Binary Microlensing Events from the MACHO Project (open access)

Binary Microlensing Events from the MACHO Project

This article presents the light curves of 21 gravitational microlensing events from the first six years of the MACHO Project gravitational microlensing survey that are likely examples of lensing by binary systems.
Date: March 27, 2000
Creator: Alcock, C.; Allsman, R. A.; Alves, D.; Axelrod, T. S.; Baines, D.; Becker, A. C. et al.
System: The UNT Digital Library
Heavy Quarks (open access)

Heavy Quarks

None
Date: March 27, 2006
Creator: Baines, J.; Baranov, S. P.; Behnke, O.; Bracinfk, J.; Cacciari, M.; Corradi, M. et al.
System: The UNT Digital Library
Mastering Layers (open access)

Mastering Layers

None
Date: March 27, 2007
Creator: Beer, G.
System: The UNT Digital Library
Flat-Field Grating Spectrometer for High-Resolution Soft X-Ray and EUV Measurements on an Electron Beam Ion Trap (open access)

Flat-Field Grating Spectrometer for High-Resolution Soft X-Ray and EUV Measurements on an Electron Beam Ion Trap

A R = 44.3 m grazing-incidence grating spectrometer has been implemented on the Livermore electron beam ion traps for high-resolution measurements in the soft x-ray and extreme ultraviolet region spanning from below 10 Angstrom up to 50 Angstrom. The instrument uses a grating with variable line spacing (about 2400 l/mm) for a flat field of view. Spectra are recorded with a back-illuminated charge-coupled device detector. The new instrument greatly improves upon the resolution achieved with existing grating spectrometers and complements crystal spectrometers at the shorter wavelengths both in terms of wavelength coverage and polarization independent reflectivity response.
Date: March 27, 2004
Creator: Beiersdorfer, P.; Magee, E.; Trabert, E.; Chen, H.; Lepson, J. K.; Gu, M. F. et al.
System: The UNT Digital Library
Electron Bunch Length Measurements in the E-167 Plasma Wakefield Experiment (open access)

Electron Bunch Length Measurements in the E-167 Plasma Wakefield Experiment

Bunch length is of prime importance to beam driven plasma wakefield acceleration experiments due to its inverse relationship to the amplitude of the accelerating wake. We present here a summary of work done by the E167 collaboration measuring the SLAC ultra-short bunches via autocorrelation of coherent transition radiation. We have studied material transmission properties and improved our autocorrelation traces using materials with better spectral characteristics.
Date: March 27, 2007
Creator: Blumenfeld, I.; Auerbach, D.; Berry, M.; Clayton, C. E.; Decker, F. J.; Hogan, M. J. et al.
System: The UNT Digital Library
Estimation of fatigue crack initiation in austenitic stainless steels in LWR environments. (open access)

Estimation of fatigue crack initiation in austenitic stainless steels in LWR environments.

None
Date: March 27, 2002
Creator: Chopra, O. K.
System: The UNT Digital Library
Mechanism of fatigue crack initiation in austenitic stainless steels in LWR environments. (open access)

Mechanism of fatigue crack initiation in austenitic stainless steels in LWR environments.

This paper examines the mechanism of fatigue crack initiation in austenitic stainless steels (SSs) in light water reactor (LWR) coolant environments. The effects of key material and loading variables, such as strain amplitude, strain rate, temperature, level of dissolved oxygen in water, and material heat treatment on the fatigue lives of wrought and cast austenitic SSs in air and LWR environments have been evaluated. The influence of reactor coolant environments on the formation and growth of fatigue cracks in polished smooth SS specimens is discussed. Crack length as a function of fatigue cycles was determined in air and LWR environments. The results indicate that decreased fatigue lives of these steels are caused primarily by the effects of the environment on the growth of cracks <200 {micro}m and, to a lesser extent, on enhanced growth rates of longer cracks. A detailed metallographic examination of fatigue test specimens was performed to characterize the fracture morphology. Exploratory fatigue tests were conducted to enhance our understanding of the effects of surface micropits or minor differences in the surface oxide on fatigue crack initiation.
Date: March 27, 2002
Creator: Chopra, O. K.
System: The UNT Digital Library
Externally Dispersed Interferometry for Precision Radial Velocimetry (open access)

Externally Dispersed Interferometry for Precision Radial Velocimetry

Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response to a Doppler shift. Moire patterns are broader than the underlying spectral features and more easily survive spectrograph blurring and common distortions. Thus, the EDI technique allows lower resolution spectrographs having relaxed optical tolerances (and therefore higher throughput) to return high precision velocity measurements, which otherwise would be imprecise for the spectrograph alone.
Date: March 27, 2007
Creator: Erskine, D. J.; Muterspaugh, M. W.; Edelstein, J.; Lloyd, J.; Herter, T.; Feuerstein, W. M. et al.
System: The UNT Digital Library
Finite Elements approach for Density Functional Theory calculations on locally refined meshes (open access)

Finite Elements approach for Density Functional Theory calculations on locally refined meshes

We present a quadratic Finite Elements approach to discretize the Kohn-Sham equations on structured non-uniform meshes. A multigrid FAC preconditioner is proposed to iteratively solve the equations by an accelerated steepest descent scheme. The method was implemented using SAMRAI, a parallel software infrastructure for general AMR applications. Examples of applications to small nanoclusters calculations are presented.
Date: March 27, 2006
Creator: Fattebert, J; Hornung, R D & Wissink, A M
System: The UNT Digital Library
Supernova 2002ap: the first month (open access)

Supernova 2002ap: the first month

This article reports the results of the first month of an intensive photometric and spectroscopic monitoring campaign of Supernova 2002ap.
Date: March 27, 2002
Creator: Gal-Yam, Avishay; Ofek, Efran & Shemmer, Ohad
System: The UNT Digital Library
Use of a genome-wide approach to identify new genes that control resistance of saccharomyces cerevisiae to ionizing radiation (open access)

Use of a genome-wide approach to identify new genes that control resistance of saccharomyces cerevisiae to ionizing radiation

None
Date: March 27, 2003
Creator: Game, John C.; Birrell, Geoff W.; Brown, James A.; Shibata, Toru; Baccari, Clelia; Chu, Angela M. et al.
System: The UNT Digital Library
A Review of the Properties of Nb3Sn and Their Variation with A15Composition, Morphology and Strain State (open access)

A Review of the Properties of Nb3Sn and Their Variation with A15Composition, Morphology and Strain State

Significant efforts can be found throughout the literature to optimize the current carrying capacity of Nb{sub 3}Sn superconducting wires. The achievable transport current density in wires depends on the A15 composition, morphology and strain state. The A15 sections in wires contain, due to compositional inhomogeneities resulting from solid state diffusion A15 formation reactions, a distribution of superconducting properties. The A15 grain size can be different from wire to wire and is also not necessarily homogeneous across the A15 regions. Strain is always present in composite wires, and the strain state changes as a result of thermal contraction differences and Lorentz forces in magnet systems. To optimize the transport properties it is thus required to identify how composition, grain size and strain state influence the superconducting properties. This is not accurately possible in inhomogeneous and spatially complex systems such as wires. This article therefore gives an overview of the available literature on simplified, well defined(quasi--)homogeneous laboratory samples. After more than 50 years of research on superconductivity in Nb{sub 3}Sn, a significant amount of results are available, but these are scattered over a multitude of publications. Two reviews exist on the basic properties of A15 materials in general, but no specific review …
Date: March 27, 2006
Creator: Godeke, Arno
System: The UNT Digital Library
The Flat Decay Phase in the Early X-Ray Afterglows of Swift GRBs (open access)

The Flat Decay Phase in the Early X-Ray Afterglows of Swift GRBs

Many Swift GRBs show an early phase of shallow decay in their X-ray afterglows, lasting from t {approx} 10{sup 2.5} s to {approx} 10{sup 4} s after the GRB, where the flux decays as {approx} t{sup -0.2} - t{sup -0.8}. This is perhaps the most mysterious of the new features discovered by Swift in the early X-ray afterglow, since it is still not clear what causes it. I discuss different possible explanations for this surprising new discovery, as well as their potential implications for the gamma-ray efficiency, the afterglow kinetic energy, and perhaps even for the physics of collisionless relativistic shocks.
Date: March 27, 2007
Creator: Granot, Jonathan
System: The UNT Digital Library
Automated analysis of failure event data (open access)

Automated analysis of failure event data

This paper focuses on fully automated analysis of failure event data in the concept and early development stage of a semiconductor-manufacturing tool. In addition to presenting a wide range of statistical and machine-specific performance information, algorithms have been developed to examine reliability growth and to identify major contributors to unreliability. These capabilities are being implemented in a new software package called Reliadigm. When coupled with additional input regarding repair times and parts availability, the analysis software also provides spare parts inventory optimization based on genetic optimization methods. The type of question to be answered is: If this tool were placed with a customer for beta testing, what would be the optimal spares kit to meet equipment reliability goals for the lowest cost? The new algorithms are implemented in Windows{reg_sign} software and are easy to apply. This paper presents a preliminary analysis of failure event data from three IDEA machines currently in development. The paper also includes an optimal spare parts kit analysis.
Date: March 27, 2000
Creator: Hennessy, Corey; Freerks, Fred; Campbell, James E. & Thompson, Bruce M.
System: The UNT Digital Library
The LLNL Cluster Tool (open access)

The LLNL Cluster Tool

{lg_bullet} The Cluster Tool -is a set of linked vacuum chambers -can deposit multiple layers of metal and metal oxides {lg_bullet} Each layer can be deposited without breaking vacuum {lg_bullet} Shadow masks can give each layer a different pattern {lg_bullet} The Cluster Tool will be operational in April
Date: March 27, 2007
Creator: Hunter, S L
System: The UNT Digital Library
Building Public Confidence in Nuclear Activities (open access)

Building Public Confidence in Nuclear Activities

Achieving public acceptance has become a central issue in discussions regarding the future of nuclear power and associated nuclear activities. Effective public communication and public participation are often put forward as the key building blocks in garnering public acceptance. A recent international workshop in Finland provided insights into other features that might also be important to building and sustaining public confidence in nuclear activities. The workshop was held in Finland in close cooperation with Finnish stakeholders. This was most appropriate because of the recent successes in achieving positive decisions at the municipal, governmental, and Parliamentary levels, allowing the Finnish high-level radioactive waste repository program to proceed, including the identification and approval of a proposed candidate repository site. Much of the workshop discussion appropriately focused on the roles of public participation and public communications in building public confidence. It was clear that well constructed and implemented programs of public involvement and communication and a sense of fairness were essential in building the extent of public confidence needed to allow the repository program in Finland to proceed. It was also clear that there were a number of other elements beyond public involvement that contributed substantially to the success in Finland to date. …
Date: March 27, 2002
Creator: Isaacs, T
System: The UNT Digital Library
''A Wavelet Optimized Adaptive, High-Order, Multi-Domain Method for Parallel Architectures'' (open access)

''A Wavelet Optimized Adaptive, High-Order, Multi-Domain Method for Parallel Architectures''

Constructing numerical schemes which are both adaptive and suitable for parallel architectures is very challenging. The challenge lies in the need to maintain a balanced load across the processing elements using a method that is both efficient and scalable. Here we propose a method which is adaptive, load balanced, absolutely efficient and scalable offering significant speedup over lower order adaptive schemes. The ability of wavelets to accurately and efficiently represent functions with localized features has spawned intensive research into applying wavelets for the solution of partial differential equations with the promise of significantly reducing the necessary computational effort and memory requirements. Traditionally, this effort has been centered around using wavelets as an orthogonal and complete basis, spanning a space in which to seek approximate solutions satisfying the equation in a Galerkin sense. Besides from the well known difficulties associated with such an approach for non-linear problems, one is also faced with the problem of dealing with non-trivial boundary conditions in an accurate and stable manner. Such restrictions on the applicability of wavelet based methods for the solution of problems of more general interest have, in recent years, induced significant interest into grid-based collocation wavelet methods, with various different approaches being …
Date: March 27, 2001
Creator: Jameson, L M; Johnson, J R & Hesthaven, J S
System: The UNT Digital Library
Rotational hysteresis of exchange-spring magnets. (open access)

Rotational hysteresis of exchange-spring magnets.

We highlight our experimental studies and micromagnetic simulations of the rotational hysteresis in exchange-spring magnets. Magneto-optical imaging and torque magnetometry measurements for SmCo/Fe exchange-spring films with uniaxial in-plane anisotropy show that the magnetization rotation created in the magnetically soft Fe layer by a rotating magnetic field is hysteretic. The rotational hysteresis is due to the reversal of the chirality of the spin spiral structure. Micromagnetic simulations reveal two reversal modes of the chirality, one at low fields due to an in-plane untwisting of the spiral, and the other, at high fields, due to an out-of-plane fanning of the spiral.
Date: March 27, 2002
Creator: Jiang, J. S.; Bader, S. D.; Kaper, H.; Leaf, G. K.; Shull, R. D.; Shapiro, A. J. et al.
System: The UNT Digital Library
Separation of Yeast Cells from MS2 Viruses Using Acoustic Radiation Force (open access)

Separation of Yeast Cells from MS2 Viruses Using Acoustic Radiation Force

We report a rapid and robust separation of Saccharomyces cerevisiae and MS2 bacteriophage using acoustic focusing in a microfluidic device. A piezoelectric transducer (PZT) generates acoustic standing waves in the microchannel. These standing waves induce acoustic radiation force fields that direct microparticles towards the nodes (i.e., pressure minima) or the anti-nodes (i.e., pressure maxima) of the standing waves depending on the relative compressidensity between the particle and the suspending liquid.[1] For particles larger than 2 {micro}m, the transverse velocities generated by these force fields enable continuous, high throughput separation. Extensive work in the last decade [2-4] has demonstrated acoustic focusing for manipulating microparticles or biological samples in microfluidic devices. This prior work has primarily focused on experimental realization of acoustic focusing without modeling or with limited one-dimensional modeling estimates. We recently developed a finite element modeling tool to predict the two-dimensional acoustic radiation force field perpendicular to the flow direction in microfluidic devices.[1] Here we compare results from this model with experimental parametric studies including variations of the PZT driving frequencies and voltages as well as various particle sizes and compressidensities. These experimental parametric studies also provide insight into the development of an adjustable 'virtual' pore-size filter as well as …
Date: March 27, 2008
Creator: Jung, B.; Fisher, K.; Ness, K.; Rose, K. A. & Mariella, R. P., Jr.
System: The UNT Digital Library
SHIELDING ANALYSIS FOR X-RAY SOURCES GENERATED IN TARGET CHAMBER OF THE NATIONAL IGNITION FACILITY (open access)

SHIELDING ANALYSIS FOR X-RAY SOURCES GENERATED IN TARGET CHAMBER OF THE NATIONAL IGNITION FACILITY

Prompt doses from x-rays generated as result of laser beam interaction with target material are calculated at different locations inside the National Ignition Facility (NIF). The maximum dose outside a Target Chamber diagnostic port is {approx} 1 rem for a shot utilizing the 192 laser beams and 1.8 MJ of laser energy. The dose during a single bundle shot (8 laser beams) drops to {approx} 40 mrem. Doses calculated outside the Target Bay doors and inside the Switchyards (except for the 17 ft.-6 in. level) range from a fraction of mrem to about 11 mrem for 192 beams, and scales down proportionally with smaller number of beams. At the 17ft.-6 in. level, two diagnostic ports are directly facing two of the Target Bay doors and the maximum doses outside the doors are 51 and 15.5 mrem, respectively. Shielding each of the two Target Bay doors with 1/4 in. Pb reduces the dose by factor of fifty. One or two bundle shots (8 to 16 laser beams) present a small hazard to personnel in the Switchyards.
Date: March 27, 2008
Creator: Khater, H Y; Brereton, S J & Singh, M S
System: The UNT Digital Library
Security services negotiation through OAM cells (open access)

Security services negotiation through OAM cells

As described in contribution AF99-0335, it is interesting that new security services and mechanisms are allowed to be negotiated during a connection in progress. To do that, new ''negotiation OAM cells'' dedicated to security should be defined, as well as some acknowledgment cells allowing negotiation OAM cells to be exchanged reliably. Remarks which were given at the New Orleans meeting regarding those cell formats are taken into account. This contribution presents some baseline text describing the format of the negotiation and acknowledgment cells, and the using of those cells. All the modifications brought to the specifications are reversible using the Word tools.
Date: March 27, 2000
Creator: LAURENT,MARYLINE & TARMAN,THOMAS D.
System: The UNT Digital Library
Transient Heat Transfer Model for Srs Waste Tank Operations (open access)

Transient Heat Transfer Model for Srs Waste Tank Operations

A transient heat balance model was developed to assess the impact of a Submersible Mixer Pump (SMP) on waste temperature during the process of waste mixing and removal for the Type-I Savannah River Site (SRS) tanks. The model results will be mainly used to determine the SMP design impacts on the waste tank temperature during operations and to develop a specification for a new SMP design to replace existing long-shaft mixer pumps used during waste removal. The model will also be used to provide input to the operation planning. This planning will be used as input to pump run duration in order to maintain temperature requirements within the tank during SMP operation. The analysis model took a parametric approach. A series of the modeling analyses was performed to examine how submersible mixer pumps affect tank temperature during waste removal operation in the Type-I tank. The model domain included radioactive decay heat load, two SMP's, and one Submersible Transfer Pump (STP) as heat source terms. The present model was benchmarked against the test data obtained by the tank measurement to examine the quantitative thermal response of the tank and to establish the reference conditions of the operating variables under no SMP …
Date: March 27, 2007
Creator: Lee, S. & Richard Dimenna, R.
System: The UNT Digital Library
SuperLU{_}DIST: A scalable distributed-memory sparse direct solver for unsymmetric linear systems (open access)

SuperLU{_}DIST: A scalable distributed-memory sparse direct solver for unsymmetric linear systems

In this paper, we present the main algorithmic features in the software package SuperLU{_}DIST, a distributed-memory sparse direct solver for large sets of linear equations. We give in detail our parallelization strategies, with focus on scalability issues, and demonstrate the parallel performance and scalability on current machines. The solver is based on sparse Gaussian elimination, with an innovative static pivoting strategy proposed earlier by the authors. The main advantage of static pivoting over classical partial pivoting is that it permits a priori determination of data structures and communication pattern for sparse Gaussian elimination, which makes it more scalable on distributed memory machines. Based on this a priori knowledge, we designed highly parallel and scalable algorithms for both LU decomposition and triangular solve and we show that they are suitable for large-scale distributed memory machines.
Date: March 27, 2002
Creator: Li, Xiaoye S. & Demmel, James W.
System: The UNT Digital Library
Finite Element Output Bounds for Hyperbolic Problems (open access)

Finite Element Output Bounds for Hyperbolic Problems

We propose a Neumann-subproblem a posteriori finite element error bound technique for linear stationary scalar advection problems. The method is similar in many respects to the previous output bound technique developed for elliptic problems. In the new approach, however, the primal residual is enhanced with a streamline diffusion term. We first formulate the bound algorithm, with particular emphasis on the proof of the bounding properties; then, we provide numerical results for an illustrative example.
Date: March 27, 2000
Creator: Machiels, L.
System: The UNT Digital Library