Absorption methods of control of technical condition of electrical insulation

The article provides an overview of the most common methods for monitoring the technical state of electrical insulation, based on the applying of absorption phenomena arising in dielectric materials under the influence of DC voltage. The main provisions of the control method based on determining the voltage at the electrodes of the investigated capacitive control object, which is recovering after a short-term discharge of its capacity, are described. The main aspects of the application of the polarization index and the absorption coefficient for determining the technical state of insulation by using the coefficients characterizing the change in time of the current through the dielectric when a constant test voltage is applied to it are analyzed. The advantages of using absorption methods for monitoring the technical state of electrical insulation, first of all, are the ability to carry out testing without the necessity of applying of relatively high test voltages, which greatly simplifies all the necessary technical operations. Such control methods show a significant dependence of the informative parameters used in them on the technical state of insulation on the degree of development of slow polarization processes in the material under study and, therefore, are successfully used to determine the degree of moisture in tested electrical insulation.

Requirements for the Procedure for Assessing the Operator’s Person When Processing Accelerometer Data

The article considers the possibility of biometric authentication based on gait parameters, which are obtained after intelligent processing of the accelerometer data of a wearable device. The article discusses the main trends and trends in the field of biometric authentication, as well as authentication by gait parameters. The developed neural network algorithm and informative parameters are described in the authentication procedure based on the data of a single sensor of a portable device. The practical verification of the proposed approach is carried out on 32 subjects of different physiology. The results of the study show the possibility of distinguishing their own movements in 100% of cases, and the distinction of the subjects is more than 90%. Also, the final part of the article provides the requirements for the authentication procedure when processing accelerometric data of gait biometrics, the level of trust of the developed algorithm is determined.

Wavelet Processing of Acoustic Emission of VT 1-0 Titanium Alloy under Tension

The paper proposes a method for processing acoustic emission signals for calculating informative signal parameters characterizing the stages of plastic deformation and fractures in a loaded titanium alloy. The proposed method has a complex structure that includes digital signal processing algorithms and multivariate data analysis methods. The acoustic emission signals are processed using the mathematical apparatus of the multilevel discrete wavelet transform to obtain the approximation coefficients of the 10-level decomposition. These coefficients characterize the low-frequency features of acoustic emission at various stages of samples loading. The approximation coefficients are further used as informative parameters of acoustic emission signals. Principal components analysis is used to investigate the informative parameters and establish their quantitative relationship with the stages of plastic deformation of titanium by clustering the processed results. Differences in the informative parameters at different stages of plastic deformation of the material are revealed by the following analysis of the clustered results. The obtained results can be used to develop a new generation of diagnostic devices for acoustic emission measurements.

Enhanced Feature Extraction Algorithms Using Oscillatory-Mode Pulsed Eddy Current Techniques for Aircraft Structure Inspection

A review of the existing literature shows that modern pulsed eddy current (PEC) technique for flaw detection in aircraft structure inspection is typically carried out in aperiodic mode. Аt the same time, the unstable characteristic points of the EC signal usually used as informative parameters can restrict the potential of this excitation mode due to significant measurement errors. This article considers an advanced PEC method of NDT based on the oscillatory mode. To obtain the conditions concerned with different modes of EC probe response oscillations, an equivalent scheme of the “testing object – EC probe” system was developed and analyzed. The frequency and attenuation coefficient of natural oscillations are proposed as the informative parameters of the probe signals. The obtained mathematical model of the probe signals allows for the dependence of proposed signal parameters on the characteristics of the testing object to be evaluated. Herein, we first develop algorithmic software for determining and analyzing the discrete amplitude and phase characteristics of PEC NDT signals based on the simulation results. The errors of the natural frequency oscillations and the attenuation coefficient determination as well as the optimal time for its determination are analyzed in order to minimize the possible errors. Next, the proposed informative parameters are experimentally investigated using a set of specimens. The obtained results confirm the possibility of the proposed methodology to enhance the inspection procedures related to the electrical conductivity and geometric parameters measurements as well as the detected defect sizing.

Qualimetric assessment of metrological characteristics of household gas meters during periodic verification

Informative parameters for statistical estimation of operational error of SAMGAS, METRIX, PREMAGAS household gas meters (HGM) are formulated. These are the values of the measured volume during the verification period of operation and the experimentally determined error of the meter during operation at three normalized flow rates: minimum, maximum and 20% of the maximum. Six ranges of variation of the HGM error at the minimum flow rate were selected to form statistical samples of meters. According to the proposed algorithm, the change in the weighted average HGM error for three normalized flow rates from the measured volume is quantified, taking into account the number of HGMs and their error ranges. It is proposed to apply the concept of generalized weighted average error of HGM, which reflects the operational error of HGMs during their operation in the entire range of consumption when measuring gas volumes up to 60 thousand cubic meters.

Assessment of the state of technical objects in the conditions of indistinguishability and the presence of non-deterministic metrological characteristics

В статье рассматривается проблема оценки прочности потенциально опасных систем техногенного характера в условиях недетерминированности метрологических характеристик и неразличимости информативных параметров такого метода диагностирования, как акустическая эмиссия. Приводится пример учета неразличимости и получения достоверных исходных данных для определения технического состояния объектов. The article deals with the problem of assessing the strength of potentially dangerous man-made systems under conditions of non-deterministic metrological characteristics and indistinguishability of informative parameters of such a diagnostic method as acoustic emission. An example of accounting for indistinguishability and obtaining reliable source data for determining the technical condition of objects is given.

The place of impulse oscillometry system in the diagnosis of early obstructive disorders associated with asthma

Asthma is one of the most common and socially significant human diseases. To date, spirometry is included in most recommendations as the gold standard for the diagnosis of obstructive disorders. However, in real clinical practice, this procedure does not always reveal signs of bronchial obstruction, not only in the early stages of the disease but also in more severe controlled bronchial asthma. Tests of oscillatory mechanics are increasingly being used to detect early violations of the pulmonary ventilation function. These tests are based on the forced oscillation technique, and the latest modification is impulse oscillometry system. The aim of this study was to investigate the capabilities of impulse oscillometry in diagnosing early changes in the function of the respiratory system in patients with asthma and identifying the most informative parameters of the method. Methods. A total of 146 patients with an established diagnosis of mild and moderate asthma were examined during remission. The patients were divided into 2 groups by the severity of asthma. The comparison group included 40 people with no signs of lung abnormalities. Results. Disorders of the pulmonary ventilation function were found in 23% of patients with asthma by spirometry, in 42% by bodypletismography in 42%, and in 72% of patients by impulse oscillometry. Impulse oscillometry system revealed obstructive changes localized in the central respiratory tract in 11% of patients, and obstruction of mixed localization was found in 6% of respondents. Peripheral respiratory tract disorders were diagnosed in 56 % of patients. Most respiratory tract lesions were located in the small bronchi in both groups. The obstructive disorders in large bronchi and generalized obstruction were observed more often in the 2nd group. Among impulse oscillometry parameters, the increase in Delta (Rrs5 – Rrs20) was most often recorded in both examined groups of patients with asthma. Conclusion. Compared to standard methods, impulse oscillometry system is more sensitive. Therefore, it has advantages in diagnosing respiratory system dysfunctions both in the early stages of asthma and in more severe cases during remission.