针对一类具有一般不确定转移概率的T-S模糊半马尔可夫跳变系统(S-MJS)设计了一个降维观测器,它可以同时估计系统状态、执行器故障及传感器故障, 并且能够完全解耦外部干扰。利用线性矩阵不等式的形式, 给出了观测器存在的充分条件, 并证明误差系统可在有限时间内稳定。最后通过数值仿真验证了所提方法的有效性。
半马尔可夫跳变系统 故障估计 降维观测器 模糊系统 Semi-Markovian Jump System (S-MJS) fault estimation reduced-order observer fuzzy system
上海工程技术大学电子电气工程学院, 上海 201000
针对一类含有未知输入和测量噪声的线性离散时间马尔可夫跳变系统, 设计了一种降维观测器,可以对系统中的未知输入和测量噪声同时解耦。以线性矩阵不等式的形式给出观测器存在的充分条件, 并确保误差系统有限时间随机稳定; 之后利用一种代数重构的思想实现了未知输入的估计; 最后通过数值仿真验证了所提方法的有效性。
离散系统 未知输入估计 降维观测器 马尔可夫跳变系统 discrete-time system unknown input estimation reduce-order observer Markovian Jump System (MJS)
研究一类具有未知输入的线性离散时间马尔可夫跳变系统的降维观测器设计问题。首先, 针对含有未知输入的线性系统设计一种新的降维观测器, 通过构造观测器增益矩阵, 使得未知输入完全解耦。此外, 通过线性矩阵不等式形式给出观测器存在的充分条件, 并证明观测器误差在有限时间意义上是稳定的, 保证了估计的良好暂态性。最后, 通过实例验证了所提方法的有效性和可行性。
马尔可夫跳变系统 降维观测器 有限时间稳定 未知输入 Markov jump system reduced-order observer finite time stability unknown input
Author Affiliations
Abstract
Advanced Semiconductor Laboratory, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
We demonstrate a neural network capable of designing on-demand multiple symmetry-protected bound states in the continuum (BICs) in freeform structures with predefined symmetry. The latent representation of the freeform structures allows the tuning of the geometry in a differentiable, continuous way. We show the rich band inversion and accidental degeneracy in these freeform structures by interacting with the latent representation directly. Moreover, a high design accuracy is demonstrated for arbitrary control of multiple BIC frequencies by using a photonic property readout network to interpret the latent representation.
Photonics Research
2021, 9(4): 04000B96
Author Affiliations
Abstract
1 Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
3 College of Physics Science & Technology, Laboratory of Optoelectronic Materials and Detection Technology, Guangxi Key Laboratory for the Relativistic Astrophysics, Guangxi University, Nanning 530004, China
4 Advanced Micro-Fabrication Equipment Inc., Shanghai 201201, China
5 Zhe Jiang Bright Semiconductor Technology Co., Ltd., Jinhua 321026, China
6 Advanced Semiconductor Laboratory, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
We report on the carrier dynamic and electronic structure investigations on AlGaN-based deep-ultraviolet multiple quantum wells (MQWs) with lateral polarity domains. The localized potential maximum is predicted near the domain boundaries by first-principle calculation, suggesting carrier localization and efficient radiative recombination. More importantly, lateral band diagrams of the MQWs are proposed based on electron affinities and valance band levels calculated from ultraviolet (UV) photoelectron spectroscopy. The proposed lateral band diagram is further demonstrated by surface potential distribution collected by Kelvin probe microscopy and the density-of-state calculation of energy bands. This work illustrates that lateral polarity structures are playing essential roles in the electronic properties of III-nitride photonic devices and may provide novel perspective in the realization of high-efficiency UV emitters.
Photonics Research
2020, 8(6): 06000812
Author Affiliations
Abstract
1 King Abdullah University of Science and Technology (KAUST), Advanced Semiconductor Laboratory, Thuwal 23955-6900, Saudi Arabia
2 School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
3 Technische Universität Berlin, Institute of Solid State Physics, Berlin D-10623, Germany
Semiconductor UV photonics research has emerged as one of the most heavily invested areas among semiconductor photonics research due to numerous crucial applications such as sterilization, sensing, curing, and communication. The feature issue disseminates nine timely original research and two review papers from leading research groups and companies, covering most frontiers of the semiconductor UV photonics research, from epitaxy, device physics and design, nanostructures, fabrication, packaging, reliability, and application for light-emitting diodes, laser diodes, and photodetectors.
Photonics Research
2019, 7(12): 120SUVP1
Author Affiliations
Abstract
1 Hubei Key Laboratory of Intelligent Wireless Communications, College of Electronics and Information Engineering, South-Central University for Nationalities, Wuhan 430074, China
2 King Abdullah University of Science and Technology (KAUST), Advanced Semiconductor Laboratory, Thuwal 23955-6900, Saudi Arabia
Connected-annular-rods photonic crystals (CARPCs) in both triangular and square lattices are proposed to enhance the two-dimensional complete photonic bandgap (CPBG) for chalcogenide material systems with moderate refractive index contrast. For the typical chalcogenide-glass–air system with an index contrast of 2.8:1, the optimized square lattice CARPC exhibits a significantly larger normalized CPBG of about 13.50%, though the use of triangular lattice CARPC is unable to enhance the CPBG. It is almost twice as large as our previously reported result [
IEEE J. Sel. Top. Quantum Electron.22, 4900108 (2016)IJSQEN1077-260X10.1109/JSTQE.2015.2422997]. Moreover, the CPBG of the square-lattice CARPC could remain until an index contrast as low as 2.24:1. The result not only favors wideband CPBG applications for index contrast systems near 2.8:1, but also makes various optical applications that are dependent on CPBG possible for more widely refractive index contrast systems.
Photonics Research
2018, 6(4): 04000282
Author Affiliations
Abstract
1 Advanced Semiconductor Laboratory, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
2 Photonics Laboratory, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
A nanowire (NW) structure provides an alternative scheme for deep ultraviolet light emitting diodes (DUV-LEDs) that promises high material quality and better light extraction efficiency (LEE). In this report, we investigate the influence of the tapering angle of closely packed AlGaN NWs, which is found to exist naturally in molecular beam epitaxy (MBE) grown NW structures, on the LEE of NW DUV-LEDs. It is observed that, by having a small tapering angle, the vertical extraction is greatly enhanced for both transverse magnetic (TM) and transverse electric (TE) polarizations. Most notably, the vertical extraction of TM emission increased from 4.8% to 24.3%, which makes the LEE reasonably large to achieve high-performance DUV-LEDs. This is because the breaking of symmetry in the vertical direction changes the propagation of the light significantly to allow more coupling into radiation modes. Finally, we introduce errors to the NW positions to show the advantages of the tapered NW structures can be projected to random closely packed NW arrays. The results obtained in this paper can provide guidelines for designing efficient NW DUV-LEDs.
Light-emitting diodes Quantum-well, -wire and -dot devices Photonics Research
2018, 6(5): 05000457
1 总装驻西安地区军代室, 陕西 西安 710043
2 西安应用光学研究所, 陕西 西安 710065
传统的Hough变换检测方法由于计算量大、实时性差以及受图像噪声影响较大等缺点, 不能较为准确地进行实际道路的检测。鉴于此, 提出了一种改进的基于Hough变换的道路图像检测方法。该方法在对实际道路形态建模分析的基础上, 针对有/无路面标识以及存在其他干扰因素的结构化道路, 均能有效剔除实际道路图像中的干扰因素并准确检测出道路边缘, 且检测时间均在200 ms以内。
道路检测 Hough变换 地面无人车辆 road detection Hough transform unmanned ground vehicle
