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in subjects: "Equations"

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COMP: a BASIC language nonlinear least-squares curve fitting program

COMP is an interactive nonlinear least squares routine written in BASIC language and used to obtain estimates of parameters in nonlinear functions and to approximate their associated statistical errors. The program uses the linearizing (or Taylor Series) expansion of partial derivatives outlined in Draper and Smith, (1966, pp. 267 to 270). Therefore, partial derivatives must be supplied (as well as the function) by the user for any new models not currently contained in the programs. When a line… more

Date: November 1, 1977

Creator: Thomas, J. M.; Cochran, M. I.; Watson, C. R. & Eberhardt, L. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Continuum damping of low-n toroidicity-induced shear Alfven eigenmodes

The effect of resonant continuum damping is investigated for the low-mode-number, toroidicity-induced, global shear Alfven eigenmodes, which can be self-excited by energetic circulating alpha particles in an ignited tokamak plasma. Resonant interaction with the shear Alfven continuum is possible for these eigenmodes, especially near the plasma periphery, leading to significant dissipation, which is typically larger than direct bulk plasma dissipation rates. Two perturbation methods are develope… more

Date: September 1, 1991

Creator: Berk, H.L.; Van Dam, J.W.; Guo, Z. & Lindberg, D.M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Power excitation by the use of a rf wiggler

It is well-known that there are difficulties to obtain rf power sources of significant amount for frequencies larger than 3 GHz. Yet, rf sources in the centimeter/millimeter wavelength range would be very useful to drive, for example, high-gradient accelerating linacs for electron-positron linear colliders. We would like to propose an alternative method to produce such radiation. It makes use of a short electron bunch traveling along the axis of a waveguide which is at the same time excited by … more

Date: January 1, 1992

Creator: Ruggiero, Alessandro G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Boundary element formulation for planar time-dependent inelastic deformation of plates with cutouts

A boundary element formulation for planar, time-dependent, inelastic deformation problems for bodies with cutouts is presented in this paper. A stress function description for these nonlinear problems leads to a nonhomogeneous biharmonic equation for the stress function rate. An integral representation of the solution uses modified kernels which guarantee that the cutout boundary is traction free for all time. This incorporation of the effect of the cutout on the stress field into the kernels l… more

Date: February 1, 1980

Creator: Mukherjee, S. & Morjaria, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Final Report of Modeling of CWM Droplet Combustion

The objective of the present study was to develop a one-dimensional, unsteady state model for coal-water mixture droplet combustion, and to compare the characteristic times for the various processes, such as water vaporization, devolatilization and char oxidation with available experimental data. A water film surrounding a spherical coal particle is considered to undergo vaporization by heat transfer from the hot air. After the water vaporization is complete, devolatilization begins. This proce… more

Date: October 1, 1983

Creator: Pandalai, Krish; Aggarwal, Suresh & Sirignano, William

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

The interpretation of reflectometry measurements of plasma fluctuations

Wave reflections from density fluctuations with magnitudes and frequencies typical of drift waves have been investigated. Both drift waves and the reflected phase and amplitude depend on the density gradient scale length, and this common feature implies that both the angular deviation of a normally propagating wave and the phase change on reflection are of order unity. Thus the surface will always appear rough'' and amplitude variations will always be large. For smaller amplitude waves numerica… more

Date: October 1, 1991

Creator: Bretz, N.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Electron-beam envelopes and matching for a combined wiggler and alternating-gradient quadrupole channel

This work studies the electron-beam envelopes and matching for a combined wiggler and alternating-gradient quadrupole field for a free-electron laser (FEL) that will be operated in the VUV or XUV wavelength region. The quadrupole field is assumed to vary continuously along the symmetry axis. The linearized equations of electron motion are solved analytically by using the two-scale perturbation method for a plane polarized wiggler. The electron-beam envelopes and the envelope equations, as well … more

Date: January 1, 1985

Creator: Wang, T. F. & Cooper, R. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

D/sup -/ production by multiple charge-transfer collisions of low-energy D ions and atoms in cesium vapor

The production of D/sup -/ by multiple charge-transfer collisions of a D/sup +/ beam in a cesium-vapor target is considered for D/sup +/ energies above 300 eV. The cross sections relevant to D/sup -/ formation are obtained by a least-squares fit of three-charge-state differential equations to experimental yield curves. Implications for production of intense negative-ion beams are discussed, and speculations are made about extrapolation to lower engeries.

Date: January 22, 1978

Creator: Hooper, E. B. Jr.; Willmann, P. A. & Schlachter, A. S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Fundamental theory of elastic wave scattering by defects in elastic materials: integral equation methods for application to ultrasonic flaw detection

The use of ultrasonic methods in nondestructive testing depends on the interpretation of the scattering of sound waves by flaws. The theory of elastic waves and their scattering in non-uniform media is developed in detail from first principles, and in generality. Both integral equation and differential methods are discussed, with emphasis on the former. General methods for defining scattering cross sections are presented, and conservation theorems are noted. The Born Approximation to the integr… more

Date: May 1, 1976

Creator: Gubernatis, J.E.; Domany, E.; Krumhansl, J.A. & Huberman, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Estimate of the longitudinal self electric field of an ion beam

The self electric field on the axis of an ion beam of radius a in a conducting cylinder of radius b is given. The formula assumes that the radius of the conducting cylinder is much smaller than the length of the ion beam (b much less than L) and that E/sub z/ is calculated away from the edge of the beam (vertical bar z vertical bar less than vertical bar L/2 vertical bar). For the HIDE parameters, i.e., loosely speaking a 50 TW, 100 JK, multi-GeV heavy ion beam, the assumption b much less than … more

Date: January 1, 1977

Creator: Irani, A.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Theory of chemical kinetics. Progress report, May 1, 1977--January 15, 1978. [Massachusetts Inst. of Tech. , Cambridge]

Recent work on Franck--Condon factors in studies of the dynamics of chemical reactions is related; emphasis was on simple chemical rearrangement reactions. Other work concerned collision-free unimolecular decomposition of large molecules at a given total energy, equations of motion for simple quantum systems that are strongly driven by an external field and are modulated stochastically by a coupling to a bath, and the efficiency of rate processes in irreversible chemical reactions. This report … more

Date: unknown

Creator: Ross, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Magnetic fusion with high energy self-colliding ion beams

Field-reversed configurations of energetic large orbit ions with neutralizing electrons have been proposed as the basis of a fusion reactor. Vlasov equilibria consisting of a ring or an annulus have been investigated. A stability analysis has been carried out for a long thin layer of energetic ions in a low density background plasma. There is a growing body of experimental evidence from tokamaks that energetic ions slow down and diffuse in accordance with classical theory in the presence of lar… more

Date: June 1, 1992

Creator: Rostoker, N.; Wessel, F. (California Univ., Irvine, CA (United States)); Maglich, B. (Advanced Physics Corp., Irvine, CA (United States)) & Fisher, A. (Naval Research Lab., Washington, DC (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Stochastic modelling of physiologic processes with radiotracers and positron emission tomography

The compartment model, so often used in nuclear medicine and in pharmacokinetics, is formed by a set of linear differential equations of order one with constant coefficients; its validity depends upon the hypothesis that the system described contains a finite number of components, and that each component is homogeneous. These hypotheses exclude the presence of diffusion and of age-dependent processes, or in general of transport of a non-Markovian nature. The fact that frequently the experimenta… more

Date: January 1, 1982

Creator: Rescigno, A.; Lambrecht, R. M. & Duncan, C. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Performance estimates for personnel access control systems

Current performance estimates for personnel access control systems use estimates of Type I and Type II verification errors. A system performance equation which addresses normal operation, the insider, and outside adversary attack is developed. Examination of this equation reveals the inadequacy of classical Type I and II error evaluations which require detailed knowledge of the adversary threat scenario for each specific installation. Consequently, new performance measures which are consistent … more

Date: October 1, 1980

Creator: Bradley, R. G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Coarse-node computations with an adaptive node structure

The analysis with COMMIX of liquid metal reactor (LMR) intermediate heat exchanger (IHX) transients that are characterized by low flows, and especially imbalanced low flows, shows that if a coarse-node structure is used the predicted temperatures are significantly different than those given by a fine-node structure. If a fine-node structure is used, for problems that involve a large part of the plant, the computation time becomes excessive. This paper presents an improved version of an adaptive… more

Date: January 1, 1988

Creator: Tzanos, C.P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Is the two-term expansion valid for highly anisotropic systems. The Townsend ionization coefficient in strong runaway as a test case

The Townsend ionization coefficient in the strong runaway regime is calculated within the framework of the two-term expansion. Results are compared to the 1-D model. General features of the two models are qualitatively similar, but quantitative differences by factors of approx. 2 are observed.

Date: July 15, 1982

Creator: Yu, S. S. & Melendez, R. E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Equation of state of solid neon from x-ray diffraction measurements to 110 GPa

This paper briefly discusses the pressure-volume properties of condensed neon. X-ray diffraction techniques are used to determine solid neon equation of state and crystal structure. 16 refs., 2 figs. (LSP)

Date: January 1, 1987

Creator: Hemley, R. J.; Jephcoat, A. P.; Zha, C. S.; Mao, H. K.; Finger, L. W. & Cox, D. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Methods and techniques of NDA (nondestructive assay)

Nondestructive assay (NDA) refers to techniques and instruments developed to measure nuclear materials in the many forms in which they occur throughout the fuel cycle. These techniques were first developed to support nuclear safeguards inspections and nuclear material accountability; they are also used extensively for process and quality control. Most accountability measurements are based on analytical chemistry and require that a sample be drawn and analyzed destructively. Destructive analysis… more

Date: January 1, 1988

Creator: Reilly, T. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Probing nuclear matter with dileptons

Dileptons are shown to be of interest in helping probe extreme conditions of temperature and density in nuclear matter. The current state of experimental knowledge about dileptons is briefly described, and their use in upcoming experiments with light ions at CERN SPS are reviewed, including possible signatures of quark matter formation. Use of dileptons in an upcoming experiment with a new spectrometer at Berkeley is also discussed. This experiment will probe the nuclear matter equation of stat… more

Date: June 1, 1986

Creator: Schroeder, L. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Multi-grid and ICCG for problems with interfaces

Computation times for the multi-grid (MG) algorithm, the incomplete Cholesky conjugate gradient (ICCG) algorithm (J. Comp. Phys. 26, 43-65 (1978); Math. Comp. 31, 148-162 (1977)), and the modified ICCG (MICCG) algorithm (BIT 18, 142-156 (1978)) to solve elliptic partial differential equations are compared. The MICCG and ICCG algorithms are more robust than the MG for general positive definite systems. A major advantage of the MG algorithm is that the structure of the problem can be exploited to… more

Date: January 1, 1980

Creator: Dendy, J.E. & Hyman, J.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fermi molecular dynamics

classical many body models supplemented by repulsive momentum-dependent potentials to simulate the Pauli and Heisenberg principles have been use with some success for nuclear and atomic bound state and collision problems. They are capable of describing mean ground state properties, hydrodynamics, shocks (if warranted by the physics), viscosity, correlations, clustering, fragmentation, etc. We have become interested in the Feldmeier Gaussian packet formulation since it is based on a variational … more

Date: January 1, 1991

Creator: Wilets, L. & Beck, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Some general properties of stimulated Raman propagation with pump depletion, transiency and dispersion

This note considers some of the properties of the Stokes pulse that grows from a specified seed pulse in the presence of a strong pump pulse as it propagates through a dispersive atomic vapor. We first present an generic dimensionless form for the coupled equations that govern the propagation of pump and Stokes fields or collinear plane-wave pulses. By treating the two fields we permit pump depletion. We include transient atomic response (as embodied in the Raman coherence), but neglect changes… more

Date: August 2, 1991

Creator: Shore, B. W.; Lowder, S. & Johnson, M. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Quantum electrodynamics with complex fermion mass

The quantum electrodynamics (QED) with a complex fermion mass -- that is, a fermion mass with a chiral phase -- is restudied, together with its chirally rotated version. We show how fake electric dipole moment can be obtained and how to avoid it. 10 refs.

Date: August 1, 1991

Creator: McKellar, B. J. H. & Wu, D. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Three-dimensional free electron laser dispersion relation including betatron oscillations

We have developed a 3-D FEL theory based upon the Maxwell-Vlasov equations including the effects of the energy spread and emittance of the electron beam, and of betatron oscillations. The radiation field is expressed in terms of the Green's function of the inhomogeneous wave equation and the distribution function of the electron beam. The distribution function is expanded in terms of a set of orthogonal functions determined by the unperturbed particle distribution. The coupled Maxwell-Vlasov eq… more

Date: August 1, 1991

Creator: Chin, Y. H.; Kim, K. J. & Xie, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department