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61.
Xi‐Sheng Zhan Zhi‐Hong Guan Rui‐Quan Liao Fu‐Shun Yuan 《Asian journal of control》2012,14(6):1608-1616
The analysis method of optimal tracking performance is proposed for multiple‐input multiple‐output (MIMO) linear time‐invariant (LTI) systems under disturbance rejection. An H2 criterion of the error signal between the output of the plant and the reference signal is used as a measure for the tracking performance. Spectral factorization is applied to obtain the optimal solution of the system tracking error. The explicit expressions are derived for this minimal tracking error with respect to random reference signals under disturbance rejection. It is shown that the nonminimum phase zeros, the zero direction, the unstable poles, the pole direction of a given plant, statistical characteristics of the reference input signal, and disturbance signal have a negative effect on a feedback system's ability to reduce the system error with disturbance rejection. The results show that the optimal tracking performance will further be damaged because of disturbance rejection. Some typical examples are given to illustrate the theoretical results. 相似文献
62.
Sun Wei Wang Cong Bu Dexu Liu Shengnan Wu Baoqiang Ouyang Minghua 《International Journal of Control, Automation and Systems》2012,10(2):430-436
This paper presents a novel online learning visual servo controller integrating the FCMAC with proportion controller for the
control of position of manipulator end-effector. Since the FCMAC has good learning capability and fast learning speed, and
can save much computer memory space by fuzzy processing of input space division and memory unit activation, it is used to
develop an adaptive control law by learning the relationship between the image feature errors and manipulator input, and the
aim of online learning of the FCMAC is to minimize the output of proportion controller. Furthermore, the FCMAC has no need
for models of robot manipulator and image feature extraction, so that the capability of proposed controller for tasks under
uncertain environment can be improved. Finally, the proposed controller is proved to be effective by the experiment, and compared
with BP neural network. 相似文献
63.
方柱体镦粗的两个新力学模型 总被引:8,自引:1,他引:8
在对平板间镦粗圆柱体的研究[1,2,3]基础上,进一步对普通平板间的方柱体镦粗,进行了工程力学的分析,提出了二个新力学模型,并进行了实验验证。这为形成新的拔长理论[4,6]奠定了力学基础。 相似文献
64.
给出实际热输入值是正确求解焊接热弹塑性问题和焊接残余应力与变形问题的前提;因而,准确地确定热源有效利用率η,在焊接力学的发展中是一个急待解决的命题。本文推荐采用的“测试计算法”提供了一个能够准确、简捷地求得η值的新途径。引入被焊材料的熔化潜热系数后,给出了线热源加热焊缝金属至熔化温度(处于液态)时的实际热有效利用率ηt 的表达式。在四种不同类型的薄板材料上进行了钨极氩弧焊试验,测试计算结果与理论值相符合。理论推导与试验结果均证明,形成焊缝所需要的线能量的无量纲数值等于焊缝金属熔化热有效利用率ηt 的倒数。文中给出的焊接规范参数选择原则也适用于符合线热源条件的其它熔焊热源。η值不但与焊接工艺方法、规范参数有关,而且也随被焊材料的热物理特性不同而异。 相似文献
65.
Anion exchange membranes (AEMs) are one of the core components of AEM fuel cells. A series of poly(vinyl alcohol)/polyquaternium-10 (PVA/PQ-10) AEMs with semi-interpenetrating networks (s-IPNs) are prepared by a simple solution-casting method using glutaraldehyde (GA) as a cross-linking agent. Subsequently, the prepared PVA/PQ-10 cross-linked membranes are characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, mechanical analysis, water uptake and swelling ratio tests, ion exchange capacity (IEC) tests, ionic conductivity measurements, and oxidative/alkaline stability tests. The effects of the mass ratio of PVA and PQ-10 and the amount of cross-linking agent GA on the performance of the PVA/PQ-10 cross-linked membranes are systematically explored. The results show that the cross-linked PVA/PQ-10 AEMs have high IEC and low water uptake and swelling ratio, and its maximum ionic conductivity can reach 79.37 mS cm–1 at 80 °C. In addition, the PVA/PQ-10 cross-linked membrane has good oxidative and alkaline stability under optimal preparation conditions. These results may provide valuable insights toward more effective scheme designs and new, simple preparation methods for AEMs with s-IPN structures. 相似文献
66.
Sajjad Muhammad Asif Sana Ullah Guan Linlin Jiao Yangjing Jiang Yuhan Zhang Linlin Wen Jia Zhang Shuyu Lin Yuting Zhang Shuangshuang Ding Zhiwei Ren Yang Zhou Xiaowei Hu Wanbiao Liu Zhu 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(11):4440-4441
Journal of Inorganic and Organometallic Polymers and Materials - The original version of this article unfortunately contained mistakes. In line 9 of the abstract, 5% should read as 2%. The... 相似文献
67.
研究了Mg-Sr牺牲阳极的显微组织和电化学性能的特征.结果表明,Mg-Sr牺牲阳极的晶粒尺寸随Sr含量的增加而减小;当Sr质量分数为0.19%时,电流效率达到58.56%,开路电位达到-1.735 VSCE;Sr的质量分数再增加,Mg-Sr阳极的电流效率降低,开路电位正移.研究认为,Sr的质量分数为0.19%时,晶界析出的Mg17Sr2相(弱阴极相)和α-Mg基体(阳极相)组成电偶对,阻碍了阳极晶间腐蚀,减少了晶粒大块脱落, 且Sr能够和Mg、Fe形成弱阴极性化合物降低Fe的危害,电流效率升高,同时晶粒细化,晶界面积变大,杂质相分布更均匀,开路电位负移;Sr含量大于0.19%时,过量的Mg17Sr2相作为阴极相加大了阳极的自腐蚀,电流效率下降,开路电位正移. 相似文献
68.
一种Cr—Mn—Mo—B低碳低合金钢的热变形行为 总被引:2,自引:0,他引:2
利用THERMCMASTOR-Z热处理机对一种Cr-Mn-Mo-B钢的热变形行为进行了研究,绘制了真应力-应变曲线,得到了各变形工艺参数之间的定量关系,得出试验用钢的Q值为373.7kj/mol。在此基础上给出了试验用钢的动态再结晶图,试验发现,试验用钢900℃以上变形后,在奥氏体区冷过程中发生静态再结晶与晶粒长大,相变前晶粒尺寸与变形条件Z的关系:drec=2.88×10^4×Z^-0.205。 相似文献
69.
The oxidation behavior of a single-crystal (SC) Ni-base superalloy was studied over the temperature range from 1000–1150°C and analysed by TGA, XRD, EDAX, and SEM. The results indicated that the SC Ni-base superalloy exhibited parabolic oxidation kinetics, which were controlled by the growth of the inner -Al2O3 layer. A mixed scale formed on the SC Ni-base superalloy after prolonged oxidation. The scale consisted of an outer layer of spinel, a sublayer of mainly -Al2O3 with small amount of spinel adjoined by a very thin and even discontinuous layer of CrTaO4-rich oxide, and an inner -Al2O3 layer. The inner -Al2O3 layer provided good protection. No internal oxides or nitrides were observed below the inner -Al2O3 layer after 1000 hr at 1000°C, and after 200 hr at 1100 and 1150°C. 相似文献
70.