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We study the generation of electromagnetic fields during inflation in a model with kinetic and axial couplings to the inflaton field using the gradient expansion formalism. This formalism allows us to simultaneously take into account the possible presence of two nonlinear phenomena: (i) the backreaction of the generated electromagnetic fields on the evolution of the inflaton and (ii) the creation of pairs of charged fermions from the physical vacuum (the Schwinger effect). We model the latter phenomenon by using the generalized Ohmic form of the induced current, J → = σ E E → + σ B B → , with σ E and σ B being the electric and magnetic conductivities. We derive the system of equtions of the gradient expansion formalism for generic kinetic and axial coupling functions as well as Schwinger conductivities. Further, in order to test our system of equations, we apply it to a specific case of the kinetic coupling in the exponential Ratra form and the linear axial coupling function for a few benchmark points in the parameter space. To estimate the accuracy of the obtained numerical results, we perform a comparison with the results of mode-by-mode solution in the Fourier space. We show that the backreaction causes a noticeable increase in the duration of the inflationary epoch while the Schwinger effect strongly suppresses the produced electromagnetic fields and lifts their backreaction.

Purpose. Development of selective microprocessing earth fault protection in compensated electrical networks of 6‒35 kV. Use of the Goertzel algorithm for the separation of components of frequencies higher than fundamental frequency from the zero sequence voltage and currents. Methodology. The methods of mathematical modeling and analysis of transients in compensated electric networks of 6‒35 kV, Fourier transform and Goertzel algorithm, construction of earth-fault protection algorithms, and experimental research are used. Findings. The results of mathematical modeling show that in compensated electric networks of 6‒35 kV at phase-to-ground fault the reactive power direction in a in a damaged feeder1can be similar to the one in an undamaged feeder1; therefore, conventional protections cannot perform selective operation. This action can be provided by protections based on separation of components of fixed frequencies of 200‒300 Hz from the zero sequence voltage and currents. Their reactive power in an undamaged connection is always directed offtyres, because is hardly compensated by the reactor regardless of degree of its cavity tuning. When applying band-pass frequency filters, the required protection responsivity is not always provided at phase-to-ground fault through resistances exceeding 10‒15 Ohm. Moreover, failure of steady operation of filters is possible due to location of their poles on a circular curve of a unit radius, while use of blocks of numerical differentiation of current and voltage can result in running failure at alternate arcing ground. The application of the Goertzel algorithm for high-frequency components detection is proposed. It is implemented through an infinite impulse-response filter of the second order with two real coefficients in back coupling and one complex coefficient in circuit of direct relation. The results of simulation of the behavior of protection in the system of computer algebra Mathcad confirmed the reduction of calculation costs and stable work, regardless of the presence of aperiodic components at different initial phases of the voltage at the time of fault. As part of the protection, a trigger unit is provided that allows the operation if the voltage of the zero sequence exceeds the setpoint, which is 12‒15 % of the nominal value. In order to ensure reliable operation of the protection, permanent and arcing faults provide activation of protection impulses in the event of a fault. The positive results of protection algorithm were achieved on the mathematical model of the network as well as when testing a microprocessor prototype of a protective system in a laboratory environment. Originality. For the first time for ground-fault protection in 6‒35 kV compensated networks, it is proposed to separate components of frequencies higher than fundamental frequency from the zero sequence voltage and currents using frequency filters created on the basis of the Goertzel algorithm are proposed; the algorithm is an improved modification of the Fourier transform; this increased the sensitivity, speed and stability of work protection. Practical value. The mathematical model of the compensated electric network allows analyzing the behavior of protection at permanent and arcing ground faults. Selective protection from phase faults on the ground has been developed, which allows increasing the reliability of the power supply systems with a voltage of 6‒35 kV.

The long-term (1980−2018) data on the water temperature regime and associated synoptic processes in favorable and unfavorable years of the abundance formation and the pink salmon Oncorhynchus gorbuscha return to the rivers of the Sea of Japan coast in Primorskii krai have been analyzed. It is shown that low catches of Primorye pink salmon at the end of the past century were accompanied by negative temperature anomalies in the coastal waters and increasing catches during the first two decades of the new century were accompanied by positive temperatures anomalies. Pink salmon returns to rivers at the sea-water temperature 8.6−14.9°С, and values below 3.0–4.0°С are one of the reasons of redistribution of anadromous migratory flows of pink salmon in the Primorye subzone. The synoptic and hydrological situation at different intensity of pink salmon return is described using concrete examples. With a high frequency of cold air troughs typical for the first cold stage of the Far Eastern monsoon caused by the Okhotsk anticyclone, the pink salmon return was delayed and extremely high catches were recorded when the second (warm) stage of the summer monsoon strengthened due to spreading of the Hawaiian anticyclone in the Sea of Japan. The results may be used for short-term prediction of the dynamics of the Primorye pink salmon return.

Introduction. A significant proportion of earth faults in 6 - 35 kV networks is a transient and short-lived process, which is followed by an electric arc. Problem. In such cases, earth-fault protection that responds to steady-state current and voltage is not able to operate properly. Also, the use of the Petersen coil to compensate for the capacitive earth fault current complicates the protection function because it significantly reduces the single phase earth fault current in steady state. Purpose. To develop selective single-phase earth faults protection algorithm using harmonic components that occur in zero-sequence currents and voltage in the transient process. Method. A mathematical model of the power supply system is applied to study the frequency components of currents and voltage of zero sequence in compensated electrical networks with phase-to-earth faults, and a mathematical model is used to test the operation of the developed protection algorithm. The results showed that, the reactive power for harmonic components of the frequency greater than 100 Hz, which are separated from the current and voltage of zero sequence in compensated electrical networks on the damaged feeder, is positive regardless of the degree of compensation of the capacitive current. That may be the basis of the principle of directional protection. Originality. Phase-to-earth fault selective protection algorithm has been developed. In that algorithm, first derivatives of currents and voltages of zero sequence are found, to reduce the influence of aperiodic components. And then, by using of the Fourier transform, a number of harmonic orthogonal components are extracted from them. Reactive power is calculated for each of frequency component and their total sum is found. If that sum excess of threshold, the relay will make a decision. The reliability of the developed protection algorithm is confirmed by the results of mathematical modeling and verification of the test sample at the laboratory stand and by means of field signals that were recorded by digital loggers at the substations.

Introduction. A significant proportion of earth faults in medium voltage networks represents a short-lived and transient process. Problem. In such cases, earth fault protection that responds to steady-state current and voltage is not able to operate properly. Purpose. To develop earth faults protection selective algorithm using transient components, that occur in zero- sequence currents and voltage in the fault process. Method. A mathematical model of the power supply system was applied to study the transient components of currents and voltage of zero sequence in compensated electrical networks with phase-to-earth faults, and a those model also is used to test the operation of the developed protection algorithm. The results showed that, the reactive power for transient components, of the frequency greater by 4-6 times, than fundamental frequency, which are extracted from the current and voltage of zero sequence by wavelet transform in compensated electrical networks on the damaged feeder, is positive regardless of the degree of compensation of the capacitive current. That may be the basis of the principle of directional protection. Originality. Phase-to-earth fault selective protection algorithm has been developed. In that algorithm, first derivatives of currents and voltages of zero sequence are found, to reduce the influence of aperiodic components. And then, by using of the wavelet transform with Morlet mother function, an orthogonal components are extracted from them. Reactive power is calculated for transient component. If that reactive power excess of threshold, the relay will make a decision. The reliability of the developed protection algorithm is confirmed by the results of mathematical modelling and verification of the test sample at the laboratory stand and by means of field signals that were recorded by digital loggers at the substations. References 10, figures 5. Key words: electrical grid, earth fault protection, current, voltage, zero sequence, wavelet transform, reactive power.

New algorithms have been developed for selective protection against phase-to-earth faults in power supply systems of 6–35 kV. In such, due to the impact of an arc-suppressing compensating reactor (Petersen coil), the selective action of traditional protection devices is not ensured. The purpose of the work is to develop new algorithms for selective protection against phase-to-earth faults in power supply systems with Petersen coil. Mathematical modeling showed that at frequencies of 200–400 Hz, the Petersen coil practically does not reduce the capacitive current in the damaged junction when the phase is shorted to ground, unlike in the case of fundamental frequency. Therefore, to protection device current and voltage with a frequency of 300 Hz are used. This current and voltage are extracted from the current and voltage of zero-sequence using band-pass frequency filters and are used to determine the direction of reactive power. Scientific novelty comprises determining the direction of reactive power using both the current and voltage after the filters, and also their derivatives, which significantly improves the sensitivity and stability of the relay; the performance of filters being controlled depending on the instantaneous values of the zero sequence voltage amplitude, which ensures the stability of the filters; the implementation of a two-channel protection relay for receiving a constant (instead of a pulsating) signal at the output device. The effectiveness of the developed protection is confirmed by the results of the mathematical modeling, tests on a laboratory bench and the supply of full-scale signals registered by the recorders in real networks.

In this paper, an analysis of the wave dynamics of a parametric superheterodyne H-ubitron free-electron laser with a longitudinal wave amplification section is carried out within the cubic nonlinear approximation. A key feature of the studied free-electron laser is the implementation of two interconnected three-wave parametric resonances. The first parametric resonance occurs between the electromagnetic signal and the magnetic field of the H-ubitron pump. The second parametric resonance occurs between the longitudinal field of the electrostatic undulator and the fast and slow space-charge waves. The second parametric resonance pro-vides additional amplification of the slow space-charge wave. The studied model considers the effect of electrostatic pumping field generation, an analysis of the influence of a quasi-electrostatic support field is carried out, and the lengths and saturation levels of such devices are determined. It is demonstrated that, due to the additional amplification of the slow space charge wave in the longitudinal wave amplification section, as well as taking into account the effect of electrostatic pumping field generation, the saturation length of the electromagnetic signal wave is reduced by 18%. To increase the output electromagnetic signal's saturation level, we propose using a quasi-electrostatic support field, in which the electrostatic field strength in-creases linearly starting from a specific coordinate. It is demonstrated that an optimal quasi-electrostatic support field allows us to increase the output saturation level of the electromagnetic signal by more than 130%. Thus, the use of a parametric superheterodyne H-ubitron free-electron laser with a longitudinal space charge wave amplification section and a quasi-electrostatic support field has several advantages compared to a traditional H-ubitron free-electron laser, namely, a reduction in the longitudinal dimensions of the en-tire device and an increase in the power of the output electromagnetic signal.

Issues in the output signal generation of an atomic clock ensemble and the smooth management of the time scale are considered. Special algorithms are proposed to solve the objectives, making it possible to improve the stability of the output signals against possible reference frequency signal jumps. The operation of the algorithms is demonstrated by means of numerical modeling.

The effects of preparation regimes of poly(vinyl alcohol) carbon fibers on their dimensions and morphology were studied. The mean-statistical values of the geometric cross-sectional parameters of starting, dehydrated, and carbonized filaments were determined. Trends in the carbonization of poly(vinyl alcohol) fibers were found.

The high amplification properties of such a device are ensured by implementing two interconnected three-wave parametric resonances. Due to the first of these resonances between the electromagnetic wave of the signal, the H-ubitron pump magnetic field and the slow space charge wave (SCW), the first one is amplified. The second of these resonances between the longitudinal pump electric field, slow and fast SCWs allows us to increase the slow SCW more. The connection between the two parametric resonances is ensured by the slow SCW common to resonances. In the work, the growth increments of the waves of the above-mentioned three-wave resonances are analysed separately and for the entire system. It has been demonstrated that generating an additional pump electric field significantly affects the growth increment of the second parametric resonance of longitudinal waves, increasing it by 33 %. Due to this, the growth increment of the entire FEL increases by 28 – 10 %, depending on the system parameters. It was found that the influence of the generated pump electric field is most effective at high frequencies and relatively low energies of the electron beam when the amplification of the electromagnetic signal due to the first parametric resonance is significantly less compared to the amplification of longitudinal waves due to the second parametric resonance.