2 μm lasers are in demand for a number of practical applications, such as environmental monitoring, remote sensing, medicine, material processing, and are also used as a pump sources for optical parametric generators. Crystals of double potassium tungstates doped with ions of rare-earth elements were shown to be promising materials both for  the  creation  of  classical  solid-state  lasers  and  waveguide  lasers. The aim of this work was to develop a tunable pump laser in the spectral region of 1.9 µm based on double tungstate crystals doped with thulium ions and to study the lasing characteristics of a Ho:KY(WO₄)₂ crystal and a Ho:KGdYbY(WO₄)₂ single-crystal epitaxial layer under in-band pumping.

With a Ho(1at.%):KY(WO₄)₂  crystal, continuous wave low-threshold lasing with an output power of 85 mW with a slope efficiency of 54 % at 2074 nm was achieved. For the first time to our knowledge, continuous wave laser  generation  in  a  waveguide  configuration  is  realized  in  a  single-crystal  layer of potassium tungstate doped with holmium ions grown by liquid-phase epitaxy. The maximum output power at a wavelength of 2055 nm was 16.5 mW.

Currently, non-destructive testing is an interdisciplinary field of science and technology that serves to ensure the safe functioning of complex technical systems in the face of multifactorial risks. In this regard, there is a need to consider new information technologies based on intellectual perception, recognition technology, and general network integration. The purpose of this work was to develop an ultrasonic flaw detector, which uses a smartphone to process the test results, as well as transfer them directly to an powerful information processing center, or to a cloud storage to share operational information with specialists from anywhere in the world.

The proposed flaw detector consists of a sensor unit and a smartphone. The exchange of information between the sensor and the smartphone takes place using wireless networks that use "bluetooth" technology. To ensure the operation of the smartphone in the ultrasonic flaw detector mode, the smartphone has software installed that runs in the Android operating system and implements the proposed algorithm of the device, and can serve as a repeater for processing data over a considerable distance (up to hundreds and thousands of kilometers) if it necessary.

The experimental data comparative analysis of the developed device with the Einstein-II flaw detector from Modsonic (India) and the TS-2028H+ flaw detector from Tru-Test (New Zealand) showed that the proposed device is not inferior to them in terms of such characteristics as the range of measured thicknesses, the relative error in determining the depth defect and the object thickness. When measuring small thicknesses from 5 to 10 mm, the proposed device even surpasses them, providing a relative measurement error of the order of 1 %, while analogues give this error within 2–3 %.

Grain size is one of the most important characteristics of the microstructure of metals and alloys. Determination of the grain size of steel is regulated by Standart 5639-82 "Steels and alloys. Methods for detection and determination of the grain size". Standart includes determining the grain score by comparison with reference scales, as well as manual measurement methods. The use of image processing software opens up new opportunities for the materials analysis, including for the quantitative metallographic analysis of steels and alloys. The purpose of this work was to test the specialized "Metallography" module to determine the grain score of the image processing software "IMAGE – SP", as well as to check the reliability of the obtained results using the example of ferritic and austenitic steels.

In the "Metallography" module, the analysis of standard images of annex No. 3 of Standart 5639-82, as well as real images of the structures of ferritic and austenitic steel, is carried out. It is shown that the results correspond to the definition of the Standart grain score. The divergence in the results is 1 point, which is acceptable.

The active development of software products for the quantitative analysis of images in metallography will make it possible to legitimize the methods of computer measurement of parameters of the structures of metals and alloys by creating appropriate standards. Successful testing of the specialized "Metallography" module demonstrates opportunities and prospects for further development of specialized software products for measuring quantitative values of metal and alloy structures. The active development of software for quantitative analysis of the images in metallography will make it possible to legalize methods for measuring parameters of metal and alloy structures by computer techniques.

One of the main factors affecting the effectiveness of radiation therapy is the constancy of the patient’s position on the treatment table created by immobilization devices of various designs and held throughout the entire irradiation procedure, which guarantees the accuracy of the delivery of the prescribed dose distribution. The purpose of the work was to establish the numerical values of the dominant components of a radiation therapy session for each of the irradiation techniques most commonly used in clinical practice of the radiation therapy.

To determine the numerical values of the components of the radiation therapy session, the authors have measured each component for some clinical cases of patients’ irradiation placed. The patients had been diagnosed with the following malignant tumours: prostate cancer, breast cancer, lung cancer, head and neck tumours. More than 2000 individual measurements have been carried out with the help of such medical linear accelerators as "Clinac", "Unique", "Truebeam", and the gamma-therapeutic apparatus named "Theratron".

The numerical values of the time spent on 3 groups of parameters of an irradiation session were established: the mechanical parameters of the radiation therapy equipment, the functional characteristics of the irradiation systems and the parameters that directly depend on the personnel involved in an irradiation procedure.

According to the measurement results, the flow diagram for the procedures of verifying a patient’s position on the therapeutic table (2 different techniques), preceding their irradiation and the radiation therapy procedures themselves was proposed. It has been shown that a number of session components can run in parallel to each other thus optimizing the time spent by a patient in the treatment room.

Using the obtained values of the time spent on the radiation session parameters it is possible to actualize the mathematical model that will allow the medical physicist to determine in advance the duration of the irradiation session at the stage of treatment planning and choose a radiation therapy technique taking into account the individual parameters of the irradiation session in each particular clinical case.

The use of graphene, which has high mobility of charge carriers, high thermal conductivity and a number of other positive properties, is promising for the creation of new semiconductor devices with good output characteristics. The aim was to simulate the output characteristics of field effect transistors containing graphene using the Monte-Carlo method and the Poisson equation.

Two semiconductor structures in which a single layer (or monolayer) of graphene is placed on a substrate formed from 6H-SiC silicon carbide material are considered. The peculiarity of the first of them is that the contact areas of drain and source were completely located on the graphene layer, the length of which along the longitudinal coordinate was equal to the length of the substrate. The second structure differed in that the length of the graphene layer was shortened and the drain and source areas were partly located on the graphene layer and partly on the substrate.

The main output characteristics of field-effect transistors based on the two semiconductor structures considered were obtained by modeling. The modeling was performed using the statistical Monte Carlo method. To perform the simulation, a computational algorithm was developed and a program of numerical simulation using the Monte-Carlo method in three-dimensional space using the Poisson equation was compiled and debugged.

The results of the studies show that the development of field-effect transistors using graphene layers can improve the output characteristics – to increase the output current and transconductance, as well as the limit frequency of semiconductor structures in high frequency ranges.

The miniature spacecraft have a high ballistic coefficient, which is advantageous for the resolution of sensing the density  of  the  upper  atmosphere.  The  purpose  of  this  work  is  to  show  new  features of the "falling spheres method" based on the miniaturization of the Spacecraft. The "falling spheres method" is used to probe variations in the density of the upper atmosphere.

A technical solution for diagnostics of orbital sections with abnormal changes in the speed and acceleration of  spacecraft  equipped  with  onboard  navigation  receivers  and  micro-accelerometers is considered.

The technical result of the proposed development is the efficiency and cost – effectiveness of sounding variations in the density of the upper atmosphere, seismic-orbital effects-variations in the density of the atmosphere over earthquake-regions and the seismic hazard.