共查询到20条相似文献,搜索用时 0 毫秒
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According to geometrical acoustics, zones of silence can occurwhen sound waves traverse flows. These zones are not often observedin practice. It is suggested that one reason for this in jetflows is that the sound scattered from the end of the jet-pipepenetrates the zone of silence to an appreciable extent. Theconjecture is confirmed by considering a line source, oscillatingharmonically in time, in the presence of a semi-infinite plateabove which is a shear layer in which the velocity increaseslinearly over a finite distance and then remains constant. Theedge wave is found to be dominant in the zone of silence andto be of the same order of magnitude as the refracted fieldoutside. Refracted rays produced by complex rays in the fluiddo not seem to be as important as the edge rays. The results are developed so as to allow quantitative investigationof more general configurations. 相似文献
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Stevo Stević 《Results in Mathematics》2002,41(3-4):386-393
In this note we investigate the relationship between the following integrals: $$\int_{U}\mid f^{(n)}(z)\mid^{p}\mid f^{(k)}(z)\mid^{q}(1-\mid z\mid )^{np+kq+\alpha}dm\ \ \ {\rm and}\ \ \ \int_{U}\mid f^{\prime}\mid^{p+q}(1-\mid z\mid)^{\alpha}dm$$ where 0 < p,q < ∞, α > ?1, k,n ∈ N ∪{0} and where ? is an arbitrary analytic function on the unit disc U. 相似文献
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研究了在应力自由和刚性固定边界条件下,无能量耗散的均匀、各向同性微极热弹性无限板的轴对称自由振动波的传播,导出了相应的对称和斜对称模态波传播的闭合式特征方程和不同区域的特征方程.对短波的情况,应力自由热绝缘和等温板中对称和斜对称模态波传播的特征方程退化为Rayleigh表面波频率方程.根据导出的特征方程得到了热弹性、微极弹性和弹性板的结果.在对称和斜对称运动中计算了板的位移分量幅值、微转动幅值和温度分布,给出了对称和斜对称模式的频散曲线,并示出了位移分量和微转动幅值和温度分布的曲线.能够发现理论分析和数值结论是非常一致的. 相似文献
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This paper deals with the analytic Feynman integral of functionals on a Wiener space. First the authors establish the existence of the analytic Feynman integrals of functionals in a Banach algebra S_α. The authors then obtain a formula for the first variation of integrals. Finally, various analytic Feynman integration formulas involving the first variation are established. 相似文献
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M. I. Ivanov I. A. Kremer M. V. Urev 《Computational Mathematics and Mathematical Physics》2012,52(3):476-488
Nedelec vector finite elements are used for the numerical solution of a regularized version of the quasi-stationary Maxwell equations written in terms of a scalar and a vector magnetic potential with special calibration taking into account the conductivity of the medium. An optimal energy estimate for the error of the approximate solution in Lipschitz polyhedral domains is established. Numerical results are presented that demonstrate the stability of the method. 相似文献
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R. M. Aron P. Galindo D. Garcí a M. Maestre 《Transactions of the American Mathematical Society》1996,348(2):543-559
A Banach space is known to be Arens regular if every continuous linear mapping from to is weakly compact. Let be an open subset of , and let denote the algebra of analytic functions on which are bounded on bounded subsets of lying at a positive distance from the boundary of We endow with the usual Fréchet topology. denotes the set of continuous homomorphisms . We study the relation between the Arens regularity of the space and the structure of .
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R. A. Bonham 《Studies in Applied Mathematics》1966,45(1-4):331-334
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Luciano M. de Socio Giovanni Gaffuri 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1976,47(1):591-598
A method is proposed for solving the linear integral equations governing some problems of radiation transport. The Fourier transform technique provides the solution as a convolution integral of the kernel and a series expansion in orthogonal functions. Two standard problems were considered as an application and the results given in comparison with those obtained by different approaches. 相似文献
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Luciano M. de Socio Giovanni Gaffuri 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1976,27(5):591-598
A method is proposed for solving the linear integral equations governing some problems of radiation transport. The Fourier transform technique provides the solution as a convolution integral of the kernel and a series expansion in orthogonal functions. Two standard problems were considered as an application and the results given in comparison with those obtained by different approaches.
This work was partially supported by the Consiglio Nazionale delle Ricerche, Gruppo di Fisica Matematica. 相似文献
Riassunto Si propone un metodo per risolvere le equazioni lineari integrali del trasporto radiativo. La tecnica della trasformata di Fourier fornisce la soluzione come integrale di convoluzione del kernel e di uno sviluppo in serie di funzioni ortogonali. Come applicazione si sono risolti due problemi classici ed i risultati si sono confrontati con quelli ottenuti mediante altri procedimenti.
This work was partially supported by the Consiglio Nazionale delle Ricerche, Gruppo di Fisica Matematica. 相似文献
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Yan-fei Wang Qing-hua Ma 《应用数学学报(英文版)》2006,22(3):429-436
The adaptive regularization method is first proposed by Ryzhikov et al. in [6] for the deconvolution in elimination of multiples which appear frequently in geoscience and remote sensing. They have done experiments to show that this method is very effective. This method is better than the Tikhonov regularization in the sense that it is adaptive, i.e., it automatically eliminates the small eigenvalues of the operator when the operator is near singular. In this paper, we give theoretical analysis about the adaptive regularization. We introduce an a priori strategy and an a posteriori strategy for choosing the regularization parameter, and prove regularities of the adaptive regularization for both strategies. For the former, we show that the order of the convergence rate can approach O(||n||^4v/4v+1) for some 0 〈 v 〈 1, while for the latter, the order of the convergence rate can be at most O(||n||^2v/2v+1) for some 0 〈 v 〈 1. 相似文献
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V. G. Samoilenko 《Ukrainian Mathematical Journal》2004,56(2):351-356
For systems in a magnetic field, we investigate the form sum of an infinite-dimensional energy operator perturbed by a potential. We also investigate changes in the spectrum of the energy operator in the case of its perturbation by a potential. 相似文献
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We establish a formula that expresses the value of the density of the Temlyakov-type integral with defining domain of type A in terms of the integral itself by means of a differential operator. We extend this operator connection to the Temlyakov–Bavrin-type integral of order k. Our study bases on the method of linear differential operators with variable coefficients which is developed by A. V. Nelaev. 相似文献
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We present sets of parameterized integral test families over each of the domains [0,∞)2 and (?∞,∞)2, exhibiting various rates of integrand decay, and use these families to compare the performances of the two general-purpose two-dimensional cubature algorithms r2d2lri and Cubpack++ for integration over such nonfinite domains. The data collected for this comparison is helpful in identifying the respective advantages and disadvantages of the strategies adopted by the two algorithms when dealing with nonfinite domains. 相似文献
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We investigate the relationship between the norm N
G() of infinite subgroups of an infinite group G and the structure of this group. We prove that N
G() is Abelian in the nonperiodic case, and a locally finite group is a finite extension of a quasicyclic subgroup if N
G() is a non-Dedekind group. In both cases, we describe the structure of the group G under the condition that the subgroup N
G() has finite index in G. 相似文献
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本文提出了弹体冲击靶板时弹靶接触面的运动速度和接触面上所受法向应力的解析表达式.这些解析式是著名的Hopkins-Kolsky理论的推广.由于弹道极限速度在工程实际中的重要性,本文也给出了弹道极限速度的解析表达式.本文并证明了,作用在与靶板相接触的冲塞圆柱面上的沿板厚方向的剪应力,与板厚方向的坐标无关. 相似文献