Summary
During the structural health monitoring of bridge structures, simultaneous noncontact determination of relative displacements in different points is preferred. The existing measurement displacement methods and systems used for bridge structures deprived of this ability or have the low accuracy and thus automation level that makes their usage for long‐term monitoring of bridge structure elements becomes impossible. To avoid the imperfections of existing methods and determining displacements simultaneously in different construction points, we proposed to use the laser spot tracking technology, in which the laser modules are mounted in certain points, and their rays are directed to the translucent screen of a recording device. After screen images recording and processing, one determines displacements of different spots formed by the laser modules on the translucent screen by specialized software. Potential opportunities for this technique are demonstrated during research of a concrete beam deflection in laboratory conditions. The errors of the proposed measurement algorithm were analyzed using computer simulation and laboratory study. The influence of laser modules and screen different spatial positions on the beam deflection measurement was also estimated. Practical application of the proposed system for underground crossing overlap vibration measurements has been showed. Based on the obtained data, several evaluations of its technical state and the residual bearing capacity of a reinforced concrete are made.
A modified spatial-temporal speckle correlation technique for operational assessment of structural changes in muscle tissues after slaughtering is considered. Coefficient of biological activity as a quantitative indicator of structural changes of biochemical processes in biological tissues is proposed. The experimental results have shown that this coefficient properly evaluates the biological activity of pig and chicken muscle tissue samples. Studying the degradation processes in muscle tissue during long-time storage in a refrigerator by measuring the spatial-temporal dynamics of biospeckle patterns is carried out. The reduction of the bioactivity level of refrigerated muscle tissue samples connected with the initiation of muscle fiber cracks and ruptures, reduction of sarcomeres, nuclei deformation, nuclear chromatin diminishing, and destruction of mitochondria is analyzed.
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