An Algebraic Approach to the Evolution of Emittances upon Crossing the Linear Coupling Difference Resonance (open access)

An Algebraic Approach to the Evolution of Emittances upon Crossing the Linear Coupling Difference Resonance

N/A
Date: September 1, 2008
Creator: Gardner, C. J.
Object Type: Report
System: The UNT Digital Library
An Algebraic Approach to the Evolution of Emittances upon Crossing the Linear Coupling Difference Resonance (open access)

An Algebraic Approach to the Evolution of Emittances upon Crossing the Linear Coupling Difference Resonance

One of the hallmarks of linear coupling is the resonant exchange of oscillation amplitude between the horizontal and vertical planes when the difference between the unperturbed tunes is close to an integer. The standard derivation of this phenomenon (known as the difference resonance) can be found, for example, in the classic papers of Guignard [1, 2]. One starts with an uncoupled lattice and adds a linear perturbation that couples the two planes. The equations of motion are expressed in hamiltonian form. As the difference between the unperturbed tunes approaches an integer, one finds that the perturbing terms in the hamiltonian can be divided into terms that oscillate slowly and ones that oscillate rapidly. The rapidly oscillating terms are discarded or transformed to higher order with an appropriate canonical transformation. The resulting approximate hamiltonian gives equations of motion that clearly exhibit the exchange of oscillation amplitude between the two planes. If, instead of the hamiltonian, one is given the four-by-four matrix for one turn around a synchrotron, then one has the complete solution for the turn-by-turn (TBT) motion. However, the conditions for the phenomenon of amplitude exchange are not obvious from a casual inspection of the matrix. These conditions and those …
Date: September 1, 2008
Creator: Gardner,C.
Object Type: Report
System: The UNT Digital Library
A search for W+- H ---> muon-neutrino b anti-b production at the Tevatron (open access)

A search for W+- H ---> muon-neutrino b anti-b production at the Tevatron

All known experimental results on fundamental particles and their interactions can be described to great accuracy by a theory called the Standard Model. In the Standard Model of particle physics, the masses of particles are explained through the Higgs mechanism. The Higgs boson is the only Standard Model particle not discovered yet, and its observation or exclusion is an important test of the Standard Model. While the Standard Model predicts that a Higgs boson should exist, it does not exactly predict its mass. Direct searches have excluded a Higgs with m{sub H} < 114.4 GeV at 95% confidence level, while indirect measurements indicate that the mass should be less than 144 GeV. This analysis looks for W{sup {+-}}H {yields} {mu}{nu}{sub {mu}}b{bar b} in 1 fb{sup -1} of data collected with the D0 detector in p{bar p} collisions with {radical}s = 1.96 TeV. The analysis strategy relies on the tracking, calorimetry and muon reconstruction of the D0 experiment. The signature is a muon, missing transverse energy (E{sub T}) to account for the neutrino and two b-jets. The Higgs mass is reconstructed using the invariant mass of the two jets. Backgrounds are W{sup {+-}}b{bar b}, W{sup {+-}} c{bar c}, W{sup {+-}} + …
Date: February 1, 2008
Creator: Anastasoaie, Carmen Miruna & U., /Nijmegen
Object Type: Thesis or Dissertation
System: The UNT Digital Library
R_transport_matrices (open access)

R_transport_matrices

N/A
Date: January 1, 2008
Creator: N., Tsoupas; MacKay, W. W.; Satogata, T.; Glenn, W.; Ahrens, L.; Brown, K. et al.
Object Type: Report
System: The UNT Digital Library
R_transport_matrices of the Fast Extraction Beam (FEB) of the AGS, and Beam Parameters at the Starting point of the AtR Line (open access)

R_transport_matrices of the Fast Extraction Beam (FEB) of the AGS, and Beam Parameters at the Starting point of the AtR Line

As part of the task to improve and further automate the 'AtR BPM Application' we provide the theoretically calculated R-transport-matrices for the following beam line sections, which are shown schematically in Figure 1: (a) the Fast Extraction Beam section (FEB) of the AGS synchrotron. The FEB section starts at the middle of the GlO-kicker and ends at the middle of the H1 0{_}septum. (b) the Drift Extraction Channel (DEC) section of the AGS synchrotron. The DEC section starts at the middle of the H10{_}septum, continues along the fringe field region of the H11,H12, and H13 AGS main magnets, and ends at the starting point of the AtR line. The knowledge of these R-transport-matrices are needed in order to calculate the beam parameters at the beginning of the AtR line, which in turn, are required to calculate the magnet settings of the U{_}line, that match the U{_}line into the W{_}line. Also by incorporating these R{_}matrices into the model of the AtR line, the G10 kicker and the H10 septum are included in the AtR model therefore one can investigate any 'jitter' of either the GlO{_}kicker or HlO{_}septum by looking at the trajectory of the beam in the AtR line.
Date: January 1, 2008
Creator: Tsoupas, N.; MacKay, W. W.; Satogata, T.; Glenn, W.; Ahrens, L.; Brown, K. et al.
Object Type: Report
System: The UNT Digital Library
Summary of the RHIC Retreat 2007 (open access)

Summary of the RHIC Retreat 2007

N/A
Date: August 1, 2008
Creator: Pilat, F.; Gardner, C.; Montag, C. & Roser, T.
Object Type: Report
System: The UNT Digital Library
Summary of the RHIC Retreat 2007 (open access)

Summary of the RHIC Retreat 2007

The RHIC Retreat 2007 took place on July 16-17 2007 at the Foxwoods Resort in CT, about 3 weeks after the end of the RHIC Run-7. The goal of the Retreat is traditionally to plan the upcoming run in the light of the results from the previous one, by providing a snapshot of the present understanding of the machine and a forum for free and frank discussion. A particular attention was paid to the challenge of increasing the time at store, and the related issue of system reliability. An interesting Session covered all new developments aimed to improve the machine performance and luminosity. In Section 2 we summarize the results from Run-7 for RHIC and the injectors and discuss the present objectives of the RHIC program and performance. Sections 3-6 are summaries of the Retreat sessions focused on preparation for deuteron gold and polarized protons, respectively, machine availability and new developments.
Date: August 1, 2008
Creator: Pilat, F.; Gardner, C.; Montag, C. & Roser, T.
Object Type: Report
System: The UNT Digital Library

Legislating Biofuels in the United States

Legislation supporting U.S. biofuels production can help to reduce petroleum consumption and increase the nation's energy security.
Date: July 1, 2008
Creator: Clark, W.
Object Type: Presentation
System: The UNT Digital Library
MSTD 2007 Publications and Patents (open access)

MSTD 2007 Publications and Patents

The Materials Science and Technology Division (MSTD) supports the central scientific and technological missions of the Laboratory, and at the same time, executes world-class, fundamental research and novel technological development over a wide range of disciplines. Our organization is driven by the institutional needs in nuclear weapons stockpile science, high-energy-density science, nuclear reactor science, and energy and environment science and technology. We maintain expertise and capabilities in many diverse areas, including actinide science, electron microscopy, laser-materials interactions, materials theory, simulation and modeling, materials synthesis and processing, materials science under extreme conditions, ultrafast materials science, metallurgy, nanoscience and technology, nuclear fuels and energy security, optical materials science, and surface science. MSTD scientists play leadership roles in the scientific community in these key and emerging areas.
Date: April 1, 2008
Creator: King, W. E.
Object Type: Book
System: The UNT Digital Library
An Atomic Gravitational Wave Interferometric Sensor (AGIS) (open access)

An Atomic Gravitational Wave Interferometric Sensor (AGIS)

We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10m atom interferometer presently under construction. Each configuration compares two widely separated atom interferometers run using common lasers. The signal scales with the distance between the interferometers, which can be large since only the light travels over this distance, not the atoms. The terrestrial experiment with baseline {approx} 1 km can operate with strain sensitivity {approx} 10{sup -19}/{radical}Hz in the 1 Hz-10 Hz band, inaccessible to LIGO, and can detect gravitational waves from solar mass binaries out to megaparsec distances. The satellite experiment with baseline {approx} 1000 km can probe the same frequency spectrum as LISA with comparable strain sensitivity {approx} 10{sup -20}/{radical}Hz. The use of ballistic atoms (instead of mirrors) as inertial test masses improves systematics coming from vibrations, acceleration noise, and significantly reduces spacecraft control requirements. We analyze the backgrounds in this configuration and discuss methods for controlling them to the required levels.
Date: August 1, 2008
Creator: Dimopoulos, Savas; Graham, Peter W.; Hogan, Jason M.; Kasevich, Mark A. & Rajendran, Surjeet
Object Type: Report
System: The UNT Digital Library
Discovery of a Giant Lya Emitter Near the Reionization Epoch (open access)

Discovery of a Giant Lya Emitter Near the Reionization Epoch

We report the discovery of a giant Ly{alpha} emitter (LAE) with a Spitzer/IRAC counterpart near the reionization epoch at z = 6.595. The giant LAE is found from the extensive 1 deg{sup 2} Subaru narrow-band survey for z = 6.6 LAEs in the Subaru/XMM-Newton Deep Survey (SXDS) field, and subsequently identified by deep spectroscopy of Keck/DEIMOS and Magellan/IMACS. Among our 207 LAE candidates, this LAE is not only the brightest narrow-band object with L(Ly{alpha}) = 3.9 {+-} 0.2 x 10{sup 43} erg s{sup -1} in our survey volume of 10{sup 6} Mpc{sup 3}, but also a spatially extended Ly{alpha} nebula with the largest isophotal area whose major axis is at least {approx_equal} 3-inches. This object is more likely to be a large Ly{alpha} nebula with a size of {approx}> 17-kpc than to be a strongly-lensed galaxy by a foreground object. Our Keck spectrum with medium-high spectral and spatial resolutions suggests that the velocity width is v{sub FWHM} = 251 {+-} 21 km s{sup -1}, and that the line-center velocity changes by {approx_equal} 60 km s{sup -1} in a 10-kpc range. The stellar mass and star-formation rate are estimated to be 0.9-5.0 x 10{sup 10}M{sub {circle_dot}} and > 34 M{sub {circle_dot}}yr{sup …
Date: August 1, 2008
Creator: Ouchi, Masami; Ono, Yoshiaki; Egami, Eiichi; Saito, Tomoki; Oguri, Masamune; McCarthy, Patrick J. et al.
Object Type: Article
System: The UNT Digital Library
Post-Translational Modifications of Desulfovibrio vulgaris Hildenborough Sulfate Reduction Pathway Proteins (open access)

Post-Translational Modifications of Desulfovibrio vulgaris Hildenborough Sulfate Reduction Pathway Proteins

Recent developments in shotgun proteomics have enabled high-throughput studies of a variety of microorganisms at a proteome level and provide experimental validation for predicted open reading frames in the corresponding genome. More importantly, advances in mass spectrometric data analysis now allow mining of large proteomics data sets for the presence of post-translational modifications(PTMs). Although PTMs are a critical aspectof cellular activity, such information eludes cell-wide studies conducted at the transcript level. Here, we analyze several mass spectrometric data sets acquired using two-dimensional liquid chromatography tandem mass spectrometry, 2D-LC/MS/MS, for the sulfate reducing bacterium, Desulfovibrio vulgaris Hildenborough. Our searches of the raw spectra led us to discover several post-translationally modified peptides in D. vulgaris. Of these, several peptides containing a lysine with a +42 Da modification were found reproducibly across all data sets. Both acetylation and trimethylation have the same nominal +42 Da mass, and are therefore candidates for this modification. Several spectra were identified having markers for trimethylation, while one is consistent with an acetylation. Surprisingly, these modified peptides predominantly mapped to proteins involved in sulfate respiration. Other highly expressed proteins in D. vulgaris, such as enzymes involved in electron transport and other central metabolic processes, did not contain this …
Date: March 1, 2008
Creator: Gaucher, S. P.; Redding, A. M.; Mukhopadhyay, A.; Keasling, J. D. & Singh, A. K.
Object Type: Article
System: The UNT Digital Library
Aspen Ecology in Rocky Mountain National Park: Age Distribution, Genetics, and the Effects of Elk Herbivory (open access)

Aspen Ecology in Rocky Mountain National Park: Age Distribution, Genetics, and the Effects of Elk Herbivory

Lack of aspen (Populus tremuloides) recruitment and canopy replacement of aspen stands that grow on the edges of grasslands on the low-elevation elk (Cervus elaphus) winter range of Rocky Mountain National Park (RMNP) in Colorado has been a cause of concern for more than 70 years (Packard, 1942; Olmsted, 1979; Stevens, 1980; Hess, 1993; R.J. Monello, T.L. Johnson, and R.G. Wright, Rocky Mountain National Park, 2006, written commun.). These aspen stands are a significant resource since they are located close to the park's road system and thus are highly visible to park visitors. Aspen communities are integral to the ecological structure of montane and subalpine landscapes because they contain high native species richness of plants, birds, and butterflies (Chong and others, 2001; Simonson and others, 2001; Chong and Stohlgren, 2007). These low-elevation, winter range stands also represent a unique component of the park's plant community diversity since most (more than 95 percent) of the park's aspen stands grow in coniferous forest, often on sheltered slopes and at higher elevations, while these winter range stands are situated on the low-elevation ecotone between the winter range grasslands and some of the park's drier coniferous forests.
Date: October 1, 2008
Creator: Tuskan, Gerald A & Yin, Tongming
Object Type: Report
System: The UNT Digital Library
Emerging factors associated with the decline of a gray fox population and multi-scale land cover associations of mesopredators in the Chicago metropolitan area. (open access)

Emerging factors associated with the decline of a gray fox population and multi-scale land cover associations of mesopredators in the Chicago metropolitan area.

Statewide surveys of furbearers in Illinois indicate gray (Urocyon cinereoargenteus) and red (Vulpes vulpes) foxes have experienced substantial declines in relative abundance, whereas other species such as raccoons (Procyon lotor) and coyotes (Canis latrans) have exhibited dramatic increases during the same time period. The cause of the declines of gray and red foxes has not been identified, and the current status of gray foxes remains uncertain. Therefore, I conducted a large-scale predator survey and tracked radiocollared gray foxes from 2004 to 2007 in order to determine the distribution, survival, cause-specific mortality sources and land cover associations of gray foxes in an urbanized region of northeastern Illinois, and examined the relationships between the occurrence of gray fox and the presence other species of mesopredators, specifically coyotes and raccoons. Although generalist mesopredators are common and can reach high densities in many urban areas their urban ecology is poorly understood due to their secretive nature and wariness of humans. Understanding how mesopredators utilize urbanized landscapes can be useful in the management and control of disease outbreaks, mitigation of nuisance wildlife issues, and gaining insight into how mesopredators shape wildlife communities in highly fragmented areas. I examined habitat associations of raccoons, opossums (Didelphis virginiana), …
Date: January 1, 2008
Creator: Willingham, Alison N.
Object Type: Report
System: The UNT Digital Library
Physical Fidelity in Particle-In-Cell Modeling of Small Debye-Length Plasmas (open access)

Physical Fidelity in Particle-In-Cell Modeling of Small Debye-Length Plasmas

The connection between macro-particle shape functions and non-physical phase-space"heating" in the particle-in-cell (PIC) algorithm is examined. The development of fine-scale phasespace structures starting from a cold initial condition is shown to be related to spatial correlations in the interpolated fields used in the Lorentz force. It is shown that the plasma evolution via the PIC algorithm from a cold initial condition leads to a state that is not consistent with that of a thermal plasma.
Date: August 1, 2008
Creator: Shadwick, B. A. & Schroeder, C. B.
Object Type: Article
System: The UNT Digital Library
Fast six-channel pyrometer for warm-dense-matter experiments with intense heavy-ion beams (open access)

Fast six-channel pyrometer for warm-dense-matter experiments with intense heavy-ion beams

This paper describes a fast multi-channel radiation pyrometer that was developed for warmdense-matter experiments with intense heavy ion beams at Gesellschaft fur Schwerionenforschung mbH (GSI). The pyrometer is capable of measuring of brightness temperatures from 2000 K to 50000 K, at 6 wavelengths in visible and near-infrared parts of spectrum, with 5 nanosecond temporal resolution and several micrometers spatial resolution. The pyrometer's spectral discrimination technique is based on interference filters, which act as filters and mirrors to allow for simultaneous spectral discrimination of the same ray at multiple wavelengths.
Date: December 1, 2008
Creator: Ni, P.A.; Kulish, M.I.; Mintsev, V.; Nikolaev, D.N.; Ternovoi, V.Ya.; Hoffmann, D.H.H. et al.
Object Type: Article
System: The UNT Digital Library
A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces (open access)

A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces

We describe a combined ambient pressure photoelectron spectroscopy/droplet train apparatus for investigating the nature and heterogeneous chemistry of liquid/vapor interfaces. In this instrument a liquid droplet train with typical droplet diameters from 50...150 {micro}m is produced by a vibrating orifice aerosol generator (VOAG). The droplets are irradiated by soft X-rays (100...1500 eV) in front of the entrance aperture of a differentially pumped electrostatic lens system that transfers the emitted electrons into a conventional hemispherical electron analyzer. The photoemission experiments are performed at background pressures of up to several Torr, which allows the study of environmentally important liquid/vapor interfaces, in particular aqueous solutions, under equilibrium conditions. The exposure time of the droplet surface to the background gases prior to the XPS measurement can be varied, which will allow future kinetic measurements of gas uptake on liquid surfaces. As an example, a measurement of the surface composition of a {chi} = 0.21 aqueous methanol solution is presented. The concentration of methanol at the vapor/liquid interface is enhanced by a factor of about 3 over the bulk value, while the expected bulk value is recovered at depths larger than about 1.5 nm.
Date: May 1, 2008
Creator: Starr, David E.; Wong, Ed K.; Worsnop, Douglas R.; Wilson, Kevin R. & Bluhm, Hendrik
Object Type: Article
System: The UNT Digital Library
Advanced Mud System for Microhole Coiled Tubing Drilling (open access)

Advanced Mud System for Microhole Coiled Tubing Drilling

An advanced mud system was designed and key components were built that augment a coiled tubing drilling (CTD) rig that is designed specifically to drill microholes (less than 4-inch diameter) with advanced drilling techniques. The mud system was tailored to the hydraulics of the hole geometries and rig characteristics required for microholes and is capable of mixing and circulating mud and removing solids while being self contained and having zero discharge capability. Key components of this system are two modified triplex mud pumps (High Pressure Slurry Pumps) for advanced Abrasive Slurry Jetting (ASJ) and a modified Gas-Liquid-Solid (GLS) Separator for well control, flow return and initial processing. The system developed also includes an additional component of an advanced version of ASJ which allows cutting through most all materials encountered in oil and gas wells including steel, cement, and all rock types. It includes new fluids and new ASJ nozzles. The jetting mechanism does not require rotation of the bottom hole assembly or drill string, which is essential for use with Coiled Tubing (CT). It also has low reactive forces acting on the CT and generates cuttings small enough to be easily cleaned from the well bore, which is important in …
Date: December 1, 2008
Creator: Oglesby, Kenneth
Object Type: Report
System: The UNT Digital Library
Hydrogen Scenario Analysis Summary Report: Analysis of the Transition to Hydrogen Fuel Cell Vehicles and the Potential Hydrogen Energy Infrastructure Requirements (open access)

Hydrogen Scenario Analysis Summary Report: Analysis of the Transition to Hydrogen Fuel Cell Vehicles and the Potential Hydrogen Energy Infrastructure Requirements

Achieving a successful transition to hydrogen-powered vehicles in the U.S. automotive market will require strong and sustained commitment by hydrogen producers, vehicle manufacturers, transporters and retailers, consumers, and governments. The interaction of these agents in the marketplace will determine the real costs and benefits of early market transformation policies, and ultimately the success of the transition itself. The transition to hydrogen-powered transportation faces imposing economic barriers. The challenges include developing and refining a new and different power-train technology, building a supporting fuel infrastructure, creating a market for new and unfamiliar vehicles, and achieving economies of scale in vehicle production while providing an attractive selection of vehicle makes and models for car-buyers. The upfront costs will be high and could persist for a decade or more, delaying profitability until an adequate number of vehicles can be produced and moved into consumer markets. However, the potential rewards to the economy, environment, and national security are immense. Such a profound market transformation will require careful planning and strong, consistent policy incentives. Section 811 of the Energy Policy Act (EPACT) of 2005, Public Law 109-59 (U.S. House, 2005), calls for a report from the Secretary of Energy on measures to support the transition to …
Date: March 1, 2008
Creator: Greene, David L.; Leiby, Paul Newsome; James, Brian; Perez, Julie; Melendez, Margo; Milbrandt, Anelia et al.
Object Type: Report
System: The UNT Digital Library
Hierarchical image feature extraction by an irregular pyramid of polygonal partitions (open access)

Hierarchical image feature extraction by an irregular pyramid of polygonal partitions

We present an algorithmic framework for hierarchical image segmentation and feature extraction. We build a successive fine-to-coarse hierarchy of irregular polygonal partitions of the original image. This multiscale hierarchy forms the basis for object-oriented image analysis. The framework incorporates the Gestalt principles of visual perception, such as proximity and closure, and exploits spectral and textural similarities of polygonal partitions, while iteratively grouping them until dissimilarity criteria are exceeded. Seed polygons are built upon a triangular mesh composed of irregular sized triangles, whose spatial arrangement is adapted to the image content. This is achieved by building the triangular mesh on the top of detected spectral discontinuities (such as edges), which form a network of constraints for the Delaunay triangulation. The image is then represented as a spatial network in the form of a graph with vertices corresponding to the polygonal partitions and edges reflecting their relations. The iterative agglomeration of partitions into object-oriented segments is formulated as Minimum Spanning Tree (MST) construction. An important characteristic of the approach is that the agglomeration of polygonal partitions is constrained by the detected edges; thus the shapes of agglomerated partitions are more likely to correspond to the outlines of real-world objects. The constructed partitions …
Date: January 1, 2008
Creator: Skurikhin, Alexei N
Object Type: Article
System: The UNT Digital Library
Hierarchical image feature extraction by an irregular pyramid of polygonal partitions (open access)

Hierarchical image feature extraction by an irregular pyramid of polygonal partitions

None
Date: January 1, 2008
Creator: Skurikhin, Alexei N
Object Type: Article
System: The UNT Digital Library
Software and codes for analysis of concentrating solar power technologies. (open access)

Software and codes for analysis of concentrating solar power technologies.

This report presents a review and evaluation of software and codes that have been used to support Sandia National Laboratories concentrating solar power (CSP) program. Additional software packages developed by other institutions and companies that can potentially improve Sandia's analysis capabilities in the CSP program are also evaluated. The software and codes are grouped according to specific CSP technologies: power tower systems, linear concentrator systems, and dish/engine systems. A description of each code is presented with regard to each specific CSP technology, along with details regarding availability, maintenance, and references. A summary of all the codes is then presented with recommendations regarding the use and retention of the codes. A description of probabilistic methods for uncertainty and sensitivity analyses of concentrating solar power technologies is also provided.
Date: December 1, 2008
Creator: Ho, Clifford Kuofei
Object Type: Report
System: The UNT Digital Library
ORNL Neutron Sciences Annual Report for 2007 (open access)

ORNL Neutron Sciences Annual Report for 2007

This is the first annual report of the Oak Ridge National Laboratory Neutron Sciences Directorate for calendar year 2007. It describes the neutron science facilities, current developments, and future plans; highlights of the year's activities and scientific research; and information on the user program. It also contains information about education and outreach activities and about the organization and staff. The Neutron Sciences Directorate is responsible for operation of the High Flux Isotope Reactor and the Spallation Neutron Source. The main highlights of 2007 were highly successful operation and instrument commissioning at both facilities. At HFIR, the year began with the reactor in shutdown mode and work on the new cold source progressing as planned. The restart on May 16, with the cold source operating, was a significant achievement. Furthermore, measurements of the cold source showed that the performance exceeded expectations, making it one of the world's most brilliant sources of cold neutrons. HFIR finished the year having completed five run cycles and 5,880 MWd of operation. At SNS, the year began with 20 kW of beam power on target; and thanks to a highly motivated staff, we reached a record-breaking power level of 183 kW by the end of the …
Date: July 1, 2008
Creator: Anderson, Ian S; Horak, Charlie M; Counce, Deborah Melinda & Ekkebus, Allen E
Object Type: Report
System: The UNT Digital Library
Mathematical approaches for complexity/predictivity trade-offs in complex system models : LDRD final report. (open access)

Mathematical approaches for complexity/predictivity trade-offs in complex system models : LDRD final report.

The goal of this research was to examine foundational methods, both computational and theoretical, that can improve the veracity of entity-based complex system models and increase confidence in their predictions for emergent behavior. The strategy was to seek insight and guidance from simplified yet realistic models, such as cellular automata and Boolean networks, whose properties can be generalized to production entity-based simulations. We have explored the usefulness of renormalization-group methods for finding reduced models of such idealized complex systems. We have prototyped representative models that are both tractable and relevant to Sandia mission applications, and quantified the effect of computational renormalization on the predictive accuracy of these models, finding good predictivity from renormalized versions of cellular automata and Boolean networks. Furthermore, we have theoretically analyzed the robustness properties of certain Boolean networks, relevant for characterizing organic behavior, and obtained precise mathematical constraints on systems that are robust to failures. In combination, our results provide important guidance for more rigorous construction of entity-based models, which currently are often devised in an ad-hoc manner. Our results can also help in designing complex systems with the goal of predictable behavior, e.g., for cybersecurity.
Date: September 1, 2008
Creator: Goldsby, Michael E.; Mayo, Jackson R.; Bhattacharyya, Arnab (Massachusetts Institute of Technology, Cambridge, MA); Armstrong, Robert C. & Vanderveen, Keith
Object Type: Report
System: The UNT Digital Library