Volcanogenic Deposits of Non-ferrous Metals in the Lesser Caucasus and Eastern Pontides

The paper presents brief characteristics of geological environments of ore deposit occurrences in Turkey, Georgia and Armenia. They can be attributed to Kuroko-type deposits, being distinguished by the character of ore accumulation. To the west, in Turkey, there are epigenetic and hydrothermal-sedimentary copper-zinc deposits that were formed in deep restricted basinal settings. An example of the latter is the Chayeli deposit.To the east, in the Caucasus, we have predominantly only epigenetic deposits. Besides, in the Bolnisi mining district (Georgia) there is the Madneuli deposit which represents an example of polyformational deposit. Here, within the restricted territory, have been concentrated:barite, barite-polymetallic, gold-bearing secondary quartzite, large-scale stockworks of copper ores. Judged by the 87Sr/86Sr ratios, some volcanites which are spatially associated with ores, might have been products of the “differentiation” of undepleted mantle, or other magmas that were generated in the lower part of the earth crust.In the Alaverdi ore district in Armenia, there are Jurassic volcanodepressions that host copper, copper-zinc and barite-sulfide ores. All the deposits of the Alaverdi district, porphyry copper including, contain economic reserves of ores.On the basis of available literature material and our own data, there has been created a mental-logical geological-genetic model of volcanogenic deposits

Buckling Analysis and Stability of Compressed Low-Carbon Steel Rods in the Elastoplastic Region of Materials

[EN] This paper presents new approaches for solving a problem of the stability of compressed rods in the elastoplastic working region of materials. It is known that the columns of buildings, supports of engineering devices, drill rods of oil, and gas extraction industry may be subjected to significant risk of stability loss. Nowadays, there are design methods based on test results defining the relations (e.g., critical stresses-slenderness) to avoid this risk due to stability loss, but the precision and limits of definition are not always known. The main objectives of the study were to develop new approaches that would allow specifying the values of critical stresses of compressed elements beyond the proportional limit. The problem of stability of the compressed elements in the elastoplastic region was studied according to the stability theory. The authors suggested an original approach to the issue; in particular, the determination of values of the critical stresses and the finding of the points of the bifurcation were carried out by the tangent established by experimental results and by the approximation of the so-called double modulus. Comparative analysis showed the advantage of the proposed approach, particularly that the new critical curves were located below the curves of Engesser-Karman and Shanley and above the critical curves established by building codes. A new approach for the determination of critical stresses in the elastoplastic region was developed through which the structural reliability and economic efficiency was increased by almost 12% compared to the existing approaches.This research was financially supported by the Erasmus Mundus Action 2 Project Electra: Enhancing Learning in ENPI Countries through Clean Technologies and Research related Activities (project: ELEC1400294) and the Spanish Ministry of Economy and Competitiveness, along with FEDER funding (project: BIA2017-85098-R).Partskhaladze, G.; Mshvenieradze, I.; Medzmariashvili, E.; Chavleshvili, G.; Yepes, V.; Alcalá-González, J. (2019). Buckling Analysis and Stability of Compressed Low-Carbon Steel Rods in the Elastoplastic Region of Materials. Advances in Civil Engineering. 2019:1-9. https://doi.org/10.1155/2019/7601260S192019Braun, D. J. (2008). On the optimal shape of compressed rotating rod with shear and extensibility. 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