EFFECTS OF POROSITY ON SEISMIC ATTENUATION

1994 ◽  
Vol 02 (01) ◽  
pp. 53-69 ◽  
Author(s):  
YUE-FENG SUN ◽  
JOHN T. KUO ◽  
YU-CHIUNG TENG
Keyword(s):  
Quality Factor ◽  
Crack Density ◽  
Seismic Attenuation ◽  
Center Frequency ◽  
Fluid Content ◽  
Intrinsic Attenuation ◽  
Resolution Mapping ◽  
Waveform Change ◽  
Optimization Schemes ◽  
Quality Factor Q

Effects of porosity on the attenuation of wave propagation are studied. The effects of pore fluids and porous structures are significant on changing the shapes of propagating wavelets. The waveform change of a propagating wavelet is much more sensitive to porosity than intrinsic attenuation. The attenuation occurred in natural rocks may largely due to these porous effects in addition to the internal friction of the solid represented by the intrinsic quality factor Q. The waveform of a propagating wavelet is quantitatively associated with attenuation, porosity, and fluid content, and is characterized by three parameters: the porosity ϕ, the quality factor Q, and the center frequency f0. Estimations of attenuation, porosity, and fluid content can be made by optimal wavelet analysis. High-resolution mapping of subsurface structures can be achieved by solving the integral equation with the nonlinear optimization of the time-variant wavelets. The inversion and the optimization schemes have been applied to study the porous sea floor and the crustal axial magma chamber (AMC) on the East Pacific Rise. These results provide porosity, attenuation information, and the highly resolved wave events, for further evaluation of compressional and shear wave velocities and other physical properties such as crack density and aspect ratio.

scholarly journals Fully-Integrated Tunable Q-Enhanced Linear Low Noise Amplifier for Wireless Receivers

2020 ◽  
Vol 9 (3) ◽  
pp. 1762-1766
Keyword(s):  
Quality Factor ◽  
Tuning Range ◽  
Low Noise ◽  
Wireless Receivers ◽  
Center Frequency ◽  
Third Order ◽  
Fully Integrated ◽  
Noise Amplifier ◽  
Quality Factor Q ◽  
Peak Gain

This paper presents the design of a fully-integrated tunable Q-enhanced LNA resonator filter designed to tune the circuit center frequency and quality factor Q. The proposed circuit achieves a 600 MHz 3dB bandwidth tunable center frequency at 2.4 GHz with a 5.5 dB Quality Factor Q tuning range. The proposed circuit utilize a distortion transistor compensator to improve linearity of the circuit. The results show an 18 dBc of third order intermodulation IM3 cancellation. The overall proposed circuit peak gain is 16.5 dB and the minimum NF is 0.94 dB at 2.4 GHz frequency with power consumption of 5.2 mA

scholarly journals Wide Acoustic Bandgap Solid Disk-Shaped Phononic Crystal Anchoring Boundaries for Enhancing Quality Factor in AlN-on-Si MEMS Resonators

Micromachines ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 413 ◽  
Author(s):  
Muhammad Siddiqi ◽  
Joshua Lee
Keyword(s):  
Quality Factor ◽  
Phononic Crystal ◽  
Center Frequency ◽  
Very High Frequency ◽  
Mems Resonators ◽  
Solid Disk ◽  
Cell Topology ◽  
Transmission Measurements ◽  
Quality Factor Q ◽  
Very High

This paper demonstrates the four fold enhancement in quality factor (Q) of a very high frequency (VHF) band piezoelectric Aluminum Nitride (AlN) on Silicon (Si) Lamb mode resonator by applying a unique wide acoustic bandgap (ABG) phononic crystal (PnC) at the anchoring boundaries of the resonator. The PnC unit cell topology, based on a solid disk, is characterized by a wide ABG of 120 MHz around a center frequency of 144.7 MHz from the experiments. The resulting wide ABG described in this work allows for greater enhancement in Q compared to previously reported PnC cell topologies characterized by narrower ABGs. The effect of geometrical variations to the proposed PnC cells on their corresponding ABGs are described through simulations and validated by transmission measurements of fabricated delay lines that incorporate these solid disk PnCs. Experiments demonstrate that widening the ABG associated with the PnC described herein provides for higher Q.

Measures of scale based on the wavelet scalogram with applications to seismic attenuation

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. V111-V118 ◽  
Author(s):  
Hongbing Li ◽  
Wenzhi Zhao ◽  
Hong Cao ◽  
Fengchang Yao ◽  
Longyi Shao
Keyword(s):  
Quality Factor ◽  
Maximum Amplitude ◽  
Seismic Signal ◽  
Seismic Attenuation ◽  
Frequency Resolution ◽  
Center Frequency ◽  
Small Scale ◽  
Wavelet Domain ◽  
Time Frequency ◽  
Scale Shift

The attenuation of seismic signal is usually characterized in the frequency domain using Fourier power spectra and is often usefully characterized by average measures, such as the center frequency or spectral mean. Fourier analysis, however, suffers from time-frequency resolution problems. Wavelet analysis has better time-frequency localization and offers superior spectral decomposition. In this paper, we show that seismic attenuation can be characterized by the scalogram (also called energy density) in the wavelet domain. A single scale encompasses a frequency band. The scalogram relates absorption to peak-scale variations. The peak scale is the scale of maximum amplitude in the scalogram. Seismic attenuation can be estimated directly from the scalogram according to the scale shift of the data and can also be described indirectly by the centroid of scale (the mean of a scalogram). In absorbing media, seismic attenuation increases with frequency, i.e., decreases with scale. In the wavelet domain, small-scale energies of the seismic signal are attenuated more rapidly than are large-scale energies as waves propagate. As a result, both the peak scale and the centroid of the signal’s scalogram increase during propagation. Under the assumption of a frequency-independent [Formula: see text] model, these increases of the peak scale and the centroid of scale are inversely proportional to the quality factor, i.e., a lower quality factor results in an upshift of the peak scale in the scalogram and an increase of the centroid of scale. The peak-scale-shift method can be applied to seismic data with sufficiently broad signal bandwidth. The centroid of scale can be used as an attribute to qualitatively characterize seismic attenuation. Examples of gas detection in both synthetic and field data show the value of this technique.

NÉEL LINES STRUCTURES IN UNIAXIAL FERROMAGNETS WITH QUALITY FACTOR Q > 1

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1947-C8-1948
Author(s):  
J. Miltat ◽  
P. Trouilloud
Keyword(s):  
Quality Factor ◽  
Quality Factor Q

scholarly journals 422 Million intrinsic quality factor planar integrated all-waveguide resonator with sub-MHz linewidth

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Matthew W. Puckett ◽  
Kaikai Liu ◽  
Nitesh Chauhan ◽  
Qiancheng Zhao ◽  
Naijun Jin ◽  
...  
Keyword(s):  
Quality Factor ◽  
High Capacity ◽  
Precision Spectroscopy ◽  
Narrow Linewidth ◽  
Waveguide Resonator ◽  
Environmental Disturbances ◽  
Fiber Communications ◽  
Intrinsic Quality ◽  
Quality Factor Q ◽  
Quantum Photonics

AbstractHigh quality-factor (Q) optical resonators are a key component for ultra-narrow linewidth lasers, frequency stabilization, precision spectroscopy and quantum applications. Integration in a photonic waveguide platform is key to reducing cost, size, power and sensitivity to environmental disturbances. However, to date, the Q of all-waveguide resonators has been relegated to below 260 Million. Here, we report a Si3N4 resonator with 422 Million intrinsic and 3.4 Billion absorption-limited Qs. The resonator has 453 kHz intrinsic, 906 kHz loaded, and 57 kHz absorption-limited linewidths and the corresponding 0.060 dB m−1 loss is the lowest reported to date for waveguides with deposited oxide upper cladding. These results are achieved through a careful reduction of scattering and absorption losses that we simulate, quantify and correlate to measurements. This advancement in waveguide resonator technology paves the way to all-waveguide Billion Q cavities for applications including nonlinear optics, atomic clocks, quantum photonics and high-capacity fiber communications.

Study of Inductance-Coupling-RFID Tag's Quality Factor

2013 ◽  
Vol 722 ◽  
pp. 198-201
Author(s):  
Cai Feng Liu ◽  
Fu Gui Yan ◽  
Di Feng Lu ◽  
Yang Mei
Keyword(s):  
Quality Factor ◽  
Simulation Analysis ◽  
Influence Factors ◽  
Rfid Tags ◽  
Space Thickness ◽  
Manufacturing Quality ◽  
Length Width ◽  
Quality Factor Q

To improve the read performance of RFID tags,improve the quality factor is very important. Firstly,from theory and practical, confirmed that quality factor Q is very important for RFID tags,a higher Q means the tag could have a good performance. Then,through calculations and simulation,analysis the influence factors of Q. With simulation figures show that length, width, space, thickness of the tags coil all affect the Q,but when manufacturing of tags , the control of manufacturing quality and accuracy is very difficultly. Finally, shows many figures about tags manufacturing quality and accuracy of manufacturing which have lower Q and badly read performance.

scholarly journals NGTS-10b: the shortest period hot Jupiter yet discovered

2020 ◽  
Vol 493 (1) ◽  
pp. 126-140 ◽  
Author(s):  
James McCormac ◽  
Edward Gillen ◽  
James A G Jackman ◽  
David J A Brown ◽  
Daniel Bayliss ◽  
...  
Keyword(s):  
Quality Factor ◽  
Orbital Period ◽  
Next Generation ◽  
Short List ◽  
Stellar Activity ◽  
Tidal Interactions ◽  
Solar Metallicity ◽  
Quality Factor Q ◽  
Hot Jupiter

ABSTRACT We report the discovery of a new ultrashort period (USP) transiting hot Jupiter from the Next Generation Transit Survey (NGTS). NGTS-10b has a mass and radius of $2.162\, ^{+0.092}_{-0.107}$ MJ and $1.205\, ^{+0.117}_{-0.083}$ RJ and orbits its host star with a period of 0.7668944 ± 0.0000003 d, making it the shortest period hot Jupiter yet discovered. The host is a 10.4 ± 2.5 Gyr old K5V star (Teff = 4400 ± 100 K) of Solar metallicity ([Fe/H] = −0.02 ± 0.12 dex) showing moderate signs of stellar activity. NGTS-10b joins a short list of USP Jupiters that are prime candidates for the study of star–planet tidal interactions. NGTS-10b orbits its host at just 1.46 ± 0.18 Roche radii, and we calculate a median remaining inspiral time of 38 Myr and a potentially measurable orbital period decay of 7 s over the coming decade, assuming a stellar tidal quality factor $Q^{\prime }_{\rm s}$ =2 × 107.

Multichannel quality factor Q estimation

2019 ◽  
Vol 218 (1) ◽  
pp. 655-665 ◽  
Author(s):  
Yangkang Chen
Keyword(s):  
Quality Factor ◽  
Quality Factor Q
Sign in / Sign up

Export Citation Format

Share Document