Analysis of Rayleigh-Taylor Instability: Statistics on Rising Bubbles and Falling Spikes (open access)

Analysis of Rayleigh-Taylor Instability: Statistics on Rising Bubbles and Falling Spikes

The analysis of coherent structures in Rayleigh-Taylor simulations is a challenging task as the lack of a precise definition of these structures is compounded by the massive size of the datasets. In an earlier work, we used techniques from image analysis to count these coherent structures in two high-resolution simulations, one a large-eddy simulation with 30 terabytes of analysis data, and the other a direct numerical simulation with 80 terabytes of analysis data. Our analysis indicated that there were four distinct regimes in the process of the mixing of the two fluids, starting from the initial linear stage, followed by the non-linear stage with weak turbulence, the mixing transition stage, and the final stage of strong turbulence. In this paper, we extend our earlier work to focus on only the rising bubbles and the falling spikes. We first consider different ways in which we can constrain the bubble and spike definitions and then extract various statistics on them. Our results on the rising bubble and falling spike counts again show that there are four regimes in the process of fluid mixing, each characterized by an integer-valued slope. Further, the average bubble heights and spike depths are related to similar results …
Date: October 30, 2007
Creator: Kamath, C; Gezahegne, A & Miller, P
System: The UNT Digital Library
Summary of Research through Phase II/Year 2 of Initially Approved 3 Phase/3 Year Project - Establishing the Relationship between Fracture-Related Dolomite and Primary Rock Fabric on the Distribution of Reservoirs in the Michigan Basin (open access)

Summary of Research through Phase II/Year 2 of Initially Approved 3 Phase/3 Year Project - Establishing the Relationship between Fracture-Related Dolomite and Primary Rock Fabric on the Distribution of Reservoirs in the Michigan Basin

This final scientific/technical report covers the first 2 years (Phases I and II of an originally planned 3 Year/3 Phase program). The project was focused on evaluating the relationship between fracture-related dolomite and dolomite constrained by primary rock fabric in the 3 most prolific reservoir intervals in the Michigan Basin. The characterization of select dolomite reservoirs was the major focus of our efforts in Phases I and II of the project. Structural mapping and log analysis in the Dundee (Devonian) and Trenton/Black River (Ordovician) suggest a close spatial relationship among gross dolomite distribution and regional-scale, wrench fault-related NW-SE and NE-SW structural trends. A high temperature origin for much of the dolomite in these 2 studied intervals (based upon fluid inclusion homogenization temperatures and stable isotopic analyses,) coupled with persistent association of this dolomite in reservoirs coincident with wrench fault-related features, is strong evidence for these reservoirs being influenced by hydrothermal dolomitization. In the Niagaran (Silurian), there is a general trend of increasing dolomitization shelfward, with limestone predominant in more basinward positions. A major finding is that facies types, when analyzed at a detailed level, are directly related to reservoir porosity and permeability in these dolomites which increases the predictability of …
Date: September 30, 2007
Creator: Grammer, G.
System: The UNT Digital Library
The Davis-Bacon Act: Institutional Evolution and Public Policy (open access)

The Davis-Bacon Act: Institutional Evolution and Public Policy

This report examines policy issues the Davis-Bacon Act has sparked through the years and which remain a part of the Davis-Bacon debate of the 1990s. These include such questions as: wage rate determination procedures, reporting requirements under the Copeland Act, an appropriate threshold for activation of the statute, interagency relationships with respect to Davis-Bacon enforcement and compliance activity, administrative or judicial appeals procedures, the use of "helpers" and other low-skilled workers on covered projects, and the right of a President to suspend the statute as well as the conditions under which such a suspension may occur. That the fundamental premise of the Act remains in contention after 60 years may be, itself, part of the public policy debate.
Date: November 30, 2007
Creator: Whittaker, William G.
System: The UNT Digital Library
TECHNICAL EVALUATION OF THE SAFE TRANSPORTATION OF WASTE CONTAINERS COATED WITH POLYUREA (open access)

TECHNICAL EVALUATION OF THE SAFE TRANSPORTATION OF WASTE CONTAINERS COATED WITH POLYUREA

This technical report is to evaluate and establish that the transportation of waste containers (e.g. drums, wooden boxes, fiberglass-reinforced plywood (FRP) or metal boxes, tanks, casks, or other containers) that have an external application of polyurea coating between facilities on the Hanford Site can be achieved with a level of onsite safety equivalent to that achieved offsite. Utilizing the parameters, requirements, limitations, and controls described in the DOE/RL-2001-36, ''Hanford Sitewide Transportation Safety Document'' (TSD) and the Department of Energy Richland Operations (DOE-RL) approved package specific authorizations (e.g. Package Specific Safety Documents (PSSDs), One-Time Requests for Shipment (OTRSs), and Special Packaging Authorizations (SPAS)), this evaluation concludes that polyurea coatings on packages does not impose an undue hazard for normal and accident conditions. The transportation of all packages on the Hanford Site must comply with the transportation safety basis documents for that packaging system. Compliance with the requirements, limitations, or controls described in the safety basis for a package system will not be relaxed or modified because of the application of polyurea. The inspection criteria described in facility/projects procedures and work packages that ensure compliance with Container Management Programs and transportation safety basis documentation dictate the need to overpack a package without …
Date: March 30, 2007
Creator: VAIL, T.S.
System: The UNT Digital Library
Defense Acquisitions: Assessments of Selected Weapon Programs (open access)

Defense Acquisitions: Assessments of Selected Weapon Programs

A letter report issued by the Government Accountability Office with an abstract that begins "This report is GAO's fifth annual assessment of selected weapon programs. From 2001 to the present, the Department of Defense (DOD) has doubled its planned investment in new systems from approximately $750 billion to almost $1.5 trillion. While DOD expects these systems to transform military operations, their acquisition remains a high-risk area. GAO's reviews of weapons over three decades have found consistent cost increases, schedule delays, and performance shortfalls. The nation's growing long-range fiscal challenges may ultimately spur Congress to pressure DOD to cut spending on new weapons and to redirect funding to other priorities. In response, DOD might be compelled to deliver new weapon programs within estimated costs and to obtain the most from its investments. This report provides congressional and DOD decision makers with an independent, knowledge-based assessment of selected defense programs, identifying potential risks and needed actions when a program's projected attainment of knowledge diverges from the best practices. Programs assessed were selected using several factors: high dollar value, acquisition stage, and congressional interest. This report also highlights issues raised by the cumulative experiences of individual programs. GAO updates this report annually under …
Date: March 30, 2007
Creator: United States. Government Accountability Office.
System: The UNT Digital Library
Final Report - Advanced MEA's for Enhanced Operating Conditions, Amenable to High Volume Manufacture (open access)

Final Report - Advanced MEA's for Enhanced Operating Conditions, Amenable to High Volume Manufacture

This report summarizes the work completed under a 3M/DOE contract directed at advancing the key fuel cell (FC) components most critical for overcoming the polymer electrolyte membrane fuel cell (PEMFC) performance, durability & cost barriers. This contract focused on the development of advanced ion exchange membranes & electrocatalysts for PEMFCs that will enable operation under ever more demanding automotive operating conditions & the use high volume compatible processes for their manufacture. Higher performing & more durable electrocatalysts must be developed for PEMFCs to meet the power density & lifetime hours required for FC vehicles. At the same time the amount of expensive Pt catalyst must be reduced to lower the MEA costs. While these two properties are met, the catalyst must be made resistant to multiple degradation mechanisms to reach necessary operating lifetimes. In this report, we present the work focused on the development of a completely new approach to PEMFC electrocatalyts, called nanostructured thin film (NSTF) catalysts. The carbon black supports are eliminated with this new approach which eliminates the carbon corrosion issue. The thin film nature of the catalyst significantly improves its robustness against dissolution & grain growth, preserving the surface area. Also, the activity of the NSTF …
Date: September 30, 2007
Creator: Debe, Mark K.
System: The UNT Digital Library