scholarly journals A Framework for Efficient Calculation of Photoionization and Photodetachment Rates With Application to the Lower Ionosphere

2020 ◽  
Vol 125 (7) ◽  
Author(s):  
Reza Janalizadeh ◽  
Victor P. Pasko
Keyword(s):  
Lower Ionosphere ◽  
Efficient Calculation ◽  
Photoionization And Photodetachment

Dynamical processes in the lower ionosphere

2003 ◽  
Vol 8 (5-6) ◽  
pp. 76-80 ◽  
Author(s):  
S.V. Panasenko ◽  
◽  
V.T. Rozumenko ◽  
O.F. Tyrnov ◽  
L.F. Chernogor ◽  
...  
Keyword(s):  
Lower Ionosphere ◽  
Dynamical Processes

Efficient calculation of expected shortfall contributions in large credit portfolios

2007 ◽  
Vol 11 (2) ◽  
pp. 1-43 ◽  
Author(s):  
Michael Kalkbrener ◽  
Anna Kennedy ◽  
Monika Popp
Keyword(s):  
Expected Shortfall ◽  
Efficient Calculation

Efficient calculation of interior scattering from cavities with small modifications

2020 ◽  
Vol 56 (2) ◽  
pp. 80-82 ◽  
Author(s):  
Xinlei Chen ◽  
Xiuqiang Liu ◽  
Changqing Gu
Keyword(s):  
Efficient Calculation

scholarly journals Statistical and Criticality Analysis of the Lower Ionosphere Prior to the 30 October 2020 Samos (Greece) Earthquake (M6.9), Based on VLF Electromagnetic Propagation Data as Recorded by a New VLF/LF Receiver Installed in Athens (Greece)

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 676
Author(s):  
Dimitrios Z. Politis ◽  
Stelios M. Potirakis ◽  
Yiannis F. Contoyiannis ◽  
Sagardweep Biswas ◽  
Sudipta Sasmal ◽  
...  
Keyword(s):  
Time Series ◽  
Fresnel Zone ◽  
Lower Ionosphere ◽  
Propagation Path ◽  
Northern Coast ◽  
Analysis Method ◽  
Ionospheric Propagation ◽  
Amplitude Data ◽  
Natural Time ◽  
Criticality Analysis

In this work we present the statistical and criticality analysis of the very low frequency (VLF) sub-ionospheric propagation data recorded by a VLF/LF radio receiver which has recently been established at the University of West Attica in Athens (Greece). We investigate a very recent, strong (M6.9), and shallow earthquake (EQ) that occurred on 30 October 2020, very close to the northern coast of the island of Samos (Greece). We focus on the reception data from two VLF transmitters, located in Turkey and Israel, on the basis that the EQ’s epicenter was located within or very close to the 5th Fresnel zone, respectively, of the corresponding sub-ionospheric propagation path. Firstly, we employed in our study the conventional analyses known as the nighttime fluctuation method (NFM) and the terminator time method (TTM), aiming to reveal any statistical anomalies prior to the EQ’s occurrence. These analyses revealed statistical anomalies in the studied sub-ionospheric propagation paths within ~2 weeks and a few days before the EQ’s occurrence. Secondly, we performed criticality analysis using two well-established complex systems’ time series analysis methods—the natural time (NT) analysis method, and the method of critical fluctuations (MCF). The NT analysis method was applied to the VLF propagation quantities of the NFM, revealing criticality indications over a period of ~2 weeks prior to the Samos EQ, whereas MCF was applied to the raw receiver amplitude data, uncovering the time excerpts of the analyzed time series that present criticality which were closest before the Samos EQ. Interestingly, power-law indications were also found shortly after the EQ’s occurrence. However, it is shown that these do not correspond to criticality related to EQ preparation processes. Finally, it is noted that no other complex space-sourced or geophysical phenomenon that could disturb the lower ionosphere did occur during the studied time period or close after, corroborating the view that our results prior to the Samos EQ are likely related to this mainshock.

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