Transmission electron microscopy of oxide dispersion strengthened (ODS) molybdenum: effects of irradiation on material microstructure (open access)

Transmission electron microscopy of oxide dispersion strengthened (ODS) molybdenum: effects of irradiation on material microstructure

Oxide dispersion strengthened (ODS) molybdenum has been characterized using transmission electron microscopy (TEM) to determine the effects of irradiation on material microstructure. This work describes the results-to-date from TEM characterization of unirradiated and irradiated ODS molybdenum. The general microstructure of the unirradiated material consists of fine molybdenum grains (< 5 {micro}m average grain size) with numerous low angle boundaries and isolated dislocation networks. 'Ribbon'-like lanthanum oxides are aligned along the working direction of the product form and are frequently associated with grain boundaries, serving to inhibit grain boundary and dislocation movement. In addition to the 'ribbons', discrete lanthanum oxide particles have also been detected. After irradiation, the material is characterized by the presence of nonuniformly distributed large ({approx} 20 to 100 nm in diameter), multi-faceted voids, while the molybdenum grain size and oxide morphology appear to be unaffected by irradiation.
Date: March 3, 2003
Creator: Baranwal, R. and Burke, M.G.
Object Type: Report
System: The UNT Digital Library
Application of a pilot control banding tool for risk level assessment and control of nanoparticle exposures (open access)

Application of a pilot control banding tool for risk level assessment and control of nanoparticle exposures

Control Banding (CB) strategies offer simplified solutions for controlling worker exposures to constituents that are found in the workplace in the absence of firm toxicological and exposure data. These strategies may be particularly useful in nanotechnology applications, considering the overwhelming level of uncertainty over what nanomaterials and nanotechnologies present as potential work-related health risks, what about these materials might lead to adverse toxicological activity, how risk related to these might be assessed, and how to manage these issues in the absence of this information. This study introduces a pilot CB tool or 'CB Nanotool' that was developed specifically for characterizing the health aspects of working with engineered nanoparticles and determining the level of risk and associated controls for five ongoing nanotechnology-related operations being conducted at two Department of Energy (DOE) research laboratories. Based on the application of the CB Nanotool, four of the five operations evaluated in this study were found to have implemented controls consistent with what was recommended by the CB Nanotool, with one operation even exceeding the required controls for that activity. The one remaining operation was determined to require an upgrade in controls. By developing this dynamic CB Nanotool within the realm of the scientific information …
Date: March 3, 2008
Creator: Paik, S Y; Zalk, D M & Swuste, P
Object Type: Article
System: The UNT Digital Library
Cfd Modeling Analysis of Mechanical Draft Cooling Tower (open access)

Cfd Modeling Analysis of Mechanical Draft Cooling Tower

Industrial processes use mechanical draft cooling towers (MDCT's) to dissipate waste heat by transferring heat from water to air via evaporative cooling, which causes air humidification. The Savannah River Site (SRS) has a MDCT consisting of four independent compartments called cells. Each cell has its own fan to help maximize heat transfer between ambient air and circulated water. The primary objective of the work is to conduct a parametric study for cooling tower performance under different fan speeds and ambient air conditions. The Savannah River National Laboratory (SRNL) developed a computational fluid dynamics (CFD) model to achieve the objective. The model uses three-dimensional steady-state momentum, continuity equations, air-vapor species balance equation, and two-equation turbulence as the basic governing equations. It was assumed that vapor phase is always transported by the continuous air phase with no slip velocity. In this case, water droplet component was considered as discrete phase for the interfacial heat and mass transfer via Lagrangian approach. Thus, the air-vapor mixture model with discrete water droplet phase is used for the analysis. A series of the modeling calculations was performed to investigate the impact of ambient and operating conditions on the thermal performance of the cooling tower when fans …
Date: March 3, 2008
Creator: Lee, S.; Alfred Garrett, A.; James02 Bollinger, J. & Larry Koffman, L.
Object Type: Article
System: The UNT Digital Library
Development and Testing of a Life Cycle Model and a Parameterization of Thin Mid-level Stratiform Clouds (open access)

Development and Testing of a Life Cycle Model and a Parameterization of Thin Mid-level Stratiform Clouds

We used a cloud-resolving model (a detailed computer model of cloud systems) to evaluate and improve the representation of clouds in global atmospheric models used for numerical weather prediction and climate modeling. We also used observations of the atmospheric state, including clouds, made at DOE's Atmospheric Radiation Measurement (ARM) Program's Climate Research Facility located in the Southern Great Plains (Kansas and Oklahoma) during Intensive Observation Periods to evaluate our detailed computer model as well as a single-column version of a global atmospheric model used for numerical weather prediction (the Global Forecast System of the NOAA National Centers for Environmental Prediction). This so-called Single-Column Modeling approach has proved to be a very effective method for testing the representation of clouds in global atmospheric models. The method relies on detailed observations of the atmospheric state, including clouds, in an atmospheric column comparable in size to a grid column used in a global atmospheric model. The required observations are made by a combination of in situ and remote sensing instruments. One of the greatest problems facing mankind at the present is climate change. Part of the problem is our limited ability to predict the regional patterns of climate change. In order to increase …
Date: March 3, 2008
Creator: Krueger, Steven K.
Object Type: Report
System: The UNT Digital Library
Spatial Variability of Reactive Mineral and Radionuclide Kd Distributions in the Tuff Confining Unit: Yucca Flat, Nevada Test Site (open access)

Spatial Variability of Reactive Mineral and Radionuclide Kd Distributions in the Tuff Confining Unit: Yucca Flat, Nevada Test Site

None
Date: March 3, 2008
Creator: Carle, S F; Zavarin, M & Pawloski, G A
Object Type: Report
System: The UNT Digital Library
PREDICTION OF SURFACE SETTLEMENT DUE TO THE DISPLACEMENT OF SOFT ZONES (open access)

PREDICTION OF SURFACE SETTLEMENT DUE TO THE DISPLACEMENT OF SOFT ZONES

In areas composed of coastal plain sediments, soft zones subjected to partial overburden may be present in the subsurface. During or after a seismic event, these soft zones may be compressed. The resulting displacement due to the deformation of the soft zones will propagate to the ground surface and cause the surface to settle. This paper presents a method to predict the settlement at the surface due to the propagation of the displacement from the soft zones. This method is performed by discretizing the soft zones into multiple clusters of finite sub-areas or subspaces. Settlement profile at the ground surface due to the displacement of each sub-area or subspace is computed assuming the shape is a normal distribution function. Settlement due to the displacement of the soft zones can then be approximated by adding the settlements computed for all the sub-areas or subspaces. This method provides a simple and useful tool for the prediction of the settlement profile and the results are consistent with those obtained from the finite difference analysis.
Date: March 3, 2008
Creator: Li, W
Object Type: Article
System: The UNT Digital Library
Remaining Sites Verification Package for the 100-F-26:13, 108-F Drain Pipelines, Waste Site Reclassification Form 2005-011 (open access)

Remaining Sites Verification Package for the 100-F-26:13, 108-F Drain Pipelines, Waste Site Reclassification Form 2005-011

The 100-F-26:13 waste site is the network of process sewer pipelines that received effluent from the 108-F Biological Laboratory and discharged it to the 188-F Ash Disposal Area (126-F-1 waste site). The pipelines included one 0.15-m (6-in.)-, two 0.2-m (8-in.)-, and one 0.31-m (12-in.)-diameter vitrified clay pipe segments encased in concrete. In accordance with this evaluation, the verification sampling results support a reclassification of this site to Interim Closed Out. The results of verification sampling demonstrated that residual contaminant concentrations do not preclude any future uses and allow for unrestricted use of shallow zone soils. The results also showed that residual contaminant concentrations are protective of groundwater and the Columbia River.
Date: March 3, 2008
Creator: Dittmer, L. M.
Object Type: Report
System: The UNT Digital Library
A Unified Monte Carlo Approach to Fast Neutron Cross Section Data Evaluation. (open access)

A Unified Monte Carlo Approach to Fast Neutron Cross Section Data Evaluation.

A unified Monte Carlo (UMC) approach to fast neutron cross section data evaluation that incorporates both model-calculated and experimental information is described. The method is based on applications of Bayes Theorem and the Principle of Maximum Entropy as well as on fundamental definitions from probability theory. This report describes the formalism, discusses various practical considerations, and examines a few numerical examples in some detail.
Date: March 3, 2008
Creator: Smith, D.
Object Type: Report
System: The UNT Digital Library
Estimating solar access of typical residential rooftops: A case study in San Jose, CA (open access)

Estimating solar access of typical residential rooftops: A case study in San Jose, CA

Shadows cast by trees and buildings can limit the solar access of rooftop solar-energy systems, including photovoltaic panels and thermal collectors. This study characterizes rooftop shading in a residential neighborhood of San Jose, CA, one of four regions analyzed in a wider study of the solar access of California homes.High-resolution orthophotos and LiDAR (Light Detection And Ranging) measurements of surface height were used to create a digital elevation model of all trees and buildings in a 4 km2 residential neighborhood. Hourly shading of roofing planes (the flat elements of roofs) was computed geometrically from the digital elevation model. Parcel boundaries were used to determine the extent to which roofing planes were shaded by trees and buildings in neighboring parcels.In the year in which surface heights were measured (2005), shadows from all sources ("total shading") reduced the insolation received by S-, SW-, and W-facing residential roofing planes in the study area by 13 - 16percent. Shadows cast by trees and buildings in neighboring parcels reduced insolation by no more than 2percent. After 30 years of simulated maximal tree growth, annual total shading increased to 19 - 22percent, and annual extraparcel shading increased to 3 - 4percent.
Date: March 3, 2008
Creator: Levinson, Ronnen M.; Gupta, Smita; Akbari, Hashem & Pomerantz, Melvin
Object Type: Article
System: The UNT Digital Library
Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers (open access)

Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers

The overall goal of the project was to bridge the gap between our knowledge of small-scale geochemical reaction rates and reaction rates meaningful for modeling transport at core scales. The working hypothesis was that reaction rates, determined from laboratory measurements based upon reactions typically conducted in well mixed batch reactors using pulverized reactive media may be significantly changed in in situ porous media flow due to rock microstructure heterogeneity. Specifically we hypothesized that, generally, reactive mineral surfaces are not uniformly accessible to reactive fluids due to the random deposition of mineral grains and to the variation in flow rates within a pore network. Expected bulk reaction rates would therefore have to be correctly up-scaled to reflect such heterogeneity. The specific objective was to develop a computational tool that integrates existing measurement capabilities with pore-scale network models of fluid flow and reactive transport. The existing measurement capabilities to be integrated consisted of (a) pore space morphology, (b) rock mineralogy, and (c) geochemical reaction rates. The objective was accomplished by: (1) characterizing sedimentary sandstone rock morphology using X-ray computed microtomography, (2) mapping rock mineralogy using back-scattered electron microscopy (BSE), X-ray dispersive spectroscopy (EDX) and CMT, (3) characterizing pore-accessible reactive mineral surface area, …
Date: March 3, 2009
Creator: Lindquist, W Brent
Object Type: Report
System: The UNT Digital Library
An Investigation of the Effect of Graphite Degradation on the Irreversible Capacity in Lithium-ion Cells (open access)

An Investigation of the Effect of Graphite Degradation on the Irreversible Capacity in Lithium-ion Cells

The effect of surface structural damage on graphitic anodes, commonly observed in tested Li-ion cells, was investigated. Similar surface structural disorder was artificially induced in Mag-10 synthetic graphite anodes using argon-ion sputtering. Raman microscopy, scanning electron microscopy (SEM) and Brunauer Emmett Teller (BET) measurements confirmed that Ar-ion sputtered Mag-10 electrodes display similar degree of surface degradation as the anodes from tested Li-ion cells. Artificially modified Mag-10 anodes showed double the irreversible charge capacity during the first formation cycle, compared to fresh un-altered anodes. Impedance spectroscopy and Fourier transform infrared (FTIR) spectroscopy on surface modified graphite anodes indicated the formation of a thicker and slightly more resistive SEI layer. Gas chromatography/mass spectroscopy (GC/MS) analysis of solvent extracts from the electrodes detected the presence of new compounds with M{sub w} on the order of 1600 g mol{sup -1} for the surface modified electrode with no evidence of elevated M{sub w} species for the unmodified electrode. The structural disorder induced in the graphite during long-term cycling maybe responsible for the slow and continuous SEI layer reformation, and consequently, the loss of reversible capacity due to the shift of lithium inventory in cycled Li-ion cells.
Date: March 3, 2008
Creator: Stevenson, Cynthia; Hardwick, Laurence J.; Marcinek, Marek; Beer, Leanne; Kerr, John B. & Kostecki, Robert
Object Type: Article
System: The UNT Digital Library
DOE Award No. DE-FC36-03GO13108 Novel Non-Precious Metal Catalysts for PEMFC: Catalyst Selection Through Molecular Modeling and Durability Studies Final Report (September 2003 – October 2008) (open access)

DOE Award No. DE-FC36-03GO13108 Novel Non-Precious Metal Catalysts for PEMFC: Catalyst Selection Through Molecular Modeling and Durability Studies Final Report (September 2003 – October 2008)

The objective of this project is to develop novel non-precious metal electrocatalysts for oxygen reduction reaction (ORR), and demonstrate the potential of the catalysts to perform at least as good as conventional Pt catalysts currently in use in polymer electrolyte membrane fuel cell (PEMFC) with a cost at least 50 % less than a target of 0.2 g (Pt loading)/peak kW and with durability > 2,000 h operation with less than 10 % power degradation. A novel nitrogen-modified carbon-based catalyst was obtained by modifying carbon black with nitrogen-containing organic precursor in the absence of transition metal precursor. The catalyst shows the onset potential of approximately 0.76 V (NHE) for ORR and the amount of H2O2 of approximately 3% at 0.5 V (NHE). Furthermore, a carbon composite catalyst was achieved through the high-temperature pyrolysis of the precursors of transition metal (Co and Fe) and nitrogen supported on the nitrogen-modified carbon-based catalyst, followed by chemical post-treatment. This catalyst showed an onset potential for ORR as high as 0.87 V (NHE), and generated less than 1 % of H2O2. The PEM fuel cell exhibited a current density of 2.3 A cm-2 at 0.2 V for a catalyst loading of 6.0 mg cm-2. No …
Date: March 3, 2009
Creator: Popov, Branko N.
Object Type: Report
System: The UNT Digital Library
Status report : guard containment CFD analysis. (open access)

Status report : guard containment CFD analysis.

Under the auspices of the CEA Cadarache/ANL-US I-NERI project a comprehensive investigation has been made of improvements to the Gen-IV GFR safety case over that of the GCFR safety case twenty five years ago. In particular, it has been concluded and agreed upon [1] that the GFR safety approach for the passive removal of decay heat in a protected depressurization accident with total loss of electric power needs to be different from that taken for the HTRs. The HTR conduction cooldown to the vessel wall boundary mode for an economically attractive core is not feasible in the case of the GFR because the high power densities (100kW/1 compared to 5 kW/1 for pebble bed thermal reactor) require decay heat fluxes well beyond those achievable by the heat conduction and radiation heat transfer mode. A set of alternative novel design options has been evaluated for potential passive safety mechanisms unique to the GFR. In summary, from a technological risk viewpoint and R&D planning, the option which has been identified is the block/plate-based or a pin-based reactor with a secondary guard containment/vessel around the primary vessel to maintain the primary system pressure at a high enough level which would allow primary system …
Date: March 3, 2006
Creator: Tzanos, C. P.
Object Type: Report
System: The UNT Digital Library
Unraveling duality violations in hadronic tau decays (open access)

Unraveling duality violations in hadronic tau decays

There are some indications from recent determinations of the strong coupling constant alpha_s and the gluon condensate that the Operator Product Expansion may not be accurate enough to describe non-perturbative effects in hadronic tau decays. This breakdown of the Operator Product Expansion is usually referred to as being due to"Duality Violations." With the help of a physically motivated model, we investigate these duality violations. Based on this model, we argue how they may introduce a non-negligible systematic error in the current analysis, which employs finite-energy sum rules with pinched weights. In particular, this systematic effect might affect the precision determination of alpha_s from tau decays. With a view to a possible future application to real data, we present an alternative method for determining the OPE coefficients that might help estimating, and possibly even reducing, this systematic error.
Date: March 3, 2008
Creator: Cata, Oscar; Cata, Oscar; Golterman, Maarten & Peris, Santiago
Object Type: Article
System: The UNT Digital Library
The Design, Construction, and Operation of Long-Distance High-Voltage Electricity Transmission Technologies. (open access)

The Design, Construction, and Operation of Long-Distance High-Voltage Electricity Transmission Technologies.

This report focuses on transmission lines, which operate at voltages of 115 kV and higher. Currently, the highest voltage lines comprising the North American power grid are at 765 kV. The grid is the network of transmission lines that interconnect most large power plants on the North American continent. One transmission line at this high voltage was built near Chicago as part of the interconnection for three large nuclear power plants southwest of the city. Lines at this voltage also serve markets in New York and New England, also very high demand regions. The large power transfers along the West Coast are generally at 230 or 500 kV. Just as there are practical limits to centralization of power production, there are practical limits to increasing line voltage. As voltage increases, the height of the supporting towers, the size of the insulators, the distance between conductors on a tower, and even the width of the right-of-way (ROW) required increase. These design features safely isolate the electric power, which has an increasing tendency to arc to ground as the voltage (or electrical potential) increases. In addition, very high voltages (345 kV and above) are subject to corona losses. These losses are a …
Date: March 3, 2008
Creator: Molburg, J. C.; Kavicky, J. A. & Picel, K. C.
Object Type: Report
System: The UNT Digital Library
The Biocatalytic Desulfurization Project (open access)

The Biocatalytic Desulfurization Project

The material in this report summarizes the Diversa technical effort in development of a biocatalyst for the biodesulfurization of Petro Star diesel as well as an economic report of standalone and combined desulfurization options, prepared by Pelorus and Anvil, to support and inform the development of a commercially viable process. We will discuss goals of the projected as originally stated and their modification as guided by parallel efforts to evaluate commercialization economics and process parameters. We describe efforts to identify novel genes and hosts for the generation of an optimal biocatalyst, analysis of diesel fuels (untreated, chemically oxidized and hydrotreated) for organosulfur compound composition and directed evolution of enzymes central to the biodesulfurization pathway to optimize properties important for their use in a biocatalyst. Finally we will summarize the challenges and issues that are central to successful development of a viable biodesulfurization process.
Date: March 3, 2006
Creator: Nunn, David; Boltz, James; DiGrazia, Philip M. & Nace, Larry
Object Type: Report
System: The UNT Digital Library
A Multi-Layered Ceramic Composite for Impermeable Fuel Cladding for COmmercial Wate Reactors (open access)

A Multi-Layered Ceramic Composite for Impermeable Fuel Cladding for COmmercial Wate Reactors

A triplex nuclear fuel cladding is developed to further improve the passive safety of commercial nuclear plants, to increase the burnup and durablity of nuclear fuel, to improve the power density and economics of nuclear power, and to reduce the amount of spent fuel requiring disposal or recycle.
Date: March 3, 2008
Creator: Feinroth, Herbert
Object Type: Report
System: The UNT Digital Library
Impacts of China's Current Appliance Standards and LabelingProgram to 2020 (open access)

Impacts of China's Current Appliance Standards and LabelingProgram to 2020

The report summarizes the history and nature of China sstandardsand labeling program in the Introduction in Section 1. Trends indomestic production, exports, penetration rates, unit energy consumptionand the history of S&L technical levels by product are discussed ingreat detail in Section 2. The national energy impactsanalysis found inSection 3 concludes that overall China s standards and labeling programsreduce total electricity consumption in 2020 by an annual 106 TWh, or 16percent of what would otherwise been expected in that year in the absenceof standards and labeling programs.In total, the report concludes thatthe S&L programs currently in place in China are expected to save acumulative 1143 TWh by 2020, or 9 percent of the cumulative consumptionof residential electricity to that year. In 2020 alone, annual savingsare expected to be equivalent to 11 percent of residential electricityuse. In average generation terms, this is equivalent to 27 1-GW coalfired plants that would have required around 75 million tonnes of coal tooperate.In comparison, savings from the US appliance standards programalone is expected to save 10 percent of residential electricityconsumption in 2020.
Date: March 3, 2007
Creator: Fridley, David; Aden, Nathaniel; Zhou, Nan & Lin, Jiang
Object Type: Report
System: The UNT Digital Library
SQA(TM): Surface Quality Assured Steel Bar Program (open access)

SQA(TM): Surface Quality Assured Steel Bar Program

OG Technologies, Inc. (OGT) has led this SQA (Surface Quality Assured Steel Bar) program to solve the major surface quality problems plaguing the US special quality steel bars and rods industry and their customers, based on crosscutting sensors and controls technologies. Surface defects in steel formed in a hot rolling process are one of the most common quality issues faced by the American steel industry, accounting for roughly 50% of the rejects or 2.5% of the total shipment. Unlike other problems such as the mechanical properties of the steel product, most surface defects are sporadic and cannot be addressed based on sampling techniques. This issue hurts the rolling industry and their customers in their process efficiency and operational costs. The goal of this program is to develop and demonstrate an SQA prototype, with synergy of HotEye® and other innovations, that enables effective rolling process control and efficient quality control. HotEye®, OGT’s invention, delivers high definition images of workpieces at or exceeding 1,450C while the workpieces travel at 100 m/s. The elimination of surface defect rejects will be achieved through the integration of imaging-based quality assessment, advanced signal processing, predictive process controls and the integration with other quality control tools. The …
Date: March 3, 2009
Creator: Chang, Tzyy-Shuh; Shi, Jianjun & Zhou, Shiyu
Object Type: Report
System: The UNT Digital Library
Development and Integration of Single-Asperity Nanotribology Experiments & Nanoscale Interface Finite Element Modeling for Prediction and Control of Friction and Damage in Micro- and Nano-mechnical Systems (open access)

Development and Integration of Single-Asperity Nanotribology Experiments & Nanoscale Interface Finite Element Modeling for Prediction and Control of Friction and Damage in Micro- and Nano-mechnical Systems

This report describes the accomplishments of the DOE BES grant entitled "Development and Integration of Single-Asperity Nanotribology Experiments & Nanoscale Interface Finite Element Modeling for Prediction and Control of Friction and Damage in Micro- and Nano-mechnical Systems". Key results are: the determination of nanoscale frictional properties of MEMS surfaces, self-assembled monolayers, and novel carbon-based films, as well as the development of models to describe this behavior.
Date: March 3, 2007
Creator: Carpick, R. W. & Plesha, M. E.
Object Type: Report
System: The UNT Digital Library
Revisiting the U-238 thermal capture cross section and gamma-raymission probabilities from Np-239 decay (open access)

Revisiting the U-238 thermal capture cross section and gamma-raymission probabilities from Np-239 decay

The precise value of the thermal capture cross section of238U is uncertain, and evaluated cross sections from various sourcesdiffer by more than their assigned uncertainties. A number of theoriginal publications have been reviewed to assess the discrepant data,corrections were made for more recent standard cross sections andotherconstants, and one new measurement was analyzed. Due to the strongcorrelations in activation measurements, the gamma-ray emissionprobabilities from the beta decay of 239Np were also analyzed. As aresult of the analysis, a value of 2.683 +- 0.012 barns was derived forthe thermal capture cross section of 238U. A new evaluation of thegamma-ray emission probabilities from 239Np decay was alsoundertaken.
Date: March 3, 2005
Creator: Trkov, A.; Molnar, G. L.; Revay, Z. S.; Mughabghab, S. F.; Firestone, R. B.; Pronyaev, V. G. et al.
Object Type: Article
System: The UNT Digital Library
On the Long-Term Average Cost of CO2 Transport and Storage (open access)

On the Long-Term Average Cost of CO2 Transport and Storage

Paper describes general trends in the cost of CO2 transport and storage (including measurement, monitoring, and verification) and how these can be used to justify a proxy cost to cover a large number of potential CCS commercial deployment scenarios.
Date: March 3, 2008
Creator: Dooley, James J.; Dahowski, Robert T. & Davidson, Casie L.
Object Type: Report
System: The UNT Digital Library
Pulse Jet Mixer Overblow Testing for Assessment of Loadings During Multiple Overblows (open access)

Pulse Jet Mixer Overblow Testing for Assessment of Loadings During Multiple Overblows

The U.S. Department of Energy (DOE) Office of River Protection’s Waste Treatment Plant (WTP) is being designed and built to pretreat and then vitrify a large portion of the wastes in Hanford’s 177 underground waste storage tanks. The WTP consists of three primary facilities: pretreatment, low-activity waste (LAW) vitrification, and high-level waste (HLW) vitrification. The pretreatment facility will receive waste feed from the Hanford tank farms and separate it into 1) a high-volume, low-activity liquid stream stripped of most solids and radionuclides and 2) a much smaller volume of HLW slurry containing most of the solids and most of the radioactivity. Many of the vessels in the pretreatment facility will contain pulse jet mixers (PJMs) that will provide some or all of the mixing in the vessels. This technology was selected for use in so-called “black cell” regions of the WTP, where maintenance capability will not be available for the operating life of the WTP. PJM technology was selected for use in these regions because it has no moving mechanical parts that require maintenance. The vessels with the most concentrated slurries will also be mixed with air spargers and/or steady jets in addition to the mixing provided by the PJMs. …
Date: March 3, 2008
Creator: Pfund, David M.; Bontha, Jagannadha R.; Michener, Thomas E.; Nigl, Franz; Yokuda, Satoru T.; Leigh, Richard J. et al.
Object Type: Report
System: The UNT Digital Library
The effect of problem perturbations on nonlinear dynamical systems and their reduced order models (open access)

The effect of problem perturbations on nonlinear dynamical systems and their reduced order models

Reduced order models are used extensively in many areas of science and engineering for simulation, design, and control. Reduction techniques for nonlinear dynamical systems produce models that depend strongly on the nominal set of parameters for which the reduction is carried out. In this paper we address the following two questions: 'What is the effect of perturbations in the problem parameters on the output functional of a nonlinear dynamical system?' and 'To what extent does the reduced order model capture this effect?'
Date: March 3, 2005
Creator: Serban, R; Homescu, C & Petzold, L
Object Type: Article
System: The UNT Digital Library