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Plasma characteristics and material erosion mechanism in multi-channel wire electrical discharge machining

Chinese Journal of Aeronautics 2024年第10期37卷 508-525页

作者： Guokang SU Chuanyun ZHANG Junfei LI Xiaolei CHEN Guixian LIU Yongjun ZHANG State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment Guangdong University of TechnologyGuangzhou 510006China Guangdong Key Laboratory of Advanced Manufacturing Technology of Marine Energy Equipment Guangdong University of TechnologyGuangzhou 510006China Guangzhou Key Laboratory of Nontraditional Machining Technology and Equipment Guangdong University of TechnologyGuangzhou 510006China School of Mechanical Engineering Xi’an Technological UniversityXi’an 710021China

Multi-channel wire electrical discharge machining(MC-WEDM)is an advanced and high-efficiency machining technology,but its material erosion mechanism remains *** this study,dual-channel wire electrical discharge machining was utilized as a case study to investigate the impact of the plunging current on both the plasma characteristics and material erosion under complex discharge *** analysis was conducted on the charged particles in the plasma,revealing that the plunging current can influence the trajectory of the plasma by modifying the selfmagnetic *** particle tracking method was employed to simulate the motion of electrons,revealing that in MC-WEDM,electrons exhibited a larger and more uniform *** evolution of the plasma within a single-pulse discharge was observed using high-speed photography technology,and the discharge signals collected from different channels were *** was observed that the plasma in MC-WEDM experienced more intense back-and-forth sweeping on the workpiece surface,facilitating the ejection of molten metal from the molten *** oscillating plasma exhibits a larger processing area and a more uniform distribution of energy,resulting in the formation of larger and shallower discharge ***,the influence of the amplitude and time point of the plunging current on the volume and area of the discharge craters was ***,MC-WEDM significantly reduced the occurrence of holes and micro-cracks and exhibited a thinner recast layer in the continuous discharge experiment.

关键词： Multi-channel WEDM Discharge observation Plunging current Plasma characteristics Material erosion Discharge crater

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Fatigue Crack Initiation and Propagation Dominated by Crystallographic Factors in TiB/near α-Ti Composite

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Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 763-776页

作者： Fanchao Meng Rui Zhang Shuai Wang Fengbo Sun Run Chen Lujun Huang Lin Geng School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Waikato Centre for Advanced Materials and Manufacturing School of EngineeringUniversity of WaikatoHamilton 3240New Zealand State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Discontinuously reinforced titanium matrix composites(DRTMCs)with a network structure have been extensively researched due to their superior combination of strength and ***,their fatigue performance has remained *** order to elucidate the fatigue behavior of DRTMCs,a tension-tension fatigue test was performed on a TiB/nearα-Ti composite with network *** results showed that the variability of fatigue lifetime increased as the stress level *** analysis indicated that fatigue crack initiation was associated with facet formation,while the subsequent propagation was hindered by the network structure comprising TiB whiskers and *** characterization further revealed that facets formed due to a combination of shear and normal *** reduction in fatigue lifetime was attributed to an increase in the effective slip length,which was influenced by the orientation of grains near the crack-initiation sites toward basal slip in the life-limiting *** in situ observation suggested that the crack initiation was facilitated by both basal and prismatic slip ofα-Ti as well as fracture of *** propagation was found to be associated with basal and prismatic slip systems with high Schmid factors,regardless of whether the crack was intergranular or intragranular.

关键词： Titanium matrix composite TiBw Fatigue lifetime variability Crack initiation Crack propagation

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Cubic S/N co-doped TiO_(2) with rich oxygen vacancies from Ti-MOFs for efficient elimination of formaldehyde

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Chinese Chemical Letters 2024年第2期35卷 512-515页

作者： Qing Gao Lei Sun Zhihua Wang Jiguang Deng State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory for Green Catalysis and Separation Key Laboratory of Beijing on Regional Air Pollution ControlKey Laboratory of Advanced Functional MaterialsEducation Ministry of ChinaDepartment of Chemical EngineeringBeijing University of TechnologyBeijing 100124China

The cubic S/N co-doped TiO_(2)(TNSx,x is the calcination temperature)photocatalysts with rich oxygen vacancies were obtained by high temperature calcination of sulfur powder and titanium-based MOFs NH_(2)-MIL-125 for the photocatalytic removal of gaseous formaldehyde(a volatile organic compound).Among the obtained catalysts,the presence of oxygen vacancies restricted photogenerated electron and holes recombination.98.00%removal of gaseous formaldehyde in 150 min could be achieved over TNS600 by xenon *** removal efficiency for formaldehyde was well retained for five cycle *** results from PL,TRPL and EIS revealed that TNS600 had the best separation efficiency of photogenerated electrons and holes,and the enhanced charge separation led to a significant increase in photocatalytic *** photocatalytic oxidation mechanism indicated that the ^(•)OH and ^(•)O_(2)−radicals were mainly involved in the efficient elimination of gaseous formaldehyde and were able to mineralize formaldehyde to H_(2)O and CO_(2).

关键词： Metal-organic frameworks Photocatalysis Formaldehyde removal S/N co-doped TiO_(2) Oxygen vacancies

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Defect chemistry and thermal conductivity of the εSmO_(1.5)·(1−ε)ZrO_(2)(0.2≤ε≤0.65)ceramics:Effect of the nonstoichiometry

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Journal of advanced Ceramics 2024年第11期13卷 1823-1834页

作者： Zhixue Qu Tong Zhang Wei Pan Key Laboratory of Advanced Functional Materials Education Ministry of ChinaCollege of Materials Science and EngineeringBeijing University of TechnologyBeijing 100124China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Rare-earth zirconate pyrochlores,which exhibit various interesting properties,especially low thermal conductivity,are of great *** is an effective strategy involving defect engineering to reduce the thermal conductivity of *** this work,a long series of solid solutions,εSmO_(1.5)·(1−ε)ZrO_(2)(ε=0.200,0.250,0.350,0.400,0.450,0.500,0.525,0.550,0.600,and 0.650),were designed and synthesized to investigate the effects of nonstoichiometry on the structural evolution,defect chemistry,and thermal conductivity of SmO_(1.5)–ZrO_(2) system across the entire pyrochlore phase field and phase transition *** similarity of all the Raman spectra provides an incredible opportunity to confirm the structural details and evolution of pyrochlore and defective fluorite,as well as the emergence of the expected point defects.A new solution mechanism concerning nonstoichiometry was proposed and confirmed by analyzing the variations in the experimental density and Raman *** thermal conductivities of all the samples were measured,and investigated in terms of the phonon-scattering *** results show that the nonstoichiometry with SmO1.5 excess is more effective in reducing the thermal conductivity to an extremely low value of approximately 1 W/(m·K),which can be attributed to the dramatic decrease in the average acoustic velocity in addition to the strong phonon scattering of Zr ion vacancies and oxygen *** the other hand,the nonstoichiometry with ZrO_(2) excess significantly reduces the thermal conductivity at room temperature,but conversely leads to a slight increase of it above 200°*** former variation can be attributed to the phonon scattering of the 8a interstitial oxygen ions,which has a similar effectiveness to the defects on the SmO1.5-rich *** latter variation may be attributed to the Umklapp scattering of phonons.

关键词： nonstoichiometry pyrochlore rare-earth zirconate thermal conductivity defect chemistry

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Hot deformation behavior and microstructure evolution of GH3536-TiB_(2) composites fabricated by powder metallurgy

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Science China(Technological Sciences) 2024年第7期67卷 2107-2124页

作者： ZHOU ShiPeng WANG Shuai HUANG LuJun ZHANG Rui CHEN Xin MENG FanChao CHEN Run SUN FengBo WANG CunYu GENG Lin School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Waikato Centre for Advanced Materials and Manufacturing School of EngineeringUniversity of WaikatoHamilton 3240New Zealand State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

The hot deformation behavior and microstructure evolution of GH3536-TiB2composites fabricated by powder metallurgy(PM)were examined in the temperature range of 950–1150℃ and strain rate range of 0.001–1 s^(-1). The hot compression stress-strain curves and the constitutive equation were obtained. In addition, the hot processing map was drawn, which indicated that the appropriate hot working window was 950–1050℃/0.001–0.1 s^(-1)and 1050–1100℃/0.001–0.01 s^(-1). The microstructure analysis showed that the splitting and spheroidization of M3B2led to a decrease in size and volume fraction at 950–1100℃. At 1150℃,the eutectic microstructure of M_(3)B_(2)+ γ was formed due to the dissolution of M_(3)B_(2), which caused macroscopic cracking of the deformed sample. Additionally, the deformation temperature and the strain rate had little effect on the size and volume fraction of M_(3)B_(2). Besides, discontinuous dynamic recrystallization(DDRX) and continuous dynamic recrystallization(CDRX) were found in the deformed microstructure, while the former was dominant. Within the test range of this work, the dynamic recrystallization(DRX) fraction of the deformed composites was high due to the bulging nucleation of numerous interfaces. The DRX grain size increased with increasing deformation temperature or decreasing strain rate. Texture analysis showed that the deformation texture of <101>//compression direction RD existed in the matrix when the deformation temperature was below 1100℃, and the texture type became <001>//RD at 1100℃. Additionally, it was also found that the <001>//RD texture was formed in M3B2under the strain rates of 0.1 and 0.01 s^(-1).

关键词： GH3536 alloy matrix composites powder metallurgy hot deformation behavior microstructure evolution

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Characteristics of the SOL ion-to-electron temperature ratio on the J-TEXT tokamak with different plasma configurations

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Plasma Science and technology 2024年第2期26卷 13-21页

作者：李存凯梁云峰江中和周松华建坤阳杰杨庆虎 Alexander KNIEPS Philipp DREWS 徐鑫毛飞越谢伟杨雨桐郭金龙李杨波任正康陈志鹏王能超 the J-TEXT Team International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China Forschungszentrum Jülich GmbH Institut für Energie-und Klimaforschung—PlasmaphysikPartner of the Trilateral Euregio Cluster(TEC)Julich 52425Germany 不详

Accurate measurement of the average plasma parameters in the edge region,including the temperature and density of electrons and ions,is critical for understanding the characteristics of the scrape-off layer(SOL) and divertor plasma transport in magnetically confined fusion *** the J-TEXT tokamak,a multi-channel retarding field analyzer(RFA) probe has been developed to study average plasma parameters in the edge region under various poloidal divertor and island divertor *** edge radial profile of the ion-to-electron temperature ratio,τ_(i/e),has been determined,which gradually decreases as the SOL ion self-collisionality,v_(SOL)*,*** is broadly consistent with what has been observed previously from various tokamak ***,the comparison of experimental results under different configurations shows that in the poloidal divertor configuration,even under the same v_(SOL)*,τ_(i/e) in the SOL region becomes smaller as the distance from the X-point to the target plate *** the island divertor configuration,τ_(i/e) near the O-point is higher than that near the X-point at the same v_(SOL)*,and both are higher than those in the limiter *** results suggest that the magnetic configuration plays a critical role in the energy distributions between electrons and ions at the plasma boundary.

关键词： ion temperature island divertor poloidal divertor retarding field analyzer(RFA)probe

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Development of spectral radiation imaging diagnostic systems for HFRC Device 5

Development of spectral radiation imaging diagnostic systems...

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2024 5th International Conference on Electrical, Electronic Information and Communication engineering, EEICE 2024

作者： Han, Cheng Cheng, Zhifeng Lin, Weijie Tian, Ye Zhang, Yuchen Rao, Bo Jin, Xinyi International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

Spectral radiation imaging diagnostic systems utilizing PDA (avalanche PhotoDiode Array) have been developed and deployed on the HFRC device (HUST Field Reversed Configuration Device). These systems are designed to measure Hα radiation imaging, plasma velocity, orientation, and shape. Their innovative features include higher spatial resolution, integrated system design, flexible measurement, and superior electronic performance. This paper discusses the selection of basic electronic circuits, circuit analysis, parameter design, and noise analysis in detail. The accuracy of the design is validated through simulation and practical testing. The final system parameters achieved a bandwidth of 610 kHz, low noise of 2.5 mV, approximately 3% system overshoot, and a rising time of 468.5 ns. Additionally, preliminary measurement results are provided. © Published under licence by IOP Publishing Ltd.

关键词： Flexible electronics

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Prediction of Contact Terminal Temperature of Vacuum Circuit Breaker under Complex and Unknown Boundary Conditions 7

Prediction of Contact Terminal Temperature of Vacuum Circuit...

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7th IEEE Conference on Energy Internet and Energy System Integration, EI2 2023

作者： Li, Yingzhuo Chen, Lixue Yuan, Zhao Xu, Shengqin Sun, Likang Zou, Xinyang School of Electrical and Electronic Engineering Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Technology Key Laboratory of Pulsed Power Technology Ministry of Education Wuhan China

ISBN: (纸本)9798350345094

The monitoring of contact terminal temperature of vacuum circuit breakers is of great significance for fault prediction, life assessment, and structural improvement of circuit breakers. This article proposes a prediction method for steady-state temperature of vacuum circuit breaker's contact based on RBF neural network. Firstly, a finite element simulation model based on the actual characteristics of ZKTD 2S00/36-31.5kV vacuum circuit breakers is built, according to which, 793 electromagnetic and thermal model samples of circuit breakers with different boundary conditions are generated. Then, Random Forest regression, LASSO regression and ReliefF regression are used to rank the importance of temperature measurement points at different locations, based on the ranking results from 3 regression models, 4 optimal temperature measuring points are obtained. While the actual boundary conditions of the vacuum circuit breaker are unknown, the contact terminal temperature is accurately predicted by only using the temperatures of four temperature measuring points and the contact resistance values. Finally, a control experiment was set up to further verify the predictive ability of multiple temperature measuring points for contact terminal temperature under complex and unknown boundary conditions. © 2023 IEEE.

关键词： Boundary conditions

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Design of the Reference Signal Generation Module in Standard Power Source 18th

Design of the Reference Signal Generation Module in Standard...

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18th Annual Conference of China Electrotechnical Society, ACCES 2023

作者： Zhengjie, Lin Junchang, Huang Dong, Li Dezhi, Chen Feitong, Zeng State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China China Electric Power Research Institute Wuhan430074 China

ISBN: (纸本)9789819710676

Nowadays, the operating power system has a characteristic called High-RE-PE, which represents "high proportion of renewable energy access" and "high proportion of power electronic equipment application". The characteristic increases the content and frequency of harmonics in the power grid, which poses a challenge to the measurement accuracy of traditional electricity measurement equipment. Due to the High-RE-PE of the power system, it’s necessary to use a wideband and high-precision standard power source to calibrate electricity measurement equipment. A typical standard power source usually consists of a reference signal generation module, a power amplification module and a sampling feedback module. The reference signal generation module is designed in this paper, including the scheme of the reference signal generation module, selection of digital to analog converter (DAC), design of the filter circuit and design of the basic program. Theoretically, the designed reference signal generation module can output fundamental wave with amplitude error less than 0.2%, and the amplitude error of high-order harmonics is less than 2%. The simulation result shows that the designed filter circuit meets the requirements of the standard power source, the amplitude error of the filter’s output less than 0.2% under various temperature conditions. © Beijing Paike Culture Commu. Co., Ltd. 2024.

关键词： Errors

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Three-dimensional fracture of UO_(2)ceramic pellets by phase field modeling

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Science China(Physics,Mechanics & Astronomy) 2025年第1期68卷 165-176页

作者： Wei Xiong Xuan Ye Hongzhang Cheng Xiaoming Liu Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Fracture is the primary failure type for the UO_(2)ceramic pellets,which are operated under irradiation and thermal processes,and physically confined by the *** this work,by combining closely coupled physical processes of heat conduction,heat transfer,and mechanical deformation with the cohesive phase field framework,we proposed a high-precision modeling of quasistatic cracking of three-dimensional(3D)UO_(2)ceramic fuel pellets under high temperature and *** simulation results agree well with the experimental results,indicating that the proposed method has the potential to capture 3D crack modes in the interested time ***,we studied the relation of the 3D fracture patterns of fuel pellets with the peak power *** was found that the power level plays a critical role in determining the competition between radial and circumferential cracks,as well as transverse penetrating cracks.

关键词： phase field method nuclear fuel pellet coupled thermo-mechanical model thermal fracture

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