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On The Reproducibility of Seasonal Land-surface Climate (open access)

On The Reproducibility of Seasonal Land-surface Climate

The sensitivity of the continental seasonal climate to initial conditions is estimated from an ensemble of decadal simulations of an atmospheric general circulation model with the same specifications of radiative forcings and monthly ocean boundary conditions, but with different initial states of atmosphere and land. As measures of the ''reproducibility'' of continental climate for different initial conditions, spatio-temporal correlations are computed across paired realizations of eleven model land-surface variables in which the seasonal cycle is either included or excluded--the former case being pertinent to climate simulation, and the latter to seasonal anomaly prediction. It is found that the land-surface variables which include the seasonal cycle are impacted only marginally by changes in initial conditions; moreover, their seasonal climatologies exhibit high spatial reproducibility. In contrast, the reproducibility of a seasonal land-surface anomaly is generally low, although it is substantially higher in the Tropics; its spatial reproducibility also markedly fluctuates in tandem with warm and cold phases of the El Nino/Southern Oscillation. However, the overall degree of reproducibility depends strongly on the particular land-surface anomaly considered. It is also shown that the predictability of a land-surface anomaly implied by its reproducibility statistics is consistent with what is inferred from more conventional predictability …
Date: October 22, 2004
Creator: Phillips, T J
Object Type: Article
System: The UNT Digital Library
Sustaining the Landscape: A Method for Comparing Current and Desired Future Conditions of Forest Ecosystems in the North Cumberland Plateau and Mountains (open access)

Sustaining the Landscape: A Method for Comparing Current and Desired Future Conditions of Forest Ecosystems in the North Cumberland Plateau and Mountains

This project initiates an integrated-landscape conservation approach within the Northern Cumberlands Project Area in Tennessee and Kentucky. The mixed mesophytic forests within the Cumberland Plateau and Mountains are among the most diverse in North America; however, these forests have been impacted by and remain threatened from changes in land use across this landscape. The integrated-landscape conservation approach presented in this report outlines a sequence of six conservation steps. This report considers the first three of these steps in two, successive stages. Stage 1 compares desired future conditions (DFCs) and current prevailing conditions (CPCs) at the landscape-scale utilizing remote sensing imagery, remnant forests, and descriptions of historical forest types within the Cumberland Plateau. Subsequently, Stage 2 compares DFCs and CPCs for at-risk forest types identified in Stage 1 utilizing structural, compositional, or functional attributes from USFS Forest Inventory and Analysis data. Ecological indicators will be developed from each stage that express the gaps between these two realizations of the landscape. The results from these first three steps will directly contribute to the final three steps of the integrated-landscape conservation approach by providing guidance for the generation of new conservation strategies in the Northern Cumberland Plateau and Mountains.
Date: December 22, 2004
Creator: Druckenbrod, D. L.
Object Type: Report
System: The UNT Digital Library
Ultrasonic Examination of Double-Shell Tank 241-SY-101. Examination Completed March 2004. (open access)

Ultrasonic Examination of Double-Shell Tank 241-SY-101. Examination Completed March 2004.

COGEMA Engineering Corporation (COGEMA), under a contract from CH2M Hill Hanford Group (CH2M Hill), has performed an ultrasonic nondestructive examination of selected portions of Double-Shell Tank 241-SY-101. The purpose of this examination was to provide information that could be used to evaluate the integrity of the wall of the primary tank. The requirements for the ultrasonic examination of Tank 241-SY-101 were to detect, characterize (identify, size, and locate), and record measurements made of any wall thinning, pitting, or cracks that might be present in the wall of the primary tank. Any measurements that exceed the requirements set forth in the Engineering Task Plan (ETP), RPP-17750 (Jensen 2003) and summarized on page 1 of this document, are reported to CH2M Hill and the Pacific Northwest National Laboratory (PNNL) for further evaluation. Under the contract with CH2M Hill, all data is to be recorded on disk and paper copies of all measurements are provided to PNNL for third-party evaluation. PNNL is responsible for preparing a report that describes the results of the COGEMA ultrasonic examinations.
Date: July 22, 2004
Creator: Pardini, Allan F. & Posakony, Gerald J.
Object Type: Report
System: The UNT Digital Library
Dynamic Load Balancing of Parallel Monte Carlo Transport Calculations (open access)

Dynamic Load Balancing of Parallel Monte Carlo Transport Calculations

The performance of parallel Monte Carlo transport calculations which use both spatial and particle parallelism is increased by dynamically assigning processors to the most worked domains. Since the particle work load varies over the course of the simulation, this algorithm determines each cycle if dynamic load balancing would speed up the calculation. If load balancing is required, a small number of particle communications are initiated in order to achieve load balance. This method has decreased the parallel run time by more than a factor of three for certain criticality calculations.
Date: December 22, 2004
Creator: O'Brien, M; Taylor, J & Procassini, R
Object Type: Article
System: The UNT Digital Library
Raman Scattering of Azafullerene C48N12 (open access)

Raman Scattering of Azafullerene C48N12

Raman scattering activities and Raman-active frequencies are reported for the minimum energy structure of azafullerene C{sub 48}N{sub 12} at the B3LYP/6-31G* level of theory. Analysis of the vibrational spectrum shows that the most intense IR and Raman bands are those associated with C-C vibrations, and that strong IR and Raman C-N vibrations occur below 1400 cm{sup -1}. Together with the recently reported infrared, optical absorption and x-ray spectroscopies, a complete identification of this cluster should now be feasible.
Date: September 22, 2004
Creator: Manaa, M R
Object Type: Article
System: The UNT Digital Library
Cable Design for Fast Ramped Superconducting Magnets (Cos-θ Design). (open access)

Cable Design for Fast Ramped Superconducting Magnets (Cos-θ Design).

The new heavy ion synchrotron facility proposed by GSI will have two superconducting magnet rings in the same tunnel, with rigidities of 300 T-m and 100 T-m. Fast ramp times are needed, which can cause significant problems for the magnets, particularly in the areas of ac loss and magnetic field distortion. The development of the low loss Rutherford cable that can be used is described, together with a novel insulation scheme designed to promote efficient cooling. Measurements of contact resistance in the cable are presented and the results of these measurements are used to predict the ac losses, in the magnets during fast ramp operation. For the high energy ring, a lm model dipole magnet was built, based on the RHIC dipole design. This magnet was tested under boiling liquid helium in a vertical cryostat. The quench current showed very little dependence on ramp rate. The ac losses, measured by an electrical method, were fitted to straight line plots of loss/cycle versus ramp rate, thereby separating the eddy current and hysteresis components. These results were compared with calculated values, using parameters which had previously been measured on short samples of cable. Reasonably good agreement between theory and experiment was found, …
Date: March 22, 2004
Creator: Ghosh, A.
Object Type: Article
System: The UNT Digital Library
Resolving the Nature of the LMC Microlensing Event LMC-5 (open access)

Resolving the Nature of the LMC Microlensing Event LMC-5

The authors present the results from an analysis of Hubble Space Telescope High Resolution Camera data for the Large Magellanic Cloud microlensing event MACHO-LMC-5. By determining the parallax and proper motion of this object they find that the lens is an M dwarf star at a distance of 578{sub -53}{sup +65}pc with a proper motion of 21.39 {+-} 0.04 mas/yr. Based on the kinematics and location of this star is it more likely to be part of the Galactic thick disk than thin disk population. They confirm that the microlensing event LMC-5 is a jerk-parallax microlensing event.
Date: April 22, 2004
Creator: Drake, A J; Cook, K H & Keller, S C
Object Type: Article
System: The UNT Digital Library
Concurrent Multiscale Simulation at Finite Temperature: Coarse-Grained Molecular Dynamics (open access)

Concurrent Multiscale Simulation at Finite Temperature: Coarse-Grained Molecular Dynamics

With the advent of nanotechnology, predictive simulations of nanoscale systems have become in great demand. In some cases nanoscale systems can be simulated directly at the level of atoms. The atomistic techniques used range from models based on a quantum mechanical treatment of the electronic bonds to those based on more empirical descriptions of the interatomic forces. In many cases, however, even nanoscale systems are too big for a purely atomistic approach, typically because the nanoscale device is coupled to its surroundings, and it is necessary to simulate the entire system comprising billions of atoms. A well-known example is the growth of nanoscale epitaxial quantum dots in which the size, shape and location of the dot is affected by the elastic strain developed in a large volume of the substrate as well as the local atomic bonding. The natural solution is to model the surroundings with a more coarse-grained description, suitable for the intrinsically longer length scale. The challenge then is to develop the computational methodology suitable for this kind of concurrent multiscale modeling, one in which the simulated length scale can be changed smoothly and seamlessly from one region of the simulation to another while maintaining the fidelity of …
Date: January 22, 2004
Creator: Rudd, R E
Object Type: Article
System: The UNT Digital Library
Evaluation Of Microdosing Strategies For Studies In Preclinical Drug Development: Demonstration Of Linear Pharmacokinetics In Dogs Of A Nucleoside Analogue Over A 50-Fold Dose Range (open access)

Evaluation Of Microdosing Strategies For Studies In Preclinical Drug Development: Demonstration Of Linear Pharmacokinetics In Dogs Of A Nucleoside Analogue Over A 50-Fold Dose Range

The technique of accelerator mass spectrometry (AMS) was validated successfully and utilized to study the pharmacokinetics and disposition in dogs of a preclinical drug candidate (Compound A), after oral and intravenous administration. The primary objective of this study was to examine whether Compound A displayed linear kinetics across sub-pharmacological (microdose) and pharmacological dose ranges in an animal model, prior to initiation of a human microdose study. The AMS-derived disposition properties of Compound A were comparable to data obtained via conventional techniques such as LC-MS/MS and liquid scintillation counting analyses. Thus, Compound A displayed multiphasic kinetics and possessed low plasma clearance (4.4 mL/min/kg), a long terminal elimination half-life (19.4 hr) and high oral bioavailability (82%). Currently there are no published comparisons of the kinetics of a pharmaceutical compound at pharmacological versus sub-pharmacological doses employing microdosing strategies. The present study thus provides the first description of the pharmacokinetics of a drug candidate assessed under these two dosing regimens. The data demonstrated that the pharmacokinetic properties of Compound A were similar following dosing at 0.02 mg/kg as at 1 mg/kg, indicating that in the case of Compound A, the kinetics of absorption, distribution and elimination in the dog appear to be linear across …
Date: April 22, 2004
Creator: Sandhu, P; Vogel, J S; Rose, M J; Ubick, E A; Brunner, J E; Wallace, M A et al.
Object Type: Article
System: The UNT Digital Library
Little Supersymmetry and the Supersymmetric Little Hierarchy Problem (open access)

Little Supersymmetry and the Supersymmetric Little Hierarchy Problem

The current experimental lower bound on the Higgs mass significantly restricts the allowed parameter space in most realistic supersymmetric models, with the consequence that these models exhibit significant fine-tuning. We propose a solution to this `supersymmetric little hierarchy problem'. We consider scenarios where the stop masses are relatively heavy - in the 500 GeV to a TeV range. Radiative stability of the Higgs soft mass against quantum corrections from the top quark Yukawa coupling is achieved by imposing a global SU(3) symmetry on this interaction. This global symmetry is only approximate - it is not respected by the gauge interactions. A subgroup of the global symmetry is gauged by the familiar SU(2) of the Standard Model. The physical Higgs is significantly lighter than the other scalars because it is the pseudo-Goldstone boson associated with the breaking of this symmetry. Radiative corrections to the Higgs potential naturally lead to the right pattern of gauge and global symmetry breaking. We show that both the gauge and global symmetries can be embedded into a single SU(6) grand unifying group, thereby maintaining the prediction of gauge coupling unification. Among the firm predictions of this class of models are new states with the quantum numbers …
Date: April 22, 2004
Creator: Birkedal, Andreas; Chacko, Z. & Gaillard, Mary K.
Object Type: Article
System: The UNT Digital Library
Design of a 2 Slot VLPC Cryostat Cooled by a Cryocooler (open access)

Design of a 2 Slot VLPC Cryostat Cooled by a Cryocooler

The conceptual design and preliminary engineering calculations have been completed for a two cassette cryostat. This report summarizes the design. A cryocooler is permanently mounted in the center of a stainless steel, 0.75 inch thick top lid. The cryocooler sits upon a spacer which raises the cooling stage elevations to favorably match the cassette heat intercept elevations. The top lid (32.0-inch outside diameter) mates to a 24-inch pipe size flange with o-ring. The 24-inch pipe size vacuum vessel with end plate has a minimum internal depth of 16-inch to give adequate clearance for the depth of the cryocooler and multilayer insulation blankets. Support stand legs elevate the container to a convenient height and allow for placement of the AFE power supply underneath. Two cassette slots are located on either side of the cryocooler. The slots are positioned parallel to each other, 10.5-inch center to center (6 standard cassette slot widths) so that the standard 8 slot AFE backplane can be used. The slot opening through the lid is approximately 1.422-inch x 16.782-inch. A 0.016-inch thick titanium (Ti-6AI-4V) envelope with sealing lip is inserted through lid and defines the gas helium boundary that the VLPC cassette resides. The internal dimensions of …
Date: April 22, 2004
Creator: Rucinski, Russell A.
Object Type: Report
System: The UNT Digital Library
Whole-Core Depletion Studies in Support of Fuel Specification for the Nextgeneration Nuclear Plant (NGNP) Core. (open access)

Whole-Core Depletion Studies in Support of Fuel Specification for the Nextgeneration Nuclear Plant (NGNP) Core.

None
Date: November 22, 2004
Creator: Kim, T. K.; Yang, W. S.; Taiwo, T. A. & Khalil, H. S.
Object Type: Report
System: The UNT Digital Library
Modeling Production Plant Forming Processes (open access)

Modeling Production Plant Forming Processes

Engineering has simulation tools and experience in modeling forming processes. Y-12 personnel have expressed interest in validating our tools and experience against their manufacturing process activities such as rolling, casting, and forging etc. We have demonstrated numerical capabilities in a collaborative DOE/OIT project with ALCOA that is nearing successful completion. The goal was to use ALE3D to model Alcoa's slab rolling process in order to demonstrate a computational tool that would allow Alcoa to define a rolling schedule that would minimize the probability of ingot fracture, thus reducing waste and energy consumption. It is intended to lead to long-term collaboration with Y-12 and perhaps involvement with other components of the weapons production complex. Using simulations to aid in design of forming processes can: decrease time to production; reduce forming trials and associated expenses; and guide development of products with greater uniformity and less scrap.
Date: September 22, 2004
Creator: Rhee, M; Becker, R; Couch, R & Li, M
Object Type: Report
System: The UNT Digital Library
Demonstration of Smart Building Controls to Manage Building Peak Loads: Innovative Non-Wires Technologies (open access)

Demonstration of Smart Building Controls to Manage Building Peak Loads: Innovative Non-Wires Technologies

As a part of the non-wires solutions effort, BPA in partnership with Pacific Northwest National Laboratory (PNNL) is exploring the use of two distributed energy resources (DER) technologies in the City of Richland. In addition to demonstrating the usefulness of the two DER technologies in providing peak demand relief, evaluation of remote direct load control (DLC) is also one of the primary objectives of this demonstration. The concept of DLC, which is used to change the energy use profile during peak hours of the day, is not new. Many utilities have had success in reducing demand at peak times to avoid building new generation. It is not the need for increased generation that is driving the use of direct load control in the Northwest, but the desire to avoid building additional transmission capacity. The peak times at issue total between 50 and 100 hours a year. A transmission solution to the problem would cost tens of millions of dollars . And since a ?non wires? solution is just as effective and yet costs much less, the capital dollars for construction can be used elsewhere on the grid where building new transmission is the only alternative. If by using DLC, the …
Date: December 22, 2004
Creator: Katipamula, Srinivas & Hatley, Darrel D.
Object Type: Report
System: The UNT Digital Library
Shared Communications: Volume 2. In-Depth Systems Research (open access)

Shared Communications: Volume 2. In-Depth Systems Research

This report is the second of two documents that examine the literature for actual examples of organizations and agencies that share communications resources. While the primary emphasis is on rural, intelligent transportation system (ITS) communications involving transit, examples will not be limited to rural activities, nor to ITS implementation, nor even to transit. In addition, the term ''communication'' will be broadly applied to include all information resources. The first document of this series, ''Shared Communications: Volume I. A Summary and Literature Review'', defines the meaning of the term ''shared communication resources'' and provides many examples of agencies that share resources. This document, ''Shared Communications: Volume II. In-Depth Systems Research'', reviews attributes that contributed to successful applications of the sharing communication resources concept. A few examples of each type of communication sharing are provided. Based on the issues and best practice realworld examples, recommendations for potential usage and recommended approaches for field operational tests are provided.
Date: September 22, 2004
Creator: Truett, LF
Object Type: Report
System: The UNT Digital Library
TRANSPORTATION SYSTEM REQUIREMENTS DOCUMENT (open access)

TRANSPORTATION SYSTEM REQUIREMENTS DOCUMENT

None
Date: December 22, 2004
Creator: /a, n
Object Type: Report
System: The UNT Digital Library
Broadband THz response of a resonantly excited high-densityexciton gas (open access)

Broadband THz response of a resonantly excited high-densityexciton gas

The density-driven crossover of electron-hole pairs frominsulating to conducting states is observed via the internal 1s-2pexciton resonance. Decreasing interparticle distance induces strongshifts and broadening, and ultimately the disappearance of the excitonicresonance.
Date: November 22, 2004
Creator: Huber, Rupert; Kaindl, Robert A.; Schmid, Benjamin A. & Chemla,Daniel S.
Object Type: Article
System: The UNT Digital Library
Shared Communications: Volume 1. A Summary and Literature Review (open access)

Shared Communications: Volume 1. A Summary and Literature Review

This paper provides a review of examples from the literature of shared communication resources and of agencies and/or organizations that share communication resources. The primary emphasis is on rural, intelligent transportation system communications involving transit. Citations will not be limited, however, to rural activities, or to ITS implementation, or even to transit. In addition, the term ''communication'' will be broadly applied to include all information resources. Literature references to issues that contribute to both successful and failed efforts at sharing communication resources are reviewed. The findings of this literature review indicate that: (1) The most frequently shared communication resources are information/data resources, (2) Telecommunications infrastructure and technologies are the next most frequently shared resources, (3) When resources are successfully shared, all parties benefit, (4) A few unsuccessful attempts of sharing resources have been recorded, along with lessons learned, (5) Impediments to sharing include security issues, concerns over system availability and reliability, service quality and performance, and institutional barriers, (6) Advantages of sharing include financial benefits to agencies from using shared resources and benefits to the public in terms of congestion mitigation, information transfer (e.g., traveler information systems), mobility (e.g., welfare-to-work paratransit), and safety (e.g., speed of incident response, incident avoidance), …
Date: September 22, 2004
Creator: Franzese, O
Object Type: Report
System: The UNT Digital Library
Femtosecond Near Edge X-ray Absorption Measurement of the VO2Phase Transition (open access)

Femtosecond Near Edge X-ray Absorption Measurement of the VO2Phase Transition

None
Date: July 22, 2004
Creator: Cavalleri, A.; Chong, H. H. W.; Fourmaux, S.; Glover, T. E.; Heimann, P. A; Kieffer, J. C. et al.
Object Type: Article
System: The UNT Digital Library
Report of the Solar and Atmospheric Neutrino Working Group (open access)

Report of the Solar and Atmospheric Neutrino Working Group

The highest priority of the Solar and Atmospheric Neutrino Experiment Working Group is the development of a real-time, precision experiment that measures the pp solar neutrino flux. A measurement of the pp solar neutrino flux, in comparison with the existing precision measurements of the high energy {sup 8}B neutrino flux, will demonstrate the transition between vacuum and matter-dominated oscillations, thereby quantitatively testing a fundamental prediction of the standard scenario of neutrino flavor transformation. The initial solar neutrino beam is pure {nu}{sub e}, which also permits sensitive tests for sterile neutrinos. The pp experiment will also permit a significantly improved determination of {theta}{sub 12} and, together with other solar neutrino measurements, either a measurement of {theta}{sub 13} or a constraint a factor of two lower than existing bounds. In combination with the essential pre-requisite experiments that will measure the {sup 7}Be solar neutrino flux with a precision of 5%, a measurement of the pp solar neutrino flux will constitute a sensitive test for non-standard energy generation mechanisms within the Sun. The Standard Solar Model predicts that the pp and {sup 7}Be neutrinos together constitute more than 98% of the solar neutrino flux. The comparison of the solar luminosity measured via neutrinos …
Date: October 22, 2004
Creator: Back, H.; Bahcall, J. N.; Bernabeu, J.; Boulay, M. G.; Bowles, T.; Calaprice, F. et al.
Object Type: Report
System: The UNT Digital Library
Development of a Novel Catalyst for NO Decomposition (open access)

Development of a Novel Catalyst for NO Decomposition

Air pollution arising from the emission of nitrogen oxides as a result of combustion taking place in boilers, furnaces and engines, has increasingly been recognized as a problem. New methods to remove NO{sub x} emissions significantly and economically must be developed. The current technology for post-combustion removal of NO is the selective catalytic reduction (SCR) of NO by ammonia or possibly by a hydrocarbon such as methane. The catalytic decomposition of NO to give N{sub 2} will be preferable to the SCR process because it will eliminate the costs and operating problems associated with the use of an external reducing species. The most promising decomposition catalysts are transition metal (especially copper)-exchanged zeolites, perovskites, and noble metals supported on metal oxides such as alumina, silica, and ceria. The main shortcoming of the noble metal reducible oxide (NMRO) catalysts is that they are prone to deactivation by oxygen. It has been reported that catalysts containing tin oxide show oxygen adsorption behavior that may involve hydroxyl groups attached to the tin oxide. This is different than that observed with other noble metal-metal oxide combinations, which have the oxygen adsorbing on the noble metal and subsequently spilling over to the metal oxide. This observation …
Date: October 22, 2004
Creator: Akyurtlu, Ates & Akyurtlu, Jale F.
Object Type: Report
System: The UNT Digital Library
Final Report for Sheet Beam Klystron Program (open access)

Final Report for Sheet Beam Klystron Program

The Phase I program demonstrated feasibility of the RF circuit, periodic permanent magnet focusing and beam transport. Computer simulations indicate that the device should meet the goals of the program with the anticipated power and efficiency. The electron gun is currently under construction in another program, and the collector is a simple design based on existing technology.
Date: September 22, 2004
Creator: Read, Michael; Ives, Lawrence & Phillips, Purobi
Object Type: Report
System: The UNT Digital Library
Secure password-based authenticated key exchange for web services (open access)

Secure password-based authenticated key exchange for web services

This paper discusses an implementation of an authenticated key-exchange method rendered on message primitives defined in the WS-Trust and WS-SecureConversation specifications. This IEEE-specified cryptographic method (AuthA) is proven-secure for password-based authentication and key exchange, while the WS-Trust and WS-Secure Conversation are emerging Web Services Security specifications that extend the WS-Security specification. A prototype of the presented protocol is integrated in the WSRF-compliant Globus Toolkit V4. Further hardening of the implementation is expected to result in a version that will be shipped with future Globus Toolkit releases. This could help to address the current unavailability of decent shared-secret-based authentication options in the Web Services and Grid world. Future work will be to integrate One-Time-Password (OTP) features in the authentication protocol.
Date: November 22, 2004
Creator: Liang, Fang; Meder, Samuel; Chevassut, Olivier & Siebenlist, Frank
Object Type: Article
System: The UNT Digital Library
Search for higgs, leptoquarks, and exotics at Tevatron (open access)

Search for higgs, leptoquarks, and exotics at Tevatron

This paper reviews some of the most recent results from the CDF and D0 experiments on the searches for Standard Model and Non-Standard Model Higgs bosons, and other new phenomena at the Tevatron. Both experiments examine data from proton anti-proton collision at {radical}s = 1.96 TeV, of integrated luminosity {approx} 200 pb{sup -1} (per experiment), to search for Higgs predicted in the Standard Model and beyond Standard Model, supersymmetric particles in the Gauge Mediated Symmetry Breaking scenario, leptoquarks, and excited electrons. No signal was observed, and limits on the signatures and models are derived.
Date: June 22, 2004
Creator: Wang, Song Ming
Object Type: Article
System: The UNT Digital Library