共查询到20条相似文献,搜索用时 218 毫秒
1.
分析气体火花开关的电阻特性是研究开关能量损耗、电弧通道的热等离子过程、开关间隙绝缘恢复及输出脉冲特性的重要基础。基于气体开关的导通机理,建立了开关导通工作的电路模型,给出了与形成线、传输线联通的开关等效电路和开关电流表达式,分析了开关电感、电阻对电流增长(脉冲前沿)的影响。研究结果表明:对于大间距、高电压气体开关,火花电阻是影响开关输出脉冲前沿的主要因素。 相似文献
2.
3.
4.
气体开关是脉冲功率技术中广泛应用的关键部件之一,高功率、高性能气体开关的技术研究及设计具有重要意义,陡化前沿是开关技术研究的重要内容。分析了气体开关的击穿机理和击穿通道的分布规律。对气体开关充分"老练",开关击穿点和击穿通道将相对稳定,实验研究了开关间距和电场对脉冲前沿的影响。击穿电场较低时,减小开关间距有利于陡化脉冲前沿;击穿电场较大时(大于180kV/cm),开关间隙(电感)对输出脉冲前沿的影响减弱,气体开关的击穿电场成为影响输出脉冲前沿的关键因素。研究结果表明,增大开关的击穿场强,是陡化开关脉冲前沿的有效途径。 相似文献
5.
6.
7.
8.
利用SOA中的偏振主态的概念,理论分析了SOA中的偏振旋转的问题,并以此为基础提出了一种基于SOA中偏振旋转的光开关。这种光开关以SOA和偏振分柬器(Polarization Beam Combiner,PBC)为核心元件,利用光在SOA中的偏振旋转实现了光信号的开关,这种光开关具有开关速度快,功率均衡,易集成等优点,实验得到的开关消光比达到24dB以上,开关速度达到20ns。 相似文献
9.
10.
11.
The hyperfine interaction is studied in two different crystal lografic forms of Mn. In the -Mn no magnetic, but a distinct electric quadrupole interaction is found. Effects of heat treatment are discussed. For the -Mn two magnetic field sites are found. Their temperature dependence and dependence on the In concentration are discussed. 相似文献
12.
Tomislav Ivezić 《Foundations of Physics Letters》1999,12(6):507-531
In this paper the physical systems consisting of relatively moving subsystems are considered in the true transformations relativity. It is found in a manifestly covariant way that there is a second-order electric field outside stationary current-carrying conductor. It is also found that there are opposite charges on opposite sides of a square loop with current and these charges are invariant charges. 相似文献
13.
In this paper, we address the problem of evaluating the acoustic attenuation of "difficult" media, i.e. highly attenuating and scattering media. In a broadband, through transmission setup, the signals acquired from such media are characterized by a poor signal-to-noise ratio. Therefore, an accurate estimate of attenuation cannot be obtained from a single measurement, but multiple measurements must be combined. Two methods are considered to yield a single estimate of attenuation from multiple measurements. The first one, the "average attenuation" (AA) method, consists in a simple average of individual attenuation estimates. The second one, the "cross spectrum" (CS) method, is based on a system identification approach. In order to evaluate the estimation errors for these methods, ultrasonic signals transmitted through a material of known attenuation were simulated and mixed with both coherent and incoherent noise. In all tests performed, the "CS" method was found to yield the most accurate estimate. This method, combined time delay compensation, is then applied to real signals measured from a concrete slab. A valid frequency band for the attenuation estimate can be defined based on the coherence function. Results from this research are being applied to characterize the degradation of concrete structures using high-frequency ultrasound. 相似文献
14.
本文提出了反常作用的μ荷观点,μ荷不仅是一种反映μ-e禁戒性的量子数,而且是反常作用的承担者。在此观点下,讨论了轻子结构和μ-e质量差,得到了关于轻子结构的一些普遍定理。例如,证明了电子的反常作用和电磁作用形状因子相同等。在讨论轻子结构的基础上,得到了将μ-e质量差和轻子的电磁结构相联系的公式,证明了主要由于电磁作用干涉产生的μ荷-μ矩作用是反常作用自能的主要部分,它是负值,故是电子参与反常作用。利用电子的电磁结构数据能合理地解释μ-e质量差,而后者也提供了有关电子电磁结构的进一步知识。 相似文献
15.
《中国物理 B》2015,(8)
Based on the B-spline basis method, the properties of the helium atom confined inside an endohedral environment,such as buckminster fullerene, are studied. In our calculations, the endohedral environment is a parabolic potential well. In this situation, the phenomenon of "mirror collapse" is exhibited for energy levels of a confined helium atom. The "giant resonance" of oscillator strength of the dipole transition emerges with the variation of depth of the confining well. The physical mechanisms of these phenomena are analyzed in this paper. 相似文献
16.
>Vidal Alonso Salvatore De Vincenzo 《International Journal of Theoretical Physics》2000,39(6):1483-1498
The problem of a relativistic free particle on a line with a hole, which ischaracterized in terms of boundary conditions for a one-dimensional DiracHamiltonian perturbed at one point, is reviewed. We show that the generalfour-parameter family of point interactions earlier obtained by Falkensteiner andGrosse can be written in two forms: In one of them three subfamilies of boundaryconditions are obtained. In the nonrelativistic limit one of these subfamiliescoincides with those given by Carreau et al. and Carreau. In the other form, threesubfamilies of boundary conditions are also obtained, two of which coincide withthose studied by Benvegnu;ag and Dabrowski. In the nonrelativistic limit all thesesubfamilies coincide with those studied by Albeverio et al. The most generalsubfamilies for which the Dirac Hamiltonian is invariant under space inversionP as well as under time reversal T and PT are obtained. Only these subfamiliesrepresent delta-type Dirac point interactions. Typical relativistic andnonIrelativistic boundary conditions are therein included. 相似文献
17.
G. S. Hall 《General Relativity and Gravitation》1990,22(2):203-215
A geometrical discussion of special conformal vector fields in space-time is given. In particular, it is shown that if such a vector field is admitted, it is unique up to a constant scaling and the addition of a homothetic or a Killing vector field. In the case when the gradient of the conformal scalar associated with is non-null it is shown that other homothetic and affine symmetries are necessarily admitted by the space-time, that an intrinsic family of 2-dimensional flat submanifolds is determined in the space-time, that is, in general, hypersurface orthogonal and that the space-time, if non-flat, is necessarily (geodesically) incomplete. Other geometrical features of such space-times are also considered. 相似文献
18.
I. A. Kunin 《International Journal of Theoretical Physics》1990,29(11):1167-1176
The fundamental postulate of continuum mechanics states that a body is a three-dimensional differentiable manifold and its motions are diffeomorphisms. Simple thought experiments with cyclic motions of dislocations show that they do not preserve topology (set of neighborhoods). The same is valid for chaotic and turbulent motions with coarse-graining. To describe such motions, kinematics of a generalized continuum mechanics is suggested. Observables are defined operationally in the laboratory system which is not anymore equivalent to the Lagrangian picture. The body is a submanifold of a higher-dimensional space and generalized motions are its diffeomorphisms. In a gauge-theoretic interpretation, the motion is a translational connection with the curvature identified as a dislocation density-flux. 相似文献
19.
Horst G. Müller 《Zeitschrift für Physik B Condensed Matter》1982,47(2):119-127
111In doped Al specimes (c
In1 ppm) were cold worked by extension at 77 K to several amounts of strain. The PAC method was applied to study the trapping of lattice defects at the indium impurities between 77 K and 293 K. From electron irradiation experiments it is known that the In probes are suitable traps for self-interstitials in Al. Since in the present experiment no such effect is observed, it is concluded that by extension at 77 K in Al essentially no freely migrating interstitials are created. Between 110 K and 210 K an increasing fraction of the indium impurities traps a well defined defect. The symmetry axis of the resulting indium-defect-complex is found to point along 111 crystallographic directions. It is proposed that the In impurity traps a divacancy at nearest neighbour sites and relaxes into the open space, thus forming an equilateral triangle of three vacancies in a {111} plane with the In atom in its centre. Reasons for the formation of this complex at rather low annealing temperatures are discussed. 相似文献