Nonlinear Statistical Signal Processing: A Particle Filtering Approach (open access)

Nonlinear Statistical Signal Processing: A Particle Filtering Approach

A introduction to particle filtering is discussed starting with an overview of Bayesian inference from batch to sequential processors. Once the evolving Bayesian paradigm is established, simulation-based methods using sampling theory and Monte Carlo realizations are discussed. Here the usual limitations of nonlinear approximations and non-gaussian processes prevalent in classical nonlinear processing algorithms (e.g. Kalman filters) are no longer a restriction to perform Bayesian inference. It is shown how the underlying hidden or state variables are easily assimilated into this Bayesian construct. Importance sampling methods are then discussed and shown how they can be extended to sequential solutions implemented using Markovian state-space models as a natural evolution. With this in mind, the idea of a particle filter, which is a discrete representation of a probability distribution, is developed and shown how it can be implemented using sequential importance sampling/resampling methods. Finally, an application is briefly discussed comparing the performance of the particle filter designs with classical nonlinear filter implementations.
Date: September 19, 2007
Creator: Candy, J
Object Type: Article
System: The UNT Digital Library
MEMS adaptive optics for the Gemini Planet Imager: control methods and validation (open access)

MEMS adaptive optics for the Gemini Planet Imager: control methods and validation

None
Date: December 19, 2007
Creator: Poyneer, L A & Dillon, D
Object Type: Article
System: The UNT Digital Library
Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740 (open access)

Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740

In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Special Metals Corporation (SMC) to determine the mechanical property response of the IN740 alloy to help establish thermo-mechanical processing parameters for the use of this alloy in supercritical and ultra-critical boiler tubes with the potential for other end uses. SMC had developed an alloy, commercially known as INCONEL alloy 740, which exhibited various beneficial physical, mechanical, and chemical properties. As part of SMC's on-going efforts to optimize this alloy for targeted boiler applications there was a need to develop an understanding of the thermo-mechanical response of the material, characterize the resulting microstructure from this processing, and possibly, utilize models to develop the appropriate processing scheme for this product.
Date: November 19, 2007
Creator: Ludtka, G.M. & Smith, G.
Object Type: Report
System: The UNT Digital Library
Linear Multifrequency-Grey Acceleration Recast for Preconditioned Krylov Iterations (open access)

Linear Multifrequency-Grey Acceleration Recast for Preconditioned Krylov Iterations

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Date: March 19, 2007
Creator: Morel, J E; Yang, T B & Warsa, J S
Object Type: Article
System: The UNT Digital Library

Long-term Stability of Biogeochemically Reduced U and Cr in Contaminated Sediments

The general goal of this report is to diminish concentrations of metals/radionuclide in groundwaters of contaminated sites to below MCL values through reduction to lower solubility species.
Date: April 19, 2007
Creator: Tetsu Tokunaga, Jiamin Wan, Yongman Kim, Terry Hazen, Eoin Brodie, Zuoping Zheng, Jackie Pena
Object Type: Presentation
System: The UNT Digital Library

Kinetic Controls on the Desorption/Dissolution of Sorbed U(VI) and Their Influence on Reactive Transport

None
Date: April 19, 2007
Creator: Zachara, J. M.; Liu, C.; Qafoku, N.; McKinley, J. P.; Davis, J. A.; Stoliker, D. et al.
Object Type: Poster
System: The UNT Digital Library

Development of Modeling Methods and Tools for Predicting Coupled Reactive Transport Processes in Porous Media at Multiple Scales

None
Date: April 19, 2007
Creator: Kanel, S. R.; Loganathan, V. A.; Jeppu, G.; Kumar, A.; Srinivasan, V.; Radu, T. et al.
Object Type: Poster
System: The UNT Digital Library

Mechanistically-Based Field-Scale Models of Uranium Biogeochemistry from Upscaling Pore-Scale Experiments and Models

Effective environmental management of DOE sites requires reliable prediction of reactive transport phenomena. A central issue in prediction of subsurface reactive transport is the impact of multiscale physical, chemical, and biological heterogeneity. Heterogeneity manifests itself through incomplete mixing of reactants at scales below those at which concentrations are explicitly defined (i.e., the numerical grid scale). This results in a mismatch between simulated reaction processes (formulated in terms of average concentrations) and actual processes (controlled by local concentrations). At the field scale, this results in apparent scale-dependence of model parameters and inability to utilize laboratory parameters in field models. Accordingly, most field modeling efforts are restricted to empirical estimation of model parameters by fitting to field observations, which renders extrapolation of model predictions beyond fitted conditions unreliable. The objective of this project is to develop a theoretical and computational framework for (1) connecting models of coupled reactive transport from pore-scale processes to field-scale bioremediation through a hierarchy of models that maintain crucial information from the smaller scales at the larger scales; and (2) quantifying the uncertainty that is introduced by both the upscaling process and uncertainty in physical parameters. One of the challenges of addressing scale-dependent effects of coupled processes in …
Date: April 19, 2007
Creator: Scheibe, Tim; Tartakovsky, Alexandre; Wood, Brian & Seymour, Joe
Object Type: Poster
System: The UNT Digital Library

Applying EMSL Capabilities to Biogeochemistry and Environmental Research

The Environmental Molecular Sciences laboratory (EMSL) is a national scientific user facility operated by the Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy's Office of Biological and Environmental Research. Located in Richland, Washington, EMSL offers researchers a comprehensive array of cutting-edge capabilities unmatched anywhere else in the world and access to the expertise of over 300 resident users--all at one location. EMSL's resources are available on a peer-reviewed proposal basis and are offered at no cost if research results are shared in the open literature. Researchers are encouraged to submit a proposal centered around one of EMSL's four Science Themes, which represent growing areas of research: (1) Geochemistry/Biogeochemistry and Subsurface Science; (2) Atmospheric Aerosol Chemistry; (3) Biological Interactions and Dynamics; and (4) Science of Interfacial Phenomena. To learn more about EMSL, visit www.emsl.pnl.gov.
Date: April 19, 2007
Creator: Felmy, Andy
Object Type: Poster
System: The UNT Digital Library
Speckle Noise Attenuation in Coronagraphy and High-Contrast Imaging (open access)

Speckle Noise Attenuation in Coronagraphy and High-Contrast Imaging

None
Date: September 19, 2007
Creator: Marois, C
Object Type: Article
System: The UNT Digital Library

Scale Dependence of Biogeochemical Reaction Rates: Experimental and Modeling Approaches

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Date: April 19, 2007
Creator: Steefel, Carl I.; Li, Li & Yang, Li
Object Type: Presentation
System: The UNT Digital Library

Responses of Desulfovibrio vulgaris to Physiological Constraints Relevant to Bioremediation in the Field

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Date: April 19, 2007
Creator: Fields, Matthew W.
Object Type: Presentation
System: The UNT Digital Library
STRANGENESS PRODUCTION AS A FUNCTION OF SYSTEM SIZE AND ENERGY OF RHIC. (open access)

STRANGENESS PRODUCTION AS A FUNCTION OF SYSTEM SIZE AND ENERGY OF RHIC.

In this paper we report on strangeness measurements in p+p, Au+Au and Cu+Cu collisions at different energies in the STAR detector at RHIC. We will focus on two momentum regions in particular: Firstly we look at strangeness enhancement in A+A collisions with respect to p+p. These yields are dominated by low transverse momentum. We compare the enhancements from Au+Au and Cu+Cu data at {radical}s{sub NN} = 200 GeV with Pb+Pb data at {radical}s{sub NN} = 17.2 GeV and find that the enhancement does not scale with N{sub part} as expected, but rather scales with N{sub part}{sup 1/3}, where N{sub part} represents the number of participants; We then examine {Lambda}/K{sub S}{sup 0} ratios at intermediate transverse momentum in both Au+Au and Cu+Cu data where we find a greater enhancement in Cu+Cu compared to Au+Au data when we compare integrated ratios between 1.5 < p{sub T} < 3.5 GeV/c.
Date: July 19, 2007
Creator: LAMONT,M.
Object Type: Article
System: The UNT Digital Library
Mechanism of Bacterial Uranium and Technetium Reduction (open access)

Mechanism of Bacterial Uranium and Technetium Reduction

None
Date: April 19, 2007
Creator: DiChristina, Thomas
Object Type: Article
System: The UNT Digital Library
LCLS soft x-ray imager mirrors and their performance (open access)

LCLS soft x-ray imager mirrors and their performance

Soft X-ray imager mirrors have been designed, calibrated and fabricated at Lawrence Livermore National Laboratory and characterized at the Advanced Light Source for their performance between 200 and 1300 eV. The mirrors are coated with a multilayer coating consisting of 70 bilayers of W/ SiC. The mirrors are to reflect at 22.5 deg from grazing angle at 1.50 nm wavelength and the width of the reflectivity peak should be at least 1.3%. Also, the mirrors should be non-reflective elsewhere. Our multilayer design was optimized to satisfy these requirements. The coating is very challenging since the individual layer thicknesses need to be less than 1 nm thick and reproducibility from layer to layer is crucial. To minimize the second harmonic peak we designed a multilayer with {Gamma} = 0.5 (W and SiC layer thicknesses are the same). This way we end up with a mirror that has only the 1st and 3rd harmonic peak as shown in Figure 1. To suppress reflectivity outside the first peak we used our novel approach, an antireflective coating. Modeling predicted substantial reduction in reflectivity, especially for lower energies as shown in Figure 1. The experimental results of the soft x-ray imager mirror as measured at …
Date: October 19, 2007
Creator: Bajt, S
Object Type: Report
System: The UNT Digital Library
Electron Beam Lifetime in SPEAR3: Measurement and Simulation (open access)

Electron Beam Lifetime in SPEAR3: Measurement and Simulation

In this paper we report on electron beam lifetime measurements as a function of scraper position, RF voltage and bunch fill pattern in SPEAR3. We then outline development of an empirical, macroscopic model using the beam-loss rate equation. By identifying the dependence of loss coefficients on accelerator and beam parameters, a numerically-integrating simulator can be constructed to compute beam decay with time. In a companion paper, the simulator is used to train a parametric, non-linear dynamics model for the system [1].
Date: December 19, 2007
Creator: Corbett, J.; Huang, X.; Lee, M. & Lui, P.
Object Type: Article
System: The UNT Digital Library
Fabrication of Pillar-Structured Thermal Neutron Detectors (open access)

Fabrication of Pillar-Structured Thermal Neutron Detectors

Pillar detector is an innovative solid state device structure that leverages advanced semiconductor fabrication technology to produce a device for thermal neutron detection. State-of-the-art thermal neutron detectors have shortcomings in achieving simultaneously high efficiency, low operating voltage while maintaining adequate fieldability performance. By using a 3-dimensional silicon PIN diode pillar array filled with isotopic boron 10, ({sup 10}B) a high efficiency device is theoretically possible. The fabricated pillar structures reported in this work are composed of 2 {micro}m diameter silicon pillars with a 4 {micro}m pitch and pillar heights of 6 and 12 {micro}m. The pillar detector with a 12 {micro}m height achieved a thermal neutron detection efficiency of 7.3% at 2V.
Date: November 19, 2007
Creator: Nikolic, R. J.; Conway, A. M.; Reinhardt, C. E.; Graff, R. T.; Wang, T. F.; Deo, N. et al.
Object Type: Article
System: The UNT Digital Library
Effects of Chromium(VI) and Chromium(III) on Desulfovibrio vulgaris Cells (open access)

Effects of Chromium(VI) and Chromium(III) on Desulfovibrio vulgaris Cells

Desulfovibrio vulgaris ATCC 29579 is a well studied sulfate reducer that has known capabilities of reducing heavy metals and radionuclides, like chromium and uranium. Cultures grown in a defined medium (i.e. LS4D) had a lag period of approximately 40 h when exposed to 50 μMof Cr(VI). Substrate analysis revealed that although chromium is reduced within the first 5 h, growth does not resume for another 35 h. During this time, small amounts of lactate are still utilized but the reduction of sulfate does not occur. Sulfate reduction occurs concurrently with the accumulation of acetate approximately 40 h after inoculation, when growth resumes. Similar amounts of hydrogen are produced during this time compared to hydrogen production by cells not exposed to Cr(VI); therefore an accumulation of hydrogen cannot account for the utilization of lactate. There is a significant decrease in the carbohydrate to protein ratio at approximately 25 h, and this result indicated that lactate is not converted to glycogen. Most probable number analysis indicated that cell viability decreased steadily after inoculation and reached approximately 6 x 104 cells/ml 20 h post-chromium exposure. Regeneration of reducing conditions during chromium exposure does not induce growth and in fact may make the growth …
Date: April 19, 2007
Creator: Clark, M.E.; Klonowska, A.; Thieman, S.B.; Giles, B.; Wall, J.D. & Fields, and M.W.
Object Type: Article
System: The UNT Digital Library
Empirical evidence for a recent slowdown in irrigation-induced cooling (open access)

Empirical evidence for a recent slowdown in irrigation-induced cooling

Understanding the influence of past land use changes on climate is needed to improve regional projections of future climate change and inform debates about the tradeoffs associated with land use decisions. The effects of rapid expansion of irrigated area in the 20th century has remained unclear relative to other land use changes, such as urbanization, that affected a similar total land area. Using spatial and temporal variations in temperature and irrigation extent observed in California, we show that irrigation expansion has had a large cooling effect on summertime average daily daytime temperatures (-0.15 to -0.25 C.decade{sup -1}), which corresponds to a cooling estimated at -2.0 - -3.3 C since the introduction of irrigation practice. Irrigation has negligible effects on nighttime temperatures, leading to a net cooling effect of irrigation on climate (-0.06 to -0.19 C.decade{sup -1}). Stabilization of irrigated area has occurred in California since 1980 and is expected in the near future for most irrigated regions. The suppression of past human-induced greenhouse warming by increased irrigation is therefore likely to slow in the future, and a potential decrease in irrigation may even contribute to a more rapid warming. Changes in irrigation alone are not expected to influence broadscale temperatures, …
Date: January 19, 2007
Creator: Bonfils, C & Lobell, D
Object Type: Article
System: The UNT Digital Library

Microcantilever Sensors for in-situ Sub-surface Characterization

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Date: April 19, 2007
Creator: Thundat, Thomas; Gu, Bahua & Brown, and Gilbert
Object Type: Presentation
System: The UNT Digital Library

Microbiological, Geochemical and Microbiological, Geochemical and Hydrologic Processes Controlling Uranium Mobility: An Integrated Field-Scale Subsurface Research Challenge Site at Rifle, Colorado

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Date: April 19, 2007
Creator: Long, P. E.; Banfield, J.; Chandler, D.P.; Davis, J.A.; Hettich, B.; Jaffe, P.R. et al.
Object Type: Presentation
System: The UNT Digital Library
Birth of Massive Black Hole Binaries (open access)

Birth of Massive Black Hole Binaries

If massive black holes (BHs) are ubiquitous in galaxies and galaxies experience multiple mergers during their cosmic assembly, then BH binaries should be common albeit temporary features of most galactic bulges. Observationally, the paucity of active BH pairs points toward binary lifetimes far shorter than the Hubble time, indicating rapid inspiral of the BHs down to the domain where gravitational waves lead to their coalescence. Here, we review a series of studies on the dynamics of massive BHs in gas-rich galaxy mergers that underscore the vital role played by a cool, gaseous component in promoting the rapid formation of the BH binary. The BH binary is found to reside at the center of a massive self-gravitating nuclear disc resulting from the collision of the two gaseous discs present in the mother galaxies. Hardening by gravitational torques against gas in this grand disc is found to continue down to sub-parsec scales. The eccentricity decreases with time to zero and when the binary is circular, accretion sets in around the two BHs. When this occurs, each BH is endowed with it own small-size ({approx}< 0.01 pc) accretion disc comprising a few percent of the BH mass. Double AGN activity is expected to …
Date: November 19, 2007
Creator: Colpi, M.; Dotti, M.; Mayer, L. & Kazantzidis, S.
Object Type: Article
System: The UNT Digital Library