Vol 5, No 1 (2025)

A new impedance method for measuring and monitoring surface temperature and non-stationary heat flow in conductive thermophysical objects is presented. The peculiarity of the method is the use of the electric skin effect, which allows using the conductive control object as a sensitive element, which increases the speed of measurements due to the absence of additional sensors in the measurement area. By electronic (frequency) control of the skin layer thickness, it is possible to change the sensitive area and sensitivity of measurements. The use of the mathematical apparatus of fractional operators allows us to relate the non-stationary heat flow to the surface temperature, which makes it possible to simultaneously measure two thermophysical quantities – surface temperature and non-stationary heat flow. A corresponding algorithm for numerically calculating the non-stationary heat flow using fractional derivatives of half order has been developed. Experimental studies of the proposed impedance method have been carried out and its advantages have been shown.

The paper presents an overview of systems for monitoring the dynamic characteristics of vehicle wheels, such as forces, moments, and angular velocities. Existing and prospective monitoring systems were considered, general characteristics of systems of the specified class were determined, which allowed proposing a classification that enables the identification of the application area and specific features of systems of each class. Promising directions for the development of advanced systems for monitoring the dynamic characteristics of wheel adhesion to the road surface and methods for their implementation in active safety systems of vehicles were determined. Based on the set of tasks facing advanced dynamic characteristics monitoring systems and the technical capabilities of monitoring systems, promising development paths have been identified based on the use of fiber-optic measuring systems with radio-photonic methods of signal acquisition and processing, and the use of addressable fiber Bragg structures as a sensitive element of the sensor.

Noninvasive operational monitoring of an athlete's vital signs is a necessary requirement for the control and prevention of overloads during the training process for many reasons, one of the most important of which is to increase effectiveness of the training process. This article discusses the main methods of ballystocardiogram record based on the fiber-optic technologies, namely fiber Bragg gratings and addressable fiber Bragg structures, in the dynamic state of an athlete during the training process. Based on the analysis, it was concluded that it is necessary to build athlete-wearable devices operating on the principle of an accelerometer. The advantages of using addressable fiber Bragg structures in accelerometers are shown, which makes it possible to increase both the accuracy of the formation of the recorded ballystocardiogram as an oscillatory process and to characterize the process of their removal as addressable in the presence of several wearable sensors.

A Ramsey resonance with narrowed lines is experimentally discovered in an optically thick two level atomic medium. We show that the formation of the narrowed lines is caused by the effects of multiple photon echo signals originating in the depths of the optically thick atomic medium, which is also confirmed by the observation of these signals at the medium output. The analytical solutions obtained using the pulse area theorem and its generalization to photon echo together with the inverse scattering method well describe the main patterns of the processes under consideration and spectroscopic parameters of Ramsey resonances.