Ion-exchange Polymer-Metal Composites(IPMCs)gain huge attentions due to large deformation,rapid electromechanical response,and high energy conversion efficiency.Deflection of IPMC arises from the volumetric swelling e...Ion-exchange Polymer-Metal Composites(IPMCs)gain huge attentions due to large deformation,rapid electromechanical response,and high energy conversion efficiency.Deflection of IPMC arises from the volumetric swelling effect induced by the concentration gradient of hydrated cations between the two electrodes,thus the volume of hydrated cation deter-mines the motion magnitude and direction of IPMC.H ion is one of the most commonly used driving cations for IPMC.However,due to its unique characteristics,particularly the inability to accurately quantify its hydration volume,existing literatures primarily focus on the physical driving models for metallic cations,i.e.,Na+,no driving model for the H ion is reported until now.This paper proposes a novel model of H ion escape from the water's body-centered cubic lattice to count the hydration volume.Number(n)of water molecules carried by the H ion is solved by combining the Lennard-Jones potential energy function with Maxwell's velocity distribution.The specific n value is equivalent to 4.04 for the H ion inside Nafion electrolyte under a 3.0 V DC electric field.Substituting it into the classic Friction Model(proposed by Tadokoro et al.at 2000),actuation behaviors of H ion driven IPMC were therefore achieved through Matlab calculations and Abaqus simulations.The calculated results of dynamic displacement and force highly match to the experimental data form the Nafion IPMC actuator driven by same electric field,showing a highly reliability of the established escape model.展开更多
We present a general theoretical framework for the formulation of the nonlinear electromechanics of polymeric and biological active media.The approach developed here is based on the additive decomposition of the Helmh...We present a general theoretical framework for the formulation of the nonlinear electromechanics of polymeric and biological active media.The approach developed here is based on the additive decomposition of the Helmholtz free energy in elastic and inelastic parts and on the multiplicative decomposition of the deformation gradient in passive and active parts.We describe a thermodynamically sound scenario that accounts for geometric and material nonlinearities.In view of numerical applications,we specialize the general approach to a particular material model accounting for the behavior of fiber reinforced tissues.Specifically,we use the model to solve via finite elements a uniaxial electromechanical problem dynamically activated by an electrophysiological stimulus.Implications for nonlinear solid mechanics and computational electrophysiology are finally discussed.展开更多
Developing sensorless techniques for estimating battery expansion is essential for effective mechanical state monitoring,improving the accuracy of digital twin simulation and abnormality detection.Therefore,this paper...Developing sensorless techniques for estimating battery expansion is essential for effective mechanical state monitoring,improving the accuracy of digital twin simulation and abnormality detection.Therefore,this paper presents a data-driven approach to expansion estimation using electromechanical coupled models with machine learning.The proposed method integrates reduced-order impedance models with data-driven mechanical models,coupling the electrochemical and mechanical states through the state of charge(SOC)and mechanical pressure within a state estimation framework.The coupling relationship was established through experimental insights into pressure-related impedance parameters and the nonlinear mechanical behavior with SOC and pressure.The data-driven model was interpreted by introducing a novel swelling coefficient defined by component stiffnesses to capture the nonlinear mechanical behavior across various mechanical constraints.Sensitivity analysis of the impedance model shows that updating model parameters with pressure can reduce the mean absolute error of simulated voltage by 20 mV and SOC estimation error by 2%.The results demonstrate the model's estimation capabilities,achieving a root mean square error of less than 1 kPa when the maximum expansion force is from 30 kPa to 120 kPa,outperforming calibrated stiffness models and other machine learning techniques.The model's robustness and generalizability are further supported by its effective handling of SOC estimation and pressure measurement errors.This work highlights the importance of the proposed framework in enhancing state estimation and fault diagnosis for lithium-ion batteries.展开更多
The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and run...The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and running resistance,and the dynamic models of gear transmission system are not sufficiently comprehensive.This paper aims to establish an electromechanical coupling dynamic model of HST traction transmission system and study its electromechanical coupling vibration characteristics,in which the internal excitation factors such as gear eccentricity,time-varying meshing stiffness,backlash,meshing error,and external excitation factors such as electromagnetic torque and running resistance are stressed.The research results indicate that gear eccentricity and running resistance have a significant impact on the stability of the system,and gear eccentricity leads to intensified system vibration and decreased anti-interference ability.In addition,the characteristic frequency of gear eccentricity can be extracted from mechanical signals and current signals as a preliminary basis for eccentricity detection,and electrical signals can also be used to monitor changes in train running resistance in real time.The results of this study provide some useful insights into designing dynamic performance parameters for HST transmission systems and monitoring train operational states.展开更多
Flexible sensors,a class of devices that can convert external mechanical or physical signals into changes in resistance,capacitance,or current,have developed rapidly since the concept was first proposed.Due to the spe...Flexible sensors,a class of devices that can convert external mechanical or physical signals into changes in resistance,capacitance,or current,have developed rapidly since the concept was first proposed.Due to the special properties and naturally occurring excellent microstructures of biomaterials,it can provide more desirable properties to flexible devices.This paper systematically discusses the commonly used biomaterials for bio-based flexible devices in current research applications and their deployment in preparing flexible sensors with different mechanisms.According to the characteristics of other properties and application requirements of biomaterials,the mechanisms of their functional group properties,special microstructures,and bonding interactions in the context of various sensing applications are presented in detail.The practical application scenarios of biomaterial-based flexible devices are highlighted,including human-computer interactions,energy harvesting,wound healing,and related biomedical applications.Finally,this paper also reviews in detail the limitations of biobased materials in the construction of flexible devices and presents challenges and trends in the development of biobased flexible sensors,as well as to better explore the properties of biomaterials to ensure functional synergy within the composite materials.展开更多
As an emerging multifunctional metal with the lowest melting point except for mercury,gallium combines a wide range of metallic and non-metallic elements to form advanced semiconductors critically important in cutting...As an emerging multifunctional metal with the lowest melting point except for mercury,gallium combines a wide range of metallic and non-metallic elements to form advanced semiconductors critically important in cutting-edge technologies.However,due to its low melting point and poor machinability,it is quite difficult to simultaneously characterize gallium’s elastic properties and damping characteristics using conventional methods,which is es-sential in designing and evaluating gallium-based structures.Therefore,developing effective methods to achieve accurate and efficient measurements of Young’s modulus and corresponding internal friction of gallium is of great significance.This letter studies simultaneous measurements of the variations in Young’s modulus and internal friction of gallium at varying temperatures by employing the modified piezoelectric ultrasonic composite oscil-lator technique.Combining the explicit theoretical formulas with the measured resonance and anti-resonance frequencies,it has been discovered that Young’s modulus undergoes an approximately linear decrease as the temperature rises,declining from 83.84 GPa at -70℃ to 79.37 GPa at 20℃.Moreover,like aluminum in the same Group ⅢA of the Periodic Table of Elements and exhibits a grain-boundary internal friction peak,gallium displays a longitudinal internal friction peak at approximately-12°C,with the peak value reaching 1.77×10^(-3).This basic research on gallium’s elastic properties and damping characteristics under low-temperature condi-tions will inspire further explorations of the mechanical properties of a diverse spectrum of low-melting-point functional materials and facilitate applications of gallium-based structures under complex conditions.展开更多
The arterial pulse tapping artifact,known as Aslanger’s sign,is an electrocardiographic artifact resulting from the transmission of arterial pulsation onto the limb electrodes of the standard 12-lead electrocardiogra...The arterial pulse tapping artifact,known as Aslanger’s sign,is an electrocardiographic artifact resulting from the transmission of arterial pulsation onto the limb electrodes of the standard 12-lead electrocardiograph(ECG)which are placed near the radial or posterior tibial arteries.[1-16]This electromechanical artifact is of cardiac origin and is synchronous with the cardiac cycle.[17]Nearly all reported cases of Aslanger’s sign exhibit an unusual waveform morphology in all 12 leads except one limb lead.[1-14,16]However,we previously reported a case of Aslanger’s sign that showed distorted waveforms from the ST to TP segments observed only in five limb leads among 12 leads.展开更多
This study explores engineering risk prevention and control in electromechanical engineering from the technical management perspective.It elaborates on technical management’s role,core concepts,critical risks,and var...This study explores engineering risk prevention and control in electromechanical engineering from the technical management perspective.It elaborates on technical management’s role,core concepts,critical risks,and various strategies like fail-safe design,predictive maintenance,ISO-compliant workflows.It also emphasizes future research areas such as AI-driven predictive risk modeling and cross-disciplinary management frameworks.展开更多
Electromechanical engineering in building facility management is crucial.It involves detecting and maintaining building lighting circuits,central-air-conditioning units,and handling customer maintenance requirements.A...Electromechanical engineering in building facility management is crucial.It involves detecting and maintaining building lighting circuits,central-air-conditioning units,and handling customer maintenance requirements.Approaches like real-time monitoring,scheduled maintenance,non-invasive testing,energy-efficient retrofitting,and client-centric services enhance building operations,reliability,and tenant satisfaction,laying a foundation for sustainable development.展开更多
Recent theoretical work has predicted the existence of a“dipole spiral”structure in strained freestanding membranes of PbTiO_(3),suggesting a potential route to enhanced electromechanical responses[Phys.Rev.Lett.133...Recent theoretical work has predicted the existence of a“dipole spiral”structure in strained freestanding membranes of PbTiO_(3),suggesting a potential route to enhanced electromechanical responses[Phys.Rev.Lett.133046802(2024)].However,its microscopic nature,energetic landscape,and electronic properties remain largely unexplored from a first-principles perspective.Here,using density functional theory on PbTiO3 under biaxial tensile strain,we identify a novel form of polar order:a chiral,non-collinear ferroelectric double helix.We find that two distinct,intertwined polarization helices are formed by the local Pb-O and Ti-O dipoles,reminiscent of DNA.This topology is stabilized by a collective helical twisting of the encompassing oxygen cages(the polyhedra for both Pb and Ti cations),which gives rise to an electric Dzyaloshinskii–Moriya-like interaction.The resulting structure,which can be conceptualized as a“self-moiré”crystal,exhibits two coupled functionalities.First,it possesses a rotational pseudo-zero-energy mode that underpins a giant piezoelectric response(e_(33)≈16C/m^(2)).Second,the long-period potential reconstructs the electronic band structure,leading to a multi-valley electronic topology at the valence band edge.Our work establishes a physical route to designing complex chiral order that supports both giant electromechanical coupling and multi-valley electronics.展开更多
To achieve the manufacturing of Thin-Wall and High-Rib Components(TWHRC)with high precision,a novel heavy load Multi-DOF Envelope Forming Press(MEFP)with Parallel Kinematic Mechanism(PKM),driven by six Permanent Magne...To achieve the manufacturing of Thin-Wall and High-Rib Components(TWHRC)with high precision,a novel heavy load Multi-DOF Envelope Forming Press(MEFP)with Parallel Kinematic Mechanism(PKM),driven by six Permanent Magnet Synchronous Motors(PMSMs),is developed.However,on account of the heavy forming load,the PMSM parameters are in great variation.Meanwhile,the PMSM is always in a transient state caused by fast time-varying forming load,resulting in low identification precision of varied PMSM parameters and control precision of PMSM under traditional parameter identification methods.To solve this problem,a novel Sliding Mode Control Method with Enhanced PMSM Parameter Identification(SMCMEPPI)for heavy load MEFP is proposed.Firstly,the kinematic model of MEFP is established.Secondly,the variation law of PMSM parameters under heavy load is revealed.Thirdly,an enhanced PMSM parameter identification method is proposed,in which the q axis current of PMSM is used to represent the changing rate of forming load and the adjustment factor is first proposed to remove improper input of PMSM parameter identification online.Fourthly,the Electromechanical Coupling Dynamic Model(ECDM)of MEFP,which includes identified PMSM parameters,is developed.Finally,based on the developed ECDM,a novel SMCMEPPI is proposed to realize the high-precision control of heavy load MEFP.The experimental results indicate that the proposed SMCMEPPI can significantly improve the control precision of heavy load MEFP.展开更多
This article presents the design of a microfabricated bio-inspired flapping-wing Nnano Aaerial Vvehicle(NAV),driven by an electromagnetic system.Our approach is based on artificial wings composed of rigid bodies conne...This article presents the design of a microfabricated bio-inspired flapping-wing Nnano Aaerial Vvehicle(NAV),driven by an electromagnetic system.Our approach is based on artificial wings composed of rigid bodies connected by compliant links,which optimise aerodynamic forces though replicating the complex wing kinematics of insects.The originality of this article lies in a new design methodology based on a triple equivalence between a 3D model,a multibody model,and a mass/spring model(0D)which reduces the number of parameters in the problem.This approach facilitates NAV optimisation by using only the mass/spring model,thereby simplifying the design process while maintaining high accuracy.Two wing geometries are studied and optimised in this article to produce large-amplitude wing motions(approximately 40^\circ),and enabling flapping and twisting motion in quadrature.The results are validated thanks to experimental measurements for the large amplitude and through finite element simulations for the combined motion,confirming the effectiveness of this strategy for a NAV weighing less than 40 mg with a wingspan of under 3 cm.展开更多
This paper focuses on electrical fault diagnosis and operation and maintenance technology in property service electromechanical engineering.It details core diagnostic methods,application-oriented tools,predictive main...This paper focuses on electrical fault diagnosis and operation and maintenance technology in property service electromechanical engineering.It details core diagnostic methods,application-oriented tools,predictive maintenance frameworks,and enhanced maintenance planning.It also explores wireless sensor networks,big data analytics,and design-phase applications.Case studies in construction and operation phases are presented.Challenges like legacy system retrofitting are noted,and future potential in quantum sensing and edge AI is discussed.展开更多
Cells live in a multiphysics-coupled microenvironment in vivo,in which electric fields(EFs)and mechanical cues are the most essential induction signals.The regulatory effects of EFs and stiffness on cells have been in...Cells live in a multiphysics-coupled microenvironment in vivo,in which electric fields(EFs)and mechanical cues are the most essential induction signals.The regulatory effects of EFs and stiffness on cells have been independently demonstrated.However,how cells respond to electromechanical coupling cues remains mysterious.In this study,an electro-stiffness-coupled chip system was designed and fabricated,freely integrating and precisely controlling EF strength and the mechanical stiffness applied to cells across the physiological spectrum.Utilizing the innovative bioreactor,it was observed that electromechanical coupling stimulations can shape cancer cell morphology and cytoskeleton into a unique anteroposterior polarization state and orient cancer cell migration in a voltage-dependent manner through cytoskeleton-associated mechanisms.Moreover,the mechanical stiffness regulated cancer cell susceptibility to EFs,and the orientation effect of EFs on cells required a stiffness threshold.Furthermore,transforming growth factor-β1 suppressed the orientation of cancer cells induced by electromechanical coupling signals and showed a splitting effect on the directionality and velocity of cancer cell migration,indicating a comprehensive cross-talk of biochemical–electromechanical signals.Together with the dual-physical bioreactor we designed,these findings provide a robust and convenient platform for exploring cellular responses to electro-stiffness coupling signals,reveal the biophysical mechanisms of cell polarization and migration from the perspective of electromechanical coupling,and lay a promising foundation for biophysical-based cell manipulation and therapeutic interventions.展开更多
In order to effectively control the working state of the gyroscope in drive mode, the drive characteristics of the micro electromechanical system （MEMS） gyroscope are analyzed in principle. A novel drive circuit for...In order to effectively control the working state of the gyroscope in drive mode, the drive characteristics of the micro electromechanical system （MEMS） gyroscope are analyzed in principle. A novel drive circuit for the MEMS gyroscope in digital closed-loop control is proposed, which utilizes a digital phase-locked loop （PLL） in frequency control and an automatic gain control （AGC） method in amplitude control. A digital processing circuit with a field programmable gate array （FPGA） is designed and the experiments are carried out. The results indicate that when the temperature changes, the drive frequency can automatically track the resonant frequency of gyroscope in drive mode and that of the oscillating amplitude holds at a set value. And at room temperature, the relative deviation of the drive frequency is 0.624 ×10^-6 and the oscillating amplitude is 8.0 ×10^-6, which are 0. 094% and 18. 39% of the analog control program, respectively. Therefore, the control solution of the digital PLL in frequency and the AGC in amplitude is feasible.展开更多
In this study, the effects of cardiac fibroblast proliferation on cardiac electric excitation conduction and mechanical contraction were investigated using a proposed integrated myocardial-fibroblastic electromechanic...In this study, the effects of cardiac fibroblast proliferation on cardiac electric excitation conduction and mechanical contraction were investigated using a proposed integrated myocardial-fibroblastic electromechanical model. At the cellular level, models of the human ventricular myocyte and fibroblast were modified to incorporate a model of cardiac mechanical contraction and cooperativity mechanisms. Cellular electromechanical coupling was realized with a calcium buffer. At the tissue level, electrical excitation conduction was coupled to an elastic mechanics model in which the finite difference method （FDM） was used to solve electrical excitation equations, and the finite element method （FEM） was used to solve mechanics equations. The electromechanical properties of the proposed integrated model were investigated in one or two dimensions under normal and ischemic pathological conditions. Fibroblast proliferation slowed wave propagation, induced a conduction block, decreased strains in the fibroblast proliferous tissue, and increased dispersions in depolarization, repolarization, and action potential duration （APD）. It also distorted the wave-front, leading to the initiation and maintenance of re-entry, and resulted in a sustained contrac- tion in the proliferous areas. This study demonstrated the important role that fibroblast proliferation plays in modulating cardiac electromechanical behaviour and which should be considered in planning future heart-modeling studies.展开更多
An electromechanical nonlinear model of rotor system of electric machine is built.Respondance curves in parameter excited nonlinear vibration of this system caused by electromagnetic forces are investigated.Further mo...An electromechanical nonlinear model of rotor system of electric machine is built.Respondance curves in parameter excited nonlinear vibration of this system caused by electromagnetic forces are investigated.Further more,the analysis reveals the effects of various electromagnetic and mechanical parameters on resonances, and some valuable results are obtained.The analytical result of this paper provides electric machine with the condition of 1/2 subharmonic resonance under the electromechanical electromagnetic forces.Electromagnetic forces apparently affect the stability zone, and both linear term and nonlinear term can excite parametric resonance.The revealed dynamic phenomena provide some new theories and active methods for the fault recognition of electric machine and the defination of stability range,and the theoretical bases for qualitatively controlling the stable operating state of rotors.展开更多
An electroaeroelastic model for wind energy harvesting using piezoelectric generators is presented.The flow field is mapped in detail.The force which the fluid flow exerts on the generator is formulated.The output vol...An electroaeroelastic model for wind energy harvesting using piezoelectric generators is presented.The flow field is mapped in detail.The force which the fluid flow exerts on the generator is formulated.The output voltage levels generated from the mechanical strain within the piezoelectric elements are determined.An analytical model is developed with consideration of the interactions between the fluid,solid and electric.Various analytical results are obtained,such as flow velocity contour and pressure contour for the flow,moving trajectories,stress contour and output voltage of the harvester.A prototype is fabricated and tested.The simulation result is close to the experimental result.The model developed in this paper can predict the performance and behavior of different energy harvesters.And it also can be used as a design tool for optimizing the performance of the harvester.展开更多
The growing need for renewable energy and zero carbon dioxide emissions has fueled the development of thermoelectric generators with improved power generating capability.Along with the endeavor to develop thermoelectr...The growing need for renewable energy and zero carbon dioxide emissions has fueled the development of thermoelectric generators with improved power generating capability.Along with the endeavor to develop thermoelectric materials with greater figures of merit,the geometrical and structural optimization of thermoelectric generators is equally critical for maximum power output and efficiency.Green energy strategies that are constantly updated are a viable option for addressing the global energy issue while also protecting the environment.There have been significant focuses on the development of thermoelectric modules for a range of solar,automotive,military,and aerospace applications in recent years due to various advantages including as low vibration,great reliability and durability,and the absence of moving components.In order to enhance the system performance of the thermoelectric generator,an artificial neural network(ANN)based algorithm is proposed.Furthermore,to achieve high efficiency and system stability,a buck converter is designed and deployed.Simulation and experimental findings demonstrate that the suggested method is viable and available,and that it is almost similar to the real value in the steady state with the least power losses,making it ideal for vehicle exhaust thermoelectric generator applications.Furthermore,the proposed hybrid algorithm has a high reference value for the development of a dependable and efficient car exhaust thermoelectric generating system.展开更多
基金National Natural Science Foundations of China(52275295)Central Plains Science and Technology Innovation Leading Talents(234200510026).
文摘Ion-exchange Polymer-Metal Composites(IPMCs)gain huge attentions due to large deformation,rapid electromechanical response,and high energy conversion efficiency.Deflection of IPMC arises from the volumetric swelling effect induced by the concentration gradient of hydrated cations between the two electrodes,thus the volume of hydrated cation deter-mines the motion magnitude and direction of IPMC.H ion is one of the most commonly used driving cations for IPMC.However,due to its unique characteristics,particularly the inability to accurately quantify its hydration volume,existing literatures primarily focus on the physical driving models for metallic cations,i.e.,Na+,no driving model for the H ion is reported until now.This paper proposes a novel model of H ion escape from the water's body-centered cubic lattice to count the hydration volume.Number(n)of water molecules carried by the H ion is solved by combining the Lennard-Jones potential energy function with Maxwell's velocity distribution.The specific n value is equivalent to 4.04 for the H ion inside Nafion electrolyte under a 3.0 V DC electric field.Substituting it into the classic Friction Model(proposed by Tadokoro et al.at 2000),actuation behaviors of H ion driven IPMC were therefore achieved through Matlab calculations and Abaqus simulations.The calculated results of dynamic displacement and force highly match to the experimental data form the Nafion IPMC actuator driven by same electric field,showing a highly reliability of the established escape model.
文摘We present a general theoretical framework for the formulation of the nonlinear electromechanics of polymeric and biological active media.The approach developed here is based on the additive decomposition of the Helmholtz free energy in elastic and inelastic parts and on the multiplicative decomposition of the deformation gradient in passive and active parts.We describe a thermodynamically sound scenario that accounts for geometric and material nonlinearities.In view of numerical applications,we specialize the general approach to a particular material model accounting for the behavior of fiber reinforced tissues.Specifically,we use the model to solve via finite elements a uniaxial electromechanical problem dynamically activated by an electrophysiological stimulus.Implications for nonlinear solid mechanics and computational electrophysiology are finally discussed.
基金Fund supported this work for Excellent Youth Scholars of China(Grant No.52222708)the National Natural Science Foundation of China(Grant No.51977007)+1 种基金Part of this work is supported by the research project“SPEED”(03XP0585)at RWTH Aachen Universityfunded by the German Federal Ministry of Education and Research(BMBF)。
文摘Developing sensorless techniques for estimating battery expansion is essential for effective mechanical state monitoring,improving the accuracy of digital twin simulation and abnormality detection.Therefore,this paper presents a data-driven approach to expansion estimation using electromechanical coupled models with machine learning.The proposed method integrates reduced-order impedance models with data-driven mechanical models,coupling the electrochemical and mechanical states through the state of charge(SOC)and mechanical pressure within a state estimation framework.The coupling relationship was established through experimental insights into pressure-related impedance parameters and the nonlinear mechanical behavior with SOC and pressure.The data-driven model was interpreted by introducing a novel swelling coefficient defined by component stiffnesses to capture the nonlinear mechanical behavior across various mechanical constraints.Sensitivity analysis of the impedance model shows that updating model parameters with pressure can reduce the mean absolute error of simulated voltage by 20 mV and SOC estimation error by 2%.The results demonstrate the model's estimation capabilities,achieving a root mean square error of less than 1 kPa when the maximum expansion force is from 30 kPa to 120 kPa,outperforming calibrated stiffness models and other machine learning techniques.The model's robustness and generalizability are further supported by its effective handling of SOC estimation and pressure measurement errors.This work highlights the importance of the proposed framework in enhancing state estimation and fault diagnosis for lithium-ion batteries.
基金supported by Sichuan Science and Technology Program(Grant No.2020YFH0080)the National Natural Science Foundation of China(Grant No.51475386)the National Basic Research Project of China(973 Program,Grant No.2015CB654801).
文摘The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and running resistance,and the dynamic models of gear transmission system are not sufficiently comprehensive.This paper aims to establish an electromechanical coupling dynamic model of HST traction transmission system and study its electromechanical coupling vibration characteristics,in which the internal excitation factors such as gear eccentricity,time-varying meshing stiffness,backlash,meshing error,and external excitation factors such as electromagnetic torque and running resistance are stressed.The research results indicate that gear eccentricity and running resistance have a significant impact on the stability of the system,and gear eccentricity leads to intensified system vibration and decreased anti-interference ability.In addition,the characteristic frequency of gear eccentricity can be extracted from mechanical signals and current signals as a preliminary basis for eccentricity detection,and electrical signals can also be used to monitor changes in train running resistance in real time.The results of this study provide some useful insights into designing dynamic performance parameters for HST transmission systems and monitoring train operational states.
基金supported financially by the National Natural Science Foundation of China(52205308,22208120)the China Postdoctoral Science Foundation(2022M711300).
文摘Flexible sensors,a class of devices that can convert external mechanical or physical signals into changes in resistance,capacitance,or current,have developed rapidly since the concept was first proposed.Due to the special properties and naturally occurring excellent microstructures of biomaterials,it can provide more desirable properties to flexible devices.This paper systematically discusses the commonly used biomaterials for bio-based flexible devices in current research applications and their deployment in preparing flexible sensors with different mechanisms.According to the characteristics of other properties and application requirements of biomaterials,the mechanisms of their functional group properties,special microstructures,and bonding interactions in the context of various sensing applications are presented in detail.The practical application scenarios of biomaterial-based flexible devices are highlighted,including human-computer interactions,energy harvesting,wound healing,and related biomedical applications.Finally,this paper also reviews in detail the limitations of biobased materials in the construction of flexible devices and presents challenges and trends in the development of biobased flexible sensors,as well as to better explore the properties of biomaterials to ensure functional synergy within the composite materials.
基金financially supported by the National Key R&D Program of China(Grant No.2023YFF0716800)the National Natural Science Foundation of China(Grant No.12074160)the Natural Science Foundation of Liaoning Province of China(Grant No.2024-MS-181).
文摘As an emerging multifunctional metal with the lowest melting point except for mercury,gallium combines a wide range of metallic and non-metallic elements to form advanced semiconductors critically important in cutting-edge technologies.However,due to its low melting point and poor machinability,it is quite difficult to simultaneously characterize gallium’s elastic properties and damping characteristics using conventional methods,which is es-sential in designing and evaluating gallium-based structures.Therefore,developing effective methods to achieve accurate and efficient measurements of Young’s modulus and corresponding internal friction of gallium is of great significance.This letter studies simultaneous measurements of the variations in Young’s modulus and internal friction of gallium at varying temperatures by employing the modified piezoelectric ultrasonic composite oscil-lator technique.Combining the explicit theoretical formulas with the measured resonance and anti-resonance frequencies,it has been discovered that Young’s modulus undergoes an approximately linear decrease as the temperature rises,declining from 83.84 GPa at -70℃ to 79.37 GPa at 20℃.Moreover,like aluminum in the same Group ⅢA of the Periodic Table of Elements and exhibits a grain-boundary internal friction peak,gallium displays a longitudinal internal friction peak at approximately-12°C,with the peak value reaching 1.77×10^(-3).This basic research on gallium’s elastic properties and damping characteristics under low-temperature condi-tions will inspire further explorations of the mechanical properties of a diverse spectrum of low-melting-point functional materials and facilitate applications of gallium-based structures under complex conditions.
文摘The arterial pulse tapping artifact,known as Aslanger’s sign,is an electrocardiographic artifact resulting from the transmission of arterial pulsation onto the limb electrodes of the standard 12-lead electrocardiograph(ECG)which are placed near the radial or posterior tibial arteries.[1-16]This electromechanical artifact is of cardiac origin and is synchronous with the cardiac cycle.[17]Nearly all reported cases of Aslanger’s sign exhibit an unusual waveform morphology in all 12 leads except one limb lead.[1-14,16]However,we previously reported a case of Aslanger’s sign that showed distorted waveforms from the ST to TP segments observed only in five limb leads among 12 leads.
文摘This study explores engineering risk prevention and control in electromechanical engineering from the technical management perspective.It elaborates on technical management’s role,core concepts,critical risks,and various strategies like fail-safe design,predictive maintenance,ISO-compliant workflows.It also emphasizes future research areas such as AI-driven predictive risk modeling and cross-disciplinary management frameworks.
文摘Electromechanical engineering in building facility management is crucial.It involves detecting and maintaining building lighting circuits,central-air-conditioning units,and handling customer maintenance requirements.Approaches like real-time monitoring,scheduled maintenance,non-invasive testing,energy-efficient retrofitting,and client-centric services enhance building operations,reliability,and tenant satisfaction,laying a foundation for sustainable development.
基金supported by Zhejiang Provincial Natural Science Foundation of China(Grant No.LR25A040004)。
文摘Recent theoretical work has predicted the existence of a“dipole spiral”structure in strained freestanding membranes of PbTiO_(3),suggesting a potential route to enhanced electromechanical responses[Phys.Rev.Lett.133046802(2024)].However,its microscopic nature,energetic landscape,and electronic properties remain largely unexplored from a first-principles perspective.Here,using density functional theory on PbTiO3 under biaxial tensile strain,we identify a novel form of polar order:a chiral,non-collinear ferroelectric double helix.We find that two distinct,intertwined polarization helices are formed by the local Pb-O and Ti-O dipoles,reminiscent of DNA.This topology is stabilized by a collective helical twisting of the encompassing oxygen cages(the polyhedra for both Pb and Ti cations),which gives rise to an electric Dzyaloshinskii–Moriya-like interaction.The resulting structure,which can be conceptualized as a“self-moiré”crystal,exhibits two coupled functionalities.First,it possesses a rotational pseudo-zero-energy mode that underpins a giant piezoelectric response(e_(33)≈16C/m^(2)).Second,the long-period potential reconstructs the electronic band structure,leading to a multi-valley electronic topology at the valence band edge.Our work establishes a physical route to designing complex chiral order that supports both giant electromechanical coupling and multi-valley electronics.
基金the National Science and Technology Major Project of China(No.2019-Ⅶ-0017-0158)the National Natural Science Foundation of China(Nos.U2037204,U21A20131)the Innovative Research Team Development Program of Ministry of Education of China(No.IRT17R83)for the support given to this research。
文摘To achieve the manufacturing of Thin-Wall and High-Rib Components(TWHRC)with high precision,a novel heavy load Multi-DOF Envelope Forming Press(MEFP)with Parallel Kinematic Mechanism(PKM),driven by six Permanent Magnet Synchronous Motors(PMSMs),is developed.However,on account of the heavy forming load,the PMSM parameters are in great variation.Meanwhile,the PMSM is always in a transient state caused by fast time-varying forming load,resulting in low identification precision of varied PMSM parameters and control precision of PMSM under traditional parameter identification methods.To solve this problem,a novel Sliding Mode Control Method with Enhanced PMSM Parameter Identification(SMCMEPPI)for heavy load MEFP is proposed.Firstly,the kinematic model of MEFP is established.Secondly,the variation law of PMSM parameters under heavy load is revealed.Thirdly,an enhanced PMSM parameter identification method is proposed,in which the q axis current of PMSM is used to represent the changing rate of forming load and the adjustment factor is first proposed to remove improper input of PMSM parameter identification online.Fourthly,the Electromechanical Coupling Dynamic Model(ECDM)of MEFP,which includes identified PMSM parameters,is developed.Finally,based on the developed ECDM,a novel SMCMEPPI is proposed to realize the high-precision control of heavy load MEFP.The experimental results indicate that the proposed SMCMEPPI can significantly improve the control precision of heavy load MEFP.
基金supported by ANR-ASTRID NANOFLY(ANR-19-ASTR-0023)and French AID(Defense Innovation Agency).
文摘This article presents the design of a microfabricated bio-inspired flapping-wing Nnano Aaerial Vvehicle(NAV),driven by an electromagnetic system.Our approach is based on artificial wings composed of rigid bodies connected by compliant links,which optimise aerodynamic forces though replicating the complex wing kinematics of insects.The originality of this article lies in a new design methodology based on a triple equivalence between a 3D model,a multibody model,and a mass/spring model(0D)which reduces the number of parameters in the problem.This approach facilitates NAV optimisation by using only the mass/spring model,thereby simplifying the design process while maintaining high accuracy.Two wing geometries are studied and optimised in this article to produce large-amplitude wing motions(approximately 40^\circ),and enabling flapping and twisting motion in quadrature.The results are validated thanks to experimental measurements for the large amplitude and through finite element simulations for the combined motion,confirming the effectiveness of this strategy for a NAV weighing less than 40 mg with a wingspan of under 3 cm.
文摘This paper focuses on electrical fault diagnosis and operation and maintenance technology in property service electromechanical engineering.It details core diagnostic methods,application-oriented tools,predictive maintenance frameworks,and enhanced maintenance planning.It also explores wireless sensor networks,big data analytics,and design-phase applications.Case studies in construction and operation phases are presented.Challenges like legacy system retrofitting are noted,and future potential in quantum sensing and edge AI is discussed.
基金Beijing Academy of Science and Technology (BJAST) supported this worksupported by the Financial Program of BJAST (Nos. 24CE-BGS-02, 24CA010-01, and 23CB106)
文摘Cells live in a multiphysics-coupled microenvironment in vivo,in which electric fields(EFs)and mechanical cues are the most essential induction signals.The regulatory effects of EFs and stiffness on cells have been independently demonstrated.However,how cells respond to electromechanical coupling cues remains mysterious.In this study,an electro-stiffness-coupled chip system was designed and fabricated,freely integrating and precisely controlling EF strength and the mechanical stiffness applied to cells across the physiological spectrum.Utilizing the innovative bioreactor,it was observed that electromechanical coupling stimulations can shape cancer cell morphology and cytoskeleton into a unique anteroposterior polarization state and orient cancer cell migration in a voltage-dependent manner through cytoskeleton-associated mechanisms.Moreover,the mechanical stiffness regulated cancer cell susceptibility to EFs,and the orientation effect of EFs on cells required a stiffness threshold.Furthermore,transforming growth factor-β1 suppressed the orientation of cancer cells induced by electromechanical coupling signals and showed a splitting effect on the directionality and velocity of cancer cell migration,indicating a comprehensive cross-talk of biochemical–electromechanical signals.Together with the dual-physical bioreactor we designed,these findings provide a robust and convenient platform for exploring cellular responses to electro-stiffness coupling signals,reveal the biophysical mechanisms of cell polarization and migration from the perspective of electromechanical coupling,and lay a promising foundation for biophysical-based cell manipulation and therapeutic interventions.
基金The National Natural Science Foundation of China(No. 60974116 )the Research Fund of Aeronautics Science (No.20090869007)Specialized Research Fund for the Doctoral Program of Higher Education (No. 200902861063)
文摘In order to effectively control the working state of the gyroscope in drive mode, the drive characteristics of the micro electromechanical system （MEMS） gyroscope are analyzed in principle. A novel drive circuit for the MEMS gyroscope in digital closed-loop control is proposed, which utilizes a digital phase-locked loop （PLL） in frequency control and an automatic gain control （AGC） method in amplitude control. A digital processing circuit with a field programmable gate array （FPGA） is designed and the experiments are carried out. The results indicate that when the temperature changes, the drive frequency can automatically track the resonant frequency of gyroscope in drive mode and that of the oscillating amplitude holds at a set value. And at room temperature, the relative deviation of the drive frequency is 0.624 ×10^-6 and the oscillating amplitude is 8.0 ×10^-6, which are 0. 094% and 18. 39% of the analog control program, respectively. Therefore, the control solution of the digital PLL in frequency and the AGC in amplitude is feasible.
基金Project supported by the National Basic Research Program （973） of China （No. 2007CB512100） and the National Natural Science Foun- dation of China （Nos. 81171421 and 61101046）
文摘In this study, the effects of cardiac fibroblast proliferation on cardiac electric excitation conduction and mechanical contraction were investigated using a proposed integrated myocardial-fibroblastic electromechanical model. At the cellular level, models of the human ventricular myocyte and fibroblast were modified to incorporate a model of cardiac mechanical contraction and cooperativity mechanisms. Cellular electromechanical coupling was realized with a calcium buffer. At the tissue level, electrical excitation conduction was coupled to an elastic mechanics model in which the finite difference method （FDM） was used to solve electrical excitation equations, and the finite element method （FEM） was used to solve mechanics equations. The electromechanical properties of the proposed integrated model were investigated in one or two dimensions under normal and ischemic pathological conditions. Fibroblast proliferation slowed wave propagation, induced a conduction block, decreased strains in the fibroblast proliferous tissue, and increased dispersions in depolarization, repolarization, and action potential duration （APD）. It also distorted the wave-front, leading to the initiation and maintenance of re-entry, and resulted in a sustained contrac- tion in the proliferous areas. This study demonstrated the important role that fibroblast proliferation plays in modulating cardiac electromechanical behaviour and which should be considered in planning future heart-modeling studies.
文摘An electromechanical nonlinear model of rotor system of electric machine is built.Respondance curves in parameter excited nonlinear vibration of this system caused by electromagnetic forces are investigated.Further more,the analysis reveals the effects of various electromagnetic and mechanical parameters on resonances, and some valuable results are obtained.The analytical result of this paper provides electric machine with the condition of 1/2 subharmonic resonance under the electromechanical electromagnetic forces.Electromagnetic forces apparently affect the stability zone, and both linear term and nonlinear term can excite parametric resonance.The revealed dynamic phenomena provide some new theories and active methods for the fault recognition of electric machine and the defination of stability range,and the theoretical bases for qualitatively controlling the stable operating state of rotors.
基金supported by the National Natural Science Foundations of China(Nos.51305248,51577112)Shanghai Natural Science Foundation of China(No.13ZR1416900)the Training Project for Young Teachers in Shanghai Colleges and Universities(No.ZZSD13051)
文摘An electroaeroelastic model for wind energy harvesting using piezoelectric generators is presented.The flow field is mapped in detail.The force which the fluid flow exerts on the generator is formulated.The output voltage levels generated from the mechanical strain within the piezoelectric elements are determined.An analytical model is developed with consideration of the interactions between the fluid,solid and electric.Various analytical results are obtained,such as flow velocity contour and pressure contour for the flow,moving trajectories,stress contour and output voltage of the harvester.A prototype is fabricated and tested.The simulation result is close to the experimental result.The model developed in this paper can predict the performance and behavior of different energy harvesters.And it also can be used as a design tool for optimizing the performance of the harvester.
文摘The growing need for renewable energy and zero carbon dioxide emissions has fueled the development of thermoelectric generators with improved power generating capability.Along with the endeavor to develop thermoelectric materials with greater figures of merit,the geometrical and structural optimization of thermoelectric generators is equally critical for maximum power output and efficiency.Green energy strategies that are constantly updated are a viable option for addressing the global energy issue while also protecting the environment.There have been significant focuses on the development of thermoelectric modules for a range of solar,automotive,military,and aerospace applications in recent years due to various advantages including as low vibration,great reliability and durability,and the absence of moving components.In order to enhance the system performance of the thermoelectric generator,an artificial neural network(ANN)based algorithm is proposed.Furthermore,to achieve high efficiency and system stability,a buck converter is designed and deployed.Simulation and experimental findings demonstrate that the suggested method is viable and available,and that it is almost similar to the real value in the steady state with the least power losses,making it ideal for vehicle exhaust thermoelectric generator applications.Furthermore,the proposed hybrid algorithm has a high reference value for the development of a dependable and efficient car exhaust thermoelectric generating system.
