server (NTRS), DISCONTINUITY, GALERKIN METHOD, LEAST SQUARES METHOD, FINITE...
No abstract available
Topics: NASA Technical Reports Server (NTRS), ONE DIMENSIONAL FLOW, TWO DIMENSIONAL FLOW, COMPUTATIONAL...
Experiments on graphiteepoxy laminated plates containing unloaded small holes show that these laminates are notch insensitive. That is, the uniaxial strength of these laminates with small holes exceeds the strength predicted by a point stress criterion using the stress concentration factor for the inplane stress field. Laminates containing large holes exhibit notch sensitive behavior and consequently their strength is reasonably well predicted by the stress concentration effect. This hole...
Topics: NASA Technical Reports Server (NTRS), COMPOSITE MATERIALS, COMPRESSIVE STRENGTH, FAILURE ANALYSIS,...
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O'Malley, Owen; MansouriSamani, Masoud; Mehlitz, Peter; Penix, Joh
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The difficulty of characterizing and observing valid software behavior during testing can be very difficult in flight systems. To address this issue, we evaluated several approaches to increasing test observability on the Shuttle Abort Flight Management (SAFM) system. To increase test observability, we added probes into the running system to evaluate the internal state and analyze test data. To minimize the impact of the instrumentation and reduce manual effort, we used AspectOriented...
Topics: RIVERS, SEDIMENTS, DISCONTINUITY, IDENTIFYING, TOPOGRAPHY, MINERAL EXPLORATION, SURFACE PROPERTIES,...
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Slivon, L. E.; HernonKenny, L. A.; Katona, V. R.; Dejarme, L. E
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This report describes analytical methods and results obtained from chemical analysis of 31 charcoal samples in five sets. Each set was obtained from a single scrubber used to filter ambient air on board a Spacelab mission. Analysis of the charcoal samples was conducted by thermal desorption followed by gas chromatography/mass spectrometry (GC/MS). All samples were analyzed using identical methods. The method used for these analyses was able to detect compounds independent of their polarity or...
Topics: FINITE DIFFERENCE THEORY, HOMOGENEITY, WAVELET ANALYSIS, FLUX VECTOR SPLITTING, EULER EQUATIONS OF...
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Aircraft laminar flow control (LFC) from the 1930's through the 1990's is reviewed and the current status of the technology is assessed. Examples are provided to demonstrate the benefits of LFC for subsonic and supersonic aircraft. Early studies related to the laminar boundarylayer flow physics, manufacturing tolerances for laminar flow, and insectcontamination avoidance are discussed. LFC concept studies in windtunnel and flight experiments are the major focus of the paper. LFC design tools...
Topics: HYPERSONIC FLOW, COMPUTATIONAL FLUID DYNAMICS, UNSTRUCTURED GRIDS (MATHEMATICS), FLUX VECTOR...
A model inverse design problem is used to investigate the effect of flow discontinuities on the optimization process. The optimization involves finding the crosssectional area distribution of a duct that produces velocities that closely match a targeted velocity distribution. Quasionedimensional flow theory is used, and the target is chosen to have a shock wave in its distribution. The objective function which quantifies the difference between the targeted and calculated velocity...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT DESIGN, AIRCRAFT MODELS, COORDINATE TRANSFORMATIONS,...
A thirdorder Energy Stable Weighted Essentially Non{Oscillatory (ESWENO) finite difference scheme developed by Yamaleev and Carpenter [1] was proven to be stable in the energy norm for both continuous and discontinuous solutions of systems of linear hyperbolic equations. Herein, a systematic approach is presented that enables "energy stable" modifications for existing WENO schemes of any order. The technique is demonstrated by developing a oneparameter family of fifthorder...
Topics: NASA Technical Reports Server (NTRS), FINITE DIFFERENCE THEORY, HYPERBOLIC DIFFERENTIAL EQUATIONS,...
Directional discontinuities from Mariner 5 are studied. A substantial majority of the events have properties which are consistent with their being identified as tangential discontinuties. The results presented here agree in several respects with those of Burlaga from Pioneer 6. In addition, new results are presented. Previous Mariner 5 work on this subject is summarized with an explanation of apparent inconsistencies.
Topics: NASA Technical Reports Server (NTRS), DISCONTINUITY, MARINER 5 SPACE PROBE, SOLAR WIND, MAGNETIC...
Computation of interlaminar stresses from the higherorder shear and normal deformable beam theory and the refined zigzag theory was performed using the Sinc method based on Interpolation of Highest Derivative. The Sinc method based on Interpolation of Highest Derivative was proposed as an efficient method for determining throughthethickness variations of interlaminar stresses from one and twodimensional analysis by integration of the equilibrium equations of threedimensional elasticity....
Topics: NASA Technical Reports Server (NTRS), INTERLAMINAR STRESS, COMPUTER PROGRAMS, EQUILIBRIUM...
Accurate numerical simulations of complex multiscale compressible viscous flows, especially high speed turbulence combustion and acoustics, demand high order schemes with adaptive numerical dissipation controls. Standard high resolution shockcapturing methods are too dissipative to capture the small scales and/or longtime wave propagations without extreme grid refinements and small time steps. An integrated approach for the control of numerical dissipation in high order schemes with...
Topics: NASA Technical Reports Server (NTRS), NUMERICAL ANALYSIS, NUMERICAL CONTROL, ADAPTIVE CONTROL,...
An improved method of locating small breaches in insulation on electrical wires combines aspects of the prior dielectric withstand voltage (DWV) and timedomain reflectometry (TDR) methods. The method was invented to satisfy a need for reliably and quickly locating insulation defects in spacecraft, aircraft, ships, and other complex systems that contain large amounts of wiring, much of it enclosed in structures that make it difficult to inspect. In the DWV method, one applies a predetermined...
Topics: NASA Technical Reports Server (NTRS), DEFECTS, WIRING, DIELECTRICS, ELECTRIC POTENTIAL, ELECTRICAL...
Thin sheets of resistive or dielectric material are commonly encountered in radar cross section calculations. Analysis of such sheets is simplified by using sheet impedances. It is shown that sheet impedances can be modeled easily and accurately using Finite Difference Time Domain (FDTD) methods. These sheets are characterized by a discontinuity in the tangential magnetic field on either side of the sheet but no discontinuity in tangential electric field. This continuity, or single valued...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC FIELDS, ELECTRICAL IMPEDANCE, MATHEMATICAL MODELS,...
This final report describes a brief summary of our accomplishments during the complete contract period. Traditionally, due to computational limitations, it has been impossible to obtain a global view of the magnetosphere on ion time and spatial scales. As a result, kineticsimulations have concentrated on the local structure of different magnetospheric discontinuities and boundaries. However, due to the emergence of low cost supercomputers, as well as by taking full advantage of latest advances...
Topics: NASA Technical Reports Server (NTRS), BOUNDARY LAYERS, BOW WAVES, FLUX TRANSFER EVENTS,...
Without resorting to special treatment for each individual test case, the 1D and 2D CE/SE shockcapturing schemes described previously (in Part I) are used to simulate flows involving phenomena such as shock waves, contact discontinuities, expansion waves and their interactions. Five 1D and six 2D problems are considered to examine the capability and robustness of these schemes. Despite their simple logical structures and low computational cost (for the 2D CE/SE shockcapturing scheme, the CPU...
Topics: NASA Technical Reports Server (NTRS), CONSERVATION LAWS, SHOCK WAVES, COMPUTATIONAL FLUID DYNAMICS,...
The crustal structure across Amchitka was determined from two inline reversedrefraction profiles located northeast and southwest of Amchitka. Both profiles employed 10 OceanBottom Seismographs (OBS) spaced at 20km intervals and 5ton shots detonated at 20km intervals off each end of the OBS line. Traveltimes were corrected to a reference plane 4.5 km below sea level to minimize lateral velocity variations associated with the large changes in water depth in the area. Depth to the Moho along...
Topics: DTIC Archive, Linville, A Frank, TEXAS INSTRUMENTS INC DALLAS SCIENCE SERVICE DIV, *MOHOROVICIC...
MOCAGH.ORG: Miscellaneous: starsaga2 booki
Topics: clathran, clathrans, planet, menace, ship, hadrakian, interphase, space, galactic, hadrakians,...
A new, highorder, conservative, and efficient method for conservation laws on unstructured grids is developed. The concept of discontinuous and highorder local representations to achieve conservation and high accuracy is utilized in a manner similar to the Discontinuous Galerkin (DG) and the Spectral Volume (SV) methods, but while these methods are based on the integrated forms of the equations, the new method is based on the differential form to attain a simpler formulation and higher...
Topics: NASA Technical Reports Server (NTRS), CONSERVATION LAWS, SPECTRAL METHODS, UNSTRUCTURED GRIDS...
From the bitsavers.org collection, a scannedin computerrelated document. mit :: ai :: aim :: AIM970
Topics: depth, intensity, discontinuities, mrf, edges, stereo, process, lattice, integration, image,...
A fullpotential steady transonic wing flow solver has been modified so that freestream density and residual are captured in regions of constant velocity. This numerically precise freestream consistency is obtained by slightly altering the differencing scheme without affecting the implicit solution algorithm. The changes chiefly affect the fifteen metrics per grid point, which are computed once and stored. With this new method, the outer boundary condition is captured accurately, and the...
Topics: NASA Technical Reports Server (NTRS), CONSISTENCY, DIFFERENCE EQUATIONS, FREE FLOW, POTENTIAL...
In these lecture notes we describe the construction, analysis, and application of ENO (Essentially NonOscillatory) and WENO (Weighted Essentially NonOscillatory) schemes for hyperbolic conservation laws and related Hamilton Jacobi equations. ENO and WENO schemes are high order accurate finite difference schemes designed for problems with piecewise smooth solutions containing discontinuities. The key idea lies at the approximation level, where a nonlinear adaptive procedure is used to...
Topics: NASA Technical Reports Server (NTRS), ESSENTIALLY NONOSCILLATORY SCHEMES, FINITE DIFFERENCE...
In this paper we present a new form of the collocation method that allows one to find very accurate solutions to time marching problems without the unwelcome appearance of Gibb's phenomenon oscillations. The basic method is applicable to any partial differential equation whose solution is a continuous, albeit possibly rapidly varying function. Discontinuous functions are dealt with by replacing the function in a small neighborhood of the discontinuity with a spline that smoothly connects the...
Topics: NASA Technical Reports Server (NTRS), COLLOCATION, PARTIAL DIFFERENTIAL EQUATIONS, DISCONTINUITY,...
In this paper we discuss the waveresolution properties of the Fourier approximations of a wave function with discontinuities. It is well known that a minimum of two points per wave is needed to resolve a periodic wave function using Fourier expansions. For Chebyshev approximations of a wave function, a minimum of pi points per wave is needed. Here we obtain an estimate for the minimum number of points per wave to resolve a discontinuous wave based on its Fourier coefficients. In our recent...
Topics: NASA Technical Reports Server (NTRS), DISCONTINUITY, FOURIER ANALYSIS, FOURIER SERIES, GIBBS...
The device and associated analysis methodology summarized in this report were developed for the purpose of estimating the size of discontinuities in the surface of the foam that covers the Space Shuttle External Tank. These surface offsets are thought to be due to subsurface cracks in the foam insulation. The mathematical analysis and procedure described here provide a method to quantity the dimensions of the crack offset in a direction perpendicular to the surface, making use of the projected...
Topics: NASA Technical Reports Server (NTRS), CRACKS, EXTERNAL TANKS, LASER TARGETS, IMAGE ANALYSIS, SPACE...
Advances in modeling and simulation, new finite element software, modeling engines and powerful computers are providing opportunities to interrogate designs in a very different manner and in a more detailed approach than ever before. Margins of safety are also often evaluated using local stresses for various design concepts and design parameters quickly once analysis models are defined and developed. This paper suggests that not all the negative margins of safety evaluated are real. The...
Topics: NASA Technical Reports Server (NTRS), ERROR ANALYSIS, STRUCTURAL ANALYSIS, BOUNDARY CONDITIONS,...
Window layers help in reducing the surface recombination at the emitter surface of the solar cells resulting in significant improvement in energy conversion efficiency. Indium gallium arsenide (In(x)Ga(1x)As) and related materials based solar cells are quite promising for photovoltaic and thermophotovoltaic applications. The flexibility of the change in the bandgap energy and the growth of InGaAs on different substrates make this material very attractive for multibandgap energy,...
Topics: NASA Technical Reports Server (NTRS), SOLAR CELLS, INDIUM GALLIUM ARSENIDES, INDIUM PHOSPHIDES,...
The 2ndorder upwind inviscid flux scheme implemented in the multiblock, structured grid, cell centered, finite volume, highspeed reacting flow code VULCAN has been modified to reduce numerical dissipation. This modification was motivated by the desire to improve the codes ability to perform large eddy simulations. The reduction in dissipation was accomplished through a hybridization of nondissipative and dissipative discontinuitycapturing advection schemes that reduces numerical...
Topics: NASA Technical Reports Server (NTRS), ADVECTION, DISSIPATION, INVISCID FLOW, LARGE EDDY SIMULATION,...
We introduce a new approach to highorder accuracy for the numerical solution of diffusion problems by solving the equations in differential form using a reconstruction technique. The approach has the advantages of simplicity and economy. It results in several new highorder methods including a simplified version of discontinuous Galerkin (DG). It also leads to new definitions of common value and common gradient quantities at each interface shared by the two adjacent cells. In addition, the new...
Topics: NASA Technical Reports Server (NTRS), GALERKIN METHOD, POLYNOMIALS, NUMERICAL ANALYSIS, DIFFUSION...
In this paper, we develop a time and its corresponding spatial discretization scheme, based upon the assumption of a certain weak singularity of parallel ut(t) parallel Lz(omega) = parallel ut parallel2, for the discontinuous Galerkin finite element method for onedimensional parabolic problems. Optimal convergence rates in both time and spatial variables are obtained. A discussion of automatic timestep control method is also included.
Topics: NASA Technical Reports Server (NTRS), FINITE ELEMENT METHOD, GALERKIN METHOD, DISCONTINUITY,...
Two different aspects of active antenna array design were investigated. The transition between monolithic microwave integrated circuits and rectangular waveguides was studied along with crosstalk in multiconductor transmission lines. The boundary value problem associated with a discontinuity in a microstrip line is formulated. This entailed, as a first step, the derivation of the propagating as well as evanescent modes of a microstrip line. The solution is derived to a simple discontinuity...
Topics: NASA Technical Reports Server (NTRS), ANTENNA ARRAYS, DISCONTINUITY, INTEGRATED CIRCUITS,...
The convergence of the Fourier method for scalar nonlinear conservation laws which exhibit spontaneous shock discontinuities is discussed. Numerical tests indicate that the convergence may (and in fact in some cases must) fail, with or without postprocessing of the numerical solution. Instead, a new kind of spectrally accurate vanishing viscosity is introduced to augment the Fourier approximation of such nonlinear conservation laws. Using compensated compactness arguments, it is shown that...
Topics: NASA Technical Reports Server (NTRS), CONSERVATION LAWS, CONVERGENCE, NONLINEAR SYSTEMS, SPECTRAL...
A nonintrusive electrical cable tester determines the nature and location of a discontinuity in a cable through application of an oscillating signal to one end of the cable. The frequency of the oscillating signal is varied in increments until a minimum, close to zero voltage is measured at a signal injection point which is indicative of a minimum impedance at that point. The frequency of the test signal at which the minimum impedance occurs is then employed to determine the distance to the...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC POTENTIAL, IMPEDANCE, NONINTRUSIVE MEASUREMENT,...
This paper presents a physicsbased model describing the currentinduced formation of a parasitic barrier in the conduction band at the base collector heterojunction in npn SiGe heterojunction bipolar transistors (HBTs). Due to the valence band discontinuity DELTA E(sub v), hole injection into the collector at the onset of base pushout is impeded, which gives rise to formation of a barrier to electron transport which degrades the device's high frequency performance. In this paper, we present...
Topics: NASA Technical Reports Server (NTRS), BIPOLAR TRANSISTORS, CONDUCTION BANDS, HETEROJUNCTIONS,...
The overall goal of this research was to assess the effect of discontinuities and uncertainties on the nonlinear response and failure of composite structures subjected to combined mechanical and thermal loads. The four key elements of the study were: (1) development of simple and efficient procedures for the accurate determination of transverse shear and transverse normal stresses in structural sandwiches as well as in unstiffened and stiffened composite panels and shells; (2) study the effects...
Topics: NASA Technical Reports Server (NTRS), COMPOSITE STRUCTURES, DISCONTINUITY, FAILURE, SANDWICH...
Ultimate safety factors of high performance structures depend on stress behavior beyond the elastic limit, a region not too well understood. An analytical modeling approach was developed to gain fundamental insights into inelastic responses of simple structural elements. Nonlinear material properties were expressed in engineering stresses and strains variables and combined with strength of material stress and strain equations similar to numerical piecewise linear method. Integrations are...
Topics: NASA Technical Reports Server (NTRS), AXIAL LOADS, BENDING, SAFETY FACTORS, STRESS ANALYSIS,...
A calculation method is presented for sound propagation over an impedance discontinuity in flat ground with a homogeneous, still atmosphere. The method is based on an approximate solution to a two dimensional boundary integral equation formulation of the problem, which expresses the wave field as the solution for homogeneous ground plus an integral over half of the boundary. Through recognizing this integral as a generalized Fourier integral, asymptotic methods are applied to evaluate the part...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC IMPEDANCE, BOUNDARY INTEGRAL METHOD, EARTH SURFACE,...
Several numerical simulations of the transient flow of helium in an expansion tube are presented. The aim of the exercise is to provide further information on the operational problems of the NASA Langley expansion tube. The calculations were performed with an axisymmetric NavierStokes code based on a finitevolume formulation and upwinding techniques. Although laminar flow and ideal bursting of the diaphragms was assumed, the simulations showed some of the important features seen in the...
Topics: NASA Technical Reports Server (NTRS), COMPUTATIONAL FLUID DYNAMICS, EXPANSION, HELIUM,...
Among the many methods available for the determination of inviscid fluxes across a surface of discontinuity, the fluxdifferencesplitting technique that employs Roeaveraged variables has been used extensively by the CFD community because of its simplicity and its ability to capture shocks exactly. This method, originally developed for perfect gas flows, has since been extended to equilibrium as well as nonequilibrium flows. Determination of the Roeaveraged variables for the case of a perfect...
Topics: NASA Technical Reports Server (NTRS), AEROTHERMODYNAMICS, COMPUTATIONAL FLUID DYNAMICS, GAS FLOW,...
The study of printed circuit discontinuities is necessary in order to design, for example, transitions between rectangular waveguides and printed circuits. New developments with respect to the analytical approaches to this problem are discussed. A summary of the progress in the experimental approach is presented. The accurate solution for the modes in various millimeterwave waveguides is essential in the analysis of many integrated circuit components, such as filters and impedance...
Topics: NASA Technical Reports Server (NTRS), ANTENNAS, DISCONTINUITY, MILLIMETER WAVES, PHASED ARRAYS,...
Bell System Technical Journal, 41: 2. March 1962 pp 603633. Analysis of the PhaseControlled Loop with a Sawtooth Comparator. (Goldstein, A. Jay)
Topics: tanh, loop, filter, phase, lag, equation, relative, comparator, discontinuity, normalized, time...
Bell System Technical Journal, 46: 3. March 1967 pp 649672. Iterative Solution of Waveguide Discontinuity Problems. (Cole, W.J.; Nagelberg, E.R.; Nagel, C.M.)
Topics: discontinuity, matrix, waveguide, transverse, magnetic, vector, mode, modes, field, iterative,...
Folkscanomy Electronics Articles: The DDRRDirectional Discontinuity Ring Radiator
Topics: antenna, ddrr, photo, slot, polarized, vertically, inch, mhz, dipole, vhf, vertically polarized,...
The size and shape of opening in dam causes the stress concentration, it also causes the stress variation in the rest of the dam cross section. The gravity method of the analysis does not consider the size of opening and the elastic property of dam material. Thus the objective of study is comprises of the Finite Element Method which considers the size of opening, elastic property of material, and stress distribution because of geometric discontinuity in cross section of dam. Stress...
Topics: Openings in dam, Finite Element Method, geometric discontinuity, Koyna Dam, 2D plane strain...
The pointwise values of a function, f(x), can be accurately recovered either from its spectral or pseudospectral approximations, so that the accuracy solely depends on the local smoothness of f in the neighborhood of the point x. Most notably, given the equidistant function grid values, its intermediate point values are recovered within spectral accuracy, despite the possible presence of discontinuities scattered in the domain. (Recall that the usual spectral convergence rate decelerates...
Topics: NASA Technical Reports Server (NTRS), APPROXIMATION, DISCONTINUITY, SHOCK WAVES, SMOOTHING,...