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Diffractive optical elements based on Fourier optical techniques: A new class of optics for extreme ultraviolet and soft x-ray wavelengths
None
Date:
May 5, 2002
Creator:
Chang, Chang; Naulleau, Patrick; Anderson, Erik; Rosfjord, Kristine & Attwood, David
Object Type:
Article
System:
The UNT Digital Library
Cutting fluid study for single crystal silicon
An empirical study was conducted to evaluate cutting fluids for Single Point Diamond Turning (SPDT) of single crystal silicon. The pH of distilled waster was adjusted with various additives the examine the effect of pH on cutting operations. Fluids which seemed to promote ductile cutting appeared to increase tool wear as well, an undesirable tradeoff. High Ph sodium hydroxide solutions showed promise for further research, as they yielded the best combination of reduced tool wear and good surface finish in the ductile regime. Negative rake tools were verified to improve the surface finish, but the negative rake tools used in the experiments also showed much higher wear than conventional 0{degree} rake tools. Effects of crystallographic orientation on SPDT, such as star patterns of fracture damage forming near the center of the samples, were observed to decrease with lower feedrates. Silicon chips were observed and photographed, indicative of a ductile materials removal process.
Date:
May 5, 1998
Creator:
Chargin, D.
Object Type:
Report
System:
The UNT Digital Library
Nonlinear Amplitude Evolution During Spontaneous Patterning of Ion-Bombarded Si(001)
The time evolution of the amplitude of periodic nanoscale ripple patterns formed on Ar+ sputtered Si(OOl ) surfaces was examined using a recently developed in situ spectroscopic technique. At sufficiently long times, we find that the amplitude does not continue to grow exponentially as predicted by the standard Bradley-Harper sputter rippling model. In accounting for this discrepancy, we rule out effects related to the concentration of mobile species, high surface curvature, surface energy anisotropy, and ion-surface interactions. We observe that for all wavelengths the amplitude ceases to grow when the width of the topmost terrace of the ripples is reduced to approximately 25 nm. This observation suggests that a short circuit relaxation mechanism limits amplitude . growth. A strategy for influencing the ultimate ripple amplitude is discussed.
Date:
May 5, 1999
Creator:
Chason, Eric; Erlebacher, Jonah, Aziz, Michael J.; Floro, Jerold A. & Sinclair, Michael B.
Object Type:
Article
System:
The UNT Digital Library
Observational Signatures and Non-Gaussianities ofGeneral Single Field Inflation
We perform a general study of primordial scalar non-Gaussianities in single field inflationary models. We consider models where the inflaton Lagrangian is an arbitrary function of the scalar field and its first derivative, and the sound speed is arbitrary. We find that under reasonable assumptions, the non-Gaussianity is completely determined by 5 parameters. In special limits of the parameter space, one finds distinctive ''shapes'' of the non-Gaussianity. In models with a small sound speed, several of these shapes would become potentially observable in the near future. Different limits of our formulae recover various previously known results.
Date:
May 5, 2006
Creator:
Chen, Xingang; Huang, Min-xin; Kachru, Shamit & Shiu, Gary
Object Type:
Report
System:
The UNT Digital Library
Quantum dynamics via Planck-scale-stepped action-carrying 'Graph Paths'
A divergence-free, parameter-free, path-based discrete-time quantum dynamics is designed to not only enlarge the achievements of general relativity and the standard particle model, by approximations at spacetime scales far above Planck scale while far below Hubble scale, but to allow tackling of hitherto inaccessible questions. ''Path space'' is larger than and precursor to Hilbert-space basis. The wave-function-propagating paths are action-carrying structured graphs-cubic and quartic structured vertices connected by structured ''fermionic'' or ''bosonic'' ''particle'' and ''nonparticle'' arcs. A Planck-scale path step determines the gravitational constant while controlling all graph structure. The basis of the theory's (zero-rest-mass) elementary-particle Hilbert space (which includes neither gravitons nor scalar bosons) resides in particle arcs. Nonparticle arcs within a path are responsible for energy and rest mass.
Date:
May 5, 2003
Creator:
Chew, Geoffrey F.
Object Type:
Report
System:
The UNT Digital Library
Spall Strength Measurements of Concrete for Varying Aggregate Sizes
Controlled impact experiments have been performed to determine the spall strength of four different concrete compositions. The four concrete compositions are identified as, `SAC-5, CSPC', ("3/4") large, and ("3/8") small, Aggregate. They differ primarily in aggregate size but with average densities varying by less than five percent. Wave profiles from sixteen experiments, with shock amplitudes of 0.07 to 0.55 GPa, concentrate primarily within the elastic regime. Free-surface particle velocity measurements indicate consistent pullback signals in the release profiles, denoting average span strength of approximately 40 MPa. It is the purpose of this paper to present spall measurements under uniaxial strain loading. Notwithstanding considerable wave structure that is a unique characteristic to the heterogeneous nature of the scaled concrete, the spall amplitudes appear reproducible and consistent over the pressure range reported in this study.
Date:
May 5, 1999
Creator:
Chhabildas, Lalit C.; Kipp, Marlin E.; Reinhart, William D. & Wilson, Leonard T.
Object Type:
Article
System:
The UNT Digital Library
COAMPS Application to Dispersion Scavenging Problem: Heavy Precipitation Simulation
Precipitation scavenging can effectively remove particulates from the atmosphere. Therefore, this process is of importance in the real-time modeling of atmospheric transport for hazardous materials. To account for the rainfall effect in LLNL operational dispersion model, a modified version of a standard below-cloud aerosol scavenging model has been developed to handle the emergency response in this scenario (Loosmore and Cerdewall, 2003, hereafter referred to as LC). Two types of rain data can be used to incorporate precipitation scavenging in the dispersion model; realtime measurements (rain gauge and radar), and model prediction. The former approach has been adopted in LC's study for the below-cloud scavenging problem based on the surface rain measurements. However, the in-cloud scavenging effect remains unresolved as a restriction of available real-time measurements in providing the vertical structure of precipitation systems. The objective of this study is to explore the possibility to incorporate three-dimensional precipitation structure of forecast data into the dispersion model. Therefore, both in-cloud and below-cloud scavenging effects can be included in LLNL aerosol scavenging model. To this end, a mesoscale model (Naval Research Laboratory 3-D weather forecast model, COAMPS) is used to demonstrate this application using a mid-west severe storm case occurring on July 18, …
Date:
May 5, 2004
Creator:
Chin, H. & Cederwall, R.
Object Type:
Report
System:
The UNT Digital Library
Nano Vacancy Clusters and Trap Limited Diffusion of Si Interstitials in Silicon
The objective of this project is to develop a method to characterize nano vacancy clusters and the dynamics of their formation in ion-irradiated silicon. It will impact (1) semiconductor device processing involving ion implantation, and (2) device design concerning irradiation hardness in harsh environments. It also aims to enhance minority participation in research and curricula on emerging materials and ion beam science. Vacancy defects are of scientific and technological importance since they are ubiquitous when the host materials are exposed to particle irradiation. Studies on vacancy clustering in the past decades were mainly theoretical and the approach heavily relied on the total-energy calculation methods. The lack of experimental data is mainly due to the formidable task in measuring the cluster size and density using modern metrological techniques, including transmission electron microscopy and positron annihilation spectroscopy. To surmount these challenges, we proposed a novel approach to tackle the metrological problems on the nano vacancy clusters, especially in determining densities and sizes of the nano vacancies based on the premise that the vacancy-clusters act as diffusion-trapping centers. For a silicon substrate containing vacancyclusters, the diffusion of interstitials (from the surface) can be classified into three phases: (1) an ultrafast phase-I in which …
Date:
May 5, 2010
Creator:
Chu, Prof. Wei-Kan
Object Type:
Report
System:
The UNT Digital Library
Solid Waste Information Tracking System (SWITS), Backlog Waste Modifications, Software Requirements Specification (SRS)
Purpose of this document is to define the system requirements necessary to improve computer support for the WHC backlog waste business process through enhancements to the backlog waste function of the SWITS system. This SRS document covers enhancements to the SWITS system to support changes to the existing Backlog Waste screens including new data elements, label changes, and new pop-up screens. The pop-ups will allow the user to flag the processes that a waste container must have performed on it, and will provide history tracking of changes to data. A new screen will also be provided allowing Acceptable Services to perform mass updates to specific data in Backlog Waste table. The SWITS Backlog Waste enhancements in this document will support the project goals in WHC-SD-WM-003 and its Revision 1 (Radioactive Solid Waste Tracking System Conceptual Definition) for the control, tracing, and inventory management of waste as the packages are generated and moved through final disposal (cradle-to-grave).
Date:
May 5, 1995
Creator:
Clark, R. E.
Object Type:
Report
System:
The UNT Digital Library
Data from Tests of a 1/5-Scale Model of a Proposed High-Speed Submarine in the Langley Full-Scale Tunnel
Tests of a 1/5 scale model of a proposed 153-foot high-speed submarine have been conducted in the Langley full-scale tunnel at the request of the Bureau of Ships, Department of the Navy. The test program included: (1) force tests to determine the drag, control effectiveness, and static stability characteristics for a number of model configurations, both in pitch and in yaw, (2) pressure measurements to determine the boundary-layer conditions and flow characteristics in the region of the propeller, and (3) an investigation of the effects of propeller operation on the model aerodynamic characteristics. In response to oral requests from the Bureau of Ships representatives t hat the basic data obtained in these tests be made available to them as rapidly as possible, this data report has been prepared to present some of the more pertinent results. All test results given in the present paper are for the propeller-removed condition and were obtained at a Reynolds number of approximately 22,300,000 based on model length.
Date:
May 5, 1950
Creator:
Cocke, Bennie W.; Lipson, Stanley & Scallion, William I.
Object Type:
Report
System:
The UNT Digital Library
Identification of potential transuranic waste tanks at the Hanford Site
The purpose of this document is to identify potential transuranic (TRU) material among the Hanford Site tank wastes for possible disposal at the Waste Isolation Pilot Plant (WIPP) as an alternative to disposal in the high-level waste (HLW) repository. Identification of such material is the initial task in a trade study suggested in WHC-EP-0786, Tank Waste Remediation System Decisions and Risk Assessment (Johnson 1994). The scope of this document is limited to the identification of those tanks that might be segregated from the HLW for disposal as TRU, and the bases for that selection. It is assumed that the tank waste will be washed to remove soluble inert material for disposal as low-level waste (LLW), and the washed residual solids will be vitrified for disposal. The actual recommendation of a disposal strategy for these materials will require a detailed cost/benefit analysis and is beyond the scope of this document.
Date:
May 5, 1995
Creator:
Colburn, R. P.
Object Type:
Report
System:
The UNT Digital Library
Measuring and Proportioning Machine.
Patent for "a device by which the mixing of various ingredients in certain desired proportions may be easily and accurately accomplished" (lines 8-11). It is meant for industrial measuring.
Date:
May 5, 1896
Creator:
Collins, Alonzo G.
Object Type:
Patent
System:
The Portal to Texas History
A Collection of Recent Articles on Portuguese Africa
This report provides a collection of recent articles on Portuguese Africa.
Date:
May 5, 1971
Creator:
Colwell, Carolyn K.
Object Type:
Report
System:
The UNT Digital Library
Review of Offshore Energy Leasing: President Trump's Executive Order
This report discusses President Trump's executive order (E.O.) on U.S. offshore energy strategy including a brief overview of previous policies and the scope of the E.O.
Date:
May 5, 2017
Creator:
Comay, Laura B.
Object Type:
Report
System:
The UNT Digital Library
Overseas Basing Commission
The Commission on Review of Overseas Military Facility Structure of the United States is charged with implementing Public Law 108-132 Sec. 128 by conducting a thorough study of matters relating to the overseas military facility structure of the United States. See also the Commission's Amended Charter and the Original Charter.
Date:
May 5, 2004
Creator:
Commission on Review of Overseas Military Facility Structure of the United States
Object Type:
Website
System:
The UNT Digital Library
Solid-state modulators for RF and fast kickders
As the switching capabilities of solid-state devices increase, these devices are being incorporated into modulator designs for high voltage accelerator applications. Solid-state modulators based on inductive adder circuit topology have demonstrated great versatility with regard to pulse width and pulse repetition rate while maintaining fast pulse rise and fall times. Additionally, these modulators are capable of being scaled to higher output voltage and power levels. An explanation of the basic circuit operation will be presented as well as test data of several different hardware systems.
Date:
May 5, 2005
Creator:
Cook, E. G.; Akana, G.; Gower, E. J.; Hawkins, S. A.; Hickman, B. C.; Brooksby, C. A. et al.
Object Type:
Article
System:
The UNT Digital Library
Effect of Interaction on Landing-Gear Behavior and Dynamic Loads in a Flexible Airplane Structure
"The effects of interaction between a landing gear and a flexible airplane structure on the behavior of the landing gear and the loads in the structure have been studied by treating the equations of motion of the airplane and the landing gear as a coupled system. The landing gear is considered to have nonlinear characteristics typical of conventional gears, namely, velocity-squared damping, polytropic air-compression springing, and exponential tire force-deflection characteristics. For the case where only two modes of the structure are considered, an equivalent three-mass system is derived for representing the airplane and landing-gear combination, which may be used to simulate the effects of structural flexibility in jig drop tests of landing gears" (p. 619).
Date:
May 5, 1955
Creator:
Cook, Francis E. & Milwitzky, Benjamin
Object Type:
Report
System:
The UNT Digital Library
AIDS in Africa
Sub-Saharan Africa has been far more severely affected by AIDS than any other part of the world. The United Nations reports that 25.8 million adults and children are infected with the HIV virus in the region, which has about 11.3% of the world's population but more than 64% of the worldwide total of infected people. This report discusses this issue in detail, including the cause of the African AIDS epidemic, the social and economic consequences, response and treatment, and U.S. policy.
Date:
May 5, 2006
Creator:
Cook, Nicolas
Object Type:
Report
System:
The UNT Digital Library
Liberia's Post-War Recovery: Key Issues and Developments
This report describes recent developments in Liberia, a small, poor West African country that is undergoing a post-conflict transition and peace-building process after its second civil war in a decade.
Date:
May 5, 2006
Creator:
Cook, Nicolas
Object Type:
Report
System:
The UNT Digital Library
Balance-Staff for Watches.
Patent for improvements in balance-staffs for watches by “strengthen and increase the durability of the pivots or journals of the staff while reducing the friction to a minimum” (lines 16-19), included illustration.
Date:
May 5, 1891
Creator:
Cooper, Jonathan H.
Object Type:
Patent
System:
The Portal to Texas History
Beta-cell Assembly for the Quad Gas Sampling Detector
The beta-cells used in the beta-gamma detector have taken time to develop and to standardize the assembly of them. In making the assembly routine it is important to have step by step assembly instructions as well as a list of potential problems and their solutions. This document attempts to accomplish these goals.
Date:
May 5, 2008
Creator:
Cooper, Matthew W.; Bowyer, Ted W.; McIntyre, Justin I.; Hayes, James C.; Heimbigner, Tom R.; Ripplinger, Michael D. et al.
Object Type:
Report
System:
The UNT Digital Library
War Infrastructure Needs and Investment: Review and Analysis of Key Issues
None
Date:
May 5, 2005
Creator:
Copeland, Claudia & Tiemann, Mary
Object Type:
Report
System:
The UNT Digital Library
War Infrastructure Needs and Investment: Review and Analysis of Key Issues
None
Date:
May 5, 2005
Creator:
Copeland, Claudia & Tiemann, Mary
Object Type:
Report
System:
The UNT Digital Library
Ambipolar potential formation in TMX
TMX experimental data on ambipolar potential control and on the accompanying electrostatic confinement are reported. New results on the radial dependence of the central-cell confining potential are given. Radial and axial particle losses as well as scaling of the central-cell axial confinement are discussed.
Date:
May 5, 1981
Creator:
Correl, D. L.; Allen, S. L. & Casper, T. A.
Object Type:
Report
System:
The UNT Digital Library