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326,234 Matching Results

Start Over Decade 1980-1989

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Best Match Title Creator Date Created (Newest) Date Created (Oldest) Date Added (Newest) Date Added (Oldest)
3-D hybrid PIC code to model the tilt mode in FRCs (open access)

3-D hybrid PIC code to model the tilt mode in FRCs

The results from QN3D are presented. QN3D is a 3-dimensional hybrid particle-in-cell code designed to run efficiently on the Cray-2 Multiprocessor. The chief application has been to the tilt mode instability in FRCs. QN3D accepts as input, the magnetic field, the ion particle density and the ion temperature on a two-dimensional r-z grid. These quantities are interpolated to the rest of the cartesian grid under the assumption of azimuthal symmetry. The particles are initialized with random numbers chosen according to the particle distributions input from the equilibrium code. The runs done here used equilibria computed by EQV, a kinetic equilibrium code.
Date: June 1, 1987
Creator: Horowitz, E. J. & Shumaker, D. E.
Object Type: Article
System: The UNT Digital Library
3-D magnetic field calculations for wiggglers using MAGNUS-3D (open access)

3-D magnetic field calculations for wiggglers using MAGNUS-3D

The recent but steady trend toward increased magnetic and geometric complexity in the design of wigglers and undulators, of which tapered wigglers, hybrid structures, laced electromagnetic wigglers, magnetic cladding, twisters and magic structures are examples, has caused a need for reliable 3-D computer models and a better understanding of the behavior of magnetic systems in three dimensions. The capabilities of the MAGNUS-3D Group of Programs are ideally suited to solve this class of problems and provide insight into 3-D effects. MAGNUS-3D can solve any problem of Magnetostatics involving permanent magnets, linear or nonlinear ferromagnetic materials and electric conductors of any shape in space. The magnetic properties of permanent magnets are described by the complete nonlinear demagnetization curve as provided by the manufacturer, or, at the user's choice, by a simpler approximation involving the coercive force, the residual induction and the direction of magnetization. The ferromagnetic materials are described by a magnetization table and an accurate interpolation relation. An internal library with properties of common industrial steels is available. The conductors are independent of the mesh and are described in terms of conductor elements from an internal library.
Date: January 1, 1988
Creator: Pissanetzky, S. & Tompkins, P.
Object Type: Article
System: The UNT Digital Library
A 3-D measurement system using object-oriented FORTH (open access)

A 3-D measurement system using object-oriented FORTH

Discussed is a system for storing 3-D measurements of points that relates the coordinate system of the measurement device to the global coordinate system. The program described here used object-oriented FORTH to store the measured points as sons of the measuring device location. Conversion of local coordinates to absolute coordinates is performed by passing messages to the point objects. Modifications to the object-oriented FORTH system are also described. 1 ref.
Date: January 1, 1989
Creator: Butterfield, K.B.
Object Type: Article
System: The UNT Digital Library
3-D Nonlinear Calculations of Resistive Tearing Modes (open access)

3-D Nonlinear Calculations of Resistive Tearing Modes

Recent numerical calculations of the evolution of resistive tearing modes have been central to the understanding of magnetohydrodynamic activity and disruptions in tokamaks. The nonlinear, 3-D, initial-value computer code RSF has provided many of these results. This code assumes cylindrical geometry with a Fourier series representation in the two periodic coordinates and a finite-difference representation in the radial direction. This choice makes RSF considerably more accurate and efficient than previous codes.
Date: March 1, 1981
Creator: Hicks, H. R.; Holmes, J. A.; Lee, D. K.; Carreras, B. & Waddell, B. V.
Object Type: Report
System: The UNT Digital Library
3-D numerical analysis of a high-gain free-electron laser (open access)

3-D numerical analysis of a high-gain free-electron laser

We present a novel approach to the 3-dimensional high-gain free- electron laser amplifier problem. The method allows us to write the laser field as an integral equation which can be efficiently and accurately evaluated on a small computer. The model is general enough to allow the inclusion of various initial electron beam distributions to study the gain reduction mechanism and its dependence on the physical parameters. 16 refs., 8 figs., 1 tab.
Date: October 19, 1988
Creator: Gallardo, J.C.
Object Type: Report
System: The UNT Digital Library
3-D resistive MHD calculations for tokamak plasmas: beyond the simple reduced set of equations (open access)

3-D resistive MHD calculations for tokamak plasmas: beyond the simple reduced set of equations

Numerical studies of the resistive stability of tokamak plasmas in cylindrical geometry have been performed using: (1) the full set of resistive Magnetohydrodynamic (MHD) equations and (2) an extended version of the reduced set of resistive MHD equations including diamagnetic and electron temperature effects. In particular, the nonlinear interaction of tearing modes of many helicities has been investigated. The numerical results confirm many of the features uncovered previously using the simple reduced equations.
Date: January 1, 1983
Creator: Carreras, B. A.; Garcia, L.; Hender, T. C.; Hicks, H. R.; Holmes, J. A.; Lynch, V. E. et al.
Object Type: Article
System: The UNT Digital Library
3-D solution of flow in an infinite square array of circular tubes by using boundary-fitted coordinate system (open access)

3-D solution of flow in an infinite square array of circular tubes by using boundary-fitted coordinate system

Heat transfer and fluid flow over circular tubes have wide applications in the design of heat exchangers and nuclear reactors. However, it is often difficult to accurately calculate the detailed velocity and temperature distributions of the flow because of the complex geometry involved in the analysis, and a lack of an appropriate coordinate system for the analysis. Boundary conditions on the surfaces of the tubes are often interpolated. This interpolation process introduces inaccuracy. To overcome this difficulty, the present study used the technique of the boundary-fitted coordinate system. In this technique, all the physical boundaries are transformed into constant coordinate lines in the transformed coordinates. Therefore, the boundary conditions can be specified on the grid points without interpolation.
Date: January 1, 1982
Creator: Chen, B. C. J.; Chien, T. H.; Sha, W. T. & Kim, J. H.
Object Type: Article
System: The UNT Digital Library
3-D structures and intrinsic defects in trans-polyacetylene (open access)

3-D structures and intrinsic defects in trans-polyacetylene

We report first-principles local-density functional pseudopotential calculations of static and dynamic electronic structure properties of crystalline 3-D trans--(CH)/sub x/. We find a broken symmetry ground state of P2/sub 1//a symmetry with in-phase dimerizations. Using a Green's function technique, we show that the 3-D character of the electronic band edge states strongly suppresses self-trapping, destabilizing polarons and possibly bipolarons as well in perfectly ordered 3-D trans--(CH)/sub x/. 26 refs.
Date: January 1, 1989
Creator: Vogl, Peter & Campbell, David K.
Object Type: Article
System: The UNT Digital Library
3-D transient eddy current calculations for the FELIX cylinder experiments (open access)

3-D transient eddy current calculations for the FELIX cylinder experiments

The three-dimensional eddy current transient field problem is formulated first using the U-V method. This method breaks the vector Helmholtz equation into two scalar Helmholtz equations. Null field integral equations and the appropriate boundary conditions are used to set up an identification matrix which is independent of null field point locations. Embedded in the identification matrix are the unknown eigenvalues of the problem representing its impulse response in time. These eigenvalues are found by equating the determinant of the identification matrix to zero. When this initial forcing function is Fourier decomposed into its spatial harmonics, each Fourier component can be associated with a unique eigenvalue by this technique. The true transient solution comes through a convolution of the impulse response so obtained with the particular external field decay governing the problem at hand. The technique is applied to the FELIX cylinder experiments; computed results are compared to data. A pseudoanalytic confirmation of the eigenvalues so obtained is formulated to validate the procedure.
Date: December 1, 1986
Creator: Davey, K. R. & Turner, L. R.
Object Type: Report
System: The UNT Digital Library
3-D treatment of convective flow in the earth's mantle (open access)

3-D treatment of convective flow in the earth's mantle

A three-dimensional finite-element method is used to investigate thermal convection in the earth's mantle. The equations of motion are solved implicitly by means of a fast multigrid technique. The computational mesh for the spherical problem is derived from the regular icosahedron. The calculation described use a mesh with 43,554 nodes and 81,920 elements and were run on a Cray X. The earth's mantle is modeled as a thick spherical shell with isothermal, free-slip boundaries. The infinite Prandtl number problem is formulated in terms of pressure, density, absolute temperature, and velocity and assumes an isotropic Newtonian rheology. Solutions are obtained for Rayleigh numbers up to approximately 10/sup 6/ for a variety of modes of heating. Cases initialized with a temperature distribution with warmer temperatures beneath speading ridges and cooler temperatures beneath present subduction zones yield whole-mantle convection solutions with surface velocities that correlate well with currently observed plate velocities. 8 references, 6 figures.
Date: May 1, 1984
Creator: Baumgardner, J.R.
Object Type: Article
System: The UNT Digital Library
3 divertissements numériques (1 franchir le rubicon, 2 fission, 3 mange ta télévision)

3 divertissements numériques (1 franchir le rubicon, 2 fission, 3 mange ta télévision)

Access: Use of this item is restricted to the UNT Community
Recording of Jean-François Cavro's 3 divertissements numériques (1 franchir le rubicon, 2 fission, 3 mange ta télévision). This work is created with electronics and uses traditional electronic technique. There is present noise elements within this work's texture, which establish a good balance within the orchestration of sound. By working with electronic sound effects and pre-recorded sounds of many qualities or frequencies, balance is found.
Date: 1989/1993
Creator: Cavro, Jean-François
Object Type: Sound
System: The UNT Digital Library
T-3 electron-beam-excited laser system (open access)

T-3 electron-beam-excited laser system

A laser system specifically designed to study the kinetics of electron-beam driven systems is described. Details of the system are given along with measurements of the electron-beam uniformity and deposition in the laser medium. Some HF laser results obtained with this system are also given.
Date: February 1, 1981
Creator: Klein, R. A.
Object Type: Report
System: The UNT Digital Library
[3 horses next to fence]

[3 horses next to fence]

Photograph of two horses standing next to a fence looking at the camera while a third horse is grazing the grass near the fence post.
Date: June 1986
Creator: Shugart, Don
Object Type: Photograph
System: The Portal to Texas History
[3 Letters from Donald J. Maison] (open access)

[3 Letters from Donald J. Maison]

Copies of three letters from Donald J. Maison: a carbon copy of a letter from Maison to Chief Prosecutor (dated April 16, 1980), copy of a letter from Maison to Steve Tokoley (dated April 7, 1980), and carbon copy of letter from Maison to Bill Arnold (dated March 26, 1980).
Date: April 16, 1980
Creator: Maison, Donald J.
Object Type: Letter
System: The UNT Digital Library
3-megajoule heavy-ion fusion driver (open access)

3-megajoule heavy-ion fusion driver

The initiation of inertial confinement fusion reactions with a heavy ion particle beam has been under intensive study since 1976, and the progress of this study is principally documented in the proceedings of annual workshops held by US National Laboratories. At this time a 3MJ, 150 TW, ion beam is a good choice to initiate microexplosions with energy gain of 100. The Lawrence Berkeley Laboratory has made systems studies based on a Linear Induction Accelerator to meet the beam requirements. The accelerator system, expected performance and cost, and technical problems to be addressed in the near future are discussed.
Date: June 1, 1981
Creator: Faltens, A.; Hoyer, E. & Keefe, D.
Object Type: Article
System: The UNT Digital Library
3 mm Anisotropy Measurement: On the Quadrupole Component in theCosmic Background Radiation (open access)

3 mm Anisotropy Measurement: On the Quadrupole Component in theCosmic Background Radiation

We have mapped the large-scale anisotropy in the cosmic background radiation at 3 mm wavelength using a liquid-helium-cooled balloon-borne radiometer sensitive enough to detect the dipole in one gondola rotation (1 minute). Statistical errors on the dipole and quadrupole components are below 0.1 mK with less than 0.1 m K galactic contribution. We find a dipole consistent with previous measurements but disagree with recent quadrupole reports. The measurement is also useful in searching for spectral distortions.
Date: November 1, 1982
Creator: Lubin, Philip M.; Epstein, Gerald L. & Smoot, George F.
Object Type: Article
System: The UNT Digital Library
A 3 TeV on 3 TeV proton-proton dedicated collider for Fermilab (open access)

A 3 TeV on 3 TeV proton-proton dedicated collider for Fermilab

The Fermilab Dedicated Collider proposed in May 1983 is a 2 TeV on 2 TeV p)bar p) collider. The expected luminosity is )approximately) 10/sup 31/ cm/sup (minus/2)sec/sup )minus/1) and the estimated cost is )approximately) $362M (FY-83 dollars). Since 1983 both the superconducting magnet and the particle detector technologies have advanced and the countenance of physics, hence the desired characteristics of new facilities have also altered somewhat. We want to show here that with the new magnet technology used for the SSC one can construct a 3 TeV on 3 TeV pp collider on the Fermilab site. This pp Dedicated Collider )PPDC) will have a luminosity of about 10/sub 33/cm/sup )minus/2)sec)sup)minus)1) and a cost only )approximately) 50)percent) more than that of the p)bar p) Dedicated Collider. 3 figs
Date: March 30, 1988
Creator: Teng, L.C.
Object Type: Report
System: The UNT Digital Library
A = 4 0/sup +/ - 1/sup +/ binding-energy difference (open access)

A = 4 0/sup +/ - 1/sup +/ binding-energy difference

The A = 4 ..lambda..-hypernuclei provide a rich source of information about the s-wave properties of the fundamental hyperon-nucleon (YN) force as well as offer a unique opportunity to investigate the complications that arise in calculations of the properties of bound systems in which one baryon (here the ..lambda..) with a given isospin couples strongly to another (the ..sigma..) with a different isospin. The ..lambda../sup 4/H - ..lambda../sup 4/He isodoublet ground-state energies are not consistent with a charge symmetry hypothesis for the YN interaction. The (spin-flip) excitation energies are quite sensitive to the ..lambda..N - ..sigma..N coupling of the YN interaction. In particular, when one represents the free YN interaction in terms of one-channel effective ..lambda..N potentials, the resulting 0/sup +/ (ground) state and 1/sup +/ (excited) spin-flip state are inversely ordered in terms of binding energies, the 1/sup +/ state being more bound. It is the ..sigma.. suppression that results from the reduced strength of the ..lambda..N - ..sigma..N off-diagonal coupling potential when the trinucleon core is restricted to isospin-1/2 which we study here. We find this spin-isospin suppression of the ..lambda..-..sigma.. conversion, which is due to the composite nature of the nuclear cores of the ..lambda../sup 4/H and …
Date: January 1, 1982
Creator: Gibson, B. F. & Lehman, D. R.
Object Type: Article
System: The UNT Digital Library
(4+2)-Cycloaddition Reactions of Ketenes; Pyranones (open access)

(4+2)-Cycloaddition Reactions of Ketenes; Pyranones

This study deals with the (4+2)-cycloaddition reactions of 4-π electron compounds with ketenes. Chloroketenes were generated in situ from the corresponding chlorinated acid chlorides in the presence of the ketenophiles. Chloro-, dichloro- and diphenylketenes reacted with 1-methoxy-3-trimethylsiloxy-l,3-butadiene, and 2,4-bis(trimethylsiloxy)-1,3-pentadiene to yield the corresponding dihydropyrans. The dihydropyrans yielded substituted 4-pyranones on hydrolysis.
Date: August 1983
Creator: Agho, Michael O. (Michael Osarenogowu)
Object Type: Thesis or Dissertation
System: The UNT Digital Library
4,5-methylenedithio-4',5'-propylenedithiotetrathiafulvalene (MPT) and 4,5-ethylenedithio-4',5'-propylenedithiotetrathiafulvalene (EPT) (open access)

4,5-methylenedithio-4',5'-propylenedithiotetrathiafulvalene (MPT) and 4,5-ethylenedithio-4',5'-propylenedithiotetrathiafulvalene (EPT)

The title electron donors, unsymmetrical analogs of Bis(ethylenedithio)tetrathiafulvalene, are synthesized. The utility of /sup 252/Cf Plasma Desorption Mass Spectrometry in the characterization and purity determinations is also reported.
Date: January 1, 1987
Creator: Kini, A. M.; Tytko, S. F.; Hunt, J. E. & Williams, J. M.
Object Type: Article
System: The UNT Digital Library
[4 Alarm Fire at Good and Bryan Street]

[4 Alarm Fire at Good and Bryan Street]

Photograph of a four-alarm fire at Good and Bryan Streets. Firefighters stand on the ground with hoses to put out the flames, and a large cloud of smoke is coming off the building. A firetruck is visible in the left foreground.
Date: 1980~/1989~
Creator: Dallas (Tex.). Fire Department.
Object Type: Photograph
System: The Portal to Texas History
4 Generations of Photography

4 Generations of Photography

An advertisement flyer used to promote the exhibition of the "4 Generations of Photography - Photographs made between 1890 and 1980 in Texas" by all four Byrd Williams.
Date: [1983,1985]
Creator: unknown
Object Type: Photograph
System: The UNT Digital Library
4 K to 20 K Rotational-Cooling Magnetic Refrigerator Capable of 1-Mw to >1-W Operation (open access)

4 K to 20 K Rotational-Cooling Magnetic Refrigerator Capable of 1-Mw to >1-W Operation

The low-temperature, magnetic entropy of certain single-crystal paramagnetic materials, such as DyPO/sub 4/, changes dramatically as the crystal rotates in a magnetic field. A new magnetic refrigerator design based on the anisotropic nature of such materials is presented. The key advantages of the rotational-cooling concept are (1) a single, rotary motion is required, (2) magnetic field shaping is not a problem because the entire working material is in a constant field, and (3) the refrigerator can be smaller than comparable magnetic refrigerators because the working material is entirely inside the magnet at all times. The main disadvantage of the rotational-cooling concept is that small-dimension single crystals are required.
Date: February 1, 1980
Creator: Barclay, J. A.
Object Type: Report
System: The UNT Digital Library
[4-panel piece, handmade paper on silk]

[4-panel piece, handmade paper on silk]

The artwork consists of four panels each turned on point. A grid ladder pattern turned in various directions appears in each panel. The colors are warm reddish browns and light blues. Other rectangular and triangular outlined shapes appear scattered across the panels.
Date: 1981~
Creator: Spear, Shigeko
Object Type: Artwork
System: The UNT Digital Library