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121.
Samik Mukherjee Nima Nateghi Robert M. Jacobberger Etienne Bouthillier Maria de la Mata Jordi Arbiol Toon Coenen Dhan Cardinal Pierre Levesque Patrick Desjardins Richard Martel Micheal S. Arnold Oussama Moutanabbir 《Advanced functional materials》2018,28(8)
Van der Waals epitaxy is an attractive alternative to direct heteroepitaxy where the forced coherency at the interface cannot sustain large differences in lattice parameters and thermal expansion coefficients between the substrate and the epilayer. Herein, the growth of monocrystalline InP on Ge and SiO2/Si substrates using graphene as an interfacial layer is demonstrated. Micrometer‐sized InP crystals are found to grow with interfaces of high crystalline quality and with different degrees of coalescence depending on the growth conditions. Some InP crystals exhibit a polytypic structure, consisting of alternating zinc‐blende and wurtzite phases, forming a type‐II homojunction with well (barrier) width of about 10 nm. The optical properties, investigated using room temperature nano‐cathodoluminescence, indicate the signatures of the direct optical transitions at 1.34 eV across the gap of the zinc‐blende phase and the indirect transitions at ≈ 1.31 eV originating from the alternating zinc‐blende and wurtzite phases. Additionally, the InP nanorods, found growing mainly on the graphene/SiO2/Si substrate, show optical transition across the gap of the wurtzite phase at ≈ 1.42 eV. This demonstration of InP growth on graphene and the correlative study between the structure and optical properties pave the way to develop hybrid structures for potential applications in integrated photonic and optoelectronic devices. 相似文献
122.
In an analog TV based passive radar, the mismatched filter for only visual signals will produce a high SNR loss. In this paper, a method for the mismatched filter for both visual and audio signals is proposed. First, the chosen frequency of the visual and audio signal is synthesized in a consecutive range of frequency, and then the mismatched filter for the synthesized signal is applied. This method can utilize all the power of analog TV. What's more, according to simulation results, it can be found that when the same peak sidelobe ratio is acquired, a much lower SNR loss can be acquired by the proposed mismatched filter based on visual and audio signals than the one based only on visual signals. 相似文献
123.
Jeang‐Lin Chang 《国际强度与非线性控制杂志
》2012,22(8):841-857
》2012,22(8):841-857
This paper addresses the problem of designing a dynamic output feedback sliding mode control algorithm for linear MIMO systems with mismatched parameter uncertainties along with disturbances and matched nonlinear perturbations. Once the system is in the sliding mode, the proposed output‐dependent integral sliding surface can robustly stabilize the closed‐loop system and obtain the desired system performance. Two types of mismatched disturbances are considered and their effects on the sliding mode are explored. By introducing an additional dynamics into the controller design, the developed control law can guarantee that the system globally reaches and is maintained on the sliding surface in finite time. Finally, the feasibility of the proposed method is illustrated by numerical examples. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
124.
The lattice mismatch and stereographic maps of the prevailing epitaxial relationships for HTS on perovskite-type substrates have been determined as a function of substrate orientation. The compositions and orientations of substrates for creating perfect single crystalline HTS layers are presented. The misfit may be decreased to nearly 0 for LnGaO3 and SrLnGaO4, where Ln is a rare-earth ion having a large ionic radius, by optimal choice of substrate orientation. For the LnAlO3 and (Ca, Sr)LnAlO4 families, good lattice match is lacking. The best compounds among them are LaAlO3 and SrLaAlO4. Because of the weak orientation dependence of the misfit for SrTiO3 and the LnAlO3 family, the main purpose of substrate orientation optimization is to suppress polysynthetic twinning.Paper presented at the 1st International Conference Material Science of High-Temperature Superconductors, Kharkov, Ukraine, 5–9 April 1993. 相似文献
125.
This paper investigates the stabilization and disturbance rejection for a class of fractional-order nonlinear dynamical systems with mismatched disturbances. To fulfill this purpose a new fractional-order sliding mode control (FOSMC) based on a nonlinear disturbance observer is proposed. In order to design the suitable fractional-order sliding mode controller, a proper switching surface is introduced. Afterward, by using the sliding mode theory and Lyapunov stability theory, a robust fractional-order control law via a nonlinear disturbance observer is proposed to assure the existence of the sliding motion in finite time. The proposed fractional-order sliding mode controller exposes better control performance, ensures fast and robust stability of the closed-loop system, eliminates the disturbances and diminishes the chattering problem. Finally, the effectiveness of the proposed fractional-order controller is depicted via numerical simulation results of practical example and is compared with some other controllers. 相似文献
126.
Yaote Chang 《International journal of control》2013,86(10):2028-2039
Based on the Lyapunov stability theorem, a methodology of designing the block backstepping controller for a class of multi-input systems with matched and mismatched perturbations is proposed in this article. Some adaptive mechanisms are embedded both in the virtual input controller and in the backstepping controllers so that not only are the mismatched perturbations suppressed, but also part knowledge of the upper bound of perturbation is not required. Finally, an example of stabilising the control-moment-gyro devices is presented to demonstrate the feasibility of the proposed methodology. 相似文献
127.
128.
基于密度泛函理论对铜上外延生长的金刚石薄膜的几何结构及其能量特征进行了计算,计算结果表明外延生长金刚石薄膜的几何参数与体金刚石的几何参数相似(特别是(111)面);在铜多晶基体的〈111〉方向更有利于金刚石薄膜的外延生长. 相似文献
129.
Based on mode-coupled theory, a Bragg grating assisted mismatched fiber coupler is analyzed theoretically. At the same time, a detailed numerical analysis on transmission characteristics of the coupler is carried out when it considers the arcs of two fibers in the coupling region of the coupler or not, and the optimized design on the Bragg grating assisted mismatched fiber coupler for wavelength-division multiplexing/ demultiplexing is proposed. 相似文献
130.