bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational studies to determine the design of prototype heater for a hypersonic wind tunnel
Authors: Rtishcheva A S
Published: November 2021

During the modernization of the TsAGI hypersonic wind tunnel, which implies an increase in the limiting values of the flow stagnation parameters, and in the thermal load, consequently, computational studies were realized for the existing design of the electric arc heater and new geometry options for the central electrode and the cooling duct of the external electrode and nozzle. The distribution of the heat flux density to the surfaces of the main elements of the wind tunnel was obtained based on the calculations for the air duct of wind tunnel. The qualitative data of the flow formation both in the pre-heater and the pre-chamber served as the basis for changing the geometry of the central electrode. In this study, a numerical modelling approach was implemented for a through calculation of the flow and heat transfer in all areas of the wind tunnel circuit (heater, pre-chamber, nozzle, test section, diffuser). The ANSYS FLUENT software package was used to solve the axisymmetric Navier-Stokes equations for a five-component chemically reacting gas mixture: O2; N2; O; N; NO using the Spalart-Allmaras turbulence model. To study the hydrodynamics and thermal state of the structure of the external and central electrodes, the possibility of the ANSYS FLUENT complex for solving conjugate problems was used (the complete Navier-Stokes equations and the energy balance equation were solved in a fluid, and the heat conduction equation was solved in a solid). In this case, at the interface between the media, the conditions for the continuity of temperature and heat flux were satisfied.
Giesekus fluid flow past a sphere in a pipe
Authors: Kadyirov A I , Zaripov R R , Kutuzova E R , Vachagina E K
Published: November 2021

A numerical simulation of a viscoelastic fluid flow past a sphere in a round pipe is carried out. The four mode Giesekus model is taken as a rheological model. By the example of a polymer melt flow, the features of the flow around a sphere in comparison with the flow around a cylinder are revealed. Velocity and stress profiles for polymer melt and polymer solution fluid flow around a sphere at the same Weissenberg numbers are analyzed.
Semi-analytical solution for the problem of extended Pom-Pom fluid flow in a round pipe
Authors: Kadyirov A I , Vachagina E K
Published: November 2021

A semi-analytical solution to the problem of the steady flow of viscoelastic single equation eXended Pom-Pom (XPP) fluid in a round pipe using the four-mode rheological equation of state of XPP is presented. An original parametric method for solving the set problem is used. The resulting method is applicable for solving a similar problem in a flat slit. The developed solution method is tested by comparing it with numerical results and experimental data. Using a polyacrylamide solution as an example, the influence of the Weissenberg number on the axial velocity profiles and the components of normal stresses is studied.
Studying the unsteady characteristics of a laminar transonic buffet depending on the angle of attack
Authors: Polivanov P A , Sidorenko A A
Published: November 2021

Laminar transonic buffet on the airfoil for low Reynolds numbers of 0.5-0.7⋅106 was experimentally studied. Basic experiments were performed using high-speed schlieren imaging. The unsteady flow structure was investigated using various methods. It was found that shock wave oscillations can be significantly different from the turbulent case. The frequency and amplitude characteristics of oscillations from the angle of attack were found.
Computational study of the efficiency of various methods of intensification of convective heat transfer
Authors: Frantsuzov M S
Published: November 2021

This paper presents the results of a computational study of the efficiency of various methods of heat transfer intensification in model channels containing various types of intensifiers. The following methods of intensification of convective heat transfer are considered: acoustic, the intensifiers twisted tape, wire spiral, and joint intensifier of a wire spiral and twisted tape. The study of thermal and hydraulic processes in the channels is carried out using computer modeling based on the solution of the Navier-Stokes equations averaged by Reynolds, the energy and state equations supplemented by the turbulence model. The thermal and hydraulic characteristics of various methods of heat transfer intensification are determined in the range of Reynolds numbers from 10000 to 60,000, and the efficiency of the intensification is determined based on the author's criterion. The characteristics of a smooth channel in the above-mentioned range of Reynolds numbers are considered as reference thermal and hydraulic characteristics. Comparative analysis has shown that the acoustic method of heat transfer intensification is most effective in the range of Reynolds numbers, where different modes of self-sustaining acoustic oscillations occur. The presented results may be used in the development and design of heat exchangers.
Applying the scalability apparatus to estimate the thermal efficiency of a single finned tube
Authors: Gizzatullina A A , Mishchenkova O V , Pushkarev F N
Published: November 2021

The paper explores the possibility of scaling the integral parameters of the cooling system operation using the working elements with the length from 0.01 to 0.5 m. Numerical solution of the conjugate problem of external aeromechanics, internal hydrodynamics and heat exchange is carried out. Parametric studies of the cooling process and aerodynamic resistance of finned tubular elements of various lengths are performed. As a result of generalization and unification of the computational experimental data, a numerical coefficient has been obtained to calculate the necessary integral characteristics for a cooling element of the assigned length.
Solid-state mechanochemical technology for deep processing of brown coal: energy efficiency improvement and dust formation control
Authors: Matveeva AG , Skripkina TS , Bulanova UE , Bukhtoyarov VA , Bychkov AL , Lomovsky I O
Published: November 2021

Energy efficiency – a compromise between reaction depth and expended energy - is an actual question for any technology implementation. Mechanochemical technology for brown coal deep processing has one more compromise - between reaction depth and dust formation. Indeed, the depth of mechanochemical reactions usually correlates with grinding efficiency, but for coal cases dust formation is an unwanted process. Here we consider a solid-state mechanochemical reaction of humic acid oxidation by sodium percarbonate in one laboratory mill at different conditions. The ratio between the grinding bodies load and the payload was varied, the reaction yield and the ground samples characteristics were controlled.
Numerical study of single bubble mobility in triangular and deltoid microchannels using the boundary element method
Authors: Bulatova A Z , Solnyshkina O A , Fatkullina N B
Published: November 2021

The study of bubbly liquid dynamics in microchannels of unconventional shapes is of great importance for different fields of science and industry. This work investigates the dynamics of the incompressible single bubbles in the slow periodic flow of viscous liquid in a triangular channel with a variable pressure gradient. The numerical approach used in this research is based on the boundary element method (BEM). This method is widely used for solving three-dimensional problems and problems in areas with complex geometry. The influence of the bubble’s initial position relative to the channel centerline on the bubble deformation, the relative velocity of the bubble, and its center of mass displacement in the channel are considered.
Comparing hydrogen absorption kinetics of the samples of intermetallic compound and metal hydride compact on its basis
Authors: Romanov I A , Borzenko V I , Kazakov A N
Published: November 2021

This work is devoted to an experimental study and comparison of the kinetics of hydrogen absorption by an intermetallic compound LaNi4.4Al0.3Fe0.3 in form of pure intermetallic compound free backfill and a compact based on it obtained by cold pressing with a spiral matrix of nickel-foam. To calculate the kinetic parameters of the hydrogen absorption reaction, the initial rates method is used. The PCT absorption isotherms are measured at temperatures of 313, 333, and 353 K. The experimental data are described with quite high confidence by the chosen model, which assumes that the reaction rate controlling step is the dissociative absorption of hydrogen on the surface of the a-phase. The rate of hydrogen absorption increases with increasing pressure drop and temperature. It is shown that the rate of hydrogen absorption by the sample of pure IMC is significantly less dependent on temperature compared to the compact sample. In addition, the reaction rate at temperatures of 313 and 333 K is higher for the free backfill sample, and at 353 K it is higher for the metal hydride compact. The values of the absorption constant and the activation energy of the hydrogen absorption reaction are determined for both samples.
Mathematical modelling of a laminar suspension flow in the flat inclined channel
Authors: Iulmukhametova R R , Musin A A , Kovaleva L A
Published: November 2021

The laminar flow of a suspension consisting of viscous incompressible fluid with solid spherical particles of the same size in a flat inclined channel is investigated in this work. The mathematical model is formulated in a one-fluid approximation in a three-dimensional statement and solved in the OpenFOAM software package. The results of mathematical modeling are compared with experimental data. The study of the dynamics of the distribution of solid spherical particles in the flow and sedimentation along the length of the channel depending on the size of particles and the angle of inclination of the channel relative to the horizon is carried out.
Incipience of the intensive heat transfer regime at cooling high-temperature bodies in subcooled liquid
Authors: Kanin P K , Yagov V V , Zabirov A R , Lexin M A
Published: November 2021

Cooling in film boiling is usually an unwanted process in many technologies due to low intensity of heat transfer. Thus, predicting the solid wall superheat at vapor film destabilization is useful to avoid this phenomenon. In the present paper, two new semi-empirical models for evaluation of the wall superheat at destabilization of vapor film around the metallic body cooled in saturated or in subcooled liquid are proposed. Both models with fitted empirical multipliers are in good agreement with an experimental dataset. To evaluate the contribution of the natural convection in the model for temperature head at cooling in subcooled liquid, a problem about the natural convection near the vapor film, occurring during film boiling along the vertical plane, is numerically solved by means of ANES20XE CFD-code. The computational results of longitudinal velocity are in good agreement with the theoretical velocity of natural convection used in the model.
Features of cooling bodies with a high coefficient of thermal effusivity in subcooled mixtures
Authors: Zabirov A R , Molotova I A , Ryzantcev V A , Gubanova T A , Yagov V V
Published: November 2021

The paper focuses on the study a special type of boiling, "microbubble boiling". Experiments are carried out on water-ethanol mixtures of different concentrations. The pressure varies from 0.1 to 0.3 MPa; and copper and stainless-steel samples are used as working samples. The purpose of the experiments is to investigate the effect of such parameters as solid and liquid properties and subcooling on the transition temperature from the stable film boiling to “microbubble” boiling regime. In the course of direct comparison of the results obtained by cooling the samples with different thermal effusivity under the same conditions, a strong influence of the properties of the cooled body on the quenching process has been revealed.
Mathematical modelling of a staged pulverized coal gasification using O2/CO2 mixtures
Authors: Donskoy I G
Published: November 2021

Conversion of pulverized coal in a two-stage gasifier is studied. When considering carbon capture power plants, mixtures of oxygen with carbon dioxide may be used as a gasification agent. Carbon dioxide is a gasification agent, so characteristics of the gasification process change significantly compared to gasification in oxygen-nitrogen mixtures. The conversion efficiency is determined by the thermophysical factor (change in the heat capacity of the gas mixture and transfer coefficients) and the concentration factor (increase in the concentration of the gaseous reagent). The ratio of primary and secondary fuel consumption determines the leading stage of the process. The influence of process efficiency on oxygen concentration is estimated in the range of 21–30 vol. %.
Numerical modeling of subsonic axisymmetric reacting gas flows
Authors: Peskova E E
Published: November 2021

A numerical algorithm is developed and implemented for modelling axisymmetric subsonic reacting gas flows based on a previously created program for plane flows. The system of Navier-Stokes equations in the low Mach number limit is used as a mathematical model. Calculations of ethane pyrolysis for axisymmetric and plane flow of mixture at heat supply from the reactor’s walls are carried out. Through the interplay of the developed code and the code for plane flows it becomes possible to identify the geometric factor role at the presence of a large number of nonlinear physicochemical processes. We found that diffusion of synthesized molecular hydrogen mainly influences heat supply from the reactor’s walls to gas and pyrolysis products distribution along its length.
Numerical Simulation of 3D Flow over a Circular Cylinder
Authors: Kusyumov A N , Kusyumov S A , Mikhailov S A , Romanova E V
Published: November 2021

Unsteady 3D flow over a circular cylinder at Reynolds number of 3900 is studied numerically using the Navier-Stokes equations. Two formulations of the problem were considered: with boundary conditions corresponding to the flow around an isolated cylinder and with periodic boundary conditions to the flow behind a parallel circular cylinders grid. A comparative analysis of the integral and distributed characteristics of the flow around the cylinder and the spectral characteristics of the flow for both formulations of the problem is carried out.
Effect of the THF molecules on the hydrate cavities formation with adding NaCL molecules into the modeling system
Authors: Bozhko Y Y , Zhdanov R K , Getz K V , Belosludov V R
Published: November 2021

In this work, using molecular dynamics methods by Gromacs package we simulate the hydrate formation in systems containing THF, water, and NACL molecules at different thermodynamic conditions and concentration of THF molecules. The curves of the number of hydrogen bonds are obtained depending on the simulation time at different temperatures. The computer simulations results show that the hydrogen bonds between THF and water molecules are relatively weak, with a maximum number of two water molecules hydrogen bonded to THF, but THF can facilitate water molecules rearrangement to form a pentagonal or hexagonal planar ring that is the part of clathrate cavity. In addition, the THF molecule can significantly increase the likelihood to form clathrate cavities suitable for the second guest molecule. The effect of THF molecules concentration on the hydrate cavities formation with adding NaCL molecules into the modeling system is shown. In this work, data are obtained on the magnitude of torsion angles, the percentage of which increases depending on the simulation time, which allows concluding that labile large and small cavities of sII hydrates are formed. The increase in the THF molecules concentration is shown to lead to a decrease in the hydrogen bonds number of water molecules in the simulated system.
Application features of micro-pixel avalanche photodetectors in the laser Doppler anemometers
Authors: Rakhmanov V V , Dvoynishnikov S V , Meledin V G , Pavlov V A , Semenov D O
Published: November 2021

The optical receiver is an essential part of any laser Doppler anemometer. Traditionally, vacuum photomultiplier tubes are used for reliable reception of weak optical radiation. However, this type of photodetector has its own drawbacks, which lead to a design complication and an increase in the cost of LDA. In this work, the characteristics of silicon micropixel avalanche photodiodes are investigated and the operation of a silicon photomultiplier as a photodetector in an LDA is tested when measuring the velocity on test benches. The possibility of using Si-PMT to receive optical signals of the laser Doppler anemometer is shown.
Geometry Monitoring of Rotating Parts of Power Unit with an Adapted Doppler Preprocessor
Authors: Kulikov D V , Dvoynishnikov S V , Rahmanov V V , Pavlov V A , Kabardin I K
Published: November 2021

Current work is devoted to the development of a device for monitoring the dynamic shape of a power unit. The work is based on the FMCW method. The light source uses a low-coherence semiconductor laser diode. Signal processing is performed on an adapted Doppler processor. The paper describes the methods, hardware and signal processing algorithms.
Developing the laser doppler anemometry method for the diagnostics of kinematic parameters of a turbulent flow in the near wall region
Authors: Meledin V G , Dvoinishnikov S V , Kabardin I K , Chubov A S , Bakakin G V , Kabardin A K , Pavlov V A , Pravdina M Kn , Yavorsky N I
Published: November 2021

The aim of the work is to develop a laser Doppler anemometry method for diagnosing turbulent aerodynamic flows in the near wall region. This will enable measuring two projections of the velocity vector in the range of 0.001 … 400 m/s with a relative error not exceeding 0.1%. The measurement area is 0.1×0.1x0.5mm. The positioning device allows moving the measuring unit in the area of 250×250x250 mm with an accuracy of 0.1 mm. This method also provides the ability to measure local flow rate fluctuations.
Thermodynamic modeling of melt of the Bi-Pb-Sn-Cd system
Authors: Barbin N , Tikina I , Terentyev D
Published: November 2021

Thermodynamic modeling of heating of the Bi-Pb-Sn-Cd system in a wide temperature range is performed in the TERRA software package. The equilibrium constants of thermal dissociation reactions are determined. The equilibrium constants of thermal dissociation reactions for metal compounds formed in the Bi-Pb-Sn-Cd melt as a result of heating are determined: BiPb, PbSn, SnBi, Pb3Bi, Pb5Bi4Sn4, PbSn3, Bi2Sn3, Bi7Pb, CdSn, Sn3Bi, PbBi2Sn2, Pb3Bi4, Cd3Bi2, Bi7Pb3, Sn4Bi2.
Investigating the adhesive properties of polymers for 3D printing
Authors: Vendland L E , Volkov-Muzylev V V , Demidov A N , Pugachuk A S
Published: November 2021

The article presents the research of adhesive properties of various polymers used in additive manufacturing by fused deposition modeling. Tensile tests of additively manufactured samples of various polymers are carried out, electro-microscopic photographs of the working area are taken before and after tests, and studies on the manufacturability of printing are performed to exclude further typical errors identified during these tests. Samples of the following polymers are studied: thermoplastic resin acrylonitrile butadiene styrene (ABS +), thermoplastic resin acrylonitrile butadiene styrene with the addition of titanium nitrite as a dye (ABS + TiN), thermoplastic resin acrylonitrile butadiene styrene with the addition of polyester inserts (ABS polylactide (PLA), polylactide based compound (PLA HP), thermoplastic polyethylene terephthalate glycol (PETG), and nylon with carbon inserts (NSC). The work reveals the advantages and disadvantages of the investigated plastics. For example, deformations occur when the part is cooled down during printing process of ABS +, and a crack could form in stress concentrators as a result of the influence of cold air flows.
The analysis of the level of emission characteristics depending on the aerosol structure
Authors: Vasilev A Yu
Published: November 2021

An attempt to combine the main verified recommendations for the organization of low-emission combustion of fuels (in relation to three main components of standardized harmful substances SN, NOx, and CO2) into one of the crucial modern problemsis implemented. Thepaper is devoted to the search for some general trends in the formation of emission characteristics based on the accumulated experience such as computational and experimental results obtained in CIAM.
Analysis of the cladding melt relocation along the surface of the fuel pin with help of the SAFR module
Authors: Usov E V , Lobanov P D , Klimonov I A , Sycheva T V , Chuhno V I , Butov A A , Kudashov I G
Published: November 2021

The presented work is dedicated to the development of approaches to simulate cladding melt relocation along the surface of the fuel pin. Development of the approaches is based on the results of the experiments carried out at the NSI RAS and IT SB RAS. Features of the melt relocation are studied in the experiments. It is demonstrated that the laminar film flow regime in the heated part of the fuel simulator is the main flow regime. Model of the melt relocation is constructed. This model is the part of the SAFR module of the EUCLID/V2 coupled code. It is shown that the proposed approaches allow simulating the melt relocation with good accuracy.
Long-term and seasonal anomalies of the Sea of the Azov thermohaline structure for 1913 – 2018
Authors: Shukalo D M , Shul’ga T Ya
Published: November 2021

Variability of temperature and salinity as well as quantifying global trends are fundamental for understanding changes in the Earth's climate. In current paper, a long-term variability of the hydrological regime of the Sea of Azov for 1913–2018 is studied. On the basis of oceanographic information, the seasonal variability of temperature and salinity by the areas of the Sea of Azov is analysed. Temperature anomalies have been revealed, periods of salinization and desalination of the Sea of Azov have been noted and linear trends of the anomaly have been obtained.
Calculating the effective thickness of the thermal barrier coating
Authors: Lukashov V V , Naumkin V S
Published: November 2021

The paper presents the results of numerical simulation of heat transfer at the interaction of a hot impact nitrogen jet with a ceramic thermal barrier coating 7YSZ based on ZrO2 with the addition of 7% Y2O3. The radiant component of heat transfer is shown to make a significant contribution to the final temperature distribution on the surface of the protected product.
The Effect of UV Irradiation on Tensile Strength of Polypropylene Reinforced Kenaf Fiber and Peat Soil
Authors: Joharudin Nurul Farahin Mohd , Mustapa Mohammad Sukri , Supawi Aiman , Latif Noradila Abdul , Hussin Wan Nasrul Nizam Wan , Alias Mohd Fairuz , Kamarudin Kamarul-Azhar , Ariffin Ahmad Hamdan , Yusof Farazila
Published: November 2021

Nowadays, natural fiber polymer composites have been widely used in many industries and applications because of their low cost, renewable and eco–friendly. However, exposing this material to the outdoor environment will affect the material properties as it is exposed to various situations such as ultraviolet exposure, raining, etc. This paper studies the degradation of kenaf fiber, polypropylene strengthened with peat soil combustion at 600ºC upon ultraviolet exposure. The wood–plastic composites (WPCs) produced into two batches, kenaf fiber mixing with polypropylene and kenaf fiber and peat soil mixing with polypropylene. All the specimen has exposed in ultraviolet (UV) irradiation at 0 hour, 100 hours, and 200 hours, respectively. The UV irradiation accelerated weathering tester machine was conducting the water spray cycle, which is 4 hours of water spray and 8 hours without water spray continuously until achieved the target time. The finding obtained from the tensile test, the composition with the highest contain of kenaf fiber in a polymer composite, has the lowest tensile strength after exposed with 200 hours of UV irradiation, which is 20.23 MPa. While the adding peat soil as reinforcement has shown the increasing the percentage of tensile strength after 200 UV exposure.
Efficiency improvement of solar cells by CaAlSiN3:Eu2+and Y2O3:Eu3+phosphors
Authors: Huang Shaoqiang , Lou Chaogang , Diao Han , Wang Zhaoyong , Yin Yunzhen
Published: November 2021

CaAlSiN3:Eu2+(CASN) and Y2O3:Eu3+(YO) phosphors are mixed into ethyl vinyl-acetate (EVA) to form luminescence down-shifting (LDS) films which are used to improve crystalline silicon solar cells by converting the photons with the wavelength from 200 nm to 500 nm into red light. Experimental results show that the conversion efficiency of the solar cells is enhanced from 19.61% to 20.00%. The improvement is better than that with only CASN phosphors in EVA films. The reason is the high quantum yield of YO phosphors in the wavelength range 250 nm-350 nm, which offsets the poorer performance of CASN phosphors in this wavelength range.
A Demodulation Circuit For Analog Front End Of Passive Tag Chip
Authors: Li Qinglong , Xu Yong , Li Qiao , Peng Kun , Zhang Xian
Published: November 2021

The demodulation circuit designed in this paper is suitable for the analog front end of passive UHF RFID tag chip, which can handle ASK signals with large changes in amplitude, modulation depth and signal frequency. Its performance meets the requirements of standards ISO/IEC 18000-6C and GB/T 29768-2013. Envelope detection circuit and limiter circuit are simple in structure and do not consume power. The comparison reference voltage is taken according to the average value of the envelope high and low levels, and is less affected by the dynamic changes of the input signal. Changing the width-to-length ratio of the MOSFETs in the feedback path of the comparator can adjust the hysteresis, with strong noise suppression and controllable sensitivity. The demodulator is implemented with TSMC 0.18 μm standard CMOS process. The simulation results show that the ASK signal modulation depth that the demodulator can handle is as low as 30%, and the maximum pulse width demodulation error is only 0.43%.
Research on Thermal Fatigue Life Prediction Technology of PoP Laminated BGA Products
Authors: Ran Hong-lei , Sheng Xiao-jie , Duan Qiang , Zhang Kui , Huang Jie
Published: November 2021

In this paper, a fast prediction method for thermal fatigue life of PoP laminated BGA Product was proposed. Firstly, the stress and strain of the solder joints of each layer of the laminated device in thermal fatigue test was determined by finite element simulation method. According to the research idea of relative stress and strain, the solder joints were divided into sensitive solder joints and reliable solder joints. Secondly, sensitive solder joint were connected with PCB traces through the internal pads, bonding wires, TSVs and reliable solder joints to form a daisy chain. Through real-time dynamic monitoring of the resistance change of the daisy chain in thermal fatigue test to judge whether the solder joints fail, and record the occurrence time of the first failure solder joint. Finally, the thermal fatigue life of the product was estimated by the Norris-Landzberg formula.
Influence of Noise on Fault Diagnosis of Transformer based on Vibration Signal
Authors: Chen Ming-hao , Zhou Quan , Ou Yangxi
Published: November 2021

Monitoring transformer vibration signals is a universal application method to realize the diagnosis of internal mechanical faults of transformers. However, the actual transformer operating is interfered by the noise of the surrounding electrical equipment, which reduces the accuracy of the vibration signal identification. This paper simulate the typical noise sources in the actual transformer operating environment, including fan noise and surrounding equipment fault noise, and explore the impact of different noise sources on the transformer vibration signal.
Analysis of the Response of a Static Reactive Power Compensator to Instability and Failure in Electrical grids
Authors: Maridueña Víctor Manuel , Castro Edwin Arnaldo , Layedra Nelson
Published: November 2021

The reliability of electrical power systems has led to the implementation of new equipment with reliable technology to solve transient failures, in recent decades flexible AC transmission systems (FACTS) have been implemented in power grids, resulting in high levels of stability and control. One of the elements used is static VAR compensators (SVC), however there is very little information about the dynamic response of the device to network instability and electrical failures, for which Simulink analyses the response of the SVC. The device consists of a 47.1 MVar reactive power compensator and a 97.6 MVar inductive reactivator compensator, implemented in a three-phase 500 kV system. The results indicate the effectiveness of response against network instability while maintaining the stable voltage of the network, but against electrical failures the type and time of failure must be considered. In the case of phase-phase faults, the response of the SVC is limited with drops of 0.52 pu.
Rock Image Intelligent Classification and Recognition Based on Resnet-50 Model
Authors: Liu Jinzi , Du Wenying , Zhou Chong , Qin Zhiqing
Published: November 2021

Machine learning algorithms becomes popular for intelligent classification of rock images. In this paper, it selects Resnet 50 neural network model to divide the data sets based on the rock pictures taken under the white light lamp. By continuously adjusting the parameters of each layer, the intelligent classification of rocks is carries out. The training final validates accuracy reached 94.12%.
Research on method of mitigating instability of wind power generation system based on hydrogen production
Authors: Chen Mengping , Ren Jianxing , Li Fangqin , Sun Haijie , Wang Ze
Published: November 2021

Intermittent power generation of renewable energy power generation system is the active reason affecting the stability of power grid, and adjusting the load imbalance between power generation and power supply through hydrogen production unit is the main means to reduce the impact of natural conditions and ensure continuous and stable power supply. In this paper, the simulation model of permanent magnet direct drive fan system for hydrogen production load is established, and the permanent magnet direct drive wind power generation unit is used to supply power to hydrogen production load to achieve the effect of stable output power.
Performance Characteristics of Epoxy Modified Open Graded Friction Course (OGFC) By Post-doping Methods
Authors: Zhang Linyan , Ma Yong , Zhao Yanbin , Li Bo , Li Peifeng , Xie Bin , Feng Jiliang
Published: November 2021

To improve drainage properties and increase driver’s safety in wet weather, epoxy modified Open Graded Friction Course (OGFC) by post-doping methods was proposed. The predominant focus of this paper evaluated the performances of epoxy modified Open Graded Friction Course (OGFC) such as rutting resistance at high-temperature, crack resistance at low temperature, friction, moisture resistance and coefficient of permeability. For comparison, the same NMAS Open friction course with epoxy asphalt which was supplied courtesy of ChemCo Systems Ltd and SK High-Viscosity Asphalt were cited. In addition, the harsh construction requirements and application limitations caused by the residence time of epoxy asphalt were solved by the post-mixing process which was produced by two steps, First step, component B of epoxy asphalt was produced in the backyard plant, then suitable amount of component A was added and mixed evenly while paving in site, affecting the holding time only in the two links of paving and rolling, and the time was easy to control. The results show that epoxy modified Open graded friction Course reinforced with Basalt fiber produced by post-mixing methods has good friction resistance and permeability while retaining satisfactory performance and mechanical properties.
Progress of high temperature polybenzimidazole proton exchange membrane: a systematic review
Authors: Liu Guanghan
Published: November 2021

Proton exchange membrane (PEM) is the core component of proton fuel cell. Generally speaking, ordinary PEM has the poor barrier to fuel (especially liquid fuel) and proton conduction has a strong dependence on water molecules. Compared with ordinary PEM, high temperature fuel cell works in high temperature non-water environment, which overcomes the above problems. Besides, the system is complex with low impurity and much simpler flow field design. Polybenzimidazole (PBI) not only meets the requirements of high temperature, but also has higher proton conductivity than ordinary PEM, i.e., is the best material for high temperature PEM. From this point of view, the properties and fabrication of PBI are systematically reviewed. Specifically, the factors influencing the performance of acid doped PBI high temperature PEM as well as existing problems (high temperature degradation as well as chemical oxidative degradation) are demonstrated. Furthermore, the corresponding solutions and future direction are put forward.
Research Progress of High Temperature Resistant Fracturing Fluid System
Authors: Xu Ke , Lu Yongjun , Chang Jin , Li Yang
Published: November 2021

China has made significant progress in the efficient exploration and development of deep-seated oil and gas wells. Reservoir reformation, as the core tool of high-temperature deep-seated exploration and development, puts forward a strong demand for fracturing fluids. The ultra-high temperature fracturing fluid system developed in my country is mainly divided into two types: ultra-high temperature guar gum fracturing fluid and ultra-high temperature synthetic polyacrylamide fracturing fluid. The high temperature resistant fracturing fluid system is mainly composed of high temperature resistant thickener, high temperature resistant crosslinking agent and temperature stabilizing additives and other additives. Based on indoor research and a large amount of literature, this article summarizes the research and application of high temperature resistant fracturing fluid system, high temperature resistant thickener, high temperature resistant crosslinking agent and temperature stabilizing additives in my country in recent years, and pointed out the shortcomings and limitations of the high-temperature fracturing fluid, the technical direction of the development of high-temperature resistant fracturing fluid technology is proposed.
Study on the preparation and thermal properties of binary mixed chloride salts
Authors: Yan Quanying , Ma Chao , Wang Wei
Published: November 2021

Nitrate phase change materials (PCMs) are the most widely used PCMs in solar thermal power generation technology. The maximum service temperature of Nitrate phase change materials is only 600°C. Therefore, to find a phase change material with large heat capacity, wide temperature range, low heat loss and low price is the focus of current research. According to different mass ratios, nine binary molten salt mixtures were prepared by mixing lithium chloride and sodium chloride. The phase change temperature and latent heat of phase transition of them were studied by differential scanning calorimeter (DSC). The experiment results showed that since the melting point of sodium chloride was high, when the content of sodium chloride in the binary mixture of lithium chloride and sodium chloride was large, a small amount of lithium chloride could not reduce the melting point of the mixture below 600°C, the mixture could not be melted. Meanwhile, when sodium chloride and lithium chloride were melted, the phase transition temperature of lithium chloride and sodium chloride remained at about 540°C and floated at ±15°C. The melting temperature and crystallization temperature of the binary mixture of 90% lithium chloride and 10% sodium chloride were quite different, and the latent heat of phase transformation was relatively high. Therefore, the binary mixed molten salt can be used in the heat transfer and storage technology of solar power generation.
Experimental study of manganese dioxide doped with metal for the treatment of phenolic wastewater
Authors: Qin Qiushi , Huang Ji , Du Xu , Zhang Jinghong , Fu Dong
Published: November 2021

The wastewater containing phenol is harmful, and the process is complicated, photocatalytic oxidation technology is believed to be the greenest and promising strategy for contaminants removal because of the solar energy utilization and no additional oxidants. Herein, manganese dioxide(MnO2) doped with metal was fabricated by a low-temperature hydrothermal method, the specific surface area of MnO2 photocatalyst was significantly enhanced by doping metal ion. This making the photocatalytic performance improved obviously, and further applying for phenol degradation under visible light irradiation at room temperature.
Research on the composition of UV curing modified compounds for 3D printing based on HyperChem simulation
Authors: Bai Weicheng , Tao Mengxiao , Zhang Xianfeng , Dong Jun
Published: November 2021

The precursor conversion method provides the possibility of 3D printing ceramic materials, and the resin system with polysilazane as the precursor is expected to prepare high-performance ceramic materials for aviation. In this paper, the UV curing reaction system of polysilazane for 3D printing is taken as the research object, and hyperchem8.0 software is used as the research means. The model construction, chemical bond energy calculation, reaction enthalpy calculation and other modules in the software are used to simulate and predict the reaction process and mechanism of UV curing, which provides a theoretical basis for the selection and optimization of the subsequent UV curing reaction system for 3D printing.
BiOCl nanomaterials for photocatalytic degradations of nitrogenous organic compound
Authors: Sun Menglin
Published: November 2021

Different BiOCl hierarchical nanostructures with controllable morphologies were synthesized by a facile glycerol-mediated solvothermal method. Every products were subsequently and well crystallized characterized by a range of methods, such as scanning electron microscopy (SEM), X-ray powder diffraction (XRD), high-resolution transmission microscopy (HRTEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED). The photocatalytic properties of the samples were further investigated through photocatalytic decomposition of Methyl Orange (MO) dye. The BiOCl hierarchical nanostructures was as a result of efficient photocatatlytic activity under UV light irradiation, which can degrade MO in a few minutes.
A Covering and protection Type Porthole Die For Semi-Hollow Al-Profiles
Authors: Yun Peng , Fu Haohua , Zhou Chuhao , Deng Rurong
Published: November 2021

A new structure named covering type for the semi-hollow Al-profiles was present. through a common actual case, the determination of structure parameters was introduced in detail. Mainly including the arrangement of portholes, the structure design of chamber and the selection of bearing. The method of checking the die strength was introduced. According to the extrusion results, the structure of the traditional solid die and the covering type structure were compared. The characteristics of the latter structure were simple and easy to process. The practical application shows that the new die structure can enhance the die life, improve the production efficiency and reduce the cost. The high precision and the surface brightness of the profiles were obtained. The structure is worth promoting. The aim is to provide reliable data and reference for the further research and development on the structure for semi-hollow Al-profiles.
A new extrusion die for aluminum profiles
Authors: Huang Xuemei , Luo Yiru , Zhou Chuhao , Deng Rurong
Published: November 2021

A new type of extrusion die is put forward, in which cemented carbide material is used to inlay the working part of the die, so as to improve the wear resistance of the die. The necessity of using cemented carbide in extrusion die is introduced. The selection of cemented carbide was introduced by taking the actual round tube aluminum profile as an example. The method for determining the size of cemented carbide and the mosaic method of cemented carbide were described. Based on the results of extrusion, the common extrusion die and cemented carbide extrusion die were compared. The results show that the wear resistance of the die can be greatly improved by the use of cemented carbide. Thus the life of the die is greatly improved.
Lift and Drag Coefficient Map of NACA4415 Airfoil
Authors: Yin Rui , Huang Jing , He Zhi-Yuan
Published: November 2021

The NACA4415 airfoil was numerically simulated with the help of the Fluent software to analyze its aerodynamic characteristics. Results are acquired as follows: The calculation accuracy of Fluent software is much higher than that of XFOIL software; the calculation result of SSTk-ω(sstkw) turbulence model is closest to the experimental value; within a certain range, the larger the Reynolds number is, the larger the lift coefficient and lift-to-drag ratio of the airfoil will be, and the smaller the drag coefficient will be; when the angle of attack is less than the optimal angle of attack, the Reynolds number has less influence on the lift-to-drag coefficient and the lift-to-drag ratio; as the Reynolds number increases, the optimal angle of attack increases slightly, and the applicable angle of attack range for high lift-to-drag ratios becomes smaller.
Analysis and treatment of insulation abnormality of a 220kV wall bushing end shield
Authors: Hu Yujing , Cao Xianhui , Zhang Gefei , Zuo Penghui , Wan Xun , Wu Tangqing , Xie Yi , Chen Wei
Published: November 2021

This work expounds a case of insulation abnormality of a 220kV wall bushing end shield caused by the failure of rubber seal gasket. The mechanism and causes of insulation abnormality were put forward combined with the method of on-site inspection, XRF analysis, infrared spectroscopy (IR) analysis and thermogravimetric analysis. And suggestions for the improvement of sealing performance to prevent this kind of defect and management of operation and maintenance of bushing end shield were proposed.
Analysis of influencing factors of flow state concrete mixture performance
Authors: Shi Dandan , Qin Xing , Qu Hao
Published: November 2021

Based on the principle of benefiting the durability of concrete, machined sand is used to configure C40 flow concrete, and the engineering application environment and economy are considered. In this paper, the author through the flow state concrete mix ratio design, give the raw material dosage, concrete mixing, finally combined with the workability measurement method, five groups of concrete mix performance testing. According to the test results, the influence of mineral admixture and water reducing agent on the workability of concrete mixture is studied and analyzed, and the reasonable admixture dosage and water reducing rate of water reducing agent and its admixture dosage are finally given.
Research progress of microcapsule self-healing anticorrosive coatings
Authors: Chen Ao , Tong Ling , Wu Lin , Liu Ying , Yang Xiaoyu , Liao Zhiyuan , Zhang Baoguo , Zhou Yilai , Hu Ya
Published: November 2021

During the long-term use of the coating, environmental factors, physical damage or other factors may cause micro-cracks in the coating. The expansion of microcracks will destroy the overall structure of the coating, reduce the protective effect of the coating and degrade its mechanical properties. However, the traditional repair methods need to consume a lot of manpower and material resources, and the micro-cracks in the coating are difficult to be repaired by the traditional external means. Inspired by biological systems, intelligent coatings with certain self-healing ability have attracted wide attention in academia and industry. According to the different remediation agents used in self-healing micro capsules, several common self-healing coating systems of micro capsules were analyzed, including corrosion inhibitor system, capsule drying oil system, capsule reactive repair agent system, etc.
Study on Structure Type and Operation Condition of UHVDC Wall Bushing
Authors: Zhang Shiling , Gong Lin , Deng Baojia
Published: November 2021

When the ±800kV UHVDC capacity is increased to 10000MW, the transmission current is 5kA and 6.25kA, which will put forward new requirements for the key technology of UHVDC through wall bushing: in UHV level, the key of through wall bushing lies in the research of basic technology of voltage sharing and field sharing. In the case of large current carrying capacity, the key lies in the basic technology research of current sharing and heat sharing. When the DC wall bushing, converter bushing and outgoing line device operate at the rated voltage, the central conductor is heated due to the carrying large DC current. Therefore, the temperature field distribution inside and at the tail of the bushing core is uneven, and the resistivity is the function of temperature, resulting in the change of resistivity with temperature and the change of potential and electric field distribution with resistivity during operation. Therefore, under the above high current operation conditions, in-depth key technology research is required for the design of bushing current carrying device, calculation of internal potential and electric field distribution, voltage sharing, field sharing, current sharing and heat sharing technology. The combined action of electrical and thermal stress will significantly affect the internal electric field distribution of converter transformer core and accelerate the aging rate of core composite insulation material, which introduces new research topic for the key technology of UHVDC converter bushing. The electric field and voltage distribution of UHVDC bushing are theoretically analyzed, the insulation structure is optimized from the aspects of material and structure, and the manufacturing process and the test technology are deeply and systematically studied.
Numerical modeling of cracking behavior in Cr coating for ATF cladding under three-point bending
Authors: Yuan Mingduo , Pan Ziyan , Zou Zhenyu , Zhang Weijian , Du Mingyue , Jiang Jishen , Ma Xianfeng
Published: November 2021

In-situ three-point bending tests and finite element modeling based on the cohesive zone model were developed to study the stress evolution and cracking behavior of the Cr coated Zr-4 alloy for accident tolerant fuel claddings. The initiation and propagation of micro-cracks were captured by in-situ observation and predicted by the numerical simulation. The results showed that vertical cracks first initiated from the coating surface and propagated to the Cr/Zr4 interface. Under larger bending strain, interfacial cracks began to initiate from the vertical crack tips driven by large local stress concentration.