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3,034 Matching Results
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Condition/damage monitoring methodologies.
COSMOS, in cooperation with the Advanced National Seismic System (ANSS), is sponsoring an invited workshop entitled Strong-Motion Instrumentation of Buildings. The workshop is motivated by the need to obtain broad input from earthquake engineering professionals for the purpose of developing guidelines for strong motion instrumentation of buildings as part of the ANSS instrument installation effort. The ANSS has been authorized capital finding for 6,000 strong-motion instruments. It is expected that funding for purchase and installation of instruments will be appropriated over a period of several years. The instrument installations must meet multiple monitoring objectives including instrumentation of buildings of various types, urban reference stations, and emergency response and recovery actions. An important opportunity therefore, exists to comprehensively define strong-motion monitoring needs as an underpinning basis for developing guidelines for installation of this important monitoring system. This workshop will specifically address instrumentation of buildings.
Date:
January 1, 2001
Creator:
Farrar, C. R. (Charles R.) & Sohn, Hong Yong
Object Type:
Article
System:
The UNT Digital Library
Continued development of the next generation of SOURCES
In development for over two decades, the SOURCES computer code calculates neutron production rates and spectra from four types of problems: homogeneous media, two-region interfaces, three-region interfaces and that of a monoenergetic alpha particle beam incident on a slab of target material. In terms of file structure, SOURCES consists of a usercreated input file (tapel), several data files (tapes 2-5) and up to six output files (outp, outp2, and tapes 6-9). SOURCES was recently upgraded from version 4A to version 48 when the code's decay data library, tapeti, was updated for 44 of the 105 available decay sources. The new version provided spontaneous fission information for 252Cf and alpha decay data revisions for 43 isotopes and isomers having Watt fission spectra parameters.' Following that work, this summary documents similar modifications made to the remaining 61 sources. It also summarizes additional enhancements and planned improvements to SOURCES for the next major code release.
Date:
January 1, 2001
Creator:
Sattelberger, J. A. (Jenifer A.) & Shores, E. F. (Erik F.)
Object Type:
Article
System:
The UNT Digital Library
Control of visible harmonic generation using polarization in photonic crystal fibers
The polarization state of the input pulses to a segment of microstructured fiber controls the harmonic generation yielding specific frequencies depending on of the input state.
Date:
January 1, 2001
Creator:
Omenetto, F. G. (Fiorenzo G.); Efimov, A. V. (Anatoly V.); Taylor, Antoinette J.,; Knight, J. C. (Jonathan C.); Wadsworth, W. J. (William J.) & Russell, P. S. J. (Philip St. J.)
Object Type:
Article
System:
The UNT Digital Library
Correction and Additions to CA/AP/33
N/A
Date:
January 1, 2001
Creator:
D., Courant E.
Object Type:
Report
System:
The UNT Digital Library
The correlation of indentation size effect experiments with pyramidal and spherical indenters.
Experiments were conducted in annealed iridium using pyramidal and spherical indenters over a wide range of load. For a Berkovich pyramidal indenter, the hardness increased with decreasing depth of penetration. However, for spherical indenters, hardness increased with decreasing sphere radius. Based on the number of geometrically necessary dislocations generated during indentation, a theory that takes into account the work hardening differences between pyramidal and spherical indenters is developed to correlate the indentation size effects measured with the two indenters. The experimental results verify the theoretical correlation.
Date:
January 1, 2001
Creator:
Swadener, J. G. (John G.); George, Easo P. & Pharr, G.M.
Object Type:
Article
System:
The UNT Digital Library
Cosmic Ray Background Analysis for a Cargo Container Counter.
We have developed a new model for calculating the expected yield of cosmic-ray spallation neutrons in a Cargo Container Counter, and we have benchmarked the model against measurements made with several existing large neutron counters. We also developed two versions of a new measurement uncertainty prediction code based on Microsoft Excel spreadsheets. The codes calculate the minimum detectability limit for the Cargo Container Counter for either neutron singles or doubles counting, and also propagate the uncertainties associated with efficiency normalization flux monitors and cosmic ray flux monitors. This paper will describe the physics basis for this analysis, and the results obtained for several different counter designs.
Date:
January 1, 2001
Creator:
Ensslin, Norbert; Geist, William H.; Lestone, John P.; Mayo, Douglas R. & Menlove, Howard O.
Object Type:
Article
System:
The UNT Digital Library
[Crowd]
An overview of the people attending the Dallas Hispanic Expo.
Date:
January 1, 2001
Creator:
Castillo, José L.
Object Type:
Photograph
System:
The UNT Digital Library
Crystal structure, superconductivity and magnetism of the quasi-2D heavy fermion materials CeTIn[sub 5] (T = Co, Rh, Ir).
The crystal structure of the recently discovered heavy-fermion (HF) superconductor CeCoIn{sub 5} (T{sub c} = 2.3 K) has been determined by high-resolution neutron powder diffraction. It is tetragonal (space group P4/mmm), with lattice parameters a = 4.61292(9) {angstrom} and c = 7.5513(2) {angstrom} at ambient conditions. Whereas CeCoIn{sub 5} is isostructural with the HF aniferromagnet CeRhIn{sub 5} and the HF superconductor CeIrIn{sub 5}, its cell constants and its only variable positional parameter, zIn2, differ significantly from the corresponding ones of CeRhIn{sub 5} and CeIrIn{sub 5}. As a result, the distortions of the cuboctahedron [CeIn{sub 3}], which is the key structural unit in all three materials, are different in CeCoIn{sub 5} from the ones in CeRhIn{sub 5} and CeIrIn{sub 5}. The compounds CeCoIn{sub 5} and CeIrIn{sub 5}, which contain the most distorted (in one or another way) [CeIn{sub 3}] cuboctahedra exhibit superconductivity at ambient pressure below 2.3 K and 0.4 K, respectively. On the other hand, CeRhIn{sub 5}, in which [CeIn{sub 3}] cuboctahedra are the less distorted, and the cubic HF CeIn{sub 3} are antiferromagnets at ambient pressure with T{sub N} = 3.8 K and 10 K respectively; they become superconductors under pressure of 16 kbar and 25 kbar with T{sub …
Date:
January 1, 2001
Creator:
Sarrao, John L.,; Pagliuso, P. J. (Pascoal J.); Moreno, N. O.; Thompson, J. D. (Joe David); Fisk, Zachary & Moshopoulou, E. G.
Object Type:
Article
System:
The UNT Digital Library
Current and Future Dynamics of the Red-Cockaded Woodpecker Population Inhabiting the Savannah River National Environmental Research Park: Managing For Population Growth
Research aimed to study the dynamics of the SRS population of Red-Cockaded woodpecker and compare to those of other populations to identify factors limiting population growth; recruitment clusters were evaluated to determine what properties of individual cavity trees, surrounding habitat and the surrounding landscape might limit occupancy through natural dispersal. A spatial simulation model was used to project expected dispersal rates and population growth under current conditions and compare those estimates to observed dispersal and population growth. Red cockaded woodpecker populations at SRS are stable considering size. Research reveals that closer placement of recruitment clusters to active territories would produce higher growth rates while decreasing management intensity.
Date:
January 1, 2001
Creator:
Walters, J. R.; Taylor, T. B.; Daniels, S. J.; Crowder, L. B. & Pridd, J. A.
Object Type:
Report
System:
The UNT Digital Library
[Dallas Hispanic Expo]
Photograph of a crowd at the Dallas Hispanic Expo.
Date:
January 1, 2001
Creator:
Castillo, José L.
Object Type:
Photograph
System:
The UNT Digital Library
[Dallas Hispanic Expo program]
On a table is a stack of programs detailing the events at the Dallas Hispanic Expo.
Date:
January 1, 2001
Creator:
Castillo, José L.
Object Type:
Photograph
System:
The UNT Digital Library
DANCE : Device for Measurement of (n.g.) Reactions on radioactive Species /
DANCE (Device for Advanced Neutron Capture Experiments) is a 4{pi} 162 element BaF{sub 2} array under development at Los Alamos National Laboratory. It is designed to provide high granularity, fast timing and high photon detection efficiency. It will be located at the Los Alamos Neutron Scattering Center where neutrons are produced using 800 MeV proton induced spallation reactions on heavy element production targets. Using the pulsed high neutron fluence available at this facility combined with time of flight techniques it will be possible to make neutron capture measurements in the neutron energy range from eV to 100's of keV on rare and radioactive target material at the milligram and below level. These measurements will provide critically needed data for the interpretation of the astrophysical s-process 'branching point' nuclei as well as information for reactions needed in understanding transmutation processes of radioactive species.
Date:
January 1, 2001
Creator:
Chamberlin, E. P. (Edwin P.); Dragowsky, M. (Michael); Fowler, Malcolm M.; Miller, G. G. (Geoffrey G.); Palmer, P. D. (Phillip D.); Pangualt, L. N. (Laurence N.) et al.
Object Type:
Article
System:
The UNT Digital Library
A data automation system at Los Alamos National Laboratory.
Idaho National Engineering and Environmental Laboratory (INEEL) has developed an automated computer program, Data Review Expert System (DRXS), for reviewing nondestructive assay (NDA) data. DRXS significantly reduces the data review time needed to meet characterization requirements for the Waste Isolation Pilot Plant (WIPP). Los Alamos National Laboratory (LANL) is in the process of developing a computer program, Software System Logic for Intelligent Certification (SSLIC), to automate other tasks associa ted with characterization of Transuranic Waste (TRU) samples. LANL has incorporated a version of DRXS specific to LANL's isotopic data into SSLIC. This version of SSLIC was audited by the National Transuranic Program on October, 24, 2001. This paper will present the results of the audit, and discuss future plans for SSLIC including the integration on the INEELLANL developed Rule Editor.
Date:
January 1, 2001
Creator:
Betts, S. E. (Stephen E.); Schneider, C. M. (Connie M.) & Pickrell, M. M. (Mark Manley)
Object Type:
Article
System:
The UNT Digital Library
DATA NORMALIZATION : A KEY FOR STRUCTURAL HEALTH MONITORING
Structural health monitoring (SHM) is the implementation of a damage detection strategy for aerospace, civil and mechanical engineering infrastructure. Typical damage experienced by this infrastructure might be the development of fatigue cracks, degradation of structural connections, or bearing wear in rotating machinery. For SHM strategies that rely on vibration response measurements, the ability to normalize the measured data with respect to varying operational and environmental conditions is essential if one is to avoid false-positive indications of damage. Examples of common normalization procedure include normalizing the response measurements by the measured inputs as is commonly done when extracting modal parameters. When environmental cycles influence the measured data, a temporal normalization scheme may be employed. This paper will summarize various strategies for performing this data normalization task. These strategies fall into two general classes: (1) Those employed when measures of the varying environmental and operational parameters are available; (2) Those employed when such measures are not available. Whenever data normalization is performed, one runs the risk that the damage sensitive features to be extracted from the data will be obscured by the data normalization procedure. This paper will summarize several normalization procedures that have been employed by the authors and issues that …
Date:
January 1, 2001
Creator:
Farrar, C. R. (Charles R.); Sohn, H. (Hoon) & Worden, K.
Object Type:
Article
System:
The UNT Digital Library
Defect studies of optical materials using near-field scanning optical microscopy and spectroscopy
Defects and impurities are generally the key material properties that govern the quality and useful lifetime of optical components. Progress in materials synthesis has advanced so that today, for high power laser applications such as the National Ignition Facility (NIF), laser induced damage is typically initiated at the site of sub-micron defects. For example, in laser glass and non-linear optical crystals such as KDP, bulk damage occurs when sub-micron metal inclusion particles absorb laser energy, leading to local heating and eventually material breakdown. It is clear that continued progress in optical materials synthesis is inextricably connected with the need for a detailed understanding of the morphology and composition of the sub-micron damage nucleation sites and the associated damage mechanisms. In this project, we have developed near-field scanning optical microscopy (NSOM) as a tool to optically characterize materials at a spatial resolution of about one order of magnitude better than conventional optical microscopy. Optical microscopy was the first and thus best understood microscopy, and a large number of contrast and spectroscopy techniques have been developed over the years. NSOM is the logical continuation of optical microscopy to the nanometer scale. NSOM combines scanning probe and optical fiber technologies, and simultaneously provides …
Date:
January 1, 2001
Creator:
Yan, M; McWhirter, J; Huser, T & Siekhaus, W
Object Type:
Report
System:
The UNT Digital Library
Deformation mechanisms at Different grain sizes in a cryogenically ball-milled Al-Mg alloy.
An Al-7.5 wt. % Mg alloy was ball-milled in liquid N2 for eight hours and its microstructures were investigated using transmission electron microscopy. Electron diffraction confirmed that the resulting powder is a supersaturated Al-Mg solid solution with a face-centered cubic structure. Three nanostructures with different grain size ranges and shapes were observed and the deformation mechanisms in these structures were found to be different. The reasons for the different deformation mechanisms were discussed. Keywords: Aluminum alloy; Cryogenic ball milling; Transmission electron microscopy; Microstructure.
Date:
January 1, 2001
Creator:
Liao, Xiaozhou; Huang, J. (Jianyu); Zhu, Y. T. (Yuntian Theodore); Zhou, F. (Fei) & Lavernia, Enrique J.
Object Type:
Article
System:
The UNT Digital Library
Demonstration of advanced combustion NO{sub X} control techniques for a wall-fired boiler. Project performance summary, Clean Coal Technology Demonstration Program
The project represents a landmark assessment of the potential of low-NO{sub x} burners, advanced overtire air, and neural-network control systems to reduce NO{sub x} emissions within the bounds of acceptable dry-bottom, wall-fired boiler performance. Such boilers were targeted under the Clean Air Act Amendments of 1990 (CAAA). Testing provided valuable input to the Environmental Protection Agency ruling issued in March 1994, which set NO{sub x} emission limits for ''Group 1'' wall-fired boilers at 0.5 lb/10{sup 6} Btu to be met by January 1996. The resultant comprehensive database served to assist utilities in effectively implementing CAAA compliance. The project is part of the U.S. Department of Energy's Clean Coal Technology Demonstration Program established to address energy and environmental concerns related to coal use. Five nationally competed solicitations sought cost-shared partnerships with industry to accelerate commercialization of the most advanced coal-based power generation and pollution control technologies. The Program, valued at over $5 billion, has leveraged federal funding twofold through the resultant partnerships encompassing utilities, technology developers, state governments, and research organizations. This project was one of 16 selected in May 1988 from 55 proposals submitted in response to the Program's second solicitation. Southern Company Services, Inc. (SCS) conducted a comprehensive evaluation …
Date:
January 1, 2001
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Demonstration of damage with a wireless sensor network
A damage detection system was developed with commercially available wireless sensors. Statistical process control methods were used to monitor the correlation of vibration data from two accelerometers mounted across a joint. Changes in correlation were used to detect damage to the joint. All data processing was done remotely on a microprocessor integrated with the wireless sensors to allow for the transmission of a simple damaged or undamaged status for each monitored joint. Additionally, a portable demonstration structure was developed to showcase the capabilities of the damage detection system to monitor joint failure in real time.
Date:
January 1, 2001
Creator:
Tanner, Neal A. & Farrar, C. R. (Charles R.)
Object Type:
Article
System:
The UNT Digital Library
DENSITY-FUNCTIONAL MOLECULAR DYNAMICS SIMULATIONS OF SHOCKED MOLECULAR LIQUIDS
Molecular dynamics (MD) simulations have been performed for highly compressed fluid deuterium, nitrogen, and oxygen, in the density and temperature regime of shock-compression experiments, using density functional (DF) electronic structure techniques to describe the interatomic forces. The Hugoniots derived from the calculated equation-of-state for deuterium does not exhibit the large compression predicted by the recently reported laser-driven experiments. However, the Hugoniot derived for nitrogen and oxygen agree well with explosively-driven and gas-gun experiments. The nature of the fluid along the Hugoniot, as calculated with DF-MD, has been analyzed. All three species (D2, N2, amd 02) undergo a continuous transition from a molecular to a partially dissociated fluid containing a mixture of atoms and molecules.
Date:
January 1, 2001
Creator:
Kress, J. D. (Joel D.); Mazevet, S. (Stephane) & Collins, L. A. (Lee A.)
Object Type:
Article
System:
The UNT Digital Library
DESIGN CONSIDERATIONS OF FAST KICKER SYSTEMS FOR HIGH INTENSITY PROTON ACCELERATORS
In this paper, we discuss the specific issues related to the design of the Fast Kicker Systems for high intensity proton accelerators. To address these issues in the preliminary design stage can be critical since the fast kicker systems affect the machine lattice structure and overall design parameters. Main topics include system architecture, design strategy, beam current coupling, grounding, end user cost vs. system cost, reliability, redundancy and flexibility. Operating experience with the Alternating Gradient Synchrotron injection and extraction kicker systems at Brookhaven National Laboratory and their future upgrade is presented. Additionally, new conceptual designs of the extraction kicker for the Spallation Neutron Source at Oak Ridge and the Advanced Hydrotest Facility at Los Alamos are discussed.
Date:
January 1, 2001
Creator:
Parsons, W. M. (William Mark); Walstrom, P. L. (Peter L.); Murray, M. M. (Matthew M.); Zhang, Wu & Sandberg, J. (Jon)
Object Type:
Article
System:
The UNT Digital Library
Design of a [Beta]=0.175 2-Gap Spoke Resonator
In this paper, we present the electromagnetic and structural design of a low-b superconducling spoke resonator for a beam-test in the Low Energy Demonstration Accelerator (LEDA). This test is part of the Advanced Accelerator Applications (AAA) project. Recently, the sole use of superconducting resonators from 6.7 MeV on has been approved for this project. The beam test will use the lowest- resonator from this accelerator design. The choices of the cavity dimensions are driven by its use imrnediately after the LEDA Radio-Frequency Quadrupole (RFQ). The frequency is 350 MHz, the lengt corresponds to a geometric p (Ps) of 0.175. Our design approach has been to carry out an integrated RF and mechanical design from the start. The final cavity is well understood in terms of IW: and mechanical properties. The RF properties, like Q, WQ, peak surface fields and acceleration efficiency are very reasonable for such a low- structure. 'The design also includes power coupler, vacuum and pick-up ports and lheir influences. The mechanical design added tuning sensitivities, tuning forces, stiffening schemes and the understanding of stresses under various load conditions. This presentation reflects changes in the coupling port and the beam aperture compared to a previously presented design.
Date:
January 1, 2001
Creator:
Krawczyk, F. L. (Frank L.); Chan, K. D. (Kwok-Chi D.); Garnett, R. W. (Robert W.); Gentzlinger, R.C. (Robert C.); La Fave, R. P. (Richard P.); Kelley, J. P. (John Patrick) et al.
Object Type:
Article
System:
The UNT Digital Library
Design of Microwave Band Pass Filters for the Debuncher Stochastic Cooling System
The FIR filters designed for the debuncher stochastic cooling system needed improvement. Its bandwidth was too wide, its magnitude was not flat, its phase ripple was too great, and it was difficult to control the characteristics of the filter. A simple microwave technique was employed to have a short time delay, simple robust layout, and small board size. A significant savings was seen over the FIR technique and these filters were installed in the Antiproton Source Debuncher while the FIR filters were removed from the debuncher stochastic cooling entirely.
Date:
January 1, 2001
Creator:
Deibele, C.
Object Type:
Report
System:
The UNT Digital Library
DESIGNING AN OPPORTUNITY FUEL WITH BIOMASS AND TIRE-DERIVED FUEL FOR COFIRING AT WILLOW ISLAND GENERATING STATION
During the period October 1, 2000 - December 31, 2000, Allegheny Energy Supply Co., LLC (Allegheny) executed a Cooperative Agreement with the National Energy Technology Laboratory to implement a major cofiring demonstration at the Willow Island Generating Station Boiler No.2. Willow Island Boiler No.2 is a cyclone boiler. Allegheny also will demonstrate separate injection cofiring at the Albright Generating Station Boiler No.3, a tangentially fired boiler. The Allegheny team includes Foster Wheeler as its primary subcontractor. Additional subcontractors are Cofiring Alternatives and N.S. Harding and Associates. This report summarizes the activities associated with the Designer Opportunity Fuel program, and demonstrations at Willow Island and Albright Generating Stations. The second quarter of the project involved completing the designs for each location. Further, geotechnical investigations proceeded at each site. Preparations were made to perform demolition on two small buildings at the Willow Island site. Fuels strategies were initiated for each site. Test planning commenced for each site. A groundbreaking ceremony was held at the Willow Island site on October 18, with Governor C. Underwood being the featured speaker.
Date:
January 1, 2001
Creator:
Payette, K. & Tillman, D.
Object Type:
Report
System:
The UNT Digital Library
Detection of Cell Wall Chemical Variation in Zea Mays Mutants Using Near-Infrared Spectroscopy
Corn stover is regarded as the prime candidate feedstock material for commercial biomass conversion in the United States. Variations in chemical composition of Zea mays cell walls can affect biomass conversion process yields and economics. Mutant lines were constructed by activating a Mu transposon system. The cell wall chemical composition of 48 mutant families was characterized using near-infrared (NIR) spectroscopy. NIR data were analyzed using a multivariate statistical analysis technique called Principal Component Analysis (PCA). PCA of the NIR data from 349 maize leaf samples reveals 57 individuals as outliers on one or more of six Principal Components (PCs) at the 95% confidence interval. Of these, 19 individuals from 16 families are outliers on either PC3 (9% of the variation) or PC6 (1% of the variation), the two PCs that contain information about cell wall polymers. Those individuals for which altered cell wall chemistry is confirmed with wet chemical analysis will then be subjected to fermentation analysis to determine whether or not biomass conversion process kinetics, yields and/or economics are significantly affected. Those mutants that provide indications for a decrease in process cost will be pursued further to identify the gene(s) responsible for the observed changes in cell wall composition …
Date:
January 1, 2001
Creator:
Buyck, N. & Thomas, S.
Object Type:
Article
System:
The UNT Digital Library