Kinetic model based on molecular mechanism for action potential

The Hodgkin-Huxley model for action potentials has been widely used but was not built on a microscopic description of the neuronal membrane. Through molecular dynamics simulations, the molecular mechanism of the channel currents is becoming clear. However, the quantitative link between molecular mechanism and action potential remains to be elucidated. Here, a kinetic model for action potential based on the molecular mechanism of the channel currents is proposed. Using it, the experimental observations about action potential are reproduced quantitatively and explained based on molecular mechanism. We find that the accumulation of Na+ ions near exit of the electivity filter is the dominant event to cause the refractory period of the Na+ channel and the types of the channel currents depend on its rate constants. The channel inductance represents the inertia of the channel to retain a certain ion binding state, the channel resistances include ones against state transition and charge transfer

Effects of Casimir force on multi-field coupled nonlinear vibration of orthotropic micro film

In this paper, the nonlinear dynamics equations of a multi-field coupled orthotropic micro film are presented. The Krylov-Bogoliubov-Mitropolsky (KBM) method is used to solve the equations. The multi-fields coupled nonlinear resonant frequencies of a micro film are analyzed. The effects of Casimir force and nonlinear parameter on nonlinear resonant frequencies and vibration amplitudes are investigated. A resonant film is designed and produced. Based on the principle of electrostatic excitation and capacitance detection, the resonant frequency of the micro film is detected. It illustrates that the Casimir force has an important influence on the resonant micro film frequencies and should be considered with a small initial clearance

Electromechanical fluidic coupled vibrations for micro film considering the van der Waals force

In this paper, a multi-fields coupled dynamic equation of the micro film is presented which includes mechanical force, the van der Waals force, electrostatic force and fluidic damping force. The multi-fields coupled free vibration of the micro film is investigated. The multi-fields coupled forced response of the micro film near natural frequency is analyzed. The multi-fields coupled natural frequencies of the micro film and their changes along with system parameters are discussed. Amplitude frequency characteristics of the micro film under the coupled fields are given

Electromechanical coupled nonlinearity and critical velocity for electromagnetic railgun

The nonlinear electromagnetic force can change the critical velocity of the projectile for a railgun. It corresponds to the resonance state in railgun. Here, the nonlinear electromechanical coupled dynamics equations for the railgun are proposed. Based on it, the equation of the nonlinear critical velocity of the projectile is given and the effects of the electromagnetic nonlinearity on the critical velocity of the projectile are investigated. Besides it, the effects of the fire velocity on the nonlinear critical velocity are studied as well. Results show that the critical velocity of the railgun system increases when the electromagnetic nonlinearity is considered, and the nonlinear critical velocity is influenced by the system parameters such as rail current, rail thickness, rail distance, etc. A FEM analysis package, ANSYS, is used to simulate dynamics performance of the railgun system and illustrate the analytical results about critical velocities of the railgun system. The results can be used to design dynamics performance of the railgun system

Four field coupled dynamics for a micro resonant gas sensor

In a micro resonant gas sensor, the electrostatic excitation is used widely. For a micro resonant gas sensor with electrostatic excitation, four physical fields are involved. In this paper, for the micro resonant gas sensor, the four-field coupled dynamics equation is proposed. It includes mechanical force field, chemical density field, electrostatic force field, and the van der Waals force field. Using the method of multiple scales, the coupled dynamics equation is resolved. The effects of the four physical fields on the natural frequencies for the micro resonant gas sensor are investigated. Results show that the effects of the Van der Waals force on the natural frequencies of the micro resonant gas sensor depend on the mechanical parameters and the bias voltages; the sensitivity of the natural frequencies to the gas adsorption depends on the mechanical parameters, the bias voltages, and the Van der Waals force

High-Resolution Remotely Sensed Small Target Detection by Imitating Fly Visual Perception Mechanism

The difficulty and limitation of small target detection methods for high-resolution remote sensing data have been a recent research hot spot. Inspired by the information capture and processing theory of fly visual system, this paper endeavors to construct a characterized model of information perception and make use of the advantages of fast and accurate small target detection under complex varied nature environment. The proposed model forms a theoretical basis of small target detection for high-resolution remote sensing data. After the comparison of prevailing simulation mechanism behind fly visual systems, we propose a fly-imitated visual system method of information processing for high-resolution remote sensing data. A small target detector and corresponding detection algorithm are designed by simulating the mechanism of information acquisition, compression, and fusion of fly visual system and the function of pool cell and the character of nonlinear self-adaption. Experiments verify the feasibility and rationality of the proposed small target detection model and fly-imitated visual perception method

Detect to Learn: Structure Learning with Attention and Decision Feedback for MIMO-OFDM Receive Processing

The limited over-the-air (OTA) pilot symbols in multiple-input-multiple-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) systems presents a major challenge for detecting transmitted data symbols at the receiver, especially for machine learning-based approaches. While it is crucial to explore effective ways to exploit pilots, one can also take advantage of the data symbols to improve detection performance. Thus, this paper introduces an online attention-based approach, namely RC-AttStructNet-DF, that can efficiently utilize pilot symbols and be dynamically updated with the detected payload data using the decision feedback (DF) mechanism. Reservoir computing (RC) is employed in the time domain network to facilitate efficient online training. The frequency domain network adopts the novel 2D multi-head attention (MHA) module to capture the time and frequency correlations, and the structural-based StructNet to facilitate the DF mechanism. The attention loss is designed to learn the frequency domain network. The DF mechanism further enhances detection performance by dynamically tracking the channel changes through detected data symbols. The effectiveness of the RC-AttStructNet-DF approach is demonstrated through extensive experiments in MIMO-OFDM and massive MIMO-OFDM systems with different modulation orders and under various scenarios.Comment: Accepted to IEEE Transactions on Communication