All staff members at our Academy praise the key decision made by the Party’s leading group at the CAS to implement the Program of Knowledge Innovation. Also, they believe the move offers both our Academy and its rese...All staff members at our Academy praise the key decision made by the Party’s leading group at the CAS to implement the Program of Knowledge Innovation. Also, they believe the move offers both our Academy and its research institutes a precious opportunity for rejuvenating China’ s S&T endeavors at the turn of the century. Our Institute has a展开更多
During the Spring Festival in 2022,China Cultural Center in Mexico focused on the themes of Winter Olympics with Ice and Snow,the 50th anniversary of the establishment of diplomatic relations between China and Mexico,...During the Spring Festival in 2022,China Cultural Center in Mexico focused on the themes of Winter Olympics with Ice and Snow,the 50th anniversary of the establishment of diplomatic relations between China and Mexico,friendship between the two countries,etc.,and cooperated with 20-plus Chinese and Mexican institutions to hold 11 categories of 180-plus Spring Festival celebration activities,such as Year of the Tiger Costume Contest,Happy Spring Festival Quiz Show,the 8th Children's Painting Competition:China in My Imagination in the theme of Winter Olympics and ice&snow sports.展开更多
The index systems are not only the tools to evaluate existing practice results, but also the guides to the future development direction and development way of practical activities. ＂Well-off society＂ is a relatively...The index systems are not only the tools to evaluate existing practice results, but also the guides to the future development direction and development way of practical activities. ＂Well-off society＂ is a relatively vague concept, and the contents of it ceaselessly change with the advancement of society and the development of productivity. Now the construction of a well-off society in an all-round way enters a critical stage, so the original evaluation standards must change with gradual advancement of the construction goal of a well-off society. So it is very necessary for us to build a comprehensive evaluation index system and make it better and better to provide effective statistical consultation and statistical supervision for constructing a well-off society in an all-round way. This paper attempts to analyze the current evaluation index system, then puts forward the general thinking and flame work of the index system of building a well-off society in an all-round way.展开更多
"The year of 2022 marked the70th anniversary of the founding of the China Council for the Promotion of International Trade(CCPIT),and it was also a milestone in the development history of trade promotion.Under th..."The year of 2022 marked the70th anniversary of the founding of the China Council for the Promotion of International Trade(CCPIT),and it was also a milestone in the development history of trade promotion.Under the strong leadership of the Central Committee of the Communist Party of China(CPC)with Comrade Xi Jinping at its core,the national trade promotion system faced up to difficulties,forged ahead.展开更多
Cognitive bias,stemming from electronic measurement error and variability in human perception,exists in cognitive electronic warfare and affects the outcomes of conflicts.In this paper,the dynamic game approach is emp...Cognitive bias,stemming from electronic measurement error and variability in human perception,exists in cognitive electronic warfare and affects the outcomes of conflicts.In this paper,the dynamic game approach is employed to develop a model for cognitive bias induced by incomplete information and measurement errors in cognitive radar countermeasures.The payoffs for both parties are calculated using the radar's anti-jamming strategy matrix A and the jammer's jamming strategy matrix B.With perfect Bayesian equilibrium,a dynamic radar countermeasure model is established,and the impact of cognitive bias is analyzed.Drawing inspiration from the cognitive bias analysis method used in stock market trading,a cognitive bias model for cognitive radar countermeasures is introduced,and its correctness is mathematically proved.A gaming scenario involving the AN/SPY-1 radar and a smart jammer is set up to analyze the influence of cognitive bias on game outcomes.Simulation results validate the effectiveness of the proposed method.展开更多
Perfect anomalous reflections have been demonstrated in optical phase gradient metasurfaces(PGMs),but they suffer from single-frequency(narrow-band)response due to the intrinsic limitation of natural geometric periodi...Perfect anomalous reflections have been demonstrated in optical phase gradient metasurfaces(PGMs),but they suffer from single-frequency(narrow-band)response due to the intrinsic limitation of natural geometric periodicity.Here,we provide both numerical and analytical evidence that a depth gradient metasurface can achieve discrete ultra-broadband perfect anomalous reflection in the microwave range in the absence of geometric periodicity.Remarkably,by adjusting the operating frequency of the incident wave,the same effect can be steadily obtained via a physically equivalent phase periodicity in the PGM.Based on this mechanism,a perfect retroreflector with a broadband response ranging from 1 GHz to 40 GHz is realized.Our work has promising applications in communication,source tracking,and military satellites.展开更多
4 When you buy something,do you buy new or usecP Both can be good.When you buy things new,they're in perfect condition.These things usually last longer because they're new.New things also often have the newest...4 When you buy something,do you buy new or usecP Both can be good.When you buy things new,they're in perfect condition.These things usually last longer because they're new.New things also often have the newest features and design.展开更多
This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene.By comparing the simulated experimental data with theoretical derivations,it was found that the ...This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene.By comparing the simulated experimental data with theoretical derivations,it was found that the absorbance of the material can be sustained above 90%in the frequency range of 2.78 to 7.14(4.36)THz,of which the absorption rate exceeds 99%in the frequency range of 4.1–4.54(0.44)THz,and remarkably,perfect absorption is achieved at4.32 THz.In the range of 2.78–7.14 THz,the average absorption rate is 96.1%,by adjusting the physical size of the graphene layer pattern,we can modify the working band gap of the absorber.By applying a voltage to modulate the Fermi level of graphene,we can increase the absorption bandwidth.When the chemical potential is 1.0 e V,at the bandwidth of 4.36 THz,its absorption rate exceeds 90%.The working principle of absorbing materials was deeply explored using the principles of electromagnetic field distribution and impedance adaptation.Through detailed analysis of different polarization states and incident angles,we found that the absorber is not sensitive to polarization due to its symmetrical structure,and found that it exhibits low sensitivity at incidence angles.In addition,after comparative analysis,significant differences were observed in the absorption efficiency of the absorber under various relaxation time conditions,and the obtained data were elaborated in detail using the carrier mechanism of plasma vibration.We found that in addition to obtaining an almost perfect absorber with wide band by adjusting the parameters,it is also feasible to obtain an approximately narrow band absorber by changing the relaxation time without having to remanufacture the structure.The absorber offers several advantages,including tunability,a wide absorption band,a high absorption rate,polarization insensitivity,and a simple structure.Therefore,this absorber exhibits great potential for absorption,monitoring,and sensing in the terahertz band.展开更多
In this study,the wave motion in elastodynamics for unbounded media is modeled using an unsplit-field perfectly matched layer(PML)formulation that is solved by employing an isogeometric analysis(IGA).In the adopted co...In this study,the wave motion in elastodynamics for unbounded media is modeled using an unsplit-field perfectly matched layer(PML)formulation that is solved by employing an isogeometric analysis(IGA).In the adopted combination,the non-uniform rational B-spline(NURBS)functions are employed as basis functions.Moreover,the unbounded and artificial domains,defined in the PML method,are contained in a single patch domain.Based on the proposed scheme,the approximation of the geometry problem is set in a new scheme in which the PML’s absorbing and attenuation properties and the description of traveling waves can be represented.This includes a higher continuity and smoother approximation of the computed domain.As high-order NURBS basis functions are non-interpolatory,a penalty method is present to apply a time-dependent displacement load.The performance of the NURBS-based PML is analyzed through numerical examples for 1D and 2D domains,considering homogeneous and heterogeneous media.Further,we verify the long-time numerical stability of the present method.The developed method can be used to simulate hypothetical stratified domains commonly encountered in soil-structure interaction analyses.展开更多
Broadband and perfect terahertz absorber based on multilayer metamaterial using cross-ring patterned structures is proposed and investigated.The structure of the absorber is double absorption layers consisting of a ch...Broadband and perfect terahertz absorber based on multilayer metamaterial using cross-ring patterned structures is proposed and investigated.The structure of the absorber is double absorption layers consisting of a chromium cross ring and eight isosceles right triangles.The unique structure of the double absorbing layers excites the electric dipole multimode resonance,giving rise to high absorption performance.Meanwhile,the influence of construal parameters on absorber behavior is also discussed.The numerical results show that the absorption achieves over 90%ranging from 2.45 THz to 6.25 THz and 99%absorption in the range of 3.7—5.3 THz.The realization of broadband and perfect absorber is described using the impedance matching principle.It is obviously found that the absorber is insensitive to the high angle of incidence for both transverse electric(TE)and transverse magnetic(TM)polarizations.Compared with the former reports,this absorber has remarkable improved absorption efficiency and smaller period.The terahertz absorber may be found applications in the fields of energy capture and thermal detection.展开更多
Acoustic wave isolation and noise reduction are significant challenges in the fields of physics and various applications.Traditional noise-control devices are often hampered by substantial size limitations,and their o...Acoustic wave isolation and noise reduction are significant challenges in the fields of physics and various applications.Traditional noise-control devices are often hampered by substantial size limitations,and their operational efficacy is generally restricted to planar waveforms.In this study,we demonstrate perfect confinement of acoustic vortex waves using an acoustic metacage consisting of phase-gradient metasurfaces.By leveraging the parity-reversed diffraction rule of phase-gradient metasurfaces,the designed metacage exhibited remarkable capabilities for the perfect confinement of acoustic vortex waves,showing robust performance even in the presence of source offsets.These findings present a promising strategy for developing precise and adaptable acoustic confinement technologies.展开更多
Each year,Lin Haiyan,president of the Chinatown Foundation in Mauritius,dedicates significant time and effort to organising the Spring Festival celebrations.During the Spring Festival season in February 2024,the Mauri...Each year,Lin Haiyan,president of the Chinatown Foundation in Mauritius,dedicates significant time and effort to organising the Spring Festival celebrations.During the Spring Festival season in February 2024,the Mauritius National Multi-Sport Complex was adorned with large red lanterns and Chinese knots,creating a vibrant setting for the festivities.The event featured captivating performances,including lion and dragon dances,parades showcasing traditional Chinese women’s clothing,or qipao,singing,and tai chi demonstrations,providing the perfect atmosphere to celebrate the Chinese New Year.展开更多
We theoretically and experimentally investigate thermal dynamics involved soliton microcomb generation in silicon oxynitride microresonators. Importantly, auxiliary laser heat balance scheme with flexible thermal mani...We theoretically and experimentally investigate thermal dynamics involved soliton microcomb generation in silicon oxynitride microresonators. Importantly, auxiliary laser heat balance scheme with flexible thermal manipulation is introduced to circumvent thermal instability and the intra-cavity temperature can be tuned from 60 ℃ to 41.5 ℃ via the commercial thermoelectric controller. As a result, various perfect soliton states with ultra-smooth spectral envelopes are observed on a well-designed and fabricated microresonator with homogeneous sidewall and thickness where spatial modes interaction and distortion are eliminated. The pre-reported spectral abrupt jumps due to mode hybridization are completely avoided and solitons tail oscillation vanishes simultaneously. This reported ideal coherent comb source without residual temporal and spectral noise will facilitate practical applications such as spectroscopy, ranging and astrocomb calibration.展开更多
Metal micro-nano grating has received much attention due to its ability to provide high-efficiency light absorption.However,the current research scales of these metal gratings are focused on subwavelengths,and little ...Metal micro-nano grating has received much attention due to its ability to provide high-efficiency light absorption.However,the current research scales of these metal gratings are focused on subwavelengths,and little attention has been paid to the absorption properties of metal gratings at other scales.We investigate the absorption properties of metal gratings based on surface plasmon resonance(SPR)across the scales from superwavelength to subwavelength.Under grazing incidence,we observe continuous strong absorption phenomena from superwavelength to subwavelength Al triangle-groove gratings(TGGs).Perfect absorption is realized at the subwavelength scale,whereas the maximum absorption at all other scales exceeds 74%.The electric field distribution gives the mechanism of the strong absorption phenomenon attributed to SPR on the surface of Al TGGs at different scales.In particular,subwavelength Al TGGs have perfectly symmetric absorption properties for different blaze angles,and the symmetry is gradually broken as the grating period’s scale increases.Furthermore,taking Al gratings with varying groove shapes for example,we extend the equivalence rule of grating grooves to subwavelength from near-wavelength and explain the symmetric absorption properties in Al TGGs.We unify the research of metal grating absorbers outside the subwavelength scale to a certain extent,and these findings also open new perspectives for the design of metal gratings in the future.展开更多
In this paper, the attack detection problem is investigated for a class of closed-loop systems subjected to unknownbutbounded noises in the presence of stealthy attacks. The measurement outputs from the sensors are qu...In this paper, the attack detection problem is investigated for a class of closed-loop systems subjected to unknownbutbounded noises in the presence of stealthy attacks. The measurement outputs from the sensors are quantized before transmission.A specific type of perfect stealthy attack, which meets certain rather stringent conditions, is taken into account. Such attacks could be injected by adversaries into both the sensor-toestimator and controller-to-actuator channels, with the aim of disrupting the normal data flow. For the purpose of defending against these perfect stealthy attacks, a novel scheme based on watermarks is developed. This scheme includes the injection of watermarks(applied to data prior to quantization) and the recovery of data(implemented before the data reaches the estimator).The watermark-based scheme is designed to be both timevarying and hidden from adversaries through incorporating a time-varying and bounded watermark signal. Subsequently, a watermark-based attack detection strategy is proposed which thoroughly considers the characteristics of perfect stealthy attacks,thereby ensuring that an alarm is activated upon the occurrence of such attacks. An example is provided to demonstrate the efficacy of the proposed mechanism for detecting attacks.展开更多
A theory based on the superposition principle is developed to uncover the basic physics of wave behavior in a finite grating of N unit cells.The theory reveals that bound states in the continuum(BICs)of infinite quali...A theory based on the superposition principle is developed to uncover the basic physics of wave behavior in a finite grating of N unit cells.The theory reveals that bound states in the continuum(BICs)of infinite quality factor(Q-factor)can be supported by such a grating when perfect reflection is introduced at its boundaries.If geometrical perturbations are introduced into the structure,the dark BICs transform into bright quasi-BICs with finite Q-factor,maintaining spectral characteristics nearly identical to those of quasi-BICs supported by infinite gratings.When the boundaries are replaced with high-reflectivity metallic mirrors,the Q-factor of the resonant mode is reduced to be finite;however,it can be much larger than that in the corresponding nanostructure with open boundaries and can be tuned over a large range by varying the number of unit cells or boundary conditions.展开更多
Consider a graph G=(V,E).A perfect double Roman dominating function(PDRDF for short)is a function h:V→{0,1,2,3}that satisfies the condition∑_(y∈NG[x],h(y)≥1)h(y)=|{y∈NG(x):h(y)≥1}|+2 for any x∈V with h(x)≤1.Th...Consider a graph G=(V,E).A perfect double Roman dominating function(PDRDF for short)is a function h:V→{0,1,2,3}that satisfies the condition∑_(y∈NG[x],h(y)≥1)h(y)=|{y∈NG(x):h(y)≥1}|+2 for any x∈V with h(x)≤1.The weightω(h)of this function is∑_(y∈V)h(y).The perfect double Roman domination number(PDRD-number)of G,denoted byγ_(dR)^(p)(G),is defined as the minimum weight among all PDRDFs of G.This article presents a comprehensive analysis of the PDRD-number of connected cographs,demonstrating that it falls within the set{2,3,4,5,6}.Furthermore,it establishes that for any integer i≥7,there is a connected cograph G such that its PDRD-number is equal to i.展开更多
文摘All staff members at our Academy praise the key decision made by the Party’s leading group at the CAS to implement the Program of Knowledge Innovation. Also, they believe the move offers both our Academy and its research institutes a precious opportunity for rejuvenating China’ s S&T endeavors at the turn of the century. Our Institute has a
文摘During the Spring Festival in 2022,China Cultural Center in Mexico focused on the themes of Winter Olympics with Ice and Snow,the 50th anniversary of the establishment of diplomatic relations between China and Mexico,friendship between the two countries,etc.,and cooperated with 20-plus Chinese and Mexican institutions to hold 11 categories of 180-plus Spring Festival celebration activities,such as Year of the Tiger Costume Contest,Happy Spring Festival Quiz Show,the 8th Children's Painting Competition:China in My Imagination in the theme of Winter Olympics and ice&snow sports.
文摘The index systems are not only the tools to evaluate existing practice results, but also the guides to the future development direction and development way of practical activities. ＂Well-off society＂ is a relatively vague concept, and the contents of it ceaselessly change with the advancement of society and the development of productivity. Now the construction of a well-off society in an all-round way enters a critical stage, so the original evaluation standards must change with gradual advancement of the construction goal of a well-off society. So it is very necessary for us to build a comprehensive evaluation index system and make it better and better to provide effective statistical consultation and statistical supervision for constructing a well-off society in an all-round way. This paper attempts to analyze the current evaluation index system, then puts forward the general thinking and flame work of the index system of building a well-off society in an all-round way.
文摘"The year of 2022 marked the70th anniversary of the founding of the China Council for the Promotion of International Trade(CCPIT),and it was also a milestone in the development history of trade promotion.Under the strong leadership of the Central Committee of the Communist Party of China(CPC)with Comrade Xi Jinping at its core,the national trade promotion system faced up to difficulties,forged ahead.
文摘Cognitive bias,stemming from electronic measurement error and variability in human perception,exists in cognitive electronic warfare and affects the outcomes of conflicts.In this paper,the dynamic game approach is employed to develop a model for cognitive bias induced by incomplete information and measurement errors in cognitive radar countermeasures.The payoffs for both parties are calculated using the radar's anti-jamming strategy matrix A and the jammer's jamming strategy matrix B.With perfect Bayesian equilibrium,a dynamic radar countermeasure model is established,and the impact of cognitive bias is analyzed.Drawing inspiration from the cognitive bias analysis method used in stock market trading,a cognitive bias model for cognitive radar countermeasures is introduced,and its correctness is mathematically proved.A gaming scenario involving the AN/SPY-1 radar and a smart jammer is set up to analyze the influence of cognitive bias on game outcomes.Simulation results validate the effectiveness of the proposed method.
基金supported by the National Natural Science Foundation of China(Grant Nos.12274313,62275184,and 62411540033)Collaborative Innovation Center of Suzhou Nano Science and Technology,Suzhou Basic Research Project(Grant No.SJC2023003)+1 种基金the Gusu Leading Talent Plan for Scientific and Technological Innovation and Entrepreneurship(Grant No.ZXL2024400)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Perfect anomalous reflections have been demonstrated in optical phase gradient metasurfaces(PGMs),but they suffer from single-frequency(narrow-band)response due to the intrinsic limitation of natural geometric periodicity.Here,we provide both numerical and analytical evidence that a depth gradient metasurface can achieve discrete ultra-broadband perfect anomalous reflection in the microwave range in the absence of geometric periodicity.Remarkably,by adjusting the operating frequency of the incident wave,the same effect can be steadily obtained via a physically equivalent phase periodicity in the PGM.Based on this mechanism,a perfect retroreflector with a broadband response ranging from 1 GHz to 40 GHz is realized.Our work has promising applications in communication,source tracking,and military satellites.
文摘4 When you buy something,do you buy new or usecP Both can be good.When you buy things new,they're in perfect condition.These things usually last longer because they're new.New things also often have the newest features and design.
基金the support form the National Natural Science Foundation of China(Grant Nos.51606158,11604311,12074151)the Funded by the Guangxi Science and Technology Base and Talent Special Project(Grant No.AD21075009)+3 种基金the funded by the Sichuan Science and Technology Program(Grant No.2021JDRC0022)the Open Fund of the Key Laboratory for Metallurgical Equipment and Control Technology of Ministry of Education in Wuhan University of Science and Technology,China(Grant Nos.MECOF2022B01MECOF2023B04)the Project supported by Guangxi Key Laboratory of Precision Navigation Technology and Application,Guilin University of Electronic Technology(Grant No.DH202321)。
文摘This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene.By comparing the simulated experimental data with theoretical derivations,it was found that the absorbance of the material can be sustained above 90%in the frequency range of 2.78 to 7.14(4.36)THz,of which the absorption rate exceeds 99%in the frequency range of 4.1–4.54(0.44)THz,and remarkably,perfect absorption is achieved at4.32 THz.In the range of 2.78–7.14 THz,the average absorption rate is 96.1%,by adjusting the physical size of the graphene layer pattern,we can modify the working band gap of the absorber.By applying a voltage to modulate the Fermi level of graphene,we can increase the absorption bandwidth.When the chemical potential is 1.0 e V,at the bandwidth of 4.36 THz,its absorption rate exceeds 90%.The working principle of absorbing materials was deeply explored using the principles of electromagnetic field distribution and impedance adaptation.Through detailed analysis of different polarization states and incident angles,we found that the absorber is not sensitive to polarization due to its symmetrical structure,and found that it exhibits low sensitivity at incidence angles.In addition,after comparative analysis,significant differences were observed in the absorption efficiency of the absorber under various relaxation time conditions,and the obtained data were elaborated in detail using the carrier mechanism of plasma vibration.We found that in addition to obtaining an almost perfect absorber with wide band by adjusting the parameters,it is also feasible to obtain an approximately narrow band absorber by changing the relaxation time without having to remanufacture the structure.The absorber offers several advantages,including tunability,a wide absorption band,a high absorption rate,polarization insensitivity,and a simple structure.Therefore,this absorber exhibits great potential for absorption,monitoring,and sensing in the terahertz band.
文摘In this study,the wave motion in elastodynamics for unbounded media is modeled using an unsplit-field perfectly matched layer(PML)formulation that is solved by employing an isogeometric analysis(IGA).In the adopted combination,the non-uniform rational B-spline(NURBS)functions are employed as basis functions.Moreover,the unbounded and artificial domains,defined in the PML method,are contained in a single patch domain.Based on the proposed scheme,the approximation of the geometry problem is set in a new scheme in which the PML’s absorbing and attenuation properties and the description of traveling waves can be represented.This includes a higher continuity and smoother approximation of the computed domain.As high-order NURBS basis functions are non-interpolatory,a penalty method is present to apply a time-dependent displacement load.The performance of the NURBS-based PML is analyzed through numerical examples for 1D and 2D domains,considering homogeneous and heterogeneous media.Further,we verify the long-time numerical stability of the present method.The developed method can be used to simulate hypothetical stratified domains commonly encountered in soil-structure interaction analyses.
基金supported by the National Natural Science Foundation of China(No.61505160)the Innovation Capability Support Program of Shaanxi(No.2018KJXX-042)+1 种基金the Natural Science Basic Research Program of Shaanxi(No.2019JM-084)the State Key Laboratory of Transient Optics and Photonics(No.SKLST202108)。
文摘Broadband and perfect terahertz absorber based on multilayer metamaterial using cross-ring patterned structures is proposed and investigated.The structure of the absorber is double absorption layers consisting of a chromium cross ring and eight isosceles right triangles.The unique structure of the double absorbing layers excites the electric dipole multimode resonance,giving rise to high absorption performance.Meanwhile,the influence of construal parameters on absorber behavior is also discussed.The numerical results show that the absorption achieves over 90%ranging from 2.45 THz to 6.25 THz and 99%absorption in the range of 3.7—5.3 THz.The realization of broadband and perfect absorber is described using the impedance matching principle.It is obviously found that the absorber is insensitive to the high angle of incidence for both transverse electric(TE)and transverse magnetic(TM)polarizations.Compared with the former reports,this absorber has remarkable improved absorption efficiency and smaller period.The terahertz absorber may be found applications in the fields of energy capture and thermal detection.
基金supported by the Undergraduate Training Program for Innovation and Entrepreneurship,Soochow University(Grant No.202410285001Z)the National Natural Science Foundation of China(Grant Nos.12274313 and 12374293)。
文摘Acoustic wave isolation and noise reduction are significant challenges in the fields of physics and various applications.Traditional noise-control devices are often hampered by substantial size limitations,and their operational efficacy is generally restricted to planar waveforms.In this study,we demonstrate perfect confinement of acoustic vortex waves using an acoustic metacage consisting of phase-gradient metasurfaces.By leveraging the parity-reversed diffraction rule of phase-gradient metasurfaces,the designed metacage exhibited remarkable capabilities for the perfect confinement of acoustic vortex waves,showing robust performance even in the presence of source offsets.These findings present a promising strategy for developing precise and adaptable acoustic confinement technologies.
文摘Each year,Lin Haiyan,president of the Chinatown Foundation in Mauritius,dedicates significant time and effort to organising the Spring Festival celebrations.During the Spring Festival season in February 2024,the Mauritius National Multi-Sport Complex was adorned with large red lanterns and Chinese knots,creating a vibrant setting for the festivities.The event featured captivating performances,including lion and dragon dances,parades showcasing traditional Chinese women’s clothing,or qipao,singing,and tai chi demonstrations,providing the perfect atmosphere to celebrate the Chinese New Year.
基金supported by the National Natural Science Foundation of China(NSFC)(No.12204381,62205370)the fund of Natural Science Fundamental Research Program of Shaanxi Province(2023-JC-QN-0645)+1 种基金Startup Funding from Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Science(24JR521001)Shanghai Magnolia Talent Plan Pujiang Project(24PJD125).
文摘We theoretically and experimentally investigate thermal dynamics involved soliton microcomb generation in silicon oxynitride microresonators. Importantly, auxiliary laser heat balance scheme with flexible thermal manipulation is introduced to circumvent thermal instability and the intra-cavity temperature can be tuned from 60 ℃ to 41.5 ℃ via the commercial thermoelectric controller. As a result, various perfect soliton states with ultra-smooth spectral envelopes are observed on a well-designed and fabricated microresonator with homogeneous sidewall and thickness where spatial modes interaction and distortion are eliminated. The pre-reported spectral abrupt jumps due to mode hybridization are completely avoided and solitons tail oscillation vanishes simultaneously. This reported ideal coherent comb source without residual temporal and spectral noise will facilitate practical applications such as spectroscopy, ranging and astrocomb calibration.
基金upported by the Guangdong Provincial Pearl River Talents Program(Grant No.2019ZT08Z779)the National Natural Science Foundation of China(Grant Nos.U21A20509 and 62205124).
文摘Metal micro-nano grating has received much attention due to its ability to provide high-efficiency light absorption.However,the current research scales of these metal gratings are focused on subwavelengths,and little attention has been paid to the absorption properties of metal gratings at other scales.We investigate the absorption properties of metal gratings based on surface plasmon resonance(SPR)across the scales from superwavelength to subwavelength.Under grazing incidence,we observe continuous strong absorption phenomena from superwavelength to subwavelength Al triangle-groove gratings(TGGs).Perfect absorption is realized at the subwavelength scale,whereas the maximum absorption at all other scales exceeds 74%.The electric field distribution gives the mechanism of the strong absorption phenomenon attributed to SPR on the surface of Al TGGs at different scales.In particular,subwavelength Al TGGs have perfectly symmetric absorption properties for different blaze angles,and the symmetry is gradually broken as the grating period’s scale increases.Furthermore,taking Al gratings with varying groove shapes for example,we extend the equivalence rule of grating grooves to subwavelength from near-wavelength and explain the symmetric absorption properties in Al TGGs.We unify the research of metal grating absorbers outside the subwavelength scale to a certain extent,and these findings also open new perspectives for the design of metal gratings in the future.
基金supported in part by the National Natural Science Foundation of China(61933007,62273087,62273088,U21A2019)the Shanghai Pujiang Program of China(22PJ1400400)+2 种基金the Hainan Province Science and Technology Special Fund of China(ZDYF2022SHFZ105)the Royal Society of U.K.the Alexander von Humboldt Foundation of Germany
文摘In this paper, the attack detection problem is investigated for a class of closed-loop systems subjected to unknownbutbounded noises in the presence of stealthy attacks. The measurement outputs from the sensors are quantized before transmission.A specific type of perfect stealthy attack, which meets certain rather stringent conditions, is taken into account. Such attacks could be injected by adversaries into both the sensor-toestimator and controller-to-actuator channels, with the aim of disrupting the normal data flow. For the purpose of defending against these perfect stealthy attacks, a novel scheme based on watermarks is developed. This scheme includes the injection of watermarks(applied to data prior to quantization) and the recovery of data(implemented before the data reaches the estimator).The watermark-based scheme is designed to be both timevarying and hidden from adversaries through incorporating a time-varying and bounded watermark signal. Subsequently, a watermark-based attack detection strategy is proposed which thoroughly considers the characteristics of perfect stealthy attacks,thereby ensuring that an alarm is activated upon the occurrence of such attacks. An example is provided to demonstrate the efficacy of the proposed mechanism for detecting attacks.
基金supported by the National Natural Science Foundation of China(Grant Nos.11874270 and 12174228)the Shenzhen Basic Research Special Project(Grant No.JCYJ20240813141606009)。
文摘A theory based on the superposition principle is developed to uncover the basic physics of wave behavior in a finite grating of N unit cells.The theory reveals that bound states in the continuum(BICs)of infinite quality factor(Q-factor)can be supported by such a grating when perfect reflection is introduced at its boundaries.If geometrical perturbations are introduced into the structure,the dark BICs transform into bright quasi-BICs with finite Q-factor,maintaining spectral characteristics nearly identical to those of quasi-BICs supported by infinite gratings.When the boundaries are replaced with high-reflectivity metallic mirrors,the Q-factor of the resonant mode is reduced to be finite;however,it can be much larger than that in the corresponding nanostructure with open boundaries and can be tuned over a large range by varying the number of unit cells or boundary conditions.
基金Supported by the National Natural Science Foundation Youth Fund of China(Grant No.11701059)The Chongqing Natural Science Foundation Innovation and Development Joint Fund(Municipal Education Commission)(Grant No.CSTB2022NSCQ-LZX0003)The Open Research Fund of Key Laboratory of Nonlinear Analysis&Applications(Central China Normal University),Ministry of Education,P.R.China。
文摘Consider a graph G=(V,E).A perfect double Roman dominating function(PDRDF for short)is a function h:V→{0,1,2,3}that satisfies the condition∑_(y∈NG[x],h(y)≥1)h(y)=|{y∈NG(x):h(y)≥1}|+2 for any x∈V with h(x)≤1.The weightω(h)of this function is∑_(y∈V)h(y).The perfect double Roman domination number(PDRD-number)of G,denoted byγ_(dR)^(p)(G),is defined as the minimum weight among all PDRDFs of G.This article presents a comprehensive analysis of the PDRD-number of connected cographs,demonstrating that it falls within the set{2,3,4,5,6}.Furthermore,it establishes that for any integer i≥7,there is a connected cograph G such that its PDRD-number is equal to i.
