Resource Type

Stabilizing and Rebuilding Iraq: U.S. Ministry Capacity Development Efforts Need an Overall Integrated Strategy to Guide Efforts and Manage Risk (open access)

Stabilizing and Rebuilding Iraq: U.S. Ministry Capacity Development Efforts Need an Overall Integrated Strategy to Guide Efforts and Manage Risk

A letter report issued by the Government Accountability Office with an abstract that begins "Iraq's ministries were decimated following years of neglect and centralized control under the former regime. Developing competent and loyal Iraqi ministries is critical to stabilizing and rebuilding Iraq. The President received $140 million in fiscal year 2007 funds and requested an additional $255 million in fiscal year 2008 to develop the capacity of the Iraq's ministries. This report assesses (1) the nature and extent of U.S. efforts to develop the capacity of the Iraqi ministries, (2) the key challenges to these efforts, and (3) the extent to which the U.S. government has an overall integrated strategy for these efforts. For this effort, GAO reviewed U.S. project contracts and reports and interviewed officials from the Departments of State (State), Defense (DOD), and the United States Agency for International Development (USAID) in Baghdad and Washington, D.C."
Date: October 1, 2007
Creator: United States. Government Accountability Office.
System: The UNT Digital Library
Financial Management: FFMIA Implementation Critical for Federal Accountability (open access)

Financial Management: FFMIA Implementation Critical for Federal Accountability

A letter report issued by the General Accounting Office with an abstract that begins "Effective management of the government's day-to-day operations has been hampered by a lack of necessary data. The Chief Financial Officers (CFO) Act of 1990 calls for the modernization of federal financial management systems, including the systematic measurement of performance; the development of cost information; and the integration of program, budget, and financial information. The Federal Financial Management Improvement Act of 1996 (FFMIA) encourages agencies to have systems that generate timely, accurate, and useful information with which to make informed decisions and to ensure accountability on an ongoing basis. Auditors for 19 of the 24 CFO Act agencies reported that their agencies' financial management systems did not comply substantially with FFMIA requirements, compared to 21 agencies reported as not being substantially compliant for 1999. The auditors for five CFO Act agencies reported no instances in which the agencies' systems did not substantially comply with FFMIA. These auditors, however, did not definitively state whether the agencies' financial management systems substantially complied with FFMIA. FFMIA requires agencies to prepare remediation plans to overcome financial management systems problems. These plans have improved over the fiscal year 1998 plans; however, further …
Date: October 1, 2001
Creator: United States. General Accounting Office.
System: The UNT Digital Library
Financial Management: Improved Financial Systems Are Key to FFMIA Compliance (open access)

Financial Management: Improved Financial Systems Are Key to FFMIA Compliance

A letter report issued by the Government Accountability Office with an abstract that begins "The ability to produce the data needed to efficiently and effectively manage the day-to-day operations of the federal government and provide accountability to taxpayers has been a long-standing challenge to most federal agencies. To help address this challenge, the Federal Financial Management Improvement Act of 1996 (FFMIA) requires the 23 Chief Financial Officers Act agencies to implement and maintain financial management systems that comply substantially with (1) federal financial management systems requirements, (2) applicable federal accounting standards, and (3) the U.S. Government Standard General Ledger (SGL) at the transaction level. FFMIA also requires GAO to report annually on the implementation of the act."
Date: October 1, 2004
Creator: United States. Government Accountability Office.
System: The UNT Digital Library
Contingency Contracting: DOD, State, and USAID Contracts and Contractor Personnel in Iraq and Afghanistan (open access)

Contingency Contracting: DOD, State, and USAID Contracts and Contractor Personnel in Iraq and Afghanistan

A letter report issued by the Government Accountability Office with an abstract that begins "The Departments of Defense (DOD) and State and the United States Agency for International Development (USAID) have relied extensively on contractors to carry out a range of services in Iraq and Afghanistan. While recognizing the benefits of using contractors, GAO and others have noted the challenges and risks associated with an increased reliance on contractors and the ability of agencies to manage their growing number of contractors. As directed by the National Defense Authorization Act for Fiscal Year 2008, GAO analyzed DOD, State, and USAID data on contracting activities in Iraq and Afghanistan for fiscal year 2007 and the first half of fiscal year 2008 including (1) the number and value of contracts and the extent they were awarded competitively; (2) the number of contractor personnel, including those performing security functions; and (3) the number of contractor personnel who were killed or wounded. GAO also reviewed the status of the three agencies' memorandum of understanding (MOU) related to maintaining data on contracts and contractor personnel. GAO reviewed selected contract files and compared personnel data to other available sources to assess the reliability of the data reported …
Date: October 1, 2008
Creator: United States. Government Accountability Office.
System: The UNT Digital Library
Contingency Contracting: DOD, State, and USAID Continue to Face Challenges in Tracking Contractor Personnel and Contracts in Iraq and Afghanistan (open access)

Contingency Contracting: DOD, State, and USAID Continue to Face Challenges in Tracking Contractor Personnel and Contracts in Iraq and Afghanistan

A letter report issued by the Government Accountability Office with an abstract that begins "The Departments of Defense (DOD) and State and the U.S. Agency for International Development (USAID) have relied extensively on contractors to provide a range of services in Iraq and Afghanistan, but as GAO has previously reported, the agencies have faced challenges in obtaining sufficient information to plan and manage their use of contractors. As directed by the National Defense Authorization Act for Fiscal Year (FY) 2008, GAO analyzed DOD, State, and USAID data for Iraq and Afghanistan for FY 2008 and the first half of FY 2009 on the (1) status of agency efforts to track information on contracts and contractor personnel; (2) number of contractor personnel; (3) number of killed and wounded contractors; and (4) number and value of contracts and extent to which they were awarded competitively. GAO reviewed selected contracts and compared personnel data to other available sources to assess the reliability of agency-reported data."
Date: October 1, 2009
Creator: United States. Government Accountability Office.
System: The UNT Digital Library
Head Start: Increased Percentage of Teachers Nationwide Have Required Degrees, but Better Information on Classroom Teachers' Qualifications Needed (open access)

Head Start: Increased Percentage of Teachers Nationwide Have Required Degrees, but Better Information on Classroom Teachers' Qualifications Needed

A letter report issued by the General Accounting Office with an abstract that begins "The 1998 Head Start Act mandated that 50 percent of all Head Start teachers nationwide have a minimum of an associate degree in early childhood education, or, in a related field with preschool teaching experience, by September 30, 2003. This law also required that each classroom in center-based programs (those that primarily provide services in classroom settings) without such a degreed teacher have a teacher with a Child Development Associate credential or an equivalent state certificate. In preparation for the reauthorization of Head Start in fiscal year 2003, GAO was asked to examine: (1) the extent to which Head Start has met legislative mandates concerning teacher qualifications; (2) whether Head Start teachers' salaries have increased and enabled grantees to attract and retain teachers with degrees; and (3) the extent to which degree and other programs in early childhood education are available for Head Start teachers and if grantees have taken steps to enhance access to them."
Date: October 1, 2003
Creator: United States. General Accounting Office.
System: The UNT Digital Library
Financial Management: FFMIA Implementation Necessary to Achieve Accountability (open access)

Financial Management: FFMIA Implementation Necessary to Achieve Accountability

A letter report issued by the General Accounting Office with an abstract that begins "The ability to produce the data needed to efficiently and effectively manage the day-to-day operations of the federal government and provide accountability to taxpayers has been a long-standing challenge at most federal agencies. To help address this challenge, the Federal Financial Management Improvement Act of 1996 (FFMIA) requires the 24 Chief Financial Officers Act agencies to implement and maintain financial management systems that comply substantially with (1) federal system requirements, (2) federal accounting standards, and (3) the U.S. Government Standard General Ledger (SGL). FFMIA also requires GAO to report annually on the implementation of the act."
Date: October 1, 2002
Creator: United States. General Accounting Office.
System: The UNT Digital Library
Economic Benefits, Carbon Dioxide (CO2) Emissions Reductions, and Water Conservation Benefits from 1,000 Megawatts (MW) of New Wind Power in Pennsylvania (Fact Sheet) (open access)

Economic Benefits, Carbon Dioxide (CO2) Emissions Reductions, and Water Conservation Benefits from 1,000 Megawatts (MW) of New Wind Power in Pennsylvania (Fact Sheet)

The U.S. Department of Energy?s Wind Powering America Program is committed to educating state-level policymakers and other stakeholders about the economic, CO2 emissions, and water conservation impacts of wind power. This analysis highlights the expected impacts of 1000 MW of wind power in Pennsylvania. Although construction and operation of 1000 MW of wind power is a significant effort, six states have already reached the 1000-MW mark. We forecast the cumulative economic benefits from 1000 MW of development in Pennsylvania to be $1.2 billion, annual CO2 reductions are estimated at 3.4 million tons, and annual water savings are 1,837 million gallons.
Date: October 1, 2008
Creator: unknown
System: The UNT Digital Library
CHARICE version 1.1 update. (open access)

CHARICE version 1.1 update.

CHARICE (CHARacteristics-based inverse analysis of Isentropic Compression Experiments) is a computer application, previously documented in SAND2007-4948, that analyzes velocity waveform data from ramp-wave experiments to determine a material's quasi-isentropic loading response in stress and density using an iterative characteristics-based approach. This short report documents only the changes in CHARICE release version 1.1 relative to release version 1.0, and is not intended to stand alone. CHARICE version 1.1 corrects an error in the algorithm of the method, fixes several bugs, improves robustness and performance, provides more useful error descriptions, and adds a number of minor features.
Date: October 1, 2008
Creator: Davis, Jean-Paul
System: The UNT Digital Library
Clean Cities: Ethanol Basics, Fact Sheet, October 2008 (open access)

Clean Cities: Ethanol Basics, Fact Sheet, October 2008

Document answers frequently asked questions about ethanol as a transportation fuel, including those on production, environmental effects, and vehicles.
Date: October 1, 2008
Creator: unknown
System: The UNT Digital Library
In-situ scanning probe microscopy of electrodeposited nickel. (open access)

In-situ scanning probe microscopy of electrodeposited nickel.

The performance characteristics and material properties such as stress, microstructure, and composition of nickel coatings and electroformed components can be controlled over a wide range by the addition of small amounts of surface-active compounds to the electroplating bath. Saccharin is one compound that is widely utilized for its ability to reduce tensile stress and refine grain size in electrodeposited nickel. While the effects of saccharin on nickel electrodeposition have been studied by many authors in the past, there is still uncertainty over saccharin's mechanisms of incorporation, stress reduction, and grain refinement. In-situ scanning probe microscopy (SPM) is a tool that can be used to directly image the nucleation and growth of thin nickel films at nanometer length scales to help elucidate saccharin's role in the development and evolution of grain structure. In this study, in-situ atomic force microscopy (AFM) and scanning tunneling microscopy (STM) techniques are used to investigate the effects of saccharin on the morphological evolution of thin nickel films. By observing mono-atomic height nickel island growth with and without saccharin present we conclude that saccharin has little effect on the nickel surface mobility during deposition at low overpotentials where the growth occurs in a layer-by-layer mode. Saccharin was …
Date: October 1, 2004
Creator: Kelly, James J. & Dibble, Dean C.
System: The UNT Digital Library
Geometric optimization of the 56 MHz SRF cavity and its frequency table (open access)

Geometric optimization of the 56 MHz SRF cavity and its frequency table

It is essential to know the frequency of a Superconducting Radio Frequency (SRF) cavity at its 'just being fabricated' stage because frequency is the key parameter in constructing the cavity. In this paper, we report our work on assessing it. We can estimate the frequency change from stage to stage theoretically and/or by simulation. At the operating stage, the frequency can be calculated accurately, and, from this value, we obtain the frequencies at other stages. They are listed in a table that serves to check the processes from stage to stage. Equally important is optimizing the geometric shape of the SRF cavity so that the peak electric-field and peak magnetic-field are as low as possible. It is particularly desirable in the 56MHz SRF cavity of RHIC to maximize the frequency sensitivity of the slow tuner. After undertaking such optimization, our resultant peak electric-field is only 44.1MV/m, and the peak magnetic-field is 1049G at 2.5MV of voltage across the cavity gap. To quench superconductivity in an SRF cavity, it is reported that the limit of the peak magnetic-field is 1800G [1], and that of the peak electric-field is more than l00MV/m for a SRF cavity [2]. Our simulations employed the codes …
Date: October 1, 2008
Creator: Chang, X. & Ben-Zvi, Ilan
System: The UNT Digital Library
Shillapoo Wildlife Area, Annual Report 2007-2008. (open access)

Shillapoo Wildlife Area, Annual Report 2007-2008.

This report summarizes accomplishments, challenges and successes on WDFW's Shillapoo Wildlife Area funded under Bonneville Power Administration's (BPA) Wildlife Mitigation Program (BPA project No.2003-012-00) during the Fiscal Year 08 contract period October 1, 2007-September 30, 2008. The information presented here is intended to supplement that contained in BPA's PISCES contract development and reporting system. The organization below is by broad categories of work but references are made to individual work elements in the PISCES Statement of Work as appropriate. Significant progress was realized in almost all major work types. Of particular note was progress made in tree plantings and pasture rehabilitation efforts. This year's tree planting effort included five sites detailed below and in terms of the number of plants was certainly the largest effort on the wildlife area to date in one season. The planting itself took a significant amount of time, which was anticipated. However, installation of mats and tubes took much longer than expected which impacted planned fence projects in particular. Survival of the plantings appears to be good. Improvement to the quality of waterfowl pasture habitats is evident on a number of sites due to replanting and weed control efforts. Continuing long-term weed control efforts will …
Date: October 1, 2007
Creator: Calkins, Brian
System: The UNT Digital Library
Economic Benefits, Carbon Dioxide (CO2) Emissions Reductions, and Water Conservation Benefits from 1,000 Megawatts (MW) of New Wind Power in Wisconsin (Fact Sheet) (open access)

Economic Benefits, Carbon Dioxide (CO2) Emissions Reductions, and Water Conservation Benefits from 1,000 Megawatts (MW) of New Wind Power in Wisconsin (Fact Sheet)

The U.S. Department of Energy?s Wind Powering America Program is committed to educating state-level policymakers and other stakeholders about the economic, CO2 emissions, and water conservation impacts of wind power. This analysis highlights the expected impacts of 1000 MW of wind power in Wisconsin. Although construction and operation of 1000 MW of wind power is a significant effort, six states have already reached the 1000-MW mark. We forecast the cumulative economic benefits from 1000 MW of development in Wisconsin to be $1.1 billion, annual CO2 reductions are estimated at 3.2 million tons, and annual water savings are 1,476 million gallons.
Date: October 1, 2008
Creator: unknown
System: The UNT Digital Library
Idaho National Laboratory Cultural Resource Monitoring Report for Fiscal Year 2007 (open access)

Idaho National Laboratory Cultural Resource Monitoring Report for Fiscal Year 2007

This report describes the cultural resource monitoring activities of the Idaho National Laboratory’s (INL) Cultural Resource Management (CRM) Office during fiscal year 2007 (FY 2007). In FY 2007, 40 localities were revisited: two locations of heightened Shoshone-Bannock tribal sensitivity, four caves, three butte/craters, twelve prehistoric archaeological sites, two historic stage stations, nine historic homesteads, a portion of Goodale’s Cutoff of the Oregon Trail, a portion of historic trail T-16, one World War II dump, four buildings from the World War II period, and Experimental Breeder Reactor –I, a modern scientific facility and National Historic Landmark. Several INL project areas were also monitored in FY 2007. This included direct observation of ground disturbing activities within the Power Burst Facility (PBF, now designated as the Critical Infrastructure Test Range Complex – CITRC), backfilling operations associated with backhoe trenches along the Big Lost River, and geophysical surveys designed to pinpoint subsurface unexploded ordnance in the vicinity of the Naval Ordnance Disposal Area. Surprise checks were also made to three ongoing INL projects to ensure compliance with INL CRM Office recommendations to avoid impacts to cultural resources. Although some impacts were documented, no significant adverse effects that would threaten the National Register eligibility of …
Date: October 1, 2007
Creator: Pace, Brenda R.
System: The UNT Digital Library
Measuring the maturity of a technology : guidance on assigning a TRL. (open access)

Measuring the maturity of a technology : guidance on assigning a TRL.

This report provides guidance on how to assign a technology readiness level (TRL). The method proposed assists in assigning TRLs through a series of questions that focus on a set of unambiguous maturation metrics. This method is slightly biased towards the environment and approach to technology maturation at Sandia National Laboratories where customers and suppliers are in very close proximity to one another, allowing for supplier-customer interactions at a very early stage in technology development. The hope is that this report can serve as a practical guide to anyone trying to understand the maturity of a specific technology. Risk is reduced in system acquisition by selecting mature technologies for inclusion in system development. TRLs are used to assess the maturity of evolving technologies and therefore become part of an overall risk reduction strategy in system development.
Date: October 1, 2007
Creator: Mitchell, John Anthony
System: The UNT Digital Library
Economic Benefits, Carbon Dioxide (CO2) Emissions Reductions, and Water Conservation Benefits from 1,000 Megawatts (MW) of New Wind Power in New Mexico (Fact Sheet) (open access)

Economic Benefits, Carbon Dioxide (CO2) Emissions Reductions, and Water Conservation Benefits from 1,000 Megawatts (MW) of New Wind Power in New Mexico (Fact Sheet)

The U.S. Department of Energy?s Wind Powering America Program is committed to educating state-level policymakers and other stakeholders about the economic, CO2 emissions, and water conservation impacts of wind power. This analysis highlights the expected impacts of 1000 MW of wind power in New Mexico. Although construction and operation of 1000 MW of wind power is a significant effort, six states have already reached the 1000-MW mark. We forecast the cumulative economic benefits from 1000 MW of development in New Mexico to be $1.1 billion, annual CO2 reductions are estimated at 2.6 million tons, and annual water savings are 1,117 million gallons.
Date: October 1, 2008
Creator: unknown
System: The UNT Digital Library
Scalable fault tolerant algorithms for linear-scaling coupled-cluster electronic structure methods. (open access)

Scalable fault tolerant algorithms for linear-scaling coupled-cluster electronic structure methods.

By means of coupled-cluster theory, molecular properties can be computed with an accuracy often exceeding that of experiment. The high-degree polynomial scaling of the coupled-cluster method, however, remains a major obstacle in the accurate theoretical treatment of mainstream chemical problems, despite tremendous progress in computer architectures. Although it has long been recognized that this super-linear scaling is non-physical, the development of efficient reduced-scaling algorithms for massively parallel computers has not been realized. We here present a locally correlated, reduced-scaling, massively parallel coupled-cluster algorithm. A sparse data representation for handling distributed, sparse multidimensional arrays has been implemented along with a set of generalized contraction routines capable of handling such arrays. The parallel implementation entails a coarse-grained parallelization, reducing interprocessor communication and distributing the largest data arrays but replicating as many arrays as possible without introducing memory bottlenecks. The performance of the algorithm is illustrated by several series of runs for glycine chains using a Linux cluster with an InfiniBand interconnect.
Date: October 1, 2004
Creator: Leininger, Matthew L.; Nielsen, Ida Marie B. & Janssen, Curtis L.
System: The UNT Digital Library
Addendum to the Streamlined Approach for Environmental Restoration Closure Report for Corrective Action Unit 454: Historical Undrground Storage Tank Release Sites, Nevada Test Site, Nevada, Revision 0 (open access)

Addendum to the Streamlined Approach for Environmental Restoration Closure Report for Corrective Action Unit 454: Historical Undrground Storage Tank Release Sites, Nevada Test Site, Nevada, Revision 0

This document constitutes an addendum to the April 1998, Streamlined Approach for Environmental Restoration Closure Report for Corrective Action Unit 454: Historical Underground Storage Tank Release Sites as described in the document Recommendations and Justifications for Modifications for Use Restrictions Established under the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office Federal Facility Agreement and Consent Order (UR Modification document) dated February 2008. The UR Modification document was approved by NDEP on February 26, 2008. The approval of the UR Modification document constituted approval of each of the recommended UR modifications. In conformance with the UR Modification document, this addendum consists of: • This cover page that refers the reader to the UR Modification document for additional information • The cover and signature pages of the UR Modification document • The NDEP approval letter • The corresponding section of the UR Modification document This addendum provides the documentation justifying the cancellation of the UR for CAS 12-25-09, Spill 960722-02 (from UST 12-B-3). This UR was established as part of a Federal Facility Agreement and Consent Order (FFACO) corrective action and is based on the presence of contaminants at concentrations greater than the action levels established at the …
Date: October 1, 2008
Creator: Kidman, Lynn
System: The UNT Digital Library
Cell Phone Detection Techniques (open access)

Cell Phone Detection Techniques

A team composed of Rick Pratt, Dave Puczyki, Kyle Bunch, Ryan Slaugh, Morris Good, and Doug McMakin teamed together to attempt to exploit cellular telephone features and detect if a person was carrying a cellular telephone into a Limited Area. The cell phone’s electromagnetic properties were measured, analyzed, and tested in over 10 different ways to determine if an exploitable signature exists. The method that appears to have the most potential for success without adding an external tag is to measure the RF spectrum, not in the cell phone band, but between 240 and 400MHz. Figures 1- 7 show the detected signal levels from cell phones from three different manufacturers.
Date: October 1, 2007
Creator: Pratt, Richard M.; Bunch, Kyle J.; Puzycki, David J.; Slaugh, Ryan W.; Good, Morris S. & McMakin, Douglas L.
System: The UNT Digital Library
Addendum to the Closure Report for Corrective Action Unit 394: Areas 12, 18, and 29 Spill/Release Sites Nevada Test Site, Nevada, Revision 0 (open access)

Addendum to the Closure Report for Corrective Action Unit 394: Areas 12, 18, and 29 Spill/Release Sites Nevada Test Site, Nevada, Revision 0

This document constitutes an addendum to the September 2003, Closure Report for Corrective Action Unit 394: Areas 12, 18, and 29 Spill/Release Sites as described in the document Recommendations and Justifications for Modifications for Use Restrictions Established under the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office Federal Facility Agreement and Consent Order (UR Modification document) dated February 2008. The UR Modification document was approved by NDEP on February 26, 2008. The approval of the UR Modification document constituted approval of each of the recommended UR modifications. In conformance with the UR Modification document, this addendum consists of: • This cover page that refers the reader to the UR Modification document for additional information • The cover and signature pages of the UR Modification document • The NDEP approval letter • The corresponding section of the UR Modification document This addendum provides the documentation justifying the cancellation of the URs for: • CAS 12-25-04, UST 12-16-2 Waste Oil Release • CAS 18-25-01, Oil Spills • CAS 18-25-02, Oil Spills • CAS 18-25-03, Oil Spill • CAS 29-44-01, Fuel Spill These URs were established as part of Federal Facility Agreement and Consent Order (FFACO) corrective actions and were …
Date: October 1, 2008
Creator: Kidman, Lynn
System: The UNT Digital Library
Experimental Breeder Reactor I Preservation Plan (open access)

Experimental Breeder Reactor I Preservation Plan

Experimental Breeder Reactor I (EBR I) is a National Historic Landmark located at the Idaho National Laboratory, a Department of Energy laboratory in southeastern Idaho. The facility is significant for its association and contributions to the development of nuclear reactor testing and development. This Plan includes a structural assessment of the interior and exterior of the EBR I Reactor Building from a preservation, rather than an engineering stand point and recommendations for maintenance to ensure its continued protection.
Date: October 1, 2006
Creator: Braun, Julie
System: The UNT Digital Library
Computational investigation of noble gas adsorption and separation by nanoporous materials. (open access)

Computational investigation of noble gas adsorption and separation by nanoporous materials.

Molecular simulations are used to assess the ability of metal-organic framework (MOF) materials to store and separate noble gases. Specifically, grand canonical Monte Carlo simulation techniques are used to predict noble gas adsorption isotherms at room temperature. Experimental trends of noble gas inflation curves of a Zn-based material (IRMOF-1) are matched by the simulation results. The simulations also predict that IRMOF-1 selectively adsorbs Xe atoms in Xe/Kr and Xe/Ar mixtures at total feed gas pressures of 1 bar (14.7 psia) and 10 bar (147 psia). Finally, simulations of a copper-based MOF (Cu-BTC) predict this material's ability to selectively adsorb Xe and Kr atoms when present in trace amounts in atmospheric air samples. These preliminary results suggest that Cu-BTC may be an ideal candidate for the pre-concentration of noble gases from air samples. Additional simulations and experiments are needed to determine the saturation limit of Cu-BTC for xenon, and whether any krypton atoms would remain in the Cu-BTC pores upon saturation.
Date: October 1, 2008
Creator: Allendorf, Mark D. (Sandia National Laboratories, Livermore, CA); Sanders, Joseph C. & Greathouse, Jeffery A.
System: The UNT Digital Library
The mechanics of soft biological composites. (open access)

The mechanics of soft biological composites.

Biological tissues are uniquely structured materials with technologically appealing properties. Soft tissues such as skin, are constructed from a composite of strong fibrils and fluid-like matrix components. This was the first coordinated experimental/modeling project at Sandia or in the open literature to consider the mechanics of micromechanically-based anisotropy and viscoelasticity of soft biological tissues. We have exploited and applied Sandia's expertise in experimentation and mechanics modeling to better elucidate the behavior of collagen fibril-reinforced soft tissues. The purpose of this project was to provide a detailed understanding of the deformation of ocular tissues, specifically the highly structured skin-like tissue in the cornea. This discovery improved our knowledge of soft/complex materials testing and modeling. It also provided insight into the way that cornea tissue is bio-engineered such that under physiologically-relevant conditions it has a unique set of properties which enhance functionality. These results also provide insight into how non-physiologic loading conditions, such as corrective surgeries, may push the cornea outside of its natural design window, resulting in unexpected non-linear responses. Furthermore, this project created a clearer understanding of the mechanics of soft tissues that could lead to bio-inspired materials, such as highly supple and impact resistant body armor, and improve our …
Date: October 1, 2007
Creator: Nguyen, Thao D. (Sandia National Laboratories, Livermore, CA); Grazier, John Mark; Boyce, Brad Lee & Jones, Reese E. (Sandia National Laboratories, Livermore, CA)
System: The UNT Digital Library