bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerodynamic modeling of ducted fans under environmental disturbances
Authors: Luo Yiwei , He Yuhang , Qian Yuping , Zhang Yangjun
Published: March 2024

Ducted fans are widely used in unmanned aerial vehicles (UAVs) to perform various tasks due to high efficiency, high safety and low noise. The external environment affects the stability of the ducted fan, and predicting the aerodynamic characteristics under environmental disturbances is of great significance for stable operations of ducted-fan aircraft. In this paper, we considered the influence of different environmental disturbances on the axial velocity through the rotor disk, and established an aerodynamic mechanism model based on the momentum theory and blade element theory. In order to verify the model validity, three-dimensional CFD (Computational Fluid Dynamics) numerical simulation and bench tests were carried out. The results indicate that the mechanism model can well predict the thrusts and torques of the ducted fan under different flow conditions and wall constraints, and the errors between the model and the simulation results are generally within 12%. Overall, the established model is universal and extendable for different types of disturbances, and has the potential to be applied to evaluate the impact of unknown disturbances.
Experimental investigation on coupling characteristics of principal and shear stress of wind turbine under dynamic change of wind direction
Authors: Yan Sijia , Wang Jianwen , Zhang Jianwei , Gao Zhiying , Bai Yefei
Published: March 2024

The wind direction misalignment problem significantly impacts the abnormal alteration in aerodynamic distribution, ultimately resulting in an abnormal stress response of wind turbines. In this study, an experimental method was employed to simulate dynamic wind changes. The study aimed to analyze the laws and mechanisms governing changes in principal and shear stress on wind turbine blades and towers under different wind dynamic change angles. The results revealed that variations in the initial tip speed ratio significantly influenced the stress experienced by the tower during dynamic changes in wind direction. The coupling effect of yaw and gyroscopic moments led to a transient increase in both principal and shear stresses in the wind turbine tower during the early stage of wind direction change. Due to inertia and aerodynamic deterioration, the principal and shear stress values of wind turbine blades and towers exhibited delayed changes. Notably, when the wind direction changed by 15° from the direction the turbine was facing, the principal stress fluctuations in the wind turbine tower and blade were 5.13 and 1.23 times higher, respectively. Therefore, when developing a small-angle yaw strategy, stress fluctuations should be comprehensively considered, in addition to power requirements.
Analysis of internal flow characteristics of water-jet propulsion under turning conditions
Authors: Chen Jiahao , Pan Zhongyong , Wu Xu
Published: March 2024

In order to explore the internal flow characteristics of the water-jet propulsion under turning conditions, we carried out numerical simulations of the axial-flow water-jet propulsion under different turning conditions and set up monitoring points at the inlet and outlet of the impeller to analyse the internal pressure pulsation law of the water-jet propulsion under different turning conditions. The calculation results show that the propulsion performance of the propeller decreases with the increase of the turning angle, and the left turn is better than the right turn. The vortices mainly appear around the rotor shaft, the inlet of the suction pipe and the side wall opposite to the suction pipe. The larger the turning angle, the larger the vortex area in the impeller section, while in right-hand rotation, the vortex on the suction surface decreases and the vortex on the trailing edge increases. The opposite is true for left-hand rotation. The change in pressure on the inlet surface of the impeller with the rotation angle is less pronounced compared to right-hand rotation. In addition, the pressure pulsation pattern on the impeller outlet surface is slightly improved in left-hand rotation compared to right-hand rotation.
Numerical simulation of the complex flow field in a new recycling cyclone separator
Authors: Liu Q X , Li Z L , He X J
Published: March 2024

The three-dimension flow field is simulated in a recycling cyclone separator using the Reynolds stress model (RSM) with Fluent 6.2. The results show that the unique design of the flow route of the recycling cyclone separator can improve the axial symmetry and the order of the inner flow field. The appearance of the eddy flow and the pressure drop of the recycling cyclone separator are also reduced. Moreover, the secondary circulation in the recycling cyclone separator is analyzed, which is useful for understanding the flow mechanism. This study provides a reference for further improvement of the recycling cyclone separator.
Heavy-duty gas turbine 3D blade modelling and flow field analysis
Authors: He Zongze , Xin Jiali , Guan Jin , Weng Yiwu , Lv Xiaojing
Published: March 2024

Hydrogen-fuelled heavy-duty gas turbine is an important trend of gas turbine due to its low emission characteristics. Due to the change of components and thermodynamic properties of the fuel, the physical properties of the working fluid of the turbine will change and affect the performance of the gas turbine. In this study, through 3D scanning and inverse modelling, the parametric models of the turbine blades were obtained. CFD analysis was conducted to analyse the change of thermodynamic performance and flow field under different fuel, which is natural gas, 50% natural gas and 50% hydrogen and hydrogen. The result of the CFD indicated that the efficiency of natural gas fuelled working flux is 92.86%, and decreased by 0.19% and 0.83% with hydrogen doped in. It is analysed that though the increased magnitude of relative velocity with hydrogen doped in, the increased flow attack angle of the rotor, from -4.74°, to -3,61°, to -1.88° with hydrogen doped in, caused the split of rotor leading edge cooling air and decreased the efficiency of the turbine stage. Modification of blade metal angle could boost the efficiency of the turbine stage under hydrogen-doped fuel.
Impact of uncertainty in the physics-informed neural network on pressure prediction for water hammer in pressurized pipelines
Authors: Huang Hai , Guo Pengcheng , Yan Jianguo , Zhang Bo , Mao Zhenkai
Published: March 2024

In pressurized pipeline systems, accurate prediction of water hammer pressure is crucial for ensuring safe system operation. When the boundary conditions are unknown and measured data is sparse, both traditional methods fully based on physical equations and data-driven neural network methods have difficulty in accurately predicting water hammer pressure. The physics-informed neural network (PINN) overcomes these challenges by simultaneously incorporating measured data and physical equations during the network training process. However, PINN has uncertainties and their impact on the accuracy of pressure prediction is not yet clear. In this study, the valve closing water hammer in a reservoir-pipeline-valve system is taken as the research object, we investigate the influence of the uncertainty of physics and data in the PINN on prediction accuracy by using water hammer equations with various friction models and training data with various noise levels. The results show that using the water hammer equation with the Brunone model, the PINN model has higher prediction accuracy. Furthermore, data noise levels less than 10% have a relatively small impact on pressure prediction accuracy, indicating that the PINN model has good robustness in terms of data noise levels.
Numerical analysis of accelerating and decelerating ducts modified by camber on the unsteady flow field of pump-jet
Authors: Zhou Yunkai , Yuan Jianping , Fu Yanxia , Gao Quanlin
Published: March 2024

Utilizing the Reynolds-averaged Navier-Stokes equations method in conjunction with Detached Eddy Simulation model, this paper investigates effects of duct camber (f) on transient hydrodynamic characteristics, particularly propulsion performance and flow field behavior. The research begins by validating the numerical methodology through experimental and numerical assessments of propeller VP1304 and a pump-jet operating under mooring conditions. The exploration commences with examining propulsion characteristics, followed by analyzing time-domain and frequency-domain data, wherein thrust fluctuations and pulsating pressures are scrutinized via fast Fourier transform (FFT). The pressure distribution and velocity field are subsequently presented to unveil the mechanisms triggered by variations in f. Comparative findings highlight that in cases of pump-jets with lower camber, the outlet velocity exceeds the inlet velocity, a trend contrary to scenarios involving higher f values. Additionally, by analyzing vorticity magnitude distribution and vortices, this study attains comparative insights into the effects of accelerating and decelerating ducts on rotor and stator trailing vortices, offering a window into the flow instability mechanism amidst diverse duct configurations. The results showcased to demonstrate the substantial impact of f variation on hydrodynamic properties. This comprehensive investigation yields practical guidance for the optimal design of pump-jets, potentially informing future design endeavours.
Investigation on influence mechanism of length-to-diameter ratio on fluid-structure interaction characteristic of serpentine nozzle
Authors: Li Qiulin , Zhou Li , Shi Jingwei , Zhang Yi , Wang Zhanxue
Published: March 2024

The effect of different length-to-diameter ratios on the fluid-structure coupling characteristics of double serpentine nozzle for turbofan engine was studied by using serial bidirectional loose coupling method. The results show that the structural deformation of the serpentine nozzle is mainly located at the downstream channel of the first bend of the nozzle and the upper wall of the exit of the nozzle, and with the increase of the length-to-diameter ratio, the deformation amount of the nozzle gradually increases. The maximum deformation of the upper and lower walls of the serpentine nozzle occurs in the downstream region of the first bend of the serpentine nozzle. The fluid-structure coupling effect has an influence on the flow field characteristics and aerodynamic performance of the serpentine nozzle. When the length-to-diameter ratio is 2.4, the influence of fluid-structure coupling effect is lowest, and the total pressure recovery coefficient decreases by 0.40%, the flow coefficient decreases by 5.34%, and the thrust coefficient decreases by 0.92%. When the length-to-diameter ratio is 3, the influence of fluid-structure coupling effect is highest, and at this time, the total pressure recovery coefficient decreases by 0.48%, the flow coefficient decreases by 5.95%, and the thrust coefficient decreases by 1.12%.
A numerical investigation of using vortex generators to improve a flush waterjet performance
Authors: Du X , Zhou Y Y , Chen L , Dai R
Published: March 2024

The flow separation on the ramp side of the inlet duct is the main reason for the performance degradation of the waterjet propulsion system under low inlet velocity ratio (IVR) conditions. A micro ramp vortex generator (MRVG) is installed on the bottom of the ship before the inlet entrance to suppress the ramp flow separation and to reduce the inlet flow distortion and improve the efficiency of the waterjet propulsion pump. The influences of the vortex generator on the overall performance and internal flow fields are computed with CFD solver. The results show that under the IVR=0.5 condition, the MRVG device can suppress the flow separation on the ramp side of the inlet duct. It increases the uniformity coefficient of the inlet flow from 0.64 to 0.75, but decreases the total pressure recovery coefficient by 0.02. The total pressure distortion DC60 is reduced by 0.665. After the installation of the vortex generator, the thrust of the propulsion system is increased by 4.01%, and the propulsion efficiency is improved by 3.99%.
Numerical simulation and thrust performance optimization of water jet thruster
Authors: Lou Yuan , Peng Guangjie , Chang Hao
Published: March 2024

With the increasing use of water jet thrusters on ships, the demand for increasing their thrust performance and efficiency is also increasing. The impeller, as the core power component, is the key to the thrust of the water jet thruster. Therefore, to obtain a more energy-saving, low-carbon, and higher-thrust water jet thruster, this paper conducts an in-depth study on the impeller of the water jet thruster. The hexahedral grid is used to divide the internal flow field of the water jet thruster into structured grids, and the RANS equation and k-ε turbulence model are used to simulate the hydraulic performance of the original model, and then the blade of the impeller is optimized. Finally, compared with the original model, the simulation results of the optimization model show that the efficiency is increased by 4.8 %, and the thrust at the highest efficiency point is increased from 614 N to 1623 N. The optimized model greatly improves the efficiency and thrust of the water jet thruster, and the optimization effect is obvious.
Vibration isolation characteristics of a rubber isolator in the deep water condition
Authors: Yang Danyi , Xue Lei , An Yvchen , Liu Jing
Published: March 2024

In order to explore the effect of the deep water condition on the vibration isolation performance of rubber isolators, a finite element model of shipboard rubber vibration isolator with different depths which considers the nonlinear material properties of rubber is established. The nonlinear properties of rubber materials are characterized by the Mooney-Rivlin hyper-elasticity model. Hydrostatic pressure is applied on the surface of the isolator in the form of pre-stress to simulate deep water conditions. The static and dynamic mechanical characteristics of the rubber isolator under deep water environment are obtained. The results show that the static stiffness of vibration isolator increases with the water depth, especially when the rubber hardness is high. The natural frequency of the isolator under deep water environment increases with the water depth. The transmission loss of rubber isolators under deep water environment significantly reduces due to the change of static stiffness. The results can provide technical support for the design and optimization of underwater vibration isolators.
Simulation analysis of bubble coalescence behavior characteristics in Newtonian fluids based on the phase field method
Authors: Long Li
Published: March 2024

Gas-liquid two-phase flow is widely used in various fields of chemical production because of its stability. The bubble coalescence behavior significantly impacts bubbles’ size, shape, and movement. These parameters are essential for interphase mass, heat transfer processes, and equipment performance. This paper presents a simulation study of the bubble coalescence behavior of Newtonian fluids using the phase field method through simulation software. The relative location of bubbles were divided into three types: vertical, parallel and random; and also the distribution of bubbles can be divided into three cases: symmetric, left-skewed and right-skewed. This paper focuses on the influence of the arrangements of the bubbles on their coalescence behavior in Newtonian fluids. The results show that the relative distance of bubbles is the crucial factor for the occurrence of bubble coalescence in Newtonian fluids, and different distributions show different laws on the motion of bubbles.
Thermal elastohydrodynamic lubrication analysis of the oil film temperature in tapered roller bearings
Authors: Yu Tao , Shen Wenhao , Xu Chunhui , Liu Quanzhong
Published: March 2024

Tapered roller bearings often experience thermal deformation and stress concentration due to high temperature during prolonged operation. However, the traditional model for calculating bearing heat does not consider the thermal elastohydrodynamic behavior of the lubricant. To address this issue, this paper proposes a finite line contact model based on thermal elastohydrodynamic lubrication analysis for calculating the temperature distribution of the lubricant within tapered roller bearings. The temperature of the lubricant is solved using the column-by-column technique. The results show that the temperature distributions along the thickness of the oil film are symmetrical, with the highest temperature occurring at the middle layer. Furthermore, the temperature at the middle layer increases with both the bearing speed and the concentrated load. These findings provide a theoretical framework for calculating the temperature distribution of lubricated bearings, offering valuable insights for practical applications.
Study on microchannel cavitation phenomena based on experiment and simulation
Authors: Meng W J , Lei C , Su W T , Li B
Published: March 2024

Cavitation phenomenon is a common fluid mechanics phenomenon. Its special flow limiting structure generates abundant microchannel cavitation in the microchannel, and the existence of these cavitation flow field with complex flow field structure characteristics is formed in the microchannel. In order to better understand the cavitation phenomenon in the microchannel, this paper takes the microchannel as the research object, adopts the method of comparison between experimental research and numerical simulation, changes the cavitation number by adjusting parameters, and analyses the cavitation phenomenon of the microchannel under different working conditions. From the experimental point of view, a micro-channel with rectangular current limiting structure was designed. In order to observe and analyse the microchannel hydraulic cavitation phenomenon, the hydraulic cavitation micro-channel experiment platform was designed and built, which could analyse the cavitation flow pattern of the microchannel. The computational fluid dynamics simulation software Fluent was used to simulate and study the microchannel cavitation phenomenon characteristics by changing the boundary conditions. It is found that the cavitation phenomenon becomes more obvious as the number of cavitations decreases. Finally, the simulation results are compared with the experimental results, and the simulated cavitation flow pattern is in good agreement with the experimental results.
Analysis of the influence of venturi structural parameters on the performance of hydraulic impactors
Authors: Hou Lingxia , Feng Ding , Wang Jiangang , Zhang Yiduo , Hou Xuewen
Published: March 2024

The venturi effect can be used to control the fluid pressure at different locations in the pipe, and the pressure difference generated based on this principle can push the piston inside the hydraulic impactor up and down to impact the drilling tool, thus expanding the use of coiled tubing and improving the efficiency of drilling. In this paper, the effects of several different necking sizes, tapering angles and diffusion angles on the flow field state and pressure control performance inside the venturi are studied, and the influence laws are analyzed by using Fluent finite element software, and the effects are verified by numerical simulation. The related research have a great significance to the selection of venturi structure size, and it also provides the theoretical basis for the optimization of the structure parameters of the hydraulic impactor.
An Eulerian-Eulerian CFD modeling analysis of gas-liquid flow under elevated pressure
Authors: Gao Yibo , Geng Linlin , Zhang Desheng
Published: March 2024

In this study, a newly proposed pressure correction method coupled with DBS drag force model was used to simulate the gas-liquid flow in a bubble column, which combines Eulerian-Eulerian approach to simulate gas-liquid flow under elevated pressure conditions. This further verifies the accuracy of the model and expands its application range. The gas holdup and velocity distributions of different models were compared, and the performance of the new model was similar to that of Yan et al., while the model of Tran et al. was not sensitive to the influence of the pressure in this study. It was found that the drag model using the new pressure correction method showed the best consistency.
Investigations on cavitation suppression of bionic water-jet impeller
Authors: Wang J Q , Wan C R , Zhou M , Wang Z L , Yang M Z
Published: March 2024

Bionic impeller blades can improve cavitation performance of waterjets. A Special kind of bionic impeller with non-smooth leading edge is designed to improve the NPSH (net positive suction head) performance of waterjets. Based on the cavitation experiment of the waterjet with original impeller, a reliable CFD method using the commercial software StarCCM+ is verified. The detailed flow field of the bionic blades is obtained by simulating the viscous flow field. The stream line, pressure distribution and vortex reveal the mechanism of bionic blades flow adjustment. The influence of bionic impeller factors, which are the amplitude, the interval and the phase, on cavitation performance is systematically studied. The area and volume of the blade cavitation pattern is used to characterize the blade cavitation performance. An efficient method of cavitation pattern recognition is proposed to determine the information of the blade cavitation pattern accurately. A feasible cavitation-adjustment method is proposed to improve the hydraulic performance by optimizing the cavitation distribution and strength.
Structure design on a new type of coupled impactor
Authors: Qiaolei Sun , Le Xia , Yuwei Liu , Long Deng
Published: March 2024

Improving drilling efficiency and reducing drilling cost are new challenges for deep drilling. Based on this, a coupling impactor is designed by applying the principle of hydraulic pulse pressurization and axial impact. Based on the impactor compression structure and principle, the fluid flow equation of the drilling fluid flowing through the compression mechanism and the mechanical balance equation of the piston body are established in order to study the pressure pulsation characteristics of the coupled impactor fluid.
Study on the Effect of SiO2 Content on the Properties of Epoxy Resin
Authors: Zhou Jiang , He Mingpeng , Zhang Yue , Huang Huixin , Yuan Yuan
Published: March 2024

With the development of energy layout in western China, the construction and operation of hydro-generator units in high-altitude and cold regions such as Tibet and Qinghai have increased rapidly, which puts forward stricter requirements for the insulation and anti-corona technology of high-altitude units. Improving the intrinsic properties of the matrix material is a highly efficient anti-corona method. In the paper, epoxy resin composites doped with different contents of micron silica were prepared. The effects of 0.5 wt%, 1 wt%, and 1.5 wt% SiO2 on the thermal conductivity, dielectric properties, and breakdown field strength of the matrix resin were researched. The results in this paper show that the doping of different contents of SiO2 has little effect on the thermal conductivity of the matrix resin, but improves the dielectric properties of the matrix resin to a certain extent. With the increase of SiO2 content, the breakdown field strength of the composites increased primarily and then decreased.
Adsorption performance of cellulose/chitosan microspheres for congo red
Authors: Du Yuanyuan , Fu Ying , Wang Ruixue , Dai Yanan , Zhang Kaili , Gao Xing
Published: March 2024

Cellulose is abundant in nature, and it has good biocompatibility and biodegradability. However, it has shortcomings such as insufficient ductility, poor solubility, and difficult in forming, which limits its further application in many fields, such as food and medicine. Cellulose/chitosan composite microspheres were prepared using carboxymethyl cellulose and chitosan as raw materials, anhydrous ethanol, and distilled water as coagulants by the crosslinking method. Fourier infrared spectroscopy (FT-IR), specific surface area and aperture test (BET), and scanning electron microscopy (SEM) were used to characterize the adsorption properties. The results showed that the adsorption rate of cellulose/chitosan was higher than that of a single substance. The maximum adsorption capacity of the cellulose/chitosan composite microsphere was 57.63 mg/g when the equilibrium was reached. Compared with single cellulose and chitosan, cellulose/chitosan composite microspheres had a better adsorption effect on Congo red. As a potential adsorption material, this material has shown good application value in the field of sewage treatment.
Study on the efficient selective oil absorption and recovery of hydrophobic chitosan aerogels
Authors: Liang Zeyi , Wang Yifei , Xu Jiangtao , Chen Kuiyong , Liu Yue
Published: March 2024

Chitosan (CS) aerogels were prepared by an ice templating method and their surfaces were then coated with reduced graphene oxide to form modified biodegradable CS (MCS) aerogels. The MCS aerogels retained the porous CS structure after modification. Based on the characteristics of high porosity and hydrophobicity, the MCS aerogels exhibited a highly selective absorption ability of oils from water. The oil absorption capacity of MCS aerogels could achieve 92.63 g g−1 for chloroform. In addition, the compressive strength of the MCS aerogels increases after modification, so they are recyclable. Therefore, the MCS aerogels could be a kind of green, biodegradable, efficient, and cost-effective absorbent for spilled oils.
Study on strength and toughness of FeCoCrNiAlx high entropy alloy
Authors: Ma Yuyang , Zhao Hui
Published: March 2024

This experiment analyzes the effects of Al content on the microstructure and mechanical properties of FeCoCrNiAlx high entropy alloy. We can observe that the high entropy alloy is FCC single-phase structure when the Al element content is low[1]. With the Al content increases, the alloy structure gradually changed from the FCC phase to a new phase composed of the FCC phase and BCC/B2 phase, and finally into the BBC single phase. The difficult element diffusion phenomenon and high entropy effect make the alloy form a simple solid solution structure. With the precipitation of the second phase, the properties of the alloy are strengthened[2]. After the Al element is gradually added to the alloy, the grain structure is refined, and fine crystal strengthening occurs. The experiment results show that with the increase of Al content, the mechanical properties of the alloy are significantly improved, and the tensile strength is increased from 358 MPa to 1265 MPa. Yield strength increased from 166 MPa to 878 MPa. Hardness increased from 1.4 Gpa to 4.22 Gpa. However, the fracture elongation of the alloy decreased from 51.3% to 12.2%.
Study on the influence of different molecular structure concrete slump retaining agents under high temperature
Authors: Guan Mengqin
Published: March 2024

In this paper, the free radical polymerization method was used to design different molecular structures of polycarboxylate slump-preserving agents. The effects of different functional monomers, acid-to-ether ratio, ester density, side chain length, and other factors on the dispersion and slump-retaining properties of concrete under high temperatures were compared and analyzed. The optimal process of high-temperature resistance was screened, before and after the alkali hydrolysis treatment, and the dispersing and retention performance of the slump-retaining agent was tested. The high-temperature slump-preserving agent was verified by gel chromatography and an infrared spectrum analyzer, which provided technical support for solving the rapid collapse of concrete in a high-temperature environment in summer.
Effect of heat treatment on the microstructure and mechanical properties of yttrium metal
Authors: Wang Shuang , Zhong Jiamin , Li Shuan , Zhang Xiaowei , Wang Zhiqiang , Yang Hongbo , Wu Daogao
Published: March 2024

Rare earth oxides prepared by magnetron sputtering of rare earth metal targets are ideal high k gate dielectric materials. The production of targets has drawn more and more attention. In this work, the yttrium (Y) metal target is subjected to cold rolling, resulting in an accumulated deformation of 40%. Subsequently, the deformed Y was heat-treated at various temperatures. Microstructural and mechanical characteristics of Y subjected to deformation and heat treatment were systematically examined utilizing an electron backscatter diffractometer and a hardness tester. The main coarse grains of rolled Y metal were replaced by fine grains with heat treatment temperatures of 550, 650, and 750 °C. Heat treated at 750 °C, grain size distribution was quite homogeneous and the grain growth was not obvious. As for recovery and recrystallization processes, the recovery process occurred after 450-°C heat treatment. And the recrystallized process is fully completed at 750 °C. Besides, the High-Angle Grain Boundaries (HAGB) fraction increased with a rise in heat treatment temperatures from 550 to 750 °C. The microhardness decreased with the heat treatment temperatures increased until 650 °C, then remained stable. This work can provide an important reference for the optimal heat treatment temperature of Y target materials.
First-principle calculations of sulfur dioxide adsorption on the palygorskite
Authors: Jia Weimin , Wang Yanbin , Ren Fang , Zhao Jinqin , Su Qiong , Lu Zhibin , Liang Junxi
Published: March 2024

This study uses the density functional theory (DFT) method of first-principle to provide theoretical guidance for a deeper understanding of the adsorption performance of palygorskite (PAL). An analysis was conducted to determine the optimal surface configurations and binding sites for SO2 on the PAL (100) surface. The results show that for the SO2/PAL adsorption system, the adsorption energies (-0.13 and -0.10 eV) and charge transfer amounts (0.017 and 0.029 e) at the top and bridge sites are greater than those at the hollow site (0.55 eV and 0.015 e), which determine the steadiest adsorption sites. Moreover, the fermi level is altered by orbitals in SO2, revealing interactions between SO2 and the (100) surface of PAL.
Surface morphology change in DLC: H coatings with gradient Cr under high temperature and high pressure
Authors: Ni Xinhua , Liu Qiongxi , Yu Jinfeng
Published: March 2024

The pressure influence of the surface morphology of DLC: H Coatings with gradient Cr (DCr) was studied by annealing in argon (HT effect) and HIPping (HT/HP effect). The results show that the voids formed on the HIPping annealed surface are rose-shaped with multi-layered edges but the edge of the voids formed on the argon annealed surface looks single-layered, and the composition of the coating surface is the same after HIPping and argon annealing. The Cr content at the bottom of the voids is higher in the HIPped surface than the argon annealed surface, and the voids formed in the HIPping annealed are relatively smaller but deeper than those in the argon. It is reasonable to deduce that the hydrogen release could have been restricted by the applied high compressive pressure on the surface.
Study on preparation technology of molybdenum-tungsten alloy with different tungsten content
Authors: Xi Sha , Zhu Qi , Chen Cheng , Wang Na , Zhou Sha , Yao Cheng , Zhang Xiao
Published: March 2024

The molybdenum-tungsten alloy rods with different tungsten content are prepared by powder metallurgy. The effects of different sintering processes on the density and microstructure of alloy rods are studied. The effects of different spinning forging processes on the yield and mass loss rate of alloy bars are also discussed. The results show that the optimum sintering processes of Mo-20W and Mo-50W alloys are 2150°C, 8 h, and 2200°C, 8 h respectively. Under the optimum sintering process, the relative density of the alloy rod reaches more than 98%. The microstructure is uniform and fine, and the grain of molybdenum tungsten alloy decreases gradually with the increase of W content. The optimum spinning forging processes of Mo-20W and Mo-50W alloys are 1280~1360°C and 1440~1520°C respectively. Under the optimum spinning forging processes, the yield of alloy bars reaches more than 92%, and the mass loss rate is reduced to 1.05~1.10%.
Denoising of laser cladding crack acoustic emission signals based on wavelet thresholding method.
Authors: Yang Hengliang , Zhang Jingli , Chen Jiaxin , Cai Hui , Jiao Yang , Wang Ming , Liu Eryong , Li Bo
Published: March 2024

Due to the influence of thermal stress and other factors during laser cladding, cracks will appear in the cladding layer. To reduce cladding loss, an effective method is to detect cracks early and adjust fusion parameters promptly. The paper utilized acoustic signal detection technology to collect crack defect signals during the laser cladding process. Subsequently, the collected acoustic signals were subjected to time-frequency analysis and wavelet thresholding denoising. Then by applying a custom thresholding approach for each level of wavelet coefficients, the crack signals were denoised. The results showed that this method achieved better denoising effects compared to other signal denoising methods and preserved the crack information to a greater extent, confirming the feasibility of the custom thresholding denoising approach. It helps to achieve online detection and acoustic signal analysis of cracks during the cladding process.
The study of the convergence conditions of the deep-learning method in the Li10GeP2S12 solid state electrolyte system
Authors: Peng Jie , Wang Liping
Published: March 2024

The ionic conductivity of solid-state electrolytes at room temperature is crucial for commercializing lithium-ion batteries with solid-state electrolytes. Ab initio methods encounter a challenge due to their substantial computational resource demands. Classical molecular dynamics methods, on the other hand, are suitable for large-scale systems with simulation times reaching the nanosecond scale. However, they rely on empirical parameters in force fields, limiting their use to systems with well-established and extensively validated parameters, which is a constraint in studying new materials. A simulation approach combines ab initio simulations and classical molecular dynamics. Deepmd-kit, a deep learning tool, trains a tailored force field model using ab initio simulation data for the target system. However, as an approximate method, its reliability must be compared with ab initio results. As a data-sensitive method, the amount of data required to achieve the desired accuracy varies for different systems and must be tested accordingly. This paper performs convergence training for system size and simulation time concerning Li10GeP2S12 solid-state electrolytes, establishing the convergence criteria for deep learning data in this system.
Study on the Preparation of a Polydiethylene Phenyl Phosphate Resin and its Adsorption of Cu2+ in Wastewater
Authors: Liu Ke , Liang Qiansheng , Li Yongsheng
Published: March 2024

In view of the problems and imperfections in the synthesis of phosphoric acid resins by existing techniques, we prepared a different phosphoric acid resin and used it to adsorb Cu2+ in wastewater. When phosphoric acid resin is prepared using cross-linked polydiethylbenzene resin as a matrix, the experimental raw material can be more selective and the experimental process is safe and non-toxic. The particle size of the synthesized resin is uniform, most of which are distributed in 100-300 μm, and the functional group content can be as high as 2.4 mmol/g. The static/dynamic adsorption on Cu2+ is excellent, with a static adsorption capacity of 51.2 mg/g. When hydrochloric acid is used as an eluant, the resin has favorable reproducibility, which provides a reference value for the preparation and application of phosphate resins.
A fluorescent CQDs for the Cu2+ detection in water
Authors: Liu Ying , Zhang Guangmei , Zhu Qiufeng
Published: March 2024

In order to obtain high efficiency and high precision fluorescent detection agent of trace metal ions in solution, the CQDs were optimized with citric acid, which acted as a carbon source, as well as urea, which acted as a nitrogen source. It was a carbon nanoparticle with a particle size of around 3.16 nm, featuring numerous functional groups attached to the surface. These attributes not only facilitated its dispersion within water but also conferred increased stability, thereby resulting in a more consistent fluorescence intensity. It was a fluorescent sensor that could successfully detect copper ions (Cu2+) in the range of 3-5 mM. First, we set the excitation wavelength to 380nm. Then, the quenched CQDs fluorescence intensity would be found, which was defined as the dynamic quenching of energy transfer caused by the binding of amine groups and Cu2+. CQDs were actually applied to detect Cu2+ in the concentration range 2-6 mM, with R2=0.9565. Thus, the CQDs had high practical application value for metal ion detection and alcohol sensing.
System design and prototyping of the CMS Level-1 Trigger at the High-Luminosity LHC
Authors: Williams T. ,   the CMS collaboration
Published: March 2024

For the High-Luminosity LHC (HL-LHC) era, the trigger and data acquisition system of the
CMS experiment will be entirely replaced. The HL-LHC CMS Level-1 Trigger system will consist of
approximately 200 ATCA boards featuring Xilinx UltraScale+ FPGAs connected by 25 Gb/s optical
links. These boards will process over 60 Tb/s of detector data within 9.5 μs of the
collision to select up to 750 kHz of events for readout. In this paper, we summarise the current
status of hardware tests, our progress on system integration tests, and the online software
designed to control and monitor these boards.
The result of simulation studies of a GEM-based TPC for the inner tracker of Super Charm-Tau Factory Detector at BINP
Authors: Vadakeppattu V.K. , Sokolov A.V.
Published: March 2024

The Super Charm Tau Factory (SCTF) is a newly proposed
electron-positron collider with an energy range of 2–7 GeV in the
center of the mass system and luminosity of about
1035 cm-2s-1, instrumented with Super Charm-Tau
Detector. The innermost part of the SCTD is the inner tracker
(IT). The main tasks of IT are the extension of the lever arm of the
drift chamber, detection of soft hadrons, and reconstruction of the
secondary particles that decay in the IT. The main candidates for IT
are silicon strip detectors, cylindrical MPGD detectors, and a time
projection chamber (TPC). This paper discusses the results of
simulation studies of the TPC detector in detail and the plans for
the inner tracker development.
Ising model on the aperiodic Smith hat
Authors: Okabe Yutaka , Niizeki Komajiro , Araki Yoshiaki
Published: March 2024

Smith et al discovered an aperiodic monotile of 13 sided shape in 2023. It is called the ‘Smith hat’ and consists of eight kites. We deal with the statistical physics of the lattice of the kites, which we call the ‘Smith-kite lattice’. We studied the Ising model on the aperiodic Smith-kite lattice and the dual Smith-kite lattice using Monte Carlo simulations. We combined the Swendsen–Wang multi-cluster algorithm and the replica exchange method. We simulated systems up to the total spin number

939
201

. Using the finite-size scaling (FSS) analysis, we estimated the critical temperature on the Smith-kite lattice as

T

c

/

J
=
2.405
±
0.0005

and that of the dual Smith-kite lattice as

T

c

∗

/

J
=
2.143
±
0.0005

. Moreover, we confirmed the duality relation between the critical temperatures on the dual pair of aperiodic lattices,

sinh
(
2
J

/

T

c

)
sinh
(
2
J

/

T

c

∗

)
=
1.000
±
0.001

. We also checked the duality relation for the nearest-neighbor correlation at the critical temperature, essentially the energy,

ϵ
(

T

c

)

/

coth
(
2
J

/

T

c

)
+
ϵ
(

T

c

∗

)

/

coth
(
2
J

/

T

c

∗

)
=
1.000
±
0.001

.
Electrowetting-on-dielectric behavior of aqueous droplets and gold nanofluid on an electrospun poly(vinyl chloride) microfiber layer
Authors: Budlayan Marco Laurence M , Patricio Jonathan N , Arco Susan D , Guerrero Raphael A
Published: March 2024

Morphology and wettability of dielectric layers are crucial properties that affect the electrowetting-on-dielectric (EWOD) performance of a working liquid. In this work, the use of a poly(vinyl chloride) (PVC) microfiber-modified PVC dielectric layer as an electrowetting-on-dielectric (EWOD) substrate is explored. Imaging with scanning electron and atomic force microscopy revealed intertwined microfibers on the original PVC film after PVC deposition via electrospinning. Hydrophobicity of the PVC layer was enhanced by the presence of microfibers, with the contact angle (CA) for a water droplet increasing from 84.9° to 123.9°. EWOD behavior of various liquids on the microfiber-modified PVC layer was investigated within a DC voltage range of 0 to 200 V DC. Gold nanofluid exhibited the largest change in CA of 57°, while smaller changes were observed for KOH (19.6°), KCl (21.2°), and water (21°). A mechanism explaining the observed reduction in contact angle for a gold nanofluid droplet is presented. Our results suggest the promising potential of PVC film-PVC microfiber as a hydrophobic dielectric material for EWOD applications involving diverse liquids, including gold nanofluids.
Effects of the presentation order of stimulations in sequential ERP/SSVEP Hybrid Brain-Computer Interface
Authors: Bekhelifi Okba , Berrached Nasr-Eddine , Bendahmane Amine
Published: March 2024

Hybrid Brain-Computer Interface (hBCI) combines multiple neurophysiology modalities or paradigms to speed up the output of a single command or produce multiple ones simultaneously. Concurrent hBCIs that employ endogenous and exogenous paradigms are limited by the reduced set of possible commands. Conversely, the fusion of different exogenous visual evoked potentials demonstrated impressive performances; however, they suffer from limited portability. Yet, sequential hBCIs did not receive much attention mainly due to slower transfer rate and user fatigue during prolonged BCI use (Lorenz et al 2014 J. Neural Eng. 11 035007). Moreover, the crucial factors for optimizing the hybridization remain under-explored. In this paper, we test the feasibility of sequential Event Related-Potentials (ERP) and Steady-State Visual Evoked Potentials (SSVEP) hBCI and study the effect of stimulus order presentation between ERP-SSVEP and SSVEP-ERP for the control of directions and speed of powered wheelchairs or mobile robots with 15 commands. Exploiting the fast single trial face stimulus ERP, SSVEP and modern efficient convolutional neural networks, the configuration with SSVEP presented at first achieved significantly (p < 0.05) higher average accuracy rate with 76.39% ( ± 7.30 standard deviation) hybrid command accuracy and an average Information Transfer Rate (ITR) of 25.05 ( ± 5.32 standard deviation) bits per minute (bpm). The results of the study demonstrate the suitability of a sequential SSVEP-ERP hBCI with challenging dry electroencephalography (EEG) electrodes and low-compute capacity. Although it presents lower ITR than concurrent hBCIs, our system presents an alternative in small screen settings when the conditions for concurrent hBCIs are difficult to satisfy.
Design and testing of an arc resistant power transformer with a reinforced turret
Authors: Johansson Joakim , Brodeur Samuel
Published: March 2024

This paper presents the design and testing of a full-scale 510-kV, 415-MVA HVDC converter transformer prototype designed to withstand the resulting pressure of a 20 MJ low-impedance fault in oil occurring inside a bushing turret, which is one of the major causes of transformer fires. In addition, there is currently few studies and recommendation regarding this failure mode, which is the main motivation for initiating this study. In total, two full-scale units were designed and built: First consisting of a reinforced turret and a transformer tank designed for arc resistance using nonlinear static finite-element analysis with design pressures retrieved from explicit dynamic simulations, and a second reference unit, with a conventional turret design. Both units were then experimentally tested with a methodology based on injecting pressurized air into the water-filled units, with test equipment dimensioned and calibrated to achieve a linear injection of energy equivalent to a 23 MJ arc in oil in 100 ms. The reinforced turret and transformer tank was able to contain the arc energy and performed as predicted by the nonlinear static and explicit dynamic simulations. The energy levels used in tests are, to our knowledge, the highest reported for a low-impedance fault occurring inside a turret, demonstrating the feasibility of designing a transformer to safely withstand mentioned faults without rupturing. The suggested reinforced turret is a robust and maintenance free solution offering passive protection against internal arcing, without the need of additional relive devices. It will significantly reduce the risk of fires, improve overall safety of the substation, and has the potential to be optimized for different arc energy levels and voltage class for turrets, cable boxes and chimneys.
Assessing the role of friction stir welding tool shoulder profile and parameters on mechanical performance of Al5083 weld joints pre- and post-corrosion exposure
Authors: Sunnapu Chendrasekhar , Kolli Murahari
Published: March 2024

Al5083 alloy sheets were joined by friction stir welding (FSW) by using three different tools having different shoulder profiles (flat, concave and convex) at three different tool rotational speeds. From the cross-sectional microstructures, weld joints obtained at 1120 rpm with three different shoulder profiles were observed as defect free. XRD analysis confirms the development of texture that was dominated with close packed planes. The weld joint mechanical performance was assessed by conducting tensile tests before and after exposing them to 3.5% NaCl solution for 24 h. Combination of concave shoulder profile with 1120 rpm tool rotational speed has given higher strength in the weld joint, compared with base alloy and the other weld joints. The weld joints produced by using flat and concave shoulder profiles exhibited higher mechanical strength even after corrosion attack compared with the base alloy. From the potentiodynamic polarization studies, the three defect free weld joints (processed at 1120 rpm) were measured with lower corrosion current density. The results demonstrate the promising role of FSW to retain the strength against the corrosion initiated mechanical failure of Al5083 alloy by selecting appropriate combination of the shoulder profile and welding parameters.
Integration Sessions
Authors: Brennan Bill , Belser Alex
Published: March 2024

Chapter 7 underscores the pivotal role of integration sessions in psychedelic therapy, where insights from medicine sessions are woven into the fabric of daily life. It presents the EMBARK model’s flexible, participant-centric approach to integration, focusing adaptively on the clinical domains that emerged for the participant. It provides guidelines and goals for the practitioner in selecting the most relevant goals for each participant within the six clinical domains. The chapter outlines a three-step process for integration: listening to understand the participant’s experience, setting actionable goals in the form of new attitudes and behaviors, and enacting these changes. It introduces the concept of three spheres of integration, including the innovative idea of participating in social change as a therapeutic growth avenue. The chapter also provides guidance on handling disappointing medicine session experiences, responding to challenging events, and managing serious adverse outcomes.