Stability analysis and H∞ control for hybrid complex dynamical networks with coupling delays

This paper formulates and studies a model of complex dynamical networks with switching topology and coupling delays. Based on the hybrid control and Lyapunov function, the stability and robust H_∞ control of such networks with impulsive and switching effects, which have not been studied before, are addressed with some criteria derived. Examples are given to illustrate the effectiveness of the theoretical results. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimal Performance in Tracking Stochastic Signal Under Disturbance Rejection

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.     

方柱体镦粗的两个新力学模型

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。     

同塔双回路供电同一变电站不同时停电设计技术方案的探讨

近年来随着城市或电网的发展,不少输电线路被提出改线,在需满足N-1要求的线路中进行改线时,如果不采取相应的技术措施,将出现N-2情况导致电网供电可靠性差的问题,本研究将探讨几种处理措施,以提高供电可靠性以保障电网改线的顺利进行.     

Correction to: Bismuth Yttrium Oxide (Bi3YO6), A New Electrode Material For Asymmetric Aqueous Supercapacitors

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...     

粉末冶金法制备云母/羟基磷灰石玻璃陶瓷

为了获得良好的可加工性和生物活性,采用粉末冶金法制备了云母/羟基磷灰石玻璃陶瓷.随着烧结温度的提高,材料的力学性能有所增加.在1100℃下、保温1.5 h可以获得材料的最佳力学性能,其相对密度、抗弯强度和断裂韧性分别为95%、124 MPa和2.1 MPa·m1/2.随着温度的提高,烧结过程中玻璃相的扩散速度加快并填充到剩余的孔隙中,使得材料的相对密度增加,从而提高了材料的抗弯强度.断裂韧性的提高来源于材料中高长径比的云母晶体相互交错的微观结构.     

Mg-Sr牺牲阳极显微组织和电化学性能的研究

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.     

一种Cr—Mn—Mo—B低碳低合金钢的热变形行为

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。     

Oxidation Behavior of a Single-Crystal Ni-Base Superalloy in Air—II: At 1000, 1100, and 1150°C

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.     

半导体硫化银纳米管的制备与光学性能

在以Triton X-100为表面活性剂形成的反相胶束体系中,成功地制备了半导体硫化银纳米管,管径88 nm～120nm、长度大于2.6 μm.X射线衍射测定表明,产物为纯单斜结构.紫外-可见光谱在275 nm处发现新的吸收峰,最大发射波长与体相材料相比,蓝移了38 nm.