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Defense Acquisitions: Plans Need to Allow Enough Time to Demonstrate Capability of First Littoral Combat Ships (open access)

Defense Acquisitions: Plans Need to Allow Enough Time to Demonstrate Capability of First Littoral Combat Ships

A letter report issued by the Government Accountability Office with an abstract that begins "To conduct operations in littorals--shallow coastal waters--the Navy plans to build a new class of surface warship: the Littoral Combat Ship (LCS). LCS is being designed to accomplish its missions through systems operating at a distance from the ship, such as helicopters and unmanned vehicles, and that will be contained in interchangeable mission packages. The Navy is using an accelerated approach to buy the LCS, building the ships in "flights." Flight 0, consisting of four ships, will provide limited capability and test the LCS concept. The schedule allows 12 months between the delivery of the first Flight 0 ship and the start of detailed design and construction for Flight 1 ships. Estimated procurement cost of the Flight 0 ships is $1.5 billion. The Congress directed GAO to review the LCS program. This report assesses the analytical basis of LCS requirements; the Navy's progress in defining the concept of operations; the technical maturity of the mission packages; and the basis of recurring costs for LCS."
Date: March 1, 2005
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Financial Audit: American Battle Monuments Commission's Financial Statements for Fiscal Year 2004 and 2003 (open access)

Financial Audit: American Battle Monuments Commission's Financial Statements for Fiscal Year 2004 and 2003

A letter report issued by the Government Accountability Office with an abstract that begins "In accordance with 36 U.S.C. 2103, GAO is responsible for conducting audits of the agencywide financial statements of the American Battle Monuments Commission (the Commission). GAO audited the financial statements of the Commission for the fiscal years ended September 30, 2004, and 2003. The audits were done to determine whether, in all material respects, (1) the Commission's financial statements were reliable, and (2) Commission management maintained effective internal control over financial reporting and compliance with laws and regulations. Also, we tested Commission management's compliance with selected laws and regulations. The American Battle Monuments Commission was created in 1923 to commemorate the sacrifices and achievements of U.S. Armed Forces where they have served overseas since April 6, 1917, and locations within the United States as directed by Congress. The Commission designs, administers, operates, and maintains 24 American military cemeteries on foreign soil and 25 federal memorials, monuments, and markers, 22 of which are on foreign soil. The Commission was also responsible for designing and constructing the national World War II Memorial on the Capitol Mall in Washington, D.C., and for maintaining 4 nonfederal memorials with funds provided …
Date: March 1, 2005
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Digests of Appropriations Law Decisions and Opinions (October 2003 to December 2004) (open access)

Digests of Appropriations Law Decisions and Opinions (October 2003 to December 2004)

Other written product issued by the Government Accountability Office with an abstract that begins "GAO published digests of appropriations law decisions and opinions for the months of October 2003 through December 2004."
Date: March 1, 2005
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library
Chemical crosslinking and mass spectrometry studies of the structure and dynamics of membrane proteins and receptors. (open access)

Chemical crosslinking and mass spectrometry studies of the structure and dynamics of membrane proteins and receptors.

Membrane proteins make up a diverse and important subset of proteins for which structural information is limited. In this study, chemical cross-linking and mass spectrometry were used to explore the structure of the G-protein-coupled photoreceptor bovine rhodopsin in the dark-state conformation. All experiments were performed in rod outer segment membranes using amino acid 'handles' in the native protein sequence and thus minimizing perturbations to the native protein structure. Cysteine and lysine residues were covalently cross-linked using commercially available reagents with a range of linker arm lengths. Following chemical digestion of cross-linked protein, cross-linked peptides were identified by accurate mass measurement using liquid chromatography-fourier transform mass spectrometry and an automated data analysis pipeline. Assignments were confirmed and, if necessary, resolved, by tandem MS. The relative reactivity of lysine residues participating in cross-links was evaluated by labeling with NHS-esters. A distinct pattern of cross-link formation within the C-terminal domain, and between loop I and the C-terminal domain, emerged. Theoretical distances based on cross-linking were compared to inter-atomic distances determined from the energy-minimized X-ray crystal structure and Monte Carlo conformational search procedures. In general, the observed cross-links can be explained by re-positioning participating side-chains without significantly altering backbone structure. One exception, between C3 …
Date: March 1, 2005
Creator: Haskins, William E.; Leavell, Michael D.; Lane, Pamela; Jacobsen, Richard B.; Hong, Joohee; Ayson, Marites J. et al.
Object Type: Report
System: The UNT Digital Library
Toxin studies using an integrated biophysical and structural biology approach. (open access)

Toxin studies using an integrated biophysical and structural biology approach.

Clostridial neurotoxins, such as botulinum and tetanus, are generally thought to invade neural cells through a process of high affinity binding mediated by gangliosides, internalization via endosome formation, and subsequent membrane penetration of the catalytic domain activated by a pH drop in the endosome. This surface recognition and internalization process is still not well understood with regard to what specific membrane features the toxins target, the intermolecular interactions between bound toxins, and the molecular conformational changes that occur as a result of pH lowering. In an effort to elucidate the mechanism of tetanus toxin binding and permeation through the membrane a simple yet representative model was developed that consisted of the ganglioside G{sub tlb} incorporated in a bilayer of cholesterol and DPPC (dipalmitoylphosphatidyl choline). The bilayers were stable over time yet sensitive towards the binding and activity of whole toxin. A liposome leakage study at constant pH as well as with a pH gradient, to mimic the processes of the endosome, was used to elucidate the effect of pH on the toxin's membrane binding and permeation capability. Topographic imaging of the membrane surface, via in situ tapping mode AFM, provided nanoscale characterization of the toxin's binding location and pore formation …
Date: March 1, 2005
Creator: Last, Julie A.; Schroeder, Anne E.; Slade, Andrea Lynn; Sasaki, Darryl Yoshio; Yip, Christopher M. (University of Toronto, Toronto, Ontario, Canada) & Schoeniger, Joseph S. (Sandia National Laboratories, Livermore, CA)
Object Type: Report
System: The UNT Digital Library
Parameter identification for the electrical modeling of semiconductor bridges. (open access)

Parameter identification for the electrical modeling of semiconductor bridges.

Semiconductor bridges (SCBs) are commonly used as initiators for explosive and pyrotechnic devices. Their advantages include reduced voltage and energy requirements and exceptional safety features. Moreover, the design of systems which implement SCBs can be expedited using electrical simulation software. Successful use of this software requires that certain parameters be correctly chosen. In this paper, we explain how these parameters can be identified using optimization. We describe the problem focusing on the application of a direct optimization method for its solution, and present some numerical results.
Date: March 1, 2005
Creator: Gray, Genetha Anne
Object Type: Report
System: The UNT Digital Library
Magnetophoretic bead trapping in a high-flowrate biological detection system. (open access)

Magnetophoretic bead trapping in a high-flowrate biological detection system.

This report contains the summary of the 'Magnetophoretic Bead Trapping in a High-Flowrate Biological Detection System' LDRD project 74795. The objective of this project is to develop a novel biodetection system for high-throughput sample analysis. The chief application of this system is in detection of very low concentrations of target molecules from a complex liquid solution containing many different constituents--some of which may interfere with identification of the target molecule. The system is also designed to handle air sampling by using an aerosol system (for instance a WESP - Wet Electro-Static Precipitator, or an impact spray system) to get air sample constituents into the liquid volume. The system described herein automatically takes the raw liquid sample, whether air converted or initially liquid matrix, and mixes in magnetic detector beads that capture the targets of interest and then performs the sample cleanup function, allowing increased sensitivity and eliminating most false positives and false negatives at a downstream detector. The surfaces of the beads can be functionalized in a variety of ways in order to maximize the number of targets to be captured and concentrated. Bacteria and viruses are captured using antibodies to surface proteins on bacterial cell walls or viral particle …
Date: March 1, 2005
Creator: Galambos, Paul C.; Hopkins, Matthew Morgan; Rahimian, Kamayar; Martin, James Ellis; Anderson, G. Ronald; Clem, Paul Gilbert et al.
Object Type: Report
System: The UNT Digital Library
Microsystem strategies for sample preparation in biological detection. (open access)

Microsystem strategies for sample preparation in biological detection.

The objective of this LDRD was to develop microdevice strategies for dealing with samples to be examined in biological detection systems. This includes three sub-components: namely, microdevice fabrication, sample delivery to the microdevice, and sample processing within the microdevice. The first component of this work focused on utilizing Sandia's surface micromachining technology to fabricate small volume (nanoliter) fluidic systems for processing small quantities of biological samples. The next component was to develop interfaces for the surface-micromachined silicon devices. We partnered with Micronics, a commercial company, to produce fluidic manifolds for sample delivery to our silicon devices. Pressure testing was completed to examine the strength of the bond between the pressure-sensitive adhesive layer and the silicon chip. We are also pursuing several other methods, both in house and external, to develop polymer-based fluidic manifolds for packaging silicon-based microfluidic devices. The second component, sample processing, is divided into two sub-tasks: cell collection and cell lysis. Cell collection was achieved using dielectrophoresis, which employs AC fields to collect cells at energized microelectrodes, while rejecting non-cellular particles. Both live and dead Staph. aureus bacteria have been collected using RF frequency dielectrophoresis. Bacteria have been separated from polystyrene microspheres using frequency-shifting dielectrophoresis. Computational modeling was …
Date: March 1, 2005
Creator: James, Conrad D.; Galambos, Paul C.; Bennett, Dawn Jonita (University of Maryland Baltimore County, Baltimore, MD); Manginell, Monica; Okandan, Murat; Acrivos, Andreas (The City College of New York, NY) et al.
Object Type: Report
System: The UNT Digital Library
An improved statistical model for linear antenna input impedance in an electrically large cavity. (open access)

An improved statistical model for linear antenna input impedance in an electrically large cavity.

This report presents a modification of a previous model for the statistical distribution of linear antenna impedance. With this modification a simple formula is determined which yields accurate results for all ratios of modal spectral width to spacing. It is shown that the reactance formula approaches the known unit Lorentzian in the lossless limit.
Date: March 1, 2005
Creator: Johnson, William Arthur; Warne, Larry Kevin; Jorgenson, Roy Eberhardt & Lee, Kelvin S. H. (ITT Industries/AES, Los Angeles, CA)
Object Type: Report
System: The UNT Digital Library
Visualization of Instrumental Verification Information Details (VIVID) : code development, description, and usage. (open access)

Visualization of Instrumental Verification Information Details (VIVID) : code development, description, and usage.

The formulation, implementation and usage of a numerical solution verification code is described. This code uses the Richardson extrapolation procedure to estimate the order of accuracy and error of a computational program solution. It evaluates multiple solutions performed in numerical grid convergence studies to verify a numerical algorithm implementation. Analyses are performed on both structured and unstructured grid codes. Finite volume and finite element discretization programs are examined. Two and three-dimensional solutions are evaluated. Steady state and transient solution analysis capabilities are present in the verification code. Multiple input data bases are accepted. Benchmark options are included to allow for minimal solution validation capability as well as verification.
Date: March 1, 2005
Creator: Roy, Christopher John; Bainbridge, Bruce L.; Potter, Donald L.; Blottner, Frederick G. & Black, Amalia Rebecca
Object Type: Report
System: The UNT Digital Library
EMPHASIS/Nevada CABANA : user guide : version 1.0. (open access)

EMPHASIS/Nevada CABANA : user guide : version 1.0.

The CABle ANAlysis (CABANA) portion of the EMPHASIS suite is designed specifically for the simulation of cable SGEMP. The code can be used to evaluate the response of a specific cable design to threat or to compare and minimize the relative response of difference designs. This document provides user-specific information to facilitate the application of the code to cables of interest.
Date: March 1, 2005
Creator: Turner, C. David
Object Type: Report
System: The UNT Digital Library
Coral Reef Genomics: Developing tools for functional genomics ofcoral symbiosis (open access)

Coral Reef Genomics: Developing tools for functional genomics ofcoral symbiosis

Symbioses between cnidarians and dinoflagellates in the genus Symbiodinium are widespread in the marine environment. The importance of this symbiosis to reef-building corals and reef nutrient and carbon cycles is well documented, but little is known about the mechanisms by which the partners establish and regulate the symbiosis. Because the dinoflagellate symbionts live inside the cells of their host coral, the interactions between the partners occur on cellular and molecular levels, as each partner alters the expression of genes and proteins to facilitate the partnership. These interactions can examined using high-throughput techniques that allow thousands of genes to be examined simultaneously. We are developing the groundwork so that we can use DNA microarray profiling to identify genes involved in the Montastraea faveolata and Acropora palmata symbioses. Here we report results from the initial steps in this microarray initiative, that is, the construction of cDNA libraries from 4 of 16 target stages, sequencing of 3450 cDNA clones to generate Expressed Sequenced Tags (ESTs), and annotation of the ESTs to identify candidate genes to include in the microarrays. An understanding of how the coral-dinoflagellate symbiosis is regulated will have implications for atmospheric and ocean sciences, conservation biology, the study and diagnosis of …
Date: March 1, 2005
Creator: Schwarz, Jodi; Brokstein, Peter; Manohar, Chitra; Coffroth, MaryAlice; Szmant, Alina & Medina, Monica
Object Type: Article
System: The UNT Digital Library
Users manual for CAFE-3D : a computational fluid dynamics fire code. (open access)

Users manual for CAFE-3D : a computational fluid dynamics fire code.

The Container Analysis Fire Environment (CAFE) computer code has been developed to model all relevant fire physics for predicting the thermal response of massive objects engulfed in large fires. It provides realistic fire thermal boundary conditions for use in design of radioactive material packages and in risk-based transportation studies. The CAFE code can be coupled to commercial finite-element codes such as MSC PATRAN/THERMAL and ANSYS. This coupled system of codes can be used to determine the internal thermal response of finite element models of packages to a range of fire environments. This document is a user manual describing how to use the three-dimensional version of CAFE, as well as a description of CAFE input and output parameters. Since this is a user manual, only a brief theoretical description of the equations and physical models is included.
Date: March 1, 2005
Creator: Khalil, Imane; Lopez, Carlos & Suo-Anttila, Ahti Jorma (Alion Science and Technology, Albuquerque, NM)
Object Type: Report
System: The UNT Digital Library
Use of Coal Drying to Reduce Water Consumed in Pulverized Coal Power Plants Quarterly Report: October-December 2004 (open access)

Use of Coal Drying to Reduce Water Consumed in Pulverized Coal Power Plants Quarterly Report: October-December 2004

This is the eighth Quarterly Report for this project. The background and technical justification for the project are described, including potential benefits of reducing fuel moisture, prior to firing in a pulverized coal boiler. Analyses were performed to determine the effects of coal product moisture on unit performance. Results are given showing how the coal product moisture level affects parameters such as boiler efficiency, power required to drive the fluidizing air fan, other station service power needed for fans and pulverizers, net unit heat rate, thermal energy rejected by the cooling tower, and stack emissions.
Date: March 1, 2005
Creator: Sarunac, Nenad & Levy, Edward
Object Type: Report
System: The UNT Digital Library
Glider communications and controls for the sea sentry mission. (open access)

Glider communications and controls for the sea sentry mission.

This report describes a system level study on the use of a swarm of sea gliders to detect, confirm and kill littoral submarine threats. The report begins with a description of the problem and derives the probability of detecting a constant speed threat without networking. It was concluded that glider motion does little to improve this probability unless the speed of a glider is greater than the speed of the threat. Therefore, before detection, the optimal character for a swarm of gliders is simply to lie in wait for the detection of a threat. The report proceeds by describing the effect of noise on the localization of a threat once initial detection is achieved. This noise is estimated as a function of threat location relative to the glider and is temporally reduced through the use of an information or Kalman filtering. In the next section, the swarm probability of confirming and killing a threat is formulated. Results are compared to a collection of stationary sensors. These results show that once a glider has the ability to move faster than the threat, the performance of the swarm is equal to the performance of a stationary swarm of gliders with confirmation and …
Date: March 1, 2005
Creator: Feddema, John Todd & Dohner, Jeffrey Lynn
Object Type: Report
System: The UNT Digital Library
Innovative applications of energy storage in a restructured electricity marketplace : Phase III final report : a study for the DOE Energy Storage Systems Program. (open access)

Innovative applications of energy storage in a restructured electricity marketplace : Phase III final report : a study for the DOE Energy Storage Systems Program.

This report describes Phase III of a project entitled Innovative Applications of Energy Storage in a Restructured Electricity Marketplace. For this study, the authors assumed that it is feasible to operate an energy storage plant simultaneously for two primary applications: (1) energy arbitrage, i.e., buy-low-sell-high, and (2) to reduce peak loads in utility ''hot spots'' such that the utility can defer their need to upgrade transmission and distribution (T&D) equipment. The benefits from the arbitrage plus T&D deferral applications were estimated for five cases based on the specific requirements of two large utilities operating in the Eastern U.S. A number of parameters were estimated for the storage plant ratings required to serve the combined application: power output (capacity) and energy discharge duration (energy storage). In addition to estimating the various financial expenditures and the value of electricity that could be realized in the marketplace, technical characteristics required for grid-connected distributed energy storage used for capacity deferral were also explored.
Date: March 1, 2005
Creator: Eyer, James M.; Erdman, Bill & Iannucci, Joseph J., Jr.
Object Type: Report
System: The UNT Digital Library
Final report to NASA JSC : thermal abuse performance of MOLI, Panasonic and Sanyo 18650 Li-ion cells. (open access)

Final report to NASA JSC : thermal abuse performance of MOLI, Panasonic and Sanyo 18650 Li-ion cells.

Thermal property measurements of 18650 cells for the Space Shuttle Orbiter Advanced Hydraulic Power System (AHPS, formerly known as EAPU) have been performed. Cells were measured from three commercial manufacturers: E-One MOLI (12 cells), Panasonic (5 cells) and Sanyo (5 cells). Thermal property measurements of the MOLI 18650 cells included measurements of specific heat, self discharge (microcalorimetry), overcharge response and thermal runaway by accelerating rate calorimetry (ARC). The Panasonic and Sanyo cells were measured only for thermal runaway response in the ARC at increasing states of charge (3.8V, 4.0V, 4.2V, 4.3V).
Date: March 1, 2005
Creator: Roth, Emanuel Peter
Object Type: Report
System: The UNT Digital Library
Low-cost inertial measurement unit. (open access)

Low-cost inertial measurement unit.

Sandia National Laboratories performs many expensive tests using inertial measurement units (IMUs)--systems that use accelerometers, gyroscopes, and other sensors to measure flight dynamics in three dimensions. For the purpose of this report, the metrics used to evaluate an IMU are cost, size, performance, resolution, upgradeability and testing. The cost of a precision IMU is very high and can cost hundreds of thousands of dollars. Thus the goals and results of this project are as follows: (1) Examine the data flow in an IMU and determine a generic IMU design. (2) Discuss a high cost IMU implementation and its theoretically achievable results. (3) Discuss design modifications that would save money for suited applications. (4) Design and implement a low cost IMU and discuss its theoretically achievable results. (5) Test the low cost IMU and compare theoretical results with empirical results. (6) Construct a more streamlined printed circuit board design reducing noise, increasing capabilities, and constructing a self-contained unit. Using these results, we can compare a high cost IMU versus a low cost IMU using the metrics from above. Further, we can examine and suggest situations where a low cost IMU could be used instead of a high cost IMU for saving …
Date: March 1, 2005
Creator: Deyle, Travis Jay
Object Type: Report
System: The UNT Digital Library
Diamond-like nanocomposite coatings for LIGA-fabricated nickel alloy parts. (open access)

Diamond-like nanocomposite coatings for LIGA-fabricated nickel alloy parts.

A commercial plasma enhanced chemical vapor deposition (PECVD) technique with planetary substrate rotation was used to apply a thin (200-400 nm thick) conformal diamond-like carbon (DLC) coating (known as a diamond-like nanocomposite (DLN)) on LIGA fabricated Ni-Mn alloy parts. The PECVD technique is known to overcome the drawbacks associated with the line-of-sight nature of physical vapor deposition (PVD) and substrate heating inherent with traditional chemical vapor deposition (CVD). The purpose of the present study is to characterize the coverage, adhesion, and tribological (friction and wear) behavior of DLN coatings applied to planar and sidewall surfaces of small featured LIGA Ni-Mn fabricated parts, e.g. 280 {micro}m thick sidewalls. Friction and wear tests were performed in dry nitrogen, dry air, and air with 50% RH at Hertzian contact pressures ranging from 0.3 to 0.6 GPa. The friction coefficient of bare Ni-Mn alloy was determined to be 0.9. In contrast, low friction coefficients ({approx}0.02 in dry nitrogen and {approx}0.2 in 50% RH air) and minimal amount of wear were exhibited for the DLN coated LIGA Ni-Mn alloy parts and test coupons. This behavior was due to the ability of the coating to transfer to the rubbing counterface providing low interfacial shear at the …
Date: March 1, 2005
Creator: Prasad, Somuri V. & Scharf, Thomas W.
Object Type: Report
System: The UNT Digital Library
Robust hermetic packaging techniques for MEMS integrated microsystems. (open access)

Robust hermetic packaging techniques for MEMS integrated microsystems.

This work is the result of a Sandia National Laboratories LDRD funded fellowship at the University of Michigan. Although, guidance and suggestions were offered by Sandia, the work contained here is primarily the work of Brian H. Stark, and his advisor, Professor Khalil Najafi. Junseok Chae, Andrew Kuo, and their coworkers at the University of Michigan helped to record some of the data. The following is an abstract of their work. We have developed a vacuum packaging technology using a thick nickel film to seal MEMS structures at the wafer level. The package is fabricated in a three-mask process by electroplating a 40 micro-meter thick nickel film over an 8 micro-meter sacrificial photoresist that is removed prior to package sealing. Implementation of electrical feedthroughs in this process requires no planarization. The large release channel enables an 800x800 micro-meter package to be released in less than three hours. Several mechanisms, based upon localized melting and lead/tin solder bumping, for sealing the release channel have been investigated. We have also developed Pirani gauges, integrated with this package, which can be used to establish the hermeticity of the different sealing technologies. They have measured a sealing pressure of approximately 1.5 Torr. Our work …
Date: March 1, 2005
Creator: Chae, Junseok (University of Michigan); Stark, Brian H. (University of Michigan); Kuo, Andrew (University of Michigan); Oliver, Andrew David & Najafi, Khalil (University of Michigan)
Object Type: Report
System: The UNT Digital Library
Microcalibrator system for chemical signature and reagent delivery. (open access)

Microcalibrator system for chemical signature and reagent delivery.

Networked systems of low-cost, small, integrable chemical sensors will enable monitoring of Nonproliferation and Materials Control targets and chemical weapons threats. Sandia-designed prototype chemical sensor systems are undergoing extended field testing supported by DOE and other government agencies. A required surety component will be verification of microanalytical system performance, which can be achieved by providing a programmable source of chemical signature(s) for autonomous calibration of analytical systems. In addition, such a controlled chemical source could be used to dispense microaliquots of derivatization reagents, extending the analysis capability of chemical sensors to a wider range of targets. We have developed a microfabricated system for controlled release of selected compounds (calibrants) into the analytical stream of microsensor systems. To minimize pumping and valve requirements of microfluidic systems, and to avoid degradation issues associated with storage of dilute solutions, we have utilized thermally labile organic salts as solid-phase reservoir materials. Reproducible deposition of tetrapropyl ammonium hydroxide onto arrays of microfabricated heating elements can provide a pair of calibration marker compounds (one fast and one slow-eluting compound) for GC analyses. The use of this microaliquot gas source array for hydrogen generation is currently under further development. The goal of the latter effort will be …
Date: March 1, 2005
Creator: Staton, Alan W.; Simonson, Robert Joseph; Adkins, Douglas Ray; Rawlinson, Kim Scott; Robinson, Alex Lockwood; Hance, Bradley G. et al.
Object Type: Report
System: The UNT Digital Library
Deciphering the genetic regulatory code using an inverse error control coding framework. (open access)

Deciphering the genetic regulatory code using an inverse error control coding framework.

We have found that developing a computational framework for reconstructing error control codes for engineered data and ultimately for deciphering genetic regulatory coding sequences is a challenging and uncharted area that will require advances in computational technology for exact solutions. Although exact solutions are desired, computational approaches that yield plausible solutions would be considered sufficient as a proof of concept to the feasibility of reverse engineering error control codes and the possibility of developing a quantitative model for understanding and engineering genetic regulation. Such evidence would help move the idea of reconstructing error control codes for engineered and biological systems from the high risk high payoff realm into the highly probable high payoff domain. Additionally this work will impact biological sensor development and the ability to model and ultimately develop defense mechanisms against bioagents that can be engineered to cause catastrophic damage. Understanding how biological organisms are able to communicate their genetic message efficiently in the presence of noise can improve our current communication protocols, a continuing research interest. Towards this end, project goals include: (1) Develop parameter estimation methods for n for block codes and for n, k, and m for convolutional codes. Use methods to determine error control …
Date: March 1, 2005
Creator: Rintoul, Mark Daniel; May, Elebeoba Eni; Brown, William Michael; Johnston, Anna Marie & Watson, Jean-Paul
Object Type: Report
System: The UNT Digital Library
Development of an efficient large-aperture high damage-threshold sol-gel diffraction grating. (open access)

Development of an efficient large-aperture high damage-threshold sol-gel diffraction grating.

In order to develop the next generation of high peak intensity lasers, new grating technology providing higher damage thresholds and large apertures is required. The current assumption is that this technical innovation will be multilayer dielectric gratings, wherein the uppermost layer of a thin film mirror is etched to create the desired binary phase grating. A variant of this is explored with the upper grating layer being a lower density gelatin-based volume phase grating in either sol-gel or dichromated gelatin. One key benefit is the elimination of the etching step.
Date: March 1, 2005
Creator: Ashley, Carol S.; Rambo, Patrick K.; Schwarz, Jens; Dunphy, Darren Robert; Branson, Eric D.; Smith, Ian Craig et al.
Object Type: Report
System: The UNT Digital Library
Restart of the chemical preparation process for the fabrication of ZnO varistors for ferroelectric neutron generator power supplies. (open access)

Restart of the chemical preparation process for the fabrication of ZnO varistors for ferroelectric neutron generator power supplies.

To date, all varistors used in ferroelectric neutron generators have been supplied from a single, proprietary source, General Electric Corporate Research and Development (GE CR&D). To protect against the vulnerability of a single source, Sandia initiated a program in the early 1980's to develop a second source for this material. A chemical preparation process for making homogeneous, high purity ZnO-based varistor powder was generated, scaled to production quantities, and transferred to external suppliers. In 1992, the chem-prep varistor program was suspended when it appeared there was sufficient inventory of GE CR&D material to supply ferroelectric neutron generator production for many years. In 1999, neutron generator production schedules increased substantially, resulting in a predicted exhaustion of the existing supply of varistor material within five years. The chem-prep program was restarted in January, 2000. The goals of the program were to (1) duplicate the chem-prep powder synthesis process that had been qualified for WR production, (2) demonstrate sintered billets from the chem-prep powder met requirements, (3) develop a process for rod fabrication and demonstrate that all component specifications could be met, and (4) optimize the process from powder synthesis through component fabrication for full-scale production. The first three of these goals have …
Date: March 1, 2005
Creator: Lockwood, Steven John
Object Type: Report
System: The UNT Digital Library