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  • 1
    Electronic Resource
    Electronic Resource
    Extension of optimality conditions via supporting functions (1973)
    Springer
    Mathematical programming 5 (1973), S. 267-285 
    Details
    ISSN: 1436-4646
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this study we introduce the notion of supporting functions and exploit some of their important properties. We make use of these functions to develop generalized optimality conditions of a mixed stationary-saddle type, where the supporting functions play either the role of the gradients/directional derivatives and/or the role of the original functions. These conditions may be applied to certain problems involving nondifferentiable and/or nonconvex functions. Classical, as well as new stationary and saddle optimality conditions follow from our approach in a natural fashion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01580133
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  • 2
    Electronic Resource
    Electronic Resource
    The traveling salesman problem: A duality approach (1977)
    Springer
    Mathematical programming 13 (1977), S. 221-237 
    Details
    ISSN: 1436-4646
    Keywords: Traveling salesman problem ; Lagrangian multipliers ; Branch and bound ; Lagrangian duality ; Subgradient optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this study we formulate the dual of the traveling salesman problem, which extends in a natural way the dual problem of Held and Karp to the nonsymmetric case. The dual problem is solved by a subgradient optimization technique. A branch and bound scheme with stepped fathoming is then used to find optimal and suboptimal tours. Computational experience for the algorithm is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01584338
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  • 3
    Electronic Resource
    Electronic Resource
    On the convergence of a class of algorithms using linearly independent search directions (1980)
    Springer
    Mathematical programming 18 (1980), S. 89-93 
    Details
    ISSN: 1436-4646
    Keywords: Cyclic Coordinate Method ; Independent Search Directions ; Cycling ; Unconstrained Minimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Powell has shown that the cyclic coordinate method with exact searches may not converge to a stationary point. In this note we consider a more general class of algorithms for unconstrained minimization, and establish their convergence under the assumption that the objective function has a unique minimum along any line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01588300
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  • 4
    Electronic Resource
    Electronic Resource
    Responsiveness and discrimination during sleep (1963)
    Springer
    Cellular and molecular life sciences 19 (1963), S. 208-209 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Résumé La discrimination tonale a été analysée chez des chats dressés pendant l'état de veille à répondre à un son d'une fréuence donnée (son «positif») et à ne pas répondre aux autres fréquences sonores (sons «négatifs»). Pendant la veille, l'efficacité des sons «negatifs» diminue au fur et à mesure que la différence de fréquence avec le son «positif» augmente. Pendant le sommeil lent et de haut voltage, l'efficacité du son «positif» ne change pas ou diminue peu, tandis que celle des sons «négatifs» est réduite: ainsi, le chat endormi possède encore la possibilité de faire des discriminations précises. Pendant la phase «rhombencéphalique» du sommeil, l'efficacité de tous les sons disparaît: on discute la nature de ce manque de réactivité.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02172319
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  • 5
    Electronic Resource
    Electronic Resource
    Ionic content of bone from uraemic patients derived by neutron activation analysis (1976)
    Springer
    Calcified tissue international 22 (1976), S. 501-501 
    Details
    ISSN: 1432-0827
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02064144
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  • 6
    Electronic Resource
    Electronic Resource
    Estimation of hydrogen peroxide formed and residual ascorbate in the copper catalysed oxidation reaction of ascorbate at pH 7 (1992)
    Springer
    Microchimica acta 106 (1992), S. 143-152 
    Details
    ISSN: 1436-5073
    Keywords: ascorbate ; hydrogen peroxide ; copper ; fluorescent assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A fluorescent method has been developed for determination of ascorbic acid concentrations. The method involves treatment of the ascorbic acid with Cu(II) and treating the hydrogen peroxide formed with horseradish peroxidase in the presence ofp-hydroxyphenylacetic acid, to form a fluorescentp-hydroxyphenylacetic acid dimer. The reaction is suitable for analysis of concentrations in the range from 50 μM to 4 mM ascorbic acid solutions and can be used for analysis of pharmaceutical preparations but is unsuitable for analysis of ascorbate in preparations derived from natural sources. By using a slight modification of the analytical technique it is possible to measure the amount of hydrogen peroxide formed and the residual concentrations of ascorbic acid in solutions treated with varying amounts of copper ion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01242085
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  • 7
    Electronic Resource
    Electronic Resource
    Book reviews (1982)
    Springer
    Origins of life and evolution of the biospheres 12 (1982), S. 119-121 
    Details
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00926916
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  • 8
    Electronic Resource
    Electronic Resource
    New Digital Magnetograph At Big Bear Solar Observatory (1998)
    Springer
    Solar physics 183 (1998), S. 1-13 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new digital magnetograph system has been installed and tested at Big Bear Solar Observatory. The system uses part of BBSO's existing videomagnetograph (VMG) system: a quarter wave plate, a ferro-electric liquid crystal to switch polarizations, and a 0.25 Å bandpass Zeiss filter tuned at Ca i 6103 Å. A new 256×256 pixels, 12-bit Dalsa camera is used as the detector and as the driver to switch the liquid crystal. The data rate of the camera is 90 frames s−1. The camera is interfaced to a Pentium-166 PC with a μTech imaging board for data acquisition and analysis. The computer has 128 MByte of RAM, and up to 700 live images can be stored in memory for quick post-exposure image processing (image selection and alignment). We have significantly improved the sensitivity and spatial resolution over the old BBSO VMG system. In particular: (1) New digital image data are in 12 bits while the video signal is digitized as 8 bits. Polarizations weaker than 1% can not be detected by a single pair subtraction in the video system. The digital system can detect a polarization signal of about 0.3% by a single pair subtraction. (2) Data rate of the digital system is 90 frames s−1, that of the video system is 30 frames s−1. So the time difference between two polarizations is reduced in the new system. Under good seeing conditions, the data rate of 90 frames s−1 ensures that most of the wavefront distortions are ‘frozen’ and fairly closely the same for the left and right circular polarized image pairs. (3) Magnetograms are constructed after image selection and alignment. We discuss the characteristics of this new system. We present the results of our first tests to reconstruct magnetograms with speckle interferometric techniques. We also present some preliminary results on the comparison of facular/micropore contrasts and magnetic field structure. The experiment with this small detector lays ground for a larger format digital magnetograph system at BBSO, as well as a future Fabry-Pérot system, which will be able to scan across the spectral line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005027605781
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  • 9
    Electronic Resource
    Electronic Resource
    Synoptic Hα Full-Disk Observations of the Sun from Big Bear Solar Observatory – I. Instrumentation, Image Processing, Data Products, and First Results (1999)
    Springer
    Solar physics 184 (1999), S. 87-102 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Big Bear Solar Observatory (BBSO) has a long tradition of synoptic full-disk observations. Synoptic observations of contrast enhanced full-disk images in the Ca ii K-line have been used with great success to reproduce the H i Lα irradiance variability observed with the Upper Atmosphere Research Satellite (UARS). Recent improvements in data calibration procedures and image- processing techniques enable us now to provide contrast enhanced Hα full-disk images with a spatial resolution of approximately 2′′ and a temporal resolution of up to 3 frames min−1. In this first paper in a series, we describe the instruments, the data calibration procedures, and the image-processing techniques used to obtain our daily Hα full-disk observations. We also present the final data products such as low- and high-contrast images, and Carrington rotation charts. A time series of an erupting mini- filament further illustrates the quality of our Hα full-disk observations and motivate one of the future research projects. This lays a solid foundation for our subsequent studies of solar activity and chromospheric fine structures. The high quality and the sunrise- to-sunset operation of the Hα full-disk observations presented in this paper make them an ideal choice to study statistical properties of mini-filament eruptions, chromospheric differential rotation, and meridional flows within the chromosphere, as well as the evolution of active regions, filaments, flares, and prominences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005047906097
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  • 10
    Electronic Resource
    Electronic Resource
    Studies of Microflares and C5.2 flare of 27 September 1998 (1999)
    Springer
    Solar physics 188 (1999), S. 365-376 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract On 27 September 1998, Big Bear Solar Observatory (BBSO) and Transition Region and Coronal Explorer (TRACE) coordinated observations from 16:00 to 19:00 UT to study properties of microflares in AR NOAA No. 8340. Fortuitously, a C5.2 flare occurred at 16:30 UT in this active region. Hα and magnetograph movies were obtained at BBSO; C iv 1550 Å, Fe ix 171 Å, and Fe xii 195 Å movies were obtained by TRACE; both with a cadence about 1 min. In this paper, we concentrate on the study of magnetic properties of 70 C iv microflares, as well as their relationship to the C5.2 flare. We obtained the following results: (1) We found two kinds of microflares: microflares of transient brightenings with a time scale of 1 to 5 min (impulsive events) and microflares lasting half an hour or longer (persistent events). Ninety percent of the microflares are impulsive events. Most of the event in this category are associated with well defined magnetic neutral lines, but some are found in non-neutral line areas. All of seven persistent events are found at parasitic magnetic configurations with inclusions of small magnetic flux within dominant magnetic flux of opposite polarity. (2) More than a third of the impulsive microflares occurred near the C5.2 flare site indicating that a local instability is responsible for both the C5.2 flare and microflares. This indirectly supports the avalanche theory of flare energy release, which implies that a big flare may be spatially associated with many small flares.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005288217459
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