Transient Resistivity Variation due to Air Entrapment under Ponding Condition

2013 ◽  
Vol 1 (3) ◽  
pp. 103 ◽  
Author(s):  
R. Andrade ◽  
D. Muralidharan ◽  
R. Rangarajan
Keyword(s):  
Air Entrapment ◽  
Resistivity Variation

scholarly journals Effect of nano and micro conductive materials on conductive properties of carbon fiber reinforced concrete

2020 ◽  
Vol 9 (1) ◽  
pp. 445-454 ◽  
Author(s):  
Juhong Han ◽  
Dunbin Wang ◽  
Peng Zhang
Keyword(s):  
Carbon Fiber ◽  
Carbon Black ◽  
Steel Slag ◽  
Pressure Sensitivity ◽  
Electric Conduction ◽  
Conductive Materials ◽  
Slag Powder ◽  
Steel Slag Powder ◽  
Resistivity Variation ◽  
Nano Carbon

AbstractIn this study, the pressure sensitivity and temperature sensitivity of the diphasic electric conduction concrete were investigated by measuring the resistivity using the four-electrode method. The diphasic electric conduction concrete was obtained by mixing nano and micro conductive materials (carbon nanofibers, nano carbon black and steel slag powder) into the carbon fiber reinforced concrete (CFRC). The results indicated that, with the increase of conduction time, the resistivity of CFRC decreased slightly at the initial stage and then became steady, while the resistivity of CFRC containing nano carbon black had a sharp decrease at the dosage of 0.6%. With the increase of compression load, the coefficient of resistivity variation of CFRC containing nano carbon black and steel slag powder changed little. The coefficient of resistivity variation increased with the increase of steel slag powder in the dry environment, and CFRC had preferable pressure sensitivity when the mass fractions of carbon fiber and carbon nanofiber were 0.4% and 0.6%, respectively. Besides, in the humid environment, the coefficient of resistivity variation decreased with the increase of steel slag powder, and the diphasic electric conduction concrete containing 0.4% carbon fibers and 20% steel slag powder had the best pressure sensitivity under the damp environment. Moreover, in the dry environment, CFRC containing nano and micro conductive materials presented better temperature sensitivity in the heating stage than in the cooling stage no matter carbon nanofiber, nano carbon black or steel slag powder was used, especially for the CFRC containing steel slag powder.

scholarly journals Correcting for Static Shift of Magnetotelluric Data with Airborne Electromagnetic Measurements: A Case Study from Rathlin Basin, Northern Ireland

2016 ◽  
Author(s):  
Robert Delhaye ◽  
Volker Rath ◽  
Alan G. Jones ◽  
Mark R. Muller ◽  
Derek Reay
Keyword(s):  
Distortion Correction ◽  
Vertical Scaling ◽  
Spatial Density ◽  
Target Area ◽  
Resistivity Structure ◽  
Static Shift ◽  
Magnetotelluric Data ◽  
Archie’S Law ◽  
Order Of Magnitude ◽  
Resistivity Variation

Abstract. Galvanic distortions of magnetotelluric (MT) data, such as the static shift effect, are a known problem that can lead to incorrect estimation of resistivities and erroneous modelling of geometries with resulting misinterpretation of subsurface electrical resistivity structure. A wide variety of approaches have been proposed to account for these galvanic distortions, some depending on the target area, with varying degrees of success. The natural laboratory for our study is a hydraulically permeable volume of conductive sediment at depth, the internal resistivity structure of which can be used to estimate reservoir viability for geothermal purposes, however static shift correction is required in order to ensure robust and precise modelling accuracy. We propose a method employing frequency–domain electromagnetic data for static shift correction, which in our case are regionally available with high spatial density. The spatial distributions of the derived static shift corrections are analysed and applied to the uncorrected MT data prior to inversion. Two comparative inversion models are derived, one with and one without static shift corrections, with instructive results. As expected from the one–dimensional analogy of static shift correction, at shallow model depths, where the structure is controlled by a single local MT site, the correction of static shift effects leads to vertical scaling of resistivity-thickness products in the model, with the corrected model showing improved correlation to existing borehole wireline resistivity data. In turn, as these vertical scalings are effectively independent of adjacent sites, lateral resistivity distributions are also affected, with up to half a decade of resistivity variation between the models estimated at depths down to 2000 m. Simple estimation of differences in bulk porosity, derived using Archie’s Law, between the two models reinforces our conclusion that the sub–order of magnitude resistivity contrasts induced by correction of static shifts correspond to similar contrasts in estimated porosities, and hence, for purposes of reservoir investigation or similar cases requiring accurate absolute resistivity estimates, galvanic distortion correction, especially static shift correction, is essential.

SSM Provides Important Advantages; So, why has SSM Failed to Achieve Greater Market Share?

2014 ◽  
Vol 217-218 ◽  
pp. 481-486 ◽  
Author(s):  
John L. Jorstad
Keyword(s):  
Turbulent Flow ◽  
Heat Treating ◽  
Solid Metal ◽  
Light Metals ◽  
Solidification Shrinkage ◽  
Air Entrapment ◽  
Thin Sections ◽  
Metal Processing ◽  
Semi Solid ◽  
Minimum Heat

Semi solid metal processing has numerous technical and economic advantages, such as viscous, non-turbulent flow (thus no air entrapment during casting), ability to fill ultra-thin sections (thus reduced part weight), little solidification shrinkage in the die (thus little or no porosity), minimum heat imparted to tooling (thus long tool life) and good response to T-5 aging (thus reduced heat treating costs). Still, SSM has never achieved a prominent position in the field of light metals casting Why? Perhaps the reason was largely the down economy of recent years and SSM will yet emerge with the prominence once expected of it.

Air entrapment in sheet molding compounds (SMC)

1986 ◽  
Vol 7 (6) ◽  
pp. 431-434 ◽  
Author(s):  
Dag Slotfeldt-Ellingsen ◽  
Elisabeth Magnus ◽  
Eric Ekern ◽  
Egil Holtmon ◽  
Lars Corneliussen
Keyword(s):  
Air Entrapment ◽  
Molding Compounds

Correlation between Room Temperature Photoluminescence and Resistivity in Semiinsulating Silicon Carbide

2006 ◽  
Vol 527-529 ◽  
pp. 717-720 ◽  
Author(s):  
Sashi Kumar Chanda ◽  
Yaroslav Koshka ◽  
Murugesu Yoganathan
Keyword(s):  
Low Temperature ◽  
Point Defects ◽  
Room Temperature ◽  
Vanadium Content ◽  
Mapping Technique ◽  
Native Defect ◽  
Room Temperature Photoluminescence ◽  
Native Point Defects ◽  
Pl Mapping ◽  
Resistivity Variation

A room temperature PL mapping technique was applied to establish the origin of resistivity variation in PVT-grown 6H SiC substrates. A direct correlation between the native defect-related PL and resistivity was found in undoped (V-free) samples. In vanadium-doped samples with low vanadium content, the resistivity showed a good correlation with the total PL signal consisting of contributions from both vanadium and native point defects. Well-known UD1 and UD3 levels were revealed by low-temperature PL spectroscopy. Some correlation was observed between these low-temperature PL signatures and the resistivity distribution.

Study of flood embankment behaviour induced by air entrapment

2008 ◽  
pp. 655-665 ◽  
Author(s):  
D Lesniewska ◽  
H Zaradny ◽  
P Bogacz ◽  
J Kaczmarek
Keyword(s):  
Air Entrapment

scholarly journals Stability and Time-Delay Effect of Rainfall-induced Landslide Considering Air Entrapment

2021 ◽  
Author(s):  
Shixin Zhang ◽  
Li Li ◽  
Dongsheng Zhao ◽  
Bo Ni ◽  
Yue Qiang ◽  
...  
Keyword(s):  
Time Delay ◽  
Slope Stability ◽  
Heavy Rainfall ◽  
Parameter Analysis ◽  
Three Gorges Reservoir Area ◽  
Actual State ◽  
Air Entrapment ◽  
Delay Effect ◽  
Hydraulic Hysteresis ◽  
Time Delay Effect

Abstract Rainfall-induced landslide is a typical geological disaster in the Three Gorges reservoir area. The air entrapment in the pores of soils has a hindrance to the infiltration of the slope. It is mainly reflected in the hydraulic hysteresis after rainfall and the decrease of the slope anti-sliding force. A method considered the air entrapment of the closed gas in soil particles’ pores is developed to study the time-delay effect and slope stability under the rainfall process. The Green-Ampt infiltration model is used to obtain the explicit analytical solution of the slope infiltration considering air entrapment. Moreover, the relationship between the safety factor, the rainfall duration, and the depth of the wetting front under the three rainfall conditions (qrain=12, 26, 51 mm/h) is discussed. The results show that the air entrapment causes a significant time-delay effect of the landslide, and the hydraulic hysteresis is the strongest under the condition of heavy rainfall (qrain= 51mm/h). The time-delay effect lasts longer than low rainfall and heavy rainfall when the rainfall intensity (qrain= 26 mm/h) is slightly greater than saturated hydraulic conductivity Ks. Parameter analysis shows that when air entrapment is considered, the smaller the slope angle and the effective internal friction angle, the more significant the air entrapment has on the slope stability; the smaller the effective cohesion, the longer the air resistance lasts. Finally, the application of the Bay Area landslide is consistent with the actual state of the landslide.

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