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一类非线性变系数波动方程系统的能量衰退
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作者 兰杰 《吕梁教育学院学报》 2018年第2期110-112,共3页
文章应用黎曼流形的方法,及半群理论讨论系统(1),分析一个在边界反馈上带有声音边界条件和时变迟滞项的非线性变系数波动方程系统的能量衰退情况。这个内容具有广泛的实际应用价值及意义,是近些年应用数学研究的热点话题。
关键词 非线性波动系统 能量函数 时变迟滞
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基于摆线刀齿轨迹的未变形铣屑厚度分析 被引量:1
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作者 窦炜 崔岗卫 +1 位作者 袁胜万 何晓聪 《机械工程学报》 EI CAS CSCD 北大核心 2019年第7期234-242,共9页
利用动态变化的未变形铣屑厚度与铣削力之间的相互作用关系,研究铣削过程的动态特性是铣削过程建模的基本思路。未变形铣屑厚度的值取决于相继切入工件的刀刃在工件上留下的切削痕迹之间的相对位置关系。处于切削状态的刀刃与前一齿尖... 利用动态变化的未变形铣屑厚度与铣削力之间的相互作用关系,研究铣削过程的动态特性是铣削过程建模的基本思路。未变形铣屑厚度的值取决于相继切入工件的刀刃在工件上留下的切削痕迹之间的相对位置关系。处于切削状态的刀刃与前一齿尖所经过的摆线运动轨迹相交,以其方位角与前一刀齿过同一交点时的方位角之差为辅助变量,建立满足铣屑形成条件的运动学超越方程。若该辅助变量已知,则可进一步求出铣削迟滞参数及未变形铣屑厚度。基于这一思路,给出两种新的求取铣屑厚度的方法:一种是将原方程转化为解描述辅助变量动态变化的微分方程,采用数值方法求得其数值解;另一种是以辅助变量的线性函数近似原方程中的三角函数,采用近似解析法解出其显式表达式。仿真结果表明:对于当前制造业普遍采用的铣削参数,所提近似解析法可以满足实际应用的精度要求,并且与现有摆线铣屑厚度模型相比数学表达式更为简洁;所提数值法不需要循环迭代求解超越方程,非常适合嵌入到对分析精度和运算效率有较高要求的铣削过程仿真或稳定性预测算法。 展开更多
关键词 铣削过程 摆线刀齿轨迹 未变形切屑厚度 时变迟滞 数值方法 近似解析解
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Oscillation control for n-dimensional congestion control model via time-varying delay 被引量:4
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作者 ZHANG Shu XU Jian 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第8期2044-2053,共10页
Time delay or round trip time (RTT) is an important parameter in the model of Internet congestion control. On the one hand, the delay may induce oscillation via the Hopf bifurcation. In the present paper, a congestion... Time delay or round trip time (RTT) is an important parameter in the model of Internet congestion control. On the one hand, the delay may induce oscillation via the Hopf bifurcation. In the present paper, a congestion control model of n dimensions is considered to study the delay-induced oscillation. By linear analysis of the n-dimensional system, the critical delay for the Hopf bifurcation is obtained. To describe the relation between the delay and oscillation analytically, the method of multiple scales (MMS) is employed to obtain the bifurcating periodic solution. On the other hand, it can be understood that the oscillation will increase the risk of congestion for the network system. To avoid the congestion derived from the oscillation, a new control scheme is proposed by perturbing the delay periodically. Particularly, according to our study, it is possible to control the oscillation by perturbing only one of the n delays. This provides a practical scheme for the oscillation control in the real network system. By MMS, the strengths of the perturbations are predicted analytically such that the oscillation disappears. To give an example, an eight-dimensional model is studied in detail. The analytical results are in good agreement with the numerical simulations. 展开更多
关键词 internet congestion control high-dimensional system Hopf bifurcation time-varying delay method of multiple scales
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Exponential synchronization for neural networks with mixed time-varying delays via periodically intermittent control 被引量:1
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作者 Pinghua Yang Xinan Tang 《International Journal of Biomathematics》 2014年第2期103-120,共18页
This paper deals with exponential synchronization for a class of neural networks with mixed time-varying delays via periodically intermittent control. Some novel and effective exponential synchronization criteria are ... This paper deals with exponential synchronization for a class of neural networks with mixed time-varying delays via periodically intermittent control. Some novel and effective exponential synchronization criteria are derived by constructing Lyapunov functional and applying some analysis techniques. These results presented in this paper generalize and improve many known results. Finally, this paper presents an illustrative example and uses the simulated results to show the feasibility and effectiveness of the proposed scheme. 展开更多
关键词 Exponential synchronization neural networks mixed time-varying delays periodically intermittent control.
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