The effect of improved, low‐frequency bandwidth in full‐wave form inversion for velocity

2009 ◽  
Author(s):  
Steve Kelly ◽  
Jaime Ramos‐Martinez ◽  
Boris Tsimelzon
Keyword(s):  
Low Frequency ◽  
Wave Form ◽  
Frequency Bandwidth ◽  
Full Wave

scholarly journals Design and Modeling of New UWB Metamaterial Planar Cavity Antennas with Shrinking of the Physical Size for Modern Transceivers

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Mohammad Alibakhshi Kenari
Keyword(s):  
Transmission Lines ◽  
Patch Antenna ◽  
Patch Antennas ◽  
Frequency Bandwidth ◽  
Left Handed ◽  
Full Wave ◽  
Radiation Properties ◽  
Unit Cells ◽  
Constitutive Parameters ◽  
Large Frequency

A variety of antennas have been engineered with MTMs and MTM-inspired constructs to improve their performance characteristics. This report describes the theory of MTMs and its utilization for antenna's techniques. The design and modeling of two MTM structures withε-μconstitutive parameters for patch antennas are presented. The framework presents two novel ultrawideband (UWB) shrinking patch antennas filled with composite right-/left-handed transmission line (CRLH-TL) structures. The CRLH-TL is presented as a general TL possessing both left-handed (LH) and right-handed (RH) natures. The CRLH-TL structures enhance left-handed (LH) characteristics which enable size reduction and large frequency bandwidth. The large frequency bandwidth and good radiation properties can be obtained by adjusting the dimensions of the patches and CRLH-TL structures. This contribution demonstrates the possibility of reducing the size of planar antennas by using LH-transmission lines. Two different types of radiators are investigated—a planar patch antenna composed of fourO-formed unit cells and a planar patch antenna composed of sixO-shaped unit cells. A CRLH-TL model is employed to design and compare these two approaches and their realization with a varying number ofL-Cloaded unit cells. Two representative antenna configurations have been selected and subsequently optimized with full-wave electromagnetic analysis. Return loss and radiation pattern simulations of these antennas prove the developed concept.

scholarly journals Acoustic Emission Wavelet Analysis of Filament Wound Composite Tube Fatigue Damage Process

2015 ◽  
Vol 9 (1) ◽  
pp. 214-219 ◽  
Author(s):  
Su Hua ◽  
Chang Cheng
Keyword(s):  
Acoustic Emission ◽  
Wavelet Transform ◽  
Fatigue Damage ◽  
Frequency Band ◽  
Low Frequency ◽  
High Signal ◽  
Wave Form ◽  
Radial Compression ◽  
Time Frequency ◽  
Emission Signal

This paper performed a radial compression fatigue test on glass fiber winding composite tubes, collected acoustic emission signals at different fatigue damages stages, used time frequency analysis techniques for modern wavelet transform, and analyzed the wave form and frequency characteristics of fatigue damaged acoustic emission signals. Three main frequency bands of acoustic emission signal had been identified: 80-160 kHz (low frequency band), 160-300 kHz (middle frequency band), and over 300kHz (high frequency band), corresponding to the three basic damage modes: the fragmentation of matrix resin, the layered damage of fiber and matrix, and the fracture of cellosilk respectively. The usage of wavelet transform enabled the separation of fatigue damaged acoustic emission signals from interference wave, and the access to characteristics of high signal-noise-ratio fatigue damage.

scholarly journals Classical soft graviton theorem rewritten

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Biswajit Sahoo ◽  
Ashoke Sen
Keyword(s):  
Low Frequency ◽  
Constant Term ◽  
Wave Form ◽  
Null Infinity ◽  
Final State ◽  
Massless Particles ◽  
Retarded Time ◽  
Hard Particles ◽  
State Radiation ◽  
Large Impact Parameter

Abstract Classical soft graviton theorem gives the gravitational wave-form at future null infinity at late retarded time u for a general classical scattering. The large u expansion has three known universal terms: the constant term, the term proportional to 1/u and the term proportional to ln u/u2, whose coefficients are determined solely in terms of the momenta of incoming and the outgoing hard particles, including the momenta carried by outgoing gravitational and electromagnetic radiation produced during scattering. For the constant term, also known as the memory effect, the dependence on the momenta carried away by the final state radiation / massless particles is known as non-linear memory or null memory. It was shown earlier that for the coefficient of the 1/u term the dependence on the momenta of the final state massless particles / radiation cancels and the result can be written solely in terms of the momenta of the incoming particles / radiation and the final state massive particles. In this note we show that the same result holds for the coefficient of the ln u/u2 term. Our result implies that for scattering of massless particles the coefficients of the 1/u and ln u/u2 terms are determined solely by the incoming momenta, even if the particles coalesce to form a black hole and massless radiation. We use our result to compute the low frequency flux of gravitational radiation from the collision of massless particles at large impact parameter.

Detection of Transformer Faults Using Frequency-Response Traces in the Low-Frequency Bandwidth

2014 ◽  
Vol 61 (9) ◽  
pp. 4971-4978 ◽  
Author(s):  
Wilder Herrera Portilla ◽  
Guillermo Aponte Mayor ◽  
Jorge Pleite Guerra ◽  
Carlos Gonzalez-Garcia
Keyword(s):  
Frequency Response ◽  
Low Frequency ◽  
Frequency Bandwidth

Period doubling of azimuthal oscillations on a non-neutral magnetized electron column

1985 ◽  
Vol 33 (1) ◽  
pp. 59-69 ◽  
Author(s):  
R. W. Boswell ◽  
M. J. Giles
Keyword(s):  
Electron Beam ◽  
Low Frequency ◽  
Period Doubling ◽  
Wave Form ◽  
Low Density ◽  
Slow Mode ◽  
Good Qualitative Agreement ◽  
Rigid Rotator ◽  
Perturbation Amplitude ◽  
Beam Experiment

We investigate the low-frequency azimuthal oscillations on a non-neutral magnetized electron column of very low density. A perturbation analysis of the slow mode of the rigid rotator equilibrium is developed to illustrate the nature of large-amplitude fundamental-mode oscillations. The results of this theoretical analysis show two important characteristics: firstly, as the perturbation amplitude is increased the wave form ceases to be purely sinusoidal and shows period doubling. Secondly, above a certain threshold, all harmonics of the wave grow and the wave breaks. The results of the former are compared with a simple electron beam experiment and are found to be in good qualitative agreement.

Full Wave Form Inversion from Topography — The Husky Experience Revisited

2012 ◽  
Author(s):  
Youngseo Kim ◽  
R. Phillip Bording ◽  
Larry R. Lines ◽  
Changsoo Shin
Keyword(s):  
Wave Form ◽  
Full Wave
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