9 Matching Results

Results open in a new window/tab.

Core-level spectroscopy of thin oxides and oxynitrides (open access)

Core-level spectroscopy of thin oxides and oxynitrides

Several spectroscopic methods are discussed that use core levels, such as photoelectron spectroscopy and absorption spectroscopy with photoelectron or fluorescence detection. Measurements are presented on the desorption of a chemical oxide and the growth of oxynitrides with N{sub 2}0 on Si(100). The stoichiometry is found to change strongly with thickness, from a nitrogen-terminated Si surface to a nearly-pure oxide in the outer region of 40--60 {Angstrom} films. Using a third generation synchrotron beam line a sensitivity of better than a tenth of a monolayer is achieved by a simple photocurrent measurement.
Date: July 19, 1994
Creator: Himpsel, F. J.; Akatsu, H. & Carlisle, J. A.
System: The UNT Digital Library
[Teen who pled homosexual assault defense certified to stand trial as adult] (open access)

[Teen who pled homosexual assault defense certified to stand trial as adult]

A document pertaining to a 16-year-old standing in trial as an adult for the murder of John Anthony Burwell.
Date: August 19, 1994
Creator: Stehle, Glenn
System: The UNT Digital Library
Modal analysis of PATHFINDER unmanned air vehicle (open access)

Modal analysis of PATHFINDER unmanned air vehicle

An experimental modal analysis was performed on PATHFINDER, a 450-lb, 100-ft wing span, flying-wing-design aircraft powered by solar/electric motors. The aircraft was softly suspended and then excited using random input from a long-stroke shaker. Modal data was taken from 92 measurement locations on the aircraft using newly designed, lightweight, tri-axial accelerometers. A conventional PC-based data acquisition system provided data handling. Modal parameters were calculated, and animated mode shapes were produced using SMS STARStruct{trademark} Modal Analysis System software. The modal parameters will be used for validation of finite element models, optimum placement of onboard accelerometers during flight testing, and vibration isolation design of sensor platforms.
Date: October 19, 1994
Creator: Woehrle, T. G.; Costerus, B. W. & Lee, C. L.
System: The UNT Digital Library
The influence of chemistry and microstructure on the fracture toughness of V-V{sub 3}Si in-situ composites (open access)

The influence of chemistry and microstructure on the fracture toughness of V-V{sub 3}Si in-situ composites

The room temperature fracture behavior is described for ductile-phase toughened V-V{sub 3}Si in-situ composites produced by arc melting (AM), cold-crucible induction melting (IM), and cold-crucible directional solidification (DS). Composites were produced containing a wide range of microstructures, interstitial impurity contents, and volume fractions of the ductile V-Si solid solution phase, denoted (V). The fracture toughness of these composites generally increases as the volume fraction of (V) increases. For a given volume fraction of (V), the fracture toughness increases with decreasing {open_quotes}effective{close_quotes} interstitial impurity content, [I]=[N]+1.3[O]+9[H]. In eutectic composites, as [I] decreases from 1400 ppm (AM) to 400 ppm (IM), the fracture toughness increases from 10 to 20 MPa {radical}m. The fracture toughness of the V-V{sub 3}Si composites is further correlated with the mechanical properties of the component phases, SEM observations of the fracture surface characteristics, and electron back-scattering pattern measurements of the fracture facet crystallography. These correlations are discussed with respect to conventional ductile phase {open_quotes}bridging{close_quotes} theories.
Date: August 19, 1994
Creator: Henshall, G. A.; Strum, M. J.; Bewlay, B. P. & Sutliff, J. A.
System: The UNT Digital Library
Accurate solution algorithms for incompressible multiphase flows (open access)

Accurate solution algorithms for incompressible multiphase flows

A number of advances in modeling multiphase incompressible flow are described. These advances include high-order Godunov projection methods, piecewise linear interface reconstruction and tracking and the continuum surface force model. Examples are given.
Date: October 19, 1994
Creator: Rider, W. J.; Kothe, D. B.; Mosso, S. J.; Cerutti, J. H. & Hochstein, J. I.
System: The UNT Digital Library
Preparation of dielectrics HR mirrors from colloidal oxide suspensions containing organic polymer binders (open access)

Preparation of dielectrics HR mirrors from colloidal oxide suspensions containing organic polymer binders

Colloidal suspensions of oxides have been used to prepare dielectric HR (high reflective) mirrors, specifically for high power fusion case applications, on substrates up to 38 cm square using a meniscus coater. These coatings consist of porous quarterwave layers of alternating high and low refractive index oxides. Silica was used as the low index oxide and AlOOH, ZrO{sub 2}, or HfO{sub 2} as the high index material. Coatings were weak because of low particle-to-particle adhesion. Use of organic polymer binders in the high index component was found to increase strength, thereby improving the laser damage threshold and also reducing the number of layers required for 99% reflection due to increased refractive index.
Date: July 19, 1994
Creator: Thomas, I. M.
System: The UNT Digital Library
Energy absorption in aluminum extrusions for a spaceframe chassis (open access)

Energy absorption in aluminum extrusions for a spaceframe chassis

This work describes the design, finite-element analysis, and verifications performed by LLNL and Kaiser Aluminum for the prototype design of the CALSTART Running Chassis purpose-built electric vehicle. Component level studies, along with our previous experimental and finite-element works, provided the confidence to study the crashworthiness of a complete aluminum spaceframe. Effects of rail geometry, size, and thickness were studied in order to achieve a controlled crush of the front end structure. These included the performance of the spaceframe itself, and the additive effects of the powertrain cradle and powertrain (motor/controller in this case) as well as suspension. Various design iterations for frontal impact at moderate and high speed are explored.
Date: September 19, 1994
Creator: Logan, R.W.; Perfect, S.A. & Parkinson, R.D.
System: The UNT Digital Library
Development of a transient three-dimensional neutron transport code with feedback (open access)

Development of a transient three-dimensional neutron transport code with feedback

A new code is being developed at the Y-12 Plant for solving the time-dependent, three-dimensional Boltzmann transport model with feedback. The new code, PADK, uses the quasi-static method in its adiabatic form and is to be utilized to analyze hypothetical criticality accidents. A description of the code along with preliminary results without feedback are presented in this paper. The code is applied to 2 standard benchmark problems and the results are compared to another method. Also, the code is used to model the GODIVA reactor. Further work needed to be completed is described.
Date: July 19, 1994
Creator: Waddell, M.W. Jr.
System: The UNT Digital Library
The National Storage Laboratory: Overview and status (open access)

The National Storage Laboratory: Overview and status

The National Storage Laboratory (NSL) was organized to investigate, demonstrate, and commercialize high-performance hardware and software storage technologies that promise to remove network computing bottlenecks and provide critically needed new storage systems functionality. This paper briefly outlines the goals, collaboration and current status of the NSL.
Date: January 19, 1994
Creator: Watson, Richard W. & Coyne, Robert
System: The UNT Digital Library