On the propagation of electromagnetic waves through the atmosphere
A general method of tackling the problem of the propagation of electromagnetic waves in the ionosphere has been developed and the current methods of Appleton, Hartree, Saha, Rai and Mathur, etc., have been deduced as special cases from the general results. The different assumptions by Appleton, Hartree, Bose, Booker and Rai, as regards the condition of reflexion of the waves from the ionosphere, have been shown to be identical. A symbol-correspondence chart for the different symbols used by the different workers has been given to facilitate the understanding of the parallelism between the different methods. Polarization of the radio waves have been discussed fully.
Measurement Of Faraday Rotation In SAR Data Using MST Radar Data
The propagation of radar signals through the atmosphere results in the signals being seriously affected by the ionosphere. Though there are many ionospheric effects on the signal like reflection, refraction, diffraction, absorption, scintillation, and dispersion, this paper focuses on the issue of Faraday Rotation (FR). FR is significant at L-band frequencies and is a major error source deteriorating the quality of the received Synthetic Aperture Radar (SAR) images. FR reduces the accuracy of SAR data recovery if uncorrected. Consequently, the estimation and rectification for FR effects is a prerequisite for valid image interpretation and data analysis. In this paper, we estimate FR from the Mesosphere-Stratosphere-Troposphere(MST) radar data and then apply the calculated FR angle to the corrupted SAR images. Keywords—Faraday rotation (FR), Advanced Land Observing Satellite (ALOS), Mesosphere-StratosphereTroposphere (MST), Phased Array L-band Synthetic Aperture Radar (PALSAR), total electron content (TEC).
The National PKI of Peru: a new certification hierarchy
In order to guarantee secure transactions through the Internet and to generate strong evidence that could be used in case of future legal disputes, several countries around the world have promoted and regulated the use of digital signatures based on Public Key Infrastructure (PKI). However, despite the high expectations, its implementation has achieved neither the desired results nor its globalization. Many of the reasons were discovered years ago, but they are still open problems for the scientific community nowadays. In order to consider the case of the national PKI of the Peruvian state as empirical evidence for studies that address the open problems, this article describes the details about a new certification hierarchy which is expected to overcome some of its predecessors’ limitations. It is also expected that the information disclosed in this article could be useful to other countries for making a preliminary assessment for possible cross-border recognition of Peruvian digital signatures.