Development of a fiber-optic system for testing instruments for monitoring nuclear power plants

The necessity of testing the equipment for monitoring the operation of nuclear power plants is justified. It is proposed to use optical fiber and pulsed laser radiation for these purposes. It is established that optical fiber is more resistant to radiation than other communication systems. The design of a fiber-optic emergency simulator is developed. The calculation of its characteristics is carried out. Their experimental research was carried out. It was found that with an optical signal delay of 98.6 microseconds, the loss is – 26 dB with an uneven frequency response of ± 2 dB. This makes it possible to test the entire set of equipment that uses optical signals used to control a nuclear power plant.

Applying fiber-optic system to control shaft torque

The article considers the procedure of torque control, which is very popular in a wide variety of industries with many design features. In marine power engineering the problems of determining the forces, torque on the shaft and power are solved by means of torsiometers with torque sensors. The most widely used torque sensors are of capacitive, induction, strain gauge and photoelectric types. It has been stated that there are limitations in the process of torque control due to the susceptibility of systems to the electromagnetic interference, lack of a high degree of protection for electrical equipment and necessary recalibration. Fiber optic systems have found application in torque measurement systems in the oil and gas and aerospace industries. The use of such systems on ships is more expensive in comparison with the technologies used today, for example, the systems based on strain gauges. It has been proposed to use an inexpensive optical measuring system based on the Pound-Drever-Hall technique with using a foil-clad strain gauge and an aluminum torsion rod. There has been illustrated the system of torque control, the phase graphs for the Fabry-Perot resonator and the graph of the resonator transmission spectrum are presented, the reflection coefficient value is given. A method for measuring the phase of a reflected beam from a Fabry-Perot resonator is being considered, the injection current of a laser is modulated by means of an electric oscillator to generate side stripes in the electric field of a laser beam. The carried out studies and calculations contribute to improving the reliability of the coastal power system; the possibility of their use in marine electrical systems has been proved.

Study of Rotational Motions Caused by Multiple Mining Blasts Recorded by Different Types of Rotational Seismometers

Digging two vertical shafts with the multiple blasts technique gave the opportunity to measure the induced angular motions in a horizontal plane with well-defined positions of sources. Three kinds of rotation rate sensors, sharing an underground location, were used. Two of them—a Fiber-Optic System for Rotational Events & phenomena Monitoring (FOSREM) and a prototypical seismometer housing the liquid-filled torus—sensed the rotation, while a microarray of two double-pendulum seismometers sensed both the rotation and symmetric strain. The FOSREM was sampled at 656.168 Hz, while all the others were only sampled at 100 Hz. There were considerable differences within the results gathered from the mining blasts, which should be attributed to two causes. The first one is the difference in principles of the operation and sampling rates of the devices used, while the other is the complex and spatially variable character of the studied wave fields. Additionally, we established that the liquid-filled sensor, due to its relatively low sensitivity, proved to be viable only during a registration of strong ground motions. Overall, a comparative study of three different rotational seismometers was performed during mining-induced strong ground motions with well-localized sources.

Fiber optic control system for geotechnical parameters of mine

In the article a fiber-optic method for monitoring rock pressure is considered, as well as the magnitude of the displacement of the layers of the stope hanging wall is measured. The authors analyze the applied rock pressure testing methods. The reasons for the need to create a safe system are given, the main requirement of which is the condition of compliance with all safety requirements during mining operations. The developed quasi-distributed fiber-optic system is capable of measuring with high accuracy changes in rock pressure and displacement of roof rocks in an explosive environment, also does not require expensive equipment associated with the use of a range of analyzers and reflectometers. A scheme has been proposed to simplify the testing process. The results of dependences of additional optical losses on the applied force are obtained

Метод обработки сигналов трехфазного PDV, устраняющий влияние ускорения на точность определения скорости

The interference method for determining the speed of objects using direct optical heterodyning (PDV-Photonic Doppler Velocimetry) has become widespread due to the simplicity of setting up the fiber-optic system, the unambiguousness of the results, and wide possibilities for varying the measurement accuracy and temporal resolution. The accuracy of speed measurement can be fractions of a percent, but there are a number of factors that prevent this. For example, a change in the speed of an object, that is, its movement with acceleration, leads to a broadening of the signal spectrum with an increase in the working time window and, as a consequence, to a decrease, rather than an increase in the accuracy of speed measurement. In this paper, we propose a method to compensate for the effect of acceleration on the accuracy of speed measurement. The proposed model for processing the registered signals makes it possible to determine both the acceleration and the speed of the object. The applied algorithm made it possible to avoid spectrum broadening with an increase in the time window and to increase the accuracy of measuring the speed of a freely falling body by an order of magnitude.