Supporting Dynamic Ad hoc Collaboration Capabilities (open access)

Supporting Dynamic Ad hoc Collaboration Capabilities

Modern HENP experiments such as CMS and Atlas involve as many as 2000 collaborators around the world. Collaborations this large will be unable to meet often enough to support working closely together. Many of the tools currently available for collaboration focus on heavy-weight applications such as videoconferencing tools. While these are important, there is a more basic need for tools that support connecting physicists to work together on an ad hoc or continuous basis. Tools that support the day-to-day connectivity and underlying needs of a group of collaborators are important for providing light-weight, non-intrusive, and flexible ways to work collaboratively. Some example tools include messaging, file-sharing, and shared plot viewers. An important component of the environment is a scalable underlying communication framework. In this paper we will describe our current progress on building a dynamic and ad hoc collaboration environment and our vision for its evolution into a HENP collaboration environment.
Date: July 14, 2003
Creator: Agarwal, Deborah A. & Berket, Karlo
System: The UNT Digital Library
Measured energy savings from the application of reflective roofsin 2 small non-residential buildings (open access)

Measured energy savings from the application of reflective roofsin 2 small non-residential buildings

Energy use and environmental parameters were monitored in two small (14.9 m{sup 2}) non-residential buildings during the summer of 2000. The buildings were initially monitored for about 1 1/2 months to establish a base condition. The roofs of the buildings were then painted with a white coating and the monitoring was continued. The original solar reflectivities of the roofs were about 26%; after the application of roof coatings the reflectivities increased to about 72%. The monitored electricity savings were about 0.5kWh per day (33 Wh/m2 per day). The estimated annual savings are about 125kWh per year (8.4 kWh/m2); at a cost of $0.1/kWh, savings are about $0.86/m2 per year. Obviously, it costs significantly more than this amount to coat the roofs with reflective coating, particularly because of the remote locations of these buildings. However, since the prefabricated roofs are already painted green at the factory, painting them a white (reflective) color would bring no additional cost. Hence, a reflective roof saves energy at no incremental cost.
Date: January 14, 2003
Creator: Akbari, Hashem
System: The UNT Digital Library
Comparison of Experimental and Model Data for the Evaporation of a Synthetic Topopah Spring Tuff Pore Water, Yucca Mountain, NV (open access)

Comparison of Experimental and Model Data for the Evaporation of a Synthetic Topopah Spring Tuff Pore Water, Yucca Mountain, NV

The evaporation of a range of synthetic pore water solutions representative of the potential high-level-nuclear-waste repository at Yucca Mountain, NV is being investigated. The motivation of this work is to understand and predict the range of brine compositions that may contact the waste containers from evaporation of pore waters, because these brines could form corrosive thin films on the containers and impact their long-term integrity. A relatively complex synthetic Topopah Spring Tuff pore water was progressively concentrated by evaporation in a closed vessel, heated to 95 C in a series of sequential experiments. Periodic samples of the evaporating solution were taken to determine the evolving water chemistry. According to chemical divide theory at 25 C and 95 C our starting solution should evolve towards a high pH carbonate brine. Results at 95 C show that this solution evolves towards a complex brine that contains about 99 mol% Na{sup +} for the cations, and 71 mol% Cl{sup -}, 18 mol% {Sigma}CO{sub 2}(aq), 9 mol% SO{sub 4}{sup 2-} for the anions. Initial modeling of the evaporating solution indicates precipitation of aragonite, halite, silica, sulfate and fluoride phases. The experiments have been used to benchmark the use of the EQ3/6 geochemical code in …
Date: October 14, 2003
Creator: Alai, M; Sutton, M & Carroll, S
System: The UNT Digital Library
Tracking down the origin of Arc plasma science. I. Early pulsed and oscillating discharges (open access)

Tracking down the origin of Arc plasma science. I. Early pulsed and oscillating discharges

None
Date: January 14, 2003
Creator: Anders, Andre
System: The UNT Digital Library
Tracking down the origin of Arc plasma science. II. Early continuous discharges (open access)

Tracking down the origin of Arc plasma science. II. Early continuous discharges

None
Date: January 14, 2003
Creator: Anders, Andre
System: The UNT Digital Library
A Dynamically Adaptive Arbitrary Lagrangian-Eulerian Method for Solution of the Euler Equations (open access)

A Dynamically Adaptive Arbitrary Lagrangian-Eulerian Method for Solution of the Euler Equations

A new method that combines staggered grid arbitrary Lagrangian-Eulerian (ALE) techniques with structured local adaptive mesh refinement (AMR) has been developed for solution of the Euler equations. The novel components of the methods are driven by the need to reconcile traditional AMR techniques with the staggered variables and moving, deforming meshes associated with Lagrange based ALE schemes. We develop interlevel solution transfer operators and interlevel boundary conditions first in the case of purely Lagrangian hydrodynamics, and then extend these ideas into an ALE method by developing adaptive extensions of elliptic mesh relaxation techniques. Conservation properties of the method are analyzed, and a series of test problem calculations are presented which demonstrate the utility and efficiency of the method.
Date: February 14, 2003
Creator: Anderson, R W; Elliott, N S & Pember, R B
System: The UNT Digital Library
Modeling water seepage into heated waste emplacement drifts at Yucca Mountain (open access)

Modeling water seepage into heated waste emplacement drifts at Yucca Mountain

This paper describes numerical prediction of the coupled thermal-hydrological processes (TH) in the vicinity of waste emplacement drifts during the heating phase of the proposed geologic repository for nuclear waste at Yucca Mountain, Nevada. Heating of rock water to above-boiling conditions induces water saturation changes and perturbed water fluxes that affect the potential of water seepage into drifts. In addition to the capillary barrier at the rock-drift interface--independent of the thermal conditions--a second barrier exists to downward percolation at above-boiling conditions. This barrier is caused by vaporization of water in the fractured rock overlying the repository. A TOUGH2 simulation model was developed to analyze the combined effect of these two barriers; it accounts for all relevant TH processes in response to heating, while incorporating the capillary barrier condition at the drift wall. Model results are presented for a variety of simulation cases.
Date: April 14, 2003
Creator: Birkholzer, Jens; Mukhophadhyay, Sumit & Tsang, Yvonne
System: The UNT Digital Library
Far-infrared absorption in GaAs:Te liquid phase epitaxial films (open access)

Far-infrared absorption in GaAs:Te liquid phase epitaxial films

None
Date: May 14, 2003
Creator: Cardozo, B. L.; Haller, E. E.; Reichertz, L. A. & Beeman, J. W.
System: The UNT Digital Library
The effect of CO2(aq), Al(aq) and temperature on feldspar dissolution (open access)

The effect of CO2(aq), Al(aq) and temperature on feldspar dissolution

The authors measured labradorite (Ca{sub 0.6}Na{sub 0.4}Al{sub 1.6}Si{sub 2.4}O{sub 8}) dissolution rates using a mixed flow reactor from 30 to 130 C as a function of CO{sub 2} (3 x 10{sup -3} and 0.6 M), and aluminum (10{sup -6} to 10{sup -3}M) at pH 3.2. Over these conditions, labradorite dissolution can be described with a single rate expression that accounts for observed increases in dissolution rate with temperature and decreases in dissolution rate with dissolved aluminum: Rate{sub Si} (mol Labradorite cm{sup -2} s{sup -1}) = k{double_prime} x 10{sup -Ea/2.303RT} [(a{sub H{sup +}}{sup 3n}/a{sub Al{sup 3+}}{sup n})K{sub T}/(1+K{sub T} (a{sub H{sup +}}{sup 3n}/a{sub Al{sup 3+}}{sup n}))] where the apparent dissolution rate constant, k{double_prime} = 10{sup -5.69} (mol Labradorite cm{sup -2}s{sup -1}); the net activation energy, E{sub a} = 10.06 (kcal mol{sup -1}); H{sup +}-Al{sup 3+} exchange coefficient, n = 0.31; and silica rich surface complex formation constant K{sub T} = 4.5 to 5.6 from 30 to 130 C. The effect of CO{sub 2}(aq) on mineral dissolution is accounted for by changes in solution pH. At temperatures below 60 C, labradorite dissolves incongruently with preferential dissolution of Na, Ca and Al over Si.
Date: October 14, 2003
Creator: Carroll, S. & Knauss, K.
System: The UNT Digital Library
Mercury-Free Dissolution of Aluminum-Based Nuclear Material: From Basic Science to the Plant (open access)

Mercury-Free Dissolution of Aluminum-Based Nuclear Material: From Basic Science to the Plant

Conditions were optimized for the first plant-scale dissolution of an aluminum-containing nuclear material without using mercury as a catalyst. This nuclear material was a homogeneous mixture of plutonium oxide and aluminum metal that had been compounded for use as the core matrix in Mark 42 nuclear fuel. Because this material had later failed plutonium distribution specifications, it was rejected for use in the fabrication of Mark 42 fuel tubes, and was stored at the Savannah River Site (SRS) awaiting disposition. This powder-like material was composed of a mixture of approximately 80 percent aluminum and 11 percent plutonium. Historically, aluminum-clad spent nuclear fuels [13] have been dissolved using a mercuric nitrate catalyst in a nitric acid (HNO3) solution to facilitate the dissolution of the bulk aluminum cladding. Developmental work at SRS indicated that the plutonium oxide/aluminum compounded matrix could be dissolved without mercury. Various mercury-free conditions were studied to evaluate the rate of dissolution of the Mark 42 compact material and to assess the corrosion rate to the stainless steel dissolver. The elimination of mercury from the dissolution process fit with waste minimization and industrial hygiene goals to reduce the use of mercury in the United States. The mercury-free dissolution technology …
Date: May 14, 2003
Creator: Crooks, W. J., III
System: The UNT Digital Library
Modeling Fluid Flow and Electrical Resistivity in Fractured Geothermal Reservoir Rocks (open access)

Modeling Fluid Flow and Electrical Resistivity in Fractured Geothermal Reservoir Rocks

Phase change of pore fluid (boiling/condensing) in rock cores under conditions representative of geothermal reservoirs results in alterations of the electrical resistivity of the samples. In fractured samples, phase change can result in resistivity changes that are more than an order of magnitude greater than those measured in intact samples. These results suggest that electrical resistivity monitoring may provide a useful tool for monitoring the movement of water and steam within fractured geothermal reservoirs. We measured the electrical resistivity of cores of welded tuff containing fractures of various geometries to investigate the resistivity contrast caused by active boiling and to determine the effects of variable fracture dimensions and surface area on water extraction. We then used the Nonisothermal Unsaturated Flow and Transport model (NUFT) (Nitao, 1998) to simulate the propagation of boiling fronts through the samples. The simulated saturation profiles combined with previously reported measurements of resistivity-saturation curves allow us to estimate the evolution of the sample resistivity as the boiling front propagates into the rock matrix. These simulations provide qualitative agreement with experimental measurements suggesting that our modeling approach may be used to estimate resistivity changes induced by boiling in more complex systems.
Date: January 14, 2003
Creator: Detwiler, R. L.; Roberts, J. J.; Ralph, W. & Bonner, B. P.
System: The UNT Digital Library
Investigation of layered intergrowth Li{sub x}M{sub y}Mn{sub 1-y}O{sub 2+z} (M=Ni,Co,Al) compounds as positive electrodes for Li-ion batteries (open access)

Investigation of layered intergrowth Li{sub x}M{sub y}Mn{sub 1-y}O{sub 2+z} (M=Ni,Co,Al) compounds as positive electrodes for Li-ion batteries

Layered substituted lithium manganese oxides suitable for use as lithium ion battery electrodes may be prepared from the corresponding sodium manganese metal oxide compounds by ion-exchange. Stacking arrangements (O2, O3, or O2/O3 intergrowths) in the lithiated materials are dependent upon the Na/transition metal ratio in the sodium-containing precursors, the degree of substitution, and the identity of the substituting metal. O3 layered materials deliver up to 200 mAh/g at moderate current densities in lithium cell configurations, but convert rapidly to spinels upon cell cycling, while O2 compounds are more stable but deliver less capacity. Intergrowths show intermediate behavior, with higher capacities than pure O2 materials and better phase stability than O3 compounds. Some intergrowth structures do not appear to convert to spinel during normal cycling, suggesting it may be possible to tailor high energy density, phase stable layered manganese oxide electrodes for lithium batteries.
Date: July 14, 2003
Creator: Dolle, M.; Hollingsworth, J.; Richardson, T. J. & Doeff, M. M.
System: The UNT Digital Library
Optimal use of information for measuring M(t) in lepton + jets t anti-t events (open access)

Optimal use of information for measuring M(t) in lepton + jets t anti-t events

The observation of the top (t) quark served as one of the major confirmations of the validity of the standard model (SM) of particle interactions. Through radiative corrections of the SM, the mass of the top quark, along with that of the W boson, provide the best indication for the value of the mass of the hypothesized Higgs boson. The mass of the W is known to a precision of < 0.1%, while the uncertainty on the mass of the top quark is at the 4% level. Improvements in both measurements are required to limit the range of mass that the Higgs boson can assume in the SM, and, of course, to check whether that agrees with expectation. It is therefore important to develop techniques for extracting the mass of the top quark that can provide the sharpest values possible.
Date: October 14, 2003
Creator: Estrada, Juan
System: The UNT Digital Library
Observation of anomalous Iron Ion Charge Distribution in FTU (open access)

Observation of anomalous Iron Ion Charge Distribution in FTU

Iron coming from the poloidal limiter or the stainless steel vessel is an important intrinsic impurity in the FTU tokamak discharges, and X-ray and VUV spectroscopy provide useful information about the impurity behavior. The iron ion charge state distribution, as usual for tokamaks, is analyzed assuming a collisional radiative model and an anomalous perpendicular diffusion. In our experiment the iron ionization level depends, as it is expected, on central electron temperature (fig. 1), but the ion charge state distribution shows a different behavior when the first wall material or the iron source are changed.
Date: November 14, 2003
Creator: Finkenthal, M.; May, M.; Pacella, D.; Leigheb, M.; Zagorski, R.; Mattioli, M. et al.
System: The UNT Digital Library
Susceptibility of Welded and Non-Welded Titanium Alloys to Environmentally Assisted Cracking in Simulated Concentrated Ground Waters (open access)

Susceptibility of Welded and Non-Welded Titanium Alloys to Environmentally Assisted Cracking in Simulated Concentrated Ground Waters

The engineering barriers for the nuclear waste repository at Yucca Mountain include a double walled container and a detached drip shield. The material selected to construct the drip shield will be Titanium Grade 7 (Ti Gr 7 or R52400). Ti Gr 7 is highly resistant to corrosion and consequently it is widely used to handle aggressive industrial environments. The model for the degradation of the engineering barriers includes three modes of corrosion, namely general corrosion, localized corrosion and environmentally assisted cracking (EAC). The objective of the current research was to characterize the susceptibility of three titanium alloys to EAC in several environmental conditions with varying solution composition, pH and temperature. The susceptibility to EAC was evaluated using constant deformation (deflection) U-bend specimens in both the non-welded and welded conditions. Results show that after more than five years exposure in the vapor and liquid phases of alkaline (pH {approx} 10) and acidic (pH {approx} 3) multi-ionic environments at 60 C and 90 C, most of the specimens were free from EAC. The only specimens that suffered EAC were welded Ti Gr 12 (R53400) exposed to liquid simulated concentrated water (SCW) at 90 C.
Date: October 14, 2003
Creator: Fix, D. V.; Estill, J. C.; Wong, L. L. & Rebak, R. B.
System: The UNT Digital Library
Characterization of Free Volume Changes Associated with Shear Band Formation in Zr- and Cu-Based Bulk Metallic Glasses (open access)

Characterization of Free Volume Changes Associated with Shear Band Formation in Zr- and Cu-Based Bulk Metallic Glasses

The free volume model for flow in metallic glasses predicts a significant increase in free volume at the onset of plastic deformation. The details of these structural changes are unclear, however, particularly during strain localization in shear bands. In this study, the free volume changes associated with inhomogeneous plastic deformation of a Cu-based bulk metallic glass were examined using positron annihilation spectroscopy (PAS). PAS results indicated that there was a distribution of free volume site sizes in both the as-quenched and rolled glasses, and that the concentration of larger sites increased with deformation. Differential scanning calorimetry (DSC) was also used to observe the glass transition behaviors of Cu- and Zr-based glasses after rolling and annealing. Annealing resulted in an increase in the height of the endothermic glass transition peak, consistent with structural relaxation relative to the as-quenched material. Deformation resulted in both a lower endothermic peak height and an earlier and deeper exothermic peak associated with structural relaxation, indicating a more disordered structure with more free volume.
Date: November 14, 2003
Creator: Flores, K. M.; Glade, S. C.; Asoka-Kumar, P. & Kanungo, B.
System: The UNT Digital Library
Historical background: Why is it important to improve automated particle selection methods? (open access)

Historical background: Why is it important to improve automated particle selection methods?

A current trend in single-particle electron microscopy is to compute three-dimensional reconstructions with ever-increasing numbers of particles in the data sets. Since manual--or even semi-automated--selection of particles represents a major bottleneck when the data set exceeds several thousand particles, there is growing interest in developing automatic methods for selecting images of individual particles. Except in special cases, however, it has proven difficult to achieve the degree of efficiency and reliability that would make fully automated particle selection a useful tool. The simplest methods such as cross correlation (i.e., matched filtering) do not perform well enough to be used for fully automated particle selection. Geometric properties (area, perimeter-to-area ratio, etc.) and the integrated ''mass'' of candidate particles are additional factors that could improve automated particle selection if suitable methods of contouring particles could be developed. Another suggestion is that data be always collected as pairs of images, the first taken at low defocus (to capture information at the highest possible resolution) and the second at very high defocus (to improve the visibility of the particle). Finally, it is emphasized that well-annotated, open-access data sets need to be established in order to encourage the further development and validation of methods for automated …
Date: August 14, 2003
Creator: Glaeser, Robert M.
System: The UNT Digital Library
Torsional Buckling and Writhing Dynamics of Elastic Cables and DNA (open access)

Torsional Buckling and Writhing Dynamics of Elastic Cables and DNA

Marine cables under low tension and torsion on the sea floor can undergo a dynamic buckling process during which torsional strain energy is converted to bending strain energy. The resulting three-dimensional cable geometries can be highly contorted and include loops and tangles. Similar geometries are known to exist for supercoiled DNA and these also arise from the conversion of torsional strain energy to bending strain energy or, kinematically, a conversion of twist to writhe. A dynamic form of Kirchhoff rod theory is presented herein that captures these nonlinear dynamic processes. The resulting theory is discretized using the generalized-method for finite differencing in both space and time. The important kinematics of cross-section rotation are described using an incremental rotation ''vector'' as opposed to traditional Euler angles or Euler parameters. Numerical solutions are presented for an example system of a cable subjected to increasing twist at one end. The solutions show the dynamic evolution of the cable from an initially straight element, through a buckled element in the approximate form of a helix, and through the dynamic collapse of this helix through a looped form.
Date: February 14, 2003
Creator: Goyal, S; Perkins, N C & Lee, C L
System: The UNT Digital Library
A Comparison of the Effect of Temperature on the Passivity Breakdown and Repassivation Potentials of Wrought and Welded Alloy 22 in 5 M CAC12 (open access)

A Comparison of the Effect of Temperature on the Passivity Breakdown and Repassivation Potentials of Wrought and Welded Alloy 22 in 5 M CAC12

The study of the electrochemical behavior of wrought and welded Alloy 22 was carried out in 5 M CaC12 at various temperatures. Comparisons were made between the electrochemical behaviors of the wrought and welded forms of Alloy 22 Multiple Crevice Assembly (MCA) specimens. The susceptibility to corrosion was found to increase with increase in temperature in both the wrought and the welded forms of the alloy: Nevertheless, the measure critical breakdown potential E{sub crit} was found to be Similar for the wrought and welded specimens.
Date: February 14, 2003
Creator: Ilevbare, G
System: The UNT Digital Library
EXISTENCE OF SUPERSCRIPT 4 SUBSCRIPT LAMBDA SUBSCRIPT LAMBDA H AND DECAY TO A RESONANCE IN SUPERSCRIPT 4 LAMBDA. (open access)

EXISTENCE OF SUPERSCRIPT 4 SUBSCRIPT LAMBDA SUBSCRIPT LAMBDA H AND DECAY TO A RESONANCE IN SUPERSCRIPT 4 LAMBDA.

Experiment E906 at the BNL-AGS, searching for light S = -2 hypernuclei, found strong evidence for the nuclide {sub {Lambda}{Lambda}}{sup 4}H. Perhaps the most striking feature of this experiment was the presence in the data of a narrow low-momentum {pi}{sup -} line at k{sub {pi}} = 104-105 MeV/c. This line was ascribed to the decay of {sub {Lambda}{Lambda}}{sup 4}H into a resonant state in {sub {Lambda}}{sup 4}H. The existence of such a state is shown to be plausible, its characteristics delineated, and its relevance to ongoing theoretical calculations considered.
Date: October 14, 2003
Creator: KAHANA,S. H. MILLENER,D. J.
System: The UNT Digital Library
Neutrino physics, superbeams and the neutrino factory (open access)

Neutrino physics, superbeams and the neutrino factory

We summarize what has been learned about the neutrino mass spectrum and neutrino mixing, identify interesting open questions that can be answered by accelerator neutrino facilities of the future, and discuss the importance and physics of answering them.
Date: October 14, 2003
Creator: Kayser, Boris
System: The UNT Digital Library
Neutrino physics: Where do we stand and where are we going? The theoretical phenomenological perspective (open access)

Neutrino physics: Where do we stand and where are we going? The theoretical phenomenological perspective

The discoveries and open questions in neutrino physics, as reported at Neutrino 2002 and more recently, are reviewed from a theoretical perspective.
Date: October 14, 2003
Creator: Kayser, Boris
System: The UNT Digital Library
Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska (open access)

Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska

Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon ({sup 14}C) signal in the environment that has provided a useful tracer and chronological marker in oceanic systems and organisms. The bomb-generated {sup 14}C signal retained in fish otoliths can be used as a permanent, time-specific recorder of the 14C present in ambient seawater, making it a useful tool in age validation of fishes. The goal of this study was to determine {sup 14}C levels in otoliths of the age-validated yelloweye rockfish (Sebastes ruberrimus) to establish a reference time series for the coastal waters of southeast Alaska. Radiocarbon values from the first year's growth of 43 yelloweye rockfish otoliths were plotted against estimated birth year to produce a 14C time series for these waters spanning 1940 to 1990. The time series shows the initial rise of bomb 14C occurred in 1958 in coastal southeast Alaskan waters and {sup 14}C levels rose relatively rapidly to peak {Delta}{sup 14}C values (60-70%) between 1966 and 1971, with a subsequent declining trend through the end of the record in 1990 (-3.2%). In addition, the radiocarbon data, independent of the radiometric study, confirms the longevity of the yelloweye rockfish up to …
Date: October 14, 2003
Creator: Kerr-Ferrey, L A; Andrews, A H; Frantz, B R; Coale, K H; Brown, T A & Cailliet, G M
System: The UNT Digital Library
Hydrogen Gas Generation Model for Fuel-Based Remote-Handled Transuranic Waste Stored at the INEEL (open access)

Hydrogen Gas Generation Model for Fuel-Based Remote-Handled Transuranic Waste Stored at the INEEL

The Idaho National Environmental and Engineering Laboratory (INEEL) initiated efforts to calculate the hydrogen gas generation in remote-handled transuranic (RH-TRU) containers in order to evaluate continued storage of unvented RH-TRU containers in vaults and to identify any potential problems during retrieval and aboveground storage. A computer code is developed to calculate the hydrogen concentration in the stored RH-TRU waste drums for known configuration, waste matrix, and radionuclide inventories as a function of time.
Date: January 14, 2003
Creator: Khericha, Soli; Bhatt, Raj & Liekhus, Kevin
System: The UNT Digital Library