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ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

Description: We conduct a detailed test of a recently developed technique, CAPloc, in recovering source parameters from a few stations against results from a large broadband network. The method uses a library of 1D Green’s functions which are broken into segments and matched to waveform observations with adjustable timing shifts. These shifts can be established by calibration against a distribution of well-located earthquake and assembled in tomographic images for predicting various phase-delays. Synthetics generated from 2D cross-sections through these models indicates that 1D synthetic waveforms are sufficient in modeling but simply shifted in time for hard-rock sites. This simplification allows the source inversion for both mechanism and location to be easily obtained by grid search. We test one-station mechanisms for 160 events against the array for both PAS and GSC which have data since 1960. While one station solutions work well (about 90%), joint solutions produce more reliable and defensible results. Inverting for both mechanism and location also works well except for certain difficult paths that cross deep basins or propagate along mountain ridges.
Date: December 10, 2007
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
Partner: UNT Libraries Government Documents Department

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

Description: The recent Nevada Earthquake (M=6) produced an extraordinary set of crustal guided waves. In this study, we examine the three-component data at all the USArray stations in terms of how well existing models perform in predicting the various phases, Rayleigh waves, Love waves, and Pnl waves. To establish the source parameters, we applied the Cut and Paste Code up to distance of 5° for an average local crustal model which produced a normal mechanism (strike=35°,dip=41°,rake=-85°) at a depth of 9 km and Mw=5.9. Assuming this mechanism, we generated synthetics at all distances for a number of 1D and 3D models. The Pnl observations fit the synthetics for the simple models well both in timing (VPn=7.9km/s) and waveform fits out to a distance of about 5°. Beyond this distance a great deal of complexity can be seen to the northwest apparently caused by shallow subducted slab material. These paths require considerable crustal thinning and higher P-velocities. Small delays and advances outline the various tectonic province to the south, Colorado Plateau, etc. with velocities compatible with that reported on by Song et al.(1996). Five-second Rayleigh waves (Airy Phase) can be observed throughout the whole array and show a great deal of variation ( up to 30s). In general, the Love waves are better behaved than the Rayleigh waves. We are presently adding higher frequency to the source description by including source complexity. Preliminary inversions suggest rupture to northeast with a shallow asperity. We are, also, inverting the aftershocks to extend the frequencies to 2 Hz and beyond following the calibration method outlined in Tan and Helmberger (2007). This will allow accurate directivity measurements for events with magnitude larger than 3.5. Thus, we will address the energy decay with distance as s function of frequency band for the various source types.
Date: April 15, 2008
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
Partner: UNT Libraries Government Documents Department

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

Description: Earthquake source parameters underpin several aspects of nuclear explosion monitoring. Such aspects are: calibration of moment magnitudes (including coda magnitudes) and magnitude and distance amplitude corrections (MDAC); source depths; discrimination by isotropic moment tensor components; and waveform modeling for structure (including waveform tomography). This project seeks to improve methods for and broaden the applicability of estimating source parameters from broadband waveforms using the Cut-and-Paste (CAP) methodology. The CAP method uses a library of Green’s functions for a one-dimensional (1D, depth-varying) seismic velocity model. The method separates the main arrivals of the regional waveform into 5 windows: Pnl (vertical and radial components), Rayleigh (vertical and radial components) and Love (transverse component). Source parameters are estimated by grid search over strike, dip, rake and depth and seismic moment or equivalently moment magnitude, MW, are adjusted to fit the amplitudes. Key to the CAP method is allowing the synthetic seismograms to shift in time relative to the data in order to account for path-propagation errors (delays) in the 1D seismic velocity model used to compute the Green’s functions. The CAP method has been shown to improve estimates of source parameters, especially when delay and amplitude biases are calibrated using high signal-to-noise data from moderate earthquakes, CAP+.
Date: June 17, 2008
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
Partner: UNT Libraries Government Documents Department

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS - REPORTING PERIOD AUGUST 1, 2007-OCTOBER 31, 2007

Description: We have developed a forward modeling technique to retrieve rupture characteristics of small earthquakes (3<M<5), including rupture propagation direction, fault dimension, and rupture speed.
Date: September 30, 2007
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
Partner: UNT Libraries Government Documents Department

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS; REPORTING PERIOD NOVEMBER 1, 2006 - JANUARY 31, 2007

Description: The amplitude fluctuations of seismic waves from point source radiation patterns are among the direct results of rupture propagation. However, these amplitude signals are seldom used for small earthquakes due to the large uncertainties in the focal mechanisms of the events or the empirical Green’s functions (EGFs). Moreover, it has been controversial if radiation patterns still exist at high frequencies, e.g., 10 Hz. We present an evidence for high frequency radiation patterns by showing that with accurately determined focal mechanism solutions, the broadband P wave records from a thrust event (M 3.0) can be turned into those from a distinctly different strike slip event of similar magnitude with simple radiation pattern corrections. Moreover, we observe systematic azimuthal variations in the P and S wave amplitude ratios between the records from unilateral magnitude 4 events and the EGF events, which suggest that these simple amplitude ratios can provide fast and useful indications of the rupture directivity. For further estimates of the fault dimension and rupture speed, we developed a forward modeling approach to retrieve apparent source time functions (ASTFs) of small earthquakes, where we assume simple Haskell model and take a grid search approach to find the ASTFs for each recording station. Compared to the usually used deconvolution approach, this method fully utilizes the information of both duration as well as amplitude. We applied this approach to the 2003 Big Bear sequence, and successfully obtained the complex rupture propagation patterns of the few large events (3.5 < M < 4.25), where both uni-lateral and bi-lateral events, fast and slow rupture speeds are observed.
Date: January 31, 2007
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
Partner: UNT Libraries Government Documents Department

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

Description: Comprehensive test ban monitoring in terms of location and discrimination has progressed significantly in recent years. However, the characterization of sources and the estimation of low yields remains a particular challenge.
Date: June 30, 2007
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
Partner: UNT Libraries Government Documents Department

Using Ionic Liquids in Selective Hydrocarbon Conversion Processes

Description: This is the Final Report of the five-year project Using Ionic Liquids in Selective Hydrocarbon Conversion Processes (DE-FC36-04GO14276, July 1, 2004- June 30, 2009), in which we present our major accomplishments with detailed descriptions of our experimental and theoretical efforts. Upon the successful conduction of this project, we have followed our proposed breakdown work structure completing most of the technical tasks. Finally, we have developed and demonstrated several optimized homogenously catalytic methane conversion systems involving applications of novel ionic liquids, which present much more superior performance than the Catalytica system (the best-to-date system) in terms of three times higher reaction rates and longer catalysts lifetime and much stronger resistance to water deactivation. We have developed in-depth mechanistic understandings on the complicated chemistry involved in homogenously catalytic methane oxidation as well as developed the unique yet effective experimental protocols (reactors, analytical tools and screening methodologies) for achieving a highly efficient yet economically feasible and environmentally friendly catalytic methane conversion system. The most important findings have been published, patented as well as reported to DOE in this Final Report and our 20 Quarterly Reports.
Date: September 28, 2009
Creator: Tang, Yongchun; Periana, Roy; Chen, Weiqun; van Duin, Adri; Nielsen, Robert; Shuler, Patrick et al.
Partner: UNT Libraries Government Documents Department

Final Report for "Experimental Petrology and Chemistry of Volatile-Bearing Silicate Melts"

Description: The goal of Part 1 was the definitive determination of the dependence of the diffusion coefficient for water (DH2O, defined as the diffusion coefficient of total water) in various compositions of silicate melts with respect to water content (CH2O). We measured profiles of CH2O in hydration and diffusion couple experiments by Fourier transform infrared spectroscopy and secondary ion mass spectrometry. DH2O values were determined from the profiles using both direct calculations (Boltzmann-Matano methods) and models assuming specific relationships between DH2O and CH2O (including constant, proportional, and exponential relationships, and a simple speciation model assuming that water molecules are mobile (with constant diffusivity) and hydroxyl groups are immobile). As expected, the constant DH2O model was never the best fit to our diffusion profile data. In order to distinguish among the models with varying diffusion coefficients, all of which require increasing DH2O with increasing CH2O, we ran a series of experiments with small ranges of CH2O, so that we could assume that DH2O was constant. If either the proportional or speciation model holds, then DH2O = 0 at CH2O = 0, whereas the exponential model predicts a finite value for DH2O at CH2O = 0. Results for haplobasalt and haploandesite compositions are consistent with DH2O = exp(DH2O). We have confirmed this conclusion by looking at experiments with very low CH2O, in which we found a finite DH2O= 2-4E-10 m2/s. Using our data and results in the literature over a range of composition (including major elements and water), temperature, and pressure conditions, we defined a general relationship between water diffusivity and viscosity (η) of silicate liquids. This is an important result, since it allows the calculation of diffusivity for compositions for which there are no measurements. Part 2 is the study of the zonation of P and other elements in olivines: (1) Complex ...
Date: March 29, 2013
Creator: Stolper, Edward M.
Partner: UNT Libraries Government Documents Department

Isotope Tracer Studies of Diffusion in Sillicates and of Geological Transport Processes Using Actinide Elements

Description: The objectives were directed toward understanding the transport of chemical species in nature, with particular emphasis on aqueous transport in solution, in colloids, and on particles. Major improvements in measuring ultra-low concentrations of rare elements were achieved. We focused on two areas of studies: (1) Field, laboratory, and theoretical studies of the transport and deposition of U, Th isotopes and their daughter products in natural systems; and (2) Study of calcium isotope fractionation effects in marine carbonates and in carbonates precipitated in the laboratory, under controlled temperature, pH, and rates of precipitation. A major study of isotopic fractionation of Ca during calcite growth from solution has been completed and published. It was found that the isotopic shifts widely reported in the literature and attributed to biological processes are in fact due to a small equilibrium fractionation factor that is suppressed by supersaturation of the solution. These effects were demonstrated in the laboratory and with consideration of the solution conditions in natural systems, where [Ca{sup 2+}] >> [CO{sub 3}{sup 2-}] + [HCO{sub 3}{sup -}]. The controlling rate is not the diffusion of Ca, as was earlier proposed, but rather the rate of supply of [CO{sub 3}{sup 2-}] ions to the interface. This now opens the issues of isotopic fractionation of many elements to a more physical-chemical approach. The isotopic composition of Ca {Delta}({sup 44}Ca/{sup 40}Ca) in calcite crystals has been determined relative to that in the parent solutions by TIMS using a double spike. Solutions were exposed to an atmosphere of NH{sub 3} and CO{sub 2}, provided by the decomposition of (NH4)2CO3. Alkalinity, pH, and concentrations of CO{sub 3}{sup 2-}, HCO{sub 3}{sup -}, and CO{sub 2} in solution were determined. The procedures permitted us to determine {Delta}({sup 44}Ca/{sup 40}Ca) over a range of pH conditions, with the associated ranges of alkalinity. ...
Date: July 31, 2008
Creator: Wasserburg, Gerald J
Partner: UNT Libraries Government Documents Department

Enhanced Power Stability for Proton Conducting Solid Oxides Fuel Cells. Calculated energy barriers for proton diffusion in Y-doped BaZrO3. Potential electrode materials for application in proton ceramic fuel cells.

Description: A series of Quantum Mechanical (QM) calculations on Y-doped BaZrO{sub 3} (BYZ) periodic structures have been performed and calculated energy barriers for the intra-octahedra and inter-octahedra proton transfer have been found. The inter-octahedra proton transfer dominates in the BYZ electrolyte. Several potential cathode materials for the Y-doped BaZrO{sub 3} system were synthesized via glycine nitrate combustion method. Of the five potential cathode materials examined BaZr{sub 0.40}Pr{sub 0.40}Gd{sub 0.20}O{sub 3} and BaZr{sub 0.60}Y{sub 0.20}Co{sub 0.20}O{sub 3} appear to be the most promising for further applications in proton ceramic fuel cells (PCFCs). Potential anode electrocatalysts (metals) have been screened for reactivity with BaZr{sub 1-x}Y{sub x}O{sub 3-d}, fabrication compatibility, and chemical stability in fuel cell environment.
Date: April 30, 2005
Creator: Merinov, Boris; Haile, Sossina & III, William A. Goddard
Partner: UNT Libraries Government Documents Department

Enhanced Power Stability for Proton Conducting Solid Oxides Fuel Cells

Description: In order to provide the basis for a rational approach to improving the performance of Y-doped BaZrO{sub 3} electrolytes for proton conducting ceramic fuel cells, we carried out a series of coupled computational and experimental studies to arrive at a consensus view of the characteristics affecting the proton conductivity of these systems. The computational part of the project developed a practical first principles approach to predicting the proton mobility as a function of temperature and doping for polycrystalline systems. This is a significant breakthrough representing the first time that first principles methods have been used to study diffusion across grain boundaries in such systems. The basis for this breakthrough was the development of the ReaxFF reactive force field that accurately describes the structure and energetics of Y-doped BaZrO{sub 3} as the proton hops from site to site. The ReaxFF parameters are all derived from an extensive set of quantum mechanics calculations on various clusters, two dimensionally infinite slabs, and three dimensionally infinite periodic systems for combinations of metals, metal alloys, metal oxides, pure and Y-doped BaZrO{sub 3}, including chemical reaction pathways and proton transport pathways, structures. The ReaxFF force field enables molecular dynamics simulations to be carried out quickly for systems with {approx} 10,000 atoms rather than the {approx}100 or so practical for QM. The first 2.5 years were spent on developing and validating the ReaxFF and we have only had an opportunity to apply these methods to only a few test cases. However these simulations lead to transport properties (diffusion coefficients and activation energy) for multi-granular systems in good agreement with current experimental results. Now that we have validated the ReaxFF for diffusion across grain boundaries, we are in the position of being able to use computation to explore strategies to improve the diffusion of protons across grain boundaries, ...
Date: December 29, 2005
Creator: Merinov, Boris; III, William A. Goddard; Haile, Sossina; Duin, Adri van; Babilo, Peter & Han, Sang Soo
Partner: UNT Libraries Government Documents Department

Improved Processes to Remove Naphthenic Acids

Description: In the past three years, we followed the work plan as we suggested in the proposal and made every efforts to fulfill the project objectives. Based on our large amount of creative and productive work, including both of experimental and theoretic aspects, we received important technical breakthrough on naphthenic acid removal process and obtained deep insight on catalytic decarboxylation chemistry. In detail, we established an integrated methodology to serve for all of the experimental and theoretical work. Our experimental investigation results in discovery of four type effective catalysts to the reaction of decarboxylation of model carboxylic acid compounds. The adsorption experiment revealed the effectiveness of several solid materials to naphthenic acid adsorption and acidity reduction of crude oil, which can be either natural minerals or synthesized materials. The test with crude oil also received promising results, which can be potentially developed into a practical process for oil industry. The theoretical work predicted several possible catalytic decarboxylation mechanisms that would govern the decarboxylation pathways depending on the type of catalysts being used. The calculation for reaction activation energy was in good agreement with our experimental measurements.
Date: December 9, 2005
Creator: Zhang, Aihua; Ma, Qisheng; Wang, Kangshi; Tang, Yongchun & Goddard, William A.
Partner: UNT Libraries Government Documents Department

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

Description: Abstract We conduct a detailed test of a recently developed technique, CAPloc, in recovering source parameters from a few stations against results from a large broadband network in Southern California. The method uses a library of 1D Green’s functions which are broken into segments and matched to waveform observations with adjustable timing shifts. These shifts can be established by calibration against a distribution of well-located earthquakes and assembled in tomographic images for predicting various phase-delays. Synthetics generated from 2D cross-sections through these models indicates that 1D synthetic waveforms are sufficient in modeling but simply shifted in time for most hard-rock sites. This simplification allows the source inversion for both mechanism and location to easily obtain by grid search. We test one-station mechanisms for 160 events against the array for both PAS and GSC which have data since 1960. While individual solutions work well (about 90%), joint solutions produce more reliable and defensible results. Inverting for both mechanism and location also works well except for certain complex paths across deep basins and along mountain ridges.
Date: January 27, 2009
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
Partner: UNT Libraries Government Documents Department

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

Description: This quarter, we have focused on several tasks: (1) Building a high-quality catalog of earthquake source parameters for the Middle East and East Asia. In East Asia, we computed source parameters using the CAP method for a set of events studied by Herrman et al., (MRR, 2006) using a complete waveform technique. Results indicated excellent agreement with the moment magnitudes in the range 3.5 -5.5. Below magnitude 3.5 the scatter increases. For events with more than 2-3 observations at different azimuths, we found good agreement of focal mechanisms. Depths were generally consistent, although differences of up to 10 km were found. These results suggest that CAP modeling provides estimates of source parameters at least as reliable as complete waveform modeling techniques. However, East Asia and the Yellow Sea Korean Paraplatform (YSKP) region studied are relatively laterally homogeneous and may not benefit from the CAP method’s flexibility to shift waveform segments to account for path-dependent model errors. A more challenging region to study is the Middle East where strong variations in sedimentary basin, crustal thickness and crustal and mantle seismic velocities greatly impact regional wave propagation. We applied the CAP method to a set of events in and around Iran and found good agreement between estimated focal mechanisms and those reported by the Global Centroid Moment Tensor (CMT) catalog. We found a possible bias in the moment magnitudes that may be due to the thick low-velocity crust in the Iranian Plateau. (2) Testing Methods on a Lifetime Regional Data Set. In particular, the recent 2/21/08 Nevada Event and Aftershock Sequence occurred in the middle of USArray, producing over a thousand records per event. The tectonic setting is quite similar to Central Iran and thus provides an excellent testbed for CAP+ at ranges out to 10°, including extensive observations of crustal thinning ...
Date: October 17, 2008
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
Partner: UNT Libraries Government Documents Department

Investigations of Solar Prominence Dynamics Using Laboratory Simulations

Description: Laboratory experiments simulating many of the dynamical features of solar coronal loops have been carried out. These experiments manifest collimation, kinking, jet flows, and S-shapes. Diagnostics include high-speed photography and x-ray detectors. Two loops having opposite or the same magnetic helicity polarities have been merged and it is found that counter-helicity merging provides much greater x-ray emission. A non-MHD particle orbit instability has been discovered whereby ions going in the opposite direction of the current flow direction can be ejected from a magnetic flux tube.
Date: May 28, 2008
Creator: Bellan, Paul M
Partner: UNT Libraries Government Documents Department

Next Generation Integrated Environment for Collaborative Work Across Internets

Description: We are now well-advanced in our development, prototyping and deployment of a high performance next generation Integrated Environment for Collaborative Work. The system, aimed at using the capability of ESnet and Internet2 for rapid data exchange, is based on the Virtual Room Videoconferencing System (VRVS) developed by Caltech. The VRVS system has been chosen by the Internet2 Digital Video (I2-DV) Initiative as a preferred foundation for the development of advanced video, audio and multimedia collaborative applications by the Internet2 community. Today, the system supports high-end, broadcast-quality interactivity, while enabling a wide variety of clients (Mbone, H.323) to participate in the same conference by running different standard protocols in different contexts with different bandwidth connection limitations, has a fully Web-integrated user interface, developers and administrative APIs, a widely scalable video network topology based on both multicast domains and unicast tunnels, and demonstrated multiplatform support. This has led to its rapidly expanding production use for national and international scientific collaborations in more than 60 countries. We are also in the process of creating a 'testbed video network' and developing the necessary middleware to support a set of new and essential requirements for rapid data exchange, and a high level of interactivity in large-scale scientific collaborations. These include a set of tunable, scalable differentiated network services adapted to each of the data streams associated with a large number of collaborative sessions, policy-based and network state-based resource scheduling, authentication, and optional encryption to maintain confidentiality of inter-personal communications. High performance testbed video networks will be established in ESnet and Internet2 to test and tune the implementation, using a few target application-sets.
Date: February 24, 2009
Creator: Newman, Harvey B.
Partner: UNT Libraries Government Documents Department

The Science of Electrode Materials for Lithium Batteries

Description: Rechargeable lithium batteries continue to play the central role in power systems for portable electronics, and could play a role of increasing importance for hybrid transportation systems that use either hydrogen or fossil fuels. For example, fuel cells provide a steady supply of power, whereas batteries are superior when bursts of power are needed. The National Research Council recently concluded that for dismounted soldiers "Among all possible energy sources, hybrid systems provide the most versatile solutions for meeting the diverse needs of the Future Force Warrior. The key advantage of hybrid systems is their ability to provide power over varying levels of energy use, by combining two power sources." The relative capacities of batteries versus fuel cells in a hybrid power system will depend on the capabilities of both. In the longer term, improvements in the cost and safety of lithium batteries should lead to a substantial role for electrochemical energy storage subsystems as components in fuel cell or hybrid vehicles. We have completed a basic research program for DOE BES on anode and cathode materials for lithium batteries, extending over 6 years with a 1 year phaseout period. The emphasis was on the thermodynamics and kinetics of the lithiation reaction, and how these pertain to basic electrochemical properties that we measure experimentally — voltage and capacity in particular. In the course of this work we also studied the kinetic processes of capacity fade after cycling, with unusual results for nanostructued Si and Ge materials, and the dynamics underlying electronic and ionic transport in LiFePO4. This document is the final report for this work.
Date: March 15, 2007
Creator: Fultz, Brent
Partner: UNT Libraries Government Documents Department

Nonequilibrium pattern formation and spatiotemporal chaos in fluid convection

Description: The final report for grant number DE-FG03-98ER14891 summarizes the application of the unique simulation capabilities developed under DOE support to investigations of important issues in pattern formation and spatiotemporal chaos in Rayleigh-Benard convection, particularly emphasizing quantitative contact with the active experimental programs.
Date: September 13, 2006
Creator: Cross, Michael
Partner: UNT Libraries Government Documents Department

Final Technical Report

Description: This project is conducted under the leadership and guidance of Sandia National Laboratory as part of the DOE Office of Science FAST-OS Program. It was initiated at the California Institute of Technology February 1, 2005. The Principal Investigator (PI), Dr. Thomas Sterling, accepted a position of Full Professor at the Department of Computer Science at Louisiana State University (LSU) on August 15, 2005, while retaining his position of Faculty Associate at California Institute of Technology’s Center for Advanced Computing Research. To take better advantage of the resources, research staff, and students at LSU, the award was transferred by DOE to LSU where research on the FAST-OS Config-OS project continues in accord with the original proposal. This brief report summarizes the accomplishments of this project during its initial phase at the California Institute of Technology (Caltech).
Date: May 29, 2007
Creator: Sterling, Thomas
Partner: UNT Libraries Government Documents Department

Final Technical Report: DE-FG03-01ER63099/DE-FG02-01ER63099

Description: Organic material contributes {approx}20-50% to the total fine aerosol mass at continental mid-latitudes (Saxena and Hildemann, 1996; Murphy et al., 1998; Peterson and Tyler, 2002; Putaud et al., 2004) and as much as 90% in tropical forested areas (Andreae and Crutzen, 1997; Artaxo et al., 2002). Significant amounts of carbonaceous aerosols are also observed in the free troposphere (Heald et al., 2005). A substantial fraction of the organic component of atmospheric particles consists of water-soluble, possibly multifunctional compounds (Saxena and Hildemann, 1996; Kavouras et al., 1998). It is critical that we understand how organic aerosols and their precursors are transformed in the atmosphere and the dependence of the transformation on the chemical and thermodynamic conditions of the ambient environment: (1) to accurately forecast how changing emissions will impact atmospheric organic aerosol concentrations and properties on the regional to global scale, and (2) to relate atmospheric measurements to sources. A large (but as yet unquantified) fraction of organic aerosol is formed in the atmosphere by precursor gases. In addition, both primary and secondary organic aerosol interact with other gas and aerosol species in the atmosphere so that their properties (i.e., size, hygroscopicity, light absorption and scattering sphere efficiency) can change significantly with time and distance from their source. Organic aerosols (OA) are composed of complex mixtures of different organic species from less-polar organics (n-alkanes, polycyclic aromatic hydrocarbons, fatty alcohols, fatty acids, etc.) to highly polar organics such as dicarboxylic acids and multi-functional organic acids. Studies employing FTIR spectroscopy and NEXAFS have demonstrated the presence of different functional groups such as ketonic and carboxylic groups. Humic-like substances (HULIS) have been identified in aerosols. Field observation and laboratory smog chamber studies have demonstrated that oxidative reactions of biogenic and anthropogenic precursors in the gas phase produce low molecular weight organic acids such as ...
Date: February 23, 2005
Creator: Seinfeld, John H.
Partner: UNT Libraries Government Documents Department

International Conference on Multiscale Methods and Partial Differential Equations.

Description: The International Conference on Multiscale Methods and Partial Differential Equations (ICMMPDE for short) was held at IPAM, UCLA on August 26-27, 2005. The conference brought together researchers, students and practitioners with interest in the theoretical, computational and practical aspects of multiscale problems and related partial differential equations. The conference provided a forum to exchange and stimulate new ideas from different disciplines, and to formulate new challenging multiscale problems that will have impact in applications.
Date: December 12, 2006
Creator: Hou, Thomas
Partner: UNT Libraries Government Documents Department

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

Description: High-Resolution Source Parameters using Calibration from Ambient Seismic Noise (ASN) Zhongwen Zhan, Shengji Wei, Sidao Ni, and Don V. Helmberger Abstract Several new methods have been developed to retrieve local Green's functions based on the cross-correlation of ambient seismic noise (station-to-station) and conventional (source-to-station) inversions. The latter methods provide the most broadband results but require accurate source parameters for phase-delay recovery which depends on the starting model. Considerable progress is being made in providing such information from 3D modeling, Tape et al. (2008), using Adjoint Tomography. But to match waveforms for the recent Chino Hills event still requires shifting synthetics to align on data. This means that it is difficult to use 3D simulations to refine source locations in near-real time. We can avoid the 3D problems by applying the CAP method and storing shifts from past events, Tan (2006), and/or using ASN, Shapiro et al. (2005), to predict lags for surface waves. Here, we directly compare results from CAP predictions with ASN results using stations near the Chino Hills event. We use the same SC seismic model as used in the Library of Earthquakes to generate Green's functions for noise (single force) for comparison with ASN correlations and allow Cap delays. We apply these delays or corrections to determine precise Centroid locations.
Date: April 30, 2009
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
Partner: UNT Libraries Government Documents Department

Center for Plasma Edge Simulation (CPES): Final Technical Report

Description: The Center for Plasma Edge Simulation (CPES) project was a multi-institutional research effort funded jointly by the Office of Advanced Scientific Computing Research (OASCR) and the Office of Fusion Energy Sciences (OFES) within the Department of Energy’s Office of Science. The effort was led by our Principal Investigator, CS Chang, at the Courant Institute for Mathematical Sciences at New York University. The Center included participants from Oak Ridge National Laboratory, Princeton Plasma Physics Laboratory, Lawrence Berkeley National Laboratory, California Institute of Technology, Columbia University, Lehigh University, Rutgers University, University of Colorado, Massachusetts Institute of Technology, University of California at Davis, University of California at Irvine, North Carolina State University, and Georgia Institute of Technology. This report concerns the work performed by Dr. Julian C. Cummings, who was the institutional Principal Investigator for the CPES project at Caltech.
Date: February 19, 2013
Creator: Cummings, Julian C.
Partner: UNT Libraries Government Documents Department