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Low-temperature chemistry in plasma-driven ammonia oxidative pyrolysis

Green Energy & Environment 2024年第9期9卷 1477-1488页

作者： Mingming Zhang Qi Chen Guangzhao Zhou Jintao Sun He Lin School of mechanical Electronic and Control Engineering Beijing Jiaotong University School of mechanical engineering Shanghai Jiao Tong University

Ammonia is gaining increasing attention as a green alternative fuel for achieving large-scale carbon emission reduction. Despite its potential technical prospects, the harsh ignition conditions and slow flame propagation speed of ammonia pose significant challenges to its application in engines. Non-equilibrium plasma has been identified as a promising method, but current research on plasma-enhanced ammonia combustion is limited and primarily focuses on ignition characteristics revealed by kinetic models. In this study, low-temperature and low-pressure chemistry in plasma-assisted ammonia oxidative pyrolysis is investigated by integrated studies of steady-state GC measurements and mathematical simulation. The detailed kinetic mechanism of NH3decomposition in plasma-driven Ar/NH3and Ar/NH3/O2mixtures has been developed. The numerical model has good agreements with the experimental measurements in NH3/O2consumption and N2/H2generation, which demonstrates the rationality of modelling. Based on the modelling results, species density profiles, path flux and sensitivity analysis for the key plasmaproduced species such as NH2, NH, H2, OH, H, O, O（1D）, O2（a1△g）, O2（b1∑g+）, Ar*, H-, Ar+, NH3+, O2-in the discharge and afterglow are analyzed in detail to illustrate the effectiveness of the active species on NH3excitation and decomposition at low temperature and relatively higher E/N values. The results revealed that NH2, NH, H as well as H2are primarily generated through the electron collision reactions e + NH3→ e + NH2+ H, e + NH3→ e + NH + H2and the excited-argon collision reaction Ar*+ NH3+ H → Ar + NH2+ 2H, which will then react with highly reactive oxidative species such as O2*, O*, O, OH, and O2to produce stable products of NOx and H2O. NH3→ NH is found a specific pathway for NH3consumption with plasma assistance, which further highlights the enhanced kinetic effects.

关键词： Non-equilibrium plasma Ammonia fuel Oxidative pyrolysis Pathway flux analysis Sensitivity analysis

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Effect of Blood Circulation in Veins on Resonance Suppression of the Dragonfly Wing Constructed by Numerical Method

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Journal of Bionic engineering 2024年第2期21卷 877-891页

作者： Lijun Zhang Xu Zhang Kaifei Wang Zhenwei Gan Shibo Liu Xiao Liu Zhengjun Jing Xudong Cui Jiahui Lu Jing Liu College of mechanical and electronic engineering China University of PetroleumQingdao266580China

To reveal the resonance suppression mechanism of the blood circulation in dragonfly wings,a numerical modeling method of dragonfly wings based on Voronoi diagrams is proposed,and the changes in mass,aerodynamic damping,and natural frequencies caused by blood circulation in veins are *** equivalent mass of blood,boundary conditions,and aerodynamic damping are calculated *** analysis and harmonic response analysis of wing models with different blood circulation paths are performed using the finite-element method(FEM).The vibration reduction ratioδis introduced to compare the damping efficiency of different mass ***,a natural frequency testing device is constructed to measure the natural frequencies of dragonfly *** results indicate that the shape,mass,and natural frequencies of the dragonfly wing model constructed by numerical method agree well with *** mass distribution on the wing can be altered by blood circulation,thereby adjusting the natural frequencies and achieving resonance *** highestδof 1.013 is observed in the C region when blood circulates solely in secondary veins,but it is still lower than theδof 1.017 when blood circulates in complete *** aerodynamic damping ratio(1.19–1.79%)should not be neglected in the vibration analysis of the beating wing.

关键词： Dragonfly wings Blood circulation Resonance suppression Voronoi diagram FEM

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Ultrathin two-dimensional medium-entropy oxide as a highly efficient and stable electrocatalyst for oxygen evolution reaction

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Nano Research 2024年第4期17卷 2555-2562页

作者： Guangyuan Yan Tianlu Wang Biwei Zhao Wenjing Gao Tong Wu Liming Ou School of mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

Medium-entropy oxides(MEOs)with broad compositional tunability and entropy-driven structural stability,are receiving booming attention as a promising candidate for oxygen evolution reaction(OER)***,ultrathin two-dimensional(2D)nanostructure offers extremely large specific surface area and is therefore considered to be an ideal catalyst ***,it remains a grant challenge to synthesize ultrathin 2D MEOs due to distinct nucleation and growth kinetics of constituent multimetallic elements in 2D anisotropic *** this work,an ultrathin 2D MEO(MnFeCoNi)O was successfully synthesized by a facile and low-temperature ionic layer epitaxy *** from multi-metal synergistic effects within ultrathin 2D nanostructure,this 2D MEO(MnFeCoNi)O revealed excellent OER electrocatalytic performance with a quite low overpotential of 117 mV at 10 mA·cm^(-2) and an impressive stability for 120 h continuous operation with only 6.9%***,the extremely high mass activity(5584.3 A·g^(-1))was three orders of magnitude higher than benchmark RuO_(2)(3.4 A·g^(-1))at the same overpotential of 117 *** work opens up a new avenue for developing highly efficient and stable electrocatalysts by creating 2D nanostructured MEOs.

关键词： medium-entropy oxide two-dimensional nanomaterials ionic layer epitaxy oxygen evolution reaction electrocatalysis

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Multimode Design and Analysis of an Integrated Leg-Arm Quadruped Robot with Deployable Characteristics

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Chinese Journal of mechanical engineering 2024年第3期37卷 41-61页

作者： Fuqun Zhao Yifan Wu Xinhua Yang Xilun Ding Kun Xu Sheng Guo Xiaodong Jin School of mechanical engineering and Automation Beihang UniversityBeijing 100191China School of mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.

关键词： Quadruped robot Multimode design Mode switching Locomotion Operation

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Electrical discharge and arc milling with automatic tracking of optimal flushing direction:A novel high-efficiency compound machining method

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Chinese Journal of Aeronautics 2024年第3期37卷 351-364页

作者： Xinlei WU Yonghong LIU Pengxin ZHANG Liang QI Dege LI Chi MA Renjie JI College of mechanical and electronic engineering China University of Petroleum(East China)Qingdao 266580China School of mechanical and Power engineering Nanjing Tech UniversityNanjing 211816China

The arc milling method has the advantages of high machining efficiency and low cost and is independent of the strength and hardness of machined ***,frequent electrode back-offs and the risk of workpiece burning may occur if erosion products are not removed *** this study,it was found that the flushing method of the working medium had a significant impact on the machining performance of arc *** on this,a novel highefficiency compound machining method of electrical discharge and arc milling with automatic tracking of the optimal flushing direction was *** automatic tracking optimizer for external working medium injection was designed to determine the optimal external flushing direction according to the feed *** influence of flushing methods,working mediums,and machining parameters on the machining efficiency,tool electrode wear rate,machining error,and surface integrity of titanium alloys were *** results indicated that better machining performance and environmental friendliness were achieved using the compound flushing method of outer compressed air and inner deionized ***,the automatic tracking flushing method in the opposite direction of the feed direction showed superior results compared to other *** material removal rate with the opposite direction injection could be increased up to 1.62 times that of the same direction,and the relative electrode wear rate could be reduced by 14.76%.This novel method has broad application prospects for machining parts with difficult-to-cut materials in aerospace and military industries.

关键词： Arc milling Dielectric Difficult-to-cut materials Electric discharge machining Erosion Material removal rate

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Battery pack capacity estimation for electric vehicles based on enhanced machine learning and field data

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Journal of Energy Chemistry 2024年第5期92卷 605-618页

作者： Qingguang Qi Wenxue Liu Zhongwei Deng Jinwen Li Ziyou Song Xiaosong Hu College of mechanical and Vehicle engineering Chongqing UniversityChongqing 400044China School of mechanical and Electrical engineering University of Electronic Science and Technology of ChinaChengdu 611731SichuanChina Department of mechanical engineering National University of SingaporeSingapore 117575Singapore

Accurate capacity estimation is of great importance for the reliable state monitoring,timely maintenance,and second-life utilization of lithium-ion *** numerous works on battery capacity estimation using laboratory datasets,most of them are applied to battery cells and lack satisfactory fidelity when extended to real-world electric vehicle(EV)battery *** challenges intensify for large-sized EV battery packs,where unpredictable operating profiles and low-quality data acquisition hinder precise capacity *** fill the gap,this study introduces a novel data-driven battery pack capacity estimation method grounded in field *** proposed approach begins by determining labeled capacity through an innovative combination of the inverse ampere-hour integral,open circuit voltage-based,and resistance-based correction ***,multiple health features are extracted from incremental capacity curves,voltage curves,equivalent circuit model parameters,and operating temperature to thoroughly characterize battery aging behavior.A feature selection procedure is performed to determine the optimal feature set based on the Pearson correlation ***,a convolutional neural network and bidirectional gated recurrent unit,enhanced by an attention mechanism,are employed to estimate the battery pack capacity in real-world EV ***,the proposed method is validated with a field dataset from two EVs,covering approximately 35,000 *** results demonstrate that the proposed method exhibits better estimation performance with an error of less than 1.1%compared to existing *** work shows great potential for accurate large-sized EV battery pack capacity estimation based on field data,which provides significant insights into reliable labeled capacity calculation,effective features extraction,and machine learning-enabled health diagnosis.

关键词： Electricvehicle Lithium-ion battery pack Capacity estimation Machine learning Field data

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Influence of Mass Ratio of Resin and Stabilizer on mechanical Properties of Mo Fiber-reinforced Granite Polymer Composite

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Journal of Wuhan University of Technology(Materials Science) 2024年第4期39卷 912-920页

作者：张超任秀华 BA Dongzhe ZHANG Jianhua LI Jianyong GUO Mengnan GAO Yinghao WANG Guixin LI Jiayang School of mechanical and electronic engineering Shandong Jianzhu UniversityJinan 250101China Key Laboratory of High Efficiency and Clean mechanical Manufacture Ministry of Education of ChinaSchool of Mechanical EngineeringShandong UniversityJinan 250061China

Because inferior mechanical strength of granite polymer composite(GPC)has become the main drawback limiting its application and popularization,Mo fibers were added into(GPC)to improve its mechanical *** properties of matrix materials with different mass ratio of resin and stabilizer(MRRS)were investigated *** influences of MRRS on interface bonding strength of Mo fiber-matrix,wettability and mechanical strength of GPC were discussed,respectively,and the theoretical calculation result of MRRS k was obtained,with the optimal value of k=*** k=4,tensile strength,tensile strain and fracture stress of the cured resin achieve the maximum *** for k=7,the corresponding values reach the *** the increase of MRRS k,surface free energy of the cured resin first increases and then decreases,while contact angles between Mo sample and matrix have displayed the opposite *** of resin to Mo fiber is the best at k=*** load of Mo fiber and interface bonding strength appear the maximum at k=4,followed by k=5,k=3 the third,and k=7 the *** k=4,mechanical properties of Mo fiber-reinforced GPC are optimal,which is consistent with the result of theoretical *** study is of great significance to get better component formulas of Mo fiber reinforced GPC and to improve its application in machine tools.

关键词： polymer composite fiber mechanical strength interface bonding

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Effect of the yaw angle on turbulent flow structures around the submarine model

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Journal of Hydrodynamics 2024年第3期36卷 421-434页

作者： Yi-jing Hu Yi Qu Qin Wu Biao Huang School of mechanical engineering Beijing Institute of TechnologyBeijing100081China Beijing Institute of electronic System engineering Beijing100854China

The objective of this paper is to investigate the turbulent flow structures around the submarine model and evaluate the effect of the yaw angle on the turbulent flow *** large eddy simulation based on the boundary data immersion method is used to *** computational domain consists of 1.2×10^(8)uniformly distributed Cartesian orthogonal grid nodes to capture the basic flow characteristics around the *** pressure coefficient,friction coefficient and wake velocity distribution are in good agreement with the experimental *** different types of vortex structures were mainly captured around the model,including horseshoe vortex,sail tip vortex and crossflow separation *** the increase of the yaw angle,the asymmetry of the horseshoe vortex and the tip vortex gradually increases,and the vortex strength of the vortex leg on the windward of the horseshoe vortex and the vortex strength of the tip vortex also increase *** the crossflow separation vortex,the flow separation zone gradually expands and migrates downstream with the increase of the yaw angle.

关键词： Vortex structure submarine model boundary data immersion method yaw angle

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Combinatorial reasoning-based abnormal sensor recognition method for subsea production control system

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Petroleum Science 2024年第4期21卷 2758-2768页

作者： Rui Zhang Bao-Ping Cai Chao Yang Yu-Ming Zhou Yong-Hong Liu Xin-Yang Qi College of mechanical and electronic engineering China University of Petroleum BGP Inc. China National Petroleum Corporation

The subsea production system is a vital equipment for offshore oil and gas production. The control system is one of the most important parts of it. Collecting and processing the signals of subsea sensors is the only way to judge whether the subsea production control system is normal. However, subsea sensors degrade rapidly due to harsh working environments and long service time. This leads to frequent false alarm incidents. A combinatorial reasoning-based abnormal sensor recognition method for subsea production control system is proposed. A combinatorial algorithm is proposed to group sensors. The long short-term memory network(LSTM) is used to establish a single inference model. A counting-based judging method is proposed to identify abnormal sensors. Field data from an offshore platform in the South China Sea is used to demonstrate the effect of the proposed method. The results show that the proposed method can identify the abnormal sensors effectively.

关键词： Abnormal sensor Combinatorial algorithm Fault identification Subsea production control system

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Effects of ignition voltage and electrode structure on electric ignition and combustion characteristics of Ammonium Dinitramide(ADN)-based liquid propellants in electric ignition mode in inert gas environment

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Chinese Journal of Aeronautics 2024年第4期37卷 229-242页

作者： Lei LI Guoxiu LI Hongmeng LI Zhaopu YAO Tao ZHANG Jinze WU Shuo ZHANG School of mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Beijing Institute of Control engineering Beijing 100190China

Hydrazine is toxic and carcinogenic, which greatly increases the difficulty of application and no longer meets the needs of green aerospace. As a green propellant, the Ammonium Dinitramide(ADN)-based liquid propellant has the advantages of higher specific impulse, being non-toxic,pollution-free, and easy storage. However, an ADN-based space engine in orbit has exposed the problems of high-temperature deactivation of catalysts and cold-start failure. An active ignition technology—electric ignition technology was explored in this paper to break through the technical bottleneck of catalyst deactivation and the inability to a cold start. An experimental system of a constant-volume combustor for the ADN-based liquid propellant based on the electric ignition method was established. The electric ignition and combustion characteristics of the ADN-based liquid propellant in a volume combustor with an electric ignition method were studied. The influencing mechanisms of the ignition voltage and the electrode structure on the electric ignition characteristics of the ADN-based liquid propellant were investigated. An elevation of the ignition voltage could facilitate the ignition process of the ADN-based liquid propellant, curtail electric energy input and heating effect, while exerting an adverse impact on the combustion process of the *** increase in the ignition voltage enhanced the ignition process of the propellant while simultaneously suppressing its combustion process when utilizing mesh electrodes. Compared to the strip electrodes, the mesh electrodes increased the contact area between the electrodes and the propellant,increased the electric energy input power in the electric ignition process, and reduced the ignition delay time. The mesh electrodes could promote the combustion process of the propellant to a certain extent.

关键词： ADN-based liquid propellant Resistive ignition Electrical ignition characteristic Combustion Inert gas

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