Search

Purpose The purpose of this paper is the development and study of capacitive coupling electrodes with the ability to monitor the quality of the skin–electrode contact in the process of electrocardiogram (ECG) diagnostics. The study’s scope embraces experimental identification of distortions contributed into the recorded ECG signal at various degrees of disturbance of the skin–electrode contact. Design/methodology/approach A capacitive coupling electrode is designed and manufactured. A large number of experiments was carried out to record ECG signals with different quality of the skin–electrode contact. Using spectral analysis, the characteristic distortions of the ECG signals in the event of contact disturbance are revealed. Findings It was found that the violation of the skin–electrode contact leads to significant deterioration in the recorded signal. In this case, the most severe distortions appear with various violations of the skin–electrode contact of two sensors in one lead. It has been experimentally shown that the developed sensor allows monitoring the quality of the contact, and therefore, improvement of the quality of signal registration, enabled by the use of bespoke processing algorithms. Practical implications These sensors will be used in personalized medicine devices and tele-ECG devices. Originality/value In this work, authors studied the effect of the skin–electrode contact of a capacitive electrode with the body on the quality of the recorded ECG signal. Based on the studies, the necessity of monitoring contact was shown to improve the quality of diagnostics provided by personalized medicine devices; the capacitive sensor with contact feedback was developed.

A state-of-the-art telemedical development including a portable electrocardiograph ECG Express and a web-based program for remote monitoring of the ECG is described. This article presents the key diagnostic features of the ECG Express cardiograph. Techniques for ECG monitoring using the “doctor–patient” telemedicine model as proposed for regular monitoring of patients’ ECG and sending data to a server for further interpretation by the treating doctor are described.

The results of the development of a high-frequency pumping source for active media on self-terminating transitions in metal vapors, which allows operation in the mode of a low energy deposition into the discharge, are presented. Reduced energy deposition into the discharge is provided due to the pumping of the active medium with short-duration high-voltage pulse (3 kV, 15 А, 40–60 ns). A record-high radiation-pulse repetition rate of 200 kHz in the active medium of copper bromide vapors was obtained when operating in the superradiance mode.

The milestones in the development of researches connected with metal vapor lasers, which have been carried out at V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, since its first days are considered. Some of the most interesting fundamental and applied results are presented. A fairly extensive list of related works, published mainly in the past twenty years, is given.

This paper addresses the theoretical study of the spatio-temporal gain profile of the copper vapor active media. The description of a kinetic model of a copper vapor amplifier which allows us to study spatio-temporal evolution of the amplifying characteristics is described. Using the kinetic model time and radial evolution of the medium optical gain and factors which governs the radial gain profile inhomogeneity of the brightness amplifier are shown.

Amplifying characteristics of the copper bromide vapor active media with the increased inversion duration are studied using the detailed kinetic modeling. The analysis of the gain radial profile and its time evolution at various points of the GDT profile is presented. The results show the possibility of application such active media to the tasks of the remote object visualization.

The results of the operation of a capacitive pumped CuBr laser in a reduced energy deposition mode are presented. A high radiation-pulse repetition rate of 100 kHz in the active medium of copper bromide vapors was obtained. The results of OrCAD simulation of the high-frequency metal vapor active media pumping source with capacitive pumping are presented.

Due to their unique radiation properties, metal vapor lasers find a variety of applications, including being used as a high- brightness amplifier in new active optical systems. This type of systems has been actively developed in recent years and is applied for visual control of fast processes in screening the background illuminations. A computer model is built and applied to an existing laser source allowing to determine the radial distribution of gas temperature in the cross section of the laser tube. Computations are performed using a preset qualitative type radial distribution of the electric power supplied to the gas discharge. The influence of the electric power supplied to the gas discharge and the wall temperature on the thermal resistance of the gas discharge was evaluated by means of computer simulations. The proposed methodology allows the planning of experiments and developing new laser sources with improved output characteristics.

Results of the experimental study of two high-frequency active elements of different sizes of a CuBr laser operating in the generator, single-pass amplification, and superradiance modes are presented. A pulse repetition rate of 195 kHz is attained for the first time in the supperradiance mode. Using the method of express estimation of the radial profile, it is shown that the gain profile does not change significantly throughout a wide pulse repetition rate range (up to 195 kHz) in the case of a small-diameter active element.

A spatiotemporal kinetics of the active medium of a copper vapor brightness amplifier is described that allows gain characteristics to be investigated during the pump pulse. Model calculations show that changing the discharge parameters allows the radial gain profiles to be improved significantly, as well as the gain and the inversion duration to be increased. The data obtained will be used to choose the operating conditions for the active medium in the brightness amplifier mode.

This paper addresses the experimental study of the beam profile of the CuBr brightness amplifier operating at a wide range of pulse repetition frequencies. The use of a medium-size gas discharge tube (2 cm) ensures the operation of the brightness amplifier both at typical PRFs (520 kHz) and at higher PRFs (up to 100 kHz), either with or without HBr additive. The effect of the active additive on the beam profile is demonstrated. The testing results on kinetic modeling of radial processes in the laser (brightness amplifier) plasma are also discussed.

This paper presents the stages of development of the device registration and processing of the EMG signal, the structural and schematic diagram of the device and the PCB of the device. The experimental results of testing the device in the form of oscillograms of EMG signals and control pulse signals that control the operation of the prototype bionic prosthetic hand are also presented.

The paper presents a laser monitor with 10 μs time-resolution based on a high-frequency copper bromide vapor brightness amplifier. A sync circuit has been designed for single-pulse imaging. The analysis of amplifying characteristics of the active elements and active optical system (laser monitor) parameters allowed to determine the optimal concentration of HBr at which the images can be obtained with minimum distortions. For the active element operating at high frequencies (more than 50 kHz) as a brightness amplifier, the concentration of HBr must be lower than that needed for obtaining the maximum output power. The limiting brightness temperature of the background radiation which does not affect the image quality is determined. The potential feasibility of using a proposed brightness amplifier for visualizing processes blocked from viewing by the background radiation with the brightness temperature up to 8000 K is demonstrated.

The imaging results of different processes blocked from the observation by the intense background light are presented in this paper. Active optical systems based on high-frequency brightness amplifier are used to decrease the negative factor of the glare. The experimental and modeling results on obtaining high pulse repetition frequencies (PRF) (more than 100 kHz) of copper bromide vapor brightness amplifiers operating in a low input energy mode are shown. The use of metal vapor brightness amplifiers for visual non-destructive testing of fast processes obscured by the glare is also discussed. It has been shown that the imaging method proposed in this paper proves to be the most reliable to obtain the information about objects or processes in a real time mode using high PRF CuBr active media.

We have considered the application of a new method of pumping of active media on metal vapors by a combined weak-current discharge. A distinguishing feature of a weak-current discharge compared to the method for the traditional pumping of self-contained lasers is the regime of lower energy input to the discharge. Using this regime, it is possible to realize a pulsed-periodic form of the discharge with laser pulses of various shapes and durations at low current amplitudes (several amperes). Additional pulsed-periodic discharge is used to heat the active zone.

Digital components of modern physical systems are often designed applying circuitry solutions based on the field programmable gate array technology (FPGA). Such (embedded) digital components should be carefully tested. In this paper, an approach for the verification of digital physical system components based on mutation testing is proposed. The reference description of the behavior of a digital component in the hardware description language (HDL) is mutated by introducing into it the most probable errors and, unlike mutants in high-level programming languages, the corresponding test case is effectively derived based on a comparison of special scalable representations of the specification and the constructed mutant using various logic synthesis and verification systems.

We present data on the development and application of an image-brightness amplifier based on copper bromide vapor intended for the visualization of objects occurring at distances above 5 m from the detecting equipment. An increase in the superradiance (gain) pulse duration was achieved by decreasing the repetition frequency of pumping pulses (to 3 kHz) and increasing the capacitance of the capacitor bank (up to 3.4 nF) so as to increase the deposited pulse energy. The basic possibility of creating active optical systems with brightness amplifiers (laser monitors) for the visualization of objects and processes occurring at large distances from a registration system is demonstrated.

This paper presents the theoretical study of the optical gain of copper vapor active media for a wide range of input signal power. The modified kinetic model is used to identify the effect of the optical saturation on the amplified spontaneous emission and the spatio-temporal evolution of amplifying characteristics. Also, the dependence of these characteristics on the copper concentration is studied. The results obtained are discussed in the context of using copper vapor active media in laser monitors.

We used an active optical system referred to as ‘laser monitor’ based on a copper bromide vapor brightness amplifier for imaging a diamond crystal surface during its synthesis in a microwave plasma in CH4-H2 gas mixture. The approach allows observation of an entire crystal without interrupting the chemical vapor deposition process. It is demonstrated that the broadband plasma background radiation with the brightness temperature of about 3000 K does not interfere with object real-time monitoring at the laser wavelength of 510.6 nm. High quality images obtained using both passive (laser illumination) and active (laser monitor) methods provide information about the surface relief of the growing crystal with resolution of a few tens of micrometer. Each frame is formed through one pulse (about 30 ns), with the maximum frame rate being 20,000 frames/sec.

The paper presents experimental results on obtaining high pulse repetition frequencies of radiation/gain in copper bromide vapor active media. Also the results of experimental and theoretical studies of radial profiles of radiation and amplification of such media at raised pump pulse frequencies are given.

The results of the development of the high-frequency metal vapor active media power supply are presented. The results of OrCAD simulation of the processes that occur in the power supply are described. The results of the simulation and experiment for the resistive load operation mode were compared.

The paper presents the results of the experimental study of a copper bromide vapor active medium operation in the amplified spontaneous emission (ASE) mode with the pulse repetition frequency (PRF) up to 200 kHz. The oscillograms of the active medium radiation pulse at various frequencies in a generator (lasing) mode, single-pass amplification mode and ASE are presented. The possibility to use active media on self-terminating transitions as brightness amplifiers at PRFs higher than 100 kHz has been shown.

International audience; Computationally constrained devices are devices with typically low resources / computational power built for specific tasks. At the same time, recent advances in machine learning, e.g., deep learning or hierarchical or cascade compositions of machines, that allow to accurately predict / classify some values of interest such as quality, trust, etc., require high computational power. Often, such complicated machine learning configurations are possible due to advances in processing units, e.g., Graphical Processing Units (GPUs). Computationally constrained devices can also benefit from such advances and an immediate question arises: how? This paper is devoted to reply the stated question. Our approach proposes to use scalable representations of ‘trained' models through the synthesis of logic circuits. Furthermore, we showcase how a cascade machine learning composition can be achieved by using ‘traditional' digital electronic devices. To validate our approach, we present a set of prelimin ary experimental studies that show how different circuit apparatus clearly outperform (in terms of processing speed and resource consumption) current machine learning software implementations

Experimental and computer studies of the CuBr laser with periodic-pulse pumping are performed with and without addition of HBr. The analysis based on the numerical simulation reveals how additions improve the lasing characteristics of this laser at both typical (10 to 20 kHz) and higher (up to 100 kHz) excitation pulse repetition frequencies during the operation with a low energy deposition in the discharge. This allows the lasing pulse repetition frequency to be increased in the experiment to 750 kHz, which does not seem to be a limit as yet.

A prototype of a bistatic laser projection system employing copper bromide vapor based active media is presented that allows remote objects and high-speed processes to be monitored online. The proposed scheme employs two active elements: one in the source for lighting the object and another in the image brightness amplifier.

This paper considers the issue how to obtain the amplification of stimulated emission in the cell with sodium vapor using a longitudinally pumped dye laser arrangement at a line shorter than the transitions from the ground state to the levels D 1 and D 2 . The broadening of the emission wavelength is calculated.

In the article a description of robot-equipped manipulator functionally and outwardly similar with human hand is introduced.

In this paper, the experimental studies of copper bromide vapor brightness amplifiers operating at high pulse repetition frequencies are presented. The obtained results show that the injection of active hydrogen-containing additives allows to increase the radiation (gain) pulse repetition frequency in active elements with a diameter of the active zone larger than 1 cm.

This paper presents actual development in the field of personal telemedicine. For personal cardiographs most suitable dry electrodes that do not require a conductive gel. This article describes experiments with capacitive electrodes from Plessey Semiconductors. On the basis of the obtained experimental data, it is planned to create own capacitive electrodes with the possibility of detuning from the skin-electrode contact.

In this paper the circuits of high frequency trigger generators of pulses of the nanosecond duration are presented. A detailed study of a generator based on the avalanche transistor with the use of a coaxial cable instead of a capacitor is described. This circuit showed advanced characteristics of the output pulses. A circuit of a generator built on high-speed digital components is also considered. The basic advantages and disadvantages of both generators are presented in this paper.

A series of experiments by air purification on fibrous filtering nozzles was made. It is experimentally shown that the fibrous filter can operate in a wide rate range. The degree of trapping of fine aerosols of glass was 99 % at a linear rate of 0.01 m/s. the degree of capture decreased to 85 % at the increasing of filtration rate up to 0.06 m/s. Dustiness of the air ranged from 3 to 5 g/m{3} at the course of the experiment. Hydraulic resistance changed from 5 to 25 mm of water column. The calculated data of resistance and falling of pressure on fibrous filters are given; these data were received on the equations from various sources in comparison with experimentally obtained data. According to the results of series of experiments the amendment of the well-known Fuchsian equation is calculated for calculation of the resistance of fibrous air filter. This amendment considers a form and defects of surface of the fibers received by centrifugal-spinneret method.

In this paper the feasibility of using metal vapor lasers for visual and optical monitoring of fast processes is discussed. The theoretical calculations consistent with the experimental study have been performed. The possibility of visualizing objects with pulse repetition frequency of the brightness amplifier up to 60 kHz has been demonstrated. The visualization results of the corona discharge are also given.

Kinetic processes in the active medium of the copper bromide vapor laser with hydrogen additives are described in detail. Mechanisms for improvement of its lasing characteristics by hydrogen additives are analyzed.

The operation of a CuBr laser in an excitation pulse train mode has been investigated. The experimental data obtained allow one to determine the characteristic time for which copper atoms are lost by the active medium of the laser. The analysis performed based on a numerical simulation of the laser operation has shown that the copper atoms are lost in the processes of reduction of CuBr molecules due to reactions of interaction of copper atoms with bromine ions. The predicted time for which copper atoms are lost by the laser active medium (150 μs) is in good agreement with the experimental one.

A method to calculate the prepulse concentrations of the CuBr molecules in the active medium of a CuBr laser is proposed. A comparison with the available experimental data is presented.

The kinetic model of a copper vapor laser operating in a low input energy mode is presented. The modelling results demonstrate the possibility of producing generation in this type of lasers at high frequencies.

This work describes the hardware-software complex that is used in educational process for students of technical specialties to study the principles of design and software implementation of digital filters. Paper describes a programming part of the complex which allows calculating the coefficients of different digital filters. The possibility to transfer these coefficients to the microcontroller using UART interface is presented. The hardware part of the complex is presented by signal generators with different shape of signals (triangle signal with variable frequency, sinusoidal signal with variable frequency, sinusoidal signal with addition of noise). Experimental results of practical implementation of designed complex using STM32F4DISCOVERY board based on STM32F407 microcontroller are shown in the paper.

The results of the experimental study of a copper bromide vapour laser at high repetition rates of regular pump pulses are presented. A record-high pulse repetition rate of 700 kHz is attained for lasing at self-terminating transitions in copper atoms. To analyse the obtained results, use is made of the data of numerical modelling of the plasma kinetics in the phase of pumping and discharge afterglow.

The research focuses on a pure-tone audiometer designing. The relevance of the study is proved by high incidence of an auditory analyser in older people and children. At first, the article provides information about subjective and objective audiometry methods. Secondly, we offer block-diagram and basic-circuit arrangement of device. We decided to base on STM32F407VG microcontroller and use digital pot in the function of attenuator. Third, we implemented microcontroller and PC connection. C programming language is used for microcontroller's program and PC's interface. Fourthly, we created the pure-tone audiometer prototype. In the future, we will implement the objective method ASSR in addition to pure-tone audiometry.

In this work control system for Peltier element air dryer is shown. The block diagram of an air dryer and schematic diagram of a control system are presented.

A single-pulse imaging laser projection system (laser monitor) is proposed for real-time monitoring high-speed processes shielded by the intensive background lighting. The brightness temperature of the lighting can reach thousands or even tens of thousands of degrees, which makes it difficult to observe the processes with the naked eye. The estimates of limiting temperatures show that the use of the proposed instrument allows to view the objects when the equivalent brightness temperature of the background lighting is up to 45 000 K. The results of visualization of some bright objects and processes using high-speed copper bromide vapor laser monitor are presented.

The modification of a power supply circuit used for pumping metal vapor lasers is analyzed. The results of OrCAD simulation of the processes that occur in the power supply are presented. The effect of the capacitance ratio on the charging process of a storage capacitor is described. The mode which provides more time for the recovery of the thyratron is discussed. The results of the development of the small-size high pulse repetition frequency laser with up to 3 W average output power are presented.

The paper discusses the use of a CuBr-laser active medium for visualization of high speed-processes obscured by background light. The methods of laser illumination and laser monitor are suggested.

The paper presents the results of the study of solid-state power supply units for pumping CuBr-lasers of various geometry. The possibility of developing solid-state high-frequency (>100 kHz) power supply units is demonstrated, and the results of simulation and breadboarding of solid-state high-voltage power supply units for pumping CuBr-lasers are discussed.

The paper presents state of the art for laser projection microscopes and their application for monitoring objects and processes hidden from view of an observer by a layer of bright luminous plasma. We show the possibility of registration of an image, which is obtained using laser projection microscope and is formed by a single pulse of the optical amplifier. Laser monitor based on CuBr-laser with a frame-by-frame imaging has been used for the first time. The paper presents the results of visualization of the process of self-propagating high-temperature synthesis, which is attended by intense stray lighting in real-time mode using synchronizing system of an optical amplifier and a highspeed camera.