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In the 21st century, we are experiencing a major change in teaching methods caused by the ubiquity of the Internet, which means that knowledge is available to anyone on the Internet without leaving home. Today, the role of a teacher is changing. Students perceive information differently. With the development of information technology, the penetration of digital tools into various spheres of our life is becoming common practice, and the field of education is no exception. Digital technologies provide many opportunities to improve education. One of the possible directions for improving higher professional education using digital technologies is the use of distance learning in the educational process. In distance learning, it is important to transfer materials not only through video calls to the student (webinars, video lectures), but also through the use of interactive technologies, especially in laboratory and practical works. This article provides an overview of the world experience in the development and implementation of labs with remote access. An approach to the creation of virtual laboratory works with remote access working in a virtual reality environment is considered. It is shown that equipment models with a computer interface completely analogous to real devices and the use of virtual reality elements make it possible to increase the effectiveness of their use in the educational process. A description of the creation of a laboratory work on the study of a microwave filter is given.

The paper considers the modeling of the H-waveguide filter. An analysis of its characteristics is carried out. The creation of a computer model for its inclusion in a virtual laboratory is described. In the new lab, the measuring instruments have a completely realistic interface and can be operated by pressing buttons on the front panel.

The problem of electrodynamic analysis of modes structure in a circular waveguide with metal radial T-ridges and layered dielectric filling is solved. The calculation algorithm of cutoff wave numbers, electromagnetic fields components of TE- and TM-waves and propagation constants of hybrid waves taking into account field singularity at metal circular segment of finite thickness have been developed. The dependencies of the normalized cutoff wave numbers and propagation constants on the geometric dimensions of the structure and on dielectric permitivity are investigated. The electromagnetic field's visualization of the main and higher modes for TE- and TM-waves and hybrid waves are shown.

The article describes the use of modern trends and information technologies for the development of training programs for future engineers. The solutions of several countries are given along with the results of own projects of the authors. The work reflects the influence of new technologies on the way of learning and teaching. The work methodology is also given.

The paper is aimed at modeling various radio engineering devices to incorporate them into a virtual laboratory. The development of a microwave transistor amplifier and its integration into a virtual laboratory are considered as well as connecting its model to a model of a vector network analyzer with a completely realistic interface. The created laboratory work allows us to study the configuration and operation of the transistor amplifier, as well as the design technique and tuning input and output amplifier matching circuits.

The possibility of applying the partial region method to investigate a cylindrical structures with inhomogeneous dielectric filling and a complex cross-sectional shape are presented in this paper. To improve the convergence of the method and to increase the speed of calculating the algorithm at the interface, we used functions that take into account the behavior of the electromagnetic field near metal ridges. The research is carried out to compute the electromagnetic waves propagation constants in a circular waveguide and an analysis is carried out to investigate the dependence of the electrodynamic characteristics on various values of dielectric constant and geometric dimensions.

The article presents the results of developing technology for the production of curd cake using a low-calorie sweetener sucralose. An analysis of literary sources has shown the relevance of developing food technologies with lower calories and glycemic index as a preventive measure in the fight against an increase in diabetes. The implementation of this direction in the form of a partial replacement in the sugar formulation for effective sweetenrs sucralose is proposed. The obtained integral quality estimates of sugars and sucralose at the levels of 0.82 and 0.60, respectively, using qualimetric analysis on five characteristics allowed us to conclude in favor of the predominant use of sucralose. The optimization of the technology for the production of curd cake using sugar substitute sucralose was carried out. As a prototype, a sugar-based recipe was used, in which a partial replacement (at the level of 30, 50 and 70%) of sugar with sucrose was carried out. The latter was used as a commercial sweetener TM Splenda. All samples, including the control on sugar, were subjected to organoleptic evaluation, which showed the absence of extraneous flavors in all samples and their similarity in terms of sweetness. However, unsatisfactory indicators were found for the sample with a replacement of 70%, we are talking about the color and characteristics of the crumb. This made it possible to opt for technology with sugar substitution in the range of 30-50%. All investigated samples of curd cake in terms of organoleptic and physico-chemical parameters met the requirements of regulatory documentation. Based on the results obtained, a technological scheme for the production of curd cake with sucralose was developed. Calculation of the energy value of the obtained product in comparison with the control sample on sucrose showed a decrease in the calorie content of the product by 10%. The results are important for the development of technology foods for people with diabetics.

Computer simulation and synthesis of waveguide selective devices based on circular waveguides with T-shaped metal ridges have been performed. A method for obtaining the initial approximation for further optimization of their characteristics has been described. As basic elements, cavity resonators consisting of sections of circular waveguides with two T-shaped metal ridges are used. The results of simulation of a band-pass filter have been presented.

We solve the problem of electrodynamic analysis of the mode composition of radiation in a circular waveguide with thin radial metal ribs. Algorithms for calculation of cutoff wave numbers and components of the electromagnetic fields of the H and E modes have been developed with allowance for the singularity of the field behavior near a thin metal rib. Spectral characteristics of the waveguide are studied. Structures of the electromagnetic fields of the fundamental mode and the higher modes are determined.

A novel approach to computer simulator development of microwave measurement equipment is presented. The main feature of the software is an interface of the simulator, which is an interactive image of the real equipment allowing to manipulate the keys and other elements of the front panel by the computer mouse. For the measurement procedure, the simulator allows to use analytical formulas or upload the data from the computer models of the microwave devices and from the real measurements in *.s2p format. Implementation of the developed simulator into the educational process provides each student with an unlimited access to the measuring equipment and gives the opportunity not only to study the characteristics of microwave devices but also to gain experience with the real equipment due to interactive computer interface that is completely identical to real front panel.

This paper provides information about the results of investigation of circular dielectric filled waveguide with metal ridges. One of the most important characteristics of waveguide structures are cutoff wave numbers. In our research we focus on cutoff wave numbers of the dominant mode and higher order modes. So, the method which is applied is the partial regions method. The researched structure has metal ridges and corners so a singularity of electromagnetic fields is considered by adding special functions in equations. Equations for electromagnetic field components are presented. Besides cutoff wave numbers the pictures of isoline of electromagnetic field are obtained. These results can be useful to create filters, diplexers and others devices based on circular dielectric filled waveguide with metal ridges. The computed results are found for different number of series terms in expansion and different numbers of approximating functions, so it allows to estimate the accuracy of the algorithm.

The article presents the results of the study of the kinetics of degradation of ascorbic acid (АA in odel jelly during time storage at temperature 4 °С. Jelly samples based on concentrated apple juice and gelatin with a content of 2% and 3% were enriched with AA in the amount of 25, 50 and 75 mg/100 g of the sample. Determination of AA content carried out by galvanostatic coulometric titration. It was found that the content of AA in samples of fruit jelly decreases with increasing storage time. The loss of AA is observed more pronounced in the initial period of storage and is more characteristic of the sample containing 2% gelatin compared with the sample containing 3% gelatin. The mechanism of ascorbic acid degradation is considered as a reaction of its multi-stage oxidation with the dominant stage of oxidation to dehydroascorbic acid. The simulation of the degradation of ascorbic acid in the jelly during storage using the equations of the kinetics of the reaction of zero and first order. The goodness of model fitting to the experimental data was evaluated by adjusted coefficients of determination and the root mean square error. Compared with the zero order, the kinetics of degradation corresponded better to the first-order reaction model for all the studied samples. The reaction rate constant and half-life calculated for a first-order kinetic model are 0.00027 (1 / hour) and 107 days for samples with gelatin content of 2% and, respectively, 0.00015 and 193 days for jelly with a gelatin content of 3%. The obtained values of the first-order reaction rate constants for samples of model jelly correspond to similar values in other food products (juices, drinks, some solid products). The magnitude of the half reaction times allows the residual content of ascorbic acid to be estimated over time. The results are important for the development of technology for ascorbic acid-rich foods.

The paper presents the approach of designing a virtual laboratory which can be used for classroom studying and for distance learning. Such virtual works are a good alternative to highly expensive microwave measurement equipment. The software package was written in C++. The testing results of applying virtual laboratory for radiophysics measurements are considered.

The problem of the electrodynamic analysis of electromagnetic fields of circular metal waveguide with thin metal ridges and unhomogeneous dielectric filling is solved. The calculation algorithm of cutoff wave numbers and components of electromagnetic fields of quasi-TE-waves taking into account field singularity at thin metal ridges is developed. The visualization of electromagnetic fields is presented

The article presents the results of the development of a method for the determination of L-ascorbic acid (AA) in model fruit jellies containing gelatin. In the determination of AA, a coulometric method with electrically generated iodine as a titrant in a galvanostatic mode with a current of 2-5 mA was used. As a research object, model fruit jelly with 2% and 3% gelatin content was used. In addition to gelatin, the systems contained apple juice concentrated clarified and potassium sorbate (used as a concerto). The peculiarity of the preliminary preparation of the samples was the stage, which envisaged the melting of the samples before the quantitative determination of AA. In order to assess the suitability of the proposed methodology for the quantitative determination of AA in fruit jelly, a validation evaluation was performed on the following parameters: specificity, linearity and the range of an analytical method, limits of detection and determination, accuracy and reproducibility. Specificity has been studied on standard aqueous solutions of AA. It has been shown that under two conditions: 100% of current output and stoichiometricity of the oxidation reaction with iodine AA, the theoretical slope of the amount of the electrice curve from the analyte concentration with accuracy up to 0.2% coincides with the experimental one. The following parameters were determined: the working area of the technique 4.92-127.6 mg/100 g; limits of the determination 1.62 mg/100 g and quantitation 4.92 mg/100 g. The absence of a systematic error for standard and fruit jelly solutions was evaluated using the "introduced-found" method. Error of recovery did not exceed RSDCorrectness and reproducibility were evaluated by the method of varying the weights at three levels of concentration using three sets at each level. Fischer and Student's criteria, which were used to compare average values, testified to the validity of the indicators of "correctness" and "reproducibility". Comparing the studied parameters, the best results were obtained for fruit jelly with a 2% gelatin content compared to a jelly with a content of 3%. The obtained results testify to the possibility of application of the developed method of determination of ascorbic acid in real food systems.

The solution of the problem of spectral electrodynamic analysis of a circular waveguide with radial metal ridges and with thin flanges is presented. The calculation algorithms of cutoff wave numbers and components of electromagnetic fields of TE- and TM -waves are developed on the basis of the partial regions method taking into account field singularity at metal ridges. The spectral characteristics of the waveguide are investigated. The visualization of electromagnetic fields patterns of the dominant and higher order modes is realized.

In this paper a method of computer modeling of measurement devices and instruments is described. A software package for virtual laboratory creation is developed. Models of measurement devices have user interface identical to real devices and can simulate the behavior of various devices. The created models of virtual measurement devices can be implemented for experimental data analysis provided in common used format *.s2p.

The general case of diffraction of nonsymmetrical TM vp and TEvp modes on irregularity in circular waveguide is discussed. The calculation is performed on the basis of the method of partial areas taking into account the features of the electromagnetic field at the metal edge. The high accuracy of the method is demonstrated.

The original approach to the computer modelling of the modern measuring equipment is presented. The interface of the computer model is an interactive photo of the real device with all buttons operation available by the PC mouse. The models of the devices can be combined in the measuring stands in arbitrary order and provide a variety of virtual laboratory works. As an example, the computer models of the Vector Network Analyzers Rohde&Schwarz ZVA40 and Keysight Technologies E8363B PNA are presented. The measuring data of the investigated microwave devices can be provided by the analytical formulas, by the computer simulation, and by the measured resultes of the real devices stored in *.s2p files.

The solution of the problem of spectral electrodynamic analysis of a circular waveguide with radial metal ridges is presented. The calculation algorithms of cutoff wave numbers and components of electromagnetic fields of TE- and TM-waves are developed on the basis of the partial regions method taking into account field singularity at metal ridges. The spectral characteristics of the waveguide are investigated. The visualization of electromagnetic fields patterns of the dominant and higher order modes is realized.

The article presents the results of the development of the technology of candy caramel for dietary-functional purpose using monosaccharide fructose and sweeteners of the new generation - polyols isomaltitol and maltitol. The feature of this technology is the lack of starch molasses in the formulation. The physical-chemical, structural-mechanical and sorption-desorption properties of the obtained caramel samples in comparison with caramel produced on the basis of traditional sugar technology are investigated. The content of reducing agents in the developed caramel samples is 6.5 and 6.7%, respectively, for samples on isomaltitol and maltitol, which is more than 3 times less than in caramel based on sucrose and starchy molasses. Isotherms of adsorption-desorption of moisture showed that the equilibrium moisture of samples at аw 0.7−0.75 varies within 2.0−2.5%, which contributes to the absence of violation of the amorphous structure during storage, despite the reduced content of reducing agents. Calculation of glycemic index and energy values indicates that new types of caramel deserve the labeling of "Product with reduced glycemicity" and "Low calorie product". On the basis of the research, new types of candy caramel "Fruity lightness" on the basis of isomaltitol and "Nasoloda" on the basis of maltitol were developed.

The problem of developing of virtual laboratory works is considered in the paper. The peculiarity of proposed approach is due to photography identity of user interface of virtual instruments to the user interface of real devices. Another key feature is in simplicity of extending the structure of virtual laboratory works. In the present work we develop the computer model of vector network analyzer Agilent (Keysight) PNA E8363B and investigated UHF microstrip filter. Proposed software package allows expand the virtual laboratory for studying the UHF devices and instruments.

New design approach and software package for computer modeling of virtual education laboratory works is proposed. Measurement equipment in virtual laboratory has interface and behaviors which are identical to real devices and allow studying characteristics of UHF devices and elements.

The method of computer simulation of microwave devices and special laboratory workshops is described. Simulated laboratory has a module structure. The basis for constructing a model of the specific workshop is a concept of the abstract “device” with layout is identical to the installation of a real one. The software interface allows changing the configuration and frequency tags to carry out all necessary measuring characteristics.

The study introduces the approach of creating a virtual laboratory for performing laboratory works with remote access. The proposed virtual lab can be used for distance learning and is an extension of the functionality of the previously created virtual workshop. This virtual laboratory with remote access is an alternative to laboratory works performed with real experimental equipment and provides an opportunity to gain skills in operation with measuring microwave equipment without giving classes in educational laboratories. The results of testing virtual lab works with remote access in educational radiophysics laboratories are presented.

The method for computer simulation of microwave measurement units and a virtual laboratory workshop for RF engineers education are described. The front panel view and manipulation principles of the models are identical to those of the real units. As an example the simulation results of the Rohde&Schwarz vector network analyzer with microwave filter are presented.

In this work the method of computer simulation of microwave devices is considered and the special virtual laboratory workshops are created. The simulated laboratory has module structure. At the model basis the concept of the abstract "device" which configuration in installation is identical to real devices underlies. As an example the laboratory work is simulated with the set of the following devices: swept frequency generator, the VSWR/attenuation scope and the studied device which is a waveguide slot antenna. In the virtual laboratory program interface the user can change the frequency markers, the dimensions and displacement of slots to carry out all necessary measurements of antenna internal characteristics, thus the frequency characteristic of the studied device is displayed on the screen of the indicator unit in real time.