On extensions of some classes of algebras

The paper consists of three parts. In the first part we discuss on extensions of Lie algebras and their importance in Physics. Then we deal with the extensions of some classes of algebras with one binary operation. The third part is devoted to the study of extensions of two classes of algebras, possessing two algebraic operations, called dialgebras. In all the cases we propose 2-cocycles and respective extensions. The motivation to study the extensions is to use them further for the classification problem of the classes algebras considered in low dimensional cases

Calculation Of Total Wash Under The Bridge Based On Guideline Flow Velocities

Many years of study, modeling, and theoretical studies of the working conditions of bridge crossings have made it possible to significantly improve the methods of determining the size of clear spans under large and medium-sized bridges. Prof. The further development of the method, founded by NA Belelyubsky, consisted in calculating the flow rate at which the under-bridge washout stops. The need for velocity calculation arose after observations of the phenomenon of bridge span washes often stopping at average flow velocities rather than domestic velocities

Calculation Of Total Wash Under The Bridge Based On Guideline Flow Velocities

Many years of study, modeling, and theoretical studies of the working conditions of bridge crossings have made it possible to significantly improve the methods of determining the size of clear spans under large and medium-sized bridges. Prof. The further development of the method, founded by NA Belelyubsky, consisted in calculating the flow rate at which the under-bridge washout stops. The need for velocity calculation arose after observations of the phenomenon of bridge span washes often stopping at average flow velocities rather than domestic velocities

Multiwavelength behaviour of the blazar 3C 279: decade-long study from gamma-ray to radio

We report the results of decade-long (2008-2018) gamma-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, Fermi and Swift data, as well as polarimetric and spectroscopic data. The X-ray and gamma-ray light curves correlate well, with no delay greater than or similar to 3 h, implying general cospatiality of the emission regions. The gamma-ray optical flux flux relation changes with activity state, ranging from a linear to a more complex dependence. The behaviour of the Stokes parameters at optical and radio wavelengths, including 43 GHz Very Long Baseline Array images, supports either a predominantly helical magnetic field or motion of the radiating plasma along a spiral path. Apparent speeds of emission knots range from 10 to 37c, with the highest values requiring bulk Lorentz factors close to those needed to explain gamma-ray variability on very short time-scales, The Mg II emission line flux in the 'blue' and 'red' wings correlates with the optical synchrotron conlinuum flux density, possibly providing a variable source of seed photons for inverse Compton scattering. in the radio bands, we find progressive delays of the most prominent light-curve maxima with decreasing frequency, as expected from the frequency dependence of the tau = 1 surface of synchrotron self-absorption. The global maximum in the 86 GHz light. curve becomes less prominent at lower frequencies, while a local maximum, appearing in 2014, strengthens toward decreasing frequencies, becoming pronounced at similar to 5 GHz, These tendencies suggest. different Doppler boosting of stratified radio-emitting zones in the jet