Topics: Radio Program, Human head and neck, Parapsychology, Endocrine system, Community, Pseudoscience,...

Topics: Radio Program, Hurricanes in South Carolina, School types, Category 4 Atlantic hurricanes,...

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Jun 26, 2018
06/18

by
Giovanni S. Alberti; Habib Ammari

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The main focus of this work is the reconstruction of the signals $f$ and $g_{i}$, $i=1,...,N$, from the knowledge of their sums $h_{i}=f+g_{i}$, under the assumption that $f$ and the $g_{i}$'s can be sparsely represented with respect to two different dictionaries $A_{f}$ and $A_{g}$. This generalizes the well-known "morphological component analysis" to a multi-measurement setting. The main result of the paper states that $f$ and the $g_{i}$'s can be uniquely and stably reconstructed...

Topics: Mathematics, Analysis of PDEs, Numerical Analysis

Source: http://arxiv.org/abs/1502.04540

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8.0

Jun 30, 2018
06/18

by
Wuchen Li; Penghang Yin; Stanley Osher

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We propose a fast algorithm to approximate the optimal transport distance. The main idea is to add a Fisher information regularization into the dynamical setting of the problem, originated by Benamou and Brenier. The regularized problem is shown to be smooth and strictly convex, thus many classical fast algorithms are available. In this paper, we adopt Newton's method, which converges to the minimizer with a quadratic rate. Several numerical examples are provided.

Topics: Numerical Analysis, Mathematics

Source: http://arxiv.org/abs/1704.04605

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Jun 30, 2018
06/18

by
Steffen Roch

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We describe the $C^*$-algebra associated with the finite sections discretization of truncated Toeplitz operators on the model space $K^2_u$ where $u$ is an infinite Blaschke product. As consequences, we get a stability criterion for the finite sections discretization and results on spectral and pseudospectral approximation.

Topics: Mathematics, Functional Analysis, Numerical Analysis, Operator Algebras

Source: http://arxiv.org/abs/1401.5237

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Topics: Radio Program, Island countries, Member states of the United Nations, Psychology, Musical quartets,...

Topics: Radio Program, Incorporated cities and towns in California, Crime, Employment compensation,...

Topics: Radio Program, Human head and neck, Parapsychology, Western Asia, Member states of the Organisation...

The goal is to consider the Magnus series expansion for numerically solving the non-linear ODE. The Magnus expansion and other geometric numerical integrators have been successfully used to solve the various equations separately. Different versions of the ME have proved highly efICIENT IN A NUMBER OF PROBLEMS *Quantum Mechanics *Highly oscillatory problems *Eigenvalue problems.

Topics: DTIC Archive, Blanes, Sergio, VALENCIA UNIV (SPAIN), *NUMERICAL ANALYSIS, *MAGNUS EFFECT, QUANTUM...

This effort has achieved its objective of evaluating the feasibility of near-field-physics as a means of discriminating against shallow scrap, in magnetic UXO investigations. In addition, and unexpectedly, the near-field character of UXO has been identified as also being useful for discriminating among different UXO. Modeling the full 3D geometrical complexity of an 80-mm projectile, 155-mm projectile, and 2 pieces of irregular scrap provided the theoretical magnetostatic data required to...

Topics: DTIC Archive, Lieblich, D A, SIV TECHNOLOGIES INC CHERRY VALLEY MA, *UNEXPLODED AMMUNITION,...

It is widely recognized that full-scale dynamic testing produces a wealth of useful information in the context of seismic performance evaluation studies of concrete dams. These types of tests can be used not only to determine the main characteristics of the dynamic response of the structure, but can also provide information to assess the relative importance of interaction mechanisms involving the dam, the impounded reservoir, and the underlying foundation region. The information gathered by...

Topics: DTIC Archive, Duron, Ziyad, ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND...

We present methodology for obtaining forward solutions to Maxwell's equations in two dimensions, in the presence of a Debye medium. Perfectly Matched Layer (PML) absorbing boundary conditions are used to absorb incoming energy at the finite boundaries. A time-domain, PDE formulation is presented, and a finite difference time-domain (FDTD) algorithm is used to obtain numerical solutions. A least squares formulation of the inverse problem results from a careful consideration of the noise model...

Topics: DTIC Archive, Banks, H T, NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC...

Sandwich structures become increasingly important as structural parts in helicopters. This does not only have effect on the way of construction but also on the vulnerability of the helicopter. The last decades the threat of helicopters has increased in military circumstances. Consequently the helicopters will be exposed to weapon effects like high blast loads and fragment impact more frequently. Moreover the blast load becomes more important because the threat comes closer to the target. At TNO...

Topics: DTIC Archive, van't Hof, C, TNO DEFENSE SECURITY AND SAFETY RIJSWIJK (NETHERLANDS), *PENETRATION,...

We fabricated side-gated quantum-dot structures on a GaAs/AlGaAs single heterostructure and measured their magnetoresistance at low temperature. We observed that oscillations appear almost periodic in B for a lower magnetic field region. We find that the oscillation period is fairly independent of the structure width. The experimental magnetoconductance are compared with numerical results.

Topics: DTIC Archive, Suzuki, T, OSAKA UNIV (JAPAN) DEPT OF ELECTRONIC ENGINEERING, *OSCILLATION,...

A series of shock tube experiments performed in the 1970s at the Institute for Aerospace Studies, University of Toronto, led in the discovery of instabilities in relaxing shock structures in noble gases under hypervelocity conditions. The instabilities were oscillatory in nature and found to affect the entire shock structure including the translational front, induction zone, and electron avalanche. Theoretical models were first developed in order to reproduce the length and time scales of the...

Topics: DTIC Archive, OHIO STATE UNIV COLUMBUS DEPT OF MECHANICAL ENGINEERING, *NONEQUILIBRIUM FLOW,...

The Algorithm presented in this report is designed for use in smoothing 3-D data at NUWES. It uses fourth-order sequential differences to screen the data for outliers and then a special form of least-squares smoothing is performed to select an appropriate low-order polynomial and fit it to seven-point data segments.

Topics: DTIC Archive, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *ALGORITHMS, *THREE DIMENSIONAL,...

In this article, we present the details of the structural acoustic approach to fault monitoring, describe various inversion algorithms for extracting the fault information, show the results of numerical feasibility studies, discuss the associated measurement technologies, and then present applied studies we have carried out using this methodology. These include both laboratory-based studies on simple structures and spin-off work we have done on art-laden walls at the U.S. Capitol building.

Topics: DTIC Archive, NAVAL RESEARCH LAB WASHINGTON DC ACOUSTICS DIV, *FAULT DETECTION, *VIBRATION,...

This paper is concerned with the mathematical analysis of the time-domain Maxwell equations in a three-dimensional cavity. An exact transparent boundary condition (TBC) is developed to reformulate the open cavity scattering problem in an unbounded domain equivalently into an initial-boundary value problem in a bounded domain. The well-posedness and stability are studied for the reduced problem. Moreover, an a priori estimate is established for the electric field with a minimum regularity...

Topics: DTIC Archive, AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH DEPT OF MATHEMATICS AND...

Nature abounds with complex patterns and structures emerging from homogenous media operating far from thermodynamic equilibrium. Such phenomena, which are widely observed in both inanimate (non-biological) and biological media, can be modeled and studied via the CNN (Cellular Neural/Nonlinear Network) paradigm in an in-depth and unified way. Whether a homogeneous medium is capable of exhibiting complexity depends on whether the CNN cells, or its couplings, is locally active in a precise...

Topics: DTIC Archive, Chua, Leon O., CALIFORNIA UNIV BERKELEY DEPT OF ELECTRICAL ENGINEERING AND COMPUTER...

The diocotron spectrum for a simplified model of Malmberg-Penning traps that includes compression effects due to end curvature is investigated herein. Performing an initial value treatment, we find that there is a class of length profiles for which the linearized eigenvalue equation of the model can be integrated in quadratures (integrable case). In this case, there is only algebraic growth when the effective angular frequency has a maximum (hollow profile) or a minimum, and the model is...

Topics: DTIC Archive, Delzanno, G. L., Pariev, V. I., Lapenta, G., Finn, J. M., LOS ALAMOS NATIONAL LAB NM,...

One way to perform CAA simulations is to split the flow field in a steady mean flow and turbulent and acoustic fluctuations The small acoustic fluctuations can then be calculated from linearized Euler equations (LEE). The mean flow can be supplied by the solution of the Reynolds averaged Navier-Stokes (RANS) equations. Since different numerical requirements exist for the numerical grids of RANS and LEE simulations, an interpolation procedure between RANS and LEE grids is necessary. The...

Topics: DTIC Archive, Lummer, M., Grogger, H. A., Delfs, J. W., DEUTSCHES ZENTRUM FUR LUFT-UND RAUMFAHRT...

The focus of the present work is on the numerical simulation of steady flows with spilling breaking waves. In particular, the breaker is modeled through a hydrostatic pressure and a shear stress exerted on the free-surface. Many elements of the exposed model are derived by Cointe and Tulin's theory of steady breaker. The model has been implemented in a RANSE code in a simple but effective way through a modification in the free-surface boundary conditions. At present, the resulting code is valid...

Topics: DTIC Archive, Muscari, R., Di Mascio, A., FLORENCE UNIV (ITALY) DEPT OF ENERGETICA, *SIMULATION,...

Monterey Bay is located 100 km south of San Francisco and is one of several large bays on the West Coast of the United States. This area is important due to the abundance of marine life. The regional circulation in the Monterey Bay area is tightly coupled to the California Current System (CCS) and highly correlated to the coastal upwelling. In the offshore region, flow is dominated by a broad, weak, equatorward flowing current, the California Current (CC). The CC extends offshore to a distance...

Topics: DTIC Archive, Tseng, Y. H., Dietrich, D. E., Ferziger, J. H., ACUSEA INC ALBUQUERQUE NM, *OCEAN...

Topics: DTIC Archive, KAO, R C, RAND CORP SANTA MONICA CA, *ECONOMICS, *NUMERICAL ANALYSIS, COSTS,...

Analytical approximations of Bessel functions and of mach numbers in terms of pressure ratio are given.

Topics: DTIC Archive, RAND CORP SANTA MONICA CA, *BESSEL FUNCTIONS, *NUMERICAL ANALYSIS,...

The paper presents a numerical investigation of a bounded ocean basin on the spherical earth, with particular attention directed to the role of planetary circulations. The time-dependent primitive equations are solved for a shallow, wind-driven, homogeneous ocean in a basin of uniform depth on the sphere. In a series of comparative numerical solutions, it is shown that at least a 2-degree resolution is needed to resolve the western boundary currents adequately and to avoid undue distortion of...

Topics: DTIC Archive, Gates, W L, RAND CORP SANTA MONICA CA, *OCEAN WAVES, *WIND, BOUNDARY VALUE PROBLEMS,...

A thermal analysis of the M140 counterrecoil spring was carried out by the Research Directorate, Weapons Laboratory at Rock Island. An investigation was made to determine the significant physical parameters influencing temperature rise of the counterrecoil spring when this spring rubs against the wall of the cradle recoil-mechanism, and to obtain data for design changes to reduce the temperature rise. A mathematical model of the frictional heating process was developed and programmed for...

Topics: DTIC Archive, Leech, William J, ARMY WEAPONS COMMAND ROCK ISLAND IL RESEARCH DEVELOPMENT AND...

To achieve an economically optimum level of reliability each improvement step is warranted only if the expected reduction in cost of failure exceeds the cost of the improvement. To this end, techniques for calculating cost of failure are described, in particular a new technique for evaluating cost of failure for long-time spacecraft missions. Guidelines for assessment of the economic impact of various improvement techniques are presented.

Topics: DTIC Archive, Hecht, H, AEROSPACE CORP EL SEGUNDO CA OFFICE FOR TECHNOLOGY, *COMPUTERS, *SPACECRAFT...

The frictional identation problem for an elastic half space is formulated in terms of a coupled pair of singular integral equations, leading to determination of adhesive boundary as an eigenvalue of Fredholm equation with positive kernel.

Topics: DTIC Archive, Spence, D A, WISCONSIN UNIV-MADISON MATHEMATICS RESEARCH CENTER, *INTEGRAL EQUATIONS,...

The paper presents a numerical solution of problems of the parametric boundary layer theory in a two-parameter approximation. The partial differential boundary layer equation is solved by a finite difference method using an implicit difference scheme, and the results obtained serve as the initial data. The derivatives in the original equation are replaced by finite difference equations, and the resulting system is solved by a brute force method. A table lists the numerical results obtained by...

Topics: DTIC Archive, Ozerova, E F, ARMY FOREIGN SCIENCE AND TECHNOLOGY CENTER CHARLOTTESVILLE VA,...

The author considers quadrature formulae (q.f.) for the numerical evaluation of the Fourier, cosine, sine, and Laplace transformations.. Three different approaches are used to construct our q.f.: either integrate an appropriate spline interpolant to f(x), require our q.f. to be exact for a particular sequence of so-called B-splines, or utilize a particular monospline. In any case, the generality and utility the author achieves is due to the form of the splines the author uses in particular to...

Topics: DTIC Archive, Silliman, Sherwood D, WISCONSIN UNIV-MADISON MATHEMATICS RESEARCH CENTER, *INTEGRAL...

In this paper the author discusses aspects of numerical mathematics which are related to computer science. The following topics are discussed: Historical perspective; A definition of numerical mathematics; Foundations; Synthesis and analysis of algorithms; Analysis of error; Programs and program libraries.

Topics: DTIC Archive, Traub, J F, CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF COMPUTER SCIENCE, *COMPUTER...

A displacement solution for the calculation of structural influence coefficients (SIC's) is presented. The formulation utilizes the lumped parameter approach that is consistent with collocation flutter solutions. The structure is synthesized as concentrated mass elements connected by massless elastic plates and/or beams. There are two methods of generating the mass matrix; they are: (1) lumped concentrated mass points, (2) consistent mass matrices. Along with the calculation of the SIC's, the...

Topics: DTIC Archive, Ulbrich, Donald R, HUGHES AIRCRAFT CO CANOGA PARK CA MISSILE SYSTEMS DIV, *COMPUTER...

An analytical study of helicopter gust response at high forward speeds is presented. A digital-computer program is described that includes rigid-body aircraft motions in space and the aeroelastic representation of two rotors. The rotors can be positioned to describe all general configurations. Various rotor types are considered, as well as compounding by the use of wings and auxiliary propulsion. Various maneuvers may be simulated, including subjecting the aircraft to gust disturbances. Results...

Topics: DTIC Archive, Harvey, Keith W, BELL HELICOPTER TEXTRON INC FORT WORTH TX, *AEROELASTICITY, *GUST...

An analysis of numerical methods for extracting aerodynamic coefficients from dynamic test data has been conducted. The emphasis of the analysis is on the effects that random measurement errors in the data and random disturbances in the system have on the accuracy with which the coefficients for linear and nonlinear systems can be determined. Both deterministic and stochastic methods for extracting the coefficients and determining their uncertainties are considered. The deterministic technique...

Topics: DTIC Archive, Daniel, Donald C, FLORIDA UNIV GAINESVILLE, *STOCHASTIC PROCESSES, BODIES OF...

A two-dimensional analysis of the cross section of a salient-pole, synchronous aircraft alternator under no load is reported. The nonlinear effects of magnetic saturation were considered. The solution algorithm is a modified version of an algorithm previously used in the analysis of nonlinear, homopolar-inductor alternators. The details of the algorithm and the computer programs implemented on a minicomputer were described in earlier MERADCOM reports. This report contains teletypewriter...

Topics: DTIC Archive, Goss,Melvin L, ARMY MOBILITY EQUIPMENT RESEARCH AND DEVELOPMENT COMMAND FORT BELVOIR...

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4.0

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Topics: Radio Program, Parapsychology, Human head and neck, Pseudoscience, Endocrine system, German...

We obtain analytical solutions for the perturbed shock paths induced by time-varying random motions of a piston moving inside an adiabatic tube of constant area. The variance of the shock location grows quadratically with time for early times and switches to linear growth for longer times. The analytical results are confirmed by stochastic numerical simulations, and deviations for large random piston motions are established.

Topics: DTIC Archive, Lin, G, BROWN UNIV PROVIDENCE RI DIV OF APPLIED MATHEMATICS, *PISTONS, STOCHASTIC...

This proposal concerns modeling, analysis, and computational simulations of some non-linear interface problems and applications, that, we believe, are of interests to DOD/ARO missions especially in the fields of computational geometry, computational fluid mechanics, non-linear dynamics, imaging processing, and inverse scattering. Most of our previous work has been focused on linear interface problems with discontinuities. We have been focusing on non-linear interface problems and applications...

Topics: DTIC Archive, Li, Zhilin, NORTH CAROLINA STATE UNIV AT RALEIGH OFFICE OF CONTRACTS AND GRANTS,...

The words Left Handed Materials in the Title were one early way of expressing what is now termed Negative Index (of refraction) Metamaterials or NIMs In our proposal for this grant we focused on four general Goals: (1) Lowering the losses for the wire and SRR (split ring resonators) based unit cell construction designed to produce a desired negative permittivity (c) and negative permeability (micron) set of values. (2) Extend the theoretical concepts for making new types of NIMs, and then...

Topics: DTIC Archive, Schultz, Sheldon, CALIFORNIA UNIV REGENTS SAN DIEGO LA JOLLA CA, *MATERIALS,...

This technical report presents numerical simulations of the ultra-wideband (UWB) radar return from a simple room with a human inside, with application to sensing through the wall (STTW) radar scenarios. We use the Finite Difference Time Domain (FDTD) and Xpatch modeling techniques to compute the range profiles of the room at specific incidence and observation angles. Our goal is to analyze the electromagnetic phenomenology in operating an UWB radar for STTW applications. At the same time, we...

Topics: DTIC Archive, Dogaru, Traian, ARMY RESEARCH LAB ADELPHI MD, *FINITE DIFFERENCE TIME DOMAIN,...

Complex variable, numerical differentiation techniques have proven useful in many fields of engineering analysis. Complex Taylor series expansion and Fourier differentiation are two such complex variable methods. This paper adapts the use of both complex Taylor series expansion and Fourier differentiation for fatigue sensitivity analysis. The sensitivity of the number of cycles to failure to input parameters and initial conditions has been determined by traditional numerical differentiation...

Topics: DTIC Archive, TEXAS UNIV AT SAN ANTONIO DEPT OF MECHANICAL ENGINEERING AND BIOMECHANICS,...

The South Florida Hybrid Coordinate Ocean Model (SoFLA-HYCOM) encompasses a variety of coastal regions (the broad Southwest Florida shelf, the narrow Atlantic Keys shelf, the shallow Florida Bay, and Biscayne Bay) and deep regions (the Straits of Florida), including Marine Protected Areas (the Florida Keys Marine Sanctuary and the Dry Tortugas Ecological Reserve). The presence of the strong Loop Current/Florida Current system and associated eddies connects the local and basin-wide dynamics. A...

Topics: DTIC Archive, NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV, *OCEAN MODELS, COASTAL...

This paper focuses on finite minimax problems with many functions, and their solutions by means of exponential smoothing. We conduct run-time complexity and rate of convergence analysis of smoothing algorithms and compare them with those of SQP algorithms. We find that smoothing algorithms may have only sublinear rate of convergence, but as shown by our complexity results, their slow rate of convergence may be compensated by small computational work per iteration. We present two smoothing...

Topics: DTIC Archive, NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OPERATIONS RESEARCH,...

Topics: Radio Program, American columnists, American political writers, Environmental skepticism, American...

Computational results for the response of piezoelectric materials to various excitations are presented. The governing equations are based on a second-order theory of piezoelectricity, which is specialized for the 6mm crystal class. The equations are formulated in a Lagrangian reference configuration. These equations represent the fully coupled nonlinear multiphysics response. Numerical solutions of these equations are first verified using analytical solutions for wave propagation in linear...

Topics: DTIC Archive, ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD, *PIEZOELECTRIC MATERIALS, COEFFICIENTS,...

This paper addresses the construction of a consistent interval estimator for the steady-state mean within a replication/deletion framework for output analysis when MSER truncation is applied. Because the MSER truncation point is a random variable, the truncated output sequences for each replication typically are un-equal in length. A weighting scheme is applied to the replication means to correct for unequal sample sizes, as is standard in ANOVA. A numerical example is provided to illustrate...

Topics: DTIC Archive, NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OPERATIONS RESEARCH, *TRUNCATION,...

The flux formulation of propagation has been used to calculate reverberation, target echo, and signal excess very efficiently in a model developed by Harrison called Artemis. This model is used in the operational planning aid MSTPA at CMRE. Propagation in this formulation falls off monotonically with range. The goal of the ONR-funded work is to improve the propagation accuracy by including convergence and focusing effects without compromising the simplicity and efficiency of the approach. The...

Topics: DTIC Archive, CENTRE FOR MARITIME RESEARCH AND EXPERIMENTATION LA SPEZIA (ITALY), *NUMERICAL...

Main objective: To perform a realistic, truly eddy resolving, windand buoyancy-forced numerical simulation of the global ocean with sophisticated data assimilation techniques that can be efficiently executed on massively parallel computers. To assess its nowcast/forecast capabilities for both Lagrangian trajectories and 3-D Eulerian fields such as velocity, temperature, salinity, and density.

Topics: DTIC Archive, NAVAL RESEARCH LAB STENNIS DETACHMENT STENNIS SPACE CENTER MS, *EDDY CURRENTS,...

Lightweight advanced materials are critical in the manufacturing of many Army vehicles. Recently, numerical tools have been utilized to customize experiments to achieve optimized behavior of micro/nano polymer composites (MNPCs). Most numerical studies are based on characterizing the MNPCs through simple microstructures, as circular particles or straight fibers embedded in a specific polymer matrix. Although these geometries are effective in virtually modeling some types of composite material...

Topics: DTIC Archive, TEXAS ENGINEERING EXPERIMENT STATION COLLEGE STATION, *COMPOSITE MATERIALS,...