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We deduce two necessary and sufficient conditions for a diffeomorphism $f : M \to \overline{M}$ of a Riemannian manifold (M,g) onto a Riemannian manifold $(\overline{M},\bar g)$ to be harmonic. Using the representation theory of groups, we define in an intrinsic way seven classes of such harmonic diffeomorphisms and partly describe the geometry of each class. 相似文献
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We prove that a vector field X on a compact Riemannian manifold (M, g) with Levi-Cività connection ? is an infinitesimal isometry if and only if it satisfies the system of differential equations: trace g (L X ?) = 0, trace g (L X Ric) = 0, where L X is the Lie derivative in the direction of X and Ric is the Ricci tensor. It follows from the second assertion that the Ricci soliton on a compact manifold M is trivial if its vector field X satisfies one of the following two conditions: trace g (L X Ric) ≤ 0 or trace g (L X Ric) ≥ 0. 相似文献
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One of the present authors defined the infinitesimal harmonictransformation in a Riemannian manifold. This paperis devoted to the study of the local and global geometryinfinitesimal harmonic transformations. 相似文献
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L. R. Bitner V. A. Vedernikov T. I. Danilina G. V. Manyakhina Z. A. Shandra 《Russian Physics Journal》1976,19(12):1535-1538
The mechanism by which electron — ion bombardment affects the growth of a silicon nitride film obtained by reactive sputtering in an apparatus based on a Penning discharge is investigated. The temperature and the degree of irradiation of the substrate are determined as functions of the distance from the substrate to the aperture in the anode. It is established that the presence or absence of bombardment leads to a difference in the formation of reactively sputtered silicon nitride films.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 11–15, December, 1976.The authors thank Yu. E. Kreindel' for his interest in the work and for useful discussions. 相似文献
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