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2008

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Articles 7051 - 7080 of 7321

Full-Text Articles in Physical Sciences and Mathematics

Arctic Perennial Ice Cover Over The Last 14 Million Years, Dennis A. Darby Jan 2008

Arctic Perennial Ice Cover Over The Last 14 Million Years, Dennis A. Darby

OES Faculty Publications

Knowledge of the long-term history of the perennial ice is an important issue that has eluded study because the Cenozoic core material needed has been unavailable until the recent Arctic Coring Expedition (ACEX). Detrital Fe oxide mineral grains analyzed by microprobe from the last 14 Ma (164 m) of the ACEX composite core on the Lomonosov Ridge were matched to circum-Arctic sources with the same mineral and 12-element composition. These precise source determinations and estimates of drift rates were used to determine that these sand grains could not be rafted to the ACEX core site in less than a year. …

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Impacts Of Chromophoric Dissolved Organic Material On Surface Ocean Heating In The Chukchi Sea, Victoria J. Hill Jan 2008

Impacts Of Chromophoric Dissolved Organic Material On Surface Ocean Heating In The Chukchi Sea, Victoria J. Hill

OES Faculty Publications

Recent observations show visible light attenuation in the Arctic Ocean to be greater than previously assumed. High attenuation observed during the period prior to ice melt and increased phytoplankton production, was attributed primarily to the high levels of absorption by chromophoric dissolved organic material ( CDOM) present in these waters. Preliminary evidence suggests this material is produced by ice algae in the early spring. Optical data from the Chukchi shelf system collected in the spring and summer of 2002, were used to model energy absorption in the mixed layer by both dissolved and particulate material. In the spring, absorption by …

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The Identification And Characterization Of Phenylalanine Ammonia-Lyase Gene Family Members In Glycine Max, Erin Kathleen Pringle Jan 2008

The Identification And Characterization Of Phenylalanine Ammonia-Lyase Gene Family Members In Glycine Max, Erin Kathleen Pringle

Masters Theses

"Gene families are collections of genes with similar functions. Studying gene families is important for understanding the evolution of genes and manipulating genes. Phenylalanine ammonia-lyase (PAL) is an enzyme found in plants. It catalyzes the deamination of phenylalanine to produce cinnamic acid. Genes for PAL have been identified in many different plant species. This project used the known sequence for the PAL1 gene in Glycine max to find other PAL genes in Glycine max"--Abstract, page iii.

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Preserd - Privacy Ensured Service Discovery In Mobile Peer-To-Peer Environment, Santhosh Muthyapu Jan 2008

Preserd - Privacy Ensured Service Discovery In Mobile Peer-To-Peer Environment, Santhosh Muthyapu

Masters Theses

"In mobile peer-to-peer networks many service discovery protocols have been proposed. Most of these protocols disregard the exposure of the participating peers' privacy details, although they consider the security issues. In these methods, the participating peers must provide their identities, during the service discovery process, to be authorized to utilize the service. However, a peer might not be willing to reveal its identity until it identifies the service providing peer. So these peers face a problem; should the requesting peer or the service providing peer reveal the identity first, and hence, this is similar to the chicken-and-egg problem. The protocol …

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A Rapid Method For Determination Of Alpha Hydroxy Acids In Seawater And Biological Fluids At Trace Levels, Ryan Lee Schwiderski Jan 2008

A Rapid Method For Determination Of Alpha Hydroxy Acids In Seawater And Biological Fluids At Trace Levels, Ryan Lee Schwiderski

Masters Theses

"Alpha hydroxy acids (AHAs) - carboxylic acids with a hydroxyl substitution on the alpha carbon are an important class of molecules. Hydroxy Methyl Thiobutanoic Acid (HMTBA) is an α-hydroxy analog of essential amino acid methionine; it finds extensive use as a feed supplement for avian and bovine species. Efficacy of alpha hydroxy acid uptake is important for nutritional studies and such studies rely on accurate and precise methods for determination of these chemicals in biological samples. Several methods for AHAs determination have been reported, however, the methods are tedious, requiring multiple sample preparation steps. Experiments reported in this thesis were …

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Emergent Behavior In Massively-Deployed Sensor Networks, Ekaterina Shurkova, Ruzana Ishak, Stephan Olariu, Shaharuddin Salleh Jan 2008

Emergent Behavior In Massively-Deployed Sensor Networks, Ekaterina Shurkova, Ruzana Ishak, Stephan Olariu, Shaharuddin Salleh

Computer Science Faculty Publications

The phenomenal advances in MEMS and nanotechnology make it feasible to build small devices, referred to as sensors that are able to sense, compute and communicate over small distances. The massive deployment of these small devices raises the fascinating question of whether or not the sensors, as a collectivity, will display emergent behavior, just as living organisms do. In this work we report on a recent effort intended to observe emerging behavior of large groups of sensor nodes, like living cells demonstrate. Imagine a massive deployment of sensors that can be in two states "red" and "blue". At deployment time …

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Timing And Nature Of Post-Collapse Sedimentation In Kulshan Caldera, North Cascades, Washington, Dennis M. (Dennis Martin) Feeney Jan 2008

Timing And Nature Of Post-Collapse Sedimentation In Kulshan Caldera, North Cascades, Washington, Dennis M. (Dennis Martin) Feeney

WWU Graduate School Collection

Sedimentary rocks found in the 4.5 x 8 km Kulshan caldera of the Mount Baker volcanic field in the North Cascades, WA, indicate that the post-collapse basin hosted a lacustrine environment shortly after the initial collapse at 1.149 Ma (Hildreth, 1996). The sedimentary rocks of the 14 Goat area in Kulshan caldera are well-preserved in 124 meters of stratigraphic exposure. Blocks of wall rock debris in the lower stratigraphy show instability in the caldera wall. Intermediate and late stages are mainly turbidites composed primarily of sediments derived from extra-caldera ignimbrite. From these 1 interpret the 14 Goat area of Kulshan …

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Nanocomposites For Novel Holographic Applications, Izabela Naydenova, Svetlana Mintova, Suzanne Martin, Vincent Toal Jan 2008

Nanocomposites For Novel Holographic Applications, Izabela Naydenova, Svetlana Mintova, Suzanne Martin, Vincent Toal

Articles

Nanozeolites incorporated into photopolymerizable holographic recording materials can be used for holographic sensing, data storage, and optical systems design.

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A Growth-Theoretic Empirical Analysis Of Simultaneity In Cross-National E-Commerce Development, Shu-Chun Ho, Robert J. Kauffman, Ting-Peng Liang Jan 2008

A Growth-Theoretic Empirical Analysis Of Simultaneity In Cross-National E-Commerce Development, Shu-Chun Ho, Robert J. Kauffman, Ting-Peng Liang

Research Collection School Of Computing and Information Systems

The emergence of information and communication technologies infrastructure has transformed the global economy. The development of information technology infrastructure is limited to some developed countries though. This research explores the role of information technology infrastructure in B2C e-commerce growth at the country-level from the perspective of growth theory in economics. We propose a hybrid exogenous and endogenous growth model to explain e-commerce growth. We estimate a panel data model that incorporates the direct effects of e-commerce infrastructure and other key explanatory variables. We further specify a simultaneous effects model that permits the analysis of reverse causality in the association between …

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Columbia University/Vireo-Cityu/Irit Trecvid2008 High-Level Feature Extraction And Interactive Video Search, Shih-Fu Chang, Junfeng He, Yu-Gang Jiang, Elie El Khoury, Chong-Wah Ngo, Akira Yanagawa, Eric Zavesky Jan 2008

Columbia University/Vireo-Cityu/Irit Trecvid2008 High-Level Feature Extraction And Interactive Video Search, Shih-Fu Chang, Junfeng He, Yu-Gang Jiang, Elie El Khoury, Chong-Wah Ngo, Akira Yanagawa, Eric Zavesky

Research Collection School Of Computing and Information Systems

In this report, we present overview and comparative analysis of our HLF detection system, which achieves the top performance among all type-A submissions in 2008. We also describe preliminary evaluation of our video search system, CuZero, in the interactive search task.

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Turbulent Lifestyle: Microbial Mats On Earth’S Sandy Beaches—Today And 3 Billion Years Ago, Nora Noffke Jan 2008

Turbulent Lifestyle: Microbial Mats On Earth’S Sandy Beaches—Today And 3 Billion Years Ago, Nora Noffke

OES Faculty Publications

Archean Earth history is very difficult to reconstruct. Until recently, only bacterial cells preserved in chert, microborings, and stromatolites provided the few clues to ancient life. Now, siliciclastic “microbially induced sedimentary structures” (MISS) are adding to our knowledge of both past life and paleoenvironments. MISS rise from the interaction of photoautotrophic microbial mats with physical sediment dynamics in siliciclastic, shallow-marine settings. Archean MISS can be understood through observations of living microbial mats and modern biotic-physical sedimentary processes. Such geobiological studies are key to the interpretation of the early evolution of prokaryotes. For example, the 2.9 Ga Pongola Supergroup, South Africa, …

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Ship Ballast Tanks: How Microbes Travel The World, Fred C. Dobbs Jan 2008

Ship Ballast Tanks: How Microbes Travel The World, Fred C. Dobbs

OES Faculty Publications

As the international shipping fleet travels the oceans, it carries with it hidden cargoes of microbes. Fred C. Dobbs explores the hazards posed and what can be done to counteract them.

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Interspecific Interactions In Oyster Reef Communities: The Effect Of Established Fauna On Oyster Larval Recruitment, Brian B. Barnes Jan 2008

Interspecific Interactions In Oyster Reef Communities: The Effect Of Established Fauna On Oyster Larval Recruitment, Brian B. Barnes

Dissertations, Theses, and Masters Projects

The behaviors of oyster larvae are difficult to monitor or experimentally manipulate, especially in field conditions. As a result, little is known of the fate of oysters in the larval portion of their life cycle, prior to recruitment. At the transition from pelagic larvae to benthic adults, larvae are likely to come into contact with many invertebrates resident on oyster reefs. Of these, fouling epifauna are generally believed to reduce the settlement of interspecific larvae through competitive exclusion and predation. Studies of these interactions, however, often utilize artificial settlement panels, which can exhibit different recruitment patterns to those observed on …

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A Modern Sediment Budget For The Continental Shelf Off The Waipaoa River, New Zealand, Andrea J. Miller Jan 2008

A Modern Sediment Budget For The Continental Shelf Off The Waipaoa River, New Zealand, Andrea J. Miller

Dissertations, Theses, and Masters Projects

No abstract provided.

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The Survival Benefit Of Benthic Macroalgae Gracilaria Vermiculophylla As An Alternative Nursery Habitat For Juvenile Blue Crabs, Justin A. Falls Jan 2008

The Survival Benefit Of Benthic Macroalgae Gracilaria Vermiculophylla As An Alternative Nursery Habitat For Juvenile Blue Crabs, Justin A. Falls

Dissertations, Theses, and Masters Projects

The Chesapeake Bay blue crab is in decline. One of the threats to it is the loss of its once plentiful nursery habitat, seagrass, due to baywide eutrophication and climate change. The emergence of the non-native benthic macroalga Gracilaria vermiculophylla may offer the blue crab an alternative nursery if it can provide juvenile crabs a refuge from predation. The ability of Gracilaria to protect juvenile blue crabs was investigated in mesocosm and field survival studies, which were combined into a larger dataset. All of these studies used tethering and therefore a tethering validation study in mesocosms accompanied these experiments. In …

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Sediment Transport And Erodibility In The York River Estuary: A Model Study, Jeffrey Paul Rinehimer Jan 2008

Sediment Transport And Erodibility In The York River Estuary: A Model Study, Jeffrey Paul Rinehimer

Dissertations, Theses, and Masters Projects

A cohesive sediment bed model was implemented in the Community Sediment Transport Modeling System (CSTMS) to examine processes influencing sediment erodibility and suspended sediment concentrations. Estimates of eroded mass from the sediment bed model were calibrated and verified with erosion chamber measurements from the York River, Virginia, a tidally-dominated environment. A constant erosion rate parameter combined with depth-varying critical shear stress was sufficient to model erosion observations of depth-limited sediment cores. Sensitivity of total eroded mass to seasonal variations in erodibility and changes in consolidation time scale was evaluated during spring-neap variations in bottom stresses. Differences were greatest during spring …

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A Bio-Economic Feasibility Model For Remote Setting: Potential For Oyster Aquaculture In Virginia, Michael Spohn Congrove Jan 2008

A Bio-Economic Feasibility Model For Remote Setting: Potential For Oyster Aquaculture In Virginia, Michael Spohn Congrove

Dissertations, Theses, and Masters Projects

No abstract provided.

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Zooplankton Community Structure In A Cyclonic And Mode-Water Eddy In The Sargasso Sea, Bethany Rose Eden Jan 2008

Zooplankton Community Structure In A Cyclonic And Mode-Water Eddy In The Sargasso Sea, Bethany Rose Eden

Dissertations, Theses, and Masters Projects

Recent evidence suggests that mesoscale eddies are an important mechanism for supplying nutrients to the surface waters of oligotrophic gyres. However, little is known about the biological response to these physical perturbations. Because mesozooplankton play a key role in food-web interactions and the flux of carbon and other elements from surface waters, changes in mesozooplankton community structure can affect biogeochemical cycling. During the summers of 2004 and 2005, respectively, we followed the development of a cyclonic eddy and an anti-cyclonic mode-water eddy in the Sargasso Sea. Zooplankton tows were conducted across both eddies using a Multiple Opening and Closing Net …

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Influences Of Habitat Conditions On Submerged Aquatic Vegetation Development In The Chickahominy River And Other Virginia Tributaries Of The Chesapeake Bay, Erin C. Shields Jan 2008

Influences Of Habitat Conditions On Submerged Aquatic Vegetation Development In The Chickahominy River And Other Virginia Tributaries Of The Chesapeake Bay, Erin C. Shields

Dissertations, Theses, and Masters Projects

Recently, there has been an expansion of submerged aquatic vegetation (SAV) in the tidal fresh and oligohaline portions of lower Chesapeake Bay tributaries. Much like the resurgence seen in the Potomac in the 1980’s, this spread of SAV in Virginia systems such as the Mattaponi, Pamunkey and Chickahominy seems to have been initiated by the introduction and spread of the invasive species Hydrilla verticillata, and appears to have been rapid. However the resurgence in the Piankatank has occurred in the absence of the introduction of this species. The factors that are influencing the growth of SAV in these tributary environments, …

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Modeling Mercury Biomagnification In The South River, Kyle R. Tom Jan 2008

Modeling Mercury Biomagnification In The South River, Kyle R. Tom

Dissertations, Theses, and Masters Projects

No abstract provided.

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Effects Of Shoreline Development And Oyster Reefs On Benthic Communities In Lynnhaven, Virginia, Amanda Sue Lawless Jan 2008

Effects Of Shoreline Development And Oyster Reefs On Benthic Communities In Lynnhaven, Virginia, Amanda Sue Lawless

Dissertations, Theses, and Masters Projects

Shoreline hardening and construction of restoration oyster reefs are occurring at rapid rates throughout Chesapeake Bay and little research has been conducted to determine whether installment of a hardened shoreline and oyster reef placement has an effect on the surrounding benthic infaunal communities. I investigated the effects of shoreline development and oyster reefs on benthic communities in Lynnhaven, Virginia. Throughout Lynnhaven, I determined the effects of shoreline type (natural marsh, oyster reef, rip-rap and bulkhead), sediment grain size, Total Organic Carbon/Total Nitrogen (TOC/TN) of the sediment, and predation (caging study) on density, biomass, and diversity of benthic infauna. An information-theoretic …

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Recent Sedimentation Patterns And Facies Distribution On The Waipaoa River Shelf, N.Z, Lila Eve Rose Jan 2008

Recent Sedimentation Patterns And Facies Distribution On The Waipaoa River Shelf, N.Z, Lila Eve Rose

Dissertations, Theses, and Masters Projects

No abstract provided.

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Acoustic Measurements Of Cohesive Sediment Transport: Suspension To Consolidation, Ho Kyung Ha Jan 2008

Acoustic Measurements Of Cohesive Sediment Transport: Suspension To Consolidation, Ho Kyung Ha

Dissertations, Theses, and Masters Projects

This dissertation aims at utilizing the acoustic approach to measure cohesive sediment behaviors including (1) suspension, (2) settling, (3) deposition and (4) consolidation. The first two processes were attempted to interpret by means of backscattered signal analysis, while the last two processes were done by echo signal analysis. The acoustic instruments used in this study include Acoustic Doppler Velocimeter (ADV), Pulse Coherent Acoustic Doppler Profiler (PC-ADP) and Micro-Chirp system. Used sediments are pure kaolinite and in-situ sediments collected from Mai Po and Clay Bank. 5-MHz ADV was used to estimate the suspended sediment concentration (SSC) and settling velocity (ws). For …

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Natural Mortality Of Blue Crab: Estimation And Influence On Population Dynamics, David A. Hewitt Jan 2008

Natural Mortality Of Blue Crab: Estimation And Influence On Population Dynamics, David A. Hewitt

Dissertations, Theses, and Masters Projects

The blue crab Callinectes sapidus supports one of the most important fisheries in the Chesapeake Bay and is the leading contributor to blue crab landings in the United States. Assessment and management of blue crab stocks has been hampered by a lack of estimates of natural mortality rates, a key parameter in assessment models. In Chapter 2, we demonstrate that the approach used for estimating natural mortality that had been used in past assessments was flawed, and provide justification for a superior alternative. In Chapter 3, we synthesize our current understanding of natural mortality rates in adult blue crab and …

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Nearshore Morphology And Lithology: Links To Framework Geology And Shoreline Change, Jennifer L. Miselis Jan 2008

Nearshore Morphology And Lithology: Links To Framework Geology And Shoreline Change, Jennifer L. Miselis

Dissertations, Theses, and Masters Projects

Despite evidence of the geologic and morphologic complexity of inner shelves worldwide, there is a paucity of observations from the nearshore, inhibiting direct comparison of these factors to coastal change. Using geophysical instruments to characterize the geology of the nearshore, this research focuses on the relationships between nearshore stratigraphy, sediment heterogeneity, shoreface morphology and shoreline behavior. While generally not considered in engineering models of shoreline evolution, these factors influence nearshore processes. Overall, the findings presented highlight the importance of nearshore geology, both at the seafloor and underlying it, in contributing to modem sediment transport processes affecting beaches. Shallow, sub-seafloor geology …

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Magnetic Nanoparticles Based On Iron: Synthesis, Characterization, Design, And Application, Michael David Shultz Jan 2008

Magnetic Nanoparticles Based On Iron: Synthesis, Characterization, Design, And Application, Michael David Shultz

Theses and Dissertations

Magnetic nanoparticles are of great interest for a wide range of applications. This work has focused on three primary forms of iron based nanoparticles and combinations thereof: α-iron, iron oxide, and iron carbide or cementite. The synthesis of several core-shell particles including cementite-iron oxide, α-iron-cementite, and α-iron-iron oxide was accomplished through reverse micelle routes and high temperature decomposition of iron pentacarbonyl in various media. Structural analysis to confirm the structures was performed using extended x-ray absorption fine structure (EXAFS) techniques. A rapid characterization technique was developed utilizing a correlation between Fourier transform infrared spectroscopy and EXAFS to determine the full …

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Bottom-Up And Top-Down Controls On Sedimentary Ecosystem Functioning In A Seagrass Habitat, Amanda C. Spivak Jan 2008

Bottom-Up And Top-Down Controls On Sedimentary Ecosystem Functioning In A Seagrass Habitat, Amanda C. Spivak

Dissertations, Theses, and Masters Projects

Coastal seagrass ecosystems are complex habitats that are increasingly influenced by human perturbations. Disturbances that affect the strength of bottom-up (i.e. resource availability) and top-down (i.e. consumer) controls may also influence biomass distribution between trophic levels, sediment biogeochemistry, and seagrass ecosystem metabolism. Here, I experimentally tested how top-down and bottom-up perturbations interact with community structure (diversity, food chain length of epibenthic consumers) to alter sediment biogeochemistry and ecosystem metabolism in an experimental eelgrass (Zostera marina ) system. My data indicated that resource availability influenced SOM composition and ecosystem metabolism. Light availability tended to be a stronger determinant of SOM composition …

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Authoring And Sharing Of Programming Exercises, Somyajit Jena Jan 2008

Authoring And Sharing Of Programming Exercises, Somyajit Jena

Master's Projects

In recent years, a number of exercises have been developed and published for educating students in the field of Computer Science. But these exercises exist in their own silos. There is no apparent mechanism to share these exercises among researchers and instructors in an effective and efficient manner. Moreover, the developers of these programming exercises are generally using a proprietary system for automatic submission and grading of these exercises. Each of these systems dictates the persistent format of an exercise that may not be inter-operable with other automatic submission and grading systems. This project provides a solution to this problem …

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Synthesis And Field Emission Properties Of Carbon Nanostructures, Kun Hou Jan 2008

Synthesis And Field Emission Properties Of Carbon Nanostructures, Kun Hou

Dissertations, Theses, and Masters Projects

This dissertation focuses on developing carbon nanostructures for application as the electron emissive material in novel back-gated triode field emission devices. The synthesis, characterization, and field emission properties of carbon nanostructures, including 1-D carbon nanofibers (CNF), 2-D carbon nanosheets (CNS), and chromium oxide coated carbon nanosheets (CrOx-CNS), are presented in this work.;First, we have fabricated aligned carbon nanofiber based back-gated triode field emission devices and confirmed the operation of these devices. 1-D carbon nanofibers were directly synthesized on blank TiW substrates using direct current plasma enhanced chemical vapor deposition. It was found that the morphology of carbon nanofibers could be …

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Methods For Stabilizing High Reynolds Number Lattice Boltzmann Simulations, Brian Robert Keating Jan 2008

Methods For Stabilizing High Reynolds Number Lattice Boltzmann Simulations, Brian Robert Keating

Dissertations, Theses, and Masters Projects

The Lattice Boltzmann Method (LBM) is a simple and highly efficient method for computing nearly incompressible fluid flow. However, it is well known to suffer from numerical instabilities for low values of the transport coefficients. This dissertation examines a number of methods for increasing the stability of the LBM over a wide range of parameters. First, we consider a simple transformation that renders the standard LB equation implicit. It is found that the stability is largely unchanged. Next, we consider a stabilization method based on introducing a Lyapunov function which is essentially a discrete-time H-function. The uniqueness of an H-function …

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