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5,542 Matching Results
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More than just wires : applying complexity theory to communications network assurance.
Complexity Theory is the study of order within otherwise chaotic systems (Holland, 1999). Complexity Theory often focuses on Complex Adaptive Systems (CAS). A CAS is a system of components that interact and reproduce while adapting to their environment. A CAS consists of large numbers of components that are diverse in both form and capability. A CAS exhibits unstable coherence in spite of constant disruptions and a lack of central planning. Large-scale, interconnected infrastructures such as communication networks are CAS. These infrastructures are vastly more dynamic than their predecessors. Such infrastructures consist of a large number of components and participants that are diverse in both form and capability. Furthermore, these infrastructures exhibit unstable coherence in spite of constant disruptions and a lack of central planning. Viewing large-scale, interconnected infrastructures with complex physical architectures, such as communication networks, as CAS can provide many new insights (Bower and Bunn, 2000; North, 2000a, 2000b, and 2001). The CAS approach emphasizes the specific evolution of integrated infrastructures and their participants' behavior, not just simple trends or end states. The adaptation of the infrastructure participants to changing conditions is paramount. Also, the effects of random events and uncertainty are explicitly considered. One powerful computational approach to …
Date:
September 5, 2002
Creator:
North, M.; Macal, C.; Thomas, W. H.; Miller, D. & Peerenboom, J.
Object Type:
Article
System:
The UNT Digital Library
The Substrate-Independence Theory: Advancing Constructor Theory to Scaffold Substrate Attributes for the Recursive Interaction between Knowledge and Information
Article exploring how information and knowledge are absorbed by utilizing Constructor Theory and the Substrate-Independence Theory.
Date:
November 30, 2021
Creator:
Turner, John R.; Snowden, Dave & Thurlow, Nigel
Object Type:
Article
System:
The UNT Digital Library
Microstability theory for the field reversed configuration. Final report
This report summarizes the work done in the last contract period. Previous work has been described in Annual Performance Reports. The work carried on under this Research Grant and not included in previous progress and annual reports includes two distinct items. One work is a study of the nonlocal high beta microstability of the FRC (Field Reversed Configuration), which they began sometime ago. This study identified the limiting beta (=4{pi}nT/B{sup 2}) for the mode to remain unstable. The study found that as beta increases, the wavenumbers (k{sub y}, K{sub z}) for maximum growth changes, so that the limiting beta is not the one found by fixing (k{sub y}, K{sub z}) and increasing beta. It also appears that the criterion for nonlocal terms to influence the result, as beta increases, is substantially weaker than might have been thought. The authors identify the parameter that determines this effect. This study is presented as Appendix 1 of this report. The second study is of the effect of collisions on the lower hybrid drift instability. The result is that the effect of collisions is substantially more important than might have been expected. These two studies are in different stages of completion. The second is …
Date:
November 5, 1997
Creator:
Krall, Nicholas A.
Object Type:
Report
System:
The UNT Digital Library
A Test for Emergent Dynamics
None
Date:
April 5, 2013
Creator:
Hook, Anson
Object Type:
Article
System:
The UNT Digital Library
An essay on discrete foundations for physics
We base our theory of physics and cosmology on the five principles of finiteness, discreteness, finite computability, absolute non- uniqueness, and strict construction. Our modeling methodology starts from the current practice of physics, constructs a self-consistent representation based on the ordering operator calculus and provides rules of correspondence that allow us to test the theory by experiment. We use program universe to construct a growing collection of bit strings whose initial portions (labels) provide the quantum numbers that are conserved in the events defined by the construction. The labels are followed by content strings which are used to construct event-based finite and discrete coordinates. On general grounds such a theory has a limiting velocity, and positions and velocities do not commute. We therefore reconcile quantum mechanics with relativity at an appropriately fundamental stage in the construction. We show that events in different coordinate systems are connected by the appropriate finite and discrete version of the Lorentz transformation, that 3-momentum is conserved in events, and that this conservation law is the same as the requirement that different paths can ''interfere'' only when they differ by an integral number of deBroglie wavelengths. 38 refs., 12 figs., 3 tabs.
Date:
October 5, 1988
Creator:
Noyes, H. P. & McGoveran, D. O.
Object Type:
Article
System:
The UNT Digital Library
Recent developments in nuclear reaction theories and calculations
A brief review is given of some recent developments in the fields of optical model potentials; level densities; and statistical model, precompound, and direct reaction codes and calculations. Significant developments have occurred in all of these fields since the 1977 Conference on Neutron Cross Sections, which will greatly enhance the ability to calculate high-energy neutron-induced reaction cross sections in the next few years. 11 figures, 3 tables.
Date:
May 5, 1980
Creator:
Gardner, D. G.
Object Type:
Article
System:
The UNT Digital Library
Heavy quarks and lattice QCD
This paper is a review of heavy quarks in lattice gauge theory, focusing on methodology. It includes a status report on some of the calculations that are relevant to heavy-quark spectroscopy and to flavor physics.
Date:
November 5, 2003
Creator:
Kronfeld, Andreas S.
Object Type:
Article
System:
The UNT Digital Library
Methods for testing transport models. Third year annual report
This report documents progress to date under a three-year contract for developing ``Methods for Testing Transport Models.`` The work described includes (1) choice of best methods for producing ``code emulators`` for analysis of very large global energy confinement databases, (2) recent applications of stratified regressions for treating individual measurement errors as well as calibration/modeling errors randomly distributed across various tokamaks, (3) Bayesian methods for utilizing prior information due to previous empirical and/or theoretical analyses, (4) extension of code emulator methodology to profile data, (5) application of nonlinear least squares estimators to simulation of profile data, (6) development of more sophisticated statistical methods for handling profile data, (7) acquisition of a much larger experimental database, and (8) extensive exploratory simulation work on a large variety of discharges using recently improved models for transport theories and boundary conditions. From all of this work, it has been possible to define a complete methodology for testing new sets of reference transport models against much larger multi-institutional databases.
Date:
January 5, 1993
Creator:
Singer, C. & Cox, D.
Object Type:
Report
System:
The UNT Digital Library
Methods for testing transport models. [Departments of Nuclear Engineering and Statistics, Univ. of Illinois at Urbana[endash]Champaign]
This report documents progress to date under a three-year contract for developing Methods for Testing Transport Models.'' The work described includes (1) choice of best methods for producing code emulators'' for analysis of very large global energy confinement databases, (2) recent applications of stratified regressions for treating individual measurement errors as well as calibration/modeling errors randomly distributed across various tokamaks, (3) Bayesian methods for utilizing prior information due to previous empirical and/or theoretical analyses, (4) extension of code emulator methodology to profile data, (5) application of nonlinear least squares estimators to simulation of profile data, (6) development of more sophisticated statistical methods for handling profile data, (7) acquisition of a much larger experimental database, and (8) extensive exploratory simulation work on a large variety of discharges using recently improved models for transport theories and boundary conditions. From all of this work, it has been possible to define a complete methodology for testing new sets of reference transport models against much larger multi-institutional databases.
Date:
January 5, 1993
Creator:
Singer, C. & Cox, D.
Object Type:
Report
System:
The UNT Digital Library
Searching for top, Higgs, and supersymmetry: the minimum invariant mass technique
Supersymmetric particls, Higgs mesons, the top quark and other heavy objects are expected to decay frequently into three or more body final states in which at least one particle, such a neutrino or photino, is non-interacting. A method is described for obtaining an excellent estimate of both the mass and the longitudinal momentum of the parent state. The probable longitudinal momenta of the non-interacting particle and of the parent, and the minimum invariant mass of the parent are derived from a minimization procedure. The distributions in these variables are shown to peak sharply at their true values.
Date:
March 5, 1984
Creator:
Berger, E. L.
Object Type:
Article
System:
The UNT Digital Library
[News Clip: Grand Old Party Senate]
Video footage from the KXAS-TV/NBC station in Fort Worth, Texas, to accompany a news story.
Date:
January 5, 1993, 5:00 p.m.
Creator:
KXAS-TV (Television station : Fort Worth, Tex.)
Object Type:
Video
System:
The UNT Digital Library
On Theories for Reacting Immiscible Mixtures
On some small scale each constituent of an immiscible mixture occupies a separate region of space. Given sufficient time and computing power, we could solve the continuum field equations and boundary conditions for this het erogenous system. This usually represents an enormously difficult task that is well beyond today's computational ca- pabilities. Mixture theories approximate this complex heterogeneous formulation with a set of field equations for an equivalent homoge- neous mat erial. In this work, we compare the theory for immiscible mixtures by Drumheller and Bedford with the theory of Passman, Nunziato, and Walsh. We describe the conditions under which these theories reduce to an equivalent formulation, and we also investigate the differences in their microinertial descriptions. Two variables play special roles in both theories. They are t he true material density and the volume fraction. Here we use a kinematical approach based on two new variables-t he true deformation gradient and the distention gradient. We show how the true deformation gra- dient is connected to the true material density and, in the absence of chemical reactions, the volume fraction is the inverse of the deter- minant of the distention gradient. However, when chemical reactions occur, the distention gradient and …
Date:
November 5, 1998
Creator:
Drumheller, D.S.
Object Type:
Article
System:
The UNT Digital Library
The representation of numbers by states in quantum mechanics.
None
Date:
September 5, 2000
Creator:
Benioff, P.
Object Type:
Article
System:
The UNT Digital Library
Networking of psychophysics, psychology, and neurophysiology
Article discussing the dynamic networking and dynamic networks in complex research on psychophysics, psychology, and neurophysiology.
Date:
November 5, 2012
Creator:
West, Bruce J. & Grigolini, Paolo
Object Type:
Article
System:
The UNT Digital Library
The Optimist (Abilene, Tex.), Vol. 98, No. 42, Ed. 1 Friday, March 5, 2010
Bi-weekly student newspaper from Abilene Christian University in Abilene, Texas that includes local, state and campus news along with advertising.
Date:
March 5, 2010
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
The quandry of benchmarking broadcasts
A message passing library's implementation of broadcast communication can significantly affect the performance of applications built with that library. In order to choose between similar implementations or to evaluate available libraries, accurate measurements of broadcast performance are required. As we demonstrate, existing methods for measuring broadcast performance are either inaccurate or inadequate. Fortunately, we have designed an accurate method for measuring broadcast performance. Measuring broadcast performance is not simple. Simply sending one broadcast after another allows them to proceed through the network concurrently, thus resulting in accurate per broadcast timings. Existing methods either fail to eliminate this pipelining effect or eliminate it by introducing overheads that are as difficult to measure as the performance of the broadcast itself. Our method introduces a measurable overhead to eliminate the pipelining effect.
Date:
February 5, 1999
Creator:
Karonis, N T & Supinski, B R
Object Type:
Article
System:
The UNT Digital Library
Improved Transport Processes for CCSM
In atmospheric modeling, global spectral methods have dominated weather and climate simulation for the past two decades. However, global methods based upon the spherical harmonic basis functions require expensive non-local communication and thus have difficulty in exploiting the full potential of current high-performance parallel computers. The primary objective of HOMME ((11)) is the development of a class of high-order scalable conservative atmospheric models for climate and general atmospheric modeling applications. The spatial discretizations are based on continuous Galerkin (spectral element method) and discontinuous Galerkin (DG). These are local methods based on high-order accurate spectral basis functions which have been shown to perform well on massively parallel supercomputers at any resolution (18). HOMME employs a cubed-sphere geometry (26) exhibiting none of the singularities present in conventional latitude-longitude spherical geometries. The element based formulation enables the use of general curvilinear geometries and adaptive conforming or non-conforming meshes.
Date:
May 5, 2011
Creator:
Tufo, Henry
Object Type:
Report
System:
The UNT Digital Library
Effects due to the large ambipolar potential in TMX
The large potentials and potential gradients in tandem mirrors have several effects. Some of these are discussed, together with supporting data from TMX. These include: azimuthal averaging by the E x B rotation, reduction of radial outward drifts (from high order multipoles) by the rapid E x B azimuthal velocity, neoclassical-resonant diffusion, Joule heating of central cell ions due to non-ambipolar transport in the radial electric field, low frequency instabilities, and differences between the details of the electron behavior and theory.
Date:
May 5, 1981
Creator:
Hooper, E. B. Jr.; Allen, S. L. & Coakley, P.
Object Type:
Article
System:
The UNT Digital Library
Supersymmetry Parameter Analysis: SPA Convention and Project
High-precision analyses of supersymmetry parameters aim atreconstructing the fundamental supersymmetric theory and its breakingmechanism. A well defined theoretical framework is needed whenhigher-order corrections are included. We propose such a scheme,Supersymmetry Parameter Analysis SPA, based on a consistent set ofconventions and input parameters. A repository for computer programs isprovided which connect parameters in different schemes and relate theLagrangian parameters to physical observables at LHC and high energy e+e-linear collider experiments, i.e., masses, mixings, decay widths andproduction cross sections for supersymmetric particles. In addition,programs for calculating high-precision low energy observables, thedensity of cold dark matter (CDM) in the universe as well as the crosssections for CDM search experiments are included. The SPA scheme stillrequires extended efforts on both the theoretical and experimental sidebefore data can be evaluated in the future at the level of the desiredprecision. We take here an initial step of testing the SPA scheme byapplying the techniques involved to a specific supersymmetry referencepoint.
Date:
May 5, 2005
Creator:
Hinchliffe, I. & al., et
Object Type:
Article
System:
The UNT Digital Library
Quantitative Characterization of Nanostructured Materials
The two-and-a-half day symposium on the "Quantitative Characterization of Nanostructured Materials" will be the first comprehensive meeting on this topic held under the auspices of a major U.S. professional society. Spring MRS Meetings provide a natural venue for this symposium as they attract a broad audience of researchers that represents a cross-section of the state-of-the-art regarding synthesis, structure-property relations, and applications of nanostructured materials. Close interactions among the experts in local structure measurements and materials researchers will help both to identify measurement needs pertinent to real-world materials problems and to familiarize the materials research community with the state-of-the-art local structure measurement techniques. We have chosen invited speakers that reflect the multidisciplinary and international nature of this topic and the need to continually nurture productive interfaces among university, government and industrial laboratories. The intent of the symposium is to provide an interdisciplinary forum for discussion and exchange of ideas on the recent progress in quantitative characterization of structural order in nanomaterials using different experimental techniques and theory. The symposium is expected to facilitate discussions on optimal approaches for determining atomic structure at the nanoscale using combined inputs from multiple measurement techniques.
Date:
August 5, 2010
Creator:
Dr. Frank (Bud) Bridges, University of California-Santa Cruz
Object Type:
Report
System:
The UNT Digital Library
Geographic Distance, Contact, and Family Perceptions of Quality Nursing Home Care
Article on the geographic distance, contact and family perceptions of quality nursing home care.
Date:
September 5, 2011
Creator:
Dillman, Jennifer L.; Yeatts, Dale E., 1952- & Cready, Cynthia M.
Object Type:
Article
System:
The UNT Digital Library
Quarterly report, physics unit, January, February, March, 1954
A new method of calculating neutron distributions in a cylinder which has appreciable absorption is described. Measurements and calculations on the small-source theory treatment of resonance absorption in U-238 are given. Experimental measurements are reported of the bucklings of lattices utilizing hollow uranium slugs. The effects of varying amounts of cooling water in a graphite-uranium lattice have been measured. A detailed mathematical fitting of experimental reactivity data has been started; some initial results are given here. Curves showing the periods of the lattice testing reactor under various conditions have been calculated in connection with a study of the nuclear safety of this reactor. A method for calculating the critical mass and an estimate (4.4 kg of-U-235) thereof is presented. A technique for measuring the conversion efficiency for U-233 production of Hanford-type lattices is being developed. In connection with the study of the temperature coefficient of reactivity, an analysis has been made of the errors in reactivity change estimates produced by errors in cross-section measurements. The dependence of Pu-240 content in product plutonium on the flux level at which irradiation takes place, which is produced by the 23-day half life of Np-239 is worked out in some detail. An experiment for …
Date:
April 5, 1954
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Terahertz radiation from laser accelerated electron bunches
Coherent terahertz and millimeter wave radiation from laser accelerated electron bunches has been measured. The bunches were produced by tightly focusing (spot diameter {approx} 6 {micro}m) a high peak power (up to 10 TW), ultra-short ({ge}50 fs) laser pulse from a high repetition rate (10 Hz) laser system (0.8 {micro}m), onto a high density (>10{sup 19} cm{sup -3}) pulsed gas jet of length {approx} 1.5 mm. As the electrons exit the plasma, coherent transition radiation is generated at the plasma-vacuum boundary for wavelengths long compared to the bunch length. Radiation in the 0.3-19 THz range and at 94 GHz has been measured and found to depend quadratically on the bunch charge. The measured radiated energy for two different collection angles is in good agreement with theory. Modeling indicates that optimization of this table-top source could provide more than 100 {micro}J/pulse. Together with intrinsic synchronization to the laser pulse, this will enable numerous applications requiring intense terahertz radiation. This radiation can also be used as a powerful tool for measuring the properties of laser accelerated bunches at the exit of the plasma accelerator. Preliminary spectral measurements indicates that bunches as short as 30-50 fs have been produced in these laser driven …
Date:
January 5, 2004
Creator:
Leemans, W. P.; van Tilborg, J.; Faure, J.; Geddes, C. G. R.; Toth, Cs.; Schroe der, C. B. et al.
Object Type:
Article
System:
The UNT Digital Library
Computational Needs for the Next Generation Electric Grid Proceedings
The April 2011 DOE workshop, 'Computational Needs for the Next Generation Electric Grid', was the culmination of a year-long process to bring together some of the Nation's leading researchers and experts to identify computational challenges associated with the operation and planning of the electric power system. The attached papers provide a journey into these experts' insights, highlighting a class of mathematical and computational problems relevant for potential power systems research. While each paper defines a specific problem area, there were several recurrent themes. First, the breadth and depth of power system data has expanded tremendously over the past decade. This provides the potential for new control approaches and operator tools that can enhance system efficiencies and improve reliability. However, the large volume of data poses its own challenges, and could benefit from application of advances in computer networking and architecture, as well as data base structures. Second, the computational complexity of the underlying system problems is growing. Transmitting electricity from clean, domestic energy resources in remote regions to urban consumers, for example, requires broader, regional planning over multi-decade time horizons. Yet, it may also mean operational focus on local solutions and shorter timescales, as reactive power and system dynamics (including …
Date:
October 5, 2011
Creator:
Birman, Kenneth; Ganesh, Lakshmi; Renessee, Robbert van; Ferris, Michael; Hofmann, Andreas; Williams, Brian et al.
Object Type:
Article
System:
The UNT Digital Library