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U.S. Public Diplomacy: State Department Expands Efforts but Faces Significant Challenges (open access)

U.S. Public Diplomacy: State Department Expands Efforts but Faces Significant Challenges

A letter report issued by the General Accounting Office with an abstract that begins "The terrorist attacks of September 11, 2001, focused attention on the need to improve public diplomacy efforts to cultivate a better public opinion of the United States abroad. However, recent opinion research indicates that many foreign publics, especially in countries with significant Muslim populations, view the United States unfavorably. GAO examined changes in the State Department's (State) public diplomacy efforts since September 11, whether State has an overall strategy for its public diplomacy programs, how it measures their effectiveness, and challenges it faces in implementing these programs."
Date: September 4, 2003
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Defense Health Care: Oversight of Military Services' Post-Deployment Health Reassessment Completion Rates Is Limited (open access)

Defense Health Care: Oversight of Military Services' Post-Deployment Health Reassessment Completion Rates Is Limited

Correspondence issued by the Government Accountability Office with an abstract that begins "Military servicemembers engaged in combat tours in Afghanistan and Iraq are at risk of developing combat-related mental health conditions, including post-traumatic stress disorder (PTSD). In many cases, signs of potential mental health conditions do not surface until months after servicemembers return from deployment. In 2004, Army researchers published a series of articles that indicated a significant increase in the number of servicemembers reporting mental health concerns 90 to 120 days after returning from deployment, compared with mental health concerns reported before or soon after deployment. These findings led the Department of Defense (DOD) in March 2005 to develop requirements and policies for the post-deployment health reassessment (PDHRA) as part of its continuum of deployment health assessments for servicemembers. PDHRA is a screening tool for military servicemembers; it is designed to identify and address their health concerns--including mental health concerns--90 to 180 days after return from deployment. Servicemembers answer a set of questions about their physical and mental health conditions and concerns, and health care providers review the answers and refer servicemembers for further evaluation and treatment if necessary. A November 2007 study showed that a larger number of …
Date: September 4, 2008
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library
Retirement Savings: Better Information and Sponsor Guidance Could Improve Oversight and Reduce Fees for Participants (open access)

Retirement Savings: Better Information and Sponsor Guidance Could Improve Oversight and Reduce Fees for Participants

A letter report issued by the Government Accountability Office with an abstract that begins "American workers increasingly rely on defined contribution (DC) plans like 401(k) plans and individual retirement accounts (IRA) for retirement income. Together with other DC plans--401(a), 403(b), and 457 plans--these accounts hold about $7.1 trillion. As workers accrue earnings on their investments, they also pay a number of fees that may significantly decrease retirement savings over the course of a career. GAO examined: (1) the types of fees charged to participants and investments of various DC plans; (2) how DC plan sponsor actions affect participant fees; (3) how fee disclosure requirements vary; and (4) the effectiveness of DC plan oversight. GAO reviewed laws and regulations and consulted with experts, federal officials, service providers, and six plan sponsors."
Date: September 4, 2009
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Securing, Stabilizing, and Rebuilding Iraq: Iraqi Government Has Not Met Most Legislative, Security, and Economic Benchmarks (open access)

Securing, Stabilizing, and Rebuilding Iraq: Iraqi Government Has Not Met Most Legislative, Security, and Economic Benchmarks

A letter report issued by the Government Accountability Office with an abstract that begins "Public Law 110-28 requires GAO to report to Congress by September 1, 2007, on whether or not the government of Iraq has met 18 benchmarks contained in the Act, and the status of the achievement of these benchmarks. The benchmarks stem from commitments first articulated by the Iraqi government in June 2006. In comparison, the Act requires the administration to report in July and September 2007 on whether satisfactory progress is being made toward meeting the benchmarks, not whether the benchmarks have been met. To complete our work, we reviewed government documents and interviewed officials from U.S. agencies; the UN; and the government of Iraq. We also made multiple visits to Iraq during 2006 and 2007. Our analyses were enhanced by approximately 100 Iraq-related audits we have completed since May 2003."
Date: September 4, 2007
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Concentrated Animal Feeding Operations: EPA Needs More Information and a Clearly Defined Strategy to Protect Air and Water Quality from Pollutants of Concern (open access)

Concentrated Animal Feeding Operations: EPA Needs More Information and a Clearly Defined Strategy to Protect Air and Water Quality from Pollutants of Concern

A letter report issued by the Government Accountability Office with an abstract that begins "Concentrated Animal Feeding Operations (CAFO) are large livestock and poultry operations that raise animals in a confined situation. CAFOs can improve the efficiency of animal production but large amounts of manure produce can, if not properly managed, degrade air and water quality. The Environmental Protection Agency (EPA) is responsible for regulating CAFOs and requires CAFOs that discharge certain pollutants to obtain a permit. This report discusses the (1) trends in CAFOs over the past 30 years, (2) amounts of waste they generate, (3) findings of key research on CAFOs' health and environmental impacts, (4) EPA's progress in developing CAFO air emissions protocols, and (5) effect of recent court decisions on EPA's regulation of CAFO water pollutants. GAO analyzed U.S. Department of Agriculture's (USDA) data from 1982 through 2002, for large farms as a proxy for CAFOs; reviewed studies, EPA documents, laws, and regulations; and obtained the views of federal and state officials."
Date: September 4, 2008
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
U.S. Patent And Trademark Office: Hiring Efforts Are Not Sufficient to Reduce the Patent Application Backlog (open access)

U.S. Patent And Trademark Office: Hiring Efforts Are Not Sufficient to Reduce the Patent Application Backlog

A letter report issued by the Government Accountability Office with an abstract that begins "Increases in the volume and complexity of patent applications have lengthened the amount of time it takes the U.S. Patent and Trademark Office (USPTO) to process them. In addition, concerns have continued about USPTO's efforts to hire and retain an adequate patent examination workforce that can not only meet the demand for patents but also help reduce the growing backlog of unexamined patent applications. In this context, GAO was asked to determine for the last 5 years (1) USPTO's process for identifying its annual hiring estimates and the relationship of these estimates to the patent application backlog; (2) the extent to which patent examiner hiring has been offset by attrition, and the factors that may contribute to this attrition; and (3) the extent to which USPTO's retention efforts align with patent examiners' reasons for staying with the agency. For this review, GAO surveyed 1,420 patent examiners, and received an 80 percent response rate."
Date: September 4, 2007
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Workforce Investment Act: One-Stop System Infrastructure Continues to Evolve, but Labor Should Take Action to Require That All Employment Service Offices Are Part of the System (open access)

Workforce Investment Act: One-Stop System Infrastructure Continues to Evolve, but Labor Should Take Action to Require That All Employment Service Offices Are Part of the System

A letter report issued by the Government Accountability Office with an abstract that begins "In 1998, Congress passed the Workforce Investment Act (WIA), requiring states and localities to bring together employment and training programs into a single workforce system, the one-stop system. States have flexibility in how they provide these services--colocated within the one-stop--through electronic linkage or referral. WIA did not provide funds to pay for the infrastructure costs, but programs must share the costs of operating one-stop centers. As Congress considers reauthorization of WIA, GAO assessed (1) the current composition of states' one-stop systems and how this has changed, (2) what funds are primarily used to support states' one-stop system infrastructure and how this has changed, and (3) the extent to which states are monitoring customer satisfaction. Our work was primarily based on a 50-state survey of state workforce officials, updating work we previously did in 2000 and 2001."
Date: September 4, 2007
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Various Issues Led to the Termination of the United States-Canada Shared Border Management Pilot Project (open access)

Various Issues Led to the Termination of the United States-Canada Shared Border Management Pilot Project

Correspondence issued by the Government Accountability Office with an abstract that begins "In the years since the 2001 terrorist attacks, balancing the need to secure U.S. borders while maintaining the flow of legitimate cross-border travel and commerce has taken on an added importance. The United States and Canada share a border that extends nearly 4,000 miles, and one of the world's largest trading relationships. Each year, approximately 70 million travelers and 35 million vehicles cross the border from Canada into the United States, according to the Department of Homeland Security (DHS). Given the volume of cross-border travel and trade between the United States and Canada, border congestion and the resulting wait times have a substantial economic impact on both nations. Furthermore, according to an analysis by DHS, the heightened emphasis on border security following the 2001 terrorist attacks has lengthened processing time for travelers and cargo crossing into the United States. Recognizing the need to improve both border security and border-crossing efficiency, the United States and Canada have cooperated on various cross-border management initiatives intended to increase the flow of legitimate travel across the border while maintaining security. For example, to facilitate the travel of low-risk prescreened individuals across the …
Date: September 4, 2008
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library
Elections: Voting Assistance to Military and Overseas Citizens Should Be Improved (open access)

Elections: Voting Assistance to Military and Overseas Citizens Should Be Improved

A chapter report issued by the General Accounting Office with an abstract that begins "The narrow margin of victory in the 2000 presidential election aroused concern about the reliability of voting machines; the training of polling place workers; and the extent to which local jurisdictions accepted ballots from members of the military, their dependents, or citizens living abroad. The Federal Voting Assistance program developed several useful tools for voters and Voting Assistance Officers, but many potential voters GAO spoke to were unaware of them. Some installations did not meet the Department of Defense (DOD) and service requirements because they provided insufficient numbers of trained Voting Assistance Officers, voter training, and voting materials. Overseas citizens and federal employees said that the State Department provided useful information. However, many military and overseas voters believe that challenges remain, such as understanding and complying with state requirements and local procedures for absentee voting. Security and privacy issues also present challenges to widespread use of the Internet for voting. Information on the precise number of military and overseas absentee votes that local jurisdictions disqualified nationwide in the 2000 general election and the reasons for disqualification are not readily available. However, GAO's national telephone survey found …
Date: September 4, 2001
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Foreign Affairs: Effective Stewardship of Resources Essential to Efficient Operations at State Department, USAID (open access)

Foreign Affairs: Effective Stewardship of Resources Essential to Efficient Operations at State Department, USAID

Testimony issued by the General Accounting Office with an abstract that begins "In recent years, funding for the Department of State has increased dramatically, particularly for security upgrades at overseas facilities and a major hiring program. The U.S. Agency for International Development (USAID) has also received more funds, especially for programs in Afghanistan and Iraq and HIV/AIDS relief. Both State and USAID face significant management challenges in carrying out their respective missions, particularly in areas such as human capital management, performance measurement, and information technology management. Despite increased funding, resources are not unlimited. Thus, State, USAID, and all government agencies have an obligation to ensure that taxpayer resources are managed wisely. Long-lasting improvements in performance will require continual vigilance and the identification of widespread opportunities to improve the economy, efficiency, and effectiveness of State's and USAID's existing goals and programs. GAO was asked to summarize its findings from reports on State's and USAID's management of resources, actions taken in response to our reports, and recommendations to promote cost savings and more efficient and effective operations at the department and agency."
Date: September 4, 2003
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Nuclear Regulatory Commission: Oversight of Security at Commercial Nuclear Power Plants Needs to Be Strengthened (open access)

Nuclear Regulatory Commission: Oversight of Security at Commercial Nuclear Power Plants Needs to Be Strengthened

A letter report issued by the General Accounting Office with an abstract that begins "The September 11, 2001, terrorist attacks intensified the nation's focus on national preparedness and homeland security. Among possible terrorist targets are the nation's nuclear power plants--104 facilities containing radioactive fuel and waste. The Nuclear Regulatory Commission (NRC) oversees plant security through an inspection program designed to verify the plants' compliance with security requirements. As part of that program, NRC conducted annual security inspections of plants and force-on-force exercises to test plant security against a simulated terrorist attack. GAO was asked to review (1) the effectiveness of NRC's security inspection program and (2) legal challenges affecting power plant security. Currently, NRC is reevaluating its inspection program. We did not assess the adequacy of security at the individual plants; rather, our focus was on NRC's oversight and regulation of plant security."
Date: September 4, 2003
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Pension Benefit Guaranty Corporation: Single-Employer Pension Insurance Program Faces Significant Long-Term Risks (open access)

Pension Benefit Guaranty Corporation: Single-Employer Pension Insurance Program Faces Significant Long-Term Risks

Testimony issued by the General Accounting Office with an abstract that begins "More than 34 million participants in 30,000 single-employer defined benefit pension plans rely on a federal insurance program managed by the Pension Benefit Guaranty Corporation (PBGC) to protect their pension benefits, and the program's long-term financial viability is in doubt. Over the last decade, the program swung from a $3.6 billion accumulated deficit (liabilities exceeded assets), to a $10.1 billion accumulated surplus, and back to a $3.6 billion accumulated deficit, in 2002 dollars. Furthermore, despite a record $9 billion in estimated losses to the program in 2002, additional severe losses may be on the horizon. PBGC estimates that financially weak companies sponsor plans with $35 billion in unfunded benefits, which ultimately might become losses to the program. This testimony provides GAO's observations on the factors that contributed to recent changes in the single-employer pension insurance program's financial condition, risks to the program's long-term financial viability, and options to address the challenges facing the single-employer program."
Date: September 4, 2003
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Small and Disadvantaged Businesses: Some Agencies' Advocates Do Not Report to the Required Management Level (open access)

Small and Disadvantaged Businesses: Some Agencies' Advocates Do Not Report to the Required Management Level

A letter report issued by the General Accounting Office with an abstract that begins "Section 15(k) of the Small Business Act requires that all federal agencies with procurement powers establish an Office of Small and Disadvantaged Business Utilization (OSDBU). This law is one of many designed to enhance the participation of small and disadvantaged businesses in federal procurement. Section 15(k)(3) of the act requires that OSDBU directors, who are intended to be advocates for small and disadvantaged businesses, be responsible only to and report directly to agency heads or deputy agency heads. GAO was asked to determine compliance with section 15(k)(3) across the government, review to whom the OSDBU director at the Office of the Secretary of Defense has reported since the office was exempted from that provision, and determine whether section 15(k) applies to the Office of Administration (OA), which is the central procurement arm of the Executive Office of the President (EOP)."
Date: September 4, 2003
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
District of Columbia: Fiscal Structural Balance Issues (open access)

District of Columbia: Fiscal Structural Balance Issues

A letter report issued by the General Accounting Office with an abstract that begins "The District of Columbia has historically faced many challenges due to its unique circumstances and role as the nation's capital. After several years of struggling with financial crises and insolvency in the early 1990s, the District has significantly improved its financial condition by achieving five consecutive balanced budgets, an upgraded bond rating, and unqualified or "clean" opinions on its financial statements. More recently, however, District officials have asserted that the District faces a fiscal structural imbalance as a result of several factors, some stemming from the federal government's presence in the city, the absence of a state to provide funding for the state-like services provided by the District, and restrictions on the District's tax base. The District argues that it faces a fiscal structural imbalance between revenues and its expenditures that undermines its capacity to meet its current responsibilities. In contrast with a cyclical fiscal imbalance caused by temporary economic downturns, the District suggests that its imbalance is longer term and more fundamental and, therefore, structural in nature. The District's estimated measures of fiscal structural imbalance are based on the continuation of current budget policy over …
Date: September 4, 2002
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Military Aircraft: Observations on the Proposed Lease of Aerial Refueling Aircraft by the Air Force (open access)

Military Aircraft: Observations on the Proposed Lease of Aerial Refueling Aircraft by the Air Force

Testimony issued by the General Accounting Office with an abstract that begins "At 543 aircraft, the KC-135 is the mainstay of U.S. aerial refueling capability. Recapitalizing this fleet is crucial to maintaining this capability and, ultimately, maintaining the mobility of U.S. forces. In the fiscal year 2002 defense appropriations act, the Congress authorized the Air Force to lease up to 100 aerial refueling aircraft after the Air Force reported its plans to the Senate and House Armed Services Committees and Defense Appropriations Subcommittees. The Air Force sent Congress on July 10 its report containing a business case analysis of its proposed lease. The Air Force plans to lease 100 KC-767A aircraft for 6 years each from a special purpose entity (SPE) that will order the aircraft from the Boeing Company. GAO was asked to (1) summarize the Air Force's report for leasing KC-767A aircraft, (2) present its observations on the report and justification for the lease, and (3) identify related issues and costs to assist the Congress as it considers the Air Force's proposal."
Date: September 4, 2003
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
GAO: Making a Difference for Congress and the Nation; Professional Development Program (open access)

GAO: Making a Difference for Congress and the Nation; Professional Development Program

Other written product issued by the General Accounting Office with an abstract that begins "This is an insert to GAO's publication, Serving the Congress and the Nation, describing the role, functions, and responsibilities of GAO's Professional Development Program team."
Date: September 4, 2001
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
World Trade Organization: Early Decisions Are Vital to Progress in Ongoing Negotiations (open access)

World Trade Organization: Early Decisions Are Vital to Progress in Ongoing Negotiations

A letter report issued by the General Accounting Office with an abstract that begins "In November 2001, the World Trade Organization launched a new set of multilateral negotiations at its ministerial conference in Doha, Qatar. The ministerial conference was important because it laid out an ambitious agenda for a broad set of new multilateral trade negotiations, set forth in the Doha Ministerial Declaration. The declaration calls for a continuation of discussions on liberalizing trade in agriculture and services which began in 2000. In addition, it provides for new talks on market access for nonagricultural products, trade and the environment, trade-related aspects of intellectual property rights, and other issues. Four main factors led to the World Trade Organization's successful launch of new multilateral trade negotiations in Doha. First, the United States' and the European Union's clear support of the launch, bolstered by the strong personal relationship between the U.S. Trade Representative and the European Union Commissioner for Trade, facilitated agreement on the agenda for new negotiations. Second, World Trade Organization members applied an effective preparation strategy before the Doha ministerial conference. Third, some key developments at the Doha conference helped gain support from the developing countries for launching negotiations. Last, World …
Date: September 4, 2002
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Bureau of Indian Affairs Schools: Expenditures in Selected Schools are Comparable to Similar Public Schools, But Data Are Insufficient to Judge Adequacy of Funding and Formulas (open access)

Bureau of Indian Affairs Schools: Expenditures in Selected Schools are Comparable to Similar Public Schools, But Data Are Insufficient to Judge Adequacy of Funding and Formulas

A letter report issued by the General Accounting Office with an abstract that begins "In 2001, Congress directed GAO to examine the adequacy of Bureau of Indian Affairs (BIA) school funding and the adequacy of the formulas employed by BIA to distribute various types of operating funds. Because there is no universally accepted standard for adequacy, for this report, GAO examined (1) the sources and amounts of federal funding provided for BIA schools and how they are determined, (2) how BIA school budgets and expenditures compared to national per-pupil expenditures and expenditures for similarly situated public schools, and (3) how equitably various formulas distribute funding across BIA schools and whether they account for all relevant costs. To obtain expenditure data for BIA schools GAO reviewed BIA budget and financial documents and collected data from 8 BIA and 6 public schools that were similar in terms of their relative isolation and student characteristics."
Date: September 4, 2003
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
GAO: Making a Difference for Congress and the Nation; Join Us (open access)

GAO: Making a Difference for Congress and the Nation; Join Us

Other written product issued by the General Accounting Office with an abstract that begins "This is an insert to GAO's publication, Serving the Congress and the Nation, describing the agency mission, work environment, and career opportunities at GAO."
Date: September 4, 2001
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Development of an Immersed Boundary Method to Resolve Complex Terrain in the Weather Research and Forecasting Model (open access)

Development of an Immersed Boundary Method to Resolve Complex Terrain in the Weather Research and Forecasting Model

Flow and dispersion processes in urban areas are profoundly influenced by the presence of buildings which divert mean flow, affect surface heating and cooling, and alter the structure of turbulence in the lower atmosphere. Accurate prediction of velocity, temperature, and turbulent kinetic energy fields are necessary for determining the transport and dispersion of scalars. Correct predictions of scalar concentrations are vital in densely populated urban areas where they are used to aid in emergency response planning for accidental or intentional releases of hazardous substances. Traditionally, urban flow simulations have been performed by computational fluid dynamics (CFD) codes which can accommodate the geometric complexity inherent to urban landscapes. In these types of models the grid is aligned with the solid boundaries, and the boundary conditions are applied to the computational nodes coincident with the surface. If the CFD code uses a structured curvilinear mesh, then time-consuming manual manipulation is needed to ensure that the mesh conforms to the solid boundaries while minimizing skewness. If the CFD code uses an unstructured grid, then the solver cannot be optimized for the underlying data structure which takes an irregular form. Unstructured solvers are therefore often slower and more memory intensive than their structured counterparts. …
Date: September 4, 2007
Creator: Lunquist, K A; Chow, F K; Lundquist, J K & Mirocha, J D
Object Type: Article
System: The UNT Digital Library
Integrated Optical Probes (open access)

Integrated Optical Probes

Optical probes used in velocimetry measurements have typically been individual probes that collect data for a single diagnostic at a single point. These probes have been used in diagnostics such as VISAR, PDV, and radiometry, which measure surface velocity, temperature, and other characteristics. When separate probes are used for these measurements, the different diagnostic points measured must be significantly separated. We have developed integrated probes that collect data for multiple optical diagnostics; these probes measure points in close proximity.
Date: September 4, 2008
Creator: Brent Frogget, Douglas DeVore, Vincent Romero, David Esquibel, and David Holtkamp
Object Type: Article
System: The UNT Digital Library
Materials Science and Technology Teachers Handbook (open access)

Materials Science and Technology Teachers Handbook

The Materials Science and Technology (MST) Handbook was developed by Pacific Northwest National Laboratory, in Richland, Washington, under support from the U.S. Department of Energy. Many individuals have been involved in writing and reviewing materials for this project since it began at Richland High School in 1986, including contributions from educators at the Northwest Regional Education Laboratory, Central Washington University, the University of Washington, teachers from Northwest Schools, and science and education personnel at Pacific Northwest National Laboratory. Support for its development was also provided by the U.S. Department of Education. This introductory course combines the academic disciplines of chemistry, physics, and engineering to create a materials science and technology curriculum. The course covers the fundamentals of ceramics, glass, metals, polymers and composites. Designed to appeal to a broad range of students, the course combines hands-on activities, demonstrations and long term student project descriptions. The basic philosophy of the course is for students to observe, experiment, record, question, seek additional information, and, through creative and insightful thinking, solve problems related to materials science and technology. The MST Teacher Handbook contains a course description, philosophy, student learning objectives, and instructional approach and processes. Science and technology teachers can collaborate to build …
Date: September 4, 2008
Creator: Wieda, Karen J.; Schweiger, Michael J.; Bliss, Mary; Pitman, Stan G. & Eschbach, Eugene A.
Object Type: Report
System: The UNT Digital Library
An Improved WRF for Urban-Scale and Complex-Terrain Applications (open access)

An Improved WRF for Urban-Scale and Complex-Terrain Applications

Simulations of atmospheric flow through urban areas must account for a wide range of physical phenomena including both mesoscale and urban processes. Numerical weather prediction models, such as the Weather and Research Forecasting model (WRF), excel at predicting synoptic and mesoscale phenomena. With grid spacings of less than 1 km (as is required for complex heterogeneous urban areas), however, the limits of WRF's terrain capabilities and subfilter scale (SFS) turbulence parameterizations are exposed. Observations of turbulence in urban areas frequently illustrate a local imbalance of turbulent kinetic energy (TKE), which cannot be captured by current turbulence models. Furthermore, WRF's terrain-following coordinate system is inappropriate for high-resolution simulations that include buildings. To address these issues, we are implementing significant modifications to the ARW core of the Weather Research and Forecasting model. First, we are implementing an improved turbulence model, the Dynamic Reconstruction Model (DRM), following Chow et al. (2005). Second, we are modifying WRF's terrain-following coordinate system by implementing an immersed boundary method (IBM) approach to account for the effects of urban geometries and complex terrain. Companion papers detailing the improvements enabled by the DRM and the IBM approaches are also presented (by Mirocha et al., paper 13.1, and K.A. Lundquist …
Date: September 4, 2007
Creator: Lundquist, J K; Chow, F K; Mirocha, J D & Lundquist, K A
Object Type: Article
System: The UNT Digital Library
Debris and Shrapnel Mitigation Procedure for NIF Experiments (open access)

Debris and Shrapnel Mitigation Procedure for NIF Experiments

All experiments at the National Ignition Facility (NIF) will produce debris and shrapnel from vaporized, melted, or fragmented target/diagnostics components. For some experiments mitigation is needed to reduce the impact of debris and shrapnel on optics and diagnostics. The final optics, e.g., wedge focus lens, are protected by two layers of debris shields. There are 192 relatively thin (1-3 mm) disposable debris shields (DDS's) located in front of an equal number of thicker (10 mm) main debris shields (MDS's). The rate of deposition of debris on DDS's affects their replacement rate and hence has an impact on operations. Shrapnel (molten and solid) can have an impact on both types of debris shields. There is a benefit to better understanding these impacts and appropriate mitigation. Our experiments on the Omega laser showed that shrapnel from Ta pinhole foils could be redirected by tilting the foils. Other mitigation steps include changing location or material of the component identified as the shrapnel source. Decisions on the best method to reduce the impact of debris and shrapnel are based on results from a number of advanced simulation codes. These codes are validated by a series of dedicated experiments. One of the 3D codes, NIF's …
Date: September 4, 2007
Creator: Eder, D.; Koniges, A.; Landen, O.; Masters, N.; Fisher, A.; Jones, O. et al.
Object Type: Article
System: The UNT Digital Library