Measurement of Rotational Events in Regions Prone to Seismicity: A Review

On the basis of the explanation of rotational seismology as an area of study, a modern approach to the seismic rotation in various continuum models is summarized. The aim of this chapter is to formulate the fundamental requirements for rotational seismometer. Consequently, a review of all existing technologies of rotational seismometers including mechanical, electrochemical, magnetohydrodynamical, as well as optical type solutions is discussed. The analysis of their parameters that considers technical requirements enforced by rotational seismology has indicated an optical instrument using a Sagnac interferometer as the best solution. Fibre-Optic System for Rotational Events & phenomena Monitoring (FOSREM) with its main parameters and features is described as an example of such solution. Moreover, the example of rotational events recorded in Książ observatory, Poland, using mechanical rotational seismometers and FOSREM is presented. There are data for M = 3.8 earthquake near Jarocin, Poland on the 2012.01.06 at 15:37:56 at a distance of about 200 km from Książ. Although the used devices have totally different designs, the results obtained using FOSREM and the results calculated by mechanical devices show compatibility in rotational signals

Detector diode circuit noise measurement and power supply method selection for the fiber optic seismograph

This paper investigates the noise levels present at various points in the FOSREM type fiber optic seismograph. The main aim of this research was to discover magnitudes of noise, introduced by various components of the analog and optical circuits of the device. First, the noise present in the electronic circuit without any optics connected is measured. Further experiments show noise levels including the detector diode not illuminated and illuminated. Additional tests were carried out to prove the necessity of analog circuitry shielding. All measurements were repeated using three powering scenarios which investigated the influence of power supply selection on noise. The results show that the electronic components provide a sufficient margin for the use of an even more precise detector diode. The total noise density of the whole device is lower than 4⋅10⁻⁷ rad/(s√Hz). The use of a dedicated Insulating Power Converter as a power supply shows possible advantages, but further experiments should be conducted to provide explicit thermic confirmation of these gains

Innovative Fibre-Optic Rotational Seismograph

Construction, laboratory tests as well as the first field application of a new fibre-optic rotational seismograph is presented. The system based on fibre-optic gyroscope (FOG) with measured Angle Random Walk on range 10−8 rad/Sqrt(s) and a few rad/s maximum detectable amplitude of rotation in frequency range from DC to 328.12 Hz designed it for rotational seismology area of interest. This work presents also exemplary relevant measurements which were conducted using two seismographs in the geophysical observatory in Książ region, Poland

Some problems of slide bearing material fatigue evaluation

A slide bearing alloy resistance against fatigue failures have been investigated for three different lubricants, different heat loadings and different stress ratio K values. The research methods and data handling procedures for determination of particular parameter effects on fatigue strength have been described and analysed for experiments that were set and performed in laboratory tester SKMR-2. Main and interaction effects of lubricant and stress ratio factors on bearing material fatigue strength have been analysed. Design scheme of the SKMR-2 head unit, Standard tested half-bearing, fatigue failures on the surface of the specimen, cross-section through the damaged surface layer of the specimen, fatigue limit stress amplitude vs. temperature and kind of oil, main effect of stress ratio, main effects of temperature and oil are illustrated in the paper. Main conclusions are cover in statements that fatigue strength of the bearing material is affected, to the highest degree, by the mechanical stress value and stress ratio and resistance to the fatigue cracks is being reduced for higher tensional stress, increase in temperature is resulting in decreasing of the fatigue strength rating values, fatigue strength of the slide layer is considerably dependent on the type of the used lubricant interactions of the type of the lubricants, their temperatures, loading stress ratio have been noticed

INVESTIGATION OF THE IC ENGINE LUBRICATING OIL EFFECTS ON JOURNAL BEARING LIFE1

Abstract. In the paper the results of IC Engine sliding bearing lining fatigue strength experimental investigations are presented. In particular the effects of the lubricating oil type have been considered

Development of Three-Axis Fibre-Optic Seismograph for Direct and Autonomous Monitoring of Rotational Events with Perspective of Historical Review

The paper presents historical perspective of fibre-optic seismographs designed and constructed at the Institute of Applied Physics at Military University of Technology, Poland based on the so-called minimum configuration of fibre-optic gyroscope. The briefly presented history, which originated in the 1998 by the system named GS-13P, laid solid foundations for the construction of a three-axis fibre-optic seismograph. The presented system meets all technical requirements of rotational seismology in terms of measurement parameters (measuring range from 10−8 rad/s to several rad/s and frequency from 0.01 Hz to 100 Hz) and utility features (mobility, autonomy, power independence, environmental stability). The presented device provides universal application both for research in engineering applications (high buildings, chimneys, wind towers) as well as in seismological research