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Open Access. Powered by Scholars. Published by Universities.®

1991

Physics

Old Dominion University

Articles 1 - 6 of 6

Full-Text Articles in Physical Sciences and Mathematics

Study Of The Heavy Fermion/Spin-Glass System, Ce1-X GdX Al3, Using 155Gd Mossbauer Spectroscopy, Nicholas G. Ruggiero Dec 1991

Study Of The Heavy Fermion/Spin-Glass System, Ce1-X GdX Al3, Using 155Gd Mossbauer Spectroscopy, Nicholas G. Ruggiero

Physics Theses & Dissertations

The magnetic properties of Ce1-xGdx.Al3 have been studied using 155Gd Mossbauer spectroscopy. It has been shown that the magnetic moments of the host GdAl3 are constrained to the basal plane. The magnetic properties of GdAl3 can best be described in the framework of RKKY theory. Prior studies of Ce1-xGdxAl3, have revealed complex magnetic behavior throughout the series. As observed with Mossbauer spectroscopy magnetic ordering occurs for x ≥ 0.5, though not at the reported spin glass temperatures. For x = 0.23 and x = 0.18, the …

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On Shock Capturing For Liquid And Gas Media, Tze Jang Chen Jul 1991

On Shock Capturing For Liquid And Gas Media, Tze Jang Chen

Mathematics & Statistics Theses & Dissertations

The numerical investigation of shock phenomena in gas or liquid media where a specifying relation for internal energy is absent poses special problems. Classically, for gas dynamics the usual procedure is to employ a splitting scheme to remove the source terms from the Euler equations, then up-wind biased shock capturing algorithms are built around the Riemann problem for the system which remains. However, in the case where the Euler equations are formulated in the term of total enthalpy, a technical difficulty associated with equation splitting forces a pressure time derivative to be treated as a source term. This makes it …

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Rotationally Resolved Laser Spectroscopy Of The 3s2Σ+ ← 2p2ii Transition In 6li20ne And 7li20ne Van Der Waals Molecules, Chang Jae Lee Apr 1991

Rotationally Resolved Laser Spectroscopy Of The 3s2Σ+ ← 2p2ii Transition In 6li20ne And 7li20ne Van Der Waals Molecules, Chang Jae Lee

Physics Theses & Dissertations

The rotationally resolved absorption spectrum of the 6Li20Ne and 7Li20Ne 3s2Σ+ ← 2p2 II transition has been observed. For each isotope, thirteen vibrational transitions from four vibrational levels (v"=0, 1, 2, and 3) of the lower 2p2 II to six (v’=0, 1, 2, 3, 4, and 5) of the upper 3s*Σ+ electronic state have been rotationally analyzed. Adiabatic potentials and dissociation energies for both states have been obtained through an inverse perturbation analysis. For the 2p2II state, a well depth of 212(5) cm-1 and an …

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Electric Field Induced Emission As A Diagnostic Tool For Measurement Of Local Electric Field Strengths, A. N. Dharamsi, K. H. Schoenbach Jan 1991

Electric Field Induced Emission As A Diagnostic Tool For Measurement Of Local Electric Field Strengths, A. N. Dharamsi, K. H. Schoenbach

Bioelectrics Publications

The phenomenon of electric field induced (EFI) emission is examined in several diatomic and polyatomic molecules. The possibility of using this phenomenon as a diagnostic tool to measure, nonintrusively, the strength and direction of local electric fields in plasmas is discussed. An estimate of the EFI signal emitted in a typical application plasma is given. This yields a lower bound on the detector sensitivity necessary to exploit EFI emission in practical applications. It is concluded that, at present, the EFI signal could be measured by some very sensitive infrared detection schemes available. Current progress in infrared detector technology, if maintained, …

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Parametric Instability Of Supersonic Shear Layers Induced By Periodic Mach Waves, Fang Q. Hu, Christopher K. W. Tam Jan 1991

Parametric Instability Of Supersonic Shear Layers Induced By Periodic Mach Waves, Fang Q. Hu, Christopher K. W. Tam

Mathematics & Statistics Faculty Publications

It is suggested that parametric instability can be induced in a confined supersonic shear layer by the use of a periodic Mach wave system generated by a wavy wall. The existence of such an instability solution is demonstrated computationally by solving the Floquet system of equations. The solution is constructed by means of a Fourier-Chebyshev expansion. Numerical convergence is assured by using a very large number of Fourier and Chebyshev basis functions. The computed growth rate of the induced flow instability is found to vary linearly with the amplitude of the mach waves when the amplitude is not excessively large. …

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Nonlinear-Interaction Of A Detonation Vorticity Wave, D. G. Lasseigne, T. L. Jackson, M. Y. Hussaini Jan 1991

Nonlinear-Interaction Of A Detonation Vorticity Wave, D. G. Lasseigne, T. L. Jackson, M. Y. Hussaini

Mathematics & Statistics Faculty Publications

The interaction of an oblique, overdriven detonation wave with a vorticity disturbance is investigated by a direct two-dimensional numerical simulation using a multidomain, finite-difference solution of the compressible Euler equations. The results are compared to those of linear theory, which predict that the effect of exothermicity on the interaction is relatively small except possibly near a critical angle where linear theory no longer holds. It is found that the steady-state computational results whenever obtained in this study agree with the results of linear theory. However, for cases with incident angle near the critical angle, moderate disturbance amplitudes, and/or sudden transient …

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