Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 84 for “"chemical transport"”.
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Development and Acceleration of Parallel Chemical Transport Models
Improving chemical transport models for atmospheric simulations relies on future developments of mathematical methods and parallelization methods. Better mathematical methods allow simulations to more accurately model realistic processes and/or to run in a shorter amount of time. Parellization …
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Chemical transport by methane ebullition in a freshwater lake
… of this important greenhouse gas. In addition to transporting gas, bubbles effectively transport particles in water columns. This process has been used extensively in industry since the 1900s to separate chemicals of interest from bulk solutions. While bubbles also transport particulate matter in …
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Water Flow and Chemical Transport in a Subsurface Drained Watershed
… River. An improved understanding of flow and transport is essential to better manage these ecosystems. However, such systems are extremely difficult to characterize and model since the regulating processes are dominated by preferential flow mechanisms that exhibit great spatial and temporal …
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EFFECT OF MICROTUBULE-TARGETING AGENTS ON STRUCTURAL SIGNALING AND CHEMICAL TRANSPORT IN CELLS
… structures, neurons rely on intracellular active transport for cargo movement along the axon, making them especially susceptible to deficits in this process caused by taxane treatment. A recent hypothesis links axonal transport impairment to lattice expansion, a structural alteration induced by …
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Deducing trace gas emissions using an inverse method in three-dimensional chemical transport models
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1993.
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Measurement of Pernitric Acid, Hydrogen Chloride, and Sulfur Dioxide during the Intercontinental Chemical Transport Experiment Campaign
… measurements of HO2NO2, HCl and SO2 using chemical ionization mass spectrometry (CIMS) during the Intercontinental Chemical Transport Experiment (INTEX) field campaign, an intensive study to characterize the chemical composition of the troposphere in the eastern United States, Mexico City, …
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Optimal estimation of the surface fluxes of chloromethanes using a 3-D global atmospheric chemical transport
… of these species. The Model of Atmospheric Transport and CHemistry (MATCH), driven by NCEP interannually varying meteorological fields, is then used to simulate the trace gas mole fractions using the a priori emissions and to quantify the time series of sensitivities of tracer concentrations …
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Estimation of methane and carbon dioxide surface fluxes using a 3-D global atmospheric chemical transport model
… our forward simulations, we use the 3-D global chemical transport model MATCH driven by NCEP meteorology. A prescribed, annually-repeating OH field scaled to fit methyl chloroform observations is used as the methane sink. A total methane source of approximately 600 Tg yr⁻¹ best reproduces the …
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Tropospheric Ozone over the Middle East and Its Interannual Variability: An Integrated Analysis with Satellite Observations and a Global Chemical Transport Model
… are scant. In this study, the GEOS-Chem chemical transport model is used to interpret newly available tropospheric ozone data from the Tropospheric Emission Spectrometer (TES) satellite instrument. TES reveals elevated ozone in the mid-troposphere (500-300 hPa) over the Middle East in …
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Development of a 3-dimensional chemical transport model based on observed winds and use in inverse modeling of the sources of CCl₃F
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996.
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Hydrogeologic Model of a Leachate Plume in an Unconfined Coastal Plain Aquifer and Chemical Transport Mechanisms of Metals and Dense Non-Aqueous Phase Liquids
… the regional groundwater flow and contaminant transport at the site. This model was then used to investigate the migration of chlorinated hydrocarbons (CHCs) and metals in unconfmed high porosity sandstone, indicating that migration for both CHCs and metals were caused by advective transport. …
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Modeling transport of agricultural chemicals in a dual porosity system resulting from macropores
… developed to simulate water flow and reactive chemical transport in both the soil matrix and the macropore region. Flow of water in both regions is governed by Richards' equation and chemical transport is based upon convective-dispersive mechanisms with linear kinetic sorption and first-order …
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A New Paradigm Of Modeling Watershed Water Quality
Accurate models to reliably predict sediment and chemical transport in watershed water systems enhance the ability of environmental scientists, engineers and decision makers to analyze the impact of contamination problems and to evaluate the efficacy of alternative remediation techniques and …
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Large-Scale Simulations Using First and Second Order Adjoints with Applications in Data Assimilation
… the computation of second order adjoints for chemical transport models, and illustrate their feasibility in several aspects. We apply first order adjoints to sensitivity analysis and data assimilation. Through sensitivity analysis, we can discover the area that has the largest influence on …
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Accelerating Atmospheric Modeling Through Emerging Multi-core Technologies
… model is developed to simulate atmospheric chemical transport and atmospheric chemical kinetics. The Cell Broadband Engine Architecture (CBEA), General Purpose Graphics Processing Units (GPGPUs), and homogeneous multi-core processors (e.g. Intel Quad-core Xeon) are introduced. These …
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An uncertainty-focused approach to modeling the atmospheric chemistry of persistent organic pollutants
… of uncertainty in emissions and physicochemical properties (including reaction rate constants) to Northern Hemisphere (NH) and Arctic PAH concentrations. NH average concentrations are more sensitive to uncertainty in the atmospheric lifetime than to emissions rate. The largest …
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Quantifying mercury surface fluxes by combining atmospheric observations and models
… Although an important component of its biogeochemical cycle, large uncertainties still exist in the estimates of surface fluxes of mercury. Three projects presented in this thesis improve our understanding of mercury surface fluxes at different spatial scales by combining atmospheric …
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A Better Tropospheric Aerosol Analysis and Forecast Using Data Assimilation and Coupled Modeling
Chemical transport models are useful to predict air pollutant concentrations and provide advice to people to minimize adverse impacts of high levels of tropospheric aerosols and ozone. This dissertation incorporated a coupled model between meteorology and air quality, as well as data assimilation …
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Impacts of emission policies in China on air pollution and human health
… strategies requires understanding policy costs, chemical non-linearities in pollution formation, and the value of health benefits. China suffers from severe air pollution, and is implementing both policies, but relevant studies are limited. This thesis incorporates three studies that examine the …
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Simulating the sources of organic aerosol in the atmosphere
… organic aerosol. Our limited knowledge about the chemical identity of thousands of organic compounds limits significantly our ability to determine their sources and their properties. In this study we developed an algorithm which has the ability to determine the sources of the emissions of the OA …
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