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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Computing 41 (1989), S. 59-74 
    ISSN: 1436-5057
    Keywords: 65L10 ; Boundary value problem ; monotone iteration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit wird eine neue Diskretisierungstechnik zur Erzeugung von Lösungseinschließungen bei schwach nichtlinearen 2-Punkt-Randwertaufgaben vorgeschlagen. Mittels verfügbarer Abschätzungen werden Unter-und Oberlösungen erzeugt. Die Monotonie des Verfahrens wird durch Prinzipien der monotonen Iteration gesichert. Es werden die Konvergenzeigenschaften des vorgeschlagenen Verfahrens analysiert.
    Notes: Abstract In this paper we propose a new discretization technique generating enclosures of the solution of a weakly nonlinear 2-point boundary value problem. By means of available extimations lower and upper solutions are generated. The monotonicity of the method is guaranteed by principles of monotone iterations. The convergence properties of the proposed algorithm are analyzed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Computing 43 (1990), S. 377-390 
    ISSN: 1436-5057
    Keywords: 65L10 ; 65L50 ; 65L60 ; differential equations ; boundary value problems ; enclosures ; grid generation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit wird ein Gittersteuerungsprinzip auf der Basis von monotonen Diskretisierungs-Iterations-Verfahren und der damit erzeugten Lösungseinschließungen bei schwach nichtlinearen 2-Punkt-Randwertaufgaben vorgeschlagen. Mittels verfügbarer Schranken wird das Gitter automatisch erzeugt. Die Monotonie des Verfahrens ist dabei durch Prinzipien der monotonen Iteration gesichert. Es werden die Konvergenzeigenschaften des vorgeschlagenen Verfahrens analysiert.
    Notes: Summary On the basis of the monotone discretization technique, we propose in this paper a new feedback grid generation principle for weakly nonlinear 2-point boundary value problems. By means of available estimations resulting from lower and upper solutions the grid can be refined automatically. The monotonicity of the method is guaranteed by principles of monotone iterations. The convergence properties of the proposed algorithm are analyzed.
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  • 3
    Publication Date: 2011-08-24
    Description: The spectral characteristics of an Alexandrite laser used for making water vapor DIAL measurements have been evaluated. The optical servo-system used to lock the laser wavelength on a water vapor absorption line is described. A brief description of the DIAL system is given and the data obtained with this lidar during flight tests in March 1990 are also presented.
    Keywords: LASERS AND MASERS
    Type: In: Earth and atmospheric remote sensing; Proceedings of the Meeting, Orlando, FL, Apr. 2-4, 1991 (A93-24176 08-42); p. 47-51.
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  • 4
    Publication Date: 2019-06-28
    Description: A compact and simple simultaneous multi-wavelength dye laser cavity was developed for a differential absorption technique. Dielectric multilayer interference filters were inserted inside the cavities as tuning elements, and two types of a DIAL system were constucted by using the dye laser tuned with dielectric multilayer filters to measure NO2 concentration. The usefulness of this dye laser was clarified for the differential absoroption technique in outdoor experiments. Some basic designs of the laser cavity with these filters to get simultaneously multi-wavelength output are summarized.
    Keywords: LASERS AND MASERS
    Type: NASA. Langley Research Center 13th International Laser Radar Conference; 5 p
    Format: application/pdf
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  • 5
    Publication Date: 2019-06-28
    Description: Raman conversion efficiency and line broadening are reported for Stokes operation at 720 and 940 nm, with hydrogen and deuterium as the Raman source, and using an Nd:YAG pumped Quanta-Ray PDL-2 dye laser. The dye laser linewidth is 0.2/cm (FWHM) with the grating alone as an intracavity element, and the conversion efficiency at 400 psi was found to be 40 and 20 percent for outputs of 720 and 940 nm, respectively. Pressure broadening coefficients of (9.2 + or - 0.9) x 10 to the -5th per cm/psi for hydrogen, and 7.7 x 10 to the -5th per cm/psi for deuterium, were obtained in good agreement with previous results. The linewidth at the first Stokes wavelength was shown to be determined by pressure broadening in the Raman medium.
    Keywords: LASERS AND MASERS
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  • 6
    Publication Date: 2019-07-13
    Description: A differential absorption lidar (DIAL) system developed at NASA Langley Research Center for the remote measurement of atmospheric H2O and aerosols from an aircraft is briefly discussed. This DIAL system utilizes a Nd:YAG laser-pumped dye laser as the off-line transmitter and a narrowband, tunable Alexandrite laser as the on-line transmitter. A 1-m monochromator and a multipass absorption cell are used to position the on-line laser to the center of the H2O line. The receiver system has a 14-in. diameter, f/7 Celestron telescope to collect the backscattered laser light and focus in into the detector optics. Return signals are converted to electrical signals by the optical detector and are digitalized and stored on magnetic tape. The results of fligh tests of the system are shown.
    Keywords: LASERS AND MASERS
    Type: Laser Radar V; Jan 18, 1990 - Jan 19, 1990; Los Angeles, CA; United States
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  • 7
    Publication Date: 2019-07-13
    Description: An overview of some of the developments completed on an alexandrite laser for making water vapor DIAL measurements is presented in this paper. A computer control for active stabilization of the two intracavity etalons has been implemented and recently tested in an aircraft environment. Long-term frequency drift (i.e., 2 hours) of less than 0.7 pm has been observed in the laboratory. An alignment technique to get the optimum free spectral range ratio for the two etalons is also developed.
    Keywords: LASERS AND MASERS
    Type: Laser Radar V; Jan 18, 1990 - Jan 19, 1990; Los Angeles, CA; United States
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  • 8
    Publication Date: 2019-07-12
    Description: For improved DIAL measurements of water vapor in the upper troposphere or lower stratosphere, narrowband (about 0.03/cm) laser radiation at 720- and 940-nm wavelengths was generated by stimulated Raman scattering (SRS), using the narrow linewidth (about 0.02/cm) output of a Nd:YAG-pumped dye laser. For a hydrogen pressure of 350 psi, the first Stokes conversion efficiencies to 940 nm were 20 percent and 35 percent, when using a conventional and waveguide Raman cell, respectively. The linewidth of the first Stokes line at high cell pressures, and the inferred collisional broadening coefficients, agree well with those previously measured in spontaneous Raman scattering.
    Keywords: LASERS AND MASERS
    Type: Applied Optics (ISSN 0003-6935); 26; 1617-162
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