scholarly journals Technique for operational diagnosis of pipelines of energy systems and complexes

2021 ◽  
Vol 22 (6) ◽  
pp. 188-201
Author(s):  
R. Z. Shakurova ◽  
S. O. Gaponenko ◽  
A. E. Kondratiev
Keyword(s):  
Vibrational Energy ◽  
Experimental Studies ◽  
Low Frequency ◽  
Signal Amplitude ◽  
Piezoelectric Sensor ◽  
Technical Condition ◽  
Transform Method ◽  
Mathematical Mode ◽  
Operational Diagnosis ◽  
Develop Software

THE PURPOSE. To consider the problems of reliability of pipeline systems of housing and communal services. To analyze existing methods for assessing the technical condition of pipelines. To develop an improved technique that allows you to search for various types of defects in pipelines. To develop a device for inertial excitation of low-frequency diagnostic vibration vibrations. To develop software in the LabVIEW environment for collecting, storing and processing signals from a sensitive sensor (piezoelectric sensor) installed on a pipeline. To conduct a series of experimental studies to te st the proposed methodology. METHODS. The method of inertial excitation of vibrations was used to excite vibrations in the wall of the investigated pipeline. To search for the natural frequencies of vibrations of the pipeline under study, mathematical mode ling methods were used, implemented in the ANSYS software package. During the experiments, the fast Fourier transform method was used to process the signals coming from the piezoelectric sensor. RESULTS. The article presents a technique for assessing the t echnical condition of pipelines, as well as a device for inertial excitation of vibrations. The article presents the results of experimental studies on a fiberglass pipeline, the results showed that when an oscillatory wave passes through the wall of a defect-free pipeline, its amplitude changes insignificantly. If there is a defect in the wall of the investigated pipeline, the vibration amplitude will be much weaker due to the dissipation of vibrational energy in the place of the defect. Thereby, it is pos sible to determine not only the presence of a defect, but also its size by the degree of attenuation of the signal amplitude CONCLUSION. The proposed technique is the basis for the creation of a new measuring and diagnostic complex for vibration control of pipelines.

scholarly journals On the issue of inertial excitation of diagnostic low-frequency vibrations in pipelines of housing and communal services

2020 ◽  
Vol 216 ◽  
pp. 01079
Author(s):  
R Z Shakurova ◽  
S O. Gaponenko ◽  
A E. Kondratiev
Keyword(s):  
Experimental Studies ◽  
Low Frequency ◽  
Technical Condition ◽  
Main Attention ◽  
Pipeline Wall

The article discusses and analyzes issues related to the diagnosis of the technical condition of pipelines for housing and communal services. The main attention is paid to the inertial excitation of diagnostic low-frequency vibrations in the pipeline wall using the developed device. The results of experimental studies are presented.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

Transmission of Ultrasonic Waves Via Optical Silica Glass Fiber Doped by 7.5% of TiO2 with the Use of Power Sandwich Transducer

2011 ◽  
Vol 36 (1) ◽  
pp. 141-150 ◽  
Author(s):  
Sylwia Muc ◽  
Tadeusz Gudra
Keyword(s):  
Optical Fibre ◽  
Output Signal ◽  
Optical Waveguides ◽  
Experimental Studies ◽  
Signal Amplitude ◽  
Capacitive Sensor ◽  
Ultrasonic Waves ◽  
Sandwich Type ◽  
Type Transducer ◽  
Simultaneous Transmission

Abstract The possibility of acoustic wave propagation in optical waveguides creates new prospects for simultaneous transmission of laser beams and ultrasonic waves. Combined laser-ultrasonic technology could be useful in e.g. surgical treatment. The article presents the results of experimental studies of transmission of ultrasonic wave in optical fibres, the core of which is doped by 7.5% of TiO2, using a sandwich-type transducer. It also presents amplitude characteristics of an ultrasonic signal propagated in the optical fibre. Authors studied the effect which the length of the fibre has on the achieved output signal amplitudes. They presented the relation of the output signal amplitude from a capacitive sensor to the power applied to the sandwich-type transducer. The obtained results were compared with the results produced when using an optical fibre with a core doped by 3% of GeO2, in order to select optical fibre suitable for simultaneous transmission of ultrasonic waves and laser rays.

scholarly journals Water Level Sensing in a Steel Vessel Using A0 and Quasi-Scholte Waves

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Peng Guo ◽  
Bo Deng ◽  
Xiang Lan ◽  
Kaili Zhang ◽  
Hongyuan Li ◽  
...  
Keyword(s):  
Water Level ◽  
Guided Waves ◽  
Mode Conversion ◽  
Experimental Studies ◽  
Low Frequency ◽  
Steel Vessel ◽  
Theoretical Predictions ◽  
Travelling Time ◽  
The Comparative Study ◽  
Group Velocities

This paper presents a water level sensing method using guided waves of A0 and quasi-Scholte modes. Theoretical, numerical, and experimental studies are performed to investigate the properties of both the A0 and quasi-Scholte modes. The comparative study of dispersion curves reveals that the plate with one side in water supports a quasi-Scholte mode besides Lamb modes. In addition, group velocities of A0 and quasi-Scholte modes are different. It is also found that the low-frequency A0 mode propagating in a free plate can convert to the quasi-Scholte mode when the plate has one side in water. Based on the velocity difference and mode conversion, a water level sensing method is developed. For the proof of concept, a laboratory experiment using a pitch-catch configuration with two piezoelectric transducers is designed for sensing water level in a steel vessel. The experimental results show that the travelling time between the two transducers linearly increases with the increase of water level and agree well with the theoretical predictions.

An Approach to the Use of an External Magnetic Field As a Diagnostic Sign of an Asynchronous Motor Malfunction

2021 ◽  
Vol 64 (3) ◽  
pp. 18-23
Author(s):  
Ildar Yamansarin ◽  
◽  
Mikhail Salikov ◽  
Alexander Padeev ◽  
Dmitry Surkov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Short Circuit ◽  
Asynchronous Motor ◽  
Technical Condition ◽  
Stator Winding ◽  
Electric Motors ◽  
Transform Method ◽  
Fast Fourier Transform Method ◽  
Measurement Location

The article deals with the issues related to the possibility of diagnosing the technical condition of an asyn-chronous electric motor by an external magnetic field. The justification of the problems associated with the di-agnosis of electric motors is given. The difficulties that arise when measuring the external magnetic field of electric motors, as well as the devices with which it is possible to carry out measurements, are described. The re-lationship between the EMF of the sensor and the external magnetic field is shown. The results of processing the EMF waveforms induced by an external magnetic field in an inductive sensor for various electric motors are presented. The processing was carried out by the fast Fourier transform method. The external magnetic field contains the first harmonic and various harmonics that are multiples of the combination of the stator teeth, or the sum of the stator and rotor teeth that fall on one pair of poles. The ratio of the amplitudes of the first and tooth harmonics is affected by the measurement location and the orientation of the sensor. Diagrams showing the ratio of the main and tooth harmonics at different points of the motor body are constructed. The depend-ences of the harmonic amplitudes on the magnitude of the magnetizing current of the stator are given. Changes in the amplitudes and spectrum of harmonics in the presence and absence of an inter-turn short circuit in the stator winding are shown. Diagrams of the circular external magnetic field for the main and higher harmonics are constructed. The study shows the possibility of using an external magnetic field to detect inter-turn short circuits of the stator winding.

scholarly journals Ultra-Low Frequency Eccentric Pendulum-Based Electromagnetic Vibrational Energy Harvester

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1009
Author(s):  
Mingxue Li ◽  
Huichao Deng ◽  
Yufeng Zhang ◽  
Kexin Li ◽  
Shijie Huang ◽  
...  
Keyword(s):  
Low Power ◽  
Energy Harvester ◽  
Vibrational Energy ◽  
Low Frequency ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
Center Frequency ◽  
Vibration Energy ◽  
Outer Side ◽  
Working Frequency

With the development of low-power technology in electronic devices, the wireless sensor network shows great potential in applications in health tracing and ocean monitoring. These scenarios usually contain abundant low-frequency vibration energy, which can be collected through appropriate energy conversion architecture; thus, the common issue of limited battery life in wireless sensor devices could be solved. Traditional energy-converting structures such as the cantilever-beam type or spring-mass type have the problem of high working frequency. In this work, an eccentric pendulum-based electromagnetic vibration energy harvester is designed, analyzed, and verified with the finite element analysis method. The pendulum that contains alternative distributed magnets in the outer side works as a rotor and has the advantages of a simple structure and low center frequency. The structure size is well scalable, and the optimal output performance can be obtained by optimizing the coil thickness and width for a given diameter of the energy harvester. The simulation results show that the energy harvester could work in ultra-low frequencies of 0.2–3.0 Hz. A full-scale prototype of the energy harvester is manufactured and tested. The center working frequency is 2.0 Hz with an average output power of 8.37 mW, which has potential for application in driving low-power wireless sensor nodes.

On vibration isolation of sandwich plate with periodic hollow tube core

2017 ◽  
Vol 21 (3) ◽  
pp. 1119-1132 ◽  
Author(s):  
Gui-Lan Yu ◽  
Hong-Wei Miao
Keyword(s):  
Vibration Isolation ◽  
Sandwich Plate ◽  
Experimental Studies ◽  
Low Frequency ◽  
Dispersion Relations ◽  
Frequency Responses ◽  
Vibration Attenuation ◽  
Potential Applications ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The vibration isolation performance of a PC sandwich plate with periodic hollow tube core is investigated experimentally and numerically. The experiment results reveal that there exist vibration attenuation zones in acceleration frequency responses which can be improved by increasing the number of periods or tuning some structure parameters. The presence of soft fillers shifts the attenuation zone to lower frequencies and enhances the capability of vibration isolation to some extent. Dispersion relations and acceleration frequency responses are calculated by finite element method using COMSOL MULTIPHYSICS. The attenuation zones obtained by experiments fit well with that by simulations, and both are consistent with the band gap in dispersion relations. The numerical and experimental studies in the present paper show that this PC sandwich plate exhibits a good performance on vibration isolation in low frequency ranges, which will provide some useful references for relevant research and potential applications in vibration propagation manipulations.

scholarly journals MHD-waves in the geomagnetic tail: A review

10.12737/7168 ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 4-22 ◽  
Author(s):  
Анатолий Леонович ◽  
Anatoliy Leonovich ◽  
Виталий Мазур ◽  
Vitaliy Mazur ◽  
Даниил Козлов ◽  
...  
Keyword(s):  
Numerical Models ◽  
Experimental Studies ◽  
Low Frequency ◽  
Detailed Comparison ◽  
Mhd Waves ◽  
Theoretical Studies ◽  
Geomagnetic Tail ◽  
Magnetopause Oscillations ◽  
Experimental And Theoretical Studies ◽  
Theoretical Results

This article presents the review of experimental and theoretical studies on ultra-low-frequency MHD oscillations of the geomagnetic tail. We consider the Kelvin–Helmholtz instability at the magnetopause, oscillations with a discrete spectrum in the “magic frequencies” range, the ballooning instability of coupled Alfvén and slow magnetosonic waves, and “flapping” oscillations of the current sheet of the geomagnetic tail. Over the last decade, observations from THEMIS, CLUSTER and Double Star satellites have been of great importance for experimental studies. The use of several spacecraft allows us to study the structure of MHD oscillations with high spatial resolution. Due to this, we can make a detailed comparison between theoretical results and those obtained from multi-spacecraft studies. To make such comparisons in theoretical studies, in turn, we have to use the numerical models closest to the real magnetosphere.

scholarly journals Implementation of the Spectral Method for Determining of Measuring Instruments' Dynamic Characteristics

2020 ◽  
Vol 11 (2) ◽  
pp. 155-162
Author(s):  
A. F. Sabitov ◽  
I. A. Safina
Keyword(s):  
Dynamic Response ◽  
Spectral Method ◽  
Amplitude Spectrum ◽  
Low Frequency ◽  
Signal Amplitude ◽  
Measuring Instruments ◽  
Frequency Noise ◽  
Frequency Range ◽  
Calculated Amplitude ◽  
Zero Frequency

The spectral method for establishing dynamic response of measuring instruments basically requires determining the amplitude spectrum of the signal in its informative part that includes the amplitude spectrum at zero frequency. The operating frequency range of existing low-frequency spectrum analyzers is above zero frequency that leads to an uncertainty in dynamic response of measuring instruments determined by the spectral method. The purpose of this paper is to develop a program for calculating the signal amplitude spectrum, starting from zero frequency, to implement a spectral method for determining the dynamic response of measuring instruments on computers equipped with the MatLab package.To implement the spectral method for determining the dynamic response of measuring instruments, we developed a program in the MatLab 2013b environment that determines the signal amplitude spectrum from zero Hertz. The program reads the source data from Excel tables and presents the calculated amplitude spectrum as a chart and a report table.It is shown that the developed program calculates the signal amplitude spectrum with a standard deviation of not more than 3.4 % in the frequency range of 0 to 10 rad/s. The calculated amplitude spectrum allows determining the time constant of first-order aperiodic measuring instruments with an uncertainty of not more than 0.166 % at any noise level, if their frequencies are outside the information part of the spectrum.We demonstrated the claimed advantage of the spectral method for determining dynamic response using the developed program by the example of a high-frequency noise in the transient response of some measuring instruments.

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