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261.
The dehydrogenation of CH4 on the Co(1 1 1) surface is studied using density functional theory calculation (DFT). It is found that CH4 is favored to dissociate to CH3 and then transforms to CH2 and CH by sequential dehydrogenation, and CH4 activation into CH3 and H is the rate-determining step on the Co(1 1 1) surface. CH2 is quite unstable on Co(1 1 1) surface. CH dehydrogenation into C and H is difficult. CH3 and H prefer to adsorb on 3-fold hollow hcp and fcc sites, and CH2, CH and C prefer to adsorb on hcp sites. 相似文献
262.
J. Zuo 《Applied Surface Science》2010,256(23):7096-241
Ag nanostructures on TiO2 films were deposited by RF magnetron sputtering under variable deposition parameters, such as DC potential, RF-power and total pressure. The concentration, shape, and distribution of the deposited nanostructures and continuous Ag films on thin films of TiO2 can be tailored by careful variation of the deposition parameters. Controllable clusterlike, islandlike and film Ag structures on TiO2 film were obtained, respectively. DC potential was found as an appropriate parameter to tailor the change of Ag nanostructure and the overall Ag amount. The compositions, nanostructures and morphologies of nanocomposite films appreciably influence the optical response. 相似文献
263.
A two-dimensional periodic Schrödingier operator is associated with every Lagrangian torus in the complex projective plane \({\mathbb C}P^2\). Using this operator, we introduce an energy functional on the set of Lagrangian tori. It turns out this energy functional coincides with the Willmore functional \(W^{-}\) introduced by Montiel and Urbano. We study the energy functional on a family of Hamiltonian-minimal Lagrangian tori and support the Montiel–Urbano conjecture that the minimum of the functional is achieved by the Clifford torus. We also study deformations of minimal Lagrangian tori and show that if a deformation preserves the conformal type of the torus, then it also preserves the area, i.e., preserves the value of the energy functional. In particular, the deformations generated by Novikov–Veselov equations preserve the area of minimal Lagrangian tori. 相似文献
264.
Let {(ξni, ηni), 1 ≤ i ≤ n, n ≥ 1} be a triangular array of independent bivariate elliptical random vectors with the same distribution function as(S_1, ρ_n S_1 +(1-ρ_n~2S_2)~(1/2)), ρn∈(0, 1), where(S1, S2) is a bivariate spherical random vector. For the distribution function of radius (S_1~2+ S_2~2)~(1/2) belonging to the max-domain of attraction of the Weibull distribution, the limiting distribution of maximum of this triangular array is known as the convergence rate of ρn to 1 is given. In this paper,under the refinement of the rate of convergence of ρn to 1 and the second-order regular variation of the distributional tail of radius, precise second-order distributional expansions of the normalized maxima of bivariate elliptical triangular arrays are established. 相似文献
265.
In this paper, we study the k-quasi-M-hyponormal operator and mainly prove that if T is a k-quasi-M-hyponormal operator, then \(\sigma _{ja}(T)\backslash \{0\}=\sigma _{a}(T)\backslash \{0\}\), and the spectrum is continuous on the class of all k-quasi-M-hyponormal operators; let \(d_{AB}\in B(B(H))\) denote either the generalized derivation \(\delta _{AB}= L_{A}-R_{B}\) or the elementary operator \(\Delta _{AB} =L_{A}R_{B}- I\), we show that if A and \(B^{*}\) are k-quasi-M-hyponormal operators, then \(d_{AB}\) is polaroid and generalized Weyl’s theorem holds for \(f(d_{AB})\), where f is an analytic function on \(\sigma (d_{AB})\) and f is not constant on each connected component of the open set U containing \(\sigma (d_{AB})\). In additon, we discuss the hyperinvariant subspace problem for k-quasi-M-hyponormal operators. 相似文献
266.
We introduce a special class of T-matrices, say, T
1, T
2, T
3, and T
4 satisfying
T1T4-T2T3=(T1T2-T2T3)¢ T_1T_4-T_2T_3=(T_1T_2-T_2T_3)' 相似文献
267.
传统的混沌控制方法大多需要获知混沌系统的模型知识, 但是工业实际中系统的参数经常是未知的,与此同时系统建模过程当中经常会不可避免地存在未建模的动态不确定性, 这种情况下常规的混沌控制方法不能取得优化的控制性能指标.为解决此问题, 提出了一类基于无模型方法的混沌系统自适应控制算法.该算法基于数据驱动, 无需混沌系统的先验知识, 无需训练过程, 在线调整参数较少, 是一种低成本的控制器.数学证明了该控制系统的稳定性, 仿真结果说明了这种理论的有效性.
关键词:
混沌控制
自适应
无模型
数据驱动 相似文献
268.
Yijing Wang Xiaomeng Shi Zhiqiang Zuo Michael Z.Q. Chen Yitian Shao 《Nonlinear Analysis: Real World Applications》2013,14(1):807-814
This paper is concerned with the finite-time stability problem for switched systems subject to both nonlinear perturbation and impulse effects. The average dwell time approach, combined with the algebraic matrix theory, is utilized to derive a criterion guaranteeing that the state trajectory does not exceed a certain threshold over a pre-specified finite-time interval. The requirement that at least one subsystem should be stable to ensure asymptotic stability is no longer necessary. Moreover, the finite-time stability degree could be positive, which is a relaxed condition for asymptotic stability. A numerical example is presented to illustrate the effectiveness of the proposed method. 相似文献
269.
A master-slave visual surveillance system is composed of one fish-eye panoramic camera and one dynamic pan-tilt-zoom (PTZ) dome camera. In order to make PTZ dome camera zoom into all targets of interest in panoramic image, the fish-eye panoramic camera is fixed inclining towards the gravity direction, which may cause more obvious distortion. This paper proposed a novel method for the distortion correction of captured panoramic image based on the midpoint circle algorithm (MCA). The method uses incremental calculation of decision parameters to determine the pixel positions along a circle circumference, and both of the vertical and horizontal are rectilinearised. Experimental results show that our correction method based on MCA is efficient and effective. In particular, due to its low computational cost, our method can be applied on embedded camera platform without any extra hardware resources. 相似文献
270.
K. Matsuta T. Minamisono M. Mihara M. Fukuda Shengyun Zhu Y. Masuda K. Hatanaka Daqing Yuan Yongnan Zheng Yi Zuo Ping Fang Dongmei Zhou T. Ohtsubo T. Izumikawa S. Momota D. Nishimura R. Matsumiya A. Kitagawa S. Sato M. Kanazawa M. Torikoshi T. Nagatomo Y. Nojiri T. Suzuki Xizhen Zhang J. R. Alonso T. J. M. Symons S. Kawasaki S. C. Jeong Y. Watanabe K. Minamisono 《Hyperfine Interactions》2013,220(1-3):21-28
We report our studies in various fields of Physics through nuclear moments utilizing the β-NMR technique, including material sciences, nuclear structures and fundamental symmetries. Especially, we focus on the recent progress in the studies on the electronic structure in Pt through Knight shifts of various impurities, lattice locations of impurities, electric field gradients, the analysis of nuclear spin in terms of its components, anomaly in the spin expectation value for 9C-9Li mirror pair, the G-parity conservation law, and the Ramsey resonance on UCN for future neutron EDM measurements. 相似文献
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