An Improved Adaptive Integral Method (AIM) with Far-Field Expansion for Analysis of Microstrip Structures

Spectral boundary integral method for simulating static and dynamic fields from a fault rupture in a poroelastodynamic solid

10.31223/x5jp6j ◽

2021 ◽

Author(s):

Elias Heimisson ◽

Antonio Pio Rinaldi

Keyword(s):

Pore Pressure ◽

Integral Method ◽

Near Field ◽

Boundary Integral ◽

Pressure Response ◽

Boundary Integral Method ◽

P Wave ◽

Computational Time ◽

Far Field ◽

Pore Pressure Response

The spectral boundary integral method is popular for simulating fault, fracture, and frictional processes at a planar interface. However, the method is less commonly used to simulate off-fault dynamic fields. Here we develop a spectral boundary integral method for poroelastodynamic solid. The method has two steps: first, a numerical approximation of a convolution kernel and second, an efficient temporal convolution of slip speed and the appropriate kernel. The first step is computationally expensive but easily parallelizable and scalable such that the computational time is mostly restricted by computational resources. The kernel is independent of the slip history such that the same kernel can be used to explore a wide range of slip scenarios. We apply the method by exploring the short-time dynamic and static responses: first, with a simple source at intermediate and far-field distances and second, with a complex near-field source. We check if similar results can be attained with dynamic elasticity and undrained pore-pressure response and conclude that such an approach works well in the near-field but not necessarily at an intermediate and far-field distance. We analyze the dynamic pore-pressure response and find that the P-wave arrival carries a significant pore pressure peak that may be observed in high sampling rate pore-pressure measurements. We conclude that a spectral boundary integral method may offer a viable alternative to other approaches where the bulk is discretized, providing a better understanding of the near-field dynamics of the bulk in response to finite fault ruptures.

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Accurate decomposition method and identification technology of drag

International Journal of Modern Physics B ◽

10.1142/s0217979220401141 ◽

2020 ◽

Vol 34 (14n16) ◽

pp. 2040114

Author(s):

Jia-Lei Yu ◽

Jing Jin ◽

Chun Shao ◽

Miao Zhang ◽

Tie-Jun Liu

Keyword(s):

Shock Wave ◽

Integral Method ◽

Physical Mechanism ◽

Wave Drag ◽

Irreversible Processes ◽

Viscous Drag ◽

Numerical Dissipation ◽

Far Field ◽

Induced Drag ◽

Field Integral

Aiming at accurate decomposition and identification of drag, the drag prediction technology based on the mid/far-field integral method is developed. The method decomposes the far-field drag into entropy drag and induced drag according to its physical mechanism, and introduces an appropriate entropy correction to eliminate the numerical dissipation by analyzing the influence of the trailing integral section position on the entropy drag calculation. Based on the analysis of thermodynamic reversible processes and irreversible processes, the drag is refined into viscous drag, shock wave drag, induced drag and pseudo-drag. The mid-field integral method is used to calculate the separate contribution of viscous drag, shock wave drag and induced drag by calculating the limited integral domain. Numerical results show that the developed method is feasible in accurately reflecting the physical mechanism and predicting the drag ratio. Thus, it provides a reliable tool for drag reduction of large passenger aircraft.

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Can Radiators Be Really Isotropic?

International Journal of Antennas and Propagation ◽

10.1155/2012/187123 ◽

2012 ◽

Vol 2012 ◽

pp. 1-9 ◽

Cited By ~ 5

Author(s):

H. Matzner ◽

E. Levine

Keyword(s):

Current Density ◽

Integral Method ◽

Function Analysis ◽

Finite Size ◽

Surface Current ◽

Real Space ◽

Far Field ◽

Surface Current Density ◽

Power Radiation ◽

Field Integral

In search for isotropic radiators with reasonable quality Factor (Q), bandwidth, and efficiency, one looks for practical radiators with a typical resonant length of . We present here a Green's function analysis in Fourier of a microstrip element and a far-field integral method in configuration (real) space of single and dual U-shaped elements. Both solutions analytically prove that the power radiation patterns are isotropic in nature (while the thickness and the width tend to zero), although the polarizations are not symmetrical in all cuts. It is also shown that the power isotropic U-shaped radiator, for which the surface current density is infinite, can be replaced by another finite-size radiator, having finite-surface current density, such that its far-field is exactly the same as the far-field of the U-shaped isotropic radiator.

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Possible applications of fraunhofer holography in high resolution electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108258 ◽

1978 ◽

Vol 36 (1) ◽

pp. 222-223 ◽

Cited By ~ 1

Author(s):

N. Bonnet ◽

M. Troyon ◽

P. Gallion

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Transfer Function ◽

Radiation Damage ◽

High Resolution Electron Microscopy ◽

Far Field ◽

Field Region ◽

Crystalline Materials ◽

Resolution Electron ◽

The Ideal

Two main problems in high resolution electron microscopy are first, the existence of gaps in the transfer function, and then the difficulty to find complex amplitude of the diffracted wawe from registered intensity. The solution of this second problem is in most cases only intended by the realization of several micrographs in different conditions (defocusing distance, illuminating angle, complementary objective apertures…) which can lead to severe problems of contamination or radiation damage for certain specimens.Fraunhofer holography can in principle solve both problems stated above (1,2). The microscope objective is strongly defocused (far-field region) so that the two diffracted beams do not interfere. The ideal transfer function after reconstruction is then unity and the twin image do not overlap on the reconstructed one.We show some applications of the method and results of preliminary tests.Possible application to the study of cavitiesSmall voids (or gas-filled bubbles) created by irradiation in crystalline materials can be observed near the Scherzer focus, but it is then difficult to extract other informations than the approximated size.

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