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OBSERVATION OF DIPOLAR FERROMAGNETISM BY TEM TECHNIQUES.
Magnetostatic interactions play a central role in determining the magnetic response of an array of patterned magnetic elements or magnetized nanoparticles of given shape. The Fourier space approach recently introduced for the analytical computation of the demagnetizing tensor, field and energy for particles of arbitrary shape [1], has been recently extended to cover interactions between elements [2]. The main achievement has been the definition of a generalized dipole-dipole interaction for cylindrical objects, which takes into account the influence of shape anisotropy without resorting to,any kind of approximations [3]. Once the interaction energy is available, it becomes possible to evaluate the minimum energy state of the system for a given set of external parameters (such as applied field, aspect ratio, distance between elements). It turns out that, below a critical combination of aspect ratios and distances, the system undergoes a phase transition, changing abruptly from a closure domain state, with zero net magnetization, to a dipolar ferromagnetic state with a net magnetization which depends on the interaction strength between the elements. In order to observe this phenomenon by TEM, it is necessary to estimate the feasibility of the experiment by a series of simulations. Figure 1 shows the electron optical phase …
Date:
August 1, 2004
Creator:
BELEGGIA, M. ZHU,Y. TANDON,S. ET AL.
Object Type:
Article
System:
The UNT Digital Library
ADVANCED DATA PROCESSING FOR VOLUMETRIC COMPUTED TOMOGRAPHY DATA
Computed tomography (CT) has long been used by industry as a non-destructive evaluation technique for discovering flaws in parts before their use. Traditional linear array computed tomography systems acquired data at a rate that could be reconstructed simultaneously with data acquisition. With new area detectors, the data rate of acquisition has increased exponentially, and the reconstruction algorithm does not scale linearly with increased data. FlashCT DPS (Flat Panel Amorphous Silicon High Resolution Computed Tomography, Data Processing System) is a software package developed by M. Sheats, and A. Davis at LANL to meet the data processing demands of new flat panel array computed tomography. FlashCT--DPS combines several features unique to industrial computed tomography systems. It addresses traditional usability problems by providing an intuitive graphical user interface and powerful analysis tools. It includes the three major CT reconstruction algorithms: parallel backprojection, fan beam resorting, and Feldkamp cone beam. It also provides visualization tools for examination of data after processing. Finally, it is able to perform distributed data reconstruction with a near linear speed increase as a function of the number of processors used. Additionally, utility programs have been developed to support project editing and computing cluster management for the FlashCT system. FlashCT--DPS …
Date:
August 1, 2001
Creator:
BERKELEY, M. SHEATS - UC
Object Type:
Report
System:
The UNT Digital Library
A Risk Assessment Methodology for Physical Security
None
Date:
August 1, 2000
Creator:
BIRINGER,BETTY E.
Object Type:
Article
System:
The UNT Digital Library
OPTIMIZING THROUGH CO-EVOLUTIONARY AVALANCHES
We explore a new general-purpose heuristic for finding high-quality solutions to hard optimization problems. The method, called extremal optimization, is inspired by ''self-organized critically,'' a concept introduced to describe emergent complexity in many physical systems. In contrast to Genetic Algorithms which operate on an entire ''gene-pool'' of possible solutions, extremal optimization successively replaces extremely undesirable elements of a sub-optimal solution with new, random ones. Large fluctuations, called ''avalanches,'' ensue that efficiently explore many local optima. Drawing upon models used to simulate far-from-equilibrium dynamics, extremal optimization complements approximation methods inspired by equilibrium statistical physics, such as simulated annealing. With only one adjustable parameter, its performance has proved competitive with more elaborate methods, especially near phase transitions. Those phase transitions are found in the parameter space of most optimization problems, and have recently been conjectured to be the origin of some of the hardest instances in computational complexity. We will demonstrate how extremal optimization can be implemented for a variety of combinatorial optimization problems. We believe that extremal optimization will be a useful tool in the investigation of phase transitions in combinatorial optimization problems, hence valuable in elucidating the origin of computational complexity.
Date:
August 1, 2000
Creator:
BOETTCHER, S. & PERCUS, A.
Object Type:
Article
System:
The UNT Digital Library
DOE-EM SNF Transportation System
None
Date:
August 1, 2000
Creator:
BREIVIK,NICOLE L. & AMMERMAN,DOUGLAS J.
Object Type:
Report
System:
The UNT Digital Library
LESSONS FROM HADRON PHENOMENOLOGY
Meson spectra can be well approximated by a specific form of a nonlinear Regge trajectory which is consistent with a finite number of bound states. This may have important consequences for experiment, and may be a hint for the theory.
Date:
August 1, 2000
Creator:
BRISUDOVA, M.; BUAKOVSKY, L. & GOLDMAN, T.
Object Type:
Article
System:
The UNT Digital Library
TEMPERATURE MEASUREMENTS COLLECTED FROM AN INSTRUMENTED VAN IN SALT LAKE CITY, UTAH AS PART OF URBAN 2000
Measurements of temperature and position were collected during the night from an instrumented van on routes through Salt Lake City and the rural outskirts. The measurements were taken as part of the Department of Energy Chemical and Biological National Security Program URBAN 2 Field Experiment conducted in October 2000 (Shinn et al., 2000 and Allwine et al., 2001a). The instrumented van was driven over three primary routes, two including downtown, residential, and ''rural'' areas and a third that went by a line of permanently fixed temperature probes (Allwine et al., 2001b) for cross-checking purposes. Each route took from 45 to 60 minutes to complete. Based on four nights of data, initial analyses indicate that there was a temperature difference of 2-5 C between the urban core and nearby ''rural'' areas. Analyses also suggest that there were significant fine scale temperature differences over distances of tens of meters within the city and in the nearby rural areas. The temperature measurements that were collected are intended to supplement the meteorological measurements taken during the URBAN2000 Field Experiment, to assess the importance of the urban heat island phenomenon in Salt Lake City, and to test the urban canopy parameterizations that have been developed …
Date:
August 1, 2001
Creator:
BROWN, M. J. & PARDYJAK, E. R.
Object Type:
Article
System:
The UNT Digital Library
PRELIMINARY PROJECT PLAN FOR LANSCE INTEGRATED FLIGHT PATHS 11A, 11B, 12, and 13
This Preliminary Project Plan Summarizes the Technical, Cost, and Schedule baselines for an integrated approach to developing several flight paths at the Manual Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center. For example, the cost estimate is intended to serve only as a rough order of magnitude assessment of the cost that might be incurred as the flight paths are developed. Further refinement of the requirements and interfaces for each beamline will permit additional refinement and confidence in the accuracy of all three baselines (Technical, Cost, Schedule).
Date:
August 1, 2000
Creator:
BULTMAN, D. H. & CORP., D. WEINACHT - AIRES
Object Type:
Report
System:
The UNT Digital Library
DEVELOPMENT OF CO2 WAVEGUIDE LASERS AND LASER TECHNOLOGY FOR REMOTE SENSING
None
Date:
August 1, 2001
Creator:
BUSCH, G. E.; HEWITT, C. J. & AL, ET
Object Type:
Article
System:
The UNT Digital Library
Washington International Renewable Energy Conference 2008 Pledges: Methodology and Assumptions Summary
The 2008 Washington International Renewable Energy Conference (WIREC) was held in Washington, D.C., from March 4-6, 2008, and involved nearly 9,000 people from 125 countries. The event brought together worldwide leaders in renewable energy (RE) from governments, international organizations, nongovernmental organizations, and the private sector to discuss the role that renewables can play in alleviating poverty, growing economies, and passing on a healthy planet to future generations. The conference concluded with more than 140 governments, international organizations, and private-sector representatives pledging to advance the uptake of renewable energy. The U.S. government authorized the National Renewable Energy Laboratory (NREL) to estimate the carbon dioxide (CO2) savings that would result from the pledges made at the 2008 conference. This report describes the methodology and assumptions used by NREL in quantifying the potential CO2 reductions derived from those pledges.
Date:
August 1, 2008
Creator:
Babiuch, B.; Bilello, D. E.; Cowlin, S. C.; Mann, M. & Wise, A.
Object Type:
Report
System:
The UNT Digital Library
Global situational awareness and early warning of high-consequence climate change.
Global monitoring systems that have high spatial and temporal resolution, with long observational baselines, are needed to provide situational awareness of the Earth's climate system. Continuous monitoring is required for early warning of high-consequence climate change and to help anticipate and minimize the threat. Global climate has changed abruptly in the past and will almost certainly do so again, even in the absence of anthropogenic interference. It is possible that the Earth's climate could change dramatically and suddenly within a few years. An unexpected loss of climate stability would be equivalent to the failure of an engineered system on a grand scale, and would affect billions of people by causing agricultural, economic, and environmental collapses that would cascade throughout the world. The probability of such an abrupt change happening in the near future may be small, but it is nonzero. Because the consequences would be catastrophic, we argue that the problem should be treated with science-informed engineering conservatism, which focuses on various ways a system can fail and emphasizes inspection and early detection. Such an approach will require high-fidelity continuous global monitoring, informed by scientific modeling.
Date:
August 1, 2009
Creator:
Backus, George A.; Carr, Martin J. & Boslough, Mark Bruce Elrick
Object Type:
Report
System:
The UNT Digital Library
Calculations of precursor propagation in dispersive dielectrics.
The present study is a numerical investigation of the propagation of electromagnetic transients in dispersive media. It considers propagation in water using Debye and composite Rocard-Powles-Lorentz models for the complex permittivity. The study addresses this question: For practical transmitted spectra, does precursor propagation provide any features that can be used to advantage over conventional signal propagation in models of dispersive media of interest? A companion experimental study is currently in progress that will attempt to measure the effects studied here.
Date:
August 1, 2003
Creator:
Bacon, Larry Donald
Object Type:
Report
System:
The UNT Digital Library
Light Meson Radial Regge Trajectories
A new physical mechanism is suggested to explain the universal depletion of high meson excitations. It takes into account the appearance of holes inside the string world sheet due to q{bar q} pair creation when the length of the string exceeds the critical value R{sub 1} {approx_equal} 1.4 fm. It is argued that a delicate balance between large N{sub c} loop suppression and a favorable gain in the action, produced by holes, creates a new metastable (predecay) stage with a renormalized string tension which now depends on the separation r. This results in smaller values of the slope of the radial Regge trajectories, in good agreement with the analysis of experimental data in references.
Date:
August 1, 2002
Creator:
Badalian, A. M.; Bakker, B. L. G. & Simonov, Yu. A.
Object Type:
Article
System:
The UNT Digital Library
Tensor-Krylov methods for solving large-scale systems of nonlinear equations.
This paper develops and investigates iterative tensor methods for solving large-scale systems of nonlinear equations. Direct tensor methods for nonlinear equations have performed especially well on small, dense problems where the Jacobian matrix at the solution is singular or ill-conditioned, which may occur when approaching turning points, for example. This research extends direct tensor methods to large-scale problems by developing three tensor-Krylov methods that base each iteration upon a linear model augmented with a limited second-order term, which provides information lacking in a (nearly) singular Jacobian. The advantage of the new tensor-Krylov methods over existing large-scale tensor methods is their ability to solve the local tensor model to a specified accuracy, which produces a more accurate tensor step. The performance of these methods in comparison to Newton-GMRES and tensor-GMRES is explored on three Navier-Stokes fluid flow problems. The numerical results provide evidence that tensor-Krylov methods are generally more robust and more efficient than Newton-GMRES on some important and difficult problems. In addition, the results show that the new tensor-Krylov methods and tensor- GMRES each perform better in certain situations.
Date:
August 1, 2004
Creator:
Bader, Brett William
Object Type:
Report
System:
The UNT Digital Library
A reclusive kind of science
This article is a review of Stephen Wolfram's book ''A New Kind of Science''
Date:
August 1, 2002
Creator:
Bailey, David H.
Object Type:
Article
System:
The UNT Digital Library
Oak Ridge Y-12 Plant Emergency Action Level (EAL) Process
This report establishes requirements and standard methods for the development and maintenance of the Emergency Action Level (EAL) Process used by all lead and event contractors for emergency planning and preparedness. The EAL process ensures a technically defensible approach to emergency categorization/classification in accordance with DOE Order 151.1. The instructions provided in this document include methods and requirements for the development and approval of the EAL process. EALs are developed to cover events inside and outside the Y-12 Plant and to allow the Emergency Response Organization (ERO) to classify or reclassify events promptly based on specific indicators. This report is divided into the following 11 subsections: (1) EAL Process, (2) Categorization/Classification System for Operational Emergencies, (3) Development of EALs, (4) Barrier Analysis for EALs, (5) Symptom-Based and Event-Based EALs, (6) Other Considerations, (7) Integration of EALs with Normal and Off-Normal Operations, (8) EAL Manual, (9) Testing EALs for Completeness, (10) Training and Implementation of EALs, and (11) Configuration Management.
Date:
August 1, 2000
Creator:
Bailiff, E. G. & Bolling, J. D.
Object Type:
Report
System:
The UNT Digital Library
Oklahoma Firefighter (Oklahoma City, Okla.), Vol. 23, No. 6, Ed. 1 Tuesday, August 1, 2006
Monthly periodical from Oklahoma City, Oklahoma published by and for members of the Oklahoma State Firefighters Association that includes news and information along with advertising.
Date:
August 1, 2006
Creator:
Bain, Chris
Object Type:
Journal/Magazine/Newsletter
System:
The Gateway to Oklahoma History
Oklahoma Firefighter (Oklahoma City, Okla.), Vol. 24, No. 6, Ed. 1 Wednesday, August 1, 2007
Monthly periodical from Oklahoma City, Oklahoma published by and for members of the Oklahoma State Firefighters Association that includes news and information along with advertising.
Date:
August 1, 2007
Creator:
Bain, Chris
Object Type:
Journal/Magazine/Newsletter
System:
The Gateway to Oklahoma History
Oklahoma Firefighter (Oklahoma City, Okla.), Vol. 25, No. 6, Ed. 1 Friday, August 1, 2008
Monthly periodical from Oklahoma City, Oklahoma published by and for members of the Oklahoma State Firefighters Association that includes news and information along with advertising.
Date:
August 1, 2008
Creator:
Bain, Chris
Object Type:
Journal/Magazine/Newsletter
System:
The Gateway to Oklahoma History
Oklahoma Firefighter (Oklahoma City, Okla.), Vol. 26, No. 6, Ed. 1 Saturday, August 1, 2009
Monthly periodical from Oklahoma City, Oklahoma published by and for members of the Oklahoma State Firefighters Association that includes news and information along with advertising.
Date:
August 1, 2009
Creator:
Bain, Chris
Object Type:
Journal/Magazine/Newsletter
System:
The Gateway to Oklahoma History
Planning for Site Transition to Long-Term Stewardship: Identification of Requirements and Issues
A systematic methodology is presented and applied for the identification of requirements and issues pertaining to the planning for, and transition to, long term stewardship (LTS). The method has been applied to three of the twelve identified LTS functions. The results of the application of the methodology to contaminated and uncontaminated federal real property in those three functions are presented. The issues that could be seen as impediments to the implementation of LTS are also identified for the three areas under consideration. The identified requirements are significant and in some cases complex to implement. It is clear that early and careful planning is required in all circumstances.
Date:
August 1, 2002
Creator:
Banaee, Jila
Object Type:
Article
System:
The UNT Digital Library
Oxygen Transport Ceramic Membranes
None
Date:
August 1, 2003
Creator:
Bandopadhyay, S. & Nagabhushana, N.
Object Type:
Report
System:
The UNT Digital Library
Oxygen Transport Ceramic Membranes
The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the previous research, the reference point of oxygen occupancy was determined and verified. In the current research, the oxygen occupancy was investigated at 1200 C as a function of oxygen activity and compared with that at 1000 C. The cause of bumps at about 200 C was also investigated by using different heating and cooling rates during TGA. The fracture toughness of LSFT and dual phase membranes at room temperature is an important mechanical property. Vicker's indentation method was used to evaluate this toughness. Through this technique, a K{sub Ic} (Mode-I Fracture Toughness) value is attained by means of semi-empirical correlations between the indentation load and the length of the cracks emanating from the corresponding Vickers indentation impression. In the present investigation, crack propagation behavior was extensively analyzed in order to understand the strengthening mechanisms involved in the non-transforming La based ceramic composites. Cracks were generated using Vicker's indenter and used to identify and evaluate the toughening mechanisms involved. Preliminary results of an electron microscopy study of the origin of …
Date:
August 1, 2005
Creator:
Bandopadhyay, S.; Nithyanantham, T.; Zhou, X.-D; Sin, Y-W.; Anderson, H.U.; Jacobson, Alan et al.
Object Type:
Report
System:
The UNT Digital Library
Applying EVM principles to Tevatron Beam Position Monitor Project
At Fermi National Accelerator Laboratory (Fermilab), the Tevatron high energy particle collider must meet the increasing scientific demand of higher beam luminosity. To achieve this higher luminosity goal, U. S. Department of Energy (DOE) sponsored a major upgrade of capabilities of Fermilab's accelerator complex that spans five years and costs over fifty million dollars. Tevatron Beam Position Monitor (BPM) system upgrade is a part of this project, generally called RunII upgrade project. Since the purpose of the Tevatron collider is to detect the smashing of proton and anti-protons orbiting the circular accelerator in opposite directions, capability to detect positions of both protons and antiprotons at a high resolution level is a desirable functionality of the monitoring system. The original system was installed during early 1980s, along with the original construction of the Tevatron. However, electronic technology available in 1980s did not allow for the detection of significantly smaller resolution of antiprotons. The objective of the upgrade project is to replace the existing BPM system with a new system utilizing capabilities of modern electronics enhanced by a front-end software driven by a real-time operating software. The new BPM system is designed to detect both protons and antiprotons with increased resolution of …
Date:
August 1, 2005
Creator:
Banerjee, Bakul
Object Type:
Article
System:
The UNT Digital Library