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187 results on '"Mikata Y"'

3. SH-waves in a medium containing a disordered periodic array of cracks

Author

Mikata, Y.

Subjects
Stress analysis (Engineering) -- Research, Shear (Mechanics) -- Research, Eigenvalues -- Analysis, Chebyshev approximation -- Analysis, Fracture mechanics -- Analysis, Science and technology
Abstract

A study investigates an antiplane shear wave (SH-wave) with a disordered periodic array of coplanar cracks, and its dispersion and attenuation in a cracked disorderly medium. The problem is derived for an averaged scattered field, and a quasi-crystalline-like approximation provides the governing singular equation of a singularly averaged crack-opening displacement. An eigenfunction expansion, Chebyschev polynomials, and numerical results are presented.

Published
1995

27. Reflection and transmission by an infinite array of randomly oriented cracks.

Author

Mikata, Y. and Achenbach, J. D.

Abstract

Reflection and transmission of an antiplane shear wave by an infinite array of randomly oriented cracks in an isotropic elastic medium are investigated. The problem has been formulated for an averaged scattered field, and a ''periodization'' technique has been developed to derive the governing singular integral equation for the conditionally averaged crack-opening displacement. The singular integral equation has been solved by splitting the kernel into a singular and a regular part. A point scatterer approximation was introduced for the part containing the regular kernel. The approximation has been checked by comparison with exact results for a deterministic periodic system. By using this approximation, the coherent part of the averaged reflection and transmission coefficients of zeroth order has been calculated for normal incidence, a completely random crack orientation, and various values of the wavenumber and the ratio of crack length and crack-center spacing. The problem was formulated in the context of antiplane shear waves. The results are, however, also applicable to reflection and transmission of acoustic or electromagnetic waves by an array of screens. [ABSTRACT FROM AUTHOR]

Published
1988
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29. Carbonyl Orientation Determines Regio- and Enantioselectivity in 1,2-/1,4-Reduction of an NAD Model Compound

Author

Mikata, Y., Aida, S., and Yano, S.

Abstract

An optically active, axially chiral NAD model compound(1) with a quinoline ring system was reduced by the chiral NADH model compound (4), affording a mixture of 1,2- and 1,4-dihydroquinolines. The carbonyl orientation governs the molecular arrangement in the transition state of the reaction and determines the regio- and enantioselectivity of the product.

Published
2004

38. Stress Field in and Around a Coated Short Fiber in an Infinite Matrix Subjected to Uniaxial and Biaxial Loadings

Author

Mikata, Y. and Taya, M.

Abstract

The stresses induced in and around a coated short-fiber composite are investigated by use of the Boussinesq-Sadowsky stress function. The coated fiber is assumed to consist of two confocal spheroids and it is embedded in an infinite body. The major parameters in this analysis are the fiber aspect ratio, the coating thickness-to-fiber radius ratio, the coating-to-matrix stiffness ratio and the fiber-to-matrix stiffness ratio. It is found in the analysis that the stiffness and thickness of the coating and the fiber aspect ratio have some effect on the stress field in and around the coating in a coated short-fiber composite.

Published
1985
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