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911.
Miao LL Li HX Yu M Zhao W Gong WJ Gao J Ren ZG Wang HF Lang JP 《Dalton transactions (Cambridge, England : 2003)》2012,41(12):3424-3430
Treatment of [CuCl(2)(bppyH(2))] (1, bppyH(2) = 2,6-di(1H-pyrazol-3-yl)pyridine) with 2 equiv. of AgNO(3) in DMF gave rise to a binuclear Cu(II) complex [Cu(2)(bppyH)(2)(NO(3))(2)] (bppyH = 2-(pyrazol-3-yl)-6-(pyrazolate)pyridine) (2). Complex 2 was characterized by elemental analysis, IR and single crystal X-ray diffraction. Complex 2 has a dimeric structure in which the two Cu(ii) centers are bridged by a couple of the in situ-generated bppyH(-) anions. Each Cu(II) center is further coordinated by one O atom of a NO(3)(-) anion and three N atoms of one bppyH(-) anion. Complex 2 exhibited a higher catalytic activity in the polymerization of methyl methacrylate (MMA) than the precursor complex 1. Even though the ratio of catalyst to MMA was raised up to 1 : 1500, the PDI for 2 (reaction time was fixed at 4 h) is 1.63 and the conversion is up to 72%. The effects of solvent, reaction temperature and the ratio of MMA to catalyst were also investigated. 相似文献
912.
滑模变结构控制是一种在宽工作范围具有快速响应和高稳定性的鲁棒控制, 因而被广泛地应用于逆变器控制中. 滑模控制的逆变器本质上是一种由非线性控制方式控制的时变非线性系统, 具有复杂的动力学行为. 本文以基于脉冲宽度调制的滑模变结构控制的一阶H桥逆变器为例, 首先观察不同滑模变结构控制器参数下系统的输出波形, 发现了一种多种倍数的倍周期同时存在的新型分岔现象; 其次, 使用频闪映射方法建立系统的离散迭代模型, 并利用折叠图法分析输出波形. 通过分析可知系统不能以这种新型分岔为道路通向混沌. 此外, 在工程应用中十分关心系统稳定性, 但是由于滑模变结构控制器的非线性特性, 常规解析方法都已不再适用于对系统进行分析, 而图解法又难以满足精度要求. 因此, 本文提出了一种新的适用于滑模变结构控制的逆变器的快变尺度稳定性的判断依据, 经验证该判据可以准确地判断系统是否处于稳定运行状态, 进而为滑模变结构控制器的参数设计提供可靠依据.
关键词:
H桥逆变器
滑模变结构控制
新型分岔
稳定性判据 相似文献
913.
Tyler Jarvis William E. Lang Gretchen Rimmasch Julie Rogers Erin D. Summers Nansen Petrosyan 《代数通讯》2013,41(12):4533-4566
ABSTRACT We list all possible configurations of singular fibers on rational elliptic surfaces in characteristic three and prove that no others exist. In total, we find 267 distinct configurations. Configurations of purely multiplicative fibers in characteristic three are compared to those in characteristics zero and two. 相似文献
914.
AMS(MOS): 46F10 We give an integral representation formula for entire holomorphic solutions of exponential type to systems of convolution equations. 相似文献
915.
This paper addresses consistency and stability of W-methods up to order three for nonlinear ODE-constrained control problems with possible restrictions on the control. The analysis is based on the transformed adjoint system and the control uniqueness property. These methods can also be applied to large-scale PDE-constrained optimization, since they offer an efficient way to compute gradients of the discrete objective function. 相似文献
916.
Buckling and vibration analysis of functionally graded magneto-electro-thermo-elastic (FGMETE) circular cylindrical shell are carried out in the present work. The Hamilton principle, higher order shear deformation theory, constitutive equation considering coupling effect between mechanical, electric, magnetic, thermal are considered to derive the equations of motion and distribution of electrical potential, magnetic potential along the thickness direction of FGMETE circular cylindrical shell. The influences of various external loads, such as axis force, temperature difference between the bottom and top surface of shell, surface electric voltage and magnetic voltage, on the buckling response of FGMETE circular cylindrical shell are investigated. The natural frequency obtained by present method is compared with results in open literature and a good agreement is obtained. 相似文献
917.
918.
S. Zitta K. Stoschitzky R. Zweiker T. Lang H. Holzer F. Mayer 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(2):190-207
A method of adapting two-compartment models to dynamic marker concentration profiles for the determination of renal clearance and of its acute changes due to protein ingestion in patients with essential hypertension is described. In 9 healthy controls glomerular filtration rates (GFR) and effective renal plasma flows (ERPF) (ml/min/1.73 m2; means +/- sd) rose significantly tested pairwise from 118.2 +/- 13.9 to 139.5 +/- 30.9, p = 0.023 and from 503.2 +/- 75.6 to 558.3 +/- 96.2, p = 0.013, respectively. Four patients with mild hypertension and mean arterial pressure (MAP) of 106 +/- 3 mmHg (duration = 13.8 +/- 10.3 years) showed rises in GFR (73.9 +/- 14.7 to 83.6 +/- 17.4, p = 0.034) after stimulation, whereas 6 patients with a MAP of 119 +/- 3 mmHg (duration = 17.5 +/- 13.7 years) exhibited ‘paradoxical’ decreases in GFR (113.3 +/- 18.7 to 103.0 +/- 14.3, p = 0.037). The ERPFs showed nonsignificant changes in the first group of patients (277.8 +/- 52.6 to 323.9 +/- 42.8), whereas the second group revealed increases in ERPF (430.7 +/- 134.5 to 502.3 +/- 113.1, p = 0.013). All patients had normal serum creatinine levels. The study demonstrates that modern system identification of kinetic experiments, but not traditional techniques relying on steady-state data, allow one to detect such dynamic alterations as measures of renal functional reserve. 相似文献
919.
We have developed a surface-enhanced Raman scattering (SERS) nanosensor firstly for Ag ions and Ag nanoparticles detection based on 2-mercaptoisonicotinic acid (2MNA)-functionalized Au nanoparticles. Ag(+) can coordinate with 2MNA resutling in a variation of its SERS spectrum, which is used as a criterion to determine Ag(+) in a solution. This sensor exhibits a detection limit no more than 25 nM and has a high selectivity against other metal ions. More importantly, it can be directly applied in real sample detection. 相似文献
920.
Reduced-order models are applied to the laminar vortex-shedding flow around a circular cylinder. The models rely on approximations of the solutions in the space spanned by a set of POD or CVT reduced basis vectors, which are computed from snapshots of a numerical solution. To enable the computation of drag and lift forces, the modeling of the velocity and pressure is realized via a one-way coupling. A comparison of the results of the CVT and POD reduced-order models is presented. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献