Characterization and Process Development of Cyanate Ester Resin Composites (open access)

Characterization and Process Development of Cyanate Ester Resin Composites

Cyanate ester resins offer advantages as composite matrices because of their high thermal stability, low outgassing, low water absorption, and radiation resistance. This paper describes the results of a processing study to develop a high-strength hoop-wound composite by the wet-filament winding method using Toray TI 000G carbon fiber and YLA RS- 14A cyanate ester resin as the constituent materials. The study shows that the cyanate ester resin has a broad process envelope but that an inert-atmosphere cure is essential for obtaining optimum resin and composite properties. Minimizing moisture exposure prior to and during cure is also crucial as it affects the glass transition temperature of the resin and composite. Composite cylinders wound and cured with these methods yielded excellent ring tensile strengths both at room and elevated temperature. A summary of the measured mechanical and thermal property data for these composites is presented. Potential applications for these materials include flywheeI energy storage systems for space and satellite structures.
Date: May 23, 1999
Creator: Frame, B.J.
Object Type: Article
System: The UNT Digital Library
Fiber-Matrix Interface Studies on Electron Beam Cured Composites (open access)

Fiber-Matrix Interface Studies on Electron Beam Cured Composites

The recently completed Department of Energy (DOE) and industry sponsored Cooperative Research and Development Agreement (CRADA) entitled, ''Electron Beam Curing of Polymer Matrix Composites,'' determined that the interlaminar shear strength properties of the best electron beam cured IM7/epoxy composites were 19-28% lower than autoclave cured IM7/epoxy composites (i.e. IM7/977-2 and IM7/977-3). Low interlaminar shear strength is widely acknowledged as the key barrier to the successful acceptance and implementation of electron beam cured composites in the aircraft/aerospace industry. The objective of this work was to improve the interlaminar shear strength properties of electron beam cured composites by formulating and evaluating several different fiber sizings or coating materials. The researchers have recently achieved some promising results by having discovered that the application of epoxy-based, electron beam compatible sizings or coatings onto surface-treated, unsized IM7 carbon fibers improved the composite interlaminar shear strength properties by as much as 55% versus composites fabricated from surface-treated, unsized IM7 fibers. In addition, by applying these same epoxy-based sizings or coatings onto surface-treated, unsized IM7 fibers it was possible to achieve an 11% increase in the composite interlaminar shear strength compared to composites made from surface-treated, GP-sized IM7 fibers. Work is continuing in this area of research …
Date: May 23, 1999
Creator: Drazel, L. T.; Janke, C. J. & Yarborough, K. D.
Object Type: Article
System: The UNT Digital Library
Step structure of GaInAsSb grown by OMVPE (Organometallic Vapor Phase Epitaxy) (open access)

Step structure of GaInAsSb grown by OMVPE (Organometallic Vapor Phase Epitaxy)

The microscopic surface morphology of GaInAsSb grown by organometallic vapor phase epitaxy (OMVPE)on GaSb substrates has been studied by atomic force microscopy. The effects of growth temperature, alloy composition, and substrate misorientation on the step structure were investigated. The competition between thermodynamically driven phase separation and kinetically limited surface diffusion is discussed.
Date: May 23, 1999
Creator: Charache, G.W. & Wang, C.A.
Object Type: Article
System: The UNT Digital Library
X-Ray Scattering Applications Using Pulsed X-Ray Sources (open access)

X-Ray Scattering Applications Using Pulsed X-Ray Sources

Pulsed x-ray sources have been used in transient structural phenomena investigations for over fifty years; however, until the advent of synchrotrons sources and the development of table-top picosecond lasers, general access to ligh temporal resolution x-ray diffraction was relatively limited. Advances in diffraction techniques, sample excitation schemes, and detector systems, in addition to IncEased access to pulsed sources, have ld tO what is now a diverse and growing array of pulsed-source measurement applications. A survey of time-resolved investigations using pulsed x-ray sources is presented and research opportunities using both present and planned pulsed x-ray sources are discussed.
Date: May 23, 1999
Creator: Larson, B.C.
Object Type: Article
System: The UNT Digital Library
Axionic hot dark matter in the hadronic axion window (open access)

Axionic hot dark matter in the hadronic axion window

Mixed dark matter scenario can reconcile the COBE data and the observed large scale structure. So far the massive neutrino with a mass of a few eV has been the only discussed candidate for the hot dark matter component. We point out that the hadronic axion in the so-called hadronic axion window, f{sub a} {approx} 10{sup 6} GeV, is a perfect candidate as hot dark matter within the mixed dark matter scenario. The current limits on the hadronic axion are summarized. The most promising methods to verify the hadronic axion in this window are the resonant absorption of almost-monochromatic solar axions from M1 transition of the thermally excited {sup 57}Fe in the Sun, and the observation of the ''axion burst'' in water Cerenkov detectors from another supernova.
Date: May 23, 1998
Creator: Moroi, Takeo & Murayama, Hitoshi
Object Type: Article
System: The UNT Digital Library
Accelerator modeling at SPEAR (open access)

Accelerator modeling at SPEAR

The response matrix, consisting of the closed orbit change at each beam position monitor (BPM) due to corrector magnet excitations, was measured and analyzed in order to calibrate a linear optics model of SPEAR. The model calibration was accomplished by varying model parameters to minimize the chi-square difference between the measured and the model response matrices. The singular value decomposition (SVD) matrix inversion method was used to solve the simultaneous equations. The calibrated model was then used to calculate corrections to the operational lattice. The results of the calibration and correction procedures are presented.
Date: May 23, 1997
Creator: LeBlanc, G. & Corbett, W.J.
Object Type: Article
System: The UNT Digital Library
Accurate atomistic simulations of the Peierls barrier and kink-pair formation energy for {lt}111{gt} screw dislocations in bcc-Mo (open access)

Accurate atomistic simulations of the Peierls barrier and kink-pair formation energy for {lt}111{gt} screw dislocations in bcc-Mo

Using multi-ion MGPT interatomic potentials derived from first- principles generalized pseudopotential theory, we have performed accurate atomistic simulations on the energetic of dislocation motion in the bcc transition metal Mo. Our calculated results include the (110) and (211) generalized stacking fault ({gamma}) energy surfaces, the Peierls stress required to move an ideal straight <111> screw dislocation, and the kink-pair formation energy for nonstraight screw dislocations. Many-body angular forces, which are accounted for in the present theory through explicit three- and four-ion potentials, are quantitatively important to such properties for the bcc transition metals. This is demonstrated explicitly through the calculated {gamma} surfaces, which are found to be 10-50% higher in energy than those obtained with pure radial-force models. The Peierls stress for an applied <111>/{l_brace}112{r_brace} shear is computed to be about 0.025{mu}, where {mu} is the bulk shear modulus. For zero applied stress, stable kink pairs are predicted to form for kink lengths greater than 4b, where b is the magnitude of the Burgers vector. For long kinks greater than 15b, the calculated asymptotic value of the kink-pair formation energy is 2.0 eV.
Date: May 23, 1997
Creator: Xu, W. & Moriarty, J.A.
Object Type: Article
System: The UNT Digital Library
Advanced ceramics for land-based gas turbine applications. Final report (open access)

Advanced ceramics for land-based gas turbine applications. Final report

In order to increase the efficiency of land-based gas turbines, inlet gas temperatures have to be increased, and the amount of air which cools the turbine vanes has to be reduced, to the maximum extent possible. Presently, thermal barrier coatings (TBC`s) are the state of the art in achieving these goals. However, since TBC`s are very thin (typically 100 {mu}m), they have clearly limitations. Since all-ceramic turbine vanes would be a very large and risky development step, Westinghouse is considering to protect the leading edges of turbine vanes with high-performance ceramics. This might be done by either replacing the leading edge with a suitably shaped ceramic part, or by modifying the vanes such that they can accommodate ceramic inserts. Among the most important criteria for the success of ceramics in such applications are (a) thermodynamic compatibility with the turbine vane alloy, (b) sufficient thermal shock resistance to survive the thermal cycling during operation and in particular during emergency shut-down, and a design considering the thermal expansion mismatch of the metallic and ceramic components. This paper presents results of work performed on SiC, SiN, and aluminas.
Date: May 23, 1997
Creator: Schneibel, J.H.; Ludeman, E. & Sabol, S.M.
Object Type: Report
System: The UNT Digital Library
FUTURE CLIMATE MODELING SCENARIOS (open access)

FUTURE CLIMATE MODELING SCENARIOS

None
Date: May 23, 1997
Creator: F.J. SCHELLING, S.L. THOMPSON
Object Type: Report
System: The UNT Digital Library
High Efficiency Vapor-Fed AMTEC System for Direct Conversion. Appendices for Final Report (open access)

High Efficiency Vapor-Fed AMTEC System for Direct Conversion. Appendices for Final Report

This report consists of four appendices for the final report. They are: Appendix A: 700 C Vapor-Fed AMTEC Cell Calculations; Appendix B: 700 C Vapor-Fed AMTEC Cell Parts Drawings; Appendix C: 800 C Vapor-Fed AMTEC Cell Calculations; and Appendix D: 800 C Wick-Pumped AMTEC Cell System Design.
Date: May 23, 1997
Creator: Anderson, W. G. & Bland, J. J.
Object Type: Report
System: The UNT Digital Library
High Efficiency Vapor-Fed AMTEC System for Direct Conversion. Final Report (open access)

High Efficiency Vapor-Fed AMTEC System for Direct Conversion. Final Report

The Alkali Metal Thermal to Electric Converter (AMTEC) is a high temperature, high efficiency system for converting thermal to electrical energy, with no moving parts. It is based on the unique properties of {beta}{double_prime}-alumina solid electrolyte (BASE), which is an excellent conductor of sodium ions, but an extremely poor conductor of electrons. When the inside of the BASE is maintained at a higher temperature and pressure, a concentration gradient is created across the BASE. Electrons and sodium atoms cannot pass through the BASE. However, the sodium atoms are ionized, and the sodium ions move through the BASE to the lower potential (temperature) region. The electrons travel externally to the AMTEC cell, providing power. There are a number of potential advantages to a wick-pumped, vapor-fed AMTEC system when compared with other designs. A wick-pumped system uses capillary forces to passively return liquid to the evaporator, and to distribute the liquid in the evaporator. Since the fluid return is self-regulating, multiple BASE tubes can use a single remote condenser, potentially improving efficiency in advanced AMTEC designs. Since the system is vapor-fed, sodium vapor is supplied at a uniform temperature and flux to the BASE tube, even with non-uniform heat fluxes and temperatures …
Date: May 23, 1997
Creator: Anderson, W. G. & Bland, J. J.
Object Type: Report
System: The UNT Digital Library
Immobilization technology down-selection radiation barrier approach (open access)

Immobilization technology down-selection radiation barrier approach

Six immobilization technology projects variants, previously selected for evaluation during the PEIS/ROD process, have been evaluated with respect to the nine basic criteria for fissile materials disposition. Metrics for the criteria were developed to facilitate a comparative analysis of the technology variants. The six technology variants are grouped according to their radiation barrier approach. Information and data for the technology options were provided by limited experimental studies, definitions of process flowsheets, and preliminary evaluations of facility concepts and costs.
Date: May 23, 1997
Creator: Gray, L.W. & Gould, T.H.
Object Type: Report
System: The UNT Digital Library
Magnetometer calibration and test procedure (open access)

Magnetometer calibration and test procedure

Nuclear waste has been sluiced and pumped from storage tank 241-AX-104, leaving a contaminated heel volume. These operations did not include measurements of the removed waste volume leaving an unknown heel volume in the tank. A magnetometer transducer will be lowered through tank riser ports to rest on the heel`s surface. The heel thickness will control the distance between the transducer and the tank`s bottom The instrument`s output varies with the distance from a magnetic mass, such as the tank`s steel bottom, thereby enabling a measurement of the heel depth. Measurements at several tank locations will permit an estimate of the tank`s heel volume. The magnetometer`s output is influenced by adjacent magnetic materials, such as the tank walls, air lift circulators or other equipment installed in the tank. An adjacent vertical steel surface produces a voltage offset in the instrument`s output. Measurements near a tank wall or other tank components may be corrected by noting the offset before the instrument`s output is influenced by the tank bottom. An unlevel or uneven heel surface could orient the magnetometer transducer so that it is not vertically level. The magnetometer readings are influenced by these skewed transducer orientations. The magnitude of these errors …
Date: May 23, 1997
Creator: Squier, D. M.
Object Type: Report
System: The UNT Digital Library
Quantum groups, roots of unity and particles on quantized Anti-de Sitter space (open access)

Quantum groups, roots of unity and particles on quantized Anti-de Sitter space

Quantum groups in general and the quantum Anti-de Sitter group U{sub q}(so(2,3)) in particular are studied from the point of view of quantum field theory. The author shows that if q is a suitable root of unity, there exist finite-dimensional, unitary representations corresponding to essentially all the classical one-particle representations with (half) integer spin, with the same structure at low energies as in the classical case. In the massless case for spin {ge} 1, {open_quotes}naive{close_quotes} representations are unitarizable only after factoring out a subspace of {open_quotes}pure gauges{close_quotes}, as classically. Unitary many-particle representations are defined, with the correct classical limit. Furthermore, the author identifies a remarkable element Q in the center of U{sub q}(g), which plays the role of a BRST operator in the case of U{sub q}(so(2,3)) at roots of unity, for any spin {ge} 1. The associated ghosts are an intrinsic part of the indecomposable representations. The author shows how to define an involution on algebras of creation and anihilation operators at roots of unity, in an example corresponding to non-identical particles. It is shown how nonabelian gauge fields appear naturally in this framework, without having to define connections on fiber bundles. Integration on Quantum Euclidean space and sphere …
Date: May 23, 1997
Creator: Steinacker, H.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Strategy for resolution of the flammable gas safety issue (open access)

Strategy for resolution of the flammable gas safety issue

This document provides a strategy for resolution of the Flammable Gas Safety Issue. It defines the key elements required for the following: Closing the Flammable Gas Unreviewed Safety Question (USQ); Providing the administrative basis for resolving the safety issue; Defining the data needed to support these activities; and Providing the technical and administrative path for removing tanks from the Watch List.
Date: May 23, 1997
Creator: Johnson, G. D.
Object Type: Report
System: The UNT Digital Library
Tank characterization report for single-shell tank 241-C-109 (open access)

Tank characterization report for single-shell tank 241-C-109

One of the major functions of the Tank Waste Remediation System (TWRS) is to characterize wastes in support of waste management and disposal activities at the Hanford Site. Analytical data from sampling and analysis, along with other available information about a tank, are compiled and maintained in a tank characterization report (TCR). This report and its appendices serve as the TCR for single-shell tank 241-C-109. The objectives of this report are: (1) to use characterization data in response to technical issues associated with tank 241 C-109 waste; and (2) to provide a standard characterization of this waste in terms of a best-basis inventory estimate. The response to technical issues is summarized in Section 2.0, and the best-basis inventory estimate is presented in Section 3.0. Recommendations regarding safety status and additional sampling needs are provided in Section 4.0. Supporting data and information are contained in the appendices.
Date: May 23, 1997
Creator: Simpson, B. C.
Object Type: Report
System: The UNT Digital Library
Tomographic Site Characterization Using CPT, ERT, and GPR (open access)

Tomographic Site Characterization Using CPT, ERT, and GPR

The U.S. Department of Energy (DOE) is responsible for the cleanup of inactive DOE sites and for bringing DOE sites and facilities into compliance with federal, state and local laws and regulations. The DOE's Office of Environmental Management (EM) needs advanced technologies that can make environmental restoration and waste management operations more efficient and less costly. These techniques are required to better characterize the physical, hydrogeological, and chemical properties of the subsurface while minimizing and optimizing the use of boreholes and monitoring wells. Today the cone penetrometer technique (CPT) is demonstrating the value of a minimally invasive deployment system fix site characterization. Applied Research Associates is developing two new sensor packages for site characterization and monitoring. The two new methods are: . Electrical Resistivity Tomography (ERT) and . Ground Penetrating Radar (GPR) Tomography. These sensor systems are now integrated with the Cone Penetrometer Technique (CPT). The results of this program now make it possible to install ERT and GPR units by CPT methods and thereby reduce installation costs and total costs for ERT and GPR surveys. These two techniques can complement each other in regions of low resistivity where ERT is more effective and regions of high resistivity where GPR …
Date: May 23, 1997
Creator: Morey, Rexford M.
Object Type: Report
System: The UNT Digital Library
Appalachian Clean Coal Technology Consortium. Technical progress report, January 1--March 31, 1996 (open access)

Appalachian Clean Coal Technology Consortium. Technical progress report, January 1--March 31, 1996

The Appalachian Clean Coal Technology Consortium has been established to help U.S. Coal producers, particularly those in the Appalachian region, increase the production of lower-sulfur coal. In keeping with the recommendations of the Advisory Committee, first-year R&D activities are focused on two areas of research: fine coal dewatering and modeling of spirals. The industry representatives to the Consortium identified fine coal dewatering as the most needed area of technology development. Dewatering studies are conducted by Virginia Tech`s Center for Coal and Minerals Processing. A spiral model will be developed by West Virginia University. The research to be performed by the University of Kentucky has recently been defined as: A Study of Novel Approaches for Destabilization of Flotation Froth. Accomplishments to date of these three projects are presented in this report.
Date: May 23, 1996
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Electronmagnetic induction probe calibration for electrical conductivity measurements and moisture content determination of Hanford high level waste (open access)

Electronmagnetic induction probe calibration for electrical conductivity measurements and moisture content determination of Hanford high level waste

Logic of converting EMI measured electrical conductivity to moisture with expected uncertainty. Estimates from present knowledge, assumptions, and measured data. Archie`s Law has been used since the 1940`s to relate electrical conductivity in porous media to liquid volume fraction. Measured electrical conductivity to moisture content uses: Porosity, Interstitial liquid electrical conductivity, Solid particle density,Interstitial liquid density, and interstitial liquid water content. The uncertainty of assumed values is calculated to determine the final moisture wt.% result uncertainty.
Date: May 23, 1996
Creator: Wittekind, W.D., Westinghouse Hanford
Object Type: Report
System: The UNT Digital Library
FY 1996 solid waste integrated life-cycle forecast characteristics summary. Volumes 1 and 2 (open access)

FY 1996 solid waste integrated life-cycle forecast characteristics summary. Volumes 1 and 2

For the past six years, a waste volume forecast has been collected annually from onsite and offsite generators that currently ship or are planning to ship solid waste to the Westinghouse Hanford Company`s Central Waste Complex (CWC). This document provides a description of the physical waste forms, hazardous waste constituents, and radionuclides of the waste expected to be shipped to the CWC from 1996 through the remaining life cycle of the Hanford Site (assumed to extend to 2070). In previous years, forecast data has been reported for a 30-year time period; however, the life-cycle approach was adopted this year to maintain consistency with FY 1996 Multi-Year Program Plans. This document is a companion report to two previous reports: the more detailed report on waste volumes, WHC-EP-0900, FY1996 Solid Waste Integrated Life-Cycle Forecast Volume Summary and the report on expected containers, WHC-EP-0903, FY1996 Solid Waste Integrated Life-Cycle Forecast Container Summary. All three documents are based on data gathered during the FY 1995 data call and verified as of January, 1996. These documents are intended to be used in conjunction with other solid waste planning documents as references for short and long-term planning of the WHC Solid Waste Disposal Division`s treatment, storage, …
Date: May 23, 1996
Creator: Templeton, K. J.
Object Type: Report
System: The UNT Digital Library
Introduction to Python (open access)

Introduction to Python

This report contains viewgraphs on a object-oriented programming language called Python. The basic elements of Python and its new numerical extension are discussed.
Date: May 23, 1996
Creator: Dubois, P.F.
Object Type: Article
System: The UNT Digital Library
A review of ELMs in divertor tokamaks (open access)

A review of ELMs in divertor tokamaks

This paper reviews what is known about edge localized modes (ELMs), with an emphasis on their effect on the scrape-off layer and divertor plasmas. ELM effects have been measured in the ASDEX-U, C-Mod, COMPASS-D, DIII-D, JET, JFT-2M,JT-60U, and TCV tokamaks and are reported here. At least three types of ELMs have been identified and their salient features determined. Type-1 giant ELMs can cause the sudden loss of up to 10-15% of the plasma stored energy but their amplitude ({Delta}W/W) does not increase with increasing power. Type- 3 ELMs are observed near the H-mode power threshold and produce small energy dumps (1-3% of the stored energy). All ELMs increase the scrape- off layer plasma and produce particle fluxes on the divertor targets which are as much as ten times larger that the quiescent phase between ELMs. The divertor heat pulse is largest on the inner target, unlike that of L-Mode or quiescent H-mode; some tokamaks report radial structure in the heat flux profile which is suggestive of islands or helical structures. The power scaling of Type-1 ELM amplitude and frequency have been measured in several tokamaks and has recently been applied to predictions of the ELM Size in ITER. Concern over …
Date: May 23, 1996
Creator: Hill, D.N.
Object Type: Article
System: The UNT Digital Library
Safety overview of the National Ignition Facility (open access)

Safety overview of the National Ignition Facility

The National Ignition Facility (NIF) is a proposed US Department of Energy inertial confinement laser fusion facility. The candidate sites for locating the NIF are: Los Alamos National Laboratory, Sandia National Laboratory, the Nevada Test Site, and Lawrence Livermore National Laboratory (LLNL), the preferred site. The NIF will operate by focusing 192 laser beams onto a tiny deuterium- tritium target located at the center of a spherical target chamber. The NIF mission is to achieve inertial confinement fusion (ICF) ignition, access physical conditions in matter of interest to nuclear weapons physics, provide an above ground simulation capability for nuclear weapons effects testing, and contribute to the development of inertial fusion for electrical power production. The NIF has been classified as a radiological, low hazard facility on the basis of a preliminary hazards analysis and according to the DOE methodology for facility classification. This requires that a safety analysis be prepared under DOE Order 5481.1B, Safety Analysis and Review System. A draft Preliminary Safety Analysis Report (PSAR) has been written, and this will be finalized later in 1996. This paper summarizes the safety issues associated with the operation of the NIF. It provides an overview of the hazards, estimates maximum routine …
Date: May 23, 1996
Creator: Brereton, S.J.; McLouth, L.; Odell, B.; Singh, M.; Tobin, M. & Trent, M.
Object Type: Article
System: The UNT Digital Library
Tank characterization report for single-shell tank 241-U-110 (open access)

Tank characterization report for single-shell tank 241-U-110

This tank characterization report for Tank 241-U-110 was initially released as WHC-EP-0643. This document is now being released as WHC- SD-WM-ER-551 in order to accommodate internet publishing.
Date: May 23, 1996
Creator: Brown, T. M.
Object Type: Report
System: The UNT Digital Library