Resource Type

125 Matching Results

Results open in a new window/tab.

Status of Continuum Edge Gyrokinetic Code Physics Development (open access)

Status of Continuum Edge Gyrokinetic Code Physics Development

We are developing an edge gyro-kinetic continuum simulation code to study the boundary plasma over a region extending from inside the H-mode pedestal across the separatrix to the divertor plates. A 4-D ({psi}, {theta}, {epsilon}, {mu}) version of this code is presently being implemented, en route to a full 5-D version. A set of gyrokinetic equations[1] are discretized on computational grid which incorporates X-point divertor geometry. The present implementation is a Method of Lines approach where the phase-space derivatives are discretized with finite differences and implicit backwards differencing formulas are used to advance the system in time. A fourth order upwinding algorithm is used for particle cross-field drifts, parallel streaming, and acceleration. Boundary conditions at conducting material surfaces are implemented on the plasma side of the sheath. The Poisson-like equation is solved using GMRES with multi-grid preconditioner from HYPRE. A nonlinear Fokker-Planck collision operator from STELLA[2] in ({nu}{sub {parallel}},{nu}{sub {perpendicular}}) has been streamlined and integrated into the gyro-kinetic package using the same implicit Newton-Krylov solver and interpolating F and dF/dt|{sub coll} to/from ({epsilon}, {mu}) space. With our 4D code we compute the ion thermal flux, ion parallel velocity, self-consistent electric field, and geo-acoustic oscillations, which we compare with standard neoclassical …
Date: May 31, 2005
Creator: Xu, X Q; Xiong, Z; Dorr, M R; Hittinger, J A; Kerbel, G D; Nevins, W M et al.
System: The UNT Digital Library
Structural Studies on Dy to 119 GPa and Applications to Lanthanide Systematics (open access)

Structural Studies on Dy to 119 GPa and Applications to Lanthanide Systematics

The Rare Earth elements (REE) are known to undergo crystallographic as well as electronic structure changes with applied pressure. On increasing pressure, the trivalent lanthanides follow the sequence hcp {yields} Sm-type {yields} dhcp {yields} fcc {yields} dfcc. In this report we present room-temperature high-pressure x-ray diffraction data for Dy as well as our observations on the post-dfcc phases and concomitant volume changes in the heavy REE.
Date: May 31, 2005
Creator: Patterson, J & Akella, J
System: The UNT Digital Library
Class B0631+519: Last of the Class Lenses (open access)

Class B0631+519: Last of the Class Lenses

We report the discovery of the new gravitational lens system CLASS B0631+519. Imaging with the VLA, MERLIN and the VLBA reveals a doubly-imaged flat-spectrum radio core, a doubly-imaged steep-spectrum radio lobe and possible quadruply-imaged emission from a second lobe. The maximum separation between the lensed images is 1.16 arcsec. High resolution mapping with the VLBA at 5 GHz resolves the most magnified image of the radio core into a number of sub-components spread across approximately 20 mas. No emission from the lensing galaxy or an odd image is detected down to 0.31 mJy (5{sigma}) at 8.4 GHz. Optical and near-infrared imaging with the ACS and NICMOS cameras on the HST show that there are two galaxies along the line of sight to the lensed source, as previously discovered by optical spectroscopy. We find that the foreground galaxy at z=0.0896 is a small irregular, and that the other, at z=0.6196 is a massive elliptical which appears to contribute the majority of the lensing effect. The host galaxy of the lensed source is detected in the HST near-infrared imaging as a set of arcs, which form a nearly complete Einstein ring. Mass modeling using non-parametric techniques can reproduce the near-infrared observations and …
Date: May 31, 2005
Creator: York, Tom; Jackson, N.; Browne, I. W. A.; Koopmans, L. V. E.; McKean, J. P.; Norbury, M. A. et al.
System: The UNT Digital Library
Workforce Planning and Analytics (open access)

Workforce Planning and Analytics

None
Date: May 31, 2005
Creator: More, J & Presta, C
System: The UNT Digital Library
Simultaneous Thermal Stability and Ultrahigh Sensitivity of Heterojunction SERS Substrates (open access)

Simultaneous Thermal Stability and Ultrahigh Sensitivity of Heterojunction SERS Substrates

Paper reports the design of Ag-Al2O3-Ag heterojunctions based on Ag nanorods (AgNRs) and their applications as thermally stable and ultrasensitive substrates of surface-enhanced Raman scattering (SERS).
Date: May 31, 2019
Creator: Ma, Lingwei; Wang, Jinke; Huang, Hanchen; Zhang, Zhengjun; Li, Xiaogang & Fan, Yi
System: The UNT Digital Library
The Russian Federal Information System for Nuclear Material Control and Accounting: Yesterday, Today and Tomorrow (open access)

The Russian Federal Information System for Nuclear Material Control and Accounting: Yesterday, Today and Tomorrow

Most enterprises in the Russian Federation are not prepared to report to the Russian Federal Nuclear Material Control and Accounting Information System (FIS) by the full function reporting method. The full function reporting method requires reporting inventory listings on a schedule based on nuclear material category, submission of individual inventory change reports, and reconciliation and closeout at the end of each reporting period. Most Russian enterprises do not have automated systems and do not have the resources to develop and implement such systems. Over the last two years, MinAtom put the regulations and national level nuclear material control and accounting (MC&A) software in place to require all enterprises in the Russian Federation to report summarized inventory listings to the FIS in January 2002. Enterprises do not need automated systems to comply with summarized reporting requirements. Along with the approximately 25% of the total Category 1 Material Balance Areas (MBAs) using full function reporting, the addition of this complete summarized inventory makes the FIS a more valuable tool for MinAtom management. The FIS is now poised to complete the work by improving the integrity and reliability of the data through increasing the number of enterprises and MBAs using full function reporting. …
Date: May 31, 2002
Creator: Martyanov, A. A.; Pitel, V. A.; Berchik, V. P.; Kasumova, L. A.; Babcock, R. A.; Kilmartin, W. E. et al.
System: The UNT Digital Library
Accounting Procedures for Foreign-owned Nuclear Material Located Temporarily in the Russian Federation (open access)

Accounting Procedures for Foreign-owned Nuclear Material Located Temporarily in the Russian Federation

None
Date: May 31, 2005
Creator: Pitel, V. A.; Kasumova, L. A. & Babcock, R. A.
System: The UNT Digital Library
Barriers to Food Security and Community Stress in an Urban Food Desert (open access)

Barriers to Food Security and Community Stress in an Urban Food Desert

This article describes how residents in urban food deserts access food, the barriers they experience in accessing nutritious, affordable food, and how community food insecurity exacerbates prior social, built, and economic stressors.
Date: May 31, 2018
Creator: Crowe, Jessica; Lacy, Constance & Columbus, Yolanda
System: The UNT Digital Library
CYP1B1 expression, a potential risk factor for breast cancer (open access)

CYP1B1 expression, a potential risk factor for breast cancer

CYP1B1 expression in non-tumor breast tissue from breast cancer patients and cancer-free individuals was determined to test the hypothesis that high CYP1B1 expression is a risk factor for breast cancer. Large interindividual variations in CYP1B1 expression were found with CYP1B1 levels notably higher in breast cancer patients than cancer-free individuals. The results indicate that CYP1B1 might play a role in breast cancer either through increased PAH activation or through metabolism of endogenous estrogen to a carcinogenic derivative.
Date: May 31, 2001
Creator: Goth-Goldstein, Regine; Erdmann, Christine A. & Russell, Marion
System: The UNT Digital Library
Making industrial energy efficiency mainstream and profitable: Where public benefit and private interests intersect (open access)

Making industrial energy efficiency mainstream and profitable: Where public benefit and private interests intersect

In 1996, the US Department of Energy s Office of Industrial Technologies (OIT) Motor Challenge program began a unique collaboration with industry called the Allied Partner program. Partnerships were sought with equipment suppliers and manufacturers, utilities, consultants, and state agencies that had extensive existing relationships with industrial customers. Partners were neither paid nor charged a fee for participation. The assumption was that these relationships could serve as the foundation for conveying a motor system efficiency message to many more industrial facilities than could be reached through a typical government-to-end-user program model. A substantial effort was made to engage industrial suppliers in delivering program information as part of their customer interactions. A recent independent evaluation of the Motor Challenge program attributes $16.9 million or nearly 67 percent of the total annual program energy savings to the efforts of Allied Partners in the first three years of operation.In 1997, the Compressed Air Challenge(R) (CAC) was developed as an outgrowth of the partnership concept. In this model, OIT is one of 15 sponsors who collaborated to create a national program of compressed air system training. The CAC has gone a step further by setting up a development and deployment model based on shared …
Date: May 31, 2001
Creator: McKane, Aimee T.; Tutterow, Vestal & Cockrill, Chris
System: The UNT Digital Library
Comparison of Field-Scale Effective Properties of Two-Phase Flow in Heterogeneous Porous Media Obtained by Stochastic Analysis and Numerical Experiments (open access)

Comparison of Field-Scale Effective Properties of Two-Phase Flow in Heterogeneous Porous Media Obtained by Stochastic Analysis and Numerical Experiments

The effects of subsurface heterogeneity on two-phase flow can be observed from the characterization functions of field-scale effective relative permeability and capillary pressure with respect to mean saturation. Numerical experiments were used to evaluate such effective properties of two-phase flow in a heterogeneous medium with properties representing the Borden Aquifer, and compared with the results of stochastic analysis developed using a spectral perturbation technique that employs a stationary, stochastic representation of the spatial variability of soil properties. Arbitrary forms of the relative permeability and capillary pressure characteristic functions with respect to saturation can be used in the theoretical analysis and numerical code. A statistical scaling procedure, which is a generalization of Leverett scaling, was developed for the relationship between intrinsic permeability and two capillary parameters. The procedure for estimating the effective properties of two-phase flow using numerical simulation consists of three-steps. Firstly, a local-scale heterogeneous system with random fields of intrinsic permeability and two capillary parameters was generated. Secondly, numerical simulation of single-phase flow in the system, with different sets of flow boundary conditions for different directions, was performed; the field-scale effective saturated hydraulic conductivity tensor was calculated on the basis of the mean Darcy law. The tensor obtained numerically …
Date: May 31, 2002
Creator: Zhou, Quanlin; Gelhar, Lynn W. & Jacobs, Bruce
System: The UNT Digital Library
A dedicated storage ring for Far-IR coherent synchrotron radiation at the ALS (open access)

A dedicated storage ring for Far-IR coherent synchrotron radiation at the ALS

We present the concepts for a storage ring dedicated to and optimized for the production of stable coherent synchrotron radiation (CSR) over the far-infrared wavelength range from about 200 microns to 1 mm.
Date: May 31, 2002
Creator: Barry, W. C.; Baptist, K. M.; Benjegerdes, R. J.; Biocca, A. K.; Byrd, J. M.; Byrne, W. E. et al.
System: The UNT Digital Library
Forming and smoothing D{sub 2} and HD layers for ICF by infra-red heating (open access)

Forming and smoothing D{sub 2} and HD layers for ICF by infra-red heating

We describe a technique to form and smooth uniform solid D{sub 2}, HD or DT layers for inertial confinement fusion targets. Pumping the infrared (IR) collision induced vibration-rotation band generates a bulk heating of the solid. Shadowgraphs reveal that this bulk heat quickly redistributes the solid into a relatively uniform layer depending on the IR intensity profile. Measured redistribution time constants are used to determine the conversion efficiency of IR light into bulk heat. Phase shifting interferometry reveals that the surface roughness decreases with increasing IR heating.
Date: May 31, 1996
Creator: Collins, G.W.; Tiszauer, D.; Feit, M.; Mapoles, E.R.; Bernat, T.P.; Bittner, D.N. et al.
System: The UNT Digital Library
Modular redundant number systems (open access)

Modular redundant number systems

With the increased use of public key cryptography, faster modular multiplication has become an important cryptographic issue. Almost all public key cryptography, including most elliptic curve systems, use modular multiplication. Modular multiplication, particularly for the large public key modulii, is very slow. Increasing the speed of modular multiplication is almost synonymous with increasing the speed of public key cryptography. There are two parts to modular multiplication: multiplication and modular reduction. Though there are fast methods for multiplying and fast methods for doing modular reduction, they do not mix well. Most fast techniques require integers to be in a special form. These special forms are not related and converting from one form to another is more costly than using the standard techniques. To this date it has been better to use the fast modular reduction technique coupled with standard multiplication. Standard modular reduction is much more costly than standard multiplication. Fast modular reduction (Montgomery`s method) reduces the reduction cost to approximately that of a standard multiply. Of the fast multiplication techniques, the redundant number system technique (RNS) is one of the most popular. It is simple, converting a large convolution (multiply) into many smaller independent ones. Not only do redundant number …
Date: May 31, 1998
Creator: unknown
System: The UNT Digital Library
Design and reality for NIF ignition targets (open access)

Design and reality for NIF ignition targets

Advances in ICF experiments and modeling have led to improved understanding of the growth of instabilities during capsule implosion and the effects on capsule performance. This has led to more refined specifications on the characteristics of igniting capsules, all of which have solid D-T fuel layers. These specifications involve a trade-off between the interior ice surface structure, outer capsule surface structure, and time-dependent drive asymmetry.
Date: May 31, 1996
Creator: Bernat, T.P.
System: The UNT Digital Library
Developing shape analysis tools to assist complex spatial decision making (open access)

Developing shape analysis tools to assist complex spatial decision making

The objective of this research was to develop and implement a shape identification measure within a geographic information system, specifically one that incorporates analytical modeling for site location planning. The application that was developed incorporated a location model within a raster-based GIS, which helped address critical performance issues for the decision support system. Binary matrices, which approximate the object`s geometrical form, are passed over the grided data structure and allow identification of irregular and regularly shaped objects. Lastly, the issue of shape rotation is addressed and is resolved by constructing unique matrices corresponding to the object`s orientation
Date: May 31, 1996
Creator: Mackey, H. E.; Ehler, G. B. & Cowen, D.
System: The UNT Digital Library
Trends in emissions of acidifying species in Asia, 1985-1997. (open access)

Trends in emissions of acidifying species in Asia, 1985-1997.

Acid deposition is a serious problem throughout much of Asia. Emissions of sulfur dioxide (SO{sub 2}) and nitrogen oxides (NO{sub x}) have been increasing steadily, as nations strive to increase their levels of economic development. Coal and fuel oil have been the main choices for powering industrial development; and, until recently, only a few countries (notably Japan and Taiwan) had taken significant steps to avert the atmospheric emissions that accompany fuel combustion. This paper discusses trends in emissions of SO{sub 2} and NO{sub x} that have occurred in Asian countries in the period 1985--1997, using results from the RAINS-ASIA computer model and energy-use trends from the IEA Energy Statistics and Balances database. Emissions of SO{sub 2} in Asia grew from 26.6 Tg in 1985 to 33.7 Tg in 1990 and to 39.2 Tg in 1997. Though SO{sub 2} emissions used to grow as fast as fossil-fuel use, recent limitations on the sulfur content of coal and oil have slowed the growth. The annual-average emissions growth between 1990 and 1997 was only 1.1%, considerably less than the economic growth rate. Emissions of NO{sub x}, on the other hand, continue to grow rapidly, from 14.1 Tg in 1985 to 18.7 Tg in …
Date: May 31, 2000
Creator: Streets, D. G.; Tsai, N. Y.; Akimoto, H. & Oka, K.
System: The UNT Digital Library
Corrosion performance of structural alloys in coal-combustion environments. (open access)

Corrosion performance of structural alloys in coal-combustion environments.

None
Date: May 31, 2000
Creator: Natesan, K.; Mathur, M. & Freeman, M.
System: The UNT Digital Library
Adaptive Position and Orientation Regulation for the Camera-in-hand Problem (open access)

Adaptive Position and Orientation Regulation for the Camera-in-hand Problem

None
Date: May 31, 2001
Creator: Setlur, P
System: The UNT Digital Library
The D-Zero Run II Detector and physics prospects (open access)

The D-Zero Run II Detector and physics prospects

The DO Detector at Fermilab is currently undergoing an extensive upgrade to participate in the Run II data taking which shall begin on March 1, 2001. The design of the detector meets the requirements of the high luminosity environment provided by the accelerator. This paper describes the upgraded detector subsystems and gives a brief outline of the physics prospects associated with the upgrade.
Date: May 31, 2001
Creator: Parashar, Neeti
System: The UNT Digital Library
Thermal characterization of Li-ion cells using calorimetric techniques (open access)

Thermal characterization of Li-ion cells using calorimetric techniques

The thermal stability of Li-ion cells with intercalating carbon anodes and metal oxide cathodes was measured as a function of state of charge and temperature for two advanced cell chemistries. Cells of the 18650 design with Li{sub x}CoO{sub 2} cathodes (commercial Sony cells) and Li{sub x}Ni{sub 0.8}Co{sub 0.2}O{sub 2} cathodes were measured for thermal reactivity. Accelerating rate calorimetry (ARC) was used to measure cell thermal runaway as a function of state of charge (SOC), microcalorimetry was used to measure the time dependence of thermal output, and differential scanning calorimetry (DSC) was used to study the thermal reactivity of the individual components. Thermal decomposition of the anode solid electrolyte interphase (SEI) layer occurred at low temperatures and contributes to the initiation of thermal runaway. Low temperature reactions from 40 C--70 C were observed during the ARC runs that were SOC dependent. These reactions measured in the microcalorimeter decayed over time with power-law dependence and were highly sensitive to SOC and temperature. ARC runs of aged and cycled cells showed complete absence of these low-temperature reactions but showed abrupt exothermic spikes between 105--135 C. These results suggest that during aging the anode SEI layer is decomposing from a metastable state to a …
Date: May 31, 2000
Creator: ROTH,EMANUEL P.
System: The UNT Digital Library
Automating the search for answers to open questions (open access)

Automating the search for answers to open questions

This article provides evidence for the arrival of automated reasoning. Indeed, one of its primary goals of the early 1960s has been reached: The use of an automated reasoning program frequently leads to significant contributions to mathematics and to logic. In addition, although not clearly an original objective, the use of such a program now plays an important role for chip design and for program verification. That importance can be sharply increased; indeed, in this article the authors discuss the possible value of automated reasoning to finding better designs of chips, circuits, and computer code. They also provide insight into the mechanisms--in particular, strategy--that have led to numerous successes. To complement the evidence they present and to encourage further research, the offer challenges and open questions for consideration. They include a glimpse of the future and some commentary on the possibly unexpected benefits of automating the search for answers to open questions.
Date: May 31, 2000
Creator: Wos, L. & Fitelson, B.
System: The UNT Digital Library
Shielding analysis for the MDAS facility. (open access)

Shielding analysis for the MDAS facility.

None
Date: May 31, 2000
Creator: Klann, R. T. & Grimm, K. N.
System: The UNT Digital Library
Appendix: Conjectures concerning proof, design, and verification. (open access)

Appendix: Conjectures concerning proof, design, and verification.

This article focuses on an esoteric but practical use of automated reasoning that may indeed be new to many, especially those concerned primarily with verification of both hardware and software. Specifically, featured are a discussion and some methodology for taking an existing design -- of a circuit, a chip, a program, or the like--and refining and improving it in various ways. Although the methodology is general and does not require the use of a specific program, McCune's program OTTER does offer what is needed. OTTER has played and continues to play the key role in my research, and an interested person can gain access to this program in various ways, not the least of which is through the included CD-ROM in [3]. When success occurs, the result is a new design that may require fewer components, avoid the use of certain costly components, offer more reliability and ease of verification, and, perhaps most important, be more efficient in the contexts of speed and heat generation. Although the author has minimal experience in circuit design, circuit validation, program synthesis, program verification, and similar concerns, (at the encouragement of colleagues based on successes to be cited) he presents materials that might indeed …
Date: May 31, 2000
Creator: Wos, L.
System: The UNT Digital Library