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针对多股螺旋弹簧加工机床张力控制系统的非线性特性及存在干扰的问题,提出了基于支持向量回归(Support Vector Regression, 简称SVR)的有效抑制噪声的控制算法;即在基于SVR的逆动力学建模中采取非线性松弛因子替代线性松弛因子,抑制噪声在建模过程中的影响,提高建模精度;把系统逆模型作为前馈控制器,构成伪线性系统,PID控制器作为反馈控制,组成有效抑制噪声的复合控制算法;实验结果表明,这种改进基于SVR的复合控制方式在多股螺旋弹簧张力控制系统中具有较好的控制精度和鲁棒性。 相似文献
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使用悬挂螺旋弹簧牵动磁体振动,在线圈内产生感应电动势的方法,将弹簧的机械振动转换为电磁振动,使弹簧机械振动的各参量转换为一一对应的电磁参量,用DIS数字化信息系统测量各电磁参量,从而展开分析研究。 相似文献
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闭圈螺旋弹簧截面中的应力分布的计算可以由考虑下面的这样一个弹性力学的轴对称问题来进行:设一圆环(半径为R)截段处于一对通过环的中心的相等而方向相反且垂直于环的平面(z=0)的力P作用之下,这两个力在圆环的所有截面上产生同样的力偶M_t=PR(图1)。在较粗的螺旋弹簧情况,截面的尺度与环的直径比较起来并非可忽略地小。规诺尔(Gohner),谢卜德(Shepherd等人都考虑过这一类问题的近似解。 相似文献
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本文利用瑞利法来计算弹簧丝大小均匀、弹性符合胡克定律的圆锥形密圈螺旋弹簧的等效质量,并用实验加以检验,最后从能量角度分析了它的物理意义. 相似文献
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本文利用弹簧纵向振动方程及其边界条件,求出了决定圆锥形螺旋弹簧的等效质量的超越方程;在弹簧本身质量远小于与其联结物体质量的情况下,得到弹簧等效质量的计算公式,并讨论了它的适用范围 相似文献
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弹簧的质量、材料及其几何性质对弹簧谐振子角频率的影响 总被引:2,自引:0,他引:2
本文从能量的观点研究了圆柱形密圈螺旋弹簧谐振子系统,导出了用弹簧质量、材料及其几何性质等量描写的谐振动微分方程,从而得到以上各量对弹簧谐振子角频率的影响.这一结果还给出了弹簧刚度系数与材料及其几何性质的联系. 相似文献
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《大学物理》1985,(5)
一、力学 1对不稳定的约束实位移不是虚位移中的一个吗! 梅凤翔《力学与实践》84年6卷5期51页 (以下年、卷、期、页顺序相同) 2.动量矩定理适用条件和动量矩矩心问题 樊勇坚 《力学 与实践》84.6.5.52. 3.平面运动刚体对速度瞬心的动量矩方程 唐红度《力学 与实践》84.6.5.56. 4.广义虚位移原理 舒仲周 《力学与实践》84.6.5.57.5.密圈螺旋弹簧的变形分析 陈文淼等《力学与实践》 84.6.6.49. 6.梁受二次分布力弯曲的多项式解答 林木《力学与实 践》84.6.6.50。 7.弹性常数关系的矩阵推导方法 潘家强《力学与实践》 84.6.6.52. 8.极坐标中应… 相似文献
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在教学中若能把一些物理实验的科学性与趣味性融为一体,则有助于提高学生对物理的兴趣,激发对本学科的学习热情。为此介绍一则有关超重与失重的演示实验,其装置简单、效果明显,既具有科学性,又饶含趣味性。一.实验装置:如附图所示,1.铁架台;2.横铁杆;3.螺旋弹簧(规格:单位伸长量33~40mm/100gf,允许载荷700gf, 相似文献
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The dynamics of spiral waves under the influences of periodic mechanical deformation are studied. Here, the mechanical deformation propagating along the medium with phase differences are considered. It is found that weak mechanical deformation may lead to resonant drift of spiral waves. The drift direction and velocity can be changed by the wave length of the deformation. Strong mechanical deformation may result in breakup of spiral waves. The characteristics of breakup are discussed. The critical amplitudes are determined by two factors, i.e. the wave length and frequency of the periodic mechanical deformation. When the wave length of mechanical deformation is comparable to the spiral wave, simulation shows that the critical amplitude is substantially increased. As the frequency of the mechanical deformation is around 1.5 times of the spiral wave, the critical amplitudes are minimal. 相似文献
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采用Greenberg-Hastings元胞自动机模型研究机械形变对心肌组织中螺旋波动力学行为的影响.数值模拟表明:对于规则网格下的稳定螺旋波,在生理性机械形变作用下,螺旋波发生漫游但不破碎;在病理性机械形变作用下,螺旋波会发生持续漫游、漫游后消失和破碎进入螺旋波湍流态三种变化.通过对比发现机械形变的振幅变化率对螺旋波的影响较大,而机械形变的角频率对螺旋波的影响较小.结合数值模拟,对心前区受到猛烈撞击会出现心颤致死及耐力运动员在发生心动过速后比一般人员更容易恢复正常进行解释. 相似文献
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本文首先通过理论推导,建立了计其本身质量的旋转体弹簧所满足的波动方程,运用能量法给出振动弹簧的有效弹性常数。然后导出了弹簧本身质量忽略不计的极限情况下弹簧有效弹性常数的表达式。最后运用泛函极值原理简单讨论了在固定材料以及外形下弹簧圈的疏密如何分布,使弹簧达到最大有效弹性常数的最优化模型。 相似文献
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Jiang-Xing Chen Gui-Na Wei Bing-Wei Li Jiang-Rong Xu 《Central European Journal of Physics》2008,6(3):427-433
The motion of spiral waves in excitable media driven by a weak pacing around the spiral tip is investigated numerically as
well as theoretically. We presented a Bifurcations diagram containing four types of the spiral motion induced by different
frequencies of pacing: rigidly rotating, inward-petal meandering, resonant drift, and outward-petal meandering spiral. Simulation
shows that the spiral resonantly drifts when the frequency of pacing is close to that of the spiral rotation. We also find
that the speed and direction of the drift can be efficiently controlled by means of the strength and phase of the local pacing,
which is consistent with analytical results based on the framework of the weak deformation approximation.
相似文献
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We study the motion of a spiral wave controlled by a local periodic forcing imposed on a region around the spiral tip in an excitable medium. Three types of trajectories of spiral tip are observed: the epicycloid-like meandering, the resonant drift, and the hypocycloid-like meandering. The frequency of the spiral is sensitive to the local periodic forcing. The dependency of spiral frequency on the amplitude and size of local periodic forcing are presented. In addition, we show how the drift speed and direction are adjusted by the amplitude and phase of local periodic forcing, which is consistent with a theoretical analysis based on the weak deformation approximation. 相似文献
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A. G. Manjavidze V. A. Barnov L. I. Jorjishvili S. V. Sobolevskaya 《Technical Physics》2008,53(3):380-382
The properties of a cylindrical spiral spring of nitinol (shape-memory alloy) are studied. When this spring is used as a working element in a rotary martensitic engine, the appearance of the two-way shape-memory effect in it is shown to decrease the engine operation efficiency. 相似文献
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S.P. LELES.K. MAITI 《Journal of sound and vibration》2002,257(3):559-583
The method of detection of location of crack in beams based on frequency measurements is extended here to short beams, taking into account the effects of shear deformation and rotational inertia through the Timoshenko beam theory and representing the crack by a rotational spring. Methods for solving both forward (determination of frequencies of beams knowing the crack parameters) and inverse (determination of crack location knowing the natural frequencies) problems are included. A method to estimate crack extension from a change in the first natural frequency is presented. Both numerical and experimental studies are given to demonstrate the accuracy of the methods. The accuracy of the results is quite encouraging. 相似文献
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在理论上,用2种方法研究了弹簧自重对形变量的影响,并用简单实验对该结论进行了论证,最终得出弹簧自身重力作用产生的形变量为x=G/2k的结论.应用该结论对习题进行了修正. 相似文献
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We study a chain of harmonically interacting atoms confined between two sinusoidal substrate potentials, when the top substrate is driven through an attached spring with a constant velocity. This system is characterized by three inherent length scales and closely related to physical situations with confined lubricant films. We show that, contrary to the standard Frenkel-Kontorova model, the most favorable sliding regime is achieved by choosing chain-substrate incommensurabilities belonging to the class of cubic irrational numbers (e.g., the spiral mean). At large chain stiffness, the well known golden mean incommensurability reveals a very regular time-periodic dynamics with always higher kinetic friction values with respect to the spiral mean case. 相似文献