SEISMIC WAVE PROPAGATION IN POROUS GRANULAR MEDIA

Geophysics ◽  
1956 ◽  
Vol 21 (3) ◽  
pp. 691-714 ◽  
Author(s):  
Norman R. Paterson
Keyword(s):  
Granular Media ◽  
Experimental Studies ◽  
Seismic Wave Propagation ◽  
Beach Sand ◽  
Sound Waves ◽  
Filling Materials ◽  
Porosity And Permeability ◽  
Size Sorting ◽  
The Media ◽  
A Charge

Theoretical and experimental studies have been made of the manner in which sound waves are propagated in porous granular aggregates. A cylindrical piezo‐electric source is used and this simulates the explosion of a charge in a seismic shot‐hole. It is found that in general two waves of volume expansion are propagated and that these involve coupled displacements of both constituents of the media. The waves are termed frame‐waves, air‐waves or liquid‐waves depending upon the nature of the pore‐filler and the relative displacements of the constituents. The frame‐wave velocity is dependent upon the strength of the frame, the densities of solid and pore‐filling materials and the texture of the medium. Air‐ and liquid‐wave velocities are related to the texture of the medium and to the density and viscosity of the pore‐filler. Frame‐strength is important to a lesser degree. Waves are dispersive only in the case of media of very low permeability. Attenuation is related to viscosity, texture and frequency. Scattering is probably important only at the highest frequencies and largest particle diameters used in the experiments. It is shown that porosity and permeability of a beach sand can be inferred from velocity measurements. These properties provide information regarding grain‐size, sorting and the nature of the pore‐filler.

scholarly journals Technological effect of processing with the organic granular media flows

2018 ◽  
Vol 226 ◽  
pp. 01026 ◽  
Author(s):  
Yevgeniy Y. Krupenya ◽  
Marina A. Boyko ◽  
Antonina P. Shishkina
Keyword(s):  
Granular Media ◽  
Experimental Studies ◽  
Organic Media ◽  
Metal Scrap ◽  
Energy Impact ◽  
Threshold Amplitude ◽  
The Media ◽  
Media Flows ◽  
Working Tank ◽  
Effect Of Surface

There has been carried out the analysis of approaches how to model vibrational processing by granulated media. The vibroprocessing model has been developed, that provides effective parts’ surfaces finishing work with granules of stone organic media initially based on the approach of energy impact of the granule flow on the processed surface. Specific volumetric metal scrap has been used as the main characteristic of processing with organic media its physical aim is increase rate of thickness of the material removed from the surface in the frames of definite velocity and pressure of the media. It is shown that metal scrap depends on media flow velocity, granular media height of the loading column, conditions that form stationary circulation motion of the media. Taking into account the analysis of experimental studies results of amplitude-frequency characteristics influence on the metal scrap during of abrasive granules vibroprocessing, there has been disclosed some certain dependence of the specific volume metal scrap while organic media processing, considering threshold amplitude and frequency of oscillations of the working tank that made it possible to observe the effect of surface treatment is. The established dependence describing the effective vibroprocessing conditions with stone organic media that was achieved due to experimental data which allows to assume validity of the obtained model.

scholarly journals IMPACT PRESSURES PRODUCED BY BREAKING WAVES

1974 ◽  
Vol 1 (14) ◽  
pp. 104 ◽  
Author(s):  
Norbert L. Ackerman ◽  
Ping-Ho Chen
Keyword(s):  
Water Surface ◽  
Ambient Pressure ◽  
Pressure Rise ◽  
Breaking Waves ◽  
Absolute Pressure ◽  
Maximum Pressure ◽  
Sound Waves ◽  
The Media ◽  
Entrapped Air ◽  
Entrained Air

Experiments were conducted in a vacuum tank in order to investigate the effect which entrained air has on impact loads which are produced when waves break upon a structure. In these experiments a flat plate was dropped onto a still water surface in an environment where the ambient pressure of the surrounding air could be controlled. Rings of varying height were fixed to the surface of the falling plate in order to trap different volumes of air between the falling plate and the water, Experimentally determined values were obtained of the maximum pressure pmax when the plate struck the water surface for various ring heights 6 and ambient pressures p0 in the vacuum tank. Experimental results indicate that the pressure rise or shock pressure Ps ~ (Pmax~Po) decreased with reductions in the ambient pressure and volume of entrapped air. Even when air was removed such that the absolute pressure in the tank was equal to the vapor pressure of the water, water hammer conditions, where the peak pressures depend upon the celerity of sound waves in the media, were never found to occur.

scholarly journals Specificity of the second sound standing waves behavior in a medium with nanoparticles

2021 ◽  
Vol 2056 (1) ◽  
pp. 012040
Author(s):  
A A Esina ◽  
V B Efimov
Keyword(s):  
Normal Component ◽  
Experimental Studies ◽  
Standing Waves ◽  
Second Sound ◽  
Sound Waves ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Significant Attenuation ◽  
Waves Propagation

Abstract The experimental studies of the second sound waves propagation in a resonator with a deuterium-helium gel were carried out. The latest experimental results, combined with those obtained in earlier experiments, have shown that the propagation of the second sound waves in gels leads to their significant attenuation and a decrease in the propagation velocity. This behavior differs from the case of the propagation of the sound waves of a two-component system with a strongly slow normal component and may indicate changes in the properties of superfluidity under confined geometry conditions.

scholarly journals Transport of engineered nanoparticles in soils and aquifers

2019 ◽  
Vol 27 (1) ◽  
pp. 43-70 ◽  
Author(s):  
Mahmood Fazeli Sangani ◽  
Gary Owens ◽  
Amir Fotovat
Keyword(s):  
Experimental Studies ◽  
Engineered Nanoparticles ◽  
Background Solution ◽  
Contributing Factors ◽  
Factors Affecting ◽  
Soil Systems ◽  
Aquifer Systems ◽  
Different Types ◽  
Transport Behaviour ◽  
The Media

Transport and deposition behaviour of engineered nanoparticles (ENPs) in natural aquifers and soil systems is a key determinant of the fate of these materials in environmental systems. A growing number of experimental studies are being conducted worldwide to address transport and deposition of ENPs in porous media (PM). Here we comprehensively review the main mechanisms and factors affecting the mobility of the environmentally important ENPs in natural PM. A variety of different processes including those that promote mobility and result in elution from the PM and those that hinder their mobility and promote ENP retention can influence ENP’s mobility through soil and aquifer media. The most important contributing factors regarding ENP transport in PM include: the physicochemical properties of the ENP, the media, the hydrodynamics of the system, and the background solution characteristics. Results from several studies conducted on the most common and environmentally important ENPs have shown that under natural environmental conditions, different types of ENPs show different transport behaviour in soil and aquifer systems. Additionally, the importance of media matrix and mobile solution factors in governing mobility of ENPs varies from one type of ENP to another.

Abstract 102: Granular Media Calcinosis in the Aortic Wall of Patients With Bicuspid and Tricuspid Aortic Valves

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Sandy von Salisch ◽  
Josephina Haunschild ◽  
Martin Misfeld ◽  
Michael A Borger ◽  
Stefan Dhein ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Bicuspid Aortic Valve ◽  
Granular Media ◽  
Aortic Wall ◽  
Aortic Disease ◽  
Dissecting Aneurysm ◽  
Media Thickness ◽  
Significant Difference ◽  
The Media ◽  
Aneurysm Dissection

Background: Bicuspid aortic valve is the most frequent congenital cardiac abnormality and associated with proximal aortic disease (i.e. aneurysm, dissection or rupture). Granular media calcinosis(GMC)--suggested to increase stiffness and play a pathogenetic role in dissecting aneurysm--has not yet been quantified in BAV. Methods: Specimen of the proximal aortic wall from 76 patients--32 with tricuspid (TAV) and 44 with bicuspid aortic valve (BAV)--were obtained during surgery to quantify media thickness and GMC by von Kossa staining (panel C), comparing the convexity (Cvx) and concavity (Ccv) in BAV vs. TAV. Results: Interlamellar GMC affected the most central layers of the media and those adjacent to the outer adventitia with a doubling within both--the Cvx and Ccv--of pts with BAV compared to patients with TAV (13.3±9.6 vs. 6.6±7.4 and 12.8±10.8 vs. 6.4±7.1; p<0.05, panel A) was seen, but neither a difference in calcification between the Ccx and the Ccv side within the BAV nor the TAV group. No association between age and calcification grade , neither in the Cvx nor the Ccv (r=0.132, p=0.218 and 0.103, p=0.341) was seen. There was a significant difference in the total media thickness between BAV and TAV at the Cvx (867±162μm vs . 993±158μm; p<0.05) and the Ccv (1005 ± 236 vs 1223 ± 217μm; p<0.05, panel B). Independent of aortic valve morphology, the Cvx was thinner than the Ccv side (TAV: 993 ± 158 vs.1223 ± 217μm; p<0.001; BAV: 869 ± 162 vs.1005 ± 236μm; p<0.05, panel B). Conclusion: BAVs had significantly thinner media and twice as much GMC than their tricuspid peers possibly associated with the loosening of the bond between the elastic lamellae causing a decrease in elasticity possibly explaining a higher risk for dissection and rupture.

scholarly journals Citizens as Complicits: Distrust in Politicians and Biased Social Dissemination of Political Information

2020 ◽  
pp. 1-17 ◽  
Author(s):  
TROELS BØGGILD ◽  
LENE AARØE ◽  
MICHAEL BANG PETERSEN
Keyword(s):  
Interpersonal Communication ◽  
Experimental Studies ◽  
Active Role ◽  
Psychological Research ◽  
Economic Interests ◽  
Group Cooperation ◽  
The Media ◽  
Foreign Governments ◽  
Mass Level

Widespread distrust in politicians is often attributed to the way elites portray politics to citizens: the media, competing candidates, and foreign governments are largely considered responsible for portraying politicians as self-interested actors pursuing personal electoral and economic interests. This article turns to the mass level and considers the active role of citizens in disseminating such information. We build on psychological research on human cooperation, holding that people exhibit an interpersonal transmission bias in favor of information on the self-interested, antisocial behavior of others to maintain group cooperation. We posit that this transmission bias extends to politics, causing citizens to disproportionally disseminate information on self-interested politicians through interpersonal communication and, in turn, contributes to distrust in politicians and policy disapproval. We support these predictions using novel experimental studies, allowing us to observe transmission rates and opinion effects in actual communication chains. The findings have implications for understanding and accommodating political distrust.

Mixed nonlinearity and double shocks in superfluid helium

1990 ◽  
Vol 221 ◽  
pp. 233-261 ◽  
Author(s):  
M. S. Cramer ◽  
R. Sen
Keyword(s):  
Superfluid Helium ◽  
Burgers Equation ◽  
Experimental Studies ◽  
Perturbation Scheme ◽  
Sound Waves ◽  
Shock Speed ◽  
Mixed Nonlinearity ◽  
Existence Conditions ◽  
Shock Thickness ◽  
Local Value

We examine weak second-sound waves in He II at temperatures and pressures near one of the zeros of the Khalatnikov steepening parameter Γ. An extension of the reductive perturbation scheme of Taniuti & Wei is employed to derive the cubic Burgers’ equation governing these waves. It is shown that mixed nonlinearity may occur in disturbances in which the local value of Γ remains strictly positive or strictly negative. Further new results include expressions for the shock speed, shock structure and the conditions under which the shock thickness increases, rather than decreases, with strength. The fundamental existence conditions for temperature shocks are also delineated and related to the shock disintegration process observed in experimental studies.

Experimental Studies on the Gas-Stack Heat Transfer in a Thermoacoustic Refrigeration System

2003 ◽  
Author(s):  
Phani R. Gurijala ◽  
Emmanuel C. Nsofor
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Experimental Studies ◽  
Heat Losses ◽  
Inert Gases ◽  
Working Fluid ◽  
Sound Waves ◽  
Thermoplastic Material ◽  
Pressure Transducers ◽  
Thermoacoustic Refrigeration

Thermoacoustic refrigeration employs inert gases as the working fluid and uses high intensity sound waves to pump heat energy. The major components of the system are the resonator, the acoustic driver, the heat exchangers and the stack. The useful thermoacoustic process for cooling in the system takes place between the gas particles and the stack. The system was designed and constructed. Experimental studies on the gas-stack heat transport and the Streaming Reynolds Number, which play crucial roles in the heat transport behavior, were studied. Input signals for the experiments, for the data acquisition system was from thermocouples and pressure transducers. Results from the study were used to make recommendations for the system. It was observed that for a given frequency, the heat transfer increases with drive ratio. Results from the comparison of the heat losses for a stainless steel stack and a stack built of thermoplastic material show that the plate heat losses can be significantly reduced if the stack with thermoplastic material is used for the system.

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