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To explore the mechanical properties and failure modes of shale under stress conditions at different depths, the MTS 815 rock mechanics testing system was used to conduct acoustic emission tests on shale under conventional triaxial loading. The test results show that peak stress, peak axial strain, modulus of elasticity, and Poisson's ratio are proportional to the confining pressure in the shale compression test with 60° bedding angle. The theoretical value of rupture azimuth of 60° laminated shale used under Mohr-Coulomb criterion is near 62°, the experimental value is slightly larger than the theoretical value, and the whole fluctuates narrowly near 62°, and the rupture mode of shale is the shear damage along the weak face. The change of transverse strain coefficient of shale specimen is related to the expansion characteristic. At 10 MPa, the volume strain of specimen continues to increase, and the rock volume shrinks. At 60 MPa, the volume strain of specimen reaches - 0.31%, the rock volume expands. The larger the circumferential pressure is, the more significant the expansion characteristic of the specimen is. The number of shale acoustic emission localisation points has good consistency with the ringing count rate and energy rate. The total number of cumulative counts and localisation points show a decreasing trend with the increase of the enclosure pressure, and the maximum energy rate and cumulative energy decrease with the increase of the enclosure pressure. [ABSTRACT FROM AUTHOR]

This article proposes an analysis of the issue of spatial representation in Byzantine art. In the first part, we identify the reasons leading to the elimination of three-dimensionality effects in Byzantine imagery. The idea that Byzantine artists intentionally gave up three-dimensional representation is supported with arguments. Even though Byzantine art systematically rejected representing the third dimension, we can definitely discover certain ways of rendering spatiality. These methods are briefly analysed in the second part of this work.

This paper is focused on the hierarchical perspective, one of the methods for representing space that was used before the discovery of the Renaissance linear perspective. The hierarchical perspective has a more or less pronounced scientific character and its study offers us a clear image of the way the representatives of the cultures that developed it used to perceive the sensitive reality. This type of perspective is an original method of representing three-dimensional space on a flat surface, which characterises the art of Ancient Egypt and much of the art of the Middle Ages, being identified in the Eastern European Byzantine art, as well as in the Western European Pre-Romanesque and Romanesque art. At the same time, the hierarchical perspective is also present in naive painting and infantile drawing. Reminiscences of this method can be recognised also in the works of some precursors of the Italian Renaissance. The hierarchical perspective can be viewed as a subjective ranking criterion, according to which the elements are visually represented by taking into account their relevance within the image while perception is ignored. This paper aims to show how the main objective of the artists of those times was not to faithfully represent the objective reality, but rather to emphasize the essence of the world and its perennial aspects. This may represent a possible explanation for the refusal of perspective in the Egyptian, Romanesque and Byzantine painting, characterised by a marked two-dimensionality.