scholarly journals Experimental determination of elastic anisotropy of Berea sandstone, Chicopee shale, and Chelmsford granite

Geophysics ◽  
1986 ◽  
Vol 51 (1) ◽  
pp. 164-171 ◽  
Author(s):  
Tien‐when Lo ◽  
Karl B. Coyner ◽  
M. Nafi Toksöz
Keyword(s):  
Grain Orientation ◽  
Elastic Anisotropy ◽  
Confining Pressure ◽  
Combined Effects ◽  
Berea Sandstone ◽  
Velocity Measurements ◽  
Transmission Method ◽  
Wave Velocities ◽  
Young’S Moduli

We used the ultrasonic transmission method to measure P-, SH-, and SV-wave velocities for Chelmsford granite, Chicopee shale, and Berea sandstone in different directions up to 1 000 bars confining pressure. The velocity measurements indicate these three rocks are elastically anisotropic. The stiffness constants, dynamic Young’s moduli, dynamic Poisson’s ratios, and dynamic bulk moduli of the three rocks were also calculated. The elastic constants, together with velocity measurements, suggest that: (1) elastic anisotropy is due to the combined effects of pores or cracks and mineral grain orientation, and (2) elastic anisotropy decreases with increasing confining pressure. The residual anisotropy at higher confining pressure is due to mineral grain orientation.

Anisotropy of elastic wave velocities in deformed shales: Part 1 — Experimental results

Geophysics ◽  
2008 ◽  
Vol 73 (5) ◽  
pp. D75-D89 ◽  
Author(s):  
Joël Sarout ◽  
Yves Guéguen
Keyword(s):  
Elastic Wave ◽  
Wave Velocity ◽  
Elastic Anisotropy ◽  
Ambient Pressure ◽  
Transversely Isotropic ◽  
Elastic Wave Velocity ◽  
Velocity Measurements ◽  
Wave Velocities ◽  
In Situ Conditions ◽  
Triaxial Cell

Elastic wave velocity measurements in the laboratory are used to assess the evolution of the microstructure of shales under triaxial stresses, which are representative of in situ conditions. Microstructural parameters such as crack aperture are of primary importance when permeability is a concern. The purpose of these experiments is to understand the micromechanical behavior of the Callovo-Oxfordian shale in response to external perturbations. The available experimental setup allows for the continuous, simultaneous measurement of five independent elastic wave velocities and two directions of strain (axial and circumferential), performed on the same cylindrical rock sample during deformation in an axisymmetric triaxial cell. The main results are (1) identification of the complete tensor of elastic moduli of the transversely isotropic shales using elastic wave velocity measurements, (2) assessment of the evolution of these moduli under triaxial loading, and (3) assessment of the evolution of the elastic anisotropy under loading in terms of Thomsen’s parameters. This last outcome allows us to use the anisotropy of the elastic properties of this rock as an indicator of the evolution of its microstructure. In particular, [Formula: see text] in the dry case decreases from 0.5 (ambient pressure) toward 0.37 [Formula: see text], while [Formula: see text] and [Formula: see text] are almost insensitive to pressure. In the wet case, [Formula: see text] decreases from 0.3 (ambient pressure) toward 0.2 [Formula: see text]. Deviatoric stresses have a strong effect on [Formula: see text], [Formula: see text], and [Formula: see text] variations. In this case, [Formula: see text] drops (both for the dry and wet conditions) when failure is approached.

scholarly journals Determination of elastic anisotropy of rocks from P- and S-wave velocities: numerical modelling and lab measurements

2014 ◽  
Vol 199 (3) ◽  
pp. 1682-1697 ◽  
Author(s):  
Tomáš Svitek ◽  
Václav Vavryčuk ◽  
Tomáš Lokajíček ◽  
Matěj Petružálek
Keyword(s):  
Numerical Modelling ◽  
Elastic Anisotropy ◽  
S Wave ◽  
Wave Velocities

The Influence of pore pressure and confining pressure on dynamic elastic properties of Berea sandstone

Geophysics ◽  
1985 ◽  
Vol 50 (2) ◽  
pp. 207-213 ◽  
Author(s):  
N. I. Christensen ◽  
H. F. Wang
Keyword(s):  
Pore Pressure ◽  
Shear Wave ◽  
Confining Pressure ◽  
Compressional Wave ◽  
Berea Sandstone ◽  
Incremental Change ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Pulse Transmission ◽  
Pressure Increment

Compressional‐ and shear‐wave velocities of watersaturated Berea sandstone have been measured as functions of confining and pore pressures to 2 kbar. The velocities, measured by the pulse transmission technique, were obtained at selected pressures for the purpose of evaluating the relative importance of confining pressure and pore pressure on elastic wave velocities and derived dynamic elastic constants. Changes in Berea sandstone velocities resulting from changes in confining pressure are not exactly canceled by equivalent changes in pore pressure. For properties that involve significant bulk compression (compressional‐wave velocities and bulk modulus) an incremental change in pore pressure does not entirely cancel a similar change in confining pressure. On the other hand, it is shown that a pore pressure increment more than cancels an equivalent change in confining pressure for properties that depend significantly on rigidity (shear‐wave velocity and Poisson’s ratio). This behavior (as well as observed wave amplitudes) is related to the presence of high‐compressibility clay that lines grains and pores within the quartz framework of the Berea sandstone.

scholarly journals Elastic constants of fibre-textured thin films determined by X-ray diffraction

2009 ◽  
Vol 42 (3) ◽  
pp. 416-428 ◽  
Author(s):  
K. J. Martinschitz ◽  
R. Daniel ◽  
C. Mitterer ◽  
J. Keckes
Keyword(s):  
Thin Films ◽  
Elastic Constants ◽  
Elastic Anisotropy ◽  
Rapid Determination ◽  
Interaction Model ◽  
Theoretical Concept ◽  
X Ray Diffraction ◽  
X Ray ◽  
Young’S Moduli

A new methodology is presented that allows the rapid determination of elastic constants of cubic fibre-textured thin films by X-ray diffraction. The theoretical concept is developed and tested on calculated examples of Cu and CrN films. The mechanical elastic constants are extrapolated from X-ray elastic constants by taking into consideration crystal and macroscopic elastic anisotropy. The derived algorithm enables the determination of a reflection and the corresponding value of the X-ray anisotropic factor Γ for which the X-ray elastic constants are equal to their mechanical counterparts in the case of fibre-textured cubic polycrystalline aggregates. The approach is independent of the crystal elastic anisotropy and depends on the fibre-texture type, the texture sharpness, the number of randomly oriented crystallites and the supposed grain-interaction model. In the experimental part, out-of-plane Young's moduli of 111 and 311 fibre-textured Cu and CrN thin films deposited on monocrystalline Si(100) substrates are determined. The moduli are extrapolated from thin-film experimental X-ray elastic constants that are determined by a combination of X-ray diffraction substrate curvature and sin2ψ methods. For the calculation, the film macroscopic elastic anisotropy (texture) is considered. The advantage of the new technique lies in the fact that experimental moduli are determined nondestructively, using a static diffraction experiment, and represent volume-averaged quantities.

Electron backscatter diffraction determination of grain orientation and constituent phases

1999 ◽  
Vol 4 (2) ◽  
pp. 174-174
Author(s):  
Chen Xiaomei ◽  
Liu Jing ◽  
Wang Jianbo ◽  
Zhang Ruikang ◽  
Wang Dahai ◽  
...  
Keyword(s):  
Grain Orientation ◽  
Electron Backscatter Diffraction ◽  
Diffraction Determination ◽  
Electron Backscatter ◽  
Backscatter Diffraction

scholarly journals Dual 2-Hydroxypropyl-β-Cyclodextrin and 5,10,15,20-Tetrakis (4-Hydroxyphenyl) Porphyrin System as a Novel Chiral-Achiral Selector Complex for Enantioseparation of Aminoalkanol Derivatives with Anticancer Activity in Capillary Electrophoresis

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 993
Author(s):  
Błażej Grodner ◽  
Mariola Napiórkowska
Keyword(s):  
Capillary Electrophoresis ◽  
Anticancer Agents ◽  
Chiral Discrimination ◽  
Combined Effects ◽  
Pilot Studies ◽  
Repeatability And Reproducibility ◽  
The Stability ◽  
Short Time ◽  
High Separation

In this study, a complex consisting of 2-hydroxypropyl-β-cyclodextrin and 5,10,15,20-tetrakis (4-hydroxyphenyl) porphyrin, (named dual chiral-achiral selector complex) was used for the determination of two novel potential anticancer agents of (I) and (II) aminoalkanol derivatives. This work aimed at developing an effective method that can be utilized for the determination of I (S), I (R), and II (S) and II (R) enantiomers of (I) and (II) compounds through the use of a dual chiral-achiral selector complex consisting of hydroxypropyl-β-cyclodextrin and 5,10,15,20-tetrakis (4-hydroxyphenyl) porphyrin system by applying capillary electrophoresis. This combination proved to be beneficial in achieving high separation selectivity due to the combined effects of different modes of chiral discrimination. The enantiomers of (I) and (II) compounds were separated within a very short time of 3.6–7.2 min, in pH 2.5 phosphate buffer containing 2-hydroxypropyl-β-cyclodextrin and 5,10,15,20-tetrakis (4-hydroxyphenyl) porphyrin system at a concentration of 5 and 10 mM, respectively, at 25 °C and +10 kV. The detection wavelength of the detector was set at 200 nm. The LOD for I (S), I (R), II (S), and II (R) was 65.2, 65.6, 65.1, and 65.7 ng/mL, respectively. LOQ for I (S), I (R), II (S), and II (R) was 216.5, 217.8, 217.1, and 218.1 ng/mL, respectively. Recovery was 94.9–99.9%. The repeatability and reproducibility of the method based on the values of the migration time, and the area under the peak was 0.3–2.9% RSD. The stability of the method was determined at 0.1–4.9% RSD. The developed method was used in the pilot studies for determining the enantiomers I (S), I (R), II (S), and II (R) in the blood serum.

scholarly journals Mass determination of the 1:3:5 near-resonant planets transiting GJ 9827 (K2-135)

2018 ◽  
Vol 618 ◽  
pp. A116 ◽  
Author(s):  
J. Prieto-Arranz ◽  
E. Palle ◽  
D. Gandolfi ◽  
O. Barragán ◽  
E. W. Guenther ◽  
...  
Keyword(s):  
Planetary System ◽  
Initial Conditions ◽  
Dynamical Evolution ◽  
Space Mission ◽  
Mass Determination ◽  
Velocity Measurements ◽  
Orbital Periods ◽  
The Masses ◽  
Better Than

Context. Multiplanet systems are excellent laboratories to test planet formation models as all planets are formed under the same initial conditions. In this context, systems transiting bright stars can play a key role, since planetary masses, radii, and bulk densities can be measured. Aims. GJ 9827 (K2-135) has recently been found to host a tightly packed system consisting of three transiting small planets whose orbital periods of 1.2, 3.6, and 6.2 days are near the 1:3:5 ratio. GJ 9827 hosts the nearest planetary system (~30 pc) detected by NASA’s Kepler or K2 space mission. Its brightness (V = 10.35 mag) makes the star an ideal target for detailed studies of the properties of its planets. Methods. Combining the K2 photometry with high-precision radial-velocity measurements gathered with the FIES, HARPS, and HARPS-N spectrographs we revised the system parameters and derive the masses of the three planets. Results. We find that GJ 9827 b has a mass of Mb = 3.69−0.46+0.48 M⊕ and a radius of Rb = 1.58−0.13+0.14 R⊕, yielding a mean density of ρb = 5.11−1.27+1.74 g cm−3. GJ 9827 c has a mass of Mc = 1.45−0.57+0.58 M⊕, radius of Rc = 1.24−0.11+0.11 R⊕, and a mean density of ρc = 4.13−1.77+2.31 g cm−3. For GJ 9827 d, we derive Md = 1.45−0.57+0.58 M⊕, Rd = 1.24−0.11+0.11 R⊕, and ρd = 1.51−0.53+0.71 g cm−3. Conclusions. GJ 9827 is one of the few known transiting planetary systems for which the masses of all planets have been determined with a precision better than 30%. This system is particularly interesting because all three planets are close to the limit between super-Earths and sub-Neptunes. The planetary bulk compositions are compatible with a scenario where all three planets formed with similar core and atmosphere compositions, and we speculate that while GJ 9827 b and GJ 9827 c lost their atmospheric envelopes, GJ 9827 d maintained its primordial atmosphere, owing to the much lower stellarirradiation. This makes GJ 9827 one of the very few systems where the dynamical evolution and the atmosphericescape can be studied in detail for all planets, helping us to understand how compact systems form and evolve.

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