Abstract:The complex dynamics of neuronal firing in the brain provide a crucial basis for highorder cognitive functions and the emergence of pathological states. Astrocytes play a key role in regulating neural activity on a timescale of seconds, influencing nervous system function through multiple mechanisms such as modulating neurotransmitter levels, ion concentrations, and energy metabolism, as well as responding to exogenous disturbances (e.g., temperature fluctuations and noise). Based on recent biological experimental studies on astrocytes, this paper reviews the latest progress in dynamic modeling of astrocyteregulated neural firing and elaborates on the contributions of astrocytes to synaptic information transmission and synaptic plasticity at the neural network level. This study offers theoretical support for an indepth understanding of astrocytes’roles in cognitive functions such as memory and attention. Additionally, the paper discusses the influence of astrocytes on the dynamic behavior of abnormal neural firing in neurological diseases (e.g., epilepsy), thereby providing potential clinical value for the prevention and treatment of related neurological diseases. Finally, considering current developments in artificial intelligence (AI) technology, the paper outlines future research directions for more comprehensively uncovering the regulatory role of astrocytes in nervous system dynamics through the integration of experimental data and dynamic modeling.

Abstract:Time scales are defined as any nonempty closed subset of the real number field, which unifies the treatment of continuous and discrete systems. In this paper, the Herglotztype Vacco dynamics of nonholonomic systems are extended to the time scales, and its Noether symmetry and conservation law are investigated. Firstly, based on the Herglotz variational principle on time scales, the Herglotztype Vacco dynamics equations on time scales are established. Secondly, according to the invariance of HamiltonHerglotz action on time scales under infinitesimal transformations, the Noether symmetry of Herglotztype Vacco dynamics of nonholonomic systems on time scales is defined, and the corresponding Noether identities are presented. Finally, the Noether’s theorem of Herglotztype Vacco dynamics for nonholonomic systems on time scales is proven, and the corresponding conserved quantities are provided. At the conclusion of the paper, two examples are presented to demonstrate the results of theoretical analysis.

Abstract:A numerical model of a Nextel/Kevlarfilled protective structure under hypervelocity impact is developed to investigate its structural response and optimize its configuration. Four key design parameters, namely the thicknesses of the front plate, Nextel and Kevlar layers, and rear plate, are chosen as variables. Latin hypercube sampling is employed to generate sample points, and highfidelity simulations are carried out using LSDYNA to obtain the projectile’s kinetic energy dissipation. A Kriging surrogate model is built to approximate the simulation response with reduced computational cost. Based on the surrogate, a multiobjective optimization using the NSGAII algorithm is performed, aiming to minimize the areal density and maximize energy dissipation. The optimized structure achieves a 2.56% reduction in areal density and a 1.91% increase in energy loss.

Abstract:Due to the severity and complexity of the working environment, turbine blades often experience fatigue failure and fracture damage under large vibration amplitude. In order to reduce the risk of fatigue failure of turbine blades, the underplatform dampers are typically employed to suppress the blade vibration. However, most experimental studies use weights and wires to simulate the application of normal load, which cannot quantitatively and precisely apply normal load. To address this problem, this paper proposes a precise loading method for underplatform dampers. Moreover, experimental studies on the vibration reduction effects of underplatform dampers are conducted. The study investigates the influence of parameters such as normal load, excitation amplitudes, and friction area ratios on the vibration reduction characteristics of dampers. Finally, a MATLABPythonABAQUS joint simulation method is used to analyze the vibration effect of the underplatform damper, which validates the effectiveness of the proposed experimental method.

Abstract:Modal localization, owing to its high sensitivity to structural perturbations, has demonstrated unique advantages in the field of microelectromechanical systems (MEMS) sensors. However, traditional modal localization resonators mostly rely on frequencyswept excitation, which can only stimulate a single mode and suffer from poor amplitude stability in openloop operation as well as instability issues in dual closedloop driving. These limitations hinder the realization of realtime measurement and fast response. To address this challenge, this paper investigates a coupled doublebeam resonator and proposes a modal localization sensing method based on broadband noise excitation. The proposed method drives multiple modes simultaneously using broadband noise and extracts the variation characteristics of the modal energy distribution through power spectral density analysis, enabling efficient and sensitive perturbation detection. A coupled dynamic model of a dual beam MEMS resonator under broadband noise excitation is established, and numerical simulations together with experimental studies are conducted to comparatively analyze the modal responses under frequencyswept and noisedriven excitations. The results show that the modal localization effect under broadband noise driven conditions is highly consistent with that under harmonic driving, thereby verifying the feasibility and effectiveness of the proposed method.

Abstract:This paper investigates the nonlinear dynamic behavior of PVC gel cylindrical shell under multiple electromechanical parameters. First, the nonlinear vibration equations of the cylindrical shell structure are theoretically derived based on the Gent hyperelastic material model, and the response and stability of the system under static and dynamic voltages are subsequently discussed. Studies on static voltage reveal that the cylindrical shell exhibits a critical voltage threshold because of the positive feedback effect of the electric field. Exceeding this threshold leads to instability and damage. And the critical voltage is greatly influenced by thickness and boundary conditions. When dynamic sinusoidal voltage is applied, the system shows complex nonlinear vibration characteristics. Through analyses of the timedomain responses, phase trajectories,Poincaré sections, bifurcation characteristics and Lyapunov exponents, the presence of periodic vibrations and bifurcation phenomena is confirmed. Numerical simulations show that multifrequency resonance occurs when the excitation frequency changes. Such resonance induces amplitude jumps, which leads to structural damage. By combining nonlinear verification at the same frequency with phase diagram analysis, it is shown that the vibration state has regular consistency under specific parameters. This finding confirms that the vibration response can be controlled by adjusting voltage parameters.

Abstract:This paper studies the dynamic response of wind turbine systems (WTS) under nonGaussian stochastic excitation. Firstly, considering the limitations of traditional Gaussian noise in representing the actual wind speed and system uncertainty, the αstable Lévy noise with heavy tail and pulse characteristics is introduced to establish a more practical WTS stochastic dynamical model. Secondly, based on the theory of stochastic differential, the fractional FokkerPlanckKolmogorov (FPK) equation corresponding to WTS under the excitation of αstable Lévy noise is derived, which precisely describes the evolution law of the transient probability density function (PDF) for the system state. Finally, to effectively solve the fractional partial differential equation, a physicsinformed neural networks (PINNs) framework is proposed, which takes the physical control equation as the constrained embedding loss function, and can directly learn the spacetime continuous PDF solution without grid discretization. Numerical experiments show that the PINNs solution is highly consistent with the Monte Carlo simulation results, which verifies the accuracy of this method in solving fractional FPK equations. Meanwhile, PINNs shows much higher computational efficiency than traditional Monte Carlo methods.

Abstract:Wind and rain loads exert a significant influence on the safety of the transmission towerline system. In this paper, the dynamic characteristics of the towerline coupling system in a 110 kV transmission line under wind and rain loads are analyzed. Firstly, the finite element model of a 110 kV transmission towerline system is established in Ansys software, and the modal analysis is carried out. Combined with the theory of Davenport wind speed spectrum and rain load, the windrain coupling load corresponding to the loading node is generated in Matlab. The dynamic response of the towerline system under this coupling load is studied, and the results of its dynamic response under different wind direction angles and with or without rain load are explored. The results show that the grounding wire increases the stiffness of the towerline system as a whole, but because of its strong ‘galloping effect’in the horizontal direction, the coupling effect in the horizontal direction and the alongline direction is different. The wind direction angle of 90 ° is the most unfavorable wind direction angle of the towerline system, and the dynamic response of the towerline system reaches the maximum value. In the case of rainfall of 20 mm/h, the dynamic response range of the towerline system will be increased by about 5 % ~10 % considering the rain load. The effect of rain load on a single tower is almost negligible, which mainly increases the dynamic response of the towerline system by aggravating the galloping effect’of the ground wire.

Abstract:In response to the challenge of efficient prediction of the dynamic behavior of the dovetailconnected bladed disk systems involving boundary nonlinearity, rotating effects, complex loads, etc., the fixed interface modal synthesis method is applied to the reducedorder modeling of a rotating dovetailconnected bladed disk system. By introducing thinlayer solid elements on both groove and tenon contact surfaces to capture interference behavior, and considering the rotationinduced stiffening and softening effects as well as the dovetail jointinduced local load action, the reduced systemlevel model including the disk substructure, dovetail joint zone, and blade substructure under aerodynamic excitation is then established. The influence of the modal truncation numbers of the blade and disk on the first three natural frequencies of the reduced system is discussed, and the effects of rotating speed and friction coefficient on the modal characteristics and vibration responses of both the full and reduced models are compared with each other. The results show that: (1) within the studied parameter range, the maximum deviation of the reduced model in predicting the first three natural frequencies compared to the full model does not exceed 0.6%, and the maximum deviation in predicting the critical speed does not exceed 0.1%; (2) the nonlinearity of the dovetail connection makes the response spectrum of the system to exhibit multiples of the excitation frequency, and a smaller friction coefficient induces slip between the tenon and the groove thus leading to a quasilinear component in the vibration response.