H02 WETLAND TREATMENT SYSTEM WATER CHEMISTRY SAMPLING AND RESULTS REPORT (open access)

H02 WETLAND TREATMENT SYSTEM WATER CHEMISTRY SAMPLING AND RESULTS REPORT

The H-02 Wetland Treatment System (Figure 1) is used to remove heavy metals (e.g., copper and zinc) from the H-Area process and storm water discharge. Routine flow enters an equalization basin by inlets on either the east (Location 1) or west end (Location 2). The west end influent constitutes 75% of the average flow into the basin which has an average residence time of approximately 3 days at low pool (i.e., 120 gal/min. through a volume of 0.5 million gallons). The water then exits via the basin outlet on the east end. Next, the water flows to a splitter box (Location 3) which evenly separates the flow between two wetland cells for a design flow of 60 gal/min. per wetland cell with a residence time in the cell of approximately 2 days. The wetland effluent is then combined (Location 4) and flows through a spillway before reaching the National Pollution Discharge Elimination System (NPDES) measurement point near Road 4. During initial operation, it was observed that the pH of the water leaving the equalization basin was elevated compared to the influent pH. Furthermore, the elevated pH remained through the wetland cells so that there was an average pH of 10 …
Date: February 15, 2008
Creator: Bach, M; Michael Serrato, M & Eric Nelson, E
System: The UNT Digital Library
Separation of Nuclear Fuel Surrogates from Silicon Carbide Inert Matrix (open access)

Separation of Nuclear Fuel Surrogates from Silicon Carbide Inert Matrix

The objective of this project has been to identify a process for separating transuranic species from silicon carbide (SiC). Silicon carbide has become one of the prime candidates for the matrix in inert matrix fuels, (IMF) being designed to reduce plutonium inventories and the long half-lives actinides through transmutation since complete reaction is not practical it become necessary to separate the non-transmuted materials from the silicon carbide matrix for ultimate reprocessing. This work reports a method for that required process.l
Date: December 15, 2008
Creator: Baney, Ronald
System: The UNT Digital Library
Applied Mathematics at the U.S. Department of Energy: Past, Present and a View to the Future (open access)

Applied Mathematics at the U.S. Department of Energy: Past, Present and a View to the Future

Over the past half-century, the Applied Mathematics program in the U.S. Department of Energy's Office of Advanced Scientific Computing Research has made significant, enduring advances in applied mathematics that have been essential enablers of modern computational science. Motivated by the scientific needs of the Department of Energy and its predecessors, advances have been made in mathematical modeling, numerical analysis of differential equations, optimization theory, mesh generation for complex geometries, adaptive algorithms and other important mathematical areas. High-performance mathematical software libraries developed through this program have contributed as much or more to the performance of modern scientific computer codes as the high-performance computers on which these codes run. The combination of these mathematical advances and the resulting software has enabled high-performance computers to be used for scientific discovery in ways that could only be imagined at the program's inception. Our nation, and indeed our world, face great challenges that must be addressed in coming years, and many of these will be addressed through the development of scientific understanding and engineering advances yet to be discovered. The U.S. Department of Energy (DOE) will play an essential role in providing science-based solutions to many of these problems, particularly those that involve the energy, …
Date: February 15, 2008
Creator: Brown, D. L.; Bell, J.; Estep, D.; Gropp, W.; Hendrickson, B.; Keller-McNulty, S. et al.
System: The UNT Digital Library
Continuation of Studies on Development of ODS Heat Exchanger Tubing (open access)

Continuation of Studies on Development of ODS Heat Exchanger Tubing

The Department of Energy (DOE), National Energy Technology Center (NETL), has initiated a strategic plan for the development of advanced technologies needed to design and build fossil fuel plants with very high efficiency and environmental performance. These plants, referred to as 'Vision 21' and FutureGen programs by DOE, will produce electricity, chemicals, fuels, or a combination of these products, and possibly secondary products such as steam/heat for industrial use. MA956 is a prime candidate material being considered for a high temperature heat exchanger in the 'Vision 21' and FutureGen programs. This material is an oxide dispersion strengthened (ODS) alloy; however, there are some gaps in the data required to commit to the use of these alloys in a full-size plant. To fill the technology gaps for commercial production and use of the material for 'Advanced Power Generation Systems' this project has performed development activity to significant increase in circumferential strength of MA956 as compared to currently available material, investigated bonding technologies for bonding tube-to-tube joints through joining development, and performed tensile, creep and fire-side corrosion tests to validate the use and fabrication processes of MA956 to heat exchanger tubing applications. Development activities within this projected has demonstrated increased circumferential strength …
Date: April 15, 2008
Creator: Brown, Lawrence; Workman, David; Kad, Bimal; Smith, Gaylord; Robertson, Archie & Wright, Ian
System: The UNT Digital Library
Evaluation of the 2007 Toyota Camry Hybrid Syneregy Drive System (open access)

Evaluation of the 2007 Toyota Camry Hybrid Syneregy Drive System

The U.S. Department of Energy (DOE) and American automotive manufacturers General Motors, Ford, and DaimlerChrysler began a five-year, cost-shared partnership in 1993. Currently, hybrid electric vehicle (HEV) research and development is conducted by DOE through its FreedomCAR and Vehicle Technologies (FCVT) program. The mission of the FCVT program is to develop more energy efficient and environmentally friendly highway transportation technologies. Program activities include research, development, demonstration, testing, technology validation, and technology transfer. These activities are aimed at developing technologies that can be domestically produced in a clean and cost-competitive manner. Under the FCVT program, support is provided through a three-phase approach [1] which is intended to: • Identify overall propulsion and vehicle-related needs by analyzing programmatic goals and reviewing industry’s recommendations and requirements, then develop the appropriate technical targets for systems, subsystems, and component research and development activities; • Develop and validate individual subsystems and components, including electric motors, emission control devices, battery systems, power electronics, accessories, and devices to reduce parasitic losses; and • Determine how well the components and subassemblies work together in a vehicle environment or as a complete propulsion system and whether the efficiency and performance targets at the vehicle level have been achieved. The research …
Date: April 15, 2008
Creator: Burress, T. A.; Coomer, C. L.; Campbell, S. L.; Seiber, L. E.; Marlino, L. D.; Staunton, R. H. et al.
System: The UNT Digital Library
EMSL Strategic Plan 2008 (open access)

EMSL Strategic Plan 2008

This Strategic Plan is EMSL’s template for achieving our vision of simultaneous excellence in all aspects of our mission as a national scientific user facility. It reflects our understanding of the long-term stewardship we must work toward to meet the scientific challenges of the Department of Energy and the nation. During the next decade, we will implement the strategies contained in this Plan, working closely with the scientific community, our advisory committees, DOE’s Office of Biological and Environmental Research, and other key stakeholders. This Strategic Plan is fully aligned with the strategic plans of DOE and its Office of Science. We recognize that shifts in science and technology, national priorities, and resources made available through the Federal budget process create planning uncertainties and, ultimately, a highly dynamic planning environment. Accordingly, this Strategic Plan should be viewed as a living document for which we will continually evaluate changing needs and opportunities posed by our stakeholders (i.e., DOE, users, staff, advisory committees), work closely with them to understand and respond to those changes, and align our strategy accordingly.
Date: August 15, 2008
Creator: Campbell, Allison A.
System: The UNT Digital Library
Hanford Tank 241-C-103 Residual Waste Contaminant Release Models and Supporting Data (open access)

Hanford Tank 241-C-103 Residual Waste Contaminant Release Models and Supporting Data

This report tabulates data generated by laboratory characterization and testing of three samples collected from tank C-103. The data presented here will form the basis for a release model that will be developed for tank C-103. These release models are being developed to support the tank risk assessments performed by CH2M HILL Hanford Group, Inc. for DOE.
Date: January 15, 2008
Creator: Cantrell, Kirk J.; Krupka, Kenneth M.; Deutsch, William J.; Lindberg, Michael J.; Schaef, Herbert T.; Geiszler, Keith N. et al.
System: The UNT Digital Library
Remaining Sites Verification Package for the 100-F-50 Stormwater Runoff Culvert, Waste Site Reclassification Form 2007-001 (open access)

Remaining Sites Verification Package for the 100-F-50 Stormwater Runoff Culvert, Waste Site Reclassification Form 2007-001

The 100-F-50 waste site, part of the 100-FR-2 Operable Unit, is a steel stormwater runoff culvert that runs between two railroad grades in the south-central portion of the 100-F Area. The culvert exiting the west side of the railroad grade is mostly encased in concrete and surrounded by a concrete stormwater collection depression partially filled with soil and vegetation. The drain pipe exiting the east side of the railroad grade embankment is partially filled with soil and rocks. The 100-F-50 stormwater diversion culvert confirmatory sampling results support a reclassification of this site to no action. The current site conditions achieve the remedial action objectives and corresponding remedial action goals established in the Remaining Sites ROD. The results of confirmatory sampling show that residual contaminant concentrations do not preclude any future uses and allow for unrestricted use of shallow zone soils. The results also demonstrate that residual contaminant concentrations are protective of groundwater and the Columbia River.
Date: April 15, 2008
Creator: Capron, J. M.
System: The UNT Digital Library
Perspectives on distributed computing : thirty people, four user types, and the distributed computing user experience. (open access)

Perspectives on distributed computing : thirty people, four user types, and the distributed computing user experience.

This report summarizes the methodology and results of a user perspectives study conducted by the Community Driven Improvement of Globus Software (CDIGS) project. The purpose of the study was to document the work-related goals and challenges facing today's scientific technology users, to record their perspectives on Globus software and the distributed-computing ecosystem, and to provide recommendations to the Globus community based on the observations. Globus is a set of open source software components intended to provide a framework for collaborative computational science activities. Rather than attempting to characterize all users or potential users of Globus software, our strategy has been to speak in detail with a small group of individuals in the scientific community whose work appears to be the kind that could benefit from Globus software, learn as much as possible about their work goals and the challenges they face, and describe what we found. The result is a set of statements about specific individuals experiences. We do not claim that these are representative of a potential user community, but we do claim to have found commonalities and differences among the interviewees that may be reflected in the user community as a whole. We present these as a series …
Date: October 15, 2008
Creator: Childers, L.; Liming, L.; Foster, I.; Science, Mathematics and Computer & Chicago, Univ. of
System: The UNT Digital Library
Final Technical Report (open access)

Final Technical Report

Most prokaryotes of interest to DOE are poorly understood. Even when full genomic sequences are available, the function of only a small number of gene products are clear. The critical question is how to best infer the most probable network architectures in cells that are poorly characterized. The project goal is to create a computational hypothesis testing (CHT) framework that combines large-scale dynamical simulation, a database of bioinformatics-derived probable interactions, and numerical parallel architecture data-fitting routines to explore many “what if ?” hypotheses about the functions of genes and proteins within pathways and their downstream effects on molecular concentration profiles and corresponding phenotypes. From this framework we expect to infer signal transduction pathways and gene expression networks in prokaryotes. Detailed mechanistic models of E. Coli have been developed that directly incorporate DNA sequence information. The CHT framework is implemented in the NIEngine network inference software. NIEngine has been applied to recover gene regulatory networks in E. coli to assess performance. Application to Shewanel la oneidensi and other organism of interest DOE will be conducted in partnership with Jim Collin's Lab at Boston University and other academic partners. The CHT framework has also found broad application in the automated learning of …
Date: October 15, 2008
Creator: Church, Bruce W
System: The UNT Digital Library
WASTE CHARACTERIZATION OF POLYMERIC COMPONENTS EXPOSED TO TRITIUM GAS (open access)

WASTE CHARACTERIZATION OF POLYMERIC COMPONENTS EXPOSED TO TRITIUM GAS

A recent independent review led to uncertainty about the technical basis for characterizing the residual amount of tritium in polymer components used in the Savannah River Site Tritium Facilities that are sent for waste disposal. A review of a paper published in the open literature firmly establishes the basis of the currently used characterization, 10 Ci/cc. Information provided in that paper about exposure experiments performed at the DOE Mound Laboratory allows the calculation of the currently used characterization. These experiments involved exposure of high density polyethylene (HD-PE) to initially 1 atm tritium gas. In addition, a review of recent research at the Savannah River Site not only further substantiates this characterization, but also establishes its use for ultra-high molecular weight polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE, a trade name is Teflon{reg_sign}), and Vespel{reg_sign} polyimide. 10 Ci/cc tritium is a representative characterization for any type of polymer components exposed at ambient temperature and at approximately 1 atm. tritium gas.
Date: February 15, 2008
Creator: Clark, E
System: The UNT Digital Library
Grid Computing Education Support (open access)

Grid Computing Education Support

The GGF Student Scholar program enabled GGF the opportunity to bring over sixty qualified graduate and under-graduate students with interests in grid technologies to its three annual events over the three-year program.
Date: January 15, 2008
Creator: Crumb, Steven
System: The UNT Digital Library
Structural Biology and Molecular Medicine Research Program (LSBMM) (open access)

Structural Biology and Molecular Medicine Research Program (LSBMM)

The UCLA-DOE Institute of Genomics and Proteomics is an organized research unit of the University of California, sponsored by the Department of Energy through the mechanism of a Cooperative Agreement. Today the Institute consists of 10 Principal Investigators and 7 Associate Members, developing and applying technologies to promote the biological and environmental missions of the Department of Energy, and 5 Core Technology Centers to sustain this work. The focus is on understanding genomes, pathways and molecular machines in organisms of interest to DOE, with special emphasis on developing enabling technologies. Since it was founded in 1947, the UCLA-DOE Institute has adapted its mission to the research needs of DOE and its progenitor agencies as these research needs have changed. The Institute started as the AEC Laboratory of Nuclear Medicine, directed by Stafford Warren, who later became the founding Dean of the UCLA School of Medicine. In this sense, the entire UCLA medical center grew out of the precursor of our Institute. In 1963, the mission of the Institute was expanded into environmental studies by Director Ray Lunt. I became the third director in 1993, and in close consultation with David Galas and John Wooley of DOE, shifted the mission of …
Date: July 15, 2008
Creator: Eisenberg, David S.
System: The UNT Digital Library
REAL TIME SYSTEM OPERATIONS 2006-2007 (open access)

REAL TIME SYSTEM OPERATIONS 2006-2007

The Real Time System Operations (RTSO) 2006-2007 project focused on two parallel technical tasks: (1) Real-Time Applications of Phasors for Monitoring, Alarming and Control; and (2) Real-Time Voltage Security Assessment (RTVSA) Prototype Tool. The overall goal of the phasor applications project was to accelerate adoption and foster greater use of new, more accurate, time-synchronized phasor measurements by conducting research and prototyping applications on California ISO's phasor platform - Real-Time Dynamics Monitoring System (RTDMS) -- that provide previously unavailable information on the dynamic stability of the grid. Feasibility assessment studies were conducted on potential application of this technology for small-signal stability monitoring, validating/improving existing stability nomograms, conducting frequency response analysis, and obtaining real-time sensitivity information on key metrics to assess grid stress. Based on study findings, prototype applications for real-time visualization and alarming, small-signal stability monitoring, measurement based sensitivity analysis and frequency response assessment were developed, factory- and field-tested at the California ISO and at BPA. The goal of the RTVSA project was to provide California ISO with a prototype voltage security assessment tool that runs in real time within California ISO?s new reliability and congestion management system. CERTS conducted a technical assessment of appropriate algorithms, developed a prototype incorporating state-of-art …
Date: August 15, 2008
Creator: Eto, Joseph H.; Parashar, Manu & Lewis, Nancy Jo
System: The UNT Digital Library
Scaling Up: Kilolumen Solid-State Lighting Exceeding 100 LPW via Remote Phosphor (open access)

Scaling Up: Kilolumen Solid-State Lighting Exceeding 100 LPW via Remote Phosphor

This thirty-month project was successful in attaining its ambitious objectives of demonstrating a radically novel 'remote-phosphor' LED light source that can out-perform conventional conformal coated phosphor LED sources. Numerous technical challenges were met with innovative techniques and optical configurations. This product development program for a new generation of solid-state light sources has attained unprecedented luminosity (over 1 kilo-lumen) and efficacy (based on the criterion lumens per 100mw radiant blue). LPI has successfully demonstrated its proprietary technology for optical synthesis of large uniform sources out of the light output of an array of separated LEDs. Numerous multiple blue LEDs illuminate single a phosphor patch. By separating the LEDs from the phosphor, the phosphor and LEDs operate cooler and with higher efficiency over a wide range of operating conditions (from startup to steady state). Other benefits of the system include: better source uniformity, more types of phosphor can be used (chemical interaction and high temperatures are no longer an issue), and the phosphor can be made up from a pre-manufactured sheet (thereby lowering cost and complexity of phosphor deposition). Several laboratory prototypes were built and operated at the expected high performance level. The project fully explored two types of remote phosphor system: …
Date: September 15, 2008
Creator: Falicoff, Waqidi
System: The UNT Digital Library
Final Report Construction of Whole Genome Microarrays, and Expression Analysis of Desulfovibrio vulgaris cells in Metal-Reducing Conditions (open access)

Final Report Construction of Whole Genome Microarrays, and Expression Analysis of Desulfovibrio vulgaris cells in Metal-Reducing Conditions

We continue to utilize the oligonucleotide microarrays that were constructed through funding with this project to characterize growth responses of Desulfovibrio vulgaris relevant to metal-reducing conditions. To effectively immobilize heavy metals and radionuclides via sulfate-reduction, it is important to understand the cellular responses to adverse factors observed at contaminated subsurface environments (e.g., nutrients, pH, contaminants, growth requirements and products). One of the major goals of the project is to construct whole-genome microarrays for Desulfovibrio vulgaris. First, in order to experimentally establish the criteria for designing gene-specific oligonucleotide probes, an oligonucleotide array was constructed that contained perfect match (PM) and mismatch (MM) probes (50mers and 70mers) based upon 4 genes. The effects of probe-target identity, continuous stretch, mismatch position, and hybridization free energy on specificity were examined. Little hybridization was observed at a probe-target identity of <85% for both 50mer and 70mer probes. 33 to 48% of the PM signal intensities were detected at a probe-target identity of 94% for 50mer oligonucleotides, and 43 to 55% for 70mer probes at a probe-target identity of 96%. When the effects of sequence identity and continuous stretch were considered independently, a stretch probe (>15 bases) contributed an additional 9% of the PM signal intensity …
Date: May 15, 2008
Creator: Fields, M.W.; Wall, J.D.; Keasling, J. & Zhou, J.
System: The UNT Digital Library
Considerations for Emerging Markets for Energy Savings Certificates (open access)

Considerations for Emerging Markets for Energy Savings Certificates

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Date: September 15, 2008
Creator: Friedman, Barry; Bird, Lori & Barbose, Galen
System: The UNT Digital Library
Mechanisms of the Bystander Effect (open access)

Mechanisms of the Bystander Effect

Generations of students in radiation biology have been taught that heritable biological damage requires direct damage to DNA. We now know that this is not true. The Bystander Effect is the name given to the phenomenon whereby biological effects are observed in cells that are not themselves traversed by a charged particle, but are in close proximity to cells that are. Several research groups have convincingly demonstrated a bystander effect for alpha particle, which are heavy and high LET, because charged particles can be focused into a tiny beam that can be directed onto individual cells. The biological effects seen in adjacent non-hit cells clearly represents a bystander effect. It is not so easy to demonstrate a similar effect for x-rays or for the electrons set in motion by the absorption of x-rays. In this project we used two types of cell that could be recognized one from the other. One cell type was fed radioactive tritiated thymidine, which is incorporated into the DNA, . The tritium emits electrons which have a very short range so that they do not even get out of the cell. These cells were then mixed with a different type of cell which are routinely …
Date: July 15, 2008
Creator: Hall, Eric J.
System: The UNT Digital Library
State-of-the-Art Beta Detection and Dosimetry (open access)

State-of-the-Art Beta Detection and Dosimetry

The research funded by this NEER grant establishes the framework for a detailed understanding of the challenges in beta dosimetry, especially in the presence of a mixed radiation field. The work also stimulated the thinking of the research group which will lead to new concepts in digital signal processing to allow collection of detection signals and real-time analysis such that simultaneous beta and gamma spectroscopy can take place. The work described herein (with detail in the many publications that came out of this research) was conducted in a manner that provided dissertation and thesis topics for three students, one of whom was completely funded by this grant. The overall benefit of the work came in the form of a dramatic shift in signal processing that is normally conducted in analog pulse shape analysis. Analog signal processing was shown not to be feasible for this type of work; digital signal processing was a must. This, in turn, led the research team to a new understanding of pulse analysis, one in which expands the state-of-the-art in simultaneous beta and gamma spectroscopy with a single detector.
Date: August 15, 2008
Creator: Hamby, David M.
System: The UNT Digital Library
Scaleable Clean Aluminum Melting Systems (open access)

Scaleable Clean Aluminum Melting Systems

The project entitled 'Scaleable Clean Aluminum Melting Systems' was a Cooperative Research and Development Agreements (CRADAs) between Oak Ridge National Laboratory (ORNL) and Secat Inc. The three-year project was initially funded for the first year and was then canceled due to funding cuts at the DOE headquarters. The limited funds allowed the research team to visit industrial sites and investigate the status of using immersion heaters for aluminum melting applications. Primary concepts were proposed on the design of furnaces using immersion heaters for melting. The proposed project can continue if the funding agency resumes the funds to this research. The objective of this project was to develop and demonstrate integrated, retrofitable technologies for clean melting systems for aluminum in both the Metal Casting and integrated aluminum processing industries. The scope focused on immersion heating coupled with metal circulation systems that provide significant opportunity for energy savings as well as reduction of melt loss in the form of dross. The project aimed at the development and integration of technologies that would enable significant reduction in the energy consumption and environmental impacts of melting aluminum through substitution of immersion heating for the conventional radiant burner methods used in reverberatory furnaces. Specifically, the …
Date: February 15, 2008
Creator: Han, Q. & Das, S.K. (Secat, Inc.)
System: The UNT Digital Library
ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS (open access)

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

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 …
Date: April 15, 2008
Creator: Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J.
System: The UNT Digital Library
Phase 2 Reese River Geothermal Project Slim Well 56-4 Drilling and Testing (open access)

Phase 2 Reese River Geothermal Project Slim Well 56-4 Drilling and Testing

This report covers the drilling and testing of the slim well 56-4 at the Reese River Geothermal Project in Lander County, Nevada. This well was partially funded through a GRED III Cooperative Funding Agreement # DE-FC36-04GO14344, from USDOE.
Date: June 15, 2008
Creator: Henkle, William R. & Ronne, Joel
System: The UNT Digital Library
Scrape-off Layer Current Model for Filament Structure Observed during Edge Localized Modes (ELMs) in the DIII-D Tokamak (open access)

Scrape-off Layer Current Model for Filament Structure Observed during Edge Localized Modes (ELMs) in the DIII-D Tokamak

The plasma in tokamaks often exhibits a relaxation oscillation called the edge localized mode (ELM), which is generally attributed to MHD instability driven by strong gradients at the plasma boundary. It is shown here that field-aligned currents flowing just outside the boundary may also play a role in the ELM process. The poloidal perturbation magnetic field during ELMs in the DIII–D tokamak calculated from measured currents can reproduce prominent observed features, including a narrow magnetic structure at the outboard midplane similar to filaments observed earlier in DIII–D and NSTX.
Date: April 15, 2008
Creator: Hironori Takahashi, E. D. Fredrickson, and M.J. Schaffer
System: The UNT Digital Library
Attenuated Vector Tomography -- An Approach to Image Flow Vector Fields with Doppler Ultrasonic Imaging (open access)

Attenuated Vector Tomography -- An Approach to Image Flow Vector Fields with Doppler Ultrasonic Imaging

The measurement of flow obtained using continuous wave Doppler ultrasound is formulated as a directional projection of a flow vector field. When a continuous ultrasound wave bounces against a flowing particle, a signal is backscattered. This signal obtains a Doppler frequency shift proportional to the speed of the particle along the ultrasound beam. This occurs for each particle along the beam, giving rise to a Doppler velocity spectrum. The first moment of the spectrum provides the directional projection of the flow along theultrasound beam. Signals reflected from points further away from the detector will have lower amplitude than signals reflected from points closer to the detector. The effect is very much akin to that modeled by the attenuated Radon transform in emission computed tomography.A least-squares method was adopted to reconstruct a 2D vector field from directional projection measurements. Attenuated projections of only the longitudinal projections of the vector field were simulated. The components of the vector field were reconstructed using the gradient algorithm to minimize a least-squares criterion. This result was compared with the reconstruction of longitudinal projections of the vector field without attenuation. Ifattenuation is known, the algorithm was able to accurately reconstruct both components of the full vector …
Date: May 15, 2008
Creator: Huang, Qiu; Peng, Qiyu; Huang, Bin; Cheryauka, Arvi & Gullberg, Grant T.
System: The UNT Digital Library