Quantum size effects in the growth and properties of ultrathin metal films, alloys, and related low-dimensional structures (open access)

Quantum size effects in the growth and properties of ultrathin metal films, alloys, and related low-dimensional structures

None
Date: January 1, 2011
Creator: Jia, Yu; Ozer, Mustafa M.; Weitering, Harm H. & Zhang, Zhenyu
System: The UNT Digital Library
Ion exchange phenomena (open access)

Ion exchange phenomena

Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).
Date: May 1, 2011
Creator: Bourg, I.C. & Sposito, G.
System: The UNT Digital Library
Geologic carbon sequestration as a global strategy to mitigate CO2 emissions: Sustainability and environmental risk (open access)

Geologic carbon sequestration as a global strategy to mitigate CO2 emissions: Sustainability and environmental risk

Fossil fuels are abundant, inexpensive to produce, and are easily converted to usable energy by combustion as demonstrated by mankind's dependence on fossil fuels for over 80% of its primary energy supply (13). This reliance on fossil fuels comes with the cost of carbon dioxide (CO{sub 2}) emissions that exceed the rate at which CO{sub 2} can be absorbed by terrestrial and oceanic systems worldwide resulting in increases in atmospheric CO{sub 2} concentration as recorded by direct measurements over more than five decades (14). Carbon dioxide is the main greenhouse gas linked to global warming and associated climate change, the impacts of which are currently being observed around the world, and projections of which include alarming consequences such as water and food shortages, sea level rise, and social disruptions associated with resource scarcity (15). The current situation of a world that derives the bulk of its energy from fossil fuel in a manner that directly causes climate change equates to an energy-climate crisis. Although governments around the world have only recently begun to consider policies to avoid the direst projections of climate change and its impacts, sustainable approaches to addressing the crisis are available. The common thread of feasible strategies …
Date: April 1, 2011
Creator: Oldenburg, C.M.
System: The UNT Digital Library
Colloid Facilitated Transport of Plutonium at the Nevada Test Site, NV USA (open access)

Colloid Facilitated Transport of Plutonium at the Nevada Test Site, NV USA

None
Date: January 19, 2011
Creator: Kersting, A. & Zavarin, M.
System: The UNT Digital Library
Ground vibration (open access)

Ground vibration

None
Date: January 1, 2011
Creator: Montag, C. & Rossbach, J.
System: The UNT Digital Library
Energy Storage Annual Progress Report - In Situ Acoustic Emission and X-ray Diffraction of Lithium Ion Battery Materials (ORNL) (open access)

Energy Storage Annual Progress Report - In Situ Acoustic Emission and X-ray Diffraction of Lithium Ion Battery Materials (ORNL)

None
Date: January 1, 2011
Creator: Daniel, Claus & Rhodes, Kevin J
System: The UNT Digital Library
The Role of Disturbance in Dry Tropical Forest Landscapes (open access)

The Role of Disturbance in Dry Tropical Forest Landscapes

Disturbance can be defined as 'any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment'. This definition requires that the spatial and temporal scales of the system and disturbance be determined. Disturbances are typically characterized by their size, spatial distribution, frequency or return time, predictability, and magnitude (which includes both intensity and severity). These disturbance attributes set the parameters for the suite of species, both plant and animal, that can persist within a given system. As such, an understanding of seasonally dry tropical forests in Asia requires an understanding of disturbance within the region. However, disturbances are relatively poorly understood in dry tropical forests, partly because of the weak seasonality in temperature and high tree species diversity of these forests relative to most forest systems of the world. There are about 1,048,700 km{sup 2} of dry tropical forests worldwide and that only 3% of this land is in conservation status. In other words, 97% of the world's seasonally dry tropical forest is at risk of human disturbance. About half of this forest occurs in South America, where most of the conservation lands are located. Satellite imagery based on …
Date: January 1, 2011
Creator: Dale, Virginia H.
System: The UNT Digital Library
Methods for Engineering Sulfate Reducing Bacteria of the Genus Desulfovibrio (open access)

Methods for Engineering Sulfate Reducing Bacteria of the Genus Desulfovibrio

Sulfate reducing bacteria are physiologically important given their nearly ubiquitous presence and have important applications in the areas of bioremediation and bioenergy. This chapter provides details on the steps used for homologous-recombination mediated chromosomal manipulation of Desulfovibrio vulgaris Hildenborough, a well-studied sulfate reducer. More specifically, we focus on the implementation of a 'parts' based approach for suicide vector assembly, important aspects of anaerobic culturing, choices for antibiotic selection, electroporation-based DNA transformation, as well as tools for screening and verifying genetically modified constructs. These methods, which in principle may be extended to other sulfate-reducing bacteria, are applicable for functional genomics investigations, as well as metabolic engineering manipulations.
Date: March 15, 2011
Creator: Chhabra, Swapnil R; Keller, Kimberly L. & Wall, Judy D.
System: The UNT Digital Library
Processing of Soybean Oil into Fuels (open access)

Processing of Soybean Oil into Fuels

Abundant and easily refined, petroleum has provided high energy density liquid fuels for a century. However, recent price fluctuations, shortages, and concerns over the long term supply and greenhouse gas emissions have encouraged the development of alternatives to petroleum for liquid transportation fuels (Van Gerpen, Shanks et al. 2004). Plant-based fuels include short chain alcohols, now blended with gasoline, and biodiesels, commonly derived from seed oils. Of plant-derived diesel feedstocks, soybeans yield the most of oil by weight, up to 20% (Mushrush, Willauer et al. 2009), and so have become the primary source of biomass-derived diesel in the United States and Brazil (Lin, Cunshan et al. 2011). Worldwide ester biodiesel production reached over 11,000,000 tons per year in 2008 (Emerging Markets 2008). However, soybean oil cannot be burned directly in modern compression ignition vehicle engines as a direct replacement for diesel fuel because of its physical properties that can lead to clogging of the engine fuel line and problems in the fuel injectors, such as: high viscosity, high flash point, high pour point, high cloud point (where the fuel begins to gel), and high density (Peterson, Cook et al. 2001). Industrial production of biodiesel from oil of low fatty-acid content …
Date: January 1, 2011
Creator: McFarlane, Joanna
System: The UNT Digital Library
NUCLEAR FORENSICS ANALYSIS CENTER FORENSIC ANALYSIS TO DATA INTERPRETATION (open access)

NUCLEAR FORENSICS ANALYSIS CENTER FORENSIC ANALYSIS TO DATA INTERPRETATION

The Nuclear Forensics Analysis Center (NFAC) is part of Savannah River National Laboratory (SRNL) and is one of only two USG National Laboratories accredited to perform nuclear forensic analyses to the requirements of ISO 17025. SRNL NFAC is capable of analyzing nuclear and radiological samples from bulk material to ultra-trace samples. NFAC provides analytical support to the FBI's Radiological Evidence Examination Facility (REEF), which is located within SRNL. REEF gives the FBI the capability to perform traditional forensics on material that is radiological and/or is contaminated. SRNL is engaged in research and development efforts to improve the USG technical nuclear forensics capabilities. Research includes improving predictive signatures and developing a database containing comparative samples.
Date: February 7, 2011
Creator: Nichols, T.
System: The UNT Digital Library
Metabolic engineering of E.coli for the production of a precursor to artemisinin, an anti-malarial drug (open access)

Metabolic engineering of E.coli for the production of a precursor to artemisinin, an anti-malarial drug

This document is Chapter 25 in the Manual of Industrial Microbiology and Biotechnology, 3rd edition. Topics covered include: Incorporation of Amorpha-4,11-Diene Biosynthetic Pathway into E. coli; Amorpha-4,11-Diene Pathway Optimization; "-Omics" Analyses for Increased Amorpha-4,11-Diene Production; Biosynthetic Oxidation of Amorpha-4,11-Diene.
Date: July 18, 2011
Creator: Petzold, Christopher & Keasling, Jay
System: The UNT Digital Library
MPACT FY2011 Advanced Time-Correlated Measurement Research at INL (open access)

MPACT FY2011 Advanced Time-Correlated Measurement Research at INL

Simulations and experiments have been carried out to investigate advanced time-correlated measurement methods for characterizing and assaying nuclear material for safeguarding the nuclear fuel cycle. These activities are part of a project studying advanced instrumentation techniques in support of the U.S. Department of Energy's Fuel Cycle Research and Development program and its Materials Protection, Accounting, and Control Technologies (MPACT) program. For fiscal year 2011 work focused on examining the practical experimental aspects of using a time-tagged, associated-particle electronic neutron generator for interrogating low-enrichment uranium in combination with steady-state interrogation using a moderated 241Am-Li neutron source. Simulation work for the project involved the use of the MCNP-PoliMi Monte Carlo simulation tool to determine the relative strength and the time-of-flight energy spectra of different sample materials under irradiation. Work also took place to develop a post-processor parser code to extract comparable data from the MCNP5&6 codes. Experiments took place using a commercial deuterium-tritium associated-particle electronic neutron generator to irradiate a number of uranium-bearing material samples. Time-correlated measurements of neutron and photon signatures of these measurements were made using five liquid scintillator detectors in a novel array, using high-speed waveform digitizers for data collection. This report summarizes the experiments that took place in …
Date: September 1, 2011
Creator: Chichester, D. L.; Pozzi, S. A.; Dolan, J. L.; Flaska, M. & Watson, S. M.
System: The UNT Digital Library
Energy Storage Annual Progress Report - Intercalation kinetics and ion mobility in electrode materials (ORNL) (open access)

Energy Storage Annual Progress Report - Intercalation kinetics and ion mobility in electrode materials (ORNL)

None
Date: January 1, 2011
Creator: Daniel, Claus & Kalnaus, Sergiy
System: The UNT Digital Library
Who's In The Dark: Satellite Based Estimates Of Electrification Rates (open access)

Who's In The Dark: Satellite Based Estimates Of Electrification Rates

A technique has been developed to estimate the percent population having electric power access based on the presence of satellite detected nighttime lighting. A global survey was conducted for the year 2006 using nighttime lights collected by the U.S. Air Force Defense Meteorological Satellite Program (DMSP) in combination with the U.S. Department of Energy Landscan population dataset. The survey includes results for 229 countries and more than 2000 subnational units. The results are compared to reported electrification rates for 87 countries compiled from a variety of sources by the International Energy Agency. The DMSP derived estimate of number of people worldwide who lack access to electricity is 1.62 billion, only slightly larger than the 1.58 billion estimated by the International Energy Agency.
Date: January 1, 2011
Creator: Elvidge, Christopher D.; Baugh, Kimberly E.; Sutton, Paul S.; Bhaduri, Budhendra L; Tuttle, Benjamin T.; Ghosh, Tilottama et al.
System: The UNT Digital Library
Cyber Security and Information Intelligence Research Workshop (CSIIRW'11) Proceedings (open access)

Cyber Security and Information Intelligence Research Workshop (CSIIRW'11) Proceedings

The energy industry is embarking upon an infrastructure transformation that will result in a national power grid that is more intelligent, robust, resilient, and secure. While the final form will not be known for quite some time, clearly a smarter grid will make better use of information. Whether an electric utility is making real-time adjustments in response to changing load conditions, or commercial and private consumers are making better choices, the timely availability of this information will become increasingly critical. Ultimately, the overall efficiency, reliability, and resilience of the grid is inextricably linked to information. Unfortunately, "the electric power sector is second from the bottom of all major U.S. industries in terms of R&D spending as a percentage of revenue, exceeding only pulp and paper [Amin2011]." Moreover, U.S. officials worry that cyber-spies could use their [demonstrated] access to shut down the grid or take control of power plants during a time of crisis or war [CIO09, WSJ09]. Moreover, Massachusetts Institute of Technology (MIT) released the results of a two-year study, The Future of the Electric Grid.
Date: January 1, 2011
Creator: Sheldon, Frederick T; Abercrombie, Robert K & Krings, Axel
System: The UNT Digital Library
Comparative assessment of status and opportunities for carbon Dioxide Capture and storage and Radioactive Waste Disposal In North America (open access)

Comparative assessment of status and opportunities for carbon Dioxide Capture and storage and Radioactive Waste Disposal In North America

Aside from the target storage regions being underground, geologic carbon sequestration (GCS) and radioactive waste disposal (RWD) share little in common in North America. The large volume of carbon dioxide (CO{sub 2}) needed to be sequestered along with its relatively benign health effects present a sharp contrast to the limited volumes and hazardous nature of high-level radioactive waste (RW). There is well-documented capacity in North America for 100 years or more of sequestration of CO{sub 2} from coal-fired power plants. Aside from economics, the challenges of GCS include lack of fully established legal and regulatory framework for ownership of injected CO{sub 2}, the need for an expanded pipeline infrastructure, and public acceptance of the technology. As for RW, the USA had proposed the unsaturated tuffs of Yucca Mountain, Nevada, as the region's first high-level RWD site before removing it from consideration in early 2009. The Canadian RW program is currently evolving with options that range from geologic disposal to both decentralized and centralized permanent storage in surface facilities. Both the USA and Canada have established legal and regulatory frameworks for RWD. The most challenging technical issue for RWD is the need to predict repository performance on extremely long time scales …
Date: July 22, 2011
Creator: Oldenburg, C. & Birkholzer, J.T.
System: The UNT Digital Library
A View on Future Building System Modeling and Simulation (open access)

A View on Future Building System Modeling and Simulation

This chapter presents what a future environment for building system modeling and simulation may look like. As buildings continue to require increased performance and better comfort, their energy and control systems are becoming more integrated and complex. We therefore focus in this chapter on the modeling, simulation and analysis of building energy and control systems. Such systems can be classified as heterogeneous systems because they involve multiple domains, such as thermodynamics, fluid dynamics, heat and mass transfer, electrical systems, control systems and communication systems. Also, they typically involve multiple temporal and spatial scales, and their evolution can be described by coupled differential equations, discrete equations and events. Modeling and simulating such systems requires a higher level of abstraction and modularisation to manage the increased complexity compared to what is used in today's building simulation programs. Therefore, the trend towards more integrated building systems is likely to be a driving force for changing the status quo of today's building simulation programs. Thischapter discusses evolving modeling requirements and outlines a path toward a future environment for modeling and simulation of heterogeneous building systems.A range of topics that would require many additional pages of discussion has been omitted. Examples include computational fluid dynamics …
Date: April 1, 2011
Creator: Wetter, Michael
System: The UNT Digital Library
On the Computation of Integral Curves in Adaptive Mesh Refinement Vector Fields (open access)

On the Computation of Integral Curves in Adaptive Mesh Refinement Vector Fields

Integral curves, such as streamlines, streaklines, pathlines, and timelines, are an essential tool in the analysis of vector field structures, offering straightforward and intuitive interpretation of visualization results. While such curves have a long-standing tradition in vector field visualization, their application to Adaptive Mesh Refinement (AMR) simulation results poses unique problems. AMR is a highly effective discretization method for a variety of physical simulation problems and has recently been applied to the study of vector fields in flow and magnetohydrodynamic applications. The cell-centered nature of AMR data and discontinuities in the vector field representation arising from AMR level boundaries complicate the application of numerical integration methods to compute integral curves. In this paper, we propose a novel approach to alleviate these problems and show its application to streamline visualization in an AMR model of the magnetic field of the solar system as well as to a simulation of two incompressible viscous vortex rings merging.
Date: June 27, 2011
Creator: Deines, Eduard; Weber, Gunther H.; Garth, Christoph; Van Straalen, Brian; Borovikov, Sergey; Martin, Daniel F. et al.
System: The UNT Digital Library
Storage Rings (open access)

Storage Rings

Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10{sup -6} eV to 3.5 x 10{sup 12} eV (LHC, 7 x 10{sup 12} eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic …
Date: January 1, 2011
Creator: Fischer, W.
System: The UNT Digital Library
Vibration Control in Accelerators (open access)

Vibration Control in Accelerators

In the vast majority of accelerator applications, ground vibration amplitudes are well below tolerable magnet jitter amplitudes. In these cases, it is necessary and sufficient to design a rigid magnet support structure that does not amplify ground vibration. Since accelerator beam lines are typically installed at an elevation of 1-2m above ground level, special care has to be taken in order to avoid designing a support structure that acts like an inverted pendulum with a low resonance frequency, resulting in untolerable lateral vibration amplitudes of the accelerator components when excited by either ambient ground motion or vibration sources within the accelerator itself, such as cooling water pumps or helium flow in superconducting magnets. In cases where ground motion amplitudes already exceed the required jiter tolerances, for instance in future linear colliders, passive vibration damping or active stabilization may be considered.
Date: January 1, 2011
Creator: Montag, C.
System: The UNT Digital Library
Stochastic Cooling (open access)

Stochastic Cooling

Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.
Date: January 1, 2011
Creator: Blaskiewicz, M.
System: The UNT Digital Library
Topological Cacti: Visualizing Contour-based Statistics (open access)

Topological Cacti: Visualizing Contour-based Statistics

Contours, the connected components of level sets, play an important role in understanding the global structure of a scalar field. In particular their nestingbehavior and topology-often represented in form of a contour tree-have been used extensively for visualization and analysis. However, traditional contour trees onlyencode structural properties like number of contours or the nesting of contours, but little quantitative information such as volume or other statistics. Here we use thesegmentation implied by a contour tree to compute a large number of per-contour (interval) based statistics of both the function defining the contour tree as well asother co-located functions. We introduce a new visual metaphor for contour trees, called topological cacti, that extends the traditional toporrery display of acontour tree to display additional quantitative information as width of the cactus trunk and length of its spikes. We apply the new technique to scalar fields ofvarying dimension and different measures to demonstrate the effectiveness of the approach.
Date: May 26, 2011
Creator: Weber, Gunther H.; Bremer, Peer-Timo & Pascucci, Valerio
System: The UNT Digital Library
Going Extreme For Small Solutions To Big Environmental Challenges (open access)

Going Extreme For Small Solutions To Big Environmental Challenges

This chapter is devoted to the scale, scope, and specific issues confronting the cleanup and long-term disposal of the U.S. nuclear legacy generated during WWII and the Cold War Era. The research reported is aimed at complex microbiological interactions with legacy waste materials generated by past nuclear production activities in the United States. The intended purpose of this research is to identify cost effective solutions to the specific problems (stability) and environmental challenges (fate, transport, exposure) in managing and detoxifying persistent contaminant species. Specifically addressed are high level waste microbiology and bacteria inhabiting plutonium laden soils in the unsaturated subsurface.
Date: March 31, 2011
Creator: Bagwell, Christopher E.
System: The UNT Digital Library
Composite Materials under Extreme Radiation and Temperature Environments of the Next Generation Nuclear Reactors (open access)

Composite Materials under Extreme Radiation and Temperature Environments of the Next Generation Nuclear Reactors

In the nuclear energy renaissance, driven by fission reactor concepts utilizing very high temperatures and fast neutron spectra, materials with enhanced performance that exceeds are expected to play a central role. With the operating temperatures of the Generation III reactors bringing the classical reactor materials close to their performance limits there is an urgent need to develop and qualify new alloys and composites. Efforts have been focused on the intricate relations and the high demands placed on materials at the anticipated extreme states within the next generation fusion and fission reactors which combine high radiation fluxes, elevated temperatures and aggressive environments. While nuclear reactors have been in operation for several decades, the structural materials associated with the next generation options need to endure much higher temperatures (1200 C), higher neutron doses (tens of displacements per atom, dpa), and extremely corrosive environments, which are beyond the experience on materials accumulated to-date. The most important consideration is the performance and reliability of structural materials for both in-core and out-of-core functions. While there exists a great body of nuclear materials research and operating experience/performance from fission reactors where epithermal and thermal neutrons interact with materials and alter their physio-mechanical properties, a process that …
Date: May 1, 2011
Creator: Simos, N.
System: The UNT Digital Library