The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Kurt Mehlhorn - One of the best experts on this subject based on the ideXlab platform.
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geometric computing with cgal and Leda
Untitled Event, 2000Co-Authors: Kurt Mehlhorn, Stefan Schirra, Pierrejean Laurent, Paul Sablonniere, Larry L SchumakerAbstract:Abstract : Leda and CGAL are platforms for combinatorial and geometric computing. We discuss the use of Leda and CGAL for geometric computing and show that they provide a unique framework for exact efficient and convenient geometric computing.
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Leda sm extending Leda to secondary memory
Lecture Notes in Computer Science, 1999Co-Authors: Andreas Crauser, Kurt MehlhornAbstract:During the last years, many software libraries for in-core computation have been developed. Most internal memory algorithms perform very badly when used in an external memory setting. We introduce Leda-SM that extends the Leda-library [22] towards secondary memory computation. Leda-SM uses I/O-efficient algorithms and data structures that do not suffer from the so called I/O bottleneck. Leda is used for in-core computation. We explain the design of Leda-SM and report on performance results.
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ten years of Leda some thoughts
Lecture Notes in Computer Science, 1999Co-Authors: Kurt MehlhornAbstract:Stefan Naher and I started the work on Leda [LED] in the spring on 1989. Many collegues and students have contributed to the project since then. A first publication appeared in the fall of the same year [MN89]. The Ledabook [MN99] will appear in the fall of 1999 and should be available at WAE99. In my talk I will discuss how the work on Leda has changed my research perspective.
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Algorithm Engineering - Leda-SM Extending Leda to Secondary Memory
Lecture Notes in Computer Science, 1999Co-Authors: Andreas Crauser, Kurt MehlhornAbstract:During the last years, many software libraries for in-core computation have been developed. Most internal memory algorithms perform very badly when used in an external memory setting. We introduce Leda-SM that extends the Leda-library [22] towards secondary memory computation. Leda-SM uses I/O-efficient algorithms and data structures that do not suffer from the so called I/O bottleneck. Leda is used for in-core computation. We explain the design of Leda-SM and report on performance results.
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the Leda platform of combinatorial and geometric computing
International Colloquium on Automata Languages and Programming, 1997Co-Authors: Kurt Mehlhorn, Stefan Naher, Christian UhrigAbstract:We give an overview of the Leda platform for combinatorial and geometric computing and an account of its development. We discuss our motivation for building Leda and to what extent we have reached our goals. We also discuss some recent theoretical developments. This paper contains no new technical material. It is intended as a guide to existing publications about the system. We refer the reader also to our web-pages for more information.
Andreas Crauser - One of the best experts on this subject based on the ideXlab platform.
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Leda sm extending Leda to secondary memory
Lecture Notes in Computer Science, 1999Co-Authors: Andreas Crauser, Kurt MehlhornAbstract:During the last years, many software libraries for in-core computation have been developed. Most internal memory algorithms perform very badly when used in an external memory setting. We introduce Leda-SM that extends the Leda-library [22] towards secondary memory computation. Leda-SM uses I/O-efficient algorithms and data structures that do not suffer from the so called I/O bottleneck. Leda is used for in-core computation. We explain the design of Leda-SM and report on performance results.
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Algorithm Engineering - Leda-SM Extending Leda to Secondary Memory
Lecture Notes in Computer Science, 1999Co-Authors: Andreas Crauser, Kurt MehlhornAbstract:During the last years, many software libraries for in-core computation have been developed. Most internal memory algorithms perform very badly when used in an external memory setting. We introduce Leda-SM that extends the Leda-library [22] towards secondary memory computation. Leda-SM uses I/O-efficient algorithms and data structures that do not suffer from the so called I/O bottleneck. Leda is used for in-core computation. We explain the design of Leda-SM and report on performance results.
L M Young - One of the best experts on this subject based on the ideXlab platform.
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Operations of the Leda resonantly coupled RFQ
PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268), 2001Co-Authors: L M YoungAbstract:The Leda RFQ is a 350-MHz continuous-wave (CW) radio-frequency quadrupole linac. Leda is the low energy demonstration accelerator, a full power front-end prototype for the accelerator production of tritium (APT) linac. This machine has accelerated a 100-mA CW proton beam from 75 keV to 6.7 MeV. The 8-m-long RFQ accepts a dc, 75-keV, /spl sim/110-mA H/sup +/ beam from the Leda injector, bunches the beam, and accelerates it to full energy with /spl sim/94% transmission. The output beam power is 670 kW. This RFQ consists of four 2-meter-long RFQs joined with resonant coupling to form an 8-meter-long RFQ. The resonant coupling improves the stability of both the longitudinal and transverse RF-field distribution in this long RFQ.
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high power operations of Leda
arXiv: Accelerator Physics, 2000Co-Authors: L M Young, L J Rybarcyk, J D Schneider, M E Schulze, H V SmithAbstract:The Leda RFQ, a 350-MHz continuous wave (CW) radio-frequency quadrupole (RFQ), successfully accelerated a 100-mA CW proton beam from 75 keV to 6.7 MeV. We have accumulated 111 hr of beam on time with at least 90 mA of CW output beam current. The 8-m-long RFQ accelerates a dc, 75-keV, ~106-mA H+ beam from the Leda injector with ~94% transmission. When operating the RFQ at the RF power level for which it was designed, the peak electrical field on the vane tips is 33 MV/m. However, to maintain the high transmission quoted above with the CW beam, it was necessary to operate the RFQ with field levels ~10% higher than design. The RFQ dissipates 1.5 MW of RF power when operating with this field. Three klystrons provide the 2.2 MW of RF power required by the RFQ to accelerate the 100-mA beam. The beam power is 670 kW. Some of the challenges that were met in accelerating a 100-mA CW proton beam to 6.7 MeV, will be discussed.
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High power RF conditioning of the Leda RFQ
Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366), 1999Co-Authors: L M Young, L J Rybarcyk, D.e. Rees, K.a. CummingsAbstract:We are preparing the radio frequency quadrupole (RFQ) for the Low Energy Demonstration Accelerator (Leda) to accelerate beam. The Leda RFQ accelerates a 100-mA CW proton beam from 75 keV to 6.7 MeV. We report our experience with high-power RF conditioning the RFQ, first with one klystron and then with two klystrons. The RFQ will dissipate 1.2 megawatts of RF power at design fields. This 350-MHz CW RFQ has peak fields on the vane tips of 33 MV/m. The average power dissipation is 13 watts/cm/sup 2/ on the outer walls of the RFQ near the high energy end. The power from each klystron is split 4 ways to lower the stress on the RF windows. Each klystron can produce 1.3 megawatts of RF power.
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tuning the Leda rfq 6 7 mev accelerator
19. international linac conference Chicago IL (United States) 23-28 Aug 1998, 1998Co-Authors: L M Young, L J RybarcykAbstract:This paper presents the results of tuning the 8 meter long Radio Frequency Quadrupole (RFQ) built for the Low Energy Demonstration Accelerator (Leda). This 350-MHz RFQ is split into four 2-meter-long-RFQs. Then they are joined with resonant coupling to form an 8-meter-long RFQ. This improves both the longitudinal stability and the transverse stability of this long RFQ. The frequencies of the modes near the RFQ mode are measured. The authors show the effect on the RF fields of an error in the temperature of each one of the 2-meter-long-RFQs. Slug tuners distributed along the outer walls tune the RFQ. The program RFQTUNE is used to determine the length of the tuners. The tuners are machined to length when the final tuning is complete.
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Simulations of the Leda LEBT H/sup +/ beam
Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167), 1997Co-Authors: H V Smith, J.d. Sherman, R.r. Stevens, L M YoungAbstract:The computer codes TRACE and SCHAR model the Low-Energy Demonstration Accelerator (Leda) low-energy beam transport (LEBT) for 75-keV, 110-mA, dc H/sup +/ beams. Solenoid-lens location studies verify that the proposed LEBT design gives a near-optimum match to the Leda RFQ. The desired RFQ transmission (/spl ges/90%) and output emittance (/spl les/0.22 /spl pi/ mm mrad, transverse) are obtained when PARMTEQM transports the file for the SCHAR-generated optimum beam through the RFQ.
Timothy A. Budd - One of the best experts on this subject based on the ideXlab platform.
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multiparadigm programming in Leda
1994Co-Authors: Timothy A. BuddAbstract:Offering an alternative approach to multiparadigm programming concepts, this work presents the four major language paradigms - imperative, object-oriented, functional and logical - through a new, common language called Leda. It: introduces the important emerging topic of multiparadigm programming - a concept that could be characterized as "the best of" programming languages; provides a coherent basis for comparing multiple paradigms in a common framework through a single language; and gives both a technical overview and summaries on important topics in programming-language development.
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CLeda--Leda With Constant Logic Programming
1993Co-Authors: Timothy A. Budd, Masami TakikawaAbstract:CLeda is a new programming language descended from the multiparadigm, strongly typed, compiled programming language Leda. In addition to the four paradigms supported by Leda, which are imperative, functional, object-oriented, and relational, CLeda supports the constraint logic programming paradigm. CLeda is intended to be used to write applications that involve constrained search problems. Constructs provided to support constraint logic programming include: * Built-in inference engine All Boolean expressions are "predicated" in the logic programming sense. Built-in operators "&" and "I" support left-most depth first search and automatic backtracking. Logical expressions can be used in any programming paradigms. * User definable constraint solver Constrained variables of a domain are represented in terms of objects of the corresponding class. Operations and predicated for the domain are written as methods of the class. To restore the necessary information upon backtracking, CLeda introduces a new built-in operator ">-", This operator is similar to the assignment operator ":=", but saves the necessary information to be recovered when backtracking occurs. This paper describes the design and implementation of the language CLeda.
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Compiler Implementation in the Multiparadigm Language Leda
1993Co-Authors: Timothy P. Justice, Rajeev K. Pandey, Timothy A. BuddAbstract:Compiler implementation is a difficult and intricate programming problem, due to the diversity of subproblems that must be solved. The compiler writer is faced with the challange of expressing solutions to these subproblems in some implementation language. With the advent of multiparadigm programming languages, diverse problem solving strategies and approaches can coexist within a single linguistic framework. The multiparadigm language Leda allows access to the imperative, logic, functional, and object-oriented paradigms within one programming language. Here we describe the experience of implementing a compiler in Leda, and examine how access to several paradigms affected our implementation.
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Multiparadigm data structures in Leda
Proceedings of the 1992 International Conference on Computer Languages, 1992Co-Authors: Timothy A. BuddAbstract:Multiparadigm programming is a term used to describe a style of software development that makes use of facilities originally designed in support of a number of different programming language paradigms. A conception of multiparadigm programming is illustrated by describing how various data structures can be implemented in Leda, a strongly typed compiled multiparadigm programming language. Specifically, a style of program development that draws upon features from a number of different programming language paradigms is illustrated. Aspects of imperative programming, object-oriented programming, functional programming, and logic (or relational) programming are used. It is shown how these various language paradigms can be integrated in a single problem domain, and how each can derive benefit from the others. The problem considered is the creation of a few simple data structures for lists and two-dimensional tables. The development of this example is used as a means to introduce Leda.
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ICCL - Multiparadigm data structures in Leda
Proceedings of the 1992 International Conference on Computer Languages, 1992Co-Authors: Timothy A. BuddAbstract:Multiparadigm programming is a term used to describe a style of software development that makes use of facilities originally designed in support of a number of different programming language paradigms. A conception of multiparadigm programming is illustrated by describing how various data structures can be implemented in Leda, a strongly typed compiled multiparadigm programming language. Specifically, a style of program development that draws upon features from a number of different programming language paradigms is illustrated. Aspects of imperative programming, object-oriented programming, functional programming, and logic (or relational) programming are used. It is shown how these various language paradigms can be integrated in a single problem domain, and how each can derive benefit from the others. The problem considered is the creation of a few simple data structures for lists and two-dimensional tables. The development of this example is used as a means to introduce Leda. >
G. Paturel - One of the best experts on this subject based on the ideXlab platform.
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a catalog of Leda galaxies with denis measurements
Astronomy and Astrophysics, 2005Co-Authors: G. Paturel, I. Vauglin, C. Petit, J Borsenberger, N Epchtein, P Fouque, G A MamonAbstract:We present a catalog of near-infrared properties of Leda galaxies, using the full resolution images from the DENIS survey. The fluxes are integrated in eight homothetic ellipses defined by their proper axis ratio, position angle and major axis (up to twice the blue diameter at the isophote 25 mag arcsec −2 ) extracted from the Leda database. From the curves of growth in I, J and Ks photometric bands, we estimated different apparent magnitudes and diameters ("total", "Kron" and "isophotal"). Isophotal parameters refer to the limiting surface brightnesses: 22.5 I mag arcsec −2 , 21.0 J mag arcsec −2 and 20.0 Ks mag arcsec −2 for the three photometric bands, respectively. The result is a catalog of 753 153 objects (among which there are 508 224 galaxies, 34 449 probable galaxies and 210 480 galaxies to be confirmed). The catalog gives about (the figures vary, depending on the considered magnitude or diameter): 668 000 I-band magnitudes, 576 000 J-band magnitudes, 357 000 Ks-band magnitudes and 452 000 I-band diameters, 299 000 J-band diameters, 114 000 Ks-band diameters. The typical standard deviations for I, J and Ks magnitudes are 0.14, 0.15 and 0.25, respectively, for magnitudes limited at I = 16, J = 15 and Ks = 14. The contamination by superimposed objects probably remains the major source of problems and could require future improvement. The completeness limits in magnitude are about: 15.5, 14.5 and 13 in I, J and Ks, respectively.
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The Denis-Leda Connexion: A Running Pipeline
Astrophysics and Space Science Library, 1997Co-Authors: I. Vauglin, G. Paturel, M. C. Marthinet, C. PetitAbstract:This connexion, realized a couple of months ago, is intended first to provide PDAC with proper cross-identifications between Leda galaxies (which are about 105at present) and the extended objects detected by DENIS (which may be up to 106). Next comes obviously the fruitful exploitation of the scientific resources of both entities.
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LONG-RANGE (FRACTAL) CORRELATIONS IN THE Leda DATABASE
Astronomy and Astrophysics, 1996Co-Authors: H. Di Nella, G. Paturel, Marco Montuori, Luciano Pietronero, F. Sylos LabiniAbstract:All the recent redshift surveys show highly irregular patterns of galaxies on scales of hundreds of megaparsecs such as chains, walls and cells. One of the most powerful catalog of galaxies is represented by the Leda database that contains more than 36,000 galaxies with redshift. We study the correlation properties of such a sample finding that galaxy distribution shows well defined fractal nature up to Rs ∼ 150h Mpc with fractal dimension D ≈ 2. We test the consistency of these results versus the incompleteness in the sample.
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Leda: The Lyon-Meudon Extragalactic Database
Information & On-Line Data in Astronomy, 1995Co-Authors: G. Paturel, I. Vauglin, H. Andernach, R. Garnier, M. C. Marthinet, C. Petit, H. Di Nella, L. Bottinelli, L. Gouguenheim, N. DurandAbstract:In 1981 our scientific team was involved in the management of large amount of HI-data. The goal, at this time, was only our own scientific research. In a collaboration with G. and A. de Vaucouleurs we started to add optical information to our first HI-catalog. It was our first contact with the difficult problem of cross-identifying two catalogs and merging them. To face this problem, one of us (GP) decided to rationalize the management by creating a database. It was created in 1983 at Lyon Observatory. Leda is thus the oldest Extragalactic Database. Since this time, the database has been continuously updated and improved.
