共查询到20条相似文献,搜索用时 31 毫秒
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N. I. Trushkin V. B. Karal’nik M. E. Grushin G. I. Aponin Yu. S. Akishev 《Laser Physics》2006,16(1):173-182
The development of streamers and sparks in nitrogen at atmospheric pressure in the pin-to-plane electrode configuration is
studied in experiments and theoretical calculations. It is demonstrated that the near-electrode regions play the decisive
role in streamer initiation. At a negative pin voltage, a spark is formed in the absence of fast primary streamers. At a positive
pin voltage, streamer build-up is initiated by the current spots on the anode that result from the development of the ionization
instabilities in the anode region. The calculations show that the formation of the current spot on the anode leads to a redistribution
of the electric field in the vicinity of the anode, so that a single avalanche is transformed into a streamer under the conditions
when the known criterion for streamer breakdown (the Meek-Raether criterion) is not satisfied.
Original Text ? Astro, Ltd., 2006. 相似文献
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从科学史的角度论述了形象思维在静态宇宙模型建立中的作用,并结合爱因斯坦的研究风格分析了这种创造性思维形态的具体表现和特征。 相似文献
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The fluctuations in the angles of arrival of a laser beam along a route 1200 m in length are investigated experimentally. The aperture dimensions of the transmitting and receiving devices and the beam geometry were varied during the measurements. The results obtained are compared with the results obtained by simultaneously determining the fluctuations in the angles of arrival of the radiation from a source of spherical waves. It is shown that the angles of arrival have a normal distribution. The dispersion of the angles of arrival depends on the diameter of the receiving aperture raised to the power -1/3 and increases as the angular aperture of the beam is reduced, becoming greater than the dispersion of the angles of arrival of spherical waves.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, Vol. 12, No. 1, pp. 103–106, January, 1969. 相似文献
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V. L. Ékelekyan 《Russian Physics Journal》1981,24(7):626-630
Solutions of the Bogolyubov-Born-Green-Kirkwood-Ivon equations in the fourth approximation in the temperature are given in a class of generalized functions both for van der Waals and ionic crystals in the case of the so-called taking into account of smoothed correlations. A statistical thermodynamics of strongly anharmonic van der Waals and ionic crystals is constructed. Temperature expansions of the correlative distribution functions and thermodynamic quantities are investigated within the framework of the indicated method. The temperature dependence of cubic order is taken into account in the expression of the isochoric specific heat and the Grüneisen parameter of the listed crystals. It is shown that the temperature expansion for the isochoric specific heat of anharmonic crystals converges well for a value of the reduced temperature 0.33 Tm (Tm is the melting temperature).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 55–59, July, 1981. 相似文献
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Kislyakov A. G. Shkelev E. I. Yastrebov I. P. Savelyev D. V. 《Radiophysics and Quantum Electronics》2003,46(11):852-859
We compare the data on the atmospheric radio emission in two ozone lines with resonance frequencies 96,228 and 101,736 MHz, obtained at the N. I. Lobachevsky State University of Nizhny Novgorod in 1996–2001, with the corresponding results of measuring the number of neutrons in the atmosphere, obtained at the Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (Troitsk, Moscow region) using the NM-64 monitor. It is shown that variations in both the optical depth and the intensity ratio of these lines correlate with variations in the number of neutrons. The maximum observed correlation coefficients for the optical-depth decrements of the lines amount to 0.5–0.6, which is about a factor of 1.5 higher than the maximum correlation coefficient for their intensity ratio. We analyze the dependence of the correlation coefficients on the time shift between data series for the ozone line intensity and the number of neutrons in the atmosphere. It is shown that correlation between these data series almost vanishes for a time shift of about 200 h. We discuss the features of the data on the number of neutrons in the atmosphere and the possibility of the solar origin of neutrons. 相似文献
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The magnetoresistance effects in the bi- and trilayer hybrid planar superconductor/ferromagnet (S/F) structures based on Py (permalloy) and Nb near the superconducting transition temperature T C are considered. It has been experimentally shown that the sign of the observed magnetoresistance peaks in the bilayer S/F systems changes from negative to positive at the permalloy layer thickness corresponding to the change in the type of domain walls from Néel to Bloch. For the Néel walls at the ferromagnet coercive fields, the negative magnetoresistance effect, which is due to a decrease in the depairing action of the exchange field E ex, is observed in the S/F bilayers. For the Bloch domain walls, the magnetoresistance of the bilayer S/F structures is determined by the dissipative motion of Abrikosov vortices in the superconducting layer. In the trilayer F/S/F structures, the magnetoresistance is mainly due to the suppression of the superconducting order parameter in the superconducting layer under the action of the accumulation of the spin-polarized carriers near the S/F interfaces. 相似文献
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Yu. N. Khanin E. E. Vdovin M. V. Grigor’ev L. Eaves O. N. Makarovskiĭ M. Henini 《Journal of Experimental and Theoretical Physics》2007,105(1):177-180
A high narrow peak in the interlayer differential tunnel conductance has been observed in heterostructures with two closely located electron layers at low temperatures. Analysis of the experimental results suggests that this peak is due to the interlayer phase coherence, which appears in the system under investigation owing to the Bose condensation of indirect excitons, i.e., pairs of electrons and holes from different layers in the absence of the magnetic field. 相似文献
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It has been shown that the use of the survival function of the Weibull distribution shifted along the ordinate axis allows one to increase the accuracy of the approximation of the normalized profile of an erosion zone in the area from the axis to the maximum sputtering region compared with the previously suggested distribution function of the extremum values. The survival function of the Weibull distribution is used in the area from the maximum to the outer boundary of an erosion zone. The major advantage of using the new approximation is observed for magnetrons with a large central nonsputtered spot and for magnetrons with substantial sputtering in the paraxial zone.
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The magnetization of maghemite and magnetite thin films is measured as a function of the temperature and orientation of the
film. It is established that the temperature dependence of the spontaneous magnetization deviates from the Bloch law at low
temperatures and is adequately described by the linear function M/M
s = 2.2(1-T/T
C) below the Curie temperature T
C. The linear temperature dependence of the magnetization below the Curie temperature is explained by the change in the spin
of iron ions in tetrahedral positions due to local deformations of the crystal lattice. 相似文献
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Yu. N. Ovchinnikov A. M. Dyugaev 《Journal of Experimental and Theoretical Physics》2000,90(1):144-152
It is shown that there are two energy scales in the Kondo problem: T k and T 0, one of which (T k) is exponentially small in the coupling constant g. The second scale T 0is proportional to the squared coupling constant. Perturbation theory is valid only in the region T? T 0. The point T 0 is apparently the crossover from weak to strong coupling. The first indications of the breakdown of the hypothesis of only one energy scale in the Kondo problem appear in fourth order of perturbation theory. 相似文献
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Doklady Physics - A linear mechanical system with n degrees of freedom is considered. The change in the character of stability of trivial equilibrium is studied in the case when the rigidity in one... 相似文献
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A. I. Terekhov 《Journal of nanoparticle research》2012,14(11):1-17
Many toxicology studies on insoluble and poorly soluble nanoparticles point out surface area as an indicator of inhalation exposure. Measuring this criterion thus constitutes an important challenge. Instruments exist which can measure particle surface area concentration in real-time, but it is not known how well they perform when faced with polydisperse nanostructured aerosols. In this study, the response functions of three commercially available instruments based on diffusion charging (LQ1-DC, Matter Engineering; NSAM, TSI model 3550; AeroTrak? 9000, TSI) were measured for monodisperse aerosols of four different chemical natures with particles ranging in size from 15 to 520?nm. Our results show good agreement between the experimental and theoretical response functions for the three instruments studied. In addition, no significant effect of the chemical nature, density or particle morphology was revealed. Instrument response was also tested with polydisperse aerosols. For these aerosols, discrepancies were observed between measurements and calculated concentrations based on response function and particle number size distribution. Relative differences varied between ?60 and +55?% with an average value of ?20?%. These differences may be explained by different factors; among them, the existence of a distribution of electrical charges on particles can lead to identical signals measured, and differential diffusion charging performance might lead to concentration-dependent response. 相似文献