scholarly journals S-wave propagating in an anisotropic inhomogeneous elastic medium under the influence of gravity, initial stress, electric and magnetic field

2014 ◽  
Vol 41 (2) ◽  
pp. 141-157 ◽  
Author(s):  
Rajneesh Kakar ◽  
Shikha Kakar
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Initial Stress ◽  
Isotropic Medium ◽  
Shear Waves ◽  
S Wave ◽  
Incompressible Medium ◽  
Material Parameters ◽  
Electric And Magnetic Field ◽  
Inhomogeneous Elastic Medium

The purpose of this paper is to study the effect of gravity, initial stress, non-homogeneity, electric and magnetic field on the propagation of shear waves in an anisotropic incompressible medium. Various graphs are plotted to show the effect of direction of propagation, the anisotropy, magnetic field, electric field, non-homogeneity of the medium and the initial stress on shear waves. The dispersion equations for shear waves are obtained and discussed for different cases. In fact, in the absence of various material parameters, these equations are in agreement with the classical results for isotropic medium.

scholarly journals Health Hazards Associated with Electric and Magnetic Field Intensities around Mobile Base Stations in Katsina State, Nigeria

2020 ◽  
Vol 24 (2) ◽  
pp. 253-256
Author(s):  
M. Abdulsalam ◽  
S. Bello ◽  
Y.A. Sumaila ◽  
H. Abubakar ◽  
I.B. Muhammad ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Field Intensity ◽  
Health Hazard ◽  
Health Hazards ◽  
Base Stations ◽  
Reconnaissance Survey ◽  
Radiated Power ◽  
Electric And Magnetic Field ◽  
Mobile Base

This work was carried out to assess the health hazards associated with exposure to radiofrequency electromagnetic fields from mobile base stations (MBS) within Katsina, Nigeria. Seventy seven MBS were identified through reconnaissance survey. Received radiated power was measured at a distance of 0, 20, 40, 60 and 80m from the MBS using a handheld B and K precision spectrum analyser. Electric and magnetic field intensities (E and H) were calculated. E (mV/m) and H (μA/m) had average values of; 21.03 and 55.78 for MTN; 9.41 and 24.96 for GLO; 2.33 and 6.18, for Etisalat; 18.32 and 48.62 for Airtel. Our results indicated that the general public exposure from radiofrequency electromagnetic radiation from all the considered mobile base stations is within the acceptable threshold of 61 V/m for Electric field intensity and 0.16A/m for Magnetic field intensity. Keywords: Mobile base stations, Radiation, Katsina, Health hazard, Electric field, Magnetic field

scholarly journals Hybridization and Field Driven Phase Transitions in Hexagonally Warped Topological Insulators

SPIN ◽  
2016 ◽  
Vol 06 (02) ◽  
pp. 1640005 ◽  
Author(s):  
Anirudha Menon ◽  
Debashree Chowdhury ◽  
Banasri Basu
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Phase Transition ◽  
Phase Transitions ◽  
Electric Field ◽  
Surface States ◽  
Material Parameters ◽  
Insulator Phase Transition ◽  
Tilted Magnetic Field

In this paper, we discuss the role of material parameters and external field effects on a thin film topological insulator(TI) in the context of quantum phase transition (QPT). First, we consider an in-plane tilted magnetic field and determine the band structure of the surface states as a function of the tilt angle. We show that the presence of either a hybridization term or hexagonal warping or a combination of both leads to a semi-metal to insulator phase transition which is facilitated by their [Formula: see text] symmetry breaking character. We then note that while the introduction of an electric field does not allow for this QPT since it does not break [Formula: see text] symmetry, it can be used in conjunction with a tunneling element to reach a phase transition efficiently. The corresponding critical point is then nontrivially dependent on the electric field, which is pointed out here. Then, we demonstrate that including a hexagonal warping term leads to an immediate [Formula: see text] symmetry violating QPT.

scholarly journals Useful characteristics of shallow and deep marine CSEM responses inferred from 3D finite-difference modeling

Geophysics ◽  
2009 ◽  
Vol 74 (5) ◽  
pp. F67-F76 ◽  
Author(s):  
Yutaka Sasaki ◽  
Max A. Meju
Keyword(s):  
Magnetic Field ◽  
Finite Difference ◽  
Electric Field ◽  
Shallow Water ◽  
Phase Response ◽  
Staggered Grid ◽  
Small Scale ◽  
Shallow Waters ◽  
Near Surface ◽  
Electric And Magnetic Field

Hydrocarbon reservoirs can be mapped if sufficient resistivity contrasts exist between them and their confining layers, but practical problems remain in target discrimination in deep and shallow waters, especially in the presence of heterogeneous overburden. We have developed an efficient 3D staggered-grid finite-difference controlled-source electromagnetic (CSEM) modeling code that enables study of the physics underlying some practical problems. We undertook a comparative analysis of reservoir detection in [Formula: see text]- and [Formula: see text]-deep waters using the simulated electric and magnetic field responses of a simple 3D reservoir. We examined the effect of two types of near-surface heterogeneity (mimicking disconnected gas clouds and/or patchy geochemical alteration halos) on the 3D reservoir response. We found that small-scale, shallow heterogeneities cause distortions that are almost independent of the source frequency. These persist at all source-receiver offsets in the electric amplitude response in deep and shallow waters and phase response in shallow water. They decrease in magnitude with increasing offset in deepwater phase response. Large-scale near-surface heterogeneities distort the horizontal electric field response more significantly than the small-scale ones, but the near-surface response gets smaller in amplitude as the offset increases. The distortions in shallow water are much smaller in magnitude than those for the deepwater case, so that the reservoir signatures still are visible on the response profiles. This might be considered as a positive feature for shallow-water inline electric field exploration. The magnetic field responses for the orthogonal direction provide diagnostic target signatures that are similar to the inline electric field responses in deep water but that are different in shallow water. The magnetic responses are affected by the airwave in a different manner from the electric field, suggesting that combined 3D electric and magnetic field analysis might be vital for handling the airwave problem.

Effect of Rotation, Gravity, Primary Stress and Magnetic Field on Shear Waves Spreading in an Anisotropic Incompressible Sandy Elastic Medium

2019 ◽  
Vol 16 (11) ◽  
pp. 4443-4454
Author(s):  
S. H. Elhag ◽  
F. S. Bayones
Keyword(s):  
Magnetic Field ◽  
Elastic Medium ◽  
Gravity Field ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Incompressible Medium ◽  
Primary Stress ◽  
Dry Sand ◽  
Inhomogeneous Elastic Medium

In this paper, we investigated the spreading of shear wave in an anisotropic non-homogeneous elastic medium under effect of dry sand, rotation, gravity, primary stress, and magnetic field. We have reached equation of variation of shear wave velocity c1 in an anisotropic incompressible medium according to sand, rotation, gravity, primary stress, and magnetic field, then we used graphs to illustrate to show the effect of direction of spreading of shear wave. The results indicate that the effect of dry sand, rotation, gravity, primary stress, and magnetic field on the spreading of shear wave in an anisotropic inhomogeneous elastic medium are very pronounced. The results have been obtained are discussed and presented visually, the results demonstrate that the effect of sand, gravity field, primary stress, magnetic field, anisotropy and rotation are noticeable.

scholarly journals The numerical simulation on ionospheric perturbations in electric field before large earthquakes

2014 ◽  
Vol 32 (12) ◽  
pp. 1487-1493 ◽  
Author(s):  
S. F. Zhao ◽  
X. M. Zhang ◽  
Z. Y. Zhao ◽  
X. H. Shen
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Topside Ionosphere ◽  
Ion Density ◽  
Frequency Wave ◽  
Theoretical Simulation ◽  
Electric And Magnetic Field ◽  
Large Earthquakes

Abstract. Many observational results have shown electromagnetic abnormality in the ionosphere before large earthquakes. The theoretical simulation can help us to understand the internal mechanism of these anomalous electromagnetic signals resulted from seismic regions. In this paper, the horizontal and vertical components of electric and magnetic field at the topside ionosphere are simulated by using the full wave method that is based on an improved transfer matrix method in the lossy anisotropic horizontally stratified ionosphere. Taken account into two earthquakes with electric field perturbations recorded by the DEMETER satellite, the numerical results reveal that the propagation and penetration of ULF (ultra-low-frequency) electromagnetic waves into the ionosphere is related to the spatial distribution of electron and ion densities at different time and locations, in which the ion density has less effect than electron density on the field intensity. Compared with different frequency signals, the minimum values of electric and magnetic field excited by earthquakes can be detected by satellite in current detection capability have also been calculated, and the lower frequency wave can be detected easier.

Quantenresonanzen der Ultraschallverstärkung in Wismut

1966 ◽  
Vol 21 (9) ◽  
pp. 1443-1462 ◽  
Author(s):  
K. Walther
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Signal Amplification ◽  
Shear Waves ◽  
Zero Magnetic Field ◽  
Acoustic Attenuation ◽  
Field Range ◽  
Drift Field ◽  
Quantum Resonances

Build-up of ultrasonic noise and ultrasonic amplification in a bismuth sample subjected simultaneously to an electric and a magnetic field are investigated. The ultrasonic noise is generated in the direction of carrier drift. Under conditions of ultrasonic amplification the quantum resonances of the magneto-acoustic attenuation in Bi are “inverted”, i. e. maxima of attenuation are converted into minima by the application of a suitable electric field. Estimated values of the de-attenuation caused by the electric drift field range around 100 db/cm, the gain referred to the attenuation at zero magnetic field being 22 db/cm for shear waves at 265 Mc/s. Optimum signal amplification corresponds to a minimum of generated ultrasonic noise.

Sign in / Sign up

Export Citation Format

Share Document