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  • Springer  (29)
  • 1995-1999  (29)
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  • 1
    Electronic Resource
    Electronic Resource
    An Evaluation on H/V Ratio vs. Spectral Ratio for Site-response Estimation Using the 1994 Northridge Earthquake Sequences (1999)
    Springer
    Pure and applied geophysics 156 (1999), S. 631-649 
    Details
    ISSN: 1420-9136
    Keywords: Key Words: H/V ratio, spectral ratio, site response, microtremor, resonant frequency, amplification.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —The applicability of the single-station H/V method, based on the spectral ratio between the horizontal and the vertical components of strong ground motions, is examined for site-response estimation using the high quality data from the 1994 Northridge earthquake sequence. Instead of using Rayleigh-wave data from microtremors, the large amplitude-wave part of the S-wave data is used and based on the 1994 Northridge mainshock and aftershock recordings. We have found that upon averaging over a number of recordings for a given station, the station site responses, derived both from the single-station H/V ratio and from the standard spectral ratio (with respect to a reference rock-site station) are sufficiently close for practical purposes. We therefore conclude that the H/V ratio can reasonably predict the resonant frequency and the amplification level of a site response, especially for sites in the neighborhood of the epicenters. In the absence of a reference rock-site station, the H/V ratio provides a practical alternative to the standard site-response estimation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050316
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  • 2
    Electronic Resource
    Electronic Resource
    Objective measures of the information density of satellite data (1996)
    Springer
    Meteorology and atmospheric physics 60 (1996), S. 105-117 
    Details
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Summary We propose and objective method whereby the density of Shannon's “information” associated with the retrieval of a profile of atmospheric variables from satellite-derived infrared radiance measurements may be estimated. The technique is a natural extension of one we previously proposed to estimate the effective data density in a profile. We test the method in a comparison of simulated satellite instruments to show that the method does indeed provide an objective summary of the spatial distribution of each instrument's information content. We propose that further extensions of the method be developed to include other more traditional data sources in a fully three-dimensional scheme. We also note that analogous and compatible methods may be used to diagnose the information content of meteorological analysis and forecast fields relative to the information contained in the covariance, at the appropriate season, of the corresponding climate fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01029788
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  • 3
    Electronic Resource
    Electronic Resource
    Solid/free-surface juncture boundary layer and wake (1998)
    Springer
    Experiments in fluids 25 (1998), S. 283-297 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The Reynolds-averaged flow for a solid/free-surface juncture boundary layer and wake is documented. The three mean-velocity components and five of the Reynolds stresses are measured for a surface-piercing flat plate in a towing tank using a laser-Doppler velocimeter system for both boundary-layer and wake planes in regions close to the free surface. The experimental method is described, including the foil-plate model, laser-Doppler velocimeter system, conditions, and uncertainty analysis. The underlying flow data is in excellent agreement with benchmark data. Inner (near the plate and wake centerplane and below the free surface) and outer (near the free surface) regions of high streamwise vorticity of opposite sign are observed, which transport, respectively, high mean velocity and low turbulence from the outer to the inner and low mean velocity and high turbulence from the inner to the outer portions of the boundary layer and wake. For the wake, the inner region of vorticity is relatively weak. The physical mechanism for the streamwise vorticity is analyzed with regard to the Reynolds-averaged streamwise vorticity equation. The anisotropy of the crossplane normal Reynolds stresses closely correlates with the vorticity and, additionally, indicates similarity, i.e., its nature is such that it only depends on the proximity to the plate and free surface boundaries or wake centerplane symmetry plane. Free-surface effects on the Reynolds stresses are analyzed with regard to the behavior close to the free surface of the turbulent kinetic energy and the normal components of the anisotropy tensor and the anisotropy invariants. Close to the free surface, the turbulent kinetic energy is nearly constant and increases for the inner and outer portions, respectively, of the boundary layer and wake and the normal components of the anisotropy tensor and the anisotropy invariants roughly correspond to the limiting values for two-component turbulence. The similarities and differences between the present results and analysis with those from related studies are discussed. The data and analysis should have practical application with regard to the development of turbulence models for computational fluid dynamics methods for the Reynolds-averaged Navier–Stokes equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050232
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  • 4
    Electronic Resource
    Electronic Resource
    An extension of digital PIV-processing to double-exposed images (1998)
    Springer
    Experiments in fluids 24 (1998), S. 364-372 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  In this paper digital processing techniques for PIV (Partical Image Velocimetry) using double-exposed particle images have been studied. It has been found that a pattern matching technique is significantly superior to the traditional autocorrelation method in the case that a large particle displacement between the double exposures is present on the image. In PIV using double-exposed images, the image shifting technique is usually used to solve the directional ambiguity problem. The performance of PIV using autocorrelation technique is dependent on the flow speed and the amount of image shift applied. This dependence, for example, causes a difficulty of autocorrelation in flows close to a solid boundary. The present study shows that a pattern matching technique eliminates such a difficulty. At the same signal-to-noise ratio, the pattern matching techndique has a better spatial resolution than that of autocorrelation. In concert with the pattern matching technique, PID (Particle Image Distortion) can be applied to double-exposed images, further improving the reliability and accuracy of velocity estimates of PIV in the presence of large velocity gradients. Generally speaking, PIP-matching and PID extend the validity of PIV using double-exposed images. The total processing time required by the PIV using the pattern matching technique and one PID iteration is of the same order as that required by the PIV using autocorrelation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050184
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  • 5
    Electronic Resource
    Electronic Resource
    A DPIV study of a starting flow downstream of a backward-facing step (1997)
    Springer
    Experiments in fluids 23 (1997), S. 395-404 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  In this paper an experimental investigation of a starting water flow downstream of a backward-facing step is described. The Reynolds number of the asymptotic steady flow is Re≈4300 based on the step height of s=2 cm and the free stream velocity of U=21.4 cm/s. Velocity measurements were performed with video-based DPIV (Digital Particle Image Velocimetry) at a sampling frequency of 25 Hz. The main purpose of this study is to reveal the temporal development of global structures which could not be analyzed with single-point probes. It was found that at initialization of the flow a regular vorticity street is formed, which collapses at a normalized time t * =U t/s≈17 due to vorticity interactions. After this the flow is dominated by complicated vorticity roll-up and shedding dynamics in the recirculation region. The starting phase is terminated for t * 〉40. Prior to the collapse of the vorticity street values of 9 times the steady state asymptotic wall normal stress and of twice the steady state negative wall shear stress were observed. The early increasing slope of the reattachment length is constant over a time of approximately t * =8. The collapse of the vorticity street and the vorticity interactions thereafter cause fluctuations both in the velocity in the free shear layer and in the reattachment length. The fully developed flow has a dominant frequency corresponding to a Strouhal number St=fs/U≈0.04.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050127
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  • 6
    Electronic Resource
    Electronic Resource
    Somatic embryo formation and germination from immature embryo-derived suspension-cultured cells of Angelica sinensis (Oliv.) Diels (1998)
    Springer
    Plant cell reports 17 (1998), S. 670-674 
    Details
    ISSN: 1432-203X
    Keywords: Key wordsAngelica sinensis ; Immature embryo culture ; Somatic embryo ; Suspension cell culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Embryogenic callus was induced from immature embryos of Angelica sinensis cultured on Murashige and Skoog (MS) basal medium. Embryogenic callus growth was more rapid on MS basal medium than on B5 or White medium. Embryogenic callus was used to establish a suspension culture and somatic embryos and germinating embryos developed during the culture. A shaking speed of 80 rpm was found to be optimal for establishing suspension cultures, while 100 rpm produced more somatic embryos and germinating embryos with an initiation cell density of 0.2 ml packed cell volume/25 ml medium. Adding 0.3% agar to the liquid medium also stimulated the formation of somatic and germinating embryos. While no plant growth regulators were needed for culture initiation and plant regeneration, the addition of 0.5–1 mg/l 2,4-dichlorophenoxyacetic acid was needed to maintain the embryogenic suspension culture by preventing embryo germination. Forty percent of the germinating embryos survived after culturing on filter paper moistened with liquid half-strength MS medium containing 3% sucrose. The plants were successfully transferred into soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050463
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  • 7
    Electronic Resource
    Electronic Resource
    Evidence for coupling between Na+ pump activity and TEA-sensitive K+ currents in Xenopus laevis oocytes (1995)
    Springer
    The journal of membrane biology 143 (1995), S. 29-35 
    Details
    ISSN: 1432-1424
    Keywords: Na+-K+-ATPase ; Electrophysiology ; K+ channel ; Tetraethylammonium ; Conductance regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Using the two-microelectrode voltage clamp technique in Xenopus laevis oocytes, we estimated Na+-K+-ATPase activity from the dihydroouabain-sensitive current (I DHO) in the presence of increasing concentrations of tetraethylammonium (TEA+; 0, 5, 10, 20, 40 mm), a well-known blocker of K+ channels. The effects of TEA+ on the total oocyte currents could be separated into two distinct parts: generation of a nonsaturating inward current increasing with negative membrane potentials (V M) and a saturable inhibitory component affecting an outward current easily detectable at positive V M. The nonsaturating component appears to be a barium-sensitive electrodiffusion of TEA+ which can be described by the Goldman-Hodgkin-Katz equation, while the saturating component is consistent with the expected blocking effect of TEA+ on K+ channels. Interestingly, this latter component disappears when the Na+-K+-ATPase is inhibited by 10 μm DHO. Conversely, TEA+ inhibits a component of I DHO with a k d of 25±4 mm at +50 mV. As the TEA+-sensitive current present in I DHO reversed at −75 mV, we hypothesized that it could come from an inhibition of K+ channels whose activity varies in parallel with the Na+-K+-ATPase activity. Supporting this hypothesis, the inward portion of this TEA+-sensitive current can be completely abolished by the addition of 1 mm Ba2+ to the bath. This study suggests that, in X. laevis oocytes, a close link exists between the Na-K-ATPase activity and TEA+-sensitive K+ currents and indicates that, in the absence of effective K+ channel inhibitors, I DHO does not exclusively represent the Na+-K+-ATPase-generated current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232521
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  • 8
    Electronic Resource
    Electronic Resource
    Estimation of long-term genetic improvement for gerbera using the best linear unbiased prediction (BLUP) procedure (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 790-794 
    Details
    ISSN: 1432-2242
    Keywords: Selection response ; Breeding value ; Mixed model ; Maximum likelihood ; Realized heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Long-term genetic improvement is measured by the selection response predicted from estimates of narrow-sense heritability. Accurate estimates of selection response require partitioning the change of population mean into genetic and environmental components. A selection experiment for cut-flower yield was conducted for 16 generations in the Davis population of gerbera (Gerbera hybrida, Compositae). Breeding values were estimated for individual plants in the population using the best linear unbiased prediction (BLUP) procedure. Genetic change in each generation was calculated from the breeding values of individual plants. The results of this study indicate that long-term selection was successful and necessary for the genetic improvement in cut-flower yield. Genetic improvement in mean breeding value over 16 generations was 33 flowers. Mean breeding values increased monotonically with an S-shape pattern while environmental effects fluctuated from generation to generation. Results predict that cut-flower yield in the Davis population of gerbera will continue to respond to selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220961
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  • 9
    Electronic Resource
    Electronic Resource
    Quantitative analysis of correlations among flower traits in Gerbera hybrida, Compositae. III. Genetic variability and structure of principal component traits (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 316-322 
    Details
    ISSN: 1432-2242
    Keywords: Key words Principal component analysis ; Genetic correlation ; Heritability ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A sample of 36 flower traits consisting of six morphological categories in the Davis population of gerbera was restructured into phenotypic and genetic principal component traits. The first 5 phenotypic principal component traits accounted for 62% of the total phenotypic variance of the 36 traits and have moderate to high heritablities. The first 5 genetic principal component traits account for 97% of total genetic variance and all have high heritability. Morphological structure of these component traits suggest an underlying process identified by the first genetic principal component involving largely trans and disk floret traits. The results of this study indicate that the quantitative genetic structure of the gerbera flower is controlled by a few independent components and that principal component analysis is a useful tool to reveal variation in this structure. These composite traits are heritable and are expected to respond to selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050901
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  • 10
    Electronic Resource
    Electronic Resource
    Two-level multipoint constraint approximation concept for structural optimization (1995)
    Springer
    Structural and multidisciplinary optimization 9 (1995), S. 38-45 
    Details
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A two-level multipoint approximation concept is proposed. Based upon the values and the first-order derivatives of the critical constraint functions at the points obtained in the procedure of optimization, explicit functions approximating the primal constraint functions have been created. The nonlinearities of the approximate functions are controlled to be near those of the constraint functions in their expansion domains. Based on the principle above, the first-level sequence of explicitly approximate problems used to solve the primarily structural optimization problem are constructed. Each of them is approximated again by the second-level sequence of approximate problems, which are formed by using the linear Taylor series expansion and then solved efficiently with dual theory. Typical numerical examples including optimum design for trusses and frames are solved to illustrate the power of the present method. The computational results show that the method is very efficient and no intermediate/generalized design variable is required to be selected. It testifies to the adaptability and generality of the method for complex problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01742643
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