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The paper discusses the results of the development of a deep learning-based algorithm of the inverse Sumudu transform applied to the problem of on-ground non-stationary electromagnetic sounding. The Sumudu transform has potential for solving forward geoelectric problems in three-dimensional earth models because, unlike using the Laplace or Fourier transform, the Sumudu image of a real function is also a real function. Thus, there is no need to use complex numbers in subsequent calculations, which reduces computational costs and memory requirements in case of successful determination of the Sumudu image of the function. The disadvantages of the approach include the absence of an explicit method for calculating the inverse transform. The inversion can be done by solving the corresponding Fredholm integral equation of the first kind, but this is a poorly conditioned task leading to high requirements for the accuracy of the Sumudu image. The use of modern machine learning techniques can provide a method that is more robust to noise in the input data. This paper describes the process of creating a training dataset and developing a neural network algorithm; we evaluate the accuracy and performance of the obtained solution. The proposed method can contribute to the development of new approaches to physical processes modeling as well as to analysis, processing and interpretation of measured geophysical data.

The development of laser technologies leads to high requirements for lasers being developed which generate narrow-band radiation with different wavelengths. In view of this, the importance of wavelength-tunable diode and vibronic lasers with broadband amplification circuits increases. The possibility of generating highly coherent radiation in a solid-state alexandrite laser using an original composite resonator which includes an additional external dispersive resonator has been demonstrated. The results of experimental studies of conditions for the generation of narrow-band (less than 20 pm) radiation in such a resonator with the possibility of smooth tuning of the lasing wavelength in the spectral range 740-780 nm are presented. Narrow-band lasing in an alexandrite laser with a radiation energy of 30 mJ and a pulse duration of 35 ns was demonstrated. The created compact narrow-band alexandrite laser can be an effective alternative to parametric oscillators (OPO) and Ti:Sapphire lasers in lidar systems operating in the spectral range 700-850 nm.

Laser radiation in the yellow wavelength range is widely used in ophthalmology due to its effectiveness and unique properties. Commercial medical laser systems existing today have low pulse power and other disadvantages. A yellow neon laser with a wavelength of 585.3 nm can be proposed as an alternative. This paper describes the experimental study of a neon laser pumped by a pulsed inductive longitudinal discharge. A Ne-H₂ gas mixture with various ratios is used as the active medium. The shape and duration of the lasing pulses strongly depend on the ratio Ne : H₂, providing both single and double pulses with a total duration of 30 to 100 ns (FWHM). The generation energy reaches 20 mJ, which corresponds to a pulse power of 200 W. The cross-section of the laser beam has a shape close to a circle, with a divergence less than 2 mrad. Further, with implementing a pulse-periodic operating mode of an induction neon laser with a pulse repetition rate of up to 100 Hz, it can be used for various applications, including in medicine.

Electric discharge nitrogen lasers remain popular sources of UV radiation and find many scientific and practical applications. Currently, some of the requirements for commercial nitrogen lasers are small overall dimensions, high pulse-to-pulse stability, and extended service life. In this paper, a nitrogen laser excited by a pulsed longitudinal inductive-electric discharge is suggested as a source which satisfies such criteria. As a result of the experimental studies, lasing at wavelengths l₁ = 337.1 and l₂ = 357.7 nm was obtained. The generation energy reached 0.67 mJ with a pulse duration of 20 ns (FWHM) and a nitrogen pressure of 7...8 Torr. Pumping nitrogen only with a longitudinal discharge in an experimental setup with similar parameters led to a decrease in the lasing energy to 0.4 mJ (with the same pulse duration of 20 ns) at a nitrogen pressure of no higher than 5 Torr. Nitrogen lasers with these radiation parameters can be used to treat ophthalmic diseases and tuberculosis.

In the course of technological development of society, the problem of violation of the ecological state of the environment inevitably arises, in particular in water reservoirs. In order to proper respond to the changes in the concentrations of various pollutants in natural water reservoirs, it is necessary to develop an express remote method. The creation of such a method is possible on the basis of Raman spectroscopy. However, during its development, a large number of various difficulties arise, in particular regarding the method of preprocessing the obtained data. The paper presents the results of using machine learning methods to develop a remote method for determining the type and concentration of dissolved ions in aqueous media from Raman spectra. The use of artificial neural networks made it possible to identify and simultaneously determine the concentration of each of the eight ions (Zn²⁺, Cu²⁺, Li⁺, Fe³⁺, Ni²⁺, NH₄⁺, SO₄², and NO₃^-) in a multicomponent aqueous mixture with errors, which meet the needs of environmental monitoring of natural and waste waters. A significant influence of the method of preprocessing Raman spectra on the result of solving the inverse spectroscopic problem is discovered. The results can be used for solution of the multiparameter inverse problem of qualitative and quantitative determination of ions in water.

The glow of diffuse plasma jets (DPJ) is studied, which make it possible to simulate in low-pressure atmospheric air some properties of red sprites - pulsed discharges observed in the upper layers of the Earth's atmosphere at altitudes of 40-100 km. DPJs were initiated by the plasma of a pulse-periodic capacitive discharge created in a quartz tube between two external electrodes and propagated simultaneously in opposite directions. To form the DPJs, which moved towards each other, two pairs of ring electrodes were used, installed at a distance of 66 cm. When unipolar voltage pulses from generators were applied to each pair of ring electrodes with a delay of hundreds of nanoseconds, bright areas of luminescence (BAL) similar to those observed in the lower area of the column sprites appeared. It has been established that at a generator voltage of 7 kV, the optimal air pressure for the appearance of BAL is 1-2 Torr. It is shown that BALs arise due to the interaction of streamers that make up the DPJs. The speed of propagation of the DPJ front was measured for the positive polarity of voltage pulses applied to the ring electrodes. Photographs and emission spectra of the DPJs, as well as bright regions in the DPJs, were obtained. Using the SPECAIR program, plasma parameters were calculated in different areas of diffuse plasma jets. It has been established that in the region where BALs appear, the average value of the electron temperature decreases.

The article examines the situation around differential equations as a tool of natural science. On the one hand, during the “Quiet Scientific Revolution” of the 18th century, they made it possible to overcome the limitations of human intuition and reveal the potential of analytical methods for understanding nature. On the other hand, by the end of the 19th century, the problem of integrability of differential equations, which most clearly manifested itself with regard to the “n-body problem,” showed the need to rehabilitate intuition as the most important factor in scientific knowledge. It was the appeal to intuition that determined the creation of qualitative/geometric methods for studying nonlinear systems. Based on the analysis of this situation, the article draws a conclusion about the changes in methodology when scientific knowledge meets its limits: here the choice of mathematical tools is made in such a way that the “complexity” of one of the elements of the research situation, which has become an insurmountable barrier for knowledge, is transferred to some other element. So, this “complexity conversion” allows progress in the study of nature.

The paper reviews «The Inessential Indexical. On the Philosophical Insignificance of Perspective and the First Person» written by Herman Cappelen and Josh Dever. The review presents the main arguments of each of ten chapters

In the monograph "Geological cognition as a subject of philosophical and methodological analysis" (Ekaterinburg, 2003. 200 p.) V.A. Mironov makes an attempt to solve the problem of scientific status of geological cognition. This work is particularly important in the context of the vacuum in the philosophical and methodological studies of geology, which was formed by the end of the 1980s. The author distinguishes two directions, within the framework of which philosophical problems of geology are studied: domestic (Soviet, Russian) and represented in the English-language literature (mainly British and American). At the same time, he draws attention to the fact that separately each of these traditions does not allow to fully reflect the complexity of the process of geological cognition.