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Using multicast in the global communications infrastructure for group communication (open access)

Using multicast in the global communications infrastructure for group communication

International Monitoring System (IMS) stations and the International Data Centre (IDC) of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization generate data and products that must be transmitted to one or more receivers. The application protocols used to transmit the IMS data and IDC products will be CD-x and IMS-x and the World Wide Web (WWW). These protocols use existing Internet applications and Internet protocols to send their data. The primary Internet applications in use are electronic mail (e-mail) and the file transfer protocol (ftp). The primary Internet communication protocol in use is the Transmission Control Protocol (TCP), which provides reliable delivery to the receiver. These Internet applications and protocol provide unicast (point-to-point) communication. A message sent using unicast has a single recipient; any message intended for more than one recipient must be sent to each recipient individually. In the current design, the IDC and the National Data Centres (NDC's) provide data forwarding to the appropriate receivers. The overhead associated with using unicast to transmit messages to multiple receivers either directly or through a forwarder increases linearly with the number of receivers. In addition, using a forwarding site introduces possible delays and possible points of failure in the path …
Date: July 30, 1999
Creator: Agarwal, Deborah A.
System: The UNT Digital Library
Single-particle states in transcurium nuclei. (open access)

Single-particle states in transcurium nuclei.

Identification of single-particle states in the heaviest known nuclei is important because their energies can be used to test the single-particle potential in these high-Z elements. These states can be identified by studying the decay schemes of very heavy odd-mass nuclides. For neutrons, the heaviest odd-mass nuclide available in milliCurie quantities is the 20-h {sup 255}Fm and for protons the heaviest nuclide available is the 20-d {sup 253}Es. These two isotopes were obtained from the Transplutonium Element Production Program at Oak Ridge and their spectra were measured with high-resolution germanium spectrometers. From the results of these measurements we have identified states in {sup 251}Cf and {sup 249}Bk up to 1 MeV excitation energy.
Date: September 30, 1999
Creator: Ahmad, I.
System: The UNT Digital Library
Liquid fuel reformer development. (open access)

Liquid fuel reformer development.

At Argonne National Laboratory we are developing a process to convert hydrocarbon fuels to a clean hydrogen feed for a fuel cell. The process incorporates a partial oxidation/steam reforming catalyst that can process hydrocarbon feeds at lower temperatures than existing commercial catalysts. We have tested the catalyst with three diesel-type fuels: hexadecane, low-sulfur diesel fuel, and a regular diesel fuel. We achieved complete conversion of the feed to products. Hexadecane yielded products containing 60% hydrogen on a dry, nitrogen-free basis at 800 C. For the two diesel fuels, higher temperatures, >850 C, were required to approach similar levels of hydrogen in the product stream. At 800 C, hydrogen yield of the low sulfur diesel was 32%, while that of the regular diesel was 52%. Residual products in both cases included CO, CO{sub 2}, ethane, ethylene, and methane.
Date: July 30, 1999
Creator: Ahmed, S.; Krumpelt, M.; Pereira, C. & Wilkenhoener, R.
System: The UNT Digital Library
X-ray diffraction studies using diamond coated rhenium gasket to megabar pressures (open access)

X-ray diffraction studies using diamond coated rhenium gasket to megabar pressures

X-ray diffraction studies at megabar pressures are limited by the sample thickness between the diamond anvils. High strength gaskets are desirable to improve the quality of x-ray diffraction data. We present a technique which employs a microwave plasma chemical vapor deposited diamond layer on one side of a rhenium gasket. As a test case, we show energy dispersive x-ray diffraction data on rare earth metal neodymium to 153 GPa using a synchrotron source. The increased sample thickness results in an unambiguous crystal structure determination of a monoclinic phase in neodymium above 75 GPa. [chemical vapor deposition, diamond, rhenium gasket, x-ray diffraction, neodymium]
Date: September 30, 1999
Creator: Akella, J; Catledge, S A; Chesnut, G N; Prokop, H; Vohra, Y K & Weir, S T
System: The UNT Digital Library
Local Probe into the Atomic Structure of Metallic Glasses using EELS (open access)

Local Probe into the Atomic Structure of Metallic Glasses using EELS

Electron energy loss spectroscopy (EELS) is used to extract information on the topological arrangement of atoms around Pd in the bulk-glass-forming Pd{sub 60}Ni{sub 20}P{sub 20}. It is found that the environment around Pd in the glass is only a slight modification of the Pd crystalline structure. However, the modification is enough to allow this alloy to form a glass in bulk. In examining the differences between the structure of crystalline Pd and glassy Pd{sub 60}Ni{sub 20}P{sub 20} it is concluded that incorporation of Ni and P into the structure frustrates the structure enough that glass formation becomes easy.
Date: November 30, 1999
Creator: Alamgir, F. M.; Ito, Y.; Schwarz, R. B.; Jain, H. & Williams, D. B.
System: The UNT Digital Library
Intricate Mechanisms-on-a Chip Enabled by 5-Level Surface Micromachining (open access)

Intricate Mechanisms-on-a Chip Enabled by 5-Level Surface Micromachining

Surface micromachining generally offers more design freedom than related technologies, and it is the technology of choice for most microelectromechanical applications that require multi-level structures. However, the design flexibility that surface micromachining offers is not without limitations. In addition to determining how to fabricate devices in a planar world, the designer also needs to consider issues such as film quality, thickness, residual stress, topography propagation, stringers, processing limitations, and concerns about surface adhesion [1]. Only a few years ago, these were the types of issues that limited design complexity. As the technology improved, the number of mechanical layers available to the designer became the dominant constraint on system functionality. In response, we developed a 5-level polysilicon fabrication technology [2] that offers an unprecedented level of microelectromechanical complexity with simultaneous increases in system yield and robustness. This paper outlines the application that was the driving force behind this work and describes the first devices specifically designed for and fabricated in this technology. The 5-level fabrication technology developed to support this program is known as SUMMiT-V. Four mechanical layers of polysilicon referred to as polyl, poly2, poly3, and poly4 are fabricated above a polyO electrical interconnect and ground plane layer [2,4]. PolyO …
Date: March 30, 1999
Creator: Allen, J. J.; McWhorter, P. J.; Miller, S. L.; Rodgers, M. S.; Smith, J. H. & Sniegowski, J. J.
System: The UNT Digital Library
MHD Modeling of Conductors at Ultra-High Current Density (open access)

MHD Modeling of Conductors at Ultra-High Current Density

In conjunction with ongoing high-current experiments on Sandia National Laboratories' Z accelerator we have revisited a problem first described in detail by Heinz Knoepfel. MITLs of previous pulsed power accelerators have been in the 1-Tesla regime. Z's disc transmission line (downstream of the current addition) is in a 100-1200 Tesla regime, so its conductors cannot be modeled simply as static infinite conductivity boundaries. Using the MHD code MACH2 we have been investigating conductor hydrodynamics, characterizing the joule heating, magnetic field diffusion, and material deformation, pressure, and velocity over a range of current densities, current rise-times, and conductor materials. Three purposes of this work are ( 1) to quantify power flow losses owing to ultra-high magnetic fields, (2) to model the response of VISAR diagnostic samples in various configurations on Z, and (3) to incorporate the most appropriate equation of state and conductivity models into our MHD computations. Certain features are strongly dependent on the details of the conductivity model. Comparison with measurements on Z will be discussed.
Date: June 30, 1999
Creator: Asay, J. R.; Desjarlais, M. P.; Douglas, M. R.; Frese, M. H.; Hall, C. A.; Morse, R. L. et al.
System: The UNT Digital Library
Is cold better ? - exploring the feasibility of liquid-helium-cooled optics. (open access)

Is cold better ? - exploring the feasibility of liquid-helium-cooled optics.

Both simulations and recent experiments conducted at the Advanced Photon Source showed that the performance of liquid-nitrogen-cooled single-silicon crystal monochromators can degrade in a very rapid nonlinear fashion as the power and for power density is increased. As a further step towards improving the performance of silicon optics, we propose cooling with liquid helium, which dramatically improves the thermal properties of silicon beyond that of liquid nitrogen and brings the performance of single silicon-crystal-based synchrotrons radiation optics up to the ultimate limit. The benefits of liquid helium cooling as well as some of the associated technical challenges will be discussed, and results of thermal and structural finite elements simulations comparing the performance of silicon monochromators cooled with liquid nitrogen and helium will be given.
Date: September 30, 1999
Creator: Assoufid, L.; Mills, D.; Macrander, A. & Tajiri, G.
System: The UNT Digital Library
Studies of ferroelectric heterostructure thin films and interfaces via in situ analytical techniques. (open access)

Studies of ferroelectric heterostructure thin films and interfaces via in situ analytical techniques.

The science and technology of ferroelectric thin films has experienced an explosive development during the last ten years. Low-density non-volatile ferroelectric random access memories (NVFRAMs) are now incorporated in commercial products such as ''smart cards'', while high permittivity capacitors are incorporated in cellular phones. However, substantial work is still needed to develop materials integration strategies for high-density memories. We have demonstrated that the implementation of complementary in situ characterization techniques is critical to understand film growth and interface processes, which play critical roles in film microstructure and properties. We are using uniquely integrated time of flight ion scattering and recoil spectroscopy (TOF-ISARS) and spectroscopic ellipsometry (SE) techniques to perform in situ, real-time studies of film growth processes in the high background gas pressure required to growth ferroelectric thin films. TOF-ISARS provides information on surface processes, while SE permits the investigation of buried interfaces as they are being formed. Recent studies on SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub x}Sr{sub 1{minus}x}TiO{sub 3} (BST) film growth and interface processes are discussed.
Date: August 30, 1999
Creator: Auciello, O.; Dhote, A.; Gao, Y.; Gruen, D. M.; Im, J.; Irene, E. A. et al.
System: The UNT Digital Library
Design of highly specific cytotoxins by using trans-splicing ribozymes (open access)

Design of highly specific cytotoxins by using trans-splicing ribozymes

This article discusses the design of highly specific cytotoxins by using trans-splicing ribozymes.
Date: March 30, 1999
Creator: Ayre, Brian G.; Köhler, Uwe; Haseloff, Jim & Goodman, Howard M.
System: The UNT Digital Library
Performance Assessment Uncertainty Analysis for Japan's HLW Program Feasibility Study (H12) (open access)

Performance Assessment Uncertainty Analysis for Japan's HLW Program Feasibility Study (H12)

Most HLW programs in the world recognize that any estimate of long-term radiological performance must be couched in terms of the uncertainties derived from natural variation, changes through time and lack of knowledge about the essential processes. The Japan Nuclear Cycle Development Institute followed a relatively standard procedure to address two major categories of uncertainty. First, a FEatures, Events and Processes (FEPs) listing, screening and grouping activity was pursued in order to define the range of uncertainty in system processes as well as possible variations in engineering design. A reference and many alternative cases representing various groups of FEPs were defined and individual numerical simulations performed for each to quantify the range of conceptual uncertainty. Second, parameter distributions were developed for the reference case to represent the uncertainty in the strength of these processes, the sequencing of activities and geometric variations. Both point estimates using high and low values for individual parameters as well as a probabilistic analysis were performed to estimate parameter uncertainty. A brief description of the conceptual model uncertainty analysis is presented. This paper focuses on presenting the details of the probabilistic parameter uncertainty assessment.
Date: August 30, 1999
Creator: Baba, T.; Ishiguro, K.; Ishihara, Y.; Sawada, A.; Umeki, H.; Wakasugi, K. et al.
System: The UNT Digital Library
Experimental investigation of beryllium-based multilayer coatings for extreme ultraviolet lithography (open access)

Experimental investigation of beryllium-based multilayer coatings for extreme ultraviolet lithography

The performance of beryllium-based multilayer coatings designed to reflect light of wavelengths near 11 nm, at normal incidence, is presented. These multilayer coatings are of special interest for extreme ultraviolet lithography (EUVL). The beryllium-based multilayers investigated were Mo/Be, Ru/Be and a new material combination Mo,CiBe. The highest reflectivity achieved so far is 70% at 11.3 mn with 70 bilayers of Mo/Be. However, even though high reflectivity is very important, there are other parameters to satisfy the requirements for an EUVL production tool. Multilayer stress, thermal stability, radiation stability and long term reflectance stability are of equal or greater importance. An experimental characterization of several coatings was carried out to determine the reflectivity, stress, microstructure, and long term stability of these coatings. Theoretically calculated reflectivities are compared with experimental results for different material pairs; differences between experimental and theoretical reflectivities and bandwidths are addressed. Keywords: Extreme ultraviolet (EUV) lithography, reflective coatings, multilayer deposition, beryllium.
Date: July 30, 1999
Creator: Bajit, S.; Behymer, R. D.; Folta, J.; Mirkarimi, P. B.; Montcalm, C.; Wall, M. A. et al.
System: The UNT Digital Library
High energy density capacitors fabricated by thin film technology (open access)

High energy density capacitors fabricated by thin film technology

Low energy density in conventional capacitors severely limits efforts to miniaturize power electronics and imposes design limitations on electronics in general. We have successfully applied physical vapor deposition technology to greatly increase capacitor energy density. The high dielectric breakdown strength we have achieved in alumina thin films allows high energy density to be achieved with this moderately low dielectric constant material. The small temperature dependence of the dielectric constant, and the high reliability, high resistivity, and low dielectric loss of Al 2 O 3 , make it even more appealing. We have constructed single dielectric layer thin film capacitors and shown that they can be stacked to form multilayered structures with no loss in yield for a given capacitance. Control of film growth morphology is critical for achieving the smooth, high quality interfaces between metal and dielectric necessary for device operation at high electric fields. Most importantly, high rate deposition with extremely low particle generation is essential for achieving high energy storage at a reasonable cost. This has been achieved by reactive magnetron sputtering in which the reaction to form the dielectric oxide has been confined to the deposition surface. By this technique we have achieved a yield of over …
Date: March 30, 1999
Creator: Barbee, T W; Johnson, G W & Wagner, A V
System: The UNT Digital Library
Recent Nuclear Astrophysics Data Activities in the US (open access)

Recent Nuclear Astrophysics Data Activities in the US

Measurements in nuclear physics laboratories form the empirical foundation for new, realistic, sophisticated theoretical models of a wide variety of astrophysical systems. The predictive power of these models has, in many instances, a strong dependence on the input nuclear data, and more extensive and accurate nuclear data is required for these models than ever before. Progress in astrophysics can be aided by providing scientists with more usable, accurate, and significant amounts of nuclear data in a timely fashion in formats that can be easily incorporated into their models. A number of recent data compilations, evaluations, calculations, and disseminations that address nuclear astrophysics data needs will be described.
Date: August 30, 1999
Creator: Bardayan, D. W.; Blackmon, J. C.; Browne, E.; Firestone, R. B.; Hale, G. M.; Hoffman, R. D. et al.
System: The UNT Digital Library
Identification of micro-organisms using superconducting tunnel junctions and time-of-flight mass spectrometry (open access)

Identification of micro-organisms using superconducting tunnel junctions and time-of-flight mass spectrometry

We present time-of-flight measurements of biological material ejected from complete bacterial spores following laser irradiation. Ion impacts are registered on a microchannel plate and on a Superconducting Tunnel Junction (STJ) detector. We compare mass spectra obtained with the two detectors. The STJ has better sensitivity to massive ions and also measures the energy of each ion. We show evidence that spores of different bacillus species produce distinctive mass spectra and associate the observed mass peaks with coat proteins identified through ion-exchange extraction and gel electrophoresis.
Date: August 30, 1999
Creator: Benner, W H; Frank, M; Horn, J M; Labov, S E; Langry, K & Ullom, J
System: The UNT Digital Library
Intrinsic and extrinsic magnetic properties of the naturally layered manganites (open access)

Intrinsic and extrinsic magnetic properties of the naturally layered manganites

Structural and magnetic properties of the two-layered Ruddlesden-Popper phase SrO(La{sub 1{minus}x}Sr{sub x}MnO{sub 3}){sub 2} with x = 0.3--0.5 are highlighted. Intrinsic properties of these naturally layered manganites include a colossal magnetoresistance, a composition-dependent magnetic anisotropy, and almost no remanence. Above the Curie temperature there is a non-vanishing extrinsic magnetization attributed to intergrowths (stacking faults in the layered structure). These lattice imperfections consist of additional or missing manganite layers, as observed in transmission electron microscopy. Their role in influencing the properties of the host material is highlighted.
Date: November 30, 1999
Creator: Berger, A.; Mitchell, J. F.; Miller, D. J.; Jiang, J. S. & Bader, S. D.
System: The UNT Digital Library
R-parity-violating production of single top squarks with R-parity-conserving decays. (open access)

R-parity-violating production of single top squarks with R-parity-conserving decays.

Single-top-squark production probes R-parity-violating extensions of the minimal supersymmetric standard model though the {lambda}{sub 3ij}{double_prime} coupling. For top-squark masses in the range 180-325 GeV, and {lambda}{sub 3ij}{double_prime} > 0.02-0.06, we show that discovery of the top squark is possible with 2 fb{sup {minus}1} of integrated luminosity at run II of the Fermilab Tevatron. The bound on {lambda}{sub 3ij}{double_prime} can be reduced by up to an order of magnitude with existing data from run I, and by two orders of magnitude at run II if the top squark is not found.
Date: April 30, 1999
Creator: Berger, E. L.; Harris, B. W. & Sullivan, Z.
System: The UNT Digital Library
Detection and Location of Structural Degradation in Mechanical Systems (open access)

Detection and Location of Structural Degradation in Mechanical Systems

The investigation of a diagnostic method for detecting and locating the source of structural degradation in a mechanical system is described in this paper. The diagnostic method uses a mathematical model of the mechanical system to determine relationships between system parameters and measurable spectral features. These relationships are incorporated into a neural network, which associates measured spectral features with system parameters. Condition diagnosis is performed by presenting the neural network with measured spectral features and comparing the system parameters estimated by the neural network to previously estimated values. Changes in the estimated system parameters indicate the location and severity of degradation in the mechanical system.
Date: August 30, 1999
Creator: Blakeman, E.D.; Damiano, B. & Phillips, L.D.
System: The UNT Digital Library
Properties of UNiAlD{sub 2.1} and UNiAlH{sub 2.3}. (open access)

Properties of UNiAlD{sub 2.1} and UNiAlH{sub 2.3}.

None
Date: July 30, 1999
Creator: Bordallo, H. N.; Christianson, A.; Drulis, H.; Havela, L.; Iwasieczko, W.; Kolomiets, A. V. et al.
System: The UNT Digital Library
MASS MEASUREMENTS ALONG THE RP-PROCESS PATH. (open access)

MASS MEASUREMENTS ALONG THE RP-PROCESS PATH.

The path and termination point for the t-p-process above {sup 56}Ni is uncertain due to a lack of knowledge of nuclear properties, especially masses, near the proton drip line. To address this need we have begun a program to measure masses of nuclei along the r-p-process pathway in the A{approximately}60-80 region using {beta}-{gamma} coincidence spectroscopy. Results for {sup 71}Se are presented and a preliminary experiment for {sup 72}Br is described.
Date: August 30, 1999
Creator: Brenner, D. S.
System: The UNT Digital Library
Geometric Correction System Capabilities, Processing, and Application (open access)

Geometric Correction System Capabilities, Processing, and Application

The U.S. Department of Energy's Remote Sensing Laboratory developed the geometric correction system (GCS) as a state-of-the-art solution for removing distortions from multispectral line scanner data caused by aircraft motion. The system operates on Daedalus AADS-1268 scanner data acquired from fixed-wing and helicopter platforms. The aircraft attitude, altitude, acceleration, and location are recorded and applied to the data, thereby determining the location of the earth with respect to a given datum and projection. The GCS has yielded a positional accuracy of 0.5 meters when used with a 1-meter digital elevation model. Data at this level of accuracy are invaluable in making precise areal estimates and as input into a geographic information system. The combination of high-spatial resolution and accurate geo-rectification makes the GCS a unique tool in identifying and locating environmental conditions, finding targets of interest, and detecting changes as they occur over time.
Date: June 30, 1999
Creator: Brewster, S. B.
System: The UNT Digital Library
Modifier coordination and phosphate glass networks (open access)

Modifier coordination and phosphate glass networks

The addition of up to approximately 16 mole% Cs{sub 2}O to vitreous P{sub 2}O{sub 5} reduces the glass transition temperature (T{sub g}) by 150 K, whereas further additions up to 50 mole% produce little additional change in T{sub g}. {sup 31}P magic angle spinning nuclear magnetic resonance spectra indicate that the phosphate network is progressively dipolymerized over the entire range of compositions. The property trend is explained by a transition in the Cs{sup +} coordination environment, from isolated Cs-polyhedra below {approximately}16 mole% Cs{sub 2}O to a corner-sharing Cs-polyhedral sub-structure in the glasses with greater Cs{sub 2}O contents. This modifier transition does not occur in Al-phosphate glasses. {sup 27}Al MAS NMR spectra indicate that the average Al coordination number decreases with increasing Al{sub 2}O{sub 3} content to avoid the formation of Al-O-Al bonds in these binary phosphate glasses.
Date: November 30, 1999
Creator: Brow, R.; Click, C. A. & Alam, T. M.
System: The UNT Digital Library
Intergrowth structures in synthetic pyrochlores : implications for radiation damage effects and waste form formulation. (open access)

Intergrowth structures in synthetic pyrochlores : implications for radiation damage effects and waste form formulation.

Titanate-based ceramic waste forms are currently under development for the immobilization of excess weapons plutonium. Both Hf and Gd are added to the ceramic formulation as neutron absorbers in order to satisfy a defense-in-depth concept for the waste form. The introduction of significant amounts of hafnium may be responsible for the presence of zirconolite-2M crystals in pyrochlore-based ceramics and the formation of zirconolite lamellae within pyrochlore. The zirconolite grows epitaxially on {l_brace}111{r_brace}planes of pyrochlore. Although the zirconolite lamellae within pyrochlore are non-cubic, any volume expansion due to radiation damage in the pyrochlore should still be isotropic; in addition, the presence of these intergrowths may allow some stress relief in the ceramic.
Date: March 30, 1999
Creator: Buck, E.
System: The UNT Digital Library
Standardization of transportation classes for object-oriented deployment simulations. (open access)

Standardization of transportation classes for object-oriented deployment simulations.

Many recent efforts to integrate transportation and deployment simulations, although beneficial, have lacked a feature vital for seamless integration: a common data class representation. It is an objective of the Department of Defense (DoD) to standardize all classes used in object-oriented deployment simulations by developing a standard class attribute representation and behavior for all deployment simulations that rely on an underlying class representation. The Extensive Hierarchy and Object Representation for Transportation Simulations (EXHORT) is a collection of three hierarchies that together will constitute a standard and consistent class attribute representation and behavior that could be used directly by a large set of deployment simulations. The first hierarchy is the Transportation Class Hierarchy (TCH), which describes a significant portion of the defense transportation system; the other two deal with infrastructure and resource classes. EXHORT will allow deployment simulations to use the same set of underlying class data, ensure transparent exchanges, reduce the effort needed to integrate simulations, and permit a detailed analysis of the defense transportation system. This paper describes EXHORT's first hierarchy, the TCH, and provides a rationale for why it is a helpful tool for modeling major portions of the defense transportation system.
Date: July 30, 1999
Creator: Burke, J. F., Jr.; Howard, D. L.; Jackson, J.; Macal, C. M.; Nevins, M. R. & Van Groningen, C. N.
System: The UNT Digital Library