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Using machine-learning methods based on self-organising Kohonen maps, the results of numerical simulation of the acceleration of electrons during the interaction of high-power laser radiation with plasma are analysed and classified. The particle-in-cell (PIC) method is used to simulate the interaction in a wide range of parameters (laser intensity and plasma concentration). For each set of parameters, the spectrum of accelerated electrons is found, based on which the charge, average energy, and relative energy spread of accelerated electrons are calculated. Using the obtained values as input parameters of the map, the classification of various acceleration regimes is performed. The developed scheme can be used to identify the optimal acceleration regimes under more realistic conditions, considering a larger number of parameters.

Collisions of ultrarelativistic electron beams are considered using full-scale 3D particle-in-cell simulation. In this process, the particles can be affected by the superintense fields of the counterpropagating beam, and the interaction can pass to the regime of nonperturbative quantum electrodynamics. In this experimentally unexplored regime, the emission of photons and the production of electron – positron pairs are extremely probable processes. It is shown that due to the transverse displacement of the beams and an increase in the number of particles located in the region of the field maximum, it is possible to increase the yield of both photons and electron – positron pairs.

Laser targets with microbubbless have recently been intensely studied, including with the aim of generating superintense electromagnetic fields. Under the action of laser radiation, ion beams are formed in the target, converging to the centre of the microbubbles. In the central region, the ion density can be several times higher than the target density, leading to the generation of an extremely intense electric field and high-energy ions. Using PIC simulation, the dynamics of target electrons is investigated taking into account the effects of quantum electrodynamics (QED) and the development of a QED cascade in the intense field region. It is shown that an increase in the electron temperature leads to a much more efficient formation of electron – positron pairs. The contribution of bremsstrahlung to the generation of photons in the central region of the microbubbles is analysed. It is found that the contribution of bremsstrahlung is insignificant in comparison with the synchrotron mechanism of electron emission in the collective field of ions.

The results of the use of the phytopreparation Tadimax in the treatment of 60 men with mild and moderate lower urinary tract symptoms (LUTS) developed as a result of benign enlargement of the prostate gland are presented. The average age of the patients was 66.5 3.8 years. Tadimax was prescribed 2 tablets 3 times a day, in courses of 7 days with 7 day breaks for 3 months (a total of 6 courses). The data obtained indicate high efficacy and good tolerability of treatment. A decrease in the severity of LUTS was noted in 59 (96.6%) patients, which was accompanied by significant changes in objective clinical indicators: a decrease in residual urine volume and an increase in urine flow rate. Tadimax is a combined preparation, which includes extracts of several medicinal plants, and the main component is Crinum latifolium. The therapeutic effect of Tadimax is based on anti-inflammatory, antiproliferative and immunotropic action.

Variants of the rotation frequency stabilization of a promising vertically axial wind-driven power plant consisting of a doubly connected stator and a rotor with blades are considered. The stator as a whole is part of the construction, axisymmetric with the rotor, and the rotor is slightly buried in the upper part of the stator — the bell. This plant can be included as an element in a complex power plant for additional and emergency power supply of both stationary and mobile objects, for example, surface robotic systems. The paper proposes to use an aerodynamic method of the rotor angular speed stabilization by controlling the positions of two variable design elements of the plant with respect to its stator. As such elements, a lower guide structure (one of the stator elements) and an aerodynamic brake flap can be used. The rearrangement of both elements positions relative to the stator changes the effective cross section for the interaction of the wind flow entering the installation with the rotor. The method of controller synthesis by the angular speed of the rotor rotation is considered in detail. A feature of this controller is the presence of two control channels with one state variable. First, it is necessary to determine the dynamic ranges of torque control on the rotor shaft for each of the variable geometry elements. This allows to correctly select the switching condition between the two control channels depending on the degree of deviation of the desired flow rate from the current speed. Based on the second-order control error equation, the desired control law of the angular rotor speed is obtained. Using the example of the problem solving of angular speed stabilization with given quality criteria, we simulated a synthesized control system for various initial data. It is shown that the constructed controller is capable of effectively countering the influence of wind disturbances in a wide range of deviations of the current speed from the frequency desired for a given target value.

We study changes in the parameters of acoustic emission that develops during quasistatic deformation of parts made of plasticized coarse- and fine-grained HMX under tension. Characteristic changes in acoustic emission dependences and absolute values of acoustic emission parameters have been determined during transition from a coarse- to a fine-grained material structure. In accordance with the results of the experiments, we analyze possible scenarios of the development of the process of damage accumulation and failure of parts with a change in the size of crystals that form their internal structure. As a confirmation of the corresponding changes in the parameters of acoustic emission, we have investigated the structure of the surface of parts in the zones of their failure using an electron microscope. Under tension, the failure of parts based on finely dispersed HMX occurs instantly, when a critical level of damage is reached in any part of the volume and conditions are created for microcracks to combine into macrocracks. For parts containing coarse HMX, failure typically occurs according to the principle of a “weak” link, ie., localization of microcracks in one or several zones over the volume of the deformed material as early as at the initial stage of loading. These zones become the spots where cracks merge and the focus of their further development up to failure at a new scale level. The results obtained expand the existing understanding of the process of damage accumulation and failure of energy-yielding materials and can be used in the development and improvement of relevant mathematical models.

The requirements for modern engines are constantly being tightened in terms of ensuring economic and environmental parameters. Thermodynamic analysis shows that approximately 30-40% of fuel energy is emitted into the environment by exhaust gases. For this reason, obtaining additional energy from exhaust gases is a promising way to significantly improve the thermal efficiency of the engine. Methods for generating additional energy from exhaust gases include: turbocharging, turbocompound, Brighton cycle, Rankine cycle and thermoelectric generators. These methods showed an increase in thermal efficiency, which vary from 2-20%, depending on the design of the system, the quality of energy recovery, component efficiency and implementation. In this work theme of one of the promising options for energy saving in piston engines will be revealed. Unfortunately, the topic turbocompounding in Russia is poorly studied, there are no methods for developing these systems, recommendations for selecting boost units. The aim of this work is to create a turbocompound system for boosting an aircraft engine. In accordance with the goal, the following tasks are formulated and solved: studied domestic and international experience in creating turbocharging systems for turbocharged piston engines; a methodology has been developed for creating turbocharged boost systems for internal combustion engines; recommendations were developed to coordinate the joint operation of a turbocompressor and a power turbine, as well as a turbocompound system with an engine; developed recommendations for choosing a method for regulating turbocompound boost systems. Based on the developed methodology and recommendations, the calculation of the pressurization parameters of the APD - 500 diesel aircraft piston engine with a power of 368 kW was performed. The required characteristics of the blade machines were determined and the required sizes were selected. The choice of turbochargher was made by superimposing the flow characteristics of the APD-500 engine on the characteristics of the compressor stage of the turbochargher. The parameters of the power turbine were calculated, the required gear ratio of the power turbine gearbox was determined.

European physical journal special topics 229(24), 3675 - 4284 (2020). doi:10.1140/epjst/e2020-000127-8, This report presents the conceptual design of a new European research infrastructure EuPRAXIA. The concept has been established over the last four years in a unique collaboration of 41 laboratories within a Horizon 2020 design study funded by the European Union. EuPRAXIA is the first European project that develops a dedicated particle accelerator research infrastructure based on novel plasma acceleration concepts and laser technology. It focuses on the development of electron accelerators and underlying technologies, their user communities, and the exploitation of existing accelerator infrastructures in Europe. EuPRAXIA has involved, amongst others, the international laser community and industry to build links and bridges with accelerator science — through realising synergies, identifying disruptive ideas, innovating, and fostering knowledge exchange. The Eu-PRAXIA project aims at the construction of an innovative electron accelerator using laser- and electron-beam-driven plasma wakefield acceleration that offers a significant reduction in size and possible savings in cost over current state-of-the-art radiofrequency-based accelerators. The foreseen electron energy range of one to five gigaelectronvolts (GeV) and its performance goals will enable versatile applications in various domains, e.g. as a compact free-electron laser (FEL), compact sources for medical imaging and positron generation, table-top test beams for particle detectors, as well as deeply penetrating X-ray and gamma-ray sources for material testing. EuPRAXIA is designed to be the required stepping stone to possible future plasma-based facilities, such as linear colliders at the high-energy physics (HEP) energy frontier. Consistent with a high-confidence approach, the project includes measures to retire risk by establishing scaled technology demonstrators. This report includes preliminary models for project implementation, cost and schedule that would allow operation of the full Eu-PRAXIA facility within 8—10 years., Published by Springer, Heidelberg

Introduction. Power transformers are the basic equipment of the industrial power systems. One of the key indicators of determining the service lifetime of the transformer including its performance characteristics is the condition and residual life of its isolation. Aging and f insulation deprecation are directly related to the operating temperature of the transformer in use, as well as to the reliable operation of the cooling system. This research direction is up-to-date, especially when it comes to fully rated power transformers. Materials and Methods . Power transformers of the district substations that feed the industrial and transport enterprises are considered. Modes of power transformers, which are caused by the uneven workload of the phases and short-circuiting, are studied. All these factors lead to the thermal deformation of the power transformer insulation and, as a rule, to the outage of power transformers. Research Results. The forced cooling system of power transformers, which allows increasing their cooling capacity and the cooling fluid volume, is developed by the authors and described in the paper. Thermal calculations of heating design elements of the power transformers are carried out both in the conventional cooling system and the new one. The comparative analysis and calculations have shown the feasibility of the developed cooling system of power transformers, which allows extending the insulation lifetime. The developed cooling system is forced. The authors used a reserve power transformer tank as an additional expander. This design solution can be implemented for transformers operating at low temperatures, as well as under long-term limit loads. Discussion and Conclusions . The developed cooling system eliminates the requirement for purchase costs on extra equipment and maintenance support. It can be used at the enterprise power facilities and in the rail transportation.

In recent years, there has been a trend of increasing activities in the development of polar territories. Negative temperatures are a characteristic feature of the North. Negative temperatures have a negative impact on the state of power installations of land, air and water transport, mobile, stationary power plants and small-scale mechanization facilities. The engine is least adapted unit for operation in such conditions. There is a chain of negative factors that consistently provides a connection between the state of the lubrication systems and the negative temperatures, in which the equipment is operated. Condensation processes are a primary link in this chain. The existence of condensation processes in the crankcase space when a piston engine is warmed up at negative temperatures is experimentally proved. The percentage of engine oil watering and the dew point temperature of crankcase gases are determined in the conditions of a full-scale experiment. However, the high labor intensity and significant financial costs of organizing such experiments require the search for other methods of testing. A mathematical representation of reality, which allows you to obtain objective and adequate experimental data information, can be one of the ways to solve this problem.

The stabilization of the rotor speed of a promising vertically axial wind-driven power plant is considered. It is proposed to use the aerodynamic method of stabilizing the rotor rotation angular speed by controlling the positions of two variable structural elements of the installation in the question relative to its stator. The controller synthesis technique by the rotor rotation angular speed is considered. A controller feature is the presence of two control channels with one state variable. Based on the second-order control error equation, the desired control law of the angular rotor speed is obtained. The synthesized control system was simulated with various input data. It is shown that the constructed controller is able to effectively counter the influence of wind disturbances in a wide range of deviations of the current speed from the desired frequency for a given target value.

This paper is devoted to a determination of the 0% probability laser-induced damage threshold of the BaGa4Se7 and BaGa2GeSe6 nonlinear elements by the R-on-1 procedure. A Ho:YAG laser radiation at 2091 nm with pulse duration 13-17 ns and varied pulse repetition rate, 2 kHz, 5 kHz and 10 kHz, was used for testing.

Laser induced damage in dark yellow phase of BaGa 4 Se 7 (BGSe) crystal has been investigated at the wavelengths of 1053 nm. Damage by multiple pulse irradiation (500 pulses) has been studied and the probabilistic behavior of the damage is discussed.

Variants of the rotation frequency stabilization of a promising vertically axial wind-driven power plant consisting of a doubly connected stator and a rotor with blades are considered. The paper proposes the use an aerodynamic method of the rotor angular speed stabilization by controlling the positions of two variable design elements of the plant with respect to its stator. As such elements, a lower guide structure (one of the stator elements) and an aerodynamic brake flap can be used. The method of controller synthesis by the angular speed of the rotor rotation is considered in detail. A feature of this controller is the presence of two control channels with one state variable. First, it is necessary to determine the dynamic ranges of torque control on the rotor shaft for each of the variable geometry elements. Based on the second-order control error equation, the desired control law of the angular rotor speed is obtained.Using the example of the problem solving of angular speed stabilization with given quality criteria, we simulated a synthesized control system for various initial data. It is shown that the designed controller is capable of effectively countering the influence of wind disturbances in a wide range of deviations of the current speed from the frequency desired for a given target value. This work was supported by the RFBR grant No. 18-08-00473 a, dated 25/12/2018 on the topic: “Development and research of optimizing and controlling methods of energy conversion processes in the complex type power plants, including those converting a continuous flow of a medium”.

Three-dimensional particle-in-cell simulations show that the periodic solid-state structures irradiated by intense ($\sim 10^{19}$ W/cm${}^2$) laser pulses can generate collimated electron bunches with energies up to 30 MeV (and acceleration gradient of $11.5$ GeV/cm), if the microstructure period is equal to the laser wavelength. A one-dimensional model of piecewise acceleration in the microstructure is proposed and it is in a good agreement with the results of numerical simulations. It shows that the acceleration process for relativistic electrons can be theoretically infinite. In the simulations, the optimal target parameters (the width of the microstructure elements and the microstructure period) are determined. The explored parameters can be used for proof-of-principle experiments demonstrating an ultrahigh gradient acceleration by a number of identical and mutually coherent laser pulses [A. Pukhov et al., Eur. Phys. J. Spec. Top. 223, 1197 (2014)].

Development of the self-sustained quantum-electrodynamical (QED) cascade in a single strong laser pulse is studied analytically and numerically. The hydrodynamical approach is used to construct the analytical model of the cascade evolution, which includes the key features of the cascade observed in 3D QED particle-in-cell (QED-PIC) simulations such as the magnetic field predominance in the cascade plasma and laser energy absorption. The equations of the model are derived in the closed form and are solved numerically. Direct comparison between the solutions of the model equations and 3D QED-PIC simulations shows that our model is able to describe the complex nonlinear process of the cascade development qualitatively well. The various regimes of the interaction based on the intensity of the laser pulse are revealed in both the solutions of the model equations and the results of the QED-PIC simulations.

This article discusses the use of special software products for the design and simulation of the operation of electrical circuits, namely, the most commonly used programs Electronic Workbench and Multisim are compared, their advantages and disadvantages are determined. In the course of the experiments, on the basis of the above presented software systems, the operation of the electrical circuits of the devices of the amplitude diode detector and the low-frequency amplifier was simulated to identify the capabilities of the programs. In the course of the research, a visual table was compiled, thanks to which it is possible to compare the obtained parameters with the reference characteristics taken from real-life devices. The uptime was chosen as a control parameter, the article contains its calculation formula, and the final calculations are given in the table to better substantiate the capabilities of the software products under consideration. At the end of the article, conclusions are presented on the work done, thanks to which it is possible to determine the pros and cons of each of the programs under consideration.

A mathematical model of the working processes of a hybrid displacement piston power machine with profiled groove seal is proposed. Calculation of the working processes in the compressor section in the presence of a liquid film under the piston and a “pump” course in the pump section and a piston seal is presented. The working processes for a hybrid displacement piston power machine with a smooth groove seal and with a profiled groove seal is calculated and the influence of a profiled groove seal on the working processes and the dynamics of the layer of liquid over the piston is demonstrated.

Al2O3:Eu3+ nanophosphors were prepared by laser vaporization method in a flowing mixture of Ar/He and O2. Luminescence properties of Al2O3:Eu3+ nanophosphors are predominantly determined by Eu3+ ions red emission with inhomogeneously broadened bands in the region of 550-750 nm corresponding to 5D0 →7FJ transitions of Eu3+ (J = 0 - 4). Hypersensitive electric dipole transition 5D0 →7F2 dominates in the spectrum and is responsible for the red emission. The effect of crystallite size on luminescence properties of Al2O3:Eu3+ nanocrystals was observed. It was shown that the introduction of oxygen during the synthesis improves the luminescence performance. The obtained chromaticity coordinates and high absolute QY (~ 14%) indicate the possibility of using red nanophosphors based on Al2O3:Eu3+.

The article provides the analysis of factors affecting the reservoir properties (filtration and capacity) during repair works. It is revealed that the maintenance of filtration and capacitive reservoir properties is ensured by high-quality blocking and unblocking the reservoir, as well as by prevention of clay material swelling. Solution of these problems is possible through proper selection of the bridging agents (nature, type and fractional composition) used in the blocking composition, and various functional additives (salts, polymeric reagents and surfactants). Furthermore, the reasons of clay minerals swelling and various ways to prevent this process are analyzed. It is determined the peculiarities of clay minerals structure are essential for their properties, and in particular, their ability to swell.

The rationale is given for the improvement of the regulatory framework for the use of shaft sensors for the in-service condition monitoring of turbo generators and the development of control systems of shaft surfacing and misalignments of supports. A modern concept and a set of methods are proposed for the condition monitoring of the “shaft line–thrust bearing oil film–turbo generator supports” system elements based on the domestic COMPACS® technology. The system raw data are design, technology, installation, and operating parameters of the turbo generator as well as measured parameters of the absolute vibration of supports and mechanical quantities, relative displacements and relative vibration of the rotor teeth in accordance with GOST R 55263-2012. The precalculated shaft line assembly line in the cold state, the nominal parameters of rotor teeth positions on the dynamic equilibrium curve, the static and dynamic characteristics of the oil film of thrust bearings, and the shaft line stiffness matrix of unit support displacements have been introduced into the system. Using the COMPACS-T system, it is planned to measure positions and oscillations of rotor teeth, to count corresponding static and dynamic characteristics of the oil film, and the static and dynamic loads in the supports in real time. Using the obtained data, the system must determine the misalignments of supports and corrective alignments of rotors of coupling halves, voltages in rotor teeth, welds, and bolts of the coupling halves, and provide automatic conclusion if condition monitoring parameters correspond to standard values. A part of the methodological support for the proposed system is presented, including methods for determining static reactions of supports under load, the method for determining shaft line stiffness matrices, and the method for solving the inverse problem, i.e., the determination of the misalignments of the supports by measurements of rotor teeth relative positions in bearing housings. The procedure for calculating misalignments of turbo generator shaft line supports is set out.

Transverse betatron oscillations and the corresponding betatron emission are investigated for electrons in a strongly non-linear wake wave excited by a high-power laser pulse in a hollow-channel plasma. The expressions for the oscillation period and critical frequency in the synchrotron regime of betatron emission are derived. A two-stage scheme is considered, in which an electron bunch formed in a plasma possessing a certain set of parameters generates betatron emission in a plasma possessing another set of parameters. The emission spectrum at the second stage is calculated in the absence of bunch acceleration.

Introduction. There is a performance improvement problem of the existing wind-driven power plants (WPP). It is worthwhile investigating nonclassical types of the WPP to solve it. The most promising are the WPP which use special guide static elements to create vortex structures. The latter contributes to the increased aerodynamic efficiency of the WPP. Materials and Methods . Ansys Workbench and Ansys Fluent software packages are used to calculate the design aerodynamics of the wind turbines. Research Results. On the analysis of the particular publications, the viability of the vortex-type WPP studies in which the additional stator structures are used to increase their energy efficiency, is proved. The aerodynamics analysis of the WPP with “rotor-in-socket” assembly type is carried out using the continuum dynamics computational methods. An advanced WPP design is obtained by the aerodynamic optimization technique. Discussion and Conclusions. The obtained results show that the construction of the vortex-type turbine on the basis of the favourable interference concept of rotor and stator is promising. The specific form of WPP with a vertical axis of rotation, axisymmetric stator and socket of special forms is analyzed. The methods of the aerodynamic optimization of the described WPP design are considered. On the basis of this methodology, an advanced socket form and its assembly with the rotor which allows reaching an average calculated value of the favourable air moment that exceeds more than twofold the corresponding value for the initial geometry of the WPP, are obtained.

Introduction. The method and results of the aerodynamic research of the vertical axis wind power plants (WPP) with an axisymmetric stator are considered. The work objective is to show the application perspectiveness of vertical axis wind-power plants of the specified type for the national economy. Materials and Methods. The technique of virtual aerodynamic blasting and the corresponding design optimization at the specified criterion are used to perform the tasks. Within the framework of this technique, numerical aerodynamic analysis of a single rotor of the given type, and of the “rotor + socket” system before and after the optimization at the specified parameters of the freestream and rotor spinning is performed. When comparing the power of the obtained optimized WPP design with analogs, other things being equal, the aerodynamic similarity method is used. Research Results. Representative patterns of the aerodynamic flow around the investigated WPP type are obtained before and after the optimization. The distinctive distributions of the scalar and vector fields at the given parameters of the freestream and rotor spinning are studied. Dependent graphs are plotted against the linear freestream velocity for the projections of the rotor shaft moment (with WPP standard and optimized forms), as well as for the corresponding useful and side powers. A comparison of the power of the optimized WPP under consideration, and analogues, other factors being equal, is made. Discussion and Conclusions. The application perspectiveness of the vertical axis wind turbines with an axisymmetric stator designed to create useful interference with the rotor in order to increase useful shaft power is shown. Such wind power plants meet and exceed, at any rate upon the average, the corresponding classical vertical axis structures.

The possibilities of stabilizing the rotor speed of a vertical-axial wind power plant as, which can be included as an element in a complex power plant, which is a cyber-physical system (CPS), for additional and emergency power supply of surface robotic complexes are considered. For this purpose, it is proposed to use the method of stabilizing the angular velocity by controlling the position of the moving structural element of the installation in question. Received the corresponding law of regulation of the angular velocity of rotation of the rotor. The equations of the system for stabilizing the rotor rotation frequency with aperiodic wind disturbance are simulated. It is shown that the constructed regulator is able to effectively counter the influence of wind disturbances.

It is demonstrated by three-dimensional quantum electrodynamics --- particle-in-cell (QED-PIC) simulations that vacuum breakdown wave in the form of QED cascade front can propagate in an extremely intense plane electromagnetic wave. The result disproves the statement that the self-sustained cascading is not possible in a plane wave configuration. In the simulations the cascade initiates during laser-foil interaction in the light sail regime. As a result, a constantly growing electron-positron plasma cushion is formed between the foil and laser radiation. The cushion plasma efficiently absorbs the laser energy and decouples the radiation from the moving foil thereby interrupting the ion acceleration. The models describing propagation of the cascade front and electrodynamics of the cushion plasma are presented and their predictions are in a qualitative agreement with the results of numerical simulations., 12 pages, 8 figures; many changes in comparison with v1

In the laser --- electron beam head-on interaction electron energy can decrease due to radiation reaction, i.e. emission of photons. For 10--100~fs laser pulses and for the laser field strength up to the pair photoproduction threshold, it is shown that one can calculate the resulting electron and photon spectra as if the electron beam travels through a constant magnetic field. The strength of this constant field and the interaction time are found as functions of the laser field amplitude and duration. Using of constant field approximation can make a theoretical analysis of stochasticity of the radiation reaction much simpler in comparison with the case of alternating laser field, also, it allows one to get electron and photon spectra much cheaper numerically than by particle-in-cell simulations., Comment: I I Artemenko et al 2019 Plasma Phys. Control. Fusion 61 074003

The paper considers the relationship between the parameters of the vibration arising in rotating machinery during operation and the shaft speed. The goal of this paper is to determine the dependence of the vibration parameters on the shaft speed for solving applied engineering problems. To properly evaluate the technical condition of bearing assemblies, we should take into account the pattern of the rotating machinery vibration parameters-shaft speed relationship, which will allow creating new diagnostic features, the totality of which will ensure an increased reliability of diagnosis. We took the check for a correlation between the factor and resultative feature parameters as the correlation analysis method. A high pair linear correlation between the diagnostic features (acceleration, velocity, displacement) and the shaft speed was determined on the basis of the check for correlation between the vibration parameters and the shaft speed, and also the linear correlation coefficients can be used to solve th...

Studies of phenomena accompanying the interaction of superstrong electromagnetic fields with matter, in particular, the generation of an electron–positron plasma, acceleration of electrons and ions, and the generation of hard electromagnetic radiation are briefly reviewed. The possibility of using thin films to initiate quantum electrodynamics cascades in the field of converging laser pulses is analyzed. A model is developed to describe the formation of a plasma cavity behind a laser pulse in the transversely inhomogeneous plasma and the generation of betatron radiation by electrons accelerated in this cavity. Features of the generation of gamma radiation, as well as the effect of quantum electrodynamics effects on the acceleration of ions, at the interaction of intense laser pulses with solid targets are studied.

To visualize the physical processes that occur in the journal bearings of the shafting of power generating turbosets, a technique for preliminary calculation of a set of characteristics of the journal bearings in the domain of possible movements (DPM) of the rotor journals is proposed. The technique is based on interpolation of the oil film characteristics and is designed for use in real-time diagnostic system COMPACS®. According to this technique, for each journal bearing, the domain of possible movement of the shaft journal is computed, then triangulation of the area is performed, and the corresponding mesh is constructed. At each node of the mesh, all characteristics of the journal bearing required by the diagnostic system are calculated. Via shaft-position sensors, the system measures—in the online mode—the instantaneous location of the shaft journal in the bearing and determines the averaged static position of the journals (the pivoting vector). Afterwards, continuous interpolation in the triangulation domain is performed, which allows the real-time calculation of the static and dynamic forces that act on the rotor journal, the flow rate and the temperature of the lubricant, and power friction losses. Use of the proposed method on a running turboset enables diagnosing the technical condition of the shafting support system and promptly identifying the defects that determine the vibrational state and the overall reliability of the turboset. The authors report a number of examples of constructing the DPM and computing the basic static characteristics for elliptical journal bearings typical of large-scale power turbosets. To illustrate the interpolation method, the traditional approach to calculation of bearing properties is applied. This approach is based on a Reynolds two-dimensional isothermal equation that accounts for the mobility of the boundary of the oil film continuity.

The purpose of this article is to determine optimal conditions for rotor machinery operation in order to evaluate its condition using coherent function. The coherent function is an analogue of the correlation factor in frequency domain. The function reflects the linear relationship levels of harmonic components of parallel signals covered in the article. The conditions are considered optimal when the coherence function is expressed the most evidently. In other words, the coherent components are close to one.

The article presents the results of reciprocating compressors operation under the control of Vibration-Based Diagnostics monitoring systems, dwells upon the issues of usage of reciprocating compressors valves by various vendors and their influence on compressors’ vibroactivity. An adequate evaluation of vibroactivity of piston machines is provided by the Russian regulative database on vibration parameters. Main differences of Russian and global methods of reciprocating compressors health evaluation, particularly, used frequency range, are presented in the article. It is shown that the approach laid in Russian standards on reciprocating compressors vibration regulations, ensures true-to-life assessment of reciprocating compressors assemblies and details condition. The examples given in the article confirm that the criteria of reciprocating compressors repair correctness assessment should be the machinery health, including its vibroactivity, not just mindless usage of new components purchased from the global brands. Practical examples of operation and monitoring of reciprocating compressors show that Russian developments and products, particularly, scientific-methodological and standards base of Vibration-Based Diagnostics monitoring, reciprocating compressors monitoring systems, reciprocating compressors valves are highly competitive with foreign ones, and sometimes even superior to them in parameters and characteristics, which is a positive factor under the conditions of current economic situation and import substitution policy.

The surface laser-induced damage threshold (LIDT) of B a G a 4 S e 7 and B a G a 2 G e S e 6 nonlinear crystals was studied at 2091 nm. Both yellow and dark yellow phases of B a G a 4 S e 7 were investigated. The Ho:YAG laser generating nanosecond pulses at 2 kHz, 5 kHz, and 10 kHz was used as a radiation source. The R-on-1 procedure was applied to determine the 0% probability damage threshold. The LIDT of the dark yellow phase of B a G a 4 S e 7 without cleavage planes is very close to the B a G a 2 G e S e 6 LIDT and exceeds by ca. 30% the LIDT of the yellow phase of B a G a 4 S e 7 at 2 and 5 kHz.

Modern laser systems are able to generate short and intense laser pulses ionizing matter in the poorly explored barrier-suppression regime. Field ionization in this regime is studied analytically and numerically. For analytical studies, both the classical and the quantum approaches are used. Two approximations to solve the time-dependent Schr\"odinger equation are proposed: the free electron approximation, in which the atomic potential is neglected, and the motionless approximation, in which only the external field term is considered. In the motionless approximation, the ionization rate in extremely strong fields is derived. The approximations are applied to several model potentials and are verified using numeric simulations of the Schr\"odinger equation. A simple formula of the ionization rate both for the tunnel and the barrier-suppression regimes is proposed. The formula can be used, for example, in particle-in-cell codes for simulations of the interaction of extremely intense laser fields with matter.

The paper deals with the challenges of the machinery vibroacoustic signal modeling. The purpose of this paper is to form a phenomenological model for the structure of vibroacoustic oscillations and signals appeared in case of malfunctions and defects. It presents particular structural models for vibroacoustic signals of some reciprocating machine malfunctions. Mathematical description of the vibroacoustic signal reveals the informative parameters of the malfunction diagnostic signs. The model enables us to define in detail the informative vibroacoustic signal parameters. The model also allows us to select the diagnostic signs of the given malfunctions and defects in certain machine parts and components. At the same time, it is considered that the signal is received in certain points on the machine taking into account the excitation sources, conditioning channel and propagation of the vibroacoustic oscillations. The model has been constructed considering the presence and interaction of the three main sources of excitation of the asset vibroacoustic oscillations, which are identified by the types of excited oscillations. It is assumed that there are damped natural, undamped induced, random broadband and narrowband vibrations. The parameters of the vibroacoustic signal structural model also take into account the properties of converting the vibroacoustic oscillation to the vibroacoustic signal by means of a piezoelectric sensor. The model shows that the vibroacoustic signal has not only the components from each source, but their mutually modulated components. We developed partial models for mechanisms of structuring the vibroacoustic signal appeared in case of malfunctions and defects in rotating parts and couplings, machine shaft and drive shaft misalignment, increased clearances and other defects and failures of the rotating and reciprocating parts and components. The proposed phenomenological structural models of the vibroacoustic signals appeared in case of malfunctions of reciprocating machines show that for the diagnostic purposes it is necessary to analyze vibroacoustic signals either in the time domain according to the cyclogram of the reciprocating machine operation or in the envelope spectrum at characteristic frequencies or the noise component. In the event of defects and malfunctions in the centrifugal rotating parts and components, there are excited the vibroacoustic signals, which are advisable to analyze in the direct spectrum or in the spectrum of the noise component envelope. The proposed models enable us to select and form scientifically grounded systems of the machine failure diagnostic signs.

With the emergence of the CAN (Coherent Amplification Network) laser technology, a new scheme for direct particle acceleration in periodic plasma structures has been proposed. By using our full electromagnetic relativistic particle-in-cell (PIC) simulation code equipped with ionisation module, we simulate the laser fields dynamics in the periodic structures of different materials. We study how the dynamic ionization influences the field structure.

A formula for the ionization rate in extremely intense electromagnetic field is proposed and used for numerical study of QED (quantum-electrodynamical) cascades in noble gases in the field of two counter-propagating laser pulses. It is shown that the number of the electron-positron pairs produced in the cascade increases with the atomic number of the gas where the gas density is taken to be reversely proportional to the atomic number. While the most electrons produced in the laser pulse front are expelled by the ponderomotive force from region occupied by the strong laser field there is a small portion of the electrons staying in the laser field for a long time until the instance when the laser field is strong enough for cascading. This mechanism is relevant for all gases. For high-$Z$ gases there is an additional mechanism associated with the ionization of inner shells at the the instance when the laser field is strong enough for cascading. The role of both mechanisms for cascade initiation is revealed.

The paper reviews the publications on low-frequency vibration in power plants. It is noted that the regulatory literature poorly defines the issues of rating and diagnosing self-excited and subharmonic vibrations. Analysis of the literature and ISO standards shows that despite the considerable experience gained by specialists in low-frequency vibration control, a number of issues, such as subharmonic resonances and nonlinear properties of complicated multi-seated rotor systems supported by journal bearings, are still understudied and require further calculations and experiments. The paper presents some results obtained in experiments of low-frequency vibrations for a rotor supported by journal bearings and having a residual deflection. The experimental results confirmed the classical hysteresis of self-excited vibrations – the difference in the boundaries of self-excited vibrations during ascent and descent is about 4 Hz. The arears of appearance and disappearance of subharmonic vibrations are shown using the spectral characteristics of vibrations and cascade spectra.

Interaction of laser plulses with intensities up to 1025 W/cm2 with overdense plasma targets is investigated via three-dimensional particle-in-cell simulations. At these intensities, radiation of electrons in the laser field becomes important. Electrons transfer a significant fraction of their energy to γ-photons and obtain strong feedbacks due to radiation reaction (RR) force. The RR effect on the distribution of laser energies among three main species: electrons, ions and photons is studied. The RR and electron-positron pair creation are implemented by a QED model. As the laser intensity inreases, the ratio of laser energy coupled to electrons drops while the one for γ-photons reaches up to 35%. Two distinctive plasma density regimes of the high-density carbon target and low-density solid hydrogen target are identified from the laser energy partitions and angular distributions of photons. The power-laws of absorption efficiency versus laser intensity and the transition of photon divergence are revealed. These show enhanced generation of γ-photon beams with improved collimation in the relativistically transparent regime. A new effect of transverse trapping of electrons inside the laser field caused by the RR force is observed: electrons can be unexpectedly confined by the intense laser field when the RR force is comparable to the Lorentz force. Finally, the RR effect and different regions of photon emission in laser-foil interactions are clarified.

Within European Partitioning & Transmutation research programs, infrastructures specifically dedicated to the study of funda- mental reactor physics and engineering parameters of future fast-neutron-based reactors are very important, being some of these features not available in present zero-power prototypes. This presentation will illustrate the conceptual design of an ADS with high safety standards, but ample flexibility for measurements. The design assumes as base option the 70 MeV, 0.75 mA proton cyclotron facility planned to be constructed at the INFN National Laboratory in Legnaro, Italy and a Beryllium target, with Helium gas as core coolant. Safety is guaranteed by limiting the thermal power to 200 kW, with a neutron multiplication coefficient around 0.94, loading the core with fuel containing Uranium enriched at 20% and a solid-lead diffuser. The small decay heat can be passively removed by thermal radiation from the vessel. Such a system could be used to study, among others, some specific aspects of neutron diffusion in lead, beam-core coupling, target cooling and could serve as a training facility.

New type of highly absorbing core-shell AZO/Au (aluminum doped zinc oxide/gold) and GZO/Au (gallium doped zinc oxide/gold) nanoparticles have been proposed for hyperthermia of malignant cells purposes. Comparative studies of pulsed laser hyperthermia were performed for Au nanoshells with AZO core and traditional SiO2 (quartz) core. We show that under the same conditions, the hyperthermia efficiency in the case of AZO increases by several orders of magnitude compared to SiO2 due to low heat capacity of AZO. Similar results have been obtained for GZO core which has same heat capacity. Calculations for pico-, nano- and sub-microsecond pulses demonstrate that reduced pulse duration results in strong spatial localization of overheated areas around nanoparticles, which ensures the absence of negative effects to the normal tissue. Moreover, we propose new alternative way for the optimization of hyperthermia efficiency: instead of maximizing the absorption of nanoparticles, we enhance the thermal damage effect on the membrane of malignant cell. This strategy allows to find the parameters of nanoparticle and the incident radiation for the most effective therapy.

We investigated the laser-induced damage threshold of two barium chalcogenides crystals, BaGa4Se7 and BaGa2GeSe6, at 1.053 μm radiation with a pulse duration of 7–10 ns at different pulse repetition rates, namely, 100 Hz, 500 Hz, and 1 kHz. The R-on-1 procedure was applied to determine the 0% probability damage threshold. Both crystals have close values of surface damage threshold at 0.1 kHz, 299 MW/cm2 (2.28 J/cm2) for BaGa2GeSe6, and 319 MW/cm2 (2.30 J/cm2) for BaGa4Se7.

We present a complex of mathematical models that formalize gas recovery and processing. Optimization problems for gas recovery and gas condensate processing are stated and corresponding solution algorithms are suggested. These mathematical models provide a foundation of interactive decision support systems used in gas recovery and gas condensate processing.

The paper is devoted to the principles of magneto-inertial fusion and laser-plasma methods of generation of a Megagauss field during spherical implosion of a magnetized target. A model based on a magnetic confinement system, namely, a cusp configuration with inertial compression of the target by a laser driver, is developed. The dynamics of plasma in a cusp compressed under the effect of laser beams is precalculated. Analytical and numerical estimates of the particle number and magnetic field intensity during magneto-inertial plasma compression are obtained. The problems of irradiation of a spherically closed volume by a high-energy laser pulse are discussed.