scholarly journals Azimuth-, angle- and frequency-dependent seismic velocities of cracked rocks due to squirt flow

Solid Earth ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 855-871
Author(s):  
Yury Alkhimenkov ◽  
Eva Caspari ◽  
Simon Lissa ◽  
Beatriz Quintal
Keyword(s):  
Seismic Wave ◽  
Seismic Waves ◽  
Numerical Study ◽  
Azimuth Angle ◽  
Hydrocarbon Exploration ◽  
Three Dimensions ◽  
Pore Scale ◽  
Frequency Dependent ◽  
Dependent Behavior ◽  
The Impact

Abstract. Understanding the properties of cracked rocks is of great importance in scenarios involving CO2 geological sequestration, nuclear waste disposal, geothermal energy, and hydrocarbon exploration and production. Developing noninvasive detecting and monitoring methods for such geological formations is crucial. Many studies show that seismic waves exhibit strong dispersion and attenuation across a broad frequency range due to fluid flow at the pore scale known as squirt flow. Nevertheless, how and to what extent squirt flow affects seismic waves is still a matter of investigation. To fully understand its angle- and frequency-dependent behavior for specific geometries, appropriate numerical simulations are needed. We perform a three-dimensional numerical study of the fluid–solid deformation at the pore scale based on coupled Lamé–Navier and Navier–Stokes linear quasistatic equations. We show that seismic wave velocities exhibit strong azimuth-, angle- and frequency-dependent behavior due to squirt flow between interconnected cracks. Furthermore, the overall anisotropy of a medium mainly increases due to squirt flow, but in some specific planes the anisotropy can locally decrease. We analyze the Thomsen-type anisotropic parameters and adopt another scalar parameter which can be used to measure the anisotropy strength of a model with any elastic symmetry. This work significantly clarifies the impact of squirt flow on seismic wave anisotropy in three dimensions and can potentially be used to improve the geophysical monitoring and surveying of fluid-filled cracked porous zones in the subsurface.

scholarly journals Azimuth-, angle- and frequency-dependent seismic velocities of cracked rocks due to squirt flow

2019 ◽  
Author(s):  
Yury Alkhimenkov ◽  
Eva Caspari ◽  
Simon Lissa ◽  
Beatriz Quintal
Keyword(s):  
Seismic Wave ◽  
Seismic Waves ◽  
Numerical Study ◽  
Azimuth Angle ◽  
Hydrocarbon Exploration ◽  
Three Dimensions ◽  
Pore Scale ◽  
Frequency Dependent ◽  
Dependent Behavior ◽  
The Impact

Abstract. Understanding the properties of cracked rocks is of great importance in scenarios involving CO2 geological sequestration, nuclear waste disposal, geothermal energy, and hydrocarbon exploration and production. Developing non-invasive detecting and monitoring methods for such geological formations is crucial. Many studies show that seismic waves exhibit strong dispersion and attenuation across a broad frequency range due to fluid flow at the pore scale known as squirt flow. Nevertheless, how and to what extent squirt flow affects seismic waves is still a matter of investigation. To fully understand its angle- and frequency-dependent behavior for specific geometries appropriate numerical simulations are needed. We perform a three-dimensional numerical study of the fluid-solid deformation at the pore scale based on coupled Lame-Navier and Navier-Stokes linear quasistatic equations. We show that seismic wave velocities exhibit strong azimuth-, angle- and frequency-dependent behavior due to squirt flow between interconnected cracks. We show that the overall anisotropy of a medium mainly increases due to squirt flow but in some specific planes the anisotropy can locally decrease. We analyze the Thomsen-type anisotropic parameters and adopt another scalar parameter which can be used to measure the anisotropy strength of a model with any elastic symmetry. This work significantly clarifies the impact of squirt flow on seismic wave anisotropy in three dimensions and can potentially be used to improve the geophysical monitoring and surveying of fluid-filled cracked porous zones in the subsurface.

scholarly journals Near-Field Measurement of Six Degrees of Freedom Mining-Induced Tremors in Lower Silesian Copper Basin

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6801
Author(s):  
Krzysztof Fuławka ◽  
Witold Pytel ◽  
Bogumiła Pałac-Walko
Keyword(s):  
Seismic Wave ◽  
Degrees Of Freedom ◽  
Seismic Waves ◽  
Near Field ◽  
High Energy ◽  
Rotational Component ◽  
Empirical Formulas ◽  
Six Degrees Of Freedom ◽  
The Impact

The impact of seismicity on structures is one of the key problems of civil engineering. According to recent knowledge, the reliable analysis should be based on both rotational and translational components of the seismic wave. To determine the six degrees of freedom (6-DoF) characteristic of mining-induced seismicity, two sets of seismic posts were installed in the Lower Silesian Copper Basin, Poland. Long-term continuous 6-DoF measurements were conducted with the use of the R-1 rotational seismometer and EP-300 translational seismometer. In result data collection, the waveforms generated by 39 high-energy seismic events were recorded. The characteristic of the rotational component of the seismic waves were described in terms of their amplitude and frequency characteristics and were compared with translational measurements. The analysis indicated that the characteristic of the rotational component of the seismic wave differs significantly in comparison to translational ones, both in terms of their amplitude and frequency distribution. Also, attenuation of rotational and translational components was qualitatively compared. Finally, the empirical formulas for seismic rotation prediction in the Lower Silesian Copper Basin were developed and validated.

scholarly journals Application of BRFP New-Type Anchor Cable Material in High Slopes against Earthquakes

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Honggang Wu ◽  
Zhixin Wu ◽  
Hao Lei ◽  
Tianwen Lai
Keyword(s):  
Dynamic Response ◽  
Seismic Wave ◽  
Seismic Waves ◽  
Response Spectrum ◽  
Basalt Fiber ◽  
Shaking Table ◽  
Measuring Point ◽  
Reinforced Plastics ◽  
Short Period ◽  
The Impact

To clarify the feasibility of BFRP (basalt fiber reinforced plastics) anchors instead of steel anchors in the seismic application of slopes under different vibration strengths, a series of shaking table tests were carried out to strengthen the slope using BFRP anchors and steel anchors, respectively. By studying the dynamic response recorded in the slope model and the observed experimental phenomena, the acceleration dynamic response and displacement spectrum dynamic response of the two slope models were analyzed. The test results show that the deformation stage of the slope reinforced by the two types of anchors is basically the same during the test, that is, elastic, plastic (potential sliding surface and plastic strengthening), and failure stages, respectively. The slope is in the elastic stage before the 0.2 g seismic wave, and it gradually enters the plastic stage after the 0.4 g seismic wave. However, the peak acceleration and displacement of the slope reinforced by steel anchors are greater than those of the slope reinforced by BFRP anchors under the same working conditions of seismic waves. In addition, we found that the acceleration response spectrum distribution curve of each measuring point in the short period has an obvious amplification effect along the elevation, and its predominant period has a forward migration phenomenon with the increase of the height of the measuring point, which also indicates that the higher frequency seismic wave has a greater impact on the top of the slope. The BFRP anchors, as a kind of flexible structure supporting slope, can effectively reduce the impact of seismic waves on the slope and attenuate seismic waves to a certain extent compared with steel anchors. Furthermore, the BFRP anchors can be deformed in coordination with the slope, which can improve the overall working performance of the slope, especially limit the dynamic response of the middle and lower slopes. These results can provide a theoretical guide for the seismic design of BFRP anchors for high slopes.

scholarly journals Seismic waves in the asteroid environment

2021 ◽  
Vol 249 ◽  
pp. 13001
Author(s):  
Paul Sánchez ◽  
Daniel J. Scheeres
Keyword(s):  
Numerical Simulations ◽  
Seismic Wave ◽  
Granular Media ◽  
Wave Speed ◽  
Seismic Waves ◽  
Wave Transmission ◽  
Overburden Pressure ◽  
Wave Speeds ◽  
The Impact ◽  
Random Packings

Through numerical simulations, we investigate impact generated seismic wave transmission in granular media under extremely low pressure. This mimics the conditions in the interior of asteroids and other small planetary bodies. We find a dependency not only on the overburden pressure on the medium, but also on the velocity of the impact that generates the wave. This is, at extremely low values of overburden pressure, the wave speed depends no only on the imposed pressure, but also on the increment in pressure created by the passing of the wave. We study crystalline and random packings and find very similar behaviour though with different wave speeds as expected. We then relate our results to different mission-related events on asteroids.

An empirical examination of firm financial performance along dimensions of supply chain resilience

2017 ◽  
Vol 40 (3) ◽  
pp. 254-269 ◽  
Author(s):  
Xun Li ◽  
Qun Wu ◽  
Clyde W. Holsapple ◽  
Thomas Goldsby
Keyword(s):  
Supply Chain ◽  
Financial Performance ◽  
Three Dimensions ◽  
Empirical Examination ◽  
Content Type ◽  
Supply Chain Resilience ◽  
Critical Dimensions ◽  
Firm Financial Performance ◽  
Supply Chain Agility ◽  
The Impact

Purpose This paper aims to investigate the impact of three critical dimensions of supply chain resilience, supply chain preparedness, supply chain alertness and supply chain agility, all aimed at increasing a firm’s financial outcomes. In a turbulent environment, firms require resilience in their supply chains to prepare for potential changes, detect changes and respond to actual changes, thus providing superior value. Design/methodology/approach Using survey data from 77 firms, this study develops scales for preparedness, alertness and agility. It then tests their hypothesized relationships with a firm’s financial performance. Findings The results reveal that the three dimensions of supply chain resilience (i.e. preparedness, alertness and agility) significantly impact a firm’s financial performance. It is also found that supply chain preparedness, as a proactive resilience capability, has a greater influence on a firm’s financial performance than the reactive capabilities including alertness and agility, suggesting that firms should pay more attention to proactive approaches for building supply chain resilience. Originality/value First, this study develops a comparatively comprehensive definition for supply chain resilience and explores its dimensionality. Second, this study provides empirically validated instruments for the dimensions of supply chain resilience. Third, this study is one of the first to provide empirical evidence for direct impact of supply chain resilience dimensions on a firm’s financial performance.

Back to the Westminster model? The Brexit process and the UK political system

2021 ◽  
pp. 019251212096737
Author(s):  
Gianfranco Baldini ◽  
Edoardo Bressanelli ◽  
Emanuele Massetti
Keyword(s):  
Political System ◽  
Party System ◽  
Political Process ◽  
Three Dimensions ◽  
Executive Power ◽  
The Political ◽  
Westminster Model ◽  
The Uk ◽  
Quantitative Indicators ◽  
The Impact

This article investigates the impact of Brexit on the British political system. By critically engaging with the conceptualisation of the Westminster model proposed by Arend Lijphart, it analyses the strains of Brexit on three dimensions developed from from Lijphart’s framework: elections and the party system, executive– legislative dynamics and the relationship between central and devolved administrations. Supplementing quantitative indicators with an in-depth qualitative analysis, the article shows that the process of Brexit has ultimately reaffirmed, with some important caveats, key features of the Westminster model: the resilience of the two-party system, executive dominance over Parliament and the unitary character of the political system. Inheriting a context marked by the progressive weakening of key majoritarian features of the political system, the Brexit process has brought back some of the traditional executive power-hoarding dynamics. Yet, this prevailing trend has created strains and resistances that keep the political process open to different developments.

scholarly journals Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

scholarly journals Exploring Residents’ Perceptions of the Socio-Cultural Benefits of Tourism Development in the Mountain Area

Societies ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 83
Author(s):  
Iulia C. Muresan ◽  
Rezhen Harun ◽  
Felix H. Arion ◽  
Ava Omar Fatah ◽  
Diana E. Dumitras
Keyword(s):  
Positive Attitude ◽  
Statistical Tests ◽  
Tourism Development ◽  
Principal Component ◽  
Local Communities ◽  
Three Dimensions ◽  
Development Economic ◽  
Mountain Area ◽  
Sustainable Tourism Development ◽  
The Impact

Development of tourism affected the socio-cultural environment of many destinations. Previous studies have focused more on analyzing the impact of tourism on all three dimensions of sustainable development (economic, environment and socio-cultural); therefore, the present paper examines tourism development’s impact with regard to the socio-cultural benefits that enhance sustainable tourism development. A survey based on a questionnaire was employed in June 2018 in a mountain village in Cluj County, Romania. The collected data were analyzed using principal component analysis, and several statistical tests were conducted. The results indicated that the respondents have a positive attitude towards tourism development and socio-cultural perceived benefits. Older people and those running a business tend to perceive more positively the benefits of tourism development. The findings of the research could contribute to future development strategies, as it is well known that supporting local communities influences the success of tourism destination.

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