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Photoluminescence from site-selected coupling between quantum dots and microtoroid cavities

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Chinese Optics Letters 2010年第7期8卷 709-712页

作者：吴晓伟邹长铃尉伟孙方稳郭光灿韩正甫 key laboratory of Quantum Information University of Science and Technology of China National Synchrotron Radiation laboratory University of Science and Technology of China

By using CdSe/ZnS quantum dots （QDs）, we study the effect of cavity quantum electrodynamics on the coupling of the microtoroid cavity. When with whispering gallery （WG） modes, the microtoroid cavity demonstrates high quality factor and small mode volume at visible wavelengths. Accordingly, fiber tapers allow QDs to adhere into the cavity and further permit the control of site-selected coupling. From the luminescence spectra, QDs are modulated effectively by cavity modes, Variable modulations are observed by changing QD coupling conditions. Therefore, based on experimental and theoretical research, strong and tunable Purcell enhancement can be realized by this system.

关键词： Luminescence Semiconductor quantum dots

A Bilayer High-Temperature Dielectric Film with Superior Breakdown Strength and Energy Storage Density

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nano-micro Letters 2023年第9期15卷 479-491页

作者： Jiang-Bo Ping Qi-Kun Feng Yong-Xin Zhang Xin-Jie Wang Lei Huang Shao-Long Zhong Zhi-Min Dang State key laboratory of Power system Department of Electrical EngineeringTsinghua UniversityBeijing 100084People’s Republic of China

The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time,including thin-film *** discharge energy density of thin-film capacitors that serves as one of the important types directly depends on electric field strength and the dielectric constant of the insulation ***,it has long been a great challenge to improve the breakdown strength and dielectric constant *** that boron nitride nanosheets(BNNS)possess superior insulation and thermal conductivity owing to wide band gap and 2-dimensional structure,a bilayer polymer film is prepared via coating BNNS by solution casting on surface of polyethylene terephthalate(PET)*** revealing the bandgap and insulating behavior with UV absorption spectrum,leakage current,and finite element calculation,it is manifested that nanocoating contributes to enhance the bandgap of polymer films,thereby suppressing the charge injection by redirecting their transport from *** to note that an ultrahigh breakdown field strength(~736 MV m^(−1)),an excellent discharge energy density(~8.77 J cm^(−3))and a prominent charge-discharge efficiency(~96.51%)are achieved concurrently,which is ascribed to the contribution of BNNS ultrathin *** addition,the modified PET films also have superior comprehensive performance at high temperatures(~120°C).The materials and methods here selected are easily accessible and facile,which are suitable for large-scale roll-to-roll process production,and are of certain significance to explore the methods about film modification suitable for commercial promotion.

关键词： Film capacitor Dielectric property Boron nitride nanosheets Surface coating Energy storage characteristics

Numerical experimental study on the potential climatic impacts oflarge-scale wind farms in China

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Advances in Climate Change Research 2019年第3期10卷 143-149页

作者： HUANG Jian-Bin LOU Peng-Kang SUN Hong-Wei LUO Yong ZHAO Zong-Ci Ministry o f Education key laboratory for Earth system Modeling Department o f Earth System ScienceTsinghua University100084BeijingChina

Wind energy has been rapidly developed in China during the past decades and the installed capacity has been the largest in the world. In the future, utilization of wind power is still expected to carry out in China mainly with a large-scale centralized layout. Here, we examine the potential climatic impacts of large-scale windfarms associated with deployment scale in China using numerical experiments, in which four deployment scenarios were designed. These four scenarios represented relatively small- (484 GW), medium- (2165 GW) and large-scale (3490 GW and 5412 GW) installed wind power capacities, respectively. Results showed that turbulent kinetic energy, wind velocity, and air temperature varied consistently within those windfarms with the largest changes in turbine hub heights. Moreover, the above relatively large- scale windfarms could induce regional wanning with a maximum of above 0.8 °C in North China. This regional warming may be linked to an anomalous circulation pattern with a negative pressure anomaly center in Northeast China and a positive pressure anomaly center in the middle and lower reaches of the Yangtze-Huaihe River Basin.

关键词： Climatic impact Large-scale windfarms Wind energy China WRF model

Distributed Model Predictive Control for Networked Plant-wide systems With Neighborhood Cooperation

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IEEE/CAA Journal of Automatica Sinica 2019年第1期6卷 108-117页

作者： Ting Bai Shaoyuan Li Yi Zheng the Department of Automation Shanghai Jiao Tong Universityand Key Laboratory of System Control and Information ProcessingMinistry of Education of China IEEE

For large-scale networked plant-wide systems composed by physically(or geographically) divided subsystems, only limited information is available for local controllers on account of region and communication restrictions. Concerning the optimal control problem of such subsystems, a neighbor-based distributed model predictive control(NDMPC) strategy is presented to improve the global system performance. In this scheme, the performance index of local subsystems and that of its neighbors are minimized together in the determination of the optimal control input, which makes the local control decision also beneficial to its neighboring subsystems and further contributes to improving the convergence and control performance of overall *** stability of the closed-loop system is proved. Moreover, the parameter designing method for distributed synthesis is ***, the simulation results illustrate the main characteristics and effectiveness of the proposed control scheme.

关键词： Distributed control model predictive control (MPC) neighborhood cooperation plant-wide systems

Mobility driven network slicing: an enabler of on demand mobility management for 5G

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The Journal of China Universities of Posts and Telecommunications 2017年第4期24卷 16-26页

作者： Wang Hucheng Chen Shanzhi Ai Ming Shi Yan State key laboratory of Networking and Switching technology Beijing University of Posts and Telecommunications State key laboratory of Wireless Mobile Communications China Academy of Telecommunications Technology

As different requirements on mobility support will be introduced by diversified communication scenarios in the fifth generation （5G）, on demand mobility management is put forward to simplify signaling process, reduce terminal power consumption, improve network efficiency and so on. In order to enable on demand mobility management in 5G networks, a mobility driven network slicing （MDNS） was proposed, which takes individual mobility support requirements into account while customizing networks for different mobile services. Within the MDNS framework, the actual levels of required mobility support are determined by a mobility description system, and network slice templates with the corresponding mobility management schemes are defined by a network slice description function. By instantiating the network slices, each mobile terminal could be directed to the network slice with the most appropriate mobility management scheme. Based on this, a prototype was implemented to validate the feasibility of MDNS framework, i.e. creating multiple network slices with different mobility management schemes. In addition, the performance evaluation on average cost of processing a mobility event is conducted for the proposed MDNS framework and the long term evolution （LTE） system, and operating benefits are analyzed including efficiency and scalability.

关键词： mobility driven network slicing network slicing on demand mobility management 5G

Second-order time-varying sliding mode control for reentry vehicle

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International Journal of Intelligent Computing and Cybernetics 2013年第3期6卷 272-295页

作者： Jie Geng Yongzhi Sheng Xiangdong Liu key laboratory of Complex system Intelligent Control and Decision School of AutomationBeijing Institute of TechnologyMinistry of EducationBeijingPeople’s Republic of China

Purpose-The purpose of this paper is to design a global robust and continuous control scheme for the attitude tracking control problem of the reentry vehicle with parameter uncertainties and ***/methodology/approach-First,feedback linearization is applied to the model of reentry vehicle,resulting in three independent uncertain *** a new second-order time-varying sliding function is proposed,based on which a continuous second-order time-varying sliding mode control(SOTVSMC)law is proposed for each *** global robustness and convergence performance of the closed-loop reentry vehicle control system under the proposed control law are ***-Simulation is made for a reentry vehicle through the assumption that there is external disturbance to aerodynamic moment and the aerodynamic parameters as well as the atmospheric density are *** results verify the validity and robustness of the proposed ***/value-The SOTVSMC attitude controller based on feedback linearization is proposed for the reentry *** advantages of the proposed SOTVSMC are ***,the global second order sliding mode is established,which implies that the closed-loop system is global robust against matched parameter uncertainties and disturbances in ***,the chattering problem is significantly alleviated.

关键词： Flight control Nonlinear control Real-time systems Robust control Variable structure control

Time-frequency analysis and detecting method research on milling force token signal in spindle current signal

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Science China(Technological Sciences) 2009年第10期52卷 2810-2813页

作者： MAO XinYong LIU HongQi LI Bin National NC system Engineering and Research Center Huazhong University of Science and TechnologyWuhan 430074China State key laboratory of Digital Manufacturing Equipment and technology Huazhong University of Science and TechnologyWuhan 430074China

The vast majority of tool condition monitoring systems use the motor current instead of the cutting force as the predictor signal. The measured motor current signal is time-dependant and instable. It is difficult to detect the cutting force token signal from such motor current signal. This paper presents a method that uses the wavelet transforms to reconstruct the cutting force token signal from the current signal based on the time frequency analysis of the cutting force signal. The result of the cutting force measurement experiment shows that the proposed reconstruct method could be used to analyze the spindle current and monitor the time-varying cutting force.

关键词： tool monitoring spindle current cutting force wavelet transform

Mechanism,Actuation,Perception,and Control of Highly Dynamic Multilegged Robots:A Review

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Chinese Journal of Mechanical Engineering 2020年第5期33卷 120-149页

作者： Jun He Feng Gao State key laboratory of Mechanical system and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Multilegged robots have the potential to serve as assistants for humans,replacing them in performing dangerous,dull,or unclean ***,they are still far from being sufficiently versatile and robust for many *** paper addresses key points that might yield breakthroughs for highly dynamic multilegged robots with the abilities of running(or jumping and hopping)and ***,21 typical multilegged robots from the last five years are surveyed,and the most impressive performances of these robots are ***,current developments regarding key technologies of highly dynamic multilegged robots are reviewed in *** latest leg mechanisms with serial-parallel hybrid topologies and rigid–flexible coupling configurations are ***,the development trends of three typical actuators,namely hydraulic,quasi-direct drive,and serial elastic actuators,are *** that,the sensors and modeling methods used for perception are ***,this paper pays special attention to the review of control approaches since control is a great challenge for highly dynamic multilegged *** dynamics-based control methods and two model-free control methods are described in ***,key open topics of future research concerning the mechanism,actuation,perception,and control of highly dynamic multilegged robots are *** paper reviews the state of the art development for multilegged robots,and discusses the future trend of multilegged robots.

关键词： Multilegged robot Mechanism Actuation Perception Control

Machining of SiC ceramic matrix composites:A review

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Chinese Journal of Aeronautics 2021年第4期34卷 540-567页

作者： Qinglong AN Jie CHEN Weiwei MING Ming CHEN State key laboratory of Mechanical system and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Continuous fiber reinforced SiC ceramic matrix composites(FRCMCs-SiC)are currently the preferred material for hot section components,safety–critical components and braking components(in the aerospace,energy,transportation)with high value,and have triggered the demand for ***,the high brittleness,anisotropy,and heterogeneity of materials bring great challenges to machining,due to high mechanical and thermal loads,severe tool wear,and poor machining *** the increasing demand of FRCMCs-SiC parts,high-quality and high-efficient machining has become a hot *** review paper provides a detailed literature survey on the machining of *** material removal mechanism,defect form,and interfacial mechanical properties of FRCMCs-SiC were *** machining processes of FRCMCs-SiC were introduced,and their respective advantages and disadvantages were *** the low machinability(high hardness,high brittleness,anisotropy,and heterogeneity)of FRCMCs-SiC,preliminary experiments have proved that ultrasonic-assisted machining and laser-assisted machining have shown unique advantages in reducing force and tool wear,improving machining quality and machining *** machined surface integrity was discussed,the influence of process parameters on the machined surface quality was analyzed,and the machining defects of FRCMCs-SiC were *** for FRCMCs-SiC,the existing quantitative evaluation of the machined surface integrity was weak and unsystematic.

关键词： Ceramic matrix composites Machining Material removal mechanisms Quality Surface integrity