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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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Observer-based dynamic event-triggered control for distributed parameter systems over mobile sensor-plus-actuator networks

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Chinese Physics B 2024年第4期33卷 237-243页

作者：穆文英庄波邱芳 Shandong Engineering Research Center of Aeronautical Materials and Devices Shangdong University of AeronauticsBinzhou 256600China School of Information Engineering Shangdong University of AeronauticsBinzhou 256600China School of Science Shangdong University of AeronauticsBinzhou 256600China

We develop a policy of observer-based dynamic event-triggered state feedback control for distributed parameter systems over a mobile sensor-plus-actuator *** is assumed that the mobile sensing devices that provide spatially averaged state measurements can be used to improve state estimation in the *** the purpose of decreasing the update frequency of controller and unnecessary sampled data transmission, an efficient dynamic event-triggered control policy is *** an event-triggered system, when an error signal exceeds a specified time-varying threshold, it indicates the occurrence of a typical *** global asymptotic stability of the event-triggered closed-loop system and the boundedness of the minimum inter-event time can be *** on the linear quadratic optimal regulator, the actuator selects the optimal displacement only when an event occurs.A simulation example is finally used to verify that the effectiveness of such a control strategy can enhance the system performance.

关键词： distributed parameter systems event-triggered control mobile sensors mobile actuators

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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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Effects of layer interactions on instantaneous stability of finite Stokes flows

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 69-84页

作者： Chen ZHAO Zhenli CHEN C.T.MUTASA Dong LI School of aeronautics Northwestern Polytechnical UniversityXi'an 710072China

The stability analysis of a finite Stokes layer is of practical importance in flow control. In the present work, the instantaneous stability of a finite Stokes layer with layer interactions is studied via a linear stability analysis of the frozen phases of the base flow. The oscillations of two plates can have different velocity amplitudes, initial phases, and frequencies. The effects of the Stokes-layer interactions on the stability when two plates oscillate synchronously are analyzed. The growth rates of two most unstable modes when δ 0.68. However, the interactions always have a stabilizing effect on the other unstable mode. It is explained that one of the two unstable modes has much higher dissipation than the other one when the Stokes-layer interactions are strong. We also find that the stability of the Stokes layer is closely related to the inflectional points of the base-flow velocity profile. The effects of inconsistent velocity-amplitude, initial phase, and frequency of the oscillations on the stability are analyzed. The energy of the most unstable eigenvector is mainly distributed near the plate of higher velocity amplitude or higher oscillation frequency. The effects of the initial phase difference are complicated because the base-flow velocity is extremely sensitive to the initial phase.

关键词： finite Stokes layer instantaneous stability Stokes-layer interaction asynchronous oscillation

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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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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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Optimal structural design for a certain near-space composite propeller of airship using adaptive region division blending model

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Chinese Journal of aeronautics 2024年第5期37卷 301-316页

作者： Weigang AN Tianyu LIN Shigen WANG School of aeronautics Northwestern Polytechnical UniversityXi’an 710072China

Near-space airship is a frontier and hotspot in current military research and development,and the near-space composite propeller is the key technology for its *** order to obtain higher aerodynamic efficiency at an altitude of 22 km,a certain near-space composite propeller is designed as a long and slender aerodynamic shape with a 10 m diameter,which brings many challenges to the composite structure *** initial design is obtained by the composite structure variable stiffness design method using based on fixed region division blending ***,it weighs 23.142 kg,exceeding the required 20 *** order to meet the structural design requirements of the propeller,a variable stiffness design method using the adaptive region division blending model is proposed in this *** with the methods using the fixed region division blending model,this method optimizes region division,stacking thickness and stacking sequence in a single level,considering the coupling effect among *** a more refined region division,this method can provide a more optimal design for composite tapered ***,to improve the efficiency of optimization subjected to manufacturing constraints,a hierarchical penalty function is proposed to quickly filter out the solutions that do not meet manufacturing *** above methods combined with a Genetic Algorithm(GA)using specific encoding are adopted to optimize the near-space composite *** optimal design of the structure weighs 18.831 kg,with all manufacturing constraints and all structural response constraints being *** with the initial design,the optimal design has a more refined region division,and achieves a weight reduction of 18.6%.This demonstrates that a refined region division can significantly improve the mechanical performance of the composite tapered structure.

关键词： Structural optimization Composite tapered structure Genetic algorithm Adaptive region division Manufacturing constraint Near-space composite propeller

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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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