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Diffuse reflectance FTIR of stains on grit blasted metals (open access)

Diffuse reflectance FTIR of stains on grit blasted metals

Diffuse reflectance mid-infrared Fourier transform (DRIFT) spectroscopy has been applied to the detection of oil contamination on grit-blasted metals. The object of this application is to detect and discriminate between silicone and hydrocarbon oil contamination at levels approaching 10 mg/m{sup 2}. A portable FTIR spectrometer with dedicated diffuse reflectance optics was developed for this purpose. Using translation devices positioned by instructions from the spectrometer operating system, images of macroscopic substrates were produced with millimeter spatial resolution. The pixels that comprise an image are each a full mid-infrared spectrum with excellent signal-to-noise, each determined as individual files and uniquely saved to disc. Reduced spectra amplitudes, based on peak height, area, or other chemometric techniques, mapped as a function of the spatial coordinates of the pixel are used to display the image. This paper demonstrates the application of the technique to the analysis of stains on grit-blasted metals, including the calibration of the method, the inspection of substrates, and the migration of oil contamination.
Date: August 9, 1997
Creator: Powell, G. L.; Hallman Jr., R. L. & Cox, R. L.
System: The UNT Digital Library
EUV optical design for 100 nm CD imaging system (open access)

EUV optical design for 100 nm CD imaging system

The imaging specifications for extreme ultraviolet lithography (EUVL) projection optics parallel those of other optical lithographies. Specifications are scaled to reflect the 100 nm critical dimension for the first generation EUVL systems. The design being fabricated for the Engineering Test Stand, an EUVL alpha tool, consists of a condenser with six channels to provide an effective partial coherence factor of 0.7. The camera contains four mirrors; three of the mirrors are aspheres and the fourth is spherical. The design of the optical package has been constrained so that the angles of incidence and the variations in the angle of incidence of all rays allow for uniform multilayer coatings. The multilayers introduce a slight shift in image position and magnification. We have shown that a system aligned with visible light is also aligned at 13.4 nm. Each mirror must be fabricated with an RMS figure error of less than 0.25 nm and better than 0.2 nm RMS roughness. Optical surfaces that exceed each of these specifications individually have been fabricated. The success of EUVL requires that these specifications be met simultaneously.
Date: April 9, 1998
Creator: Sweeney, D.W.; Hudyma, R.; Chapman, H.B. & Shafer, D.
System: The UNT Digital Library
Advancing Design-for-Assembly: The Next Generation in Assembly Planning (open access)

Advancing Design-for-Assembly: The Next Generation in Assembly Planning

At the 1995 IEEE Symposium on Assembly and Task Planning, Sandia National Laboratories introduced the Archimedes 2 Software Tool [2]. The system was described as a second-generation assembly planning system that allowed preliminmy application of awembly planning for industry, while solidly supporting further research in planning techniques. Sandia has worked closely with indust~ and academia over the last four years. The results of these working relationships have bridged a gap for the next generation in assembly planning. Zke goal of this paper is to share Sandia 's technological advancements in assembly planning over the last four years and the impact these advancements have made on the manufacturing communip.
Date: December 9, 1998
Creator: Calton, T.L.
System: The UNT Digital Library
Group-III Nitride Etch Selectivity in BCl(3)/Cl(2) ICP Plasmas (open access)

Group-III Nitride Etch Selectivity in BCl(3)/Cl(2) ICP Plasmas

Patterning the group-IH nitrides has been challenging due to their strong bond energies and relatively inert chemical nature as compared to other compound semiconductors. Plasma etch processes have been used almost exclusively to pattern these films. The use of high-density plasma etch systems, including inductively coupled plasmas (ICP), has resulted in relatively high etch rates (often greater than 1.0 pmhnin) with anisotropic profiles and smooth etch morphologies. However, the etch mechanism is often dominated by high ion bombardment energies which can minimize etch selectivity. The use of an ICP-generated BCl~/C12 pkyma has yielded a highly versatile GaN etch process with rates ranging from 100 to 8000 A/rnin making this plasma chemistry a prime candidate for optimization of etch selectivity. In this study, we will report ICP etch rates and selectivities for GaN, AIN, and InN as a function of BCl~/Clz flow ratios, cathode rf-power, and ICP-source power. GaN:InN and GaN:AIN etch selectivities were typically less than 7:1 and showed the strongest dependence on flow ratio. This trend maybe attributed to faster GaN etch rates observed at higher concentrations of atomic Cl which was monitored using optical emission spectroscopy (OES). ~E~~~~f:~ INTRODUCTION DEC j 4898 Etch selectivi
Date: December 9, 1998
Creator: Abernathy, C.R.; Han, J.; Hong, J.; Lester, L.F.; Pearton, S.J.; Shul, R.J. et al.
System: The UNT Digital Library
A Framework for Automating Cost Estimates in Assembly Processes (open access)

A Framework for Automating Cost Estimates in Assembly Processes

When a product concept emerges, the manufacturing engineer is asked to sketch out a production strategy and estimate its cost. The engineer is given an initial product design, along with a schedule of expected production volumes. The engineer then determines the best approach to manufacturing the product, comparing a variey of alternative production strategies. The engineer must consider capital cost, operating cost, lead-time, and other issues in an attempt to maximize pro$ts. After making these basic choices and sketching the design of overall production, the engineer produces estimates of the required capital, operating costs, and production capacity. 177is process may iterate as the product design is refined in order to improve its pe~ormance or manufacturability. The focus of this paper is on the development of computer tools to aid manufacturing engineers in their decision-making processes. This computer sof~are tool provides aj?amework in which accurate cost estimates can be seamlessly derivedfiom design requirements at the start of any engineering project. Z+e result is faster cycle times through first-pass success; lower ll~e cycie cost due to requirements-driven design and accurate cost estimates derived early in the process.
Date: December 9, 1998
Creator: Calton, T. L. & Peters, R. R.
System: The UNT Digital Library
A Gas-Cooled Reactor Surface Power System (open access)

A Gas-Cooled Reactor Surface Power System

A human outpost on Mars requires plentiful power to assure survival of the astronauts. Anywhere from 50 to 500 kW of electric power (kWe) will be needed, depending on the number of astronauts, level of scientific activity, and life- cycle closure desired. This paper describes a 250-kWe power system based on a gas-cooled nuclear reactor with a recuperated closed Brayton cycle conversion system. The design draws upon the extensive data and engineering experience developed under the various high-temperature gas cooled reactor programs and under the SP-100 program. The reactor core is similar in power and size to the research reactors found on numerous university campuses. The fuel is uranium nitide clad in Nb 1 %Zr, which has been extensively tested under the SP-I 00 program The fiel rods are arranged in a hexagonal array within a BeO block. The BeO softens the spectrum, allowing better use of the fbel and stabilizing the geometty against deformation during impact or other loadings. The system has a negative temperature feedback coefficient so that the power level will automatically follow a variable load without the need for continuous adjustment of control elements. Waste heat is removed by an air-cooled heat exchanger using cold Martian …
Date: November 9, 1998
Creator: Harms, G.A.; Lenard, R.X.; Lipinski, R.J. & Wright, S.A.
System: The UNT Digital Library
Safety and environmental advantages of using tritium-lean targets for inertial fusion (open access)

Safety and environmental advantages of using tritium-lean targets for inertial fusion

While traditional inertial fusion energy target designs typically use equimolar portions of deuterium and tritium and have areal densities ({rho}r) of {approx} 3 g/cm{sup 2}, significant safety and environmental (S and E) advantages may be obtained through the use of high-density ({rho}r {approx} 10 g/cm{sup 2}) targets with tritium components as low as 0.5%. Such targets would absorb much of the neutron energy within the target and could be self-sufficient from a tritium breeding point of view. Tritium self-sufficiency within the target would free target chamber designers from the need to use lithium-bearing blanket materials, while low inventories within each target would translate into low inventories in target fabrication facilities. Absorption of much of the neutron energy within the target, the extremely low tritium inventories, and the greatly moderated neutron spectrum, make ''tritium-lean'' targets appear quite attractive from an S and E perspective.
Date: August 9, 1999
Creator: Arzeni, S.; Latkowski, J. F.; Logan, B. G.; Meier, W. R.; Moir, R. W.; Perkins, L. J. et al.
System: The UNT Digital Library

An Ecological Perspective on Rural, Low-Income Mothers' Health

Article on an ecological perspective on rural, low-income mothers' health.
Date: December 9, 2014
Creator: Bice-Wigington, Tiffany; Simmons, Leigh Ann & Huddleston-Casas, Catherine A.
System: The UNT Digital Library
Optical Spectroscopy Measurements of Shock Waves Driven by Intense Z-Pinch Radiation (open access)

Optical Spectroscopy Measurements of Shock Waves Driven by Intense Z-Pinch Radiation

Z-pinches created using the Z accelerator generate {approximately}220 TW, 1.7 MJ radiation pulses that heat large ({approximately}10 cm{sup 3}) hohlraums to 100-150 eV temperatures for times of order 10 nsec. We are performing experiments exploiting this intense radiation to drive shock waves for equation of state studies. The shock pressures are typically 1-10 Mbar with 10 nsec duration in 6-mm-diameter samples. In this paper we demonstrate the ability to perform optical spectroscopy measurements on shocked samples located in close proximity to the z-pinch. These experiments are particularly well suited to optical spectroscopy measurements because of the relatively large sample size and long duration. The optical emission is collected using fiber optics and recorded with a streaked spectrograph. Other diagnostics include VISAR and active shock breakout measurements of the shocked sample and a suite of diagnostics that characterize the radiation drive. Our near term goal is to use the spectral emission to obtain the temperature of the shocked material. Longer term objectives include the examination of deviations of the spectrum from blackbody, line emission from lower density regions, determination of kinetic processes in molecular systems, evaluation of phase transitions such as the onset of metalization in transparent materials, and characterization of …
Date: April 9, 1999
Creator: Asay, J.; Bailey, J. E.; Carlson, A. L.; Chandler, G. A.; Hall, C. A.; Hanson, D. et al.
System: The UNT Digital Library
Analysis and validation of laser spot weld-induced distortion (open access)

Analysis and validation of laser spot weld-induced distortion

Laser spot welding is an ideal process for joining small parts with tight tolerances on weld size, location, and distortion, particularly those with near-by heat sensitive features. It is also key to understanding the overlapping laser spot seam welding process. Rather than attempting to simulate the laser beam-to-part coupling (particularly if a keyhole occurs), it was measured by calorimetry. This data was then used to calculate the thermal and structural response of a laser spot welded SS304 disk using the finite element method. Five combinations of process parameter values were studied. Calculations were compared to experimental data for temperature and distortion profiles measured by thermocouples and surface profiling. Results are discussed in terms of experimental and modeling factors. The authors then suggest appropriate parameters for laser spot welding.
Date: December 9, 1999
Creator: Knorovsky, G. A.; Kanouff, M. P.; Maccallum, D. O. & Fuerschbach, P. W.
System: The UNT Digital Library
18th IAEA Fusion Energy Conference Summary of Technology and Power Plans (open access)

18th IAEA Fusion Energy Conference Summary of Technology and Power Plans

There were 90 papers presented at the Conference in the category of Technology and Power Plants accounting for about 25% of the total number of contributions. As was the case at the previous meeting, a large number of papers dealt with the ITER-Engineering Design Activity (EDA) and ITER technology R&D. In the author's opinion, the rapid progress made during the ITER EDA extension on the completion of the new ITER-FEAT design and its physics and technology R&D validation stands out as the highlight of the meeting. Steady progress is being made on several other technology fronts as well. The results point towards emerging research trends in the following areas: steady-state operation with advanced performance and the increasingly important role of enabling technologies in achieving this goal, advanced, high-performance, environmentally attractive materials for the fusion energy goal, reactor and near-term applications studies that exploit advances both in the physics and technology fronts for lower cost of electricity and improved safety and environmental features, and socioeconomic studies that are helping to promote the attractive features of fusion and its public acceptance. The remaining sections of this paper are organized along the lines of these major themes; namely, ITER EDA Design, ITER Technology …
Date: March 9, 2001
Creator: Milora, S. L.
System: The UNT Digital Library
Recent KTeV Results (open access)

Recent KTeV Results

Preliminary KTEV results are presented based on the 1997 data set, and include an improved measurement of R({epsilon}{prime}/{epsilon}), CPT tests, and precise measurements of {tau}{sub S} and {Delta}{sub m}.
Date: November 9, 2001
Creator: Kessler, Richard
System: The UNT Digital Library
Modeling Thermal Desaturation of Fracture Porous Rocks (open access)

Modeling Thermal Desaturation of Fracture Porous Rocks

None
Date: November 9, 2000
Creator: REED,ALFRED W.
System: The UNT Digital Library
Carbon and hydrogen isotope signatures associated with microbial iron reduction (open access)

Carbon and hydrogen isotope signatures associated with microbial iron reduction

None
Date: January 9, 2001
Creator: Horita, J.
System: The UNT Digital Library
Evaluation of Creep Property of AS800 Silicon Nitride from As-Processed Surface Regions (open access)

Evaluation of Creep Property of AS800 Silicon Nitride from As-Processed Surface Regions

Tensile creep studies were carried out to evaluate the creep performance of AS800 silicon nitride samples extracted from the surface and bulk regions of as-processed billets at 1350 C in air. The objective of this study was to understand the creep properties of the silicon nitride in the as-processed surface region and determine if they are comparable to those obtained from the bulk region. The results indicated that samples from the as-processed surface region exhibited higher creep rates and shorter lifetimes as compared with those obtained from the bulk region. The poor creep performance of material from the as-processed surface region was due to the higher content of glassy phase enriched with oxygen and sintering additive elements.
Date: March 9, 2001
Creator: Lin, H. T.
System: The UNT Digital Library
An Evaluation of Parallel Job Scheduling for ASCI Blue-Pacific (open access)

An Evaluation of Parallel Job Scheduling for ASCI Blue-Pacific

In this paper we analyze the behavior of a gang-scheduling strategy that we are developing for the ASCI Blue-Pacific machines. Using actual job logs for one of the ASCI machines we generate a statistical model of the current workload with hyper Erlang distributions. We then vary the parameters of those distributions to generate various workloads, representative of different operating points of the machine. Through simulation we obtain performance parameters for three different scheduling strategies: (i) first-come first-serve, (ii) gang-scheduling, and (iii) backfilling. Our results show that backfilling, can be very effective for the common operating points in the 60-70% utilization range. However, for higher utilization rates, time-sharing techniques such as gang-scheduling offer much better performance.
Date: November 9, 1999
Creator: Franke, H.; Jann, J.; Moreira, J.; Pattnaik, P. & Jette, M.
System: The UNT Digital Library
Design and measurements of a deflecting mode cavity for an RF separator (open access)

Design and measurements of a deflecting mode cavity for an RF separator

The Fermilab Main Injector can produce intense 120 GeV/c proton beams for fixed target experimentation. Two deflecting mode RF systems can be used to separate charged kaons from a momentum selected secondary beam, consisting of pions, kaons and protons, using a time of flight method. We present the RF design of a 3.9 GHz superconducting cavity which operates in the deflecting (TM110) pi-mode and the dependence of the RF parameters on the cavity shape, as determined with finite difference calculations. End cell compensation has been treated, providing cell-to-cell field flatness. First results from measurements on a prototype cavity are shown. We demonstrated that it is possible to tune the deflecting mode of a cell cavity with bead pull measurements. Effects relating the polarization of the modes are discussed.
Date: July 9, 2001
Creator: Bellantoni, Leo
System: The UNT Digital Library
Monolithic GaAs surface acoustic wave chemical microsensor array (open access)

Monolithic GaAs surface acoustic wave chemical microsensor array

A four-channel surface acoustic wave (SAW) chemical sensor array with associated RF electronics is monolithically integrated onto one GaAs IC. The sensor operates at 690 MHz from an on-chip SAW based oscillator and provides simple DC voltage outputs by using integrated phase detectors. This sensor array represents a significant advance in microsensor technology offering miniaturization, increased chemical selectivity, simplified system assembly, improved sensitivity, and inherent temperature compensation.
Date: March 9, 2000
Creator: Hietala, Vincent M.; Casalnuovo, Stephen A.; Heller, Edwin J.; Wendt, Joel R.; Frye-Mason, Gregory Charles & Baca, Albert G.
System: The UNT Digital Library
Characterization of Thermally Degraded Energetic Materials: Experiments and Constitutive Modeling (open access)

Characterization of Thermally Degraded Energetic Materials: Experiments and Constitutive Modeling

None
Date: December 9, 1999
Creator: RENLUND,ANITA M.; SCHMITT,ROBERT G.; WELLMAN,GERALD W. & MILLER,JILL C.
System: The UNT Digital Library
Security preparation for receipt of SNF from the FRR to the INEEL (open access)

Security preparation for receipt of SNF from the FRR to the INEEL

This paper reports the key security related activities associated with the FRR shipment. Starting with transportation of the SNF in the country of origin to the final destination at the INEEL. Methodology for compliance will be addressed. The graded approach and a three step system will be explained. This paper will be used as part of the planning to support the FRR Project for returning the Asia and European SNF back to the US.
Date: October 9, 1997
Creator: Dahlquist, R.L.
System: The UNT Digital Library
Viscoelastic properties of healthy human artery measured in saline solution by AFM based indentation technique (open access)

Viscoelastic properties of healthy human artery measured in saline solution by AFM based indentation technique

Using an Atomic Force Microscope with an attachment for indentation, we have measured local, in vitro mechanical properties of healthy femoral artery tissue held in saline solution. The elastic modulus (34. 3 kPa) and viscoelastic response ({tau}sub{epsilon} {equals} 16.9 s and {tau}sub{sigma} {equals} 29.3 s) of the unstretched,intimal vessel wall have been determined using Sneddon theory and a three element model(standard linear solid) for viscoelastic materials. The procedures necessary to employ the indenting attachment to detect elastic moduli in the kPa range in liquid are described.
Date: February 9, 1998
Creator: Lundkvist, A.; Lilleodden, E.; Sickhaus, W.; Kinney, J.; Pruitt, L. & Balooch, M.
System: The UNT Digital Library
Raman lidar profiling of water vapor and aerosols over the ARM SGP Site (open access)

Raman lidar profiling of water vapor and aerosols over the ARM SGP Site

The authors have developed and implemented automated algorithms to retrieve profiles of water vapor mixing ratio, aerosol backscattering, and aerosol extinction from Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) Raman Lidar data acquired during both daytime and nighttime operations. The Raman lidar sytem is unique in that it is turnkey, automated system designed for unattended, around-the-clock profiling of water vapor and aerosols. These Raman lidar profiles are important for determining the clear-sky radiative flux, as well as for validating the retrieval algorithms associated with satellite sensors. Accurate, high spatial and temporal resolution profiles of water vapor are also required for assimilation into mesoscale models to improve weather forecasts. The authors have also developed and implemented routines to simultaneously retrieve profiles of relative humidity. These routines utilize the water vapor mixing ratio profiles derived from the Raman lidar measurements together with temperature profiles derived from a physical retrieval algorithm that uses data from a collocated Atmospheric Emitted Radiance Interferometer (AERI) and the Geostationary Operational Environmental Satellite (GOES). These aerosol and water vapor profiles (Raman lidar) and temperature profiles (AERI+GOES) have been combined into a single product that takes advantage of both active and passive remote sensors to characterize the …
Date: January 9, 2000
Creator: Ferrare, R.A.
System: The UNT Digital Library
The solvated electron in supercritical water (open access)

The solvated electron in supercritical water

In order to investigate the feasibility for high-efficiency supercritical-water-cooled nuclear reactors, a study of radiation chemistry in supercritical water has been undertaken. Preliminary results in measurement of the optical absorption of the hydrated electron are reported, and compared with recent anion cluster data.
Date: March 9, 2000
Creator: Bartels, D. M.; Takahashi, K.; Cline, J. & Jonah, C. D.
System: The UNT Digital Library
An object-oriented framework for dynamic ecosystem modeling : application for integrated risk assessment. (open access)

An object-oriented framework for dynamic ecosystem modeling : application for integrated risk assessment.

None
Date: June 9, 2000
Creator: Sydelko, P. J.; Hlohowskyj, I.; Majerus, K.; Christiansen, J. & Dolph, J.
System: The UNT Digital Library