Bentonite mat demonstration. Final report (open access)

Bentonite mat demonstration. Final report

The Bentonite Mat Demonstration was developed to provide the Environmental Restoration Department with field performance characteristics and engineering data for an alternative closure cover system configuration. The demonstration was initiated in response to regulatory concerns regarding the use of an alternative cover system for future design configurations. These design considerations are in lieu of the US Environmental Protection Agency (EPA) Recommended Design for Closure Cover Systems and specifically a single compacted kaolin clay layer with a hydraulic conductivity of 1 {times} 10{sup {minus}7} cm/sec. This alternative configuration is a composite geosynthetic material hydraulic barrier consisting from bottom to top: 2 ft compacted sandy clay layer (typical local Savannah River Site soil type) that is covered by a bentonite mat--geosynthetic clay liner (GCL) and is overlaid by a 40 mil High Density Polyethylene (HDPE) geomembrane--flexible membrane liner. This effort was undertaken to obtain and document the necessary field performance/engineering data for future designs and meet regulatory technical requirements for an alternative cover system configuration. The composite geosynthetic materials hydraulic barrier is the recommended alternative cover system configuration for containment of hazardous and low level radiological waste layers that have a high potential of subsidence to be used at the Savannah River …
Date: December 30, 1994
Creator: Serrato, M.G.
Object Type: Report
System: The UNT Digital Library
Compliance matrix for the Mixed Waste Disposal Facilities, Trenches 31 and 34, burial ground 218-W-5. Revision 1 (open access)

Compliance matrix for the Mixed Waste Disposal Facilities, Trenches 31 and 34, burial ground 218-W-5. Revision 1

The purpose of the Trench 31 and 34 Mixed Waste Disposal Facility Compliance Matrix is to provide objective evidence of implementation of all regulatory and procedural--institutional requirements for the disposal facilities. This matrix provides a listing of the individual regulatory and procedural--institutional requirements that were addressed. Subject matter experts reviewed pertinent documents that had direct or indirect impact on the facility. Those found to be applicable were so noted and listed in Appendix A. Subject matter experts then extracted individual requirements from the documents deemed applicable and listed them in the matrix tables. The results of this effort are documented in Appendix B. The implementing compliance documentation for WHC-CM manuals is not included in Appendix B because these are, by definition, implementing documents.
Date: December 30, 1994
Creator: Carlyle, D. W.
Object Type: Report
System: The UNT Digital Library
Control of a long reach manipulator with suspension cables for waste storage tank remediation. Final report (open access)

Control of a long reach manipulator with suspension cables for waste storage tank remediation. Final report

A long reach manipulator will be used for waste remediation in large underground storage tanks. The manipulator`s slenderness makes it flexible and difficult to control. A low-cost and effective method to enhance the manipulator`s stiffness is proposed in this research by using suspension cables. These cables can also be used to accurately measure the position of the manipulator`s wrist.
Date: December 30, 1994
Creator: Wang, S. L.
Object Type: Report
System: The UNT Digital Library
Demonstration testing and evaluation of in situ soil heating. Treatability study work plan (Revision 2) (open access)

Demonstration testing and evaluation of in situ soil heating. Treatability study work plan (Revision 2)

A Treatability Study planned for the demonstration of the in situ electromagnetic (EM) heating process to remove organic solvents is described in this Work Plan. The treatability study will be conducted by heating subsurface vadose-zone soils in an organic plume adjacent to the Classified Burial Ground K-1070-D located at K-25 Site, Oak Ridge. The test is scheduled to start during the fourth quarter of FY94 and will be completed during the first quarter of FY95. Over the last nine years, a number of Government agencies (EPA, Army, AF, and DOE) and industries sponsored further development and testing of the in situ heating and soil decontamination process for the remediation of soils containing hazardous organic contaminants. In this process the soil is heated in situ using electrical energy. The contaminants are removed from the soil due to enhanced vaporization, steam distillation and stripping. IITRI will demonstrate the EM Process for in situ soil decontamination at K-25 Site under the proposed treatability study. Most of the contaminants of concern are volatile organics which can be removed by heating the soil to a temperature range of 85{degrees} to 95{degrees}C. The efficiency of the treatment will be determined by comparing the concentration of contaminants …
Date: December 30, 1994
Creator: Sresty, G. C.
Object Type: Report
System: The UNT Digital Library
EIA model documentation: Petroleum Market Model of the National Energy Modeling System (open access)

EIA model documentation: Petroleum Market Model of the National Energy Modeling System

The purpose of this report is to define the objectives of the Petroleum Market Model (PMM), describe its basic approach, and provide detail on how it works. This report is intended as a reference document for model analysts, users, and the public. Documentation of the model is in accordance with EIA`s legal obligation to provide adequate documentation in support of its models (Public Law 94-385, section 57.b.2). The PMM models petroleum refining activities, the marketing of products, the production of natural gas liquids and domestic methanol, projects petroleum provides and sources of supplies for meeting demand. In addition, the PMM estimates domestic refinery capacity expansion and fuel consumption.
Date: December 30, 1994
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Electric vehicles: Likely consequences of US and other nations` programs and policies (open access)

Electric vehicles: Likely consequences of US and other nations` programs and policies

This report examines international electric vehicle development and commercialization programs. The study encompassed a review of current barriers to widespread electric vehicle implementation, field visits in seven nations and the United States to examine electric vehicle programs and policies, and analyses of electric vehicle effects on economics, energy, and the environment.
Date: December 30, 1994
Creator: Chan, Kwai-Cheung
Object Type: Report
System: The UNT Digital Library
Interim safety basis compliance matrix for Trenches 31 and 34 (open access)

Interim safety basis compliance matrix for Trenches 31 and 34

The tables provided in this document identify the specific requirements and basis for the administrative controls established in the Westinghouse Hanford Company (WHC) Solid Waste Burial Ground (SWBG) Interim Safety Basis (ISB) for operation of the Project W-025, Mixed Waste Lined Landfill (Trenches 31 and 34). The tables document the necessary controls and implementing procedures to ensure compliance with the requirements of the ISB. These requirements provide a basis for future Unreviewed Safety Questions (USQ) screening of applicable procedure changes, proposed physical modifications, tests, experiments, and occurrences. Table 1 provides the SWBG interim Operational Safety Requirements administrative controls matrix. The specific assumptions and commitments used in the safety analysis documents applicable to disposal of mixed wastes in Trenches 31 and 34 are provided in Table 2. Table 3 is provided to document the potential engineered and administrative mitigating features identified in the Preliminary Hazard Analysis (PHA) for disposal of mixed waste.
Date: December 30, 1994
Creator: Ames, R. R.
Object Type: Report
System: The UNT Digital Library
Safety evaluation of interim stabilization of non-stabilized single-shell watch list tanks (open access)

Safety evaluation of interim stabilization of non-stabilized single-shell watch list tanks

The report provides a summation of the status of safety issues associated with interim stabilization of Watch List SSTs (organic, ferrocyanide, and flammable gas), as extracted from recent safety analyses, including the Tank Farms Accelerated Safety Analysis efforts.
Date: December 30, 1994
Creator: Stahl, S. M.
Object Type: Report
System: The UNT Digital Library
Subcontracting strategy for the decontamination and decommissioning of Savannah River Site`s First Tritium Extraction Facility, 232-F (open access)

Subcontracting strategy for the decontamination and decommissioning of Savannah River Site`s First Tritium Extraction Facility, 232-F

The Savannah River Site (SRS) has been actively proceeding with the decontamination and decommissioning (D&D) of various facilities and structures which were instrumental in the success of past missions at the site. The most ambitious of these efforts involves the subcontracting of the complete D&D of the first SRS Tritium Extraction Facility, identified as building 232-F. This facility operated in the mid 1950`s and discontinued operations permanently in 1958. The approach utilized for this effort attempts to invoke the novel principle of {open_quotes}As Commercial As Reasonably Achievable{close_quotes} or {open_quotes}ACARA{close_quotes}. This concept of ACARA applies only the minimum essential requirements necessary to successfully perform the D&D task. Integral to this approach is the subcontractor provision for maximum flexibility in the identification of and adherence to the requirements of applicable DOE Orders, federal, state and local laws and regulations, as well as site specific procedures without violating the site contractual requirements. The technical specification prepared for this effort provides the basis for a competitively bid contract to perform the entire D&D evolution, including initial facility characterization, waste stream characterization and certification, D&D and waste disposal. Preparation and development of this specification and the subsequent Request For Proposal (RFP) was a successful team …
Date: December 30, 1994
Creator: Smith, C. W., Jr.; Dowd, A. S., Jr.; Hinds, S. S. & Johnson, S. V.
Object Type: Article
System: The UNT Digital Library
Summary report of Hanford Site well remediation and decommissioning activities for fiscal year 1994 (open access)

Summary report of Hanford Site well remediation and decommissioning activities for fiscal year 1994

Remediation and decommissioning of Hanford Site wells has become an integral part of Hanford Site Environmental Restoration (ER) and Resource Conservation and Recovery Act of 1976 (RCRA) groundwater monitoring programs. A well remediation and decommissioning program was funded and implemented in fiscal year (FY) 1993 under the RCRA and Operational Monitoring (ROM) Program. Funding for this work increased in FY 1994. In FY 1994 well decommissioning activities conducted for the ROM program were centered around the 200 West Area; activities for the ER program were centered in the Fitzner/Eberhart Arid Land Ecology (ALE) (Reserve) unit and the Wahluke Slope (North Slope) area. A total of 116 wells and test borings were decommissioned between the two programs during FY 1994. Additionally, five wells were identified as in need of remediation and were successfully brought into compliance with regulatory requirements. As Hanford Site restoration and remediation efforts increase in scope, the well decommissioning program will remain dynamic. The program will aggressively seek to fulfill the needs of the various environmental cleanup and groundwater/vadose monitoring programs. Wells that do not meet regulatory requirements for preservation will continually be identified and remediated or decommissioned accordingly.
Date: December 30, 1994
Creator: Reynolds, K. D.
Object Type: Report
System: The UNT Digital Library
Advanced Physical Coal Cleaning to Comply With Potential Air Toxic Regulations. [Quarterly] Technical Report, September 1--November 30, 1994 (open access)

Advanced Physical Coal Cleaning to Comply With Potential Air Toxic Regulations. [Quarterly] Technical Report, September 1--November 30, 1994

This research project will investigate the use of advanced fine coal cleaning technologies for cleaning PCB feed as a compliance strategy. Trace elements considered in this project will include mercury, selenium, cadmium, and chlorine. Work in the first quarter has focused on trace element analysis procedures and sample acquisition. Several experts in the field of trace element analysis of coal have been consulted and these procedures are presently being evaluated.
Date: November 30, 1994
Creator: Honaker, R. Q.; Paul, B. C. & Wang, D.
Object Type: Report
System: The UNT Digital Library
Appendices to report on DOE analytical laboratory capacity available to meet EM environmental sampling and analysis needs for FY 93-99 (open access)

Appendices to report on DOE analytical laboratory capacity available to meet EM environmental sampling and analysis needs for FY 93-99

The DOE Analytical Laboratory Capacity Study was conducted to give EM-263 current information about existing and future analytical capacities and capabilities of site laboratories within the DOE Complex. Each DOE site may have one or more analytical laboratories in operation. These facilities were established to support site missions such as production, research and development, and personnel and environmental monitoring. With changing site missions and the DOE directives for environmental monitoring and cleanup, these laboratories are either devoting or planning to devote resources to support EM activities. The DOE site laboratories represent a considerable amount of capital investment and analytical capability, capacity, and expertise that can be applied to support the EM mission. They not only provide cost-effective high-volume analytical laboratory services, but are also highly recognized analytical research and development centers. Several sites have already transferred their analytical capability from traditional production support to environmental monitoring and waste management support. A model was developed to determine the analytical capacity of all laboratories in the DOE Complex. The model was applied at nearly all the major laboratories and the results collected from these studies are summarized in this report.
Date: November 30, 1994
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Assessing the impacts of climate change on natural resource systems (open access)

Assessing the impacts of climate change on natural resource systems

This volume is a collection of papers addressing the theme of potential impacts of climatic change. Papers are entitled Integrated Assessments of the Impacts of Climatic Change on Natural Resources: An Introductory Editorial; Framework for Integrated Assessments of Global Warming Impacts; Modeling Land Use and Cover as Part of Global Environmental Change; Assessing Impacts of Climatic Change on Forests: The State of Biological Modeling; Integrating Climatic Change and Forests: Economic and Ecological Assessments; Environmental Change in Grasslands: Assessment using Models; Assessing the Socio-economic Impacts of Climatic Change on Grazinglands; Modeling the Effects of Climatic Change on Water Resources- A Review; Assessing the Socioeconomic Consequences of Climate Change on Water Resources; and Conclusions, Remaining Issues, and Next Steps.
Date: November 30, 1994
Creator: Frederick, Kenneth D. & Rosenberg, Norman J.
Object Type: Report
System: The UNT Digital Library
Coal-water slurry fuel combustion testing in an oil-fired industrial boiler. Semiannual technical progress report, August 15, 1993--February 15, 1994 (open access)

Coal-water slurry fuel combustion testing in an oil-fired industrial boiler. Semiannual technical progress report, August 15, 1993--February 15, 1994

The Pennsylvania State University is conducting a coal-water slurry fuel (CWSF) program with the objective of determining the viability of firing CWSF in an industrial boiler designed for heavy fuel oil. The project will also provide information to help in the design of new systems specifically configured to fire these clean coal-based fuels. The project consists of four phases: (1) design, permitting, and test planning, (2) construction and start up, (3) demonstration and evaluation (1,000-hour demonstration), and (4) expanded demonstration and evaluation (installing a CWSF preparation circuit, conducting an additional 1,000 hours of testing, and installing an advanced flue gas treatment system). The boiler testing and evaluation will determine if the CWSF combustion characteristics, heat release rate, fouling and slagging behavior, corrosion and erosion tendencies, and fuel transport, storage, and handling characteristics can be accommodated in a boiler system designed to fire heavy fuel oil. In addition, the proof-of-concept demonstration will generate data to determine how the properties of a CWSF and its parent coal affect boiler performance. The economic factors associated with retrofitting boilers will also be evaluated. The first demonstrations been completed and the combustion performance of the burner that was provided with the boiler has been determined …
Date: November 30, 1994
Creator: Miller, B. G.; Morrison, J. L.; Poe, R. L. & Scaroni, A. W.
Object Type: Report
System: The UNT Digital Library
Coal-water slurry fuel combustion testing in an oil-fired industrial boiler. Semiannual technical progress report, February 15, 1994--August 15, 1994 (open access)

Coal-water slurry fuel combustion testing in an oil-fired industrial boiler. Semiannual technical progress report, February 15, 1994--August 15, 1994

The Pennsylvania State University is conducting a coal-water slurry fuel (CWSF) program for the United States Department of Energy (DOE) and the Commonwealth of Pennsylvania with the objective of determining the viability of firing CWSF in an industrial boiler designed for heavy fuel oil. The project will also provide information to help in the design of new system specifically configured to fire these clean coal-based fuels. The project consists of four phases: (1) design, permitting, and test planning, (2) construction and start up, (3) demonstration and evaluation (1,000-hour demonstration), and (4) expanded demonstration and evaluation (installing a CWSF preparation circuit, conducting an additional 1,000 hours of testing, and installing an advanced flue gas treatment system). The boiler testing and evaluation will determine if the CWSF combustion characteristics, heat release rate, fouling and slagging behavior, corrosion and erosion tendencies, and fuel transport, storage, and handling characteristics can be accommodated in a boiler system designed to fire heavy fuel oil. In addition, the proof-of-concept demonstration will generate data to determine how the properties of a CWSF and its parent coal affect boiler performance. The economic factors associated with retrofitting boilers will also be evaluated. During this reporting period, the construction of the …
Date: November 30, 1994
Creator: Miller, Bruce G. & Scaroni, Alan W.
Object Type: Report
System: The UNT Digital Library
The development of coal-based technologies for Department of Defense facilities. Semiannual technical progress report, September 28, 1993--March 27, 1994 (open access)

The development of coal-based technologies for Department of Defense facilities. Semiannual technical progress report, September 28, 1993--March 27, 1994

The U.S. Department of Defense (DOD), through an Interagency Agreement with the U.S. Department of Energy (DOE), has initiated a three-phase program with the Consortium for Coal-Water Slurry Fuel Technology, with the aim of decreasing DOD`s reliance on imported oil by increasing its use of coal. The program is being conducted as a cooperative agreement between the Consortium and DOE and the first two phases of the program are underway. To achieve the objectives of the program, a team of researchers was assembled. Phase I activities are focused on developing clean, coal-based combustion technologies for the utilization of both micronized coal-water slurry fuels (MCWSFS) and dry, micronized coal (DMC) in fuel oil-designed industrial boilers. Phase II research and development activities will continue to focus on industrial boiler retrofit technologies by addressing emissions control and precombustion (i.e., slagging combustion and/or gasification) strategies for the utilization of high ash, high sulfur coals. Phase III activities will examine coal-based fuel combustion systems that cofire wastes. Each phase includes an engineering cost analysis and technology assessment. The activities and status of Phases I and II are described below. The objective in Phase I is to deliver fully engineered retrofit options for a fuel oil-designed …
Date: November 30, 1994
Creator: Miller, B. G.; Morrison, J. L.; Sharifi, R.; Shepard, J. F.; Scaroni, A. W.; Hogg, R. et al.
Object Type: Report
System: The UNT Digital Library
Fluidized-bed copper oxide process. Phase IV. Conceptual design and economic evaluation, Volume I. Final report (open access)

Fluidized-bed copper oxide process. Phase IV. Conceptual design and economic evaluation, Volume I. Final report

Universal Oil Products, Inc. (UOP) of Des Plaines, Illinois has contracted A.E. Roberts & Associates, Inc. (AERA) of Atlanta, Georgia to prepare a sensitivity analysis for the development of the Fluidized-bed Copper Oxide (FBCO) process. As proposed by AERA in September 1991, development of the FBCO process design for a 500 mega-watt (MW) unit was divided into three tasks: (1) Establishment of a Conceptual Design, (2) Conceptual Design, (3) Cost Analysis Task 1 determined the basis for a conceptual design for the 500 megawatt (MW) FBCO process. It was completed by AERA in September of 1992, and a report was submitted at that time {open_quotes}Establishment of the Design Basis for Application to a 500 MW Coal-fired Facility.{close_quotes} Task 2 gathered all pertinent data available to date and reviewed its applicability to the 500 MW FBCO process. Work on this task was carried out on a joint basis by the AERA team members: Roberts & Schaefers worked on the dense phase transport aspect of the design; Cornell and Carnegie Mellon Universities worked on the design kinetics and modeling; and AERA contributed commercial power and combustion experience. Task 3 provides budgetary cost estimates for the FBCO process and competing alternative technologies for …
Date: November 30, 1994
Creator: unknown
Object Type: Report
System: The UNT Digital Library
A Generic Device Description Scheme Using a Relational Database (open access)

A Generic Device Description Scheme Using a Relational Database

None
Date: November 30, 1994
Creator: Satogata, T.
Object Type: Report
System: The UNT Digital Library
Geophysical survey for proposed borehole 199-K-107A, 100-K Area (open access)

Geophysical survey for proposed borehole 199-K-107A, 100-K Area

The objective of the survey was to locate subsurface obstructions that may affect the drilling of proposed borehole, 199-K-107A, located about 100 ft northwest of the 105 KW Building, 100-K Area. Based upon the results of the survey, possible drill sites within the zone, with the least likelihood of encountering identified obstructions, were identified. The ground-penetrating radar (GPR) system used for this work utilized a 300-megahertz antenna to transmit the electromagnetic (EM) energy into the ground. The transmitted energy is reflected back to a receiving antenna where variations in the return signal are recorded. Common reflectors include natural geologic conditions such as bedding, cementation, moisture, and clay, or man-made objects such as pipes, barrels, foundations, and buried wires. Several isolated anomalies, at various depths, are observed in the data. Additionally, two areas that appear disturbed, with perplexing character, are plotted. Because of the uncertain nature of these two areas, they were avoided when recommending a borehole location. Initially, the proposed borehole was staked at N130/E122. The new proposed borehole location is N139/E176. This location appears free of anomalies and is over 10 ft from interpreted linear anomalies/pipe-like features.
Date: November 30, 1994
Creator: Mitchell, T. H.
Object Type: Report
System: The UNT Digital Library
Guide for preparing and maintaining generator group pollution prevention program documentation. Revision 2 (open access)

Guide for preparing and maintaining generator group pollution prevention program documentation. Revision 2

The Hanford Pollution Prevention (P2) program is an organized, comprehensive, and continual effort to: systematically reduce the quantity and toxicity of hazardous, radioactive, mixed, and sanitary wastes; conserve resources; and prevent or minimize pollutant releases to all environmental media from all Hanford Site activities. The program has been developed to meet waste minimization and pollution Prevention public law requirements, federal and state regulations, and US Department of Energy (DOE) requirements. The Hanford P2 program is implemented through the sitewide, contractor, and generator group programs.
Date: November 30, 1994
Creator: Floyd, B. C.
Object Type: Report
System: The UNT Digital Library
Integrated beta and gamma radiation dose calculations for the ferrocyanide waste tanks (open access)

Integrated beta and gamma radiation dose calculations for the ferrocyanide waste tanks

This report contains the total integrated beta and gamma radiation doses in all the ferrocyanide waste tanks. It also contains estimated gamma radiation dose rates for all single-shell waste tanks containing a liquid observation well.
Date: November 30, 1994
Creator: Parra, S. A.
Object Type: Report
System: The UNT Digital Library
Isotope Production and Distribution Program. Financial statements, September 30, 1994 and 1993 (open access)

Isotope Production and Distribution Program. Financial statements, September 30, 1994 and 1993

The attached report presents the results of the independent certified public accountants` audit of the Isotope Production and Distribution (IP&D) Program`s financial statements as of September 30, 1994. The auditors have expressed an unqualified opinion on IP&D`s 1994 statements. Their reports on IP&D`s internal control structure and on compliance with laws,and regulations are also provided. The charter of the Isotope Program covers the production and sale of radioactive and stable isotopes, byproducts, and related isotope services. Prior to October 1, 1989, the Program was subsidized by the Department of Energy through a combination of appropriated funds and isotope sales revenue. The Fiscal Year 1990 Appropriations Act, Public Law 101-101, authorized a separate Isotope Revolving Fund account for the Program, which was to support itself solely from the proceeds of isotope sales. The initial capitalization was about $16 million plus the value of the isotope assets in inventory or on loan for research and the unexpended appropriation available at the close of FY 1989. During late FY 1994, Public Law 103--316 restructured the Program to provide for supplemental appropriations to cover costs which are impractical to incorporate into the selling price of isotopes. Additional information about the Program is provided in …
Date: November 30, 1994
Creator: Marwick, P.
Object Type: Report
System: The UNT Digital Library
The land component of the global climate system with adequate spatial resolution. Final report, September 1, 1991--August 31, 1994 (open access)

The land component of the global climate system with adequate spatial resolution. Final report, September 1, 1991--August 31, 1994

The focus of the work done under this grant has been to couple global circulation models (in particular, the National Center for Atmospheric Research (NCAR) Community Climate Model Version 2 (CCM2)) to a land-surface model at a much finer mesh than that used for the atmospheric processes. The end objective has been to incorporate into the CHAMMP modeling system a state-of-the-art land model on a mesh independent of the atmospheric model resolution. Efforts have emphasized the following: development and graphical displays of the fine-mesh land surface boundary conditions; the data structures required to carry out integrations on the land fine-mesh; the physical parameterization required to diaggregate model precipitation; analyses of the NCAR 10-year control simulation of the frozen version of CM2/BATS; implementation of changes in the cloud optical properties to mitgate excess incident solar radiation and temperatures over middle latitudes in the Northern Hemisphere summer; prototype development of the CCM2/BASTS fine-mesh treatment.
Date: November 30, 1994
Creator: Dickinson, R. E.; Hahmann, A. N.; Zeng, X.; Chen, M.; Vaughan, J. & Auvine, B. A.
Object Type: Report
System: The UNT Digital Library
Mixed wasted integrated program: Logic diagram (open access)

Mixed wasted integrated program: Logic diagram

The Mixed Waste Integrated Program Logic Diagram was developed to provide technical alternative for mixed wastes projects for the Office of Technology Development`s Mixed Waste Integrated Program (MWIP). Technical solutions in the areas of characterization, treatment, and disposal were matched to a select number of US Department of Energy (DOE) treatability groups represented by waste streams found in the Mixed Waste Inventory Report (MWIR).
Date: November 30, 1994
Creator: Mayberry, J.; Stelle, S.; O`Brien, M.; Rudin, M.; Ferguson, J. & McFee, J.
Object Type: Report
System: The UNT Digital Library