bluuebunny/crossref_metadata_2025 huggingface dataset:
Preserving Low-Quality Video through Deep Learning
Authors: Galteri Leonardo , Seidenari Lorenzo , Uricchio Tiberio , Bertini Marco , Del Bimbo Alberto
Published: November 2020

Lossy video stream compression is performed to reduce the bandwidth and storage requirements. Moreover also image compression is a need that arises in many circumstances.It is often the case that older archive are stored at low resolution and with a compression rate suitable for the technology available at the time the video was created. Unfortunately, lossy compression algorithms cause artifact. Such artifacts, usually damage higher frequency details also adding noise or novel image patterns. There are several issues with this phenomenon. Low-quality images can be less pleasant to persons. Object detectors algorithms may have their performance reduced. As a result, given a perturbed version of it, we aim at removing such artifacts to recover the original image. To obtain that, one should reverse the compression process through a complicated non-linear image transformation. We propose a deep neural network able to improve image quality. We show that this model can be optimized either traditionally, directly optimizing an image similarity loss (SSIM), or using a generative adversarial approach (GAN). Our restored images have more photorealistic details with respect to traditional image enhancement networks. Our training procedure based on sub-patches is novel. Moreover, we propose novel testing protocol to evaluate restored images quantitatively. Differently from previously proposed approaches we are able to remove artifacts generated at any quality by inferring the image quality directly from data. Human evaluation and quantitative experiments in object detection show that our GAN generates images with finer consistent details and these details make a difference both for machines and humans.
Interpretation of archaeological data based on direct and remote retrieval of information
Authors: Fiorillo F , Galli S , Rossi C
Published: November 2020

This paper focuses on the archaeological and architectural analysis of the Late Roman settlement of Umm al-Dabadib (Kharga Oasis, Egypt). The available information on the archaeological remains of this site includes on-site hand-made sketches, photographs, 3D surveys. The final aim of this specific research is the interpretation and reconstruction of the historical context of this site by combining sources of different nature. This paper presents the methodology employed to elaborate the 3D data in order to achieve a digital restitution of the archaeological map of the entire settlement, which covers an area of about one hectare. The starting point was the elaboration of the close-range photogrammetric survey of the Fortified Settlement that allowed the creation of a 3D point cloud of the whole area, based on the elaboration of over 5,000 photographs, from which a complete and detailed metric model was derived. This 3D model played a key role to extract metric information and to reconstruct the geometrical structure of the settlement, but this result could only be achieved thanks to the successful combination of the digital data with the hand-made sketches and the pictures taken in situ in the recent past. This paper represents an outcome of the project LIFE (Living In a Fringe Environment), funded by the ERC CoGrant 681673.
Bacterial mineralization of calcium carbonate for conservation of stone artworks
Authors: Perito Brunella , Marvasi Massimiliano , Mastromei Giorgio
Published: November 2020

Calcareous stones have been widely used as artwork and building materials by human civilizations, especially in the Mediterranean Basin. Calcareous stone deterioration is a consequence of the weathering action of physical, chemical and biological factors, which causes a progressive dissolution of the mineral matrix and an increase in porosity, resulting in the weakening of the structure. Recently, increased environmental pollution and global warming are threatening stone cultural heritage more than ever. Inorganic or organic products have been using to slow down monument deterioration, but their use presents several drawbacks. Bacterial Calcium Carbonate Mineralization is a natural process widespread among bacteria and occurring in different environments. In the last decades it has been proposed as a new and environmentally friendly tool in conservation of monumental and ornamental calcareous stones. The aim is to develop a bacteria-mediated mineralization treatment providing a coherent calcium carbonate layer on the surface of deteriorated stone, able to protect it against the intake of water and chemicals and to consolidate the inner weakening structure. The advantage is to obtain a mineral product similar to the calcareous stone substrate, mimicking the natural process responsible for stone formation. This review introduces the mechanisms of bacterial mineralization and describes the current strategies based on this process to promote stone reinforcement in field tests. They include applications of selected bacterial strains and/or culture media as well as selected components of bacterial cells on stone. The review finally provides perspectives based on recent advances.
Dynamical and structural analysis of a Bronze Age war chariot
Authors: Mazzù A , Uberti S , Bodini I
Published: November 2020

The introduction of two-wheel chariots, pulled by horses, was a key technological innovation in the Bronze Age. Archaeological evidences, found in Northern Africa, Europe and Asia, allowed identifying various chariot typologies and understanding their main features. However, many questions about the function of single pieces and the behavior of the vehicles are still open. In a previous work, a war chariot wheel, found in northern Italy and known as the “Mercurago wheel”, was studied with an engineering approach. In this paper, the whole vehicle, to which the wheel was hypothesized to belong, was studied. In particular, two chariot typologies, differing mainly for the axle position, were analyzed. The stiffness of the various chariot parts were characterized by means of static finite element analyses. These data were subsequently used as input parameters in running multibody dynamics simulations. Finite element dynamical simulations were carried out as well. The analyses results allowed determining the crucial effect of some parts, particularly the cockpit floor, in favoring the passenger stability in dangerous conditions, such as bumping. The effect of the axle position on the passenger and wheel trajectory were evaluated as well.
Study and 3D survey of the Roman baths in the archaeological site of Lylibaeum (Marsala, Italy)
Authors: Ebolese Donatella , Lo Brutto Mauro
Published: November 2020

Archaeological documentation is a fundamental step for research and conservation planning phases. Nowadays traditional recording is always supported by geomatics technologies which offer important support to the growth of archaeological study. The integration of sensors and methodologies seems to give the best results, in terms of time, costs and accuracy of products. In particular, the combination of Terrestrial Laser Scanner (TLS) and Unmanned Aerial Vehicle (UAV) can help the documentation of complex sites and the production of 3D and 2D products for different purposes. The paper focuses on the integration of TLS and UAV methodologies to record the thermal baths of the Roman Domus in the archaeological Park of Lylibaeum (Marsala, Italy). The combination of range and image data are useful to achieve a complete 3D model and a high-resolution orthophoto of the site, in order to provide accurate and complete documentation for archaeological research and conservative project.
Geomatics techniques for the 3D survey of the Arno River to support hydraulic studies
Authors: Aminti P , Bonora V , Corongiu M , Mugnai F , Parisi E I , Tucci G
Published: November 2020

This paper presents the geomatic contribution to the hydrographical survey applied to the Arno River in Tuscany (Italy) that has been performed to obtain both underwater cross-sections as well as riverbank height using point cloud data from echo-sounder and terrestrial laser scanner so that water flow storage capability could be further estimated with high accuracy. The control network and ground control points design, measurement and adjustment are presented, describing the solutions adopted to face the specific needs of the project. The overall accuracy assessment is performed considering some known vertices: the results are fully compliant with the requirements for subsequent hydrological analysis.
A conceptual framework on the integration of solar energy systems in heritage sites and buildings
Authors: Lucchi E , Polo Lopez C S , Franco G
Published: November 2020

The integration between solar energy systems and building components is highly critical in sensitive heritage contexts. On the one hand there is the need for finding a balance between the preservation of the aesthetic appearance and the historical values, but on the other hand, finding the space where to effectively integrate the systems might be quite challenging. The solar systems can be divided in photovoltaic (PV) and solar thermal (ST) systems. Building Integrated Photovoltaics (BIPV) and Building Integrated Solar Thermal (BIST) are PV or ST panels integrated into the building envelope, combining the energy generation with other functions, such as noise, weather protection, thermal insulation, sun shadow, and other aspects. Nowadays, the dynamism of the market allows to design highly compatible products which look like traditional architecture materials. This situation fosters the integration of these products in the BIPV and BIST systems within the heritage sites, especially thanks to the use of advanced customisation processes, special and low-reflecting glasses, and innovative cost-competitive coatings. There is a limited number of studies on the application of these technologies in heritage contexts, due to the presence of architectonic, conservative, and cultural barriers. This paper aims to conduct a comprehensive review of the available literature on the integration of renewable energy sources (RES) in heritage sites and buildings, which would foster the preservation of their cultural and natural values as well as reducing primary energy consumption, increasing comfort levels, minimizing environmental impacts, and improving technical quality and economical outlays. A common framework will thus defined to support restorers, historic conservators, and energy experts and to facilitate the diffusion and application of RES in heritage contexts. This conceptual framework will provide industries and academics with operative strategies and will encourage their diffusion and application in sensible contexts.
Risk management of oil and gas transportation facilities based on reliability indicators monitoring
Authors: Zemenkova M Yu , Zemenkov Yu D , Gladenko A A , Chizhevskaya E L
Published: November 2020

The paper considers the methodological aspects of the analysis of technical risk based on real data on the reliability of objects. Today, there is a problem of assessing the probability of technological events of various types based on statistical data of events at various facilities; however, the current state of automatic control systems for production processes allows preventing an accident, transferring it to the category of incidents. In this case, there is a real distortion of information on statistics of dangerous situations. In modern control systems, information for forecasting and preventing accidents is the most valuable. The paper presents a systematic approach to the creation of new generation technical risk management systems.
Conditions choice for conducting experiments to determine the oil cooling time
Authors: Yakupov A U , Cherentsov D A , Voronin K S
Published: November 2020

The paper considers the option of processing the results of a computer experiment to determine the oil cooling time in a suspended oil pipeline. The authors of the article in previous works proposed a calculation model that allows simulating the process of oil cooling. As part of the design of the experiment, it is necessary to determine the factors affecting the oil cooling time in the pipeline, which will vary in the experiment. Empirical formulas are established, a regression analysis is carried out. The estimates of reproducibility dispersions are calculated. The adequacy hypothesis was tested using the Fisher criterion. Significant regression coefficients were established.
Simulation of the stress-strain state of the working body of the system for the development of the pipeline trench
Authors: Pirogov S P , Cherentsov D A , Voronin K S , Yakupov A U
Published: November 2020

The use of mechanical pressure gauges as pressure measuring devices is regulated by standard documentation. Also, manometric tubular springs – the sensitive elements of pressure gauges are used in various technology fields. Thus, the use of MTS in agricultural machinery allows reducing the traction resistance of tillage machines due to the effect of vibration when interacting with the soil, as well as improving the quality of the soil treatment process by adjusting the stiffness of the rack. This paper presents the results of calculating the stresses and deformations of the ripper shank structure, made in the form of a flexible tubular element when loaded with internal pressure and external force. The active development of the oil and gas industry is currently directed towards the remote territories of the Yamal peninsula and the territories of the Far East, which are characterized by complex natural and climatic conditions of construction. In this regard, it is necessary to develop new approaches and methods of construction in permafrost conditions. The paper presents the results of calculating the stresses and deformations of the structure of the ripper shank, made in the form of a flexible tubular element under loading by internal pressure and external force. The finite element method implemented in the “ANSYS” program was used for research.
Determining the location of the well’s production collecting site at an oil field
Authors: Voronin K S , Cherentsov D A , Yakupov A U
Published: November 2020

The paper considers a possible solution to the problem of optimizing the location of a well’s production collecting site at an oil field. Depending on the location of the collecting site, the length of the pipelines going from the well clusters changes. Minimizing the total length of the oil collecting pipelines network will lead to lower capital costs for the construction of a well’s production collection system.
Current state and perspectives of the gas industry of Russia
Authors: Makhmudova L Sh , Akhmadova Kh Kh , Pimenov A A , Khadisova Zh T , Abdulmezhidova Z A
Published: November 2020

The dynamics of energy consumption in the world market is analyzed. The natural gas demand growth forecast is provided. Gas will be the most crucial energy source in the next 30 years which can be considered to be the “era of gas”. It is shown that natural gas is a promising source of energy and raw materials of petrochemical chemistry. Unlike oil and coal, gas will have strengthened its position by increasing its share in the total balance of primary energy carriers from 22 to 24-26% by 2035. By the middle of the 21st century, its share will have been 25 -27% in the world and 56% in Russia. The use of natural and associated petroleum gas in Russia is compared with global trends. In Russia, the use of useful gas components does not meet potential capabilities of the raw material base and does not comply with the world practice. The rational use of hydrocarbons can be organized through the cooperation of gas processing. The backlog of Russian gas processing is described. Currently, global gas processing is in the GTL era. In order to increase the profitability of producing synthetic liquid hydrocarbons, a combination of existing and GTL enterprises is promising. Developments of Russian scientists and world experience allow us to create GTL-production in almost all developed regions of Russia. The conclusion about the possibility and necessity to develop GTL-production is drawn.
Experience in developing oil and gas deposits with horizontal wells located near the gas processing plant
Authors: Vaganov E V , Tomskaya V F , Krasnov I I , Alsheikhly M J Z
Published: November 2020

In this work, four wells were analyzed at the Srednebotuobinskoye oil, gas and condensate field located in the Republic of Sakha (Yakutia). Production of oil reserves is complicated by the problem of gas breakthrough from the gas cap into the oil area of the reservoir, which leads to gasification of production wells up to their full shutdown. The field is characterized by the presence of a thin oil rim. That is why there is an urgent need to develop innovative technologies capable of ensuring higher oil recovery rates. The result of the conducted analysis is the object of implementation of the research results of this work.
Approbation of the system technology for improving well drilling under difficult mining conditions of Bashkortostan fields
Authors: Chizhov A P , Andreev V E , Mukhametshin V V , Kuleshova L S
Published: November 2020

A method for systematic improvement of the drilling technology in difficult mining conditions has been suggested. The study deals with unstable rocks of the sedimentary cover of the eastern edge of the Russian platform and conditions for well construction. Wells are directional with horizontal ends. Field tests have shown that technical and technological solutions can solve scientific and technical problems. It is recommended to test these solutions in the conditions of other Russian regions and abroad.
Investigating the mechanisms of shape distortion of the heat-affected region during electric-arc welding of oilfield pipelines
Authors: Khabibullin M Ya , Suleimanov R I
Published: November 2020

The article studies the issue of the influence of the most encountered in practice defects of welded joints of a one-piece joint, formed in the process of applying a weld when connecting oilfield pipelines to a joint by electric arc manual welding, on the strength characteristics of a welded joint by scrutinizing the condition of the pipe material close to the heat-affected zone. As a test sample, a butt welded joint with obvious defects was used. The geometric parameters of the welded joint were measured using standard means and the hardness of the heat-affected zone was determined by the Rockwell method in certain areas with justification of the welding process. The reason for softening is established. The change in the geometry of the heat-affected area is due to the accumulation of filler material during its melting on one side of the weld with a decrease in welding speed. Recommendations are given for the prevention of the destruction of welded structures and the occurrence of emergency situations in oilfield pipelines.
Research deformation caused by hydraulic fracturing
Authors: Verisokin A E , Airapetova A A , Zhulina L G , Nazarenko A V , Tkachenko V A
Published: November 2020

The paper discusses problems of tensile loadings affecting a soil layer when conducting hydraulic fracturing. The effect of tensile stress on rocks in a bottomhole formation zone during hydraulic fracturing is studied using numerical methods. A special analysis of the processes of cores deformation under reservoir conditions is carried out in the paper. The article provides formulas to calculate stress-strain state of rocks in bottomhole formation zone. Along with an exact numerical study of the distribution of stresses in bottomhole formation zone, some approximate analytical dependencies reflecting features of the stress-strain state of bottomhole formation zone are obtained with the aim of solving optimization problems. The paper presents the scheme of production layer vertical deformation which shows layer’s roof and bottom displacement caused by increased pressure inrepression cone. Formulas describing the influence of deformation processes in bottomhole formation zone can also be used to study cyclic operation of underground gas storages.
Backfilling for mines
Authors: Zagorodnyuk L H , Chernysh A S , Lesovik V S , Schekina A Yu , Ryzhikh V D , Sumskoy D A , Sinebok D A
Published: November 2020

The article introduces results of studying the problem areas in filling masses of iron ore mining-and-processing enterprise. Some basic study of back filling after the blast hole drilling has been conducted by the authors. The samples picked from the disrupted back filling have been studied for strength. The analysis of the results evidences that all the samples meet the requirements of the strength class but there is a variation of the strength characteristics which evidences about the massif inhomogenuity. The results of chemical, X-ray and fluorescent analyses proved high inhomogenuity of solidified back filling masses in the massif. The microstructure of the back filling samples has inhomogeneous structure, with a great number of various pores. A set of studies showed lack of uniformity and consolidation of the filling solution. It resulted in the loss of strength and durability of the back filling area. The analysis of possible reasons for negative results has been given. The activities to improve the quality and durability of the back filling for mines have been suggested.
Analysis of the current issue of well bore and well bottom cleaning
Authors: Zainagalina L Z
Published: November 2020

The paper considers the problem of insufficient cleaning of oil and gas wells from drill cuttings. The formation of slurry dunes is the main cause of complications and accidents in horizontal well drilling. The task related to the development of high-efficiency equipment for well bottomhole cleaning from drill cuttings is quite relevant. The existing techniques and technologies for borehole bottom cleaning from drill cuttings caused by rotary drilling were analyzed to find a way of improving the efficiency of borehole bottom cleaning. A new technical solution for cleaning vertical, directional and horizontal wells from drill cuttings was developed. The process functional diagram of at-bit sludge chopper during turbine drilling is presented to increase the cleaning efficiency of bottomhole and wellbore of vertical, directional and horizontal wells from drill cuttings during roller boring.
Differential impact on wellbore zone based on hydrochloric-acid simulation
Authors: Zeigman Yu V , Mukhametshin V V , Kuleshova L S
Published: November 2020

On the basis of geologic and statistical modeling in high-viscosity oil deposits of the Tournaisian stage and using the obtained models the paper proposes to carry out forecasting, selection of wells, control and regulation of the impact process in order to reduce the number of inefficient operations and increase technical and economic indicators of fuel and energy complex enterprises.
Research of dependence centrifugal pump efficiency of impeller slit seal design parameters
Authors: Protopopov A , Belov N , Kalugina M , Mukhlaeva A
Published: November 2020

Efficiency and resource are the two main characteristics of a centrifugal pump. In present study, the dependence of these characteristics from impeller sealing wear ring configuration was considered. Range of models with various configurations has been analyzed using numerical flow simulation. Compromise curves nave been obtained as a result. This information allows select an optimal ratio of dimensions of wear ring hydrodynamic slit seal to achieve a balance between efficiency and reliability of centrifugal pump.
Investigation of the dependence of the axial force acting on the rotor of a vertical centrifugal pump on the area of the discharge holes of the impeller
Authors: Protopopov A , Zhestkiy N , Godorozha S , Kalugina M , Mukhlaeva A , Zaitseva A
Published: November 2020

The article describes a vertical centrifugal pump with a bearing Assembly in the upper part of the rotor. It is shown that for certain values of design parameters, the influence of the so-called discharge holes in the impellers can significantly affect the axial force acting on the rotor, and for certain parameters, for example, with a large weight of the rotor, this influence is insignificant and the manufacture of such impellers is impractical.
Profiling of the flat-tool for manufacturing worms with circular eccentric profile by cold forming
Authors: Frumuşanu G , Teodor V , Oancea N
Published: November 2020

The incremental pumps are encountered in pharmaceutical and cosmetics industries. One of the most representative categories of these pumps is formed by the progressing cavity pumps. The helical surfaces with circular profile, eccentrically positioned relative to worm axis, are frequently used in their rotors construction. In this specific case, the constructive dimensions of the worms allow their manufacturing by cold forming, with flat-tools similar to screwing dies. In this paper, an analytical algorithm for profiling such flat-tool is proposed. The algorithm starts from the analytical definition of the helical cylindrical surface with constant pitch of the generated worm, and it lays on the “Minimum distance method”. The equations of the gearing surface between worm and flat-tool are found, and, based on this, the active surface of the tool is determined. A MatLab application developed for implementing the profiling algorithm is presented. The results obtained after running the application in the case of a particular generated surface are also included.
Basic mechanical analysis of biodegradable materials
Authors: Mazurchevici A D , Popa R I , Carausu C , Comaneci R , Mazurchevici S N , Nedelcu D
Published: November 2020

The field of polymeric materials and manufacturing technologies is constantly evolving, offering the possibility to prototype 3D products in a responsible and ecological way, thus aiming to replace on a large scale the filaments of nonbiodegradable synthetic polymers (from fossil resources) with filaments of biodegradable materials, obtained from renewable resources. The paper supports the development mentioned above and follows to characterize biodegradable materials from the mechanical behavior point of view, tensile, bending, and impact tests. Also, the study reflects the influence of the technological parameters on the tensile test obtained results and also aims to optimize the obtained results. The studied materials were Extrudr Green-TEC Anthracite and Extrudr BDP Pearl which according to the obtained basic mechanical results can successfully replace conventional polymers such as Flexible, HIPS, PP and other ones.
Study on the influence of technological parameters on the friction stir butt welding process of pure copper plates
Authors: Constantin M A , Nitu E L , Iordache D M , Badulescu C
Published: November 2020

Friction stir welding - FSW is a relatively new welding process, which is increasingly used in industry, due to the advantages which it has in relation to conventional processes (by melting and adhesions). The advantages of the FSW welding process (as a solid phase welding process) are all the more obvious in the case of joining copper and its alloys, because they have a high melting temperature and high thermal diffusivity. The influence of the technological parameters of the process, the tool rotational speed and the welding feed, on the temperature and the axial force, as well as on the quality of the joint surface is presented. The study shows that the stabilization of the process takes place after a certain time from the beginning of the advance stage and highlighted the major influence of the tool rotational speed on the process temperature, surface defects and the roughness of the joint surface.
Static Structural Analysis Analytical and Numerical of Ball Bearings
Authors: Belabend S. , Paunoiu V. , Baroiu N. , Khelif R. , Iacob I.
Published: November 2020

FEM analysis is a very efficient method for achieving results of stresses at different loading conditions according to forces and boundary conditions applied to the component the static analysis. The purpose of the study is to collect data’s using two different softwares and then to compare them with analytical results. This work aims at analysing the behaviour of the ball bearings under a static load, using Solidworks, ANSYS and MESYS software. The comparison is done between the analytical results using the Hertzian theory, ANSYS and MESYS, for two different cases of loading.
Algorithm for screws profiling of a conical trilobed compressor - analytical solution
Authors: Baroiu N , Costin G A , Teodor V G , Oancea N
Published: November 2020

Screw compressors, as rotary machinery, are capable of working with high compression ratios for gas compression. They transform the mechanical work done by an electric motor or turbine into the potential energy of a gas, by reducing its volume and increasing the pressure. The essential elements of these compressors are the two helical rotors with lobes, mounted in a housing. Existing rotors in the construction of compressors are working bodies whose composite profiles include circle arcs, line segments and cycloidal curves, while also often including non-analytical curves. Such geometry of profiles gives the gear processes superior characteristics, in the sense of reducing friction and improving sealing conditions. This paper analyses, by analytical approach, the possibility of constructing a multilobated conical screw compressor with a number of lobes Z, Z + 1, of the male and female rotor. The parametric equations of the contained worm and the kinematics of the working process of the conical screw compressor shall be defined. The theory of surface wrapping comprises analytical methods of study, which were developed on the basis of the fundamental theorems on wrapping of known surfaces in differential geometry and the kinematics laws on rotor movements. Thus, this paper proposes an algorithm based on the approach to the problems analyzed under the “virtual focal points theorem” between the complex surfaces of the conical surface lobes, which constitute the active lobes of the male and female rotors. Normal to active surfaces are defined, and also the speed in relative movement, in the “gear” process of the conical screw compressor. Regarding rotors in conical screw compressors, the circular pitch of the teeth is constant. Also, the screw pitch of the conical compressor rotors is a constant value. In these conditions, the rotors of the screw compressors are acknowledged as active surfaces, conical screw surfaces with constant axial screw pitch. The cross section (in the normal plane to the driving rotor axis) determines a plane gear. This defines the specific winding condition, and the shape of the conical screw surface of the female rotor.
Comparison of the Strength Properties of Heat-Resistant Titanium Alloys at Elevated Temperatures
Authors: Davydenko L V , Egorova Yu B , Mamonov I M
Published: November 2020

The results of statistical studies of the strength properties of rods made of heat-resistant titanium alloys at test temperatures of 20-600 °C are represented. The initial data for the research were the results of experiments published in various sources from the 1960s to 2019.The chemical composition of the alloys has been compared by aluminum and molybdenum equivalents and tensile strength at various temperatures. With an increase in the degree of alloying with a-stabilizers and neutral hardeners, the heat-resistant properties of alloys increase and remain at higher temperatures. However, this may reduce the thermal stability of alloys with an aluminum equivalent of more than 9.0%. The highest strength properties while maintaining thermal stability have alloys with aluminum equivalents of 8.5-9.0% and molybdenum of 1.0-4.5%. Regression dependences of the average values of strength properties on the test temperature, silicon content, and aluminum and molybdenum equivalents of alloying elements and impurities have been determined.
Choosing the Rational Heat Treatment Conditions for High-Strength Cold-Resistant Weldable Steel with Yield Strength of more than 600 N/mm2
Authors: Poletskov P P , Kuznetsova A S , Nikitenko O A
Published: November 2020

Rational heat treatment conditions for the new weldable cold-resistant steel grade 20G2SMRA ensuring a guaranteed yield strength σ0,2 ⩾ 600 N/mm2 combined with the lowtemperature impact strength KCV-60 ⩾ 50 J/cm2 have been searched. The effect of various quenching and tempering conditions on the steel microstructure parameters, hardness, and impact strength at a temperature of -60 °C has been studied. The dependencies of the microstructure parameters, hardness (HV1), and impact strength (KCV-60) on the quenching and subsequent tempering temperature are represented. Rational heat treatment conditions have been found for a new weldable cold-resistant steel with high yield strength.
Electromagnetic Properties of Composite Materials Based on Nd-Compound Modified Fe-Si-Al Alloy
Authors: Goryachko A I , Ivanin S N , Yu Buz’ko V
Published: November 2020

The investigation of microstructure, optical and electromagnetic properties of powder prepared from Nd-compound doped Al6Si9Fe85 (Alsifer) alloy. The result of energy-dispersive X-ray spectroscopy is an evidence that the complementary Nd-containing Nd-Fe phase is on the surface of Alsifer particles. The magnetic particles distribution histogram in powder after mechanical treatment was plotted and analyzed. The electromagnetic properties (components magnetic permeability and dielectric permittivity) for produced composites with Nd-compound doped Alsifer powder with 50-90% (wt.) was studied. The nonlinear concentration dependence of magnetic and dielectric permittivity versus concentration Nd-compound doped Alsifer particles was observed. The magnetic resonance in composites was detected that shifted in low frequencies with increased magnetic filler concentration. The resonance field, absorption linewidth, g-factor and microwave absorption ability of Nd-compound doped Alsifer powder were determined from FMR experiment.
Aperiodic Schrodinger Crystals
Authors: Malkov V B , Chemezov O V , Malkov A V
Published: November 2020

In 1945, E. Schrödinger predicted the possibility of the existence of “aperiodic crystals,” that is, more and more increasing crystalline aggregates, but without a simple lattice repetition mechanism. In the present work, such structures are experimentally prepared using selenium as an example. By thermal gradient treatment of the amorphous selenium film, we have obtained nano-thin spatial dissipative structures (SDS) of hexagonal selenium, the lattice of which undergoes non-uniform rotational curvature around, in the general case, three mutually perpendicular directions. The formation of these nano-thin SDS of hexagonal selenium occurs as a result of cooperative rotations of selenium macromolecules around, in general, three mutually perpendicular directions. Since nano-thin SDS after hardening in air have all the features of crystals each of the above nano-thin SDS of hexagonal selenium obtained at different annealing temperatures corresponds to the concept of “aperiodic crystals” Thus, “aperiodic crystals” were obtained experimentally, the possibility of the existence of which was predicted by E. Schrödinger.
Synthesis, Structure and Properties of Zn0.3Ni0.7-xCoxFe2O4 Ferrite
Authors: Sherstyuk D P , Yu Starikov A , Zhivulin V E
Published: November 2020

The article presents the results of a study of ferrite Zn0.3Ni0.7-xCoxFe2O4, where x = 0 – 0.6 in increments of 0.2. The samples were obtained by solid-phase synthesis in a tube furnace with silicon carbide heaters at a temperature of 1150 °C for 5 hours. X-ray phase analysis showed that all the samples obtained are monophasic and have a spinel structure. X-ray structural analysis revealed that the substitution of cobalt atoms for nickel atoms leads to a monotonic increase in the parameters (a and V) of the unit crystal lattice. The elemental composition of the synthesized samples was monitored using an energy dispersive analyzer installed on a Jeol JSM 7001F scanning electron microscope. The aim of this work was to obtain new monophasic samples using previously developed technology.
Formation of Impurity Inclusions in Silicon when Smelting in Ore-Thermal Furnaces
Authors: Nemchinova N V , Hoang V V , Tyutrin A A
Published: November 2020

Silicon production by carbon reduction of silica-containing raw materials is performed in ore-thermal furnaces. The process proceeds at high temperatures (above 2,000°C). Consumers place high demands on the chemical purity of the silicon smelted, but the finished product contains a negligible amount of impurities. We have analyzed the causes for the impurity inclusions in silicon forming in smelting based on the data on the behavior of various elements penetrating the process with quartzite and reducing agent ashes. The chemical composition of furnace slag and silicon samples from the Silicon JSC of RUSAL (Russia) has been analyzed using various techniques, i.e. metallographic, X-ray fluorescence, X-ray diffraction, and X-ray spectral microanalysis. It has been established that the main source of non-metallic inclusions in silicon are furnace slag particles enmeshed in the melt when it is released from the tap. Due to the high degree of iron passing into the melt when smelting, the main metal inclusions are metal aluminum solutions based on iron, silicon, and other elements: FeSi2Al0,3, FeSi1,5Al0,3, and FeSi2Ti. The main way to improve the smelted silicon quality is to select feed with a minimum amount of impurities and conduct the process at optimal temperatures in the quartzite melting zone.
Mathematical Modelling of the Thermal State of a Ladle During Arc Heating of the Melt
Authors: Agapitov E B , Sokolova M S , Lemeshko M A
Published: November 2020

The paper analyzes energy losses in the ladle furnace. In particular, the authors focus on electrical losses, namely total energy losses of the electric arc, conditionally including radiation losses of a part of the arc uncovered by slag. Managing these flows creates conditions for increasing the efficiency of heating. The calculations given in the paper showed that electrical losses decreased, during prolonged heating (about 8-12 minutes) with a sufficient amount of slag. This mode provides a reduction in heat loss by 4-5 %. By selecting options of changes in a sequence of stages and their duration, the proposed mathematical model makes it possible to apply a new technology to process molten steel in the ladle furnace characterized by lower power consumption.
Research of Possibility of Processing of Oxidized Nickel Ore by Chloride Sublimation Roasting Technology
Authors: Kolmachikhina O B , Polygalov S E , Lobanov V G
Published: November 2020

Oxidized nickel ores (ONO) contain most of the world’s nickel reserves. However, choice of a cost-effe nickel ore processing technology is difficult due to the dispersed distribution of nickel compounds in refractory minerals, low nickel content, presence of a large amounts of consuming host rocks, and impossibility of beneficiation by conventional physicochemical methods. The paper presents studies on the ONO processing technology by means of chloride sublimation roasting. Sodium and calcium chlorides were used as chlorinating agents both individually and in various ratios. It has been shown that roasting allows for nickel and cobalt conversion into chloride form followed by selective distillation of the resulting compounds into the gas phase by 89 – 90% at a roasting temperature of 1100 °C.
Oxidized Nickel Ore and Galvanic Sludge Combined Treatment Investigation
Authors: Boshnyak M V , Kolmachikhina O B , Kolmachikhina E B
Published: November 2020

Galvanic sludges have been accumulated in large quantities in Ural region. These materials contain low concentration of non-ferrous metals (nickel, zinc, chromium) and iron, and are not being processed. Another difficult for treatment nickel containing materials are oxidized nickel ores, deposits of which are located in Ural. However, the nickel ores aren’t processed due to low economic efficiency. In this article simultaneous treatment of oxidized nickel ore and galvanic sludge was investigated. The proposed technology includes nickel ore sulfatization at high temperature in presence of sulfuric acid and further water leaching. Therefore, maximum nickel extraction in solution at leaching of oxidized nickel ore after sulfatization was 82 %. Solutions after leaching are neutralized by nickel containing galvanic sludge. Due to partial nickel chromite dissolution in sulfuric acid a total nickel concentration has been substantially increased. Selective nickel extraction from such solutions is possible by sorption methods, and further metal nickel obtaining – by electrowinning.
Heat Exchange in High-Power Arc Steel Furnace when the Height of the Slag Layer Changes
Authors: Makarov A N , Krupnov A V
Published: November 2020

Calculation results and analysis of changes in thermal radiation density of arcs by wall height for hundred-ton arc furnaces at different slag layer height and at equal arc power are presented. It was found that with an increase in the height of the slag layer from 70 to 300 mm, that is, with an increase in the depth of the arcs in the slag, the density of thermal radiation flows of the arcs in the most heat-loaded part of the walls decreases by 2 times. The efficiency of arcs increases with the increase in the depth of arcs in the slag and increases by 1.61 times when fully buried.
Study of the Principles for Ensuring the Accuracy of CCM Design Parameters
Authors: Sotnikov A L , Sholomitskii A A , Strichenko S M
Published: November 2020

It is established that the defining factor of accuracy of the designing parameters of S-type billet continuous casting machine (CCM) is relative difference of curvature of the adjacent arc-like sections, which form process axis of strand. An analysis of the local radius change of CCM ingot path curvature is carried out. In the process of CCM equipment alignment, it is necessary to ensure alignment of its curvature centers under condition of curvature value equality for minimization of its relative difference. Developed technology of position control and CCM equipment alignment allows meeting this requirement. The developed technology is based on the use of “Vizir 3D” a high-precision measurement system built on the base of electronic total station. Practical experience of alignment showed the efficiency of geodesic and combined method of equipment alignment on both billet and slab CCM.
Investigation of Influence of Silicon Carbide Phase and Chemical Composition on its Recovery
Authors: Boldyrev D A , Popova L I , Tokarev A A
Published: November 2020

When employing the cast iron manufacturing technology involving the use of silicon carbide, it was discovered that recovery of silicon carbide and that of its individual elements, viz., carbon and silicon varied. Based on the results obtained from a diffraction analysis and electron microscope investigation with electron microprobe analysis, the genuine structural and chemical features of industrial-grade silicon carbide were described. The phase composition of silicon carbide is inhomogeneous and consists of particles of the a-SiC crystalline silicon carbide and oxidized non-crystalline silicon carbide whose basis is a solid solution “carbon-silicon”. Recovery of silicon carbide by molten cast iron determined by the increase in the contents of carbon and silicon during the melting process is inversely on the content of the a-SiC phase.
Acoustic Methods for Testing Gas Turbine Engine Blades
Authors: Trofimov V N , Pyankov I N , Pyankov V A
Published: November 2020

In this paper the application technology of the ultrasonic testing method in the process of the PS-90A aircraft engine manufacturing is considered. It is known that the development and implementation of monocrystalline turbine blades for aircraft gas turbine engines are aimed at ensuring the material effectiveness or increasing the blade service life in comparison with polycrystalline blades. It is achieved at the cost of the increased long-term material strength in the same temperature range. Based on the results of the process and metallographic studies analysis, it has been established that during the structure formation under the internal stress action, hot crystallization cracks with an opening from 3 to 8 μm or more and a length of 3 to 35 mm along the grain boundaries can appear. Grains formation in most blades happens with their subsequent exit to the lock end, a bridge. The formation of hot cracks most likely occurs at a large grain disorientation angle (more than 25°). Grain boundaries on blades with hot crystallization cracks are located, as a rule, on the bridge at the junction of the blade root with the blade shank (“bottleneck”) with orientation along the blade axis. The method of contact laser-ultrasonic flaw detection (CLUFD) was tested on blades in the region of bridges using both pilot samples and standard parts in order to solve an urgent production and technical problem, that is timely detection of hot crystallization cracks in rotating turbine engine blades at the manufacturing stage. The use of the phased antenna array technology (PAR) in combination with a portable X-32 flaw detector represents a new level of blade ultrasonic testing. The flaw detector operates in a wide frequency range, which allows solving a very large range of various ultrasonic testing problems. The advantages and possibilities of the PAR technology with the portable X-32 flaw detector can be considered on the example of the turbine blade lock testing. S-scan (sector-scan) makes it possible to interpret the received signals quickly and easily.
Features of Design of Chill Molds for Casting of Non-Ferrous Metal
Authors: Gavariev R V , Gavarieva K N , Soldatkina E N
Published: November 2020

The article discusses methods for calculating the main parameters of the chill mold in the design process. Formulas for calculating the thickness of the working wall, as well as recommendations for choosing the material of the chill mold, depending on the size and shape of the resulting castings, are specified. Disadvantages of existing methods for calculating the chill mold parameters are indicated. Solutions for the use of multi-layer coatings applied by physical vapor deposition on the forming surface of the chill mold are proposed, which increases the efficiency of the casting process in the chill mold, regardless of the shape of the casting and the design of the chill mold.
Manufacture of Ceramic Molds and Cores from Inorganic Materials Using Permanent
Authors: Znamenskii L G , Ivochkina O V , Stepanova T V
Published: November 2020

The paper describes the technology for the manufacture of ceramic molds and cores from inorganic materials using permanent masters. A technique for reinforcing molds and cores using ceramic tubes is proposed. The effect of pulse currents of different power on the slurry has been studied. In the experimental part, the performed experiments and the data obtained are described. In contrast to the conventional Show-process based on ethyl silicate binder (basic option), the technology developed for the manufacture of ceramic molds from inorganic materials ensures improving the quality and economic and environmental efficiency of investment castings. The quality improvement is determined by improved physical and mechanical characteristics of ceramic molds and the stable ceramic cracking. The improvement in environmental indicators is ensured by using safe inorganic molding materials and eliminating the solvent burning. Improving economic indicators is determined by reducing power consumption for calcining ceramic molds, casting defects, and molding material costs. Thus, the technology developed allows improving the quality of investment castings manufactured for the country’s oil and gas complex.