... Title : USE OF TAYLOR SERIES EXPANSIONS FOR TIME SAVINGS IN COMPUTATION OF ACCURATE TRANSDUCER PRESSURE FIELDS. ...
DTIC Science & Technology
... scaling of MOSFETs induces higher electric fields in the channel because the power supply voltage ... can accurately estimate the distribution of high ...
A numerical procedure was developed to compute the inviscid super/hypersonic flow fields about complex vehicle geometries accurately and efficiently. A second-order accurate finite difference scheme is used to integrate the three-dimensional Euler equatio...
National Technical Information Service (NTIS)
The goal of this project is to accurately predict the high altitude wave energy generated by low altitude VLF sources. We applied full-wave finite difference numerical models of the electromagnetic fields in both time and frequency domain to compute the V...
QSS Group, Inc. NASA Glenn Research ... The field of Computational Aeroacoustics (CAA) is concerned with the time-accurate calculation of ... Schemes for Computational Acoustics', Journal of Computational Physics, Vol. 107,. 10)Hixon, R. ...
NASA Website
A powerful, flexible system of computer programs was developed for the computation of self-consistent-field wavefunctions for small polyatomic molecules in a gaussian basis. Accurate wavefunctions were computed for water, formaldehyde, and ethylene. A pre...
... recently been modified to more accurately simulate layered field conditions which often exist in disposal sites. The modified computer program is ...
Two main approaches are available for the rational design of networks, the statistical and the experimental. The statistical approach presupposes the ability to compute accurate correlation functions of the meteorological fields to be observed and analyze...
... computer-assisted technologies allow doctors to construct 3D radiation fields that accurately target tumor tissue while avoiding injury to important brain structures like the hearing centers. ...
MedlinePLUS
The Field of Automated Reasoning* M Larry Wos athematics and Computer Science Division Argonne National Laboratory Argonne, IL 60439�4801 T Abstract he term automated reasoning (first introduced in 1980) accurately describes the objective of the field, d the automation of logical reasoning. This article
E-print Network
Probe pattern compensation is essential in near-field scanning geometry, where there is a great need to accurately know far-field patterns at wide angular range. This paper focuses on a novel formulation and computer simulation to determine the precise ne...
A near-field acoustic measurement technique which provides the basis for accurately computing the far-field radiation characteristics of underwater sound transducers is developed, implemented and evaluated. The analysis is based on evaluating a form of th...
A numerical procedure has been developed to compute the inviscid super/hypersonic flow field about complex vehicle geometries accurately and efficiently. A second order accurate finite difference scheme is used to integrate the three dimensional Euler equ...
A versatile combination of hardware and software on the LLL T-DAC computer system has been developed that permits rapid and accurate modal analysis of complex mechanical structures under field conditions. Natural frequencies of vibration and values of dam...
At the outset of this contract, the focus of attention was the fast multipole method (FMM) for the Maxwell equations. The FMM essentially provides for a fast and accurate computation of non-near (in a sense made precise in fields of specified currents). T...
Accurate modeling of near-field wave propagation is critical to determine blast wave overpressure of large caliber muzzle brakes. Experimental testing to determine blast overpressure is costly, making computational fluid dynamics (CFD) simulations of thes...
The transport of charged particle beams requires magnetic fields that must be shaped correctly and very accurately. During the last 20 years or so, many studies have been made, both analytically and through the use of computer programs, of various magneti...
A technique is proposed for computing the field radiated from a rectangular aperture. This technique, based on the discrete fractional Fourier transform, avoids the complexities of computing the diffraction pattern by the direct evaluation of the Fresnel integral. The advocated approach provides a fast and accurate ...
PubMed
A numerical procedure was developed to compute the inviscid super/hypersonic flow field about complex vehicle geometries accurately and efficiently. A second-order accurate finite difference scheme is used to integrate the three-dimensional Euler equation...
High precision mapping of the vacuum flux surfaces of the H-1NF heliac is carried out using electron-beam multi-wire tomography for various magnetic configurations and field strengths. The extreme accuracy of this technique has been exploited to understand the nature of error fields and to determine the best-fit empirical values for the H-1NF coil ...
Energy Citations Database
NASA Astrophysics Data System (ADS)
We discuss a class of phase computer-generated holograms for the encoding of arbitrary scalar complex fields. We describe two holograms of this class that allow high quality reconstruction of the encoded field, even if they are implemented with a low-resolution pixelated phase modulator. In addition, we show that one of these holograms ...
We present a numerical method based on the generalized pseudospectral discretization in prolate spheroidal coordinates and split-operator time propagation. The method has been applied for the study of multiphoton processes of H+2 and N2 diatomic molecules in intense laser fields. It proves very accurate while using only moderate ...
Developments in permanent magnet materials such as alnicos, rare-earth cobalts and ferrites have brought in their wake new interest in their application to the design of electrical machinery, torque couplers, lifting magnets, and other electromechanical devices. In all these cases, the magnetic field provides the medium for energy conversion. The accurate ...
this paper we conduct a careful study to assess the numerical mesh resolution requirements for the accurate computation of sonic boom ground signatures produced by complete aircraft configurations. The details of the ground signature can be highly dependent on the accurate prediction of the pressure distribution in the ...
This paper presents an application of the three dimensional Navier-Stokes computations in designing a turbine vane cascade. The accurate prediction of the cascade flow characteristics such as total pressure loss and outlet flow angle is important for aero...
Computer codes which were based upon a special integral representation of the external solutions of the Helmholtz equation were upgraded so that they would yield accurate results for the acoustic radiation patterns in the field surrounding an axisymmetric...
In the study the speed limits of potential flow part of SHIPFLOW computational fluid dynamics program were found out. It was also evaluated how accurate and reliable the program is when calculating the flow field of a fast ship with immersed transom stern...
An experiment with a microwave open resonator of the Fabry-Perot type is described. The field distribution of the fundamental mode has been accurately determined. A very good agreement has been found with the distributions computed by Fox and Li. It has b...
Accurate self-consistent-field functions were computed for several small polyatomic molecules, including benzene, in a basis of Gaussian functions. All multicenter molecular integrals were calculated and the core electrons explicitly included. This work r...
A new approach to quantitative deformation characterization of high-resolution electron microscopy (HREM) defect images has been developed. The principle of this technique, (Computational Fourier Transform Deformation (CFTD)) is to extract an accurate dis...
An accurate evaluation of doses caused by external sources of neutron radiation depends on knowledge of the transport of radiation inside the human body. Health physicists use two primary methods for studying this radiation transport: computer calculation...
Geodetic satellites such as GEOSAT, SPOT, ERS-1, and TOPEX/Poseidon require accurate orbital computations to support the scientific data they collect. Until recently, gravity field mismodeling was the major source of error in precise orbit definition. How...
The general objective of computer driver adaptive testing is to accurately estimate an individual's position on the underlying trait the test purports to measure. Conventional paper-and-pencil test administration typically suffers from several sources of ...
The method of characteristics has proven to be a highly accurate and relatively straight forward technique for computing the supersonic flow field in a two-dimensional or axisymmetric nozzle. However, the method of characteristics requires an initial valu...
A quantitative model of the magnetospheric magnetic field and associated procedures for accurately cataloging charged-particle data out to and beyond geosynchronous orbit is developed. The magnetic field model incorporates all major magnetospheric current systems and is valid for all tilt angles; i.e., angles of incidence of the solar ...
Page 1. EFFICIENT AND ACCURATE COMPUTATION OF NON-NEGATIVE ANISOTROPIC SCATTERING CROSS SECTIONS ...
A simplified mathematical model for the far field of a monomode diode laser is employed for easy but fairly accurate computations of the optical field in the focal region. The present treatment is concerned with laser junctions significantly narrower than the wavelength. The field distribution ...
Laminar mixed convection in a barrel reactor is studied for the case when buoyancy assists the forced flow. Temperature dependent fluid properties are considered. A control volume based numerical technique is used to compute the coupled flow and temperature fields. Computations are also performed assuming constant properties, and the ...
The accurate computation of the external magnetic field from a permanent magnet motor is accomplished by first computing its magnetic scalar potential. In order to find a solution which is valid for any arbitrary point external to the motor, a number of p...
The magnetic fields generated by a typical distribution substation were measured and calculated based on a computer model which takes into account currents in the grounding systems, distribution feeder neutrals, overhead ground wires and induced currents in equipment structures and ground grid loops. Both measured and computer results ...
The authors compare the results of computer simulated flow fields around building 170 (B170) at Lawrence Livermore National Laboratory (LLNL) with field measurements. This is the first stage of a larger effort to assess the ability of computational fluid dynamics (CFD) models to predict atmospheric dispersion ...
An alternative method is developed to compute the magnetic field from a circular cylindrical magnetic source. Specifically, a Fourier series expansion whose coefficients are toroidal functions is introduced which yields an alternative to the more familiar spherical harmonic solution or the Elliptic integral solution. This alternate formulation coupled with ...
DOE Information Bridge
In the area where there is no field source, gravity field and magnetic field have similar properties. They all satisfy Laplace equation. In the area in which we need solution, the boundary low gradient values can be considered as the values of regional background field, so that separating out gravity anomalous ...
This study comparing momentary time sampling against the real time obtained with handheld computers confirmed laboratory findings that short-elementary time sampling estimates percentage time accurately for a wide range of behavior frequencies and durations, and suggested that observers using momentary time sampling in a natural setting are able to obtain ...
ERIC Educational Resources Information Center
An electromagnetic method based on rigorous diffraction theory of gratings is applied to the analysis of fields in semiconductor laser cavities. The method is based on the Fourier modal method; it is fully rigorous for infinitely periodic resonators and highly accurate for single resonators when absorbing boundary conditions are applied. Fundamental-mode ...
An approach to Witten string field theory based on the discretization of the world sheet is adopted. We use it to calculate tree amplitudes with the formulation of the theory based on string functionals. The results are evaluated numerically and turn out to be very accurate, giving, for a string approximated by 600 points, values within 0.02% of the ...
A distance field is a representation where, at each point within the field, we know the distance from that point to the closest point on any object within the domain. In addition to distance, other properties may be derived from the distance field, such as the direction to the surface, and when the distance field ...
... Accession Number : ADA534986. Title : Accurate Modeling of Ionospheric Electromagnetic Fields Generated by a Low Altitude VLF Transmitter. ...
The current study simultaneously addresses the problem of reflection and refraction of sound from a rigid porous ground surface. A more rigorous approach is used to derive more accurate asymptotic solutions that can be cast in a convenient form for ease of numerical implementations. The solutions provide means for rapid computations of the sound ...
The modeling of fusion plasmas requires the accurate modeling of the fields which confine these plasmas. BSC/T is a Fortran module which allows for accurate and expedient computation of these fields from the currents which produce them. Near field producing elements, ...
Although many microenvironmental factors contribute to the color shift of light emission from the firefly chromophore, the dominant one is the local electrostatic field. This opens up the possibility of accurate color tuning the bioluminescent absorption and emission by adjusting the local charged residues. With this aim, the optical response of ...
Laser beam front distortions characterizing near field losses of energy from a turret mounted on a generic helicopter have been computed to support the modeling and simulation effort of a directed energy testing. The flow field has been computed using an unstructured computational fluid ...
A method is presented that allows the computation of space charge effects of arbitrary and large distributions of particles in an efficient and accurate way based on a variant of the Fast Multipole Method (FMM). It relies on an automatic multigrid-based decomposition of charges in near and far regions and the use of high-order differential algebra methods ...
In a previous paper, the authors introduced an original model for the computation of the triboelectric charges due to particle-to-particle collisions in a vibrated bed. The evaluation of the electric field inside the particle bed is a prerequisite for the accurate modelling of the tribochaging process, as it determines the trajectory ...
The behavior of orbits in charged-particle beam transport systems, including both linear and circular accelerators as well as final focus sections and spectrometers, can depend sensitively on nonlinear fringe-field and high-order-multipole effects in the various beam-line elements. The inclusion of these effects requires a detailed and realistic model of the interior and ...
Numerical simulations of (i) the propagation and interactions of one-dimensional Langmuir solitons and (ii) their generation from random fluctuations by an external pump field are presented. The results of particle simulations are compared with computations based on Zakharov's fluid model. Those computations establish that ...
A general purpose program for drift chamber studies is described. First the capacitance matrix is calculated using a Green's function technique. The matrix is used in a linear-least-squares fit to choose optimal operating voltages. Next the electric field is computed, and given knowledge of gas parameters and magnetic field ...
The flow field is computed around a 1 cm diameter Leonid meteoroid as it enters the Earth's atmosphere at an altitude of 95 km and a velocity of 72 km/s. These conditions correspond to a Knudsen number of 4 and a Mach number of 270. To accurately compute the gas flow, these extreme nonequilibrium conditions require ...
A numerical analysis of large-signal klystron behavior based on general wave-particle interaction theory is presented. The computer code presented is tailored for the minimum amount of complexity needed in klystron simulation. The code includes self-consistent electron motion, space-charge fields, and intermediate and output fields. It ...
The computational damping and dispersion errors of some simple numerical schemes for calculating the advection of a scalar are analyzed. Computation times and accuracy are compared in calculating the two-dimensional transport of a symmetrical distribution in a uniform rotational flow field. Amplification factors, ...
Mean-Field homogenization algorithms for materials involving two or more elastic-plastic constituent phases are investigated. The Voigt, Reuss and Self consistent schemes which are directly applicable to multi-phase systems are implemented. The shortcomings of these schemes are accuracy for the former two and computational efficiency for the latter. A new ...
Cone Beam Computed Tomography (CBCT) is a diagnostic imaging modality that provides high-quality, accurate three-dimensional (3D) representations of the osseous elements of the maxillofacial skeleton. CBCT systems are available that provide small field of view images at low dose with sufficient spatial resolution for applications in ...
PubMed Central
Three of the four simulators used in computing a difficult three-dimensional problem show excellent quantitative agreement. This demonstrates that numerical simulators are capable of producing accurate results for field-wide reservoir depletion problems, involving phase transitions, gravitationally induced steam/water counterflow, and ...
Four cases of optic disk drusen were accurately diagnosed with orbital computed tomography (CT). The radiologist should be aware of the characteristic CT finding of discrete calcification within an otherwise normal optic disk. This benign process is easily differentiated from lesions such as calcific neoplastic processes of the posterior globe. CT ...
A comprehensive computational procedure is presented for predicting the supersonic region of the flow field on advanced reentry vehicle shapes in steady flight at pitch and yaw. The procedure utilizes explicit second order accurate finite difference metho...
Accurate computation of sensitivity derivatives is becoming an important item in Computational Fluid
NASA Technical Reports Server (NTRS)
Muon accelerators contain beam lines and components which are unlike any found in existing accelerators. Production of the muons requires targets for beams with powers which are at or beyond what has currently been achieved. Many subsystems use solenoid focusing systems where at any given point, several magnets have a significant influence. The beams that are transported can have energy spreads of ...
In the plane wave approximation, we study spatio-temporal dynamics of a semiconductor class B laser driven by a coherent injected field in a Fabry-Perot configuration. Below the lasing threshold, we manage to reduce the dynamics to a single evolution equation for the carrier density, to analytically compute the stationary field ...
The dynamics of trapped particles in the presence of the wiggler magnetic field and the electromagnetic radiation field in free electron lasers were investigated. From the results of computer simulations, it was found that, for a given set of parameters, the efficiency of energy extraction from the electron beam maximizes at a ...
Autonomous beam alignment for coherent Doppler lidar requires accurate information about optical misalignment and optical aberrations. A multielement heterodyne detector provides the required information without a loss in overall system performance. The effects of statistical variations from the random backscattered field (speckle ...
The adiabatic compression of an elongated field-reversed configuration (FRC) is computed by using a one-dimensional approximation. The one-dimensional results are checked against a two-dimensional equilibrium code. For ratios of FRC separatrix length to separatrix radius greater than about ten, the one-dimensional results are accurate ...
The versatile GPS Pathfinder� Pro XRS receiver is the thoroughbred of GPS receivers. Offering a full range of accurate real-time correction sources, great performance in all GPS conditions backpack system Choice of field computer and field software DATASHEET HIGH-PERFORMANCE GPS WITH A WORLD
The accurate computations of hydrogenic continuum wave functions are very important in many branches of physics such as electron-atom collisions, cold atom physics, and atomic ionization in strong laser fields, etc. Although there already exist various algorithms and codes, most of them are only reliable in a certain ranges of ...
The geomagnetic field is an important parameter in space physics. The International Geomagnetic Reference Field (IGRF) is a model of the Earth's main field. Current sources in the ionosphere, the interplanetary magnetic field, annual and diurnal variation, and other sporadic and unmodeled effects may alter the ...
The Field Grid Sense system was adapted to locate and record crop yield in the field. Accurate measurement of yield in spatially variable fields is needed to achieve maximum profitability in crop production. The harvester system is composed of a laptop computer, data acquisition system, fifth ...
The Volume Integral Equation Method (VIEM) has been used for the solution of three-dimensional non-linear magnetostatic field problems. The number of unknowns is minimal as only the magnetic material has to be discretized. For accurate solutions of problems where the magnetic field is small compared to the excitation ...
A two-stage computational procedure is presented for the accurate determination of transverse normal
Magsat, designed for making measurements of the geomagnetic vector field, is evaluated. For accurate
Electromagnetic compatibility studies require knowledge of transient voltages that may be developed near earthing systems during lightning discharge, since such voltages may be coupled to sensitive electronic circuits. For such purpose accurate evaluation of transient electric field near to and/or at the surface of the grounding conductors is necessary. In ...
Boundary-element methods (BEMs) for solving integral equations numerically have been used in many fields to compute the induced charges at dielectric boundaries. In this paper, we consider a more accurate implementation of BEM in the context of ions in aqueous solution near proteins, but our results are applicable more generally. The ...
In this paper we consider the frictional (tangential) steady rolling contact problem. We confine ourselves to the simplified theory, instead of using full elastostatic theory, in order to be able to compute results fast, as needed for on-line application in vehicle system dynamics simulation packages. The FASTSIM algorithm is the leading technology in this ...
... initialization and language usability. ... of simulation programming languages is dependent ... the fields of computer languages, computer graphics, and ...
Safe, efficient operation of waste tank farm facilities is dependent in part upon the availability of accurate, up-to-date plant drawings. Accurate plant drawings are also required in support of facility upgrades and future engineering remediation projects. This supporting document establishes the procedure for performing a visual ...
In the past, old gamma ray neutron (GRN) (1940's to 1960's) and old electric (E) logs were not widely used for detailed log analysis because performing this task accurately is manpower intensive. Recent developments in computer hardware and software have made it feasible to digitize and analyze old logs to obtain more ...
Photorealistic Image Synthesis is a relevant research and application field in computer graphics, whose aim is to produce synthetic images that are undistinguishable from real ones. Photorealism is based upon accurate computational models of light material interaction, that allow us to compute ...
