作者:
Zhang, Yu-tingWang, Zhen-chunMinist Educ
Intelligent Control Syst & Intelligent Equipment E Qinhuangdao 066004 Hebei Peoples R China Yanshan Univ
Key Lab Ind Comp control Engn Qinhuangdao 066004 Hebei Peoples R China
Modeling the electromagnetic rail launch is a critical aspect that provides solid theoretical support for the design and optimization of launch systems. This paper comprehensively considers factors such as armature sh...
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Modeling the electromagnetic rail launch is a critical aspect that provides solid theoretical support for the design and optimization of launch systems. This paper comprehensively considers factors such as armature shape, rail shape, and the skin effect of current to establish a dynamic electromagnetic field model for an H-shaped armature in electromagnetic rail launch. To achieve efficient solutions, an adaptiverecursive numerical analysis method is proposed. This method recursively segments the integration intervals of various variables and employs adaptive Simpson's numerical integration for regression once the integration nodes are determined. This successfully enables the rapid resolution of the dynamic electromagnetic field model, yielding a time-varying inductance gradient. Subsequently, the Runge-Kutta method is used to calculate the velocity and displacement curves of the armature. Experimental validation of the model indicates a 2.28% error in the calculated muzzle velocity of the armature and a maximum error of 4.48% during the launch process. These results strongly validate the proposed model and the adaptiverecursive numerical analysis method, providing strong evidence for theoretical analysis in electromagnetic launch technology.
Purpose This paper attempts to develop an efficient algorithm to solve the inverse problem of identifying constitutive parameters in VFG (viscoelastic functionally graded) materials/structures. Design/methodology/appr...
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Purpose This paper attempts to develop an efficient algorithm to solve the inverse problem of identifying constitutive parameters in VFG (viscoelastic functionally graded) materials/structures. Design/methodology/approach An adaptive recursive algorithm with high fidelity is developed to acquire the derivatives of displacements with respect to constitutive parameters, which are required for the accurate and stable gradient based inverse analysis. A two-step strategy is presented in the process of identification, by which the unknown parameters can be separately identified and the scale and complexity of the inverse VFG problem are reduced. At each step, the process of identification is treated as an optimization problem that is solved by the Levenberg-Marquardt method. Findings The solution accuracy of forward problems and derivatives of displacements can be stably achieved with different step sizes, and constitutive parameters of homogenous/regional-inhomogeneous VFG materials/structures can be effectively and accurately identified. By examining the reliability, resolution, impacts of reference information and noisy data, the effectiveness of the proposed approach is numerically verified via three numerical examples. Originality/value An adaptive recursive algorithm is developed for derivatives computing with high fidelity, providing a solid platform for the sensitivity analysis and thereby a two-step strategy in conjunction with Levenberg-Marquardt method is presented in the process of identification. Consequently, an effective algorithm is developed to identify constitutive parameters of homogenous/regional-inhomogeneous VFG materials/structures.
Introduction: Magnetically controlled shape memory alloy (MSMA) actuators take advantages of their large deformation and high controllability. However, the intricate hysteresis nonlinearity often results in low positi...
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Introduction: Magnetically controlled shape memory alloy (MSMA) actuators take advantages of their large deformation and high controllability. However, the intricate hysteresis nonlinearity often results in low positioning accuracy and slow actuator response. Methods: In this paper, a modified Krasnosel'skii-Pokrovskii model was adopted to describe the complicated hysteresis phenomenon in the MSMA actuators. adaptive recursive algorithm was employed to identify the density parameters of the adopted model. Subsequently, to further eliminate the hysteresis nonlinearity and improve the positioning accuracy, the model reference adaptive control method was proposed to optimize the model and inverse model compensation. Results: The simulation experiments show that the model reference adaptive control adopted in the paper significantly improves the control precision of the actuators, with a maximum tracking error of 0.0072 mm. Conclusions: The results prove that the model reference adaptive control method is efficient to eliminate hysteresis nonlinearity and achieves a higher positioning accuracy of the MSMA actuators.
Compared with the least-mean-square algorithm, the least mean pth power algorithm shows a better robustness performance against impulsive noises such as the alpha-stable noises. However, it still exhibits slow converg...
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Compared with the least-mean-square algorithm, the least mean pth power algorithm shows a better robustness performance against impulsive noises such as the alpha-stable noises. However, it still exhibits slow convergence rate and high kernel misadjustment. To overcome this drawback, a novel recursive logarithmic least mean pth (RLLMP) algorithm is proposed for the Volterra system identification under alpha-stable noise environments. Instead of minimizing the pth power, the new algorithm aims to minimize the pth logarithmic cost, which makes it more robust against impulsive interferences. Furthermore, to enhance tracking performance, an improved variable forgetting factor (IVFF) algorithm (IVFF-RLLMP) is proposed, which is based on the robust estimation of outliers. Simulation results are presented to demonstrate the improved performance of the RLLMP and IVFF-RLLMP.
To improve the performance of the sidelobe canceller, a method using adaptive three-dimension polarization filter is proposed to suppress the target signal in the auxiliary antenna. It uses three orthogonally polariza...
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ISBN:
(纸本)9781424424238
To improve the performance of the sidelobe canceller, a method using adaptive three-dimension polarization filter is proposed to suppress the target signal in the auxiliary antenna. It uses three orthogonally polarization channels in the auxiliary antenna, Through the adaptive polarization filtering adjusting the receiving polarization vector of antenna to be orthogonal with that of the target signal, the target portion can be suppressed possibly, and the interference portion can be retained. then the output signal can be obtained by adopting the algorithm of adaptive sidelobe canceller. At last, the simulation results prove the validity of the method.
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