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В статье представлен принцип тепловой защиты контактной сети и обоснована возможность практической реализации этого принципа для рельсового электротранспорта в горнодобывающей промышленности. Описан алгоритм реализации современной цифровой защиты контактной сети как одной из функций работы контроллера. Предложена математическая модель тепловой защиты, вытекающая из решения уравнения теплового баланса. Модель учитывает коэффициент топологии электрической сети, а также коэффициент расхода токоведущего сердечника кабеля, определяющий снижение проводящего сечения от контактной эрозии и роста оксидных пленок. Вводятся поправки на потоки воздуха при получении данных с внешнего анемометра, через протокол телемеханики. Тестирование математической модели проводилось путем написания программы реальной тепловой защиты на языке программирования С для контроллера присоединения, в основе схемотехники которого микроконтроллер STM32F407IGT6 для микроконтроллерного блока. Проверочные испытания проводились на серийном контроллере присоединения в 2020 г. Приведены графики сравнения расчетных и фактических значений температур, при различном коэффициенте расхода токоведущей жилы кабеля постоянного тока. Для получения данных использовались протоколы телемеханики МЭК 60870-104 и Modbus TCP, ПЛК Segnetics SMH4.

Two nonlinear processes, namely, two-photon absorption (TPA) and stimulated Raman scattering (SRS) in Na2W2O7 crystal at a wavelength of 523.5 nm, are studied theoretically and experimentally depending on the polarization of the incident picosecond laser radiation. It was found that, due to the anisotropy of the band gap structure, the TPA coefficient at 523.5 nm strongly depends on the pump radiation polarization. For radiation along the c axis with polarization parallel to the a axis, the TPA coefficient was measured to be 1.28 cm GW−1, and no SRS process was registered. However, for polarization parallel to the b axis, no measurable TPA was detected and SRS with a gain of 6.5 cm GW−1 was observed. To the best of our knowledge, this is the first demonstration of the competition of two nonlinear processes in one crystal depending on its orientation.

Electro-optically Q-switched side-pumped diode-pumped KTP/YAG:Nd3+ nanosecond laser system with an intracavity collinear optical parametric oscillation was proposed as a pump source for Cr2+:ZnSe laser. Energy parameters of Cr2+:ZnSe laser were investigated with respect to the wavelength of the pump laser. Under optimal conditions, pumping with laser pulses with an energy of 10.5 mJ and a duration of 7.2 ns at a wavelength of 1950 nm allowed to obtain 3.2 ns pulses at a wavelength of 2494 nm with slope optical-to-optical conversion efficiency of 5.5%.

Two-photon absorption (TPA) in La0.05Gd0.95VO4 crystal under irradiation with picosecond laser pulses with the duration of 25 ps at the wavelength of 523.5 nm has been investigated. The TPA coefficient was measured to be 0.074 cm/GW. We found that the two-photon inter-band excitation led to the creation of optical centers, which were characterized by a wide absorption band in the visible spectral region. The decay of the induced absorption is characterized by two temporal stages. The first rapid stage has the decay time of about 70 μs. However, the slow stage is characterized by a decay time ranging from 270 to 520 ms depending on the initial concentration of the induced optical centers. Induced absorption should be taken into account when developing vanadate lasers with intra-cavity second harmonic converters.

The article discusses a device for diagnosing the electrocorrosive state of hollow reinforced concrete supports of the contact network and power lines. The operation of the device is based on the use of a visual method for monitoring electro-corrosive defects. A design of a video endoscope is proposed that provides an improvement in image quality by eliminating fluctuations in the position of a flexible optical probe during its vertical movement, an increase in the level of automation of the diagnostic process with registration of the coordinates of defects and documentary evidence in the form of a replenished database of images of the diagnostic object — the inner surface of hollow reinforced concrete supports from the surface soil to their base.

This article presents the results of the mathematical simulation of processes in air ICP/RF plasma torch for high-power applications. This investigation is a part of a wide research focused on estimation and reduction of nonuniformity of plasma temperature and velocity fields. The results showed the effect of dissipated power and gas flow rate on the plasma temperature and axial velocity distributions.

In this Letter, a mixed

Crystalline materials that exhibit strong nonlinear optical properties and can be used as a host matrix for laser ions are of great interest for developing of new polyfunctional laser materials. Calcium orthovanadate, Ca 3 (VO 4 ) 2 (CVO) is known as a laser host material [1] . CVO has a noncentrosymmetric structure and can be used for second harmonic generation [2] . In addition, CVO has been found to have attractive Raman properties. Single-pass Raman conversion of 15-ps laser pulses at the wavelength of 1.06 μm in CVO was observed with threshold pump energy of only 2 times higher than that in the most efficient BaWO 4 crystal [3] . Recently efficient 30-times pulse shortening up to 1.2 ps was demonstrated in CVO Raman laser at combined Stokes shift under synchronous pumping by trains of 36-ps pulses from mode-locked Nd 3+ :GdVO 4 laser operating at 1.06 μm [4] . In spite of good transparency of CVO in visible all the above experiments were made in near-IR spectral region.

Multiwavelength, near-IR (1000-1400 nm), high-repetition-rate, ultrashort laser pulses converted by cascaded stimulated Raman scattering (SRS) have many potential applications connected with multiphoton interactions of coherent radiation with matter. Utilization of mixed Raman-active crystals can make it possible not only to enrich the generated SRS radiation spectra, but also to improve other the radiation characteristics, in particular, to ensure shortening of the laser pulses. One of the candidates is a Pb(MoO 4 ) x (WO 4 ) 1 – x mixed crystal having two-mode behaviour (corresponding to the molybdate and tungstate anionic groups) for the high-frequency (ν 1 ) stretching vibrations of the anionic groups, but one-mode behaviour for the low-frequency (ν 2 ) bending vibrations of the anionic groups [1] as it shows Fig. 1 (a) for Pb(MoO 4 ) 0.5 (WO 4 ) 0.5 . Single-pass picosecond SRS in Pb(MoO 4 ) 0.5 (WO 4 ) 0.5 has been earlier realized and shown laser frequency conversion only on the two-mode ν 1 (MoO 4 ) and ν 1 (WO 4 ) stretching vibrations [2] . In the present work we demonstrate the synchronously pumped Pb(MoO 4 ) 0.5 (WO 4 ) 0.5 Raman laser operation with combined frequency shifts not only on the two-mode stretching (ν 1 ) Raman frequencies, but also on the one-mode bending ν 2 (MoO 4 + WO 4 ) broadened (Δν 2 = 10 cm –1 ) Raman line, allowing to shorten the (ν 1 + ν 2 )-shifted SRS pulses down to 1/(π c Δν ) ≈ 2 1 ps.

This article describes a study of legal texts (in English, French, and Russian) to confirm J. Greenberg’s linguistic universals № 11 and 14. The linguistic universal № 14 refers to the ordering of subject, object, and verb in a conditional clause. Anna Wierzbicka refers the predicate “if” (which forms the conditional) to the number of semantic primitives. The linguistic universal № 11 asserts in declarative sentences with nominal subject and object, the predominant dominant order has the subject followed by the object. This study revises some of the most important provisions set forth by J. Greenberg for the languages with SVO word order. Some languages use relatively restrictive word order, often relying on the order of constituents to convey important grammatical information. Others — often those that convey grammatical information through inflection — allow more flexibility, which can be used to encode pragmatic information such as topicalisation or focus. It is hypothesized that, due to genre-stylistic and historical-cultural specificity, the texts of laws in French and English do not have a dominant word order. Texts of laws in Russian for the same reasons also do not have a dominant SVO word order.

A high-frequency/high-magnetic field (94 GHz/3.3 T) electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) study of monocrystalline nanodiamonds (ND) is carried out. Influence of the hydrogen and fluorine modification of the ND surface on EPR and ENDOR signals from the superficial and bulk paramagnetic centers is observed. The effect shows that the ND bulk paramagnetic centers could serve as the intrinsic probe of ND surface modification despite deep localization, shielding from the environment and two-layered surface of the diamond nanoparticle.

The spectral parameters of neodymium ions in anisotropic YLiF4, SrMoO4, PbMoO4, CaMoO4, SrWO4, and BaWO4 crystals with a scheelite structure are experimentally studied in the region of 1 μm. The luminescence spectra of neodymium ions at the 4F3/2 → 4I11/2 transition in these crystals exhibit pronounced polarisation dependences. It is shown that, using different orientations of the active laser element and separating a particular radiation polarisation, one can control the spectral dependence of the active medium gain, switch the laser wavelength, and create dual-wavelength lasers. A dual-wavelength Nd3+ : YLiF4 laser emitting at λ = 1047 and 1053 nm with identical linear polarisations and good temporal and spatial matching is demonstrated.

The GAMMA-400 space project is one of the new generation of space observatories designed to search for signs of dark matter in the cosmic gamma emission, and to measure the characteristics of diffuse gamma-ray emission and gamma-rays from the Sun during periods of solar activity; gamma-ray bursts; extended and point gamma-ray sources; and electron, positron, and cosmic-ray nuclei fluxes with energies in the TeV ranges. The GAMMA-400 γ-ray telescope constitutes the core of the scientific instrumentation. The nature of the intended experiments imposes stringent requirements on the gamma telescope’s system of trigger signal formation, now being developed using the state-of-the-art logic devices and fast data links. The design concept of the system is discussed, along with the chosen engineering solutions and some experimental results obtained during the operation of the system prototype using a positron beam with energies of 100–300 MeV from the PAKHRA S-25R synchrotron at the Lebedev Physical Institute.

We report characteristics of a synchronously pumped picosecond all-solid-state Raman laser based on a SrMoO4 crystal at both 887 cm−1 stretching and 327 cm−1 bending anionic group symmetric vibrations. Lasing is obtained at not only the first Stokes wavelength of 1173 nm having a usual Raman shift of 887 cm−1 from the 1063-nm pumping, but also at the additional Stokes wavelength of 1220 nm with the combined 887 cm−1 + 327 cm−1 Raman shift. The strongest 26-fold shortening of the 1220-nm Raman radiation pulse down to 1.4 ps is achieved. This is close to very short dephasing time (1 ps) of the 327 cm−1 vibrational Raman line of the SrMoO4 crystal due to self-mode-locking of the 1220-nm cascaded Stokes field under intracavity pumping by the 1173-nm fundamental Stokes field.

Electron paramagnetic resonance (EPR) study of the impurity Gd3+ ions in the multi-site SrY2O4 crystal isostructural to the magnetically-frustrated SrGd2O4 compound is reported. Analysis of the angular dependences of the EPR spectra at room temperature allowed us to establish the spin-level energy patterns in the ground states of the Gd3+ ions at the Y(1) and Y(2) sites. Parameters of the spin-Hamiltonian in the frames related to the crystal axes and to the principal center axes are determined.

The paper proposes a procedure of experimental data processing by the thin wall method for the diagnostics of stationary gas-flows. The procedure is based on solving an inverse convective heat transfer problem. It does not use smoothing and numerical differentiation of experimental data, and is resistant to measurement errors. Sensitivity coefficients are analyzed to find the most informative times for the determination of convective heat transfer parameters with the least influence of the measurement error. The numerical examples given show the effectiveness of the calculation procedure for the heat transfer coefficient and the gas-flow temperature determined from discrete measurements of the sensor temperature.

The article is focused on the development of a single-circuit vacuum tube generator 1 MW, 0.44 MHz with self-excitation which can be used for industrial applications, for example as a power source for generation of a radio-frequency induction plasma of high-enthalpy gases (air, nitrogen, etc.). A generator model in soft Matlab Simulink has been created. The vacuum tube GU-98A which produced by industry was chosen as the main element of the generator. The nonlinear characteristics of the vacuum tube (namely, the dependences of the anode current and the grid current on the anode and grid voltages) were approximated by analytical functions. The generator load which is an inductor with plasma was represented in the generator circuit as an active-inductive element with constant parameters. The article presents the parameters of effective operating modes of the tube generator and recommendations for the selection of its main elements.

A procedure based on the solution of the inverse problem of heat conduction is presented for the calculation of the heat-transfer coefficient and the temperature of a steady state gas flow via the measurement of the temperature of a material of a heat-insulated plate without numerical differentiation or the smoothing of experimental data. The sensitivity of the solution to a change in the convective heat-transfer parameters is analyzed. The measurement times at which the experimental data contain the maximal information on the sought parameters and the minimal influence of measurement error on their determination were determined. The application of the technique does not require the selection of a material-heating regime and makes it possible to increase the accuracy of the determination of the convective heat-transfer parameters

For the first time to our knowledge, the operation of a synchronously pumped ultrafast Raman laser that uses a PbMoO

Experiments on lasing in slurry-like active media based on dense mixtures of laser crystal or glass microparticles with immersion liquids are reported.

Two-photon absorption in disodium ditungstate crystal under irradiation with picoseconds laser pulses with the wavelength of 523.5 nm is investigated. Due to high value of the two-photon absorption coefficient this process should be considered in Raman laser design for the visible spectral region.

The problem of spatial flow around a hypersonic flying vehicle is considered for trajectories with different attack angles for flight through air with chemical equilibrium. The conjugate problem statement gives solutions for gas state in the boundary layer, thermal regime of streamlined body (made of different composites), and the rate of mass loss for heat protecting material. Physical processes in the condensed phase of carbon-containing coatings have complex nature: processes of heating, pyrolysis, heterogeneous oxidation, and sublimation. These processes result in protective material destruction. It was shown that using different materials for passive protection can be beneficial in reduction of the surface temperature, characteristics of thermochemical degradation, and this allows a control over heat and mass transfer for a flying body.

The problem of unsteady coupled heat and mass transfer in the course of motion of a spherically blunted conical body fabricated with the use of thermal protection materials is considered. Numerical integration is applied to study the characteristics of heat and mass transfer at constant stagnation parameters (Mach number 6, altitude 15 km, and flight time 600 s), which impose severe constraints on the choice of materials for thermal protection. It is demonstrated that the use of advanced ceramic materials ensures an admissible temperature regime and maintaining the initial geometry of the body, including its motion at an angle of attack.

The future space-based γ-ray telescope GAMMA-400 will be installed on the Navigator platform of the Russian astrophysical observatory. A highly elliptical orbit will allow prolonged (~100 days) continuous observations of many regions of the celestial sphere for 7–10 years. GAMMA-400 will measure fluxes of γ‑ray emission in the energy range of ~20 MeV to several TeV and electrons + positrons to ~20 TeV. The γ-ray telescope will have excellent separation of γ-ray emissions against the background of cosmic rays and electrons + positrons from protons, along with unprecedented angular (~0.01° at Eγ = 100 GeV) and energy (~1% at Eγ = 100 GeV) resolutions 5–10 times better than for the Fermi-LAT and ground-based γ-ray telescopes. GAMMA-400 observations will provide fundamentally new data on discrete sources and spectra of γ-ray emissions and electrons + positrons.

The GAMMA-400 γ-ray telescope installed at the Russian space observatory is intended for precision measurements in the energy range of 20 MeV–1000 GeV of γ-ray emission (with the angular and energy resolutions several times better than that of current γ-ray telescopes) from discrete sources; measurement of the energy spectra of Galactic and extragalactic diffuse γ-ray emission; studies of γ-ray emission from the active Sun; and measurements of fluxes of γ-ray emission and electron–positron cosmicray component, which are probably associated with the annihilation or decay of dark-matter particles.

In this Letter, a mixed P b ( M o O 4 ) 0.2 ( W O 4 ) 0.8 as a new, to the best of our knowledge, active medium with optimized content for a synchronously pumped multiwavelength Raman laser with a combined frequency shift is presented. The unique structure of this crystal resulted in oscillations at 12 closely spaced output wavelengths in a spectral range from 1128 to 1360 nm. The strongest pulse shortening in comparison with nominally pure scheelite-like crystals has been achieved.

At present, we can observe progress in physics of crystalline Raman lasers leading to efficient nonlinear frequency conversion at transient regime for generation of ultra-short pulses of stimulated Raman scattering (SRS) radiation with picosecond duration and shorter [1,2]. Recently the problem of a femtosecond crystalline Raman laser with femtosecond pumping has been solved [1] using an efficient SRS in a Raman-active crystal (CVD-diamond) under synchronous pumping by repetitive femtosecond laser pulses in an external cavity with a round-trip time equal to the pump pulse repetition period. However, a challenge of femtosecond SRS pulse generation in crystals under pumping by picosecond lasers which is more simple, inexpensive, and prevalent in comparison with the unique femtosecond laser systems remained unsolved.

Lasers operating in mid-infrared spectral region specifically with 3 μm wavelength attract a lot of attention due to their various applications in atmospheric monitoring, medical surgery, remote sensing and scientific research. Such laser can be used as an efficient and high-quality radiation source for optical parametric oscillators and converters to longer IR wavelengths.

New possibilities to use the zircon-type YVO4 and GdVO4 Raman-active crystals for extreme SRS-radiation pulse shortening higher than 30 times down to the inverse value of the vibrational Raman line width in a synchronouslypumped crystalline Raman laser with combined long (ν1) and short (ν2) shift Raman conversion have been found. It is caused by strong broadening of the short-shift bending vibration ν2 line in the spontaneous Raman spectrum of these crystals. We report characteristics of all-solid-state extracavity Raman lasers based on the 16-mm long a-cut YVO4 (ν1 = 889 cm–1, ν2 = 376 cm–1) and GdVO4 (ν1 = 882 cm–1, ν2 = 382 cm–1) crystals under synchronous pumping by a 1063-nm 35-picosecond Nd:GdVO4 laser. Lasing was obtained in the YVO4 (GdVO4) Raman laser at not only the ν1- shifted first Stokes wavelength of 1173 nm (1174 nm), but also at the (ν1 + ν2)-shifted Stokes wavelength of 1228 nm (1228 nm) with slope efficiency of 5.8 % (5.0 %) and output pulse energy up to 11 nJ (10 nJ) at 1228 nm. At 50 μm positive detuning of the external cavity length the strongest 30-fold and 42-fold shortening of the (ν1+ν2)-shifted Raman radiation pulse down to 1.2 ps and 850 fs in the YVO4 and GdVO4 crystals, respectively, has been achieved. These values are close to the inverse values of the ν2 line widths of 11 cm–1 and 24 cm–1, respectively.

In this paper, the characteristics of synchronously pumped picosecond Raman laser based on the 36 mm long SrWO4 crystal at the shifts of ν1 = 921 cm–1 and ν2 = 336 cm–1 under 36-ps extracavity pumping are presented. The first Stokes at the wavelength of 1178 nm, corresponding to the Raman shift of ν1, with the slope efficiency of 45.1%, output energy of up to 40 nJ, and pulse duration of 33 ps, respectively, was achieved for the output coupler reflectivity of 89%. In the case of setup with the higher cavity Q-factor at 1178 nm, we obtained not only usual ν1- shifted Raman radiation at 1178 nm, but also the unusual line at the wavelength of 1227 nm (ν1 + ν2). This additional line was achieved with the slope efficiency of 18.1 % and the output energy of 15 nJ with the output coupler reflectivity of 96.5% at 1227 nm. Strong pulse shortening from 36 ps down to 1.4 ps at the wavelength of 1227 nm was observed at +50 μm positive detuning of the external cavity length. This value is close to the inverse value of the ν2 line.

Comparative investigation of characteristics of spontaneous and stimulated Raman scattering (SRS) in different alkali-earth tungstate and molybdate crystals at both high and low frequency anionic group vibrations is presented. It has been found that, among these crystals, the SrMoO4 and SrWO4 crystals are the most perspective for SRS generation on both stretching and bending modes of internal anionic group vibrations with the strongest SRS pulse shortening under synchronous laser pumping because of not only highly intense stretching mode Raman line for efficient primary extra cavity long-shifted SRS conversion but also the widest bending mode Raman line for the strongest SRS pulse shortening down to the inverse width of the widest Raman line (~1 ps) at secondary intracavity short-shifted SRS conversion. The strongest 26-fold pump pulse shortening down to 1.4 ps at the Stokes component with the combined Raman shift in the synchronously pumped extra cavity SrMoO4 and SrWO4 Raman lasers has been demonstrated. It was found that synchronously pumped cascade SRS with combined Raman shift is more efficient in the SrWO4 crystal because the bending mode Raman line is more intense relative to the stretching mode Raman line than that in SrMoO4.

The GAMMA-400 currently developing space-based gamma-ray telescope is designed to measure the gamma-ray fluxes in the energy range from ∼20 MeV to several TeV in the highly elliptic orbit (without shadowing the telescope by the Earth) continuously for a long time. The physical characteristics of the GAMMA-400 gamma-ray telescope, especially the angular and energy resolutions (at 100-GeV gamma rays they are ∼0.01° and ∼1%, respectively), allow us to consider this space-based experiment as the next step in the development of extraterrestrial high-energy gamma-ray astronomy. In this paper, a method to improve the reconstruction accuracy of incident angle for low-energy gamma rays in the GAMMA-400 space-based gamma-ray telescope is presented. The special analysis of topology of pair-conversion events in thin layers of converter was performed. Applying the energy dependence of multiple Coulomb scattering for pair components, it is possible to estimate the energies for each particle, and to use these energies as weight in the angle reconstruction procedure. To identify the unique track in each projection the imaginary curvature method is applied. It allows us to obtain significantly better angular resolution in comparison with other methods applied in current space-based experiments. When using this method for 50-MeV gamma rays the GAMMA-400 gamma-ray telescope angular resolution is about 4°.

A useful parametrization of the energy spectrum of galactic cosmic rays (GCR) near Earth is offered by the so-called force-field model which describes the shape of the entire spectrum with a single parameter, the modulation potential. While the usefulness of the force-field approximation has been confirmed for regular periods of solar modulation, it was not tested explicitly for disturbed periods, when \GCR\ are locally modulated by strong interplanetary transients. Here we use direct measurements of protons and α -particles performed by the \PAMELA\ space-borne instrument during December 2006, including a major Forbush decrease, in order to directly test the validity of the force-field parameterization. We conclude that (1) The force-field parametrization works very well in describing the energy spectra of protons and α -particles directly measured by \PAMELA\ outside the Earths atmosphere; (2) The energy spectrum of \GCR\ can be well parameterized by the force-field model also during a strong Forbush decrease; (3) The estimate of the \GCR\ modulation parameter, obtained using data from the world-wide neutron monitor network, is in good agreement with the spectra directly measured by \PAMELA\ during the studied interval. This result is obtained on the basis of a single event analysis, more events need to be analyzed.

The results of measuring albedo deuteron fluxes in the vicinity of the Earth are presented. The data were obtained in the PAMELA experiment conducted aboard the Resurs DK-1 artificial Earth satellite. High-precision detectors of the instrument setup allow us to identify albedo deuterons and measure their spectra in the energy interval from 70 to 600 MeV/nucleon at altitudes of 350-600 km for different geomagnetic latitudes.