bluuebunny/crossref_metadata_2025 huggingface dataset:
VO2 nanophotonics
Authors: Cueff Sébastien , John Jimmy , Zhang Zhen , Parra Jorge , Sun Jianing , Orobtchouk Régis , Ramanathan Shriram , Sanchis Pablo
Published: November 2020

The intriguing physics of vanadium dioxide (VO2) makes it not only a fascinating object of study for fundamental research on solid-state physics but also an attractive means to actively modify the properties of integrated devices. In particular, the exceptionally large complex refractive index variation produced by the insulator-to-metal transition of this material opens up interesting opportunities to dynamically tune optical systems. This Perspective reviews some of the exciting work done on VO2 for nanophotonics in the last decade and suggests promising directions to explore for this burgeoning field.
Genesis, evolution, and apocalypse of Loop Current rings
Authors: Andrade-Canto F. , Karrasch D. , Beron-Vera F. J.
Published: November 2020

We carry out assessments of the life cycle of Loop Current vortices, so-called rings, in the Gulf of Mexico by applying three objective (i.e., observer-independent) coherent Lagrangian vortex detection methods on velocities derived from satellite altimetry measurements of the sea-surface height (SSH). The methods reveal material vortices with boundaries that withstand stretching or diffusion or whose fluid elements rotate evenly. This involved a technology advance that enables framing vortex genesis and apocalypse robustly and with precision in a truly parameter-free fashion. We find that the stretching- and diffusion-withstanding assessments produce consistent results, which show large discrepancies with Eulerian assessments that identify vortices with regions instantaneously filled with streamlines of the SSH field. The even-rotation assessment, which is vorticity-based, is found to be quite unstable, suggesting life expectancies much shorter than those produced by all other assessments.
Critical Galton-Watson branching processes with a countable set of types and infinite second moments
Authors: Vatutin V. A. , Dyakonova E. E. , Topchii V. A.
Published: November 2020

We consider an indecomposable Galton-Watson branching process with a countable set of types. Assuming that the process is critical and may have infinite variance of the offspring sizes of some (or all) types of particles we describe the asymptotic behaviour of the survival probability of the process and establish a Yaglom-type conditional limit theorem for the infinite-dimensional vector of the number of particles of all types.

Bibliography: 20 titles.
Polyhomomorphisms of locally compact groups
Authors: Neretin Yu. A.
Published: November 2020

Let

and

be locally compact groups with fixed two-sided invariant Haar measures. A polyhomomorphism

is a closed subgroup

with fixed Haar measure, whose marginals on

and

are dominated by the Haar measures on

and

. A polyhomomorphism can be regarded as a multi-valued map sending points to sets equipped with ‘uniform’ measures. For two polyhomomorphisms

and

there is a well-defined product

. The set of polyhomomorphisms

is a metrizable compact space with respect to the Chabauty-Bourbaki topology and the product is separately continuous. A polyhomomorphism

determines a canonical operator

, which is a partial isometry up to a scalar factor. For example, we consider locally compact linear spaces over finite fields and examine the closures of groups of linear operators in semigroups of polyhomomorphisms.

Bibliography: 40 titles.
Approximation of resolvents in homogenization of fourth-order elliptic operators
Authors: Pastukhova S. E.
Published: November 2020

We study the homogenization of a fourth-order divergent elliptic operator

with rapidly oscillating

-periodic coefficients, where

is a small parameter. The homogenized operator

is of the same type and has constant coefficients. We apply Zhikov’s shift method to obtain an estimate in the

-operator norm of order

for the difference of the resolvents

and

.

Bibliography: 25 titles.
Topological analysis of a billiard bounded by confocal quadrics in a potential field
Authors: Pustovoitov S. E.
Published: November 2020

Consider a billiard in a plane domain bounded by confocal ellipses and hyperbolae. A Hooke potential acts on a point mass. This dynamical systems turns out to be completely Liouville integrable. A topological analysis of the Liouville foliation of isoenergy manifolds at all possible levels of the Hamiltonian is performed and the complete Fomenko- Zieschang invariants (marked molecules) of these manifolds are constructed. Bibliography: 15 titles.
Condition thresholds in Australia’s threatened ecological community listings hinder conservation of dynamic ecosystems
Authors: Saunders Manu E. , Bower Deborah S. , Mika Sarah , Hunter John T.
Published: November 2020

Environmental degradation is threatening biodiversity and ecosystem function globally. Mandating ecosystem-level protection in policy and legislative frameworks is essential to prevent biodiversity loss. Australia’s Environment Protection and Biodiversity Conservation Act 1999 is the key legislative mechanism for supporting biodiversity at the national level, but has so far been ineffective at protecting habitat and ecological communities. Here we identify a major flaw in the current approach to listing threatened ecological communities (TECs): restrictive condition thresholds that threaten ecosystem function in dynamic ecosystems. Using two wetland TECs as a case study (Upland Wetlands and Coolibah-Black Box Woodlands), we argue that Australia’s environmental legislation should adopt a landscape-scale approach to TEC protection that acknowledges ecosystem function, accounts for different states in temporally dynamic systems, and sustains landscape connectivity of TEC distribution. We present a state-and-transition model for each TEC to show how human activities affect the reference-state continuum of wet and dry phases. We also show that the current listed condition thresholds do not acknowledge alternative ecosystem states and exclude areas that may be important for restoration and conservation of the TEC at the landscape-scale. Description of alternative and transitional states for dynamic systems, including how, when and why ecological communities shift between different states, should be formally integrated into the TEC listing process to protect Australia’s vulnerable ecosystems from further degradation and loss.
Crystal structure of a guanine nucleotide exchange factor encoded by the scrub typhus pathogen
Orientia tsutsugamushi
Authors: Lim Christopher , Berk Jason M. , Blaise Alyssa , Bircher Josie , Koleske Anthony J. , Hochstrasser Mark , Xiong Yong
Published: November 2020

Significance

Scrub typhus is a neglected tropical disease caused by the bacterium
Orientia tsutsugamushi
. Although
O. tsutsugamushi
is an emerging public health threat, its pathogenic mechanisms remain markedly understudied. Bacterial pathogens subvert host actin dynamics by encoding guanine nucleotide exchange factors (GEFs) as effector proteins, which activate cellular Rho GTPases. Here, we identify a GEF domain within an
O. tsutsugamushi
protein that activates the host GTPase Rac1. While the overall shape of the GEF is similar to that of other bacterial effectors, the primary sequence, topology, and catalytic mechanism are completely distinct, suggesting convergent evolution. Our studies reveal a cryptic GEF domain encoded by
O. tsutsugamushi
and provide the groundwork to probe the role of cytoskeletal modulation in this neglected pathogen.
Phosphatidylinositol 4,5-bisphosphate is regenerated by speeding of the PI 4-kinase pathway during long PLC activation
Authors: Myeong Jongyun , de la Cruz Lizbeth , Jung Seung-Ryoung , Yeon Jun-Hee , Suh Byung-Chang , Koh Duk-Su , Hille Bertil
Published: November 2020

The dynamic metabolism of membrane phosphoinositide lipids involves several cellular compartments including the ER, Golgi, and plasma membrane. There are cycles of phosphorylation and dephosphorylation and of synthesis, transfer, and breakdown. The simplified phosphoinositide cycle comprises synthesis of phosphatidylinositol in the ER, transport, and phosphorylation in the Golgi and plasma membranes to generate phosphatidylinositol 4,5-bisphosphate, followed by receptor-stimulated hydrolysis in the plasma membrane and return of the components to the ER for reassembly. Using probes for specific lipid species, we have followed and analyzed the kinetics of several of these events during stimulation of M1 muscarinic receptors coupled to the G-protein Gq. We show that during long continued agonist action, polyphosphorylated inositol lipids are initially depleted but then regenerate while agonist is still present. Experiments and kinetic modeling reveal that the regeneration results from gradual but massive up-regulation of PI 4-kinase pathways rather than from desensitization of receptors. Golgi pools of phosphatidylinositol 4-phosphate and the lipid kinase PI4KIIIα (PI4KA) contribute to this homeostatic regeneration. This powerful acceleration, which may be at the level of enzyme activity or of precursor and product delivery, reveals strong regulatory controls in the phosphoinositide cycle.
Rushing to maintain plasma membrane phosphoinositide levels
Authors: Balla Tamas
Published: November 2020

New findings by Myeong et al. provide further details on how cells maintain their plasma membrane PI(4,5)P2 levels when stimulated via M1 muscarinic receptors
Weak-focused acoustic vortex generated by a focused ring array of planar transducers and its application in large-scale rotational object manipulation*
Authors: Li Yuzhi , Li Peixia , Ding Ning , Guo Gepu , Ma Qingyu , Tu Juan , Zhang Dong
Published: November 2020

Contactless manipulation of multi-scale objects using the acoustic vortex (AV) tweezers offers tremendous perspectives in biomedical applications. However, it is still hindered by the weak acoustic radiation force (ARF) and torque (ART) around the vortex center. By introducing the elevation angle to the planar transducers of an N-element ring array, the weak-focused acoustic vortex (WFAV) composed of a main-AV and N paraxial-AVs is constructed to conduct a large-scale object manipulation. Different from the traditional focused AV (FAV) generated by a ring array of concave spherical transducers, a much larger focal region of the WFAV is generated by the main lobes of the planar transducers with the size inversely associated with the elevation angle. With the pressure simulation of the acoustic field, the capability of the rotational object driving in the focal plane for the WFAV is analyzed using the ARF and the ART exerted on an elastic ball based on acoustic scattering. With the experimental system built in water, the generation of the WFAV is verified by the scanning measurements of the acoustic field and the capability of object manipulation is also analyzed by the rotational trapping of floating particles in the focal plane. The favorable results demonstrate the feasibility of large-scale rotational manipulation of objects with a strengthened ART and a reduced acousto-thermal damage to biological tissues, showing a promising prospect for potential applications in clinical practice.
Measurement of astrophysical S-factor for 9Be(d, α
0)7Li and 9Be(d, α
1)7Li* reactions at low energies *
Authors: Huang Zhenglin , Chen Bingjun , Qin Lixin , Zhang Qian , Zhang Fang , Wang Tieshan , Fang Kaihong
Published: November 2020

The thick-target yield of the 9Be(d, α
0)7Li and 9Be(d, α
1)7Li* reactions has been first directly measured over deuteron energies from 66 to 94 keV. The obtained S(E
i) of α
0 and α
1 have similar trends calculated by the thin-target yield, consistent with Yan’s report within the errors. Furthermore, the parametric expression of S(E) was obtained to calculate the theoretical thick target yield, and it roughly agrees with the experimental thick target yield.
Reduction of well stimulation period after hydraulic fracturing
Authors: Verisokin A E , Gun’kina T A , Vasil’yev V A , Shchekin A I , Serdyukov D Yu
Published: November 2020

This article discusses the problems associated with the removal of proppant, mechanical particles of the rock and undecomposed fluid from the hydraulic fracture into the well. The necessity of developing a device for washing the perforation interval has been identified and justified. It is shown that hardened and viscoelastic gel particles fall into perforations and adhere to the walls of channels and wells. Subsequently, these zones of gel deposition reduce permeability in perforation channels. The author has developed the design of a device for decolmation (declogging), which reduces the time for well development after hydraulic fracturing. To increase the productivity of the considered wells, it is necessary to flush them with the presented device in the mode of maximum approximation to deposits. To carry particles better to the surface, it is proposed to use foam systems generated by the jet pump, which is described in this article.
Method for improving the liquid hydrocarbon preparation efficiency
Authors: Kulikov A M , Gladenko A A , Alexandrov M A
Published: November 2020

According to the “Energy Strategy of Russia for the Period until 2030” and Decree of the Government of the Russian Federation of November 13, 2009 No. 1715-r, oil and gas companies have to use machines and equipment in the production process, as well as methods and processes that minimize energy consumption, and eliminate negative impacts of technological processes on the environment. New methods for the design, construction and operation of oil and gas facilities and improvement of the existing equipment should be developed and implemented.
The deployment of the collapsible piping through a large water obstacle
Authors: Melnikov D I , Seoev L V , Zemenkova M Yu , Podorozhnikov S Yu
Published: November 2020

Portable pipelines have been used in the Armed Forces of our country since the early 1960s to transfer light oil products. They are used to pump light oil products in large volumes for considerable distances in any climatic and geographic conditions. Portable pipelines were successfully used to eliminate natural and technogenic emergencies. The paper presents an overview of the deployment of portable pipelines across water barriers. It shows the organization and technology of works during the deployment of a pipeline across the 2700 m barrier of the Volga River.
Calculation of the torque on the crank shaft of the low-speed balancing drive sucker rod pumps
Authors: Galeev A.S. , Arslanov R.I. , Suleymanov R.N. , Filimonov O.V.
Published: November 2020

Annotation

The operation of well sucker rod pump installations is the most massive way of mechanized oil production. A significant part of the wells equipped with low-speed plants of this type have a low flow rate and high water cut. Such conditions create certain restrictions on updating and modernization of the production fund of equipment in operation. The life cycle of a rocking machine is usually significant and often exceeds 20 years. During ISPR operation, both ground and downhole equipment will inevitably wear out. A significant proportion of failures of the ground part of low-speed ISPR is associated with the reduction of the rocking machine, which is the most responsible and most expensive drive element. The resource of the gearbox directly depends on its load, which is characterized by the moment on its crank (output) shaft. Reducing the maximum torque and moment fluctuations in one full swing of the rocking machine will significantly increase the reliability of the gearbox and the entire installation. This paper describes the mathematical apparatus for calculating the moment on the crank shaft of the gearbox, based on the exact kinematics of the drive and the principle of possible movements. The proposed methodology will allow to solve the problems of designing a balancing drive of a low-speed ISPR, to determine the requirements for the engine and transmission.
Development of a hydraulic classifier used to obtain various sand fractions
Authors: Verisokin A E , Yanukyan A P , Sorokin P M
Published: November 2020

The principle of crack filler selection depending on the crack depth and closing stress is presented. The study of existing classifiers and proposed a more effective device for sand sieving. The main elements of the classifier are presented and the principle of its operation is described.
The use of a liquid destructor with flow into the stream during the injection of the fracturing mixture
Authors: Fattakhov I G , Kuleshova L S , Kochetkov AV , Galiullina I F , Andaryanov I G , Safiullina A R , Gizatullin I R
Published: November 2020

For most modern development systems, hydraulic fracturing is the main method of intensification and maintenance of hydrocarbon production. Hydraulic fracturing is achieved with the volume of communicating voids between the granules of fractional proppant. The volume of voids should be maximized, which is achieved by selecting the optimal proppant fraction composition, and in addition, hydraulic fracturing fluid, the choice of which is based on a number of competing factors: high viscosity, which provides the necessary hydraulic width created at the buffer stage of the crack, as well as prediction of subsidence proppant in the fracture and subsequent premature stop of the injection, which creates additional costs. One of the new solutions, which will increase the efficiency and expand potential objects for hydraulic fracturing, is the use of a liquid destructor with a flow into the stream during the injection of the fracturing mixture.
Improving the design of a downhole filter for fluid production with an increased concentration of suspended particles
Authors: Khabibullin M Ya , Suleimanov R I , Mingulov Sh G , Kotenev Yu A , Sultanov Sh Kh
Published: November 2020

The reliability of the underground equipment of a well sucker rod pump installation will be improved by the use of a new sand filter design, the principle of which is based on the use of centrifugal force of a moving reservoir fluid. To determine the subtlety of cleaning the reservoir fluid from mechanical particles, it should be considered that the fluid velocity is the same as the particle velocity. To do this, we use the universal expression by analogy to our case for the stream function. To develop a specific filter (determination of structural dimensions) taking into account the well conditions, nomograms are developed taking into account all technical and technological conditions. The main advantage of the developed sand filter over other designs is the ability to pass formation fluid even when the cavity for collecting sand and the space between the filter housing and the pipe with radial channels are filled. The presence of the latter also does not affect the performance of the sucker rod pump, in the absence of jamming of the plunger in the cylinder.
Improving the method and equipment of thermo-acidic pulsation treatment
Authors: Khabibullin M Ya , Dubinskiy G S , Malyshev P M , Safiullina A R , Karimova A A
Published: November 2020

Initially, the method of thermo-acid pulsation was intended for heavily drained wells. But, as practice has shown, it can also be successfully used in the processing of wells of other categories, and depending on the diameter of the production string and the diameter of the reactor (jacket), the acid flow can be changed. A reactor with a diameter of 114 mm is usually used, but for 114 or 127 mm of the production string, a reactor with a diameter of 48 or 88 mm, respectively elongated, can be used to maintain the required capacity in order to accommodate the right amount of magnesium chips. The efficiency of acid treatment operations by pulsing is greater than the efficiency of thermo-acid treatments according to the results of calculations of both the increase in oil production and the duration of the wells at increased production.
Towards consistent high quality of engineering products
Authors: Kushnarev L
Published: November 2020

The low level of competitiveness and the constantly growing requirements of consumers for modern domestic technology indicate an urgent need to improve the quality of technological machinery and equipment produced by engineering. Ensuring a competitive world-class quality of the produced machines and equipment requires innovative development and modernization of the production organizational and technological system of mechanical engineering. Only the association of modern engineering companies is able to unit and direct the efforts of all participants in the process of creating machines towards a stable, continuous improvement in the quality of equipment. Encompassing quality control at all stages of the life cycle of a machine, the company as soon as possible and without any special financial expenses ensures the highest world level of quality of engineering products.

The goal of research is to comprehensively improve the quality of Russian-made machinery and equipment to the level of the best world analogues and higher based on the creation of an innovative production and technological system (complex), ensuring the as great as practicable level of quality of equipment at all stages of its life cycle.

The results of feasibility studies show, that a non-competitive level of quality of domestic equipment has developed and is maintained, despite the efforts of manufacturers, due to the long-term maintenance of the existing manufacturing system and production relations, requiring urgent and accelerated modernization. The main disadvantage of the existing manufacturing system in mechanical engineering is the isolation and fragmentation of enterprises and institutions working on the creation of machinery and equipment, the incompleteness of the production and technological chain, the lack of engineering and technical support of processes at all stages of the life cycle and, first of all, at the stage of operation of equipment. Therefore, in this article, we consider and propose a complex of priority organizational and technological measures providing the accelerated innovative development of the manufacturing system and improve the quality of Russian equipment above the level of the best world analogues.
Mathematical modeling of autonomous single-stage electro-hydraulic servo drive
Authors: Sosnovsky N , Van Hoa Nguyen
Published: November 2020

Annotation. The study is devoted to mathematical modeling of an autonomous single-stage electro-hydraulic servo drive. Two structural schemes of the drive are considered — simplified and more complex. The drive transient conditions of these two circuits are given.
Choice of finishing and strengthening treatment method for cycloidal screw surfaces for multi-product production conditions
Authors: Akulinichev P , Zenin I , Goncharov A
Published: November 2020

Annotation. This work is devoted to the study of modern methods of finishing complex profile surfaces, in particular, considered cycloidal screw surfaces, typical for single-screw machines of volume type. The operating conditions of parts with cycloidal screw surfaces are analyzed. In the article the technical requirements provided in the process of finishing are identified, and a method and device for implementing the method of finishing in the conditions of automated multi-product production are offered.
Development of methods for calculating cutting modes when processing the internal cycloidal screw surface using the original method used in drilling
Authors: Albov M , Goncharov A
Published: November 2020

Annotation. In this paper, we consider the problems that arise when using screw volumetric machines when working with chemically aggressive media. To solve this problem, it was proposed to use a chemically resistant material of fluoroplast for the manufacture of screw machine clips. To implement the process of creating clips, the kinematics of methodagerotor drilling of cycloidal screw holes was proposed, and a method for calculating processing modes was developed.
Development Prospects of High-Vacuum Mechanical Pumps Using Magnetic Bearing Support
Authors: Ochkov A , Hamadi M
Published: November 2020

The analysis of existing high-vacuum mechanical pumps with magnetic suspensions is carried out. The schemes and algorithms used for calculations for permanent magnetic suspensions (PMS) and active magnetic suspensions (AMS) are presented. Based on the results of the analysis, the relevance of the use of magnetic suspensions in high-vacuum mechanical pumps was evaluated, the development prospects of high-vacuum mechanical pumps with magnetic suspensions were noted.
Heat Resistance of Nickel-Manganese-Molybdenum Steel with Boron-Nitride Hardening
Authors: Eremin E N , Losev A S , Borodikhin S A
Published: November 2020

The metal of a coating made of steel N8G6M3FTB, deposited by a flux-cored wire containing boron nitride, titanium diboride and zirconium diboride, was studied. The metal was subjected to surface oxidation at a temperature of 900 °C. It was found that the average weight gain of the metal scale of such a coating at 900 °C is 0.0087 kg/(m2-h), which is 2.24 times less than that of steel 30Kh2V8F. It was revealed that the basis of metal scale, along with hematite and magnetite, are compounds with good protective properties. The results obtained show that the coating of steel N8G6M3FTB alloyed by boride compounds can be used for applying on the surface of parts operating at high temperatures.
Wear Resistance Structural Aspects of Materials after Laser Processing
Authors: Brover A V , Brover G I , Topolskaya I A
Published: November 2020

The conducted experiments show that the structures generated by laser processing are able to dissipate friction energy effectively with transformations at different structure levels. Thus, it becomes possible to manage surface strength and wear resistance of materials using the concept of “structural adaptability” of friction pairs that expands the range of normal friction and wear processes. The irradiated steel wear resistance is defined by its original hardness as well as its ability to deformation strengthening during friction. The temperature and strength load of irradiated steel surface layers through friction destabilize austenite towards y-xx transformation. This results from alloy carbide formation which causes depleted austenite by carbon, and contributing to its transformation into martensitic deformation. It’s necessary to regulate the amount and degree of remaining austenite stability in laser-hardened steel and alloys, applied to specific load conditions, that provides that required operation features.
Martensite Nucleation under Conditions of Austenite Superplasticity and External Magnetic Field
Authors: Pustovoit V N , Dolgachev Yu V , Aref’eva L P
Published: November 2020

The thermodynamic conditions corresponding to the instability of the crystal lattice before the martensitic transformation are analyzed. The instability of the crystal lattice before the martensitic transformation can be crucial for the occurrence of such a phenomenon as superplasticity of the martensitic transformation. Phenomena arising in an instability state are considered, a theoretical analysis of possible structural states detected experimentally is carried out. The phenomenon of superplasticity of the martensitic transformation under tension in the Ms
– Md
interval and the effect exerted by the magnetic field in this interval are described. As a result of exposure to an external magnetic field in this temperature range, the resulting magnetostrictive stresses in ferromagnetically ordered austenite nanoclusters under superplastic conditions initiate the formation of martensite.
An Analytical Model for Calculation of the Steel Hardness after Continuous Cooling
Authors: Maisuradze M V , Ryzhkov M A , Lebedev D I
Published: November 2020

A number of modern engineering steel grades were analyzed using the CCT diagrams plotted by means of the dilatometer. The statistical analysis of the experimental data allowed for the determination of the equations connecting the critical cooling rate to achieve fully martensitic microstructure and the martensite hardness with the chemical composition of the steel. The dependence of the steel hardness on the cooling rate in the range of 0.1…30 °C/s was determined. It was shown that this dependence had the logarithmic character for every studied steel grade. The equations connecting the coefficients of the logarithmic function with the chemical composition of steel were obtained.
Graphical Representation Reliability of Experimental Data Concerning to Structural and Surface Properties of Substances
Authors: Mayorov D V , Gorbacheva T T , Velyaev Yu O
Published: November 2020

Using experimental data on the pore distribution of a sample of magnesium-aluminum layered double hydroxide, various variants of their graphical representation are analyzed. It is shown that graphical interpretation of the obtained data in the coordinates dV/dD – D (dV/dlog(D) – D) or V – D is not of practical (scientific) interest and may lead to incorrect conclusions about the predominance of pores of a certain diameter in the sample and other errors. It is concluded that to avoid possible errors and provide the most complete information about the pore distribution of the studied samples, the presented graphic materials should be supplemented with histograms of the pore distribution.
Kinematic Viscosity of Melt Prepared from an Amorphous Fe72.5Cu1Nb2Mo1.5Si14B9 Ribbon
Authors: Kochetkova Ye A , Starodubtsev Yu N , Tsepelev V S
Published: November 2020

In this work, the viscosity of a melt prepared by melting an amorphous ribbon of Fe72.5Cu1Nb2Mo1.5Si14B9 alloy was studied. The amorphous ribbon was produced by rapid quenching of the melt, which was preheated at a temperature above (overheated mode) and below (not overheated mode) critical temperature Tk
. A hysteresis loop was found in the temperature dependence of viscosity, the widest part of which falls on a temperature from 1670 K to Tk
= 1760 K. In this temperature range, the melt has the highest activation energy and the largest cluster size. It has been proven that the melt viscosity increases with decreasing cluster size. In the low-temperature region, an overheated melt has the highest viscosity and the smallest cluster size comparable to the atomic size. It is shown that the heredity of the structure is preserved in the melt from the amorphous ribbon despite a number of structural transitions.
Correlation between Iron Substitution Degree in the M-Type Hexaferrites Based Crystal Structures and Dopant Content in the Crystal Growth Feeding Melt
Authors: Zhivulin V , Zaitseva O , Vinnik D
Published: November 2020

In this paper the results of the investigation of the properties of the obtained crystals of hexaferrites grown from the sodium carbonate flux doped with 1 – 12 mass % of metal oxide (aluminum, titanium, manganese, cobalt, and copper) are presentd. The ratio of concentration of doping elements in the crystal and in the feeding melt has strong dependence on nature of dopant. Doping metals can be ordered in a line Ti > Al > Mn > Co > Cu where Ti has maximal ratio of 0.5 and Cu of 0.005. Hexagonal M type ferrites attract the reseachers interest due to great capacity for the accommodation of different metals at high doping levels that provides a possibility for wide tuning of physical properties by cation substitution.
Determination of Mechanical Characteristics Plasma Hardened Wheel Steel
Authors: Bogomolov A V , Kanaev A T , Sarsembaeva T E
Published: November 2020

A technique for measuring the mechanical properties of plasma-hardened wheel steel with nanoindentation is applied. The purpose of the work is to demonstrate and substantiate the serious differences between the mechanical properties and behavior of materials in nano-volumes from those obtained in traditional macroscopic tests. The features of measuring mechanical properties – hardness, Young’s modulus, elastic recovery – affecting the wear resistance of the surface layers of the material are given. Measurement of the physic mechanical properties of the material makes it possible to evaluate and select the optimal technology for surface modification by surface plasma hardening. It is noticed that the objectivity of determining the hardness, elastic modulus, elastic recovery and flow stress depends on the parameters of the measuring equipment used and strict adherence to the requirements for the imprint depth depending on the thickness of the hardened layer. The studies carried out on wheel steel samples from the rim and from the ridge of a railway wheel subjected to surface plasma hardening under the same conditions. The HV and H of the wheel rim are greater than the corresponding values of the flange, and the young modulus of the wheel flange, on the contrary, is greater for the flange.
The Effect of Temperature and Roasting Time on the Conversion of Zinc Ferrite to Zinc Oxide in the Electric Arc Furnace Dust
Authors: Ryazanov A G , Senin A V , Kornilov N A
Published: November 2020

The dust of electric arc furnaces (EAF-dust) contains significant amounts of zinc in the form of various chemical compounds. Therefore, dust can be used as a raw material for zinc extraction. EAF-dust containing 20 wt.% Zn has been studied. The effect of dust roasting with Ca O and Na2CO3 additives on the degree of conversion of ZnFe2O4 to Zn O was studied experimentally. The effect of the roasting temperature of 700, 850 and 1000 °C and the roasting duration of 1, 2 and 3 hours were established. Ca O and Na2CO3 additives in dust contribute to the destruction of ZnFe2O4 due to the formation of Ca2Fe2O5 and NaFeO2. After treatment, zinc is presented in the form of acid soluble zinc oxide. The content of acid-soluble zinc increases from 25% in the initial dust to 97 – 98% in the roasting product (“cinder”) under optimal roasting conditions.
Effect of External Integrated Treatment on the Structure and Properties of the Castings from Steel Grade 35L
Authors: Efimov A V , Potapov M G , Kuts N A
Published: November 2020

The methods of influence of external physical and thermophysical factors on the cast steel structure formation are considered in the paper. High-temperature processing of the melt is an effective method of heat treatment. It improves a wide range of mechanical and operational properties of finished castings. The parameters of high-temperature treatment were established experimentallyin the course of this study. Its influence on the structure and properties of 35L steel castings has been shown. The usage of a nanosecond electromagnetic pulse during the crystallization of a casting in the mold is a method of dynamic action on the metal liquid phase. The parameters of nanosecond electromagnetic pulse processing during crystallization were determined by the technical capabilities of the electromagnetic pulse generator.

The study of the properties and structure of samples cast from a melt processed by electromagnetic pulses confirms the improvement of the mechanical and operational properties of castings by improving the primary cast metal structure. The influence of metal overheating, nanosecond electromagnetic pulse, and temperature-time holding on the structure and mechanical properties of castings is revealed. The modes of thermal holding (final technological heat treatment of the metal) were determined experimentally using the method of differential scanning calorimetry. The paper presents the results of changes in improving the properties of cast products due to the use of optimal modes of external complex influences.
Simulation of Physical Fields in Induction Hardening Technology - from Digital Twin to New Technology
Authors: Perevalov Yu , Demidovich V
Published: November 2020

A new technology for the final induction heat treatment of large mill rolls has been developed. When designing this technology, installation and control system, a digital twin of the system was created on the basis of combined numerical models of electromagnetic and temperature fields in cylindrical axially symmetrical systems. The final heat treatment of mill rolls consists in a two-stage, multi-frequency induction hardening of body of large rolls. The developed digital twin of the system allows one to evaluate the key features arising during induction hardening, such as temperature distribution, hardness of the hardened layer, stresses that arise during hardening. The design of induction systems through digitalization allows one to improve the design, equipment composition and heat treatment mode to achieve maximum quality and minimize energy costs.
Obtaining of Pigment-Quality Magnetite from Sintering Process Red Mud
Authors: Shoppert A A , Loginova I V , Napol’skikh J A
Published: November 2020

The limited availability of high-quality bauxite and, at the same time, the formation of a considerable amount of harmful red mud (bauxite residue) causes to develop cost-effective technologies for bauxite processing. Selective separation of iron from red mud allows solving this problem and producing marketable products in the form of pigment-quality magnetite. In this context, the possibility of the pigment-quality magnetite obtaining by the interaction of freshly precipitated iron hydroxide (III) of the sintering process red mud with ferrous iron ions in an alkaline medium is studied. It was found that the optimal parameters of the process are: temperature = 90°C; duration = 4 hours; a ratio of ferrous iron to stoichiometric quantity = 70 %. The yield of the magnetic concentrate under optimal conditions was 69.3 %, and the content of magnetite in concentrate was 47.7 %.
Study of the Manufacturing Options for an Asymmetric Plate Made of 12X18N10T Steel
Authors: Shimov G V , Bushueva N I
Published: November 2020

The analysis of possible options for manufacturing an asymmetric plate of 12X18N10T steel is presented. A phenomenological model of damage accumulation was used to analyse the probability of metal micro – and macro – destruction. The results of FEM modelling of technological processes of plate manufacturing are presented. Due to these results were made the conclusions about feasibility of their application based on the metal damage calculation. The choice of a rational technology to produce a plate is justified, in which the greatest metal ductility reserve takes place at a dangerous point. According to the proposed scheme, an experimental batch of plates have been made.
Computer Simulation of the Metal Deformation Process in an Equal Channel Step Matrix with Additional Backpressure
Authors: Naizabekov A , Lezhnev S , Panin E
Published: November 2020

Theoretical studies of the process of round cross-section billets pressing in equal-channel step matrices of various designs by modeling are carried out. It was found that the backpressure created by the narrowing of the matrix channels has a favorable effect on the stress-strain state of the metal, which in turn allows for better processing of the structure of the deformable metal. It is also found that when using an equal-channel step matrix with narrowing channels, the deformation force increases, which cannot be attributed to the positive sides of these matrix designs. It was found that the most optimal results were obtained when using an equal-channel step matrix with a narrowing of the intermediate channel.
Laser Powder Cladding Complex: Principles of Advanced Automated Control
Authors: Chkalov R V , Chkalova D G
Published: November 2020

Currently, the laser powder cladding process is one of the most promising methods for producing wear and corrosion resistant sealing surfaces of high hardness. To solve the problem of high-quality automated production of coatings, that meet specified requirements, on the surfaces of critical parts, it is necessary to identify key factors, as well as determine the contribution of each of them in the process of laser powder cladding. In view of the foregoing, the urgent task is to develop an integrated system that allows monitoring and recording parameters of ongoing physical processes, as well as ensuring reproducibility of experimental results. Since such an installation includes many disparate technical units and transition modules of various integration levels, each of which has its own functionality, a specialized software package has been developed, the purpose of which is to combine individual components into a single organized and controlled system. As an approbation of the experimental complex work, the results of laser cladding process are shown.
Process Design for the Wire Arc Additive Manufacturing of a Compressor Impeller
Authors: Kulikov A A , Sidorova A V , Balanovskiy A E
Published: November 2020

Additive manufacturing or 3D printing slowly and steadily replaces traditional subtractive manufacturing, where parts are manufactured by sequentially removing pieces of the workpiece material. In 3D printing, the material is added in layers, which enables producing parts of complex geometric shapes made from expensive metals with higher productivity and economic efficiency. In order to perform 3D printing on an industrial scale, it is necessary to combine robotics with 3D printing software. This article presents the results of the process design for 3D printing of a compressor impeller prototype. A detailed methodology of customization of the KUKA industrial robot for the 3D printing process is given. Once the impeller model was created in the CAD environment, it was cut into layers in the slicer program. Special software for offline programming of industrial robots was used to translate the program into the robot language and perform 3D printing using an experimental robotic complex. As a result, a prototype of a low-carbon steel compressor impeller was printed using a welding machine and steel wire. The developed technological process was successful and proved that an industrial robot combined with a welding machine can be used as an industrial 3D printer for printing real machine parts.
Investigation of the Effect of the Lighting Step on the Strength of a Ceramic Product in 3D Printing
Authors: Yerezhep D , Piterskov P , Pobirokhin G S
Published: November 2020

The subject of this study is to assess the effect of such a 3D printing parameter by the SLA method as the lighting step (the distance between the lines of the beam motion when lighting the layer) on the mechanical properties of a ceramic object. For the study, the lighting step of 50 μm, 75 μm and 100 μm was used. The dependencies such as the Mises stresses, the displacements of the layers of the printed object relative to each other, and also the pressure arising in the layer were compared. To exclude edge effects, dependences were evaluated in the range from 500 μm to 1500 μm of the surface of the object layer, the layer thickness was 100 μm. These studies are necessary to optimize the 3D printing process, to minimize internal stresses and pressures in the printed object. The use of optimal printing parameters will improve the results of heat treatment and obtain objects with the required surface quality.
Enhancement of Deposition Process Controlling in Electron Beam Metal Wire Deposition Method
Authors: Shcherbakov A V , Rodyakina R V , Klyushin R R
Published: November 2020

The urgency of improving control systems for electron beam metal wire deposition method is proved in terms of creating methods for controlling the geometric parameters of deposited layer. It is shown that to solve this problem in electron beam metal wire deposition method, it is advisable to use reflected electron signal detection when scanning the deposited layer. Using a mathematical model based on the application of continuous loss approximation and Monte-Carlo method, the probe characteristics recorded during cylindrical layer scanning are investigated. Experimental verification of the results obtained was carried out using an electron-beam technological installation. The effect of the distance between the layer and electron collector on the recorded signals is investigated. The possibility of using this method for simultaneous control of deposited layer height and width is shown.
Study on the surface packing cementation aluminizing processes of Q345 steel in an air environment
Authors: Xingping Fan
Published: November 2020

To address the requirement of a vacuum environment or a protective atmosphere in the process of aluminizing, pack cementation was used to aluminize the surface of Q345 steel in an air environment. The aluminized coating with a large hardness and corrosion resistance was prepared on the surface of Q345 steel. The influence of the aluminizing temperature and the holding time on the surface quality and thickness of the aluminized coating was studied to determine the optimum conditions for aluminizing. The surface quality of the coating was observed by an electron microscope and the thickness of the aluminized coating was measured. The main elemental distribution of the coating was also analyzed by an energy spectrometer. The phase composition of the aluminized coating was analyzed by an x-ray diffractometer and the change in coating hardness was measured by a microhardness tester. The results showed that when the holding time was 3 h and the heating temperature was 800 °C, the obtained thickness of the aluminized coating was 180 μm, with good quality, excellent hardness, and corrosion resistance.
Tuning of physical properties of multifunctional Mg-Zn spinel ferrite nanocrystals: a comparative investigations manufactured via conventional ceramic versus green approach sol-gel combustion route
Authors: Khirade Pankaj P , Chavan Apparao R , Somvanshi Sandeep B , Kounsalye Jitendra S , Jadhav K M
Published: November 2020

This work focused on the impact of synthesis routes on the structural, microstructural, magnetic, electrical and dielectric characteristics of Mg1−x
Zn
x
Fe2O4 (x = 0.00, 0.25, 0.50, 0.75, and 1.00) nanocrystals manufactured via the ceramic and green approach sol–gel route. The powder X-ray diffraction (XRD) analysis reveals that the entire synthesized ferrite solids crystallize in single phase spinel structure. The XRD outcomes highlight the impact of the synthesis routes and Zn2+ replacement on the morphology, crystallite size and structural parameters of magnesium nano-ferrites. The transmission electron microscopy (TEM) images illustrate that the process of synthesis causes extensive lessening of grain and crystallite sizes. The magnetic study reveals that the magnetic properties of magnesium ferrite can be tuned by zinc substitution. The saturation magnetization (Ms), retentivity (Mr), coercive force (Hc) and magneton number diminutions meaningfully with the replacement of diamagnetic Zn2+ ions in Mg-ferrite for both the synthesized systems. The deterioration of magnetic parameters with Zn2+ substitution can be clarified on the base of the random spin canting model. Likewise, the magnetic parameters, enhanced meaningfully for sol-gel derived samples this can be attributed due to decline of crystallite size effect. The DC electric resistivity displays NTCR behaviour like ideal semiconducting materials for all the produced samples. The DC resistivity values of sol-gel produced samples were found to be little bit higher than that of ceramic derived samples. The experimental dielectric constant as a function of frequency behaviour can be elucidated with the support of the heterogeneous model of the polycrystalline structure of ferrites. The dielectric constant and loss tangent decreases with Zn2+ content for both the systems. The dielectric constant enhances for sol-gel derived samples; however, lower values of loss tangent were found. The obtained outcomes can be suitable for multifunctional applications in electronics devices and biomedical field.
Astronomy for development
Authors: Dalgleish Hannah
Published: November 2020

Hannah Dalgleish examines ways in which astronomy can help to forge a sustainable future for life on Earth.
Publishing now and in the future
Authors: Clube Kim
Published: November 2020

Kim Clube, editorial office manager, reviews the changing faces of the RAS journals.
Astronomical locomotives
Authors: Williams Iwan
Published: November 2020

Iwan Williams examines the surprising range of astronomical names given to steam locomotives of the 19th century.