States

Parallel-Plate Electrostatic Dual Mass Oscillator (open access)

Parallel-Plate Electrostatic Dual Mass Oscillator

A surface-micromachined two-degree-of-freedom system that was driven by parallel-plate actuation at antiresonance was demonstrated. The system consisted of an absorbing mass connected by folded springs to a drive mass. The system demonstrated substantial motion amplification at antiresonance. The absorber mass amplitudes were 0.8-0.85 pm at atmospheric pressure while the drive mass amplitudes were below 0.1 pm. Larger absorber mass amplitudes were not possible because of spring softening in the drive mass springs. Simple theory of the dual-mass oscillator has indicated that the absorber mass may be insensitive to limited variations in strain and damping. This needs experimental verification. Resonant and antiresonant frequencies were measured and compared to the designed values. Resonant frequency measurements were difficult to compare to the design calculations because of time-varying spring softening terms that were caused by the drive configuration. Antiresonant frequency measurements were close to the design value of 5.1 kHz. The antiresonant frequency was not dependent on spring softening. The measured absorber mass displacement at antiresonance was compared to computer simulated results. The measured value was significantly greater, possibly due to neglecting fringe fields in the force expression used in the simulation.
Date: July 22, 1999
Creator: Allen, James J.; Dyck, Christopher W. & Huber, Robert J.
Object Type: Article
System: The UNT Digital Library
Radiation monitoring for vertex detectors at the Tevatron (open access)

Radiation monitoring for vertex detectors at the Tevatron

I present an overview of radiation monitoring for vertex detectors and the abort system for the Fermilab Tevatron. Details on the detectors, inputs, and measurements for the Run 1 time period are provided. Plans for the monitoring during Run 2 are discussed. The measurements imply an approximately even mix of radiation from beam-beam collisions and beam losses.
Date: July 22, 1999
Creator: Derwent, P.F.
Object Type: Article
System: The UNT Digital Library
Solid Freeform Fabrication Using the Wirefeed Process (open access)

Solid Freeform Fabrication Using the Wirefeed Process

Direct metal deposition technologies produce complex, near net shape components from CAD solid models. Most of these techniques fabricate a component by melting powder in a laser weld pool, rastering this weld bead to form a layer, and additively constructing subsequent layers. This talk describes a new direct metal deposition process, known as WireFeed, whereby a small diameter wire is used instead of powder as the feed material to fabricate components. Currently, parts are being fabricated from stainless steel. Microscopy studies show the WireFeed parts to be fully dense with fine microstructural features. Initial mechanical tests show stainless steel parts to have good strength values with retained ductility.
Date: July 22, 1999
Creator: Buchheit, T. E.; Crenshaw, T. B.; Ensz, M. T.; Greene, D. L.; Griffith, M. L.; Harwell, L. D. et al.
Object Type: Article
System: The UNT Digital Library
Design of Experiments to Estimate Temperature Dependent Thermal Properties (open access)

Design of Experiments to Estimate Temperature Dependent Thermal Properties

Experimental conditions are studied to optimize transient experiments for estimating temperature dependent thermal conductivity and volumetric heat capacity. Thermal properties are assumed to vary linearly with temperature; a total of four parameters describe linearly varying thermal conductivity and volumetric heat capacity. A numerical model of experimental configurations is studied to determine the optimum conditions to conduct the experiment. The criterion D-optimality is used to study the sensor locations, heating duration and magnitude, and experiment duration for finite and semi-infinite configurations. Results indicate that D-optimality is an order of magnitude larger for the finite configuration and hence will provide estimates with a smaller confidence region.
Date: July 22, 1999
Creator: Blackwell, B. F. & Dowding, K. J.
Object Type: Article
System: The UNT Digital Library
Design analysis of 2,000 lb JIB crane for chemical lab (open access)

Design analysis of 2,000 lb JIB crane for chemical lab

A 2,000 lbf jib crane is needed to replace an existing 1,000 lbf jib crane in the Chemical Lab (Building MO-733). The existing 1,000 lbf jib crane (to be replaced) has a 174 boom (I-beam). The crane is attached to the wall through two brackets (about 8 1/2-ft apart). The boom is attached to the lower bracket, and a supporting rod is attached to the upper bracket. The supporting rod is attached to the boom at about 8-ft from the free end. After preliminary studies and discussions, it was decided to construct the new jib crane from two perpendicular I-beams (L-shape) without a supporting rod. The crane is to be supported on the wall through the two lower existing brackets (about 5-ft apart). The boom is to be 20-ft long cantilever (the horizontal I-beam). The vertical I-beam is to be attached to the lower two existing brackets to support the jib crane to the wall. This construction is to be similar to another existing 1,000 lbf jib crane (L-shape) in the lab. The purpose of this document is to perform a design analysis for the proposed 2,000 lbf jib crane to determine suitable sizes of members and configuration of the …
Date: September 22, 1999
Creator: Ziada, H. H.
Object Type: Report
System: The UNT Digital Library
Assessment of historical leak model methodology as applied to the REDOX high-level waste tank SX-108 (open access)

Assessment of historical leak model methodology as applied to the REDOX high-level waste tank SX-108

Using the Historical Leak Model approach, the estimated leak rate (and therefore, projected leak volume) for Tank 241-SX-108 could not be reproduced using the data included in the initial document describing the leak methodology. An analysis of parameters impacting tank heat load calculations strongly suggest that the historical tank operating data lack the precision and accuracy required to estimate tank leak volumes using the Historical Leak Model methodology.
Date: September 22, 1999
Creator: Jones, T. E.
Object Type: Report
System: The UNT Digital Library
Whitey SCHE Gauge and Root Valves (open access)

Whitey SCHE Gauge and Root Valves

Whiley SCHe Gauge/Root Valves
Date: July 22, 1999
Creator: Van Katwijk, Carl
Object Type: Report
System: The UNT Digital Library
DEVELOPMENT OF PRECIPITATED IRON FISCHER-TROPSCH CATALYSTS (open access)

DEVELOPMENT OF PRECIPITATED IRON FISCHER-TROPSCH CATALYSTS

Despite the current worldwide oil glut, the US will ultimately require large-scale production of liquid (transportation) fuels from coal. Slurry phase Fischer-Tropsch (F-T) technology, with its versatile product slate, may be expected to play a major role in production of transportation fuels via indirect coal liquefaction. Some of the F-T catalysts synthesized and tested at Texas A and M University under DOE Contract No. DE-AC22-89PC89868 were more active than any other known catalysts developed for maximizing production of high molecular weight hydrocarbons (waxes). The objectives of the present contract were to demonstrate repeatability of catalyst performance and reproducibility of preparation procedures of two of these catalysts on a laboratory scale. Improvements in the catalyst performance were attempted through the use of: (a) higher reaction pressure and gas space velocity to maximize the reactor productivity; (b) modifications in catalyst preparation steps; and (c) different pretreatment procedures. Repeatability of catalyst performance and reproducibility of catalyst synthesis procedure have been successfully demonstrated in stirred tank slurry reactor tests. Reactor space-time-yield was increased up to 48% by increasing reaction pressure from 1.48 MPa to 2.17 MPa, while maintaining the gas contact time and synthesis gas conversion at a constant value. Use of calcination temperatures …
Date: July 22, 1999
Creator: Bukur, Dragomir B.; Lang, X.; Chokkaram, S.; Nowicki, L.; Wei, G.; Ding, Y. et al.
Object Type: Report
System: The UNT Digital Library
Interim Stabilization Equipment Essential and Support Drawing Plan (open access)

Interim Stabilization Equipment Essential and Support Drawing Plan

The purpose of this document is to list the Interim Stabilization equipment drawings that are classified as Essential or Support drawings. Essential Drawings: Those drawings identified by the facility staff as necessary to directly support the safe operation of the facility or equipment. Support Drawings: Those drawings identified by the facility staff that further describe the design details of structures, systems or components shown on essential drawings.
Date: October 22, 1999
Creator: Koch, M. R.
Object Type: Report
System: The UNT Digital Library
Texas Register, Volume 24, Number 43, Pages 9113-9436, October 22, 1999 (open access)

Texas Register, Volume 24, Number 43, Pages 9113-9436, October 22, 1999

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.
Date: October 22, 1999
Creator: Texas. Secretary of State.
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History
U.S. Agriculture: Grain Fungus Creates Financial Distress for North Dakota Barley Producers (open access)

U.S. Agriculture: Grain Fungus Creates Financial Distress for North Dakota Barley Producers

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO reviewed the effect of scab and vomitoxin on North Dakota barley crops, focusing on: (1) the financial impact from scab and vomitoxin on barley farmers; (2) the performance of vomitoxin test methods; and (3) short- and long-term actions that could help reduce the impact of scab and vomitoxin on North Dakota barley farmers."
Date: March 22, 1999
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Supplemental Security Income: Incentive Payments Have Reduced Benefit Overpayments to Prisoners (open access)

Supplemental Security Income: Incentive Payments Have Reduced Benefit Overpayments to Prisoners

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO provided information on the impact incentive payment legislation for correctional facilities had on the Social Security Administration's (SSA) Supplemental Security Income (SSI) program, focusing on: (1) how many correctional facilities signed incentive payment agreements, how many benefit suspensions did SSA make, and what amount of overpayments did SSA identify and prevent at these facilities; (2) how many of the incentive payment agreements represented new reporting commitments that SSA did not have before the authorization of incentive payments, and what were the results at facilities that made these new commitments; and (3) what other benefits has the legislation produced."
Date: November 22, 1999
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Transportation Coordination: Benefits and Barriers Exist, and Planning Efforts Progress Slowly (open access)

Transportation Coordination: Benefits and Barriers Exist, and Planning Efforts Progress Slowly

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a legislative requirement, GAO provided information on federal agencies that provide nonemergency human services transportation, focusing on: (1) the benefits and incentives to human services transportation coordination; (2) the Department of Health and Human Services' (HHS) and the Federal Transit Administration's (FTA) efforts to identify barriers to transportation coordination; and (3) HHS' and FTA's efforts to enhance transportation coordination through state and local transportation planning."
Date: October 22, 1999
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
International Monetary Fund: Trade Policies of IMF Borrowers (open access)

International Monetary Fund: Trade Policies of IMF Borrowers

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a legislative requirement, GAO provided information on the International Monetary Fund (IMF), focusing on the: (1) extent to which IMF borrower countries restrict international trade and the borrowers whose trade has the potential to affect the United States; (2) reported trade barriers and export policies of four IMF borrowers that are among those with the greatest capacity to affect the United States--Brazil, Indonesia, the Republic of Korea, and Thailand--and recent actions reported to have been taken to reduce those barriers or modify policies; (3) actions, in the context of their recent IMF financing arrangements, the four countries have taken or are committed to take to liberalize their trading systems; and (4) extent to which the impact of the four countries' export policies on the United States can be predicted and measured and which U.S. industry sectors might be affected by recent changes in trade from these countries."
Date: June 22, 1999
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Defense Logistics: New 120-mm Tank Training Round Procurement Will Result in Savings (open access)

Defense Logistics: New 120-mm Tank Training Round Procurement Will Result in Savings

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO provided information on the Army's 1999 multiyear contracts for the procurement of 120-mm tank training rounds, focusing on: (1) whether the Army's actions in 1999 resulted in savings on the purchase of 120-mm tank training rounds; (2) the effect the Army's decision to no longer direct that propellant be purchased from the Radford Army Ammunition Plant had on plant overhead and employment; and (3) the potential effect the decision would have on Radford's wartime replenishment mission."
Date: November 22, 1999
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Probing coal reactivity by time-resolved small angle x-ray scattering. (open access)

Probing coal reactivity by time-resolved small angle x-ray scattering.

The objective of this study is to observe changes in coal structure in situ with small angle X-ray scattering (SAXS) during solvent swelling and during pyrolysis. We have built a SAXS instrument at the Basic Energy Sciences Synchrotrons Research Center at the Advanced Photon Source that allows us to obtain scattering patterns in the millisecond time domain. The eight Argonne Premium Coal samples were used in this study. The information that can be derived from these experiments, such as changes in fractal dimensionality and in size and type of porosity, was found to be very rank-dependent. In the swelling experiments, it was noted that for certain coals, structural changes occurred in just a few minutes.
Date: January 22, 1999
Creator: Winans, R. E.
Object Type: Article
System: The UNT Digital Library
Hierarchies Without Symmetries from Extra Dimensions (open access)

Hierarchies Without Symmetries from Extra Dimensions

It is commonly thought that small couplings in a low-energy theory, such as those needed for the fermion mass hierarchy or proton stability, must originate from symmetries in a high-energy theory. We show that this expectation is violated in theories where the Standard Model fields are confined to a thick wall in extra dimensions, with the fermions ''stuck'' at different points in the wall. Couplings between them are then suppressed due to the exponentially small overlaps of their wave functions. This provides a framework for understanding both the fermion mass hierarchy and proton stability without imposing symmetries, but rather in terms of higher dimensional geography. A model independent prediction of this scenario is non-universal couplings of the Standard Model fermions to the ''Kaluza-Klein'' excitations of the gauge fields. This allows a measurement of the fermion locations in the extra dimensions at the LHC or NLC if the wall thickness is close to the TeV scale.
Date: March 22, 1999
Creator: Arkani-Hamed, Nima
Object Type: Report
System: The UNT Digital Library
Nucleon decay in Soudan 2. (open access)

Nucleon decay in Soudan 2.

The Soudan 2 detector is used to search for evidence of nucleon decay. Particular emphasis is put on searches for modes with multiple-charged particles in the final state, and for modes suggested by super-symmetric theories.
Date: June 22, 1999
Creator: Goodman, M. C.
Object Type: Article
System: The UNT Digital Library
Deposition and Characterization of Highly Oriented Mg(3)(VO(4))(2) Thin Film Catalyst (open access)

Deposition and Characterization of Highly Oriented Mg(3)(VO(4))(2) Thin Film Catalyst

Magnesium vanadates are potentially important catalytic materials for the conversion of alkanes to alkenes via oxidative dehydrogenation. However, little is known about the active sites at which the catalytic reactions take place. It may be possible to obtain a significant increase in the catalytic efficiency if the effects of certain material properties on the surface reactions could be quantified and optimized through the use of appropriate preparation techniques. Given that surface reactivity is often dependent upon surface structure and that the atomic level structure of the active sites in these catalysts is virtually unknown, we desire thin film samples consisting of a single magnesium vanadate phase and a well defined crystallographic orientation in order to reduce complexity and simplify the study of active sites. We report on the use of reactive RF sputter deposition to fabricate very highly oriented, stoichiometric Mg{sub 3}(VO{sub 4}){sub 2} thin films for use in these surface analysis studies. Deposition of samples onto amorphous substrates resulted in very poor crystallinity. However, deposition of Mg{sub 3}(VO{sub 4}){sub 2} onto well-oriented, lattice-matched thin film ''seed'' layers such as Ti(0001), Au(111), or Pt(111) resulted in very strong preferential (042) crystallographic orientation (pseudo-hexagonal oxygen planes parallel to the substrate). This …
Date: October 22, 1999
Creator: Rodriguez, Mark A.; Ruffner, Judith A.; Sault, Allen G. & Tissot, Ralph G., Jr.
Object Type: Article
System: The UNT Digital Library
Mixed-conducting dense ceramics for gas separation applications. (open access)

Mixed-conducting dense ceramics for gas separation applications.

Mixed-conducting (electronic and ionic conducting) dense ceramics are used in many applications, including fuel cells, gas separation membranes, batteries, sensors, and electrocatalysis. This paper describes mixed-conducting ceramic membranes that are being developed to selectively remove oxygen and hydrogen from gas streams in a nongalvanic mode of operation (i.e., with no electrodes or external power supply). Ceramic membranes made of Sr-Fe-Co oxide (SFC), which exhibits high combined electronic and oxygen ionic conductivities, can be used for high-purity oxygen separation and/or partial oxidation of methane to synthesis gas (syngas, a mixture of CO and H{sub 2}). The electronic and ionic conductivities of SFC were found to be comparable in magnitude. Steady-state oxygen permeability of SFC has been measured as a function of oxygen-partial-pressure gradient and temperature. For an {approx}3-mm-thick membrane, the oxygen permeability was {approx}2.5 scc{center_dot}cm{sup {minus}2}{center_dot}min{sup {minus}1} at 900 C. Oxygen permeation increases as membrane thickness decreases. Tubular SFC membranes have been fabricated and operated at 900 C for {approx}1000 h in converting methane into syngas. The oxygen permeated through the membrane reacted with methane in the presence of a catalyst and produced syngas. We also studied the transport properties of yttria-doped BaCeO{sub 3{minus}{delta}} (BCY) by impedance spectroscopy and open-cell voltage …
Date: June 22, 1999
Creator: Balachandran, U.; Dorris, S. E.; Dusek, J. T.; Guan, J.; Liu, M.; Ma, B. et al.
Object Type: Article
System: The UNT Digital Library
Online modeling of the Fermilab accelerators (open access)

Online modeling of the Fermilab accelerators

Access through the Fermilab control system to beam physics models of the Fermilab accelerators has been implemented. The models run on Unix workstations, communicating with legacy VMS-based controls consoles via a relational database and TCP/IP.The client side (VMS) and the server side (Unix) are both implemented in object-oriented C++. The models allow scientists and operators in the control room to do beam physics calculations. Settings of real devices as input to the model are supported, and readings from beam diagnostics may be compared with model predictions.
Date: November 22, 1999
Creator: E. McCrory, O. Krivosheev, L. Michelotti and J-F. Ostiguy
Object Type: Article
System: The UNT Digital Library
HIGH RESOLUTION MICROTOMOGRAPHY FOR DENSITY AND SPATIAL INFORMATION ABOUT WOOD STRUCTURES. (open access)

HIGH RESOLUTION MICROTOMOGRAPHY FOR DENSITY AND SPATIAL INFORMATION ABOUT WOOD STRUCTURES.

Microtomography has successfully been used to characterize loss of structural integrity of wood. Tomographic images were generated with the newly developed third generation x-ray computed microtomography (XCMT) instrument at the X27A beamline at the National Synchrotron Light Source (NSLS). The beamline is equipped with high-flux x-ray monochromator based on multilayer optics developed for this application. The sample is mounted on a translation stage with which to center the sample rotation, a rotation stage to perform the rotation during data collection and a motorized goniometer head for small alignment motions. The absorption image is recorded by a single-crystal scintillator, an optical microscope and a cooled CCD array detector. Data reconstruction has provided three-dimensional geometry of the heterogeneous wood matrix in microtomographic images. Wood is a heterogeneous material composed of long lignocellulose vessels. Although wood is a strong natural product, fungi have evolved chemical systems that weaken the strength properties of wood by degrading structural vessels. Tomographic images with a resolution of three microns were obtained nonintrusively to characterize the compromised structural integrity of wood. Computational tools developed by Lindquist et al (1996) applied to characterize the microstructure of the tomographic volumes.
Date: July 22, 1999
Creator: ILLMAN,B.
Object Type: Article
System: The UNT Digital Library
U.S. Atomic Energy Commission's Environmental Research Programs Established in the 1950s (open access)

U.S. Atomic Energy Commission's Environmental Research Programs Established in the 1950s

In 1946 the United States (U.S.) Congress passed the Atomic Energy Act and with it created the Atomic Energy Commission. For the ensuing half-century the AEC and its successors have pursued biological and environmental research with an unwavering mandate to exploit the use of fissionable and radioactive material for medical purposes and, at the same time, to ensure the health of it's workers, the public, and the environment during energy technology development and use (AEC. 1961; DOE 1983; DOE, 1997). The following pages are testimony to the success of this undeviating vision (Figure 1). From the early days of the AEC, cooperation has also linked researchers from the national laboratories, the academic community, and the private sector. The AEC-sponsored research both at national laboratories and universities, and also supported graduate students to develop a cadre of health physicists, radiation biologists, and nuclear engineers. Coordinating these diverse performers has been crucial to the unique teaming that has made many of the successes possible. The success of the biological and environmental research program has often been shared with other federal agencies. The future will demand even stronger and more substantive intraagency, interagency, and international collaborations.
Date: September 22, 1999
Creator: Reichle, D.E.
Object Type: Article
System: The UNT Digital Library
Buoyancy and Dissolution of the Floating Crust Layer in Tank 241-SY-101 During Transfer and Back-Dilution (open access)

Buoyancy and Dissolution of the Floating Crust Layer in Tank 241-SY-101 During Transfer and Back-Dilution

To remediate gas retention in the floating crust layer and the potential for buoyant displacement gas releases from below the crust, waste will be transferred out of Hanford Tank 241-SY-101 (SY-101) in the fall of 1999 and back-diluted with water in several steps of about 100,000 gallons each. To evaluate the effects of back-dilution on the crust a static buoyancy model is derived that predicts crust and liquid surface elevations as a function of mixing efficiency and volume of water added during transfer and back-dilution. Experimental results are presented that demonstrate the basic physics involved and verify the operation of the models. A dissolution model is also developed to evaluate the effects of dissolution of solids on crust flotation. The model includes dissolution of solids suspended in the slurry as well as in the crust layers. The inventory and location of insoluble solids after dissolution of the soluble fraction are also tracked. The buoyancy model is applied to predict the crust behavior for the first back-dilution step in SY-101. Specific concerns addressed include conditions that could cause the crust to sink and back-dilution requirements that keep the base of the crust well above the mixer pump inlet.
Date: November 22, 1999
Creator: Stewart, C. W.; Sukamto, J. H.; Cuta, J. M. & Rassat, S. D.
Object Type: Report
System: The UNT Digital Library