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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 1473-1475 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electroabsorption (EA) of CdS0.1Se0.9 nanocrystals was measured under pulse-like modulated fields and recovered both with similar frequency (1f ) and with double frequency (2 f ) of the applied field. The EA properties and the effects of applied field form and recovered frequency on the EA properties were studied. Electric field induced strong change of absorption (10−3) was observed in resonant and nonresonant regions. The EA signal in the resonant region was due to the quantum confined Stark effects and the signal in the nonresonant region was due to the change of local field that resulted in the change of refractive index, the change of absorption. The quadratic dependence of EA signal intensity on the electric fields indicated that the nanocrystals had third nonlinear optical susceptibility. The EA signal intensity measured with 1f mode was about ten times of that measured with 2 f mode. Perhaps the lower response measured with 2 f mode was due to the measured mode and the different response coefficient in different frequency regions. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3266-3268 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The pressure dependence of ultrasonic attenuation in Zr41Ti14Cu12.5Ni10−xBe22.5Cx (x=0,1) bulk metallic glasses has been studied up to 0.5 GPa by using a pulse echo overlap method. The effect of carbon addition on the attenuation is also investigated. Some unique characteristics of the ultrasonic attenuation are found and compared with those of other glasses. The origin of the anomalous attenuation behavior is discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 6378-6388 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The kinetics of deuterium doping of and removal from polycrystalline (Ba,Sr)TiO3 (BST) thin films during annealing were investigated using secondary ion mass spectrometry depth profiling, and the data were correlated to changes in the electrical behavior of the films. Results for deuterium doping of exposed BST films on a Pt bottom electrode layer are consistent with incorporation of deuterium interstitial defects at the BST/Pt interface and "upward" diffusion toward the film surface. The incorporation kinetics of deuterium in Pt/BST/Pt capacitors are more complex and are greatly enhanced by the presence of the Pt top electrode. Removal of deuterium from D2/N2-exposed Pt/BST/Pt specimens during oxygen recovery anneals appears to be limited by the rate of an interfacial reaction at low temperatures (200–250 °C). The pre-D2 exposure leakage current properties of the BST capacitors were found to be largely recovered when the deuterium concentration in the films was reduced to ∼1019 cm−3 during post-D2 oxygen recovery anneals. Recovery annealing in vacuum, although it removed deuterium from the films, was found to result in an increase in leakage current density for annealing temperatures greater than 300 °C. These results suggest that introduction of large amounts of positive space charge into the BST films has a pronounced effect on the electrical properties of the Pt/BST interface. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1570-1573 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new apparatus using the inductance method has been built to test the homogeneity of large area high-Tc superconducting thin films. The apparatus has an X–Y scanning probe that can be moved at liquid nitrogen temperature to test the different regions of the films. The sample chamber of the apparatus can provide large area with high temperature homogeneity. The maximum sample size that can be measured is 50×50 mm2. A small size of high-Tc superconducting thin film is applied to test the temperature homogeneity of the testing system and the sameness of the gap distance between the surface of the film and probe. A method for testing the apparatus is illustrated, and some experiments for the test of the apparatus have been performed. Experimental results find that the maximum temperature difference is 0.05 K at the surface of the sample mounter, and the drive field remains constant within the error of 5% in the process of X–Y scanning. The apparatus can test the homogeneity of high-Tc superconducting films not only by the superconducting transition temperature Tc, but also by the critical sheet current density Kc. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1527-3458
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 25 (1977), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The Wiener prediction filter has been an effective tool for accomplishing dereverberation when the input data are stationary. For non-stationary data, however, the performance of the Wiener filter is often unsatisfactory. This is not surprising since it is derived under the stationarity assumption.Dereverberation of nonstationary seismic data is here accomplished with a difference equation model having time-varying coefficients. These time-varying coefficients are in turn expanded in terms of orthogonal functions. The kernels of these orthogonal functions are then determined according to the adaptive algorithm of Nagumo and Noda.It is demonstrated that the present adaptive predictive deconvolution method, which combines the time-varying difference equation model with the adaptive method of Nagumo and Noda, is a powerful tool for removing both the long- and short-period reverberations. Several examples using both synthetic and field data illustrate the application of adaptive predictive deconvolution. The results of applying the Wiener prediction filter and the adaptive predictive deconvolution on nonstationary data indicate that the adaptive method is much more effective in removing multiples. Furthermore, the criteria for selecting various input parameters are discussed. It has been found that the output trace from the adaptive predictive deconvolution is rather sensitive to some input parameters, and that the prediction distance is by far the most influential parameter.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 19 (1971), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: One of the problems in signal processing is estimating the impulse response function of an unknown system. The well-known Wiener filter theory has been a powerful method in attacking this problem. In comparison, the use of stochastic approximation method as an adaptive signal processor is relatively new. This adaptive scheme can often be described by a recursive equation in which the estimated impulse response parameters are adjusted according to the gradient of a predetermined error function.This paper illustrates by means of simple examples the application of stochastic approximation method as a single-channel adaptive processor. Under some conditions the expected value of its weight sequence converges to the corresponding Wiener optimum filter when the least-mean-square error criterion is used.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 60 (2005), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Demographic and biomass allocation patterns of Agropyron cristatum were measured on steppe and dune sites in the Hunshandake desert of North China in 2001 and 2002. Total plant population, reproductive shoot densities and its differentiation rates were significantly higher in the steppe sites in both years. Plant heights for both vegetative and reproductive shoots were greater in the year with the higher rainfall. The dune sites had a higher biomass allocation to vegetative shoots and roots, while the steppe sites had a higher biomass allocation to reproductive shoots and seed production. It is suggested that the population demography and biomass allocation of the species responded to the differences in the soil variables in the steppe and dune sites.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 23 (1975), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 24 (1976), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The system of normal equations associated with the discrete Wiener filter is sometimes ill-conditioned. The purpose of this paper is to show that in such cases the solutions obtained vary drastically with the particular choice of an algorithm and of the computer used for its implementation.A review of the basic mathematical theory behind an ill-conditioned matrix is first presented. Numerical examples are then given to illustrate that the solutions of the normal equations are sensitive to the word length of a given computer. Finally, two possible remedies are described: (1) The well-known method of prewhitening and (2) the use of the conjugate-gradient algorithm for solving the normal equations.
    Type of Medium: Electronic Resource
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