Estimation of quality factors by energy ratio method

The quality factor Q, which reflects the energy attenuation of seismic waves in subsurface media, is a diagnostic tool for hydrocarbon detection and reservoir characterization. In this paper, we propose a new Q extraction method based on the energy ratio before and after the wavelet attenuation, named the energy-ratio method（ERM）. The proposed method uses multipoint signal data in the time domain to estimate the wavelet energy without invoking the source wavelet spectrum, which is necessary in conventional Q extraction methods, and is applicable to any source wavelet spectrum; however, it requires high-precision seismic data. Forward zero-offset VSP modeling suggests that the ERM can be used for reliable Q inversion after nonintrinsic attenuation（geometric dispersion, refl ection, and transmission loss） compensation. The application to real zero-offset VSP data shows that the Q values extracted by the ERM and spectral ratio methods are identical, which proves the reliability of the new method.

Interval attenuation estimation from prestack seismic data:A case study from the Arabian Peninsula

Accurately estimated interval attenuation(1/Q)values have several applications,such as in quantitative interpretation and seismic resolution enhancement.Although Q values can be estimated by measuring the spectral ratio between seismic reflections from a target and a reference reflector,the results are influenced by factors such as overburden inhomogeneities.Here,we quantitatively analyze the overburden influence on interval Q estimations using the spectral ratio method,time-space domain prestack Q inversion(PSQI),andτ-p domain PSQI.We compare these three methods using a synthetic dataset and a field dataset acquired onshore the Arabian Peninsula.Synthetic seismic gathers are generated from a three-layer model with a low-Q inclusion in the first layer to mimic overburden inhomogeneity.The fi eld data are preconditioned image gathers from a producing oil fi eld.The synthetic data test shows that the small low-Q body produces a considerable error in estimated Q values.The smallest error(i.e.,13.3%)is in theτ-p domain PSQI result.Theoretically,τ-p domain PSQI could obtain more accurate Q values when there are overburden infl uences because of the simultaneous inversion scheme and the application in theτ-p domain.The fi eld data application also illustrates that theτ-p domain PSQI produces reasonable interval Q values.Our measured Q values are also comparable with the Q values estimated from hydrocarbon saturated carbonate reservoirs.

Theoretical Analysis of Solidly Mounted Film Bulk Acoustic Resonator with Nanocrystalline Diamond as High Impedance Material of Bragg Reflector

In this paper,a solidly mounted resonator(SMR)was designed with nanocrystalline diamond(NCD)as the high acoustic impedance material of Bragg reflector to improve the quality.We used Mathcad to investigate the effect of the Bragg reflector on the performance of the SMR,as well as the influence of different materials and the number of layers of Bragg reflector on the quality factor Q.Results show that the Bragg reflector could reduce energy loss effectively,and the higher the impedance of the high acoustic impedance layer,the better the SMR.The parasitic factors of the SMR using two high acoustic impedance materials,tungsten(W)and NCD,were also simulated by an Advanced Design System(ADS)using the Mason model.It was found that the parasitic effect caused by metal would significantly decrease the Q factor of the SMR.In the frequency range below 6 GHz,within which the SMR works normally,NCD performed better than W.Therefore,NCD is a better choice of high acoustic impedance material in the design of the SMR,with improved quality at high frequency and low loss.The optimum number of layers of Bragg reflector is 6.

Study on the Inelastic Attenuation Coefficient,Site Response and Source Parameters in the Southeast Area of Gansu Province

Using digital seismograms recorded by the Gansu digital seismic network, the inelastic attenuation coefficient is calculated based on a genetic algorithm and the method proposed by Atkinson. Then, the site response and source parameters are investigated by the Moya method. The inversion results indicate the frequency-dependent inelastic attenuation, Q value, in the southeastern Gansu is estimated as Q （f） ： 404.2f^0.264 . Except for the Tianshui station, the site responses of the other stations do not show significant amplifications, which is consistent with their basement on rocks. The stress drops of all 39 earthquakes range between 1 × 10^5 and 7 × 10^6 Pa. We also found the dependence of corner frequency on seismic moment and seismic magnitude.

A high Q terahertz asymmetrically coupled resonator and its sensing performance

A terahertz asymmetrically coupled resonator （ACR） consisting of two different split ring resonators （SRRs） was designed. Using finite difference time domain （FDTD）, the transmission of ACR and its refractive-index- based sensing performaance were simulated and analyzed. Results show that the ACR possesses a sharp coupled transparent peak or high quality factor （Q）, its intensity and bandwidth can be easily adjusted by spacing the two SRRs. Furthermore, the resonator exhibits high sensitivity of 75 GHz/RIU and figure of merit （FOM） of 4.4, much higher than the individual SRR sensors. The ACR were fabricated by using laser-induced and chemical non-electrolytic plating with copper on polyimide substrate, the transmission of which measured by terahertz time-domain spectroscopy system is in good agreement with simulations.

High Q,high frequency,high overtone bulk acoustic resonator with ZnO films

Bulk acoustic wave resonators with piezoelectric films have been widely explored for the small size and high quality factor （Q） at GHz. This paper describes a high overtone bulk acoustic resonator （HBAR） based on AI/ZnO/AI sandwich layers and c-axis sapphire substrate. ZnO film with high quality c-axis orientation has been obtained using DC magnetron sputtering. The fabricated HBAR presents high Q at the multiple resonances from a 0.5-4.0 GHz wide band with a total size （including the contact pads） of 0.6 mm×0.3 mm×0.4 mm, The device exhibits the best acoustic coupling at around 2.4 GHz, which agrees with the simulation results based on the one-dimensional Mason equivalent circuit model. The HBAR also demonstrates Q values of 30 000, 25 000, and 6500 at 1.49, 2.43, and 3.40 GHz, respectively. It is indicated that the HBAR has potential applications for the low phase noise high frequency oscillator or microwave signal source.

The effect of grid shape on the properties of transparent conductive films based on flexographic printing

The effect of grid shape on the properties of transparent conductive films(TCFs) is theoretically analyzed and experimentally verified. The light transmittance by three types of grid shapes: triangle, square and hexagon have been theoretically calculated and simulated. It was found that hexagonal grid unit has the highest light transmittance limit under the practical lattice parameters and its decrease in light transmittance caused by the increase of line width in printing process is the least. The grid of three different shapes with same theoretical transmittance is fabricated through flexographic printing. The result shows that the actual light transmittance of the printed TCFs is lower than its theoretical value because of the inevitable width increase of printed grid lines, with slight difference between the three shapes. However, it is greatly different in terms of conductivity, leading to variation in the quality factor Q(defined as the ratio of light transmittance to total resistance) which represents the performance of TCFs. The Q of hexagonal grid(6.04) is the highest, which is 21% higher than that of the square grid.

A review: aluminum nitride MEMS contour-mode resonator

Over the past several decades, the technology of micro-electromechanical system（MEMS） has advanced. A clear need of miniaturization and integration of electronics components has had new solutions for the next generation of wireless communications. The aluminum nitride（AlN） MEMS contour-mode resonator（CMR）has emerged and become promising and competitive due to the advantages of the small size, high quality factor and frequency, low resistance, compatibility with integrated circuit（IC） technology, and the ability of integrating multi-frequency devices on a single chip. In this article, a comprehensive review of AlN MEMS CMR technology will be presented, including its basic working principle, main structures, fabrication processes, and methods of performance optimization. Among these, the deposition and etching process of the AlN film will be specially emphasized and recent advances in various performance optimization methods of the CMR will be given through specific examples which are mainly focused on temperature compensation and reducing anchor losses. This review will conclude with an assessment of the challenges and future trends of the CMR.