Comparative analysis of the structure and mechanical properties of welded joints of large-diameter pipes with wall thickness 30 mm produced commercially by submerged arc welding and by combination of ...the latter with hybrid laser-arc welding is performed. The results of impact tests and the data of fractographic studies are used to infer that that the combined welding process is more advantageous.
Waterflooding of low-permeable reservoirs with high pressure is often accompanied by formation of induced fracture. The positive side of this process is an injectivity increase and oil production ...rise. However, when these fractures approach producing wells, an early water breakthrough occurs, and high productivity channels are formed between the injection and producing wells. The technology of fracture clogging, for example, by suspension composition injection into an injection well, allows reducing the length of the fracture. The paper considers the problem of the fracture size reducing process on the waterflood sweep efficiency. The example of a reverse five–point waterflood pattern was investigated. In the basic calculation run, fracture length was constant during all process. The run with transformable fracture length is compared with the basic one. The results of calculations showed that the process of waterflooding after fracture impact could be divided into the following stages. The first one, which follows immediately after the fracture clogging, demonstrates a water cut decrease and an oil production rate increase. The second, in which the oil production declines below the base variant. On the third stage, there is a low, but long-term increase in oil production due to increased waterflood sweep efficiency. The authors established that monitoring of induced fractures length is relevant, since timely fractures clogging allows to increase oil production after the well treatment and to incline the oil recovery coefficient through increasing waterflood sweep efficiency.
The weld joints of pipes with a diameter of 1420 mm and a pipe-wall thickness of 30 mm manufactured by two different technologies have been studied. These technologies were (i) combining the laser ...arc welding when making a root weld with the subsequent submerged arc welding when applying cap welds and (ii) the method of double-sided submerged arc welding. It has been shown that the first technology leads to the formation of a bainite-based disperse structure in weld joints, thereby providing a tough-ductile character of fracture and an increased level of impact strength for different positions of a notch with respect to the center of a weld joint.
By using the methodology of computer engineering, we establish the regularities of the stress-strain state of the surface layer of Al
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–TiC ceramics with AlN and TiN coatings under the action of ...force loads.We determine the specific features of the influence of AlN and TiN coatings on the character of changes in the stress intensity on the surfaces of structural elements participating in the formation of the surface layer of Al
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–TiC-ceramics. The formation of microstructural stress concentrators on the boundaries of AlN and TiN coatings with the original ceramics is also detected.
The synchronicity between the extreme values of summer insolation in the northern hemisphere and the global climatic events of the Holocene is found. The transition from the cold Pleistocene to the ...warm Holocene epoch is synchronized with the summer irradiation maximum. The Little Ice Age is synchronized with the minimum of summer irradiation in the northern hemisphere. For the Holocene and Late Pleistocene, the leading role of climatic precession in changes in the global climate of the Earth has been determined. Accounting for variations in solar activity made it possible to detail the structure of the minimum irradiation of the northern hemisphere during the Little Ice Age. The necessity and possibility of simultaneously taking variations in incoming radiation of different physical nature associated with changes in the Earth’s orbital motion and changes in the activity of the Sun into account are shown in the reconstruction and forecasting of global climatic events.
Regularities of the influence of AlN and TiN coatings on the stress–strain state of the surface layer on Al
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–TiC ceramics structural elements under the influence of heat flow are established. ...The formation of microstructural stress concentrators at the boundary of AlN and TiN coatings with the initial ceramics is revealed.
The influence of AlN and TiN coatings on the stress–strain state of the surface layer on Al
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–TiC ceramics under the influence of a combined load is analyzed. The regularities of stress ...distribution and the location of microstructural stress concentrators forming the surface layer of this ceramic are established.
A modern technology for joining materials welding is commonly used in various industries. It is a process of interaction of thermal, mechanical and metallurgical properties and behaviors. Complex ...phenomena, such as solidification, microstructural changes and defect formation, have a great impact on the quality of welded joints. This article presents the results of studying the features of the austenite decomposition kinetics in the application of laser-hybrid welding technology, in a combination with multi-arc automatic submerged arc welding. The cooling rates are determined, affecting the change in properties of HAZ of welded joints on pipe steel of strength class K52. Using the dilatometric method, studies were conducted and thermo-kinetic and structural diagrams were constructed. Analysis of diagrams and microstructures showed that, as a result of the impact of the laser-hybrid welding process in the area of HAZ, the decomposition of austenite occurs mainly in the martensitic zone, followed by the formation of a bainite-perlite structure, due to recrystallization from the heat generated by the facing seams.
This paper summarizes the results of the seminar “Geopolitical Security of Russia: Remarks on the Problem Statement”, held on August 26, 2022, at the Immanuel Kant Baltic Federal University, ...Kaliningrad. During the seminar, the Institute of Geopolitical and Regional Studies of the university announced an initiative to devise a system of monitoring the geopolitical (regional) security of Russia. The debate centred around the development of a conceptual framework and a geopolitical security model as a prerequisite for the system. The discussion also covered other relevant issues, including the definition of geopolitical security and geopolitical space as well as the types of geopolitical threats and vulnerabilities. Another topic on the agenda was the analysis of theoretical approaches applicable to monitoring the geopolitical security in Russia. A constructivist approach based on discursive practices was viewed as the most promising for tracking changes in geopolitical threats. In this work, the emphasis should be placed on regional issues, i. e. the situation in particular regions. Other promising avenues for further research are the operationalization of relevant concepts and the development of a set of indicators of geopolitical threats and vulnerabilities, which Russia has already faced and may face in the future.
The culture of preimplantation embryos in vitro is an important method for human and mouse reproductive technology. This study aims to investigate the influence of different conditions of culture ...media on the preimplantation stage of mouse embryos cultured in vitro, and monitor the post-implantation development of new mice after embryo transfer to surrogate females. We demonstrated here that mouse embryos cultured in vitro in fresh M16, KSOM, Global, and HTF embryo culture media from one cell to the blastocyst stage and the subsequent embryo transfer to surrogate females are able to proceed through post-implantation development and, after birth, develop into healthy mice. However, culture of embryos in differently aged media shows various (often unpredictable) results. To find the optimal storage conditions of culture media, we suggest that the freezing and long-term storage of these media at − 80°C will not influence the quality of the media. To test this hypothesis, we grew embryos from one cell to blastocysts in vitro in the selected media after thawing and subsequently transferring them to surrogate females. Embryo culture in these four media after thawing does not affect preimplantation and postnatal mouse development. Thus, we have shown that storage of embryo culture media at low temperature (− 80°C) does not impact the quality of the media, and subsequently, it can be used for the culture of embryos for the full preimplantation period, the same as in fresh media.
