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493 Matching Results
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UV-Photoassisted Etching of GaN in KOH
The etch rate of GaN under W-assisted photoelectrochemical conditions in KOH solutions is found to be a strong function of illumination intensity, solution molarity, sample bias and material doping level. At low e-h pair generation rates, grain boundaries are selectively etched, while at higher illumination intensities etch rates for unintentionally doped (n - 3x 10^12Gcm-3) GaN are 2 1000 .min-l. The etching is diffusion limited under our conditions with an activation energy of - 0.8kCal.mol-1. The etched surfaces are rough, but retain their stoichiometry. PEC etching is found to selectively reveal grain boundaries in GaN under low light illumination conditions. At high lamp powers the rates increase with sample temperature and the application of bias to the PEC cell, while they go through a maximum with KOH solution molarity. The etching is diffusion-limited, producing rough surface morphologies that are suitable in a limited number of device fabrication steps. The surfaces however appear to remain relatively close to their stoichiometric composition.
Date:
November 12, 1998
Creator:
Abernathy, C.R.; Auh, K.H.; Cho, H.; Donovan, S.M.; Han, J.; Lambers, E.S. et al.
Object Type:
Article
System:
The UNT Digital Library
Investigation of Deep Levels in GaInNas
This paper presents and discusses the first Deep-Level transient spectroscopy (DLTS) data obtained from measurements carried out on both Schottky barriers and homojunction devices of GaInNAs. The effect of N and In doping on the electrical properties of the GaNInAs devices, which results in structural defects and interface states, has been investigated. Moreover, the location and densities of deep levels related to the presence of N, In, and N+In are identified and correlated with the device performance. The data confirmed that the presence of N alone creates a high density of shallow hole traps related to the N atom and structural defects in the device. Doping by In, if present alone, also creates low-density deep traps (related to the In atom and structural defects) and extremely deep interface states. On the other hand, the co-presence of In and N eliminates both the interface states and levels related to structural defects. However, the device still has a high density of the shallow and deep traps that are responsible for the photocurrent loss in the GaNInAs device, together with the possible short diffusion length.
Date:
November 12, 1998
Creator:
Abulfotuh, F.; Balcioglu, A.; Friedman, D.; Geisz, J. & Kurtz, S.
Object Type:
Article
System:
The UNT Digital Library
Effects of Nonlinear Absorption in BK7 and Color Glasses at 355 nm
We have demonstrated a simple experimental technique that can be used to measure the nonlinear absorption coefficients in glasses. We determine BK7, UG1, and UG11 glasses to have linear absorption coefficients of 0.0217 {+-} 10% cm{sup -1}, 1.7 {+-} 10% cm{sup -1}, and 0.82 {+-} 10% cm{sup -1}, respectively, two-photon absorption cross-sections of 0.025 {+-} 20% cm/GW, 0.035 {+-} 20% cm/GW, and 0.047 {+-} 20% cm/GW, respectively, excited-state absorption cross-sections of 8.0 x 10{sup -18} {+-} 20% cm{sup 2}, 2.8 x 10{sup -16} {+-} 20% cm{sup 2}, and 5 x 10{sup -17} {+-} 20% cm{sup 2}, respectively, and solarization coefficients of 8.5 x 10{sup -20} {+-} 20% cm{sup 2}, 2.5 x 10{sup -18} {+-} 20% cm{sup 2}, and 1.3 x 10{sup -19} {+-} 20% cm{sup 2}, respectively. For our application, nonlinear effects in 10-cm of BK7 are small ({le} 2%) for 355-nm fluences < 0.2 J/cm{sup 2} for flat-top pulses. However, nonlinear effects are noticeable for 355-nm fluences at 0.8 J/cm{sup 2}. In particular, we determine a 20% increase in the instantaneous absorption from linear, a solarization rate of 4% per 100 shots, and a 10% temporal droop introduced in the pulse, for 355-nm flat-top pulses at a fluence of …
Date:
November 12, 2003
Creator:
Adams, J. J.; McCarville, T.; Bruere, J.; McElroy, J. & Peterson, J.
Object Type:
Article
System:
The UNT Digital Library
Composition and Bonding in Amorphous Carbon Films Grown by Ion Beam Assisted Deposition: Influence of the Assistance Voltage
Amorphous carbon films have been grown by evaporation of graphite with concurrent Ar+ ions bombardment assistance. The ion energy has been varied between 0-800 V while keeping a constant ion to carbon atom arrival ratio. Film composition and density were determined by ion scattering techniques (RBS and ERDA), indicating a negligible hydrogen content and a density dependence with the assistance voltage. The bonding structure of the films has been studied by Raman and X-ray Absorption Near-Edge (XANES) spectroscopy. Different qualitative effects have been found depending on the ion energy range. For ion energies below 300 eV, there is a densification of the carbon layer due to the increase in the sp3 content. For ion energies above 300 eV sputtering phenomena dominate over densification, and thinner films are found with increasing assistance voltage until no film is grown over 600 V. The films with the highest SP3 content are grown with intermediate energies between 200-300 V.
Date:
November 12, 1998
Creator:
Albella, J. M.; Banks, J. C.; Climent-Font, A.; Doyle, B. L.; Gago, R.; Jimenez, I. et al.
Object Type:
Article
System:
The UNT Digital Library
Final Report - "UCM-Grid Service for User-Centric Monitoring"
The User Centric Monitoring (UCM) project was aimed at developing a toolkit that provides the Virtual Organization (VO) with tools to build systems that serve a rich set of intuitive job and application monitoring information to the VO's scientists so that they can be more productive. The tools help collect and serve the status and error information through a Web interface. The proposed UCM toolkit is composed of a set of library functions, a database schema, and a Web portal that will collect and filter available job monitoring information from various resources and present it to users in a user-centric view rather than and administrative-centric point of view.
Date:
November 12, 2009
Creator:
Alexander, David A.
Object Type:
Report
System:
The UNT Digital Library
Energy storage and power conditioning system for the Shiva laser
An optimal energy delivery system for the world's largest glass laser system has been designed based on computer modeling and operation of laser hardware. Components of the system have been tested on operating lasers at LLL. The Shiva system is now under construction and will be completed in 1977. The energy supply described here will provide cost-effective, reliable power and facilitate the gathering of data in pursuit of controlled thermonuclear reactions. (auth)
Date:
November 12, 1975
Creator:
Allen, G. R.; Gagnon, W. L.; Rupert, P. R. & Trenholme, J. B.
Object Type:
Article
System:
The UNT Digital Library
Examining Technology, Structure and Identity During an Enterprise System Implementation
This paper presents a longitudinal study of an Enterprise System (ES) implementation by critically examining the discursive context in which an ES implementation unfolds. The findings show that users strongly supported the ES in the earlier stage of implementation when the technology was an imaginary phenomenon. However, in later stages, when the technology is in use, user support was not consistent. In this phase the ES produces loss of control and an inability to function as an arbiter of fairness (in allocating resources associated with the system) thereby directly challenging existing professional identities and roles. These outcomes, in turn, generate acts of resistance on the part of workers. Users reach inside the technology and reshape it by devising creative workarounds that produce a sense of reskilling to counter the deskilling produced by the loss of control and power. The analysis also shows that an ES is a complex social phenomenon that is intricately linked to and complicit in shaping organizational structure and identity. In particular this study shows how technology, structure, and identity are in a mutually constitutive relationship.
Date:
November 12, 2008
Creator:
Alvarez, Rosio
Object Type:
Article
System:
The UNT Digital Library
Flexible piping joints for large-scale breeder reactor primary loop applications. Phase I. Technical summary
None
Date:
November 12, 1975
Creator:
Anderson, R. V. & Jaquay, K. R.
Object Type:
Report
System:
The UNT Digital Library
Direct Energy Conversion Fission Reactor, Gaseous Core Reactor with Magnetohydrodynamic (MHD) Generator; Final Report - Part I and Part II
This report focuses on the power conversion cycle and efficiency. The technical issues involving the ionization mechanisms, the power management and distribution and radiation shielding and safety will be discussed in future reports.
Date:
November 12, 2002
Creator:
Anghaie, Samim; Smith, Blair & Knight, Travis
Object Type:
Report
System:
The UNT Digital Library
Effective cleanup at LLNL: innovative technologies and approaches
At the Lawrence Livermore National Laboratory (LLNL) Livermore Site Superfund Site, ground water restoration efforts have been ongoing since 1989. Based on plans committed to by DOE in the Record of Decision (ROD) for the Site in 1992, ground water cleanup was predicted to take 61 years. What began as conventional pump and treat has evolved into an effective Engineered Plume Collapse strategy that employs a well-stocked tool box of remediation technologies, processes, and methodologies. This �tool box� approach has proven effective in solving the vexing problem of restoring the chlorinated volatile organic compound (CVOC) contaminated aquifers beneath the site. The Engineered Plume Collapse strategy has been used to hydraulically control the plumes on the western and southern boundaries of the site, doubled the pounds of CVOC removed from the subsurface compared to predictions in the ROD plans, and �collapsed� offsite plumes. The three major components of the Engineered Plume Collapse strategy are: (1) collection and use of historical and current chemical and hydrogeologic data to accurately identify areas of contamination in the subsurface and guide decisions about on-going remediation needs, (2) design, construction and operation of small, portable, and inexpensive ground water treatment units to implement pump and treat …
Date:
November 12, 1998
Creator:
Angleberger; Brown, M. G.; K. & Lamarre, A.
Object Type:
Article
System:
The UNT Digital Library
Measurements of e+e- to KKeta, KKpi0 and KsKpi CrossSections Using Initial State Radiation Events
This paper reports measurements of processes: e{sup +}e{sup -} {yields} {gamma}K{sup 0}{sub s}K{sup {+-}}{pi}{sup {+-}}, e{sup +}e{sup -} {yields} {gamma}K{sup +}K{sup -}{pi}{sup 0}, e{sup +}e{sup -} {yields} {gamma}{phi}{eta} and e{sup +}e{sup -} {yields} {gamma}{phi}{pi}{sup 0}. The initial state radiated photon allows to cover the hadronic final state in the energy range from thresholds up to {approx} 4.6 GeV. The overall size of the data sample analyzed is 232 fb{sup -1}, collected by the BABAR detector running at the PEP-II e{sup +}e{sup -} storage ring. From the Dalitz plot analysis of the K{sup 0}{sub s}K{sup {+-}}{pi}{sup {+-}} final state, moduli and relative phase of the isoscalar and the isovector components of the e{sup +}e{sup -} {yields} KK*(892) cross section are determined. Parameters of {phi} and {rho} recurrences are also measured, using a global fitting procedure which exploits the interconnection among amplitudes, moduli and phases of the e{sup +}e{sup -} {yields}K{sup 0}{sub s}K{sup {+-}}{pi}{sup {+-}}, K{sup +}K{sup -}{pi}{sup 0}, {phi}{eta} final states. The cross section for the OZI-forbidden process e{sup +}e{sup -} {yields} {phi}{pi}{sup 0} and the J/{psi} branching fractions to KK*(892) and K{sup +}K{sup -}{eta} are also measured.
Date:
November 12, 2007
Creator:
Aubert, B.
Object Type:
Article
System:
The UNT Digital Library
OF MICROBES AND MEN: A SPECIAL REPORT IN THE JOURNAL FOR MINORITY MEDICAL STUDENTS
In support of the mission for the Office of Science and the Office of Biological and Environmental Research (BER), Spectrum Publishers proposes an editorial project to inform and educate minority undergraduate students in the sciences, minority medical students and minority medical residents of the opportunities and challenges available to them as they complete their training. This editorial project will take the form of a 32-page insert in the Journal for Minority Medical Students. The subject matter will be determined by BER based on mission requirements. The material will be compiled, assembled, edited, revised, designed, printed and distributed as a total package with a vast majority of the work performed by our staff. Our objective is to provide the special report without added (and burdensome) work to the BER staff. The 32-page report will be distributed to our readership of 10,000 future scientists and physicians. In addition, we will prepare the insert so that it can also be used by BER as a stand-alone piece and outreach tool. After publication, we will solicit feedback from our readers through our unique Campus Rep Program of students strategically located on campuses across the nation who will provide valuable editorial feedback. This innovative program …
Date:
November 12, 2008
Creator:
BOWERS, BILL
Object Type:
Article
System:
The UNT Digital Library
An evaluation of the management system verification pilot at Hanford
The Chemical Management System (CMS), currently under development at Hanford, was used as the ''test program'' for pilot testing the value added aspects of the Chemical Manufacturers Association's (CMA) Management Systems Verification (MSV) process. The MSV process, which was developed by CMA's member chemical companies specifically as a tool to assist in the continuous improvement of environment, safety and health (ESH) performance, represents a commercial sector ''best practice'' for evaluating ESH management systems. The primary purpose of Hanford's MSV Pilot was to evaluate the applicability and utility of the MSV process in the Department of Energy (DOE) environment. However, because the Integrated Safety Management System (ISMS) is the framework for ESH management at Hanford and at all DOE sites, the pilot specifically considered the MSV process in the context of a possible future adjunct to Integrated Safety Management System Verification (ISMSV) efforts at Hanford and elsewhere within the DOE complex. The pilot involved the conduct of two-hour interviews with four separate panels of individuals with functional responsibilities related to the CMS including the Department of Energy Richland Operations (DOE-RL), Fluor Daniel Hanford (FDH) and FDH's major subcontractors (MSCS). A semi-structured interview process was employed by the team of three ''verifiers'' …
Date:
November 12, 1998
Creator:
BRIGGS, C.R.
Object Type:
Report
System:
The UNT Digital Library
Special Rules in the House of Representatives
The House Rules Committee enables the House to debate and vote on major legislation that is not privileged for floor consideration and that cannot pass by unanimous consent or under suspension of the rules. The Committee reports resolutions, known as rules or special rules, to make individual bills in order for floor action and to affect the procedures for debating, amending, and voting on the bills, usually in Committee of the Whole.
Date:
November 12, 1996
Creator:
Bach, Stanley
Object Type:
Report
System:
The UNT Digital Library
Pruning Implement.
Patent for a simple, inexpensive, and efficient pruning implement meant to prune trees, cutting brush, and trimming hedges. It has a reciprocating knife, an improved hatchet-blade, and an extensible saw-blade "which is seated within a groove or recess in the shank of the implement and capable of being extended and held in operative position by means of a retaining-spring" (lines 16-20).
Date:
November 12, 1895
Creator:
Baiey, George M.
Object Type:
Patent
System:
The Portal to Texas History
Physics considerations of K Reactor channel straightening
None
Date:
November 12, 1962
Creator:
Bailey, G. F.
Object Type:
Report
System:
The UNT Digital Library
Electron-Anode Interactions in Particle-in-Cell Simulations of Applied-B Ion Diodes
Particle-in-cell simulations of applied-B ion diodes using the QUICKSILVER code have been augmented with Monte Carlo calculations of electron-anode interactions (reflection and energy deposition). Extraction diode simulations demonstrate a link between the instability evolution and increased electron loss and anode heating. Simulations of radial and extraction ion diodes show spatial non-uniformity in the predicted electron loss profile leading to hot spots on the anode that rapidly exceed the 350-450 {degree}C range, known to be sufficient for plasma formation on electron-bombarded surfaces. Thermal resorption calculations indicate complete resorption of contaminants with 15-20 kcal/mole binding energies in high-dose regions of the anode during the power pulse. Comparisons of parasitic ion emission simulations and experiment show agreement in some aspects; but also highlight the need for better ion source, plasma, and neutral gas models.
Date:
November 12, 1998
Creator:
Bailey, J. E.; Cuneo, M. D.; Johnson, D. J.; Mehlhorn, T. A.; Pointon, T. D.; Renk, T. J. et al.
Object Type:
Article
System:
The UNT Digital Library
Condenser for Baling-Press
Patent for "a device capable of being applied to any horizontal baling-press for the purpose of compressing the charge of hay or other material before it enters the baling-chamber" (lines 10-14).
Date:
November 12, 1889
Creator:
Bailey, James W.
Object Type:
Patent
System:
The Portal to Texas History
Three-dimensional Simulation of Backward Raman Amplification
Three-dimensional (3-D) simulations for the Backward Raman Amplification (BRA) are presented. The images illustrate the effects of pump depletion, pulse diffraction, non-homogeneous plasma density, and plasma ionization.
Date:
November 12, 2005
Creator:
Balakin, A. A.; Fraiman, G. M. & Fisch, N. J.
Object Type:
Report
System:
The UNT Digital Library
Designing PV Incentive Programs to Promote System Performance: A Review of Current Practice
Some stakeholders continue to voice concerns about the performance of customer-sited photovoltaic (PV) systems, particularly because these systems typically receive financial support through ratepayer- or publicly-funded programs. Although much remains to be understood about the extent and specific causes of poor PV system performance, several studies of the larger programs and markets have shed some light on the issue. An evaluation of the California Energy Commission (CEC)'s Emerging Renewables Program, for example, found that 7% of systems, in a sample of 95, had lower-than-expected power output due to shading or soiling (KEMA 2005). About 3% of a larger sample of 140 systems were not operating at all or were operating well below expected output, due to failed equipment, faulty installation workmanship, and/or a lack of basic maintenance. In a recent evaluation of the other statewide PV incentive program in California, the Self-Generation Incentive Program, 9 of 52 projects sampled were found to have annual capacity factors less than 14.5%, although reasons for these low capacity factors generally were not identified (Itron 2005). Studies of PV systems in Germany and Japan, the two largest PV markets worldwide, have also revealed some performance problems associated with issues such as shading, equipment and …
Date:
November 12, 2006
Creator:
Barbose, Galen; Wiser, Ryan & Bolinger, Mark
Object Type:
Report
System:
The UNT Digital Library
Metrology Measurement Capabilities
This document contains descriptions of Federal Manufacturing & Technologies (FM&T) Metrology capabilities, traceability flow charts, and the measurement uncertainty of each measurement capability. Metrology provides NIST traceable precision measurements or equipment calibration for a wide variety of parameters, ranges, and state-of-the-art uncertainties. Metrology laboratories conform to the requirements of the Department of Energy Development and Production Manual Chapter 8.4, ANSI/ISO/IEC ANSI/ISO/IEC 17025:2000, and ANSI/NCSL Z540-1 (equivalent to ISO Guide 25). FM&T Metrology laboratories are accredited by NVLAP for the parameters, ranges, and uncertainties listed in the specific scope of accreditation under NVLAP Lab code 200108-0. See the Internet at http://ts.nist.gov/ts/htdocs/210/214/scopes/2001080.pdf. These parameters are summarized in the table at the bottom of this introduction.
Date:
November 12, 2003
Creator:
Barnes, L. M.
Object Type:
Report
System:
The UNT Digital Library
Data Quality Objectives Supporting Radiological Air Emissions Monitoring for the PNNL Site
Pacific Northwest National Laboratory (PNNL) is in the process of developing a radiological air monitoring program for the PNNL Site that is distinct from that of the nearby Hanford Site. The original DQO (PNNL-19427) considered radiological emissions at the PNNL Site from Physical Sciences Facility (PSF) major emissions units. This first revision considers PNNL Site changes subsequent to the implementation of the original DQO. A team was established to determine how the PNNL Site changes would continue to meet federal regulations and address guidelines developed to monitor air emissions and estimate offsite impacts of radioactive material operations. The result is an updated program to monitor the impact to the public from the PNNL Site. The team used the emission unit operation parameters and local meteorological data as well as information from the PSF Potential-to-Emit documentation and Notices of Construction submitted to the Washington State Department of Health (WDOH). The locations where environmental monitoring stations would most successfully characterize the maximum offsite impacts of PNNL Site emissions from the three PSF buildings with major emission units were determined from these data. Three monitoring station locations were determined during the original revision of this document. This first revision considers expanded Department of …
Date:
November 12, 2012
Creator:
Barnett, J. M.; Meier, Kirsten M.; Snyder, Sandra F.; Fritz, Brad G.; Poston, Theodore M. & Antonio, Ernest J.
Object Type:
Report
System:
The UNT Digital Library
Influence of specimen design on the ductility of zircaloy cladding: Experiment and analysis
In a reactivity-initiated accident (RIA), a control rod ejection or drop causes a sudden increase in reactor power, which in turn deposits a large amount of energy into the fuel. The resulting thermal expansion and fission gas release loads the cladding into the plastic regime and may cause it to fail. In order to predict cladding survivability, there has been considerable interest and effort in supplementing integral WA tests with separate-effects ring tests of cladding tubes. Such tests can give one insight into failure mechanisms and measure relevant mechanical properties (such as yield strength, uniform elongation, uniaxial stress-strain curve, etc.), for use in computer codes that attempt to predict cladding response during an RIA. The accuracy of such model predictions obviously depends on appropriate and accurate failure data. This study concerns itself with the proper development of ring tensile tests that (i) are similar to the loading conditions present in an RIA, (ii) measure the relevant mechanical properties and (iii) provide insight regarding the influence of the strain paths on the failure mechanisms present if Zircaloy cladding. Based on both experiments and computational modeling, the authors investigate the failure of Zircaloy tubing as a function of specimen geometry, and discuss …
Date:
November 12, 1999
Creator:
Bates, D. W.; Majumdar, S.; Koss, D. A. & Motta, A. T.
Object Type:
Article
System:
The UNT Digital Library
In-Situ Sample Preparation for Radiochemical Analyses of Surface Water
A new method for improved radionuclide sample analysis of surface water has been demonstrated at the Savannah River Site, a U.S. Department of Energy production facility, currently in standby. The method makes uses of selective solid phase extraction (SPE) disks being placed in a modified portable aqueous sampler.
Date:
November 12, 1998
Creator:
Beals, D.M.; Crandall, B. S. & Fledderman, P. D.
Object Type:
Article
System:
The UNT Digital Library