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991.
The possibility of usage of the spontaneous electrooptical (EO) effect in strontium barium niobate (SBN) crystals for the creation of controlled electroholographic elements is studied. It is found that unipolar EO properties of these crystals with respect to switching their spontaneous polarization make it possible to devise field-controlled holographic elements with reversible energy-independent memory for spatial position of an optical beam.  相似文献   
992.
This paper proposes a new matrix method for calculating critical flow velocity of curved pipes conveying fluid, which have arbitrary centerline shape and spring supports. Its main advantage over other methods is that the corresponding characteristic equation can be reduced to a third order one, no matter how many elements are discretized in calculation. This will lead to saving computer time and obtaining a solution with good precision.  相似文献   
993.
Asymptotic canonical variables and the classical S matrix for the nonlinear Schrödinger model with nonzero boundary conditions are calculated in terms of spectral data of an auxiliary linear operator, subject to the condition that a discrete spectrum does not exist.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 169, pp. 60–67, 1988.  相似文献   
994.
X.F. Hu 《Applied Surface Science》2006,252(13):4625-4627
The synthetic antiferromagnets (SAF) have been used in spin-valve sensor in data storage industry [1]. We report a new hard/Ru/soft sandwich structure (SHBL) fabricated by pulsed lased deposition to replace current single layer structure for information recording application. SHBL consists of two magnetic layers separated by thin nonmagnetic layers, typically with Ru layers of 0.7-1.2 nm, through which antiferromagnetic coupling is induced. Varying the relative thickness of the magnetic layers, the spacer layers, and the type of magnetic materials can alter magnetic properties of CoCrPt/Ru/CoFe superlattice. The coercivity Hc and grain size of magnetic layer is also dependent on the laser fluence. High laser fluence results in both small grain size and high Hc. The observed phenomena are related to high quenching and deposition rates during PLD at high fluence, resulting in more pronounced phase segregation.  相似文献   
995.
We investigate the viability of f(R) theories in the framework of the Palatini approach as solutions to the problem of the observed accelerated expansion of the universe. Two physically motivated popular choices for f(R) are considered,: power law, f(R) = β R n , and logarithmic, f(R) = α ln R. Under the Palatini approach, both Lagrangians give rise to cosmological models comprising only standard matter and undergoing a present phase of accelerated expansion. We use the Hubble diagram of type Ia Supernovae and the data on the gas mass fraction in relaxed galaxy clusters to see whether these models are able to reproduce what is observed and to constrain their parameters. It turns out that they are indeed able to fit the data with values of the Hubble constant and of the matter density parameter in agreement with some model independent estimates, but the today deceleration parameter is higher than what is measured in the concordance ΛCDM model.  相似文献   
996.
There is experimental evidence that the non-sphericity of certain atmospheric particles can cause scattering properties different from those predicted by standard Mie theory. Numerous studies indicate the need to consider the presence of non-spherical particles in modeling the optical properties of atmospheric aerosols. On the other hand, natural aerosols show a great variety of shapes, making difficult a realistic choice of a particle shape (or shape mixture) model. In this paper, we test a parameterization of the particle shape in the retrieval of size distribution, phase function, single scattering albedo and asymmetry parameter from direct and sky-radiance measurements. For this purpose we have substituted the Kernel based on the Mie theory included in the model SKYRAD.PACK by one derived for non-spherical particles. The method is applied under different atmospheric conditions, including Saharan dust outbreak, polluted and local mineral episodes. We compare the results with those obtained by the well known spheroids algorithm used in the AERONET network.  相似文献   
997.
998.
Optimum experimental conditions for the brittle fracture technique applied in trace metal analysis of biological material are described. The efficiency of the technique was tested by sieve and radio-tracer experiments. Numerical results are presented for human placenta submitted to eight different grinding procedures.  相似文献   
999.
Lewis  M.F. 《Electronics letters》1985,21(13):573-574
It is shown that, by exploiting the 2-dimensional structure of a SAW substrate to propagate different frequency components over distinct physical paths, the amplitude-limiting process that occurs at high power levels can be made `local? in the frequency domain. One application of such a frequency-domain limiter is to suppress CW interference in spread-spectrum communications.  相似文献   
1000.
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