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[UNT graduate students take center stage, April 9, 1995] (open access)

[UNT graduate students take center stage, April 9, 1995]

An article written by April M. Washington for the Denton Record-Chronicle that covers two graduate students from UNT, Bader Alruwais and Matthew Mailman. Alruwais received the Prince Bandar ibn Sultan Annual Award for Cultural and Scientific Research and Mailman is conducting a recital performance.
Date: April 9, 1995
Creator: Washington, April M.
System: The UNT Digital Library
[Art Smart article, April 9, 1995] (open access)

[Art Smart article, April 9, 1995]

An article from the Fort Worth Star-Telegram written by Clara Herrera. The article covers Brandon Lewis and other students in art classes and the logistics behind what courses are available to them.
Date: April 9, 1995
Creator: Herrera, Clara G.
System: The UNT Digital Library
Spectroscopy and decay kinetics of Pr{sup 3+}-doped chloride crystals for 1300-nm optical amplifiers (open access)

Spectroscopy and decay kinetics of Pr{sup 3+}-doped chloride crystals for 1300-nm optical amplifiers

Several Pr{sup 3+}-doped chloride crystals have been tested spectroscopically for suitability as 1300-nm optical amplifiers operating on the {sup 1}G{sub 4} - {sup 3}H{sub 5} transition. {sup 1}G{sub 4} lifetimes are much longer than in fluoride hosts, ranging up to 1300 {mu}sec and suggesting a near-unity luminescence quantum yield. Emission spectra are typically broad (FWHM {approximately} 70 nm) and include the 1310-nm zero-dispersion wavelength of standard telecommunications fiber.
Date: March 9, 1995
Creator: Page, R.H.; Schaffers, K.I. & Wilke, G.D.
System: The UNT Digital Library
Capacitive deionization of water: An innovative new process (open access)

Capacitive deionization of water: An innovative new process

The capacitive deionization of water with a stack of carbon aerogel electrodes has been successfully demonstrated for the first time. Unlike ion exchange, one of the more conventional deionization processes, no chemicals were required for regeneration of the system. Electricity was used instead. Water with various anions and cations was pumped through the electrochemical cell. After polarization, ions were electrostatically removed from the water and held in the electric double layers formed at electrode surfaces. The water leaving the cell was purified, as desired.
Date: January 9, 1995
Creator: Farmer, J.; Fix, D. & Mack, G.
System: The UNT Digital Library
Feasibility of organo-beryllium target mandrels using organo-germanium PECVD as a surrogate (open access)

Feasibility of organo-beryllium target mandrels using organo-germanium PECVD as a surrogate

Inertial Confinement Fusion capsules incorporating beryllium are becoming attractive for use in implosion experiments designed for modest energy gain. This paper explores the feasibility of chemical vapor deposition of organo-beryllium precursors to form coating materials of interest as ablators and fuel containers. Experiments were performed in a surrogate chemical system utilizing tetramethylgermane as the organometallic precursor. Coatings with up to 60 mole percent germanium were obtained. These coatings compare favorably with those previously reported in the literature and provide increasing confidence that a similar deposition process with an organo-beryllium precursor would be successful.
Date: March 9, 1995
Creator: Brusasco, R.M.; Dittrich, T. & Cook, R.C.
System: The UNT Digital Library
Model-based internal wave processing (open access)

Model-based internal wave processing

A model-based approach is proposed to solve the oceanic internal wave signal processing problem that is based on state-space representations of the normal-mode vertical velocity and plane wave horizontal velocity propagation models. It is shown that these representations can be utilized to spatially propagate the modal (dept) vertical velocity functions given the basic parameters (wave numbers, Brunt-Vaisala frequency profile etc.) developed from the solution of the associated boundary value problem as well as the horizontal velocity components. Based on this framework, investigations are made of model-based solutions to the signal enhancement problem for internal waves.
Date: June 9, 1995
Creator: Candy, J. V. & Chambers, D. H.
System: The UNT Digital Library
Nonlinear image filtering within IDP++ (open access)

Nonlinear image filtering within IDP++

IDP++, image and data processing in C++, is a set of a signal processing libraries written in C++. It is a multi-dimension (up to four dimensions), multi-data type (implemented through templates) signal processing extension to C++. IDP++ takes advantage of the object-oriented compiler technology to provide ``information hiding.`` Users need only know C, not C++. Signals or data sets are treated like any other variable with a defined set of operators and functions. We here some examples of the nonlinear filter library within IDP++. Specifically, the results of MIN, MAX median, {alpha}-trimmed mean, and edge-trimmed mean filters as applied to a real aperture radar (RR) and synthetic aperture radar (SAR) data set.
Date: February 9, 1995
Creator: Lehman, S.K.; Wieting, M.G. & Brase, J.M.
System: The UNT Digital Library
Properties of a new average power Nd-doped phosphate laser glass (open access)

Properties of a new average power Nd-doped phosphate laser glass

The Nd-doped phosphate laser glass described herein can withstand 2.3 times greater thermal loading without fracture, compared to APG-1 (commercially-available average-power glass from Schott Glass Technologies). The enhanced thermal loading capability is established on the basis of the intrinsic thermomechanical properties and by direct thermally-induced fracture experiments using Ar-ion laser heating of the samples. This Nd-doped phosphate glass (referred to as APG-t) is found to be characterized by a 29% lower gain cross section and a 25% longer low-concentration emission lifetime.
Date: March 9, 1995
Creator: Payne, S. A.; Marshall, C. D.; Bayramian, A. J.; Wilke, G. D. & Hayden, J. S.
System: The UNT Digital Library
Low efficiency gratings for 3rd harmonic diagnostics applications (open access)

Low efficiency gratings for 3rd harmonic diagnostics applications

The baseline design of the National Ignition Facility (NIF) calls for sampling gratings to provide third-harmonic energy diagnostics in the highly constrained area of the target chamber. These 40 {times} 4O cm transmission gratings are to diffract at (order +1) nominally 0.3% of the incident 351 run light at a small angle on to a focusing mirror and into a calorimeter. The design calls for a plane grating of 500 lines/mm, and approximately 30 run deep, etched into a fused silica focusing lens and subsequently overcoated with a solgel anti reflective coating. Gratings of similar aperture and feature size have been produced for other applications by ion etching processes, but, in an effort to reduce substantially the cost of such optics, we are studying the feasibility of making these gratings by wet chemical etching techniques. Experimentation with high-quality fused silica substrates on 5 and 15 cm. scale has led to a wet etching process which can meet the design goals and which offers no significant scaleup barriers to full sized optics. The grating is produced by holographic exposure and a series of processing steps using only a photoresist mask and a final hydrofluoric acid etch. Gratings on 15 cm diameter …
Date: August 9, 1995
Creator: Britten, J. A.; Boyd, R. D.; Perry, M. D.; Shore, B. W. & Thomas, I. M.
System: The UNT Digital Library
Continuous contour phase plates for tailoring the focal plane irradiance profile (open access)

Continuous contour phase plates for tailoring the focal plane irradiance profile

We present fully continuous phase screens for producing super-Gaussian focal-plane irradiance profiles. Such phase screens are constructed with the assumption of either circular symmetric near-field and far-field profiles or a separable phase screen in Cartesian co-ordinates. In each case, the phase screen is only a few waves deep. Under illumination by coherent light, such phase screens produce high order super-Gaussian profiles in the focal plane with high energy content effects of beam aberrations on the focal profiles and their energy content are also discussed.
Date: August 9, 1995
Creator: Dixit, S. N.; Rushford, M. C.; Thomas, I. M. & Perry, M. D.
System: The UNT Digital Library
Effect of ELMs on the SOL plasma in DIII-D (open access)

Effect of ELMs on the SOL plasma in DIII-D

We have studied the evolution of the edge plasma in VH-mode discharges in DIII-D as the discharge evolves from the ELM-free H-mode phase through the VH-mode phase to the final ELMing H-mode phase, by following the changes in the radial profiles of the density and temperature, in the core plasma near the separatrix and in the scrape-off-layer (SOL) plasma outside the separatrix. The electron density and temperature profiles in the SOL do not show any significant difference between the ELM-free H-mode and VH-mode phases. In the ELMing phase, the, density profile broadens during an ELM, forming a high density (n{sub e} > 1 x 10{sup 19}/m{sup 3}) plateau that extends out into the SOL to the limit of the measurement. This density plateau persists between the ELMs, although the density in the SOL does relax somewhat between the ELMs, with a characteristic time that can be larger than ten milliseconds, much longer than the sonic particle flow time to the divertor plates. The time average density scale length measured at the separatrix increases by about a factor of two after the ELMs begin. This density scale length increases with the ELM background, as measured by the photo-diodes nearest to, but …
Date: May 9, 1995
Creator: Jong, R. A.; Porter, G. D. & Groebner, R. J.
System: The UNT Digital Library
Design of a mid-IR immersion echelle grating spectrograph for remote sensing (open access)

Design of a mid-IR immersion echelle grating spectrograph for remote sensing

We describe the design of a silicon immersion grating spectrograph for the remote detection of chemicals in the atmosphere. The instrument is designed to operate in the two atmospheric windows from 2.3 to 2.5 and 2.8 and 4.2 microns at a resolution of 0.1 cm{sup {minus}1}. This is achieved by cross dispersing a high order silicon immersion echelle (13.5 grooves/mm) and a first order concave grating operating in a reflective configuration to generate a two-dimensional spectrum in the image plane with diffraction limited performance.
Date: May 9, 1995
Creator: Thomas, N.L.; Lewis, I.T. & Stevens, C.G.
System: The UNT Digital Library
Yb{sup 3+}:BaCaBO{sub 3}F: A potential new self-frequency-doubling laser material (open access)

Yb{sup 3+}:BaCaBO{sub 3}F: A potential new self-frequency-doubling laser material

Yb:BaCaBO{sub 3}F (Yb:BCBF) has been investigated as a new laser crystal with potential for self-frequency-doubling. An YB:BCBF laser has been pumped at 912 mm, and a measured slope efficiency of 38% has been obtained for the fundamental laser output at 1034 nm. Single crystal powders of BCBF have been compared with K*P for a relative measure of the second harmonic generating potential, yielding d{sub eff}[BCBF]= (0-66)d{sub eff}[K*P]. The growth, spectroscopy, laser performance, and linear and nonlinear optical properties of YB:BCBF are reported here.
Date: March 9, 1995
Creator: Schaffers, K. I.; DeLoach, L. D.; Ebbers, C. A. & Payne, S. A.
System: The UNT Digital Library
Legal aspects of national implementation of the Chemical Weapons Convention national authority provisions. Workshop I: The National Authority (open access)

Legal aspects of national implementation of the Chemical Weapons Convention national authority provisions. Workshop I: The National Authority

This seminar is an excellent opportunity for all attendees to learn from each other about how the Chemical Weapons Convention (CWC) can become a foundation of arms control in Africa and around the world. The author discusses legal aspects of implementing the CWC`s national authority provisions. These implementing measures are universal, applying not only to the few States Parties that will declare and destroy chemical weapons, but also to the many States Parties that have never had a chemical weapons programme. This new need for national measures to implement multilateral arms control agreements has generated unease due to a perception that implementation may be burdensome and at odds with national law. In 1993, concerns arose that the complexity of integrating the treaty with national law would cause each nation to effectuate the Convention without regard to what other nations were doing, thereby engendering significant disparities in implementation steps among States Parties. As a result, the author prepared the Manual for National Implementation of the Chemical Weapons Convention late last year and presented it to each national delegation at the December 1993 meeting of the Preparatory Commission in The Hague. Here the author discusses progress among several States in actually developing …
Date: May 9, 1995
Creator: Tanzman, E. A. & Kellman, B.
System: The UNT Digital Library
Segmentation strategies for the irradiated and tritium contaminated PPPL TFTR (open access)

Segmentation strategies for the irradiated and tritium contaminated PPPL TFTR

The Tokamak Fusion Test Reactor (TFTR) at Princeton Plasma Physics Laboratory is scheduled to complete its final experiments in the Fall of 1995. As a result, the TFTR will be activated and tritium contaminated. After the experiments are complete, the TFTR will undergo Shutdown and Removal (S and R). The space vacated by the TFTR will be used for a new test reactor, the Tokamak Physics Experiment (TPX). Remote methods may be required to remove components and to segment the Vacuum Vessel. The TFTR has been studied to determine alternatives for the segmentation of the Vacuum Vessel from the inside (In-Vessel). The methodology to determine suitable strategies to segment the Vacuum Vessel from In-Vessel included several areas of concentration. These areas were segmentation locations, cutting/removal technologies, pros and cons, and cutting/removal technology delivery systems. The segmentation locations for easiest implementation and minimal steps in cutting and removal have been identified. Each of these will also achieve the baseline for packaging and shipment. The methods for cutting and removal of components were determined. In addition, the delivery systems were conceptualized.
Date: February 9, 1995
Creator: Walton, G. R.; Litka, T. J. & Spampinato, P. T.
System: The UNT Digital Library
Initial results from the Lick Observatory laser guide star adaptive optics system (open access)

Initial results from the Lick Observatory laser guide star adaptive optics system

We present initial results from the sodium-layer laser guide star adaptive optics system developed for the 3-m Shane telescope at Lick Observatory.
Date: June 9, 1995
Creator: Olivier, S. S.; An, Jong & Avicola, K.
System: The UNT Digital Library
A neutron method for NDA analysis in the SAPPHIRE Project (open access)

A neutron method for NDA analysis in the SAPPHIRE Project

The implementation of Project SAPPHIRE, the top secret mission to the Republic of Kazakhstan to recover weapons grade nuclear materials, consisted of four major elements: (1) the re-packing of fissile material from Kazakh containers into suitable US containers; (2) nondestructive analyses (NDA) to quantify the U-235 content of each container for Nuclear Criticality Safety and compliance purposes; (3) the packaging of the fissile material containers into 6M/2R drums, which are internationally approved for shipping fissile material; and (4) the shipping or transport of the recovered fissile material to the United States. This paper discusses the development and application of a passive neutron counting technique used in the NDA phase of SAPPHIRE operations to analyze uranium/beryllium (U/Be) alloys and compounds for U-235 content.
Date: January 9, 1995
Creator: Lewis, K. D.
System: The UNT Digital Library
Bench- and pilot-scale thermal desorption treatability studies on pesticide-contaminated soils from Rocky Mountain Arsenal (open access)

Bench- and pilot-scale thermal desorption treatability studies on pesticide-contaminated soils from Rocky Mountain Arsenal

Thermal desorption is being considered as a potential remediation technology for pesticide-contaminated soils at the Rocky Mountain Arsenal (RMA) in Denver, Colorado. From 1988 through 1992, numerous laboratory- and bench-scale indirect-heated thermal desorption (IHTD) treatability studies have been performed on various soil medium groups from the arsenal. RMA has contracted Argonne National Laboratory to conduct a pilot-scale direct-fired thermal desorption (DFTD) treatability study on pesticide-contaminated RMA soil. The purpose of this treatability study is to evaluate the overall effectiveness of the DFTD technology on contaminated RMA soils and to provide data upon which future conceptual design assumptions and cost estimates for a full-scale system can be made. The equipment used in the DFTD treatability study is of large enough scale to provide good full-scale design parameters and operating conditions. The study will also provide valuable-emissions and materials-handling data. Specifically this program will determine if DFTD can achieve reductions in soil contamination below the RMA preliminary remediation goals (PRGs), define system operating conditions for achieving the PRGs, and determine the fate of arsenic and other hazardous metals at these operating conditions. This paper intends to compare existing data from a bench-scale IHTD treatability study using equipment operated in the batch mode …
Date: March 9, 1995
Creator: Swanstrom, C.P. & Besmer, M.
System: The UNT Digital Library
Legal aspects of national implementation of the chemical weapons convention confidential provisions (open access)

Legal aspects of national implementation of the chemical weapons convention confidential provisions

Today, I shall discuss legal aspects of implementing the Chemical Weapons Convention`s (CORK) confidentiality provisions. These implementing measures are universal, applying not only to the few States Parties that will declare and destroy chemical weapons, but also to the many States Parties that have never had a chemical weapons program. Progress is reported in actually developing implementing measures for the cork`s confidentiality requirements from Australia, Germany, Norway, South Africa, and Sweden.
Date: May 9, 1995
Creator: Tanzman, E.A. & Kellman, B.
System: The UNT Digital Library
The advantages of including professionals from different fields of study in the solution of today`s water-related problems (open access)

The advantages of including professionals from different fields of study in the solution of today`s water-related problems

This report presents the details of a meeting of the American Society of Civil Engineers pertaining to water resources and quality. This report suggests an interdisciplinary approach to solving today`s problems dealing with water resources.
Date: May 9, 1995
Creator: Renshaw, A.
System: The UNT Digital Library
Discrete-fracture modeling of thermal-hydrological processes at Yucca Mountain and the LLNL G-Tunnel heater test (open access)

Discrete-fracture modeling of thermal-hydrological processes at Yucca Mountain and the LLNL G-Tunnel heater test

An in situ heater test was performed at G-Tunnel, Nevada Nuclear Test Site, to investigate the thermal-hydrological response of unsaturated, fractured volcanic tuff under conditions similar to those at Yucca Mountain. The NUFT flow and transport code was used to model the test using discrete-fracture and equivalent-continuum approaches. Nonequilibrium fracture flow and thermal buoyant gas-phase convection were found to be the likely causes for observed lack of condensate imbibition into the matrix. The potential repository at Yucca Mountain was also modeled. Disequilibrium fracture flow is predicted to occur for less than a hundred years after emplacement followed by a period of fracture-matrix equilibrium, during which the equivalent-continuum and discrete-fracture models give almost identical results.
Date: November 9, 1995
Creator: Nitao, J. J. & Buscheck, T. A.
System: The UNT Digital Library
Generation of Pseudotachylites in Shock Experiments: Implications for Impact Cratering Products and Processes (open access)

Generation of Pseudotachylites in Shock Experiments: Implications for Impact Cratering Products and Processes

Meteorite impacts produce enormous pressure and strain in rocks. While the role of pressure on the formation of shock metamorphic features has been well studied, the role of strain and strain rate has not been fully appreciated. We shock loaded single-crystal quartz in Al capsules up to 56 GPa using a novel capsule design that allows for significant strain of the sample but 100% recovery of material. We have made features analogous to type A pseudotachylites at pressures of 42--56 GPa. These pseudotachylites contain Al, Si and minor Al{sub 2}O{sub 3} in a matrix of SiO{sub 2} class and cut the sample along radial and concentric fractures. Our results suggest that strain heating is an important energy sink in the formation of large impact craters.
Date: August 9, 1995
Creator: Fiske, P. S.; Nellis, W. J.; Lorenzana, H.; Lipp, M.; Kikuchi, M. & Syono, Y.
System: The UNT Digital Library
Analysis of distributed cooled high power millimeter wave windows (open access)

Analysis of distributed cooled high power millimeter wave windows

The sectional high-frequency (100--170 GHz) distributed cooled window has been investigated both electromagnetically and thermally previously using computational electromagnetics (EM) and thermal codes. Recent data describes the relationship to some experimental data for the window. Results are presented for time domain CW EM analyses and CW thermal and stress calculations.
Date: September 9, 1995
Creator: Nelson, S. D.; Caplan, M. & Reitter, T. A.
System: The UNT Digital Library
Experimental characterization of high-brightness electron photoinjector (open access)

Experimental characterization of high-brightness electron photoinjector

Operational experience of the emittance compensated photoinjector at the Brookhaven Accelerator Test Facility (ATF) is presented in this paper. The photoinjector has demonstrated the stability and reliability required for UV and X-ray FEL applications. The RF gun has been routinely running at more than 100 MV/m peak acceleration field; the laser system of the photoinjector has achieved 2% peak to peak energy stability, 0.5% point stability and better than 2 ps timing jitter. The highest measured quantum efficiency of the Cu cathode is 0.05%. The electron beam bunch length was measured to be 10 ps using a linac RF phase scan. The normalized rms emittance for a 0.5 nC charge was measured, to be from 1 to 2 mm-mrad, which agrees with PARMELA simulations.
Date: October 9, 1995
Creator: Wang, X. J.; Babzien, M.; Batchelor, K.; Ben-Zvi, Ilan; Pogorelsky, R. M. I.; Qui, X. et al.
System: The UNT Digital Library