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2008

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Articles 2911 - 2940 of 4190

Full-Text Articles in Engineering

Dspace Implementation Of A Generalized Method Of Harmonic Elimination For Pwm Boost Type Rectifier Under Unbalanced Operating Conditions, Ke Chen Jan 2008

Dspace Implementation Of A Generalized Method Of Harmonic Elimination For Pwm Boost Type Rectifier Under Unbalanced Operating Conditions, Ke Chen

ETD Archive

In this thesis, the implementation of a generalized method of harmonic elimination for the PWM boost type rectifier under severe fault conditions in the power system is presented. This method has been implemented by using DSPACE RT1104 digital control system. Control loop has been designed for real-time DC link voltage regulation. The simulation and experimental results verify the feasibility of the control scheme for input-output harmonic elimination. With the proposed method, unity power factor can be achieved as well as low-order harmonic elimination. High quality input and output waveforms of the three-phase PWM boost type rectifier are obtained under extremely …

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Slurry Based Coatings On Silicon Based Ceramics, Sameer K. Khaja-Abdul Jan 2008

Slurry Based Coatings On Silicon Based Ceramics, Sameer K. Khaja-Abdul

ETD Archive

The use of advanced structural ceramics, such as Si3N4 (SN282), SiC, and SiC/SiC composites, is a promising technology to accomplish the high performance goals for advanced turbine applications. These materials exhibit excellent corrosion resistance by forming a dense silica scale. However, severe degradation of the silica scale has been observed due to the presence of certain environmental species, like alkali salts and water vapors, limiting the long-term reliability of structural ceramics. Presence of water vapor in the turbine environment leads to the formation of a gaseous silicon hydroxide species (Si(OH)4) via a reaction with silica layer, SiO2(s) + 2H2O(g) = …

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Nonlinear State Estimation In Polymer Electrolyte Membrane Fuel Cells, Uma Tumuluri Jan 2008

Nonlinear State Estimation In Polymer Electrolyte Membrane Fuel Cells, Uma Tumuluri

ETD Archive

Research on alternative and renewable energy sources which are amicable to the environment has gained momentum because of the growing concern about the tremendous increase in the concentration of toxic and green house gases and scarcity of the fossil fuels. Among the available renewable sources, fuel cell technology has received a high research attention due to their high efficiency and superior reliability. Among the various fuel cells available, Polymer electrolyte membrane fuel cell is promising source for both stationary and mobile applications because of its high efficiency and low operating temperatures. The performance of the fuel cell depends on the …

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A Novel Cascaded Multilevel Converter, Rajmohan Rangarajan Jan 2008

A Novel Cascaded Multilevel Converter, Rajmohan Rangarajan

ETD Archive

A novel cascaded multilevel converter is proposed in this thesis. The thesis proposes to produce more voltage levels from fewer H-bridges in a cascaded multilevel converter. The converter uses fewer H-bridges and the proposed switching scheme renders more voltage level in the staircase waveform with equal steps. Since the resulting voltage levels are equal, the angles are determined for the complete elimination of more unwanted harmonics. The implementation of the switching scheme, in single and three-phase configurations were simulated with Ansoft Simplorer♭ and the frequency spectrum of the resulting waveform and its total harmonic distortion are shown to verify the …

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Byzantine Fault Tolerance For Nondeterministic Applications, Bo Chen Jan 2008

Byzantine Fault Tolerance For Nondeterministic Applications, Bo Chen

ETD Archive

The growing reliance on online services accessible on the Internet demands highly reliable system that would not be interrupted when encountering faults. A number of Byzantine fault tolerance (BFT) algorithms have been developed to mask the most complicated type of faults - Byzantine faults such as software bugs,operator mistakes, and malicious attacks, which are usually the major cause of service interruptions. However, it is often difficult to apply these algorithms to practical applications because such applications often exhibit sophisticated non-deterministic behaviors that the existing BFT algorithms could not cope with. In this thesis, we propose a classification of common types …

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Experimental Test And Cost Analysis Of Residential Solar Water Heaters, Sai Mahesh Dharanikota Jan 2008

Experimental Test And Cost Analysis Of Residential Solar Water Heaters, Sai Mahesh Dharanikota

ETD Archive

Non renewable energy sources have been diminishing in the recent times.Renewable energy is abundant in nature, but the use of it is very low.Lowering the energy consumption and using renewable energy, thereby decreasing the use of fossil fuels and nuclear energy would have a positive impact on our environment. The use of solar energy as an alternate resource is discussed in this research. The solar water heater is tested for its recovery rates, under normal solar radiation in static testing. The effect of solar radiation in increasing the temperature of water is studied and discussed. The solar water heater is …

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Effect Of Adding A Regenerator To Kornhauser's Mit "Two-Space" Test Rig, Praveen Gidugu Jan 2008

Effect Of Adding A Regenerator To Kornhauser's Mit "Two-Space" Test Rig, Praveen Gidugu

ETD Archive

A 3-space solution domain (gas spring + heat exchanger + regenerator) is adapted from the 2-space solution domain (gas spring + heat exchanger) in Kornhauser MIT test rig [25] by modifying the heat exchanger space to include a porous regenerator system. A thermal non-equilibrium porous-media model is employed for the regenerator. Extensive numerical simulations of the fluid flow and heat transfer phenomena under conditions of oscillating pressure and oscillating fluid flow inside the 3-space solution domain were performed using 1-D Sage and 2-D Fluent numerical codes. 3-space results of temperature, pressure and surface heat transfer variations, pressure-volume diagrams, energy conservation …

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Experimental Testing And Performance Analysis Of "Room Air Cleaners", Pavan Kumar Mudiya Jan 2008

Experimental Testing And Performance Analysis Of "Room Air Cleaners", Pavan Kumar Mudiya

ETD Archive

HMI industries are the manufacture of the air cleaners and vacuum cleaners, in which a solution is adapted for the current model of the volute to the new design of the volute in order to calculate the "Clean Air Delivery rate" and qualify for the "Energy Star requirements". For the above model to be employed as a Energy Star certificate, a test rig was made in which "air velocity" and "flow rate" was calculated for the three different air cleaners in two cases i.e. (i) three different air cleaners with different filters and different rpm's (ii) three different air cleaners …

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Radiation View Factors Between A Disk And The Interior Of A Class Of Axisymmetric Bodies Including Converging Diverging Rocket Nozzles, Mark Richard Murad Jan 2008

Radiation View Factors Between A Disk And The Interior Of A Class Of Axisymmetric Bodies Including Converging Diverging Rocket Nozzles, Mark Richard Murad

ETD Archive

A general symbolic exact analytic solution is developed for the radiation view factors including shadowing by the throat between a divergence thin gas disk between the combustion chamber and the beginning of the rocket nozzle radiating energy to the interior downstream of the nozzle contour for a class of coaxial axisymmetric converging diverging rocket nozzles. The radiation view factors presented in this thesis for the projection which are blocked or shadowed through the throat radiating downstream to the contour have never been presented before in the literature. It was found that the curvature of the function of the contour of …

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Application Of Reverse Engineering And Rapid Prototyping To Casting, Venkat Deepak Kolar Jan 2008

Application Of Reverse Engineering And Rapid Prototyping To Casting, Venkat Deepak Kolar

ETD Archive

The automotive industry has an increasing need for the re manufacturing of spare parts through reverse engineering. In this thesis we will review the techniques used in Fused Deposition Modeling system for the reverse engineering of vintage automotive parts. The objective of the project is to be able to generate part-to-CAD and CAD-to-part reconstruction of the original part for future usage. These newly created 3D models will be added to the 3D Part Database. The integration of reverse engineering and rapid prototyping is being used for getting product to the market quickly by resolving a long-standing conflict between design and …

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Probabilistic Finite Element Heat Transfer And Structural Analysis Of A Cone-Cylinder Pressure Vessel, Omar Haddad Jan 2008

Probabilistic Finite Element Heat Transfer And Structural Analysis Of A Cone-Cylinder Pressure Vessel, Omar Haddad

ETD Archive

Stress analysis of a cone-cylinder pressure vessel was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for overall Von Mises stresses due to the structural and thermodynamic random variables. These results can be used to quickly identify the most critical design variables in order to optimize the design and make it cost effective. The analysis leads to the selection of the appropriate measurements to be used in structural and heat transfer analysis and to the identification of both the most …

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Mathematical Analysis Of A Geothermal System, Ivan P. Erceg Jan 2008

Mathematical Analysis Of A Geothermal System, Ivan P. Erceg

ETD Archive

The issue being examined is to design a more economical and efficient therefore superior geothermal system than currently in use in industry. Current geothermal systems are designed and built 300 feet into the ground. After researching ground temperature gradients for Ohio we found out that below 10 feet of depth, the temperature varies by 1 degree Fahrenheit per 100 feet depth. Our goal is to utilize the heat as close to the surface as possible and greatly reduce the need to dig so deeply into the ground. The procedure used to go about designing a superior geothermal system is to …

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Missouri River Recovery Program: Missouri River Ecosystem Restoration Plan (Mrerp) Jan 2008

Missouri River Recovery Program: Missouri River Ecosystem Restoration Plan (Mrerp)

United States Army Corps of Engineers, Omaha District

The Missouri River Ecosystem Restoration Plan (MRERP) and Missouri River
Recovery Program (MRRP) are complementary efforts led by the U.S. Army Corps of Engineers in partnership with the U.S. Fish and Wildlife Service to protect, recover and restore the Missouri River ecosystem and its native species. The MRERP will provide a long-term, focused analysis of basin-wide restoration, mitigation and recovery needs of the Missouri River for the next 30 years. It will provide a comprehensive perspective to accomplish restoration objectives and reduce conflict over scarce resources while balancing the river’s social, economic and cultural values.

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Effective Elution Of Rdx And Tnt From Particles Of Comp B In Surface Soil, John S. Furey, Herbert L. Fredrickson, Margaret J. Richmond, Michael Michel Jan 2008

Effective Elution Of Rdx And Tnt From Particles Of Comp B In Surface Soil, John S. Furey, Herbert L. Fredrickson, Margaret J. Richmond, Michael Michel

United States Army: Publications

During live fire training exercises, large amounts of explosives are consumed. Low order detonations of high explosive payloads result in the patchy dispersal of particles of high explosive formulations over large areas of firing range soils. Dissolution of explosives from explosive formulation particles into soil pore water is a controlling factor for transport, fate, and effects of explosive compounds. We developed an empirical method to evaluate soils based on functionally defined effective dissolution rates. An automated Accelerated Solvent Extractor was used to determine the effective elution rates under controlled conditions of RDX and TNT from soil columns containing particles of …

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Detection Of The Superoxide Radical Anion Using Various Alkanethiol Monolayers And Immobilized Cytochrome C, Xiaojun J. Chen, Alan C. West, Donald M. Cropek, Scott Banta Jan 2008

Detection Of The Superoxide Radical Anion Using Various Alkanethiol Monolayers And Immobilized Cytochrome C, Xiaojun J. Chen, Alan C. West, Donald M. Cropek, Scott Banta

United States Army: Publications

The superoxide radical anion (SO) is a critical biomarker for monitoring cellular stress responses. Electrochemical SO biosensors are frequently constructed through the covalent immobilization of cytochrome c (Cyt c) onto self-assembled monolayers (SAMs); however, a detailed comparison of these systems as well as configuration influence on SO detection is needed to enable robust applications. Two reaction pathways, oxidation of SO by the SAM-modified gold electrode or electron transfer through a protein and monolayer relay, may be involved during the electrochemical detection of SO with Cyt c, depending on the SAM that is used. Although electrodes with SAMs alone can exhibit …

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Phase 2a Trial Of 0, 1, And 3 Month And 0, 7, And 28 Day Immunization Schedules Of Malaria Vaccine Rts,S/As02 In Malaria-Naive Adults At The Walter Reed Army Institute Of Research, Kent E. Kester, James F. Cummings, Christian F. Ockenhouse, Robin Nielsen, B. Ted Hall, Daniel M. Gordon, Robert J. Schwenk, Urszula Krzych, Carolyn A. Holland, Gregory Richmond, Megan G. Dowler, Jackie Williams, Robert A. Wirtz, Nadia Tornieporth, Laurence Vigneron, Martine Delchambre, Marie-Ange Demoitie, W. Ripley Ballou, Joe Cohen, D. Gray Heppner Jr. Jan 2008

Phase 2a Trial Of 0, 1, And 3 Month And 0, 7, And 28 Day Immunization Schedules Of Malaria Vaccine Rts,S/As02 In Malaria-Naive Adults At The Walter Reed Army Institute Of Research, Kent E. Kester, James F. Cummings, Christian F. Ockenhouse, Robin Nielsen, B. Ted Hall, Daniel M. Gordon, Robert J. Schwenk, Urszula Krzych, Carolyn A. Holland, Gregory Richmond, Megan G. Dowler, Jackie Williams, Robert A. Wirtz, Nadia Tornieporth, Laurence Vigneron, Martine Delchambre, Marie-Ange Demoitie, W. Ripley Ballou, Joe Cohen, D. Gray Heppner Jr.

United States Army: Publications

Background: Immunization with RTS,S/AS02 consistently protects some vaccinees against malaria infection in experimental challenges and in field trials. A brief immunization schedule against falciparum malaria would be compatible with the Expanded Programme on Immunization, or in combination with other prevention measures, interrupt epidemic malaria or protect individuals upon sudden travel to an endemic area.
Methods: We conducted an open label, Phase 2a trial of two different full dose schedules of RTS,S/AS02 in 40 healthy malaria-naıve adults. Cohort 1 (n = 20) was immunized on a 0, 1, and 3 month schedule and Cohort 2 (n = 20) on a 0, …

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Vietnam: Historians At War, Mark Moyar Jan 2008

Vietnam: Historians At War, Mark Moyar

United States Army: Publications

By the early 1990s, when I began studying the Vietnam War, the American public had largely lost interest in the history of that conflict. The Civil War and World War II were the wars that historians were advised to cover if they wanted to reach the public. Among government officials, military officers, and political scientists, Vietnam was considered irrelevant, because the United States would never get caught in protracted counterinsurgency warfare again. Iraq changed all that. Ever since the outbreak of insurgency in the former empire of Saddam Hussein, people of all persuasions have been mining the history of Vietnam …

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Influenza Immunization And Subsequent Diagnoses Of Group A Streptococcus-Illnesses Among U.S. Army Trainees, 2002–2006, Seung-Eun Lee, Angelia Eick, Michael S. Bloom, John F. Brundage Jan 2008

Influenza Immunization And Subsequent Diagnoses Of Group A Streptococcus-Illnesses Among U.S. Army Trainees, 2002–2006, Seung-Eun Lee, Angelia Eick, Michael S. Bloom, John F. Brundage

United States Army: Publications

To assess the association between influenza immunization and subsequent diagnosis of group A streptococcus (GAS)-illness in Army recruits during influenza seasons 2002–2006. A case–control study was employed with cases as trainees with outpatient GAS diagnosis (ICD-9-CM codes: 034.0, 035, 038.0, 041.01, 320.2, 390–392, 482.31) during the influenza season, and controls as trainees with no outpatient GAS diagnosis during the influenza season. Primary exposure was influenza immunization during 1st September to 30th April of each season. Estimated protective effects of influenza immunization against GAS-illness ranged from 50% to 77%. A strong protective effect was suggested for Army trainee influenza immunization on …

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Utility Of Lipid Biomarkers In Support Of Bioremediation Efforts At Army Sites, D. Ringelberg, M. Richmond, K. Foley, C. Reynolds Jan 2008

Utility Of Lipid Biomarkers In Support Of Bioremediation Efforts At Army Sites, D. Ringelberg, M. Richmond, K. Foley, C. Reynolds

United States Army: Publications

Lipid biomarker analysis has proven valuable in testing the hypothesis that attributes of the extant microbiota can directly reflect the occurrence of contaminant biodegradation. Two past research efforts have demonstrated this utility and are described here.
A 4.5 m vertical core was obtained from a diesel fuel oil contamination plume. Core material was assayed for total petroleum hydrocarbons (TPH) and bacterial membrane phospholipids (PLFA) via a single solvent extraction. Microbial viable biomass and the relative abundance of Gram-negative bacterial PLFA biomarkers were found to be significantly correlated with TPH concentration. The core TPH profile also revealed two distinct areas where …

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"Making It Fresh - Your Choice For Performance", The Army's Hospital Foodservice Program, S. Spielmann, M. Worley, R. Harris Jan 2008

"Making It Fresh - Your Choice For Performance", The Army's Hospital Foodservice Program, S. Spielmann, M. Worley, R. Harris

United States Army: Publications

To describe the Army’s new foodservice design and concept, “Making it Fresh—Your Choice for Performance” and its application for customer and patient feeding in a fixed medical treatment facility.

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Moderate Zinc Restriction Affects Intestinal Health And Immune Function In Lipopolysaccharide-Challenged Mice, Daniel G. Peterson, Angus G. Scrimgeour, James P. Mcclung, Elizabeth A. Koutsos Jan 2008

Moderate Zinc Restriction Affects Intestinal Health And Immune Function In Lipopolysaccharide-Challenged Mice, Daniel G. Peterson, Angus G. Scrimgeour, James P. Mcclung, Elizabeth A. Koutsos

United States Army: Publications

Zinc (Zn) is an essential nutrient that affects immune function, especially within the digestive system, although the underlying mechanisms are not well understood. This study examined the effects of short-term moderate Zn restriction on intestinal health and immune function in lipopolysaccharide (LPS)-challenged mice through plasma cytokine profiling and histological evaluation of intestinal tissue sections. Adult male mice were fed with a Zn-adequate (40 ppm) or a Zn-marginal (4 ppm) diet for 4 weeks, and then a bacterial challenge was simulated by intraperitoneal injection of LPS (10 μg/g body weight [BW]) or saline (control). BW was recorded weekly, and feed intake …

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The 2008 Strategy For United States Air Force Intelligence, Surveillance And Reconnaissance, United States Air Force Jan 2008

The 2008 Strategy For United States Air Force Intelligence, Surveillance And Reconnaissance, United States Air Force

United States Air Force: Publications

Since the inception of the Air Force, our Nation has asked us to create aerospace forces that no adversary could "out gun" under any circumstances. For over six decades we have answered that call. Now the Nation demands that we also create a set of capabilities that no adversary can "out smart" in the future. This strategy outlines our response in the realm of Intelligence, Surveillance and Reconnaissance (ISR).
This is a new document that specifies why and how our Air Force will provide the capacity and capability for full spectrum ISR. It provides the foundation for enabling our air …

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An Integer Programming Approach To Support The Us Air Force’S Air Mobility Network, Corbin G. Koepke, Andrew P. Armacost, Cynthia Barnhart, Stephan E. Kolitz Jan 2008

An Integer Programming Approach To Support The Us Air Force’S Air Mobility Network, Corbin G. Koepke, Andrew P. Armacost, Cynthia Barnhart, Stephan E. Kolitz

United States Air Force: Publications

The United States Air Force’s air mobility command is responsible for creating a schedule and executing that schedule for a large-scale air mobility network that encompasses aircraft with prioritized missions. Aerial ports (airports) can process or park a maximum number of aircraft, called the maximum on ground (MOG). As the schedule changes due to disruptions, such as equipment failure or weather, the MOG constraint can cause the new schedule to be infeasible. Traditionally, re-planning the channel route schedule to adhere to MOG constraints has been a manual process that usually stops after the first feasible set of changes is found, …

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Conduction In Rectangular Plates With Boundary Temperatures Specified, James V. Beck, Neil T. Wright, A. Haji-Sheikh, Kevin D. Cole, Donald E. Amos Jan 2008

Conduction In Rectangular Plates With Boundary Temperatures Specified, James V. Beck, Neil T. Wright, A. Haji-Sheikh, Kevin D. Cole, Donald E. Amos

Department of Mechanical and Materials Engineering: Faculty Publications

Steady-state components of heat conduction solutions may have very slowly convergent series for temperatures and non-convergent heat fluxes for temperature boundary conditions. Previous papers have proposed methods to remove these convergence problems. However, even more effective procedures based on insights of Morse and Feshbach are given herein. In some cases it is possible to replace poorly-convergent or non-convergent series by closed-form algebraic solutions. Examples are given.

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The Design And Testing Of Hand Held Devices To Assist Persons With Disabilities To Navigate Bus Services, Daniel Fitch Jan 2008

The Design And Testing Of Hand Held Devices To Assist Persons With Disabilities To Navigate Bus Services, Daniel Fitch

Undergraduate Review

Many transit systems around the U.S. are using global positioning systems to track their buses. Some of these systems provide bus locations in real-time on web maps. With internet integration becoming common in portable electronics, this research project analyzed the opportunity to utilize mass market devices to assist the general public and persons with disabilities to access and navigate fixed route bus services. This study has taken advantage of the state of the art automatic vehicle location systems aboard the Cape Cod Regional Transit Authority and MetroWest (Boston) Regional Transit Authority bus services, Microsoft Virtual Earth mapping services and Microsoft …

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Characterization Of Aerosols Containing Zn, Pb, And Cl From An Industrial Region Of Mexico City, Ryan C. Moffet, Yury Desyaterik, Rebecca J. Hopkins, Alexei V. Tivanski, Mary K. Gilles, Y. Wang, V. Shuthanandan, Luisa T. Molina, Rodrigo Gonzalez Abraham, Kirsten S. Johnson, Violeta Mugica, Mario J. Molina, Alexander Laskin, Kimberly A. Prather Jan 2008

Characterization Of Aerosols Containing Zn, Pb, And Cl From An Industrial Region Of Mexico City, Ryan C. Moffet, Yury Desyaterik, Rebecca J. Hopkins, Alexei V. Tivanski, Mary K. Gilles, Y. Wang, V. Shuthanandan, Luisa T. Molina, Rodrigo Gonzalez Abraham, Kirsten S. Johnson, Violeta Mugica, Mario J. Molina, Alexander Laskin, Kimberly A. Prather

United States Department of Energy: Publications

Recent ice core measurements show lead concentrations increasing since 1970, suggesting new non automobile-related sources of Pb are becoming important worldwide (1). Developing a full understanding of the major sources of Pb and other metals is critical to controlling these emissions. During the March, 2006 MILAGRO campaign, single particle measurements in Mexico City revealed the frequent appearance of particles internally mixed with Zn, Pb, Cl, and P. Pb concentrations were as high as 1.14 μg/m3 in PM10 and 0.76 μg/m3 in PM2.5. Real time measurements were used to select time periods of interest …

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Assignment Of Polarization-Dependent Peaks In Carbon K-Edge Spectra From Biogenic And Geologic Aragonite, Dong Zhou, Rebecca A. Metzler, Tolek Tyliszczak, Jinghua Guo, Mike Abrecht, Susan N. Coppersmith, P. U. P. A. Gilbert Jan 2008

Assignment Of Polarization-Dependent Peaks In Carbon K-Edge Spectra From Biogenic And Geologic Aragonite, Dong Zhou, Rebecca A. Metzler, Tolek Tyliszczak, Jinghua Guo, Mike Abrecht, Susan N. Coppersmith, P. U. P. A. Gilbert

United States Department of Energy: Publications

Many biominerals, including mollusk and echinoderm shells, avian eggshells, modern and fossil bacterial sediments, planktonic coccolithophores, and foraminifera, contain carbonates in the form of biogenic aragonite or calcite. Here we analyze biogenic and geologic aragonite using different kinds of surface- and bulksensitive X-ray absorption near-edge structure (XANES) spectroscopy at the carbon K-edge, as well as highresolution scanning transmission X-ray microscopy (STXM). Besides the well-known main π* and σ* carbonate peaks, we observed and fully characterized four minor peaks, at energies between the main π* and σ* peaks. As expected, the main peaks are similar in geologic …

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Challenges In Earth System Modelling: Approaches And Applications, D.J. Erickson Ill, Robert J. Oglesby, S. Elliott, W. Steffen, G. Brasseur Jan 2008

Challenges In Earth System Modelling: Approaches And Applications, D.J. Erickson Ill, Robert J. Oglesby, S. Elliott, W. Steffen, G. Brasseur

United States Department of Energy: Publications

Earth system modelling has taken on increasing importance over the past several years. These models are being used to address an increasing number of environmental and global change problems of societal concern (e.g. Adams et al., 1998; Easterling et al., 2000; Foley et al., 2003). Perhaps most commonly known is the application to possible greenhouse-gas induced warming (Hoffman et al., 2005). Other compelling problems include the climatic effects of land use changes, aerosols (including sulphate emissions, and smoke from biomass burning; Erickson et al., 1995; Oglesby et al., 1999), changing trace gas fluxes, interactions and feedbacks with the global carbon …

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Understanding The Grafting Of Telechelic Polymers On A Solid Substrate To Form Loops, Zhenyu Huang, Haining Ji, Jimmy W. Mays, Mark D. Dadmun Jan 2008

Understanding The Grafting Of Telechelic Polymers On A Solid Substrate To Form Loops, Zhenyu Huang, Haining Ji, Jimmy W. Mays, Mark D. Dadmun

United States Department of Energy: Publications

Recent experimental and theoretical studies have demonstrated that relative to singly tethered chains, the presence of polymer loops at interfaces significantly improves interfacial properties such as adhesion, friction, and wettability. In the present study, a simple system was studied to examine the formation of polymeric loops on a solid surface, where the grafting of carboxylic acid terminated telechelic polystyrene from the melt to an epoxy functionalized silicon is chosen. The impact of telechelic molecular weight, grafting temperature, and surface functionality on the telechelic attachment process is studied. It was found that grafting of the telechelic to the surface at both …

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Synthesis And Characterization Of An Abc Miktoarm Star Terpolymer Of Cyclohexadiene, Styrene, And 2-Vinylpyridine, David Uhrig, Kunlun Hong, Jimmy W. Mays, S. Michael Kilbey Ii, Phillip F. Britt Jan 2008

Synthesis And Characterization Of An Abc Miktoarm Star Terpolymer Of Cyclohexadiene, Styrene, And 2-Vinylpyridine, David Uhrig, Kunlun Hong, Jimmy W. Mays, S. Michael Kilbey Ii, Phillip F. Britt

United States Department of Energy: Publications

Several research groups have expended great effort toward the preparation of miktoarm (mixed-arm) star copolymers and terpolymers. We describe herein a novel synthesis, using anionicpolymerization,ofapoly(cyclohexadiene)[PCHD]-polystyrene [PS]-poly(2-vinylpyridine) [P2VP] miktoarm star terpolymer.

Previously, miktoarm A2B and A3B star polydiene copolymers comprised partially of poly(cyclohexadiene) have been synthesized by Tsoukatos and Hadjichristidis by employing chlorosilane linking techniques. More recently, an ABC star terpolymer of PS, polyisoprene, and PCHD was prepared by Yang and co-workers by using meta-double-diphenylethylene-based linking chemistry.

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