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open access

Mathematical modeling of the nickel/metal hydride battery system

Description: A group of compounds referred to as metal hydrides, when used as electrode materials, is a less toxic alternative to the cadmium hydroxide electrode found in nickel/cadmium secondary battery systems. For this and other reasons, the nickel/metal hydride battery system is becoming a popular rechargeable battery for electric vehicle and consumer electronics applications. A model of this battery system is presented. Specifically the metal hydride material, LaNi{sub 5}H{sub 6}, is chosen for investi… more
Date: September 1, 1995
Creator: Paxton, B.K.
Partner: UNT Libraries Government Documents Department
open access

Surface structures from low energy electron diffraction: Atoms, small molecules and an ordered ice film on metal surfaces

Description: We investigated the surface bonding of various adsorbates (0, S, C{sub 2}H{sub 3} and NO) along with the resulting relaxation of the Pt(111) surface using low energy electron diffiraction (LEED). LEED experiments have been performed on these ordered overlayers along with theoretical structural analysis using automated tensor LEED (ATLEED). The resulting surface structures of these ordered overlayers exhibit similar adsorbate-induced relaxations. In all cases the adsorbate occupies the fcc hollo… more
Date: September 1, 1995
Creator: Materer, N.F.
Partner: UNT Libraries Government Documents Department
open access

Terahertz time domain interferometry of a SIS tunnel junction and a quantum point contact

Description: The author has applied the Terahertz Time Domain Interferometric (THz-TDI) technique to probe the ultrafast dynamic response of a Superconducting-Insulating-Superconducting (SIS) tunnel junction and a Quantum Point Contact (QPC). The THz-TDI technique involves monitoring changes in the dc current induced by interfering two picosecond electrical pulses on the junction as a function of time delay between them. Measurements of the response of the Nb/AlO{sub x}/Nb SIS tunnel junction from 75--200 G… more
Date: September 1, 1995
Creator: Karadi, C.
Partner: UNT Libraries Government Documents Department
open access

On the numerical treatment of problems in atmospheric chemistry

Description: Atmospheric chemical-radiative-transport (CRT) models are vital in performing research on atmospheric chemical change. Even with the enormous computing capability delivered by massively parallel systems, extended three dimensional CRT simulations are still not computationally feasible. The major obstacle in a CRT model is the nonlinear ODE system describing the chemical kinetics in the model. These ODE systems are usually very stiff and account for anywhere from 75% to 90% of the CPU time requi… more
Date: September 1, 1995
Creator: Aro, C.J.
Partner: UNT Libraries Government Documents Department
open access

Spectral analysis of the turbulent mixing of two fluids

Description: We describe a spectral approach to the investigation of fluid instability, generalized turbulence, and the interpenetration of fluids across an interface. The Technique also applies to a single fluid with large variations in density. Departures of fluctuating velocity components from the local mean are far subsonic, but the mean Mach number can be large. Validity of the description is demonstrated by comparisons with experiments on turbulent mixing due to the late stages of Rayleigh-Taylor inst… more
Date: September 1995
Creator: Steinkamp, M. J.
Partner: UNT Libraries Government Documents Department
open access

Nuclear magnetic resonance studies of macroscopic morphology and dynamics

Description: Nuclear magnetic resonance techniques are traditionally used to study molecular level structure and dynamics with a noted exception in medically applied NMR imaging (MRI). In this work, new experimental methods and theory are presented relevant to the study of macroscopic morphology and dynamics using NMR field gradient techniques and solid state two-dimensional exchange NMR. The goal in this work is not to take some particular system and study it in great detail, rather it is to show the utili… more
Date: September 1, 1995
Creator: Barrall, G. A.
Partner: UNT Libraries Government Documents Department
open access

The multi-niche crowding genetic algorithm: Analysis and applications

Description: The ability of organisms to evolve and adapt to the environment has provided mother nature with a rich and diverse set of species. Only organisms well adapted to their environment can survive from one generation to the next, transferring on the traits, that made them successful, to their offspring. Competition for resources and the ever changing environment drives some species to extinction and at the same time others evolve to maintain the delicate balance in nature. In this disertation we pre… more
Date: September 1, 1995
Creator: Cedeno, W.
Partner: UNT Libraries Government Documents Department
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