Moscow Aviation Institute

This paper presents a table for the surface tension of water from 0.01 to 374 °C and an interpolating equation which represents the values in the table to well within their estimated uncertainties. The table of values and the interpolating equation are those recommended by the International Association for the Properties of Steam (IAPS) in its recent official release. The experimental measurements of the surface tension of water and their uncertainties are discussed, as is the development of the IAPS tables.

This chapter contains sections titled: Theory of Free Turbulence, Prandtl's Old Theory of Free Turbulence, Application of Prandtl's Old Theory of Free Turbulence to Heat and Diffusion Problems, Theory of the Boundary Layer of a Two-Dimensional Turbulent Jet of Incompressible Fluid, Tollmien's Plane Turbulent Source, Tollmien's Axially Symmetric Turbulent Source, Distribution of Temperature and Constituent Concentration in the Main Region of a Jet According to Prandtl's Old Theory of Free Turbulence, Taylor's Free Turbulence Theory and Its Application, Prandtl's New Theory of Free Turbulence and Its Applications, Reichardt's Theory of Turbulent Mixing and Its Application, Determination of the Temperature Profile in a Jet on the Basis of the New Prandtl-Gortler Theory of Turbulence and Reichardt's Theory

This article concerns the foundations of a new technology for surface modification of metallic materials based on the use of original sources of low-energy, high-current electron beams. The sources contain an electron gun with an explosive-emission cathode and a plasma anode, placed in a guide magnetic field. The acceleration gap and the transportation channel are prefilled with plasma with the use of spark plasma sources or a low-pressure reflected discharge. The electron-beam sources produce electron beams with the parameters as follows: electron energy 10–40 keV; pulse duration 0.5–5 μs; energy density 0.5–40 J/cm2, and beam cross-section area 10–50 cm2. They are simple and reliable in operation. Investigations performed with a variety of constructional and tool materials (steels, aluminum and titanium alloys, hard alloys) have shown that the most pronounced changes of the structure-phase state occur in the near-surface layers quenched from the liquid state, where the crystallization front velocity reaches its maximum. In these layers partial or complete dissolving of second phases and formation of oversaturated solid solutions and ordered nanosized structures may take place. This makes it possible to improve substantially the electrochemical and strength properties of the surface layers. It has been established that the deformation processes occurring in the near-surface layers have the result that the thickness of the modified layer with improved strength properties is significantly greater than that of the heat-affected zone. Some examples of the use of low-energy, high-current electron beams for improving the performance of materials and articles are given.

This monograph is based on the authors' studies carried out to investigate one of the most promising trends in the theory of ill-posed problems: namely, iterative regularization and its application to inverse heat transfer problems. Effective methods for solving inverse problems have allowed researchers to simplify experiments considerably, and to increase the accuracy and confidence of results in experimental data processing. The authors discuss a broad range of problems concerned with both the theory of regularizing gradient algorithms and peculiarities of their application to the most often encountered inverse problems of reconstruction of external heat fluxes and the identification of mathematical models for heat transfer processes. <br><br><br><br>306 pages, <big> &#169; 1995</big><br>

The main physical features and processes determining stationary plasma thrusters (SPTs) performance levels are considered in this paper, including ionization processes and ion dynamics in the accelerating channel, as well as the results of SPT design optimization, factors determining SPT lifetime, and the possibilities of simulating the plasma particle dynamics in the accelerating channel and in its plume. Nomenclature B, Br, Bopt = magnetic eld induction, its radial component, and the optimum B value, respectively d, bc = accelerating channel mean diameter and its width, respectively E, Ez = electric eld intensity and its z component, respectively e = electron charge F = thrust hc = cycloid height, 22mE /eBz r Id = discharge current Ii = ion current Im = current corresponding to the mass ow rate through the accelerating channel, (mÇ a/M)e jez = z component of electron current density jH = Hall current density j ’ = normal ion current component at surface Ka, , Kh, KwKa9 = numerical factor KM = scaling factor Ks = sputtering yield factor Kl &amp;lt;&amp;lt; 1 = numerical factor Kj = surface erosion rate factor La = length of accelerating channel L*a = length of the self-consistent accelerating layer LB = characteristic width of Br(z) distribution l, l0 = magnetic system element sizes M = ion and atom mass m = electron mass mÇ, mÇ a, mÇ i = total mass ow rate in a thruster, mass ow rate through the accelerating channel, and mass ow rate of ions, respectively Na = atom ow rate density, na?Vaz Nd = discharge power, Ud? Id Nsp = speci c power, Nd/Sc na, ni, ne = concentrations of atoms, ions, and electrons, respectively q = ion charge r̄, Dr ̄ = normalized coordinates Sc ’ pd?bc = accelerating channel cross-sectional area SM = magnetic core element cross-sectional area Sv(g, «i) = volumetric sputtering yield

The present book has evolved from the well-known basic reference Handbook of Physical Properties of Liquids and Gases, which has been published in four editions in the Soviet Union, the United States, and Japan, between 1963 and 1975.Since the last edition, both the scope and the experimental material and the methods of processing and compilation of data have undergone considerable changes. The experimentally studied regions of the reference parameters have been expanded to cover higher pressures as well as the regions of both high and very low temperatures, including the extreme states. Data are given both in the form of the detailed tables and correlation equations demonstrating the temperature and pressure dependencies of the properties. In some regions extrapolated values are given, which, as a rule, are indicated in the text. In a few extreme regions the property values were estimated theoretically. A thorough, easy-to-use cross-referenced index is included. <br><br><br><br>1370 pages, <big> &#169; 1996</big><br> <br>

It has recently been found that Dirac and Weyl metals are characterized by an unusual weak-field longitudinal magnetoresistance: large, negative, and quadratic in the magnetic field. This has been shown to arise from the chiral anomaly, i.e., nonconservation of the chiral charge in the presence of external electric and magnetic fields, oriented collinearly. In this paper we report on a theory of this effect in both Dirac and Weyl metals. We demonstrate that this phenomenon contains two important ingredients. One is the magnetic-field-induced coupling between the chiral and the total (or vector, in relativistic field theory terminology) charge densities. This arises from the Berry curvature and is present in principle whenever the Berry curvature is nonzero, i.e., is nonspecific to Dirac and Weyl metals. This coupling, however, leads to a large negative quadratic magnetoresistance only when the second ingredient is present, namely when the chiral charge density is a nearly conserved quantity with a long relaxation time. This property is specific to Dirac and Weyl metals and is realized only when the Fermi energy is close to Dirac or Weyl nodes, expressing an important low-energy property of these materials, emergent chiral symmetry.

Adirect method for a real-time generationof near-optimal spatial trajectories of short-termmaneuvers onboard a ying vehicle with predetermined thrust history is introduced. The paper starts with a survey about the founders of the direct methods of calculus of variations and their followers in ight mechanics, both in Russia and in the United States. It then describes a new direct method based on three cues: high-order polynomials from the virtual arc as a reference function for aircraft’s coordinates, a preset history of one of the controls (thrust), and a few optimization parameters. The trajectory optimization problem is transformed into a nonlinear programming problem and then solved numerically using an appropriate algorithm in accelerated scale of time. A series of examples is presented. Calculated near-optimal trajectory is compared with real ight data, and with the solution obtainedbyPontryagin’smaximumprinciple.Fast convergenceof the numerical algorithm,whichhasbeen already implemented and tested onboard a real aircraft, is illustrated. Nomenclature aik = polynomial coef cients g = accelerationdue to gravity J = cost function j = quantity pertaining to the j th time node

The dynamic characteristics of liquid-rocket injectors in the presence of intense combustion-chamber and propellant feed-line oscillations are discussed. Liquid-propellant injectors always function in nonsteady e ow environments and are therefore considered as a dynamic component of an engine. In addition to its main function of injecting propellant and preparing a combustible mixture, an injector simultaneously acts as a sensitive element that may generate and modify e ow oscillations because of its intrinsic unsteadiness and interactions with the combustion-chamber and feed-system dynamics. This paper also addresses nonlinear effects of nonstationary processes occurring in injectors. Various mechanisms for driving self-pulsations in both liquid and gas ‐liquid injectors are summarized systematically. A vital problem of bifurcational unsteadiness of injector operation is considered.

One result of the intake and settlement of migrants is the formation of culturally plural societies. In the contemporary world, all societies are now culturally plural, with many ethnocultural groups living in daily interaction. A second result is that intercultural relations become a focus of public and private concern, as the newcomers interact with established populations (both indigenous and earlier migrants).

It has been known that the lack of excellent corrosion resistance is the key problem restricting the wide application of Mg−Li alloys. Based on a quantity of literature about corrosion behavior of Mg−Li alloys, this review elaborates the factors affecting the corrosion behavior of Mg−Li alloys and the processing methods for improving corrosion resistance. The corrosion characteristics of Mg−Li alloys are described firstly. Then, it is explained that the grain size, orientation, second phase, and surface film strongly influence corrosion performance, which can be tailored by alloying, plastic deformation, and heat treatment. Further in-depth discussion about the corrosion mechanisms for Mg−Li alloys was also presented. Finally, important points of improving corrosion resistance are suggested.

Optimal experiment design is the definition of the conditions under which an experiment is to be conducted in order to maximize the accuracy with which the results are obtained. This paper summarizes a number of methods by which the parameters of the mathematical model of the system are estimated and describes the application of the Fisher information matrix. Examples are given for thermal property estimation in which the estimation is affected both by measurement noise, which is present during any experiment, but also by uncertainties in the parameters of the model used to describe the system.

The full-bridge isolated current fed converter with active clamp advantages are in its ZVS capability and its well-clamped operation devoid of voltage overshoot on the converter switches and the rectifier diodes. Another relative advantage is that the isolation transformer magnetising current does not have a DC component. An analysis defines the converter voltage transfer ratio taking into consideration the switches' parasitic capacitance and the transformer leakage and magnetizing inductance. The analysis defines the selection criteria for power stage component values. Two breadboard models were built and tested utilizing the current fed full bridge topology. One model was realized as a DC/DC and the other as a single stage PFC. The models' experimental data confirmed calculations.

The current study examines the contribution of left–right (or liberal–conservative) ideology to voting, as well as the extent to which basic values account for ideological orientation. Analyses were conducted in 16 countries from five continents (Europe, North America, South America, Asia, and Oceania), most of which have been neglected by previous studies. Results showed that left–right (or liberal–conservative) ideology predicted voting in all countries except Ukraine. Basic values exerted a considerable effect in predicting ideology in most countries, especially in established democracies such as Australia, Finland, Italy, United Kingdom, and Germany. Pattern of relations with the whole set of 10 values revealed that the critical trade-off underlying ideology is between values concerned with tolerance and protection for the welfare of all people (universalism) versus values concerned with preserving the social order and status quo (security). A noteworthy exception was found in European postcommunist countries, where relations of values with ideology were small (Poland) or near to zero (Ukraine, Slovakia).

Abstract The area of fractional calculus (FC) has been fast developing and is presently being applied in all scientific fields. Therefore, it is of key relevance to assess the present state of development and to foresee, if possible, the future evolution, or, at least, the challenges identified in the scope of advanced research works. This paper gives a vision about the directions for further research as well as some open problems of FC. A number of topics in mathematics, numerical algorithms and physics are analyzed, giving a systematic perspective for future research.

During the last few years the Moscow Aviation Institute (Russia) and the Industrial Technology Research Institute (Taiwan) have worked jointly on the development of ultrawideband (UWB) medical radars for remote and contactiess monitoring of patients in hospitals. Preliminary results of these works were published in [1]. As of the present, several radars have been produced and tested in real conditions in hospitals in Russia and Taiwan. Some results of these tests are given.

We review research investigating the application of intense pulsed ion beams (IPIBs) for the surface treatment and coating of materials. The short range (0.1–10 μm) and high-energy density (1–50 J/cm2) of these short-pulsed (⩽1 μs) beams (with ion currents I=5–50 kA, and energies E=100–1000 keV) make them ideal in flash heating a target surface, similar to the more familiar pulsed laser processes. IPIB surface treatment induces rapid melt and solidification at up to 1010 K/s causing amorphous layer formation and the producing nonequilibrium microstructures. At higher energy density the target surface is vaporized, and the ablated vapor is condensed as coatings onto adjacent substrates or as nanophase powders. Progress towards the development of robust, high-repetition rate IPIB accelerators is presented.

cations with a high configurational mixing entropy were prepared by solid-phase synthesis. Phase purity and unit cell parameters were obtained from XRD and analyzed versus the average ionic radius of the iron sublattice. The crystallite size varied around ∼4.5 μm. A comprehensive study of the magnetization was realized in various fields and temperatures. The saturation magnetization was calculated using the Law of Approach to Saturation. The accompanying magnetic parameters were determined. The magnetic crystallographic anisotropy coefficient and the anisotropy field were calculated. All investigated magnetization curves turned out to be nonmonotonic. The magnetic ordering and freezing temperatures were extracted from the ZFC and FC curves. The average size of magnetic clusters varied around ∼350 nm. The high values of the configurational mixing entropy and the phenomenon of magnetic dilution were taken into account.

The practical aspects and prospects of application of ionic liquids as heat transfer fluids are discussed. The physicochemical properties of ionic liquids (heat capacity, thermal conductivity, thermal and radiation stability, viscosity, density, saturated vapour pressure and corrosion activity) are compared with the properties of some commercial heat transfer fluids. The issues of toxicity of ionic liquids are considered. Much attention is paid to known organosilicon heat transfer fluids, which are considered to have much in common with ionic liquids in the set of properties and are used in the review as reference materials. The bibliography includes 132 references.

Chronic liver disease (CLD), manifested as hepatic injury, is a major cause of global morbidity and mortality. CLD progresses to fibrosis, cirrhosis, and-ultimately-hepatocellular carcinoma (HCC) if left untreated. The different phenotypes of CLD based on their respective clinical features and causative agents include alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), metabolic-associated fatty liver disease (MAFLD), and drug-induced liver injury (DILI). The preferred treatment modality for CLD includes lifestyle modification and diet, along with limited pharmacological agents for symptomatic treatment. Moreover, oxidative stress (OS) is an important pathological mechanism underlying all CLD phenotypes; hence, the use of antioxidants to manage the disease is justified. Based on available clinical evidence, silymarin can be utilized as a hepatoprotective agent, given its potent antioxidant, antifibrotic, and anti-inflammatory properties. The role of silymarin in suppressing OS has been well established, and therefore silymarin is recommended for use in ALD and NAFLD in the guidelines approved by the Russian Medical Scientific Society of Therapists and the Gastroenterology Scientific Society of Russia. However, to discuss the positioning of the original silymarin in clinical guidelines and treatment protocols as a hepatoprotective agent for managing CLD concomitantly with other therapies, an expert panel of international and Russian medical professionals was convened on 11 November 2020. The panel reviewed approaches for the prevention and treatment of OS, existing guidelines for patient management for CLD, and available evidence on the effectiveness of silymarin in reducing OS, fibrosis, and hepatic inflammation and presented in the form of a narrative review. Key messagesAn expert panel of international and Russian medical professionals reviewed existing guidelines for ALD, NAFLD, MAFLD, and DILI to establish consensus recommendations that oxidative stress is the common pathophysiological mechanism underlying these conditions.The panel also discussed the positioning of original silymarin in clinical guidelines and treatment protocols as a hepatoprotective agent for managing CLD concomitantly with other therapies.The panel reviewed the effectiveness of 140 mg original silymarin three times a day in reducing oxidative stress in chronic liver diseases such as ALD, NAFLD, MAFLD, and DILI.