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991.
The anti-plane problem of an elliptical inhomogeneity with an interfacial crack in piezoelectric materials is investigated. The system is subjected to arbitrary singularity loads (point charge and anti-plane concentrated force) and remote anti-plane mechanical and in-plane electrical loads. Using the complex variable method, the explicit series form solutions for the complex potentials in the matrix and the inclusion regions are derived. The electroelastic field intensity factors, the corresponding energy release rates and the generalized strain energy density at the cracks tips are then provided. The influence of the aspect ratio of the ellipse, the crack geometry and the electromechanical coupling coefficient on the energy release rate and the strain energy density is discussed and shown in graphs. The results indicate that the energy release rate increases with increment of the aspect ratio of the ellipse and the influence of electromechanical coupling coefficient on the energy release rate is significant. The strain energy density decreases with increment of the aspect radio of the ellipse and it is always positive for the cases discussed. The energy release rate, however, can be negative when both mechanical and fields are applied. 相似文献
992.
Comparative numerical study of laminar heat transfer characteristics of annular tubes with sinusoidal wavy fins has been conducted
both experimentally and numerically with Re = 299–1,475. The uniform heat flux is imposed on the tube outside wall surface.
Two tube materials (copper and stainless steel) are considered. It is found that the fluid temperature profile is not linear
but convex along the flow direction due to the axial heat conduction in tube wall, and the effects of axial heat conduction
on the heat transfer decreases with an increase in Reynolds number or decrease in tube wall thermal conductivity. The axial
distributions of local Nusselt number could reach periodically fully developed after 3–5 cycles. The convectional data reduction
method based on the traditional method should be improved for tube with high thermal conductivity or low Reynolds numbers,
Otherwise, the heat transfer performance of internally finned tube may be underestimated. 相似文献
993.
This work proposes two simple dynamic methods that provide an accurate method for measurement of diffusion coefficients in
building materials. Experimental measurements of moisture diffusion coefficients covered three commonly used building materials
and they were carried out for a range of the relevant parameters, as temperature and relative humidity. The diffusion coefficients
obtained by the two dynamic methods show a deviation comparatively to the steady-sate cup method; however, this variance is
in accordance with the results presented in literature. 相似文献
994.
D. Gilles S. Turck-Chièze G. Loisel L. Piau J.-E. Ducret M. Poirier T. Blenski F. Thais C. Blancard P. Cossé G. Faussurier F. Gilleron J.C. Pain Q. Porcherot J.A. Guzik D.P. Kilcrease N.H. Magee J. Harris M. Busquet F. Delahaye C.J. Zeippen S. Bastiani-Ceccotti 《High Energy Density Physics》2011,7(4):312-319
Opacity is an important ingredient of the evolution of stars. The calculation of opacity coefficients is complicated by the fact that the plasma contains partially ionized heavy ions that contribute to opacity dominated by H and He. Up to now, the astrophysical community has greatly benefited from the work of the contributions of Los Alamos [1], Livermore [2],
[2a]
and
[2b]
and the Opacity Project (OP) [3]. However unexplained differences of up to 50% in the radiative forces and Rosseland mean values for Fe have been noticed for conditions corresponding to stellar envelopes. Such uncertainty has a real impact on the understanding of pulsating stellar envelopes, on the excitation of modes, and on the identification of the mode frequencies. Temperature and density conditions equivalent to those found in stars can now be produced in laboratory experiments for various atomic species. Recently the photo-absorption spectra of nickel and iron plasmas have been measured during the LULI 2010 campaign, for temperatures between 15 and 40 eV and densities of ∼3 mg/cm3. A large theoretical collaboration, the “OPAC”, has been formed to prepare these experiments. We present here the set of opacity calculations performed by eight different groups for conditions relevant to the LULI 2010 experiment and to astrophysical stellar envelope conditions. 相似文献
995.
Shrideh K. Q. Al‐Omari Dumitru Baleanu 《Mathematical Methods in the Applied Sciences》2019,42(2):541-552
In this article, various convolution theorems involving certain weight functions and convolution products are derived. The convolution theorems we obtain are more general, convenient, and efficient than the complicated convolution theorem of the Hartley transform. Further results involving new variants of generalizations of Fourier and Hartley transforms are also discussed. 相似文献
996.
Queueing Systems - In this paper, we investigate exact tail asymptotics for the stationary distribution of a fluid model driven by the M / M / c queue, which is... 相似文献
997.
Debbie Marie B. Verzosa Maria Alva Q. Aberin Len Patrick Dominic M. Garces 《International Journal of Mathematical Education in Science & Technology》2019,50(5):766-778
This paper presents apps designed to assist students in understanding and developing proofs in geometric theorems. These technologies focus on triangle congruence, triangle similarity and properties of parallelograms. Focus group discussions and initial testing of the apps revealed that the apps offered a more engaging medium for learning proving and were capable of facilitating proof-writing skills in geometry. 相似文献
998.
Croom B.P. Burden D. Jin H. Vonk N.H. Hoefnagels J.P.M. Smaniotto B. Hild F. Quintana E. Sun Q. Nie X. Li X. 《Experimental Mechanics》2021,61(2):395-410
Experimental Mechanics - The quality of Digital Volume Correlation (DVC) full-field displacement measurements depends directly on the characteristics of the X-ray Computed Tomography (XCT)... 相似文献
999.
We extend Morley’s trisector theorem in the plane to an isosceles tetrahedron in three-dimensional space. We will show that the Morley tetrahedron of an isosceles tetrahedron is also isosceles tetrahedron. Furthermore, by the formula for distance in barycentric coordinate, we introduce and prove a general theorem on an isosceles tetrahedron.
相似文献1000.
Free space optics (FSO) has attracted a lot of attention for a variety of applications in telecommunications area, and it is dream of every researcher and telecommunication society to make it a real alternative solution for the last mile problem, to replace fiber optics. FSO is much preferred because of its low maintenance cost and deployment time. FSO with single-beam system is vulnerable to atmospheric attenuation, so to overcome this, a multiple-beam FSO transceiver system has become prominent and is usually used. In this paper, average rain attenuation is evaluated from the collected rain intensity data which are collected for a period of seven months, and implemented in the study concerning results relating link distance, and received optical power of using multiple-beam FSO system in tropical rainy weather. Comparison is made in terms of received optical power, geometrical losses, atmospheric losses, and bit error rate (BER) on using different number of optical beams, based on simulation at data rate of 1 Gb/s. From the results it is clear that the quality of received power is improved by using up to four beams, along with link distance up to 1141.2 m as compared to one-beam, two-beam, and three-beam, with link distances 833.3 m, 991.0 m, 1075.4 m, respectively. 相似文献