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Information theory of metasurfaces

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National Science Review 2020年第3期7卷 561-571页

作者： Haotian Wu guo dong bai Shuo Liu Lianlin Li Xiang Wan Qiang Cheng Tie Jun Cui State Key Laboratory of Millimeter Waves Southeast University School of Physics and Astronomy University of Birmingham State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronics Peking University

We propose a theory to characterize the information and information processing abilities of metasurfaces,and demonstrate the relation between the information of the metasurface and its radiation pattern in the far-field region. By incorporating a general aperture model with uncertainty relation in L2-space, we propose a theory to predict the upper bound of information contained in the radiation pattern of a metasurface, and reveal the theoretical upper limit of orthogonal radiation states. The proposed theory also provides guidance for inverse design of the metasurface with respect to given functionalities. Through investigation of the information of disordered-phase modulated metasurfaces, we find the information invariance(1-γ, whereγ is Euler’s constant) of chaotic radiation patterns. That is to say, the information of the disordered-phase modulated radiation patterns is always equal to 1-γ, regardless of variations in size, the number of elements and the phase pattern of metasurface. This value might be the lower bound of radiation-pattern information of the metasurface, which can provide a theoretical limit for information modulation applications, including computational imaging, stealth technologies and wireless communications.

关键词： metasurfaces differential entropy radiation information bounds maximum orthogonal radiation patterns information invariance

Harmonic information transitions of spatiotemporal metasurfaces

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Light(Science & Applications) 2020年第1期9卷 58-70页

作者： Haotian Wu Xin Xin Gao Lei Zhang guo dong bai Qiang Cheng Lianlin Li Tie Jun Cui State Key Laboratory of Millimetre Waves Southeast University210096 NanjingChina Institute of Electromagnetic Space Southeast University210096 NanjingChina State Key Laboratory of Advanced Optical Communication Systems and Networks Department of ElectronicsPeking University100871 BeijingChina

Facilitated by ultrafast dynamic modulations,spatiotemporal metasurfaces have been identified as a pivotal platform for manipulating electromagnetic waves and creating exotic physical phenomena,such as dispersion cancellation,Lorentz reciprocity breakage,and Doppler illusions.Motivated by emerging information-oriented technologies,we hereby probe the information transition mechanisms induced by spatiotemporal variations and present a general model to characterize the information processing capabilities of the spatiotemporal metasurface.Group theory and abstract number theory are adopted through this investigation,by which the group extension and independent controls of multiple harmonics are proposed and demonstrated as two major tools for information transitions from the spatiotemporal domain to the spectra-wavevector domain.By incorporating Shannon’s entropy theory into the proposed model,we further discover the corresponding information transition efficiencies and the upper bound of the channel capacity of the spatiotemporal metasurface.The results of harmonic information transitions show great potential in achieving high-capacity versatile information processing systems with spatiotemporal metasurfaces.

关键词： surface transitions surfaces

Smart metasurface with self-adaptively reprogrammable functions

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Light(Science & Applications) 2019年第1期8卷 266-277页

作者： Qian Ma guo dong bai Hong Bo Jing Cheng Yang Lianlin Li Tie Jun Cui State Key Laboratory of Millimeter Wave Southeast University210096 NanjingChina Jiangsu Cyber-Space Science&Technology Co. Ltd.12 Mozhou East Road211111 NanjingChina State Key Laboratory of Advanced Optical Communication Systems and Networks Department of ElectronicsPeking University100871 BeijingChina

Intelligence at either the material or metamaterial level is a goal that researchers have been pursuing.From passive to active,metasurfaces have been developed to be programmable to dynamically and arbitrarily manipulate electromagnetic(EM)wavefields.However,the programmable metasurfaces require manual control to switch among different functionalities.Here,we put forth a smart metasurface that has self-adaptively reprogrammable functionalities without human participation.The smart metasurface is capable of sensing ambient environments by integrating an additional sensor(s)and can adaptively adjust its EM operational functionality through an unmanned sensing feedback system.As an illustrative example,we experimentally develop a motion-sensitive smart metasurface integrated with a three-axis gyroscope,which can adjust self-adaptively the EM radiation beams via different rotations of the metasurface.We develop an online feedback algorithm as the control software to make the smart metasurface achieve single-beam and multibeam steering and other dynamic reactions adaptively.The proposed metasurface is extendable to other physical sensors to detect the humidity,temperature,illuminating light,and so on.Our strategy will open up a new avenue for future unmanned devices that are consistent with the ambient environment.

关键词： surface ambient adjust

Negative reflection and negative surface wave conversion from obliquely incident electromagnetic waves

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Light(Science & Applications) 2018年第1期7卷 1047-1057页

作者： Shuo Liu Tie Jun Cui Ahsan Noor Zui Tao Hao Chi Zhang guo dong bai Yan Yang Xiao Yang Zhou State Key Laboratory of Millimeter Waves Southeast UniversityNanjing 210096China Synergetic Innovation Center of Wireless Communication Technology Southeast UniversityNanjing 210096China Centre of Intelligent Acoustics and Immersive Communications and School of Marine Science and Technology Northwestern Polytechnical UniversityXian 710072China Jiangsu Xuantu Technology Co. Ltd.12 Mozhou East RoadNanjing 211111China

Complete control of spatially propagating waves(PWs)and surface waves(SWs)is an ultimate goal that scientists and engineers seek for,in which negative reflection of PW and negative surface wave are two exotic phenomena.Here,we experimentally demonstrate an anisotropic digital coding metasurface capable of controlling both PWs and SWs with a single coding pattern.On the basis of the digital description of coding metasurfaces,a simple coding method is proposed to allow dual functionalities(either PW or SW manipulations)under two orthogonal polarizations at arbitrarily oblique incidences,thus improving the adaptability of digital coding metasurfaces in more practical circumstances.With elaborately designed ellipse-shaped coding particles,we experimentally demonstrate various functions under oblique incidences,including the negative reflection of PW,negative SW,anomalous reflection and their arbitrary combinations,all having good agreements with theoretical and numerical predictions.We believe that the proposed method may enable the digital coding metasurfaces to have broad applications in radar detections,wireless communications and imaging.

关键词： anisotropic coding metasurface negative reflection negative surface wave oblique incidence spatial wave surface wave

Programmable time-domain digital-coding metasurface for non-linear harmonic manipulation and new wireless communication systems

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National Science Review 2019年第2期6卷 231-238页

作者： Jie Zhao Xi Yang Jun Yan Dai Qiang Cheng Xiang Li Ning Hua Qi Jun Chen Ke guo dong bai Shuo Liu Shi Jin Andrea Alù Tie Jun Cui State Key Laboratory of Millimeter Waves Southeast University Jiangsu Cyber-Space Science & Technology Co. Ltd Physics Program The Graduate Center City University of New York National Mobile Communication Research Laboratory Southeast University Synergetic Innovation Center of Wireless Communication Technology Southeast University Department of Electrical Engineering City College of New York Photonics Initiative Advanced Science Research Center City University of New York

Optical non-linear phenomena are typically observed in natural materials interacting with light at high intensities, and they benefit a diverse range of applications from communication to sensing. However,controlling harmonic conversion with high efficiency and flexibility remains a major issue in modern optical and radio-frequency systems. Here, we introduce a dynamic time-domain digital-coding metasurface that enables efficient manipulation of spectral harmonic distribution. By dynamically modulating the local phase of the surface reflectivity, we achieve accurate control of different harmonics in a highly programmable and dynamic fashion, enabling unusual responses, such as velocity illusion. As a relevant application, we propose and realize a novel architecture for wireless communication systems based on the time-domain digital-coding metasurface, which largely simplifies the architecture of modern communication systems, at the same time yielding excellent performance for real-time signal transmission. The presented work, from new concept to new system, opens new pathways in the application of metamaterials to practical technology.

关键词： metasurface time-domain digital coding non-linear harmonics control new architecture of communication

Polysaccharides from Chinese herbal medicine:a review on the hepatoprotective and molecular mechanism

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Chinese Journal of Natural Medicines 2024年第1期22卷 4-14页

作者： LI Jifeng guo Haolin dong Ying YUAN Shuo WEI Xiaotong ZHANG Yuxin dong Lu WANG Fei bai Ting YANG Yong Dalian Key Laboratory of Chronic Disease Research Center Dalian UniversityDalian 116622China Key Laboratory of Natural Medicines of the Changbai Mountain Ministry of EducationCollege of PharmacyYanbian UniversityYanji 133002China

Polysaccharides,predominantly extracted from traditional Chinese medicinal herbs such as Lycium barbarum,Angelica sinensis,Astragalus membranaceus,Dendrobium officinale,Ganoderma lucidum,and Poria cocos,represent principal bioactive constituents extensively utilized in Chinese medicine.These compounds have demonstrated significant anti-inflammatory capabilities,especially anti-liver injury activities,while exhibiting minimal adverse effects.This review summarized recent studies to elucidate the hepatoprotective efficacy and underlying molecular mechanisms of these herbal polysaccharides.It underscored the role of these polysaccharides in regulating hepatic function,enhancing immunological responses,and improving antioxidant capacities,thus contributing to the attenuation of hepatocyte apoptosis and liver protection.Analyses of molecular pathways in these studies revealed the intricate and indispensable functions of traditional Chinese herbal polysaccharides in liver injury management.Therefore,this review provides a thorough examination of the hepatoprotective attributes and molecular mechanisms of these medicinal polysaccharides,thereby offering valuable insights for the advancement of polysaccharide-based therapeutic research and their potential clinical applications in liver disease treatment.

关键词： Polysaccharides Hepatoprotective Chinese herbal medicine Mechanism

All laser direct writing process for temperature sensor based on graphene and silver

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Frontiers of Optoelectronics 2024年第1期17卷 45-55页

作者： Qi Li Ruijie bai Lianbo guo Yang Gao Shanghai Key Laboratory of Intelligent Sensing and Detection Technology School of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China North Automatic Control Technology Institute Taiyuan 030006China Wuhan National Laboratory for Optoelectronics Huazhong University of Science&TechnologyWuhan 430074China

A highly sensitive temperature sensing array is prepared by all laser direct writing(LDW)method,using laser induced silver(LIS)as electrodes and laser induced graphene(LIG)as temperature sensing layer.A finite element analysis(FEA)photothermal model incorporating a phase transition mechanism is developed to investigate the relationship between laser parameters and LIG properties,providing guidance for laser processing parameters selection with laser power of 1–5 W and laser scanning speed(greater than 50 mm/s).The deviation of simulation and experimental data for widths and thickness of LIG are less than 5%and 9%,respectively.The electrical properties and temperature responsiveness of LIG are also studied.By changing the laser process parameters,the thickness of the LIG ablation grooves can be in the range of 30–120μm and the resistivity of LIG can be regulated within the range of 0.031–67.2Ω・m.The percentage temperature coefficient of resistance(TCR)is calculated as−0.58%/°C.Furthermore,the FEA photothermal model is studied through experiments and simulations data regarding LIS,and the average deviation between experiment and simulation is less than 5%.The LIS sensing samples have a thickness of about 14μm,an electrical resistivity of 0.0001–100Ω・m is insensitive to temperature and pressure stimuli.Moreover,for a LIS-LIG based temperature sensing array,a correction factor is introduced to compensate for the LIG temperature sensing being disturbed by pressure stimuli,the temperature measurement difference is decreased from 11.2 to 2.6°C,indicating good accuracy for temperature measurement.

关键词： Laser direct writing Temperature sensor Finite element analysis Laser induced graphene Laser induced silver

SCAB1 coordinates sequential Ca^(2+) and ABA signals during osmotic stress induced stomatal closure in Arabidopsis

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Science China(Life Sciences) 2024年第1期67卷 1-18页

作者： Tianren Zhang Li bai Yan guo State Key Laboratory of Plant Environmental Resilience College of Biological SciencesChina Agricultural UniversityBeijing 100193China

Hyperosmotic stress caused by drought is a detrimental threat to plant growth and agricultural productivity due to limited water availability.Stomata are gateways of transpiration and gas exchange,the swift adjustment of stomatal aperture has a strong influence on plant drought resistance.Despite intensive investigations of stomatal closure during drought stress in past decades,little is known about how sequential signals are integrated during complete processes.Here,we discovered that the rapid Ca^(2+) signaling and subsequent abscisic acid(ABA)signaling contribute to the kinetics of both F-actin reorganizations and stomatal closure in Arabidopsis thaliana,while STOMATAL CLOSURE-RELATED ACTIN BINDING PROTEIN1(SCAB1)is the molecular switch for this entire process.During the early stage of osmotic shock responses,swift elevated calcium signaling promotes SCAB1 phosphorylation through calcium sensors CALCIUM DEPENDENT PROTEIN KINASE3(CPK3)and CPK6.The phosphorylation restrained the microfilament binding affinity of SCAB1,which bring about the Factin disassembly and stomatal closure initiation.As the osmotic stress signal continued,both the kinase activity of CPK3 and the phosphorylation level of SCAB1 attenuated significantly.We further found that ABA signaling is indispensable for these attenuations,which presumably contributed to the actin filament reassembly process as well as completion of stomatal closure.Notably,the dynamic changes of SCAB1 phosphorylation status are crucial for the kinetics of stomatal closure.Taken together,our results support a model in which SCAB1 works as a molecular switch,and directs the microfilament rearrangement through integrating the sequentially generated Ca^(2+) and ABA signals during osmotic stress induced stomatal closure.

关键词： calcium signal ABA stomatal movement microfilaments kinase

Resonance mechanism of flapping wing based on fluid structure interaction simulation

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Chinese Journal of Aeronautics 2024年第5期37卷 243-262页

作者： Yueyang guo Wenqing YANG Yuanbo dong dong XUE National Key Laboratory of Science and Technology on Aerodynamic Design and Research School of AeronauticsNorthwestern Polytechnical UniversityXi'an 710072China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China Yangtze River Delta Research Institute of Northwestern Polytechnical University Taicang 215400China

Certain insect species have been observed to exploit the resonance mechanism of their wings.In order to achieve resonance and optimize aerodynamic performance,the conventional approach is to set the flapping frequency of flexible wings based on the Traditional Structural Modal(TSM)analysis.However,there exists controversy among researchers regarding the relationship between frequency and aerodynamic performance.Recognizing that the structural response of wings can be influenced by the surrounding air vibrations,an analysis known as Acoustic Structure Interaction Modal(ASIM)is introduced to calculate the resonant frequency.In this study,Fluid Structure Interaction(FSI)simulations are employed to investigate the aerodynamic performance of flapping wings at modal frequencies derived from both TSM and ASIM analyses.The performance is evaluated for various mass ratios and frequency ratios,and the findings indicate that the deformation and changes in vortex structure exhibit similarities at mass ratios that yield the highest aerodynamic performance.Notably,the flapping frequency associated with the maximum time-averaged vertical force coefficient at each mass ratio closely aligns with the ASIM frequency,as does the frequency corresponding to maximum efficiency.Thus,the ASIM analysis can provide an effective means for predicting the optimal flapping frequency for flexible wings.Furthermore,it enables the prediction that flexible wings with varying mass ratios will exhibit similar deformation and vortex structure changes.This paper offers a fresh perspective on the ongoing debate concerning the resonance mechanism of Flexible Flapping Wings(FFWs)and proposes an effective methodology for predicting their aerodynamic performance.

关键词： Flexible Flapping Wing(FFW) Acoustic Structure Interaction Modal(ASIM) Fluid Structure Interaction(FSI) Resonance mechanism Aerodynamic performance