70 Matching Results

Search Results

Results: 1 - 24 next
open access

Theory of ordering transformations in metals and minerals

Description: This dissertation presents an investigation of ordering in FCC based systems using the pair potential approximation in the ground state and mean field limits. The theoretical approach is used to explain the occurrence of observed equilibrium phases and characteristics of thermodynamic instabilities, in particular, spinodal ordering and decomposition. It is shown that the stability of non-integer domain sizes in long period superstructures such as Al{sub 3}Ti and Ag{sub 3}Mg may result from the … more
Date: July 1, 1991
Creator: Lindsey, Timothy Francis
Partner: UNT Libraries Government Documents Department
open access

The Effects of Computer Performance Assessment on Student Scores in a Computer Applications Course

Description: The goal of this study was to determine if performance-based tests should be routinely administered to students in computer application courses. The purpose was to determine the most appropriate mode of testing for individuals taking a computer applications course. The study is divided into areas of assessment, personality traits, and computer attitudes.
Date: July 1994
Creator: Casey, Sue Hartness
Partner: UNT Libraries
open access

The effects of computer performance assessment on student scores in a computer applications course

Description: The goal of this study was to determine if performance -based tests should be routinely administered to students in computer application courses. The purpose was to determine the most appropriate mode of testing for individuals taking a computer applications course. The study is divided into areas of assessment, personality traits, and computer attitudes.
Date: July 1994
Creator: Casey, Sue Hartness
Partner: UNT Libraries
open access

The Use of the Power Method to Find Dominant Eigenvalues of Matrices

Description: This paper is the result of a study of the power method to find dominant eigenvalues of square matrices. It introduces ideas basic to the study and shows the development of the power method for the most well-behaved matrices possible, and it explores exactly which other types of matrices yield to the power method. The paper also discusses a type of matrix typically considered impossible for the power method, along with a modification of the power method which works for this type of matrix. It g… more
Date: July 1992
Creator: Cavender, Terri A.
Partner: UNT Libraries
open access

A.B. Marx's Concept of Rondo and Sonata: A Critical Evaluation of His Explanations of Musical Form

Description: The third volume of A.B. Marx's theory treatise Die Lehre von der musikalischen Komposition is discussed. His definitions of rondo and sonata formal types are demonstrated in the first chapter in addition to the manner of their derivation through a developmental process originating in the Liedform. Musical examples chosen by Marx are examined in chapter two. These examples, taken from Mozart's and Beethoven's piano works, are evaluated in relation to Marx's definitions of the various types of f… more
Date: July 1993
Creator: Lang, Adelheid K.
Partner: UNT Libraries
open access

Strangeonium spectroscopy at 11 GeV/c and Cherenkov Ring Imaging at the SLD

Description: This thesis is divided into two sections, which describe portions of the data acquisition system and online software for the Cherenkov Ring Imaging Detector (CRID) for the SLD, and analyses of several low cross section strangeonium channels in data from the LASS spectrometer. The CRID section includes a description of the data acquisition system, determination of the preamplifier gain, and development of an online pulse finding algorithm based on deconvolution. Deconvolution uses knowledge of t… more
Date: July 1990
Creator: Bienz, Timothy Lawrence
Partner: UNT Libraries Government Documents Department
open access

Synthesis and characterization of novel ternary and quaternary reduced molybdenum oxides

Description: This thesis is divided into 8 sections: synthesis and characterization (char.) of Ba{sub 3}Mo{sub 18}O{sub 28} (an oligomer with four traps edge-sharing Mo octahedra); synthesis and char. of K{sub x}M{sub y}Mo{sub 14}O{sub 22} (M=Sn, Pb, Sr) (oligomers with three traps edge-sharing Mo octahedra); synthesis and char. of K{sub 0.19}Ba{sub 3.81}Mo{sub 22}O{sub 34} (an oligomer with five traps edge-sharing Mo octahedra); synthesis and char. of Ti{sub 0.31}Fe{sub 1.69}Mo{sub 4}O{sub 7} (a material c… more
Date: July 1, 1993
Creator: Schimek, G. L.
Partner: UNT Libraries Government Documents Department
open access

Chemically modified polymeric resins for solid-phase extraction and group separation prior to analysis by liquid or gas chromatography

Description: Polystyrene divinylbenzene was modified by acetyl, sulfonic acid, and quaternary ammonium groups. A resin functionalized with an acetyl group was impregnated in a PTFE membrane and used to extract and concentrate phenolic compounds from aqueous samples. The acetyl group created a surface easily wetted, making it an efficient adsorbent for polar compounds in water. The membrane stabilized the resin bed. Partially sulfonated high surface area resins are used to extract and group separate an aqueo… more
Date: July 1, 1993
Creator: Schmidt, L. W.
Partner: UNT Libraries Government Documents Department
open access

Optimization of separation and detection schemes for DNA with pulsed field slab gel and capillary electrophoresis

Description: The purpose of the Human Genome Project is outlined followed by a discussion of electrophoresis in slab gels and capillaries and its application to deoxyribonucleic acid (DNA). Techniques used to modify electroosmotic flow in capillaries are addressed. Several separation and detection schemes for DNA via gel and capillary electrophoresis are described. Emphasis is placed on the elucidation of DNA fragment size in real time and shortening separation times to approximate real time monitoring. The… more
Date: July 1, 1993
Creator: McGregor, D. A.
Partner: UNT Libraries Government Documents Department
open access

A measurement of the ({tau}) polarization at the Z resonance with the DELPHI detector at LEP

Description: The polarization of {tau} leptons produced in the reaction e{sup +}e{sup {minus}} {yields} {tau}{sup +}{tau}{sup {minus}} near the peak of the Z{degree} resonance has been measured using a sample of 24904 {tau}{sup +}{tau}{sup {minus}} events, with an estimated background of 1.5%. We have selected 4562 {tau} {yields} e{nu}{bar {nu}} 2218 {tau} {yields} {pi}{nu} and 5133 {tau} {yields} {rho}{nu} candidates. The mean value obtained is P{sub {tau}} = {minus}0.176 {plus_minus} 0.029. This correspon… more
Date: July 1, 1993
Creator: Wong Chan, A.
Partner: UNT Libraries Government Documents Department
open access

Interstitially stabilized phases in the zirconium-nickel system

Description: Addition of nonmetal interstitial atoms to Zr-Ni compounds has resulted in several new phases. A single-crystal x-ray study was carried out for Zr{sub 3}NiO. Zr{sub 4}Ni{sub 2}O is a high- temperature phase, forming in samples annealed at 1250 C. Huekel band calculations led to prediction and confirmation of additional phases in more electron rich systems. Other phases studied by XRD are Zr{sub 6}Ni{sub 4}Ti{sub 2}O{sub 0.6}, Nb{sub 6}Ni{sub 6}O, and Nb{sub 6}Ni{sub 4}Ta{sub 2}O{sub 2}. Phases … more
Date: July 1, 1993
Creator: MacKay, R. A.
Partner: UNT Libraries Government Documents Department
open access

Imaging earth`s interior: Tomographic inversions for mantle P-wave velocity structure

Description: A formalism is developed for the tomographic inversion of seismic travel time residuals. The travel time equations are solved both simultaneously, for velocity model terms and corrections to the source locations, and progressively, for each set of terms in succession. The methods differ primarily in their treatment of source mislocation terms. Additionally, the system of equations is solved directly, neglecting source terms. The efficacy of the algorithms is explored with synthetic data as we p… more
Date: July 1, 1991
Creator: Pulliam, R. J.
Partner: UNT Libraries Government Documents Department
open access

Oxygen electrode reaction in molten carbonate fuel cells. Final report, September 15, 1987--September 14, 1990

Description: Molten carbonate fuel cell system is a leading candidate for the utility power generation because of its high efficiency for fuel to AC power conversion, capability for an internal reforming, and a very low environmental impact. However, the performance of the molten carbonate fuel cell is limited by the oxygen reduction reaction and the cell life time is limited by the stability of the cathode material. An elucidation of oxygen reduction reaction in molten alkali carbonate is essential because… more
Date: July 7, 1992
Creator: Appleby, A. J. & White, R. E.
Partner: UNT Libraries Government Documents Department
open access

Acceleration of electrons using an inverse free electron laser auto- accelerator

Description: We present data from our study of a device known as the inverse free electron laser. First, numerical simulations were performed to optimize the design parameters for an experiment that accelerates electrons in the presence of an undulator by stimulated absorption of radiation. The Columbia free electron laser (FEL) was configured as an auto-accelerator (IFELA) system; high power (MW`s) FEL radiation at {approximately}1.65 mm is developed along the first section of an undulator inside a quasi-o… more
Date: July 1, 1992
Creator: Wernick, I. K. & Marshall, T. C.
Partner: UNT Libraries Government Documents Department
open access

Leaks in nuclear grade high efficiency aerosol filters

Description: Nuclear grade high efficiency aerosol filters, also known as high efficiency particulate air (HEPA) filters, are commonly used in air cleaning systems for removal of hazardous aerosols. Performance of the filter units is important in assuring health and environmental protection. The filter units are constructed from pleated packs of fiberglass filter media sealed into rigid frames. Results of previous studies on such filter units indicate that their performance may not be completely predicted b… more
Date: July 1, 1994
Creator: Scripsick, R. C.
Partner: UNT Libraries Government Documents Department
open access

Current-potential characteristics of electrochemical systems

Description: This dissertation contains investigations in three distinct areas. Chapters 1 and 2 provide an analysis of the effects of electromagnetic phenomena during the initial stages of cell discharge. Chapter 1 includes the solution to Maxwell`s equations for the penetration of the axial component of an electric field into an infinitely long cylindrical conductor. Chapter 2 contains the analysis of the conductor included in a radial circuit. Chapter 3 provides a complete description of the equations th… more
Date: July 1, 1993
Creator: Battaglia, V. S.
Partner: UNT Libraries Government Documents Department
open access

A dip-dependent divergence correction

Description: A divergence correction is conventionally applied to zero-offset data in an effort to preserved amplitude information. The conventional divergence correction compensates for the geometrical spreading of a point source in a horizontally layered medium where velocity varies with depth only. The dip-dependent divergence correction extends the conventional correction for improved amplitude processing of dipping beds. The dip-dependent divergence correction is computed by dynamic ray tracing, and ap… more
Date: July 1992
Creator: Fazzari, Franscesca
Partner: UNT Libraries Government Documents Department
open access

The processing and potential applications of porous silicon

Description: Stability of a cylindrical pore under the influence of surface energy is important for porous silicon (PS) processing in the integrated circuit industry. Once the zig-zag cylindrical pores of porous silicon or oxidized porous silicon (OPS) are unstable and breakup into rows of isolated spherical pores, oxidation of PS and densification/nitridation of OPS become difficult. Swing to difficulty transport of reactant gas (O{sub 2}, NH{sub 3}) or the trapped gas (for densification of OPS). A first o… more
Date: July 1, 1992
Creator: Shieh, Syyuan
Partner: UNT Libraries Government Documents Department
open access

Transition metal oxides deposited on rhodium and platinum: Surface chemistry and catalysis

Description: The surface chemistry and catalytic reactivity of transition metal oxides deposited on Rh and Pt substrates has been examined in order to establish the role of oxide-metal interactions in influencing catalytic activity. The oxides investigated included titanium oxide (TiOx), vanadium oxide (VOx), iron oxide (FeOx), zirconium oxide (ZrOx), niobium oxide (NbOx), tantalum oxide (TaOx), and tungsten oxide (WOx). The techniques used to characterize the sample included AES, XPS, LEED, TPD, ISS, and S… more
Date: July 1, 1994
Creator: Boffa, A. B.
Partner: UNT Libraries Government Documents Department
open access

Low-frequency nuclear quadrupole resonance with a dc SQUID

Description: Conventional pure nuclear quadrupole resonance (NQR) is a technique well suited for the study of very large quadrupolar interactions. Numerous nuclear magnetic resonance (NMR) techniques have been developed for the study of smaller quadrupolar interactions. However, there are many nuclei which have quadrupolar interactions of intermediate strength. Quadrupolar interactions in this region have traditionally been difficult or unfeasible to detect. This work describes the development and applicati… more
Date: July 1, 1991
Creator: Chang, J. W.
Partner: UNT Libraries Government Documents Department
open access

The effect of simplifying the building description on the numerical modeling of its thermal performance

Description: A thermal building simulation program is a numerical model that calculates the response of the building envelopes to weather and human activity, simulates dynamic heating and cooling loads, and heating and cooling distribution systems, and models building equipment operation. The scope of the research is to supply the users of such programs with information about the dangers and benefits of simplifying the input to their models. The Introduction describes the advantages of modeling the heat tra… more
Date: July 1, 1993
Creator: Stetiu, C.
Partner: UNT Libraries Government Documents Department
open access

Spatiotemporal Properties of Coupled Nonlinear Oscillators

Description: Spatiotemporal properties of classical coupled nonlinear oscillators are investigated in this thesis. Chapter 1 gives an introduction to nonlinear lattices and to the concept of breathers, that are spatially localized and temporally periodic excitation in nonlinear lattices. The concept of anti-continuous limit that provides the basic methodology in probing spatiotemporal breather properties is discussed. In Chapter 2, the general approach for finding exact breather solutions from the anti-cont… more
Date: July 1996
Creator: Chen, Ding
Partner: UNT Libraries
open access

A Study of the Relationships among Student Expectations about Teacher Nonverbal Immediacy, Student Perceptions of Teacher Nonverbal Immediacy, and Affective Learning in Distance Learning and the On-Site Classroom

Description: This thesis explored the relationships among three communication variables in college-level instruction: students' expectancy about teachers' nonverbal immediacy, students' actual perceptions of teachers' nonverbal immediacy, and students' affective learning. Community college students enrolled in either distance learning or a traditional classroom course completed pre-course and mid-course questionnaires to indicate their expectations and observations of the nonverbal immediacy behaviors of th… more
Date: July 1997
Creator: Witt, Paul L.
Partner: UNT Libraries
open access

A Machine Learning Method Suitable for Dynamic Domains

Description: The efficacy of a machine learning technique is domain dependent. Some machine learning techniques work very well for certain domains but are ill-suited for other domains. One area that is of real-world concern is the flexibility with which machine learning techniques can adapt to dynamic domains. Currently, there are no known reports of any system that can learn dynamic domains, short of starting over (i.e., re-running the program). Starting over is neither time nor cost efficient for real-wor… more
Date: July 1996
Creator: Rowe, Michael C. (Michael Charles)
Partner: UNT Libraries
Back to Top of Screen