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Two-stage Framework for a Topology-Based Projection and Visualization of Classified Document Collections

Description: During the last decades, electronic textual information has become the world's largest and most important information source available. People have added a variety of daily newspapers, books, scientific and governmental publications, blogs and private messages to this wellspring of endless information and knowledge. Since neither the existing nor the new information can be read in its entirety, computers are used to extract and visualize meaningful or interesting topics and documents from this huge information clutter. In this paper, we extend, improve and combine existing individual approaches into an overall framework that supports topological analysis of high dimensional document point clouds given by the well-known tf-idf document-term weighting method. We show that traditional distance-based approaches fail in very high dimensional spaces, and we describe an improved two-stage method for topology-based projections from the original high dimensional information space to both two dimensional (2-D) and three dimensional (3-D) visualizations. To show the accuracy and usability of this framework, we compare it to methods introduced recently and apply it to complex document and patent collections.
Date: July 19, 2010
Creator: Oesterling, Patrick; Scheuermann, Gerik; Teresniak, Sven; Heyer, Gerhard; Koch, Steffen; Ertl, Thomas et al.
Partner: UNT Libraries Government Documents Department

Modeling Renewable Penetration Using a Network Economic Model

Description: This paper evaluates the accuracy of a network economic modeling approach in designing energy systems having renewable and conventional generators. The network approach models the system as a network of processes such as demands, generators, markets, and resources. The model reaches a solution by exchanging prices and quantity information between the nodes of the system. This formulation is very flexible and takes very little time to build and modify models. This paper reports an experiment designing a system with photovoltaic and base and peak fossil generators. The level of PV penetration as a function of its price and the capacities of the fossil generators were determined using the network approach and using an exact, analytic approach. It is found that the two methods agree very closely in terms of the optimal capacities and are nearly identical in terms of annual system costs.
Date: March 6, 2001
Creator: Lamont, A.
Partner: UNT Libraries Government Documents Department

On Issues of Precision for Hardware-based Volume Visualization

Description: This paper discusses issues with the limited precision of hardware-based volume visualization. We will describe the compositing OVER operator and how fixed-point arithmetic affects it. We propose two techniques to improve the precision of fixed-point compositing and the accuracy of hardware-based volume visualization. The first technique is to perform dithering of color and alpha values. The second technique we call exponent-factoring, and captures significantly more numeric resolution than dithering, but can only produce monochromatic images.
Date: April 11, 2003
Creator: LaMar, E C
Partner: UNT Libraries Government Documents Department

Long-Range Corrected Hybrid Density Functionals with Damped Atom-Atom Dispersion Corrections

Description: We report re-optimization of a recently proposed long-range corrected (LC) hybrid density functionals [J.-D. Chai and M. Head-Gordon, J. Chem. Phys. 128, 084106 (2008)] to include empirical atom-atom dispersion corrections. The resulting functional, {omega}B97X-D yields satisfactory accuracy for thermochemistry, kinetics, and non-covalent interactions. Tests show that for non-covalent systems, {omega}B97X-D shows slight improvement over other empirical dispersion-corrected density functionals, while for covalent systems and kinetics, it performs noticeably better. Relative to our previous functionals, such as {omega}B97X, the new functional is significantly superior for non-bonded interactions, and very similar in performance for bonded interactions.
Date: June 14, 2008
Creator: Chai, Jeng-Da & Head-Gordon, Martin
Partner: UNT Libraries Government Documents Department

Basis for dose rate to curie assay method

Description: Disposition of low-level solid waste packages at the Hanford Site requires quantifying the radioactive contents of each container. This study generated conversion factors to apply to the results of contact surveys that are performed with standard dose rate survey instruments by field health physics technicians. This study determined the accuracy of this method, and identified the major sources of uncertainty. It is concluded that the dominant error is associated with the possibility that the radioactive source is not homogeneously distributed.
Date: October 31, 1996
Creator: Gedeon, S.R.
Partner: UNT Libraries Government Documents Department

Coupling Through Tortuous Path Narrow Slot Apertures into Complex Cavitivies

Description: A hybrid FEM/MoM model has been implemented to compute the coupling of fields into a cavity through narrow slot apertures having depth. The model utilizes the slot model of Warne and Chen [23]-[29] which takes into account the depth of the slot, wall losses, and inhomogeneous dielectrics in the slot region. The cavity interior is modeled with the mixed-order, covariant-projection hexahedral elements of Crowley [32]. Results are given showing the accuracy and generality of the method for modeling geometrically complex slot-cavity combinations.
Date: July 26, 1999
Creator: Jedlicka, Russell P.; Castillo, Steven P. & Warne, Larry K.
Partner: UNT Libraries Government Documents Department

Advanced Lost Foam Casting Technology - Phase V

Description: Previous research, conducted under DOE Contracts DE-FC07-89ID12869, DE-FC07-93ID12230 and DE-FC07-95ID113358 made significant advances in understanding the Lost Foam Casting (LFC) Process and clearly identified areas where additional developments were needed to improve the process and make it more functional in industrial environments. The current project focused on eight tasks listed as follows: Task 1--Computational Model for the Process and Data Base to Support the Model; Task 2--Casting Dimensional Accuracy; Task 3--Pattern Production; Task 4--Improved Pattern Materials; Task 5--Coating Control; Task 6--In-Plant Case Studies; Task 7--Energy and the Environmental Data; and Task 8--Technology Transfer. This report summarizes the work done on all tasks in the period of October 1, 1999 through September 30, 2004. The results obtained in each task and subtask are summarized in this Executive Summary and details are provided in subsequent sections of the report.
Date: April 29, 2004
Creator: Sun, Wanliang; Littleton, Harry E. & Bates, Charles E.
Partner: UNT Libraries Government Documents Department

Development of millimeter-wave accelerating structures using precision metal forming technology

Description: High gradients in radio-frequency (RF) driven accelerators require short wavelengths that have the concomitant requirements of small feature size and high tolerances, 1-2 {micro}m for millimeter wavelengths. Precision metal-forming stampling has the promise of meeting those tolerances with high production rates. This STI will evaluate that promise.
Date: June 3, 2003
Partner: UNT Libraries Government Documents Department

The effect of stick-force gradient and stick gearing on the tracking accuracy of a fighter airplane

Description: Report presenting steady straight-and-level and steady turning tracking runs against an aerial target using an F-51H airplane equipped with a fixed optical sight and with various combinations of maneuvering stick-force and stick-deflection gradients. Results regarding aim wander, elevator movement, and stick-force variation for various test conditions are provided.
Date: December 17, 1954
Creator: Abramovitz, Marvin & Van Dyke, Rudolph D., Jr.
Partner: UNT Libraries Government Documents Department

Citation Accuracy in the Journal Literature of Four Disciplines : Chemistry, Psychology, Library Science, and English and American Literature

Description: The primary purpose of this study was to determine if there is a relationship between the bibliographic citation practices of the members of a discipline and the emphasis placed on citation accuracy and purposes in the graduate instruction of the discipline.
Date: May 1992
Creator: Sassen, Catherine J. (Catherine Jean)
Partner: UNT Libraries

Computation of Confidence Limits for Linear Functions of the Normal Mean and Variance

Description: A program is described that calculates exact and optimal (uniformly most accurate unbiased) confidence limits for linear functions of the normal mean and variance. The program can therefore also be used to calculate confidence limits for monotone transformations of such functions (e.g., lognormal means). The accuracy of the program has been thoroughly evaluated in terms of coverage probabilities for a wide range of parameter values.
Date: September 1, 1999
Creator: Land, C.E. & Lyon, B.F.
Partner: UNT Libraries Government Documents Department

The BBP Algorithm for Pi

Description: The 'Bailey-Borwein-Plouffe' (BBP) algorithm for {pi} is based on the BBP formula for {pi}, which was discovered in 1995 and published in 1996 [3]: {pi} = {summation}{sub k=0}{sup {infinity}} 1/16{sup k} (4/8k+1 - 2/8k+4 - 1/8k+5 - 1/8k+6). This formula as it stands permits {pi} to be computed fairly rapidly to any given precision (although it is not as efficient for that purpose as some other formulas that are now known [4, pg. 108-112]). But its remarkable property is that it permits one to calculate (after a fairly simple manipulation) hexadecimal or binary digits of {pi} beginning at an arbitrary starting position. For example, ten hexadecimal digits {pi} beginning at position one million can be computed in only five seconds on a 2006-era personal computer. The formula itself was found by a computer program, and almost certainly constitutes the first instance of a computer program finding a significant new formula for {pi}. It turns out that the existence of this formula has implications for the long-standing unsolved question of whether {pi} is normal to commonly used number bases (a real number x is said to be b-normal if every m-long string of digits in the base-b expansion appears, in the limit, with frequency b{sup -m}). Extending this line of reasoning recently yielded a proof of normality for class of explicit real numbers (although not yet including {pi}) [4, pg. 148-156].
Date: September 17, 2006
Creator: Bailey, David H.
Partner: UNT Libraries Government Documents Department

Thin Silicon MEMS Contact-Stress Sensor

Description: This thin, MEMS contact-stress sensor continuously and accurately measures time-varying, solid interface loads over tens of thousands of load cycles. The contact-stress sensor is extremely thin (150 {mu}m) and has a linear output with an accuracy of {+-} 1.5% FSO.
Date: May 28, 2010
Creator: Kotovksy, J; Tooker, A & Horsley, D
Partner: UNT Libraries Government Documents Department

FY04 Engineering Technology Reports Technology Base

Description: Lawrence Livermore National Laboratory's Engineering Directorate has two primary discretionary avenues for its investment in technologies: the Laboratory Directed Research and Development (LDRD) program and the ''Tech Base'' program. This volume summarizes progress on the projects funded for technology-base efforts in FY2004. The Engineering Technical Reports exemplify Engineering's more than 50-year history of researching and developing (LDRD), and reducing to practice (technology-base) the engineering technologies needed to support the Laboratory's missions. Engineering has been a partner in every major program and project at the Laboratory throughout its existence, and has prepared for this role with a skilled workforce and technical resources. This accomplishment is well summarized by Engineering's mission: ''Enable program success today and ensure the Laboratory's vitality tomorrow''. LDRD is the vehicle for creating those technologies and competencies that are cutting edge. These require a significant level of research or contain some unknown that needs to be fully understood. Tech Base is used to apply those technologies, or adapt them to a Laboratory need. The term commonly used for Tech Base projects is ''reduction to practice''. Tech Base projects effect the natural transition to reduction-to-practice of scientific or engineering methods that are well understood and established. They represent discipline-oriented, core competency activities that are multi-programmatic in application, nature, and scope. The objectives of technology-base funding include: (1) the development and enhancement of tools and processes to provide Engineering support capability, such as code maintenance and improved fabrication methods; (2) support of Engineering science and technology infrastructure, such as the installation or integration of a new capability; (3) support for technical and administrative leadership through our technology Centers; and (4) the initial scoping and exploration of selected technology areas with high strategic potential, such as assessment of university, laboratory, and industrial partnerships. Engineering's five Centers, in partnership with the Division ...
Date: January 27, 2005
Creator: Sharpe, R M
Partner: UNT Libraries Government Documents Department

Interfacial Widths of Conjugated Polymer Bilayers

Description: The interfaces of conjugated polyelectrolyte (CPE)/poly[2-methoxy-5-(2{prime}-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) bilayers cast from differential solvents are shown by resonant soft X-ray reflectivity (RSoXR) to be very smooth and sharp. The chemical interdiffusion due to casting is limited to less than 0.6 nm, and the interface created is thus nearly 'molecularly' sharp. These results demonstrate for the first time and with high precision that the nonpolar MEH-PPV layer is not much disturbed by casting the CPE layer from a polar solvent. A baseline is established for understanding the role of interfacial structure in determining the performance of CPE-based polymer light-emitting diodes. More broadly, we anticipate further applications of RSoXR as an important tool in achieving a deeper understanding of other multilayer organic optoelectronic devices, including multilayer photovoltaic devices.
Date: August 13, 2009
Creator: NCSU; Berkeley, UC; UCSB; Source, Advanced Light; Garcia, Andres; Yan, Hongping et al.
Partner: UNT Libraries Government Documents Department

Evaluation of flow capture techniques for measuring HVAC grilleairflows

Description: This paper discusses the accuracy of commercially available flow hoods for residential applications. Results of laboratory and field tests indicate these hoods can be inadequate to measure airflows in residential systems, and there can be large measurement discrepancies between different flow hoods. The errors are due to poor calibrations, sensitivity of the hoods to grille airflow non-uniformities, and flow changes from added flow resistance. It is possible to obtain reasonable results using some flow hoods if the field tests are carefully done, the grilles are appropriate, and grille location does not restrict flow hood placement. We also evaluated several simple flow capture techniques for measuring grille airflows that could be adopted by the HVAC industry and homeowners as simple diagnostics. These simple techniques can be as accurate as commercially available devices. Our test results also show that current calibration procedures for flow hoods do not account for field application problems. As a result, agencies such as ASHRAE or ASTM need to develop a new standard for flow hood calibration, along with a new measurement standard to address field use of flow capture techniques.
Date: November 1, 2002
Creator: Walker, Iain S. & Wray, Craig P.
Partner: UNT Libraries Government Documents Department

Analysis and algorithms for a regularized Cauchy problem arising from a non-linear elliptic PDE for seismic velocity estimation

Description: In the present work we derive and study a nonlinear elliptic PDE coming from the problem of estimation of sound speed inside the Earth. The physical setting of the PDE allows us to pose only a Cauchy problem, and hence is ill-posed. However we are still able to solve it numerically on a long enough time interval to be of practical use. We used two approaches. The first approach is a finite difference time-marching numerical scheme inspired by the Lax-Friedrichs method. The key features of this scheme is the Lax-Friedrichs averaging and the wide stencil in space. The second approach is a spectral Chebyshev method with truncated series. We show that our schemes work because of (1) the special input corresponding to a positive finite seismic velocity, (2) special initial conditions corresponding to the image rays, (3) the fact that our finite-difference scheme contains small error terms which damp the high harmonics; truncation of the Chebyshev series, and (4) the need to compute the solution only for a short interval of time. We test our numerical scheme on a collection of analytic examples and demonstrate a dramatic improvement in accuracy in the estimation of the sound speed inside the Earth in comparison with the conventional Dix inversion. Our test on the Marmousi example confirms the effectiveness of the proposed approach.
Date: January 1, 2009
Creator: Cameron, M.K.; Fomel, S.B. & Sethian, J.A.
Partner: UNT Libraries Government Documents Department

Experimental and model-based study of the robustness of line-edgeroughness metric extraction in the presence of noise

Description: As critical dimensions shrink, line edge and width roughness (LER and LWR) become of increasing concern. Crucial to the goal of reducing LER is its accurate characterization. LER has traditionally been represented as a single rms value. More recently the use of power spectral density (PSD), height-height correlation (HHCF), and {sigma} versus length plots has been proposed in order to extract the additional spatial descriptors of correlation length and roughness exponent. Here we perform a modeling-based noise-sensitivity study on the extraction of spatial descriptors from line-edge data as well as an experimental study of the robustness of these various descriptors using a large dataset of recent extreme-ultraviolet exposure data. The results show that in the presence of noise and in the large dataset limit, the PSD method provides higher accuracy in the extraction of the roughness exponent, whereas the HHCF method provides higher accuracy for the correlation length. On the other hand, when considering precision, the HHCF method is superior for both metrics.
Date: June 1, 2007
Creator: Naulleau, Patrick P. & Cain, Jason P.
Partner: UNT Libraries Government Documents Department

Fourth-Order Method for Numerical Integration of Age- and Size-Structured Population Models

Description: In many applications of age- and size-structured population models, there is an interest in obtaining good approximations of total population numbers rather than of their densities. Therefore, it is reasonable in such cases to solve numerically not the PDE model equations themselves, but rather their integral equivalents. For this purpose quadrature formulae are used in place of the integrals. Because quadratures can be designed with any order of accuracy, one can obtain numerical approximations of the solutions with very fast convergence. In this article, we present a general framework and a specific example of a fourth-order method based on composite Newton-Cotes quadratures for a size-structured population model.
Date: January 8, 2008
Creator: Iannelli, M; Kostova, T & Milner, F A
Partner: UNT Libraries Government Documents Department

FY06 Engineering Research and Technology Report

Description: This report summarizes the core research, development, and technology accomplishments in Lawrence Livermore National Laboratory's Engineering Directorate for FY2006. These efforts exemplify Engineering's more than 50-year history of developing and applying the technologies needed to support the Laboratory's national security missions. A partner in every major program and project at the Laboratory throughout its existence, Engineering has prepared for this role with a skilled workforce and technical resources developed through both internal and external venues. These accomplishments embody Engineering's mission: ''Enable program success today and ensure the Laboratory's vitality tomorrow''. Engineering's investment in technologies is carried out primarily through two internal programs: the Laboratory Directed Research and Development (LDRD) program and the technology base, or ''Tech Base'', program. LDRD is the vehicle for creating technologies and competencies that are cutting-edge, or require discovery-class research to be fully understood. Tech Base is used to prepare those technologies to be more broadly applicable to a variety of Laboratory needs. The term commonly used for Tech Base projects is ''reduction to practice''. Thus, LDRD reports have a strong research emphasis, while Tech Base reports document discipline-oriented, core competency activities. This report combines the LDRD and Tech Base summaries into one volume, organized into six thematic technical areas: Engineering Modeling and Simulation; Measurement Technologies; Micro/Nano-Devices and Structures; Precision Engineering; Engineering Systems for Knowledge and Inference; and Energy Manipulation.
Date: January 22, 2007
Creator: Minichino, C; Alves, S W; Anderson, A T; Bennett, C V; Brown, C G; Brown, W D et al.
Partner: UNT Libraries Government Documents Department

A comparison of drive mechanisms for precision motion controlled stages

Description: This abstract presents a comparison of two drive mechanisms, a Rohlix{reg_sign} drive and a polymer nut drive, for precision motion controlled stages. A single-axis long-range stage with a 50 mm traverse combined with a short-range stage with a 16 {micro}m traverse at a operational bandwidth of 2.2 kHz were developed to evaluate the performance of the drives. The polymer nut and Rohlix{reg_sign} drives showed 4 nm RMS and 7 nm RMS positioning capabilities respectively, with traverses of 5 mm at a maximum velocity of 0.15 mm{sup -}s{sup -1} with the short range stage operating at a 2.2 kHz bandwidth. Further results will be presented in the subsequent sections.
Date: March 22, 2006
Creator: Buice, E S; Yang, H; Otten, D; Smith, S T; Hocken, R J; Trumper, D L et al.
Partner: UNT Libraries Government Documents Department

Experimental Mathematics and Mathematical Physics

Description: One of the most effective techniques of experimental mathematics is to compute mathematical entities such as integrals, series or limits to high precision, then attempt to recognize the resulting numerical values. Recently these techniques have been applied with great success to problems in mathematical physics. Notable among these applications are the identification of some key multi-dimensional integrals that arise in Ising theory, quantum field theory and in magnetic spin theory.
Date: June 26, 2009
Creator: Bailey, David H.; Borwein, Jonathan M.; Broadhurst, David & Zudilin, Wadim
Partner: UNT Libraries Government Documents Department

Experimental computation with oscillatory integrals

Description: A previous study by one of the present authors, together with D. Borwein and I. Leonard [8], studied the asymptotic behavior of the p-norm of the sinc function: sinc(x) = (sin x)/x and along the way looked at closed forms for integer values of p. In this study we address these integrals with the tools of experimental mathematics, namely by computing their numerical values to high precision, both as a challenge in itself, and also in an attempt to recognize the numerical values as closed-form constants. With this approach, we are able to reproduce several of the results of [8] and to find new results, both numeric and analytic, that go beyond the previous study.
Date: June 26, 2009
Creator: Bailey, David H. & Borwein, Jonathan M.
Partner: UNT Libraries Government Documents Department