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Yasser Kiani 《热应力杂志》2013,36(12):1495-1518
Based on the uncoupled thermoelasticity assumptions, axisymmetric thermally induced vibrations of a circular plate made of functionally graded materials (FGMs) are analyzed. Each thermomechanical property of the circular plate is assumed to be functions of temperature and thickness coordinate. Solution of the transient one-dimensional heat conduction equation with the arbitrary type of time-dependent boundary conditions is carried out employing the central finite difference method combined with the Crank–Nicolson time marching scheme. Afterwards, with the establishment of the associated Hamilton's principle and the accountancy of the von Kármán type of geometrical non-linearity, the motion equations are obtained with the aid of the conventional multi-term Ritz method. The solution of highly coupled non-linear motion equations is obtained utilizing a hybrid iterative Newton–Raphson–Newmark scheme. After validating the developed computer code, some parametric studies are accomplished to show the influences of various involved parameters. It is shown that temperature dependency, geometrical non-linearity, plate thickness, power law index, and the type of thermal in-plane and out-of-plane mechanical boundary conditions, all affect the temporal evolution of plate characteristics. 相似文献
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分析了以肢剪力墙在地震载荷作用下弹塑性各个阶段的变形和受力特点,提出了双肢剪力墙材料的非线性的差分方程分析方法,使用该方法对双肢剪力墙进行了计算,计算结果与试验结果吻合较好。 相似文献
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差压传感器非线性特性研究 总被引:1,自引:0,他引:1
介绍了一种智能差压传感器,针对影响传感器准确度的输出—输入非线性问题进行了研究。采用了BP神经网络来建立差压传感器的输出—输入模型,网络模型采用了三层结构,输出—输入层各自采用了一个神经元,将神经网络的均方误差目标值设定为10-6,并在MATLAB中进行了仿真,经训练得到的输出—输入模型的非线性误差可以达到±0.032%。通过与多项式拟合方法和最小二乘直线拟合方法所得结果进行比较,结果表明:采用BP神经网络方法对提高智能差压传感器的测量准确度具有参考价值。 相似文献
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In this article, two robust adaptive control schemes are investigated for a class of completely non-affine pure-feedback non-linear systems with input non-linearity and perturbed uncertainties using radial basis function neural networks (RBFNNs). Based on the dynamic surface control (DSC) technique and using the quadratic Lyapunov function, the explosion of complexity in the traditional backstepping design is avoided when the gain signs are known. In addition, the unknown virtual gain signs are dealt with using the Nussbaum functions. Using the mean value theorem and Young's inequality, only one learning parameter needs to be tuned online at each step of recursion. It is proved that the proposed design method is able to guarantee semi-global uniform ultimate boundedness (SGUUB) of all signals in the closed-loop system. Simulation results verify the effectiveness of the proposed approach. 相似文献
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The optical scanner is one of the most important components in free-space optical communications,airborne and space-based lidars,adaptive optics,and so on.The performance of an optical scanner is frequently limited by the presence of mechanical resonances.This paper presents an analog notch filter with adjustable function to reject the mechanical resonances of the optical scanner.First of all,the structure and work principle of the piezoelectric optical scanner are introduced.Furthermore,the frequency sweep method based on virtual instruments is used to gain the natural frequency of the piezoelectric optical scanner.Then,the notch filters in series are used to reduce the oscillation of the scanner at the resonance frequencies.A variety of scanning experiments were carried out.After the introduction of the notch filter,the non-linearity was reduced to±1.1% from ±2.1%.The linearity performance was greatly improved. 相似文献
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