Laboratory evidence for Krauklis-wave resonance in fractures and implications for seismic coda wave analysis

Geophysics ◽  
2016 ◽  
Vol 81 (6) ◽  
pp. T285-T293 ◽  
Author(s):  
Pei-Ju Rita Shih ◽  
Marcel Frehner
Keyword(s):  
Analytical Solution ◽  
Resonance Frequency ◽  
Quality Factor ◽  
Laboratory Data ◽  
Rock Properties ◽  
Coda Wave ◽  
Resonance Effects ◽  
Seismic Coda ◽  
Major Interest ◽  
Over Time

Krauklis waves are of major interest because they can lead to resonance effects in fluid-filled fractures. This resonance is marked by seismic signals with a dominant signature frequency, which may reveal fracture-related rock properties. In our laboratory study, we used homogeneous Plexiglas samples containing a single well-defined (i.e., manufactured) fracture. We recorded the signals obtained from propagating ultrasonic P- and S-waves (source frequency: 0.6, 1, and 2.25 MHz) along a sample without a fracture and samples with a fracture with different inclination angles of 30°, 45°, and 60° with respect to the short axis. The experimental results obtained from an incident S-wave confirmed that the presence of the fracture led to resonance effects at frequencies lower than the dominant source frequency, which slowly decayed over time in the recorded seismic coda after the first arrival. The resonance frequency was independent of the fracture orientation and the source frequency. We have interpreted this narrow-banded coda signal as a resonance in the fracture, and the frequency at which this occurred was an intrinsic property of the fracture size and elastic properties. To verify our laboratory results, we used an analytical solution, which provided a relationship between the fracture width, fracture length, resonance frequency, and temporal quality factor (i.e., exponential decay over time). The temporal quality factor obtained from our laboratory data agreed very well with the analytical solution. Hence, we concluded that the observed signature frequency (approximately 0.1 MHz) in the seismic coda was indeed a resonance effect. Finally, we have developed possible applications on the reservoir scale to infer fracture-related properties based on seismic coda analysis.

Investigation on Resonance Effects of Closely Resonating Nano-Pillars Attached to SAW Resonator

2011 ◽  
Vol 403-408 ◽  
pp. 1183-1187
Author(s):  
N. Ramakrishnan ◽  
Harshal B. Nemade ◽  
Roy Paily Palathinkal
Keyword(s):  
Acoustic Wave ◽  
Resonance Frequency ◽  
Frequency Shift ◽  
Fem Simulation ◽  
Mass Loading ◽  
Loading Effect ◽  
Resonance Effects ◽  
Additional Information ◽  
Resonance Frequency Shift ◽  
Small Change

Surface acoustic wave (SAW) sensors form an important class of micro sensors in the microelecto mechanical systems (MEMS) family. Mass loading effect of a sensing medium is one of the prime sensing principles in SAW sensors. Recently we reported mass loading effect of high aspect ratio nano-pillars attached to a SAW resonator. We observed increase in resonance frequency of the SAW resonator in addition to the general mass loading characteristics. We concluded that when the resonance frequency of the pillar is equal to the SAW resonator frequency, the resonance frequency shift caused by mass loading of pillar tends to a negligible value. When such resonating pillars are used as sensing medium in SAW sensors, even a very small change in the dimension of the pillar will offer significant resonance frequency shift. Accordingly, high sensitive SAW sensors can be developed. However in practice it’s quite difficult to manufacture nano-pillars with accurate dimensions such that they resonate with SAW resonator. There is more probability that the pillars may closely resonate with SAW device and offer mass loading. In the present work we have extended our earlier work and performed finite element method (FEM) simulation to study the insight physics of the closely resonating pillars and their effects on acoustic wave propagating on SAW substrate. In this paper we present the discussion on the resonance effects of typical closely resonating pillars on resonance frequency spectrum of the SAW resonator and observations in the pressure wave at the contact surface of the pillar and SAW resonator substrate. It is observed that when the nano-pillars closely resonate with SAW resonator, the pillar oscillations combine with waves propagating in the substrate and introduce beat frequencies. The results and discussion of this paper adds additional information in designing SAW based coupled resonating systems.

scholarly journals Modeling neutral viral mutations in the spread of SARS-CoV-2 epidemics

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0255438
Author(s):  
Vitor M. Marquioni ◽  
Marcus A. M. de Aguiar
Keyword(s):  
Population Genetics ◽  
Analytical Solution ◽  
Genetic Distance ◽  
Mean Field ◽  
Neutral Evolution ◽  
Genetic Evolution ◽  
Epidemic Spreading ◽  
Different Strains ◽  
Over Time ◽  
Good Agreement

Although traditional models of epidemic spreading focus on the number of infected, susceptible and recovered individuals, a lot of attention has been devoted to integrate epidemic models with population genetics. Here we develop an individual-based model for epidemic spreading on networks in which viruses are explicitly represented by finite chains of nucleotides that can mutate inside the host. Under the hypothesis of neutral evolution we compute analytically the average pairwise genetic distance between all infecting viruses over time. We also derive a mean-field version of this equation that can be added directly to compartmental models such as SIR or SEIR to estimate the genetic evolution. We compare our results with the inferred genetic evolution of SARS-CoV-2 at the beginning of the epidemic in China and found good agreement with the analytical solution of our model. Finally, using genetic distance as a proxy for different strains, we use numerical simulations to show that the lower the connectivity between communities, e.g., cities, the higher the probability of reinfection.

Seismic coda Q and scaling law of the source spectra at the Aeolian Islands, southern Italy

1983 ◽  
Vol 73 (1) ◽  
pp. 97-108
Author(s):  
E. Del Pezzo ◽  
F. Ferulano ◽  
A. Giarrusso ◽  
M. Martini
Keyword(s):  
Southern Italy ◽  
Scaling Law ◽  
Coda Wave ◽  
Corner Frequency ◽  
Volcanic Complex ◽  
Coda Q ◽  
Aeolian Islands ◽  
Scaling Properties ◽  
Linear Pattern ◽  
Seismic Coda

abstract The model developed by Aki and Chouet for the coda wave generation and propagation has been used to calculate the quality factor Q for the zone of the Aeolian Islands, southern Italy, in the frequency range of 1 to 12 Hz, and the scaling properties of the seismic spectrum in the magnitude range of 0.4 to 4.7. The Q found for the Aeolian area has a frequency dependence of the form Q = qfv. The absolute values of Q seem to be dependent on the station and location of the seismic events, confirming the strong lateral heterogeneities in the geological structure beneath the Aeolian Arc. A temporal variation has been noted in the Q calculated at Vulcano station (VPL) in a period of 3 weeks soon after the occurrence of a main shock of ML = 5.5 located near the station. The scaling behavior of this sequence is similar to that obtained in two areas of California and one portion of Japan, with a corner frequency that remains constant with an increasing seismic moment between magnitudes 1 and 4. It differs substantially from the scaling properties of the Hawaian earthquakes that show a linear pattern, without an increase of the stress drop with magnitude. The fact that Vulcano is an active volcano seems not to influence the scaling properties of the seismic sequence localized very near it. It probably indicates that the aftershocks used for calculating the scaling law are generated out of the volcanic complex Lipari-Vulcano, in a zone with a good capability of accumulating the stress.

Conclusion

2020 ◽  
pp. 249-258
Author(s):  
Emily J. Charnock
Keyword(s):  
Interest Groups ◽  
Political Development ◽  
Party System ◽  
Political Life ◽  
Party Change ◽  
Policy Issues ◽  
Specific Policy ◽  
Major Interest ◽  
Ideological Dimension ◽  
Over Time

This conclusion highlights the importance of PACs in twentieth-century American political development. The emergence of partisan PACs, initially formed by major interest groups, played an important and neglected role in fostering the polarization of American politics—a phenomenon that has raised concern in recent decades. Seeking to reconfigure party politics around specific policy issues—more broadly, to realign the party system along an ideological dimension of conflict—these PACs helped make the parties more distinct and more deeply divided over time. They did so via electoral tools and tactics that are now ubiquitous in political life but are rarely probed in scholarship. A focus on PACs thus illuminates the very mechanisms through which party change was brought about, as much as its wider meaning. The book concludes with a consideration of contemporary US politics, in which PACs continue to play a prominent role.

scholarly journals Wear of elastic tube with nonuniform coating by rigid bush

2020 ◽  
Vol 162 ◽  
pp. 02002 ◽  
Author(s):  
Kirill E. Kazakov
Keyword(s):  
Analytical Solution ◽  
Special Form ◽  
Special Functions ◽  
Contact Stresses ◽  
Elastic Tube ◽  
Analytical Representation ◽  
Standard Methods ◽  
In Series ◽  
Separate Factor ◽  
Over Time

This article is devoted to the statement and construction of analytical solution of the wearcontact problem for a rigid bush and elastic pipe with a coating in the case when the coating is nonuniform. The presence of nonuniformity leads us to the necessity of constructing a solution in a special form over special functions, since standard methods does not allow us to effectively take into account the complex properties of the coating. Analytical representation for contact stresses under the bush is presented in series with separate factor, which connect with complex properties of coating. This allows provide effective calculation even if these properties are described by rapidly changing or discontinuous functions. It is also shown that contact stresses will be negligible over time.

scholarly journals Dynamic Responses of Electrically Driven Quartz Tuning Fork and qPlus Sensor: A Comprehensive Electromechanical Model for Quartz Tuning Fork

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2686
Author(s):  
Manhee Lee ◽  
Bongsu Kim ◽  
Sangmin An ◽  
Wonho Jhe
Keyword(s):  
Resonance Frequency ◽  
Quality Factor ◽  
Tuning Fork ◽  
Quartz Tuning Fork ◽  
Dynamic Responses ◽  
Peak Amplitude ◽  
Quantitative Prediction ◽  
Dynamic Features ◽  
Electromechanical Model ◽  
Different Characteristics

A quartz tuning fork and its qPlus configuration show different characteristics in their dynamic features, including peak amplitude, resonance frequency, and quality factor. Here, we present an electromechanical model that comprehensively describes the dynamic responses of an electrically driven tuning fork and its qPlus configuration. Based on the model, we theoretically derive and experimentally validate how the peak amplitude, resonance frequency, quality factor, and normalized capacitance are changed when transforming a tuning fork to its qPlus configuration. Furthermore, we introduce two experimentally measurable parameters that are intrinsic for a given tuning fork and not changed by the qPlus configuration. The present model and analysis allow quantitative prediction of the dynamic characteristics in tuning fork and qPlus, and thus could be useful to optimize the sensors’ performance.

Modeling and electromechanical performance analysis of frequency-variable piezoelectric stack transducers

2020 ◽  
Vol 31 (6) ◽  
pp. 897-910
Author(s):  
Jianjun Wang ◽  
Shuyuan Cai ◽  
Lei Qin ◽  
Donghuan Liu ◽  
Peijun Wei ◽  
...  
Keyword(s):  
Experimental Study ◽  
Performance Analysis ◽  
Analytical Solution ◽  
Resonance Frequency ◽  
Analytical Model ◽  
Dynamic Characteristics ◽  
Active Element ◽  
Underwater Sound ◽  
Layer Number ◽  
Electromechanical Performance

An exact analytical model of frequency-variable piezoelectric stack transducers is proposed, and their dynamic characteristics are studied in this article. Based on the linear piezoelasticity theory, the dynamic analytical solution is first derived, and then its correctness is validated by comparing it with the results of a special example in the previous literature and the ones of the experimental study. The effects of the tuning resistance and the layer number of the active element on the dynamic characteristics are discussed. Numerical results show that tuning the resistance and the layer number of the active element can enable the multi-frequency characteristics of the piezoelectric stack transducers. A proper layer number of the active element can minimize the short-circuited resonance frequency and the open-circuited anti-resonance frequency. These findings provide guidelines to design and optimize the piezoelectric stack transducers, which have promising potential in developing the multi-frequency Langevin transducers for some underwater sound and ultrasonic applications, such as ultrasonic cleaning, ultrasonic chemistry, and sonar radiators.

Natural Analogues: Alamosa River Monzonite Intrusive into Tuffaceous and Andesitic Rocks

1982 ◽  
Vol 15 ◽  
Author(s):  
D. G. Brookins ◽  
M. S. Abashian ◽  
L. H. Cohen ◽  
A. E. Williams ◽  
H. A. Wollenberg ◽  
...  
Keyword(s):  
Fission Product ◽  
Conceptual Models ◽  
Laboratory Data ◽  
Hydrothermal Systems ◽  
Rock Matrix ◽  
Natural Processes ◽  
Natural Analogues ◽  
Time Periods ◽  
Over Time

This project encompasses investigations of selected natural analogues of minerals and rocks containing radioelements and fission-product elements, to ascertain how radionuclides and their daughter elements may migrate from sites of origin in response to long-term natural processes such as heating due to an igneous intrusion, circulating hydrothermal systems, diffusion through the rock matrix, weathering and erosion. Comparison of natural occurrences with conceptual models based on laboratory data will furnish a test of such models over time periods comparable to or longer than those expected for a repository.

scholarly journals Theoretical Study on Internal Forces of Primary Support of Tunnel by considering Time Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Zhuangzhi Yang ◽  
Yuqing Wang ◽  
Lin Song ◽  
Xinyu Wang
Keyword(s):  
Analytical Solution ◽  
Rock Pressure ◽  
Internal Force ◽  
Parameter Method ◽  
Tunnel Construction ◽  
Construction Technology ◽  
Supporting Structure ◽  
Internal Forces ◽  
Primary Support ◽  
Over Time

Understanding the internal force distribution and prejudging the weak part of tunnel supporting structure under complicated construction surroundings have become one of the important measures to ensure the safety of tunnel construction. Based on the initial parameter method and field-monitoring results of surrounding rock pressure, the theory of beam on elastic foundation is employed to derive the analytical solution of primary support internal forces. By combining the monitored data of rock pressure in one tunnel, solution of primary support internal force of a section is back analyzed and weak parts of the primary support are analyzed and evaluated. The results show that, after the tunnel excavation is completed, the internal forces of the primary support of the tunnel arch grow larger over time. When θ > 1.0, the internal forces change greatly. The internal force of the primary support decreased to different extents within 2 days after the primary support was applied and then gradually increased over time. Considering the situationality and changeability of the tunnel construction process, the analytical solution for the primary support internal forces of a multicenter arch tunnel proposed in this paper has a strong feasibility in tunnel construction. The conclusions obtained here could provide theoretical support for the design of supporting structure and the optimization of tunnel construction technology.

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