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Design method and experimental study of a cathode tool with an extremely high leveling ratio for electrochemical machining of blisk

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Chinese Journal of Aeronautics 2024年第4期37卷 593-608页

作者： Moqi shen Jia lIU Jingtao WANG Di ZHU College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

To obtain final parts with the desired dimensional accuracy and repeatability via electrochemical machining(ECM), the machining process must enter an ECM balanced state. However,for the ECM processing of blisk, a key component of aerospace engines, the surface of the blade blank often has an uneven allowance distribution due to the narrow passage of the cascade. It is difficult to remedy this issue in subsequent processing steps, which is necessary to ensure the dimensional accuracy and repeatability of the final blade profile. To solve this problem, electrolytic machining must be preceded by electrolytic shaping, which requires cathode tools with large leveling ratios to quickly homogenize the blank surface of the blade. In this study, to obtain a cathode tool with an extremely high leveling ratio, a design method based on the variation in the electrode gap in the non-equilibrium electrolytic state is proposed, and a dissolution model based on the nonequilibrium state is established. In this design method, the allowance on the blank to be machined is first divided into many discrete allowances with the normal direction. The initial machining clearance, feed rate, and total machining time are then calculated using classical ECM equilibrium state theory based on the maximum allowance. Meanwhile, the point coordinates of the cathode tool at maximum allowance can be determined. The non-equilibrium model can then be used to calculate the relative coordinate positions corresponding to the remaining discrete allowances. Finally, the entire cathode tool profile is designed. Simulations, fundamental experiments, and blisk unit workpiece experiments were carried out to validate the design approach. In the simulated processing of the plane workpiece, the leveling ratio of the cathode tool designed by the proposed method(0.77)was 83% higher than that of the cathode tool designed using the traditional method. The simulation results were confirmed by processing experiments. In t

关键词： Electrochemical machining(ECM) Non-equilibrium machining large leveling ratios Cathode design Finite element simulation Blisk

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Improving surface integrity of micro-holes in ECDM using ultrahigh-speed rotary of tool cathode and non-water-based electrolyte

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Chinese Journal of Aeronautics 2024年第5期37卷 506-519页

作者： Jiwen shen Weijing KONG Zhengyang XU yongbin ZENG Jiangsu Key laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The surface integrity of metal micro-hole structures produced by electrochemical discharge machining is unsatisfactory owing to the insufficient reaction area and strength of electrolysis action.A novel ultrahigh-speed Rotary Electrochemical Discharge Machining(R-ECDM)using non-water-based electrolyte is proposed to improve surface integrity by changing the breakdown medium of spark discharge and increasing the reaction area and strength of electrolysis.A mathematical model was developed to establish the relationship between rotational speed and forces acting on the *** on the magnitude of forces,controlling rotational speed changed the behavior and departure radius of bubbles on the cathode ***-speed photographs validate that,in the mathematical model,the number and departure radius of bubbles on the cathode surface gradually decrease with the increase of rotational *** experimental results show that the roughness(Ra)of the micro-hole sidewall decreases from 2.54μm to 0.20μm when the rotational speed increases from 500 r/min to 40000 r/*** length loss and wear ratio of the cathode are only 9.75μm and 6.5%,***,the micro-holes array with recast-free and surface roughness of 0.20μm is fabricated,demonstrating that the proposed approach contributes to improving surface integrity of metal micro-holes.

关键词： Electrochemical discharge machining Micro-holes Recast layer Ultrahigh-speed rotary Bubbles Force analysis Non-water-based solution

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Research Progress on Bionic Water Strider Robots

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Journal of Bionic Engineering 2024年第2期21卷 635-652页

作者： Jianhao liu Mingjun shen Ziqiang Ma Xinping Zhou School of Mechanical Science and Engineering Huazhong University of Science and TechnologyWuhan430074China State Key laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan430074China

Biological water striders have advantages such as flexible movement,low disturbance to the water surface,and low *** have developed a large number of biomimetic water strider robots based on their movement mechanism,which have broad application prospects in water quality testing,water surface reconnaissance,and *** article mainly reviews the research progress of biomimetic water strider ***,the biological and kinematic characteristics of water striders are outlined,and some mechanical parameters of biological water striders are *** basic equations of water strider movement are then ***,an overview is given of the past and current work on skating and jumping movements of biomimetic water strider robots based on surface tension and water pressure *** on the current research status of biomimetic water strider robots,the shortcomings of current research on biomimetic water striders are summarized,and the future development of biomimetic water strider robots is *** article provides new insights for the design of biomimetic water strider robots.

关键词： Bionics Water strider Robot Motion of robots on water surface

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Study on thermal decomposition kinetics of azobenzene-4,4′-dicarboxylic acid by using compensation parameter method and nonlinear fitting evaluation

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Chinese Journal of Chemical Engineering 2024年第6期70卷 269-279页

作者： Shuyi shen Song Guo Sining Chen Jinhua Zhao Nanjing University of Science&Technology Nanjing 210094China China Academy of Safety Science and Technology Beijing 100012China

Recently,azobenzene-4,4'-dicarboxylic acid(ADCA)has been produced gradually for use as an organic synthesis or pharmaceutical intermediate due to its eminent *** large quantities put into application in the future,the thermal stability of this substance during storage,transportation,and use will become quite ***,in this work,the thermal decomposition behavior,thermal decomposition kinetics,and thermal hazard of ADCA were *** were conducted by using a SENSyS evo DSC device.A combination of differential iso-conversion method,compensation parameter method,and nonlinear fitting evaluation were also used to analyze thermal kinetics and mechanism of ADCA *** results show that when conversion rate α increases,the activation energies of ADCA's first and main decomposition peaks *** amount of heat released during decomposition varies between 182.46 and 231.16 J·g^(-1).The proposed kinetic equation is based on the Avrami-Erofeev model,which is consistent with the decomposition *** the Frank-Kamenetskii model,a calculated self-accelerating decomposition temperature of 287.0℃is obtained.

关键词： Azobenzene-4,4′-dicarboxylic acid Thermal decomposition behavior Kinetic mechanism Thermal hazard evaluation Compensation parameter effect

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Transient Stability Analysis and Design of VSGs with Different DC-link Voltage Controllers

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 593-604页

作者： Chao shen Wei Gu Wanxing sheng Keyan liu School of Electrical Engineering Southeast UniversityNanjingChina Power Distribution Research Department China Electric Power Research InstituteBeijing 100192China

Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.

关键词： DC-link voltage dynamics equal area criterion(eac) transient synchronization stability virtual synchronous generator(VSG)

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Constitutive modelling of concrete material subjected to low-velocity projectile impact:insights into damage mechanism and target resistance

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第2期25卷 161-182页

作者： shen lIU Xieping HUANG Xiangzhen KONG Qin FANG Center for Hypergravity Experiment and Interdisciplinary Research Zhejiang UniversityHangzhou310058China Institute of Geotechnical Engineering Zhejiang UniversityHangzhou310058China State Key laboratory of Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing210007China

This paper presents a numerical study to improve the understanding of the complex subject of penetration and perforation of concrete targets impacted by low-velocity *** main focus is on the damage mechanisms and the major factors that account for the target resistance of the *** improved continuous surface cap model recently proposed was *** model was first equipped with element erosion criteria and was adequately validated by comparisons with ballistic *** numerical simulations were carried out where the individual influence of tensile,shear,and volumetric behaviors(pore collapse)of a concrete target on its ballistic performance was *** demonstrated that cratering on the front face and scabbing on the rear face of the concrete target were mainly dominated by its tensile *** major target resistance came from the second tunneling stage which was primarily governed by the shear and volumetric behaviors of the ***,this study captured the pore collapse-induced damage phenomenon during the high-pressure tunneling stage,which has been extensively reported in experiments but has usually been neglected in previous numerical investigations.

关键词： Penetration Perforation Damage mechanism Target resistance Projectile impact Pore collapse

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Motion Planning for Autonomous Driving with Real Traffic Data Validation

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 74-86页

作者： Wenbo Chu Kai yang shen li Xiaolin Tang Western China Science City Innovation Center of Intelligent and Connected Vehicle Chongqing 400044China College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing 400044China School of Civil Engineering Tsinghua UniversityBeijing 100084China

Accurate trajectory prediction of surrounding road users is the fundamental input for motion planning,which enables safe autonomous driving on public *** this paper,a safe motion planning approach is proposed based on the deep learning-based trajectory prediction *** begin with,a trajectory prediction model is established based on the graph neural network(GNN)that is trained utilizing the INTERACTION ***,the validated trajectory prediction model is used to predict the future trajectories of surrounding road users,including pedestrians and *** addition,a GNN prediction model-enabled motion planner is developed based on the model predictive control ***,two driving scenarios are extracted from the INTERACTION dataset to validate and evaluate the effectiveness of the proposed motion planning approach,i.e.,merging and roundabout *** results demonstrate that the proposed method can lower the risk and improve driving safety compared with the baseline method.

关键词： Trajectory prediction Graph neural network Motion planning INTERACTION dataset

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Recent progress of cobalt-based electrocatalysts for water splitting: Electron modulation, surface reconstitution, and applications

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Nano Research 2024年第4期17卷 2234-2269页

作者： Zhijian liang Di shen lei Wang Honggang Fu Key laboratory of Functional Inorganic Material Chemistry Ministry of Education of the People’s Republic of ChinaHeilongjiang UniversityHarbin 150080China

Electrocatalytic water splitting is an essential and effective means to produce green hydrogen energy structures,so it is necessary to develop non-precious metal catalysts to replace precious ***-based catalysts present effective alternatives due to the diverse valence states,adjustable electronic structures,and plentiful *** this review,the catalytic mechanisms of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)for electrocatalytic water splitting are ***,the synthesis strategies of various cobalt-based catalysts are systematically summarized,followed by the relationships between the structure and performance ***,the effects of d-band center and spin regulation for cobalt-based catalysts are also ***,the dynamic electronic and structural devolution of cobalt-based catalysts are elucidated by combining a series of in-situ ***,we highlight the challenges and future developed directions of cobalt-based catalysts for electrocatalytic water splitting.

关键词： cobalt-based electrocatalysts water splitting electron modulation surface reconfiguration

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Research on the evolutionary game of the supervision of civil aviation dangerous goods transportation training

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Transportation Safety and Environment 2024年第1期6卷 68-74页

作者： Haibin shen shengnan Zhao School of Safety Science and Engineering Civil Aviation University of ChinaTianjin 300300China

This study is carried out to promote the precise supervision of dangerous goods transportation training,improve the efficiency of civil aviation supervision and further ensure the safety of air ***,from the perspective of behaviour interaction and interest demands,evolutionary game theory is used to construct a tripartite evolutionary game model of dangerous goods transportation training institutions,the Civil Aviation Administration of China(CAAC)and the ***,the evolutionary game equilibrium of the system is further analysed under the joint action of the three ***,the influences of important parameters of the model on the behavioural strategy selection of the three parties are investigated via MATlAB numerical *** conclusions reveal that the system has three evolutionarily stable strategies under different parameters,namely(non-compliant training,supervision,non-participation in supervision),(non-compliant training,supervision,participation in supervision)and(compliant training,supervision,non-participation in supervision).Moreover,the CAAC supervision cost,the fine amount,the supervision cost of public participation,the supervision success rate and the reporting reward amount are the main parameters that affect the behavioural strategy selection of the tripartite game *** conclusions and suggestions of this study provide a decision-making basis and guidance for the supervision and management of civil aviation dangerous goods transportation training.

关键词： evolutionary game dangerous goods air transportation training supervision

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Highly selective electrosynthesis of 3,4-dihydroisoquinoline accompanied with hydrogen production over three-dimensional hollow CoNi-based microarray electrocatalysts

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Nano Research 2024年第4期17卷 2509-2519页

作者： yu Xin liyu Chen yingwei li Kui shen Guangdong Provincial Key lab for Green Chemical Product Technology School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou 510640China State Key laboratory of Pulp and Paper Engineering School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou 510640China

Electrocatalytic oxidation reaction of biomass-based derivatives is an excellent candidate to replace water oxidation for obtaining both value-added products and hydrogen(H_(2)),but the exploration of competent electrocatalysts is still highly ***,two new types of three-dimensional self-supported hollow microarrays containing CoNi layered double hydroxide(CoNi-lDH)and N-doped carbon nanosheets decorated with CoNi alloyed nanoparticles(CoNi-NC)on carbon cloth(CC)are prepared,which are further used as efficient electrocatalysts for tetrahydroisoquinoline(THIQ)electrooxidation and hydrogen evolution reaction(HER),*** demonstrate that the Co-modulated electronic environment for Ni(II)/Ni(Ⅲ)redox-looping in CoNi-lDH is the main factor to boost the selectivity of 3,4-dihydroisoquinoline(DHIQ)for the indirect electrooxidation process of *** functional theory(DFT)calculations reveal that the Ni(Ⅲ)/Co(Ⅲ)dual sites of CoNi-lDH exhibit enhanced adsorption for THIQ but poorer adsorption for DHIQ compared to pure Co(Ⅲ)or Ni(Ⅲ).Therefore,the Ni(Ⅲ)/Co(Ⅲ)dual sites can effectively inhibit the peroxidation of DHIQ to isoquinoline(IQ)over CoNi-lDH,thus improving the selectivity of DHIQ to nearly 100%,much higher than that of its pure Ni ***,CC@CoNi-NC can deliver high HER activity with low overpotential(40 mV@10 mA·cm^(-2))and high exchange current density(3.08 mA·cm^(-2)).Impressively,the assembled flow-cell device with CC@CoNi-lDH anode and CC@CoNi-NC cathode only requires low cell voltage and electricity consumption of 1.6 V and 3.50 kWh per cubic meter of H_(2)(@25 mA·cm^(-2)).

关键词： highly selective electrosynthesis dihydroisoquinolines hydrogen evolution reaction metal-organic frameworks hollow microarrays

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