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Image-Based Flow Prediction of Vocal Folds Using 3D Convolutional Neural Networks

Journal of Bionic Engineering 2024年第2期21卷 991-1002页

作者： Yang Zhang Tianmei Pu Jiasen Xu Chunhua Zhou College of astronautics Nanjing University of Aeronautics and AstronauticsNanjing210016China College of Electrical Energy and Power EngineeringYangzhou UniversityYangzhou225127China College of aeronautics Nanjing University of Aeronautics and AstronauticsNanjing210016China

In this work,a three dimensional(3D)convolutional neural network(CNN)model based on image slices of various normal and pathological vocal folds is proposed for accurate and efficient prediction of glottal *** 3D CNN model is composed of the feature extraction block and regression *** feature extraction block is capable of learning low dimensional features from the high dimensional image data of the glottal shape,and the regression block is employed to flatten the output from the feature extraction block and obtain the desired glottal flow *** input image data is the condensed set of 2D image slices captured in the axial plane of the 3D vocal folds,where these glottal shapes are synthesized based on the equations of normal vibration *** output flow data is the corresponding flow rate,averaged glottal pressure and nodal pressure distributions over the glottal *** 3D CNN model is built to establish the mapping between the input image data and output flow *** ground-truth flow variables of each glottal shape in the training and test datasets are obtained by a high-fidelity sharp-interface immersed-boundary *** proposed model is trained to predict the concerned flow variables for glottal shapes in the test *** present 3D CNN model is more efficient than traditional Computational Fluid Dynamics(CFD)models while the accuracy can still be retained,and more powerful than previous data-driven prediction models because more details of the glottal flow can be *** prediction performance of the trained 3D CNN model in accuracy and efficiency indicates that this model could be promising for future clinical applications.

关键词： Vocal folds Computational fluid dynamics Machine learning 3D convolutional neural network

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An Aerial–Wall Robotic Insect That Can Land, Climb, and Take Off from Vertical Surfaces

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Research 2024年第1期2023卷 149-163页

作者： Qian Li Haoze Li Huan Shen Yangguang Yu Haoran He Xincheng Feng Yi Sun Zhiyuan Mao Guangming Chen Zongjun Tian Lida Shen Xiangming Zheng Aihong Ji College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjingChina College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjingChina State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjingChina

Insects that can perform flapping-wing flight,climb on a wall,and switch smoothly between the 2 locomotion regimes provide us with excellent biomimetic ***,very few biomimetic robots can perform complex locomotion tasks that combine the 2 abilities of climbing and ***,we describe an aerial–wall amphibious robot that is self-contained for flying and climbing,and that can seamlessly move between the air and *** adopts a flapping/rotor hybrid power layout,which realizes not only efficient and controllable flight in the air but also attachment to,and climbing on,the vertical wall through a synergistic combination of the aerodynamic negative pressure adsorption of the rotor power and a climbing mechanism with bionic adhesion *** the basis of the attachment mechanism of insect foot pads,the prepared biomimetic adhesive materials of the robot can be applied to various types of wall surfaces to achieve stable *** longitudinal axis layout design of the rotor dynamics and control strategy realize a unique cross-domain movement during the flying–climbing transition,which has important implications in understanding the takeoff and landing of ***,it enables the robot to cross the air–wall boundary in 0.4 s(landing),and cross the wall–air boundary in 0.7 s(taking off).The aerial–wall amphibious robot expands the working space of traditional flying and climbing robots,which can pave the way for future robots that can perform autonomous visual monitoring,human search and rescue,and tracking tasks in complex air–wall environments.

关键词： robot smoothly Vertical

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Experimental study on spray characteristics of aviation kerosene RP-3 in a radial rotary atomizer

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Acta Mechanica Sinica 2024年第7期40卷 66-79页

作者： Jing Hou Zhixin Zhu Chengbiao Ma Gaogfeng Wang Elsayed Barakat School of aeronautics and astronautics Zhejiang UniversityHangzhou 310027China

In this work,the spray behaviors of a rotary atomizer with round-shaped injection orifices are experimentally investigated to study the breakup mechanism and spray characteristics using RP-3 as the liquid *** breakup process of the liquid is visualized by the backlight shadow imaging method,which also provides the measurements of liquid breakup length and penetration *** injection mode of the liquid film is observed using the front-light illumination *** droplet size and distribution are measured using the laser particle size analyzer at various radial *** typical breakup modes are identified:the ligament breakup mode,bag breakup mode,and shear breakup *** Weber number(Wed)and momentum flux ratio(q)are used to elaborate the liquid breakup *** of droplet sizing indicate that the Sauter mean diameter decreases with a higher rotational speed and slightly varies with the volume flow rate.A correlation between liquid breakup modes and non-dimensional droplet size is established based on Wed and *** study presents some significance for understanding the impacts of the rotational speed and volume flow rates on the spray performance of actual aviation fuels in rotary atomizers.

关键词： Rotary atomizer Breakup mode Breakup length Droplet sizing

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Multi-scale collaborative design method for macroscopic thermal optimization and mesoscopic woven structure of hypersonic vehicle's TOCMC leading edge

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Chinese Journal of aeronautics 2024年第4期37卷 524-541页

作者： Chenwei ZHAO Zecan TU Junkui MAO Jian HUI Pingting CHEN College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 21016China Integrated Energy Institute Nanjing University of Aeronautics and AstronauticsNanjing 210016China

A new thermal protection design method for hypersonic vehicle's leading edge is proposed, which can effectively reduce temperature of the leading edge without additional cooling measures. This method reduces the leading-edge's temperature by the multi-scale collaborative design of the macroscopic thermal optimization and the mesoscopic woven structures of Three-dimensional Orthogonal Woven Ceramic Matrix Composites(TOCMC). The macroscopic thermal optimization is achieved by designing different mesoscopic woven structures in different regions to create combined heat transfer channels to dredge the heat. The combined heat transfer channel is macroscopically represented by the anisotropic thermal conductivity of TOCMC. The thermal optimization multiple linear regression model is established to optimize the heat transport channel, which predicts Theoretical Optimal Thermal Conductivity Configuration(TOTCC) in different regions to achieve the lowest leading-edge temperature. The function-oriented mesostructure design method is invented to design the corresponding mesostructure of TOCMC according to the TOTCC, which consists of universal thermal conductivity prediction formulas for TOCMC. These universal formulas are firstly derived based on the thermal resistance network method, which is verified by experiments with an error of 6.25%. The results show that the collaborative design method can effectively reduce the leading edge temperature by about 12.8% without adding cooling measures.

关键词： Multi-scale collaborative design Thermal optimization Ceramic matrix composite Hypersonic vehicle Thermal protection Intelligent optimization

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Novel high-safety aeroengine performance predictive control method based on adaptive tracking weight

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Chinese Journal of aeronautics 2024年第7期37卷 352-374页

作者： Qian CHEN Hanlin SHENG Jie ZHANG Jiacheng LI College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Increasing attention has been attracted to the dynamic performance and safety of advanced performance predictive control systems of the next-generation *** latest research demonstrates that Subspace-based Improved Model Predictive Control(SIMPC)can overcome the difficulty in solving the predictive model in MPC/NMPC ***,applying constant design parameters cannot maintain consistent control effects in all ***,the designed system relies too much on sensor-measured data,and thus it is difficult to thoroughly validate the safety of the system because of its high *** means that any potential hardware/software faults will endanger the ***,this paper first presents a novel nonlinear mapping relationship to adaptively tune the tracking weight online with the change of Power Lever Angle(PLA)and real-time relative tracking ***,without introducing additional design parameters,an Adaptive Tracking Weight-based SIMPC(ATW-SIMPC)controller is designed to improve the control performance in all operating states ***,a Primary/Backup Hybrid Control(PBHC)strategy with the ATW-SIMPC controller as the primary system and the traditional speed(Nf)controller as the backup system is proposed to ensure *** designed affiliated switching controller and the real-time monitor therein can be used to realize reasonable and smooth switching between primary/backup systems,so as to avoid bump *** PBHC system switches to the Nf controller when the ATW-SIMPC controller is wrong because of potential hardware/software faults;otherwise,the ATW-SIMPC controller keeps acting on the *** main results prove that the ATW-SIMPC controller with the optimal nonlinear mapping relationship,compared with the existing SIMPC controller,uplifts the dynamic control performance by 32%and reduces overshoots to an allowable limit,resulting in a better control effect in full *** comparison results consistently i

关键词： Aeroengine Model predictive control Hybrid system Adaptive weight Safety

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Research on the macro-and meso-mechanical properties of frozen sand mold based on Hertz-Mindlin with Bonding model

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Particuology 2024年第5期88卷 176-191页

作者： Jianpei Shi Zhongde Shan Haoqin Yang College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Material Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In this study,macro-and meso-mechanical properties of frozen sand molds were discussed based on the Hertz-Mindlin with Bonding(HMB)***-Burman,steepest ascent,and central composite designs were utilized to propose a parameter calibration *** effects of mesoscopic parameter variations on the compressive strength and average gradient of stress-strain were investigated through response surface method *** showed that the relative error between the simulated and measured repose angle is 3.1%under calibrated intrinsic contact *** compressive strength and average stress-strain gradient primarily depend on the normal and shear stiffness per unit area,as well as the particle size and porosity of the silica ***,taking load-displacement curves of three frozen sand molds with different geometric characteristics as the target value,the reliability and effectiveness of the frozen sand mold HMB model were verified through uniaxial compression tests and discrete element simulations.

关键词： Frozen sand mold Hertz-Mindlin with Bonding model Uniaxial compression test Discrete element method Mechanical properties

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Numerical investigation of dynamic characteristics of dual throat nozzle and bypass dual throat nozzle in thrust vectoring starting process

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Chinese Journal of aeronautics 2024年第10期37卷 184-206页

作者： Yuqi ZHANG Jinglei XU Minglei CAO Ruifeng PAN Shuai HUANG Key Laboratory of Inlet and Exhaust System Technology of Ministry of Education Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of Mechanics and Control of aeronautics and astronautics Structures Nanjing 210016China

The Bypass Dual Throat Nozzle(BDTN)is a novel fluidic Thrust Vectoring(TV)nozzle,it switches to TV state by opening the valve in the *** greatly manipulate the BDTN,the dynamic characteristics in the TV starting process should be *** paper conducts numerical simulations to grasp the variation processes of performances and the flow field evolution of BDTN and Dual Throat Nozzle(DTN).The dynamic responses of TV starting in typical DTN models are investigated at ***,the TV starting processes of BDTN in different Nozzle Pressure Ratio(NPR)conditions are simulated,and the valve opening durations(T)are also *** the expected TV direction is achieved in the DTN,the jet is deflected to the opposite direction at the beginning of the dynamic process,which is called the reverse TV ***,this phenomenon disappears in the *** larger injection width of DTN intensifies unsteady oscillations,and the reverse TV phenomenon is *** the BDTN,T determines the delay degree of performance variations compared to the static results,which is called hysteresis *** NPR=10,the hysteresis affects the final stable performance of *** study analyses the dynamic characteristics in DTN and BDTN,laying a foundation for further design of nozzles and control strategies.

关键词： Dual Throat Nozzle(DTN) Bypass Dual Throat Nozzle(BDTN) Dynamic characteristic Thrust vectoring starting process Cavity vortex Hysteresis effect

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Adaptive fault-tolerant control for non-minimum phase hypersonic vehicles based on adaptive dynamic programming

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Chinese Journal of aeronautics 2024年第3期37卷 290-311页

作者： Le WANG Ruiyun QI Bin JIANG State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

In this paper,a novel adaptive Fault-Tolerant Control(FTC)strategy is proposed for non-minimum phase Hypersonic Vehicles(HSVs)that are affected by actuator faults and parameter *** strategy is based on the output redefinition method and Adaptive Dynamic Programming(ADP).The intelligent FTC scheme consists of two main parts:a basic fault-tolerant and stable controller and an ADP-based supplementary *** the basic FTC part,an output redefinition approach is designed to make zero-dynamics stable with respect to the new ***,Ideal Internal Dynamic(IID)is obtained using an optimal bounded inversion approach,and a tracking controller is designed for the new output to realize output tracking of the nonminimum phase HSV *** the ADP-based compensation control part,an ActionDependent Heuristic Dynamic Programming(ADHDP)adopting an actor-critic learning structure is utilized to further optimize the tracking performance of the HSV control ***,simulation results are provided to verify the effectiveness and efficiency of the proposed FTC algorithm.

关键词： Hypersonic vehicle Fault-tolerant control Non-minimum phase system Adaptive control Nonlinear control Adaptive dynamic programming

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Deflagration and detonation induced by shock wave focusing at different Mach numbers

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Chinese Journal of aeronautics 2024年第2期37卷 249-258页

作者： Zezhong YANG Jun CHENG Bo ZHANG School of aeronautics and astronautics Shanghai Jiao Tong UniversityShanghai 200240China

Shock wave focusing is an effective way to create a hot spot or a high-pressure and hightemperature region at a certain place,showing its unique usage in detonation initiation,which is beneficial for the development of detonation-based *** flame propagation behavior after the autoignition induced by shock wave focusing is crucial to the formation and self-sustaining of the detonation *** this study,wedge reflectors with two different angles(60°and 90°)and a planar reflector are employed,and the Mach number of incident shock waves ranging from 2.0 to 2.8 is utilized to trigger different flame propagation *** pressure transducers and the high-speed schlieren imaging system are both employed to investigate the shock-shock collision and ignition *** results reveal a total of four flame propagation modes:deflagration,DDT(Deflagration-to-Detonation Transition),unsteady detonation,and direct *** detonation wave formed in the DDT and unsteady detonation mode is only approximately 75%-85%of the Chapman-Jouguet(C-J)speed;meanwhile,the directly induced detonation wave speed is close to the C-J *** waves,which are strong evidence for the existence of detonation waves,are discovered in *** usage of wedge reflectors significantly reduces the initial pressure difference ratio needed for direct detonation *** also provide a practical method for differentiating between detonation and deflagration modes,which involves contrasting the speed of the reflected shock wave with the speed of the theoretically nonreactive reflected shock *** findings should serve as a reference for the detonation initiation technique in advanced detonation propulsion engines.

关键词： Deflagration Detonation Hydrogen Ignition Shock wave focusing

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Calculation and Analysis of TVMS Considering Profile Shifts and Surface Wear Evolution Process of Spur Gear

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 136-150页

作者： Wenzheng Liu Rupeng Zhu Wenguang Zhou Jingjing Wang College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjingChina

Profile shift is a highly effective technique for optimizing the performance of spur gear transmission ***,tooth surface wear is inevitable during gear meshing due to inadequate lubrication and long-term *** profile shift and tooth surface wear(TSW)can impact the meshing characteristics by altering the involute tooth *** this study,a tooth stiffness model of spur gears that incorporates profile shift,TSW,tooth deformation,tooth contact deformation,fillet-foundation deformation,and gear body structure coupling is *** model efficiently and accurately determines the time-varying mesh stiffness(TVMS).Additionally,an improved wear depth prediction method for spur gears is developed,which takes into consideration the mutually prime teeth numbers and more accurately reflects actual gear meshing *** show that consideration of the mutual prime of teeth numbers will have a certain impact on the TSW ***,the finite element method(FEM)is employed to accurately verify the values of TVMS and load sharing ratio(LSR)of profile-shifted gears and worn *** study quantitatively analyzes the effect of profile shift on the surface wear process,which suggests that gear profile shift can partially alleviate the negative effects of *** contribution of this study provides valuable insights into the design and maintenance of spur gear systems.

关键词： Profile shift Tooth surface wear Structure coupling effect Improved wear depth prediction method TVMS

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