bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of pressure on the wake of a hydrophobic circular cylinder for a flow regime with Reynolds number of 2.2×105
Authors: Dobroselsky K G
Published: December 2021

Vortex flow structures in a turbulent wake behind a circular Teflon cylinder immersed in an incoming flow with a change in pressure for the Reynolds number Re = 2.2×105 have been experimentally studied using a two-dimensional image (2D-PIV) of particles in a closed-circuit water tunnel. The obtained results are presented in the form of time-averaged velocity fields, Reynolds stresses, and distributions of turbulent kinetic energy. The flow data showed that the size of the wake flow region, Reynolds stresses and turbulent kinetic energy change depending on the pressure in the flow. As a result of a 20% reduction in pressure, the size of the vortex zone in the wake increases by about 20%.
Vortex heat transfer enhancement on energy-efficient surfaces structured by inclined trench dimples
Authors: Isaev S A , Mikheev N I , Dushin N S , Goltsman A E , Nikushchenko D V , Sudakov A G
Published: December 2021

Experimental measurements and numerical predictions of the longitudinal component of the air velocity in a narrow channel with two rows of 26 densely packed oval trenches at angles of ±45° and ±135° in laminar (Re=103) and turbulent (Re=4×103) regimes have been compared. The acceptability of the RANS approach using the modified SST turbulence model within the Rodi–Leschziner–Isaev approach has been substantiated. The flow acceleration in the dimpled channel up to the longitudinal velocity maxima of 1.85 and 1.55 of the average bulk velocity for laminar and turbulent air flows has been experimentally confirmed.
Experimental study of the flow structure in cross flows
Authors: Nebuchinov A S
Published: December 2021

This study investigates the development of flow and mixing processes in the stationary and impulsive transverse jets with a small degree and frequency of blowing pulsation. Velocity field measurements were carried out using the TR PIV technique. The fields of statistical moments are obtained. It is shown that when a cross flow is injected, the main flow is turbulized, while the rise of the pulsating jet depends on the outflow mode. It is shown that with an increase in the frequency of pulsations of the transverse jet, it is more strongly “pressed” against the lower wall, maximum values of the intensity of pulsations of the transverse velocity component exceed by more than 1.5 times the values of pulsations of the transverse component.
Large-eddy simulations of a swirling flow in a model Francis turbine
Authors: Palkin E V , Hrebtov M Yu , Mullyadzhanov R I
Published: December 2021

We performed Large-eddy simulations of the flow in a model air Francis turbine in a range of low-load regimes with a swirler rotating at fixed frequency. All investigated regimes revealed the presence of coherent helical vortex structure in the draft tube: the precessing vortex core. We identified the frequency of this instability and obtained mean flow velocity fields to be utilized in further works.
Effect of the attack angle of the ribs on the flow and heat transfer in a flat channel
Authors: Barsukov A V , Terekhov V V , Terekhov V I
Published: December 2021

The results of numerical simulation of a turbulent flow in a flat channel with periodic inclined ribs by the RANS method are presented. The Reynolds number, calculated from the rib height and the superficial velocity, is Re = 12600. The obtained data are analyzed in order to determine the influence of the inclination angle on heat transfer. It is shown that the optimal angle of inclination, at which the average heat transfer in the channel is maximum, is 60°.
Peculiarities of hydrogen production using methane steam reforming in a microstructured reactor-heat exchanger
Authors: Kuznetsov V V , Gasenko O A
Published: December 2021

This paper presents the description of the rhodium catalyst synthesis and the results of numerical study of the methane-steam reforming in a microstructured reactor-heat exchanger. The kinetics of the reforming reactions on a synthesized catalyst was determined using the numerical simulations and experimental data on activation energy of the methane reactions. It allows finding the characteristics of methane steam reforming that can be used for optimization of the microstructured reactor implementing the microchannel technology.
The investigation of the efficiency of oil displacing from the pore in the rock formation depending on the width and height of the pore using nanosuspension as a displacing agent
Authors: Lobasov A S , Minakov A V
Published: December 2021

The numerical investigation of the two-phase fluid flow in a microchannel was carried out. The effect of the pore width and height on the oil displacing efficiency by nanofluids for various Reynolds numbers was studied. The computational domain was a T-shaped microchannel with a horizontal main flow channel and a vertical channel that imitated the pore in the rock formation, called a pore channel. The main channel width and height were 200 µm, and the pore channel width and height were varied in the range from 100 µm to 800 µm. The Reynolds number was varied from 0.1 to 100. The main studied characteristic was the oil recovery coefficient, defined as the ratio of the volume of oil remaining in the pore to the volume of the pore. That characteristic, obtained for a case, when the nanofluid was used as a displacing agent, was compared to the similar one obtained for a case, when pure water was used as a displacing agent. A single-phase fluid with properties, determined experimentally, was considered the nanofluid. The mass concentrations of SiO2 nanoparticles were 0.25% and 0.5%. The average diameter of nanoparticles was equal to 5 nm. It was found, that the oil recovery coefficient increased with an increase in width of the pore channel and a decrease in its height. It was obtained that the nanofluid can enhance the oil recovery in several times as compared to pure water. It was also found that the main factor affecting the efficiency of oil recovery is the contact angle of wetting.
Study of interface gas-liquid flow characteristics in a rectangular microchannel for wavy-annular flow
Authors: Bartkus G V , Kuznetsov V V
Published: December 2021

The aim of this work is an experimental study of a gas-liquid flow in a rectangular slit microchannel with a cross-section of 200 × 2045 μm. Ethanol/water (95/5) mixture and nitrogen are used as working liquid and gas, accordingly. The external T-mixer is used for obtaining of wavy-annular flow pattern. The experimental data on interfacial waves and their characteristics in the meniscus area on the short side of the microchannel are obtained using high-speed visualization for a wide range of gas and liquid superficial velocities. Images are processed using the Python libraries to define the average liquid layer thickness and maximum amplitude of waves. An increase of gas superficial velocity causes decreasing in the average liquid layer thickness and maximal amplitude of the liquid layer thickness. The waves on the liquid layer surface (maximal amplitude) can be three times larger than the average liquid layer thickness for presented liquid and gas velocities. With increasing gas superficial velocities more liquid displace from the meniscus area to the liquid film on the wide side of the microchannel.
Sound emission of solid surfaces through bubble layer
Authors: Ogorodnikov I A
Published: December 2021

The analysis of the influence of a thin homogeneous bubble layer on sound emission from a solid surface is carried out. Sound pulses and monochromatic wave packets with a carrier frequency equal to the resonant frequency of the bubbles forming the bubble layer are considered. It is shown that the bubble layer transforms short sound pulses into wave sound packets and significantly reduces the amplitude of the emitted sound. The structure of a sinusoidal wave packet is transformed similarly. A long sound pulse is stored in the form of a pulse, its shape changes significantly. A homogeneous bubble layer near a solid radiating surface is an open resonator. The layer generates far-field radiation with spectral lines depending on the method of layer excitation and the internal properties of the bubble layer. The resonant frequency of the bubble is the limiting frequency in the spectrum, but it is not distinguished by a separate line.
Rivulet deflection in the heated liquid film with different initial characteristics
Authors: Semionov V V
Published: December 2021

Analysis of rivulet movement across flow direction in vertical flowing heated liquid film at different Reynolds numbers and initial temperatures was carried out. It is shown, that amplitude of deflection increases substantially at heat fluxes corresponding to the appearance of thermocapillary structures of type A.
Modelling of water jet impact on molten metal
Authors: Yakush S E , Sivakov N S , Melikhov V I , Melikhov O I
Published: December 2021

Splashes of high-temperature melt spreading over a water pool bottom can be a reason for the formation of a zone where melt, water and steam are mixed, providing conditions for powerful steam explosions. The paper considers the formation of melt splashes arising from the impact of a water jet on the surface of the melt. Numerical simulations are performed in 3D formulation, using the VOF method and an improved phase change model. The evolution of melt surface following the water jet impact is demonstrated, including the formation of a cavern, a primary melt splash known as the crown, as well as a secondary splash following the collapse of the cavern, known as the cumulative jet. Parametric study for the melt splash height dependence on the water jet geometry and velocity is carried out. The results of numerical analysis are discussed from the point of view of the similarity with respect to the momentum and kinetic energy of water jet. The significance of the results for the steam explosion problem is discussed.
Effect of phase transitions on operation of air-to-air heat exchangers with drop irrigation
Authors: Nizovtsev M I , Letushko V N
Published: December 2021

The article presents the results of experimental studies of the thermal and humidity parameters of air flows of a regenerative air-to-air heat exchanger with drop irrigation and an intermediate heat carrier when operating in winter conditions with negative outside temperatures. The dependences of temperature and humidity efficiency of the heat exchanger on saline solution flow rate were determined, while the maximum temperature efficiency in the heating column was more than 70%. It is shown that under all investigated regimes in the heating column, moisture evaporated from the saline solution, and the air entering the room became more humid, which is a positive factor that increases the comfort of premises at negative outside temperatures.
Numerical studies of the advective flow of heptadecane in a horizontal layer with a longitudinal temperature gradient at the lower boundary
Authors: Kislitsyn S A , Berdnikov V S
Published: December 2021

Numerical studies of the convective flow of heptadecane in a horizontal layer with a suddenly applied longitudinal temperature gradient at the lower high-thermal conductivity boundary have been carried out by the finite element method. A system of nonstationary dimensionless equations of free convection containing stream function, velocity vortex, and temperature as variables was solved. The calculations were carried out with a free upper boundary with and without taking into account the influence of the thermocapillary effect.
The effect of operating parameters on the heat transfer in the heat pipe
Authors: Litvintceva A. A. , Volkov N. I. , Vorogushina N. I. , Moskovskikh V. A. , Cheverda V. V.
Published: December 2021

Heat pipes are a good solution for temperature stabilization, for example, of microelectronics, because these kinds of systems are without any moving parts. Experimental research of the effect of operating parameters on the heat transfer in a cylindrical heat pipe has been conducted. The effect of the working fluid properties and the porous layer thickness on the heat flux and temperature difference in the heat pipe has been investigated. The temperature field of the heat pipe has been investigated using the IR-camera and K-type thermocouples. The data obtained by IR-camera and K-type thermocouples have been compared. It is demonstrated the power transferred from the evaporator to the condenser is a linear function of the temperature difference between them.
Numerical simulation of the processes of atomization and combustion of a coal-water slurry in different-scale installations
Authors: Kuznetsov V A , Dekterev A A
Published: December 2021

Numerical simulation of atomization of a coal-water suspension (CWS) by a pneumatic nozzle is carried out, taking into account the processes of secondary breakup of droplets. The characteristic parameters of atomization were obtained (the dispersed jet opening angle, the size and velocity of the droplets). The data obtained were used to simulate atomization and combustion of the CWS on the firing stand. The results obtained are in good agreement with experimental data. The proposed numerical technique allows research on the introduction of advanced technologies and the improvement of existing different-scale installations (from stands to pilot industrial boilers).
Metallurgical silicon refining using electron-beam plasma
Authors: Shchukin V G , Konstantinov V O , Sharafutdinov R G
Published: December 2021

The possibilities of plasma-chemical refining of metallurgical silicon have been demonstrated. It is shown that by electron-beam refining it is possible to reduce the concentration of phosphorus and boron, as well as the main metallic impurities by evaporation of both these impurities and their volatile compounds.
Thermodynamic modeling of solid fuel gasification in mixtures of oxygen and carbon dioxide
Authors: Donskoy I G
Published: December 2021

One of the main problems in the use of solid fuels is inevitable formation of significant amounts of carbon dioxide. The prospects for reducing CO2 emissions (carbon capture and storage, CCS) are opening up with the use of new coal technologies, such as thermal power plants with integrated gasification (IGCC) and transition to oxygen-enriched combustion (oxyfuel). In order to study the efficiency of solid fuel conversion processes using carbon dioxide, thermodynamic modeling was carried out. Results show that difference between efficiency of fuel conversion in O2/N2 and O2/CO2 mixtures increases with an increase in the volatile content and a decrease in the carbon content. The effect of using CO2 as a gasification agent depends on the oxygen concentration: at low oxygen concentrations, the process temperature turns out to be low due to dilution; at high oxygen concentrations, the CO2 concentration is not high enough for efficient carbon conversion.
Flow regimes in a multi-gap circular Couette-Taylor system with opposite rotating cylinders
Authors: Serov A F , Mamonov V N , Nazarov A D , Miskiv N B
Published: December 2021

This work investigates the flow structure in the gaps of a multi-cylinder circular Couette-Taylor system, which is a model of a two-rotor heat generator. The initial information for studying the flow structure was data on the magnitude of the resistance torque to rotors opposed rotation, as well as on the nature of the amplitude-frequency spectrum of pulsations of this torque, depending on the viscosity of the working fluid and the rotational speed of the heat generator rotors. The obtained data allow comparing the nature of hydrodynamic processes in the single and obtained multi-gap circular space of Couette-Taylor and calculating the parameters of structural formations in the multi-gap working space of the heat generator. At relative rotational speeds of rotors (3-50) rad/s, the main energy of flow pulsations (up to 90%) is found in the amplitude-frequency spectra in the frequency range (12-70) Hz. It is associated with vortices first described by Taylor, which are extended low-frequency regularly alternating spirals and vortex structures with right and left rotation in the region of higher frequencies (200– 500) Hz; their frequency is determined by the width of the annular gaps of the multi-cylinder system.
Energy efficiency of an absorption thermotransformer with two-stage absorption as part of a heat and cold supply complex based on a gas boiler house
Authors: Stepanov K I , Mukhin D G
Published: December 2021

The article proposes a scheme for using a lithium bromide absorption thermotransformer (LBATT) with two-stage absorption for deep utilization of the heat of combustion products (CPs) of gas boilers. At the same time, this solution allows heating the dictrict heating systems return water in the cold season. In the warm season, LBATT is used to cool the water of the air conditioning system or process equipment cooling. In this case, heat removal from LBAHT with two-stage absorption in the warm season is carried out using an drycooler. The analysis of the effectiveness of the use of LBATT in the cold and warm seasons is carried out. The theoretical transformation coefficient of LBATT with deep utilization of flue gases reaches 1.72. The theoretical thermal coefficient of LBATT when cooling water in the warm season reaches a value of 0.7.
Increasing the efficiency of electric submersible pumps by using big data processing and machine learning technologies
Authors: Abdurakipov S
Published: December 2021

The current coverage of oil wells with telemetry does not allow timely determination of deviations in the operation of about 40% of electric submersible pumps. To solve this problem, a model of virtual sensors has been developed that allows the prediction of temperature and pressure growth at the pump intake in the absence of submersible sensors based on modern big data processing and machine learning technologies. The developed models of virtual sensors are embedded directly into the process control system, which allows notifying the technologists and operators about a possible reduction in the planned average pump operating time and their possible failures for various reasons.
Radiation of argon clustered flow particles outside the exciting electron beam
Authors: Dubrovin K A , Zarvin A E , Rebrov A K , Konstantinov S E , Borynyak K I , Yaskin A S , Kalyada V V
Published: December 2021

The spectral study results of a supersonic clustered argon flow stimulated emission in the region of particle excitation (on an electron beam) and downstream are presented. Anomalies in the luminescence of the traditional spindle-shaped jet and the flow of heavy clusters (“wake”) are discussed. Possible causes of the observed anomalous phenomena are presented on the basis of the given comparisons of the results obtained.
Dynamics of bubble growth under a heated substrate
Authors: Kochkin D Y , Mungalov A S , Derevyannikov I A
Published: December 2021

This paper investigates the growth dynamics of a vapor-gas bubble pressed against a heating plate by the buoyancy force. The shadow method was used to capture images, which were then automatically processed to calculate the size of the bubble. As expected, the bubble dynamics significantly depends on the heating power. It was found that the ratio of bubble diameter to bubble height increases as it grows.
Thermophysical properties of NP2 brand nickel
Authors: Samoshkin D A , Agazhanov A Sh , Stankus S V
Published: December 2021

The heat capacity and the thermal diffusivity of NP2 brand nickel were investigated in the temperature interval 296–1000…1375 K of the solid-state, including the region of the magnetic phase transformation. Measurements were carried out on samples from one initial ingot by laser flash technique and method of differential scanning calorimetry using LFA-427 and DSC 404 F1 setups, respectively. The thermal conductivity was calculated based on the measured thermophysical properties. The estimated errors of the obtained results were 2–4%, 3–5%, and 2–3% for thermal diffusivity, thermal conductivity, and heat capacity, respectively. For investigated thermophysical properties the fitting equations and the reference table have been received.
The linear thermal expansion coefficient of Inconel 617 alloy
Authors: Kozlovskii Yu M , Stankus S V
Published: December 2021

The experimental results of a study of the thermal expansion of Inconel 617 alloy in the temperature range of 293.15-1460 K are presented. An anomalous change in the thermal expansion coefficient at high temperatures was detected. The initial data are obtained with an error within 3%. The approximation equations and the table of reference values for the temperature dependence of the volumetric properties are obtained.
Numerical study of thermal stress of a silicon mirror forming a beam of synchrotron radiation
Authors: Finnikov K.A. , Vinokurov V.V. , Nikolenko A.D. , Zubavichus Y.V. , Kabov O.A.
Published: December 2021

Numerical simulation of heat transfer in a mirror for focusing a synchrotron radiation beam and its thermally stressed state has been carried out. The choice of the method for cooling the mirror through contact with the water-cooled plates, which provides the specified limitations on thermal deformation, has been substantiated. The modes of heat transfer, implemented under different conditions of heat transfer at the boundary of the mirror with water-cooled plates, are compared.
Analysis of ribbed tube heating in the cooling system
Authors: Gizzatullina A F , Mischenkova O V , Pushkarev F N , Terentyev A N
Published: December 2021

The paper presents the solution of the conjugated heat exchange problem in a cylindrical ribbed tube using the open integrated platform OpenFOAM. The obtained results allow estimating the fluid heating along the channel as well as the temperature difference on the walls of the tube. It is shown that the minimum temperature difference of the fluid is observed in the center of the tube, and the maximum one is closer to the tube walls.
Aerodynamics of airfoil moving along a circular trajectory
Authors: Bozheeva D M , Dekterev D A , Dekterev Ar A , Dekterev A A , Platonov D V
Published: December 2021

An experimental and computational study of the NACA0016 airfoil has been carried out for two cases: a stationary airfoil in an incoming flow on an aerodynamic stand and an airfoil moving along a circular trajectory in a stationary flow in a hydrodynamic stand. The Reynolds number for both cases was 60000. A qualitative comparison of the velocity fields for the cases with smooth airflow and boundary layer separation was carried out. It is shown that the used calculation methods describe the task under study with sufficient quality.
Modeling the conjugate problem of heat transfer at hot jet impingement onto a cooled surface
Authors: Lukashov V V , Naumkin V S
Published: December 2021

The paper solves the problem of thermal conductivity inside a flat plate under the impact of a hot jet of nitrogen impinging from one side and cooled by a gas flow from the other side. In this formulation of the problem, there may be local maxima and minima of the temperature inside the plate, caused by an uneven distribution of heat fluxes along the plate.
Influence of thermal gravitational-capillary convection on temperature fields in a thin wall
Authors: Bodneva N I , Berdnikov V S , Grishkov V A , Mikhailov A V
Published: December 2021

The development of convective flow in a layer of ethyl alcohol when heating one of the vertical walls of a rectangular cavity was investigated experimentally. Thermal films were obtained, whose processing allowed plotting in time the distribution of temperature and temperature gradients on the free surface of the liquid layer and the opposite thin vertical wall of the cavity after the flow of heated liquid on it.
Numerical and physical study of transitions to unsteady modes of melt flow with the Prandtl number 16 in the Czochralski method
Authors: Berdnikov V S , Vinokurov V A , Vinokurov V V
Published: December 2021

The evolution of the flow structure and heat transfer with an increase in the characteristic temperature drop in the ranges of Grashof and Marangoni numbers 3558 ≤ Gr ≤ 7116 and 2970 ≤ Ma ≤ 5939 are investigated numerically. The boundary of the transition to unsteady flow and heat transfer regimes has been determined.
Design features of a high-vacuum steam jet pump and some results of its tests
Authors: Petrova I V , Ermolov V I , Rebrov A K
Published: December 2021

This paper presents an original design of a high-vacuum steam jet pump in which a heater made of a heating cable is immersed in a working fluid located in a stainless steel boiler. At the same time, the boiler itself is vacuum isolated from the pump housing. There is also a heater made of a heating cable in a stainless steel shell, made in the form of a spiral and immersed in a working fluid. Such an arrangement of the heater is possible only when a liquid with a homogeneous chemical composition and a low saturated vapor pressure is used as a working fluid in high-vacuum pumps.
Analysis of the possibility of a submarine implosion using finite element method
Authors: Kiciński R , Szturomski B , Świątek K
Published: December 2021

Recently, there have been reports of disasters related to the disappearance of submarines. One of the potential causes of disasters is the ship’s descent to the so-called critical depth and its subsequent implosion. However, the occurrence of the submarine implosion phenomenon may be difficult to achieve. This is due to the presence of hydraulic fittings and other more susceptible hull components. The article presents an analysis of the strength of a fragment of the submarine’s hull, modelled on Kobben-class ships, to demonstrate the possibility of an implosion. Furthermore, the construction of submarines was presented, and phenomena related to the strength of submarine hulls using FEM were discussed.
Modelling of hardfacing layers deposition parameters using robust machine learning algorithms
Authors: Zając K , Płatek K , Biskup P , Łatka L
Published: December 2021

The study presents a data-driven framework for modelling parameters of hardfacing deposits by GMAW using neural models to estimate the influence of process parameters without the need of creating experimental samples of the material and detailed measurements. The process of GAS Metal Arc Welding (GMAW) hardfacing does sometimes create non-homogenous structures in the material not only in deposited material, but also in the heat-affected zone (HAZ) and base material. Those structures are not fully deterministic, so the modelling method should account for this unpredictable component and only learn the generic structure of the hardness of the resulting material. Artificial neural networks (ANN) were used to create a model of the process using only measured samples without any knowledge of equations governing the process. Robust learning was used to decrease the influence of outliers and noise in the measured data on the neural model performance. The proposed method relies on modification of the loss function and several of them are compared and evaluated as an attempt to construct general framework for analysing the hardness as a function of electric current and arc velocity. The proposed method can create robust models of the hardfacing layers deposition or other welding processes and predict the properties of resulting materials even for unseen parameters based on experimental data. This modelling framework is not typically used for metallurgy, and it requires further case studies to verify its generalisability.
FEM analysis of the manufacturing of hollow forgings from a tube billet
Authors: Bulzak T , Winiarski G , Wójcik Ł , Szala M
Published: December 2021

The study presents an analysis of the manufacturing process of a hollow forging. The process was proposed to consist of three stages. In the first stage (extrusion) wall thickness was reduced and the flange was formed. In the two subsequent stages the flange was formed. The material flow was examined using FEM. The issue of defect occurrence in the area of a hole caused by the material moving away from the mandrel was especially researched. Moreover, the strain state was analysed in the following forging operations. The distribution of the fracture criterion was presented. Moreover, a prediction of the forces necessary for the process to be performed in real conditions was carried out. The conclusion is that the proposed scheme of forming hollow forgings may be implemented in industrial conditions.
Cold forging of a hollow flanged part by an unconventional extrusion method
Authors: Winiarski G , Bulzak T , Wójcik Ł , Szala M
Published: December 2021

This paper presents a numerical analysis of a new cold forming process for a hollow part with an external flange. The following techniques were used: forward extrusion, an unconventional method of extrusion with a moving sleeve, and upsetting in a tapered die cavity. The billet (42CrMo4 steel tube) was formed at ambient temperature. The study aimed to investigate the proposed method in terms of forged part accuracy. The following are examined and discussed: material flow, process force parameters in relation to tool strength, energy consumption of individual operations, as well as the distributions of strains, stresses, temperature and Cockcroft-Latham integrals in the produced part. The study has confirmed that hollow forged parts with external flanges of relatively large diameters and heights can be cold formed in several operations using different techniques.
Application of artificial neural network (ANN) for water quality index (WQI) prediction for the river Warta, Poland
Authors: Kulisz M , Kujawska J
Published: December 2021

The aim of this paper is to present the potential of using neural network modelling for the prediction of the surface water quality index (WQI). An artificial neural network modelling has been performed using the physicochemical parameters (TDS, chloride, TH, nitrate, and manganese) as an input layer to the model, and the WQI as an output layer. The physicochemical parameters have been taken from five measuring stations of the river Warta in the years 2014-2018 via the Chief Inspectorate of Environmental Protection (GIOŚ). The best results of modelling were obtained for networks with 5 neurons in the hidden layer. A high correlation coefficient (general and within subsets) 0.9792, low level of MSE in each subset (training, test, validation), as well as RMSE at a level of 0.624507639 serve as a confirmation. Additionally, the maximum percentage of an error for WQI value did not exceed 4%, which confirms a high level of conformity of real data in comparison to those obtained during prediction. The aforementioned results clearly present that the ANN models are effective for the prediction of the value of the Surface water quality index and may be regarded as adequate for application in simulation by units monitoring condition of the environment.
Numerical calculations of the autorotating rotor under transient conditions
Authors: Czyż Z , Kazimierska A , Karpiński P , Skiba K
Published: December 2021

It is necessary to evaluate the performance of the main rotor in design stages of a rotorcraft to obtain the assumed lift force and low aerodynamic drag. This paper presents the CFD numerical analysis of the autorotating rotor under transient conditions. Auto-rotation is particularly important in the case of gyrocopters, while in the case of helicopters it is related to flight safety. The calculations allowed us to obtain aerodynamic forces and torque as a function of rotor azimuth for individual rotor blades. The analysis was performed for a rotor tilted by 15 degrees toward the airflow direction. A geometric model was created for the calculations and then a computational model was created in Ansys Fluent software. The k-ω SST model was adopted as the turbulence model which considers the turbulence kinetic energy and its unit dissipation. The obtained results are presented in a rotor and flow coordinate system.
Research on the Calibration Method of Torque Sensor
Authors: Cheng Lei , Su Yang , Wang Lifang
Published: December 2021

Remote calibration has the property of real-time and remote location, and can be used to control the calibration method for the calibration instrument. It is an effective method to improve the calibration efficiency. Based on the torque sensor calibration method for research, because the remote calibration technology has complex structure, calibration are not allowed to wait for a characteristic, through the remote technology combined with a torque sensor automatic calibration technology, analyze the torque sensor remote calibration technology research, which not only can improve the traditional calibration technology cycle is long, low efficiency of faults. Remote calibration technology based on the basic methods and characteristics are studied, by using the method of torque meter calibration, according to the characteristics of torque sensor, choose corresponding calibration program and method, which can effectively improve the technical problems in the process of system design and analysis of torque sensor remote calibration method research, in addition, through the analysis of electromagnetic interference technology research, which can restrain the interference is proposed; Finally, the remote calibration technology of the torque sensor is effectively improved through the calibration experiment of the system debugging.
Research on Key Technology of Security and Privacy Protection of Distribution Network Information Physical Fusion System
Authors: Tong Donghui , Di Zhuo , Ding Yi , Zhai Xianhui
Published: December 2021

As one of the most critical contents in the field of modern interdisciplinary research, information physical fusion not only changes the way of human interaction, but also promotes the development of modern information processing and development. Therefore, on the basis of making clear the current operation situation of distribution network information physical fusion system, this paper makes a simple understanding of the key technologies to guarantee system security and privacy from four aspects: security threat and response, crisis state and access control, reputation and trust management, and idle state monitoring algorithm.
One Early Warning and Traffic Control Method for Satellite Communication System and the Implement of Time Prediction Algorithm
Authors: Yang Qiang
Published: December 2021

This article introduces an early warning and control method of user satellite communication traffic applied to satellite communication system. Due to the high communication cost of transportation satellites, in order to avoid high communication bills, the full-service ability to collect call data records (CDR) by Transportation Satellite Business Support System is required to provide early warning and business control over the four dimensions of voice, data, text messages, and package fees for satellite communications. At the same time, the system predicts the typical user behavior through the time series prediction Prophet algorithm, which serves as the default reminder rule to achieve full coverage of users.
Research on the Design of Digital Signal Processing Algorithm Based on Spark Parallel Calculation
Authors: Ming Yifan , Li Rui
Published: December 2021

Digital signal processing as a key and difficult point of network technology research and development, currently commonly used content such as LabVIEW. But from a practical point of view, while these techniques can be used to process real-time signals, they can’t handle historical offline data. The Spark parallel computing studied in this paper can be used to process offline signals. Therefore, on the basis of understanding the development trend of Spark parallel computing framework, the distributed Mallat algorithm is analyzed based on Spark parallel computing engine, and the application performance of the corresponding algorithm is verified.
Application of Fuzzy Mathematics Algorithm in Computer Speech Recognition
Authors: Zhou Xuan
Published: December 2021

Speech recognition, as one of the key artificial intelligence technologies in modern development, plays an important role in any aspect. However, there are still problems in practical application, such as poor anti-interference and low degree of perfection. Therefore, this paper aims at the content of existing computer speech recognition technology, grasps fuzzy mathematical algorithm, and analyzes how to use this algorithm to better study computer speech recognition.
Implementation and Application of Fall Detection on Mobile Perception Robot
Authors: Chen Zeyu
Published: December 2021

With the rapid increase in the number of people living in the elderly population, reducing and dealing with the problem of falls in the elderly has become the focus of research for decades. It is impossible to completely eliminate falls in daily life and activities. Detecting a fall in time can protect the elderly from injury as much as possible. This article uses the Turtlebot robot and the ROS robot operating system, combined with simultaneous positioning and map construction technology, Monte Carlo positioning, A* path planning, dynamic window method, and indoor map navigation. The YOLO network is trained using the stance and fall data sets, and the YOLOv4 target detection algorithm is combined with the robot perception algorithm to finally achieve fall detection on the turtlebot robot, and use the average precision, precision, recall and other indicators to measure.
Research on the Method of Machine Learning Algorithms in Ecological Construction
Authors: Xia Binjie
Published: December 2021

In the rapid development of modern artificial intelligence, for the development of ecological construction, how to rationally use machine learning to promote the development of agricultural economy has become a focus of practice and scientific research. This paper takes ecological image recognition as an example to analyze how to use support vector machine in image processing technology and machine learning in deep learning to conduct in-depth research, and to optimize and improve the algorithm to build an ecological image recognition model.
Design Specification for Network Fault Diagnosis System
Authors: Cao Lu , Wang Baosheng
Published: December 2021

As the network becomes more and more complex and heterogeneous, the problem of network management becomes more and more prominent. The research and application of network management is of great significance for ensuring the normal operation of network and improving the reliability and availability of network system. The main problems of network management are network configuration, failure, performance, security, planning and scaling, etc. On the basis of in-depth research and discussion on network management and fault management, this paper designs the system requirements of network fault diagnosis system.
RIPTIDE: a novel recoil-proton track imaging detector for fast neutrons
Authors: Musumarra A. , Leone F. , Massimi C. , Pellegriti M.G. , Romano F. , Spighi R. , Villa M.
Published: December 2021

Neutron detectors are an essential tool for the development of many research fields, as nuclear, particle and astroparticle physics as well as radiotherapy and radiation safety. Since neutrons cannot directly ionize, their detection is only possible via nuclear reactions. Consequently, neutron-based experimental techniques are related to the detection of charged particle or electromagnetic radiation originating from neutron-induced reactions. The study of fast neutrons is often based on the neutron-proton elastic scattering reaction. In this case, the ionization induced by the recoil protons in a hydrogenous material constitutes the basic information for the design and development of neutron detectors. Although experimental techniques have continuously improved and refined, so far, proton-recoil track imaging is still weak in laboratory rate environments because of the extremely small detection efficiency. To address this deficiency, we propose a novel recoil-proton track imaging system in which the light deriving from a fast scintillation signal is used to perform a complete reconstruction in space and time of the event. In particular, we report the idea of RIPTIDE (RecoIl Proton Track Imaging DEtector): an innovative system which combines a plastic scintillator coupled to imaging devices, based on CMOS technology, or micro channel plate sensors. The proposed apparatus aims at providing neutron spectrometry capability by stereoscopically imaging the recoil-protons tracks, correlating the spatial information with the time information. RIPTIDE intrinsically enable the online analysis of the ionization track, thus retrieving the neutron direction and energy, without spoiling the overall efficiency of the detection system. Finally, the spatial and topological event reconstruction enables particle discrimination — a crucial requirement for neutron detection — by deducing the specific energy loss along the track.
Influence of B2O3 doping on synthesis of MgTiO3 ceramics from recycled magnesia-hercynite materials
Authors: Jia Xiaodong , Mao Shuo , Tian Lin , Chen Shujiang , Li Guohua , Gao Wei
Published: December 2021

Herein, magnesium metatitanate (MgTiO3) ceramics were synthesised using recycled magnesia-hercynite (MH) bricks as the raw materials to achieve solid waste reusing of cement kiln refractories. The recycled MH materials were mixed with anatase TiO2 to investigate the effect of addition of doped B2O3 during the synthesis of MgTiO3 ceramics at 1400 °C. Phase compositions and microstructural studies were performed using x-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. In addition, energy-dispersive spectroscopy (EDS) was conducted and the dielectric properties of the samples were studied. Results show that the addition of B2O3 can promote sintering, improve shrinkage, promote densification, stabilise MgTiO3 lattice, and inhibit the formation of MgTiO3. In addition, the presence of appropriate amount of B2O3 can accelerate the material diffusion and result in grain growth through the formation of intercrystalline liquid phase. Results also suggest that an increase in dielectric constant results in a decrease in dielectric loss. It was concluded that 2 wt% was the optimum amount of B2O3 required to obtain the most favourable synthesis rate of MgTiO3 (98.2%). The samples exhibited a maximum density of 3.69 g·cm−3 and excellent microwave dielectric properties at ε
r = 18.28 and tanδ = 0.086.
Fabrication of superhydrophobic surface with corrosion resistance via cyclic chemical etching process on aluminum substrate
Authors: Lv Shuwei , Zhang Xinming , Yang Xiaodong , Liu Xianli , Yang Zhuojuan , Zhai Ying
Published: December 2021

Aluminum (Al) is a metal material commonly used in industry, but its surface is easily corroded. The superhydrophobic surface has great self-cleaning and anti-corrosion properties, and it is an ideal method to construct a functional aluminum surface. Here, a simple method based on cyclic chemical etching was proposed to achieve the superhydrophobic Al surface with honeycomb structures. The surface of the sample etched eight times comprised micro/nano-scale honeycomb cavities, while exhibiting a water contact angle (WCA) of 135°. After being treated with an octadecanethiol (C18H38S) methanol solution, this sample demonstrated a WCA of 153.1°. A self-cleaning test was performed on the superhydrophobic Al surface, showing the excellent self-cleaning property. Finally, the electrochemical anti-corrosion test demonstrated that the above-mentioned superhydrophobic Al surface had great corrosion resistance property. Overall, this work has enriched the theory and technology for fabricating aluminum to achieve superhydrophobic.
The size effect of martensite laths and precipitates on high strength wear-resistant steels
Authors: Xue Huan , Zhang Yansong , Zhu Min , Yin Xiyan , Zhang Wenqian , Liu Shengnan
Published: December 2021

Low alloy high strength wear resistant steels are with high toughness, low cost and good abrasion resistance. It can effectively resist the propagation of wear cracks and prolong the service life of machine components. This paper focuses on the internal relationship between macroscopic physical properties and microscopic martensite lath and precipitate size throughout thickness of wear resistant steel. Four kinds of 40mm thickness wear resistant steels with different alloy chemical composition were produced and investigated. Results show the strength and hardness performance of ARIV are obviously higher than other three steels. ARI have a relatively large strength difference through thickness. The impact toughness of ARIV is relatively uniform, which is greater than that of the ARIII at middle layer and lower than that of the ARIII at 1/4 layer. The width of martensite lath of ARIV is relatively small, mainly 100 ∼ 300 nm, while that of ARII and ARIII is mainly 200 ∼ 400 nm. ARIV steel has shorter martensite lath band and more precipitates below 50 nm. It indicates that the size of martensite laths and precipitates of wear-resistant steels are important factors to determine its performance throughout thickness.
Virtual monochromatic imaging reduces beam hardening artefacts in cardiac interior photon counting computed tomography: a phantom study with cadaveric specimens
Authors: Inkinen Satu I , Juntunen Mikael A K , Ketola Juuso , Korhonen Kristiina , Sepponen Pasi , Kotiaho Antti , Pohjanen Vesa-Matti , Nieminen Miika
Published: December 2021

In interior cardiac computed tomography (CT) imaging, the x-ray beam is collimated to a limited field-of-view covering the heart volume, which decreases the radiation exposure to surrounding tissues. Spectral CT enables the creation of virtual monochromatic images (VMIs) through a computational material decomposition process. This study investigates the utility of VMIs for beam hardening (BH) reduction in interior cardiac CT, and further, the suitability of VMIs for coronary artery calcium (CAC) scoring and volume assessment is studied using spectral photon counting detector CT (PCD-CT). Ex vivo coronary artery samples (N = 18) were inserted in an epoxy rod phantom. The rod was scanned in the conventional CT geometry, and subsequently, the rod was positioned in a torso phantom and re-measured in the interior PCD-CT geometry. The total energy (TE) 10–100 keV reconstructions from PCD-CT were used as a reference. The low energy 10–60 keV and high energy 60–100 keV data were used to perform projection domain material decomposition to polymethyl methacrylate and calcium hydroxylapatite basis. The truncated basis-material sinograms were extended using the adaptive detruncation method. VMIs from 30–180 keV range were computed from the detruncated virtual monochromatic sinograms using filtered back projection. Detrending was applied as a post-processing method prior to CAC scoring. The results showed that BH artefacts from the exterior structures can be suppressed with high (≥100 keV) VMIs. With appropriate selection of the monoenergy (46 keV), the underestimation trend of CAC scores and volumes shown in Bland-Altman (BA) plots for TE interior PCD-CT was mitigated, as the BA slope values were −0.02 for the 46 keV VMI compared to −0.21 the conventional TE image. To conclude, spectral PCD-CT imaging using VMIs could be applied to reduce BH artefacts interior CT geometry, and further, optimal selection of VMI may improve the accuracy of CAC scoring assessment in interior PCD-CT.
A Torelli theorem for moduli spaces of parabolic vector bundles over an elliptic curve
Authors: Fassarella Thiago , Justo Luana
Published: December 2021

Let

C
C

be an elliptic curve,

w
∈
C

w\in C

, and let

S
⊂
C

S\subset C

be a finite subset of cardinality at least

3
3

. We prove a Torelli type theorem for the moduli space of rank two parabolic vector bundles with determinant line bundle

O

C

(
w
)

\mathcal O_C(w)

over

(
C
,
S
)

(C,S)

which are semistable with respect to a weight vector

(

1
2

,
…
,

1
2

)

\big (\frac {1}{2}, \dots , \frac {1}{2}\big )

.