bluuebunny/crossref_metadata_2025 huggingface dataset:
A new telescope with three fields of view to measure the orientation parameters of the Moon and terrestrial planets
Authors: Sun Li-Zao , Huang Cheng-Li , Yu Yong , Qi Zhao-Xiang , Tang Zheng-Hong , Zhao Ming , Yang De-Hua , Wu Tong
Published: March 2021

For lots of scientific questions about lunar physics deep inside the Moon, in-situ observation on lunar physical libration is one of the most potential ways. In this paper, we propose a brand new optical telescope functioned with simultaneously observing multiple (here there are three) fields of view (FOVs) for in-situ observation of lunar physical libration. The telescope can be placed at any place with any attitude on the Moon and do not require manned install, control or operation. It passively, continuously and simultaneously observe stars in three FOVs along with rotation of the Moon. Libration is to be measured and studied from celestial motion of the directions of three FOVs from image processing. The concept and design of this telescope are firstly introduced in this paper. The principle and feasibility of the method of in-situ observation are also demonstrated. From simulation, precision of the determined lunar physical libration is expected to be several milliarcsecs, about two orders of magnitude better than the current precision of libration by lunar laser ranging observation. Libration data with milliarcsec precision level can play a valuable role in the study of the physics and dynamics of the interior of the Moon. This telescope can also be applied to observe the rotation of other terrestrial planets like Mars.
Spin-down and emission variations for PSR J0742−2822
Authors: Dang Shi-Jun , Wang Na , Wang Hui-Hui , Yuan Jian-Ping , Shang Lun-Hua , Yuen Rai , Ge Ming-Yu , Zhou Xia , Wang Shuang-Qiang , Kou Fei-Fei , Yan Wen-Ming , Wang Jing-Bo , Wen Zhi-Gang , Bai Jun-Tao , Liu Zhi-Yong , Zhou Zu-Rong
Published: March 2021

PSR J0742−2822 is known for its quasi-periodic changes in the observed pulse profile and spindown rate. In this paper, we analyzed 13 years of timing data obtained with the Nanshan 25-m radio telescope and the Parkes 64-m radio telescope. We found that the average values of the spin-down rate (

〈

ν
˙

〉

) of this pulsar changed in four different states. We investigated the correlation between

ν
˙

and W
50, and ascertained that the correlation changed in different

〈

ν
˙

〉

states. Moreover, not all the changes in

〈

ν
˙

〉

states and correlation can be associated with glitch activities. We examined the long term evolution of γ-ray flux (0.1–300 GeV) and the pulse profiles corresponding to the four different states using Fermi-LAT Pass 8 (P8R3) data from 2008 August 5 to 2019 October 1. We did not detect a significant change in γ-ray flux or the pulse profile. Our results suggest that the connection between pulsar rotation and emission is more complex than previously reported for this pulsar.
Anomalies in Young's modulus behavior after annealing in polycrystalline SmS
Authors: Kaminskii V. V. , Sharenkova N. V. , Kamenskaya G. A. , Grevtsev M. A. , Lyubimova Yu. V.
Published: March 2021

In this paper, the dependencies of Young's modulus and attenuation decrement on samarium sulfide polycrystals (SmS) under various annealing temperatures are studied by the piezoelectric ultrasonic composite oscillator technique at a frequency of 100 kHz in the temperature range of 80–300 K. A decrease in Young's modulus with an increase of the annealing temperature due to the texturing of the material was revealed. At the same time, attenuation peaks were observed at temperatures about 90 and 125 K, presumably due to Niblett-Wilks and Bordoni relaxations.
A 1.2 V, 3.1% 3σ-accuracy thermal sensor analog front-end circuit in 12 nm CMOS process
Authors: Yang Liqiong , Wang Linfeng , Xiao Junhua , Zhang Longbing , Wang Jian
Published: March 2021

This paper presents a 1.2 V high accuracy thermal sensor analog front-end circuit with 7 probes placed around the microprocessor chip. This analog front-end consists of a BGR (bandgap reference), a DEM (dynamic element matching) control, and probes. The BGR generates the voltages linear changed with temperature, which are followed by the data read out circuits. The superior accuracy of the BGR’s output voltage is a key factor for sensors fabricated via the FinFET digital process. Here, a 4-stage folded current bias structure is proposed, to increase DC accuracy and confer immunity against FinFET process variation due to limited device length and low current bias. At the same time, DEM is also adopted, so as to filter out current branch mismatches. Having been fabricated via a 12 nm FinFET CMOS process, 200 chips were tested. The measurement results demonstrate that these analog front-end circuits can work steadily below 1.2 V, and a less than 3.1% 3σ-accuracy level is achieved. Temperature stability is 0.088 mV/°C across a range from –40 to 130 °C.
Side-channel attack-resistant AES S-box with hidden subfield inversion and glitch-free masking
Authors: Li Xiangyu , Jiao Pengyuan , Yang Chaoqun
Published: March 2021

A side-channel attack (SCA)-resistant AES S-box implementation is proposed, which is an improvement from the power-aware hiding (PAH) S-box but with higher security and a smaller area. We use the composite field approach and apply the PAH method to the inversion in the nonlinear kernel and a masking method to the other parts. In addition, a delay-matched enable control technique is used to suppress glitches in the masked parts. The evaluation results show that its area is contracted to 63.3% of the full PAH S-box, and its power-delay product is much lower than that of the masking implementation. The leakage assessment using simulation power traces concludes that it has no detectable leakage under t-test and that it at least can thwart the moment-correlation analysis using 665 000 noiseless traces.
Energy band adjustment of 808 nm GaAs laser power converters via gradient doping
Authors: Zhao Yingjie , Li Shan , Ren Huixue , Li Shaojie , Han Peide
Published: March 2021

The gradient doping regions were employed in the emitter layer and the base layer of GaAs based laser power converters (LPCs). Silvaco TCAD was used to numerically simulate the linear gradient doping and exponential gradient doping structure, and analyze the transport process of photogenerated carriers. Energy band adjustment via gradient doping improved the separation and transport efficiency of photogenerated carriers and reduced the total recombination rate of GaAs LPCs. Compared with traditional structure of LPCs, the photoelectric conversion efficiency of LPCs with linear and exponential gradient doping structure were improved from 52.7% to 57.2% and 57.7%, respectively, under 808 nm laser light at the power density of 1 W/cm2.
Film flows with recirculation: hydrodynamics and heat transfer
Authors: Solodov A P
Published: March 2021

Hydrodynamics and heat transfer in film flows along solid surfaces are analyzed by numerical simulation. The current version of the Kolmogorov-Prandtl turbulence model is used to obtain a compact mathematical description focused on engineering applications in power engineering and other heat technologies. Film flows with recirculation are studied as special modes of condensing (or evaporative) devices of power plants. Other possible applications are the problems of evaporative cooling, problems of hydraulic roughness of technical surfaces, technologies of thin-film materials and – in the field of large linear scales - modeling of some natural catastrophic phenomena, such as mudflows. The mathematical description is presented as a system of three ordinary first-order nonlinear differential equations - for distributions of turbulent energy, turbulent energy flux density, flow velocity. The phenomena of laminar – turbulent transition and special modes of “flooding” of the flow are diagnosed. Temperature distributions are calculated and heat fluxes are determined. The Reynolds number of the film and the Stanton number are presented as functions of two dimensionless determining parameters specifying the film thickness and the ratio of the friction stresses at the boundaries.
Hydrodynamics of coolant in VVER reactor core with fuel assemblies of various designs
Authors: Dmitriev S M , Gerasimov A V , Dobrov A A , Doronkov D V , Liskova V E , Rubtsova E V , Ryazanov A V , Khrobostov A E
Published: March 2021

The article presents the results from experimental investigations into local coolant flow fluid dynamics that were carried out on the fragmental model of a VVER-type pressurized water reactor’s mixed core consisting of two types of fuel assemblies (FAs): TVSA-T (one segment) and TVSA-T.mod.2 (two segments). The coolant flow processes in the fuel rod bundle were simulated on an aerodynamic test bench. The pressure field in the flow was measured using a five-channel pneumometric probe. The obtained pressure field in the flow was recalculated for the coolant velocity vector according to the dependences derived during calibration. For drawing up a detailed flow motion pattern, a characteristic model cross section area was separated, which included the space between the assemblies and four fuel rod rows in each TVSA-type fuel assembly. The spatial distribution of coolant flow velocity projections was analyzed, as a result of which it became possible to reveal the regularities associated with the streamlining of spacer, mixing-, and combined-spacer grids in TVSA assemblies by coolant; to determine coolant cross flows resulting from streamlining of hydraulically nonidentical grids and to determine their localization in the experimental model longitudinal and cross sections; and to reveal the effect of accumulating flow hydrodynamic disturbances in the model longitudinal and cross sections resulting from the staggered arrangement of hydraulically nonidentical grids. The results obtained from investigations of interassembly interaction of coolant between the neighboring TVSA-T and TVSA-T.mod.2 assemblies have been adopted for practical use at JSC “Afrikantov OKBM” in estimating the thermal reliability of VVER-type reactor cores and have been included in the database for verification of computation fluid dynamics computer programs (CFD codes) and detailed cell-wise numerical analysis of VVER reactors’ core.
Non-contact heat transfer models identification: Laser hyperthermia of superficial human tissues
Authors: Semenov D S , Nenarokomov A V , Budnik S A
Published: March 2021

Planning and predicting the processes of biological tissues heating associated with therapeutic effects involves high-precision mathematical modelling. However, the thermophysical properties of tissues can vary greatly from patient to patient. The paper presents a computational and experimental method for identifying mathematical models of heat transfer, not involving the placement of temperature sensors inside of the studied object. The experimental setup consists of a flat sample of the material, a laser setup, and a thermal imaging camera. The surface thermal response to the pulsed heat flux of the laser is an array of input data for the developed software package. The heat transfer coefficient and heat flux density are determined iteratively by minimizing the residual functional between the calculated and experimental values. The method was tested when determining the characteristics of a specimen of low-pressure polyethylene. The result was obtained in 5 iterations and under the influence of external natural convection, and without taking into account the translucency of the material, a discrepancy of calculated and experimental values of 3.5% was shown. The method can be used to plan the therapeutic process in order to ensure its maximum effectiveness.
Application of the homogenous nucleation theory to the study of explosive boiling of superheated liquid drops
Authors: Mayorov V O , Yastrebov A K , Levashov V Yu
Published: March 2021

In the work, a model of explosive boiling of a single droplet was proposed, which is based on the classical nucleation theory. A criterion is proposed for estimation the droplet’s lifetime. Calculations were made for droplets of liquid oxygen in saturated vapor. Analysis is made for influence of the initial temperature and droplet size on its lifetime.
Studies of coal and coke ignition intensified by copper salt additives
Authors: Larionov K B , Zenkov A V , Mishakov I V , Kaltaev A Z , Bauman Y I , Gromov A A
Published: March 2021

Process of coal and semi-coke ignition modified with copper salts (Cu(NO3)2, Cu(CH3COO)2 and CuSO4) in amount of 5 wt.% was studied. Application of additives to coal and semi-coke samples was carried out by incipient wetness impregnation method with preliminary dissolution of the additive in an aqueous-alcohol solution with a volume ratio of C2H5OH/H2O = 50/50. Combustion of coal samples has been conducted in combustion chamber at temperatures of the heating medium 500-700 °C. Ignition time was recorded using high-speed video recording. Application of copper-salt additives helped to reduce ignition delay time for samples of BC and SC series by 1.9 and 2.2 times, respectively. The maximum change in the minimum ignition temperature for samples of BC and SC series was 70 °C and 135 °C, respectively.
Swirl Flow Crisis and Its Manifestation in Various Energy Systems
Authors: Mitrofanova O V , Bayramukov A S
Published: March 2021

Conducted analytical studies have shown that in complex geometry channels with three-dimensional curvature, and a variable cross-section area, the conditions leading to large-scale vortex formation and swirl flow. In this case, not only the mode of swirl flow can be implemented, but also the effect of locking the flow due to the crisis of the swirl flow. It is shown that the crisis of swirl flow can take place in various power, motor, chemical-technological devices and other technical devices associated with the use of high-speed swirl flows of liquids or gases. A characteristic feature of such devices is the presence of large pressure losses required for the organization of flow swirling in channels of complex geometry. In the present paper, the manifestation of the swirl flow crisis is considered on the example of modeling the processes of hydrodynamics and heat exchange in the channels of an icebreaker steam generating installation.
CFD-calculation of influence of impurities on the characteristics of a helium turboexpander
Authors: Sidorov A A , Yastrebov A K
Published: March 2021

The process of expanding of two-component gaseous mixture was studied in a stage of a turboexpander unit in three-dimensional unsteady setting with use of methods of computer fluid dynamics. The calculation method used in this work made it possible to study the turboexpander unit in a single calculation model but not in parts due to the use of sliding interfaces. Based on the distribution of the supersaturation ratio, assumption was made about the possible localization of phase transitions in the flow part of the stage of the turboexpander unit, confirmed by the characteristic impeller damage.
Determining the smoke-generating ability of modern cable products needed to model fires in energy facilities
Authors: Puzach S V , Mustafin V M , Akperov R G
Published: March 2021

A comparative analysis of methods of carrying out fire tests was carried out in order to obtain the value of smoke formation coefficient required for simulation of fire dynamics at power engineering facilities. A new method of carrying out fire tests to determine smoke-forming ability of substances and materials is proposed. Results of measurements of radiant heat flux density and gas medium temperature inside combustion chamber at different distances from heating element are presented. The effect of the sample area, the density of the heat flow incident on the sample and the temperature inside the combustion chamber on the value of the smoke formation coefficient is shown. For modern types of cable products used at power engineering facilities, values of smoke formation coefficient under different modes have been determined. Dependence of smoke formation coefficient on sample area and on distance from heating element inside combustion chamber is obtained. A comparative analysis of the results obtained at different facilities with the values given in the database of typical fire load was carried out. It was found that the experimental value of smoke formation coefficient differs significantly from the values obtained in the standard ГOCT12.1.044 facility. The results were analyzed.
Physical simulation of blood flow in a femoropopliteal artery graft
Authors: Mikheev N I , Molochnikov V M , Paereliy A A , Dushina O A
Published: March 2021

The paper describes a new experimental setup intended for simulation of blood flow through stenosis or distal end of anastomosis. The setup is able to reproduce flow rate pulsations with a wave form identical to the one of real blood flow during a cardiac cycle, including the high-amplitude antegrade peak and flow reversal. The design of experimental setup provides stable average flow rate in the test section and repeatability of simulated flow regimes.
Recommendation for prediction of pool boiling heat transfer of various liquids on microstructured surfaces
Authors: Aksianov R A , Kokhanova Y S , Kuimov E S , Ley R A , Popov I A , Skrypnik A N
Published: March 2021

Recommendations for prediction heat transfer coefficients and critical heat flux according to available in the literature experimental data of heat transfer and critical heat flux for boiling different liquids on microstructured surfaces made by deformed cutting method are obtained. In the work, on available in the literature sources of experimental data on heat transfer and critical heat flux at boiling of various liquids on the microstructured surfaces made by the deforming cutting method, recommendations for prediction of heat transfer coefficients and critical heat fluxes are received. Microstructured surfaces allow to intensify the heat transfer is 1.1 to 6 times. Due to the variable wettability of microstructured surfaces elements, critical heat flux increase before 4 times. The proposed criteria equations allow predicting heat transfer coefficients with an error of 30%, and critical heat fluxes with an error of 30-35%. In order to improve the accuracy of forecasting, the possibility of using an artificial neural network model for generalizing heat transfer coefficients is shown. Forecasting using an artificial neural network model allows us to determine the heat transfer coefficients with an error of ±20%.The equations are of interest for designing cooling systems for microelectronic devices, heat and mass transfer devices, boiling zones of heat pipes and thermosyphons, etc.
Air breathable thermal insulation with heat transferintensifiers for high-temperature installation
Authors: Vu S K , Glazov V S , Kobzeva A A
Published: March 2021

To increase the efficiency of the high-temperature installation (HTI), several design options for air-permeable insulation in the outer furnace body are considered, differing in the location of heat-exchange intensifiers(HEI) - dimples in the form of spherical segments. As a result of a computational experiment, an option was established in which the heat losses are minimal, and the temperature of the heated air directed to combustion is maximum.
Calculation of sputtering yields of SiO2 layers from the Si surface by helium ions bombardment
Authors: Manukhin V V , Manukhin M V
Published: March 2021

An analytical model of the sputtering of two-component layered inhomogeneous targets by light ions bombardment has been developed, an analytical formula has been obtained, which makes it possible to calculate the total and partial sputtering coefficients of a binary layer of target heterogeneity by light ions bombardment. The formula obtained is used to calculate the sputtering coefficients of silicon oxide layers from the surface of a uniform silicon substrate. The calculation results are in good agreement with the data of computer simulation.
Thermal Conductivity of Phase Changing Materials Doped with Carbon Nanotubes
Authors: Bocharov G S , Gerasimov D N , Grigoriev I S , Dedov A V , Zverev M A , Eletskii A V
Published: March 2021

Phase changing materials (PCM) can accumulate and release a great quantity of energy at changing the temperature in result of the phase transition. This permits one to use PCMs as a basis of thermal accumulators storing the thermal energy at elevated temperatures and releasing it at lowering the temperature below the phase transition point. Worldwide usage of PCMs in building technology and other fields is hindered by a rather low thermal conductivity coefficient of the most PCMs which makes the response of the relevant thermal accumulators too slow and limits the possibilities of application of such devices. This drawback can be overcame through doping a PCM with particles having high thermal conduction coefficient. The present article contains results of experimental and theoretical investigations of heat propagation in PCM doped with carbon nanotubes the thermal conduction coefficient of which exceeds that of the most PCM by 4 – 5 orders of magnitude. Paraffin П-2 have been used as PCM. The experiments performed demonstrate a 2 – 3 times enhancement of thermal conductivity and 16 orders of magnitude enhancement of the electric conductivity because of doping paraffin with 10% multi-walled nanotubes. The propagation of both heat and electric current has a percolation character, so that nanotubes form conductive paths at exceeding some concentration of the dopant. The heat propagation process was modelled through the solution of the non-stationary heat conduction equation with taking into account the sorption of heat due to the phase transition. The calculations performed for composite materials with the varied thermal characteristics of a material imply that the characteristic heating time is proportional to the value of the melting enthalpy and inversely proportional to the value of the heat conduction coefficient.
ThinFilmsAnalysisMPEI – Software for XPS Analysis of Multilayer Multicomponent Films
Authors: Lubenchenko A V , Lubenchenko O I , Ivanov D A , Ivanova I V
Published: March 2021

The work presents ThinFilmsAnalysisMPEI software implementing the method of chemical and phase depth profiling based on photoelectron spectra interpretation, described in paper [1]. Efficiency and productivity of the software for the problem of chemical and depth profiling is shown on examples of synthetic and experimental spectra.
Structure and thermal conductivity of multi-layer Boron Nitride nano-onions medium size groupe
Authors: Zarichnyak Yu P , Ivanov V A , Marova A A , Khodunkov V P
Published: March 2021

The structure of multilayer concentric nano-particles of boron nitride (borofen), the so-called “nano-onions” promising for creating ultra-hard sintering material, is considered. A model of the structure of hollow multilayer boron nitride nanoparticles of a medium-sized group (30 <D <100 nm, the number N of layers from 2 to 100) and an approximate estimation method for the range of changes in their effective thermal conductivity depending on the size of the nanoparticles and the number of layers are proposed
Phase Transitions of n-Hexane–Water Binary Mixtures (0.5 Mole Fraction)
Authors: Bazaev E A , Bazaev A R , Osmanova B K , Dzhapparov T A G
Published: March 2021

By the method of constant volume piezometer among the isochores new values of p,T andp,ρ,T- relations of n-hexane– water binary mixture (0.5 mole fraction) in three phase (llg) and two phase (ll and lg, l-liquid, g – gas) regions, over the wide temperature range from 373.15 to 673.15 K, pressures between 0.2 and 56 MPa and densities between 55 kg/m3and 554 kg/m3are obtained.

Using isochoric P-T break point technique the values of the phase transition parameters (llg ⇄ll, llg⇄lg and ll⇄lg) on p,T – plane were determined and phase coexistence curves in different thermodynamic sections (p,ρ,T)Xwere built.

The dependence of pressure from temperature, density and composition along the phase coexistence curve is described by three parameter polynomial represented by expansion of the compressibility factorZs=psVms/RTs=ps/RTsρmsinto a power series of density ω=ρs/ρcand temperature τ=Ts/Tc.

Zs=ps/RTsρms=1+∑i=1m∑j=0naijωi/τj,Zs=ps/RTsρms=1+∑i=1m∑j=0naijωi/τj, where ρm-molar density (mol/m3), R=8.314-gas constant (J/mol⋅K). The average relative deviation of calculated values of pressure from experimental ones is not more than 0.1%.
Thermal performance of hybrid thermal interface graphene nanocomposites
Authors: Babenko D D , Dmitriev A A , Dmitriev A S , Mikhailova I A
Published: March 2021

This research examines thermal performance of hybrid thermal interface graphene nanocomposites. Graphene nanoflakes were added in different wt. fractions to thermoplastic polymeric materials (polyacrylate and other polymers) followed by thin film preparation. The prepared thin film samples were characterized using optical and scanning electron microscopy. The fabricated samples of polymer-graphene composites were studied to determine the contact angles at different temperatures and the droplet evaporation rates from the surfaces of such materials.
Protective Coating of Irradiation Device for Fast-Neutron Reactor
Authors: Polunin K K , Mokrushin A A , Bragin S Yu , Kiselev D S , Kuzma-Kichta Yu A
Published: March 2021

The objective of this paper is to select a coating on the surface of zirconium hydride (ZH) in order to reduce hydrogen losses under the operating conditions of an irradiation device of FN-reactors. Tests were carried out on the samples of the moderator units made of zirconium hydride. Oxide, phosphide-oxide and oxide-enamel coatings were considered as a protective layer. Hydrogen yield out of the ZH was studied using a calorimeter and a mass spectrometer by thermal heating of the samples according to the test program (heating rate of 10 °C/min, maximum temperature of 1000 °C, isothermal exposure of 40 min, cooling with a furnace). The hydrogen content in the samples was determined by high temperature vacuum extraction. It is shown the oxide coating is the most technologically advanced and effective. A thermogravimetric analysis of the ZH sample with the protective oxide coating was carried out, and the temperature-time dependence of a stoichiometric coefficient (H / Zr) was determined. The amount of the hydrogen released was determined in a temperature range of 20–1100 °C. The temperature increase in up to 1100 °C leads to almost total loss of hydrogen (98–99 %). In this case, the sample retained its integrity, and the coating exfoliated and fragmented.
Effect of material properties on heat transfer during cooling of high-temperature cylindrical bodies in liquids
Authors: Molotova I A , Zabirov A R , Yagov V V , Vinogradov M M , Belyaev I A
Published: March 2021

The aim of the present paper is an experimental study of the cooling processes of high-temperature cylindrical samples with different thermal conductivity of the metal in liquids. Studying the influence of material properties on heat transfer during cooling and the possibility of accurately prediction of the transition surface temperature to the intensive cooling regime will allow substantiating the choice of a new type of tolerant fuel from the standpoint of thermophysics. The experiments were conducted for cooling in water and ethanol with different subcoolings under atmospheric pressure. For metals with low thermal effusivity, an increase in the transition temperature with a significant increase of the removed heat fluxes from the surface was experimentally discovered.
Thermodynamic analysis and optimization of low-boiling fluid parameters in a turboexpander
Authors: Ovsyannik A V , Kliuchinski V P
Published: March 2021

The influence of the initial parameters of a low-boiling working fluid on the thermodynamic efficiency for two turbo-expander cycles (with a heat exchanger at the outlet of the turbo-expander and without a heat exchanger) is considered. For each of the studied cycles, the dependences of the exergy efficiency on the temperature of the low-boiling working fluid before the turboexpander at a constant pressure and the dependence of the exergetic efficiency on the pressure of the low-boiling working fluid before the turbo-expander at a constant temperature were obtained. The dependences of exergy losses on the elements of the studied cycles on the parameters of a low-boiling working fluid are constructed and their analysis is carried out. For the considered schemes, the dependences of the exergy efficiency on pressure are constructed at various temperatures of the low-boiling working fluid in front of the turboexpander. An analysis of the results showed that at any temperature of a low-boiling working fluid, it is possible to determine the pressure at which the exergy efficiency of the investigated circuit will be maximum. Graphic dependencies are obtained that are characterized, from a thermodynamic point of view, by the optimal parameters of a low-boiling working fluid. Comparison of these dependences revealed that, over the entire range of studied temperatures (from 100 °C to 300 °C), a cycle with a heat exchanger at the outlet of the turboexpander has a large exergy efficiency. These graphical dependencies make it possible to determine the optimal parameters of the working fluid in the turboexpander cycle, as well as to predict the change in the exergy efficiency of the installation with changing parameters of the working fluid.
Experimental studies of sediment formation in channels with annular diaphragms of power plants
Authors: Myraviev A V , Nadeev A A , Dakhin S V , Dubanin V Yu , Naumov A M , Vorob’eva Y A
Published: March 2021

In this paper, we consider measures to reduce the amount of deposits in heat exchange tubes and increase the intensity of heat exchange through the use of annular notches-turbulators in tubes of shell-and-tube heat exchangers.
Optimization of CCGT operating modes at variable loads taking into account equivalent operating hours
Authors: Garievskii M V
Published: March 2021

The optimal control of the operating modes of combined cycle power plants is a difficult scientific and practical task, due to the difficulty of taking into account the real technical condition of the equipment, the particularities of the operating modes of a combined cycle gas turbine (with one or two operating gas turbines) and other factors. To determine the optimal regime of combined cycle unit with heat recovery steam generator at variable loads, the method of calculating equivalent operating hours (equivalent operating time) was used, based on the accumulation of damageability from creep and low-cycle fatigue of the main equipment of the combined cycle unit (gas, steam turbines and heat recovery steam generators). The equivalent operating hours and economic parameters of the 450 MW combined cycle power plant were calculated and the optimal operating mode of the main equipment was determined while reducing the load during night off-peak hours.
Prediction of Valves Technical Condition Using Neural Network Models
Authors: Steklov A S
Published: March 2021

An approach to predicting the technical state of reinforcement based on the use of artificial neuro-fuzzy networks, which allow predictingthe value of the predicted value, taking into account external factors, such as operating conditions and wear and tearIntroduction
Mathematical model of estimation of technical condition and prediction of emergency modes of power equipment of power plants using example of power transformer
Authors: Zenina E G , Strizhichenko A V , Efimov V V
Published: March 2021

This paper analyzes the existing regulatory indicators of the technical condition of power transformers. Causal relationships between measurable parameters and defects in the transformer have been studied to identify vulnerabilities and likely scenarios for an emergency. The technical condition of the transformer was assessed using the method of pairing comparisons. The probability of trouble-free operation of functional nodes and transformer in general has been determined. The impact on all transformer systems in determining its lifespan of congestion and short-circuit currents by introducing congestion ratios has been taken into account.
The technique for increase of generating system technical and economic indexes evaluation accuracy using machine learning
Authors: Arakelyan E K , Boldyrev I A , Evseev K V , Sultanov M M , Yurov V A
Published: March 2021

This paper addresses the problem of thermal power plant generating unit efficiency evaluation accuracy increase. The comparison of classic regression analysis and artificial neural network regression approaches is described. The feasibility and reasonability of application of the machine learning techniques for generating unit performance prediction and selecting most influential parameters on its efficiency evaluation accuracy are considered.
Evaluation of the Technical Condition of the Turbine Unit During Diagnostics Using Fuzzy Information
Authors: Krokhin G D , Arakelyan E K , Pestunov A I , Mezin S V , Kibireva A E
Published: March 2021

The report is devoted to the problem of applying fuzzy set theory and fuzzy logic methods in models of diagnostics and assessment of the technical condition of TPP equipment using artificial intelligence methods. Are given here: description of fuzzy images; formation of features of fuzzy images; development of criteria for evaluating features; definition of dividing rules for fuzzy images; classification of fuzzy states of the power plant. The simulation algorithm is considered in relation to a heat and power unit with fuzzy input information and a statistical assessment of the adequacy of fuzzy models. The accuracy of the obtained mathematical model is estimated based on the estimation of the degree of dispersion of the obtained regression line relative to its mathematical model, while the adequacy criteria of 2 types (“R” and “D”) are introduced, which help to integrally assess the proximity of mathematical models to the object under study using the selected measure.
Accounting for the heating cycle in the construction of the optimization model of the thermal power station
Authors: Andryushin A V , Arakelyan E K , Neklyudov A V , Yagupova Y Y , Kuznetsova A V
Published: March 2021

Determining the optimal operating mode of equipment is an important task of modern energy. When planning the operating modes of thermal power plants (TPPs) in the short term (from several hours to several weeks), the following requirements are usually taken into account: production and distribution between the generating units of a given amount of electricity, supply of a given capacity in accordance with the schedule for each group of generation supply points, heat supply to external consumers in accordance with the planned schedule of heat supply. Accounting for heat supply to external consumers allows us to consider in more detail the influence of the volume of heat withdrawals on the area of permissible loads of generating units. This article pays special attention to the optimization of equipment operating modes taking into account the volumes of heat withdrawals from generating units.
Determination of power engineering equipment’s defects in predictive analytic system using machine learning algorithms
Authors: Shcherbatov I A , Turikov G N
Published: March 2021

An approach to forecasting of power equipment’s defects and failures is considered in this paper. The main operations of predictive analytic system for forecasting turbine’s regulation system’s defects is represented. Special attention on machine learning models tuning for explored forecast problem is paid. The following machine learning algorithms: Logistic Regression, Random Forest, Extreme Gradient Boosting, ensembles of these algorithms are explored. According to the results of optimal machine learning models determined, their comparison is done and the conclusion on the appropriateness of the use in predictive analytic system is made.
Technology of desorption of dissolved oxygen from water by boiler exhaust gases
Authors: Zamaleev M M , Kamalova R I , Pazushkina O V
Published: March 2021

A new technology of water degassing based on the use of boiler flue gases as a desorbing agent is described. In the process of burning gaseous fuel, almost all oxygen is consumed, which ensures its absence in the composition of exhaust gases. This makes it possible to use the flue gases of a gas-tight boiler as a desorbent in the process of water deaeration and to avoid using steam. The increasing concentration of carbon dioxide in deaerated water is proposed to be reduced by metering an alkaline agent. The article presents the results of evaluating the mass transfer efficiency of water degassing by the proposed method, as well as the results of calculating the theoretically required specific flow rate of exhaust gases for deaeration.
Construction and Analysis of Adaptive Fuzzy Linear Quadratic Regulator
Authors: Kudinov Y I , Duvanov E S , Kudinov I Y , Pashchenko A F , Pashchenko F F , Pikina G A , Andryushin A V , Arakelyan E K , Mezin S V
Published: March 2021

The paper proposes a formulation and solution of the LQR control problem based on adaptive fuzzy logic. The designs of regulators are considered. The results of analysis of the quality of transients in control systems with adaptive fuzzy LQR controllers are presented. It is shown that the proposed adaptive fuzzy LQR controller provides a shorter transition time and rise time compared to traditional LQR controllers.
Competitiveness of the combined production of chpp with the best available technologies for the separate production of electric energy and heat
Authors: Beloborodov S S , Dudolin AA
Published: March 2021

Further development of the Russian energy sector involves the use of the best available technologies. An important issue is the identification of bats. Increasing the fuel efficiency of power plants is carried out by increasing the unit capacity of generating equipment, increasing the parameters of the working medium to supercritical and super-supercritical. Unfortunately, when forming the list of bats, performance indicators are not always taken into account in real operating modes of the equipment. The calculations have shown that combined production of PTU-CHP plant with subcritical parameters of the working body on the basis of steam turbines of the type P, T and PT given the mandatory process releases steam into the condenser and the gas turbine CHP based on gas turbines of a small capacity has the best specific fuel consumption for generation of electric energy and heat compared to the separate generation of the best available technologies (BAT).
Both numerical and experimental separation of heat transfer mechanisms in porous refractory thermal insulation materials
Authors: Skurikhin A V , Kostanovsky A V
Published: March 2021

The results of estimation of three heat transfer mechanisms in porous refractory thermal insulating materials on example of exfoliated vermiculite at temperatures near 626, 773 and 910 K using experimental data by additive approach are presented.
Features of noise radiation from gas turbines
Authors: Tupov V B , Taratorin A A
Published: March 2021

Gas turbine unit (GTU) is the most intensive source of constant noise during normal operation. The noise of the gas turbine unit is emitted from the compressor intake, from the installation shell and from the chimney mouth of the gas turbine unit. Mathematical models for GTU of various capacities are compiled. It is shown that the determining role plays the noise from combustion. That noise is radiated from the chimney outside. Considered various factors affecting noise emission. Obtained empirical formulas for calculating the noise level at various distances depending on the power of the gas turbine. For the first time indicated the importance of taking into account regional climate factors to determine the required noise reduction from GTU. This is especially important to consider when determining the required reduction at high frequencies. The set of factors considered in this paper allows us to determine the required reduction from the gas turbine. Indicated possible measures to reduce noise from gas turbine unit and bring it to sanitary standards.
Fundamentals of the procedure of a comparative analysis of the thermodynamic effectiveness for power generation facilities in a multigeneration complex with various combinations of their main equipment items
Authors: Petin S N , Korshikova A A
Published: March 2021

A problem is examined of improving the efficiency of power generation facilities during their operation in a multi-generation complex. The efficiency of operation is raised by proper distribution of additional power and heat generating capacities used to cover the consumers’ demand for additional (except for electricity and heat) utilities, among various main equipment items of generation facilities. In this case, electricity and heat generated with a higher efficiency is delivered to the consumers, and electricity and heat with no demand, which have also been generated with a higher efficiency, are utilized at the generation facility to produce other utilities (for example, hydrogen, compressed air, cold, etc.) that are centrally delivered to industrial and social facilities.
Metal-hydride reactor for low rate fuel supply with pressure driven adsorption and cooled by natural convection
Authors: Blinov D V , Borzenko V I , Bezdudny A V , Dunikov D O , Kazakov A N , Romanov I A , Kuleshov V N , Porembsky V I
Published: March 2021

A metal hydride reactor for hydrogen accumulation RHA-1 containing 18 kg of La0.85Ce0.15Ni5 alloy is created. RHA-1 and has maximum hydrogen capacity of 2.7 st.m3 and nominal capacity of 2 st.m3. Experiments have shown that the reactor could be operated using the pressure difference between an electrolyzer (1 MPa) and a fuel cell (>0.2 MPa) with passive cooling/heating of air in indoor conditions. The equilibrium charge rate is 1 st.L/min, the equilibrium discharge rate is 1.3 st.L. The RHA-1 could be used for long term energy storage and in combination with the 100 W PEM fuel cell is comparable with 12V 210Ah electrochemical batteries. The metal hydride/fuel cell system is lighter and more durable than lead acid batteries and cheaper that Li-ion batteries.
Electrode-diaphragm assembly for alkaline water electrolysis
Authors: Kuleshov V N , Kurochkin S V , Kuleshov N V , Blinov D V , Grigorieva O Y
Published: March 2021

In connection with the development of hydrogen energy, special attention is currently being paid to the creation of highly efficient water electrolyzers, including electrolyzers with alkaline electrolyte. The main disadvantage of hydrogen production by water electrolysis is its high energy consumption. The present article shows that energy consumption can be reduced by changing of the electrodes and diaphragm layout. The phase inversion method used for the manufacture of polymer-based porous diaphragms for alkaline water electrolysers made it possible to create an electrode-diaphragm assembly, where elements of electrode-diaphragm assembly represent a single element. The comparative research of electrolysis cells with different electrode-diaphragm assemblies and cells of the traditional “zero gap” was carried out.
Two-stage pyrolytic conversion of coffee husk and parchment into synthesis gas
Authors: Faleeva Yu M , Zaichenko V M
Published: March 2021

The paper considers the technology of two-stage pyrolytic conversion of biomass into gaseous fuel. Coffee husk and parchment were used in this study. The experimental data on composition and quantity of the gaseous products formed in the process of thermal treatment of husk and parchment are presented. The results indicated that the method allows obtaining more than 1.34 m3 of synthesis gas, which consists 96-97% of hydrogen and carbon monoxide, with a heating value of about 11.7 MJ/m3. At the same time, 26-29% of the solid residue (biochar) remains with a heating value of 27-31 MJ/kg. The resulting synthesis gas can be used for generating electricity and for producing liquid chemicals.
Recommendations for improving the accuracy of calculations of load losses of electricity in the wires of overhead power transmission lines
Authors: Shchepotin A S , Shvedov G V , Musorina O S
Published: March 2021

The calculations of load losses of electricity in the wires of overhead power transmission lines in the vast majority of cases are carried out by «traditional» methods, in other words without taking into account the change in the resistance of the wires. Such calculations have significant infelicities, and the existing methods of accounting for factors affecting the temperature of the wire are complex, volumetric in calculations, and require comprehensive information about the weather, and therefore are not used in practice. Recommendations for improving the accuracy of afore-referenced calculations through the application of the method of corrective coefficients were developed in this article. The focus is on the practical application of the recommendations.
Elements of energy infrastructure modernization of buildings and cities
Authors: Perepelitsa R R , Sergeeva K D
Published: March 2021

The formation of effective energy technological systems of buildings and cities in new economic conditions requires comprehensive analysis of dynamic of their developing, complex of diverse conditions of their function, diverse factors of their changes. The need for a systematic approach to the analysis of the functioning of complex technical systems is difficult to dispute. Methodologically, the task is to select from the many approaches the most appropriate for achieving the assigned engineering tasks. This implies the need for a comprehensive analysis of the subject area of the studied systems and the choice of the necessary system equipment, commensurate with the complexity of the selected objects. This article presents a number of elements and technologies for the modernization of the infrastructure of buildings and cities, which in practice shows their energy efficiency: fuel cells, recuperators, heat pumps, thermoactive building systems, and a predictive management with using of weather data - an intelligent tool for controlling the building’s air conditioning.
The method for approximate determination of the heat pipes finned radiators optimal geometric characteristics
Authors: Rekunenko E S , Garyaev A B
Published: March 2021

The method is proposed for approximate optimization of the geometric characteristics of heat pipes finned radiators, the heat from which is removed by natural convection. The mass of the radiator is used as the objective function for a given transmitted heat flux from its surface. The mathematical model developed to calculate the optimal geometric characteristics of radiators made of flat round fins, as well as fins made of square plates.
The influence of the geometric parameters of the evaporator on the process of ice formation in the SAR
Authors: Dyadichenko I A , Samson I F
Published: March 2021

Fossil resources are the foundation of the global economy. However, the extraction, transportation and consumption of this energy source are harmful to the environment. Economic reasons and the search for new solutions based on energy recovery have generated a growing interest in adsorption technology.

In recent decades, the number of studies on adsorption refrigeration systems has increased significantly, because, unlike vapor compression refrigeration units, they cause less harm to the environment. [1]