25,445 Matching Results

Results open in a new window/tab.

Advanced Hydride Laboratory (open access)

Advanced Hydride Laboratory

The Replacement Tritium Facility (RTF) is a $140 million reservoir loading and unloading facility using state-of-the-art technology, scheduled for completion in 1990 and startup in 1991. In the RTF, metal hydride technology will be used to store, separate, purify, pump, and compress hydrogen isotopes. In support of the RTF, a $3.2 million ``cold`` process demonstration facility began operation in November, 1987. The purpose of the Advanced Hydride Laboratory (AHL) is to demonstrate the RFT`s metal hydride technology by integrating the various unit operations into an overall process. While much of the RTF`s metal hydride technology had been demonstrated in laboratory bench-scale and pilot-scale units, none of the units had been operated together and integrated into an overall process.
Date: December 31, 1989
Creator: Horen, A. S.
System: The UNT Digital Library
Advanced Hydride Laboratory (open access)

Advanced Hydride Laboratory

Metal hydrides have been used at the Savannah River Tritium Facilities since 1984. However, the most extensive application of metal hydride technology at the Savannah River Site is being planned for the Replacement Tritium Facility, a $140 million facility schedules for completion in 1990 and startup in 1991. In the new facility, metal hydride technology will be used to store, separate, isotopically purify, pump, and compress hydrogen isotopes. In support of the Replacement Tritium Facility, a $3.2 million, ``cold,`` process demonstration facility, the Advanced Hydride Laboratory began operation in November of 1987. The purpose of the Advanced Hydride Laboratory is to demonstrate the Replacement Tritium Facility`s metal hydride technology by integrating the various unit operations into an overall process. This paper will describe the Advanced Hydride Laboratory, its role and its impact on the application of metal hydride technology to tritium handling.
Date: December 31, 1989
Creator: Motyka, T.
System: The UNT Digital Library
Analysis of natural convection in a waste glass melter (open access)

Analysis of natural convection in a waste glass melter

Laminar natural convection is a two-dimensional cavity with a line heat sink at the top boundary is investigated numerically. The fluid in the cavity is a high Prandtl number fluid with volumetric heat source. Parametric study is conducted to find the effect of variations in Rayleigh number, aspect ratio, sink location, and volumetric heat source on the flow and temperature field. 5 refs.
Date: December 31, 1989
Creator: Choi, Inn Gui
System: The UNT Digital Library
Background modelling in Rietveld analysis (open access)

Background modelling in Rietveld analysis

The Rietveld method is a complete profile fitting technique, which requires modelling the total scattering from crystalline samples. Many diffraction experiments involve the analysis of scattering patterns containing additional noncrystalline scattering components; these components are broad oscillations superimposed on the sharp Bragg pattern. Conventional background functions cannot be used for the noncrystalline scattering; but treating the additional scattering as though it were from an amorphous material can provide additional structural information. This is demonstrated using AlPO{sub 4}-5, an aluminophosphate framework molecular sieve. The correlation function for the amorphous component has peaks close to interatomic distances also characteristic of the crystal. The cose agreement suggests that the amorphous component, although lacking long-range periodicity, has a similar atomic arrangement to the crystal. A calibration experiment is performed using a 50-50 wt% quartz-amorphous silica mixture; the crystal structural parameters obtained from Fourier-filtered data are compared with neutron powder diffraction refinement of quartz and single-crystal x-ray results. All refined parameters agree within 3-4 {sigma}. 2 tables, 5 refs, 6 figs. (DLC)
Date: December 31, 1989
Creator: Richardson, J. W. Jr.
System: The UNT Digital Library
Burning of a spherical fuel droplet in a uniform subsonic flowfield (open access)

Burning of a spherical fuel droplet in a uniform subsonic flowfield

An analytical/numerical model is described for the evaporation and burning of a spherical fuel droplet in a subsonic crossflow. The external gaseous flowfield is represented using an approximate compressible potential solution, while the internal flowfield of the droplet is represented by the classical Hill`s spherical vortex. This allows numerical solution for the external boundary layer and diffusion flame characteristics to be made, from which the droplet`s effective drag coefficient, rate of mass loss, size, and flame shape are determined. Comparison with experimental data indicate good agreement, and thus the potential for such simplified models in performing parametric studies.
Date: December 31, 1989
Creator: Madooglu, K. & Karagozian, A. R.
System: The UNT Digital Library
Characterization of liquid-water percolation in tuffs in the unsaturated zone, Yucca Mountain, Nye County, Nevada (open access)

Characterization of liquid-water percolation in tuffs in the unsaturated zone, Yucca Mountain, Nye County, Nevada

A surface-based borehole investigation currently (1989) is being done to characterize liquid-water percolation in tuffs of Miocene age in the unsaturated zone beneath Yucca Mountain, Nye County, Nevada Active in-situ testing and passive in-situ monitoring will be used in this investigation to estimate the present-day liquid-water percolation (flux). The unsaturated zone consists of a gently dipping sequence of fine-grained, densely fractured, and mostly welded ash-flow tuffs that are interbedded with fine-grained, slightly fractured, non-welded ash-flow and ash-fall tuffs that are partly vitric and zeolitized near the water table. Primary study objectives are to define the water potential field within the unsaturated zone and to determine the in-situ bulk permeability and bulk hydrologic properties of the unsaturated tuffs. Borehole testing will be done to determine the magnitude and spatial distribution of physical and hydrologic properties of the geohydrologic units, and of their water potential fields. The study area of this investigation is restricted to that part of Yucca Mountain that immediately overlies and is within the boundaries of the perimeter drift of a US Department of Energy proposed mined, geologic, high-level radioactive-waste repository. Vertically, the study area extends from near the surface of Yucca Mountain to the underlying water table, about …
Date: December 31, 1989
Creator: Kume, J. & Rousseau, J.P.
System: The UNT Digital Library
Comparison of the Layer Structure of Vapor Phase and Leached SRL Glass by Use of AEM [Analytical Electron Microscopy] (open access)

Comparison of the Layer Structure of Vapor Phase and Leached SRL Glass by Use of AEM [Analytical Electron Microscopy]

Test samples of 131 type glass that have been reacted for extended time periods in water vapor atmospheres of different relative humidities and in static leaching solution have been examined to characterize the reaction products. Analytical electron microscopy (AEM) was used to characterize the leached samples, and a complicated layer structure was revealed, consisting of phases that precipitate from solution and also form within the residual glass layer. The precipitated phases include birnes-site, saponite, and an iron species, while the intralayer phases include the U-Ti containing phase brannerite distributed within a matrix consisting of bands of an Fe rich montmorillonite clay. Comparison is made between samples leached at 40{degrees}C for 4 years with those leached at 90{degrees}C for 3-1/2 years. The samples reacted in water vapor were examined with scanning electron microscopy and show increasing reaction as both the relative humidity and time of reaction increases. These samples also contain a layered structure with reaction products on the glass surface. 15 refs., 5 figs.
Date: December 31, 1989
Creator: Biwer, B. M.; Bates, J. K.; Abrajano, T. A., Jr. & Bradley, J. P.
System: The UNT Digital Library
Control of DWPF melter feed composition (open access)

Control of DWPF melter feed composition

The Defense Waste Processing Facility will be used to immobilize Savannah River Site high-level waste into a stable borosilicate glass for disposal in a geologic repository. Proper control of the melter feed composition in this facility is essential to the production of glass which meets product durability constraints dictated by repository regulations and facility processing constraints dictated by melter design. A technique has been developed which utilizes glass property models to determine acceptable processing regions based on the multiple constraints imposed on the glass product and to display these regions graphically. This system along with the batch simulation of the process is being used to form the basis for the statistical process control system for the facility.
Date: December 31, 1989
Creator: Brown, K. G.; Edwards, R. E.; Postles, R. L. & Randall, C. T.
System: The UNT Digital Library
The development of early pediatric models and their application to radiation absorbed dose calculations (open access)

The development of early pediatric models and their application to radiation absorbed dose calculations

This presentation will review and describe the development of pediatric phantoms for use in radiation dose calculations . The development of pediatric models for dose calculations essentially paralleled that of the adult. In fact, Snyder and Fisher at the Oak Ridge National Laboratory reported on a series of phantoms for such calculations in 1966 about two years before the first MIRD publication on the adult human phantom. These phantoms, for a newborn, one-, five-, ten-, and fifteen-year old, were derived from the adult phantom. The ``pediatric`` models were obtained through a series of transformations applied to the major dimensions of the adult, which were specified in a Cartesian coordinate system. These phantoms suffered from the fact that no real consideration was given to the influence of these mathematical transformations on the actual organ sizes in the other models nor to the relation of the resulting organ masses to those in humans of the particular age. Later, an extensive effort was invested in designing ``individual`` pediatric phantoms for each age based upon a careful review of the literature. Unfortunately, the phantoms had limited use and only a small number of calculations were made available to the user community. Examples of the …
Date: December 31, 1989
Creator: Poston, J. W.
System: The UNT Digital Library
Environmental data management system at the Savannah River Site (open access)

Environmental data management system at the Savannah River Site

The volume and complexity of data associated with escalating environmental regulations has prompted professionals at the Savannah River Site to begin taking steps necessary to better manage environmental information. This paper describes a plan to implement an integrated environmental information system at the site. Nine topic areas have been identified. They are: administrative, air, audit & QA, chemical information/inventory, ecology, environmental education, groundwater, solid/hazardous waste, and surface water. Identification of environmental databases that currently exist, integration into a ``friendly environment,`` and development of new applications will all take place as a result of this effort. New applications recently completed include Groundwater Well Construction, NPDES (Surface Water) Discharge Monitoring, RCRA Quarterly Reporting, and Material Safety Data Sheet Information. Database applications are relational (Oracle RDBMS) and reside largely in DEC VMS environments. In today`s regulatory and litigation climate, the site recognizes they must have knowledge of accurate environmental data at the earliest possible time. Implementation of this system will help ensure this.
Date: December 31, 1989
Creator: Story, C. H. & Gordon, D. E.
System: The UNT Digital Library
The fiftieth anniversary of the first public announcement of the successful test of fission: Proceedings (open access)

The fiftieth anniversary of the first public announcement of the successful test of fission: Proceedings

This report contains comments and discussions on the history of fission. The following people comments and lectures are discussed in this report: Remarks and introduction of Maxine F. Singer; president`s message, Maxine F. Singer; introduction of Stephen Joel Trachtenberg; President`s message, Stephen Joel Trachtenberg; introduction of Frederick Seitz; lecture: ``Nuclear Science: Promises and Perceptions, `` Frederick Seitz; introduction of K. Alex Mueller; lecture: ``High Temperature Ferroelectricity and Superconductivity,`` introduction of Edward Teller; and lecture: ``Toward a More Secure World,`` Edward Teller.
Date: December 31, 1989
Creator: unknown
System: The UNT Digital Library
Flow boiling in vertical down-flow (open access)

Flow boiling in vertical down-flow

An experimental program has been conducted to investigate the onset of Ledinegg instability in vertical down-flow. For three size uniformly heated test sections with L/D ratios from 100 to 150, the pressure drop under subcooled boiling conditions has been obtained for a wide range of operating parameters. The results are presented in non-dimensional forms which correlate the important variables and provide techniques for predicting the onset of flow instability. 3 refs.
Date: December 31, 1989
Creator: Dougherty, T.; Fighetti, C.; Reddy, G.; Yang, B.; Jafri, T.; McAssey, E. et al.
System: The UNT Digital Library
Fourteenth workshop geothermal reservoir engineering: Proceedings (open access)

Fourteenth workshop geothermal reservoir engineering: Proceedings

The Fourteenth Workshop on Geothermal Reservoir Engineering was held at Stanford University on January 24--26, 1989. Major areas of discussion include: (1) well testing; (2) various field results; (3) geoscience; (4) geochemistry; (5) reinjection; (6) hot dry rock; and (7) numerical modelling. For these workshop proceedings, individual papers are processed separately for the Energy Data Base.
Date: December 31, 1989
Creator: Ramey, H. J. Jr.; Kruger, P.; Horne, R. N.; Miller, F. G.; Brigham, W. E. & Cook, J. W.
System: The UNT Digital Library
Genome sequencing by direct imaging x-ray color holography. Appendix A (open access)

Genome sequencing by direct imaging x-ray color holography. Appendix A

Currently available techniques for sequencing DNA are inadequate for oligonucleotides of length greater than 600 nucleotides and are most effective in the 300 nucleotide range. Automated sequencers are now available which use, basically, the Sanger dideoxy termination method. The sequencing rates of these conventional methods are extremely low and involve very labor intensive procedures, requiring on the order of two man-years of effort for the determination of the sequence of a single 100 kilobase segment. Since the full human genetic complement is of vast size, representing {approximately} 3 {times} 10{sup 9} bases, a fast and accurate method for DNA sequencing is needed. Therefore, we set as a goal a sequencing rate in the range of {approximately} 10{sup 2} bp/s with an accuracy of {approximately} 1 error per 10{sup 6} bases, a value exceeding that set by the fidelity of current enzymatic processes. These values would permit the accurate determination of the sequence of the full human genome in one year. An approach involving rapid direct imaging of large segments of DNA is desired. A properly constructed x-ray Fourier-transform holographic microscope appears to combine these features. A basic x-ray holographic instrument has been designed. This concept, with appropriate modifications, and the …
Date: December 31, 1989
Creator: Haddad, W.; Boyer, K.; Solem, J. C.; Rhodes, C. K. & Moriarty, R. M.
System: The UNT Digital Library
A hierarachical data structure representation for fusing multisensor information (open access)

A hierarachical data structure representation for fusing multisensor information

A major problem with MultiSensor Information Fusion (MSIF) is establishing the level of processing at which information should be fused. Current methodologies, whether based on fusion at the data element, segment/feature, or symbolic levels, are each inadequate for robust MSIF. Data-element fusion has problems with coregistration. Attempts to fuse information using the features of segmented data relies on a Presumed similarity between the segmentation characteristics of each data stream. Symbolic-level fusion requires too much advance processing (including object identification) to be useful. MSIF systems need to operate in real-time, must perform fusion using a variety of sensor types, and should be effective across a wide range of operating conditions or deployment environments. We address this problem through developing a new representation level which facilitates matching and information fusion. The Hierarchical Data Structure (HDS) representation, created using a multilayer, cooperative/competitive neural network, meets this need. The HDS is an intermediate representation between the raw or smoothed data stream and symbolic interpretation of the data. it represents the structural organization of the data. Fused HDSs will incorporate information from multiple sensors. Their knowledge-rich structure aids top-down scene interpretation via both model matching and knowledge-based region interpretation.
Date: December 31, 1989
Creator: Maren, A. J.; Pap, R. M. & Harston, C. T.
System: The UNT Digital Library
A hierarchical structure approach to MultiSensor Information Fusion (open access)

A hierarchical structure approach to MultiSensor Information Fusion

A major problem with image-based MultiSensor Information Fusion (MSIF) is establishing the level of processing at which information should be fused. Current methodologies, whether based on fusion at the pixel, segment/feature, or symbolic levels, are each inadequate for robust MSIF. Pixel-level fusion has problems with coregistration of the images or data. Attempts to fuse information using the features of segmented images or data relies an a presumed similarity between the segmentation characteristics of each image or data stream. Symbolic-level fusion requires too much advance processing to be useful, as we have seen in automatic target recognition tasks. Image-based MSIF systems need to operate in real-time, must perform fusion using a variety of sensor types, and should be effective across a wide range of operating conditions or deployment environments. We address this problem through developing a new representation level which facilitates matching and information fusion. The Hierarchical Scene Structure (HSS) representation, created using a multilayer, cooperative/competitive neural network, meets this need. The MSS is intermediate between a pixel-based representation and a scene interpretation representation, and represents the perceptual organization of an image. Fused HSSs will incorporate information from multiple sensors. Their knowledge-rich structure aids top-down scene interpretation via both model matching …
Date: December 31, 1989
Creator: Maren, A. J.; Pap, R. M. & Harston, C. T.
System: The UNT Digital Library
An introduction to geographic information systems as applied to a groundwater remediation program (open access)

An introduction to geographic information systems as applied to a groundwater remediation program

While the attention to environmental issues has grown over the past several years, so has the focus on groundwater protection. Addressing the task of groundwater remediation often involves a large-scale program with numerous wells and enormous amounts of data. This data must be manipulated and analyzed in an efficient manner for the remediation program to be truly effective. Geographic Information System`s (GIS) have proven to be an extremely effective tool in handling and interpreting this type of groundwater information. The purpose of this paper is to introduce the audience to GIS technology, describe how it is being used at the Savannah River Site (SRS) to handle groundwater data and demonstrate how it may be used in the corporate Westinghouse environment.
Date: December 31, 1989
Creator: Hammock, J. K. & Lorenz, R.
System: The UNT Digital Library
Magnetic characteristics and measurements of filamentary Nb-Ti wire for the Superconducting Super Collider (open access)

Magnetic characteristics and measurements of filamentary Nb-Ti wire for the Superconducting Super Collider

In synchrotron accelerator applications, such as the Superconducting Super Collider (SSC), superconducting magnets are cycled in magnetic field. Desirable properties of the magnets include field uniformity, field stability with time, small residual field, and fairly small energy losses upon cycling. This paper discusses potential sources of problems in achieving these goals, describes important magnetic characteristics to be considered, and reviews measurement techniques for magnetic evaluation of candidate SSC wires. Instrumentation that might be practical for use in a wire-fabrication environment is described. The authors report on magnetic measurements of prototype SSC wires and cables and speculate on causes for instability in multipole fields of dipole magnets constructed with such cables.
Date: December 31, 1989
Creator: Goldfarb, R. B. & Spomer, R. L.
System: The UNT Digital Library
Magnetic resonance as a structural probe of a uranium (VI) sol-gel process (open access)

Magnetic resonance as a structural probe of a uranium (VI) sol-gel process

NMR investigations on the ORNL process for sol-gel synthesis of microspherical nuclear fuel (UO{sub 2}), has been useful in sorting out the chemical mechanism in the sol-gel steps. {sup 13}C, {sup 15}N, and {sup 1}H NMR studies on the HMTA gelation agent (Hexamethylene tetramine, C{sub 6}H{sub l2}N{sub 4}) has revealed near quantitative stability of this adamantane-like compound in the sol-Gel process, contrary to its historical role as an ammonia source for gelation from the worldwide technical literature. {sub 17}0 NMR of uranyl (UO{sub 2}{sup ++}) hydrolysis fragments produced in colloidal sols has revealed the selective formation of a uranyl trimer, [(UO{sub 2}){sub 3}({mu}{sub 3}-O)({mu}{sub 2}-OH){sub 3}]{sup +}, induced by basic hydrolysis with the HMTA gelation agent. Spectroscopic results show that trimer condensation occurs during sol-gel processing leading to layered polyanionic hydrous uranium oxides in which HMTAH{sup +} is occluded as an ``intercalation`` cation. Subsequent sol-gel processing of microspheres by ammonia washing results in in-situ ion exchange and formation of a layered hydrous ammonium uranate with a proposed structural formula of (NH{sub 4}){sub 2}[(UO{sub 2}){sub 8}O{sub 4}(OH){sub 10}] {center_dot} 8H{sub 2}0. This compound is the precursor to sintered U0{sub 2} ceramic fuel.
Date: December 31, 1989
Creator: King, C. M.; Thompson, M. C.; Buchanan, B. R.; King, R. B. & Garber, A. R.
System: The UNT Digital Library
MIIT: International in-situ testing of simulated HLW forms--preliminary analyses of SRL 165/TDS waste glass and metal systems (open access)

MIIT: International in-situ testing of simulated HLW forms--preliminary analyses of SRL 165/TDS waste glass and metal systems

The first in-situ tests involving burial of simulated high-level waste (HLW) forms conducted in the United States were started on July 22, 1986. This effort, called the Materials Interface Interactions Tests (MIIT), comprises the largest, most cooperative field testing venture in the international waste management community. Included in the study are over 900 waste form samples comprising 15 different systems supplied by seven countries. Also included are almost 300 potential canister or overpack metal samples of 11 different metals along with more than 500 geologic and backfill specimens. There are a total of 1926 relevant interactions that characterize this effort which is being conducted in the bedded salt site at the Waste Isolation Pilot Plant (WIPP), near Carlsbad, New Mexico.
Date: December 31, 1989
Creator: Wicks, G. G.; Lodding, A. R.; Macedo, P. B.; Clark, D. E. & Molecke, M. A.
System: The UNT Digital Library
Monitoring seasonal and annual wetland changes in a freshwater marsh with SPOT HRV data (open access)

Monitoring seasonal and annual wetland changes in a freshwater marsh with SPOT HRV data

Eleven dates of SPOT HRV data along with near-concurrent vertical aerial photographic and phenological data for 1987, 1988, and 1989 were evaluated to determine seasonal and annual changes in a 400-hectare, southeastern freshwater marsh. Early April through mid-May was the best time to discriminate among the cypress (Taxodium distichum)/water tupelo (Nyssa acquatica) swamp forest and the non-persistent (Ludwigia spp.) and persistent (Typha spp.) stands in this wetlands. Furthermore, a ten-fold decrease in flow rate from 11 cubic meters per sec (cms) in 1987 to one cms in 1988 was recorded in the marsh followed by a shift to drier wetland communities. The Savannah River Site (SRS), maintained by the US Department of Energy, is a 777 km{sup 2} area located in south central South Carolina. Five tributaries of the Savannah River run southwest through the SRS and into the floodplain swamp of the Savannah River. This paper describes the use of SPOT HRV data to monitor seasonal and annual trends in one of these swamp deltas, Pen Branch Delta, during a three-year period, 1987--1989.
Date: December 31, 1989
Creator: Mackey, H. E., Jr.
System: The UNT Digital Library
Oxygen-17 NMR studies on uranium (VI) hydrolysis and gelation (open access)

Oxygen-17 NMR studies on uranium (VI) hydrolysis and gelation

Hydrolysis and gelation processes in uranyl solutions are observed using the strong sharp uranyl oxygen-17 resonance. The ability to follow the hydrolysis of uranyl salts by observation of the sharp uranyl oxygen-17 resonance provides a clear indication of the dependence of uranyl hydrolysis on the counteranion (nitrate versus chloride) but not on the means of introducing hydroxide into the solution (Me{sub 4}NOH versus R{sub 3}N extraction). In addition, two different pathways for gelation are suggested. In the first pathway the uranyl hydrolysis is conducted with a base (HMTA in these studies) which preferentially forms trimeric (UO{sub 2}){sub 3} ({mu}{sub 3}-O) units which can then condense into the polymeric UO{sub 2}O{sub 6/3} layers of a gel based on the hexagonal structure of {proportional_to}UO{sub 2}(OH){sub 2}. In the second gelation pathway a uranyl derivative is treated with excess hydroxide in the absence of a metal or hydrogen-bonding ammonium cations which form insoluble solids uranates. Consensation of the resulting solution of soluble UO{sub 2}(OH)n{sup 2-n} anions can then lead to a similar polymer UO{sub 2}O{sub 4/2} or UO{sub 2}O{sub 6/3} structure of a gel. 9 refs., 2 figs.
Date: December 31, 1989
Creator: King, R. B.; King, C. M. & Garber, A. R.
System: The UNT Digital Library
Parallel computing: One opportunity, four challenges (open access)

Parallel computing: One opportunity, four challenges

The author reviews briefly the area of parallel computer processing. This area has been expanding at a great rate in the past decade. Great strides have been made in the hardware area, and in the speed of performance of chips. However to some degree the hardware area is beginning to run into basic physical speed limits, which will slow the rate of advance of this area simply because of physical limitations. The author looks at ways that computer architecture, and software applications, can work to continue the rate of increase in computing power which has occurred over the past decade. Four particular areas are mentioned: programmability; communication network design; reliable operation; performance evaluation and benchmarking.
Date: December 31, 1989
Creator: Gaudiot, J.-L.
System: The UNT Digital Library
A parallel multigrid method for data-driven multiprocessor systems (open access)

A parallel multigrid method for data-driven multiprocessor systems

The multigrid algorithm (MG) is recognized as an efficient and rapidly converging method to solve a wide family of partial differential equations (PDE). When this method is implemented on a multiprocessor system, its major drawback is the low utilization of processors. Due to the sequentiality of the standard algorithm, the fine grid levels cannot start relaxation until the coarse grid levels complete their own relaxation. Indeed, of all processors active on the fine two dimensional grid level only one fourth will be active at the coarse grid level, leaving full 75% idle. In this paper, a novel parallel V-cycle multigrid (PVM) algorithm is proposed to cure the idle processors` problem. Highly programmable systems such as data-flow architectures are then applied to support this new algorithm. The experiments based on the proposed architecture show that the convergence rate of the new algorithm is about twice faster than that of the standard method and twice as efficient system utilization is achieved.
Date: December 31, 1989
Creator: Lin, C. H.; Gaudiot, J. L. & Proskurowski, W.
System: The UNT Digital Library