10 research outputs found
Binary Pulsar Tests of General Relativity in the Presence of Low-Frequency Noise
The influence of the low-frequency timing noise on the precision of
measurements of the Keplerian and post-Keplerian orbital parameters in binary
pulsars is studied. Fundamental limits on the accuracy of tests of alternative
theories of gravity in the strong-field regime are established. The
gravitational low-frequency timing noise formed by an ensemble of binary stars
is briefly discussed.Comment: 4 pages, contributed paper to the proceedings of the IAU167
colloquium on pulsars, Bonn, August-September 199
Electromagnetic Pulse Propagation over Nonuniform Earth Surface: Numerical Simulation
We simulate EM pulse propagation along the nonuniform earth surface using so
called time-domain parabolic equation. To solve it by finite differences, we
introduce a time-domain analog of the impedance boundary condition and a
nonlocal BC of transparency reducing open computational domain to a strip of
finite width. Numerical examples demonstrate influence of soil conductivity on
the wide-band pulse waveform. For a high-frequency modulated EM pulse, we
develop an asymptotic approach based on the ray structure of the monochromatic
wave field at carrier frequency. This radically diminishes the computation
costs and allows for pulsed wave field calculation in vast domains measured by
tens of thousands wavelengths
Millisecond and Binary Pulsars as Nature's Frequency Standards. III. Fourier Analysis and Spectral Sensitivity of Timing Observations to Low-Frequency Noise
This paper discusses spectral sensitivity of solitary and binary pulsars to a
low-frequency (colored) noise. It is a third paper in a series of papers
devoted to analysis of the low-frequency noise in pulsar timing observations
and its impact on observable fitting parameters of timing model.Comment: 25 pages, 3 figures, accepted to MNRA
Search for Chelyabinsk Meteorite Fragments in Chebarkul Lake Bottom (GPR and Magnetic Data), Journal of Telecommunications and Information Technology, 2017, nr 3
The paper summarizes experimental efforts of the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) undertaken in search of the biggest part of Chelyabinsk meteorite in the bottom of lake Chebarkul, South Ural, Russia, and to estimate the ecological effects of its subsequent excavation
Spatial Distribution of Black Carbon Concentrations in the Atmosphere of the North Atlantic and the European Sector of the Arctic Ocean
We discuss the measurements of black carbon concentrations in the composition of atmospheric aerosol over the seas of the North Atlantic and European sector of the Arctic Ocean (21 expeditions in 2007â2020). The black carbon concentrations were measured by an aethalometer and filter method. The comparison of the two variants of the measurements of the black carbon concentrations showed that the data acceptably agreed and can be used jointly. It is noted that the spatial distribution of black carbon over the ocean is formed under the influence of outflows of air masses from the direction of continents, where the main sources of emission of absorbing aerosol are concentrated. We analyzed the statistical characteristics of black carbon concentrations in five marine regions, differing by the outflows of continental aerosol. The largest black carbon content is a salient feature of the atmosphere of the North and Baltic Seas, surrounded by land: average values of concentrations are 210 ng/m3, and modal values are 75 ng/m3. In other regions (except in the south of the Barents Sea), the average black carbon concentrations are 37â44 ng/m3 (modal concentrations are 18â26 ng/m3). We discuss the specific features of the spatial (latitude-longitude) distributions of black carbon concentrations, relying on ship-based measurements and model calculations (MERRA-2 reanalysis data). A common regularity of the experimental and model spatial distributions of black carbon is that the concentrations decrease in the northern direction and with the growing distance from the continent: from several hundred ng/m3 in the southern part of the North Sea to values below 50 ng/m3 in polar regions of the ocean