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Regular version of the site
Of all publications in the section: 467
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Article
Kostyukevich Y., Vlaskin M., Borisova L. A. et al. European Journal of Mass Spectrometry. 2018. Vol. 24. No. 1. P. 116-123.

Recent research has revealed that more than 1.3 billion tons of food is wasted globally every year. The disposal of such huge biomass has become a challenge. In the present paper, we report the production of the bio-oil by hydrothermal liquefaction of three classes of food waste: meat, cheese and fruits. The highest yield of the bio-oil was observed for meat (∼60%) and cheese (∼75%), while for fruits, it was considerably low (∼10%). The molecular composition of the obtained bio-oil was investigated using ultrahigh resolution Fourier Transform Ion Cyclotron Resonance mass spectrometry and was found to be similar to that obtained from algae. Several thousand heteroatom compounds (N, N2, ON2, etc. classes) were reliably identified from each sample. It was found that bio-oils produced from meat and cheese have many compounds (∼90%) with common molecular formulas, while bio-oil produced from fruits differs considerably (∼30% of compounds are unique).

Added: Jan 30, 2018
Article
Aksenov S. A., Sorgente D. Procedia Engineering. 2017. Vol. 207. P. 1892-1897.

In this work, a new experimental-numerical technique is developed in order to investigate the constitutive behaviour of a sheet material in conditions of superplastic forming. The principal feature of this technique is that unlike classical tensile testing it allows one to obtain stress-strain curves for a material formed in biaxial tension conditions produced by free bulging process. These conditions are much closer to the ones that the material undergoes during the superplastic forming process. Consequently, they give more accurate information about the material behaviour than the ones coming from tensile tests data. The drawback is that the strain (and similarly its time derivative) cannot be directly measured and controlled during free bulging test but its value has to be derived from other macroscopic measurement. Towards this end, a blow forming machine was equipped with a position transducer for the measurement of the dome height during the test. In order to control the stress in the dome apex at a predetermined level the applied pressure was continuously adjusted to current dome height using a special algorithm. After the test, the dome height data were processed to obtain the evolution of stress, strain and strain rate at the dome apex as well as the stress strain curves for constant referenced strain rates. The tests were performed on superplastic aluminium alloy (ALNOVI-U) sheets of 1.35 mm initial thickness at 500 °C. Using the data from two tests with different strain rate paths the stress-strain curves and the strain rate sensitivity index evolution were calculated for two constant referenced strain rates. The obtained constitutive data were verified by finite element simulation of a blow forming.

Added: Feb 20, 2018
Article
Kostyukevich Y., Stavitskaya A., Zherebker A. et al. European Journal of Mass Spectrometry. 2017. Vol. 23. No. 4. P. 152-155.

Natural complex mixtures such as oil and dissolved organic matter play an important role in the economy and in the global carbon cycle. One of the most promising approaches for the investigation of the chemical structure of such substances is the combination of the high-resolution mass spectrometry and selective chemical reactions. Here, we report the investigation of the ozonation products of natural complex mixtures using Fourier transform ion cyclotron resonance mass spectrometry. Ozonation of crude oil results in the appearance of the new compounds with high content (up to 9 atom) of oxygen. Isotopic exchange reaction showed that those oxygen stem from the carbonyl groups. Ozonation of the dissolved organic matter leads to the destruction of the substance and shift towards the region of the saturated compounds.

Added: Jan 30, 2018
Article
Fabik R., Kliber J., Mamuzic I. et al. Metalurgija. 2012. Vol. 51. No. 3. P. 341-344.

The aim of this paper is to critically assess the potential of mathematical modelling which uses finite element method software for solving operation problems in the hot rolling of flat and long products. We focused on concrete issues faced by rolling plants in the Moravian-Silesian region (Czech Republic). The investigation was always combined with field or pilot measurements or laboratory experiments.

 

Added: Dec 17, 2012
Article
Mamontov A. V., Nefedov V. N., Simonov V. Measurement Techniques. 2015. No. Volume 58, Issue 10. P. 1156-1159.

The results of theoretical and experimental investigations in the area of high performance microwave technologies for the heat treatment of sheet materials are presented. Two-dimensional periodic slow-wave systems are used as the heating elements of the microwave devices. The disagreement between the theoretical and experimental temperature distribution characteristics in the sheet material and the temperature deviation from the nominal value does not exceed 3% and 5%, respectively.

Added: Feb 9, 2016
Article
Proskuryakova L. N., Kovalev A. Applied Energy. 2015. No. 138. P. 450-459.

There is a widespread assumption in energy statistics and econometrics that energy intensity and energy efficiency are equivalent measures of energy performance of economies. The paper points to the discrepancy between the engineering concept of energy efficiency and the energy intensity as it is understood in macroeconomic statistics. This double discrepancy concerns definitions (while engineering concept of energy efficiency is based on the thermodynamic definition, energy intensity includes economic measures) and use. With regard to the latter, the authors conclude that energy intensity can only provide indirect and delayed evidence of technological and engineering energy efficiency of energy conversion processes, which entails shortcomings for management and policy-making. Therefore, we suggest to stop considering subsectoral, sectoral and other levels of energy intensities as aggregates of lower-level energy efficiency. It is suggested that the insufficiency of energy intensity indicators can be compensated with the introduction of thermodynamic indicators describing energy efficiency at the physical, technological, enterprise, sub-sector, sectoral and national levels without references to any economic or financial parameters. Structured statistical data on thermodynamic efficiency is offered as a better option for identifying break-through technologies and technological bottle-necks that constrain efficiency advancements. It is also suggested that macro-level thermodynamic indicators should be based on the thermodynamic first law efficiency and the energy quality problem may be left to enterprise-level thermoeconomic optimization.

Added: Apr 21, 2014
Article
Chumachenko E. N., Portnoi V., Logashina I. V. Metallurgist. 2015. Vol. 59. P. 69-75.

Different test methods are described to determine the mechanical properties of materials in the superplastic state. The flow stress depends on strain and strain rate, the structural parameter of the materials, and temperature. The rheology and mechanics of superplastic deformation are discussed. The methods have been checked for reliability and produced good results in testing titanium alloys and constructing mathematical models as part of an order submitted by the company EADS (Airbus). The information given on the test methods and the subsequent approximation of materials’ mechanical properties is of considerable interest for making reliable predictions of the deformation of materials during shaping operations. © 2015 Springer Science+Business Media New York

Added: Sep 7, 2015
Article
Kychkin A., Vaysman Y., Surkov A. et al. IOP Conference Series: Earth and Environmental Science. 2019. Vol. 317. International Conference on Sustainable Cities 012001. 2019. P. 1-8.

The paper is devoted to the development of a methodology to evaluate the possible locations of wind generators using GIS technologies for the climatic conditions of the Western Urals. A model of the wind generator operation in the electrical network using the OpenModelica simulation environment has been built. Recommendations on the use of a wind generator and a feasibility study of its use on the base of an energy-efficient autonomous research module (EEARM) are worked out.

Added: Oct 14, 2019
Article
Kurkin A., Belyakov V., Makarov V. et al. Science of Tsunami Hazards. 2016. Vol. 35 . No. 2. P. 68 -83.

In our paper we describe some of the methods of the last 25 years which have been used extensively to examine and register tsunami traces - particularly by satellite imaging of coastal zones before and after a tsunami has struck, thus assessing quickly the extent of coastal inundation over large areas without the need of a site visit. Nearly all countries bordering oceans, seas and bodies of water have established digital systems of water level registration in the range of tsunami waves. In this article we describe methods of tsunami detection and runup measurements, some based on our own participation in post-tsunami surveys. Also, we discuss the possibility of using robotic systems to survey tsunami traces in hard-to-reach places. 

Added: Jul 7, 2016
Article
Kovalev A. Energy. 2016. Vol. 100. P. 129-136.

The direct relationship between thermodynamic entropy and economic scarcity is only valid for a thermodynamically isolated economy. References to the second law of thermodynamics in economics within the context of scarcity ignore the fact that the earth is not an isolated system. The earth interacts with external sources and sinks of entropy and the resulting total entropy fluctuates around a constant. Even if the mankind finally proves unable to recycle industrial waste and close the technological cycle, the economic disruption caused by the depletion of natural resources may happen while the total thermodynamic entropy of the ecosystem remains essentially at the present level, because the transfer of chemically refined products may not increase significantly the total entropy, but it may decrease their recyclability.

The inutility of industrial waste is not connected with its entropy, which may be exemplified with the case of alumina production. The case also demonstrates that industrially generated entropy is discharged into surroundings without being accumulated in ‘thermodynamically unavailable matter’.

Material entropy, as a measure of complexity and economic dispersal of resources, can be a recyclability metric, but it is not a thermodynamic parameter, and its growth is not equivalent to the growth of thermodynamic entropy.

Added: Feb 19, 2016
Article
Mosleh A., Mikhaylovskaya A., Kotov A. et al. Metals. 2017. Vol. 7. No. 12. P. 1-15.

The paper focuses on developing constitutive models for superplastic deformation behaviour of near-αtitanium alloy (Ti-2.5Al-1.8Mn) at elevated temperatures in a range from 840 to 890 °C and in a strain rate range from 2 × 10−4 to 8 × 10−4 s−1. Stress–strain experimental tensile tests data were used to develop the mathematical models. Both, hyperbolic sine Arrhenius-type constitutive model and artificial neural-network model were constructed. A comparative study on the competence of the developed models to predict the superplastic deformation behaviour of this alloy was made. The fitting results suggest that the artificial neural-network model has higher accuracy and is more efficient in fitting the superplastic deformation flow behaviour of near-α Titanium alloy (Ti-2.5Al-1.8Mn) at superplastic forming than the Arrhenius-type constitutive model. However, the tested results revealed that the error for the artificial neural-network is higher than the case of Arrhenius-type constitutive model for predicting the unmodelled conditions.

Added: Feb 1, 2018
Article
Zharkov M. Y., Lublinsky I., Vertkov A. et al. Fusion Engineering and Design. 2012. Vol. 87. No. 10. P. 1719-1723.

Activity on projects of ITER and DEMO reactors has shown that solution of problems of divertor target plates and other plasma facing elements (PFEs) based on the solid plasma facing materials cause serious difficulties. Problems of PFE degradation, tritium accumulation and plasma pollution can be overcome by the use of liquid lithium–metal with low Z. Application of lithium will allow to create a self-renewal and MHD stable liquid metal surface of the in-vessel devices possessing practically unlimited service life; to reduce power flux due to intensive re-irradiation on lithium atoms in plasma periphery that will essentially facilitate a problem of heat removal from PFE; to reduce Zeff of plasma to minimally possible level close to 1; to exclude tritium accumulation, that is provided with absence of dust products and an opportunity of the active control of the tritium contents in liquid lithium. Realization of these advantages is based on use of so-called lithium capillary-porous system (CPS) – new material in which liquid lithium fill a solid matrix from porous material. The progress in development of lithium technology and also activity in lithium experiments in the tokamaks TFTR, T-11M, T-10, FTU, NSTX, HT-7 and stellarator TJ II permits of solving the problems in development of steady-state operating lithium divertor module project for Kazakhstan tokamak KTM. At present the lithium divertor module for KTM tokamak is under development in the framework of ISTC project # K-1561. Initial heating up to 200 °C and lithium surface temperature stabilization during plasma interaction in the range of 350–550 °C will be provided by external system for thermal stabilization due to circulation of the Na–K heat transfer media. Lithium filled tungsten felt is offered as the base plasma facing material of divertor. Development, creation and experimental research of lithium divertor model for KTM will allow to solve existing problems and to fulfill the basic approaches to designing of lithium divertor and in-vessel elements of new fusion reactor generation, to investigate plasma physics aspects of lithium influence, to develop technology of work with lithium in tokamak conditions. Results of this project addresses to the progress in the field of fusion neutrons source and fusion energy source creation.

Added: Feb 26, 2013
Article
Loganathan N., Yazaydin A. O., Bowers G. M. et al. The Journal of Physical Chemistry C. 2017. Vol. 121. No. 44. P. 24527-24540.

Grand Canonical Molecular Dynamics (GCMD) simulations were performed to investigate the intercalation of CO2 and H2O molecules in the interlayers of the smectite clay, Na-hectorite, at temperatures and pressures relevant to petroleum reservoir and geological carbon sequestration conditions and in equilibrium with H2O-saturated CO2. The computed adsorption isotherms indicate that CO2 molecules enter the interlayer space of Na-hectorite only when it is hydrated with approximately three H2O molecules per unit cell. The computed immersion energies show that the bilayer hydrate structure (2WL) contains less CO2 than the monolayer structure (1WL) but that the 2WL hydrate is the most thermodynamically stable state, consistent with experimental results for a similar Na-montmorillonite smectite. Under all T and P conditions examined (323–368 K and 90–150 bar), the CO2 molecules are adsorbed at the midplane of clay interlayers for the 1WL structure and closer to one of the basal surfaces for the 2WL structure. Interlayer CO2 molecules are dynamically less restricted in the 2WL structures. The CO2 molecules are preferentially located near basal surface oxygen atoms and H2O molecules rather than in coordination with Na+ ions. Accounting for the orientation and flexibility of the structural −OH groups of the clay layer has a significant effect on the details of the computed structure and dynamics of H2O and CO2 molecules but does not affect the overall trends with changing basal spacing or the principal structural and dynamical conclusions. Temperature and pressure in the ranges examined have little effect on the principal structural and energetic conclusions, but the rates of dynamical processes increase with increasing temperature, as expected.

Added: Nov 11, 2017
Article
S.A. Aksenov, E.N. Chumachenko, I.V. Logashina et al. Metalurgija. 2015. Vol. 1. No. 54. P. 75-78.

The application of finite element simulation to the problem of roll pass design for round bar rolling is considered. Two roll pass sequences were developed by analytical methods and then optimized using 2.5D Finite Element Method (FEM). The first one is a classical oval-round roll pass design. The second one is a combination of flat rolls and round roll passes. Relying on the simulation data obtained by FEM, the roll gaps were adjusted to achieve the required bar shape and the uniform distribution of rolling force between the passes. Advantages and disadvantages of each roll pass design were considered.

Added: Oct 14, 2014
Article
Burov A.A., German A., Kosenko I. Cosmic Research. 2014. Vol. 52. No. 4. P. 289-294.

The problem of planar oscillations of a pendulum with variable length suspended on the Moon’s surface is considered. It is assumed that the Earth and Moon (or, in the general case, a planet and its satellite, or an asteroid and a spacecraft) revolve around the common center of mass in unperturbed elliptical Keplerian orbits. We discuss how the change in length of a pendulum can be used to compensate its oscillations. We wrote equations of motion, indicated a rule for the change in length of a pendulum, at which it has equilibrium positions relative to the coordinate system rotating together with the Moon and Earth. We study the necessary conditions for the stability of these motions. Chaotic dynamics of the pendulum is studied numerically and analytically.

Added: Nov 21, 2014
Article
Burov A. A., Shalimova E. Regular and Chaotic Dynamics. 2015. Vol. 20. No. 3. P. 225-233.

The problem of motion of a heavy particle on a sphere uniformly rotating about a fixed axis is considered in the case of dry friction. It is assumed that the angle of inclination of the rotation axis is constant. The existence of equilibria in an absolute coordinate system and their linear stability are discussed. The equilibria in a relative coordinate system rotating with the sphere are also studied. These equilibria are generally nonisolated. The dependence of the equilibrium sets of this kind on the system parameters is also considered. © 2015, Pleiades Publishing, Ltd.

Added: Sep 3, 2015
Article
Chumachenko E. N., Logashina I. V., Zakhariev I. Y. Metallurgist. 2016. Vol. 60. No. 3. P. 460-465.

This article discusses research done on modeling, analyzing, and optimizing the technology used to forge the titanium sections of pressure vessels. The finite-element method was used for computer modeling of the deformation of the material during the forging operation. The study examined the forging force, the uniformity of deformation of the vessel’s walls, the filling of the dies, and the probability of crimping. Consideration was given to the possibility of using the phenomenon of superplasticity to forge the given product. The superplastic flow regime is maintained only during the final stage of the forging operation (the last 20% of the stroke of the die) in order to shorten operation as a whole. This is done by setting the die speed at a value which ensures that the material is deformed within a prescribed rate range and that the limits specified for the maximum forces are observed. Several alternatives were examined for making the vessel, these variants differing in the form of the semifinished product and the configuration of the dies. With constraints on the maximum loads and forging time, the technology that was chosen makes it possible to significantly increase the coefficient that characterizes the utilization of titanium in the production process.

Added: Sep 19, 2016
Article
Burov A. A., Kosenko I. I. Mechanics of Solids. 2014. Vol. 49. No. 5. P. 506-517.

 In the usual everyday life, it is well known that the inverted pendulum is unstable and is ready to fall to “all four sides,” to the left and to the right, forward and backward. The theoretical studies and the lunar experience of moon robots and astronauts also confirms this property. The question arises: Is this property preserved if the pendulum is “very, very long”? It turns out that the answer is negative; namely, if the pendulum length significantly exceeds the Moon radius, then the radial equilibria at which the pendulum is located along the straight line connecting the Earth and Moon centers are Lyapunov stable and the pendulum does not fall in any direction at all. Moreover, if the pendulum goes beyond the collinear libration points, then it can be extended and manufactured from cables. This property was noted by F. A. Tsander and underlies the so-called lunar space elevator (e.g., see [1]). In the plane of the Earth and Moon orbits, there are some other equilibria which turn out to be unstable. The question is, Are there equilibria at which the pendulum is located outside the orbital plane? In this paper, we show that the answer is positive, but such equilibria are unstable in the secular sense. We also study necessary conditions for the stability of lunar pendulum oscillations in the plane of the lunar orbit. It was numerically discovered that stable and unstable equilibria alternate depending on the oscillation amplitude and the angular velocity of rotation.

Added: Nov 27, 2014
Article
Makarov A., Mitrova T. A., Veselov F. et al. Thermal Engineering (English translation of Teploenergetika). 2017. Vol. 64. P. 703-714.

A scenario-based prognosis of the evolution of global power generation markets until 2040, which was developed using the Scaner model-and-information complex, was given. The perspective development of fuel markets, vital for the power generation industry, was considered, and an attempt to predict the demand, production, and prices of oil, gas, coal, and noncarbon resources across various regions of the world was made. The anticipated decline in the growth of the global demand for fossil fuels and their sufficiency with relatively low extraction expenses will maintain the fuel prices (the data hereinafter are given as per 2014 prices) lower than their peak values in 2012. The outrunning growth of demand for electric power is shown in comparison with other power resources by regions and large countries in the world. The conditions of interfuel competition in the electric power industry considering the changes in anticipated fuel prices and cost indicators for various power generation technologies were studied. For this purpose, the ratios of discounted costs of electric power production by new gas and coal TPPs and wind and solar power plants were estimated. It was proven that accounting the system effects (operation modes, necessary duplicating and reserving the power of electric power plants using renewable energy sources) notably reduces the competitiveness of the renewable power industry and is not always compensated by the expected lowering of its capital intensity and growth of fuel for TPPs. However, even with a moderate (in relation to other prognoses) growth of the role of power plants using renewable energy sources, they will triple electric power production. In this context, thermal power plants will preserve their leadership covering up to 60% of the global electric power production, approximately half using gas. Keywords: electric power, gas, coal, renewable power sources, power consumption, fuel extraction, fuel markets, interfuel competition, social efficiency, cost of electric power production

Added: Oct 21, 2017
Article
Zaichenko V., Knyazeva M., Krylova A. et al. Solid Fuel Chemistry. 2019. Vol. 53. No. 3. P. 159-165.

The effect of mild pyrolysis methods (hydrothermal carbonization and torrefaction) on the physi-cochemical properties of biocoal was studied. It was established that biocoal obtained by hydrothermal car-bonization has a large specific surface area and exerts an exothermic effect upon decomposition; as comparedwith the samples obtained by torrefaction, it has a more dispersed structure and lower ash content.

Added: Nov 19, 2019