828 Matching Results

Search Results

Advanced search parameters have been applied.

The Ways of Reflection: Heidegger, Science, Reflection, and Critical Interdisciplinarity

Description: This thesis argues that there is a philosophical attempt directed at combating the fragmentation of the sciences that starts with Heidegger and continues today through Trish Glazebrook's interpretations of the former's concept of "reflection," and Carl Mitcham and Robert Frodeman's concept of "critical interdisciplinarity" (CID). This is important as the sciences are both more implicated in our lives and more fragmented than ever. While scientific knowledge is pursued for its own sake, the pertinent facts, meaning, and application of the science is ignored. By linking Heidegger's views on the fragmentation of the sciences to Glazebrook's interpretations of reflection and Mitcham and Frodeman's CID, I show that CID is a concrete realization of Heidegger's reflection.
Date: May 2013
Creator: Toole, Toby Houston
Partner: UNT Libraries

Shock transmission and reflection from a material interface and subsequent reflection from a hard boundary

Description: As a shock wave passes through a material interface into a region of higher density (the receiver material), a trans- mitted and reflected shock wave are both generated and the interface is set into motion. The speeds of the transmitted shock, reflected shock, and interface are related to the ini- tial shock speed and material properties via a set of coupled nonlinear equations that, in general, cannot be easily solved analytically. In this report, we derive the equations which describe this process and we document a numerical routine which solves the nonlinear equations. We then go on to solve the problem of finding the position where the interface col- lides with the transmitted shock wave once the transmitted shock wave is reflected from an impenetrable boundary lo- cated somewhere away from the initial material interface. Fi- nally, we compare the analytical predictions with the CALE simulation running in 1-D.
Date: November 20, 1998
Creator: Hurricane, O A & Miller, P L
Partner: UNT Libraries Government Documents Department

T-R CYCLE CHARACTERIZATION AND IMAGING: ADVANCED DIAGNOSTIC METHODOLOGY FOR PETROLEUM RESERVOIR AND TRAP DETECTION AND DELINEATION

Description: The principal research effort for Year 1 of the project has been T-R cycle characterization and modeling. The research focus for the first nine (9) months of Year 1 was on outcrop study, well log analysis, seismic interpretation and data integration and for the remainder of the year the emphasis has been on T-R cycle model development. Information regarding the characteristics of T-R cycles has been assembled from the study of outcrops, from well log analyses, and from seismic reflection interpretation. From these studies, stratal boundaries separating T-R cycles have been found to be useful for the recognition and delineation of these cycles. The key stratal surfaces include subaerial unconformities, shoreface ravinement surfaces, transgressive surfaces, surfaces of maximum regression, and surfaces of maximum transgression. These surfaces can be identified and mapped in surface exposures and can be recognized in well log signatures and seismic reflection profiles as discontinuities. The findings from the study of outcrop, well log, and seismic reflection data are being integrated into a database for use in constructing a model for T-R cycle development.
Date: September 24, 2004
Creator: Mancini, Ernest A.
Partner: UNT Libraries Government Documents Department

Novel ultrasound scintillator

Description: This development project addressed the need for a faster, less expensive method of transmission ultrasound. It utilized the principle of frustrated total internal reflection to transduce acoustic pressure into optical modulation. These data were acquired an entire 2D plane at a time. This report described the modeling and verification of a final sensor design.
Date: February 9, 1999
Creator: Ashby, E; Ciarlo, D; Kallman, J S & Thomas, G
Partner: UNT Libraries Government Documents Department

Hochschild Cohomology and Complex Reflection Groups

Description: A concrete description of Hochschild cohomology is the first step toward exploring associative deformations of algebras. In this dissertation, deformation theory, geometry, combinatorics, invariant theory, representation theory, and homological algebra merge in an investigation of Hochschild cohomology of skew group algebras arising from complex reflection groups. Given a linear action of a finite group on a finite dimensional vector space, the skew group algebra under consideration is the semi-direct product of the group with a polynomial ring on the vector space. Each representation of a group defines a different skew group algebra, which may have its own interesting deformations. In this work, we explicitly describe all graded Hecke algebras arising as deformations of the skew group algebra of any finite group acting by the regular representation. We then focus on rank two exceptional complex reflection groups acting by any irreducible representation. We consider in-depth the reflection representation and a nonfaithful rotation representation. Alongside our study of cohomology for the rotation representation, we develop techniques valid for arbitrary finite groups acting by a representation with a central kernel. Additionally, we consider combinatorial questions about reflection length and codimension orderings on complex reflection groups. We give algorithms using character theory to compute reflection length, atoms, and poset relations. Using a mixture of theory, explicit examples, and calculations using the software GAP, we show that Coxeter groups and the infinite family G(m,1,n) are the only irreducible complex reflection groups for which the reflection length and codimension orders coincide. We describe the atoms in the codimension order for the groups G(m,p,n). For arbitrary finite groups, we show that the codimension atoms are contained in the support of every generating set for cohomology, thus yielding information about the degrees of generators for cohomology.
Date: August 2012
Creator: Foster-Greenwood, Briana A.
Partner: UNT Libraries

Exploration of Sculpture

Description: The images that I sculpt deal with reflections of human traits. Wood lends itself to this endeavor, offering minimal resistance to manipulation. Keeping the origin and qualities of the material while manipulating it into another object is a statement within itself. Letting the wood do what it does naturally keeps the viewer in touch with the fact it is still just an object of nature. Wood does not make itself any less real because of the relationship of the sculpture to it as wood.
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: December 1999
Creator: Coldewey, Charles
Partner: UNT Libraries

Crystallographic Complex Reflection Groups and the Braid Conjecture

Description: Crystallographic complex reflection groups are generated by reflections about affine hyperplanes in complex space and stabilize a full rank lattice. These analogs of affine Weyl groups have infinite order and were classified by V.L. Popov in 1982. The classical Braid theorem (first established by E. Artin and E. Brieskorn) asserts that the Artin group of a reflection group (finite or affine Weyl) gives the fundamental group of regular orbits. In other words, the fundamental group of the space with reflecting hyperplanes removed has a presentation mimicking that of the Coxeter presentation; one need only remove relations giving generators finite order. N.V Dung used a semi-cell construction to prove the Braid theorem for affine Weyl groups. Malle conjectured that the Braid theorem holds for all crystallographic complex reflection groups after constructing Coxeter-like reflection presentations. We show how to extend Dung's ideas to crystallographic complex reflection groups and then extend the Braid theorem to some groups in the infinite family [G(r,p,n)]. The proof requires a new classification of crystallographic groups in the infinite family that fail the Steinberg theorem.
Date: August 2017
Creator: Puente, Philip C
Partner: UNT Libraries

Reflection Mode Imaging with High Resolution X-rayMicroscopy

Description: We report on the first demonstration of imaging microstructures with soft x-ray microscopy operating in reflection geometry. X-ray microscopy in reflection mode combines the high resolution available with x-ray optics, the ability to image thick samples, and to directly image surfaces and interfaces. Future experiments with this geometry will include tuning the incident angle to obtain depth resolution. In combination with XMCD as magnetic contrast mechanism this mode will allow studies of deep buried magnetic interfaces.
Date: April 2, 2005
Creator: Denbeaux, Greg; Fischer, Peter; Salmassi, Farhad; Dunn, Kathleen & Evertsen, James
Partner: UNT Libraries Government Documents Department

Reconstruction of quasi-monochromatic images from a multiple monochromatic x-ray imaging diagnostic for inertial confinement fusion

Description: We have developed a software package for image reconstruction of a multiple monochromatic x-ray imaging diagnostics (MMI) for diagnostic of inertial conferment fusion capsules. The MMI consists of a pinhole array, a multi-layer Bragg mirror, and a charge injection device image detector (CID). The pinhole array projects {approx}500 sub-images onto the CID after reflection off the multi-layer Bragg mirror. The obtained raw images have continuum spectral dispersion on its vertical axis. For systematic analysis, a computer-aided reconstruction of the quasi-monochromatic image is essential.
Date: April 15, 2004
Creator: Izumi, N; Turner, R; Barbee, T; Koch, J; Welser, L & Mansini, R
Partner: UNT Libraries Government Documents Department

Restricting Invariants and Arrangements of Finite Complex Reflection Groups

Description: Suppose that G is a finite, unitary reflection group acting on a complex vector space V and X is a subspace of V. Define N to be the setwise stabilizer of X in G, Z to be the pointwise stabilizer, and C=N/Z. Then restriction defines a homomorphism from the algebra of G-invariant polynomial functions on V to the algebra of C-invariant functions on X. In my thesis, I extend earlier work by Douglass and Röhrle for Coxeter groups to the case where G is a complex reflection group of type G(r,p,n) in the notation of Shephard and Todd and X is in the lattice of the reflection arrangement of G. The main result characterizes when the restriction mapping is surjective in terms of the exponents of G and C and their reflection arrangements.
Date: August 2015
Creator: Berardinelli, Angela
Partner: UNT Libraries

Determination of the electronic structure of bilayer graphene from infrared spectroscopy results

Description: We present an experimental study of the infrared conductivity, transmission, and reflection of a gated bilayer graphene and their theoretical analysis within the Slonczewski-Weiss-McClure (SWMc) model. The infrared response is shown to be governed by the interplay of the interband and the intraband transitions among the four bands of the bilayer. The position of the main conductivity peak at thecharge-neutrality point is determined by the interlayer tunneling frequency. The shift of this peak as a function of the gate voltage gives information about less known parameters of the SWMc model such as those responsible for the electron-hole and sublattice asymmetries. These parameter values are shown to be consistent with recent electronic structure calculations for the bilayer graphene and the SWMc parameters commonly used for the bulk graphite.
Date: November 12, 2008
Creator: Zhang, L. M.; Li, Z. Q.; Basov, D. N.; Fogler, M. M.; Hao, Z. & Martin, Michael C.
Partner: UNT Libraries Government Documents Department

An Examination of Text Reflection and Imagery in Zoltán Gárdonyi’s Fünf Lieder Nach Gedichten Von Rainer Maria Rilke

Description: Zoltán Gárdonyi is described as having exemplified “the continuation of the Liszt tradition” in his music; however, since for so much of his compositional life he was forbidden to publish by the Communist government in Hungary due to his connection to the Christian church, he has been largely forgotten. Shortly after the composer’s death in 1986, Gárdonyi’s son, Zsolt (b.1946) began publishing his father’s music in addition to his own. However, the elder Gárdonyi’s works are still not widely known outside Hungary and Germany. Gárdonyi’s ability to support and reflect text musically makes his songs excellent teaching tools and recital repertoire. A characteristic example of this may be found in his Fünf Lieder nach Gedichten von Rainer Maria Rilke. According to his son, Zoltán wrote these songs “in the German romantic tradition (e.g. Brahms) like a mirror for the romantic influenced lyrics.” Examination of the Rilke-Lieder, and of the poems which make up the cycle, demonstrates the composer’s ability to “mirror” text in both general tone and specific idea. Discussion of imagery, textures and sonorities, and elements of harmony, melody and rhythm as they relate to interpretation of the poetry, reveal the depth to which the poetry is embedded in the music of the songs. At times the piano becomes another “narrator” or even a character in the poems, expressing not only text but subtext as well. This document explores the illustration of the extensive imagery of Rilke’s texts in the music of Fünf Lieder nach Gedichten von Rainer Maria Rilke, with the purpose of both introducing Gárdonyi’s song literature to American singers and voice teachers, and making the case for its inclusion in the canon of repertoire for the studio and the stage.
Date: August 2014
Creator: Beloncik Schantz, Anne
Partner: UNT Libraries

Ball lens reflections by direct solution of Maxwell`s equations

Description: Ball lenses are important for many applications. For example, ball lenses can be used to match the mode of a laser diode (LD) to a single mode fiber (SMF), essential for low-loss, high bit rate communication systems. Modeling the propagation of LD light through a ball lens presents a challenge due to the large angular divergence of the LD field (typically > 20{degrees} HWHM) and the subsequent significant effect of spherical aberration. Accurately calculating the reflected power is also difficult, but essential, since reflections as small as {minus}30 dB can destabilize the LID. A full-wave analysis of this system using, e.g., a finite-difference time-domain method is not practical because of the size of the ball lens, typically hundreds of wavelengths in diameter. Approximate scalar methods can give good results in some cases, but fail to calculate reflected power and miss polarization effects entirely. The authors` approach exploits the fact that the scattering of an arbitrary electromagnetic beam from a sphere is an exactly solvable problem. The scattering of a plane wave from a sphere is a classical problem which was solved by Mie in 1908. More recently, various workers have considered the scattering of a Gaussian beam from a sphere and its numerical implementation for other applications. To the authors knowledge, this is the first time this approach has been applied to a problem in optical design. They are able to calculate reflection and transmission accurately with modest computational effort.
Date: February 15, 1995
Creator: Ratowsky, R.P.; Deri, R.J. & Kallman, J.S.
Partner: UNT Libraries Government Documents Department

A hydrologic view on Biot's theory of poroelasticity

Description: The main objective of this work is to obtain a simplified asymptotic representation of the reflection of seismic signal from a fluid-saturated porous medium in the low-frequency domain. In the first part, we derive the equations of low-frequency harmonic waves in a fluid-saturated elastic porous medium from the basic concepts of filtration theory. We demonstrate that the obtained equations can be related to the poroelasticity model of Frenkel-Gassmann-Biot, and to pressure diffusion model routinely used in well test analysis as well. We thus try to put the poroelastic and filtration theories on the same ground. We study the reflection of a low-frequency signal from a plane interface between elastic and elastic fluid-saturated porous media. We obtain an asymptotic scaling of the frequency-dependent component of the reflection coefficient with respect to a dimensionless parameter depending on the frequency of the signal and the reservoir fluid mobility. We also investigate the impact of the relaxation time and tortuosity on this scaling.
Date: January 13, 2004
Creator: Silin, D.B.; Korneev, V.A.; Goloshubin, G.M. & Patzek, T.W.
Partner: UNT Libraries Government Documents Department

T-R Cycle Characterization and Imaging: Advanced Diagnostic Methodology for Petroleum Reservoir and Trap Detection and Delineation

Description: Characterization of stratigraphic sequences (T-R cycles or sequences) included outcrop studies, well log analysis and seismic reflection interpretation. These studies were performed by researchers at the University of Alabama, Wichita State University and McGill University. The outcrop, well log and seismic characterization studies were used to develop a depositional sequence model, a T-R cycle (sequence) model, and a sequence stratigraphy predictive model. The sequence stratigraphy predictive model developed in this study is based primarily on the modified T-R cycle (sequence) model. The T-R cycle (sequence) model using transgressive and regressive systems tracts and aggrading, backstepping, and infilling intervals or sections was found to be the most appropriate sequence stratigraphy model for the strata in the onshore interior salt basins of the Gulf of Mexico to improve petroleum stratigraphic trap and specific reservoir facies imaging, detection and delineation. The known petroleum reservoirs of the Mississippi Interior and North Louisiana Salt Basins were classified using T-R cycle (sequence) terminology. The transgressive backstepping reservoirs have been the most productive of oil, and the transgressive backstepping and regressive infilling reservoirs have been the most productive of gas. Exploration strategies were formulated using the sequence stratigraphy predictive model and the classification of the known petroleum reservoirs utilizing T-R cycle (sequence) terminology. The well log signatures and seismic reflector patterns were determined to be distinctive for the aggrading, backstepping and infilling sections of the T-R cycle (sequence) and as such, well log and seismic data are useful for recognizing and defining potential reservoir facies. The use of the sequence stratigraphy predictive model, in combination with the knowledge of how the distinctive characteristics of the T-R system tracts and their subdivisions are expressed in well log patterns and seismic reflection configurations and terminations, improves the ability to identify and define the limits of potential stratigraphic traps and ...
Date: August 30, 2006
Creator: Mancini, Ernest A.
Partner: UNT Libraries Government Documents Department

Extensions to Jinni Mobile Agent Architecture

Description: We extend the Jinni mobile agent architecture with a multicast network transport layer, an agent-to-agent delegation mechanism and a reflection based Prolog-to-Java interface. To ensure that our agent infrastructure runs efficiently, independently of router-level multicast support, we describe a blackboard based algorithm for locating a randomly roaming agent. As part of the agent-to-agent delegation mechanism, we describe an alternative to code-fetching mechanism for stronger mobility of mobile agents with less network overhead. In the context of direct and reflection based extension mechanisms for Jinni, we describe the design and the implementation of a reflection based Prolog-to-Java interface. The presence of subtyping and method overloading makes finding the most specific method corresponding to a Prolog call pattern fairly difficult. We describe a run-time algorithm which provides accurate handling of overloaded methods beyond Java's reflection package's limitations.
Date: May 2001
Creator: Tyagi, Satyam
Partner: UNT Libraries

Laterally graded multilayer double-monochromator.

Description: The authors describe a tunable multilayer monochromator with an adjustable bandpass to be used for reflectivity and grazing incidence diffraction studies on surfaces at energies near 10 keV. Multilayers have a bandpass typically 100 times larger than the Si(111) reflection, and by using multilayers an experimenter can significantly increase data collection rates over those available with a Si monochromator. The transmission through 1 and 2 laterally graded multilayer (LGML) reflections was recorded versus photon energy. The identical LGMLs were comprised of 60 bilayers of W and C on 100 x 25 x 3 mm float glass with a bilayer spacing varying from 35 to 60 {angstrom}. The average gradient was 0.27 {angstrom}/mm along the long dimension. The rms deviation of the data for the bilayer spacing from a linear fit was 0.36 {angstrom}. Data were obtained for a nondispersive ({+-}) double-multilayer arrangement. The relative bandpass width (FWHM) when the two multilayers exposed the same bilayer spacing was measured to be 2.2% with a transmission of 78.7 {+-} 1.6%. This value is consistent with the transmission of 88.9% that they also measured for a single LGML at HASYLAB beamline D4. The bandpass was tunable in the range 1.1% to 2.2%.
Date: September 1, 1999
Creator: Als-Nielsen, J.; Erdmann, J.; Gaarde, P.; Krasnicki, S.; Liu, C.; Macrander, A. T. et al.
Partner: UNT Libraries Government Documents Department

Low-frequency asymptotic analysis of seismic reflection from afluid-saturated medium

Description: Reflection of a seismic wave from a plane interface betweentwo elastic media does not depend on the frequency. If one of the mediais poroelastic and fluid-saturated, then the reflection becomesfrequency-dependent. This paper presents a low-frequency asymptoticformula for the reflection of seismic plane p-wave from a fluid-saturatedporous medium. The obtained asymptotic scaling of the frequency-dependentcomponent of the reflection coefficient shows that it is asymptoticallyproportional to the square root of the product of the reservoir fluidmobility and the frequency of the signal. The dependence of this scalingon the dynamic Darcy's law relaxation time is investigated as well.Derivation of the main equations of the theory of poroelasticity from thedynamic filtration theory reveals that this relaxation time isproportional to Biot's tortuosity parameter.
Date: April 14, 2004
Creator: Silin, D.B.; Korneev, V.A.; Goloshubin, G.M. & Patzek, T.W.
Partner: UNT Libraries Government Documents Department

Structure Determination I

Description: A program to calculate the structure factor or intensity for a given set of reflections written for the IBM 650 is described. Each sin/sup 2/ theta , multiplicity, and scattening factor for each element must be entered. The program has space for a maximum of 100 atomic positions and 18 elements. Instruction for an option to calculate cos or sin alone with some saving of time is included. (J.R.D.)
Date: March 1, 1960
Creator: Sherry, E. G.
Partner: UNT Libraries Government Documents Department

A TREATMENT OF SOME PERIODIC POTENTIAL PROBLEMS

Description: A method of treating periodic potential problems, which appears to offer some simplifications, is described. The classical Kronig-Penny problem was treated as an introduction to the applications after which the method was used to obtain the band structure for the periodic potential, the parabolic scallop potential,'' consisting of a linear chain of segments of vertical parabolas opening upwards. The general problem for the one-dimensional periodic potential with reflection symmetry was then treated and illustrated by application of the method to the linear chain of inverted parabolic segments. As a third example the band structure was obtained for the hip-roof'' potential. The three- dimensional problem is also discussed. (auth)
Date: November 1, 1962
Creator: McColl, D. & Simpson, O.C.
Partner: UNT Libraries Government Documents Department

Nature of room-temperature photoluminescence in ZnO

Description: The temperature dependence of the photoluminescence (PL) transitions associated with various excitons and their phonon replicas in high-purity bulk ZnO has been studied at temperatures from 12 K to above room temperature (320 K). Several strong PL emission lines associated with LO phonon replicas of free and bound excitons are clearly observed. The room temperature PL spectrum is dominated by the phonon replicas of the free exciton transition with the maximum at the first LO phonon replica. The results explain the discrepancy between the transition energy of free exciton determined by reflection measurement and the peak position obtained by the PL measurement.
Date: November 11, 2004
Creator: Shan, W.; Walukiewicz, W.; Ager III, J.W.; Yu, K.M.; Yuan, H.B.; Xin, H.P. et al.
Partner: UNT Libraries Government Documents Department