High intensity direct third harmonic generation in BBO (open access)

High intensity direct third harmonic generation in BBO

The azimuthal dependence of second- and third-order coupling are used to measure the relative contributions of each to direct third harmonic generation with efficiencies up to 6%. The values of {xi}{sub ij}{sup (3)} are measured.
Date: February 23, 1998
Creator: Banks, P.S., LLNL
Object Type: Article
System: The UNT Digital Library
Stabilization and disposal of Argonne-West low-level mixed wastes in ceramicrete waste forms. (open access)

Stabilization and disposal of Argonne-West low-level mixed wastes in ceramicrete waste forms.

The technology of room-temperature-setting phosphate ceramics or Ceramicrete{trademark} technology, developed at Argonne National Laboratory (ANL)-East is being used to treat and dispose of low-level mixed wastes through the Department of Energy complex. During the past year, Ceramicrete{trademark} technology was implemented for field application at ANL-West. Debris wastes were treated and stabilized: (a) Hg-contaminated low-level radioactive crushed light bulbs and (b) low-level radioactive Pb-lined gloves (part of the MWIR {number_sign} AW-W002 waste stream). In addition to hazardous metals, these wastes are contaminated with low-level fission products. Initially, bench-scale waste forms with simulated and actual waste streams were fabricated by acid-base reactions between mixtures of magnesium oxide powders and an acid phosphate solution, and the wastes. Size reduction of Pb-lined plastic glove waste was accomplished by cryofractionation. The Ceramicrete{trademark} process produces dense, hard ceramic waste forms. Toxicity Characteristic Leaching Procedure (TCLP) results showed excellent stabilization of both Hg and Pb in the waste forms. The principal advantage of this technology is that immobilization of contaminants is the result of both chemical stabilization and subsequent microencapsulation of the reaction products. Based on bench-scale studies, Ceramicrete{trademark} technology has been implemented in the fabrication of 5-gal waste forms at ANL-West. Approximately 35 kg of real …
Date: February 17, 1998
Creator: Barber, D. B.; Singh, D.; Strain, R. V.; Tlustochowicz, M. & Wagh, A. S.
Object Type: Article
System: The UNT Digital Library
A mathematical basis for automated structured grid generation with close coupling to the flow solver (open access)

A mathematical basis for automated structured grid generation with close coupling to the flow solver

The first two truncation error terms resulting from finite differencing the convection terms in the two-dimensional Navier-Stokes equations are examined for the purpose of constructing two-dimensional grid generation schemes. These schemes are constructed such that the resulting grid distributions drive the error terms to zero. Two sets of equations result, one for each error term, that show promise in generating grids that provide more accurate flow solutions and possibly faster convergence. One set results in an algebraic scheme that drives the first truncation term to zero, and the other a hyperbolic scheme that drives the second term to zero. Also discussed is the possibility of using the schemes in sequentially constructing a grid in an iterative algorithm involving the flow solver. In essence, the process is envisioned to generate not only a flow field solution but the grid as well, rendering the approach a hands-off method for grid generation
Date: February 1, 1998
Creator: Barnette, D. W.
Object Type: Report
System: The UNT Digital Library
Some theoretical issues on computer simulations (open access)

Some theoretical issues on computer simulations

The subject of this paper is the development of mathematical foundations for a theory of simulation. Sequentially updated cellular automata (sCA) over arbitrary graphs are employed as a paradigmatic framework. In the development of the theory, the authors focus on the properties of causal dependencies among local mappings in a simulation. The main object of and study is the mapping between a graph representing the dependencies among entities of a simulation and a representing the equivalence classes of systems obtained by all possible updates.
Date: February 1, 1998
Creator: Barrett, C. L. & Reidys, C. M.
Object Type: Article
System: The UNT Digital Library
The greenhouse of the future: Using a sponsored competition in a capstone course (open access)

The greenhouse of the future: Using a sponsored competition in a capstone course

Educational objectives of capstone courses such as critical-thinking and problem-solving skills are among the most cited needs in curriculum revitalization efforts. Sponsored competitions present an important vehicle for achieving these educational objectives. Opportunities such as the Greenhouse of the Future Competition provide students a diverse range of critical experiences not easily simulated in traditional classroom settings. The objective of the competition was to provide an opportunity for US university students to conceptualize, design, integrate, fabricate, and demonstrate innovative greenhouse or controlled environment ideas. The students achieved a great sense of accomplishment and satisfaction by converting their ideas into proposals, developing proposals into experiments, tracking the data generated by the experiments and translating that data into a meaningful communication locally and to the scientific community at large. Most of these important learning experiences would have remained as components of the project even if the team had not advanced as the winning entry.
Date: February 18, 1998
Creator: Bates, R.M. & Baumbauer, D.
Object Type: Report
System: The UNT Digital Library
Geothermal Financing Workbook (open access)

Geothermal Financing Workbook

This report was prepared to help small firm search for financing for geothermal energy projects. There are various financial and economics formulas. Costs of some small overseas geothermal power projects are shown. There is much discussion of possible sources of financing, especially for overseas projects. (DJE-2005)
Date: February 1, 1998
Creator: Battocletti, E.C.
Object Type: Report
System: The UNT Digital Library
Domain topology of micro-scale, ferromagnetic pancakes (open access)

Domain topology of micro-scale, ferromagnetic pancakes

Planar, micron-scale ellipses patterned from 700A-thick Co films exhibit nearly complete suppression of hysteresis when magnetized in- plane along their short axes. Using a combination of Magnetic Force Microscopy and Vibrating Sample Magnetometry, we find that the suppression of hysteresis is associated with the continuous deformation of a dipole field configuration. The presence of hysteresis for in-plane, long-axis magnetization is associated with transitions between topologically inequivalent configurations.
Date: February 1, 1998
Creator: Bedrossian, P. J., LLNL
Object Type: Article
System: The UNT Digital Library
How to build VLSI-efficient neural chips (open access)

How to build VLSI-efficient neural chips

This paper presents several upper and lower bounds for the number-of-bits required for solving a classification problem, as well as ways in which these bounds can be used to efficiently build neural network chips. The focus will be on complexity aspects pertaining to neural networks: (1) size complexity and depth (size) tradeoffs, and (2) precision of weights and thresholds as well as limited interconnectivity. They show difficult problems-exponential growth in either space (precision and size) and/or time (learning and depth)-when using neural networks for solving general classes of problems (particular cases may enjoy better performances). The bounds for the number-of-bits required for solving a classification problem represent the first step of a general class of constructive algorithms, by showing how the quantization of the input space could be done in O (m{sup 2}n) steps. Here m is the number of examples, while n is the number of dimensions. The second step of the algorithm finds its roots in the implementation of a class of Boolean functions using threshold gates. It is substantiated by mathematical proofs for the size O (mn/{Delta}), and the depth O [log(mn)/log{Delta}] of the resulting network (here {Delta} is the maximum fan in). Using the fan in …
Date: February 1, 1998
Creator: Beiu, V.
Object Type: Article
System: The UNT Digital Library
The Effects of Joints in Two Beryllium Hemispheres Used to Form an Ignition Capsule for the National Ignition Facility (open access)

The Effects of Joints in Two Beryllium Hemispheres Used to Form an Ignition Capsule for the National Ignition Facility

None
Date: February 2, 1998
Creator: Bel'kov, S. A.; Bondarenko, S. V.; Ilkaeva, L. A.; Kochemasov, G. G.; Mkhitarian, L. S.; Vinokurov, O. A. et al.
Object Type: Report
System: The UNT Digital Library
Sensor Driven Intelligent Control System For Plasma Processing (open access)

Sensor Driven Intelligent Control System For Plasma Processing

This Cooperative Research and Development Agreement (CRADA) between Innovative Computing Technologies, Inc. (IC Tech) and Martin Marietta Energy Systems (MMES) was undertaken to contribute to improved process control for microelectronic device fabrication. Process data from an amorphous silicon thin film deposition experiment was acquired to validate the performance of an intelligent, adaptive, neurally-inspired control software module designed to provide closed loop control of plasma processing machines used in the microelectronics industry. Data acquisition software was written using LabView The data was collected from an inductively coupled plasma (ICP) source, which was available for this project through LMES's RF/Microwave Technology Center. Experimental parameters measured were RF power, RF current and voltage on the antenna delivering power to the plasma, hydrogen and silane flow rate, chamber pressure, substrate temperature and H-alpha optical emission. Experimental results obtained were poly-crystallin silicon deposition rate, crystallinity, crystallographic orientation and electrical conductivity. Owing to experimental delays resulting from hardware failures, it was not possible to assemble a complete data for IC Tech use within the time and resource constraints of the CRADA. IC Tech was therefore not able to verify the performance of their existing models and control structures and validate model performance under this CRADA.
Date: February 23, 1998
Creator: Bell, G. & Campbell, V. B.
Object Type: Report
System: The UNT Digital Library
Atomic structure of a polar ceramic/metal interface: {l_brace}222{r_brace}MgO/Cu (open access)

Atomic structure of a polar ceramic/metal interface: {l_brace}222{r_brace}MgO/Cu

{l_brace}222{r_brace}MgO/Cu is one of the most extensively characterized ceramic/metal interfaces, in view of the atom probe field ion microscopy, Z-contrast Scanning Transmission Electron Microscopy (STEM), and spatially resolved Electron energy loss spectroscopy (EELS) measurements performed by the present authors, as well as the high resolution electron microscopy (HREM) of this system by others. Atomistic simulations with local density functional theory (LDFT) and Molecular Dynamics (MD) have been performed to gain additional insight into the structure of this interface. This presentation describes an interface interatomic potential for {l_brace}222{r_brace}MgO/Cu derived from LDFT total energy calculations, and its application to structural properties, including the terminating species, the absence of dislocation standoff, and the symmetry of the interfacial dislocation network.
Date: February 1, 1998
Creator: Benedek, R.; Shashkov, D. A.; Seidman, D. N.; Muller, D. A.; Silcox, J.; Chisholm, M. F. et al.
Object Type: Article
System: The UNT Digital Library
Silicon carbide amorphization by electron irradiation (open access)

Silicon carbide amorphization by electron irradiation

Observations made more than ten years ago showed that SiC could be made amorphous at cryogenic temperatures by in-situ 300kV electron irradiation. However, high voltage electron microscope (HVEM) results indicate a threshold voltage of 725 kV for amorphization of SiC at 140 K. In addition, a recent review exposes the considerable uncertainty in the literature regarding displacement energies for SiC. Therefore, further experiments have been performed in a Philips CM30 (LaB{sub 6} cathode) with a Gatan double-tilt cooling holder in an attempt to determine the threshold voltage for amorphization at {approximately} 140 K. Sintered {alpha}-SiC (defected 6H polytype), beam direction B = <11{bar 2}0>, and probes containing {approximately} 75 nA in {approximately} 0.5 {micro}m, were used. Amorphization occurred in <10 min at 300 kV and after {approximately} 60 min at 180 kV; visible darkening occurred at lower voltages and doses. Similar behavior occurred for B = [0001]. The critical dose for amorphization was measured as a function of accelerating voltage. Probe current profiles were measured by post-specimen scanning (CM30 SCIM mode with 100 {micro}m diameter Gatan STEM detector) images of the focused probes positioned in a hole, and probe currents were measured from the exposure time, which had previously been …
Date: February 1, 1998
Creator: Bentley, J.
Object Type: Article
System: The UNT Digital Library
Threshold resummation of soft gluons in hadronic reactions - an introduction. (open access)

Threshold resummation of soft gluons in hadronic reactions - an introduction.

The authors discuss the motivation for resummation of the effects of initial-state soft gluon radiation, to all orders in the strong coupling strength, for processes in which the near-threshold region in the partonic subenergy is important. The author summarizes the method of perturbative resummation and its application to the calculation of the total cross section for top quark production at hadron colliders. Comments are included on the differences between the treatment of subleading logarithmic terms in this method and in other approaches.
Date: February 17, 1998
Creator: Berger, E. L.
Object Type: Article
System: The UNT Digital Library
Hanford Tanks Initiative fiscal year 1997 retrieval technology demonstrations (open access)

Hanford Tanks Initiative fiscal year 1997 retrieval technology demonstrations

The Hanford Tanks Initiative was established in 1996 to address a range of retrieval and closure issues associated with radioactive and hazardous waste stored in Hanford`s single shell tanks (SSTs). One of HTI`s retrieval goals is to ``Successfully demonstrate technology(s) that provide expanded capabilities beyond past practice sluicing and are extensible to retrieve waste from other SSTS.`` Specifically, HTI is to address ``Alternative technologies to past practice sluicing`` ... that can ... ``successfully remove the hard heel from a sluiced tank or to remove waste from a leaking SST`` (HTI Mission Analysis). During fiscal year 1997, the project contracted with seven commercial vendor teams to demonstrate retrieval technologies using waste simulants. These tests were conducted in two series: three integrated tests (IT) were completed in January 1997, and four more comprehensive Alternative Technology Retrieval Demonstrations (ARTD) were completed in July 1997. The goal of this testing was to address issues to minimize the risk, uncertainties, and ultimately the overall cost of removing waste from the SSTS. Retrieval technologies can be separated into three tracks based on how the tools would be deployed in the tank: globally (e.g., sluicing) or using vehicles or robotic manipulators. Accordingly, the HTI tests included an …
Date: February 5, 1998
Creator: Berglin, E. J.
Object Type: Report
System: The UNT Digital Library
A.c. transport and collective excitation in a quantum point contact (open access)

A.c. transport and collective excitation in a quantum point contact

The authors calculate the a.c.-admittance of a two dimensional quantum point contact (QPC) using a Boltzmann-like kinetic equation derived for the partial Wigner distribution function. An integral equation for a potential inside a QPC is solved numerically. The dependence of the admittance on the frequency of the a.c. field is found in a wide frequency range {omega} {approx} 0--50 GHz. The contribution to the imaginary part of the admittance due to the quantum capacitance and inductance is numerically calculated. It is shown that the crossover from localized parameters--quantum capacitance and inductance--to distributed behavior takes place at {omega} {approximately} 10 GHz. A transition from 2D plasmons to quasi-1D plasmons is analyzed as a function of two dimensionless parameters: k{sub x}d{sub 0} (where k{sub x} is the longitudinal wave vector, and d{sub 0} is the width of the QPC), and the number of open electron channels, N.
Date: February 1, 1998
Creator: Berman, G. P.; Doolen, G. D.; Mainieri, R.; Aronov, I. E.; Campbell, D. K.; Beletskii, N. N. et al.
Object Type: Report
System: The UNT Digital Library
On properties of boundaries and electron conductivity in mesoscopic polycrystalline silicon films for memory devices (open access)

On properties of boundaries and electron conductivity in mesoscopic polycrystalline silicon films for memory devices

The authors present the results of MD modeling on the structural properties of grain boundaries (GB) in thin polycrystalline films. The transition from crystalline boundaries with low mismatch angle to amorphous boundaries is investigated. It is shown that the structures of the GBs satisfy a thermodynamical criterion suggested in a cited reference. The potential energy of silicon atoms is closely related with a geometrical quantity -- tetragonality of their coordination with their nearest neighbors. A crossover of the length of localization is observed to analyze the crossover of the length of localization of the single electron states and properties of conductance of the thin polycrystalline film at low temperature. They use a two-dimensional Anderson localization model, with the random one site electron charging energy for a single grain (dot), random non-diagonal matrix elements, and random number of connections between the neighboring grains. The results on the crossover behavior of localization length of the single electron states and characteristic properties of conductance are presented in the region of parameters where the transition from an insulator to a conductor regimes takes place.
Date: February 1, 1998
Creator: Berman, G. P.; Doolen, G. D.; Mainieri, R.; Rehacek, J.; Campbell, D. K.; Luchnikov, V. A. et al.
Object Type: Article
System: The UNT Digital Library
An English translation of the 50-year chronicle of historical events of the State Scientific Center - Russian Federation Physico-Energetics Institute 1946-1996 (open access)

An English translation of the 50-year chronicle of historical events of the State Scientific Center - Russian Federation Physico-Energetics Institute 1946-1996

This document is an English translation of a Russian document which gives a brief overview of the historical events of the Russian State Scientific Center over the first 50 years of its existence.
Date: February 1, 1998
Creator: Berman, G.; Gudowski, W. & Doolen, G.
Object Type: Report
System: The UNT Digital Library
Advanced weigh-in-motion system for weighing vehicles at high speed (open access)

Advanced weigh-in-motion system for weighing vehicles at high speed

A state-of-the-art, Advanced Weigh-In-Motion (WIM) system has been designed, installed, and tested on the west bound side of Interstate I-75/I-40 near the Knox County Weigh Station. The project is a Cooperative Research and Development Agreement (CRADA) between Oak Ridge National Laboratory (ORNL) and International Road Dynamics, Inc. (IRD) sponsored by the Office of Uranium Programs, Facility and Technology Management Division of the Department of Energy under CRADA No. ORNL95-0364. ORNL, IRD, the Federal Highway Administration, the Tennessee Department of Safety and the Tennessee Department of Transportation have developed a National High Speed WIM Test Facility for test and evaluation of high-speed WIM systems. The WIM system under evaluation includes a Single Load Cell WIM scale system supplied and installed by IRD. ORNL developed a stand-alone, custom data acquisition system, which acquires the raw signals from IRD`s in-ground single load cell transducers. Under a separate contract with the Federal Highway Administration, ORNL designed and constructed a laboratory scale house for data collection, analysis and algorithm development. An initial advanced weight-determining algorithm has been developed. The new advanced WIM system provides improved accuracy and can reduce overall system variability by up to 30% over the existing high accuracy commercial WIM system.
Date: February 1, 1998
Creator: Beshears, D.L.; Muhs, J.D. & Scudiere, M.B.
Object Type: Report
System: The UNT Digital Library
Bayesian analysis of the solar neutrino anomaly (open access)

Bayesian analysis of the solar neutrino anomaly

We present an analysis of the recent solar neutrino data from the five experiments using Bayesian approach. We extract quantitative and easily understandable information pertaining to the solar neutrino problem. The probability distributions for the individual neutrino fluxes and, discrepancy distribution for B and Be fluxes, which include theoretical and experimental uncertainties have been extracted. The analysis carried out assuming that the neutrinos are unaltered during their passage from the sun to earth, clearly indicate that the observed PP flux is consistent with the 1995 standard solar model predictions of Bahcall and Pinsonneault within 2{sigma} (standard deviation), whereas the {sup 8}B flux is down by more than 12{sigma} and the {sup 7}Be flux is maximally suppressed. We also deduce the experimental survival probability for the solar neutrinos as a function of their energy in a model-independent way. We find that the shape of that distribution is in qualitative agreement with the MSW oscillation predictions.
Date: February 1, 1998
Creator: Bhat, C.M.
Object Type: Article
System: The UNT Digital Library
Evaluation of engineered barriers at the Idaho National Engineering and Environmental Laboratory (open access)

Evaluation of engineered barriers at the Idaho National Engineering and Environmental Laboratory

Subsurface Disposal (SDA) of the Radioactive Waste Management Complex serves as the low level waste burial ground at the Idaho National Engineering and Environmental Laboratory (INEEL). The low level wastes are buried in trenches, pits, and soil vaults in surficial sediments. A closure/post-closure plan must be written prior to closure of the SDA. The closure plan for the facility must include a design for an engineered barrier closure cover that will meet all applicable regulatory requirements. This paper describes the approach being followed at the INEEL to choose an appropriate cover design for the SDA closure. Regulatory requirements and performance objectives potentially applicable to closure of the SDA were identified. Technical issues related to SDA closure were identified from a literature search of previous arid site engineered barrier studies and from previous SDA closure cover evaluations. Five engineered barrier conceptual design alternatives were identified: (1) a bio/capillary barrier cover, (2) a thin soil cover, (3) a thick soil cover, (4) a Resource Conservation and Recovery Act cover, and (5) a concrete sealed surface cover. Two of these designs were chosen for in situ hydraulic testing, rather than all five, in order to maximize the amount of information generated relative to …
Date: February 1, 1998
Creator: Bhatt, Rajiv N. & Porro, Indrek
Object Type: Article
System: The UNT Digital Library
A damage mechanics based approach to structural deterioration and reliability (open access)

A damage mechanics based approach to structural deterioration and reliability

Structural deterioration often occurs without perceptible manifestation. Continuum damage mechanics defines structural damage in terms of the material microstructure, and relates the damage variable to the macroscopic strength or stiffness of the structure. This enables one to predict the state of damage prior to the initiation of a macroscopic flaw, and allows one to estimate residual strength/service life of an existing structure. The accumulation of damage is a dissipative process that is governed by the laws of thermodynamics. Partial differential equations for damage growth in terms of the Helmholtz free energy are derived from fundamental thermodynamical conditions. Closed-form solutions to the equations are obtained under uniaxial loading for ductile deformation damage as a function of plastic strain, for creep damage as a function of time, and for fatigue damage as function of number of cycles. The proposed damage growth model is extended into the stochastic domain by considering fluctuations in the free energy, and closed-form solutions of the resulting stochastic differential equation are obtained in each of the three cases mentioned above. A reliability analysis of a ring-stiffened cylindrical steel shell subjected to corrosion, accidental pressure, and temperature is performed.
Date: February 1998
Creator: Bhattcharya, B. & Ellingwood, B.
Object Type: Report
System: The UNT Digital Library
Systematic Process Synthesis and Design Methods for Cost Effective Waste Minimization. Final report (open access)

Systematic Process Synthesis and Design Methods for Cost Effective Waste Minimization. Final report

This report focuses on research done over the past four years under the grant with the above title. In addition, the report also includes a brief summary of work done before 1994 under grant DOE-DE-FG02-85ER13396. Finally, a complete list of publications that acknowledge support from this grant is listed at the end.
Date: February 14, 1998
Creator: Biegler, L. T.; Grossmann, I. E. & Westerberg, A. W.
Object Type: Report
System: The UNT Digital Library
[Geothermal system temperature-depth database and model for data analysis]. 4. quarterly technical progress report (open access)

[Geothermal system temperature-depth database and model for data analysis]. 4. quarterly technical progress report

The activities that have been carried out this quarter include continued planning and development of the geothermal system thermal-well data-base that will be one of the main contract results. The authors are continuing to modify the specifications of the database and continuing initial input. They have added several additional areas to their inventory of the geothermal areas for which data are available in the literature (published and open file) and on open file as described in the third quarterly report. A map was enclosed with the second quarterly report that gave the preliminary location of sites of various categories of wells. They will include a revised map with the next quarterly report when all of the sites, including the new ones described below, have been located and added to the index map. In particular in the last quarter the authors have added about 100 wells in west Texas in the transPecos region from a previously proprietary report that they recently obtained. In addition they have made arrangements to obtain thermal data collected by AMAX Geothermal during their exploration activities. The number of wells is large, several hundred, and the sites are spread throughout the western US from New Mexico and …
Date: February 19, 1998
Creator: Blackwell, D.D.
Object Type: Report
System: The UNT Digital Library
Anisotropic behavior in 0.5m scale blocks of Topopah Spring tuff (open access)

Anisotropic behavior in 0.5m scale blocks of Topopah Spring tuff

Laboratory tests on 0.5 meter scale blocks of Topopah Spring tuff were performed to determine fluid flow and mechanical behavior of samples containing fractures. Results include data for a comprehensive set of flow measurements through a rock sample containing a horizontally oriented fracture at uniaxial stress conditions up to 8 MPa at room temperature. Directional channeling, rather than mean fracture aperture, controls the flow. On the time scale of these experiments, inhibition is negligible.
Date: February 1, 1998
Creator: Blair, S. C. & Costantino, M. S.
Object Type: Article
System: The UNT Digital Library