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High-speed electro-optic modulation in topological interface states of a one-dimensional lattice

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Light(Science & Applications) 2023年第9期12卷 1961-1970页

作者： yong Zhang jian Shen Jingchi Li Hongwei Wang Chenglong Feng Lei Zhang Lu sun jian Xu Ming Liu Ying Wang yonghui Tian jianwen Dong Yikai su State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic EngineeringShanghai Jiao Tong UniversityShanghai 200240China Center for Advanced Electronic Materials and Devices Shanghai Jiao Tong UniversityShanghai 200240China Institute of Microelectronics and Key Laboratory for Magnetism and Magnetic Materials of MOE School of Physical Science and TechnologyLanzhou UniversityLanzhou 730000 GansuChina State Key Laboratory of Optoelectronic Materials and Technologies&School of Physics Sun Yat-sen UniversityGuangzhou 510275China

lectro-optic modulators are key components in data communication,microwave photonics,and quantum *** bandwidth,energy efficiency,and device dimension are crucial metrics of ***,we provide an important direction for the miniaturization of electro-optic modulators by reporting on ultracompact topological modulators.A topological interface state in a one-dimensional lattice is implemented on a thin-film lithium-niobate integrated *** to the strong optical confinement of the interface state and the peaking enhancement of the electro-optic response,a topological cavity with a size of 1.6×140μm^(2)enables a large modulation bandwidth of 104 *** first topological modulator exhibits the most compact device size compared to reported LN modulators with bandwidths above 28 GHz,to the best of our knowledge.100 Gb/s non-return-to-zero and 100 Gb/s four-level pulse amplitude modulation signals are *** switching energy is 5.4 fJ/bit,owing to the small electro-optic mode volume and low *** topological modulator accelerates the response time of topological photonic devices from the microsecond order to the picosecond order and provides an essential foundation for the implementation of large-scale lithium-niobate photonic integrated circuits.

关键词： modulator interface lattice

Effect of Microdomain Structure on the Mechanical Behavior of Binary Blends

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Chinese Journal of Polymer Science 2015年第7期33卷 964-975页

作者： Bin su yong-sheng Zhao 陈枫傅强 College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan University

The relationship between microphase structure and mechanical response of the binary blends consisting of polystyrene-block-polyisoprene-block-polystyrene copolymer and low molecular weight polystyrene has been investigated. Low molecular weight polystyrene was chosen to obtain uniformly solubilized nano-blends without macrophase separation. The specimens were solution-cast by adding different amounts of homo-polystyrene to acquire different microphase structures. Small angle X-ray scattering（SAXS）, transmission electron microscopy（TEM） and atom force microscopy（AFM） have been used to study the microdomain and grain structure. It is observed that the structural changes in d-spacing and grain size on account of different amounts of polystyrene alter the mechanical behavior in both monotonic tensile and cyclic tests. The elastic and the Mullins effects are strongly sensitive to the changes in d-spacing and grain sizes. Moreover, the sample with bi-continuous structure shows the largest tensile strength and Mullins effect. In addition, the Mooneye-Rivlin phenomenological model was used to evaluate and explore the relationship between the polymer topological networks and the rubber elasticity of these styrenic nano-blends.

关键词： Microphase Grain size d-Spacing Bi-continuous structure Elastic response

Reversible switching between normal and thermally activated delayed fluorescence towards “smart” and single compound whitelight luminescence via controllable conformational distribution

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Science China Chemistry 2018年第6期61卷 677-686页

作者： Zuozheng He Xinyi Cai Zhiheng Wang Dongjun Chen Yunchuan Li Haobin Zhao Kunkun Liu yong Cao Shi-jian su State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices South China University of Technology

An organic compound exhibiting simultaneously reversible switch between its emission colors and luminescence mechanisms,possessing high contrast from deep blue normal fluorescence(NF) to yellow thermally activated delayed fluorescence(TADF),is reported. Based on these two complementary colors, white-light emission combining NF and TADF from a single compound can be achieved in various states. Experimental results and density functional theory calculations indicate that the controllable conformational distribution under thermal and mechanical activation is the mechanism responsible for the reversible switching behavior.

关键词： reversible switching luminescence "smart" luminescent material white-light emission conformational relaxation

Cell search algorithms for the 3G long-term evolution

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The Journal of China Universities of Posts and Telecommunications 2007年第2期14卷 33-37页

作者： su Huan ZHANG jian-hua Wireless Technology Innovation of Institute Beijing University of Posts and Telecommunications Beijing 100876 China

This article presents downlink initial synchronization and cell identification algorithms for long term evolution （LTE） of third-generation （3G） mobile communication systems, which are based on synchronization channel （SCH） and cell specific pilot symbols, respectively. The key features of the proposed scheme are： it can improve performance of the frequency synchronization through oversampling of the SCH, it can support a large number of target cells by modulating a cell-specific pilot sequence over two symbols within a subframe, and it can guarantee cell identification performance by maximally ratio combining the frequency domain differential cross-correlation. Simulations show that the proposed scheme has a potential use in 3G LTE.

关键词： 3rd generation partnership project (3GPP) LTE orthogonal frequency division multiple access (OFDMA) cell search oversampling

The Regularity of Local Solutions for a Generalized Camassa-Holm Type Equation

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Acta Mathematica Sinica,English Series 2009年第12期25卷 2065-2076页

作者： Shao yong LAI jian ZHANG Department of Applied Mathematics Southwestern University of Finance and Economics Chengdu 610074 Po R. China Department of Mathematics Sichuan Normal University Chengdu 610066 P. R. China

The regularity of the Cauchy problem for a generalized Camassa-Holm type equation is investigated. The pseudoparabolic regularization approach is employed to obtain some prior estimates under certain assumptions on the initial value of the equation. The local existence of its solution in Sobolev space Hs （R） with 1 〈 s ≤ 3/2 is derived.

关键词： existence of local solutions Camassa-Holm type equation dissipative term pseudoparabolic regularization method

Numerical investigation of an advanced aircraft model during pitching motion at high incidence

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Science China(Technological Sciences) 2016年第2期59卷 276-288页

作者： LIU jian suN HaiSheng HUANG yong jianG yong XIAO ZhiXiang School of Aerospace Engineering Tsinghua University Beijing 100084 China China Aerodynamics Research and Development Center Mianyang 621000 China

An unsteady Reynolds averaged Navier–Stokes(URANS) method combined with a rigid dynamic mesh technique was developed to simulate unsteady flows around complex configurations during pitching motion. First, a test case with the NACA0012 airfoil was selected to validate the numerical methods and our in-house codes. Then, we evaluated the unsteady flows around an advanced aircraft model during harmonic pitching motion at high incidence. The effects of pitching motion on the hysteresis of aerodynamic force, the evolution of the leading-edge vortex, and the distribution of pressure on the model's surface were analyzed in detail. The roles of several significant parameters such as the reduced frequency and pitching amplitude were revealed. Several conclusions were found: pitching motion would delay the initiation of the leading-edge vortex, strengthen the vorticity, postpone the occurrence of vortex breakdown, and weaken the massively separated flows, thus causing additional aerodynamic force. Two categories of critical reduced frequency have been found, which divide the influence of reduced frequency on aerodynamic force into three stages, called the linear increasing range, slowly increasing range, and constant range. The first-order phase lag between the aerodynamic force and the incidence is a constant that is independent of the amplitude when the reduced frequency is sufficiently high. A scaled maximum value of C_L is proposed; it depends only on the reduced frequency(instead of the amplitude), and increases linearly when the reduced frequency is sufficiently low.

关键词： pitching motion hysteresis critical reduced frequency phase lag scaled maximum of CL

A SECOND ORDER MODIFIED CHARACTERISTICS VARIATIONAL MULTISCALE FINITE ELEMENT METHOD FOR TIME-DEPENDENT NAVIER-STOKES PROBLEMS

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Journal of Computational Mathematics 2013年第2期31卷 154-174页

作者： Zhiyong Si jian su Yinnian He School of Mathematics and Information Science Henan Polytechnic University Jiaozuo 454003 China Center for Computational Geosciences School of Mathematics and Statistics Xi 'an Jiaotong University Xi'an 710049 China

In this paper, by combining the second order characteristics time discretization with the variational multiscale finite element method in space we get a second order modified characteristics variational multiscale finite element method for the time dependent Navier- Stokes problem. The theoretical analysis shows that the proposed method has a good convergence property. To show the efficiency of the proposed finite element method, we first present some numerical results for analytical solution problems. We then give some numerical results for the lid-driven cavity flow with Re = 5000, 7500 and 10000. We present the numerical results as the time are sufficient long, so that the steady state numerical solutions can be obtained.

关键词： Modified method of characteristics Defect-correction finite element method Navier-Stokes problems Characteristics-based method Lid-driven problem.

Reliable H-infinity filtering for linear systems with sensor saturation

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控制理论与应用（英文版） 2013年第1期11卷 80-85页

作者： Ting SHI Hongye su jian CHU Institute of Automation Hangzhou Dianzi University State Key Laboratory of Industrial Control Technology Institute of Cyber-Systems and Control Zhejiang University (Yuquan Campus)

In this paper, a new reliable H-infinity filter design problem is proposed for a class of continuous-time sys- tems with sensor saturation and failures. Attention is focused on the analysis and synthesis problems of a full order reliable H-infinity filter such that the filtering error dynamics is asymptotically stable with a guaranteed disturbance rejection atten- uation level -y. It is shown that the filtering error dynamics obtained from the original system plus the filter can be modeled by a linear system with sector bounded nonlinearity. The design conditions are given in terms of solutions to a set of linear matrix inequalities （LMIs）. These conditions are then considered in a convex optimization problem with LMIs constraints in order to design an optimal reliable H-infinity filter. A numerical example is given to illustrate the effectiveness of the proposed results.

关键词： H-infinity filtering Reliable filtering Sensor saturation Sensor failures Linear matrix inequality

Sap Flow of Populus euphratica in a Desert Riparian Forest in an Extreme Arid Region During the Growing Season

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Journal of Integrative Plant Biology 2007年第4期49卷 425-436页

作者： jian-Hua Si Qi Feng Xiao-You Zhang Zong-Qiang Chang yong-Hong su Hai-Yang Xi Cold and Arid Region Environmental and Engineering Research Institute the Chinese Academy of Sciences Alashan Desert Eco-hydrology Experimental Research Station Lanzhou 730000 China

In the present study, the heat pulse technique was applied to investigate the stem sap flow of Populus euphratica in a desert riparian forest in an extreme arid region from April to October 2003 and from May to October 2004. The experimental sites were in Qidaoqiao （101 °10′ E, 41°59′ N） and Bayantaolai farm （101°14′ E, 42°01′ N） in Ejina county, in the low reaches of the Heihe River, China. The results indicated that the diurnal change in the velocity of sap flow showed minor fluctuations. At night, the rising of sap flow could be observed in the main tree species because of root pressure. During the growing season, the maximum average velocity was observed in July, followed by August, and the same velocity was observed in September and May; the minimum velocity was observed in October. The transpiration from June to August during the growing season accounted for approximately 70% of the annual total transpiration. The sap flow velocity of P. euphratica trees of different ages could be arranged in the order： 15 yr 〉 25 yr 〉 50 yr. Sap flow velocity was closely related to changes in micrometeorological factors, with average sap flow velocity showing a significant linear correlation with net radiation, air temperature and relative humidity.

关键词： desert riparian forest extreme arid region heat-pulse technique Populus euphratica sap flow velocity.