Home – Home – Jornals – Avtometriya 2021 number 1

An algorithm for combined estimation of the frequency and its change rate by increasing chirp signal sampling is proposed. The algorithm allows sequential calculation of the frequency estimates taking into account the time correlation of errors of the initial phase difference measurements. The proposed method is computationally efficient, and the results tend to the minimum variance unbiased estimator as the input signal-to-noise ratio increases.

The BRISK, AKAZE, and ORB feature detectors are compared in a series of experiments on a set of 10,000 images. Several characteristics of the efficiency of these detectors are estimated: the proportion of correctly found positions of features, the proportion of correctly established correspondences, and the number of correspondences in comparisons of two randomly chosen images. The dependence between the average number of false correspondences and the value of proximity of descriptors is estimated. Distributions of the number of correct and false correspondences are plotted.

Convolutional neural networks (CNNs) allow reaching the highest accuracy for the task of object detection in images. The major challenges in further development of object detectors are false-positive detections. In some applications, it is of interest to detect only moving objects: face of a person approaching the intercom or car in overall traffic. In this paper, we propose an approach to object detection, which makes it possible to reduce the number of false-positive detections by processing only moving objects. The proposed approach is a modification of CNNs already trained for the object detection task and can be used to improve the accuracy of an existing system by applying minor changes to the algorithm. The efficiency of the proposed approach is demonstrated on the open dataset "CDNet2014 pedestrian."

Issues of anomaly detection in nonstationary process signals are considered because anomalies could be an early indication of defects and equipment failure. An approach to detection of anomalies utilizing the Hilbert-Huang transformation and statistical model is presented. The main idea of the proposed approach is to analyze the statistical parameters of the components of the Hilbert-Huang transformation, which has high adaptive properties for nonstationary signals and provides precise resolution in the time-frequency domain. The paper describes the principal scheme and algorithm of the approach, detailed definition of the statistical model, numeric experiments on real and augmented data, and comparative analysis with similar anomaly detection methods.

The results of the indication of the vaccinia virus by using nanowire biosensors made on the silicon-on-insulator basis are presented. In the experiments, we used the vaccinia virus, the strain of LIVP from the collection of the Federal State Scientific Research Center of Virology and Biotechnology "Vector" of Rospotrebnadzor, and the rabbit blood serum containing specific polyclonal antibodies to the vaccinia virus. The results show that the polyvalent blood serum at the interface between the biosensor surface and the viral suspension is electrically neutral, the vaccinia virus is positively charged, and the complex of the polyvalent blood serum and vaccinia virus is negatively charged.

The analysis of nucleic acids remains an important trend in the development of medical diagnostics. Modern ultrasensitive diagnostic systems make it possible to convert a specific interaction during the analysis into a hardware-recorded signal. An example of such diagnostic devices is biosensors based on silicon-on-insulator (SOI) field-effect transistors (FET). In this work, we use glass surfaces (as a Si/SiO₂ surface of a SOI biosensor) to optimize and test all stages of the analysis. Efficient immobilization of electrically neutral analogs of oligonucleotides on the Si/SiO₂ surface after activation of Si-OH groups with 3-glycidoxypropyltrimethoxysilane or carbonyldiimidazole is demonstrated. The possibility of detecting an RNA target on model glass surfaces in the parallel analysis mode under conditions of a low or zero salt concentration is provided. The regeneration of the Si/SiO₂ surface of the sensors for the repeated analysis and the stability of the sensors during long-term storage are demonstrated.

An analytical review of optical-acoustic receivers (OARs) based on the Golay cells in the infrared and terahertz radiation ranges is presented. The history of the OAR emergence and development from the first works of Bell, Hayes, Golay, up to the present time is considered. The OAR advantages, namely, the constant and high sensitivity in a wide range of the spectrum and the highest detection ability among thermal receivers, are noted. The main characteristics of membranes, which are the main elements of OARs, are considered, and the physical properties of graphene, as the most preferred material for membranes, are analyzed. Three OAR design groups are considered: single cells with optical information reading and a condenser microphone, selective receivers with gas-filled chambers, and matrix receivers. Estimates are presented, which show that the use of single layer graphene membranes makes it possible to create IR and THZ radiation receivers with cells of the order of tens of microns with extremely high sensitivity. A new design scheme of matrix terahertz opto-acoustic receivers with the use of hexatrigraphene (C)₆₃₍₆₎ membranes with record-breaking characteristics is proposed.

An analytical solution of the problem of deflection of a deformable mirror with a thin circular plate with a free edge under the action of a concentrated load generated by one of the actuators acting on the plate with the other end resting on an infinitely rigid base is derived. The solution is based on the application of integral transforms and takes into consideration the kinematic pairs between the plate and each actuator, which is deformed according to Hooke’s law. The analytical solution is compared to the finite element solution obtained by using the ANSYS software. The results of the study can be used to optimize the actuator positions and to control the circular deformable mirrors in adaptive optics problems.

A method for measuring displacements based on a logometric method using a branched fiber-optic collector is analyzed. An analytical model of an optical-electronic probe of small axial displacements has been developed, and significant factors influencing the character of the calibration characteristic have been determined. The light-energy analysis of the optical scheme of the measuring optoelectronic probe is carried out, and the optical loss along the optical path length is estimated.

A method for the formation and transmission of 3D holographic images is proposed, based on the formation of a 2D holographic signal by subtracting the carrier spatial frequency from the signal, thereby, compressing the holographic information for the purpose of fast transmission over a standard radio channel in real time. The information about the3D structure of the holographic object is recorded with the use of coherent and incoherent radiation, in which an analog of the object's hologram is obtained by structured light methods, suitable for transmission to a distance in the form of a 2D frame equivalent to a hologram with eliminated redundancy. This way of transmission of 3D holographic information is similar to the transmission known in radio engineering on one sideband with subtraction of the carrier frequency and the possibility of subsequent introduction of this frequency or any other carrier frequency at a distance from the holographic object. This method of transmission of 3D holographic information is applicable for problems of holographic TV and 3D augmented reality. Examples of the implementation of this technology in creating holographic images of a real 3D portrait of a person and transmitting it over WiFi are given. 3D images synthesized in the IR range are shown. This technology is easily adaptable to the tasks of integrating images of different parts of the spectrum of electromagnetic radiation. Possible applications of the method in 3D instrumentation are proposed.

The method of laser pulsed location as applied to the problem of detecting retroreflective objects, including optical and optoelectronic observation devices, is studied. By using the created specialized mobile hardware and software stand, the retroreflection indices of typical video recording devices under real conditions are experimentally determined. The effectiveness of using periodic illumination, frame accumulation, and formation of difference images for object detection under conditions of intense sunlight is demonstrated.

The result of scribing of silicon very large-scale integrated (VLSI) circuits in hybrid infrared photodetectors by laser radiation in an aqueous medium is studied. The width of the material damage around the scribe groove (approximately 47 microns) and the occurrence of a water hammer when water boils during scribing (exerting the pressure on the material equal to 1.5 x 10^-6 kg/ μm² or more) are determined.

A method of focused delivery of ultrasonic energy to a specified point inside a biological object using an annular antenna array is presented. A functional diagram of a multi-element annular array with alternating radiating and receiving elements is described. The channels of the radiating elements have controlled phase shifters, and all the receiving elements are connected to the adder. The possibility of focusing the ultrasonic energy with allowance for the wave propagation in two media is demonstrated by means of simulations of the annular antenna array operation. The result of focusing with considering the interface between the two media is estimated. It is assumed that the two media have different speeds of ultrasonic wave propagation. The presence of two media on the ultrasonic wave path leads to defocusing and shifting of the focus position.