Introduction. Polyaniline (PANI) demonstrates a unique combination of electrophysical properties, stability, and ease of synthesis, making this material one of the most promising conductive polymers. Its ability to significantly alter electrical conductivity during protonation provides broad opportunities for tailoring the functional characteristics of materials. Despite extensive research, the charge transfer mechanisms in PANI-based systems remain insufficiently studied. The lack of a unified theoretical model describing the relationship between chemical structure and electronic properties poses significant limitations for the targeted development of PANI-based materials with specified parameters.

Aim. To generalize current knowledge of conduction mechanisms in PANI and to develop a comprehensive approach integrating polaron theory and hopping conductivity models.

Materials and methods. The selection of literature sources for review was conducted using a chronological approach covering a period of over 10 years, driven by the need for a retrospective analysis of the evolution of modern views on conduction mechanisms in PANI and the extension of its application areas. The criterion for forming the final set of sources was the presence of factual data relevant to the research topic.

Results. The analysis revealed the predominance of the polaron conduction mechanism in protonated PANI and highlighted the inadequacy of existing theoretical models (such as variable-range hopping and tunneling mechanisms) in providing a comprehensive description of its electronic properties. This necessitates the development of a comprehensive approach integrating elements of various transport theories.

Conclusion. The analysis of modern theoretical approaches to describing conductivity in PANI revealed fundamental differences between hopping transport and tunneling mechanism models. It is noted that none of the concepts possesses sufficient predictive power regarding the spatial distribution of charge transfer. The obtained results indicate the need to develop a synthetic theory combining the methodological advantages of the considered approaches. The creation of such a hybrid model will facilitate progress in the design of PANI-containing materials with tailored electrophysical characteristics.

Introduction. The Cramér–Rao lower bound for the root-mean-square error of height estimation in radio altimeters with continuous frequency-modulated periodic signals is determined. Analysis of the bound showed that a periodic stepwise change in the emitted signal frequency between two levels, the difference between which is equal to the selected deviation value, is a type of frequency modulation that enables the potential altitude estimation accuracy of lowaltitude radio altimeters. However, such signals cannot be used in existing radio altimeters that are based on beat frequency estimation. An alternative solution is to implement a phase-locked altitude measurement mode.

Aim. To investigate the feasibility of implementing a phase altitude measurement mode in a low-altitude tracking radio altimeter using a phase-locked loop (PLL) for altitude estimation, and to verify its performance using mathematical simulation.

Materials and methods. The stated problem was solved by constructing a mathematical model of a tracking radio altimeter with the PLL to implement the phase method for altitude estimation.

Results. The conducted computer simulation demonstrated the operability of the PLL-based radio altimeter that utilizes the phase method of altitude estimation. When operating over a perfectly flat surface, the altimeter provides an unbiased and effective altitude estimate with signal-to-noise ratios greater than 5 dB. In the case of a rough surface, the quality of altitude estimation in the altimeter is approximately an order of magnitude higher than in tracking altimeters, which implement estimation of the beat signal frequency.

Conclusion. The data obtained via computer simulation demonstrate the potential for achieving the height estimation accuracy in a PLL-based radio altimeter that combines frequency and phase measurement modes. Future research will examine the influence of various factors on the performance of the radio altimeter and its circuit design.

Introduction. When measuring the distance with a laser rangefinder, interference along the path of the beam can significantly affect measurement accuracy. Classical filtering algorithms, which rely on the characteristics of the received signal, are unable to reliably distinguish the useful signals from natural interference and targets. In this work, we propose an algorithm for classifying objects based on processing echolocation path signals obtained by vertical laser rangefinder sensing. The main task is to distinguish useful signals against the background of natural interference, such as atmospheric aerosols, haze, and clouds. The problem is solved by a method based on isolating intensity peaks on an echolocation path, followed by their classification using machine learning methods. Owing to the preprocessing of the signal, the algorithm is compatible with systems having different parameters of the emitter and the receiving channel.

Aim. To develop an algorithm for identifying and classifying objects on an echolocation path obtained by vertical sensing using a laser rangefinder.

Materials and methods. Vertical sensing was carried out using an experimental stand, which includes a laser rangefinder with a radiation source of 100 mJ and a wavelength of 1064 nm. This made it possible to collect data in various meteorological conditions. The sample included echolocation traces obtained from different objects with different characteristics, such as monolithic structures, lattice structures, and natural interference encountered during vertical sensing. A comparative analysis of the following algorithms was conducted: logistic regression, random forest, gradient boosting, and a neural network algorithm. The metrics accuracy and F1-score were chosen to evaluate the prediction quality of the models. The models were trained on a dataset containing cloud structures, with a split into training and test sets.

Results. The gradient boosting model demonstrated performance comparable with that of the neural network algorithm, achieving an F1-score of 0.89 on the test set. This makes it suitable for deployment in resource-limited systems without compromising predictive performance.

Conclusion. The results confirm the effectiveness of the algorithm for useful signal discrimination under interference conditions, which is important for geodesy, navigation, and satellite sensing.

Introduction. In recent years, there has been a growing trend toward the miniaturization of printed radiators for phased arrays. At the same time, such radiators are frequently required to operate over an ultra wide bandwidth, support wide angle scanning, and enable dual polarization. To enhance the performance of printed radiators, matcing inserts with specific geometries and dimensions can be used.

Aim. To increase the overlap ratio of a printed radiator while maintaining its ultra wideband performance and wide-angle scanning within an angular sector of ±60º, limited by the mismatch, and ensuring electrical compactness with a height not exceeding λ at the upper operating frequency through the use of various matching metal inserts.
Materials and methods. Electrodynamic simulation of the radiator was performed as part of an infinite antenna array using the Ansys HFSS computer aided design software.
Results. The use of metal rectangular inserts measuring 25.5 × 145.0 mm at the edges of the radiator allowed its operating frequency band to be extended, while the use of an additional insert in the aperture allowed its matching (radiator with combined inserts) to be improved. The operating frequency band of the original radiator, at a voltage standing wave ratio (VSWR) of ≤ 3, extends from 257.6 to 732.5 MHz, corresponding to an overlap ratio of 2.844. For the radiator with combined inserts, the operating band at the same VSWR level ranges from 164.9 to 677.5 MHz, yielding an overlap ratio of 4.109. The electrical dimensions of the proposed radiator are 0.339λ × 0.339λ × 0.678λ at the upper operating frequency of 677.5 MHz, and 0.083λ × 0.083λ × 0.165λ at the lower frequency of 164.9 MHz.
Conclusion. The application of combined inserts in the radiator allows its overlap ratio to be increased at the same time as maintaining its ultra wideband performance, wide-angle scanning in the sector of angles up to ±60°, and compact dimensions. The proposed radiator can be used in phased arrays for radio communication, radar and radio navigation systems.

Introduction. The safety of conducting activities on the snow and ice cover of a reservoir depends directly on the accuracy of its condition assessment. This is particularly important when landing a helicopter on unequipped and unexplored snow covered areas or frozen water bodies for transporting goods and people, evacuating victims, or conducting search and rescue operations. The ability to remotely assess the characteristics of snow and ice layers and reconstruct their structure makes it possible to conclude whether the selected site is suitable for helicopter landing or whether an alternative site, which meets the necessary requirements, should be selected. Ultimately, this determines the safety of aircraft landing.
Aim. Development of a non invasive method for assessing planar layered media based on polarization relationships of backscattering signals with vertical and horizontal polarizations within a helicopter mounted subsurface sensing radar system.
Materials and methods. The Engee platform and the Julia programming language were used to simulate the operation of a radar system for subsurface sensing.
Results. An innovative method for remote assessment of the characteristics of planar layered media is proposed. The approach is based on analyzing the polarization properties of backscattered signals from the interfaces of layers within a planar layered medium, using both vertical and horizontal polarizations. Specific ranges of polarization backscattering ratios that correlate with varying densities of snow and ice layers at particular incidence angles are identified.
Conclusion. The proposed non invasive method for analyzing planar layered media based on polarization characteristics of backscattered radio signals opens up new possibilities for the assessment of snow and ice cover. This approach makes it possible to evaluate unprepared and unexplored snow covered sites, as well as reservoirs covered with snow and ice, for helicopter landing. A distinctive feature of the proposed method lies in its ability to detect and characterize all layers within a multilayer environment, compared to existing methods that are limited to analyzing exclusively the near surface layer.

Introduction. Recent years have seen an increased interest in research on small autonomous vehicles, in which naviga-tion are the fundamental problems that must be addressed. In outdoor environments, the use of global satellite naviga-tion systems remains the optimum solution due to their wide coverage, high level of automation, and ease of use. How-ever, operation in unknown and GPS denied environments, such as indoor spaces, is still a relevant research problem. The Valve Lighthouse (LH) system has been proposed for guiding mobile platforms in confined spaces due to its autonomous operation, low cost, ease of deployment, and miniature onboard sensors, which are particularly suitable for small scale vehicles. Nevertheless, similar to other indoor localization sensors, the LH system does not allow the reconstruction of an unknown environment (i.e., obstacle detection), which may lead to collisions and potential damage to the vehicle. Therefore, integration with a mapping system is necessary. Currently, an optimal choice for small scale platforms is ORB SLAM based on a monocular camera. The main drawback of monocular camera based systems lies in their inability to determine the scale factor of the map. In this regard, this paper proposes an algorithm to estimate the map scale factor of the ORB SLAM system through its integration with an infrared system.

Aim. Determination of the map scale factor of the ORB SLAM system in an integrated infrared system.

Materials and methods. The proposed algorithm is based on an extended adaptive Kalman filter with a Sage window combined with a maximum likelihood estimation method.

Results. The proposed algorithm enables the determination of the map scale factor of the ORB SLAM system along each axis in real time. Conclusion. An algorithm is proposed to determine the map scale factor of the ORB SLAM system along each axis in real time within a system integrated with the Valve Lighthouse infrared system.

Introduction. The microfocus X ray tube is a key component in modern medical diagnostic, scientific research, and industrial applications. One of its main elements is the focusing system, with the magnetic lens at its core. The characteristics of this lens largely determine the spatial resolution of the device. Accurate consideration of thermal conditions is essential for ensuring the efficiency and reliability of the focusing system. The importance of thermal analysis has increased significantly due to the tightening requirements imposed on the quality of X ray images. Today, the electron-ic lenses of the X ray tube focusing system are cooled mainly by forced liquid cooling. However, this approach creates additional technological and economic difficulties during the manufacture and operation of the device.
Aim. Construction of a numerical model of thermal processes in a magnetic lens, as well as determination of its optimal parameters for operation without forced liquid cooling and ensuring a micron diameter of the focal spot.
Materials and methods. Numerical and analytical methods were used to construct a model of thermal processes in a magnetic lens. The results obtained were evaluated using numerical modeling of thermal processes implemented in the Comsol Multiphysics environment.
Results. The temperature values of the magnetic lens coil obtained within the calculation model and as a result of simulation did not exceed the maximum permissible values. The temperature distribution graphs across the coil cross section obtained by the calculation and Comsol Multiphysics models showed good agreement, which confirms the validity of the calculations.
Conclusion. The obtained optimal parameters of the magnetic lens ensure its stable operation under natural cooling.

Introduction. Intensive research is currently focused on identifying materials suitable for the development of ad-vanced gas sensors and systems for water and air purification. Among the diversity of purification approaches, photocatalysis is viewed as a particularly promising method. Considering various potential materials, titanium dioxide stands out due to its physicochemical properties. Reactive magnetron sputtering is considered one of most effective techniques for titanium dioxide deposition.

Aim. To investigate the influence of synthesis parameters on the efficiency of a TiO2-based photocatalyst for its further application in water purification and gas sensing.

Materials and methods. Two series of five samples each were manufactured. In the first series, the sputtering duration was varied (3, 7, 10, 15, 30 min). In the second series, the argon-to-oxygen ratio in the reactive mixture was varied (90/10, 70/30, 50/50, 30/70, 10/90%). Subsequently, all samples in both series were irradiated for 2 h and then evaluated for hydrophilicity using an OSA 15 EC device.

Results. Two dependencies, i.e., the contact angle as a function of sputtering duration and the contact angle as a function of oxygen content in the reactive mixture, were established. The employed method was found to be suitable for depositing photocatalytic titanium dioxide films. Upon an increase in film thickness, the contact angle index varies within 37 and 45º. A 10-fold increase in sputtering duration (from 3 to 30 min) caused no significant differences in the photocatalytic and hydrophilic properties of the samples. It was experimentally established that the most photoactive films are synthesized at Ar/O2 ratios of 90/10 and 10/90%.

Conclusion. The developed photocatalytic titanium dioxide film can be recommended for a number of water purification tasks and for use in gas sensors.

Introduction. The determination of normative ranges for the biomechanical parameters of human motor activity is a relevant task for disorder diagnostics, orthopedic treatment planning, rehabilitation monitoring, and development of assistive devices. The creation of such a database requires a validated methodology for data collection and analysis.
Aim. To develop and test a methodology for collecting and analyzing the biomechanical parameters of fundamental motor activities (walking, squats, lunges, torso bends) using modern motion capture systems with the purpose of compiling a normative database of spatiotemporal, angular, and electromyographic (EMG) characteristics.
Materials and methods. The Qualisys motion capture system (kinematics), Kistler force plates (kinetics), and the Delsys Trigno EMG system (activity of key lower limb muscles) were used. Data was collected from eight healthy volunteers in a laboratory setting following a standard protocol. Preprocessing included marker trajectory interpolation, EMG signal smoothing, and outlier removal (based on IQR). Normative ranges (±1 SD) were calculated based on mean values and standard deviations.
Results. A methodology for collecting biomechanical data for four types of motor activity (walking, squats, lunges, torso bends) was developed and tested. The average values and preliminary normative ranges for spatiotemporal, angular, and EMG parameters were obtained, reflecting characteristic movement patterns and muscle activation in healthy individuals. According to the results obtained, the proposed methodology is effective for comprehensive collection and analysis of biomechanical data. The use of Qualisys and Delsys Trigno systems ensured accurate recording of kinematic, kinetic, and EMG movement parameters. The developed preliminary normative ranges indicate the potential of the methodology for diagnosing movement disorders, rehabilitation, and engineering design (exoskeletons, prosthetics).
Conclusion. The proposed methodology represents a reliable tool for an objective functional assessment of human motor activity. The obtained preliminary normative data serves as a foundation for further sample expansion and formation of a comprehensive database essential for clinical practice (diagnosis, treatment monitoring, rehabilitation) and engineering applications in movement correction.