Comparison of Three Different Methods for Pile Integrity Testing on a Cylindrical Homogeneous Polyamide Specimen

Three different methods for pile integrity testing are proposed to compare on a cylindrical homogeneous polyamide specimen. The methods are low strain pile integrity testing, multichannel pile integrity testing and testing with a shaker system. Since the low strain pile integrity testing is well-established and standardized method, the results from it are used as a reference for other two methods

Electronic load as part of the test complex of the power processing unit of electric and plasma propulsion

This article provides the advantages and technical solutions for the use of electronic loads as part of a testing complex of power and management systems of electric and plasma propulsion of three types. The paper shows the parameters that were applied to select the electronic loads and describes their functionality

Surface inspection problems in thermoelectric testing

This paper demonstrates the outcome of experimental studies on thermoelectric characteristics of thermocouples. Measurements were carried out using different types of thermocouples; each studied alone then investigated when they are connected in parallel, in order to simulate the imperfect nature of the various multi-contact surface of the tested object. The investigated types were Chromel-Alumel and Nichrome-Constantan. The thermoelectric characteristics were measured at the temperature range 160°-400° Celsius, in order to identify the best operating temperature for the hot electrode. Furthermore, the load resistance is another important factor that has been investigated and therefore varied from 1[omega] to 10k[omega], in order to determine its effect on the electrical characteristics of thermocouples. Accordingly, these characteristics will help defining the requirements for an optimum thermoelectric testing

Simulation of Surface Oscillation of Ultrasound Sensor Based on Piezoelectric Semiconductor Transducer

In the article theoretical and experimental studies of the surface deformation of piezoelectric sensors are carried out. Round membrane was used as a model of piezoelectric sensors. Experimental studies were conducted on mass-produced sensors and self-made sensor. Good match fluctuations in membrane model with fixed edges real sensors is shown

Measurement error reducing in the ultrasound time-pulse systems

Ultrasound wave propagation in bounded media results in change of the echo-pulse shape, therefore the use of traditional method of determining of the propagation time of the ultrasound pulse based on use of threshold device (comparator) gives a large error of measurement. To reduce this error the new methods of the determining of echo-pulse propagation time are proposed in this paper. The first method is the method based on the use of two comparators, the second one is the method based on second-order polynomial approximation of the echo-pulse envelope. Analysis showed that the steeper the rising edge of the echo-pulse envelope, the less the error of determining of the pulse start time. The more the difference between comparator thresholds the less the error of determining of the pulse start time. Application of the method of two comparators gives two times systematic error reducing. Minimal sampling of input signal is determined for the method based on echo-pulse envelope. Dependence of the error at start echo-pulse determining on adjacent samples amplitude ratio is obtained. Application of echo-pulse envelope gives three times systematic error reducing

Measurement error reducing in the ultrasound time-pulse systems

Ultrasound wave propagation in bounded media results in change of the echo-pulse shape, therefore the use of traditional method of determining of the propagation time of the ultrasound pulse based on use of threshold device (comparator) gives a large error of measurement. To reduce this error the new methods of the determining of echo-pulse propagation time are proposed in this paper. The first method is the method based on the use of two comparators, the second one is the method based on second-order polynomial approximation of the echo-pulse envelope. Analysis showed that the steeper the rising edge of the echo-pulse envelope, the less the error of determining of the pulse start time. The more the difference between comparator thresholds the less the error of determining of the pulse start time. Application of the method of two comparators gives two times systematic error reducing. Minimal sampling of input signal is determined for the method based on echo-pulse envelope. Dependence of the error at start echo-pulse determining on adjacent samples amplitude ratio is obtained. Application of echo-pulse envelope gives three times systematic error reducing

The increase of ultrasound measurements accuracy with the use of two-frequency sounding

In the article the new method for detection of the temporary position of the received echo signal is considered. The method consists in successive emission of sounded impulses on two frequencies and also the current study is concerned with the analysis of ultrasound fluctuation propagation time to and from the deflector on every frequency. The detailed description of the mathematical tool is presented in the article. The math tool used allows the authors to decrease the measurement error with help of calculations needed

Optimization of frequency discretization for diagnostic information at diagnostics of technical objects

The block diagram of the monitoring device is presented. The operation principle of the monitoring device is described. The main units affecting the quality of the monitored signal reconstruction are shown. The analysis of the differentiating device and the voltage-controlled generator is carried out. The main characteristics of the differentiating device and the voltage-controlled oscillator are given and the quality of signal reconstruction is evaluated when their parameters change. The requirements for choosing the optimal value of the derivative time constant and the frequency range of the voltage-controlled generator are specified. A calculation example of the required RAM for recording and reconstruction of the monitored signal is shown

Automatic device for testing thermal resistance with thermoelectric effect

This paper presents the results of the developed device for testing thermal resistance of thermointerface. Experiments to determine thermal resistance in different cases of thermal interface application were carried out. Dependence of thermoEMF value is obtained, which occurs between semiconductor element body and cooling system radiator at different quality of thermal interface application