Collective processes in relativistic plasma and their implications for gamma-ray burst afterglows

We consider the effects of collective plasma processes on synchrotron emission from highly relativistic electrons. We find, in agreement with Sazonov (1970), that strong effects are possible also in the absence of a non-relativistic plasma component, due to the relativistic electrons (and protons) themselves. In contrast with Sazonov, who infers strong effects only in cases where the ratio of plasma frequency to cyclotron frequency is much larger than the square of the characteristic electron Lorentz factor, nu_p/nu_B >> gamma^2, we find strong effects also for 1 << nu_p/nu_B << gamma^2. The modification of the spectrum is prominent at frequencies nu < nu_{R*} = nu_p min[gamma, (nu_p/nu_B)^(1/2)], where nu_{R*} generalizes the Razin-Tsytovich frequency, nu_R = gamma nu_p, to the regime nu_p/nu_B << gamma^2. Applying our results to gamma-ray burst (GRB) plasmas, we predict a strong modification of the radio spectrum on minute time scale following the GRB, at the onset of fireball interaction with its surrounding medium, in cases where the ratio of the energy carried by the relativistic electrons to the energy carried by the magnetic field exceeds ~ 10^5. Plausible electron distribution functions may lead to negative synchrotron reabsorption, i.e to coherent radio emission, which is characterized by a low degree of circular polarization. Detection of these effects would constrain the fraction of energy in the magnetic field, which is currently poorly determined by observations, and, moreover, would provide a novel handle on the properties of the environment into which the fireball expands.Comment: 28 pages, 1 figure, submitted to Ap

Gravitational orientation of the orbital complex, Salyut-6--Soyuz

A simple mathematical model is proposed for the Salyut-6-Soyuz orbital complex motion with respect to the center of mass under the one-axis gravity-gradient orientation regime. This model was used for processing the measurements of the orbital complex motion parameters when the above orientation region was implemented. Some actual satellite motions are simulated and the satellite's aerodynamic parameters are determined. Estimates are obtained for the accuracy of measurements as well as that of the mathematical model

Quantum interference in the classically forbidden region: a parametric oscillator

We study tunneling between period two states of a parametrically modulated oscillator. The tunneling matrix element is shown to oscillate with the varying frequency of the modulating field. The effect is due to spatial oscillations of the wave function and the related interference in the classically forbidden region. The oscillations emerge already in the ground state of the oscillator Hamiltonian in the rotating frame, which is quartic in the momentum.Comment: Submitted to PR

Research of high-current pulsed electron beam energy distribution in depth of sheet of water

Distribution of the absorbed doze and energy of the high-current pulsed electron beam formed by accelerator TEU-500 (350...500 kV, 60 ns, current density 0,3...0,4 kA/sm2) in water sheet depth has been measured. The high-resolution measurement technique of doze and energy distribution with application of dosimetric film based on lavsan with phenazine covering was used. Spatial resolution at registration of the absorbed doze in the range of 5...100 kGr amounts to 20...30 mkm. It was shown that at absorption of electron beam with high current density (in conditions of track overlapping on surface of the absorbing layer) distribution of the absorbed doze in thedepth within the limits of ±10 % coincides with distribution obtained for low-current bea

Production’s digital transformation analysis using Industry 4.0 technologies

The article is devoted to a detailed analysis of the industry’s digital transformation processes based on the use of Industry 4.0 technologies. The theoretical analysis made it possible to establish that technological trends are often in the spotlight, however, the need for transformation is not posed by technology as such, but by deep shifts in the enterprise’s external environment caused by digitalization. The study of industry transformation global mechanisms allowed the article’s authors to identify eight key levers necessary for creating value due to the Industry 4.0 technologies implementation at a high-tech production. In conclusion, the authors consider the technological transformation process in Russia, as well as the main directions that can effectively accelerate it

New Kinds of Acoustic Solitons

We find that the modified sine-Gordon equation belonging to the class of the soliton equations describes the propagation of extremely short transverse acoustic pulses through the low-temperature crystal containing paramagnetic impurities with effective spin S=1/2 in the Voigt geometry case. The features of nonlinear dynamics of strain field and effective spins, which correspond to the different kinds of acoustic solitons, are studied.Comment: 9 pages, 1 figur

A hard X-ray survey of the Crux Galactic spiral arm tangent. A catalog of sources

This work is part of a large solid angle hard X-ray survey. We analized a number of observations by the IBIS telescope aboard the INTEGRAL observatory covering the Crux Galactic spiral arm tangent. We have detected 46 hard X-ray sources, with 15 of them being new. Among the identified sources there are 12 AGNs, 11 HMXBs, 6 LMXBs and 2 active stars. 13 sources remain unidendified.Comment: Accepted for publication in Astronomy Letter

Geometrical parametres of the adaptive unit for industrial robots’ gripper calculation

Виконано аналіз конструктивних особливостей вузла адаптації схвата промислового робота. У результаті аналізу виявлено ряд залежностей геометричних параметрів конструктивних елементів компенсаторів кутових похибок від величин похибок позиціонування схватів промислових роботів. Наведено аналітичні вирази для розрахунку вказаних конструктивних параметрів.The need to carry out investigations on the raise of accuracy and decrease of negative after-effect of pose error for the principal and auxiliary technical equipment is caused by the availability of errors in the robotized installation. One of the possible methods for negative influence decrease arising in the robotized technological service of facilities, which is industrial robots gripper adaptation, is considered in the article. Industrial robots’ gripper adaptation expects to apply additional facilities, so-called “Industrial Robots’ Adaptive Unit”. Compliance of the Adaptive Unit for Industrial Robots’ Grippers compensative element is achieved due to using of compensative spring elements, which are included into the compliant mechanisms construction. Using of the linear and angular errors compensator in the Adaptive Unit for Industrial Robots’ Grippers allows to overcome negative force-torque influence which arises at the moment of handling object fixing in the working position device. In the article the analysis of the constructive peculiarities of the Adaptive Unit for Industrial Robots’ Grippers has been carried out. As the analysis result dependencies of the angular error compensator constructive elements geometrical parameters on the industrial robots pose errors have been found. The analytical expressions for calculation of the mentioned construction parameters of the Adaptive Unit for Industrial Robots’ Grippers have been presented. Analytical dependences, which are connected with the geometric parameters of the Adaptive Unit for Industrial Robots’ Grippers constructive elements and take into account the length of handling object and distance of industrial robots’ grippers pole from the left end face of the handling object in its coordinate system, have been found. The obtained results make possible to calculate and choose the Adaptive Unit for Industrial Robots’ Grippers, which is necessary for certain conditions of mechanical assembly manufacturing

Obtaining the fine-grained silicon carbide, used in the synthesis of construction ceramics

Silicon carbide is used in the production of construction and temperature-resistant goods, capable of withstanding high mechanical and thermal loads. During recent times, silicon carbide has been frequently used in the electronics industry. Since sintered silicon carbide has increasingly been used as a replacement for metal components of various devices, the process of obtaining compact goods from silicon powder has become the defining factor in the technology used for its synthesis. The selection of conditions in which the sintering is conducted depends on granulometric structure, the form and the surface condition of the initial powder. The work consists of the synthesis of silicon carbide powder using the purified form of metallurgical silicon powder and soot. The qualities of testing samples were studied, where silicon carbide was obtained using established technology, from mechanically activated elementary, fine-grained silicon and soot, by pyrolytic synthesis. It was demonstrated that synthesis produces highly pure silicon carbide powder, (α- and β-phases) with a granulometric composition that allowed subsequent sintering to produce high quality compact goods. It was established that the content of silica in synthesized silicon carbide powder does not exceed 1-2% of the total mass