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339

Jul 11, 2010
07/10

by
Ahrons, R. W

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An increase in efficiency from 2% to over 7% was achieved by a solar cell that used polycrystal silicon heterojunction with SnO2 glass. For Single crystal substrates, efficiencies close to 10% were measured. These cells had the same structures as polycrystalline cells. Work on p/n heterojunction using In2O3 glass resulted in cells of 3% efficiency on polycrystalline material and 4% efficiency on single crystal material.

Topics: COMPUTERIZED SIMULATION, DYNAMIC STRUCTURAL ANALYSIS, PROBLEM SOLVING, RIGID STRUCTURES,...

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387

Jun 21, 2010
06/10

by
Akyuz, F. A.; Utku, S

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ELAS general purpose digital computer program for equilibrium problems of linear structures

Topics: COMPUTER PROGRAMMING, INPUT, MATHEMATICAL MODELS, MATRICES (MATHEMATICS), OUTPUT, PUNCHED CARDS,...

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205

May 28, 2011
05/11

by
Alexander, Reginald A.; Coleman, Hugh W

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A thermal/fluids analysis of a direct gain solar thermal upper stage engine is presented and the results are discussed. The engine was designed and constructed at the NASA Marshall Space Flight Center for ground testing in a facility that can provide about 10 kilowatts of concentrated solar energy to the engine. The engine transfers energy to a coolant (hydrogen) that is heated and accelerated through a nozzle to produce thrust. For the nominal design values and a hydrogen flowrate of 2...

Topics: STRESS-STRAIN RELATIONSHIPS, VISCOPLASTICITY, SUBROUTINES, PEEK, NONLINEARITY, METALS, MATRICES...

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198

Jul 11, 2010
07/10

by
Anderson, J. R.; Witmer, R. E

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The Land Use Data and Analysis (LUDA) Program which provides a systematic and comprehensive collection and analysis of land use and land cover data on a nationwide basis is described. Maps are compiled at about 1:125,000 scale showing present land use/cover at Level II of a land use/cover classification system developed by the U.S. Geological Survey in conjunction with other Federal and state agencies and other users. For each of the land use/cover maps produced at 1:125,000 scale, overlays are...

Topics: COMPUTER GRAPHICS, FINITE ELEMENT METHOD, MATRICES (MATHEMATICS), NODES (STANDING WAVES), NUMERICAL...

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398

Jul 11, 2010
07/10

by
ARGYRIS, J. H.; LOCHNER, N. M.; SCHARPF, D. W

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THE APPLICATION OF THE MATRIX THEORY OF STATICS AND DYNAMICS TO THE CALCULATION OF NATURAL MODES OF OSCILLATION OF ROTOR BLADES IS DESCRIBED. THE BASIC PRINCIPLES OF THE MATRIX DISPLACEMENT METHOD ARE SUMMARIZED. THE IDEALIZED ROTOR BLADE IS BROKEN DOWN INTO ELEMENTS; THEIR ELASTIC REGIDITIES AND KINEMATICALLY EQUIVALENT POINT FORCES AND MOMENTS APPLIED TO NODES, RATHER THAN BEING DISTRIBUTED, ARE DERIVED. THE CORRESPONDING KINEMATICALLY EQUIVALENT MASS MATRIX IS ALSO OBTAINED. THESE AND...

Topics: ARTIFICIAL SATELLITES, ALGORITHMS, MATRICES (MATHEMATICS), SATELLITE ORIENTATION

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345

May 23, 2011
05/11

by
Babcock, Dale A.; Bruce, Robert A

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The advantages of high-molecular-weight gas (heavy gas) as a wind-tunnel medium have been recognized for some time. The current heavy gas of choice chlorofluorocarbon-12(CFC-12) (refrigerant R12) for the Transonic Dynamics Tunnel(TDT) must be replaced because manufacture of this gas ceased in 1995. An attractive replacement is 1,1,1,2-tetrafluoroethane (refrigerant R134a). Acceptable properties of this gas include molecular weight and speed of sound. Its vapor pressure allows simplified...

Topics: ALGORITHMS, ROBOT ARMS, DEGREES OF FREEDOM, WEIGHTING FUNCTIONS, MATRICES (MATHEMATICS), LEAST...

285
285

Jun 19, 2010
06/10

by
Babenko, K. I.; Rusanov, V. V

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Differential calculations for three-dimensional supersonic gas flow around smooth body

Topics: DIFFERENTIAL CALCULUS, THREE-DIMENSIONAL FLOW, GAS DYNAMICS, GAS FLOW, MATRICES (MATHEMATICS),...

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262

Jun 9, 2011
06/11

by
Banger, Kulbinder K.; Jin, Michael H. C.; Harris, Jerry D.; Fanwick, Philip E.; Hepp, Aloysius F

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We report a new simplified synthetic procedure for commercial manufacture of ternary single source precursors (SSP). This new synthetic process has been successfully implemented to fabricate known SSPs on bulk scale and the first liquid SSPs to the semiconductors CuInSe2 and AgIn(x)S(y). Single crystal X-ray determination reveals the first unsolvated ternary AgInS SSP. SSPs prepared via this new route have successfully been used in a spray assisted chemical vapor deposition (CVD) process to...

Topics: GALERKIN METHOD, MATRICES (MATHEMATICS), QUADRATURES, VECTORS (MATHEMATICS), SYMMETRY, POLYNOMIALS,...

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171

Jun 21, 2010
06/10

by
Barashenkov, V. S.; Gudima, K. K.; Toneyev, V. D

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Monte Carlo method for calculating inelastic collisions of deuterons with nuclei

Topics: CANONICAL FORMS, COMPLEX VARIABLES, FUNCTIONS (MATHEMATICS), MATRICES (MATHEMATICS),...

145
145

Jul 5, 2010
07/10

by
Beatty, M. E., II

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The effects of 22-MeV protons on various types of silicon single junction and silicon controlled rectifiers were investigated. The results show that low-leakage devices and silicon controlled rectifiers are the most susceptable to radiation damage. There are also differences noted between single junction rectifiers of the same type made by different manufacturers, which emphasizes the need for better selection of devices used in spacecraft.

Topics: ALGORITHMS, TRAJECTORY MEASUREMENT, MATRICES (MATHEMATICS), OPTIMIZATION, PARAMETERIZATION, RANDOM...

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270

Jul 21, 2010
07/10

by
Beek, J. M

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Three theories for prediction of inelastic deformation which are based on considerations of the microstructural behavior of materials are reviewed. The mechanics of continua with internal state variables and the historical development of constitutive modeling are summarized. A detailed discussion, including chronological development, review of theory, and method of determination of material parameters, of each model follows. An experimental data base is established from which the material...

Topics: ANTIFRICTION BEARINGS, ROTATING SHAFTS, TRANSFER FUNCTIONS, VIBRATION DAMPING, ROTARY STABILITY,...

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445

Jul 26, 2010
07/10

by
Belcastro, Celeste M

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Control systems for advanced aircraft, especially those with relaxed static stability, will be critical to flight and will, therefore, have very high reliability specifications which must be met for adverse as well as nominal operating conditions. Adverse conditions can result from electromagnetic disturbances caused by lightning, high energy radio frequency transmitters, and nuclear electromagnetic pulses. Tools and techniques must be developed to verify the integrity of the control system in...

Topics: ADAPTIVE CONTROL, BOUNDARY VALUE PROBLEMS, CONTROL SYSTEMS DESIGN, MATHEMATICAL MODELS, ON-LINE...

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200

Jul 12, 2010
07/10

by
Benjamin, P

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No Abstract Available

Topics: MATRICES (MATHEMATICS), SPACECRAFT, SYSTEMS ANALYSIS, CONTRACTION, DEGREES OF FREEDOM, STIFFNESS

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Jun 21, 2010
06/10

by
Benson, H. E

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No Abstract Available

Topics: CONTROL SIMULATION, DYNAMIC CONTROL, MODAL RESPONSE, SATURN S-4B STAGE, BURNING TIME, MATRICES...

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218

Sep 20, 2010
09/10

by
Berenji, Hamid R.; Chen, Yung-Yaw; Lee, Chuen-Chein; Murugesan, S

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An approach for controlling a dynamic physical system by using approximate reasoning is presented. The approach was implemented in a program named POLE, and we have successfully built a prototype hardware system to solve the cart-pole balancing problem in real-time. This provides a complementary alternative to the conventional analytical control methodology and is of substantial use where a precise mathematical model of the process being controlled is not available. Also, we furnish a set of...

Topics: MACLAURIN SERIES, PADE APPROXIMATION, MATHEMATICAL MODELS, MATRICES (MATHEMATICS), MEROMORPHIC...

145
145

Jun 12, 2011
06/11

by
Bergman, Mart

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Emergent agents, those agents whose local interactions can cause unexpected global results, require a method of modeling that is both dynamic and structured Petri Nets, a modeling tool developed for dynamic discrete event system of mainly functional agents, provide this, and have the benefit of being an established tool. We present here the details of the modeling method here and discuss how to implement its use for modeling agent-based systems. Petri Nets have been used extensively in the...

Topics: AEROACOUSTICS, FREQUENCY RANGES, DEGREES OF FREEDOM, THREE DIMENSIONAL MODELS, ALGORITHMS, MATRICES...

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241

May 27, 2011
05/11

by
Bergstrom, R. W.; Kinne, S.; Sokolik, I. N.; Toon, O. B.; Mlawer, E. J.; Clough, S. A.; Ackerman, T. P.; Mather, J

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A new radiative transfer model combining the efforts of three groups of researchers is discussed. The model accurately computes radiative transfer in a inhomogeneous absorbing, scattering and emitting atmospheres. As an illustration of the model, results are shown for the effects of dust on the thermal radiation.

Topics: ORBIT CALCULATION, STANDARD DEVIATION, POSITION ERRORS, COVARIANCE, DOWNRANGE, CIRCULAR ORBITS,...

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266

May 24, 2011
05/11

by
Bernstein, Max P.; Sandford, Scott A.; Allamandola, Louis J.; Chang, Sherwood; Scharberg, Maureen A

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The InfraRed (IR) spectra of UltraViolet (UV) and thermally processed, methanol-containing interstellar / cometary ice analogs at temperatures from 12 to 300 K are presented. Infrared spectroscopy, H-1 and C-13 Nuclear Magnetic Resonance (NMR) spectroscopy, and gas chromatography-mass spectrometry indicate that CO (carbon monoxide), CO2 (carbon dioxide), CH4 (methane), HCO (the formyl radical), H2CO (formaldehyde), CH3CH2OH (ethanol), HC([double bond]O)NH2 (formamide), CH3C([double bond]O)NH2...

Topics: STRUCTURAL ANALYSIS, COVARIANCE, DEGREES OF FREEDOM, STRUCTURAL DESIGN, FEEDBACK CONTROL, MATRICES...

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177

May 23, 2011
05/11

by
Bozzolo, Guillermo; Ibanez-Meier, Rodrigo; Ferrante, Joh

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Recent experiments using scanning tunneling microscopy show evidence for the formation of surface alloys of otherwise immiscible metals. Such is the case for Au deposited in Ni(110), where experiments by Pleth Nielsen el al.indicate that at low Au coverage (less than 0. 5 ML), Au atoms replace Ni atoms in the surface layer forming a surface alloy while the Ni atoms form islands on the surface. In this paper, we present results of a theoretical modeling of this phenomenon using the recently...

Topics: SIGNAL ANALYSIS, POLARIZED LIGHT, LEAST SQUARES METHOD, LINEARITY, PLANTS (BOTANY), CANOPIES...

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152

May 31, 2011
05/11

by
Branduardi-Raymont, G.; Sako, M.; Kahn, S. M.; Brinkman, A. C.; Kaastra, J. S.; Page, M. J

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XMM-Newton Reflection Grating Spectrometer (RGS) spectra of the Narrow Line Seyfert 1 galaxies MCG -6-30-15 and Mrk 766 are physically and spectroscopically inconsistent with standard models comprising a power-law continuum absorbed by either cold or ionized matter. We propose that the remarkably similar features detected in both objects in the 5 - 35 A band are H-like oxygen, nitrogen, and carbon emission lines, gravitation- ally redshifted and broadened by relativistic effects in the vicinity...

Topics: AEROSERVOELASTICITY, PHYSICAL EXERCISE, SCALING LAWS, EQUATIONS OF MOTION, FINITE ELEMENT METHOD,...

316
316

Jun 1, 2011
06/11

by
Brown, W. Byron; Monroe, William R

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A theoretical analysis of the temperature distribution through the trailing portion of a blade near the coolant passages of liquid cooled gas turbines was made. The analysis was applied to obtain the hot spot temperatures at the trailing edge and influence of design variables. The effective gas temperature was varied from 2000 degrees to 5000 degrees F in each investigation.

Topics: NAVIER-STOKES EQUATION, VISCOUS FLUIDS, FRICTION, STRESS ANALYSIS, SHEAR FLOW, ONE DIMENSIONAL...

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508

May 31, 2011
05/11

by
Camanho, P. P.; Davila, C. G.; Ambur, D. R

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The use of decohesion elements for the simulation of delamination in composite materials is reviewed. The test methods available to measure the interfacial fracture toughness used in the formulation of decohesion elements are described initially. After a brief presentation of the virtual crack closure technique, the technique most widely used to simulate delamination growth, the formulation of interfacial decohesion elements is described. Problems related with decohesion element constitutive...

Topics: PROLATE SPHEROIDS, SPHERES, SCATTERING, MATRICES (MATHEMATICS), CIRCULAR CYLINDERS, BACKSCATTERING,...

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482

Jul 25, 2010
07/10

by
Cetinkunt, Sabr

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A general gross and fine motion planning and control strategy is needed for lightweight robotic manipulator applications such as painting, welding, material handling, surface finishing, and spacecraft servicing. The control problem of lightweight manipulators is to perform fast, accurate, and robust motions despite the payload variations, structural flexibility, and other environmental disturbances. Performance of the rigid manipulator model based computed torque and decoupled joint control...

Topics: ATOMIC STRUCTURE, ULTRAVIOLET SPECTRA, CYANIDES, DISSOCIATION, MATRICES (MATHEMATICS), QUANTUM...

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201

Jul 26, 2010
07/10

by
Chamis, Christos C.; Rubinstein, Robert I

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A multidisciplinary design process for aerospace propulsion composite structures was formalized and embedded into computer codes. These computer codes are streamlined to obtain tailored designs for select composite structures. The codes available are briefly described with sample cases to illustrate their applications. The sample cases include aircraft engine blades, propfans (turboprops), flat, and cylindrical panels. Typical results illustrate that the use of these codes enable the designer...

Topics: GEOIDS, ORTHOGONAL FUNCTIONS, GRAVITATIONAL FIELDS, GRAVITY ANOMALIES, MATHEMATICAL MODELS,...

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315

May 23, 2011
05/11

by
Chattopadhyay, Aditi; Jha, Ratneshwa

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Composite wings have become increasingly popular in recent years due to significant potential of weight savings and stiffness tailoring. For aircraft wings made out of composite materials, aeroelastic tailoring presents an opportunity to enhance the aircraft performance by utilizing their unique stiffness and strength properties. Therefore, the goal of the current research are as follows: (1) Development of a new composite beam modeling, technique to represent the principal load-carrying member...

Topics: H-INFINITY CONTROL, TRANSFER FUNCTIONS, ROBUSTNESS (MATHEMATICS), COMPUTERIZED SIMULATION, SELF...

347
347

May 23, 2011
05/11

by
Choi, Sung R.; Salem, Jonathan A.; Holland, Frederic A

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The two estimation methods, individual data and arithmetic mean methods, were used to determine the slow crack growth (SCG) parameters (n and D) of advanced ceramics and glass from a large number of room- and elevated-temperature constant stress-rate ('dynamic fatigue') test data. For ceramic materials with Weibull modulus greater than 10, the difference in the SCG parameters between the two estimation methods was negligible; whereas, for glass specimens exhibiting Weibull modulus of about 3,...

Topics: COMPUTATIONAL GRIDS, MULTIPROCESSING (COMPUTERS), HEURISTIC METHODS, MATRICES (MATHEMATICS),...

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286

May 23, 2011
05/11

by
Christopher, Sundar A.; Kliche, Donna A.; Chou, Joyce; Welch, Ronald M

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Collocated measurements from the Advanced Very High Resolution Radiometer (AVHRR) and the Earth Radiation Budget Experiment (ERBE) scanner are used to examine the radiative forcing of atmospheric aerosols generated from biomass burning for 13 images in South America. Using the AVHRR, Local Area Coverage (LAC) data, a new technique based on a combination of spectral and textural measures is developed for detecting these aerosols. Then, the instantaneous shortwave, longwave, and net radiative...

Topics: JET AIRCRAFT NOISE, NAVIER-STOKES EQUATION, MATRICES (MATHEMATICS), NEAR FIELDS, PERIODIC...

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172

Jul 21, 2010
07/10

by
Clayton, D. D

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The relationship between solar system dust (SSD) and interstellar dust particles (ISMD) is being reconsidered because of the discovery of isotopic anomalies in meteorites. Meteoritic, circumstellar/meteoritic, interstellar/meteoritic, planetary, and cometary data are reviewed.

Topics: COMPOSITE MATERIALS, HOLES (ELECTRON DEFICIENCIES), MATHEMATICAL MODELS, PROJECTILES, TARGETS, BORN...

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172

May 23, 2011
05/11

by
Cohen, Ross D.; Beaver, E. A.; Diplas, Athanassios; Junkkarinen, Vesa T.; Barlow, Thomas A.; Lyons, Ronald W

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We present imaging and spectroscopy of the quasar 3CR 196 (z(sub e) = 0.871), which has 21 cm and optical absorption at z(sub a) = 0.437. We observed the region of Ly alpha absorption in 3CR 196 at z(sub a) = 0.437 with the Faint Object Spectrograph on the Hubble Space Telescope. This region of the spectrum is complicated because of the presence of a Lyman limit and strong lines from a z(sub a) approx. z(sub e) system. We conclude that there is Ly alpha absorption with an H I column density...

Topics: ALGORITHMS, SPECTRA, WAVE FRONTS, COMBINATORIAL ANALYSIS, ASYMPTOTIC PROPERTIES, MEAN SQUARE...

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198

Jun 21, 2010
06/10

by
Cole, D. Q

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Techniques for controlling warpage and residual stresses in welded aluminum alloy structures for Saturn project

Topics: COMPUTER PROGRAMS, ENERGY SPECTRA, LEAST SQUARES METHOD, PULSE AMPLITUDE, CONSTRAINTS, MATRICES...

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332

May 30, 2011
05/11

by
Comiso, Josefino C

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Co-registered and continuous satellite data of sea ice concentrations and surface ice temperatures from 1981 to 1999 are analyzed to evaluate relationships between these two critical climate parameters and what they reveal in tandem about the changing Arctic environment. During the 18-year period, the actual Arctic ice area is shown to be declining at a rate of 3.1 /- 0.4 % /decade while the surface ice temperature has been increasing at 0.4 /- 0.2 K /decade. Yearly anomaly maps also show that...

Topics: COMPUTATIONAL GRIDS, POLARIZERS, MAXWELL EQUATION, BEAMS (RADIATION), MATHEMATICAL MODELS,...

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214

Jul 6, 2010
07/10

by
Conn, A. F.; Rudy, S. L

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An investigation pertaining to the development of life prediction methods for materials subjected to high temperature creep/fatigue conditions is presented. High frequency (13.4 kHz) fatigue data were measured at 1400 F on specimens of the nickel-based alloy Udimet 700. Tests were conducted on the virgin material, as well as on specimens which had received prior exposures to high temperature, fatigue, and creep.

Topics: CANONICAL FORMS, DIFFERENTIAL EQUATIONS, LINEARITY, MATRICES (MATHEMATICS), EIGENVALUES, OPERATORS...

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196

May 23, 2011
05/11

by
Cuntz, Manfred; Deeney, Bryan D.; Brown, Alexander; Stencel, Robert E

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We evaluate time series observations of chromospheric lines (Mg II, Mg I, and C II) for the K giant alpha Tau obtained using the IUE LWP camera at high dispersion. These observations cover a time span of about 2 weeks in 1994 February-March and were designed to resolve variations occurring within hours, days, and weeks. We consider the observational results in relation to theoretical acoustic heating models, motivated by the fact that alpha Tau may exhibit a basal (i.e., minimum) level of...

Topics: P-I-N JUNCTIONS, MATRICES (MATHEMATICS), GALLIUM ARSENIDE LASERS, INDIUM GALLIUM ARSENIDES, INDIUM...

Contents: Some Applications of Transversal Theory to Graph Theory; Upper and Lower Bounds for Unrestricted Binary Error Correcting Codes; and Three-Class Association Schemes on a Small Number of Vertices.

Topics: DTIC Archive, Ray-Chaudhuri,D K, OHIO STATE UNIV COLUMBUS DEPT OF MATHEMATICS, *INFORMATION...

Data association is one of the core problems of simultaneous localization and mapping (SLAM), and it requires knowledge about the uncertainties of the estimation problem in the form of marginal covariances. However, it is often difficult to access these quantities without calculating the full and dense covariance matrix, which is prohibitively expensive. We present a dynamic programming algorithm for efficient recovery of the marginal covariances needed for data association. As input we use a...

Topics: DTIC Archive, MASSACHUSETTS INST OF TECH CAMBRIDGE COMPUTER SCIENCE AND ARTIFICIAL INTELLIGENCE...

A robust version of Principal Component Analysis (PCA) can be constructed via a decomposition of a data matrix into low-rank and sparse components, the former representing a low-dimensional linear model of the data, and the latter representing sparse deviations from the low-dimensional subspace. This decomposition has been shown to be highly effective, but the underlying model is not appropriate when the data are not modeled well by a single low-dimensional subspace. We construct a new...

Topics: DTIC Archive, LOS ALAMOS NATIONAL LAB NM, *BACKGROUND, *DECOMPOSITION, *IMAGE PROCESSING, *REMOVAL,...

In sparse approximation problems, the goal is to find an approximate representation of a target signal using a linear combination of a few elementary signals drawn from a fixed collection. This paper surveys the major algorithms that are used for solving sparse approximation problems in practice. Specific attention is paid to computational issues, to the circumstances in which individual methods tend to perform well, and to the theoretical guarantees available. Many fundamental questions in...

Topics: DTIC Archive, CALIFORNIA INST OF TECH PASADENA, *APPROXIMATION(MATHEMATICS), *INVERSE PROBLEMS,...

Uncertainty is an unavoidable aspect of engineering systems and will often degrade system performance or perhaps even lead to system failure. As a result, uncertainty must be considered as a part of the design process for all real-world engineering systems. The presence of reducible uncertainty further complicates matters as designers must not only account for the degrading effects of uncertainty but must also determine what levels of uncertainty can be considered as acceptable. For these...

Topics: DTIC Archive, MARYLAND UNIV COLLEGE PARK, *MATHEMATICAL MODELS, *UNCERTAINTY, COEFFICIENTS,...

Efficient reanalysis models, which provide high quality explicit approximations for the structural behavior, are introduced. The presented algorithms are based on a series expansion which is shown to be equivalent to a simple iteration procedure. Only the decomposed stiffness matrix, known from exact analysis of the initial design, is required to obtain the approximate expressions. Two approaches of accelerated convergence are proposed to improve the quality of the approximations: (a) An...

Topics: DTIC Archive, Kirsch, U., Hofman, B., TECHNION - ISRAEL INST OF TECH HAIFA DEPT OF CIVIL...

This paper presents a proof of correctness of an iterative approximate Byzantine consensus (IABC) algorithm for directed graphs. The iterative algorithm allows fault- free nodes to reach approximate consensus despite the presence of up to f Byzantine faults. Necessary conditions on the underlying network graph for the existence of a correct IABC algorithm were shown in our recent work [15, 16]. [15] also analyzed a specific IABC algorithm and showed that it performs correctly in any network...

Topics: DTIC Archive, ILLINOIS UNIV AT URBANA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING, *CONVERGENCE,...

The linear least trimmed squares (LTS) estimator is a statistical technique for fitting a linear model to a set of points. It was proposed by Rousseeuw as a robust alternative to the classical least squares estimator. Given a set of n points in Rd, the objective is to minimize the sum of the smallest 50% squared residuals (or more generally any given fraction). There exist practical heuristics for computing the linear LTS estimator, but they provide no guarantees on the accuracy of the final...

Topics: DTIC Archive, MARYLAND UNIV COLLEGE PARK DEPT OF COMPUTER SCIENCE, *LEAST SQUARES METHOD, *LINEAR...

In this paper we introduce CARRQR, a communication avoiding rank revealing QR factorization with tournament pivoting. We show that CARRQR reveals the numerical rank of a matrix in an analogous way to QR factorization with column pivoting (QRCP). Although the upper bound of a quantity involved in the characterization of a rank revealing factorization is worse for CARRQR than for QRCP, our numerical experiments on a set of challenging matrices show that this upper bound is very pessimistic, and...

Topics: DTIC Archive, CALIFORNIA UNIV BERKELEY DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE,...

This paper provides a methodology for the systematic derivation of subdivision schemes that model solutions to inhomogeneous order linear differential equations. In previous work, we showed that subdivision can be used to capture very efficiently the solutions of homogeneous order, linear differential equations. The resulting subdivision masks are stationary and can be precomputed, allowing for very simple and fast application of these schemes. In this paper, we show that this method can be...

Topics: DTIC Archive, Warren, Joe, Weimer, Henrik, RICE UNIV HOUSTON TX DEPT OF COMPUTER SCIENCE, *LINEAR...

This thesis considers the use of acoustic communications in reducing position uncertainty for collaborating autonomous underwater vehicles. The foundation of the work relies on statistical techniques for accurate navigation without access to GPS, known as Simultaneous Localization and Mapping (SLAM). Multiple AUVs permit increased coverage, system redundancy and reduced mission times. Collaboration through acoustic communications can minimize navigational uncertainty by permitting the group to...

Topics: DTIC Archive, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *ACOUSTIC COMMUNICATIONS, *SELF OPERATION,...

Sequential, adaptive, and gradient diffusion filters are implemented into spatial multiscale three-dimensional variational data assimilation (3DVAR) as alternative schemes to model background error covariance matrix for the commonly used correction scale method, recursive filter method, and sequential 3DVAR. The gradient diffusion filter (GDF) is verified by a two-dimensional sea surface temperature (SST) assimilation experiment. Compared to the existing DF, the new GDF scheme shows a superior...

Topics: DTIC Archive, NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY, *CLIMATE, *OCEAN SURFACE,...

In this thesis we focus on the problem of entanglement in an important class of states, called X-states, that we will introduce. Our study led us to an algebraic formula for the value of multipartite entanglement for X-states. We will take advantage of this formula to further explore the connection of entanglement and mixedness in multipartite systems and study the dynamics of entanglement in open systems. We introduce the entanglement, its definition, and the properties of good measures of...

Topics: DTIC Archive, ROCHESTER UNIV NY, *MATRICES(MATHEMATICS), ALGEBRA, DYNAMICS, FORMULATIONS, FOULING,...

We show how modern techniques of multiple time series analysis can be used to determine if two time series are related by the model: Y(t) = (gamma sub 0)X(t) + (gamma sub 1)X(t - 1) + ETA(t), X(t) + alpha X(t - 1) = epsilon(t). (Author)

Topics: DTIC Archive, Tritchler,David, TEXAS A AND M UNIV COLLEGE STATION INST OF STATISTICS, *TIME SERIES...

This work introduces estimation of disturbance covariance matrices for radar STAP. In particular, we first exploit physically inspired constraints, both the structure of the disturbance covariance and importantly the knowledge of the clutter rank to yield a new rank constrained maximum likelihood (RCML) estimator of clutter/disturbance covariance. We demonstrate that the rank-constrained estimation problem can in fact be cast in the framework of a tractable convex optimization problem, and...

Topics: DTIC Archive, PENNSYLVANIA STATE UNIV STATE COLLEGE, *ADAPTIVE SYSTEMS, *NOISE JAMMERS, *RADAR...

DINO is a new language, consisting of high-level modifications to C, for writing numerical programs on distributed memory multiprocessors. The authors' intent is to raise interprocess communication and process control to a higher and more natural level than using messages. They achieve this by allowing the user to define a virtual machine onto which data structures can be distributed. Interprocess communication is implicitly invoked by reading and writing the distributed data. Parallelism is...

Topics: DTIC Archive, Rosing, Matthew, COLORADO UNIV AT BOULDER DEPT OF COMPUTER SCIENCE, *ALGORITHMS,...

A new method of evaluation of matrix elements of the monopole and dipole terms of the Green's function appearing in volumetric integral equations in acoustics and elasticity is presented. The procedure offers both analytical simplicity and accuracy. It does not require the conventional singularity extraction procedure and it offers improved computational efficiency since it reduces six-dimensional volumetric integrals to four-dimensional surface integrals with nonsingular integrands. The...

Topics: DTIC Archive, MONOPOLE RESEARCH THOUSAND OAKS CA, *TEST AND EVALUATION, *GREENS FUNCTIONS,...