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Full-Text Articles in Physical Sciences and Mathematics

Polymeric Carbon Nanocomposites - Preparation, Characterization, And Properties, Lucia Veca Dec 2009

Polymeric Carbon Nanocomposites - Preparation, Characterization, And Properties, Lucia Veca

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Excellent thermal properties of carbon nanomaterials such as carbon nanotubes and newly discovered graphene make them the filler of choice for the development of thermal management materials. Graphene has been viewed as “ unrolled single-walled carbon nanotube and as a wonder material with many superlatives to its name ” thus there is an excessive interest in developing new synthetic routes towards large scale production of high quality graphene nanosheets.
In this dissertation, we report different methods that could further exfoliate the commercially available expanded graphite to nanometer sized carbon structures, “carbon nanosheets ”, for their use in highly thermal conductive …


Decoding Of Multipoint Algebraic Geometry Codes Via Lists, Nathan Drake Dec 2009

Decoding Of Multipoint Algebraic Geometry Codes Via Lists, Nathan Drake

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Algebraic geometry codes have been studied greatly since their introduction by Goppa . Early study had focused on algebraic geometry codes CL(D;G) where G was taken to be a multiple of a single point. However, it has been shown that if we allow G to be supported by more points, then the associated code may have better parameters. We call such a code a multipoint code and if G is supported by m points, then we call it an m-point code. In this dissertation, we wish to develop a decoding algorithm for multipoint codes. We show how we can embed …


Synthesis, Modification Of Mesoporous Carbons And Their Application In Polymer Electrolyte Membrane Fuel Cells, Bing Liu Dec 2009

Synthesis, Modification Of Mesoporous Carbons And Their Application In Polymer Electrolyte Membrane Fuel Cells, Bing Liu

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Mesoporous carbon materials of carbon xerogel (CX) and silica-templated carbon (MC) were synthesized and explored as catalyst supports alternative to the most-commonly-used carbon black (CB) support, for polymer-electrolyte-membrane fuel cell (PEMFC) application. Pt catalyst was loaded on these carbons and electrodes were fabricated from them. These Pt-loaded carbon supports were characterized with XRD, TEM, ex-situ and in-situ cyclic voltammetry, etc. The fabricated electrodes were evaluated in single-cell testing in comparison with commercial CB-supported Pt catalyst fabricated electrodes. The experimental results showed that CX-supported Pt catalyst had close or better performance than that of CB-supported Pt, possibly due to CX's 3-D …


Metal Oxide And Mercuric Sulfide Nanoparticles Synthesis And Characterization, Xin Xu Dec 2009

Metal Oxide And Mercuric Sulfide Nanoparticles Synthesis And Characterization, Xin Xu

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Increasing applications of nanoparticles (NPs), such as metal oxide and mercuric sulfide NPs, lead to heightened environmental concern. Challenges to the study of natural and engineered NPs include the physical and chemical characterizations.
Commercially available and laboratory-synthesized metal based NPs, iron oxide (Fe2O3), copper oxide (CuO), titanium dioxide (TiO2), zinc oxide (ZnO) and mercuric sulfide (HgS) were studied by comprehensive characterizations methods. The general synthesis process was modified sol-gel method. The size and morphology of NPs could be influenced by temperature, sonication, calcination, precursor concentration, pH and types of reaction media. In the synthesis of nZnO in ethanol, the essential …


Atom Scattering From Metals, William Hayes Dec 2009

Atom Scattering From Metals, William Hayes

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In the initial portion of this dissertation studies of Ar
scattering from Ru(0001) at thermal and hyperthermal energies are
compared to calculations with classical scattering theory. These
data exhibited a number of characteristics that are unusual in
comparison to other systems for which atomic beam experiments have
been carried out under similar conditions. The measured energy
losses were unusually small. Some of the angular distributions
exhibited an anomalous shoulder feature in addition to a broad
peak near the specular direction and quantum mechanical
diffraction was observed under conditions for which it was not
expected. Many of the unusual features observed …


Visuohaptic Simulation Of A Borescope For Aircraft Engine Inspection, Deepak Vembar Dec 2009

Visuohaptic Simulation Of A Borescope For Aircraft Engine Inspection, Deepak Vembar

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Consisting of a long, fiber optic probe containing a small CCD camera controlled by hand-held articulation interface, a video borescope is used for remote visual inspection of hard to reach components in an aircraft. The knowledge and psychomotor skills, specifically the hand-eye coordination, required for effective inspection are hard to acquire through limited exposure to the borescope in aviation maintenance schools. Inexperienced aircraft maintenance technicians gain proficiency through repeated hands-on learning in the workplace along a steep learning curve while transitioning from the classroom to the workforce.
Using an iterative process combined with focused user evaluations, this dissertation details the …


Synthesis And Development Of Novel Fullerene-Based Structures For Photovoltaics, Electronic Applications And Mri Contrast Agents, Manuel Chaur Dec 2009

Synthesis And Development Of Novel Fullerene-Based Structures For Photovoltaics, Electronic Applications And Mri Contrast Agents, Manuel Chaur

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Metallic nitride endohedral metallofullerenes (EMFs) are one of the most interesting types of metallofullerenes due to their high yields and interesting electronic properties. The synthesis of these compounds allows the encapsulation of different metals inside fullerenes making it possible to combine the properties of the metal with those of the fullerene. Their interesting electrochemical and optical features make them potential candidates for several applications such as molecular electronics, biomedical imaging, non-linear optical devices, and magnetic resonance imaging (MRI) agents. This thesis reports the synthesis of novel metallic nitride EMFs based on Gd, Nd, Pr, Ce and La. These families of …


Examining The Dynamics Of Managing Information Systems Development Projects: A Control Loss Perspective, Ravi Narayanaswamy Dec 2009

Examining The Dynamics Of Managing Information Systems Development Projects: A Control Loss Perspective, Ravi Narayanaswamy

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The failure rate of information systems development (ISD) projects continues to pose a big challenge for organizations. The success rate of ISD projects is less then forty percent. Factors such as disagreements and miscommunications among project manager and team members, poor monitoring and intermediary problems contribute to project failure.
Agency theory and leader member exchange (LMX) theories offer potential explanations for project failure. In particular, three monitoring strategies - control strategy, decision rights, and influence tactics were found to be effective in promoting project success. LMX theorists suggest that achieving congruence between the manager and subordinate regarding each other actions …


Characterization Of Escherichia Coli Related To Construction Site Sediment Basins, Calvin Sawyer Dec 2009

Characterization Of Escherichia Coli Related To Construction Site Sediment Basins, Calvin Sawyer

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Large construction sites can have significant temporary and permanent impacts on the physical landscape. Excess sediment is frequently deposited into nearby surface waters, altering benthic habitat, reducing water clarity and transporting other pollutants such as enteric bacteria. To capture eroded soil and attenuate storm discharge peaks, many permitted construction projects larger than 10 acres in South Carolina require the installation of a sediment basin. Sediment-laden runoff is routed to a newly excavated impoundment, where larger particles settle out of suspension. Thus an entirely new hydrologic feature designed to concentrate eroded sediment and water is introduced into the landscape.
Eight construction …


Branchings And Time Evolution Of Reaction Networks, Changyuan Wang Dec 2009

Branchings And Time Evolution Of Reaction Networks, Changyuan Wang

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In this thesis I analyze flows in reaction networks in terms of branchings
in a digraph. If the coupled differential equations governing the rate
of change of probabilities X of a state or species are finite-differenced in time, a matrix equation (I + Adt)X(t+dt) = X(t) results, where X(t) is a vector giving the probabilities at time t and X(t+dt) is a vector giving the probabilities at time t + dt. I demonstrate that the matrix (I + Adt) may be written as the product of an incidence matrix and a weight matrix for a directed graph (digraph) representing the …


Synthesis And Characterization Of Metallic, Core-Shell And Composite Nanoparticles, Amar Kumbhar Dec 2009

Synthesis And Characterization Of Metallic, Core-Shell And Composite Nanoparticles, Amar Kumbhar

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ABSTRACT
Silver nanoparticles exhibit size, shape and the surrounding dielectric medium dependent optical properties (scattering and absorption) in the visible spectral region. These optical properties can be explained in terms of the collective oscillation of the 'free conduction band electrons' or 'surface plasmons' induced by an external electromagnetic field. Dipole and Quadrupole Plasmon resonances have been observed for silver particles less than 100nm in diameter prepared using various synthetic techniques. However higher order resonances have been elusive due to lack of experimental techniques to prepare colloidal solutions of large silver nanoparticles in the size range above 100nm. Controlled hydrogen reduction …


Development Of A Fluorescent Probe For Determination Of Water Transport In Subcellular Organelles, Adriana Chaurra-Arboleda Dec 2009

Development Of A Fluorescent Probe For Determination Of Water Transport In Subcellular Organelles, Adriana Chaurra-Arboleda

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Water transport has been widely studied in a variety of cells and isolated membranes. However, the intrinsic complexity related with the study of intracellular processes has delayed the development of an analytical technique for the study of water transport in subcellular compartments of living cells. This study represents the development and application of a ratiometric fluorescent probe to study water transport in endocytic organelles of intact living cells. The probe is based on the use of a D2O-sensitive fluorophore, Lucifer yellow dextran (LY-dex), together with a D2O-insensitive fluorophore, Alexa fluor 546 dextran (AF546-dex), used as an …


Functional Characterization Of Calcium Dependent Protein Kinase 32 From Arabidopsis, Rucha Karve Dec 2009

Functional Characterization Of Calcium Dependent Protein Kinase 32 From Arabidopsis, Rucha Karve

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Calcium-dependent protein kinases (CPKs) are major plant Ca2+ sensors, many of which have roles in plant stress responses. The Arabidopsis genome encodes 34 CPK isoforms. Here we report characterization of AtCPK32 gene function. Analysis of transgenic plants expressing pCPK32-GUS shows that CPK32 is highly expressed in roots, pollen and embryo, as well as leaf hydathodes, and the abscission zone of mature siliques. Real time RT-PCR and promoter expression patterns show that CPK32 is responsive to abiotic and biotic stresses. Plants treated with salt, ABA, osmotic stress (PEG), wounding, and flagellin 22 peptide show up-regulation of CPK32 upon these stress treatments. …


An Approach Designed For Reginal Prospective Human Health And Ecological Risk Assessment And Its Application To Mercury Risks From A Coal-Fired Power Plant, Pathratipa Sansayavichai Dec 2009

An Approach Designed For Reginal Prospective Human Health And Ecological Risk Assessment And Its Application To Mercury Risks From A Coal-Fired Power Plant, Pathratipa Sansayavichai

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A large and/or long-term released source of a toxic chemical(s) can cause adverse effects to humans and non–human species inhabiting all over the region. The overall goal of this dissertation was to improve practices in risk assessment concerning a regional risk posed by a prospective source. A generic conceptual framework for performing regional prospective human health and ecological risk assessment was developed. The formulation of a priori considerations was used to identify the possible sources of uncertainties in the prospective risk assessment. Physiologically based pharmacokinetic (PBPK) modeling was utilized to reduce uncertainty in a toxicologically safe dose used in risk …


Observations Of Very High Energy Gamma-Ray Emission From Supernova Remnants With Veritas, Mark Theiling Dec 2009

Observations Of Very High Energy Gamma-Ray Emission From Supernova Remnants With Veritas, Mark Theiling

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The nature and source of cosmic rays has been at the core of particle astrophysics since their discovery almost a century ago. The cosmic ray spectrum is best described by a broken power law, and can be better understood as three distinct parts. Theory holds that cosmic rays up to ∼1015 eV – those below the “knee” or steepening in the spectrum – are produced in the shocks of supernova remnants. Direct detection of cosmic rays produced in supernova remnant shocks is impossible, however, as cosmic rays below ∼1018 eV are deflected by the Galactic magnetic field and cannot be …


A Cognitive Model For Problem Solving In Computer Science, Jennifer Parham Dec 2009

A Cognitive Model For Problem Solving In Computer Science, Jennifer Parham

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According to industry representatives, computer science education needs to emphasize the processes involved in solving computing problems rather than their solutions. Most of the current assessment tools used by universities and computer science departments analyze student answers to problems rather than investigating the processes involved in solving them. Approaching assessment from this perspective would reveal potential errors leading to incorrect solutions.
This dissertation proposes a model describing how people solve computational problems by storing, retrieving, and manipulating information and knowledge. It describes how metacognition interacts with schemata representing conceptual and procedural knowledge, as well as with the external sources of …


Some New Problems In Changepoint Analysis, Jonathan Woody Dec 2009

Some New Problems In Changepoint Analysis, Jonathan Woody

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Climatological studies have often neglected changepoint effects when modeling
various physical phenomena. Here, changepoints are plausible whenever a station location moves or its instruments are changed. There is frequently meta-data to
perform sound statistical inferences that account for changepoint
information. This dissertation focuses on two such problems in changepoint analysis.
The first problem we investigate involves assessing trends
in daily snow depth series. Here, we introduce a stochastic storage model. The model allows for seasonal features, which permits the
analysis of daily data. Changepoint times are shown to greatly influence estimated trends in one snow depth series and are accounted …


On The Testing And Estimation Of High-Dimensional Covariance Matrices, Thomas Fisher Dec 2009

On The Testing And Estimation Of High-Dimensional Covariance Matrices, Thomas Fisher

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Many applications of modern science involve a large number of parameters. In
many cases, the number of parameters, p, exceeds the number of observations,
N. Classical multivariate statistics are based on the assumption that the
number of parameters is fixed and the number of observations is large. Many of
the classical techniques perform poorly, or are degenerate, in high-dimensional
situations.
In this work, we discuss and develop statistical methods for inference of
data in which the number of parameters exceeds the number of observations.
Specifically we look at the problems of hypothesis testing regarding and the
estimation of the covariance …


Field Evaluation Of The Immunocontraceptive Gonacontm In Reducing Eastern Gray Squirrel Fecundity In Urban Areas, Murali Pai Dec 2009

Field Evaluation Of The Immunocontraceptive Gonacontm In Reducing Eastern Gray Squirrel Fecundity In Urban Areas, Murali Pai

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The purpose of this study was to evaluate the immunocontraceptive GonaConTM in reducing fecundity in Eastern gray squirrel (EGS) (Sciurus carolinensis) in urban areas. Using a modified box trap design, 317 EGS were captured during four trapping sessions on a 5.66 ha site on Clemson University's main campus. EGS were handled using a restraint cone and sexed, weighed, ear-tagged and implanted with a microchip at the nape of the neck on all 'original' captures and later identified in subsequent captures as 'recaptures.' Blood samples and morphometric data were obtained on EGS before the immunocontraceptive GonaConTM was administered by …


Exploring Formation And Distribution Of Halonitromethanes In Drinking Waters, Jia Hu Dec 2009

Exploring Formation And Distribution Of Halonitromethanes In Drinking Waters, Jia Hu

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ABSTRACT
Nine halonitromethanes (HNMs) were among the more than fifty unregulated high-priority disinfection by-products (DBPs) that were monitored for and detected in drinking waters in a 2000-2002 nationwide occurrence study funded by the US Environmental Protection Agency (USEPA). The toxicology studies conducted in recent years have shown that HNMs are one of the most cytotoxic and genotoxic classes among the emerging DBPs, with orders of magnitude higher cytotoxicity and genotoxicity than any of the regulated organic DBPs. Furthermore, brominated HNMs were found to be more toxic than their chlorinated analogs, with dibromonitromethane being the most cyto- and genotoxic. Today, our …


Variations On Graph Products And Vertex Partitions, Jobby Jacob Aug 2009

Variations On Graph Products And Vertex Partitions, Jobby Jacob

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In this thesis we investigate two graph products called double vertex graphs and complete double vertex graphs, and two vertex partitions called dominator partitions and rankings.
We introduce a new graph product called the complete double vertex graph and study its properties. The complete double vertex graph is a natural extension of the Cartesian product and a generalization of the double vertex graph.
We establish many properties of complete double vertex graphs, including results involving the chromatic number of a complete double vertex graph and the characterization of planar complete double vertex graphs. We also investigate the important problem of …


Fast Rendering Of Forest Ecosystems With Dynamic Global Illumination, Jay Steele Aug 2009

Fast Rendering Of Forest Ecosystems With Dynamic Global Illumination, Jay Steele

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Real-time rendering of large-scale, forest ecosystems remains
a challenging problem, in that important global illumination effects,
such as leaf transparency and inter-object light scattering, are
difficult to capture, given tight timing constraints and scenes
that typically contain hundreds of millions of primitives.
We propose a new lighting model, adapted from
a model previously used to light convective clouds and other
participating media,
together with GPU ray tracing, in order to achieve these global illumination
effects while maintaining near real-time performance. The lighting
model is based on a lattice-Boltzmann method in which
reflectance, transmittance, and absorption parameters are
taken from measurements …


Factoring Polynomials And Groebner Bases, Genhua (Yinhua) Guan Aug 2009

Factoring Polynomials And Groebner Bases, Genhua (Yinhua) Guan

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Factoring polynomials is a central problem in computational algebra and number theory and is a basic routine in most
computer algebra systems (e.g. Maple, Mathematica, Magma, etc). It has been extensively studied
in the last few decades by many mathematicians and computer scientists. The main approaches include Berlekamp's method
(1967) based on the kernel of Frobenius map, Niederreiter's method (1993) via an ordinary differential equation,
Zassenhaus's modular approach (1969), Lenstra, Lenstra and Lovasz's lattice reduction (1982), and Gao's method via a partial differential equation (2003). These methods and their recent improvements due to van Hoeij (2002) and
Lecerf et al …


Synthesis And Characterization Of Magnetic Solids Containing Periodic Arrays Of Transition Metal Oxide Nanostructures, Wendy Queen Aug 2009

Synthesis And Characterization Of Magnetic Solids Containing Periodic Arrays Of Transition Metal Oxide Nanostructures, Wendy Queen

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The ultimate goal of the research presented in this dissertation was to explore new systems containing low–dimensional magnetic nanostructures in hopes of finding new extended solids exhibiting novel magnetic properties due to the confined magnetic lattices. The scope of this research is threefold: 1) to explore new solids containing low–dimensional magnetic nanostructures in the A–M–X–O system, where A is an alkali or alkalinendash;earth metal cation, M is a first–row transition metal cation, and X is P, As, or V, 2) to characterize these new materials and, through chemical substitution, fine tune (and optimize) magnetic and electronic properties of solids that …


Asymptotics Of Families Of Polynomials And Sums Of Hurwitz Class Numbers, Timothy Flowers Aug 2009

Asymptotics Of Families Of Polynomials And Sums Of Hurwitz Class Numbers, Timothy Flowers

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In a note in the American Mathematical Monthly in 1960, Strodt mentions a way to prove both the Euler-Maclaurin summation formula and the Boole summation formula using operators. In a 2009 article in the Monthly, Borwein, Calkin, and Manna expand on this idea. Therein, they define Strodt operators and Strodt polynomials and show that the classical Bernoulli polynomials and Euler polynomials are examples of Strodt polynomials.
It is well known that both Bernoulli polynomials and Euler polynomials on a fixed interval are asymptotically sinusoidal. Borwein, Calkin, and Manna show that a similar result holds for the uniform Strodt polynomials. We …


Discrete Dynamics Over Finite Fields, Jang-Woo Park Aug 2009

Discrete Dynamics Over Finite Fields, Jang-Woo Park

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A dynamical system consists of a set V and a map f : V → V . The primary goal is to characterize points in V according to their limiting behaviors under iteration of the map f . Especially understanding dynamics of nonlinear maps is an important but difficult problem, and there are not many methods available. This work concentrates on dynamics of certain nonlinear maps over finite fields. First we study monomial dynamics over finite fields. We show that determining the number of fixed points of a boolean monomial dynamics is #P–complete problem and consider various cases in which …


Improved Thermoelectric Performance Of P-Type Polycrystalline Bi2te3 Via Hydrothermal Treatment With Alkali Metal Salts, Zhe Su Aug 2009

Improved Thermoelectric Performance Of P-Type Polycrystalline Bi2te3 Via Hydrothermal Treatment With Alkali Metal Salts, Zhe Su

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The field of thermoelectric research has attracted a lot of interest in hope of helping address the energy crisis. In recent years, low-dimensional thermoelectric materials have been found promising and thus become a popular school of thought. However, the high complexity and cost for fabricating low-dimensional materials give rise to the attempt to further improve conventional bulk polycrystalline materials. Polycrystals are featured by numerous grain boundaries that can scatter heat-carrying phonons to significantly reduce the thermal conductivity κ whereas at the same time can unfortunately deteriorate the electrical resistivity ρ. Aiming at the dualism of the grain boundaries in determining …


Understanding The Antioxidant Mechanism Of Inorganic Selenium, Oxo- Sulfur, And Polyphenol Compounds, And The Biological Implications Of Functionalized Nanoparticles, Ria Ramoutar Aug 2009

Understanding The Antioxidant Mechanism Of Inorganic Selenium, Oxo- Sulfur, And Polyphenol Compounds, And The Biological Implications Of Functionalized Nanoparticles, Ria Ramoutar

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Inorganic selenium, oxo-sulfur, and polyphenol compounds are found in foods and dietary supplements, and are recognized for their nutritional benefits and their potential to treat or prevent diseases caused by oxidative stress. In our experiments to determine the effects of inorganic selenium compounds on iron-mediated DNA damage, Na2SeO33 and SeO2 exhibit antioxidant and pro-oxidant activities depending on concentrations of both the compound and hydrogen peroxide. Additional experiments demonstrate that iron coordination is a novel mechanism responsible for the observed activities. In similar experiments, oxo-sulfur compounds prevent Cu+/ H2O2-mediated DNA damage significantly …


Effect Of Cosb3 Nanoparticles On The Thermoelectric Properties Of Filled And Unfilled Cosb3 Skutterudites, Paola Alboni Aug 2009

Effect Of Cosb3 Nanoparticles On The Thermoelectric Properties Of Filled And Unfilled Cosb3 Skutterudites, Paola Alboni

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This study explores the possibility of somewhat decoupling the electrical and thermal conduction, thereby being able to limit the thermal conduction while minimizing the effect on the electrical conduction. The approach is using a nanoparticle layer with a slight compositional mismatch as compared to the bulk skutterudite. A hydrothermal nanoparticle-plating technique has been employed to grow a layer of CoSb3 nanoparticles on the surface of skutterudite bulk matrix grains. Skutterudites of various forms were fabricated and studied in order to assess the effect of this nano-plated layer as a viable method in the improvement of thermoelectric properties of CoSb …


A Study Of Client-Based Caching For Parallel I/O, Bradley Settlemyer Aug 2009

A Study Of Client-Based Caching For Parallel I/O, Bradley Settlemyer

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The trend in parallel computing toward large-scale cluster computers running thousands of cooperating processes per application has led to an I/O bottleneck that has only gotten more severe as the the number of processing cores per CPU has increased. Current parallel file systems are able to provide high bandwidth file access for large contiguous file region accesses; however, applications repeatedly accessing small file regions on unaligned file region boundaries continue to experience poor I/O throughput due to the high overhead associated with accessing parallel file system data.
In this dissertation we demonstrate how client-side file data caching can improve parallel …