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211.
Results of an experimental observation of the voltage oscillations associated with a discrete tunneling of holes in porous silicon at room temperature are presented. The noise characteristics of diode structures with a porous silicon interlayer formed on heavily boron-doped silicon single crystals are studied. Peaks of excessive noise are observed at frequencies of ~1 MHz, at which single-electron oscillations should be expected. The peak noise power is found to increase with current according to the ~2.5 power law and, at a current density of 0.15 A/cm2, to exceed the noise power of the receiver by three to four orders of magnitude. The complex shape of the noise spectrum and its extension to the higher frequency region with increasing current are explained by the three-dimensionality of the system of nanometer-sized silicon grains embedded in insulating silicon dioxide of porous silicon. 相似文献
212.
T. N. Kravets 《Journal of Mathematical Sciences》1991,53(4):398-403
In this paper we study a stochastic differential equation with multivalued maximally monotone drift operator. Under certain assumptions on the growth of the multivalued operator we prove a theorem on the existence and uniqueness of the solution of such an equation.Translated fromTeoriya Sluchainykh Protsessov, Vol. 15, pp. 54–59, 1987. 相似文献
213.
214.
N S Sergeeva M Iu Vasil'ev T I Kovalenko N V Sokolova G I Avdeev 《Eksperimental?nai?a onkologii?a》1989,11(2):35-37
The indirect immunofluorescent technique was used to study the distribution of the ascitic fluid antigen (AgD) on histological sections from surgical specimens of gastric and colon tumours from proximal to distal lines of resection. AgD was found in gastric tumours exceptionally in the tumour area and in colon cancer--both in the tumour stroma and in surrounding histologically normal mucosa. 相似文献
215.
A simple model for a distributed self-oscillatory system with cubic nonlinearity and delay is presented. Conditions for oscillation self-excitation and stationary oscillation conditions, as well as the stability of the oscillations, are analyzed. Nonstationary self-modulation regimes (including conditions of complex dynamics and chaos) are simulated numerically over a wide range of control parameters. As the factor of nonequilibrium grows, regular and chaotic regimes alternate in a complex manner. The transitions to chaos may follow all scenarios known for finite-dimensional systems. The model suggested is somewhat akin to a number of earlier finite-dimensional models aimed at studying mode competition in resonance electron masers. 相似文献
216.
217.
Problems associated with different calibration techniques and some instrumental effects that can determine instrumental accuracy are discussed. It is shown how transmission effects can be observed and used to generate a correction curve for refracted near-field instruments. High-quality fiber slices needed for axial interferometry were used to obtain refractive index differences on suitable fibers to ±1% with the measurements traceable to national standards. Interferometry was used to calibrate a multiple-step fiber which is available in 10-m lengths with a certificate of calibration. The limitations of the technique are discussed, and preliminary results of a study on the effects of residual stress and stress relief on measurements are given. Comparisons are made between measurements made by axial interferometry and refracted near field on a range of fibers. It is shown that commercial profilers can produce reliable measurements of refractive index difference, absolute refractive index, profile shape, and numerical aperture that agree well with measurements by other techniques 相似文献
218.
A. A. Karabutov V. A. Larichev G. A. Maksimov I. M. Pelivanov N. B. Podymova 《Acoustical Physics》2006,52(5):582-588
The first experimental observation of the propagation dynamics of a short broadband acoustic pulse in a resonance medium with gas bubbles is carried out. The probing pulse is generated using the optoacoustic effect. It is shown that the theory of short pulse propagation in media with generalized resonance relaxation adequately and accurately describes the dynamics of short pulse dispersion. A possibility to determine the relaxation and resonance parameters of media by the pulsed testing technique is demonstrated. 相似文献
219.
Summary Thermopiezoelastic materials have recently attracted considerable attention because of their potential use in intelligent
or smart structural systems. The governing equations of a thermopiezoelastic medium are more complex due to the intrinsic
coupling effects that take place among mechanical, electrical and thermal fields. In this analysis, we deal with the problem
of a crack in a semi-infinite, transversely isotropic, thermopiezoelastic material by means of potential functions and Fourier
transforms under steady heat-flux loading conditions. The problem is reduced to a singular integral equation that is solved.
The thermal stress intensity factor for a crack situated in a cadmium selenide material is calculated.
Received 20 March 2001; accepted for publication 18 October 2001 相似文献
220.
A quasi-TEM approach based on conformal transformation is used for the determination of the characteristic impedance of a rectangular coaxial line (TEM cell) having a symmetrically located inner conductor (septum) supported on a dielectric slab of equal width. The method of determination of the capacitance of the dielectric-filled portion is discussed. The results on characteristic impedance for two values of dielectric constant are presented. 相似文献