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3,018 Matching Results
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3,018
Madrid Protocol Implementation Act: Overview of H.R. 769
None
Date:
February 8, 2000
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Medicare: Program Reform and Modernization Are Needed But Entail Considerable Challenges
Testimony issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO discussed efforts to reform the administration, structure, and financing of the Medicare Program."
Date:
February 8, 2000
Creator:
United States. General Accounting Office.
Object Type:
Text
System:
The UNT Digital Library
Numerical simulation of two-phase flow with front-capturing
Because of the complexity of two-phase flow phenomena, two-phase flow codes rely heavily on empirical correlations. This approach has a number of serious shortcomings. Advances in parallel computing and continuing improvements in computer speed and memory have stimulated the development of numerical simulation tools that rely less on empirical correlations and more on fundamental physics. The objective of this work is to take advantage of developments in massively parallel computing, single-phase computational fluid dynamics of complex systems, and numerical methods for front capturing in two-phase flows to develop a computer code for direct numerical simulation of two-phase flow. This includes bubble/droplet transport, interface deformation and topology change, bubble/droplet interactions, interface mass, momentum and energy transfer.
Date:
February 8, 2000
Creator:
Tzanos, C. P. & Weber, D. P.
Object Type:
Article
System:
The UNT Digital Library
Optimal Segmentation Strategy for Compact Representation of Hyperspectral Image Cubes
By producing compact representations of hyperspectral image cubes (hypercubes), image storage requirements and the amount of time it takes to extract essential elements of information can both be dramatically reduced. However, these compact representations must preserve the important spectral features within hypercube pixels and the spatial structure associated with background and objects or phenomena of interest. This paper describes a novel approach for automatically and efficiently generating a particular type of compact hypercube representation, referred to as a supercube. The hypercube is segmented into regions that contain pixels with similar spectral shapes that are spatially connected, and the pixel connectivity constraint can be relaxed. Thresholds of similarity in spectral shape between pairs of pixels are derived directly from the hypercube data. One superpixel is generated for each region as some linear combination of pixels belonging to that region. The superpixels are optimal in the sense that the linear combination coefficients are computed so as to minimize the level of noise. Each hypercube pixel is represented in the supercube by applying a gain and bias to the superpixel assigned to the region containing that pixel. Examples are provided.
Date:
February 8, 2000
Creator:
Paglieroni, D & Roberts, R
Object Type:
Article
System:
The UNT Digital Library
Origin of the pseudogap in high temperature superconductors
Underdoped high temperature superconductors (HTS) exhibit a normal state for energies E > E{sub g} and/or temperatures T > T{sub 0}, and a pseudogap in their electronic spectrum for E < E{sub g} and/or T{sub 0} > T > {Tc}. Strikingly similar behavior occurs in the transition metal dichalcogenides (TMD) 2H-MX{sub 2}, where M = Ta, Nb, and X = S, Se, both in the normal (T > T{sub 0}) and in the incommensurate charge-density wave (T{sub ICDW} > T > T{sub c}) states. Such strikingly similar behavior has also been seen in the organic layered superconductors (OLS) {kappa}-(ET){sub 2}X, where ET is bis(ethylenedithio)tetrathiafulvalene, and X = Cu[N(CN){sub 2}]Br, and Cu(SCN){sub 2}, both in the normal region T > T{sub SDW} > {Tc} and in the spin-density wave region T{sub SDW} > T > T{sub c}. In all three materials classes, the anomalous transport and thermodynamic properties associated with the pseudogap or density-wave regime are completely independent of the applied magnetic field strength, whereas the same properties below {Tc} are all strongly field-dependent. Hence, the authors propose that the pseudogap in the HTS arises from charge- and/or spin-density waves, and not from either superconducting fluctuations or preformed charged quasiparticle pairs.
Date:
February 8, 2000
Creator:
Klemm, R. A.
Object Type:
Article
System:
The UNT Digital Library
Polarized light propagation through tissue and tissue phantoms
We show that standard tissue phantoms can be used to mimic the intensity and polarization properties of tissue. Polarized light propagation through biologic tissue is typically studied using tissue phantoms consisting of dilute aqueous suspensions of microspheres. The dilute phantoms can empirically match tissue polarization and intensity properties. One discrepancy between the dilute phantoms and tissue exist: common tissue phantoms, such as dilute Intralipid and dilute 1-{micro}m-diameter polystyrene microsphere suspensions, depolarize linearly polarized light more quickly than circularly polarized light. In dense tissue, however, where scatterers are often located in close proximity to one another, circularly polarized light is depolarized similar to or more quickly than linearly polarized light. We also demonstrate that polarized light propagates differently in dilute versus densely packed microsphere suspensions, which may account for the differences seen between polarized light propagation in common dilute tissue phantoms versus dense biologic tissue.
Date:
February 8, 2000
Creator:
Sankaran, V; Walsh, J T JR & Maitland, D J
Object Type:
Article
System:
The UNT Digital Library
Q-Switched Operation of a Coupled-Resonator Vertical-Cavity Laser Diode
The authors report Q-switched operation from an electrically-injected monolithic coupled-resonator structure which consists of an active cavity with InGaAs quantum wells optically coupled to a passive cavity. The passive cavity contains a bulk GaAs region which is reverse-biased to provide variable absorption at the lasing wavelength of 990 nm. Cavity coupling is utilized to effect large changes in output intensity with only very small changes in passive cavity absorption. The device is shown to produce pulses as short as 150 ps at repetition rates as high 4 GHz. A rate equation approach is used to model the Q-switched operation yielding good agreement between the experimental and theoretical pulse shape. Small-signal frequency response measurements also show a transition from a slower ({approximately} 300 MHZ) forward-biased modulation regime to a faster ({approximately} 2 GHz) modulation regime under reverse-bias operation.
Date:
February 8, 2000
Creator:
Fischer, Arthur J.; Chow, Weng W.; Choquette, Kent D.; Allerman, Andrew A. & Geib, Kent M.
Object Type:
Article
System:
The UNT Digital Library
Results of Retrieval Studies with Waste from Tank 241-C-104
Laboratory studies were performed on samples of waste from Tank 241-C-104. Physical property data was gathered to develop engineering plans for retrieval operations. Chemical composition data was collected to verify the ability to meet contract feed specifications.
Date:
February 8, 2000
Creator:
O'Rourke, J. F.
Object Type:
Report
System:
The UNT Digital Library
Soot scattering measurements in the visible and near-infrared spectrum
Scattering to extinction cross-section ratios, {rho}{sub se} were measured using the NIST Large Agglomerate Optics Facility for soot produced from ethene and acetylene laminar diffusion flames. Measurements were performed using light sources at 543.5 nm, 632.8 nm and 856 nm. The average scattering to extinction cross-section ratios for these wavelengths are equal to 0.246, 0.196, and 0.196 for ethene and 0.316, 0.230, and 0.239 for acetylene. The 856 nm measurements represent the longest wavelength for which accurate scattering measurements have been performed for soot. The size distribution and fractal properties of the two soots were determined to assess the effects of limited acceptance angle range, finite size of the sensor, and departure from cosine response on the uncertainty in the measurement of {rho}{sub se} The expanded relative uncertainty (95% confidence level) was found to be {+-}6% at the two visible wavelengths and {+-}8% at 856 nm. Both the magnitude and wavelength dependence of {rho}{sub se} for the present experiments are significantly different from those reported by Krishnan et al. for overfire soot produced using a turbulent flame. The results are compared with the predictions of fractal optics.
Date:
February 8, 2000
Creator:
Zhu, Jinyu; Choi, Mun Young; Mulholland, George W. & Gritzo, Louis A.
Object Type:
Article
System:
The UNT Digital Library
Spent Nuclear Fuel (SNF) Project Safety Basis Implementation Strategy
The objective of the Safety Basis Implementation is to ensure that implementation of activities is accomplished in order to support readiness to move spent fuel from K West Basin. Activities may be performed directly by the Safety Basis Implementation Team or they may be performed by other organizations and tracked by the Team. This strategy will focus on five key elements, (1) Administration of Safety Basis Implementation (general items), (2) Implementing documents, (3) Implementing equipment (including verification of operability), (4) Training, (5) SNF Project Technical Requirements (STRS) database system.
Date:
February 8, 2000
Creator:
TRAWINSKI, B.J.
Object Type:
Report
System:
The UNT Digital Library
Summary of the Solar Two Test and Evaluation Program
Solar Two was a collaborative, cost-shared project between eleven US industry and utility partners and the U. S. Department of Energy to validate molten-salt power tower technology. The Solar Two plant, located east of Barstow, CA, was comprised of 1926 heliostats, a receiver, a thermal storage system and a steam generation system. Molten nitrate salt was used as the heat transfer fluid and storage media. The steam generator powered a 10 MWe, conventional Rankine cycle turbine. Solar Two operated from June 1996 to April 1999. The major objective of the test and evaluation phase of the project was to validate the technical characteristics of a molten salt power tower. This paper describes the significant results from the test and evaluation activities.
Date:
February 8, 2000
Creator:
PACHECO,JAMES E.; REILLY,HUGH E.; KOLB,GREGORY J. & TYNER,CRAIG E.
Object Type:
Article
System:
The UNT Digital Library
Texas Attorney General Opinion: JC-180
Document issued by the Office of the Attorney General of Texas in Austin, Texas, providing an interpretation of Texas law. It provides the opinion of the Texas Attorney General, John Cornyn, regarding a legal question submitted for clarification; Whether section 21.055 of the Tax Code, which governs the taxation of certain business aircraft used outside of taxes in tax years 1995 through 1999 (RQ-0136-JC)
Date:
February 8, 2000
Creator:
Texas. Attorney-General's Office.
Object Type:
Text
System:
The Portal to Texas History
Three dimensional position sensitivity in two dimensionally segmented HP-Ge detectors
None
Date:
February 8, 2000
Creator:
Vetter, K.; Kuhn, A.; Deleplanque, M.; Lee, I. Y.; Stephens, F. S.; Schmid, G. J. et al.
Object Type:
Article
System:
The UNT Digital Library
Trade Legislation in the 106th Congress: An Overview
None
Date:
February 8, 2000
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library
Updated Drainable Interstitial Liquid Volume Estimates for 119 Single Shell Tanks (SST) Declared Stabilized
This document assesses the volume of drainable interstitial liquid (DIL) and pumpable liquid remaining in 119 single-shell tanks (SSTs) that were previously stabilized. Based on the methodology and assumptions presented, the DIL exceeded the stabilization criterion of less than 50,000 gal in two of the 119 SSTs. Tank 241-C-102 had an estimated DIL of 62,000 gal, and the estimated DIL for tank 241-BY-103 was 58,000 gal. In addition, tanks 241-BX-103, 241-T-102, and 241-T-112 appear to exceed the stabilization criterion of 5,000 gal supernatant. An assessment of the source of the supernatant in these tanks is beyond the scope of this document. The actual DIL and pumpable liquid remaining volumes for each tank may vary significantly from estimated volumes as a result of specific tank waste characteristics that are not currently measured or defined. Further refinement to the pumpable liquid and DIL volume estimates may be needed as additional tank waste information is obtained.
Date:
February 8, 2000
Creator:
FIELD, J.G.
Object Type:
Report
System:
The UNT Digital Library
Waste Feed Delivery Raw Water and Potable Water and Compressed Air Capacity Evaluation
This study evaluated the ability of the Raw Water, Potable Water, and Compressed Air systems to support safe storage as well as the first phase of the Waste Feed Delivery. Several recommendations are made to improve the system.
Date:
February 8, 2000
Creator:
MAY, T.H.
Object Type:
Report
System:
The UNT Digital Library
World Trade Organization: Seattle Ministerial: Outcomes and Lessons Learned
Testimony issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO discussed the World Trade Organization's (WTO) 1999 ministerial conference, focusing on the: (1) outcome of the ministerial conference; (2) factors contributing to the outcome; and (3) the lessons learned from the meeting."
Date:
February 8, 2000
Creator:
United States. General Accounting Office.
Object Type:
Text
System:
The UNT Digital Library
Uncharted Frontiers in the Spectroscopy of Highly Charged Ions
The development of novel techniques is critical for maintaining a state-of-the-art core competency in atomic physics and readiness for evolving programmatic needs. We have carried out a three-year effort to develop novel spectroscopic instrumentation that added new dimensions to our capabilities for measuring energy levels, radiative transition probabilities, and electron-ion excitation processes. The new capabilities created were in areas that heretofore had been inaccessible to scientific scrutiny and included high-resolution spectroscopy of hard x rays, femtosecond lifetime measurements, measurements of transition probabilities of long-lived metastable levels, polarization spectroscopy, ultra-precise determinations of energy levels, and the establishment of absolute wavelength standards in x-ray spectroscopy. Instrumentation developed during the period included a transmission-type crystal spectrometer, a flat-field EUV spectrometer, and the development and deployment of absolutely calibrated monolithic crystals. The new capabilities enabled very sensitive tests of atomic wave functions, of calculations of magnetic sublevel populations, and of fundamental theories in uncharted regimes, and provided the basis for developing new diagnostic techniques of high-density plasmas.
Date:
January 8, 2000
Creator:
Beiersdorfer, P.; Brown, G.; Crespo, J.; Kim, S. H.; Neill, P.; Utter, S. et al.
Object Type:
Report
System:
The UNT Digital Library