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Radiation safety training for accelerator facilities (open access)

Radiation safety training for accelerator facilities

In November 1992, a working group was formed within the U.S. Department of Energy`s (DOE`s) accelerator facilities to develop a generic safety training program to meet the basic requirements for individuals working in accelerator facilities. This training, by necessity, includes sections for inserting facility-specific information. The resulting course materials were issued by DOE as a handbook under its technical standards in 1996. Because experimenters may be at a facility for only a short time and often at odd times during the day, the working group felt that computer-based training would be useful. To that end, Lawrence Livermore National Laboratory (LLNL) and Argonne National Laboratory (ANL) together have developed a computer-based safety training program for accelerator facilities. This interactive course not only enables trainees to receive facility- specific information, but time the training to their schedule and tailor it to their level of expertise.
Date: February 1, 1997
Creator: Trinoskey, P.A.
Object Type: Article
System: The UNT Digital Library
Materials science and engineering (open access)

Materials science and engineering

During FY-96, work within the Materials Science and Engineering Thrust Area was focused on material modeling. Our motivation for this work is to develop the capability to study the structural response of materials as well as material processing. These capabilities have been applied to a broad range of problems, in support of many programs at Lawrence Livermore National Laboratory. These studies are described in (1) Strength and Fracture Toughness of Material Interfaces; (2) Damage Evolution in Fiber Composite Materials; (3) Flashlamp Envelope Optical Properties and Failure Analysis; (4) Synthesis and Processing of Nanocrystalline Hydroxyapatite; and (5) Room Temperature Creep Compliance of Bulk Kel-E.
Date: February 1, 1997
Creator: Lesuer, D. R.
Object Type: Report
System: The UNT Digital Library
Record of decision remedial alternative selection for the F-area burning/rubble pits (231-F, 231-1F, and 231-2F) (open access)

Record of decision remedial alternative selection for the F-area burning/rubble pits (231-F, 231-1F, and 231-2F)

This decision document presents the selected remedial alternative for the FBRP located at the SRS in Aiken, South Carolina. The selected alternative was developed in accordance with CERCLA, as amended, and to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan. This decision is based on the Administrative Record File for this specific RCRA/CERCLA unit.
Date: February 1, 1997
Creator: Palmer, E.
Object Type: Report
System: The UNT Digital Library
Calendar year 1996 annual groundwater monitoring report for the Upper East Fork Poplar Creek Hydrogeologic Regime at the U.S. Department of Energy Y-12 Plant, Oak Ridge, Tennessee (open access)

Calendar year 1996 annual groundwater monitoring report for the Upper East Fork Poplar Creek Hydrogeologic Regime at the U.S. Department of Energy Y-12 Plant, Oak Ridge, Tennessee

This annual monitoring report contains groundwater and surface water monitoring data obtained in the Upper East Fork Poplar Creek Hydrogeologic Regime (East Fork Regime) during calendar year (CY) 1996. The East Fork Regime encompasses several confirmed and suspected sources of groundwater contamination within industrialized areas of the US Department of Energy (DOE) Oak Ridge Y-12 Plant in Bear Creek Valley (BCV) southeast of Oak Ridge, Tennessee. Groundwater and surface water monitoring in the East Fork Regime are performed under the auspices of the Y-12 Plant Groundwater Protection Program (GWPP). Included are the groundwater monitoring data obtained in compliance with the Resource Conservation and Recovery Act (RCRA) post-closure permit for the East Fork Regime issued by the Tennessee Department of Environment and Conservation (TDEC) on August 30, 1996. The post-closure permit addresses post-closure monitoring requirements for two closed RCRA-regulated surface impoundments: the S-3 Ponds and New Hope Pond.
Date: February 1, 1997
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Fracture toughness evaluations of TP304 stainless steel pipes (open access)

Fracture toughness evaluations of TP304 stainless steel pipes

In the IPIRG-1 program, the J-R curve calculated for a 16-inch nominal diameter, Schedule 100 TP304 stainless steel (DP2-A8) surface-cracked pipe experiment (Experiment 1.3-3) was considerably lower than the quasi-static, monotonic J-R curve calculated from a C(T) specimen (A8-12a). The results from several related investigations conducted to determine the cause of the observed toughness difference are: (1) chemical analyses on sections of Pipe DP2-A8 from several surface-cracked pipe and material property specimen fracture surfaces indicate that there are two distinct heats of material within Pipe DP2-A8 that differ in chemical composition; (2) SEN(T) specimen experimental results indicate that the toughness of a surface-cracked specimen is highly dependent on the depth of the initial crack, in addition, the J-R curves from the SEN(T) specimens closely match the J-R curve from the surface-cracked pipe experiment; (3) C(T) experimental results suggest that there is a large difference in the quasi-static, monotonic toughness between the two heats of DP2-A8, as well as a toughness degradation in the lower toughness heat of material (DP2-A8II) when loaded with a dynamic, cyclic (R = {minus}0.3) loading history.
Date: February 1, 1997
Creator: Rudland, D. L.; Brust, F. W. & Wilkowski, G. M.
Object Type: Report
System: The UNT Digital Library
Factors affecting coercivity in rare-earth based advanced permanent magnet materials (open access)

Factors affecting coercivity in rare-earth based advanced permanent magnet materials

The relationships that link microstructural properties of advanced permanent magnet materials with magnetic properties such as the coercivity are often difficult to quantify, especially in materials with nano-scale structures. Recent work on RE{sub 2}Fe{sub 14}B-based powders fabricated with rapid-solidification techniques such as inert gas atomization (IGA) and melt-spinning provide insight into the nanostructural features which affect the acquisition and stability of coercivity. In all cases the coercivity is found to be a function of both the scale of the constituent microstructure and of the presence and distribution of minor phases.
Date: February 1, 1997
Creator: Lewis, L.H.; Sellers, C.H. & Panchanathan, V.
Object Type: Report
System: The UNT Digital Library
Hanford Site groundwater monitoring for fiscal year 1996 (open access)

Hanford Site groundwater monitoring for fiscal year 1996

This report presents the results of groundwater and vadose-zone monitoring for fiscal year (FY) 1996 on the Hanford Site, Washington. Hanford Site operations from 1943 onward produced large quantities of radiological and chemical waste that affected groundwater quality on the site. Characterization and monitoring of the vadose zone during FY 1996 comprised primarily spectral gamma logging, soil-gas monitoring, and electrical resistivity tomography. Water-level monitoring was performed to evaluate groundwater-flow directions, to track changes in water levels, and to relate such changes to evolving disposal practices. Water levels over most of the Hanford Site continued to decline between June 1995 and June 1996. Groundwater chemistry was monitored to track the extent of contamination, to note trends, and to identify emerging groundwater-quality problems. The most widespread radiological contaminant plumes were tritium and iodine-129. Smaller plumes of strontium-90, technetium-99, and plutonium also were present at levels above the U.S. Environmental Protection Agency or State of Washington interim drinking water standards. Uranium concentrations greater than the proposed drinking water standard were also observed. Nitrate, fluoride, chromium, carbon tetrachloride, chloroform, trichloroethylene, and cis-1,2-dichlomethylene were present in groundwater samples at levels above their U.S. Environmental Protection Agency or State of Washington maximum contaminant levels. The nitrate …
Date: February 1, 1997
Creator: Hartman, M. J.; Dresel, P. E. & Borghese, J. V.
Object Type: Report
System: The UNT Digital Library
Evaluation and monitoring plan for consolidation tanks: Gunite and Associated Tanks Operable Unit, Waste Area Grouping 1, Oak Ridge National Laboratory, Oak Ridge, Tennessee (open access)

Evaluation and monitoring plan for consolidation tanks: Gunite and Associated Tanks Operable Unit, Waste Area Grouping 1, Oak Ridge National Laboratory, Oak Ridge, Tennessee

This report describes the results of an integrity evaluation of Tanks W-8 and W-9, part of the Gunite and Associated Tanks (GAAT), in the South Tank Farm at Oak Ridge National Laboratory (ORNL), together with a plan for monitoring those tanks for potential releases during the GAAT CERCLA treatability study and waste removal activities. This work was done in support of an ORNL plan to use W-8 and W-9 as consolidation tanks during remediation of the other tanks in the North and South Tank Farms. The analysis portion of the report draws upon both tank-internal measurements of liquid volume change and tank-external measurements of the change in electrical conductivity of the groundwater in the dry wells adjacent to each tank. The results of the analysis show that both W-8 and W-9 are liquid-tight and are suitable for use as consolidation tanks. The recommended monitoring plan will utilize the dry well conductivity monitoring method as the primary release detection tool during the CERCLA activities. This method is expected to be able to detect releases of less than 0.5 gal/h with a 95% probability of detection, most of the time. The results described here validate three prior independent efforts: a liquid integrity …
Date: February 1, 1997
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Towards a formal taxonomy of hybrid uncertainty representations (open access)

Towards a formal taxonomy of hybrid uncertainty representations

Recent years have seen a proliferation of methods in addition to probability theory to represent information and uncertainty, including fuzzy sets and systems, fuzzy measures, rough sets, random sets, possibility distributions, imprecise probabilities, etc. We can identify these fields collectively as General Information Theory. The components of GIT represent information according to different axiomatic bases, and are thus capable of capturing different semantic aspects of uncertainty. Traditionally, these semantic criteria include such categories as fuzziness, vagueness, nonspecificity, conflict, and randomness. So it is clear that there is a pressing need for the GIT community to synthesize these methods, searching out larger formal frameworks within which to place these various components with respect to each other. Ideally, syntactic (mathematical) generalization can both aid and be aided by the semantic analysis available in terms of the conceptual categories outlined above. In this paper we present some preliminary ideas about how to formally relate various uncertainty representations together in a taxonomic lattice, capturing both syntactic and semantic generalization. Some partial and provisional results are shown. Assume a simple finite universe of discourse {Omega} = (a, b, c). We want to describe a situation in which we ask a question of the sort {open_quotes}what …
Date: February 1, 1997
Creator: Joslyn, C. & Rocha, L.
Object Type: Article
System: The UNT Digital Library
Meeting the constraint of neutrino-Higgsino mixing in gravity unified theories (open access)

Meeting the constraint of neutrino-Higgsino mixing in gravity unified theories

In Gravity Unified Theories all operators that are consistent with the local gauge and discrete symmetries are expected to arise in the effective low-energy theory. given the absence of multiplets like 126 of S0(10) in string models, and assuming that B - L is violated spontaneously to generate light neutrino masses via a seesaw mechanism, it is observed that string theory solutions genetically face the problem of producing an excessive {nu}{sub L} - {tilde H} mixing mass at the GUT scale, which is some nineteen orders of magnitude larger than the experimental bound of 1 MeV. The suppression of {nu}{sub L} - {tilde H} mixing, like proton longevity, thus provides one of the most severe restraints on the validity of any string theory solution. We examine this problem in a class of superstring derived models. We find a family of solutions within this class for which the symmetries of the models and an allowed pattern of VEVs, surprisingly, succeed in adequately suppressing the neutrino-Higgsino mixing terms. At the same time they produce the terms required to generate small neutrino masses via seesaw mechanism.
Date: February 1, 1997
Creator: Faraggi, A.E. & Pati, J.C.
Object Type: Report
System: The UNT Digital Library
A simple arc column model that accounts for the relationship between voltage, current and electrode gap during VAR (open access)

A simple arc column model that accounts for the relationship between voltage, current and electrode gap during VAR

Mean arc voltage is a process parameter commonly used in vacuum arc remelting (VAR) control schemes. The response of this parameter to changes in melting current (I) and electrode gap (g{sub e}) at constant pressure may be accurately described by an equation of the form V = V{sub 0} + c{sub 1}g{sub e}I + c{sub 2}g{sub e}{sup 2} + c{sub 3}I{sup 2}, where c{sub 1}, c{sub 2} and c{sub 3} are constants, and where the non-linear terms generally constitute a relatively small correction. If the non-linear terms are ignored, the equation has the form of Ohm`s law with a constant offset (V{sub 0}), c{sub 1}g{sub e} playing the role of resistance. This implies that the arc column may be treated approximately as a simple resistor during constant current VAR, the resistance changing linearly with g{sub e}. The VAR furnace arc is known to originate from multiple cathode spot clusters situated randomly on the electrode tip surface. Each cluster marks a point of exist for conduction electrons leaving the cathode surface and entering the electrode gap. Because the spot clusters re highly localized on the cathode surface, each gives rise to an arc column that may be considered to operate independently …
Date: February 1, 1997
Creator: Williamson, R.L.
Object Type: Article
System: The UNT Digital Library
Light-trapped interconnected, Silicon-Film{trademark} modules. Annual technical status report, 18 November 1995--18 November 1996 (open access)

Light-trapped interconnected, Silicon-Film{trademark} modules. Annual technical status report, 18 November 1995--18 November 1996

AstroPower is developing a module-manufacturing technology based on a film-silicon technology. AstroPower, as a Technology Partner in the Thin-Film PV Partnership, is employing its Silicon-Film{trademark} technology to develop an advanced thin-silicon-based product. This module will combine the design and process features of the most advanced thin-silicon solar cells with light-trapping. These cells will be integrated into a low-cost interconnected array. During the second year of the 3-year project, AstroPower`s emphasis was on developing key submodule fabrication processes. Key results of the work include developing a new thin-film growth concept process based on attaching the low-cost substrate to the thin silicon layer after film growth; developing a new technique to achieve light-trapping in thin layers of silicon based on pigmented high-temperature glass materials; and developing key submodule fabrication processes, including contact grid design, subelement isolation, and screen-printed interconnection.
Date: February 1, 1997
Creator: Hall, R. B.; Rand, J. A.; Cotter, J. E. & Ford, D. H.
Object Type: Report
System: The UNT Digital Library
Self shielding in cylindrical fissile sources in the APNea system (open access)

Self shielding in cylindrical fissile sources in the APNea system

In order for a source of fissile material to be useful as a calibration instrument, it is necessary to know not only how much fissile material is in the source but also what the effective fissile content is. Because uranium and plutonium absorb thermal neutrons so Efficiently, material in the center of a sample is shielded from the external thermal flux by the surface layers of the material. Differential dieaway measurements in the APNea System of five different sets of cylindrical fissile sources show the various self shielding effects that are routinely encountered. A method for calculating the self shielding effect is presented and its predictions are compared with the experimental results.
Date: February 1, 1997
Creator: Hensley, D.
Object Type: Report
System: The UNT Digital Library
On the statistical strength of nicalon fibers and its characterization (open access)

On the statistical strength of nicalon fibers and its characterization

Nicalon fibers are one of the most attractive ceramic fibers for reinforcing high temperature structural composites. Experiment show that the diameter variation (from 8 to 22 {mu}m) in a tow of commercial Nicalon fibers has an effect on statistical strength distribution of Nicalon fibers. Therefore, an appropriate characterization of the statistical distribution of fiber strength, capable of accounting for the effect of diameter variation, is required. The two-parameter single-modal Weibull distribution is found inadequate for characterizing the strength of Nicalon fibers. This work demonstrates that a 3-parameter modified Weibull distribution can successfully characterize the strength of Nicalon fibers; this distribution yields a higher {beta} value, which indicates less scatter in fiber strength than with the 2-parameter single modal Weibull distribution. It more accurately treats the strength variation caused by diameter variation. It is also much easier to use than the 4-parameter bimodal. Moreover, it is seen to more accurately treat the strength variation caused by diameter variation than the single modal 2-parameter analysis.
Date: February 1, 1997
Creator: Zhu, Yuntian T.; Taylor, Seth T.; Stout, Michael G.; Butt, Darryl P.; Blumenthal, William R. & Lowe, Terry C.
Object Type: Article
System: The UNT Digital Library
Use of organic solderability preservatives on solderability retention of copper after accelerated aging (open access)

Use of organic solderability preservatives on solderability retention of copper after accelerated aging

Organic solderability preservatives (OSP`s) have been used by the electronics industry for some time to maintain the solderability of circuit boards and components. Since solderability affects both manufacturing efficiency and product reliability, there is significant interest in maintaining good solder wettability. There is often a considerable time interval between the initial fabrication of a circuit board or component and its use at the assembly level. Parts are often stored under a variety of conditions, in many cases not well controlled. Solder wettability can deteriorate during storage, especially in harsh environments. This paper describes the ongoing efforts at Sandia National Laboratories to quantify solder watability on bare and aged copper surfaces. Benzotriazole and imidazole were applied to electronic grade copper to retard aging effects on solderability. The coupons were introduced into Sandia`s Facility for Atmospheric Corrosion Testing (FACT) to simulate aging in a typical indoor industrial environment. H{sub 2}S, NO{sub 2} and Cl{sub 2} mixed gas was introduced into the test cell and maintained at 35{degrees}C and 70% relative humidity for test periods of one day to two weeks. The OSP`s generally performed better than bare Cu, although solderability diminished with increasing exposure times.
Date: February 1, 1997
Creator: Hernandez, C. L.; Sorensen, N. R. & Lucero, S. J.
Object Type: Article
System: The UNT Digital Library
Automatic TLI recognition system, programmer`s guide (open access)

Automatic TLI recognition system, programmer`s guide

This report describes the software of an automatic target recognition system (version 14), from a programmer`s point of view. The intent is to provide information that will help people who wish to modify the software. In separate volumes are a general description of the ATR system, Automatic TLI Recognition System, General Description, and a user`s manual, Automatic TLI Recognition System, User`s Guide. 2 refs.
Date: February 1, 1997
Creator: Lassahn, G.D.
Object Type: Report
System: The UNT Digital Library
A case study: using a multi-grout barrier to control {sup 90}Sr release at ORNL (open access)

A case study: using a multi-grout barrier to control {sup 90}Sr release at ORNL

During summer 1996, low-pressure permeation grouting was performed inside portions of four unlined, shallow waste disposal trenches at a radioactive waste burial ground that was opened in 1951 at the Oak Ridge National Laboratory (ORNL). The objective was to selectively control sources that release about 25 percent of all strontium 90 (90Sr) discharged from the ORNL complex. A unique grouting methodology was adapted to control interaction of wastes with natural runoff at this humid site. Driven sleeve pipes were injected 4 to 5 times with multiple formulae of type III portland cement- based grouts, ultra fine cement-based grouts, and acrylamide grouts. Multiple-hole grout injection was monitored continuously using real time monitoring equipment. Apparent Lugeon values were calculated during grouting operations and grout formulae were continually adjusted during injection to maximize permeation, durability, and economy. Over 500 cubic meters of combined grout types were emplaced. At the completion of production grouting, the effectiveness of grout spread and in situ hydraulic conductivity of the grouted mass were assessed. The average residual hydraulic conductivity measured in more than 20 check pipes was less than I x 10` cm/sec. Hydrologic monitoring has been established to determine the overall effectiveness of the project for 9OSr …
Date: February 1, 1997
Creator: Long, J.D.; Huff, D.D. & Naudts, A.A.
Object Type: Article
System: The UNT Digital Library
Effect of lead content on phase evolution and microstructural development in Ag-clad Bi-2223 composite conductors (open access)

Effect of lead content on phase evolution and microstructural development in Ag-clad Bi-2223 composite conductors

A two powder process was used to prepare silver-sheathed monofilamentary Bi{sub 1.8}Pb{sub x}Sr{sub 1.98}Ca{sub 1.97}Cu{sub 3.08}O{sub y} (Bi-2223) tapes with varying lead contents, x, from 0.2 to 0.5. The resulting tapes were subjected to thermomechanical processing and then characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray analysis (EDX). Layered phase texture was accessed using image analysis software on scanned SEM micrographs. Transport currents were measured at 77 K and zero field by the four-probe method. It was found that tapes with low lead content (X = 0.2 and 0.25) showed incomplete conversion to Bi-2223, had small grain size and poor c-axis texture. Tapes having higher lead content (x = 0.4 and 0.5) also showed incomplete conversion and the presence of lead-rich secondary phases. Tapes with lead content x = 0.3 and 0.35 showed complete conversion to Bi-2223, and had the least amount of secondary phases, the best c-axis texture, and the highest transport current (j{sub c}). The carbon content of the precursor powder also had a strong influence on secondary-phase chemistry.
Date: February 1, 1997
Creator: Merchant, N. N.; Maroni, V. A.; Fischer, A. K.; Dorris, S. E.; Zhong, W. & Ashcom, N.
Object Type: Report
System: The UNT Digital Library
Algorithm for image registration and clutter and jitter noise reduction (open access)

Algorithm for image registration and clutter and jitter noise reduction

This paper presents an analytical, computational method whereby two-dimensional images of an optical source represented in terms of a set of detector array signals can be registered with respect to a reference set of detector array signals. The detector image is recovered from the detector array signals and represented over a local region by a fourth order, two-dimensional taylor series. This local detector image can then be registered by a general linear transformation with respect to a reference detector image. The detector signal in the reference frame is reconstructed by integrating this detector image over the respective reference pixel. For cases in which the general linear transformation is uncertain by up to plus-or-minus two pixels, the general linear transformation can be determined by least squares fitting the detector image to the reference detector image. This registration process reduces clutter and jitter noise to a level comparable to the electronic noise level of the detector system. Test results with and without electronic noise using an analytical test function are presented.
Date: February 1, 1997
Creator: Brower, K.L.
Object Type: Report
System: The UNT Digital Library
Dual Arm Work Package performance estimates and telerobot task network simulation (open access)

Dual Arm Work Package performance estimates and telerobot task network simulation

This paper describes the methodology and results of a network simulation study of the Dual Arm Work Package (DAWP), to be employed for dismantling the Argonne National Laboratory CP-5 reactor. The development of the simulation model was based upon the results of a task analysis for the same system. This study was performed by the Oak Ridge National Laboratory (ORNL), in the Robotics and Process Systems Division. Funding was provided the US Department of Energy`s Office of Technology Development, Robotics Technology Development Program (RTDP). The RTDP is developing methods of computer simulation to estimate telerobotic system performance. Data were collected to provide point estimates to be used in a task network simulation model. Three skilled operators performed six repetitions of a pipe cutting task representative of typical teleoperation cutting operations.
Date: February 1, 1997
Creator: Draper, J.V. & Blair, L.M.
Object Type: Article
System: The UNT Digital Library
Advanced turbine systems sensors and controls needs assessment study. Final report (open access)

Advanced turbine systems sensors and controls needs assessment study. Final report

The Instrumentation and Controls Division of the Oak Ridge National Laboratory performed an assessment of the sensors and controls needs for land-based advanced gas turbines being designed as a part of the Department of Energy`s (DOE`s) Advanced Turbine Systems (ATS) Program for both utility and industrial applications. The assessment included visits to five turbine manufacturers. During these visits, in-depth discussions were held with design and manufacturing staff to obtain their views regarding the need for new sensors and controls for their advanced turbine designs. The Unsteady Combustion Facilities at the Morgantown Energy Technology Center was visited to assess the need for new sensors for gas turbine combustion research. Finally, a workshop was conducted at the South Carolina Energy Research and Development Center which provided a forum for industry, laboratory, and university engineers to discuss and prioritize sensor and control needs. The assessment identified more than 50 different measurement, control, and monitoring needs for advanced turbines that cannot currently be met from commercial sources. While all the identified needs are important, some are absolutely critical to the success of the ATS Program.
Date: February 1, 1997
Creator: Anderson, R.L.; Fry, D.N. & McEvers, J.A.
Object Type: Report
System: The UNT Digital Library
Investigation of defects in highly photosensitive germanosilicate thin films (open access)

Investigation of defects in highly photosensitive germanosilicate thin films

Germanosilicate glasses exhibit a significant photosensitive response which has been linked to the presence of oxygen-deficient germanium point defects in the glass structure. Based on this correlation, highly photosensitive thin films have been engineered which demonstrate the largest reported ultraviolet-induced refractive index perturbations (An) in an as-synthesized material. Our thin-film fabrication process avoids the use of hydrogen sensitizing treatments and, thus, yields stable films which retain their predisposition for large photosensitivity for over one year of storage. Understanding the nature of the defects in such films and their relationship to charge trapping and enhanced photosensitivity is of paramount importance in designing and optimizing the materials. Toward this end, our films have been studied using electron paramagnetic resonance (EPR), capacitance-voltage, and optical bleaching and absorption spectroscopies. We find experimental evidence suggesting a model in which a change in spin state and charge state of isolated paramagnetic neutral Ge dangling bonds form either diamagnetic positively or negatively charged Ge sites which are largely responsible for the charge trapping and photosensitivity in these thin films. We present experimental data and theoretical modeling to support our defect model and to show the relevance of the work.
Date: February 1, 1997
Creator: Simmons-Potter, K.; Potter, B.G. Jr. & Warren, W.L.
Object Type: Article
System: The UNT Digital Library
A complete monolithically-integrated circuit for all-optical generation of millimeter-wave frequencies (open access)

A complete monolithically-integrated circuit for all-optical generation of millimeter-wave frequencies

An optoelectronic integrated circuit for generating mm-wave frequencies is demonstrated and design issues detailed. A monolithically integrated ring laser, optical amplifier, and photodiode generate electrical signals up to 85.2 GHz.
Date: February 1, 1997
Creator: Vawter, G. A.; Mar, A.; Hietala, V. & Zolper, J.
Object Type: Article
System: The UNT Digital Library
Black box multigrid solver for definite and indefinite problems (open access)

Black box multigrid solver for definite and indefinite problems

A two-level analysis method for certain separable problems is introduced. It motivates the definition of improved versions of Black Box Multigrid for diffusion problems with discontinuous coefficients and indefinite Helmholtz equations. For anisotropic problems, it helps in choosing suitable implementations for frequency decomposition multigrid methods. For highly indefinite problems, it provides a way to choose in advance a suitable mesh size for the coarsest grid used. Numerical experiments confirm the analysis and show the advantage of the present methods for several examples.
Date: February 1, 1997
Creator: Shapira, Yair
Object Type: Report
System: The UNT Digital Library