bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermometry utilizing stored short-wavelength spin waves in cold atomic ensembles
Authors: Wang Xingchang , Wang Jianmin , Zuo Ying , Dong Liang , Siviloglou Georgios A , Chen Jiefei
Published: April 2023

Temperature, as a measure of thermal motion, is a significant parameter characterizing a cold atomic ensemble optical quantum memory. In a cold gas, storage lifetime strongly depends on its temperature and is associated with the spin wave decoherence. Here we experimentally demonstrate a new spin wave thermometry method relying on this direct dependence. The short-wavelength spin waves resulting from the counter-propagating configuration of the control and the probe laser beams make this thermometry highly suitable for probing in situ the atomic motion in elongated clouds as the ones used in quantum memories. Our technique is realized with comparable precision for memories that rely on electromagnetically induced transparency as well as far-detuned Raman storage.
A Study of Holographic Dark Energy Models with Configuration Entropy
Authors: Das Biswajit , Pandey Biswajit
Published: April 2023

The holographic dark energy models provide an alternative description of dark energy. These models are motivated by the possible application of the holographic principle to the dark energy problem. In this work, we present a theoretical study of the one parameter Li holographic dark energy and the two parameter Barrow holographic dark energy models using configuration entropy of the matter distribution in the universe. The configuration entropy rate exhibits a distinct minimum at a specific scale factor that corresponds to the epoch, beyond which dark energy takes a driving role in the accelerated expansion of the universe. We find that the location of the minimum and magnitude of the entropy rate at the minimum are sensitive to the parameters of the models. We find the best fit relations between these quantities and the parameters of each model. We propose that these relations can be used to constrain the parameters of the holographic dark energy models from future observations such as the SKA. Our study suggests that the signature of a large quantum gravitational effect on the future event horizon can be detected from measurements of the configuration entropy of the matter distribution at multiple redshifts.
The Masses of a Sample of Radial-velocity Exoplanets with Astrometric Measurements
Authors: Xiao Guang-Yao , Liu Yu-Juan , Teng Huan-Yu , Wang Wei , Brandt Timothy D. , Zhao Gang , Zhao Fei , Zhai Meng , Gao Qi
Published: April 2023

Being one of the most fundamental physical parameter of astronomical objects, mass plays a vital role in the study of exoplanets, including their temperature structure, chemical composition, formation, and evolution. However, nearly a quarter of the known confirmed exoplanets lack measurements of their masses. This is particularly severe for those discovered via the radial velocity (RV) technique, which alone could only yield the minimum mass of planets. In this study, we use published RV data combined with astrometric data from a cross-calibrated Hipparcos-Gaia Catalog of Accelerations to jointly constrain the masses of 115 RV-detected substellar companions, by conducting full orbital fits using the public tool orvara. Among them, 9 exoplanets with

M

p

sin

i
<
13.5

M

Jup

are reclassified to the brown dwarf (BD) regime, and 16 BD candidates (

13.5
≤

M

p

sin

i
<
80

M

Jup

) turn out to be low-mass M dwarfs. We point out the presence of a transition in the BD regime as seen in the distributions of host star metallicity and orbital eccentricity with respect to planet masses. We confirm the previous findings that companions with masses below 42.5 M
Jup might primarily form in the protoplanetary disk through core accretion or disk gravitational instability, while those with masses above 42.5 M
Jup formed through the gravitational instability of a molecular cloud like stars. Selection effects and detection biases, which may affect our analysis to some extent, are discussed.
A New Method of Frequency Fluctuation Estimation and IPS Processing Results Based on the Downlink Signal of Tianwen-1
Authors: Liu Yu-Chen , Kong De-Qing , Liu Dong-Hao , Zhu Xin-Ying , Su Yan , Zhang Hong-Bo , Wang Zan
Published: April 2023

The radio-occultation observations taken by Tianwen-1 are aiming to study the properties of solar wind. A new method of frequency fluctuation (FF) estimation is presented for processing the down-link signals of Tianwen-1 during the occultation period to study the properties of the coronal plasma at the heliocentric distances of 4.48–19 R
⊙. Because of low S/N as well as the phase fluctuation phenomena caused by solar activity, a Kalman based on polynomial prediction methods is proposed to avoid the phase locked loop loss lock. A new detrend method based on multi-level iteration correction is proposed to estimate Doppler shift to get more accurate power density spectra of FF in the low frequency region. The data analyze procedure is used to get the properties of the solar corona during the occultation. The method was finally verified at the point when the solar offset is 5.7 R
⊙, frequency tracking was successfully performed on data with a carrier-to-noise ratio of about 28 dBHz. The density spectra obtained by the improved method are basically the same when the frequency is greater than 2 mHz, the uncertainty in the result of the rms of the FF obtained by removing the trend term with different order polynomials is less than 3.3%. The data without eliminating interference show a large error for different detrending orders, which justifies the need for an improved approach. Finally, the frequency fluctuation results combined with the information on intensity fluctuation obtained by the new method are compared with the results of the integrated Space Weather Analysis system and theoretical formula, which verifies that the processing results in this paper have a certain degree of credibility.
A Novel Silicone Rubber for Situation Awareness
Authors: Xia Bing , Li Xiaofei , Yang Xiaoyan , Zhang Donghai , Zhang Miao , Li Hao , Xu Shanjun , Kong Deqing , Li Xiang
Published: April 2023

An insulator plays an important role in the external insulation of power grid. The antifouling flashover coating on the insulator’s surface can effectively reduce the incidence of pollution flashover accidents. Local overheating, local arc, lightning and other damage lead to the deterioration of the antifouling flashover coating, resulting in pollution flashover accidents. In order to realize the on-line identification of electric arc on the surface of antifouling flashover coating, various functional nanoparticles were prepared and added into the silicone rubber to prepare functional antifouling flashover coating. The colour deviation of the coating heated at different temperatures was measured by a spectrophotometer, and the trace of arcs on the sample surface was observed. The results show that the functional nanoparticles can slightly improve the tensile strength and AC breakdown strength of silicone rubber composites. The composites change colour in 2 min at 250°C or 1s at 500°C, showing obvious indication traces after an electric arc passes the surface of an insulator in a short period. Still, the composites possess excellent functional properties after 1000h artificial accelerated aging test.
High Temperature Performance Evaluation of High Viscosity Asphalt at Different Aging Degrees Based on Multiple Stress Creep Recovery Test
Authors: Wei Jintao , Xi Chenchen , Sun Tuanwei , Yan Shoujing , Wang Yangyang , Chi Fengxia
Published: April 2023

In order to investigate the effect of high temperature on the performance of three high viscous asphalt in company with various aging degrees (ADs), multiple stress creep recovery (MSCR) test was employed. CRR and irrecoverable compliance were also carried out to measure the high temperature resistance of high viscous asphalt to external loading in the presence of various aging conditions (ACs) as well as to examine the sensitivity of high viscous asphalt towards the stress. The findings of the study demonstrated that after short- and long-term aging, the high-viscosity asphalt turned harder. Also, type I high-viscosity asphalt was observed to have the greatest deformation resistance acted upon by various stress fields and ACs. Furthermore, in company with various ACs, while the average creep recovery rate (CRR) of Type I and Type II high-viscosity asphalt was found to be higher than that of the SBS modified asphalt, the average irrecoverable compliance was observed to be smaller. This indicated the significant effect of high-viscosity modifiers on the improvement of the elastic recovery performance of asphalt and its resistance to high temperature flow deformation. Contrary to the order of their CRRs, the magnitude of stress sensitivity of the three high-viscosity asphalt at various ADs was observed to be type II < type I < SBS modified asphalt, indicating a good negative correlation between stress sensitivity and average CRR. Furthermore, the obtained results revealed that, in the presence of various ACs, the high temperature viscoelastic qualities of high viscosity modified asphalt is considered by the MSCR test. Also, to comprehensively evaluate the high temperature performance of high viscosity modified asphalt at various Ads, the use of such indexes as the average CRR, average irrecoverable compliance and stress sensitivity coefficient were essential.
Methods of Bidirectional Interpolation and Finite Volume Element for Surface Reconstruction and Volume Calculation of Midwater Trawl
Authors: Zhang Xinfeng , Hu Fuxiang , Zhang Jian , Qu Xiaoyu , Qian Weiguo , Zhang Yunwei
Published: April 2023

The spatial surface of the midwater trawl was reconstructed with combined interpolation methods of cubic spline, cubic Heimite and polar-coordinate periodic spline interpolation. The results show that the trawl surface obtained only by the ring section method or the vertical section method has a certain deviation, especially when cubic spline is used only in the X direction. When the ring section is combined with the vertical section, and the cubic spline is combined with the cubic Heimite in the X direction, the smoothest feasible trawl surface can be obtained. Two different trawl volume algorithms (volume element method and numerical integration method) were proposed. The finite volume element method can accurately calculate the volume inside the trawl, and the approximation calculation result of the numerical integration method is also very ideal. The numerical integration method is easier to calculate and suitable for the calculation of the trawl volume under any circumstances.
Preparation of Polystyrene/Polyacrylamide Core-Shell Microspheres via Microfluidizer-Assistant Emulsification Template Methods for Oil Recovery Enhancement
Authors: Sheng Li , Cui Jia , Gao Yuan , Yuan Wenjing , Wu Ying , Liu Liuxin , Lu Xiaoying
Published: April 2023

Polyacrylamide and its derivatives are commonly used functional polymers to enhance oil recovery in a water-flooding oilfield. By using its hydrophilic amide group to swell and gel in stratum water, it can plug the fractures and pore throats of underground. In order to improve the strength of polyacrylamide material, the polystyrene/polyacrylamide (PS/PAM) core-shell microspheres were successfully prepared by the microfluidizer-assistant emulsification template method. The influences of different preparation conditions, such as the different types and concentrations of surfactants, organic phase and oil/water ratios, on the morphology, diameter, and distribution of corresponding PS core have been systematically studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and laser light scattering analysis (LLS). Moreover, by the integration of porous meshes onto both inlet and outlet of the interaction chamber, the resultant polymer microspheres could be tuned larger due to the dual homogenization. Our procedure can provide a simple and general method to modulate the diameter of the polymer microspheres in the range of 30 nm to 3 μm with a narrow polydispersity index (PDI) of <0.2. The PS/PAM core-shell microspheres exhibited good water plugging performance.
Prestress Modal Analysis under Assembling Error of Diaphragm Disc Coupling
Authors: Cao Angang , Zhou Bin , Zhu Yonggang
Published: April 2023

The high-speed and high-torque diaphragm disc coupling used in coal machine-driven systems is the critical power transmission component, especially in high-speed and heavy-duty shafting. The dynamic rotor characteristics are significant. In the case of external excitation in the installation or working process of diaphragm coupling, it is inevitable to have axial deviation, angular misalignment, and radial misalignment error. Therefore, analyzing the prestress mode under the assembly error of diaphragm disc coupling is crucial. The finite element model of diaphragm plate coupling was established using ABAQUS software. The accessible way under critical speed, the mode under axial dislocation, and radial dislocation were analyzed. The results show that the assembly error of the diaphragm disc coupling will affect the first and second-order natural frequencies in a specific range but will not cause resonance.
Simulation and Experimental Research on Low-Frequency Vibration and Rotation Assisted Micro-EDM Gap Flow Field
Authors: Yi Guanwei , Guo Guangyu , Zhang Mingfang , Huo Mengyou
Published: April 2023

As the depth increases when the Electrical Discharge Machining (EDM) process is applied to the machining of micro-holes, it becomes more difficult to remove the corrosion products, leading to a decrease in machining efficiency. In order to study the mechanism and effect of the additional low-frequency vibration and rotating motion of the electrode on the improvement of micro-EDM chip removal, this paper firstly conducted a simulation study on the flow field of the machining gap, and analyzed the pressure, velocity and electrical erosion of the gap flow field by adding different auxiliary motions. The simulation results show that the auxiliary motion has a greater promotion effect on the elimination of electro-erosion products; after further experimental tests, the processing results show that adjusting the appropriate vibration frequency and rotation speed can greatly improve the chip removal ability, and then the processing efficiency has been greatly improved.
Optimal Matching Method of Structural Parameters of Hydro-mechanical Transmission Device
Authors: Wang Di , Zhu Genghui , Yang Long , Liu Quanzhong
Published: April 2023

In this paper, for the hydro-mechanical transmission device with constant speed input and variable speed output, an optimization model is constructed, which takes the structural parameters of the fixed gear train, the rotating gear train, and the circular diameter of the torque converter as the design variables and the weighted comprehensive efficiency as the objective function. The optimization model considers the influence of the change of the stator opening on the original characteristics of the torque converter, and limits the value of the structural parameters of the planetary gear train by the reference value of the transmission ratio of the planetary gear train given in the mechanical design manual, and gives the steps to solve the optimization model by using the search algorithm. The value range of the hydraulic torque converter is limited by reversely calculating the circulation circle diameter of the hydraulic torque converter within the speed range, so as to improve the search efficiency. The optimization model and solution method are verified by taking a boiler feed pump of a thermal power plant as the load.
Study on the Effect of Two Angle and Two Flow Oxygen Lance Jet on Molten Pool in Converter
Authors: Jia Hongbin , Liu Xiang , Gui Lin , Han Peng , Liu Kun
Published: April 2023

To achieve the smelting effect of low splash in large and medium-sized converters, the jet flow field simulated by compressed air at room temperature is studied by the oxygen lance (OL) jet detection experimental system in this paper. This paper mainly analyzes the variation law of jet velocity at the geometric axis of the OL nozzle and scalar distribution and attenuation of jet isovelocity line at different cross sections. The results show that the oxygen jet cross-section of all OL nozzles gradually expands with the rise of OL position. When the large hole flow ratio is between 55% and 65%, the large hole angle is between 12° and 14° and the small hole angle is between 16° and 18°, therefore the angle of hole plays a significant role in the impact radius. The larger the angle is, the larger the impact radius is. The area of action between jet and molten pool could be enlarged by staggered double-structure six-hole OL.
Optimal Design of Torque Converter Blade Angle Based on Surrogate Model Method
Authors: Zhu Genghui , Li Zhenyu , Dong Yong , Liu Quanzhong
Published: April 2023

In this paper, the blade cascade system of the basic torque converter JQB2 is redesigned and changed into a hydraulic torque converter with an adjustable stator. Firstly, the basic torque converter cascade system is modified to realize the adjustable stator. In order to study the influence of the blade angles on the performance of the torque converter, the blade angles were parameterized. Taking the peak efficiency of the torque converter at the design opening as the optimization objection, the pump torque factor is not less than 90% of the initial torque converter as the constraint condition. The central composite experimental design method was used to generate 49 design points, and the Kriging surrogate model was selected to construct the response surface of efficiency and pump torque factor, and to verify the goodness of fit of the response surface, and then iteratively search for the optimal response surface. The peak efficiency of the optimized JQB2X is 89.7%, which is 1.6% higher than that before optimization. After optimization, the pump torque factor is 6.1×10−6, which is slightly lower than that of the basic torque converter, but it can still maintain the large capacity of the torque converter.
Study on Wet Purification of Keerjian Bentonite
Authors: Deng Lirong , Lu Yufeng , Shang Xinlong , Liu Zhenxing , Dong Yongwang
Published: April 2023

The application potential of bentonite is closely related to the content of montmorillonite from it, and the purification of bentonite is conducive to expanding its industrial application. In this paper, purification method of Keerjian bentonite with low to medium grade were studied systematically. A comparative study of natural settlement, chemical dispersion and high-speed centrifugation was carried out. In addition, one-factor experiment and orthogonal experiment on a compound purification method, chemical dispersion following by high-speed centrifugation, were conducted. According to the experimental result, the optimal parameters of the compound purification, namely slurry ratio 1:8, dispersant amount 1.2% and soaking time 24h, were obtained. This study solved the problem of low utilization level and low purification efficiency, which shade light in the application of Keerjian bentonite with high efficiency and high economic benefits.
Strain-Modulated Electronic and Thermal Transport of Monolayer Black Arsenic Phosphorus
Authors: Li Xiangke , Yang Hai , Jin Guojun
Published: April 2023

In this paper, the first-principles density functional theory and non-equilibrium Green’s function method were used to investigate the effect of strain on the electronic and thermal transport of monolayer black arsenic phosphorus (B-AsP). Through this research, we found that the band gap of the monolayer B-AsP decreased under compressive strain, the electronic transport was revealed by I-V curves, and there was current at a very small voltage. The compressive strain can enhance the electronic transport, but it does not have a favorable effect on the thermal transport. When increasing the temperature at the same time for the tensile strain, the thermal transport has been improved, reflected by the ZT coefficient, which is increased by 7.76% compared with the original system. At the same time, we also used temperature to regulate the ZT coefficient. At a high temperature of 400 K, the ZT coefficient is larger than the one at room temperature by 26.11%.
Effect of Nb/V/Ti Microalloy on Microstructure and Properties of 16Mn Seamless Steel Pipe
Authors: Yuan Qin , Wang Shanbao , Zhao Bo , Wu Hong , Cheng Junxia , Xie Degang
Published: April 2023

In order to study the effect of Nb, V and Ti microalloys on the microstructure and properties of 16Mn seamless steel tube, the static CCT diagram of tested steel was made on Glecble-3800 thermo-mechanical simulator. Based on the observation of microstructures and precipitates by optical microscopy, SEM and TEM, the effect of different microalloy on mechanical properties of 16Mn steel was analyzed. The results show that Ti treated 16Mn steel is advantageous to both grain refinement and the low temperature impact toughness. The impact toughness of Nb or V microalloyed steel is decreased, which appeared bainite in hot rolling. Normalizing can improve the impact toughness of Nb microalloyed steel, while the microstructure and properties of V microalloyed steel are not improved. 16MnTi is taken to produce hot-rolled pipes with wall thickness between 8 mm to 16 mm, that impact value is more than 80 J at - 40 °C; while 16MnTiNb is taken to produce normalized pipes with wall thickness greater than 16 mm, that impact value reaches 120 J at -40°C.
Modeling and Simulation of Removal Function for Dual-axis Wheel Polishing
Authors: Chen Fulei , Peng Xiaoqiang , Lai Tao , Hu Hao , Wang Guilin , Luo Tiancong
Published: April 2023

Modern optical manufacturing techniques, such as stress disc polishing, bonnet polishing, magnetorheological finishing, and ion beam finishing, suffer from edge effects or low removal efficiency. To solve the above problems, this paper mainly studies dual-axis wheel polishing technology. According to the Preston equation combined with Hertz contact theory and kinematics, a theoretical removal function model of dual-axis wheel polishing is established. Then, the removal function shape and removal efficiency under different revolution-to-rotation speed ratios are simulated. From the simulation results, it can be concluded that the removal function of the dual-axis wheel polishing technology in this paper is Gauss type when the revolution-to-rotation speed ratio is 10:1 or less. With the increase of rotation ratio, the efficiency of the removal function is higher. This paper establishes a theoretical foundation for the design of the dual-axis wheel polishing device.
The Performance Analysis of Elevator Brake
Authors: Ren Zhaolin
Published: April 2023

In order to understand the safety status of traction drive elevator brake, taking the most common drum brake as the research object, several common failure forms of drum brake and the problems found in brake disassembly are summarized and sorted out. Based on the analysis of failure causes, suggestions on the use and maintenance of elevator brakes are put forward, and the in-service elevator brakes which have been used for a certain period of time are tested, and the performance characteristics of the in-service elevator brakes are analyzed, which provides a basis for the promotion of hidden trouble investigation and rectification of elevator brakes.
Study on Spent Lubricating Oil from Catalytic Cracking of Al/SO42-/AL-MCM-41 Molecular Sieve
Authors: Gong Jing
Published: April 2023

The waste lubricating oil will cause great harm to the natural environment if it is discarded randomly or handled improperly. Catalytic cracking is the main technology for regenerating waste lubricating oil into fuel oil. The molecular sieve Al/SO42-/Al-MCM-41 was prepared by introducing metal Al atoms into the molecular skeleton of MCM-41 and then modifying it with Al2(SO4)3. The samples in the preparation process were characterized and analyzed by TG, FTIR, XRD, N2 adsorption desorption and other test techniques. The effects of reaction temperature and the amount of catalyst on catalytic cracking of used lubricating oil were studied. The results show that: The existence of large pores in the catalyst is conducive to the entry of waste lubricating oil molecules into the pores, so that the surface active sites of the catalyst can be fully utilized. When the silicon aluminum ratio is 1:0.02 and the calcination temperature is 600 °C, the catalyst has the highest activity. When the reaction temperature is 400°C, the reaction pressure is 0.01 MPa, the stirring speed is 200 rpm, and the amount of catalyst is 2.8 g. The yield of gas product is 1.11%, the yield of liquid product is 87.02%.
Simulation on the Solid Flow in COREX Shaft Furnace with CGD Using DEM
Authors: Wang Xiaoai , Luo Zhiguo , Zhang Caidong , Li Lanjie , Yao Hongyong , Tian Zhiqiang , Han Xing
Published: April 2023

In order to obtain the resonable gas distribution, a Center Gas Distribution (CGD) technology was introduced into a new set of COREX-3000 in Baosteel. However, CGD can affect the solid flow in the shaft furnace. In this paper, DEM was used to investigate the basic solid flow pattern, the influence of discharging rates and non-uniform discharging rates on the burden movement and the influence of CGD on the solid flow pattern. The influence of CGD on the velocity and distribution of solid flow was also studied. The results confirm that there are three types of flow zones in furnace. The discharging rate has almost no effect on the overall burdern movement. The non-uniform discharging rate leads to a large stagnant zone on one side of the shaft furnace. CGD has a great influence on the solid flow pattern of furnace, and there may be two stagnant zones where the small particles tend to segregate. The distribution of particles velocity along the radial is different with the distance from the bottom.
Degradation of Methylene Blue Using Fe-ZSM-5 Zeolite as a Heterogeneous Fenton Catalyst
Authors: Ning Mencui , Li Li , Xu Xiaojing
Published: April 2023

A Fe2O3 modified ZSM-5 hybrid was synthesized by solid phase exchange method in this work. The prepared Fe-ZSM-5 material was characterized by XRD and SEM and was used as a heterogeneous Fenton catalyst in oxidation of methylene blue. The influences of different parameters such as the initial pH value, the amount of catalyst, amount of H2O2, contact time and reaction temperature on the removal rate of methylene blue were evaluated. Results showed that under the optimum conditions of catalyst dosage of 1.1 g/L, initial pH value of 3.0, reaction temperature of 30°Cand H2O2 30 mmol/L, 98.2% of decolorization rate could be achieved in 60 minutes. This work provides a promising catalyst for the decolorization of methylene blue in aqueous solution.
Effect of Natural Particles on the Growth and Behavior of Sebastes Schlegelii
Authors: Diao Wenjing , Liu Liuqingqing
Published: April 2023

In recent years, human activities and climate change are likely increasing the input of particles in the aquatic environment, raising concerns about the negative effects to aquatic organisms. However, the impact of natural particles on the marine organisms is not clear. Here, this study compared the effects of two different size of natural particles on the growth and behavior of Sebastes schlegelii. Results indicated that the weight gain rate and specific growth rate of juvenile fish in the P-S treatment group were respectively reduced by 11.12% and 1.48%, while it respectively reduced by 17.62% and 2.16% in P-L treatment group after 7 days of exposure. In addition, dietary exposure to natural particles seriously increased the average speed and distance moved of the fish than the control, and the negative effects was enhanced with the increase of particle size. The results not only showed the inhibition of natural particles on the growth of the juvenile fish, but indicated that the locomotor activity of the juvenile fish was increased. This study provided basic theoretical data for assessing the effects of natural particles on aquatic organisms.
Environmental Impact Assessment of Apple Production under Different Production Modes and in Different Regions in China
Authors: Men Xiaopeng , Wang Yubin , Xu Xuefeng , Wang Yi , Han Zhenhai
Published: April 2023

The full-fruit period in apple orchards has the greatest environmental impact during the whole apple life cycle, and the characteristics of apple planting and high investment in agricultural materials in China aggravate the impact of this stage on the environment. The life cycle assessment (LCA) method was used to study the resource use (RU), global warming potential (GWP), environmental acidification potential (AP), and eutrophication potential (EP) of apple orchards in the full-fruit period. These apple orchards are, smallholder orchards (SO) in the Bohai Bay area (BH), commercial orchards (CO) in the Bohai Bay area, smallholder orchards in the Loess Plateau area (LP), and commercial orchards in the Loess Plateau area. The results showed that the RU of commercial orchards was 23.87% higher than that of smallholder orchards, the EP of smallholder orchards was 72.36% higher than that of commercial orchards, the RU of the Bohai Bay was 19.70% higher than that of the Loess Plateau, the EP in the Loess Plateau was 35.93% higher than that in Bohai Bay.
Preparation and Photocatalytic Degradation of ZnO Graphene Composites
Authors: Guan Xianqi , An Changwei , Zhang Jun
Published: April 2023

A series of ZnO graphene composites with different reduced graphene oxide (RGO) contents (0%, 2%, 4%, 6% and 8% (mass fraction)) were prepared by solvothermal method. The composite samples were characterized by XRD, SEM and pl. The results show that all the composite samples doped with RGO do not change the structure of ZnO; Pure ZnO samples are spherical particles with grain size of about 40 nm. After adding RGO, the grain size of the samples is uneven, and the agglomeration of the composite samples increases gradually with the increase of RGO content; The emission peaks of all composites are near 373 nm. With the increase of RGO content, the intensity of the intrinsic emission peak of the composites decreases first and then increases. The introduction of RGO makes the absorption peak has a slight red shift, which improve the visible-light absorption ability of the composites. With the increase of RGO content, the photocatalytic performance of the composites increased first and then decreased. When the RGO content was 6% (mass fraction), the photocatalytic performance of the composites was the best, and the degradation rate and reaction rate constants reached 71.97% and 0.017 min-1 respectively.
Energy Conservation and Carbon Reduction of Air Source Heat Pump for District Heating
Authors: Zhao Yuan , Gao Jun , Zhu Bo , Qian Tang , Wang Dabiao , Wang Qilong , Zhao Ruirui , Dai Baomin
Published: April 2023

Using ASHP for space heating is an environmental solution. Based on the concept of Lorenz cycle, an ASHP is proposed. Taking a residential community as an example, this study proposes a thermodynamic model. Then, the energy consumption and carbon emission performance of the heating system are discussed. The results indicate that the primary energy consumption of ASHP is 13.45% less than the coal-fired boiler and the carbon emission reduces by 1203.6 tCO2. This study is meaningful for the development of air source CO2 heat pump for space heating integrated with DMS.
Ballistic Wound Evaluation Based on Dye Diffusion Method
Authors: Mo Genlin , Jin Yongxi
Published: April 2023

Ballistic gelatin is widely used as a kind of tissue simulants in wound ballistics. Evaluations of the wound tract of gelatin by projectiles are mainly based on fissures in the gelatin slices. For there are difficulties in building relationships between the areas and the fissures, a new method based on dye diffusion is proposed in this paper. Colored regions in the slices are obtained after penetration of a Chinese 7.62mm rifle bullet into the gelatin block. The colored regions can be divided into ‘X’, ‘I’ and branching ‘I’ shapes. In the second half of the penetration, there is a strong correlation between the areas of the regions and the energy dissipation of the bullet. However, the correlation is poor in the first half of the penetration. Branches of the colored regions mainly distributed at the heads and tails of the permanent cavities. The permanent cavities’ shapes have a great dependence on the nutation angles of the bullets. Orientation angles of the permanent cavities are determined by the precession angles of the bullets.
Solution of Density Profile Function of Trapped Fermi System
Authors: Liu Hongyan , Ren Shufeng , Wang Jiaxiao , Li Yushan
Published: April 2023

Starting from many-body theory, the density profile function of ideal Fermi systems in harmonic and delta traps are obtained under the quantum mechanics and thermodynamic statistical physics, respectively. The related thermodynamic properties are analyzed based on the Fermi-Dirac distribution and exact solution of the density profile function.
2-D Quantum Ising Model Fidelity and Order Parameter
Authors: Li Shenghao , Wu Yuanyuan
Published: April 2023

This paper explores an interesting relationship between the ground-state fidelity quantum phase transitions and bifurcations per lattice site, and proposes a universal order parameter for the quantum Ising model for a square lattice of infinite-size in two spatial dimensions as a prototype model with symmetry breaking order. The approach is based on computing ground-state wave functions using a tensor network algorithm utilizing a representation with infinite projected entangled-pair states. The results can be applied to any systems with symmetry breaking order, because in the conventional Landau-Ginzburg-Wilson paradigm a quantum system subjected to a phase transition exhibits spontaneous symmetry breaking quantified by a local order parameter. A reduced fidelity bifurcation between two different reduced density matrices is also explored.
The Dynamic Programming Model for Calculating the Maximum Number of Gathering Passengers in High-Speed Railway Station Based on Gaussian distribution
Authors: Xia Xiong , Hou Wei , Li Xin
Published: April 2023

in this paper, based on the actual train operation plan and evacuation plan of the high-speed railway station, taking the train capacity and occupancy rate as the basic data, the Gaussian function is used to describe the passenger arrival law and the uniform distribution is used to describe the passenger evacuation law. Also, the calculation model of the number of gathering passengers at the high-speed railway station is established by MATLAB. Taking Guangzhou South Railway Station as an actual case, the maximum number of gathering passengers in the whole day and the change curve of the number of gathering passengers with time are obtained. The calculation results are consistent with the actual situation, which can provide a reference for the passenger flow organization and management of the high-speed railway station and the new construction and reconstruction of the high-speed railway station.
Tunneling Time of the Triangular Barrier and the Rectangular Barrier
Authors: Li Qingling , Zheng Shuang
Published: April 2023

In this paper, we calculate the phase time and dwell time of the triangular barrier and the rectangular barrier. The phase time and dwell time firstly increase and then decrease with wave number. In the tunneling region, the phase time decreases with the increase of barrier height, and firstly decreases and then increases with the increase of barrier width. Dwell time decreases with the increase of barrier height and increases with the increase of barrier width.
Conceptual options for solving the problem of icing rollers and drums of belt conveyors
Authors: Minin Ivan , Nedyalkov Petko , Hristova Teodora , Kraychev Evgeni , Dimov Emil
Published: April 2023

In the current development, the object is the icing of drums of belt conveyors that work in open mines located at high altitudes and in winter conditions. A literature review was made of publications related to the problems at low temperatures and the presence of moisture, including the icing of rollers and drums of belt conveyors. Conceptual options are suggested to prevent freezing and related accidents. The options are accompanied by short methods for determining the main technical parameters. Finally, the advantages and disadvantages of the described options are indicated and, in conclusion, the best among them for the specific working conditions. A stationary or a mobile heater is chosen as a better option.
Complex diagnostics of concrete lining technical condition
Authors: Skipochka Serhii , Serhiienko Viktor , Amelin Volodymyr , Amelina Larysa
Published: April 2023

The main use of concrete lining is mine and hydraulic engineering construction. The options of its use in underground structures and mining operations have been considered. The advantages of this lining during construction and operation have been reflected. A long service life of underground facilities with concrete lining in Ukraine has been noted. The typical defect types have been identified. The main reasons for defect formation have been reflected. The impact of natural factors on the deterioration of the lining has been researched. The possible consequences of the flaw growth have been reported. Limited opportunities for visual inspection of the concrete surface have been noted. The main areas of non-destructive test of linings have been analyzed. The basic set of methods and control devices have been established. Special features of monitoring with various methods have been indicated. The main requirements for the registration of primary data have been defined. Typical options of office data processing have been outlined. According to the processing results, the category of the technical condition of the lining is determined. Criteria for assessing the technical condition have been presented. Specific examples of complex examination of concrete lining have been provided.
Numerical analysis of aerodynamic regime near tailings storage facility
Authors: Semenenko Evhen , Medvedieva Olha , Biliaiev Mykola , Rusakova Tetiana , Blyuss Konstantin
Published: April 2023

Tailings formed during the mining and beneficiation of iron ore are sources of intensive dust generation. In order to assess the intensity of dust formation and determine the effectiveness of methods of its reduction, it is necessary to know the local velocity of the air flow near the various surfaces of the tailings storage facility. For the theoretical solution of this problem, a CFD model was developed, which allows determining the velocity field of the air flow when flowing around the tailings storage facility. The model allows you to obtain the value of the wind speed near the surfaces of the structure and, based on this information, to make a forecast of possible dust formation. The constructed CFD model is based on the use of an aerodynamic model of potential motion. The modeling equation is the Laplace equation for the velocity potential. To build a numerical model, the idea of establishing a solution in time is used, therefore numerical integration of the “unsteady equation” for the velocity potential is carried out. Numerical integration is carried out using the finite-difference method of total approximation. The results of the computational experiment are presented.
Influence of waste rock dump placement on the geomechanical state of underground mine workings
Authors: Petlovanyi Mykhailo , Sai Kateryna , Malashkevych Dmytro , Popovych Vasyl , Khorolskyi Andrii
Published: April 2023

This paper is devoted to assessing the influence of waste rock surface dumps on the geomechanical state of underground mine workings. The conditions of the Pivdenno-Bilozerskyi high-grade iron ore field are chosen as the research object. To study the influence of dump placement and the depth of mine working on the mass stress state on the contour of sublevel drifts, a numerical modeling methodology based on the SolidWorks software package has been developed. This methodology involves the substantiation of the elements and properties of the geomechanical model, as well as the calculation scheme. Polynomial patterns of changing stress value in the hanging wall drift sides have been determined in the depth intervals of 440–740 m depending on the distance of the dump to the geometric center of the stope chamber. It has been revealed that the degree of the waste rock dump influence on the stress state gradually decreases with depth. It has been found that the maximum degree of the waste rock dump influence is observed on the upper horizons. When the waste rock dump is located above the geometric center of the future stope chamber that the stress value on the contour of the hanging wall drift can increase up to 10% compared to the absence of a dump on the earth’s surface. The research results are important for designing stable parameters for supporting sublevel drifts in difficult conditions of occurrence of the hanging wall rocks.
Substantiating the parameters for a non-circular structure of the mine shaft under construction in a heterogeneous rock massif
Authors: Alkhdour Ahmad , Tiutkin Oleksii , Bannikov Dmytro , Heletiuk Ihor
Published: April 2023

Mine shafts are those workings without which the normal operation of coal enterprises and underground construction facilities is impossible. The new experience in the construction of mine shafts for the Dnipro Metro is based on the rejection of prefabricated structures. In addition, the ellipse structure of the mine shaft 15 bis of the Dnipro Metro is uncharacteristic for construction in Soviet and post-Soviet Ukraine. That is why technological advancements in the design of vertical workings for the non-circular structure require scientific justification. The complexity of operating such underground facilities under the engineering and geological conditions in the city of Dnipro is the interaction with a heterogeneous massif. Therefore, the design of the mine shaft frame involves its division into parts (the so-called pile system and shotcrete system). The finite-element models of both systems have been developed. A search for the force factors in a non-circular structure of the shaft has been carried out; the parameters for both systems have been substantiated. The results of the analysis have made it possible to scientifically substantiate the structural solutions. They enable the prediction of high strength indicators of the mine shaft under construction in a heterogeneous rock massif.
Regularities of the stress state of the rock massif around the single-vault station under construction by NATM
Authors: Radkevych Anatolii , Tiutkin Oleksii , Kuprii Volodymyr , Tkach Taisiia
Published: April 2023

Subway stations are underground facilities of high responsibility. The use of new construction technologies requires their scientific justification. The single-vault station “Teatralna” of the Dnipro Metro is designed as one that is under construction by the New Austrian tunneling method. Since this type of station is a working of a large cross-section, it is necessary to determine the stress state of the rock massif, which affects the temporary fastening. The finite-element model is developed, which shows the stages of cross-section opening. The developed model reproduces the layout of the subway station in the rock massif and the characteristics of the temporary fastening. The numerical analysis for six stages of station construction is carried out. The distributive features of horizontal stresses and the asymmetry of the stress state of the rock massif are clarified. For the first time, the regularities of the rock massif around the single-vault station under construction by the New Austrian tunneling method are obtained. It is established that the maximum of horizontal stresses appears at the stage of opening the lower left part of the cross-section.
Analytical determination of transient current flowing through a human in contact with conductive objects under high voltage power lines
Authors: Petrov Petar , Velev Georgi , Ivanov Krasimir
Published: April 2023

The paper inhere presents an approach for calculation of transient currents flowing through a human in contact with conductive objects under high voltage (HV) power lines by means of analytical expressions derived for that purpose. Three different case studies have been investigated and their respective equivalent circuit’s parameters have been specified and implemented: contact of an insulated from earth person with the steel-tower pole of an outdoor high voltage power line; contact of a non-insulated from earth person with a vehicle under a high voltage power line; contact of an insulated from earth person with a vehicle under a high voltage power line. The derived mathematical models and expressions have been obtained using the Mirror images method and Maxwell’s potential coefficients and the transient current trough the human body has been calculated using the Classical method for analysis of transient processes in linear electrical circuits. Conclusions have been made in regard with the degree of danger of electric shock for the three discussed case studies depending on the rated voltage and the geometrical properties of the most often met high voltage power lines in EU.
Study of vertically mounted photovoltaic modules and their influence on the production of electrical energy in free-standing photovoltaic systems using PVGIS-CMSAF
Authors: Varbov Tsvyatko , Velev Georgi , Ivanov Krasimir
Published: April 2023

The paper inhere explores the impact of the azimuth angle of vertically mounted bifacial photovoltaic modules on annual electricity generation. At the recent years bifacial photovoltaic modules are introduced to the market, opening new opportunities for increasing efficiency of electricity production and decreasing of the space needed for installation. The purpose of the current study is to obtain and evaluate the annual electricity production of bifacial vertically mounted photovoltaic modules in dependence on the orientation. Comparative analysis has been made between the efficiency and annual energy yield of bifacial vertically mounted PV modules and classically installed PV modules. All the calculations and analyses have been made with the aid of the software product PVGIS-CMSAF. Despite of the controversial increase of efficiency of bifacial vertically mounted photovoltaic modules compared to classically installed photovoltaic modules, the study had confirmed some of their advantages: they require less space for installation; can be used also as PV fences or noise barriers; in some cases the land of installation can be cultivated, used for agriculture or animal husbandry.
The concept of risk-based technical solutions for the protection of coal mine workings
Authors: Skipochka Serhii , Palamarchuk Tetiana , Prokhorets Liliya
Published: April 2023

Annotation

The concept of risk-based technical solutions for the protection of coal mines workings is outlined. The initial data of effective risk management methods are substantiated. A mixed method of risks assessment has been used. The method involves building a matrix of consequences and probabilities by ranking them in the form of tables. The following data have been used as initial data: location, method and parameters of the workings protection, additional measures to manage the state of the rock mass around the workings, cost of certain types of work and material costs, purpose and term operation of the workings. Technical solutions for the protection of underground workings in coal mines to increase labor safety and reduce environmental and financial risks are substantiated. Initial data for effective methods of risks management in the protection of workings in difficult mining and technical conditions have been prepared. It is recommended to use these data as the basis of the new regulatory framework.