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排序方式: 共有80条查询结果,搜索用时 31 毫秒
71.
研究了大型汽轮发电机定子端部固定绕组的压板松动时,位于两侧压板间某段绕组的振动问题.首先,采用分离变量法,给出了发电机运行时定子端部绕组区域的磁感应强度表达式,并给出了绕组所受电磁力及与松动压板间摩擦力的计算式.其次,建立了研究绕组非线性振动问题的力学分析模型,采用多尺度法对主共振情形进行了解析求解,推得了稳态运动下的幅频响应方程,并对定常解的稳定性及分岔奇异性进行了研究,得到了稳定性的判定条件及分岔方程的转迁集.最后,针对工程实际问题进行了计算,给出了相应的幅频响应曲线图,并进行了分析讨论. 相似文献
72.
The low-temperature periodical activation of the catalysts based on the metal complexes of nitrogen-containing carbon is observed
in the course of isopropylbenzene oxidation. The concentration of the surface hydroperoxide groups responsible for the chain
process affects both catalyst deactivation and reactivation. Possible reactions responsible for the deactivation and periodical
activation of the catalyst are considered. 相似文献
73.
D. M. Sedrakyan D. A. Badalyan V. M. Gasparyan A. Zh. Khachatryan 《Journal of Experimental and Theoretical Physics》1997,84(2):317-321
We find the dependence of the ensemble-averaged resistance, 〈ρ
L〉, of a one-dimensional chain consisting of periodically spaced random delta-function potentials of the chain length L, the incident-electron energy, and the chain disorder parameter w. We show that generally the 〈ρ
L〉 vs L dependence can be written as a sum of three exponential functions, two of which tend to zero as L℩∞. Hence the asymptotic expression for 〈ρ
L〉 is always an exponential function of L. Such an expression for 〈ρ
L〉 means that the electronic states are indeed localized and makes it possible (which is important) to find the dependence
of the localization radius on the incident-electron energy and the force with which an electron interacts with the sites of
the chain. We also derive a recurrence representation for 〈ρ
L〉, which proves convenient in numerical calculations.
Zh. éksp. Teor. Fiz. 111, 575–584 (February 1997) 相似文献
74.
75.
D. M. Sedrakian D. A. Badalyan L. R. Sedrakyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2014,49(2):43-49
A problem of finding the energy of ground state of a quantum particle in a nanostructure with axial symmetry is considered. It is assumed that there is a point defect inside the nanostructure, which is given by δ-potential. A transcendent equation, which defines the lowest level of energy of the particle, is obtained. Corresponding formulas are used for calculation of the threshold frequency of interband absorption of light in semiconductor nanocrystals, which are dispersed in transparent dielectric matrix. Absorption spectrum edge dependence on location and power of δ-potential is obtained. It is shown that the effective length of the cylindrical nanocrystal is decreased in case of existence of δ-potential, which leads to increase in the threshold frequency of the optical spectrum of absorption. 相似文献
76.
超声兰姆(Lamb)波在结构缺陷检测方面愈来愈受到重视,但目前Lamb波的应用局限于单信号源激励,单通道接收的方法,容易受到噪声干扰,其后续的信号分析处理也比较复杂。本文旨在采用多通道Lamb波对板状结构中的裂纹进行定量分析与诊断。在铝板的表面凿刻出不同深度的凹槽作为裂纹,通过线阵换能器采集在一定传播距离内的多通道Lamb波信号,并采用二维傅里叶变换分析在不同深度的裂纹下,Lamb波模式能量的变化规律。结果表明,相对于完好铝板中的Lamb波信号,裂纹的存在会使Lamb波发生模式转换现象,并且转换模式能量百分比随裂纹深度的增加而线性增加。其结果为Lamb波评价板状结构中的裂纹状况提供了一种可能的方法。 相似文献
77.
The Landauer resistance ρ
N
L has been generalized to the case of multichannel scattering of a particle by the system of N nonoverlapping random potentials that are localized at the points x
i
(i = 1, 2,..., N) and depend on x − x
i
and y. It has been shown that, in this case, a new resistance ρ
N
L appears, which is an exponential function of N. The recurrence equation for determining the Landauer resistance ρ
N
L has been derived and its solution in the general case has been obtained. 相似文献
78.
We develop a technique to formulate quantum field theory on an arbitrary network, based on different randomly disposed sets of scattering points. We define the R-matrix of the whole network as a product of R-matrices attached to each scattering node. Then an action is formulated for a network in terms of fermionic fields, which allows to calculate the transition amplitudes as Green functions. On so-called bubble and triangle diagrams it is shown that the method produces the same results as the one which uses the generalized star product. The approach allows to extend network models by including multiparticle interactions at the scattering nodes. 相似文献
79.
为方便兰姆波信号分析与模式定征,提出一种将短时傅里叶变换(Short-Time Fourier Transform,STFT)与独立元分析(Independent Component Analysis,ICA)相结合的多模式超声兰姆波识别方法.首先通过STFT将兰姆波时域信号投影至时频域,基于各模式信号在时频域相对独立... 相似文献
80.