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排序方式: 共有215条查询结果,搜索用时 15 毫秒
1.
V. A. Gorelik V. I. Erokhin R. V. Pechenkin 《Journal of Computer and Systems Sciences International》2006,45(5):727-737
The problem of correction of matrices (extended matrices) of inconsistent systems of linear algebraic equations with block structure and with the cost function of minimax type is considered. These problems are reduced to a constrained optimization problem, which, in turn, is reduced to a series of linear programming problems. All problems of matrix correction are illustrated by numerical examples. 相似文献
2.
The charge collection efficiency of CdZnTe radiation detectors with two different configurations: aSchottky diode detector and aresistive detector are compared. The average charge collection efficiencies for three different directions of irradiation (negative electrode,
positive electrode and perpendicular to the electric field) are calculated. The mobility-lifetime product of the CdZnTe substrates
is evaluated from the dependence of the measured spectra upon detector bias voltage. The measurement of the average charge
collection efficiency is based on monitoring the shift of the peak channel with bias voltage in an experimental setup which
is well calibrated. Two types of radiation are used:gamma photons from several radioactive sources andalpha particles from an241Am source. The models for the evaluation of mobility-lifetime product from the measured data for the two types of detector
configurations as well as for the two types of radiation sources, are compared and discussed. The CdZnTe (Zn = 10%) substrates
under study are obtained commercially and are grown by the high pressure Bridgeman method. The mobility-lifetime products
and specific resistivity of the two types of detectors are evaluated and compared. A lower resistivity material has a narrower
depletion region and behaves like a thinner detector thus exhibiting better collection efficiencies. Therefore, medium resistivity
material which is completely inadequate for resistive detectors can still yield high performance Schottky detectors. The preferred
direction of irradiation, i.e. from the negative electrode, is possible only in the case of n-type material which is reverse
biased by negative voltages applied to the Schottky gate. The mobility-lifetime products that are derived on both the resistive
detector (with specific resistivity of ≈1.1010 ω.cm) and the Schottky diode (with specific resistivity of ≈1.106 Ω.cm) are μnτn ≈-4.10−4 cm2V−1 and μpτp≅ 8.10−5 cm2V−1. 相似文献
3.
V. S. Gorelik S. O. Nechipurenko A. A. Loboiko Yu. P. Voinov 《Inorganic Materials》2018,54(7):694-699
We have measured photoluminescence spectra of an aqueous uranyl chloride solution under excitation by various light sources: semiconductor light-emitting diodes and cw laser. The excitation wavelength lay within a resonance absorption band of uranyl chloride, which ensured photoluminescence detection at exposure times of 10–3 s using an extremely small volume of the substance (10–9 cm3). The photoluminescence spectra were measured using a small minispectrometer, which allowed us to analyze the spectra in the range 200–1000 nm. 相似文献
4.
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6.
Infiltration of opal with nonlinear optical materials is shown to markedly raise its emission intensity in the visible range under pulsed laser excitation. Evidence is presented for three-photon parametric scattering in both uninfiltrated and infiltrated globular photonic crystals, with excitation of “slow” photons in the visible range. Our results indicate that synthetic opal crystals can be used as photon traps for studying the emission spectra of organic and inorganic materials infiltrated in opal pores. 相似文献
7.
The dispersion laws of the optical and acoustic branches in diamond-like crystals have been derived using idealized models
of crystal lattices. Two types of analytical expressions have been proposed, whose parameters can be derived from inelastic
neutron scattering experiments and the properties of acoustic waves. The calculation results are in satisfactory agreement
with experimental data for the crystallographic directions [100], [110], and [111]. The group velocities of optical and acoustic
phonons have been determined, and expressions for the effective mass of optical phonons have been derived. 相似文献
8.
V. S. Gorelik Yu. P. Voinov G. A. Emel’chenko V. M. Masalov N. I. Yurasov V. V. Gryaznov 《Inorganic Materials》2009,45(6):645-650
We analyze broadband visible reflectivity spectra of opal photonic crystals annealed in an argon atmosphere and air. Scanning electron microscopic examination has shown that the crystals consist of close-packed spheres with a mean diameter in the range 200–290 nm. Incorporation of even small amounts of carbon (?0.5 wt %) increases the density of the opal matrix. The presence of carbon shifts the Bragg reflection peak of the opal and increases its intensity. 相似文献
9.
V. S. Gorelik N. I. Yurasov V. V. Gryaznov Yu. P. Voinov P. P. Sverbil’ M. I. Samoilovich 《Inorganic Materials》2009,45(9):1013-1017
We have studied the optical properties of opal photonic crystals infiltrated with the M0.35Zn0.65Fe2O4 (M = Ni, Co) ferrites. The crystals consisted of amorphous SiO2 nanospheres. The visible reflectivity spectra of the crystals were used to determine parameters of their photonic band gap
and their refractive index. 相似文献
10.
G. E. Gorelik V. G. Leitsina N. V. Pavlyukevich 《Journal of Engineering Physics and Thermophysics》1985,49(2):983-987
The distribution of radiation absorbed by the inner surface of a cylindrical cavity is found by the Monte Carlo method for a different nature of the reflection and different ratios between the input beam and cavity diameters.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 2, pp. 304–308, August, 1985. 相似文献