Digital Commons Network^™

Digital Analysis Of Pulse Code Modulated Signals In Telecommunications Channels, Edmund Littlefield Chase

Doctoral Dissertations

In this dissertation the techniques required to test pulse code modulated telecommunications channels are developed using the fast Fourier transform. The techniques are then applied through the design and assembly of the corresponding hardware. Windowing of data to improve spectral estimation is discussed as well as the conditions where special test signals may be synthesized to preclude the need for windowing. Conjugate-periodic functions encountered in prime radix transforms are defined and their fast transform techniques are developed.

Conductance In Restricted-Dimensionality Accumulation Layers, A. B. Fowler, A. Hartstein, Richard A. Webb

Faculty Publications

Conductance has been studied in metal-oxide-silicon field-effect transistor accumulation-layer samples in which it is possible to constrict the channel to small dimensions both perpendicular to the surface and perpendicular to the channel. A temperature-dependent conductance σ=σ₀exp[-(T₀/T)ⁿ] is observed, where n=1/2 for small channel widths and n=1/3 for larger channel widths. It is believed that this behavior arises from a transition from one-dimensional to two-dimensional variable-range hopping in the sample.

Macroscopic Quantum Tunneling In 1-Μm Nb Josephson Junctions, Richard F. Voss, Richard A. Webb

Faculty Publications

The probability distributions for switching out of the superconducting state of low-cur-rent-density 1-μm Nb Josephson junctions with capacitance ≈ 0.1 pF have been measured as a function of temperature T down to 3 mK. Below 100 mK the distribution widths become independent of T. The results are in excellent agreement with predictions for the quantum tunneling of the (macroscopic) junction phase that include the reduction of tunneling rates due to dissipation.

Faraday Rotation Investigations Of Surface Space-Charge Layers In Metal - Oxide - Semiconductor (Mos) Systems., Gary L. Wallace

LSU Historical Dissertations and Theses

The free carrier Faraday effect is considered in both the Drude model and the Appel-Overhauser model for inversion layer electrons at the SiO(,2)-Si interface. An exact algebraic relation between the photon, cyclotron, collision and plasma frequencies is obtained which must be satisfied in order to achieve null rotation and null ellipticity for a single pass of the electromagnetic wave in the Drude model. Plots of the rotation versus angular photon frequency in the Appel-Overhauser model for various values of the electron-electron (e-e) scattering time (tau)(,e) are presented. These plots show that Faraday rotation measurements are a possible way of determining …

Auroral Thermospheric Temperatures, Marjorie Althea Cole

Theses (Unassigned)

No abstract provided.

The Solution To Single Kink Solitary Wave Transport For Systems Described By A Generalized Frenkel-Kontorova Equation., Louis William Adams Jr

LSU Historical Dissertations and Theses

A numerical procedure to solve the differential equation for solitary waves via iteration for a generalized Frenkel-Kontorova model is presented. The generalization consists of adding a constant force proportional to particle velocity. The equation of motion is cast into integral form using a Green's function. The introductory chapter briefly reviews recent progress in nonlinear dynamics using the sine-Gordon equation as an example. Emphasis is placed on the concept of "non-linear modes" and its relevance in theoretical descriptions of transport processes. After a second chapter defining the generalized Frenkel-Kontorova equation, its dimensionless reparametrization and an outline of the iteration scheme, the …

Interpretation Of Narrow Beam Sonar Echos Using A Variable Impedance Subbottom Model, Robert Leicester Bolus

Doctoral Dissertations

An underwater antenna consisting of an acoustic paraboloid reflector with a 12 kHz transducer mounted at its focus was designed and built for remote sensing of the subbottom {1}. Surveys taken with the 3 degree half-power beamwidth projector operating in a 1/2 ms pulsed mode indicated horizontal and vertical resolutions of less than 1 m with penetration into the sediments of up to 20 m at 20 m of depth. The image detail was substantially increased over that taken with a conventional 30 degree profiler.

The data was interpreted using a physical model of the subbottom consisting of plane parallel …

Spin-Glass-Like Behavior In Very Dilute Pdfe At Very Low Temperatures, Richard A. Webb, G. W. Crabtree, J. J. Vuillemin

Faculty Publications

Measurements of the electrical resistivity of palladium, residual resistivity ratio ∼22 500, containing 1.7 ppm of Fe have been made from 5.5 K to 1.8 mK. 15 Hz ac susceptibility measurements from 1 K to 1.8 mK together with the resistivity data suggest that a transition into a spin-glass state occurs near 7 mK.

A Theory For The Asymmetry In The Auroral Ionization Density Profile For The Generation Of Auroral Infrasonic Waves, Paul Albert Goodwin

Theses (Unassigned)

No abstract provided.

Tip-Angle-Dependent Magnetic Relaxation In Superfluid 3he, Richard A. Webb

Faculty Publications

Using a pulsed superconducting-quantum-interference-device (SQUID) NMR technique, relaxation of the longitudinal magnetization in superfluid ³He has been measured in magnetic fields of 31, 102, 180, and 306 Oe in the pressure range 16-26 bar. It is observed that in both superfluid phases there is a temperature-dependent, well-defined spin-tipping angle, θc, for which the relaxation of the magnetization changes from an exponential to a nonexponential behavior.

The Effects Of Plane Parallel Boundaries On Cylinder Drag At Low Reynolds Number., John Franklin Stalnaker

LSU Historical Dissertations and Theses

No abstract provided.

The Effect Of A Horizontal Plane Boundary On A Falling Horizontal Cylinder At Low Reynolds Number., Yang-Jen Chen

LSU Historical Dissertations and Theses

No abstract provided.

Ferromagneticlike Resonance Behavior In Superfluid 3he-B, Richard A. Webb

Faculty Publications

Nonlinear cw NMR behavior, similar to that observed on ferromagnets at high rf powers, has been observed in superfluid ³He-B using a superconducting quantum interference device (SQUID) magnetometer in fields of 31, 102, 180, and 308 Oe and at a pressure of 21 bar. It is observed that beyond some threshold value of the transverse H₁ field the z component of magnetization anomalously decreases and is followed by a rapid increase back to the normal resonance curve as the frequency of the H₁ field is swept through resonance.

Measurement Of The Difference Between The Dynamic Nmr And Static Susceptibilites Of Superfluid 3he-B Using An Rf-Biased Superconducting Quantum-Interference Device, Richard A. Webb

Faculty Publications

The temperature-dependent susceptiblity of superfluid ³He-B has been measured both statically and via a pulse technique in a field of 309 G using an rf-biased superconducting quantum-interference device (SQUID). In the pressure range 26.5 to 18 bar, the dynamic NMR susceptiblity agrees qualitatively with the theoretical weak-coupling predictions for the Balian-Werthamer state. However, the static susceptiblity, measured using the same rf-biased SQUID and detection system, is significantly smaller thatn the dynamic susceptibility.

Fifty Years Of Uncertainty, Richard C. Heyser

Unpublished Writings

Richard C. Heyser frequently explores ways to find a "mathematical basis for perception" in his writings. In this article, Heyser discusses implementing geometry elements to quantum physics.

Cylinder Drag At Low Reynolds Number., Burke Huner

LSU Historical Dissertations and Theses

No abstract provided.

Charge Exchange Optical Pumping, Sallie Slawson Townsend

Doctoral Dissertations

No abstract provided.

Part I: Exact Physical Properties Of Electron Gases In Uniform Magnetic Fields At T = 0 Degrees K. Part Ii: The Path Of A Sound Wave In General Relativity., Young Bae Suh

LSU Historical Dissertations and Theses

No abstract provided.

A Computer Model Of The Polar F-Region Ionosphere, Brenton John Watkins

Theses (Unassigned)

No abstract provided.

The Measurement Of (Nuclear G-Factor Of Unipositive Sodium-23 Ion)/(Electronic G-Factor Of Sodium-23) By Optical Pumping, Chung-Jen Tsai

Doctoral Dissertations

No abstract provided.

Group Of Point Transformations Of Time Dependent Harmonic Oscillators, Jose Ricardo Bernal

University of the Pacific Theses and Dissertations

In general, a physical system has invariant quantities which are very often related to its symmetry and to the invariance of the equation that describe it. A detailed study of the invariance property of the differential equation will be helpful in understanding this relation.

The work is concerned with a preliminary investigation of the Lie-group which leaves invariant the Newtonian and Lagrangian equation of motion for a one-dimensional harmonic oscillator. A brief review of Ehrenfest's adiabatic principle and the later treatments on exact and adiabatic invariants will be presented.

Relaxation Of The Wall-Pinned Magnetization Ringing Mode In Superfluid 3he-B, Richard A. Webb, R. E. Sager, J. C. Wheatley

Faculty Publications

Observations of the wall-pinned mode in ³He-B allow new magnetic relaxation phenomena to be studied. Excepting the quantitative value of the zero-time ringing frequency, comparison of experiment with theory is satisfactory, including a linear dependence of the square of the ringing period on time and a square-root singularity near T_c in the relaxation parameter.

Nonlinear Parallel Ringing Of Magnetization In Superfluid 3he, Richard A. Webb, R. E. Sager, J. C. Wheatley

Faculty Publications

Experiments based on an analogy to the ac Josephson effect have shown in both ³He-A and ³He-B that a pairing theory of the superfluidity of ³He is essentially correct. Additional observations of parallel ringing are not in agreement with the simple "pendulum models" used to describe nonlinear dynamic magnetic effects.

Relationship Between The Linear Ringing Frequencies In 3he-A And 3he-B Near The Polycritical Point, Richard A. Webb, R. E. Sager, J. C. Wheatley

Faculty Publications

New measurements of parallel ringing in a quasi-ideal geometry for ³He-B near the temperature and pressure of the polycritical point suggest f_B²/f_A²∼5/2, where f_B and f_A are the linear parallel-ringing frequencies at a given temperature near T_c. This result approaches the prediction of theory using the Anderson-Brinkman-Morel and Balian-Werthamer states to describe ³He-A and ³He-B, respectively, and hence the results of Osheroff at melting pressure, but disagrees with earlier observations at pressures near the polycritical point.

An Introduction To Model Rocketry For The Classroom Teacher, David Reese

All Graduate Projects

The writer of this project was in a fifth grade teaching position beginning Fall, 1974, in Lacey, Washington. The writer taught thirty students in a self-contained classroom situation. The purpose of this individualized study was to develop a general framework and assemble some specific materials which would aid others in starting and developing a program in model rocketry in an orderly and logical manner.

A Mathematical Model Of Interplanetary Radio Scintillation, In The Weak-Scattering Regime, Donald Grant Mitchell

Doctoral Dissertations

No abstract provided.

Aristotle's Doctrine Of Elements, L. Shannon Dubose

The Society for Ancient Greek Philosophy Newsletter

In his studies of nature, Aristotle pursues a series of connected inquiries. He elicits a series of sets of elements; none of the steps is abandoned in favor of later ones. Each set of elements discovers primary constituents of an appropriate sort. Substratum, form, and privation are the most fundamental for the study of generable objects.

Experiments On Dynamic Parallel Magnetism In Superfluid 3he, Richard A. Webb, R. L. Kleinberg, J. C. Wheatley

Faculty Publications

Observations are reported of the ringing of parallel magnetization in superfluid ³He when an incremental magnetic field parallel to a steady field is suddenly turned off.

Wittgenstein's Tractatus: Some Metaphilosophical Considerations, Howard P. Kainz

Philosophy Faculty Research and Publications

No abstract provided.

Band Mixing In Tungsten-184, Osmium-186, And Osmium-188 And The Nuclear Structure Of Tungsten-184., Michael David Svoren

LSU Historical Dissertations and Theses

No abstract provided.