Droplet impact dynamics on solid surfaces,which are ubiquitously present in aerospace engineering,energy systems,agricultural production,etc.,involve complex fluid–structure interactions.Herein,we employ a single-cam...Droplet impact dynamics on solid surfaces,which are ubiquitously present in aerospace engineering,energy systems,agricultural production,etc.,involve complex fluid–structure interactions.Herein,we employ a single-camera high-speed threedimensional digital image correlation system to quantify the full-field deformations of flexible thin films during droplet impact dynamics.Experimental results revealed that the substrate flexibility not only reduces the maximum spreading diameter by 10%but also modulates rebound dynamics via energy competition between kinetic energy and surface adhesion energy,suggesting that coupled deformation of the solid–fluid interface plays an important role in the dynamic progress.We propose the structure-coupled response number(Sn),a governing dimensionless parameter unifying droplet spreading on both rigid and flexible films,validated by a universal 1/2 scaling law.A theoretical criterion for droplet rebound on hydrophobic flexible thin films is derived and experimentally demonstrated,which achieves the precise control of droplet rebound/non-rebound mode.This work bridges the theories of droplet impact dynamics on rigid and flexible substrates,offering a robust strategy to govern the droplet impact behaviors.展开更多
Reusable and flexible capturing of space debris is highly required in future aerospace technologies.A tendon-actuated flexible robotic arm is therefore proposed for capturing floating targets in this paper.Firstly,an ...Reusable and flexible capturing of space debris is highly required in future aerospace technologies.A tendon-actuated flexible robotic arm is therefore proposed for capturing floating targets in this paper.Firstly,an accurate dynamic model of the flexible robotic arm is established by using the absolute nodal coordinate formulation(ANCF)in the framework of the arbitrary Lagrangian-Eulerian(ALE)description and the natural coordinate formulation(NCF).The contact and self-contact dynamics of the flexible robotic arm when bending and grasping an object are considered via a fast contact detection approach.Then,the dynamic simulations of the flexible robotic arm for capturing floating targets are carried out to study the influence of the position,size,and mass of the target object on the grasping performance.Finally,a principle prototype of the tendon-actuated flexible robotic arm is manufactured to validate the dynamic model.The corresponding grasping experiments for objects of various shapes are also conducted to illustrate the excellent performance of the flexible robotic arm.展开更多
The quantity of space debris on Earth orbit has escalated tremendously in recent years, presenting a significant hazard to human space operations. It is urgent to develop effective measures to capture and remove vario...The quantity of space debris on Earth orbit has escalated tremendously in recent years, presenting a significant hazard to human space operations. It is urgent to develop effective measures to capture and remove various space debris. For this purpose, this paper presents a tendon-actuated flexible deployable manipulator. The flexible manipulator consists of several deployable units connected by Cardan joints and actuated by tendons. Compared with the present technologies for capturing space debris such as rigid robotic arm or flying net, this flexible manipulator is deployable, reusable, lightweight and applicable to the capture of large space debris. In order to investigate its deployment dynamics, an accurate dynamic model of the flexible manipulator is established based on the natural coordinate formulation (NCF) and the absolute nodal coordinate formulation (ANCF). Subsequently, numerical simulations are carried out to study the effects of system parameters and the base satellite on its deployment dynamics. Finally, ground experiments for both deployment and bending of the flexible manipulator are conducted to verify its effectiveness and feasibility.展开更多
To meet the demand for the machining of blisks with narrow cascade channels and twisted blade profiles,especially integral shrouded blisks with shrouds,this paper innovatively proposes a method for dynamic deformation...To meet the demand for the machining of blisks with narrow cascade channels and twisted blade profiles,especially integral shrouded blisks with shrouds,this paper innovatively proposes a method for dynamic deformation electrochemical cutting of flexible electrodes with arrayed group slit structure.By applying torque to both ends of the flexible electrode,the proposed method produces bending deformation and realizes the processing of a twisted profile.The flexible electrode is an important carrier of this method,and its properties such as elasticity,rigidity,and flow field uniformity have a crucial impact on smooth processing.Therefore,this paper proposes a design theory of flexible electrodes with an arrayed group slit structure and designs flexible electrodes with variable cross-sections.Compared with traditional uniform section tube electrode,the designed flexible electrode was subjected to the corresponding mechanical simulation,flow field simulation,and fluid–structure interaction simulation to investigate the elasticity,rigidity,and flow field uniformity of the flexible electrode.In addition,a deformation device of flexible electrodes was constructed and the corresponding experiments were carried out.Simulations and experiments demonstrate that flexible electrodes with arrayed group slit structures have good comprehensive performance.Finally,typical components were successfully machined to verify the feasibility of the proposed method and the rationality of the designed flexible electrode.It is shown that the proposed method has great potential for the machining of distorted profiles and provides a new idea for the machining of complex profiles.展开更多
We propose a simplified version of the classic two-dimensional Hindmarsh–Rose neuron(2DHR),resulting in a new 2DHR that exhibits novel chaotic phenomena.Its dynamic characteristics are analyzed through bifurcation di...We propose a simplified version of the classic two-dimensional Hindmarsh–Rose neuron(2DHR),resulting in a new 2DHR that exhibits novel chaotic phenomena.Its dynamic characteristics are analyzed through bifurcation diagrams,Lyapunov exponent spectra,equilibrium points,and phase diagrams.Based on this system,a corresponding circuit is designed and circuit simulations are carried out,yielding results consistent with the numerical simulations.To explore practical applications of chaotic systems,2DHR is employed to improve the solution of the flexible job-shop scheduling problem with dynamic events.The research results demonstrate that applying 2DHR can significantly enhance the convergence rate of the optimization algorithm and improve the quality of the scheduling solution.展开更多
Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging becaus...Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.展开更多
Intelligent production is an important development direction in intelligent manufacturing,with intelligent factories playing a crucial role in promoting intelligent production.Flexible job shops,as the main form of in...Intelligent production is an important development direction in intelligent manufacturing,with intelligent factories playing a crucial role in promoting intelligent production.Flexible job shops,as the main form of intelligent factories,constantly face dynamic disturbances during the production process,including machine failures and urgent orders.This paper discusses the basic models and research methods of job shop scheduling,emphasizing the important role of dynamic job shop scheduling and its response schemes in future research.A multi-objective flexible job shop dynamic scheduling mathematical model is established,highlighting its complex and multi-constraint characteristics under different interferences.A classification discussion is conducted on the dynamic response methods and optimization objectives under machine failures,emergency orders,fuzzy completion times,and mixed dynamic events.The development process of traditional scheduling rules and intelligent methods in dynamic scheduling are also analyzed.Finally,based on the current development status of job shop scheduling and the requirements of intelligent manufacturing,the future development trends of dynamic scheduling in flexible job shops are proposed.展开更多
The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich i...The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich in deep-sea polymetallic nodules.These nodules,which are nodular and unevenly distributed in seafloor sediments,have significant industrial exploitation value.Over the decades,the deep-sea mining industry has increasingly adopted systems that combine rigid and flexible risers supported by large surface mining vessels.However,current systems face economic and structural stability challenges,hindering the development of deep-sea mining technology.This paper proposes a new structural design for a deep-sea mining system based on flexible risers,validated through numerical simulations and experimental research.The system composition,function and operational characteristics are comprehensively introduced.Detailed calculations determine the production capacity of the deep-sea mining system and the dimensions of the seabed mining subsystem.Finite element numerical simulations analyze the morphological changes of flexible risers and the stress conditions at key connection points under different ocean current incident angles.Experimental research verifies the feasibility of collaborative movement between two tethered underwater devices.The proposed deep-sea mining system,utilizing flexible risers,significantly advances the establishment of a commercial deep-sea mining system.The production calculations and parameter determinations provide essential references for the system’s future detailed design.Furthermore,the finite element simulation model established in this paper provides a research basis,and the method established in this paper offers a foundation for subsequent research under more complex ocean conditions.The control strategy for the collaborative movement between two tethered underwater devices provides an effective solution for deep-sea mining control systems.展开更多
Flexible microporous metal rubber(FMP-MR)is widely used in national defense applications,yet its mechanical behavior under high-speed impact conditions remains insufficiently explored.In this study,dynamic and static ...Flexible microporous metal rubber(FMP-MR)is widely used in national defense applications,yet its mechanical behavior under high-speed impact conditions remains insufficiently explored.In this study,dynamic and static experiments were conducted to systematically investigate the mechanical response of metal-wrapped microporous materials under impact loading that spanned 10~6 orders of magnitude.By combining a high-precision numerical model with a spatial contact point search algorithm,the spatio–temporal contact characteristics of the complex network structure in FMP-MR were systematically analyzed.Furthermore,the mapping mechanism from turn topology and mesoscopic friction behavior to macroscopic mechanical properties was comprehensively explored.The results showed that compared with quasi-static loading,FMP-MR under high-speed impact exhibited higher energy absorption efficiency due to high-strain-rate inertia effect.Therefore,the peak stress increased by 141%,and the maximum energy dissipation increased by 300%.Consequently,the theory of dynamic friction locking effect was innovatively proposed.The theory explains that the close synergistic effect of sliding friction and plastic dissipation promoted by the stable interturn-locked embedded structure is the essential reason for the excellent dynamic mechanical properties of FMP-MR under dynamic loading conditions.Briefly,based on the in-depth investigation of the mechanical response and energy dissipation mechanism of FMP-MR under impact loads,this study provides a solid theoretical basis for further expanding the application range of FMP-MR and optimizing its performance.展开更多
This work reviews models and methods for determining the dynamic response of pavements to moving vehicle loads in the framework of continuum-based three dimensional models and linear theories.This review emphasizes th...This work reviews models and methods for determining the dynamic response of pavements to moving vehicle loads in the framework of continuum-based three dimensional models and linear theories.This review emphasizes the most representative models and methods of analysis in the existing literature and illustrates all of them by numerical examples.Thus,13 such examples are presented here in some detail.Both flexible and rigid(concrete)pavement models involving simple and elaborate cases with respect to geometry and material behavior are considered.Thus,homogeneous or layered half-spaces with isotropic or cross-anisotropic and elastic,viscoelastic or poroelastic properties are considered.The vehicles are modeled as simple point or distributed loads or discrete spring-mass-dashpot system moving with constant or variable velocity.The dynamic response of the above pavement-vehicle systems is obtained by analytical/numerical or purely numerical methods of solution.Analytical/numerical methods have mainly to do with Fourier transforms or complex Fourier series with respect to both space and time.Purely numerical methods involve the finite element method(FEM)and the boundary element method(BEM)working in time or frequency domain.Critical discussions on the advantages and disadvantages of the various pavement-vehicle models and their methods of analysis are provided and the effects of the main parameters on the pavement response are determined through parametric studies and presented in the examples.Finally,conclusions are provided and suggestions for future research are made.展开更多
The demand for sensors capable of operating in extreme environment of the fields,such as aerospace vehicles,aeroengines and fire protection,is rapidly increasing.However,developing flexible ceramic fibrous pressure se...The demand for sensors capable of operating in extreme environment of the fields,such as aerospace vehicles,aeroengines and fire protection,is rapidly increasing.However,developing flexible ceramic fibrous pressure sensors that combine high temperature stability with robust mechanical properties remains a significant challenge.Herein,through precise multi-scale process control,high-strength(2.1 MPa)TiC-SiC flexible fibrous membrane is successfully fabricated.The membrane exhibits exceptional thermal resistance(2000℃)and long–term thermal stability(1800℃ for 5 h)in the inert atmosphere.Meanwhile,the TiC-SiC fibrous membrane shows excellent oxidation resistance and still achieves strength of 1.8 MPa after being oxidized at 1200℃ for 1 h in air.Remarkably,TiC-SiC fibrous membrane withstands a load of approximately 1400 times its own weight and the ablation of butane flame(~1300℃)for at least 1 h without breaking.Notably,after heat treatment at 1800℃ for 5 h in an argon atmosphere,the TiC-SiC fibrous membrane even sustains pressure–sensing performance for up to 300 cycles.The membrane exhibits stable resistivity up to 900℃ and shows sensing stability under butane flame.The results of this work provide an effective and feasible solution to fill the research gap of flexible fibrous sensors for extreme environments.展开更多
Driven by the burgeoning demand for wearable electronics,the development of inherently safe,mechanically compliant,and high-energy–density power sources has become imperative.Flexible aqueous Zn ions batteries(FAZIBs...Driven by the burgeoning demand for wearable electronics,the development of inherently safe,mechanically compliant,and high-energy–density power sources has become imperative.Flexible aqueous Zn ions batteries(FAZIBs)are hampered by Zn dendrite formation and hydrogen evolution,underscoring the urgent need for highly stable and novel flexible energy-storage devices.Although flexible aqueous cobalt-ion batteries(FACIBs)employing cobalt-salt aqueous electrolytes exhibit high theoretical capacity,they suffer from two limitations:the rapid dissolution of cathode active substances in the aqueous electrolyte and the risk of liquid electrolyte leakage under mechanical deformation.Here,we report the first realization of an ultra-stable,quasi-solid-state and mechanically FACIBs.Polyacrylamide(PAM)containing CoSO_(4) serves as the quasi-solid electrolyte,while cobalt hexacyanoferrate(CoHCF)functions as the cathode active material,and metallic cobalt foil as the flexible anode.This configuration simultaneously eliminates electrolyte leakage and suppresses the dissolution of CoHCF due to the common-ion effect of Co^(2+).Consequently,the fabricated FACIBs exhibit extraordinary cycling durability and remarkable mechanical robustness(95.9%retention after 500 bending cycles).Thus,this work provides a new way for designing ultra-stable energy storage devices for wearable electronics.展开更多
In the future power-electronics-dominated power systems,grid-forming(GFM)converters have been regarded as important devices to actively establish frequency and voltage,so as to provide essential grid support.However,d...In the future power-electronics-dominated power systems,grid-forming(GFM)converters have been regarded as important devices to actively establish frequency and voltage,so as to provide essential grid support.However,due to their voltage source behavior and emulated swing dynamics,GFM converters may encounter low-frequency oscillations(LFOs)when connected to strong grids,which belongs to the self-stability problem of GFM converters.Moreover,GFM converters will also interact with grid-following(GFL)converters and thus impact the mid-frequency oscillations(MFOs)induced by phase-locked loops(PLLs).It has been preliminarily shown in the literature that GFM converters can help stabilize the PLL-induced MFOs,but currently,there is a lack of systematic design methods to coordinate the self-stability and stabilizing ability of GFM converters.This paper addresses this gap by revisiting the impedance model of a typical GFM converter and briefly analyze the oscillations caused by converters.Based on our analysis,we propose a frequency-partitioned synthesis design framework to enable dynamic virtual impedance(DVI)in GFM converters,aiming to enhance their self-stability and stabilizing ability simultaneously.Particularly,a self-stabilizing module is designed to ensure robust device-level damping,with control parameters auto-tuned using H∞methods.In parallel,a stabilizing module is introduced to stabilize GFL converters and enhance the system-level stability,which utilizes a perceive-and-optimize tuning strategy.Simulation results validate the effectiveness of the proposed synthesis DVI framework.展开更多
A model for dynamic frictionless contact between a viscoelastic body and foundation is considered.The viscoelastic constitutive law is assumed to be nonlinear and the contact is modelled with the normal compliance con...A model for dynamic frictionless contact between a viscoelastic body and foundation is considered.The viscoelastic constitutive law is assumed to be nonlinear and the contact is modelled with the normal compliance condition.We obtain the well-posedness using nonlinear semigroup theory arguments.Moreover,the exponential stability result of the solution is shown by using the energy method to produce a suitable Lyapunov function.展开更多
Phase segregation triggered by illumination is a typical stimulus response in wide-bandgap perovskites,and addressing it is vital for overcoming the stability bottleneck of perovskite devices by mitigating phase segre...Phase segregation triggered by illumination is a typical stimulus response in wide-bandgap perovskites,and addressing it is vital for overcoming the stability bottleneck of perovskite devices by mitigating phase segregation and implementing dynamic management.To tackle this,a dynamic covalent bond-mediated approach is proposed to deal with phase segregation in wide-bandgap perovskites.Results show that adding dynamic disulfide and diselenide bonds effectively suppresses phase segregation while keeping halogen homogeneity.A 1.77 eV wide-bandgap perovskite device attains a peak conversion efficiency of 21.02% and retains over 90% of its initial efficiency after 1200 h of continuous illumination at the maximum power point.A fabricated perovskite/perovskite tandem device reaches an optimal conversion efficiency of 28.45%.Incorporating dynamic covalent bonds presents a new strategy for mitigating phase segregation in wide-bandgap perovskites and is expected to drive further progress in this area.展开更多
Pulsed dynamic electrolysis(PDE),driven by renewable energy,has emerged as an innovative electrocatalytic conversion method,demonstrating significant potential in addressing global energy challenges and promoting sust...Pulsed dynamic electrolysis(PDE),driven by renewable energy,has emerged as an innovative electrocatalytic conversion method,demonstrating significant potential in addressing global energy challenges and promoting sustainable development.Despite significant progress in various electrochemical systems,the regulatory mechanisms of PDE in energy and mass transfer and the lifespan extension of electrolysis systems,particularly in water electrolysis(WE)for hydrogen production,remain insufficiently explored.Therefore,there is an urgent need for a deeper understanding of the unique contributions of PDE in mass transfer enhancement,microenvironment regulation,and hydrogen production optimization,aiming to achieve low-energy consumption,high catalytic activity,and long-term stability in the generation of target products.Here,this review critically examines the microenvironmental effects of PDE on energy and mass transfer,the electrode degradation mechanisms in the lifespan extension of electrolysis systems,and the key factors in enhancing WE for hydrogen production,providing a comprehensive summary of current research progress.The review focuses on the complex regulatory mechanisms of frequency,duty cycle,amplitude,and other factors in hydrogen evolution reaction(HER)performance within PDE strategies,revealing the interrelationships among them.Finally,the potential future directions and challenges for transitioning from laboratory studies to industrial applications are proposed.展开更多
This paper introduces a novel fractional-order model based on the Caputo-Fabrizio(CF)derivative for analyzing computer virus propagation in networked environments.The model partitions the computer population into four...This paper introduces a novel fractional-order model based on the Caputo-Fabrizio(CF)derivative for analyzing computer virus propagation in networked environments.The model partitions the computer population into four compartments:susceptible,latently infected,breaking-out,and antivirus-capable systems.By employing the CF derivative—which uses a nonsingular exponential kernel—the framework effectively captures memory-dependent and nonlocal characteristics intrinsic to cyber systems,aspects inadequately represented by traditional integer-order models.Under Lipschitz continuity and boundedness assumptions,the existence and uniqueness of solutions are rigorously established via fixed-point theory.We develop a tailored two-step Adams-Bashforth numerical scheme for the CF framework and prove its second-order accuracy.Extensive numerical simulations across various fractional orders reveal that memory effects significantly influence virus transmission and control dynamics;smaller fractional orders produce more pronounced memory effects,delaying both infection spread and antivirus activation.Further theoretical analysis,including Hyers-Ulam stability and sensitivity assessments,reinforces the model’s robustness and identifies key parameters governing virus dynamics.The study also extends the framework to incorporate stochastic effects through a stochastic CF formulation.These results underscore fractional-order modeling as a powerful analytical tool for developing robust and effective cybersecurity strategies.展开更多
This paper deals with the stabilization of dynamic systems for two omni directional mobile robots by using the inner product of two vectors, one is from a robot's position to another's, the other is from a ro...This paper deals with the stabilization of dynamic systems for two omni directional mobile robots by using the inner product of two vectors, one is from a robot's position to another's, the other is from a robot's target point to another's. The multi step control laws given can exponentially stabilize the dynamic system and make the distance between two robots be greater than or equal to the collision free safe distance. The application of it to two omni directional mobile robots is described. Simulation result shows that the proposed controller is effective.展开更多
The body of quadruped robot is generally developed with the rigid structure. The mobility of quadruped robot depcnds on the mechanical properties of the body mechanism, It is difficult for quadruped robot with rigid s...The body of quadruped robot is generally developed with the rigid structure. The mobility of quadruped robot depcnds on the mechanical properties of the body mechanism, It is difficult for quadruped robot with rigid structure to achieve better mobility walking or running in the unstructured environment. A kind of bionic flexible body mechanism for quadruped robot is proposed, which is composed of one bionic spine and four pneumatic artificial muscles（PAMs）. This kind of body imitates the four-legged creatures＇ kinematical structure and physical properties, which has the characteristic of changeable stiff＇hess, lightweight, flexible and better bionics. The kinematics of body bending is derived, and the coordinated movement between the flexible body and legs is analyzed. The relationship between the body bending angle and the PAM length is obtained. The dynamics of the body bending is derived by the floating coordinate method and Lagrangian method, and the driving tbrce of PAM is determined. The experiment of body bending is conductcd, and the dynamic bending characteristic of bionic flexible body is evaluated. Experimental results show that the bending angle of the bionic flexible body can reach 18. An innovation body mechanism for quadruped robot is proposed, which has the characteristic of flexibility and achieve bending by changing gas pressure of PAMs. The coordinated movement of the body and legs can achieve spinning gait in order to improve the mobility of quadruped robot.展开更多
A unified theoretical aeroservoelastic stability analysis framework for flexible aircraft is established in this paper. This linearized state space model for stability analysis is based on nonlinear coupled dynamic eq...A unified theoretical aeroservoelastic stability analysis framework for flexible aircraft is established in this paper. This linearized state space model for stability analysis is based on nonlinear coupled dynamic equations, in which rigid and elastic motions of aircraft are both considered.The common body coordinate system is utilized as the reference frame in the deduction of dynamic equations, and significant deformations of flexible aircraft are also fully concerned without any excessive assumptions. Therefore, the obtained nonlinear coupled dynamic models can well reflect the special dynamic coupling mechanics of flexible aircraft. For aeroservoelastic stability analysis,the coupled dynamic equations are linearized around the nonlinear equilibrium state and together with a control system model to establish a state space model in the time domain. The methodology in this paper can be easily integrated into the industrial design process and complex structures.Numerical results for a complex flexible aircraft indicate the necessity to consider the nonlinear coupled dynamics and large deformation when dealing with aeroservoelastic stability for flexible aircraft.展开更多
基金supported by the National Key R&D Program of China(grant nos.2022YFF0503500 and 2022YFA1203200)the Guangdong Basic and Applied Basic Research Foundation(grant no.2023A1515011784)+2 种基金the National Natural Science Foundation of China(grant no.12032019)the Strategic Priority Research Program of Chinese Academy of Sciences(grant nos.XDB0620101 and XDB0620103)the Youth Innovation Promotion Association,Chinese Academy of Sciences(no.2020020).
文摘Droplet impact dynamics on solid surfaces,which are ubiquitously present in aerospace engineering,energy systems,agricultural production,etc.,involve complex fluid–structure interactions.Herein,we employ a single-camera high-speed threedimensional digital image correlation system to quantify the full-field deformations of flexible thin films during droplet impact dynamics.Experimental results revealed that the substrate flexibility not only reduces the maximum spreading diameter by 10%but also modulates rebound dynamics via energy competition between kinetic energy and surface adhesion energy,suggesting that coupled deformation of the solid–fluid interface plays an important role in the dynamic progress.We propose the structure-coupled response number(Sn),a governing dimensionless parameter unifying droplet spreading on both rigid and flexible films,validated by a universal 1/2 scaling law.A theoretical criterion for droplet rebound on hydrophobic flexible thin films is derived and experimentally demonstrated,which achieves the precise control of droplet rebound/non-rebound mode.This work bridges the theories of droplet impact dynamics on rigid and flexible substrates,offering a robust strategy to govern the droplet impact behaviors.
基金funded by the"14th Five-Year Plan"Civil Aerospace Pre-research Project of China(Grant No.D010301).
文摘Reusable and flexible capturing of space debris is highly required in future aerospace technologies.A tendon-actuated flexible robotic arm is therefore proposed for capturing floating targets in this paper.Firstly,an accurate dynamic model of the flexible robotic arm is established by using the absolute nodal coordinate formulation(ANCF)in the framework of the arbitrary Lagrangian-Eulerian(ALE)description and the natural coordinate formulation(NCF).The contact and self-contact dynamics of the flexible robotic arm when bending and grasping an object are considered via a fast contact detection approach.Then,the dynamic simulations of the flexible robotic arm for capturing floating targets are carried out to study the influence of the position,size,and mass of the target object on the grasping performance.Finally,a principle prototype of the tendon-actuated flexible robotic arm is manufactured to validate the dynamic model.The corresponding grasping experiments for objects of various shapes are also conducted to illustrate the excellent performance of the flexible robotic arm.
基金the National Natural Science Foundation of China(Nos.11832005,12372042,12232011)Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001)+1 种基金the Fundamental Research Funds for the Central Universities(No.NS2023002)State Key Laboratory of Mechanics and Control for Aerospace Structures(Nanjing University of Aeronautics and Astronautics)(No.MCAS-S-0223K04).
文摘The quantity of space debris on Earth orbit has escalated tremendously in recent years, presenting a significant hazard to human space operations. It is urgent to develop effective measures to capture and remove various space debris. For this purpose, this paper presents a tendon-actuated flexible deployable manipulator. The flexible manipulator consists of several deployable units connected by Cardan joints and actuated by tendons. Compared with the present technologies for capturing space debris such as rigid robotic arm or flying net, this flexible manipulator is deployable, reusable, lightweight and applicable to the capture of large space debris. In order to investigate its deployment dynamics, an accurate dynamic model of the flexible manipulator is established based on the natural coordinate formulation (NCF) and the absolute nodal coordinate formulation (ANCF). Subsequently, numerical simulations are carried out to study the effects of system parameters and the base satellite on its deployment dynamics. Finally, ground experiments for both deployment and bending of the flexible manipulator are conducted to verify its effectiveness and feasibility.
基金supported by the National Natural Science Foundation of China(No.52375443)the Innovative Research Group Project of the National Natural Science Foundation of China(No.51921003)。
文摘To meet the demand for the machining of blisks with narrow cascade channels and twisted blade profiles,especially integral shrouded blisks with shrouds,this paper innovatively proposes a method for dynamic deformation electrochemical cutting of flexible electrodes with arrayed group slit structure.By applying torque to both ends of the flexible electrode,the proposed method produces bending deformation and realizes the processing of a twisted profile.The flexible electrode is an important carrier of this method,and its properties such as elasticity,rigidity,and flow field uniformity have a crucial impact on smooth processing.Therefore,this paper proposes a design theory of flexible electrodes with an arrayed group slit structure and designs flexible electrodes with variable cross-sections.Compared with traditional uniform section tube electrode,the designed flexible electrode was subjected to the corresponding mechanical simulation,flow field simulation,and fluid–structure interaction simulation to investigate the elasticity,rigidity,and flow field uniformity of the flexible electrode.In addition,a deformation device of flexible electrodes was constructed and the corresponding experiments were carried out.Simulations and experiments demonstrate that flexible electrodes with arrayed group slit structures have good comprehensive performance.Finally,typical components were successfully machined to verify the feasibility of the proposed method and the rationality of the designed flexible electrode.It is shown that the proposed method has great potential for the machining of distorted profiles and provides a new idea for the machining of complex profiles.
基金supported by the Graduate Research Fund of Guizhou Province(Grant No.2024YJSKYJJ165)the National Natural Science Foundation of China(Grant No.62061008)the Guizhou Provincial Basic Research Program(Natural Science)(Grant No.Qian Ke He Ji Chu-ZK[2024]General 439)。
文摘We propose a simplified version of the classic two-dimensional Hindmarsh–Rose neuron(2DHR),resulting in a new 2DHR that exhibits novel chaotic phenomena.Its dynamic characteristics are analyzed through bifurcation diagrams,Lyapunov exponent spectra,equilibrium points,and phase diagrams.Based on this system,a corresponding circuit is designed and circuit simulations are carried out,yielding results consistent with the numerical simulations.To explore practical applications of chaotic systems,2DHR is employed to improve the solution of the flexible job-shop scheduling problem with dynamic events.The research results demonstrate that applying 2DHR can significantly enhance the convergence rate of the optimization algorithm and improve the quality of the scheduling solution.
基金financially supported by the China Postdoctoral Science Foundation(No.2024M751205)。
文摘Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.
基金supported by the National Key Research and Development Program Project(No.2021YFB3301300).
文摘Intelligent production is an important development direction in intelligent manufacturing,with intelligent factories playing a crucial role in promoting intelligent production.Flexible job shops,as the main form of intelligent factories,constantly face dynamic disturbances during the production process,including machine failures and urgent orders.This paper discusses the basic models and research methods of job shop scheduling,emphasizing the important role of dynamic job shop scheduling and its response schemes in future research.A multi-objective flexible job shop dynamic scheduling mathematical model is established,highlighting its complex and multi-constraint characteristics under different interferences.A classification discussion is conducted on the dynamic response methods and optimization objectives under machine failures,emergency orders,fuzzy completion times,and mixed dynamic events.The development process of traditional scheduling rules and intelligent methods in dynamic scheduling are also analyzed.Finally,based on the current development status of job shop scheduling and the requirements of intelligent manufacturing,the future development trends of dynamic scheduling in flexible job shops are proposed.
基金Supported by Finance Science and Technology Project of Hainan Province under Grant No.ZDKJ2021027the National Natural Science Foundation of China under Grant No.52231012.
文摘The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich in deep-sea polymetallic nodules.These nodules,which are nodular and unevenly distributed in seafloor sediments,have significant industrial exploitation value.Over the decades,the deep-sea mining industry has increasingly adopted systems that combine rigid and flexible risers supported by large surface mining vessels.However,current systems face economic and structural stability challenges,hindering the development of deep-sea mining technology.This paper proposes a new structural design for a deep-sea mining system based on flexible risers,validated through numerical simulations and experimental research.The system composition,function and operational characteristics are comprehensively introduced.Detailed calculations determine the production capacity of the deep-sea mining system and the dimensions of the seabed mining subsystem.Finite element numerical simulations analyze the morphological changes of flexible risers and the stress conditions at key connection points under different ocean current incident angles.Experimental research verifies the feasibility of collaborative movement between two tethered underwater devices.The proposed deep-sea mining system,utilizing flexible risers,significantly advances the establishment of a commercial deep-sea mining system.The production calculations and parameter determinations provide essential references for the system’s future detailed design.Furthermore,the finite element simulation model established in this paper provides a research basis,and the method established in this paper offers a foundation for subsequent research under more complex ocean conditions.The control strategy for the collaborative movement between two tethered underwater devices provides an effective solution for deep-sea mining control systems.
基金National Natural Science Foundation of China-NSAF(Grant No.U2330202)the National Natural Science Foundation of China(Grant Nos.52175162 and 51805086)+1 种基金Fujian Provincial Technological Innovation Key Research and Industrialization Projects(Grant Nos.2023XQ005 and 2024XQ010)The National Independent Innovation Demonstration Platform Project of Fujian Province(2024QZFX07)。
文摘Flexible microporous metal rubber(FMP-MR)is widely used in national defense applications,yet its mechanical behavior under high-speed impact conditions remains insufficiently explored.In this study,dynamic and static experiments were conducted to systematically investigate the mechanical response of metal-wrapped microporous materials under impact loading that spanned 10~6 orders of magnitude.By combining a high-precision numerical model with a spatial contact point search algorithm,the spatio–temporal contact characteristics of the complex network structure in FMP-MR were systematically analyzed.Furthermore,the mapping mechanism from turn topology and mesoscopic friction behavior to macroscopic mechanical properties was comprehensively explored.The results showed that compared with quasi-static loading,FMP-MR under high-speed impact exhibited higher energy absorption efficiency due to high-strain-rate inertia effect.Therefore,the peak stress increased by 141%,and the maximum energy dissipation increased by 300%.Consequently,the theory of dynamic friction locking effect was innovatively proposed.The theory explains that the close synergistic effect of sliding friction and plastic dissipation promoted by the stable interturn-locked embedded structure is the essential reason for the excellent dynamic mechanical properties of FMP-MR under dynamic loading conditions.Briefly,based on the in-depth investigation of the mechanical response and energy dissipation mechanism of FMP-MR under impact loads,this study provides a solid theoretical basis for further expanding the application range of FMP-MR and optimizing its performance.
文摘This work reviews models and methods for determining the dynamic response of pavements to moving vehicle loads in the framework of continuum-based three dimensional models and linear theories.This review emphasizes the most representative models and methods of analysis in the existing literature and illustrates all of them by numerical examples.Thus,13 such examples are presented here in some detail.Both flexible and rigid(concrete)pavement models involving simple and elaborate cases with respect to geometry and material behavior are considered.Thus,homogeneous or layered half-spaces with isotropic or cross-anisotropic and elastic,viscoelastic or poroelastic properties are considered.The vehicles are modeled as simple point or distributed loads or discrete spring-mass-dashpot system moving with constant or variable velocity.The dynamic response of the above pavement-vehicle systems is obtained by analytical/numerical or purely numerical methods of solution.Analytical/numerical methods have mainly to do with Fourier transforms or complex Fourier series with respect to both space and time.Purely numerical methods involve the finite element method(FEM)and the boundary element method(BEM)working in time or frequency domain.Critical discussions on the advantages and disadvantages of the various pavement-vehicle models and their methods of analysis are provided and the effects of the main parameters on the pavement response are determined through parametric studies and presented in the examples.Finally,conclusions are provided and suggestions for future research are made.
基金supported by National Natural Science Foundation of China(Grant No.52272100)the Fund of Science and Technology on Advanced Ceramic Fibers and Composites Laboratory(Grant No.WDZC20215250507)the Fund of National Key Laboratory of Nuclear Reactor Technology of Nuclear Power Institute of China(KGSW-0324-0301-08)。
文摘The demand for sensors capable of operating in extreme environment of the fields,such as aerospace vehicles,aeroengines and fire protection,is rapidly increasing.However,developing flexible ceramic fibrous pressure sensors that combine high temperature stability with robust mechanical properties remains a significant challenge.Herein,through precise multi-scale process control,high-strength(2.1 MPa)TiC-SiC flexible fibrous membrane is successfully fabricated.The membrane exhibits exceptional thermal resistance(2000℃)and long–term thermal stability(1800℃ for 5 h)in the inert atmosphere.Meanwhile,the TiC-SiC fibrous membrane shows excellent oxidation resistance and still achieves strength of 1.8 MPa after being oxidized at 1200℃ for 1 h in air.Remarkably,TiC-SiC fibrous membrane withstands a load of approximately 1400 times its own weight and the ablation of butane flame(~1300℃)for at least 1 h without breaking.Notably,after heat treatment at 1800℃ for 5 h in an argon atmosphere,the TiC-SiC fibrous membrane even sustains pressure–sensing performance for up to 300 cycles.The membrane exhibits stable resistivity up to 900℃ and shows sensing stability under butane flame.The results of this work provide an effective and feasible solution to fill the research gap of flexible fibrous sensors for extreme environments.
基金supported by the National Natural Science Foundation of China(52402040 and 52561160149)National Key R&D Program of China(2024YFE0109200)+7 种基金Fundamental Research Funds for the Central Universities(2024300440)Open Project(M37033)of National Laboratory of Solid State Microstructures,Nanjing UniversityGuangdong Basic and Applied Basic Research Foundation(2025A1515011098)Shenzhen Science and Technology Program(JCYJ20250604190115021)Key Research Project of Universities in Henan Province(25A430006)Henan Province University Students Innovation Training Project(202510479001)Funded by the Training Program for Young Backbone Teachers in Higher Education Institutions of Henan Province(Prof.Chaowei Li)Science and Technology Research Project of Henan Province(242102240076)。
文摘Driven by the burgeoning demand for wearable electronics,the development of inherently safe,mechanically compliant,and high-energy–density power sources has become imperative.Flexible aqueous Zn ions batteries(FAZIBs)are hampered by Zn dendrite formation and hydrogen evolution,underscoring the urgent need for highly stable and novel flexible energy-storage devices.Although flexible aqueous cobalt-ion batteries(FACIBs)employing cobalt-salt aqueous electrolytes exhibit high theoretical capacity,they suffer from two limitations:the rapid dissolution of cathode active substances in the aqueous electrolyte and the risk of liquid electrolyte leakage under mechanical deformation.Here,we report the first realization of an ultra-stable,quasi-solid-state and mechanically FACIBs.Polyacrylamide(PAM)containing CoSO_(4) serves as the quasi-solid electrolyte,while cobalt hexacyanoferrate(CoHCF)functions as the cathode active material,and metallic cobalt foil as the flexible anode.This configuration simultaneously eliminates electrolyte leakage and suppresses the dissolution of CoHCF due to the common-ion effect of Co^(2+).Consequently,the fabricated FACIBs exhibit extraordinary cycling durability and remarkable mechanical robustness(95.9%retention after 500 bending cycles).Thus,this work provides a new way for designing ultra-stable energy storage devices for wearable electronics.
基金supported by National Natural Science Foundation of China(U24B6008,U22B6008)State Grid Zhejiang Electric Power Co.,Ltd.Science,and Technology Project(B311DS240015).
文摘In the future power-electronics-dominated power systems,grid-forming(GFM)converters have been regarded as important devices to actively establish frequency and voltage,so as to provide essential grid support.However,due to their voltage source behavior and emulated swing dynamics,GFM converters may encounter low-frequency oscillations(LFOs)when connected to strong grids,which belongs to the self-stability problem of GFM converters.Moreover,GFM converters will also interact with grid-following(GFL)converters and thus impact the mid-frequency oscillations(MFOs)induced by phase-locked loops(PLLs).It has been preliminarily shown in the literature that GFM converters can help stabilize the PLL-induced MFOs,but currently,there is a lack of systematic design methods to coordinate the self-stability and stabilizing ability of GFM converters.This paper addresses this gap by revisiting the impedance model of a typical GFM converter and briefly analyze the oscillations caused by converters.Based on our analysis,we propose a frequency-partitioned synthesis design framework to enable dynamic virtual impedance(DVI)in GFM converters,aiming to enhance their self-stability and stabilizing ability simultaneously.Particularly,a self-stabilizing module is designed to ensure robust device-level damping,with control parameters auto-tuned using H∞methods.In parallel,a stabilizing module is introduced to stabilize GFL converters and enhance the system-level stability,which utilizes a perceive-and-optimize tuning strategy.Simulation results validate the effectiveness of the proposed synthesis DVI framework.
文摘A model for dynamic frictionless contact between a viscoelastic body and foundation is considered.The viscoelastic constitutive law is assumed to be nonlinear and the contact is modelled with the normal compliance condition.We obtain the well-posedness using nonlinear semigroup theory arguments.Moreover,the exponential stability result of the solution is shown by using the energy method to produce a suitable Lyapunov function.
基金the financial support from the National Key R&D Program of China(2023YFE0111500)the National Nature Science Foundation of China(52103237,52321006,T2394480,T2394484)the Key Research Project Plan of Higher Education Institutions in Henan Province,China(26A150044)。
文摘Phase segregation triggered by illumination is a typical stimulus response in wide-bandgap perovskites,and addressing it is vital for overcoming the stability bottleneck of perovskite devices by mitigating phase segregation and implementing dynamic management.To tackle this,a dynamic covalent bond-mediated approach is proposed to deal with phase segregation in wide-bandgap perovskites.Results show that adding dynamic disulfide and diselenide bonds effectively suppresses phase segregation while keeping halogen homogeneity.A 1.77 eV wide-bandgap perovskite device attains a peak conversion efficiency of 21.02% and retains over 90% of its initial efficiency after 1200 h of continuous illumination at the maximum power point.A fabricated perovskite/perovskite tandem device reaches an optimal conversion efficiency of 28.45%.Incorporating dynamic covalent bonds presents a new strategy for mitigating phase segregation in wide-bandgap perovskites and is expected to drive further progress in this area.
基金financially supported by the Key Research and Development Program of Heilongjiang Province(No.2024ZXJ03C06)National Natural Science Foundation of China(No.52476192,No.52106237)+1 种基金Natural Science Foundation of Heilongjiang Province(No.YQ2022E027)Technology Project of China Datang Technology Innovation Co.,Ltd(No.DTKC-2024-20610).
文摘Pulsed dynamic electrolysis(PDE),driven by renewable energy,has emerged as an innovative electrocatalytic conversion method,demonstrating significant potential in addressing global energy challenges and promoting sustainable development.Despite significant progress in various electrochemical systems,the regulatory mechanisms of PDE in energy and mass transfer and the lifespan extension of electrolysis systems,particularly in water electrolysis(WE)for hydrogen production,remain insufficiently explored.Therefore,there is an urgent need for a deeper understanding of the unique contributions of PDE in mass transfer enhancement,microenvironment regulation,and hydrogen production optimization,aiming to achieve low-energy consumption,high catalytic activity,and long-term stability in the generation of target products.Here,this review critically examines the microenvironmental effects of PDE on energy and mass transfer,the electrode degradation mechanisms in the lifespan extension of electrolysis systems,and the key factors in enhancing WE for hydrogen production,providing a comprehensive summary of current research progress.The review focuses on the complex regulatory mechanisms of frequency,duty cycle,amplitude,and other factors in hydrogen evolution reaction(HER)performance within PDE strategies,revealing the interrelationships among them.Finally,the potential future directions and challenges for transitioning from laboratory studies to industrial applications are proposed.
基金supported and funded by the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University(IMSIU)(grant number IMSIU-DDRSP2601).
文摘This paper introduces a novel fractional-order model based on the Caputo-Fabrizio(CF)derivative for analyzing computer virus propagation in networked environments.The model partitions the computer population into four compartments:susceptible,latently infected,breaking-out,and antivirus-capable systems.By employing the CF derivative—which uses a nonsingular exponential kernel—the framework effectively captures memory-dependent and nonlocal characteristics intrinsic to cyber systems,aspects inadequately represented by traditional integer-order models.Under Lipschitz continuity and boundedness assumptions,the existence and uniqueness of solutions are rigorously established via fixed-point theory.We develop a tailored two-step Adams-Bashforth numerical scheme for the CF framework and prove its second-order accuracy.Extensive numerical simulations across various fractional orders reveal that memory effects significantly influence virus transmission and control dynamics;smaller fractional orders produce more pronounced memory effects,delaying both infection spread and antivirus activation.Further theoretical analysis,including Hyers-Ulam stability and sensitivity assessments,reinforces the model’s robustness and identifies key parameters governing virus dynamics.The study also extends the framework to incorporate stochastic effects through a stochastic CF formulation.These results underscore fractional-order modeling as a powerful analytical tool for developing robust and effective cybersecurity strategies.
文摘This paper deals with the stabilization of dynamic systems for two omni directional mobile robots by using the inner product of two vectors, one is from a robot's position to another's, the other is from a robot's target point to another's. The multi step control laws given can exponentially stabilize the dynamic system and make the distance between two robots be greater than or equal to the collision free safe distance. The application of it to two omni directional mobile robots is described. Simulation result shows that the proposed controller is effective.
基金Supported by National Natural Science Foundation of China(Grant No.51375289)Shanghai Municipal Natural Science Foundation of China(Grant No.13ZR1415500)Innovation Fund of Shanghai Education Commission(Grant No.13YZ020)
文摘The body of quadruped robot is generally developed with the rigid structure. The mobility of quadruped robot depcnds on the mechanical properties of the body mechanism, It is difficult for quadruped robot with rigid structure to achieve better mobility walking or running in the unstructured environment. A kind of bionic flexible body mechanism for quadruped robot is proposed, which is composed of one bionic spine and four pneumatic artificial muscles（PAMs）. This kind of body imitates the four-legged creatures＇ kinematical structure and physical properties, which has the characteristic of changeable stiff＇hess, lightweight, flexible and better bionics. The kinematics of body bending is derived, and the coordinated movement between the flexible body and legs is analyzed. The relationship between the body bending angle and the PAM length is obtained. The dynamics of the body bending is derived by the floating coordinate method and Lagrangian method, and the driving tbrce of PAM is determined. The experiment of body bending is conductcd, and the dynamic bending characteristic of bionic flexible body is evaluated. Experimental results show that the bending angle of the bionic flexible body can reach 18. An innovation body mechanism for quadruped robot is proposed, which has the characteristic of flexibility and achieve bending by changing gas pressure of PAMs. The coordinated movement of the body and legs can achieve spinning gait in order to improve the mobility of quadruped robot.
基金supported by the National Key Research and Development Program of China(No.2016YFB0200703)
文摘A unified theoretical aeroservoelastic stability analysis framework for flexible aircraft is established in this paper. This linearized state space model for stability analysis is based on nonlinear coupled dynamic equations, in which rigid and elastic motions of aircraft are both considered.The common body coordinate system is utilized as the reference frame in the deduction of dynamic equations, and significant deformations of flexible aircraft are also fully concerned without any excessive assumptions. Therefore, the obtained nonlinear coupled dynamic models can well reflect the special dynamic coupling mechanics of flexible aircraft. For aeroservoelastic stability analysis,the coupled dynamic equations are linearized around the nonlinear equilibrium state and together with a control system model to establish a state space model in the time domain. The methodology in this paper can be easily integrated into the industrial design process and complex structures.Numerical results for a complex flexible aircraft indicate the necessity to consider the nonlinear coupled dynamics and large deformation when dealing with aeroservoelastic stability for flexible aircraft.
