ATW neutronics design studies. (open access)

ATW neutronics design studies.

The Accelerator Transmutation of Waste (ATW) concept has been proposed as a transuranics (TRU) (and long-lived fission product) incinerator for processing the 87,000 metric tonnes of Light Water Reactor used fuel which will have been generated by the time the currently deployed fleet of commercial reactors in the US reach the end of their licensed lifetime. The ATW is proposed to separate the uranium from the transuranics and fission products in the LWR used fuel, to fission the transuranics, to send the LWR and ATW generated fission products to the geologic repository and to send the uranium to either a low level waste disposal site or to save it for future use. The heat liberated in fissioning the transuranics would be converted to electricity and sold to partially offset the cost of ATW construction and operations. Options for incineration of long-lived fission products are under evaluation. A six-year science-based program of ATW trade and system studies was initiated in the US FY 2000 to achieve two main purposes: (1) ''to evaluate ATW within the framework of nonproliferation, waste management, and economic considerations,'' and (2) ''to evaluate the efficacy of the numerous technical options for ATW system configuration.'' This paper summarizes …
Date: November 10, 2000
Creator: Wade, D. C.; Yang, W. S. & Khalil, H.
Object Type: Article
System: The UNT Digital Library
Design and modeling of cylindrical and falt-wound lithium-ion cells for the PNGV application. (open access)

Design and modeling of cylindrical and falt-wound lithium-ion cells for the PNGV application.

In this study, 10-Ah cylindrical and flat-wound cells were designed and studied for use in batteries for the Partnership for a New Generation of Vehicles (PNGV). A low-cost current collection system was devised that results in a low resistance. Heat rejection from flat cells is much better than that from cylindrical cells and is an important safety factor. Very compact, powerful batteries of about 1.5 kW/L can be designed with wound lithium-ion cells.
Date: November 10, 2000
Creator: Nelson, P. A.; Henriksen, G. L. & Amine, K.
Object Type: Article
System: The UNT Digital Library
An evaluation of Java's I/O capabilities for high-performance computing. (open access)

An evaluation of Java's I/O capabilities for high-performance computing.

Java is quickly becoming the preferred language for writing distributed applications because of its inherent support for programming on distributed platforms. In particular, Java provides compile-time and run-time security, automatic garbage collection, inherent support for multithreading, support for persistent objects and object migration, and portability. Given these significant advantages of Java, there is a growing interest in using Java for high-performance computing applications. To be successful in the high-performance computing domain, however, Java must have the capability to efficiently handle the significant I/O requirements commonly found in high-performance computing applications. While there has been significant research in high-performance I/O using languages such as C, C++, and Fortran, there has been relatively little research into the I/O capabilities of Java. In this paper, we evaluate the I/O capabilities of Java for high-performance computing. We examine several approaches that attempt to provide high-performance I/O--many of which are not obvious at first glance--and investigate their performance in both parallel and multithreaded environments. We also provide suggestions for expanding the I/O capabilities of Java to better support the needs of high-performance computing applications.
Date: November 10, 2000
Creator: Dickens, P. M. & Thakur, R.
Object Type: Article
System: The UNT Digital Library
Latency, bandwidth, and concurrent issue limitations in high-performance CFD. (open access)

Latency, bandwidth, and concurrent issue limitations in high-performance CFD.

To achieve high performance, a parallel algorithm needs to effectively utilize the memory subsystem and minimize the communication volume and the number of network transactions. These issues gain further importance on modern architectures, where the peak CPU performance is increasing much more rapidly than the memory or network performance. In this paper, we present some performance enhancing techniques that were employed on an unstructured mesh implicit solver. Our experimental results show that this solver adapts reasonably well to the high memory and network latencies.
Date: November 10, 2000
Creator: Gropp, W. D.; Kaushik, D. K.; Keyes, D. E. & Smith, B. F.
Object Type: Article
System: The UNT Digital Library
Liquid-lithium cooling for 100-kW ISOL and fragmentation targets. (open access)

Liquid-lithium cooling for 100-kW ISOL and fragmentation targets.

Advanced exotic beam facilities that are currently being developed will use powerful driver accelerator for the production of short-lived rare isotopes. Multi-beam-drivers capable of producing high power beams from very light to very heavy ions are now technically feasible. A challenge for such facilities is the development of production targets to be used for a variety of reaction mechanisms with beam powers of about 100 kilowatts. This paper presents engineering concepts that have been developed recently for using liquid lithium coolant for two types of targets, one for use with light-ion beams on high atomic number (Z) targets and the other for heavy-ion beams on low-Z targets.
Date: November 10, 2000
Creator: Nolen, J. A. & Reed, C. B.,Hassanein, A.,Gomes, I. C.
Object Type: Article
System: The UNT Digital Library
SCHe Helium Bottles and Associated Isolation Valves (open access)

SCHe Helium Bottles and Associated Isolation Valves

None
Date: November 10, 2000
Creator: Miska, C. R.
Object Type: Report
System: The UNT Digital Library
Shadowing effects on vector boson production (open access)

Shadowing effects on vector boson production

We explore how nuclear modifications to the nucleon structure functions, shadowing, affect massive gauge boson production in heavy ion collisions at different impact parameters. We calculate the dependence of Z{sup 0}, W{sup +} and W{sup -} production on rapidity and impact parameter to next-to-leading order in Pb+Pb collisions at 5.5 TeV/nucleon to study quark shadowing at high Q{sup 2}. We also compare our Pb+Pb results to the pp rapidity distributions at 14 TeV.
Date: November 10, 2000
Creator: Vogt, R.
Object Type: Article
System: The UNT Digital Library
Speaker verification using combined acoustic and EM sensor signal processing (open access)

Speaker verification using combined acoustic and EM sensor signal processing

Low Power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference. This greatly enhances the quality and quantity of information for many speech related applications. See Holzrichter, Burnett, Ng, and Lea, J. Acoustic. SOC. Am . 103 ( 1) 622 (1998). By combining the Glottal-EM-Sensor (GEMS) with the Acoustic-signals, we've demonstrated an almost 10 fold reduction in error rates from a speaker verification system experiment under a moderate noisy environment (-10dB).
Date: November 10, 2000
Creator: Ng, L C; Gable, T J & Holzrichter, J F
Object Type: Article
System: The UNT Digital Library
7th ICFA mini-workshop on high intensity high brightness hadron beams (open access)

7th ICFA mini-workshop on high intensity high brightness hadron beams

None
Date: October 10, 2000
Creator: Mokhov, Nikolai V. & Chou, Weiren
Object Type: Article
System: The UNT Digital Library
Application of constrained-layer damping to a precision kinematic coupling (open access)

Application of constrained-layer damping to a precision kinematic coupling

This paper addresses the need to support a very precise optical instrument while causing essentially no influence to its natural shape. Such influences could come from a number of sources, such as manufacturing tolerances, temperature changes, over-constrained structural members, or ground motion. Kinematic couplings have long been used for purposes of repeatable location and minimal influence to the supported object, however these couplings typically offer very little damping. This paper presents a kinematic coupling that utilizes constrained-layer damping techniques to damp out the first three modes of vibration of a precision optical instrument. Finite element analysis was used to aid in the design and tuning of the dampers for the kinematic coupling. Experimental tests were conducted and confirmed the effectiveness of the dampers. The quality factor (Q), which measure the amplification at resonance, dropped from 33.3 to 5.9 on the first mode, from 156.3 to 7.1 on the second mode, and from 147.1 to 18.5 on the third mode. These dampers help to ensure that the stringent vibration requirements necessary to produce high quality optical images are met.
Date: October 10, 2000
Creator: Jensen, S A & Hale, L C
Object Type: Article
System: The UNT Digital Library
Applications of disorder-induced concept to critical-solute-accumulation processes. (open access)

Applications of disorder-induced concept to critical-solute-accumulation processes.

A generalized version of the Lindemann melting criterion has recently been used to develop a unified thermodynamic description of disorder-induced amorphization and heat-induced melting. This concept of amorphization as a melting process is based on the fact that the melting temperature of a defective crystal driven far from equilibrium will decrease relative to that of its defect-free equilibrium state. The broader view of melting provides a new perspective of damage-accumulation processes such as radiation damage, ion implantation, ion beam mixing, plastic deformation, and fracture. For example, within this conceptual framework, disorder-induced amorphization is simply polymorphous melting of a critically disordered crystal at temperatures below the glass transition temperature. In the present communication, we discuss the application of the concept to two specific cases: amorphous phase formation during ion implantation and solute segregation-induced intergranular fracture.
Date: October 10, 2000
Creator: Lam, N. Q.; Okamoto, P. R. & Heuer, J. K.
Object Type: Article
System: The UNT Digital Library
Argonne National Laboratory ATLAS Accelerator tune archiving system. (open access)

Argonne National Laboratory ATLAS Accelerator tune archiving system.

None
Date: October 10, 2000
Creator: Munson, F. & Quock, D.
Object Type: Article
System: The UNT Digital Library
Atomistic simulations of point defects in Zr-Ni intermetallic compounds. (open access)

Atomistic simulations of point defects in Zr-Ni intermetallic compounds.

None
Date: October 10, 2000
Creator: Moura, C. S.; Motta, A. T.; Lam, N. Q. & Amaral, L.
Object Type: Article
System: The UNT Digital Library
B physics at CDF (open access)

B physics at CDF

From 1992 to 1995 the CDF experiment has taken 110 pb{sup {minus}1} of p{anti p} collisions at a center-of-mass energy of 1.8 TeV. These data gave rise to a variety of important B physics measurements. Most importantly B mass, lifetime and mixing measurements, the observation of the last missing meson, the B{sub c}, and a measurement of the CP violation parameter sin 2{beta}. The highlights of those results are described and a perspective for the upcoming Run II period is given.
Date: October 10, 2000
Creator: Paus, Christoph
Object Type: Article
System: The UNT Digital Library
The CDF silicon vertex tracker (open access)

The CDF silicon vertex tracker

Real time pattern recognition is becoming a key issue in many position sensitive detector applications. The CDF collaboration is building SVT: a specialized electronic device designed to perform real time track reconstruction using the silicon vertex detector (SVX II). This will strongly improve the CDF capability of triggering on events containing b quarks, usually characterized by the presence of a secondary vertex. SVT is designed to reconstruct in real time charged particles trajectories using data coming from the Silicon Vertex detector and the Central Outer Tracker drift chamber. The SVT architecture and algorithm have been specially tuned to minimize processing time without degrading parameter resolution.
Date: October 10, 2000
Creator: al., A. Cerri et
Object Type: Article
System: The UNT Digital Library
Charm and beauty production and polarization at CDF (open access)

Charm and beauty production and polarization at CDF

In this paper the authors present results on Charm and Beauty production as well as on production and polarization of Quarkonia at {radical}s = 1.8 TeV. These results were obtained from data taken with the CDF detector at Fermilab. They cover recently completed analyses of the 1992--96 collider run.
Date: October 10, 2000
Creator: Papadimitriou, Vaia
Object Type: Article
System: The UNT Digital Library
China energy, environment, and climate study: Background issues paper (open access)

China energy, environment, and climate study: Background issues paper

The total costs and impacts of expanding energy use in China will depend, in part, on a number of important factors, an understanding of which is vital for China's policy-makers. These issues include the additional environmental and public health impacts associated with energy use, the economic costs of infrastructure expansion to meet growing energy needs, and the potential role that renewable energy technologies could play if pushed hard in China's energy future. This short report summarizes major trends and issues in each of these three areas.
Date: October 10, 2000
Creator: Sinton, Jonathan E.; Fridley, David G.; Logan, Jeffrey; Guo, Yuan; Wang, Bangcheng & Xu, Qing
Object Type: Report
System: The UNT Digital Library
Color transparency and pion valence quark distributions from di-jet events in Fermilab E791 (open access)

Color transparency and pion valence quark distributions from di-jet events in Fermilab E791

Diffractive, exclusive di-jet events produced by 500 GeV/c {pi}{sup {minus}} scattered off nuclei were used to measure their A-dependence, and to make the first direct measurement of the valence-quark momentum distribution in pions. Data on the latter are compared to two limiting predictions for the pion light-cone wave-function. The results show that the asymptotic wave-function of perturbative QCD describes the data well for Q{sup 2} of 10 GeV{sup 2} and above. The measured A-dependence is consistent with observation of point-like configurations in the pion and color-transparency calculations.
Date: October 10, 2000
Creator: Appel, Jeffrey A.
Object Type: Article
System: The UNT Digital Library
Contemporary applications of Dyson-Schwinger equations. (open access)

Contemporary applications of Dyson-Schwinger equations.

None
Date: October 10, 2000
Creator: Hecht, M. B. & Roberts, C. D.Schmidt, S. M.
Object Type: Article
System: The UNT Digital Library
Dark matter distribution in the universe and ultra-high energy cosmic rays (open access)

Dark matter distribution in the universe and ultra-high energy cosmic rays

Two of the greatest mysteries of modern physics are the origin of the dark matter in the universe and the nature of the highest energy particles in the cosmic ray spectrum. The authors discuss here possible direct and indirect connections between these two problems, with particular attention to two cases: in the first they study the local clustering of possible sources of ultra-high energy cosmic rays (UHECRs) driven by the local dark matter overdensity. In the second case they study the possibility that UHECRs are directly generated by the decay of weakly unstable super heavy dark matter.
Date: October 10, 2000
Creator: Blasi, Pasquale
Object Type: Article
System: The UNT Digital Library
DRIVING G-MODE PULSATIONS IN GAMMA DORADUS VARIABLES (open access)

DRIVING G-MODE PULSATIONS IN GAMMA DORADUS VARIABLES

The {gamma} Doradus stars are a newly-discovered class of gravity-mode pulsators which lie just at or beyond the red edge of the {delta} Scuti instability strip. We present the results of calculations which predict pulsation instability of high-order g-modes with periods between 0.4 and 3 days, as observed in these stars. The pulsations are driven by the modulation of radiative flux by convection at the base of a deep envelope convection zone. Pulsation instability is predicted only for models with temperatures at the convection zone base between {approximately}200,000 and {approximately}480,000 K. The estimated shear dissipation due to turbulent viscosity within the convection zone, or in an overshoot region below the convection zone, can be comparable to or even exceed the predicted driving, and is likely to reduce the number of unstable modes, or possibly to quench the instability. Additional refinements in the pulsation modeling are required to determine the outcome. A few Doradus stars have been observed that also pulsate in {delta} Scuti-type p-modes, and at least two others have been identified as chemically peculiar. Since our calculated driving region is relatively deep, Doradus pulsations are not necessarily incompatible with surface abundance peculiarities or with {delta} Scuti p-mode pulsations driven …
Date: October 10, 2000
Creator: GUZIK, J.; KAYE, A. & AL, ET
Object Type: Article
System: The UNT Digital Library
The effect of bulk composition on swelling and radiation-induced segregation in austenitic alloys. (open access)

The effect of bulk composition on swelling and radiation-induced segregation in austenitic alloys.

None
Date: October 10, 2000
Creator: Allen, T. R.; Cole, J. I.; Dietz, N. L.; Wang, Y.; Was, G. S. & Kenik, E. A.
Object Type: Article
System: The UNT Digital Library
Emittance measurements at the A0 photo-injector (open access)

Emittance measurements at the A0 photo-injector

The A0 photo-injector produces electron bunches of 1--14 nC charge with an energy of 18 MeV. Detailed measurements and optimization of emittance have been carried out for a number of gun and laser operating conditions, beam line optics conditions, and at a number of beam line locations. Results are compared with the predictions of simulations using HOMDYN.
Date: October 10, 2000
Creator: Carneiro, Jean-Paul
Object Type: Article
System: The UNT Digital Library
Evaluation of Brine Inflow at the Waste Isolation Pilot Plant (open access)

Evaluation of Brine Inflow at the Waste Isolation Pilot Plant

None
Date: October 10, 2000
Creator: KNOWLES,M. KATHRYN & ECONOMY,KATHY M.
Object Type: Article
System: The UNT Digital Library