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Imaging columns of the light elements carbon, nitrogen and oxygen with sub angstrom resolution (open access)

Imaging columns of the light elements carbon, nitrogen and oxygen with sub angstrom resolution

It is reported that lattice imaging with a 300 kV field emission microscope in combination with numerical reconstruction procedures can be used to reach an interpretable resolution of about 80 pm for the first time. A retrieval of the electron exit wave from focal series allows for the resolution of single atomic columns of the light elements carbon, nitrogen, and oxygen at a projected nearest neighbor spacing down to 85 pm. Lens aberrations are corrected on-line during the experiment and by hardware such that resulting image distortions are below 80 pm. Consequently, the imaging can be aberration-free to this extent. The resolution enhancement results from increased electrical and mechanical stability's of the instrument coupled with a low spherical aberration coefficient of 0.595 + 0.005 mm.
Date: January 2, 2000
Creator: Kisielowski, C.; Hetherington, C. J. D.; Wang, Y. C.; Kilaas, R.; O'Keefe, M. A. & Thust, A.
System: The UNT Digital Library
Certification of solar products - The Florida experience (open access)

Certification of solar products - The Florida experience

Florida legislation enacted in 1976 directed the Florida Solar Energy Center (FSEC) to develop standards for solar energy systems manufactured or sold in the state, establish criteria for testing the performance of solar energy systems, and provide a means to display compliance with approved performance tests for these systems. This mandate has been effectively implemented for both solar domestic water heating and solar pool heating systems. With growing interest and markets for photovoltaic systems, plans are presently being developed to expand the scope of the mandate to include photovoltaic technology. This paper discusses four complementary facets of a photovoltaic (PV) system certification program. They include PV module performance characterization and rating; PV system design review and approval; examination and authorization of photovoltaic system installers; and inspection and acceptance testing of PV system installation. The suggested photovoltaic system process builds on lessons learned from over 20 years of testing, certifying and labeling of solar thermal collectors, and the certification of solar thermal systems.
Date: February 2, 2000
Creator: POST,HAROLD N.; ROLAND,JAMES D.; VENTRE,GERARD G. & HUGGINS,JAMES C.
System: The UNT Digital Library
A comparison of spin observable predictions for RHIC (open access)

A comparison of spin observable predictions for RHIC

There have been many versions of spin-dependent parton distributions in the literature. Although most agree with present data within uncertainties, they are based upon different physical assumptions. Some physical models are discussed and the corresponding predictions for double spin asymmetries are shown. A summary of the most feasible measurements in the appropriate kinematic regions at RHIC, which should yield the most useful information about the polarized gluon distribution, is given.
Date: February 2, 2000
Creator: Ramsey, G. P.
System: The UNT Digital Library
Conductor development for High Energy Physics - Plans and Status of the U.S. Program (open access)

Conductor development for High Energy Physics - Plans and Status of the U.S. Program

None
Date: February 2, 2000
Creator: Scanlan, R. M.
System: The UNT Digital Library
Electrodialysis technology for salt recovery from aluminum salt cake (open access)

Electrodialysis technology for salt recovery from aluminum salt cake

Electrodialysis technology for recovering salt from aluminum salt cake is being developed at Argonne National Laboratory. Salt cake, a slag-like aluminum-industry waste stream, contains aluminum metal, salt (NaCl and KCl), and nonmetallics (primarily aluminum oxide). Salt cake can be recycled by digesting with water and filtering to recover the metal and oxide values. A major obstacle to widespread salt cake recycling is the cost of recovering salt from the process brine. Electrodialysis technology developed at Argonne appears to be a cost-effective approach to handling the salt brines, compared to evaporation or disposal. In Argonne's technology, the salt brine is concentrated until salt crystals are precipitated in the electrodialysis stack; the crystals are recovered downstream. The technology is being evaluated on the pilot scale using Eurodia's EUR 40-76-5 stack.
Date: February 2, 2000
Creator: Hryn, J. N.; Krumdick, G.; Graziano, D. & Sreenivasarao, K.
System: The UNT Digital Library
Estimating model parameter values for total system performance assessment (open access)

Estimating model parameter values for total system performance assessment

The intrinsic dissolution rates of nine borosilicate waste glasses were extracted from the results of MCC-1 tests conducted for durations long enough that the solution pH reached a nearly constant value but short enough that the buildup of dissolved species did not affect the dissolution rate. The effects of the pH and temperature on the measured rates were deconvoluted to determine the sensitivity of the rate to the glass composition. The intrinsic dissolution rates were similar for all of these glasses and were not correlated with the glass composition. The mean and standard deviation of the intrinsic dissolution rates of these glasses are log k{sub 0}/[g/(m{sup 2}{center_dot}d)] = 8.2 {+-} 0.2.
Date: February 2, 2000
Creator: Ebert, W. L.; Zyryanov, V. N. & Cunnane, J. C.
System: The UNT Digital Library
Ferroelectric and piezoelectric properties of MOCVD Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}PbTiO{sub 3} epitaxial thin films (open access)

Ferroelectric and piezoelectric properties of MOCVD Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}PbTiO{sub 3} epitaxial thin films

The authors have grown epitaxial Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3} (PMN) and (1-x)(Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3})-x(PBTiO{sub 3})(PMN-PT)thin films by metalorganic chemical vapor deposition at 700 -- 780 C on (100) SrTiO{sub 3} and SrRuO{sub 3}/SrTiO{sub 3} substrates. The zero-bias permittivity and loss measured at room temperature and 10 kHz for 220 nm thick pure PMN films were 900 and 1.5%, respectively. For PMN-PT films the small-signal permittivity ranged from 1000 to 1500 depending on deposition conditions and Ti content; correspondingly low values for the zero-bias dielectric loss between 1 and 5% were determined for all specimens. For PMN-PT with x of approximately 0.30--0.35, polarization hysteresis with P{sub r}{approximately}18{mu}C/cm{sup 2} was obtained. Initial piezoresponse data are discussed.
Date: February 2, 2000
Creator: Baumann, P. K.; Bai, G. R.; Streiffer, S. K.; Ghosh, K.; Auciello, O.; Stemmer, S. et al.
System: The UNT Digital Library
The impact of process parameters on gold elimination from soldered connector assemblies (open access)

The impact of process parameters on gold elimination from soldered connector assemblies

Minimizing the likelihood of solder joint embrittlement in connectors is realized by reducing or eliminating retained Au plating and/or Au-Sn intermetallic compound formation from the assemblies. Gold removal is performed most effectively by using a double wicking process. When only a single wicking procedure can be used, a higher soldering temperature improves the process of Au removal from the connector surfaces and to a nominal extent, removal of Au-contaminated solder from the joint. A longer soldering time did not appear to offer any appreciable improvement toward removing the Au-contaminated solder from the joint. Because the wicking procedure was a manual process, it was operator dependent.
Date: February 2, 2000
Creator: VIANCO,PAUL T. & KILGO,ALICE C.
System: The UNT Digital Library
New Direction in Hydrogeochemical Transport Modeling: Incorporating Multiple Kinetic and Equilibrium Reaction Pathways (open access)

New Direction in Hydrogeochemical Transport Modeling: Incorporating Multiple Kinetic and Equilibrium Reaction Pathways

At least two distinct kinds of hydrogeochemical models have evolved historically for use in analyzing contaminant transport, but each has important limitations. One kind, focusing on organic contaminants, treats biodegradation reactions as parts of relatively simple kinetic reaction networks with no or limited coupling to aqueous and surface complexation and mineral dissolution/precipitation reactions. A second kind, evolving out of the speciation and reaction path codes, is capable of handling a comprehensive suite of multicomponent complexation (aqueous and surface) and mineral precipitation and dissolution reactions, but has not been able to treat reaction networks characterized by partial redox disequilibrium and multiple kinetic pathways. More recently, various investigators have begun to consider biodegradation reactions in the context of comprehensive equilibrium and kinetic reaction networks (e.g. Hunter et al. 1998, Mayer 1999). Here we explore two examples of multiple equilibrium and kinetic reaction pathways using the reactive transport code GIMRT98 (Steefel, in prep.): (1) a computational example involving the generation of acid mine drainage due to oxidation of pyrite, and (2) a computational/field example where the rates of chlorinated VOC degradation are linked to the rates of major redox processes occurring in organic-rich wetland sediments overlying a contaminated aerobic aquifer.
Date: February 2, 2000
Creator: Steefel, C.I.
System: The UNT Digital Library
Nonlinear system modeling based on experimental data (open access)

Nonlinear system modeling based on experimental data

The canonical variate analysis technique is used in this investigation, along with a data transformation algorithm, to identify a system in a transform space. The transformation algorithm involves the preprocessing of measured excitation/response data with a zero-memory-nonlinear transform, specifically, the Rosenblatt transform. This transform approximately maps the measured excitation and response data from its own space into the space of uncorrelated, standard normal random variates. Following this transform, it is appropriate to model the excitation/response relation as linear since Gaussian inputs excite Gaussian responses in linear structures. The linear model is identified in the transform space using the canonical variate analysis approach, and system responses in the original space are predicted using inverse Rosenblatt transformation. An example is presented.
Date: February 2, 2000
Creator: PAEZ,THOMAS L. & HUNTER,NORMAN F.
System: The UNT Digital Library
On the development of a subgrid CFD model for fire extinguishment (open access)

On the development of a subgrid CFD model for fire extinguishment

A subgrid model is presented for use in CFD fire simulations to account for thermal suppressants and strain. The extinguishment criteria is based on the ratio of a local fluid-mechanics time-scale to a local chemical time-scale compared to an empirically-determined critical Damkohler number. Local extinction occurs if this time scale is exceeded, global fire extinguishment occurs when local extinction has occurred for all combusting cells. The fluid mechanics time scale is based on the Kolmogorov time scale and the chemical time scale is based on blowout of a perfectly stirred reactor. The input to the reactor is based on cell averaged temperatures, assumed stoichiometric fuel/air composition, and cell averaged suppressant concentrations including combustion products. A detailed chemical mechanism is employed. The chemical time-scale is precalculated and mixing rules are used to reduce the composition space that must be parameterized. Comparisons with experimental data for fire extinguishment in a flame-stabilizing, backward-facing step geometry indicates that the model is conservative for this condition.
Date: February 2, 2000
Creator: Tieszen, Sheldon R. & Lopez, Amalia R.
System: The UNT Digital Library
Phase transitions in insertion electrodes for lithium batteries (open access)

Phase transitions in insertion electrodes for lithium batteries

Phase transitions that occur during lithium insertion into layered and framework structures are discussed in the context of their application as positive and negative electrodes in lithium-ion batteries. The discussion is focused on the two-dimensional structures of graphite, LiNi{sub 1{minus}x}M{sub x}O{sub 2} (M = Co, Ti and Mg), and Li{sub 1.2}V{sub 3}O{sub 8}; examples of framework structures with a three-dimensional interstitial space for Li{sup +}-ion transport include the spinel oxides and intermetallic compounds with zinc-blende-type structures. The phase transitions are discussed in terms of their tolerance to lithium insertion and extraction and to the chemical stability of the electrodes in the cell environment.
Date: February 2, 2000
Creator: Thackeray, M. M.
System: The UNT Digital Library
Ray-tracing studies for a whole-viewing-angle retroreflector (open access)

Ray-tracing studies for a whole-viewing-angle retroreflector

The APS Survey and Alignment team uses LEICA laser trackers for the majority of their alignment tasks. These instruments utilize several different retroreflectors for tracking the path of the laser interferometer. Currently in use are open-air corner cubes with an acceptance angle of {+-}20{degree}, corner cube prisms with an acceptance angle of {+-}50{degree}, and a Cat's eye with an acceptance angle of {+-}60{degree}. Best measurement results can be achieved by using an open-air corner cube that eliminates the need for the laser beam to travel through a different medium before it returns to the instrument detector. However, the trade off is a small acceptance angle. In order to overcome the limitations of the small acceptance angles, Takatsuji et al. has proposed the creation of a full-viewing-angle retroreflector. Based on the notion that the radius R{sub 1} of a common Cat's eye is proportional to R{sub 2}, one can write: R{sub 1} = (n {minus} 1)R{sub 2}. In the case that n, the refractive index of glass, equals 2, the radii R{sub 1} and R{sub 2} are identical, and one can create a solid sphere Cat's eye. This design has the advantages that no adhesives are used to bond the two …
Date: February 2, 2000
Creator: Yang, B. & Friedsam, H.
System: The UNT Digital Library
Spall formation in solution mined storage caverns based on a creep and fracture analysis (open access)

Spall formation in solution mined storage caverns based on a creep and fracture analysis

Because of limited direct observation, understanding of the interior conditions of the massive storage caverns constructed in Gulf Coast salt domes is realizable only through predictions of salt response. Determination of the potential for formation of salt spans, leading to eventual salt falls, is based on salt creep and fracture using the Multimechanism-Deformation Coupled Fracture (MCDF) model. This is a continuum model for creep, coupled to continuum damage evolution. The model has been successfully tested against underground results of damage around several test rooms at the Waste Isolation Pilot Plant (WIPP). Model simulations, here, evaluate observations made in the Strategic Petroleum Reserve (SPR) storage caverns, namely, the accumulation of material on cavern floors and evidence of salt falls. A simulation of a smooth cavern wall indicates damage is maximum at the surface but diminishes monotonically into the salt, which suggests the source of salt accumulation is surface sluffing. If a protuberance occurs on the wall, fracture damage can form beneath the protuberance, which will eventually cause fracture, and lead to a salt fall.
Date: February 2, 2000
Creator: MUNSON,DARRELL E.
System: The UNT Digital Library
Technical investigation of a pyrophoric event involving corrosion products from HEU ZPPR fuel plates (open access)

Technical investigation of a pyrophoric event involving corrosion products from HEU ZPPR fuel plates

A pyrophoric event recently occurred which involved corrosion products collected from highly-enriched uranium (HEU) fuel plates used in the Zero Power Physics Reactor (ZPPR). This paper summarizes the event and its background, and presents the results of an investigation into its source and mechanism. The investigation focused on characterization of corrosion product samples similar to those involved in the event using thermo-gravimetric analysis (TGA). Burning curve TGA tests were performed to measure the ignition temperature and hydride fractions of corrosion products in several different conditions to assess the effects of passivation treatment and long-term storage on chemical reactivity. The hydride fraction and ignition temperature of the corrosion products were found to be strongly dependent on the corrosion extent of the source metal. The results indicate that the energy source for the event was a considerable quantity of uranium hydride present in the corrosion products, but the specific ignition mechanism could not be identified.
Date: February 2, 2000
Creator: Totemeier, T. C.
System: The UNT Digital Library
Time and length scales within a fire and implications for numerical simulation (open access)

Time and length scales within a fire and implications for numerical simulation

A partial non-dimensionalization of the Navier-Stokes equations is used to obtain order of magnitude estimates of the rate-controlling transport processes in the reacting portion of a fire plume as a function of length scale. Over continuum length scales, buoyant times scales vary as the square root of the length scale; advection time scales vary as the length scale, and diffusion time scales vary as the square of the length scale. Due to the variation with length scale, each process is dominant over a given range. The relationship of buoyancy and baroclinc vorticity generation is highlighted. For numerical simulation, first principles solution for fire problems is not possible with foreseeable computational hardware in the near future. Filtered transport equations with subgrid modeling will be required as two to three decades of length scale are captured by solution of discretized conservation equations. By whatever filtering process one employs, one must have humble expectations for the accuracy obtainable by numerical simulation for practical fire problems that contain important multi-physics/multi-length-scale coupling with up to 10 orders of magnitude in length scale.
Date: February 2, 2000
Creator: Tieszen, Sheldon R.
System: The UNT Digital Library
Using Java to visualize and manipulate large arrays of neutron scattering data (open access)

Using Java to visualize and manipulate large arrays of neutron scattering data

The Intense Pulsed Neutron Source at Argonne National Laboratory is a world class pulsed neutron source with thirteen instruments designed to characterize materials using time-of-flight neutron scattering techniques. For each instrument, a collimated pulse of neutrons is directed to a material sample. The neutrons are scattered by the sample and detected by arrays of detectors. The type, number and arrangement of detectors vary widely from instrument to instrument, depending on which properties of materials are being studied. In all cases, the faster, higher energy neutrons reach the detectors sooner than the lower energy neutrons. This produces a time-of-flight spectrum at each detector element. The time-of-flight spectrum produced by each detector element records the scattering intensity at hundreds to thousands of discrete time intervals. Since there are typically between two hundred and ten thousand distinct detector elements, a single set of raw data can include millions of points. Often many such datasets are collected for a single sample to determine the effect of different conditions on the microscopic structure and dynamics of the sample. In this project, Java was used to construct a portable highly interactive system for viewing and operating on large collections of time-of-flight spectra. Java performed surprisingly well …
Date: February 2, 2000
Creator: Mikkelson, D.; Worlton, T.; Chatterjee, A.; Hammonds, J. & Chen, D.
System: The UNT Digital Library
AC magnetohydrodynamic microfluidic switch (open access)

AC magnetohydrodynamic microfluidic switch

A microfluidic switch has been demonstrated using an AC Magnetohydrodynamic (MHD) pumping mechanism in which the Lorentz force is used to pump an electrolytic solution. By integrating two AC MHD pumps into different arms of a Y-shaped fluidic circuit, flow can be switched between the two arms. This type of switch can be used to produce complex fluidic routing, which may have multiple applications in {micro}TAS.
Date: March 2, 2000
Creator: Lemoff, A V & Lee, A P
System: The UNT Digital Library
Comparisons of CAP88PC version 2.0 default parameters to site specific inputs (open access)

Comparisons of CAP88PC version 2.0 default parameters to site specific inputs

The effects of varying the input for the CAP88PC Version 2.0 program on the total effective dose equivalents (TEDEs) were determined for hypothetical releases from the Hot Fuel Examination Facility (HFEF) located at the Argonne National Laboratory site on the Idaho National Engineering and Environmental Laboratory (INEEL). Values for site specific meteorological conditions and agricultural production parameters were determined for the 80 km radius surrounding the HFEF. Four nuclides, {sup 3}H, {sup 85}Kr, {sup 129}I, and {sup 137}Cs (with its short lived progeny, {sup 137m}Ba) were selected for this study; these are the radioactive materials most likely to be released from HFEF under normal or abnormal operating conditions. Use of site specific meteorological parameters of annual precipitation, average temperature, and the height of the inversion layer decreased the TEDE from {sup 137}Cs-{sup 137m}Ba up to 36%; reductions for other nuclides were less than 3%. Use of the site specific agricultural parameters reduced TEDE values between 7% and 49%, depending on the nuclide. Reductions are associated with decreased committed effective dose equivalents (CEDEs) from the ingestion pathway. This is not surprising since the HFEF is located well within the INEEL exclusion area, and the surrounding area closest to the release point …
Date: March 2, 2000
Creator: Lehto, M. A.; Courtney, J. C.; Charter, N. & Egan, T.
System: The UNT Digital Library
Deployment of in Situ Measurement Techniques and the Marssim Process for Characterization of the Brookhaven Graphite Research Reactor. (open access)

Deployment of in Situ Measurement Techniques and the Marssim Process for Characterization of the Brookhaven Graphite Research Reactor.

None
Date: March 2, 2000
Creator: Kalb, P. D.; Luckett, L.; Watters, D.; Gogolak, C. & Milian, L. W.
System: The UNT Digital Library
Deployment of in Situ Measurement Techniques and the Marssim Process for Characterization of the Brookhaven Graphite Research Reactor. (open access)

Deployment of in Situ Measurement Techniques and the Marssim Process for Characterization of the Brookhaven Graphite Research Reactor.

None
Date: March 2, 2000
Creator: Kalb, P. D.; Luckett, L.; Watters, D.; Gogolak, C. & Milian, L. W.
System: The UNT Digital Library
Dislocation Multiplication in the Early Stage of Deformation in Mo Single Crystals (open access)

Dislocation Multiplication in the Early Stage of Deformation in Mo Single Crystals

Initial dislocation structure in annealed high-purity Mo single crystals and deformation substructure in a crystal subjected to 1% compression have been examined and studied using transmission electron microscopy (TEM) techniques in order to investigate dislocation multiplication mechanisms in the early stage of plastic deformation. The initial dislocation density is in a range of 10{sup 6} {approx} 10{sup 7} cm{sup -2}, and the dislocation structure is found to contain many grown-in superjogs along dislocation lines. The dislocation density increases to a range of 10{sup 8} {approx} 10{sup 9} cm{sup -2}, and the average jog height is also found to increase after compressing for a total strain of 1%. It is proposed that the preexisting jogged screw dislocations can act as (multiple) dislocation multiplication sources when deformed under quasi-static conditions. The jog height can increase by stress-induced jog coalescence, which takes place via the lateral migration (drift) of superjogs driven by unbalanced line-tension partials acting on link segments of unequal lengths. The coalescence of superjogs results in an increase of both link length and jog height. Applied shear stress begins to push each link segment to precede dislocation multiplication when link length and jog height are greater than critical lengths. This ''dynamic'' …
Date: March 2, 2000
Creator: Hsiung, L. & Lassila, D.H.
System: The UNT Digital Library
Integrating Records Management (RM) and Information Technology (IT) (open access)

Integrating Records Management (RM) and Information Technology (IT)

Records Managers are continually exploring ways to integrate their services with those offered by Information Technology-related professions to capitalize on the advantages of providing customers a total solution to managing their records and information. In this day and age, where technology abounds, there often exists a fear on the part of records management that this integration will result in a loss of identity and the focus of one's own mission - a fear that records management may become subordinated to the fast-paced technology fields. They need to remember there is strength in numbers and it benefits RM, IT, and the customer when they can bring together the unique offerings each possess to reach synergy for the benefit of all the corporations. Records Managers, need to continually strive to move ''outside the records management box'', network, expand their knowledge, and influence the IT disciplines to incorporate the concept of ''management'' into their customer solutions.
Date: March 2, 2000
Creator: NUSBAUM,ANNA W. & CUSIMANO,LINDA J.
System: The UNT Digital Library
Laboratory Data for X-Ray Astronomy (open access)

Laboratory Data for X-Ray Astronomy

Laboratory facilities have made great strides in producing large sets of reliable data for X-ray astronomy, which include ionization and recombination cross sections needed for charge balance calculations as well as the atomic data needed for interpreting X-ray line formation. We discuss data from the new generation sources and pay special attention to the LLNL electron beam ion trap experiment, which is unique in it's ability to provide direct laboratory access to spectral data under precisely controlled conditions that simulate those found in many astrophysical plasmas. Examples of spectral data obtained in the 1-160 A wavelength range are given illustrating the type of laboratory X-ray data produced in support of such missions as Chandra, XMM, ASCA and EUVE.
Date: March 2, 2000
Creator: Beiersdorfer, P.; Brown, G.V.; Chen, H.; Gu, M.F.; Kahn, S.M.; Lepson, J.K. et al.
System: The UNT Digital Library