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A 1.8 Mev K+ injector for the high current beam transport experiment fusion
For the High Current Beam Transport Experiment (HCX) at LBNL, an injector is required to deliver up to 1.8 MV of 0.6 A K{sup +} beam with an emittance of {approx}1 p-mm-mrad. We have successfully operated a 10-cm diameter surface ionization source together with an electrostatic quadrupole (ESQ) accelerator to meet these requirements. The pulse length is {approx}4 {micro}s, firing at once every 10-15 seconds. By optimizing the extraction diode and the ESQ voltages, we have obtained an output beam with good current density uniformity, except for a small increase near the beam edge. Characterization of the beam emerging from the injector included measurements of the intensity profile, beam imaging, and transverse phase space. These data along with comparison to computer simulations provide the knowledge base for designing and understanding future HCX experiments.
Date:
May 20, 2002
Creator:
Kwan, J. W.; Bieniosek, F. M.; Henestroza, E.; Prost, L. & Seidl, P.
Object Type:
Article
System:
The UNT Digital Library
1-MeV-Electron Irradiation of GaInAsN Cells: Preprint
This conference paper describes the GaInAsN cells that are measured to retain 933% and 894% of their original efficiency after exposure to 5 X 1014 and 1 X 1015 cm-2 1-MeV electrons, respectively. The rate of degradation is not correlated with the performance at beginning of life (BOL). The depletion width remains essentially unchanged, increasing by< 1%. Temperature-coefficient data for GaInAsN cells are also presented. These numbers are used to project the efficiency of GaInAsN-containing multijunction cells. The GaInAsN junction is not currently predicted to increase the efficiencies of the multijunction cells. Nevertheless, GaInAsN-containing multijunction cell efficiencies are predicted to be comparable to those of the conventional structures, and even small improvements in the GaInAsN cell may lead to higher multijunction cell efficiencies, especially for high-radiation applications and when cell operating temperature is low.
Date:
May 1, 2002
Creator:
Kurtz, Sarah; King, R. R.; Edmondson, K. M.; Friedman, D. J. & Karam, N. H.
Object Type:
Article
System:
The UNT Digital Library
A 2-Liter, 2000 MPa Air Source for the Radiatively Driven Hypersonic Wind Tunnel
The A2 LITE is a 2 liter, 2000 MPa, 750 K ultra-high pressure (UHP) vessel used to demonstrate UHP technology and to provide an air flow for wind tunnel nozzle development. It is the largest volume UHP vessel in the world. The design is based on a 100:1 pressure intensification using a hydraulic ram as a low pressure driver and a three-layer compound cylinder UHP section. Active control of the 900 mm piston stroke in the 63.5 mm bore permits pressure-time profiles ranging from static to constant pressure during flow through a 1 mm throat diameter nozzle for 1 second.
Date:
May 30, 2002
Creator:
Costantino, M & Lofftus, D
Object Type:
Article
System:
The UNT Digital Library
15th Street News (Midwest City, Okla.), Vol. 31, No. 27, Ed. 1 Friday, May 3, 2002
Newspaper from Rose State College in Midwest City, Oklahoma that includes national, local, and campus news along with advertising.
Date:
May 3, 2002
Creator:
Baldwin, Alisha
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
15th Street News (Midwest City, Okla.), Vol. 31, No. 28, Ed. 1 Friday, May 10, 2002
Newspaper from Rose State College in Midwest City, Oklahoma that includes national, local, and campus news along with advertising.
Date:
May 10, 2002
Creator:
Baldwin, Alisha
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
2001 Columbia River Recreation Survey -- Implications for Hanford Site Integrated Assessment
This report presents the results from the Columbia River Recreation Survey conducted in the summer of 2001. The survey combined on-site personal interviews with parties engaged in river recreation with on-site field observations to develop a picture of summer river recreation on the Columbia. The study area stretched from just below Priest Rapids Dam in the north to McNary Dam in the south, and was divided into four "Areas" that correspond to the river areas used by the Groundwater/Vadose Zone Integration Project. This study is part of the Groundwater/Vadose Zone Integration Project and was commissioned specifically to document the current recreation use levels in these areas of the river, and to elicit recreation-related expenditure information from visitors. This information informs economic and environmental models used to measure the economic risk posed by possible, but unlikely, releases of contaminants from the Hanford site into the Columbia River. During the study period, researchers collected 256 survey responses and 396 field observations from recreation sites up and down both shores of the river in the study area. Results presented include analysis of trip duration by river activity, trip frequency, and visitor place of origin. Economics-related results include trip expenditure profiles by activity and …
Date:
May 16, 2002
Creator:
Anderson, Dave M.; Scott, Michael J.; Bunn, Amoret L.; Fowler, Richard A.; Prendergast, Ellen L.; Miley, Terri B. et al.
Object Type:
Report
System:
The UNT Digital Library
2001 NSLS Activity Report (National Synchrotron Light Source).
This describes the advertising of cover page of 2001 NSLS Activity Report (National Synchrotron Light Source).
Date:
May 1, 2002
Creator:
Corwin, M. A.
Object Type:
Report
System:
The UNT Digital Library
2001 NSLS Activity Report (National Synchrotron Light Source)
The year 2001 has been another highly productive year at the NSLS, with over 2500 users, including 720 first time users, conducting nearly 1200 experiments in fields ranging from the life, materials, chemical, and environmental sciences to applied science and technology. An impressive array of highlights from this scientific activity is included in this Activity Report. They include the first demonstration of a direct structural probe of the superconducting ground state in the cuprates by utilizing anomalous soft x-ray resonance effects to selectively enhance the scattering from doped holes. Another highly significant result was the determination of the structure of the potassium channel membrane protein. This is especially significant as it provides insight into how the channel functions and how it selects a particular kind of ion. In the nanoscience area, small angle x-ray scattering measurements played an essential role in determining that preferential sequestering of tailored metal nanocrystals into a self-assembled lamellar diblock copolymer can produce high quality metallodielectric photonic bandgap structures, demonstrating the potential of these nanocomposites for photonic crystal engineering. The infrared microscopy program continued to yield noteworthy results, including an important study that characterized the types and abundances of organic materials in contaminated and uncontaminated sediments …
Date:
May 1, 2002
Creator:
Corwin, M. A.
Object Type:
Report
System:
The UNT Digital Library
The 2002 Farm Bill: Overview and Status
The Federal Agriculture Improvement and Reform, or FAIR, Act of 1996 (commonly known as the "farm bill"), which was due to expire in 2002, is expected to be extended for another six years when President Bush signs the bill into law. This report discusses the provisions of the new "farm bill," including the federal spending involved.
Date:
May 3, 2002
Creator:
Becker, Geoffrey S. & Womach, Jasper
Object Type:
Report
System:
The UNT Digital Library
2002 Summer Visitors' Guide (Port Aransas, Tex.)
Summer visitors' guide from Port Aransas, Texas that includes information of interest to visitors along with extensive advertising.
Date:
May 23, 2002
Creator:
Judson, Mary
Object Type:
Newspaper
System:
The Portal to Texas History
A 3D Contact Smoothing Method
Smoothing of contact surfaces can be used to eliminate the chatter typically seen with node on facet contact and give a better representation of the actual contact surface. The latter affect is well demonstrated for problems with interference fits. In this work we present two methods for the smoothing of contact surfaces for 3D finite element contact. In the first method, we employ Gregory patches to smooth the faceted surface in a node on facet implementation. In the second method, we employ a Bezier interpolation of the faceted surface in a mortar method implementation of contact. As is well known, node on facet approaches can exhibit locking due to the failure of the Babuska-Brezzi condition and in some instances fail the patch test. The mortar method implementation is stable and provides optimal convergence in the energy of error. In the this work we demonstrate the superiority of the smoothed versus the non-smoothed node on facet implementations. We also show where the node on facet method fails and some results from the smoothed mortar method implementation.
Date:
May 2, 2002
Creator:
Puso, M. A. & Laursen, T. A.
Object Type:
Article
System:
The UNT Digital Library
3D Extended Logging for Geothermal Resources: Field Trials with the Geo-Bilt System
Geo-BILT (Geothermal Borehole Induction Logging Tool) is an extended induction logging tool designed for 3D resistivity imaging around a single borehole. The tool was developed for deployment in high temperature geothermal wells under a joint program funded by the California Energy Commission, Electromagnetic Instruments (EMI) and the U.S. Department of Energy. EM1 was responsible for tool design and manufacture, and numerical modeling efforts were being addressed at Lawrence Livermore Laboratory (LLNL) and other contractors. The field deployment was done by EM1 and LLNL. The tool operates at frequencies from 2 to 42 kHz, and its design features a series of three-component magnetic sensors offset at 2 and 5 meters from a three-component magnetic source. The combined package makes it possible to do 3D resistivity imaging, deep into the formation, from a single well. The manufacture and testing of the tool was completed in spring of 2001, and the initial deployment of Geo-BILT occurred in May 2001 at the Lost Hills oil field in southern California at leases operated by Chevron USA. This site was chosen for the initial field test because of the favorable geological conditions and the availability of a number of wells suitable for tool deployment. The second …
Date:
May 29, 2002
Creator:
Mallan, Robert; Wilt, Michael; Kirkendall, Barry & Kasameyer, Paul
Object Type:
Article
System:
The UNT Digital Library
Ability Estimation Under Different Item Parameterization and Scoring Models
A Monte Carlo simulation study investigated the effect of scoring format, item parameterization, threshold configuration, and prior ability distribution on the accuracy of ability estimation given various IRT models. Item response data on 30 items from 1,000 examinees was simulated using known item parameters and ability estimates. The item response data sets were submitted to seven dichotomous or polytomous IRT models with different item parameterization to estimate examinee ability. The accuracy of the ability estimation for a given IRT model was assessed by the recovery rate and the root mean square errors. The results indicated that polytomous models produced more accurate ability estimates than the dichotomous models, under all combinations of research conditions, as indicated by higher recovery rates and lower root mean square errors. For the item parameterization models, the one-parameter model out-performed the two-parameter and three-parameter models under all research conditions. Among the polytomous models, the partial credit model had more accurate ability estimation than the other three polytomous models. The nominal categories model performed better than the general partial credit model and the multiple-choice model with the multiple-choice model the least accurate. The results further indicated that certain prior ability distributions had an effect on the accuracy …
Date:
May 2002
Creator:
Si, Ching-Fung B.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Acceleration schedules for a recirculating heavy-ion accelerator
Recent advances in solid-state switches have made it feasible to design programmable, high-repetition-rate pulsers for induction accelerators. These switches could lower the cost of recirculating induction accelerators, such as the ''small recirculator'' at Lawrence Livermore National Laboratory (LLNL), by substantially reducing the number of induction modules. Numerical work is reported here to determine what effects the use of fewer pulsers at higher voltage would have on the beam quality of the LLNL small recirculator. Lattices with different numbers of pulsers are examined using the fluid/envelope code CIRCE, and several schedules for acceleration and compression are compared for each configuration. For selected schedules, the phase-space dynamics is also studied using the particle-in-cell code WARP3d.
Date:
May 1, 2002
Creator:
Sharp, W. M. & Grote, D. P.
Object Type:
Article
System:
The UNT Digital Library
Accelerator-Based Surface Chemistry by Combined Time-of-Flight Mass Spectrometry (TOF-MS) and Particle-Induced X-Ray Emission (PIXE)
We describe the development of a new capability for performing microscopic chemical analysis in the near surface of a sample. The technology uses a focused high-energy ion beam from an accelerator to cause characteristic elemental x-rays to be emitted and, simultaneously, molecules and fragments to be desorbed from the surface of the sample. Spectroscopic analysis of the fluoresced x-rays provides quantitative trace element information of the sample volume probed by the beam. The elemental data are subsequently used to identify peaks in the mass analysis of the desorbed species, thereby providing a detailed description of the local surface chemistry. High-resolution (micron-scale) chemical imaging is possible by scanning the beam over the sample.
Date:
May 31, 2002
Creator:
Morse, D. H.; Grant, P. G.; Antolak, A. J.; Sproch, N. & Fernando, Q.
Object Type:
Article
System:
The UNT Digital Library
Accounting Profession: Oversight, Auditor Independence, and Financial Reporting Issues
Correspondence issued by the General Accounting Office with an abstract that begins "The accounting system's self-regulatory system for auditors, which largely depends on voluntary contributions from the accounting industry, is plagued by fragmentation, lack of coordination, poor communication, and conflicts of interest. In GAO's view, the current self-regulatory system is broken, and oversight by the Securities and Exchange Commission (SEC) has fallen short in protecting the public interest. Because of the important role played by independent auditors, GAO believes that direct government intervention is needed to create a new body to oversee the auditing of public companies by the accounting profession. Concerns about the timeliness, relevancy, and transparency of the financial reporting model could be addressed by closer cooperation between SEC and the Financial Accounting Standards Board (FASB), adequate and independent funding for FASB operations, and periodic reporting to Congress on FASB matters."
Date:
May 3, 2002
Creator:
United States. General Accounting Office.
Object Type:
Text
System:
The UNT Digital Library
The Accounting Profession: Status of Panel on Audit Effectiveness Recommendations to Enhance the Self-Regulatory System
A letter report issued by the General Accounting Office with an abstract that begins "The accounting profession maintains a voluntary, self-regulatory system through the American Institute of Certified Public Accountants (AICPA) that includes establishing professional standards, monitoring compliance with professional standards, disciplining members for improper acts and substandard performance, and conducting oversight. The Panel of Audit Effectiveness, set up to examine the AICPA's methods, made recommendations to enhance the accounting profession's self-regulatory system. Implementing actions taken or in process have addressed many of the Panel's recommendations. However, the Panel's recommendations did not fully address the limitations of the self-regulatory system identified in its report. Also, some of the Panel's recommendations were either not accepted or are still under study. Additional experience is needed to evaluate the effectiveness of actions taken or planned. However, the system is fragmented, uncoordinated, and has a disciplinary function that is widely perceived to be ineffective. The self-regulatory system is unable to protect the confidentiality of investigative information about alleged audit failures or other disciplinary matters concerning members of the profession. The lack of such protective powers hinders the timing of investigations and affects the public's perception of the self-regulatory system's effectiveness. The Panel recognized the …
Date:
May 17, 2002
Creator:
United States. General Accounting Office.
Object Type:
Report
System:
The UNT Digital Library
Accuracy of flow hoods in residential applications
To assess whether houses can meet performance expectations, the new practice of residential commissioning will likely use flow hoods to measure supply and return grille airflows in HVAC systems. Depending on hood accuracy, these measurements can be used to determine if individual rooms receive adequate airflow for heating and cooling, to determine flow imbalances between different building spaces, to estimate total air handler flow and supply/return imbalances, and to assess duct air leakage. This paper discusses these flow hood applications and the accuracy requirements in each case. Laboratory tests of several residential flow hoods showed that these hoods can be inadequate to measure flows in residential systems. Potential errors are about 20% to 30% of measured flow, due to poor calibrations, sensitivity to grille flow non-uniformities, and flow changes from added flow resistance. Active flow hoods equipped with measurement devices that are insensitive to grille airflow patterns have an order of magnitude less error, and are more reliable and consistent in most cases. Our tests also show that current calibration procedures for flow hoods do not account for field application problems. As a result, a new standard for flow hood calibration needs to be developed, along with a new measurement …
Date:
May 1, 2002
Creator:
Wray, Craig P.; Walker, Iain S. & Sherman, Max H.
Object Type:
Article
System:
The UNT Digital Library
Accurate estimation of the RMS emittance from single current amplifier data
This paper presents the SCUBEEx rms emittance analysis, a self-consistent, unbiased elliptical exclusion method, which combines traditional data-reduction methods with statistical methods to obtain accurate estimates for the rms emittance. Rather than considering individual data, the method tracks the average current density outside a well-selected, variable boundary to separate the measured beam halo from the background. The average outside current density is assumed to be part of a uniform background and not part of the particle beam. Therefore the average outside current is subtracted from the data before evaluating the rms emittance within the boundary. As the boundary area is increased, the average outside current and the inside rms emittance form plateaus when all data containing part of the particle beam are inside the boundary. These plateaus mark the smallest acceptable exclusion boundary and provide unbiased estimates for the average background and the rms emittance. Small, trendless variations within the plateaus allow for determining the uncertainties of the estimates caused by variations of the measured background outside the smallest acceptable exclusion boundary. The robustness of the method is established with complementary variations of the exclusion boundary. This paper presents a detailed comparison between traditional data reduction methods and SCUBEEx by …
Date:
May 31, 2002
Creator:
Stockli, Martin P.; Welton, R. F.; Keller, R.; Letchford, A. P.; Thomae, R. W. & Thomason, J. W. G.
Object Type:
Article
System:
The UNT Digital Library
Active and passive safety control performance in sub - critical, accelerator - driven nuclear reactors.
Traditional safety performance requirements for nuclear reactors have been developed for critical reactors, whose kinetics characteristics differ significantly from sub-critical, accelerator-driven nuclear reactors. In a critical nuclear reactor, relatively small amounts of reactivity (negative or positive) can produce large changes in the fission rate. In sub-critical reactors, the self-multiplication (k) decreases as the sub-criticality (1-k) increases, and the responsiveness to small reactivity changes decreases. This makes sub-critical nuclear reactors less responsive to positive reactivity insertions than critical reactors. Also, larger negative reactivity insertions are needed in sub-critical reactors to shut down the fission chain if the neutron source remains. This paper presents the results from a computational analysis of the safety performance of sub-critical, accelerator-driven nuclear reactors. Coupled kinetics and thermal-hydraulics models are used to quantify the effectiveness of traditional protection and control system designs in sub-critical reactors. The analyses also quantify the role of inherent, passive reactivity feedback mechanisms in sub-critical reactors. Computational results are used to develop conclusions regarding the most favorable and effective means for reactor control and protection in sub-critical, accelerator-driven nuclear reactors.
Date:
May 24, 2002
Creator:
Cahalan, J. E. & Eriksson, M.
Object Type:
Article
System:
The UNT Digital Library
Adaptive Management Platform for Natural Resources in the Columbia River Basin
Adaptive management is a systematic and rigorous scientifically defensible program of learning from the outcomes of management actions, accommodating change, and improving management. The critical requirements and toolboxes of an information management framework, referred to as the Adaptive Management Platform (AMP), to realize the goal of adaptive management are described. The AMP design that connects various modules to ensure that the decision-making needs are met. The modules are data management, visualization tools, optimization algorithms, and models of Columbia Basin physical and biological processes. When fully developed, AMP will enable subbasin planners and responsible entities throughout the Basin to collectively and continuously integrate data and decisions, assess cumulative trends and outcomes over time, and demonstrate discipline and accountability. AMP would function at the basin, ecoprovince, as well as the subbasin scale. AMP would assist in ensuring that uncertainties from individual modules and analytical integration are properly presented to decision makers.
Date:
May 1, 2002
Creator:
Vail, Lance W. & Skaggs, Richard
Object Type:
Report
System:
The UNT Digital Library
The advanced computational testing and simulation toolkit (ACTS)
During the past decades there has been a continuous growth in the number of physical and societal problems that have been successfully studied and solved by means of computational modeling and simulation. Distinctively, a number of these are important scientific problems ranging in scale from the atomic to the cosmic. For example, ionization is a phenomenon as ubiquitous in modern society as the glow of fluorescent lights and the etching on silicon computer chips; but it was not until 1999 that researchers finally achieved a complete numerical solution to the simplest example of ionization, the collision of a hydrogen atom with an electron. On the opposite scale, cosmologists have long wondered whether the expansion of the Universe, which began with the Big Bang, would ever reverse itself, ending the Universe in a Big Crunch. In 2000, analysis of new measurements of the cosmic microwave background radiation showed that the geometry of the Universe is flat, and thus the Universe will continue expanding forever. Both of these discoveries depended on high performance computer simulations that utilized computational tools included in the Advanced Computational Testing and Simulation (ACTS) Toolkit. The ACTS Toolkit is an umbrella project that brought together a number of …
Date:
May 21, 2002
Creator:
Drummond, L. A. & Marques, O. A.
Object Type:
Article
System:
The UNT Digital Library
ADVANCED FLUE GAS CONDITIONING AS A RETROFIT UPGRADE TO ENHANCE PM COLLECTION FROM COAL-FIRED ELECTRIC UTILITY BOILERS
The U.S. Department of Energy and ADA Environmental Solutions are engaged in a project to develop commercial flue gas conditioning additives. The objective is to develop conditioning agents that can help improve particulate control performance of smaller or under-sized electrostatic precipitators on utility coal-fired boilers. The new chemicals will be used to control both the electrical resistivity and the adhesion or cohesivity of the fly ash. There is a need to provide cost-effective and safer alternatives to traditional flue gas conditioning with SO{sub 3} and ammonia. During this reporting quarter, performance testing of flue gas conditioning was underway at the PacifiCorp Jim Bridger Power Plant. The product tested, ADA-43, was a combination resistivity modifier with cohesivity polymers. This represents the first long-term full-scale testing of this class of products. Modifications to the flue gas conditioning system at Jim Bridger, including development of alternate injection lances, was also undertaken to improve chemical spray distribution and to avoid spray deposition to duct interior surfaces. Also in this quarter, a firm commitment was received for another long-term test of the cohesivity additives. This plant fires a bituminous coal and has opacity and particulate emissions performance issues related to fly ash re-entrainment. Ammonia conditioning …
Date:
May 1, 2002
Creator:
Baldrey, Kenneth E.
Object Type:
Report
System:
The UNT Digital Library
Advanced intraundulator electron beam diagnostics using COTR techniques.
None
Date:
May 15, 2002
Creator:
Lumpkin, A. H. L.; Berg, W. J. B.; Biedron, S. B.; Borland, M. B.; Chae, Y. C. C.; Dejus, R. D. et al.
Object Type:
Article
System:
The UNT Digital Library