Determination of the polarization characteristics of the large Pulkovo radio telescope

1973 ◽  
Vol 16 (5) ◽  
pp. 506-510
Author(s):  
N. A. Esepkina ◽  
N. S. Bakhvalov ◽  
L. G. Vasil'eva ◽  
N. S. Soboleva ◽  
A. V. Temirova
Keyword(s):  
Radio Telescope ◽  
Polarization Characteristics ◽  
Large Pulkovo Radio Telescope

scholarly journals Numerical Model for Simulation of the Cathodic Protection System with Dynamic Nonlinear Polarization Characteristics

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Numerical Model ◽  
Current Density ◽  
Cathodic Protection ◽  
Electric Potential ◽  
Protection System ◽  
Nonlinear Polarization ◽  
Electrode Surfaces ◽  
Polarization Characteristics ◽  
Cathodic Protection System

Cathodic protection is defined as a method for slowing down or complete elimination of corrosion processes on underground or underwater, insulated or uninsulated metal structures. Protection by cathodic protection system is achieved by polarizing protected object to more negative value, with respect to its equilibrium potential. Design of the cathodic protection system implies determination of the electric potential and current density on the electrode surfaces after installation of the cathodic protection system. Most efficient way for determination of the electric potential and current density in the cathodic protection system is by applying numerical techniques. When modeling cathodic protection systems by numerical techniques, electrochemical reactions that occur on electrode surfaces are taken into account by polarization characteristics. Because of nature of the electrochemical reactions, polarization characteristics are nonlinear and under certain conditions can be time – varying (dynamic nonlinear polarization characteristics). This paper deals with numerical modeling of the cathodic protection system with dynamic nonlinear polarization characteristics. Numerical model presented in this paper is divided in the two parts. First part, which is based on the direct boundary element method, is used for the calculation of the distribution of electric potential and current density on the electrode surfaces in the spatial domain. Second part of the model is based on the finite difference time domain method and is used for the calculation of the electric potential and current density change over time. The use of presented numerical model is demonstrated on two simple geometrically examples.

The Tanaka-Enome criterion and solar activity in October?November 2003 as observed by the Large Pulkovo Radio Telescope

2004 ◽  
Vol 42 (6) ◽  
pp. 561-570 ◽  
Author(s):  
T. P. Borisevich ◽  
G. N. Il?in ◽  
A. N. Korzhavin ◽  
N. G. Peterova ◽  
N. A. Topchilo ◽  
...  
Keyword(s):  
Solar Activity ◽  
Radio Telescope ◽  
Large Pulkovo Radio Telescope

THE POLARIZATION CHARACTERISTICS OF Pi-2 MICROPULSATIONS AND THEIR RELATION TO THE DETERMINATION OF POSSIBLE SOURCE MECHANISMS FOR THE PRODUCTION OF NIGHTTIME IMPULSIVE MICROPULSATION ACTIVITY

1967 ◽  
Vol 45 (3) ◽  
pp. 1319-1335 ◽  
Author(s):  
Gordon Rostoker
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Horizontal Plane ◽  
Auroral Zone ◽  
Propagation Path ◽  
Source Mechanisms ◽  
Polarization Characteristics ◽  
Direction Of Polarization

From the analysis of 20 separate events it is shown that Pi-2 micropulsations are polarized in an anticlockwise sense in the horizontal plane at northern-hemisphere mid-latitude stations. Combined with the knowledge that in the southern hemisphere polarization is predominantly in the clockwise sense, it can be inferred that at least the last part of the propagation path of the Pi 2 from the auroral zone to the observing station is traversed in the Alfvén mode. The presence of occasional pulsations possessing clockwise polarization in the northern hemisphere and anticlockwise polarization in the southern hemisphere suggests that the Alfvén mode alone is insufficient to explain the mode of propagation of a Pi 2. It is shown how ionospheric screening may influence the direction of polarization of a micropulsation. It is found that the initial kick of a Pi-2 micropulsation is strongly related to the sign of the accompanying geomagnetic bay. Deviations from this trend are discussed and it is shown that the Pi-2 micropulsation train and the initial kick may be considered as two separate effects. A theory for the origin of Pi-2 micropulsations is proposed.

scholarly journals The extraordinary composition of the blue comet C/2016 R2 (PanSTARRS)

2018 ◽  
Vol 619 ◽  
pp. A127 ◽  
Author(s):  
N. Biver ◽  
D. Bockelée-Morvan ◽  
G. Paubert ◽  
R. Moreno ◽  
J. Crovisier ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Heliocentric Distance ◽  
Abundance Ratio ◽  
Visible Spectroscopy ◽  
Production Rates ◽  
Sulfur Species ◽  
Upper Limits ◽  
Multi Wavelength ◽  
Rare Group

We present a multi-wavelength study of comet C/2016 R2 (PanSTARRS). This comet was observed on 23 and 24 January 2018 with the IRAM 30 m telescope, and in January to March 2018 with the Nançay radio telescope. Visible spectroscopy was performed in December 2017 and February 2018 with small amateur telescopes. We report on measurements of CO, CH3OH, H2CO and HCN production rates, and on the determination of the N2/CO abundance ratio. Several other species, especially OH, were searched for but not detected. The inferred relative abundances, including upper limits for sulfur species, are compared to those measured in other comets at about the same heliocentric distance of ~2.8 AU. The coma composition of comet C/2016 R2 is very different from all other comets observed so far, being rich in N2 and CO and dust poor. This suggests that this comet might belong to a very rare group of comets formed beyond the N2 ice line. Alternatively, comet C/2016 R2 (PanSTARRS) could be the fragment of a large and differentiated transneptunian object, with properties characteristic of volatile-enriched layers.

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