bluuebunny/crossref_metadata_2025 huggingface dataset:
Using semantic field model to create information search engines
Authors: Sachkov V E , Zhukov D O , Andrianova E G
Published: February 2021

In the web infrastructure of information search, the use of semantic methods is considered to be a new round of the technology development. With the emergence of big data, a relevant issue is processing large amounts of data to extract valuable knowledge, especially for text files in natural language. Practice shows that traditional natural language search engines cannot always extract the necessary data from such data sets, as they do not take into account several subtle aspects of the language used in human speech. To solve this problem, the possibilities of using semantic search engines for text processing are being explored. This paper discusses the possible use of the semantic field model developed by the authors, to create a semantic search engine. Experiments have shown that using this model can improve the search accuracy. This model can be additionally used in creation of interactive dialogue systems.
Influence of rainfall dynamics uncertainty on sensitivity analyses results in hydrodynamic models of large urbanised catchments
Authors: Majewska M , Wałek G , Ciupa T , Musz-Pomorska A , Widomski M K
Published: February 2021

This paper presents an analysis method of rainfall uncertainty influence on the variability of modelled runoff from a municipal catchment. The model of 41.75 km2 basin prepared in SWMM 5.0 software was used in this study. The developed model consisted of 120 sub-catchments of area 5-100 ha and terrain slope 0.2 – 6%. The share of the impervious surface area of sub-catchments was in the range of 1 – 80%. The model was preliminary calibrated basing on measurement data for six rainfall-runoff events at four measuring cross-sections. To allow assessment of time-related rainfall intensity variability influence on maximal flow values registered at measuring cross-sections, the length of time step was changed by a division of registered data values on 30 minutes periods. The uncertainty parameterisation was performed for analysed rainfall events (resolution 30 minutes) by introduction the subsequent values of θ = {0.3; 0.4; 0.5; 0.6; 0.7}. Thus, it was assumed that for θ = 0.3, 30% of hourly rainfall dropped during the first 30 minutes, the remaining 70% during the next time step, etc. For the assumed θ = 0.3 – 0.7 values influence calculations of calibrated parameters variability (retention depth of impervious, impervious surfaces, the roughness of impervious surfaces, retention depth of pervious surfaces, and roughness of pervious surfaces) on modelled values of maximal flows at measuring cross-sections were performed. In order to supplement the analysis, the influence of impervious terrains spatial variability at measuring cross-sections on determined dynamics of maximal flows concerning SWMM 5.0 calibrated parameter values was assessed.
Structural factors influence on strength properties of S235JR steel welded joints
Authors: Miturska I , Rudawska A
Published: February 2021

The paper presents the results of strength tests of welded joints of S235JR structural steel. Welded joints of various geometries were made: butt joints, overlap joints with a single weld, overlap joints with double welds, overlap joints with spot welds, overlap joints with hole welds, and double-flanged seam. The strength tests carried out made it possible to determine the destructive force. Eight joints of each type were made. Based on the results obtained, a statistical analysis was carried out to determine the influence of structural factors on the strength of welded joints and to assess the repeatability of the process of making joints of a given type. This analysis allows verifying which of the tested geometries of welded joints are the most strength and stability, which is especially important when designing new structures or planning renovation of existing structures. The analysis showed that the highest strength as well as the highest repeatability was obtained in the case of overlapped joints with double welds – destructive force at 37 367 MPa. The lowest strength was characterised by double-flanged seam – destructive force 8 603 MPa.
Neural modelling of solar radiation variability
Authors: Ronkiewicz T , Aleksiejuk-Gawron J , Awtoniuk M , Kurek J
Published: February 2021

Artificial neural networks are increasingly used in engineering and technical sciences, especially to solve problems under process uncertainty. The mathematical model presented in this article describes cloud variability. The application of the model can increase the efficiency of solar systems because the response time of the solar panel to changing weather conditions is crucial. The model involves an artificial neural network that serves to determine the degree of daily cloud coverage based on three data – the month, daily solar radiation sum and total harmonic distortion factor (THD). The THD factor is determined for daily solar radiation courses using a Fast Fourier Transform. Approaching the daily variability of solar radiation as a sine wave allows employing the THD factor in an unconventional and innovative way. The modelling data have been derived from the measurements of the meteorological station of the Institute of Mechanical Engineering of the Warsaw University of Life Sciences. MATLAB Software (2019a) was used for data processing and network modelling. The model is verified using the mean square error. The performed analysis provides promising results and conclusions.
Numerical modelling of forming load on pre-stressed dies
Authors: Bulzak T , Wójcik Ł , Szala M
Published: February 2021

The article presents a method of numerical modelling of the load on pre-stressed dies. Numerical modelling was performed in two stages. In the first stage, a simulation of the process of extruding with stiff tools was performed. In the second stage, load on the tools obtained in the first stage was implemented and strength tests of the dies were performed. Four construction variants of the tools made of steel and sintered carbide were analysed. In the first set of tools, a monolithic die with a container was used. In the second set, a die and a divided container were applied. In the third set, a die and a container stressed with a singular ring were used. In the last set, a die with a container stressed with two rings was analysed. As a result, distributions of reduced, radial, tangential, and axial stresses were presented for various construction variants. Die and container made of sintered carbide stressed with two rings ensure the necessary strength of tools and correct progression of the process.
The crack surface morphology investigation of S355J2 steel after bending-torsion fatigue
Authors: Macek W , Marciniak Z , Branco R , Szala M , Rehmus-Forc A
Published: February 2021

The paper describes the analysis of crack surface morphology of S355J2 steel specimens after bending-torsion fatigue. These experimental investigations of the surface topography were carried out using the focus variation microscope, an optical 3D measurement device. Selected results of measured fracture surfaces for S355J2 steel were analysed according to the surface texture ISO 25178 standard. Differences in roughness values for different loadings were demonstrated. For profile Rx and areal Sx parameters, characteristic relationships of fracture zones have been demonstrated. It has been shown that roughness profile Ra for the rupture area is higher than for the propagation area, as well as increases after both the LCF and HCF tests and increases with the torsional loading level. However, Sa in the propagation area increases and the rupture area decreases.
Strength analysis of the conceptual model of a main rotor blade spar with actuators
Authors: Siadkowska K , Borowiec P
Published: February 2021

This paper concerns the conceptual design of a main rotor blade spar with actuators. A three-dimensional model of a main rotor blade is based on the preliminary geometric blade setting angle to increase the aerodynamic performance caused by different linear velocities of individual cross-sections. A modification of the blade setting angle results in a change of the angle of attack and influences the value of the lifting force in a given blade cross-section. The geometric setting angle was applied in designing both the main rotor blade spars and the blade. The overall dimensions of the blade depended on the available surface of the outmost blade airfoils. The important element of the designed spars was a cut in the form of a notch enabling the upper and lower crossbars of the designed spar to move during the operation of actuators. The FEM analysis was carried out on the parts of the designed blade spars. Three types of materials were compared in the finite element analysis. The internal stresses and displacements of the outmost edges of the crossbars were analyzed. The Catia V5 software was used for the designing work. The sections of the spars were analyzed using the Finite Element Method. The Pre/Post module of NX 12 was used for the FEM analysis. The displacement results were analyzed, which allowed us to determine their twist angle.
Application of chitosan for the removal of heavy metals from drilling fluids wastewaters
Authors: Wasag H , Kujawska J
Published: February 2021

The purpose of this study was to present a possibility of application of chitosan, covalently cross-linked by treating with glutaraldehyde as an effective sorbent of heavy metals ions from drilling wastewaters. The influence of the concentration and pH on the sorption capacity of the modified chitosan was determined in relation to Cr(II), Zn(II), Pb(II) and Cd(II) ions. Sorption parameters were defined. The greatest affinity to the modified chitosan was observed from ions of Zn(II), Pb(II). The effectiveness of the studied process is pH-depended. Processes of sorption of Cr(II), Zn(II), Pb(II) and Cd(II) ions in the presence of cross-linked with glutaraldehyde chitosan are well-described by Langmuir and Freundlich isotherms, which may be confirmed by high values of correlation coefficients (R>0.91). High values of the maximal sorption capacity (q0) have been reached for zinc ions (q0=3.67 mg/g) and lead ions (q0=3.31 mg/g), calculated on the basis of Langmuir isotherm equation which proves their great affinity to chitosan cross-linked with glutaraldehyde. Obtained results confirm good sorption properties of cross-linked chitosan towards heavy metals and a possibility of application of this sorbent in a wide range of the pH. Even small doses of sorbent, such as 5 g/L, facilitate the effective reduction of Cd, Cr, Pb, Zn content in drilling wastewaters, even from 75 to 90 %. Application of chitosan may be one of alternative and all the same effective methods leading to reduction of the inconvenience of fluid drilling waste.
Numerical analysis of porous materials subjected to oblique crushing force
Authors: Rogala M , Gajewski J
Published: February 2021

This article presents an analysis of porous materials subjected to oblique loading. The analysis was carried out with the Abaqus software using the finite element method. The material model used for numerical analysis was Crushable Foam. The subject of the study involved solid elements located on a base with a variable angle of inclination. The values of the base angle were 15, 30, 45, 60 degrees. All samples were loaded with the same boundary conditions. During the test, the normal and shear forces were determined. The crushing efficiency indicators were calculated from the measured forces. The aim of the tests was to define the distribution of forces in the foam element.
Effect of cut-out radius for behaviour of symmetrically laminated plates
Authors: Falkowicz K
Published: February 2021

The buckling and post-buckling behaviour analysis of thin-walled composite plate under an axial compressive force is hereby presented. The plate with central cut-out is made of a carbon-epoxy composite - a laminate consisting of eight symmetrically oriented plies. This paper addresses the influence of the cut-out radius on the buckling behaviour of laminated composite plates and stress concentration. To develop a discrete model and to perform numerical calculations the commercial ABAQUS program was used.
Dynamics of a nonlinear energy harvester with subharmonic responses
Authors: Litak G , Ambrożkiewicz B , Wolszczak P
Published: February 2021

A frequency transmission band of the nonlinear energy harvester shall be studied numerically. For the analysis, the nonlinear piezoelectric energy harvesting system based on a cantilever elastic beam has been applied to harvest the kinetic energy of the moving frame. We used a double-well potential induced by permanent magnets for a ferromagnetic beam resonator. A piezoelectric patch attached along the beam was used as a transducer of the mechanical into electrical energy. It occurred that the system could work in a wide interval of frequency beyond the linear resonance. Besides the response with a period of excitation, solutions with dominating sub-harmonics of the harmonic inertial force excitation have been found. Particular solutions were illustrated, classified, and discussed using phase portraits and Fourier spectra of the output signals.
Matrix profile implementation perspective in Industrial Internet of Things production maintenance application
Authors: Pizoń J , Kulisz M , Lipski J
Published: February 2021

The matrix profile processing is considered for the implementation of production maintenance tasks in the context of data acquisition by industrial Internet of Things solutions. The prospective implementation of the matrix profile data structure is verified through a dedicated case study, presenting the method of processing non-labelled data registered by sensors. The case study demonstrates the functionality of the profile and indicates the prospects of their applications in the field of production maintenance.
Alternative numerical solution of transient flow in viscoelastic pipes
Authors: Urbanowicz K , Bergant A , Duan HF , Karadzić U , Sobków D
Published: February 2021

A new numerical solution of transient flow simulations in viscoelastic pipes is presented, examined, and compared with traditional solutions and experimental results. Here the viscoelastic behaviour of the pipe wall is modelled explicitly and the wall shear stress implicitly. The new solution will be able to facilitate a better understanding of the unsteady flow behaviour in a plastic pipe in water supply systems. It will also contribute to lowering the computational costs of such systems and improving the accuracy of viscoelastic pipe diagnosis such as leak detection in the future.
Numerical investigation of the cavitating flow for constant water hammer number
Authors: Urbanowicz K , Bergant A , Karadžić U , Jing H , Kodura A
Published: February 2021

Several comparative studies in this work were carried out with the help of the method of characteristics. This numerical method is the most effective for solving a system of partial equations (hyperbolic type) describing a complex problem associated with the water hammer phenomenon. The numerical tests have been performed for the selected constant value of the introduced dimensionless water hammer number. The presented comparisons showed that the unsteady flows without column separation are analogous in various hydraulic systems when the value of this number has been preserved. Besides, cavitating flows with such a constant value of this number were also tested. These studies indicated the existence of another dimensionless number which was called a cavitation number. Maintaining the fixed values of both dimensionless numbers guaranteed similarity of flows in different examined systems in which cavitation occurred.
Comparison of the use of species abundance and presence-absence data for diversity assessment
Authors: Kirichenko-Babko M B , Danko Y M , Danylkiv J M , Majerek D
Published: February 2021

The article is devoted to the analysis of empirical data on the distribution of ground beetles in three model sites located in Lublin (Poland). Using Principal Coordinates Analysis (PCoA) and hierarchical cluster analysis, we compared the results of the studies based on the data of species × abundance and binary data (species × presence / absence). It was shown that the hierarchical clustering method and PCoA based on binary data demonstrate the individuality of the studied territories, although they have some common species. While the results of the analysis, based on abundances, did not show a clear separation of the stations within the three studied locations, the similarity between the studied territories is more objectively reflected from a biological point of view.
Influence of diversified anthropogenic pressure on heavy metals contents in soils and plants of garden allotments
Authors: Żukowska G , Chomczyńska M , Myszura M
Published: February 2021

The presented research aimed at assessing the impact of anthropogenic pressure of varying intensity on the heavy metals content in the soils of garden allotments and in the biomass of plants grown there. In order to achieve the study purpose, the contents of Pb, Zn, Cu, Cd were determined in the soil samples of three allotments located in Silesia (strong industrial and urban pressure), Lublin (moderate industrial and urban pressure) and Biała Podlaska (weak urban pressure). The same elements were analysed in leaves and roots of red beets grown on the soils in urban areas mentioned above. It was found that the soils derived from Silesia were the most polluted, less polluted were the soils from Lublin, and the least polluted were the soils from Biała Podlaska. The content of Pb, Cu, and Cd in the leaves and roots of red beet harvested on the examined soils was dependent on the concentrations of these elements in soils. The obtained results indicated that the contamination of soils and plants with heavy metals should be included into the comprehensive assessment of the human impact on the environment, especially in industrial and urbanised areas, and suggested the need for further, widely spread studies of soils in such areas.
Strength analysis of the drive wheel hub of a hydrogen-powered prototype hyper-light vehicle
Authors: Gilewski M , Czarnigowski J , Górski W , Mitrus K , Różyło P , Trocha S , Wypychowski M
Published: February 2021

This article presents a strength analysis of the rear wheel hub of the prototype vehicle for the Shell Eco-Marathon competition. Due to only one wheel in the vehicle’s driving axle, all drive components and the wheel are subjected to higher loads. Therefore, the rear hub must withstand the loads generated by the rear part of the vehicle and the powertrain. The aim of the paper was to develop a hub with the minimum possible weight while fulfilling the strength conditions. The low weight of the hub is particularly important because of the efforts to achieve the highest possible efficiency of the drive system, which generates less energy loss and the ability to travel a longer distance on the same amount of fuel. The article presents the developed three-dimensional model of the hub. The suitable materials for the individual elements that are parts of the whole hub were selected. The three-dimensional model was tested to strength analysis using the finite element method with the use of Abaqus® software. The developed calculation mesh as well as the assumptions and boundary conditions of the modelling carried out are presented. The results of the simulation tests, which are the basis for further design work are also described.
Modification of carbon sorbents by ozonation
Authors: Mikhaylova E S , Fedorova N I , Ismagilov Z R
Published: February 2021

The paper presents the results of a study of changes in the textural and physicochemical properties of the carbon sorbent surface after oxidative modification with an ozone-oxygen mixture. For the study, we used a carbon sorbent sample obtained on the basis of long-flame coal. It is shown that oxidative modification with the mixture leads to an increase in the surface area of the studied sorbent, mainly due to the growth of micro-and mesopores. In this case, according to IR spectroscopy data, an increase in the content of oxygen-containing groups on its surface is observed.
Development of catalysts for the hydrogenation of levulinic acid to gamma-valerolactone in the framework of the problem of cellulose conversion into valuable chemicals
Authors: Okhlopkova L B , Ismagilov Z R
Published: February 2021

Gamma-valerolactone (GVL) is a starting reagent for the production of fuels and fine chemicals. GVL can be used as a solvent, as part of an electrolyte, for the production of chemicals and fuel additives. It can be converted to liquid fuels such as valerian biofuels, liquid alkanes or valuable chemical intermediates such as 1,4-pentanediol or alkylpentenoates being biopolymer precursors. The production of GVL is based mainly on the hydrogenation of levulinic acid (LA), which can be obtained directly from cellulose by acid hydrolysis. This article describes the development of heterogeneous catalysts for the targeted conversion of LA to GVL. In order to analyze both achievements and unresolved problems in this area the emphasis was placed on the discussion of systems based on noble and non-noble metal catalysts, hydrogenation by means of hydrogen transfer.
Transmission electron microscopy for evaluating the structural parameters of nanoparticles
Authors: Zakharov N S , Popova A N , Zakharov Yu A , Pugachev V M , Russakov D M
Published: February 2021

In this work, on the example of bimetallic systems FePt and FePd, an approach is developed to assessing the structural parameters of nanoscale mono-and polymetallic systems by transmission electron microscopy (TEM), in comparison with the X-ray diffraction method of analysis. The interplanar distances, average sizes and phase compositions of FePt and FePd nanosystems are calculated.
Synthesis of nanostructured FePt systems
Authors: Zakharov N S , Popova A N , Zakharov Yu A , Pugachev V M
Published: February 2021

The paper compares some characteristics of nanoparticles of the FePt system obtained by the method of joint reduction of solutions of metal precursors using different reducing agents: an alkaline solution of hydrazine hydrate and sodium tetrahydroborate. The method of transmission electron microscopy is used to analyze the shape and morphology of the obtained nanosized particles, according to the data obtained by the methods of X-ray diffraction, phase analysis is carried out and the main X-ray structural parameters are evaluated. Thermal analysis in combination with mass spectrometry is used to characterize the state and purity of the surface of nanoparticles. It is shown in the work that nanoscale FePt systems obtained using the reductants selected in the work have similar physicochemical characteristics.
Study of coke by X-ray structural analysis and scanning electron microscopy
Authors: Ismagilov Z R , Popova A N , Sozinov S A
Published: February 2021

In this work, a number of industrial samples of needle cokes from various manufacturers were studied. The study of the samples was carried out by methods of X-ray diffractometry and analytical scanning electron microscopy. The parameters of their crystal structure were determined, and the features of their microstructure were investigated. The differences found in the crystal structure and morphology of coke particles made it possible to divide the studied samples into 2 groups: isotropic, with equal longitudinal and transverse crystallite sizes, and anisotropic, in which the longitudinal crystallite sizes exceed the transverse ones by 3-4 times. Particles of isotropic cokes have a fracture texture characteristic of a glassy amorphous body, in contrast to which particles of anisotropic cokes have a lamellar texture. The consistency of the conclusions obtained from the results of two independent methods makes it possible to consider X-ray diffraction analysis in combination with analytical electron microscopy as the necessary complementary tools for evaluating cokes with the aim of their possible application in various technological processes.
Glow of a coal flame during exposure to microsecond laser pulses with different energy densities
Authors: Kraft Ya.V. , Aduev B. P. , Nurmukhametov D.R. , Ismagilov Z. R.
Published: February 2021

The kinetic characteristics of the glow of coal during exposure to microsecond laser pulses have been investigated. It is shown that the glow intensity increases from the moment of exposure to the laser pulse, the maximum glow intensity falls on ∼ 110-120 µs• i.e. at the end of the laser pulse. In the submillisecond range, a decrease in the glow intensity is observed. The glow intensity of coals increases linearly with an increase in the energy density of the laser radiation.
Study Of Fossil Coals In The Kuznetsk Basin By Epr Spectroscopy
Authors: Nelyubina N V , Nikitin A P , Valnyukova A S , Ismagilov Z R
Published: February 2021

Fossil coals of the Kuznetsk Basin of varying degrees of metamorphism were studied by the method of electron paramagnetic resonance. It is shown that in the series from brown coal to anthracite, the g-factor of the EPR signal decreases, due to the aromatization of the carbon framework and a decrease in oxygen-containing and hydrogen-containing fragments in the coals. The maximum width of the EPR spectrum is observed for coals of the middle stage of metamorphism, which indicates the presence of both aliphatic and aromatic paramagnetic centers (PCs) in their structure. Also, in the series of coal metamorphism, the concentration of PCs increases. Thus, it has been shown that in the process of coal metamorphism, a change in the electronic structure occurs, associated with the rearrangement of the carbon skeleton of the organic mass of coal (OMC) and a decrease in the amount of oxygen-containing and hydrogen-containing radicals.
Adsorption method for determining the texture characteristics of Kuzbass fossil coals of the metamorphism series
Authors: Dudnikova Y N , Zykov I Yu , Fedorova N I , Ismagilov Z R
Published: February 2021

The presented work is devoted to the study and development of a technique for measuring the parameters of the porous structure of fossil coals in Kuzbass by the adsorption method on an ASAP 2020 analyzer “Micromeritics”. The conditions for sample preparation of samples were selected, which make it possible to record reproducible isotherms of low-temperature adsorption-desorption of nitrogen (77K) by the studied samples of fossil coal of various grades. The obtained isotherms of low-temperature adsorption-desorption of nitrogen were used to determine the textural characteristics of Kuzbass fossil coals by various methods (the specific pore surface area was calculated using the Brunauer-Emmett-Taylor (BET) method; the volume of micropores was determined using the comparative t-Plot method; the mesopore volume was determined using the method of Barrett-Joiner-Halenda (BJH). The obtained values of the textural characteristics of Kuzbass coals of the metamorphism series make it possible to reveal their macro-and microstructural features, to obtain information on the adsorption properties of coal, and can also be used to optimize coal use processes, such as the extraction of methane from coal seams, gasification, combustion, liquefaction, beneficiation, production of metallurgical coke.
Study of the textural characteristics of carbon sorbents prepared by alkaline activation
Authors: Zykov I Yu , Dudnikova Y N , Tsvetkov V E , Fedorova N I , Ismagilov Z R
Published: February 2021

The paper investigates the textural characteristics of carbon sorbents prepared by alkaline activation of brown coal from the Tisul deposit. The texture characteristics (specific surface area-SBET, m2/g, total pore volume-VΣ, cm3/g, mesopore volume-Vme, cm3/g and volume of micropores-Vmi, cm3/g) of carbon sorbents were measured on an ASAP-2020 analyzer. The production of carbon sorbents was carried out by activating coal impregnated with potassium hydroxide at a KOH/coal (RKOH) ratio of 0.5 g/g; 1 g/g and 2 g/g. The activation of brown coal was carried out at three different temperatures-700 °C, 750 °C and 800 °C. It is shown that the RKOH ratio has a greater effect on the texture characteristics of carbon sorbents, as compared to the effect of the alkaline activation temperature. Alkaline activation at an RKOH ratio of 2 g/g makes it possible to obtain carbon sorbents with the highest values of textural characteristics. High-temperature alkaline activation (800 °C) has a positive effect on the formation of a common pore space of carbon sorbents based on brown coal from the Tisulsky deposit for all studied RKOH.
Methods and approaches to the determination of the carbon-containing dust concentrations in the atmospheric air during coal mining and processing
Authors: Zhuravleva N.V. , Zhuravleva E.V. , Mikhailova E.S. , Ismagilov Z.R.
Published: February 2021

An overview of russian and foreign methods and approaches to control carbon-containing dust in the atmospheric air in the influence zone of coal mining and processing enterprises is presented in this paper. The main composition of suspended substances (coal dust), entering in the atmosphere in the processes of coal mining and processing, consists of an inorganic part, represented by the main rock-forming oxides, toxic elements, mineral particles PM2,5 and PM10, also organic substances, which include soot(carbon), organic matter of coal, benz(a)pyrene and other PAHs. The capabilities of modern physical and chemical analysis methods, which significantly increase the accuracy, reliability and information content of monitoring the state of atmospheric air, are still poorly used in industrial environmental control. Information about the composition and properties of coal dust obtained from research of Kuzbass coals, its mining and processing waste should be used in the development of industrial environmental monitoring programs by industry enterprises.
The development of ecologically clean technology for coal use in terms of the coal-water slurry usage
Authors: Korotkiy I A , Neverov E N , Murko V I , Chernikova O P
Published: February 2021

The baseline conditions of technology for producing and burning coal-water slurries in Russia and foreign countries is exposed. The technological and economic efficiency of using this technology for the coal processing and cleaning waste disposal is shown at experimental and industrial facilities. The feasibility studies of the technology usage at large Kuzbass thermal power plants are presented. The possibility of solving a serious environmental problem of reducing the storage of the most coal washing toxic waste volume in the areas where coal processing plants and coal mining enterprises are located is demonstrated. It is shown that on the basis of these wastes, it is possible to prepare a suspension coal-water fuel with a solid phase content of 56-59%, with the required structural and rheological characteristics and a lower calorific value of up to 13 MJ/kg. The boiler with a thermal capacity of 0.58 MW with an eddy combustion system, which effectively operates on coal-processing waste fuel is designed, manufactured and tested. The results of the boiler operation on the specified fuel showed its high efficiency (efficiency is 83-85%) with the level of harmful emissions in the flue gases significantly lower than the permissible values.
Assessment of Long-Range Guided-Wave Active Testing of Storage Tanks
Authors: Cailly William , Walaszek Henri , Brzuchacz Sebastien , Zhang Fan , Lasaygues Philippe
Published: February 2021

Guided Wave Testing (GWT) is now increasingly being used for the non-destructive testing of large structures. Petrochemical tank bottoms are particularly subject to corrosion. Today, the monitoring of corrosion in storage tanks is probably one of the most challenging applications of GWT because of the size and the complexity of such medium. This article deals with the main physical issues of this application, in particular, the prediction of the elastic field propagating in the tank wall and bottom, and the prediction of guided wave scattering by joints. Drawing on current research work, a representative numerical configuration is defined. The global diffusive effect and the local diffraction effect of the lap joints are studied. The methodology have led us to focus on the low ultrasound frequency range: from 10 to 50 kHz. A quantitative evaluation of the scattering by lap joint is carried out by means of simulations and experiments on elementary reduced scale joints. Dynamic range computations make it possible to get prior knowledge about the minimum signal-to-noise ratio (SNR) required to get information about the tank bottom, for a given configuration, leading to a SNR-resolution trade-off. The method can be extended to larger tanks. The results confirm that the use of GWT technology for long-range active testing and imaging of storage tanks is promising.
Preparation of laser markable polyamide compounds
Authors: Li W H
Published: February 2021

Laser marking technique has been increasingly used in electrical and electronic industry in the recent decades for scanning and control purpose. Laser marking is superior to the traditional labelling techniques in terms of speed, flexibility and duration. The mechanism of laser marking is either blackening by carbonization or brightening by microbubbles, upon the effect of laser on the base. Normally laser marking additives were introduced in order to achieve the controllable marking effect. In this paper, a light-on-dark laser markable polyamide compound was studied with the leveraged properties of mechanical, physical and laser marking effect.
Biodegradable wet-spun fibers modified with antimicrobial agents for potential applications in biomedical engineering
Authors: Felgueiras H P , Homem N C , Teixeira M A , Ribeiro A R M , Teixeira M O , Antunes J C , Amorim M T P
Published: February 2021

Wet-spinning is a non-solvent induced phase inversion technique that allows the production of continuous polymeric microfibers, with a uniform morphology, based on the principle of precipitation. It allows the production of 3D fibrous constructs with an intricated architecture that facilitates cell infiltration, something that is very limited in electrospun nanofibrous mats, thus increasing its interest in biomedicine. Wet-spun scaffolds are also more easily processed and can be loaded with a variety of biomolecules of interest. Antimicrobial agents that display a broad spectrum of activity against bacteria, fungi and viruses have been combined with such constructs demonstrating great potential to fight infections. In the present work, we explore the use of wet-spinning to process both natural and synthetic biodegradable polymers in the form of microfibers, and the necessary processes to modify their surface to increase their antimicrobial profile. The synergistic potential of specialized biomolecules within wet-spun fibrous architectures are also highlighted.
A novel catalyst prepared from black liquor for biodiesel conversion: An optimization study
Authors: Sun Y , Liu J Z , He H Z , Wang Y X , Yang G , Liu Y Y , He J , Xiao X
Published: February 2021

This paper reports a new approach for high-value conversion of black liquor into biochar to catalyse the transesterification for biodiesel conversion using waste fry oil (WFO). The central composite design (CCD) and response surface methodology (RSM) were employed to optimize the biodiesel preparation using the catalyst prepared from the paper pulp black liquor precipitated biochar. The transesterification reaction is catalysed by oxidative functional groups (enolic) on the surface of biochar. The effect of alkaline loading in biochar, carbonization temperature, the methanol to oil ratio and the catalyst loading were systematically investigated. The optimal biodiesel conversion conditions were achieved as the following: 27wt% (alkaline loading in biochar), 585 °C (carbonization temperature), 7 (methanol to oil ratio) and 5.5 wt% (catalyst loading), with the biodiesel yield of 95%.
Preliminary screening of dominant epitopes of truncated p72 protein of African swine fever virus
Authors: Wang J L , Dong L , Meng W Q , Zhang C L , Chen J L , Jia J , Shen Z Q
Published: February 2021

African swine fever (ASF) causes huge economic losses in the absence of vaccines with protective efficacy. Diagnostic tools are critical for the early detection, prevention, and control of African swine fever virus (ASFV). The protein p72 is a good serological target for conducting ASF detection and surveillance. This study aimed to adopt a multiparameter analytic method to predict the dominant epitopes for p72 protein of ASFV based on a comprehensive analysis of the secondary structure, hydrophilicity, surface accessibility, and effects of the index of proteins using the software. The results showed that the area of the dominant epitope of protein p72 contained the N-terminal residues aa137–286. This study laid the foundation for developing vaccines and immunodiagnostic techniques.
Comparison of damage mechanism of polyimide films in space radiation environments
Authors: Shen Z C , Ding Y G , Wang Y Z , He H B
Published: February 2021

Thin polyimide (PI) film are widely used as structure material or functional material of spacecraft, but their microstructure and properties may be damaged by space radiation environments such as electron, proton, and ultraviolet and so on By using space combined radiation simulation facility and X ray photoelectron spectroscopy (XPS), the damage mechanism of PI film in different irradiation environments were studied. Both charged particles and ultraviolet photons cause the breakage and cross linking of molecular bonds of PI films. Among them, the charged particles mainly show that the PI film breaks the molecular valence bond, while the ultraviolet photon mainly shows the cross linking of the molecular valence bond. For charged particles, the breakage of PMDA molecular chain, especially the break of C = O double bond and -N (CO) bond is the main effect, and at the same time, C-O is generated. For UV irradiation, the breakage of C = O bond, C-O bond, C-N bond and C-C bond mainly occurred firstly, and then the cross-linking between ions of C, N, O with the benzene ring and between different benzene rings will appears with the UV irradiation.
Features of amplitude frequency characteristics of ABS plastic 3D printed metamaterial sample
Authors: Shirgina N V , Kokshayskiy A I , Volodarsky A B , Odina N I , Korobov A I
Published: February 2021

In this study, we investigated the acoustical properties of custom-designed phononic crystal-like acoustic metamaterials 3D printed from ABS plastic. The elastic properties of these metamaterials were studied experimentally and numerically. The metamaterial consisted of a set of plane parallel lattices the number of which could vary in different samples. Each lattice in the sample consisted of 16 parallel square rods. The amplitude-frequency characteristics (AFC) of the fabricated metamaterial sample were measured in the frequency range (35-100) kHz using longitudinal acoustic waves both in air and water. The propagation velocities of longitudinal and shear acoustic waves of ABS plastic itself were measured prior to the experiment. The band gaps (stop bands) were detected and investigated while measuring AFC of the metamaterials. We have found that the increase in the number of lattice layers in the sample led to the band gap acoustic wave attenuation coefficient increase along with the band gap narrowing, while the central frequency of the band gap remained the same. The numerical simulation of the sample frequency response was carried out in COMSOL. The results of experimental studies and numerical simulations were in satisfactory agreement. We have also investigated the ultrasound scattering diffraction pattern of the sample. The obtained results can be used in solid-state physics and material science, to create materials with controlled frequency-dependent acoustic properties.
Study on the allocation of congestion revenue under doubletrack pricing system
Authors: Zhang Maolin , Xing Yuhui , Wang Bangcan , Chen Qinggui , Liu Xiangrui , Mu Chunfeng , Li Wenxuan
Published: February 2021

The introduction of nodal spot market has brought unneglectable problem of congestion revenue allocation in China. Meanwhile, the coexistence of market and regulation in nowadays power market in China added specialty when it comes to appropriately allocate congestion revenue in China. Based on thorough review and analysis on both the principle of congestion revenue allocation as well as the status quo of a typical provincial market in China, this paper attempts to tackle this problem with consideration on property right, with which the contribution to the grid network of electricity users are taken into account. The solution is established in two stages, which is based on the reality that the distribution of two types of users in each node remains currently unknown.
Research on Mirror Coupling Process in Array Semiconductor Laser
Authors: Zhu Ma , Guodong Wu , Da Gong , Qiuyue Jiang , Xiang Sun
Published: February 2021

In order to improve the coupling efficiency of the array semiconductor laser and the multimode fiber, this paper establishes an ideal coupling model for the general structure of the array semiconductor laser. Combined with experiments and Zemax simulation, the relationship between the size error of the mirror package and the coupling efficiency is studied. The results show that : in the displacement error, the coupling efficiency is most sensitive to the X-axis displacement; in the angle error, the coupling efficiency is more sensitive to the Y-axis rotation angle than the Z-axis rotation angle error; the coupling efficiency curve has obvious peaks and is sensitive to changes, and the tolerance is small, which puts forward higher requirements on the stability of the coupling device.
Influence of coupling characteristics on commutation failure of new hybrid HVDC transmission system
Authors: Liu Jiaqi , Chen Zhengguang , Wang Xingguo
Published: February 2021

Hybrid cascaded multi-terminal DC transmission provides a more flexible transmission method, improves the voltage stability of the inverter AC system, and reduces the probability of commutation failure. The hybrid LCC-VSC at the receiving end of the DC system is a new type of topology.In order to study the influence of coupling characteristics between VSC and LCC on commutation failure in AC power grid at receiving end,firstly,a hybrid LCC-VSC simulation model is built on PSCAD to analyze the operation characteristics of the system during the fault and verify the reactive power support ability of VSC to LCC, and the improvement effect of VSC on LCC-HVDC under different reactive power control modes is compared and analyzed. In order to study the influence of AC/DC coupling on commutation failure of LCC, commutation failure immune factor (CFII) was introduced to study the influence of AC system strength on commutation failure of LCC. Finally, considering that the influence of AC/DC coupling on commutation failure is closely related to the degree of coupling, the electrical distance between LCC and VSC is further studied. The results show that the conclusion can provide theoretical guidance for the design and analysis of related projects.
A Comprehensive Method of Recovering Electricity Stealing Based on Data Mining
Authors: Tingchao Jin , Jianbo Wang , Shuya Cheng , Hui Cai , Yue Xie , Ying Wang
Published: February 2021

Aiming at the current situation that the current methods of recovering the stolen electricity often use manual analysis and estimation, which leads to unsatisfactory results, this paper proposes a comprehensive electricity recovery method based on data mining. First of all, it is determined for the stealing time and other relevant data. Then, for users who can calculate the correction coefficients, the correction coefficient method is used to analyze the electricity theft electricity, and the users who meet the requirements of the prediction algorithm are analyzed using the corresponding forecast algorithm time series or neural network. Finally, the remaining users use the calibrated capacity of the electric energy meter instead of the actual load to analyze the stolen electricity. Time series forecasting uses an improved ARIMA algorithm based on white noise to predict the stolen electricity. The neural network uses an improved BP neural network based on independent variables to predict the stolen electricity. The research results show that this method takes into account the characteristics of a single power-stealing user while taking into account the user’s periodicity. It can reasonably recover the electricity of power-stealing users and provides a new idea for power recovery.
Research on Coal Mine Risk Control Technology and Platform Base on Big Data
Authors: Jiang Jiachen , Miao Dejun
Published: February 2021

In order to improve the risk management and control ability, this paper studies coal mine risk management technology and big data platforms. First, BP neural network was optimized through data mining, and correction parameter technology. Based on this, a coal mine risk data prediction model was constructed. Then, combined with the control chart analysis, the coal mine risk early prevention method was proposed. At last, a big data platform to manage coal mine risk was developed. The results of this paper provide implementation methods and tools for coal mine risk management and control, and have reference significance for other enterprises.
Experimental study on the evolution of shock waves generated by high-pressure diesel spray
Authors: Li Yue , Liu Bingbing , Liu Gang
Published: February 2021

High fuel injection pressure leads to supersonic fuel jet and shock wave phenomenon. The characteristic of shock waves induced by supersonic jets under different working conditions were researched based on visualization experiments. The shock wave classification characteristics were studied. This paper indicates that the shock wave angle decreases with the increase of fuel injection pressure. And the shock wave angle increases with the time. The increase of ambient pressure will speed up the separation time of the spray and the shock wave. The classification of the shock wave is determined by the Mach number of the spray.
Electricity stealing time recognition method based on difference and K-means clustering
Authors: Yining Yang , Yang Xue , Hui Cai , Boliang Pan , Jianyu Chen , Jing Li , Qian Guo
Published: February 2021

The time of stealing electricity is an important element of stealing electricity. In order to solve the disadvantages of traditional manual determination of stealing time and make the verified stealing users pay electricity charges accurately, this paper proposes a new kind of method to determine the time of stealing electricity. In this method, the difference and clustering algorithms are combined through the electricity fluctuation rate. When the power fluctuation is small, the stealing time is determined through detecting an abnormal value with the difference distribution combined box diagram method; when the power fluctuation is large, the low power period of several consecutive days is found by clustering to determine the stealing time. The example demonstrates the high accuracy of this method and its value in practical applications.