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In-situ embedding CoTe catalyst into 1D-2D nitrogen-doped carbon to didirectionally regulate lithium-sulfur batteries

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Nano Research 2022年第10期15卷 8972-8982页

作者： Bin Li Peng Wang Baojuan Xi Ning Song Xuguang An Weihua Chen Jinkui Feng Shenglin Xiong key laboratory of Colloid and Interface Chemistry Ministry of EducationSchool of Chemistry and Chemical EngineeringState Key Laboratory of Crystal MaterialsShandong UniversityJinan 250100China Key Laboratory of Mechanical Engineering of Education School of Mechanical EngineeringChengdu UniversityChengdu 610106China key laboratory of Material Processing and Mold of Ministry of education Zhengzhou UniversityZhengzhou 450001China School of Materials Science and engineering Shandong UniversityJinan 250061China

Lithium-sulfur(Li-S)batteries have been widely investigated attributed to their advantages of high energy density and cost effectiveness.However,it is still limited by the uncontrolled shuttle effect of the sulfur cathode and the promiscuous dendrite growth over the lithium anode.To handle the above issues,the highly conductive CoTe catalyst is precisely loaded onto nitrogendoped nanotube and graphene-like carbon(CoTe NCGs),which is employed as a bi-functionally integrated host.On the lithium anode,the CoTe NCGs with excellent lithiophilic property effectively regulate the uniform deposition of lithium and achieve the effect of suppressing the disorderly growth of lithium dendrites.On the sulfur cathode,the electrochemical conversion of lithium polysulfides(LiPSs)is catalyzed to mitigate the notorious shuttle effect.In view of the bifunctionality of CoTe NCGs,the assembled full cell can be steadily stable even for 800 cycles at a high rate of 2 C,and the capacity decay rate is only 0.05%per cycle.The areal capacity of 6.0 mAh·cm^(−2) is well retained after 50 cycles under the conditions of high sulfur loading,poor electrolyte(a low electrolyte-to-sulfur ratio,E/S=4.2),and low negative to positive capacity ratio(N/P=1.6:1).

关键词： CoTe nanocrystals dual-functional shuttling effect lithium dendrite Li-S batteries

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Mode-localized accelerometer with ultrahigh sensitivity

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Science China(Information Sciences) 2022年第4期65卷 238-250页

作者： Hao KANG Bing RUAN Yongcun HAO Honglong CHANG Ministry of education key laboratory of Micro and Nano Systems for Aerospace School of Mechanical EngineeringNorthwestern Polytechnical University

The mode localization phenomenon is an effective technique to enhance sensor sensitivity,and some low noise floor mode-localized sensors,including accelerometers,mass sensors,and electrometers,have been successfully realized.To further improve the performance of the mode-localized accelerometer,we report a microelectromechanical system mode-localized accelerometer based on 4-degree of freedom (DoF) weakly coupled resonators (WCRs) with a stress-relief structure eliminating the thermal stress generated during the silicon-on-glass fabrication process.Experimental results show that compared with the state-of-the-art 3-DoF mode-localized accelerometer (4.40 g),the amplitude ratio-based sensitivity of the proposed accelerometer(119.36 V·g) is improved by 2612%.Moreover,the noise floor is 0.64μg·Hzfrom 0.01 to 3 Hz under the closed-loop circumstance.To the authors’best knowledge,this is the lowest measured noise floor for mode-localized accelerometers.

关键词： mode localization weakly coupled resonators accelerometer degree-of-freedom microe-lectromechanical system

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Recent progress in electric-field assisted combustion: a brief review

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Frontiers in Energy 2022年第6期16卷 883-899页

作者： Hecong LIU Weiwei CAI key laboratory of the Ministry of education for Power Machinery and engineering School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The control of combustion is a hot and classical topic.Among the combustion technologies,electric-field assisted combustion is an advanced technology that enjoys major advantages such as fast response and low power consumption compared with thermal power.However,its fundamental principle and impacts on the flames are complicated due to the coupling between physics,chemistry,and electromagnetics.In the last two decades,tremendous efforts have been made to understand electric-field assisted combustion.New observations have been reported based on different combustion systems and improved diagnostics.The main impacts,including flame stabilization,emission reduction,and flame propagation,have been revealed by both simulative and experimental studies.These findings significantly facilitate the application of electric-field assisted combustion.This brief review is intended to provide a comprehensive overview of the recent progress of this combustion technology and further point out research opportunities worth investigation.

关键词： electric field combustion flame stabilization emission reduction flame propagation

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Effects of process parameters on periodic impact force exerting on cutting tool in ultrasonic vibration-assisted oblique turning

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Advances in Manufacturing 2022年第3期10卷 411-427页

作者： Long-Xu Yao Zhan-Qiang Liu Qing-Hua Song Bing Wang Yu-Kui Cai School of mechanical engineering Shandong UniversityJinan 250061People's Republic of China key laboratory of High Efficiency and Clean mechanical Manufacture of Ministry of education/key National Demonstration Center for Experimental mechanical engineering education Jinan 250061People's Republic of China

During ultrasonic vibration-assisted machining,the large impact force induced by tool-workpiece reengagement(TWR)is an important factor that affects tool chipping.However,mechanical analysis into process factors that affect the impact force and their influencing mechanisms are insufficient.Herein,a prediction model for the instantaneous cutting force during both TWR and the stable turning process,which depends on the process parameters and material properties,is firstly proposed based on the kinematic and dynamic analysis of ultrasonic vibration-assisted oblique turning(UVAOT).The results calculated using the developed cutting force model agree well with the experimental results presented in the literature.Next,the linear change law of the instantaneous cutting force with cutting time during the actual TWR is clarified using the proposed model.The effect of the UVAOT process parameters on the average impact force during the periodic TWR process is discussed,and the influence mechanism is analyzed from the perspective of mechanics.A positive linear correlation is discovered between the feed speed and average impact force.The ultrasonic amplitude and cutting speed do not significantly affect the average impact force of the new sharp cutting tools.These findings are consistent with the experimental observations of tool chipping and are applicable to select process parameters for reducing tool chipping during UVAOT.

关键词： Kinematics Dynamics Ultrasonic vibrationassisted oblique turning(UVAOT) Impact force Cutting force

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Comparing Online Performance of EMG Pattern Recognition with and Without Joint Movements

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Journal of Bionic engineering 2023年第5期20卷 2135-2146页

作者： Lizhi Pan Kai Liu Jianmin Li key laboratory of Mechanism Theory and Equipment Design of Ministry of education School of Mechanical EngineeringTianjin UniversityTianjin300350China

Our previous study suggested that the subcutaneous muscle displacement caused by joint movements might alter muscle activation patterns and thus affect the classification performance.To further analyze the effect of joint movements on the online performance of Electromyography(EMG)Pattern Recognition(PR),this study assessed online classification performance with and without joint movements.EMG signals were recorded from the dominant forearm of 10 able-bodied subjects under two motion scenarios:Hand and Wrist Joints Unconstrained(HAWJU)and Constrained(HAWJC).Sixth-order autoregressive coefficients and four time-domain features were extracted from EMG signals.Linear Discriminant Analysis(LDA)models were trained to perform an online performance evaluation of the limb motions.The experimental results showed that the four online performance metrics:Motion Selection Time(MST),Motion Completion Time(MCT),Motion Completion Rate(MCR),and Online Classification Accuracy(ONCA)were 0.35 s,1.44 s,97.40%,and 82.61%for HAWJU and 0.37 s,1.47 s,89.70%,and 73.57%for HAWJC,respectively.The outcomes of this study indicated that subcutaneous muscle displacement due to joint movements has a positive effect on online classification performance.The absence of joint movements may be a physiological factor contributing to the poor online performance of the EMG-PR of transradial amputees.This study can provide a new perspective for improving the online performance of EMG-PR for transradial amputees.

关键词： Electromyography(EMG) Pattern recognition(PR) Joint movements Online performance

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Introducing Ce ions and oxygen defects into V_(2)O_(5)nanoribbons for efficient aqueous zinc ion storage

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Nano Research 2023年第2期16卷 2445-2453页

作者： Mingying Bao Zhengchunyu Zhang Xuguang An Jie Liu Jinkui Feng Baojuan Xi Shenglin Xiong key laboratory of Colloid and Interface Chemistry Ministry of EducationSchool of Chemistry and Chemical EngineeringState Key Laboratory of Crystal MaterialsShandong UniversityJinan 250100China Key Laboratory of Mechanical Engineering of Education School of Mechanical EngineeringChengdu UniversityChengdu 610106China key laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China School of Materials Science and engineering Shandong UniversityJinan 250061China

Cost-effectively,eco-friendly rechargeable aqueous zinc-ion batteries(AZIBs)have reserved widespread concerns and become outstanding candidate in energy storage systems.However,the progress pace of AZIBs suffers from limitation of suitable and affordable cathode materials.Herein,a double-effect strategy is realized in a one-step hydrothermal treatment to prepare V_(2)O_(5)nanoribbons with intercalation of Ce and introduction of abundant oxygen defects(Od-Ce@V_(2)O_(5))to enhance electrochemical performance synergistically.Coupled with the theoretical calculation results,the introduction of Ce ions intercalation and oxygen vacancies in V2O5 structure enhances the electrical conductivity,reduces the adsorption energy of zinc ions,enlarges the interlayer distance,renders the structure more stable,and facilitates rapid diffusion kinetics.As expected,the desirable cathode delivers the reversible capacity of 444 mAh·g^(−1)at 0.5 A·g^(−1)and shows excellent Coulombic efficiency,as well as an extraordinary energy density of 304.9 Wh·kg^(−1).The strategy proposed here may aid in the further development of cathode materials with stable performance for AZIBs.

关键词： double-effect Ce element doping oxygen defects Od-Ce@V_(2)O_(5) aqueous zinc-ion batteries

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A toolpath strategy for improving geometric accuracy in double-sided incremental sheet forming

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Chinese Journal of Aeronautics 2023年第1期36卷 468-479页

作者： Sattar ULLAH Xiaoqiang LI Peng XU Yanle LI Kai HAN Dongsheng LI School of mechanical engineering and Automation Beihang UniversityBeijing 100191China key laboratory of High Efficiency and Clean mechanical Manufacture Ministry of EducationSchool of Mechanical EngineeringShandong UniversityJinan 250061China

The double-sided incremental forming(DSIF)improved the process flexibility compared to other incremental sheet forming(ISF)processes.Despite the flexible nature,it faces the challenge of low geometric precision like ISF variants.In this work,two strategies are used to overcome this.First,a novel method is employed to determine the optimal support tool location for improving geometric precision.In this method,the toolpath oriented the tools to each other systematically in the circumferential direction.Besides,it squeezed the sheet by the same amount at the point of interest.The impacts of various support tool positions in the circumferential direction are evaluated for geometric precision.The results demonstrate that the support tool should support the master tool within 10°to its local normal in the circumferential direction to improve the geometric accuracy.Second,a two-stage process reduced the geometric error of the part by incrementally accommodating the springback error by artificially increasing the step size for the second stage.With the optimal support tool position and two-stage DSIF,the geometric precision of the part has improved significantly.The proposed method is compared to the best DSIF toolpath strategies for geometric accuracy,surface roughness,forming time,and sheet thickness fluctuations using grey relational analysis(GRA).It outperforms the other toolpath strategies including single-stage DSIF,accumulative double-sided incremental forming(ADSIF),and two-stage mixed double sided incre-mental forming(MDSIF).Our approach can improve geometric precision in complex parts by successfully employing the support tool and managing the springback incrementally.

关键词： incremental sheet forming double-sided incremental forming geometric accuracy springback grey relational analyses

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Comparing EMG Pattern Recognition with and Without Hand and Wrist Movements

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Journal of Bionic engineering 2022年第3期19卷 700-708页

作者： Lizhi Pan Kai Liu Kun Zhu Jianmin Li key laboratory of Mechanism Theory and Equipment Design of Ministry of education School of Mechanical EngineeringTianjin UniversityTianjin300072China

Electromyography(EMG)pattern recognition has been widely employed for prosthesis control.Several studies demonstrated that amputees had poorer performances of EMG pattern recognition when compared to able-bodied individuals.Several factors,such as the muscle weakness and atrophy of residual limbs,the length of residual limbs,and the decrease of the affected side's motor cortex,had been studied to improve the performance of amputees.However,there was no study on the factor that the absence of joint movements for amputees.This study aimed to investigate whether the hand and wrist joint movements had effects on the EMG pattern recognition.Ten able-bodied subjects were tested for 11 hand and wrist gestures with two different gesture modalities:hand and wrist joints unconstrained(HAWJU)and constrained(HAWJC).Time-domain(TD)features and Linear Discriminant Analysis(LDA)were employed to compare the classification performance of the two modalities.Compared to HAWJU,HAWJC significantly reduced the average Classification Accuracy(CA)across all subjects from 95.53 to 85.52%.The experimental results demonstrated that the hand and wrist joint movements had significant effects on EMG pattern recognition.The outcomes provided a new perspective to study the factors affecting EMG pattern recognition.

关键词： Electromyography(EMG) Pattern recognition Classification accuracy(CA) Joint movements

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Modified Coffin-Manson equation to predict the fatigue life of structural materials subjected to mechanical-thermal coupling non-coaxial loading

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Journal of Materials Science & Technology 2023年第29期160卷 118-127页

作者： Zhichao Ma Chaofan Li Wei Zhang Shenghui Wang Jiakai Li Hongwei Zhao Luquan Ren School of mechanical and Aerospace engineering Jilin UniversityChangchun 130025China key laboratory of CNC Equipment Reliability Ministry of EducationJilin UniversityChangchun 130025China key laboratory of Bionic engineering Ministry of education Jilin UniversityChangchun 130025China

With regard to the structures subjected to severe mechanical-thermal coupling fatigue conditions,the consistency between service conditions and loading conditions was the prerequisite for the fatigue prop-erties test and fatigue life prediction.A miniature piezoelectric-driven instrument integrating with a tripodal piezoelectric actuator and envelope-type heating function was developed to investigate the mechanical-thermal coupling fatigue properties and obtain the fatigue life of materials under approximate service conditions.A physical model was described to quantitatively calculate the alternating deformation under the mechanical-thermal coupling tensile-bending combined condition.Accordingly,a fatigue life prediction method based on the Coffin-Manson equation under tensile-bending combined loading was proposed to estimate the mechanical-thermal coupling fatigue life in terms of the total coupling defor-mation and plastic strain amplitude.The feasibility of the proposed instrument was verified through the analysis of displacement responses of high entropy alloy specimens under the thermal-mechanical cou-pling tensile-bending combined condition at temperatures ranging from RT to 600°C.The comparison between fatigue lives directly measured through thermal-mechanical coupling experiments and theoreti-cally predicted fatigue lives indicated the availability of the modified Coffin-Manson equation.

关键词： Fatigue testing instrument mechanical-thermal coupling Combined loading Fatigue life prediction odified Coffin-Manson equation

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A Bionic Stick–Slip Piezo-Driven Positioning Platform Designed by Imitating the Structure and Movement of the Crab

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Journal of Bionic engineering 2023年第6期20卷 2590-2600页

作者： Zhixin Yang Xuan Li Jinyan Tang Hu Huang Hongwei Zhao Yiming Cheng Shiwei Liu Chunyu Li Maoji Xiong key laboratory of CNC Equipment Reliability Ministry of EducationSchool of Mechanical and Aerospace EngineeringJilin UniversityChangchun130022JilinChina

By imitating the body structure and movement mode of the crab in nature,a novel stick–slip piezo-driven positioning platform was proposed by employing the bionic flexible hinge mechanism with a symmetrical structure and two piezoelectric stacks.The structural design and bionic motion principle were discussed,followed by analyzing the feasibility,safety,and output magnification ratio of the bionic flexible hinge mechanism via the stiffness matrix method and finite element simulation.To investigate the output performances of the positioning platform,a prototype was fabricated and an experiment system was established.Stepping characteristics of the positioning platform under various driving voltages were characterized,and the results indicated that the positioning platform could move steadily under various driving voltages.Within 1 s,the differences between the forward and reverse output displacement were less than 3%under different driving frequencies,proving the high bidirectional motion symmetry.The maximum driving speed of 5.44 mm/s was obtained under the driving voltage of 120 V and driving frequency of 5 Hz.In addition,the carrying load capacity of the positioning platform was tested by standard weights,and the results showed that when the carrying load reached 10 N,the driving speed could still reach 60μm/s.

关键词： Piezo-driven Stick–slip Bionic design Positioning platform Bidirectional motion symmetry

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