Mechanical Behavior and Fractography of 304 Stainless Steel with High Hydrogen Concentration (open access)

Mechanical Behavior and Fractography of 304 Stainless Steel with High Hydrogen Concentration

Hydrogen embrittlement of 304 stainless steel with different hydrogen concentrations has been investigated. An electrochemical technique was used to effectively charge the high level of hydrogen into 304 stainless steel in a short period of time. At 25 ppm of hydrogen, 304 stainless steel loses 10 percent of its original mechanical strength and 20 percent plasticity. Although the ductile feature dominates the fractography, the brittle crown area near the outer surface shows the intergranular rupture effected by hydrogen. At 60 ppm of hydrogen, 304 stainless steel loses 23 percent of its strength and 38 percent plasticity, where the brittle mode dominates the fracture of the materials. Experimental results show that hydrogen damage to the performance of 304 stainless steel is significant even at very low levels. The fractograph analysis indicates the high penetration ability of hydrogen in 304 stainless steel. This work also demonstrates the advantages of the electrochemical charging technique in the study of hydrogen embrittlement.
Date: February 5, 2003
Creator: Au, M.
System: The UNT Digital Library
Effects of Point Sources in Trench Disposal of Radioactive Waste (open access)

Effects of Point Sources in Trench Disposal of Radioactive Waste

At the U. S. Department of Energy Savannah River Site, disposal of radioactive wastes in shallow trenches was simulated with vadose zone models and decoupled aquifer models. The vadose zone models provided contaminant fluxes to the aquifer models.
Date: February 5, 2003
Creator: Collard, L.B.
System: The UNT Digital Library
Introduction to heavy meson decays and CP asymmetries (open access)

Introduction to heavy meson decays and CP asymmetries

These lectures are intended to provide an introduction to heavy meson decays and CP violation. The first lecture contains a brief review of the standard model and how the CKM matrix and CP violation arise, mixing and CP violation in neutral meson systems, and explanation of the cleanliness of the sin 2{beta} measurement. The second lecture deals with the heavy quark limit, some applications of heavy quark symmetry and the operator product expansion for exclusive and inclusive semileptonic B decays. The third lecture concerns with theoretically clean CP violation measurements that may become possible in the future, and some developments toward a better understanding of nonleptonic B decays. The conclusions include a subjective best buy list for the near future.
Date: February 5, 2003
Creator: Ligeti, Zoltan
System: The UNT Digital Library
The CDF data handling system (open access)

The CDF data handling system

The Collider Detector at Fermilab (CDF) records proton-antiproton collisions at center of mass energy of 2.0 TeV at the Tevatron collider. A new collider run, Run II, of the Tevatron started in April 2001. Increased luminosity will result in about 1 PB of data recorded on tapes in the next two years. Currently the CDF experiment has about 260 TB of data stored on tapes. This amount includes raw and reconstructed data and their derivatives. The data storage and retrieval are managed by the CDF Data Handling (DH) system. This system has been designed to accommodate the increased demands of the Run II environment and has proven robust and reliable in providing reliable flow of data from the detector to the end user. This paper gives an overview of the CDF Run II Data Handling system which has evolved significantly over the course of this year. An outline of the future direction of the system is given.
Date: November 5, 2003
Creator: Litvintsev, Dmitry O.
System: The UNT Digital Library
Hash sorter - firmware implementation and an application for the Fermilab BTeV level 1 trigger system (open access)

Hash sorter - firmware implementation and an application for the Fermilab BTeV level 1 trigger system

A hardware hash sorter for the Fermilab BTeV Level 1 trigger system will be presented. The has sorter examines track-segment data before the data are sent to a system comprised of 2500 Level 1 processors, and rearranges the data into bins based on the slope of track segments. They have found that by using the rearranged data, processing time is significantly reduced allowing the total number of processors required for the Level 1 trigger system to be reduced. The hash sorter can be implemented in an FPGA that is already included as part of the design of the trigger system. Hash sorting has potential applications in a broad area in trigger and DAQ systems. It is a simple O(n) process and is suitable for FPGA implementation. Several implementation strategies will also be discussed in this document.
Date: November 5, 2003
Creator: al., Jinyuan Wu et
System: The UNT Digital Library
Introduction to heavy meson decays and CP asymmetries (open access)

Introduction to heavy meson decays and CP asymmetries

These lectures are intended to provide an introduction to heavy meson decays and CP violation. The first lecture contains a brief review of the standard model and how the CKM matrix and CP violation arise, mixing and CP violation in neutral meson systems, and explanation of the cleanliness of the sin 2{beta} measurement. The second lecture deals with the heavy quark limit, some applications of heavy quark symmetry and the operator product expansion for exclusive and inclusive semileptonic B decays. The third lecture concerns with theoretically clean CP violation measurements that may become possible in the future, and some developments toward a better understanding of nonleptonic B decays. The conclusions include a subjective best buy list for the near future.
Date: February 5, 2003
Creator: Ligeti, Zoltan
System: The UNT Digital Library
RF impedance measurements on the DARHT-II accelerator intercell assembly (open access)

RF impedance measurements on the DARHT-II accelerator intercell assembly

We report upon recent experimental measurements made of RF properties of the intercell assembly of the second axis accelerator[1] of Dual Axis Radiographic Hydrodynamic Test (DARHT) facility at LANL. The intercells provide both pumping and diagnostic access to the main DARHT-II beamline. Their design includes a pumping plenum separated from the main beam pipe by return current rods together with RF shielding provided by a copper-coated stainless steel mesh. Measurements using the twin lead technique (see Ref. [2]) at low frequencies (f < 200 MHz) suggest a constant value for the ratio h of the radial and azimuthal magnetic field components to which the transverse impedance is linearly related. We find that these results compare favorably to predictions from a simple analytic, lumped circuit model which includes the effects of the mesh and return current rods. We also present RF loop-to-loop frequency scans above beam pipe cutoff ({approx}600 MHz) showing the existence of many RF modes with relatively high Q's.
Date: May 5, 2003
Creator: Fawley, William M.; Eylon, Shmuel & Briggs, Richard
System: The UNT Digital Library
Study of indium and solder bumps for the BTeV Pixel Detector (open access)

Study of indium and solder bumps for the BTeV Pixel Detector

The pixel detector proposed for the BTeV experiment at the Fermilab Tevatron will use bump-bonding technology based on either Indium or Pb/Sn solder to connect the front-end readout chips to the silicon pixel sensors. We have studied the strength of the bumps by visual inspection of the bumps bonding silicon sensor modules to dummy chips made out of glass. The studies were done before and after thermal cycles, exposed to intense irradiation, and with the assemblies glued to a graphite substrate. We have also carried out studies on effects of temperature changes on both types of bump bonds by observing the responses of single-chip pixel detectors to an Sr{sup 90} source. We report the results from these studies and our plan to measure the effect of cryogenic temperatures on the bumps.
Date: November 5, 2003
Creator: al., Simon W Kwan et
System: The UNT Digital Library
Heavy quarks and lattice QCD (open access)

Heavy quarks and lattice QCD

This paper is a review of heavy quarks in lattice gauge theory, focusing on methodology. It includes a status report on some of the calculations that are relevant to heavy-quark spectroscopy and to flavor physics.
Date: November 5, 2003
Creator: Kronfeld, Andreas S.
System: The UNT Digital Library
Pixel multichip module design for a high energy physics experiment (open access)

Pixel multichip module design for a high energy physics experiment

At Fermilab, a pixel detector multichip module is being developed for the BTeV experiment. The module is composed of three layers. The lowest layer is formed by the readout integrated circuits (ICs). The back of the ICs is in thermal contact with the supporting structure, while the top is flip-chip bump-bonded to the pixel sensor. A low mass flex-circuit interconnect is glued on the top of this assembly, and the readout IC pads are wire-bounded to the circuit. This paper presents recent results on the development of a multichip module prototype and summarizes its performance characteristics.
Date: November 5, 2003
Creator: al., Guilherme Cardoso et
System: The UNT Digital Library
Cross platform SCA component using C++ builder and KYLIX (open access)

Cross platform SCA component using C++ builder and KYLIX

A cross-platform component for EPICS Simple Channel Access (SCA) has been developed. EPICS client programs with GUI become portable at their C++ source-code level both on Windows and Linux by using Borland C++ Builder 6 and Kylix 3 on these platforms respectively.
Date: May 5, 2003
Creator: Nishimura, Hiroshi; Timossi, Chiris & McDonald, James L.
System: The UNT Digital Library
ALS user meeting features 10th anniversary celebration (open access)

ALS user meeting features 10th anniversary celebration

The Advanced Light Source (ALS) saw first light on October 5, 1993, not quite to the day but close to 10 years before the 2003 ALS Users Association meeting, held October 6-8. Fittingly, the proceedings included retrospectives from two of the key players in the early history of the ALS, David Attwood and Jay Marx, and a display of photographs chronicling its construction and commissioning. Science highlights, highlights from young researchers, and posters constituted the meat of the program on Monday and Tuesday morning, while workshops took over Tuesday afternoon and all day Wednesday.
Date: December 5, 2003
Creator: Robinson, Art
System: The UNT Digital Library
Studies of the N=90 region: The decay of 154Eu to 154Gd (open access)

Studies of the N=90 region: The decay of 154Eu to 154Gd

The decay of {sup 154}Eu {yields} {sup 154}Gd has been studied by {gamma}-ray singles and {gamma}-{gamma} coincidence spectroscopy using an array of 20 Compton-suppressed Ge detectors. The primary goal of the work was to confirm or refute a large number of questionable features in the decay scheme: the outcome is the removal of 8 levels from the previously adopted scheme, with the result that a new type of collective band is revealed. Many weak decay branches for the decay are clarified. These results are critical for understanding the structure of {sup 154}Gd and the N = 90 isotones; and the improved completeness of the decay scheme contributes to the use of {sup 154}Eu as a metrological standard.
Date: December 5, 2003
Creator: Kulp, W. D.; Wood, J. L.; Krane, K. S.; Loats, J.; Schmelzenbach, P.; Stapels, C. J. et al.
System: The UNT Digital Library
Atomic resolution of lithium ions in LiCoO{sub 2} (open access)

Atomic resolution of lithium ions in LiCoO{sub 2}

LiCoO{sub 2} is the most common lithium storage material used as positive electrode in lithium rechargeable batteries. Ordering of lithium and vacancies has a profound effect on the physical properties of Li{sub x}CoO{sub 2} and the electrochemical performances of lithium batteries. An exit surface wave (ESW) phase image reconstructed from experimental images obtained on the LBNL One-Angstrom Microscope (OAM) shows all three types of atoms in LiCoO{sub 2}.
Date: June 5, 2003
Creator: Shao-Horn, Yang; Croguennec, Laurence; Delmas, Claude; Nelson, E. Chris & O'Keefe, Michael A.
System: The UNT Digital Library
Miscoding properties of 1,N{sup 6}-ethanoadenine, a DNA adduct derived from reaction with antitumor agent 1,3-bis(2-chloroethyl)-1-nitrosourea (open access)

Miscoding properties of 1,N{sup 6}-ethanoadenine, a DNA adduct derived from reaction with antitumor agent 1,3-bis(2-chloroethyl)-1-nitrosourea

1,N{sup 6}-Ethanoadenine (EA) is an exocyclic adduct formed from DNA reaction with the antitumor agent, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). To understand the role of this adduct in the mechanism of mutagenicity or carcinogenicity by BCNU, an oligonucleotide with a site-specific EA was synthesized using phosphoramidite chemistry. We now report the in vitro miscoding properties of EA in translesion DNA synthesis catalyzed by mammalian DNA polymerases (pols) {alpha}, {beta}, {eta} and {iota}. These data were also compared with those obtained for the structurally related exocyclic adduct, 1,N{sup 6}-ethenoadenine ({var_epsilon}A). Using a primer extension assay, both pols {alpha} and {beta} were primarily blocked by EA or {var_epsilon}A with very minor extension. Pol {eta} a member of the Y family of polymerases, was capable of catalyzing a significant amount of bypass across both adducts. Pol {eta} incorporated all four nucleotides opposite EA and {var_epsilon}A, but with differential preferences and mainly in an error-prone manner. Human pol {iota}, a paralog of human pol {eta}, was blocked by both adducts with a very small amount of synthesis past {var_epsilon}A. It incorporated C and, to a much lesser extent, T, opposite either adduct. In addition, the presence of an A adduct, e.g. {var_epsilon}A, could affect the specificity of …
Date: March 5, 2003
Creator: Hang, Bo; Guliaev, Anton B.; Chenna, Ahmed & Singer, B.
System: The UNT Digital Library
Efficient airflow design for cleanrooms improves business bottom lines (open access)

Efficient airflow design for cleanrooms improves business bottom lines

Based on a review of airflow design factors and in-situ energy measurements in ISO Cleanliness Class-5 cleanrooms, this paper addresses the importance of energy efficiency in airflow design and opportunities of cost savings in cleanroom practices. The paper discusses design factors that can long lastingly affect cleanroom system performance, and demonstrates benefits of energy efficient cleanroom design from viewpoints of environmental control and business operations. The paper suggests that a high performance cleanroom should not only be effective in contamination control, but also be efficient in energy and environmental performance. The paper also suggests that energy efficient design practice stands to bring in immediate capital cost savings and operation cost savings, and should be regarded by management as a strategy to improve business bottom lines.
Date: January 5, 2003
Creator: Xu, Tengfang
System: The UNT Digital Library
Working out the kinks: Understanding the fall and rise of energy use in China (open access)

Working out the kinks: Understanding the fall and rise of energy use in China

The causes of the decline in China's energy consumption between 1996 and 2000 are analyzed.
Date: March 5, 2003
Creator: Fridley, David G.; Sinton, Jonathan E. & Lewis, Joanna I.
System: The UNT Digital Library
A Particle Tracking Approach to Simulating Transport in a Complex Fracture (open access)

A Particle Tracking Approach to Simulating Transport in a Complex Fracture

None
Date: March 5, 2003
Creator: Tsang, Chin-Fu & Doughty, Christine
System: The UNT Digital Library
Instrumentation optimization for positron emission mammography (open access)

Instrumentation optimization for positron emission mammography

The past several years have seen designs for PET cameras optimized to image the breast, commonly known as Positron Emission Mammography or PEM cameras. The guiding principal behind PEM instrumentation is that a camera whose field of view is restricted to a single breast has higher performance and lower cost than a conventional PET camera. The most common geometry is a pair of parallel planes of detector modules, although geometries that encircle the breast have also been proposed. The ability of the detector modules to measure the depth of interaction (DOI) is also a relevant feature. This paper finds that while both the additional solid angle coverage afforded by encircling the breast and the decreased blurring afforded by the DOI measurement improve performance, the ability to measure DOI is more important than the ability to encircle the breast.
Date: June 5, 2003
Creator: Moses, William W. & Qi, Jinyi
System: The UNT Digital Library
Association between severity of prescribed burns and subsequent activity of conifer-infesting beetles in stands of longleaf pine (open access)

Association between severity of prescribed burns and subsequent activity of conifer-infesting beetles in stands of longleaf pine

A randomized complete block experiment was performed to measure the effect of prescribed, dormant-season burns of three different levels of severity (measured as fuel consumption and soil surface heating) on subsequent insect infestation and mortality of mature longleaf pine (Pinus palustris Mill.). Multiple-funnel traps baited with a low release rate of turpentine and ethanol were used to monitor activity of certain coniferophagous beetles. Non-aggressive species, including the root beetles Hylastes salebrosus Eichhoff and H. tenuis Eichhoff, the ambrosia beetle Xyleborus pubescens Zimmermann, the reproduction weevil Pachylobius picivorus (Germar), and buprestid borers, were attracted to burned plots in numbers that correlated positively with burn severity. Beetle attraction to burned sites was greatest in the first weeks post-burn and disappeared by the second year. Two potential tree-killing bark beetles, Dendroctonus terebrans (Olivier) and Ips grandicollis (Eichhoff), were trapped in significant numbers but exhibited no attraction to burned plots. Tree mortality correlated significantly with the severity of the burns and amounted to 5% of stems in the hottest burn treatment after 3 years. The majority of the mortality was observed in the second and third years post-burn. Attacks of Ips and Dendroctonus bark beetles were apparent on nearly all dead or dying trees, …
Date: May 5, 2003
Creator: Sullivan, Brian, T; Fettig, C. J.; Otrosina, William, J.; Dalusky, Mark, J. & Berrisford, C.W.
System: The UNT Digital Library
NON-DESTRUCTIVE IN SITU SOIL CARBON ANALYSIS: PRINCIPLE AND RESULTS. (open access)

NON-DESTRUCTIVE IN SITU SOIL CARBON ANALYSIS: PRINCIPLE AND RESULTS.

Global warming is promoted by anthropogenic CO{sub 2} emissions into the atmosphere, while at the same time it is partially mitigated by carbon sequestration by terrestrial ecosystems. However, improvement in the understanding and monitoring of below ground carbon processes is essential for evaluating strategies for carbon sequestration including quantification of carbon stores for credits. A system for non-destructive in situ carbon monitoring in soil, based on inelastic neutron scattering (INS), is described. The system can be operated in stationary or scanning mode and measures soil to depth of approximately 30 cm. There is a good agreement between results obtained from INS and standard chemical analysis of soil cores collected from the same study site.
Date: May 5, 2003
Creator: WIELOPOLSKI, L.; MITRA, S.; HENDREY, G.; ROGERS, H.; TORBERT, A. & PRIOR, S.
System: The UNT Digital Library
International Benchmarking and Conference on Women in Physics (open access)

International Benchmarking and Conference on Women in Physics

International benchmarking and conference on women in physics.
Date: February 5, 2003
Creator: Franz, Judy R.
System: The UNT Digital Library
Finding Text Information in the Ocean of Electronic Documents (open access)

Finding Text Information in the Ocean of Electronic Documents

Information management in natural resources has become an overwhelming task. A massive amount of electronic documents and data is now available for creating informed decisions. The problem is finding the relevant information to support the decision-making process. Determining gaps in knowledge in order to propose new studies or to determine which proposals to fund for maximum potential is a time-consuming and difficult task. Additionally, available data stores are increasing in complexity; they now may include not only text and numerical data, but also images, sounds, and video recordings. Information visualization specialists at Pacific Northwest National Laboratory (PNNL) have software tools for exploring electronic data stores and for discovering and exploiting relationships within data sets. These provide capabilities for unstructured text explorations, the use of data signatures (a compact format for the essence of a set of scientific data) for visualization (Wong et al 2000), visualizations for multiple query results (Havre et al. 2001), and others (http://www.pnl.gov/infoviz ). We will focus on IN-SPIRE, a MS Windows vision of PNNL’s SPIRE (Spatial Paradigm for Information Retrieval and Exploration). IN-SPIRE was developed to assist information analysts find and discover information in huge masses of text documents.
Date: February 5, 2003
Creator: Medvick, Patricia A. & Calapristi, Augustin J.
System: The UNT Digital Library
Electronic and magnetic properties of zincblende half-metal superlattices (open access)

Electronic and magnetic properties of zincblende half-metal superlattices

Zincblende half-metallic compounds such as CrAs, with large magnetic moments and high Curie temperatures, are promising materials for spintronic applications. They explore layered materials, consisting of alternating layers of zincblende half-metals, by first principles calculations, and find that superlattices of (CrAs){sub 1}(MnAs){sub 1} and (CrAs){sub 2}(MnAs){sub 2} are half-metallic with magnetic moments of 7.0{mu}{sub B} and 14.0{mu}{sub B} per unit cell, respectively. They discuss the nature of the bonding and half-metallicity in these materials and, based on the understanding acquired, develop a simple expression for the magnetic moment in such materials. They explore the range of lattice constants over which half-metallicity is manifested, and suggest corresponding substrates for growth in thin film form.
Date: November 5, 2003
Creator: Fong, C Y; Qian, M C; Pask, J; Yang, L H & Dag, S
System: The UNT Digital Library