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464 Matching Results
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Imagery and Form
This paper discusses the integration of imagery and form in the author's works, wheel thrown pottery intended to make an individualized statement. Steven L. Phillips discusses the process of making these forms and the imagery they contain, drawing connections to philosophical concepts.
Date:
May 1994
Creator:
Phillips, Steven L.
System:
The UNT Digital Library
A Visual Study of Folk Art Death Imagery Used During the Day of the Dead Celebration in Mexico
This paper discusses the author's work creating five collagraph prints based on imagery used during the Mexican Day of the Dead celebration and the process of making these prints. Eduardo J. Garcia discusses how heritage impacted these works and explores the meaning behind the folk art imagery.
Date:
December 1994
Creator:
Garcia, Eduardo J.
System:
The UNT Digital Library
Living Walls: The Integration of Clay and Architecture
Although clay has been used throughout history as an embellishment of architectural structures, clay elements have usually remained subordinate to existing architectural forms. Three-dimensional ceramic modules which divided an existing space, altered or obscured architectural forms, and intersected with or penetrated established planes provided a greater interaction between clay and architecture. I explored the use of clay as an integral three-dimensional element which interacted with an architectural space, rather than merely surfacing it. Because the installation of these works was temporary, methods of connecting the clay elements to the architecture were also investigated.
Date:
May 1994
Creator:
Gray, Douglas E.
System:
The UNT Digital Library
Ordering Chaos: The Integration of Form and Surface Through a Combination of Chance and Design
The purpose of this research was to develop a body of work which exhibited unity between form and surface, but which relied upon a combination of deliberate intent (specific form, glaze, firing temperature, etc.) and the occurrence of random accident to achieve this unity. The project dealt with the integration of altered wheel-thrown and hand-built organic clay forms with a variety of surface treatments. The firing/glazing techniques chosen (which included cone 9 reduction firing, raku firing, and saggar firing) could be controlled to some degree. However, even minor differences in glaze and/or firing treatments evolved through a variety of chance incidents into marked differences in the finished piece.
Date:
May 1994
Creator:
Rhudy, Dannon
System:
The UNT Digital Library
Personal and Universal Imagery: Prehistory and the Future
I wished to explore ways to introduce my futuristic symbols in my work that have a relevant universality, support a primordial mysticism, and maintain a personal spirituality. This would be achieved by utilizing imagery with both contemporary and futuristic connotations. This type of imagery would require specific sculptural techniques more refined than was previously present in my work. The sculpture would consist of solitary, tensely postured, monumental figures composed according to a classically proportioned totemic model.
Date:
August 1994
Creator:
Askew, Daniel
System:
The UNT Digital Library
An Analysis of Two Dimensional Printed Elements Within Three Dimensional Structures
I believe the frame or housing of a printed image plays an integral role in the context of the work. It functions as a vehicle for possible interpretation. It should respond to and complement the concept of the central image. The image presented in a vessel or reliquary format should instill a meditative or religious response.
Date:
May 1994
Creator:
Hubner, Lynne J.
System:
The UNT Digital Library
The Execution of Woodcut Prints Utilizing Photographs as Source Material
The purpose of this study was to investigate the personal success of using photographs as source material for woodcuts or other relief prints, and to determine how my selectivity, editing, and execution would enhance the content of these works. I proposed to create a body of woodcuts whose subject matter would be based on photographs dealing with the scenes and legends of Texas.
Date:
August 1994
Creator:
Hagard, Ernestine
System:
The UNT Digital Library
An Exploration of the Visual Impact of Symmetry, Texture, and Multicultural Imagery on the Chalice
The emotional and psychological reaction to a chalice is determined in part by the visual impact of the vessel. The goal of this problem has been to explore the visual impact of contemporary techniques and traditional materials, combined with multi-cultural imagery on the perception of the vessel as a chalice.
Date:
May 1994
Creator:
Siewert, Paul A. II
System:
The UNT Digital Library
Art and Self-Awareness: A Personal Investigation
This paper describes the artist's conception of their scientific knowledge and spiritual beliefs, and the juxtaposition of the two in a single awareness. Michael Muller discusses the use of printmaking, drawing, and photo mechanical processes to represent this awareness through visual imagery, and includes photographs of the works.
Date:
May 1994
Creator:
Muller, Michael
System:
The UNT Digital Library
Seismic evidence of conjugate normal faulting: The 1994 Devil Canyon earthquake sequence near Challis, Idaho
None
Date:
August 1, 1994
Creator:
Jackson, S. M.
System:
The UNT Digital Library
QCD test in three-jet Z{sup 0} decays at SLD and detector development for H{sup 0} {yields} {gamma}{gamma} searches in high energy hadron colliders
None
Date:
August 1, 1994
Creator:
Hwang, Hyun
System:
The UNT Digital Library
Carbon doping of III-V compound semiconductors
Focus of the study is C acceptor doping of GaAs, since C diffusion coefficient is at least one order of magnitude lower than that of other common p-type dopants in GaAs. C ion implantation results in a concentration of free holes in the valence band < 10% of that of the implanted C atoms for doses > 10{sup 14}/cm{sup 2}. Rutherford backscattering, electrical measurements, Raman spectroscopy, and Fourier transform infrared spectroscopy were amonth the techniques used. Ga co-implantation increased the C activation in two steps: first, the additional radiation damage creates vacant As sites that the implanted C can occupy, and second, it maintains the stoichiometry of the implanted layer, reducing the number of compensating native defects. In InP, the behavior of C was different from that in GaAs. C acts as n-type dopant in the In site; however, its incorporation by implantation was difficult to control; experiments using P co-implants were inconsistent. The lattice position of inactive C in GaAs in implanted and epitaxial layers is discussed; evidence for formation of C precipitates in GaAs and InP was found. Correlation of the results with literature on C doping in III-V semiconductors led to a phenomenological description of C in …
Date:
September 1, 1994
Creator:
Moll, A. J.
System:
The UNT Digital Library
Study of radicals, clusters and transition state species by anion photoelectron spectroscopy
Free radicals, elemental and van der Waals clusters and transition state species for bimolecular chemical reactions are investigated using anion photoelectron spectroscopy. Several low-lying electronic states of ozone have been identified via photoelectron spectroscopy of O{sub 3}{sup {minus}}. A characterization of these states is important to models for atmospheric ozone reaction kinetics. The fluoroformyloxyl radical, FCO{sub 2}, has been investigated, providing vibrational frequencies and energies for two electronic states. The technique has also been employed to make the first direct observation and characterization of the NNO{sub 2} molecule. Several electronic states are observed for this species which is believed to play a role as a reactive intermediate in the N + NO{sub 2} reaction. The experimental results for all three of these radicals are supplemented by ab initio investigations of their molecular properties. The clusters investigations include studies of elemental carbon clusters (C{sub 2}{sup {minus}} {minus} C{sub 11}{sup {minus}}), and van der Waals clusters (X{sup {minus}}(CO{sub 2}){sub n}, X = I, Br, Cl; n {le} 13 and I{sup {minus}} (N{sub 2}O){sub n=1--11}). Primarily linear clusters are observed for the smaller carbon clusters, while the spectra of the larger clusters contain contribution from cyclic anion photodetachment. Very interesting ion-solvent interactions are …
Date:
August 1, 1994
Creator:
Arnold, D. W.
System:
The UNT Digital Library
A discrete variable representation for electron-hydrogen atom scattering
A discrete variable representation (DVR) suitable for treating the quantum scattering of a low energy electron from a hydrogen atom is presented. The benefits of DVR techniques (e.g. the removal of the requirement of calculating multidimensional potential energy matrix elements and the availability of iterative sparse matrix diagonalization/inversion algorithms) have for many years been applied successfully to studies of quantum molecular scattering. Unfortunately, the presence of a Coulomb singularity at the electrically unshielded center of a hydrogen atom requires high radial grid point densities in this region of the scattering coordinate, while the presence of finite kinetic energy in the asymptotic scattering electron also requires a sufficiently large radial grid point density at moderate distances from the nucleus. The constraints imposed by these two length scales have made application of current DVR methods to this scattering event difficult.
Date:
August 1, 1994
Creator:
Gaucher, L. F.
System:
The UNT Digital Library
Transition metal oxides deposited on rhodium and platinum: Surface chemistry and catalysis
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 STM. After characterization of the surface in UHV, the sample was enclosed in an atmospheric reaction cell to measure the influence of the oxide deposits on the catalytic activity of the pure metal for CO and CO{sub 2} hydrogenation. The oxide deposits were found to strongly enhance the reactivity of the Rh foil. The rates of methane formation were promoted by up to 15 fold with the maximum in rate enhancement occurring at oxide coverages of approximately 0.5 ML. TiOx TaOx, and NbOx were the most effective promoters and were stable in the highest oxidation states during both reactions (compared to VOx, WOx, and FeOx). The trend in promoter effectiveness was attributed to the direct relationship between oxidation state and Lewis acidity. Bonding at the metal oxide/metal interface …
Date:
July 1, 1994
Creator:
Boffa, A. B.
System:
The UNT Digital Library
Laser trapping of {sup 21}Na atoms
This thesis describes an experiment in which about four thousand radioactive {sup 21}Na (t{sub l/2} = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped {sup 21}Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of {sup 21}Na {yields} {sup 21}Ne + {Beta}{sup +} + v{sub e}, which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trapped atoms that we have achieved is still about two orders of magnitude lower than what is needed to conduct a measurement of the beta-asymmetry parameter at 1% of precision level, the result of this experiment proved the feasibility of trapping short-lived radioactive atoms. In this experiment, {sup 21}Na atoms were produced by bombarding {sup 24}Mg with protons of 25 MeV at the 88 in. Cyclotron of Lawrence Berkeley Laboratory. A few recently developed techniques of laser manipulation of neutral atoms were applied in this experiment. The {sup 21}Na atoms emerging from a heated oven were first transversely cooled. As a result, the on-axis atomic beam intensity was increased by a factor of 16. The atoms in …
Date:
September 1, 1994
Creator:
Lu, Zheng-Tian
System:
The UNT Digital Library
Theory and modelling of quench in cable-in-conduit superconducting magnets
A new simple, self consistent theoretical model is presented that describes the phenomena of quench propagation in Cable-In-Conduit superconducting magnets. The model (Quencher) circumvents many of the difficulties associated with obtaining numerical solutions in more general existing models. Specifically, a factor of 30-50 is gained in CPU time over the general, explicit time dependent codes used to study typical quench events. The corresponding numerical implementation of the new model is described and the numerical results are shown to agree very well with those of the more general models, as well as with experimental data. Further, well justified approximations lead to the MacQuench model that is shown to be very accurate and considerably more efficient than the Quencher model. The MacQuench code is suitable for performing quench studies on a personal computer, requiring only several minutes of CPU time. In order to perform parametric studies on new conductor designs it is required to utilize a model such as MacQuench because of the high computational efficiency of this model. Finally, a set of analytic solutions for the problem of quench propagation in Cable-In-Conduit Conductors is presented. These analytic solutions represent the first such results that remain valid for the long time scales …
Date:
April 1, 1994
Creator:
Shajii, A.
System:
The UNT Digital Library
The low temperature properties of (Dy{sub 1-x}Er{sub x})Ni{sub 2} alloys
The study of rare earth magnetic properties is undertaken to further the understanding of critical phenomena and the mechanism of magnetic ordering in solids. There is a great variety of magnetic ordering observed in the rare earth compounds, thus providing an insight to phenomena such as heat capacity, magnetostriction and crystal fields. Studies began on the magnetic properties of the rare earths and their compounds in the 1950`s.
Date:
July 27, 1994
Creator:
Gailloux, M.
System:
The UNT Digital Library
Straddle-packer determination of the vertical distribution of hydraulic properties in the Snake River Plain Aquifer at well USGS-44, Idaho Chemical Processing Plant, INEL
Many of the monitor wells that penetrate the upper portion of the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL) are open over large intervals that include multiple water-bearing zones. Most of these wells are equipped with dedicated submersible pumps. Water of varying quality from different water-bearing zones is mixed within the wells. The hydrologic properties of individual water bearing zones are difficult to determine. Water quality and water-level data on organic, heavy metal, and radioactive contaminants have been collected, reported, and interpreted from these monitor wells for more than forty years. The problems associated with well completions over large intervals through multiple water-bearing zones raise significant questions about the data. A straddle-packer system was developed and applied at the INEL site to investigate the monitor well network. The straddle-packer system, hydraulic testing methods, data analysis procedures, and testing results are described in this report. The straddle-packer system and the straddle-packer testing and data evaluation procedures can be improved for future testing at the INEL site. Recommended improvements to the straddle-packer system are: (1) improved transducer pressure sensing systems, (2) faster opening riser valve, and (3) an in-line flowmeter in the riser pipe. Testing and data evaluation …
Date:
September 23, 1994
Creator:
Monks, J. I.
System:
The UNT Digital Library
Directional solidification of the alumina-zirconia ceramic eutectic system
It is possible to produce alumina-zirconia ceramic samples through existing solidification techniques. The resulting microstructures typically consist of rods of zirconia in an alumina matrix, although a lamellar structure has been noted in some cases. In nearly all cases, colony growth was present which may possibly result from grain size, repeated nucleation events, and lamellar oscillations. In the same vein, it appears that the amount of impurities within the system might be the underlying cause for the colony growth. Colony growth was diminished through impurity control as the higher purity samples exhibited colony free behavior. In addition to colony formations, faceted alumina dendrites or nonfaceted zirconia dendrites may result in the ceramic if the sample is solidified out of the coupled zone. In all cases, for larger-sized Bridgman samples, a lower limit in the eutectic spacing was noted. The solidification model which includes the kinetic effect has been developed, although the effect appears to be negligible under present experimental conditions. A spacing limit might also occur due to the result of heat flow problems. Heat flow out of the ceramic is difficult to control, often causing radial and not axial growth. This behavior is exaggerated in the presence of impurities. …
Date:
July 27, 1994
Creator:
Boldt, C.
System:
The UNT Digital Library
Novel absorption detection techniques for capillary electrophoresis
Capillary electrophoresis (CE) has emerged as one of the most versatile separation methods. However, efficient separation is not sufficient unless coupled to adequate detection. The narrow inner diameter (I.D.) of the capillary column raises a big challenge to detection methods. For UV-vis absorption detection, the concentration sensitivity is only at the {mu}M level. Most commercial CE instruments are equipped with incoherent UV-vis lamps. Low-brightness, instability and inefficient coupling of the light source with the capillary limit the further improvement of UV-vis absorption detection in CE. The goals of this research have been to show the utility of laser-based absorption detection. The approaches involve: on-column double-beam laser absorption detection and its application to the detection of small ions and proteins, and absorption detection with the bubble-shaped flow cell.
Date:
July 27, 1994
Creator:
Xue, Y.
System:
The UNT Digital Library
Development of novel separation techniques for biological samples in capillary electrophoresis
This dissertation includes three different topics: general introduction of capillary electrophoresis (CE); gradient in CE and CE in biological separations; and capillary gel electrophoresis (CGE) for DNA separation. Factors such as temperature, viscosity, pH, and the surface of capillary walls affecting the separation performance are demonstrated. A pH gradient between 3.0 and 5.2 is useful to improve the resolution among eight different organic acids. A flow gradient due to the change in the concentration of surfactant, which is able to coat to the capillary wall to change the flow rate and its direction, is also shown as a good way to improve the resolution for organic compounds. A temperature gradient caused by joule heat is shown by voltage programming to enhance the resolution and shorten the separation time for several phenolic compounds. The author also shows that self-regulating dynamic control of electroosmotic flow in CE by simply running separation in different concentrations of surfactant has less matrix effect on the separation performance. One of the most important demonstrations in this dissertation is that the author proposes on-column reaction which gives several advantages including the use of a small amount of sample, low risk of contamination, and time saving and kinetic …
Date:
July 27, 1994
Creator:
Chang, H. T.
System:
The UNT Digital Library
Reflective masks for extreme ultraviolet lithography
Extreme ultraviolet lithographic masks are made by patterning multilayer reflective coatings with high normal incidence reflectivity. Masks can be patterned by depositing a patterned absorber layer above the coating or by etching the pattern directly into the coating itself. Electromagnetic simulations showed that absorber-overlayer masks have superior imaging characteristics over etched masks (less sensitive to incident angles and pattern profiles). In an EUVL absorber overlayer mask, defects can occur in the mask substrate, reflective coating, and absorber pattern. Electromagnetic simulations showed that substrate defects cause the most severe image degradation. A printability study of substrate defects for absorber overlayer masks showed that printability of 25 nm high substrate defects are comparable to defects in optical lithography. Simulations also indicated that the manner in which the defects are covered by multilayer reflective coatings can affect printability. Coverage profiles that result in large lateral spreading of defect geometries amplify the printability of the defects by increasing their effective sizes. Coverage profiles of Mo/Si coatings deposited above defects were studied by atomic force microscopy and TEM. Results showed that lateral spread of defect geometry is proportional to height. Undercut at defect also increases the lateral spread. Reductions in defect heights were observed for …
Date:
May 1, 1994
Creator:
Nguyen, Khanh Bao
System:
The UNT Digital Library
Theoretical study of the noble metals on semiconductor surfaces and Ti-base shape memory alloys
The electronic and structural properties of the ({radical}3 {times} {radical}3) R30{degrees} Ag/Si(111) and ({radical}3 {times} {radical}3) R30{degrees} Au/Si(111) surfaces are investigated using first principles total energy calculations. We have tested almost all experimentally proposed structural models for both surfaces and found the energetically most favorable model for each of them. The lowest energy model structure of the ({radical}3 {times} {radical}3) R30{degrees} Ag/Si(111) surface consists of a top layer of Ag atoms arranged as ``honeycomb-chained-trimers`` lying above a distorted ``missing top layer`` Si(111) substrate. The coverage of Ag is 1 monolayer (ML). We find that the honeycomb structure observed in STM images arise from the electronic charge densities of an empty surface band near the Fermi level. The electronic density of states of this model gives a ``pseudo-gap`` around the Fermi level, which is consistent with experimental results. The lowest energy model for the ({radical}3 {times} {radical}3) R30{degrees} Au/Si(111) surface is a conjugate honeycomb-chained-trimer (CHCT-1) configuration which consists of a top layer of trimers formed by 1 ML Au atoms lying above a ``missing top layer`` Si(111) substrate with a honeycomb-chained-trimer structure for its first layer. The structures of Au and Ag are in fact quite similar and belong to the …
Date:
July 27, 1994
Creator:
Ding, Yungui
System:
The UNT Digital Library