The spacetime singularities in classical general relativity are inevitable, which are also predicated by the celebrated singularity theorems. However, it is general belief that singularities do not exist in the nature and they are the limitations of the general relativity. In the absence of a well defined quantum gravity, models of regular black holes have been studied. We employ probability distribution inspired mass function $m(r)$ to replace Kerr black hole mass $M$ to present a nonsingular rotating black hole that is identified asymptotically ($r \gg k$, $k>0$ constant) exactly as the Kerr-Newman black hole, and as the Kerr black hole when $k=0$. The radiating counterpart renders a nonsingular generalization of Carmeli's spacetime as well as Vaidya's spacetime, in the appropriate limits. The exponential correction factor changing the geometry of the classic black hole to remove curvature singularity can be also motivated by the quantum arguments. The regular rotating spacetime can also be understood as a black hole of general relativity coupled to nonlinear electrodynamics.

A nonsingular rotating black hole

We study thermodynamical structure of Einstein black holes in the presence of power Maxwell invariant nonlinear electrodynamics for two different cases. The behavior of the temperature and conditions regarding the stability of these black holes are investigated. Since the language of geometry is an effective method in general relativity, we concentrate on the geometrical thermodynamics to build a phase space for studying phase transition. In addition, taking into account the denominator of the heat capacity, we use the proportionality between cosmological constant and thermodynamical pressure to extract the critical values for these black holes. Besides, the effects of the variation of different parameters on thermodynamical structure of these black holes are investigated. In addition, some thermodynamical properties such as volume expansion coefficient, speed of sound and isothermal compressibility coefficient are calculated and some remarks regarding these quantities are given.

Geometrical thermodynamics and P-V criticality of the black holes with power-law Maxwell field

. This paper is related to the study of the ion density recorded by the low altitude satellite DEMETER. In a first time there is an automatic search for ionospheric perturbations in the complete satellite data set of ion densities. Then perturbations due to known ionospheric phenomena (for example, solar activity) are eliminated as well as perturbations not above a seismic zone. In a second time, there is a search to know if each selected perturbation corresponds to a future earthquake. The earthquakes have been classified depending on their magnitude and depth. This attempt to predict earthquakes of course generates false alarms and wrong detections. The results of this statistical analysis are presented as function of various parameters. It is shown that the number of false alarms is very important, because the ionosphere has variations not only linked to the seismic activity. The number of wrong detections is also important and can be explained by the fact that the satellite is above a seismic area only a few minutes per day and we do not expect continuous perturbations from a given earthquake. The more important results of this study is that the ratio between detected earthquakes and earthquakes to be detected increases with the magnitude of the earthquakes which intuitively makes sense.

/pdf/real-time-analysis-of-the-ion-density-measured-by-the-3vzrzn0oht.pdf

"Real time analysis" of the ion density measured by the satellite DEMETER in relation with the seismic activity

第１章 地圏で発生する電磁気現象（日本における地震に関連する地電位差観測；北海道における地震電磁気観測研究；Ｅａｒｔｈｑｕａｋｅ ｐｒｅｄｉｃｔｉｏｎ ｂａｓｅｄ ｏｎ Ｓｅｉｓｍｉｃ Ｅｌｅｃｔｒｉｃ Ｓｉｇｎａｌｓ．Ｒｅｃｅｎｔ ａｄｖａｎｃｅｓ ｏｆ ｔｈｅ ＶＡＮ ｍｅｔｈｏｄ． ほか） 第２章 大気圏で発生する電磁気現象（Ａｔｍｏｓｐｈｅｒｉｃ Ｓｉｇｎａｌｓ Ａｓｓｏｃｉａｔｅｄ ｗｉｔｈ Ｍａｊｏｒ Ｅａｒｔｈｑｕａｋｅｓ．Ａ Ｍｕｌｔｉ‐Ｓｅｎｓｏｒ Ａｐｐｒｏａｃｈ．；Ｏｎ ｔｈｅ ｌｉｔｈｏｓｐｈｅｒｅ‐ａｔｍｏｓｐｈｅｒｅ ｃｏｕｐｌｉｎｇ ｏｆ ｓｅｉｓｍｏ‐ｅｌｅｃｔｒｏｍａｇｎｅｔｉｃ ｓｉｇｎａｌｓ ａｎｄ ｉｄｅｎｔｉｆｉｃａｔｉｏｎ ｏｆ ｔｈｅｉｒ ｓｏｕｒｃｅｓ；見通し内ＶＨＦ帯伝搬異常と地震発生の統計的関連性 ほか） 第３章 電離圏で発生する電磁気現象（ＶＬＦ／ＬＦ送信局電波を用いた電離圏擾乱観測に基づく地震予知研究；Ｓｅａｒｃｈ ｆｏｒ ｅｌｅｃｔｒｏｍａｇｎｅｔｉｃ ｅａｒｔｈｑｕａｋｅ ｐｒｅｃｕｒｓｏｒｓ ｂｙ ｍｅａｎｓ ｏｆ ｓｏｕｎｄｉｎｇ ｏｆ ｕｐｐｅｒ ａｔｍｏｓｐｈｅｒｅ‐ｌｏｗｅｒ ｉｏｎｏｓｐｈｅｒｅ ｂｏｕｎｄａｒｙ ｂｙ ＶＬＦ／ＬＦ ｓｉｇｎａｌｓ；Ｓｈｏｒｔ Ｔｅｒｍ Ｅａｒｔｈｑｕａｋｅ Ｐｒｅｄｉｃｔｉｏｎ Ｕｓｉｎｇ ＶＬＦ ｏｂｓｅｒｖａｔｉｏｎｓ：Ａｎ ＩＣＳＰ Ｉｎｉｔｉａｔｉｖｅ ｉｎ Ｉｎｄｉａｎ Ｓｕｂ‐ｃｏｎｔｉｎｅｎｔ ほか）

地震予知研究の最前線 : 地震予知学・耐震工学・地震学の融和をめざして = The frontier of earthquake prediction studies

This chapter contains sections titled: RF and Microwave Frequency Ranges Fields Electromagnetics RF and Microwave Energy Penetration in Biological Tissues and Skin Effect Relaxation, Resonance, and Display Dielectric Measurements Exposure References Problems

Fundamentals of Electromagnetics

[1] Employing borehole and terrestrial antennas, vertical electric field components of the naturally occurring very low frequency electromagnetic emissions at the frequency of 3 kHz have been monitored simultaneously at Agra (geographic latitude 27.8°N, longitude 78°E), India, from 15 March 1999 to 30 September 1999. This period of observation included a major seismic swarm activity in the months of March and April which occurred in the Chamoli hills of north India, the next two months of May and June being quiet with respect to local lightning and spheric activities, and the rest of the three months from July to September being highly disturbed due to local lightning and thunderstorm activities. The abnormal electric field changes occurred in the form of noise bursts of varying amplitude and duration and included three kinds of data: (1) noise bursts observed by borehole antenna only, (2) noise bursts observed by terrestrial antenna only, and (3) noise bursts observed by both the antennas. We find that the occurrence of the first kind of data is positively correlated with major seismic activities in the region over the period of observations. The third kind of data indicates coupling between the two antennas dominated overall by atmospheric emissions. The long distance propagation of the seismo-electromagnetic emissions through the middle layer crust working as waveguide or through seismic faults is found to be associated with large attenuation ≈13 dB/km. Hence, the observation of the emissions at Agra, about 400 km from Chamoli, is interpreted in terms of leakage to the atmosphere through “windows” of low conductivity in the skin layer near the epicenter, possibly produced by some geophysical formations as discussed by other workers and then propagation in the Earth-ionosphere waveguide.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2002RS002683

On the lithosphere‐atmosphere coupling of seismo‐electromagnetic signals

We present an exact solution of Bardeen AdS black hole in massive gravity theory by taking into account the massive gravity parameter m and study its thermodynamic properties such as temperature, entropy and heat capacity at constant pressure. We also study the critical behaviour of Bardeen AdS massive black holes by taking the cosmological constant $$\Lambda $$
 as the thermodynamic pressure, and it is shown that thermodynamic volume is independent of the massive gravity parameter m. In addition to these, we investigate the dependence of critical parameters on the massive gravity parameter (m) and magnetic monopole charge (e). It is observed that the critical exponents (critical temperature and critical pressure) increase with massive gravity parameter but decrease in the presence of magnetic monopole charge. Also the numerical value of ratio $$P_\mathrm{c}r_\mathrm{c}/T_\mathrm{c}$$
 increases with increase in the values of the parameters m and e.

Extended phase space thermodynamics of Bardeen black hole in massive gravity

VLF electromagnetic noise bursts observed in a borehole and their relation with low-latitude hiss

A multi-experiment approach to ascertain electromagnetic precursors of Nepal earthquakes

This paper presents an exact solution of Bardeen black hole in presence of massive gravity, which is characterized by the additional parameter $m$. Here, we focus on $4D$ Bardeen AdS massive black hole solutions as example to discuss the thermodynamical properties such as temperature, entropy and specific heat at constant pressure. We also study the critical behaviour of Bardeen AdS massive black holes by considering the cosmological constant $\Lambda$ as thermodynamical variable (pressure) as well as the parameter associated with the nonlinear electrodynamics. We calculate the critical value of pressure and temperature and study the effect of magnetic charge $e$ and mass parameter $m$. It is seen that the thermodynamical volume are the independent of mass parameter $m$. The critical values are the one in which phase transition takes place and the nature of mass parameter $m$ and magnetic charge $e$ are opposite to each other. The critical temperature and pressure were highly sensitive for these parameters.

Raj Pal Singh

Papers

On the lithosphere‐atmosphere coupling of seismo‐electromagnetic signals

Extended phase space thermodynamics of Bardeen black hole in massive gravity

VLF electromagnetic noise bursts observed in a borehole and their relation with low-latitude hiss

A multi-experiment approach to ascertain electromagnetic precursors of Nepal earthquakes

Extended phase space thermodynamics for Bardeen black holes in massive gravity