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| 1 | Variational Principle of Instability of Atmospheric Motions显示文摘Problems of instability of rotating atmospheric motions are investigated by using nonlinear governing equations and the variational principle. The method suggested in this paper is universal for obtaining criteria of instability in all models with all possible basic flows. For example, the model can be barotropic or baroclinic, layer or continuous, quasi-geostrophic or primitive equations; the basic flow can be zonal or nonzonal, steady or unsteady.Although the basic flows possess a great deal of variety, they all are the stationary points in the functional space determined by an appropriate invariant functional. The basic flow is an unsteady one if the conservation of angular momentum is included in the associated functional.The second variation, linear or nonlinear, gives the criteria of instability. Especially, the general criteria of instability for unsteady basic flow, orographically disturbed flow as well as nongeostrophic flow are first obtained by the method described in this paper.It is also | 曾庆存 | 1989 | Advances in Atmospheric Sciences1989，6，2： | 17 |
| 2 | Spin-decoupled metasurface for simultaneous detection of spin and orbital angular momenta via momentum transformation显示文摘With inherent orthogonality,both the spin angular momentum(SAM)and orbital angular momentum(OAM)of photons have been utilized to expand the dimensions of quantum information,optical communications,and information processing,wherein simultaneous detection of SAMs and OAMs with a single element and a single-shot measurement is highly anticipated.Here,a single azimuthal-quadratic phase metasurface-based photonic momentum transformation(PMT)is illustrated and utilized for vortex recognition.Since different vortices are converted into focusing patterns with distinct azimuthal coordinates on a transverse plane through PMT,OAMs within a large mode space can be determined through a single-shot measurement.Moreover,spin-controlled dual-functional PMTs are proposed for simultaneous SAM and OAM sorting,which is implemented by a single spin-decoupled metasurface that merges both the geometric phase and dynamic phase.Interestingly,our proposed method can detect vectorial vortices with both phase and polarization singularities,as well as superimposed vortices with a certain interval step.Experimental results obtained at several wavelengths in the visible band exhibit good agreement with the numerical modeling.With the merits of ultracompact device size,simple optical configuration,and prominent vortex recognition ability,our approach may underpin the development of integrated and high-dimensional optical and quantum systems. | Yinghui Guo Shicong Zhang Mingbo Pu Qiong He Jinjin Jin Mingfeng Xu Yaxin Zhang Ping Gao Xiangang Luo | 2021 | Light(Science & Applications)2021，10，4： | 14 |
| 3 | Electromagnetic chirality:from fundamentals to nontraditional chiroptical phenomena显示文摘Chirality arises universally across many different fields.Recent advancements in artificial nanomaterials have demonstrated chiroptical responses that far exceed those found in natural materials.Chiroptical phenomena are complicated processes that involve transitions between states with opposite parities,and solid interpretations of these observations are yet to be clearly provided.In this review,we present a comprehensive overview of the theoretical aspects of chirality in light,nanostructures,and nanosystems and their chiroptical interactions.Descriptions of observed chiroptical phenomena based on these fundamentals are intensively discussed.We start with the strong intrinsic and extrinsic chirality in plasmonic nanoparticle systems,followed by enantioselective sensing and optical manipulation,and then conclude with orbital angular momentum-dependent responses.This review will be helpful for understanding the mechanisms behind chiroptical phenomena based on underlying chiral properties and useful for interpreting chiroptical systems for further studies. | Jungho Mun Minkyung Kim Younghwan Yang Trevon Badloe Jincheng Ni Yang Chen Cheng-Wei Qiu Junsuk Rho | 2020 | Light(Science & Applications)2020，9，1： | 13 |
| 4 | Interference-assisted kaleidoscopic meta-plexer for arbitrary spin-wavefront manipulation显示文摘Achieving simultaneous polarization and wavefront control,especially circular polarization with the auxiliary degree of freedom of light and spin angular momentum,is of fundamental importance in many optical applications.Interferences are typically undesirable in highly integrated photonic circuits and metasurfaces.Here,we propose an interference-assisted metasurface-multiplexer(meta-plexer)that counterintuitively exploits constructive and destructive interferences between hybrid meta-atoms and realizes independent spin-selective wavefront manipulation.Such kaleidoscopic meta-plexers are experimentally demonstrated via two types of single-layer spinwavefront multiplexers that are composed of spatially rotated anisotropic meta-atoms.One type generates a spinselective Bessel-beam wavefront for spin-down light and a low scattering cross-section for stealth for spin-up light.The other type demonstrates versatile control of the vortex wavefront,which is also characterized by the orbital angular momentum of light,with frequency-switchable numbers of beams under linearly polarized wave excitation.Our findings offer a distinct interference-assisted concept for realizing advanced multifunctional photonics with arbitrary and independent spin-wavefront features.A variety of applications can be readily anticipated in optical diodes,isolators,and spin-Hall meta-devices without cascading bulky optical elements. | He-Xiu Xu Guangwei Hu Ying Li Lei Han Jianlin Zhao Yunming Sun Fang Yuan Guang-Ming Wang Zhi Hao Jiang Xiaohui Ling Tie Jun Cui Cheng-Wei Qiu | 2019 | Light(Science & Applications)2019，8，1： | 11 |
| 5 | Non-Acceleration Theorem in a Primitive Equation System: I. Acceleration of Zonal Mean Flow显示文摘Non-acceleration theorem in a primitive equation system is developed to investigate the influences of waves on the mean flow variation against external forcing. Numerical results show that mechanical forcing overwhelms thermal forcing in maintaining the mean flow in which the internal mechanical forcing associated with horizontal eddy flux of momentum plays the most important roles. Both internal forcing and external forcing are shown to be active and at the first place for the mean flow variations, whereas the forcing-induced mean meridional circulation is passive and secondary. It is also shown that the effects on mean flow of external mechanical forcing are concentrated in the lower troposphere, whereas those due to wave-mean flow interaction are more important in the upper troposphere. These act together and result in the vertically easterly shear in low latitudes and westerly shear in mid-latitudes. This vertical shear of mean flow is to some extent weakened by thermal forcing. | 吴国雄 陈彪 | 1989 | Advances in Atmospheric Sciences1989，6，1： | 11 |
| 6 | Optical orbital-angular-momentummultiplexed data transmission under high scattering显示文摘Multiplexing multiple orbital angular momentum(OAM)channels enables high-capacity optical communication.However,optical scattering from ambient microparticles in the atmosphere or mode coupling in optical fibers significantly decreases the orthogonality between OAM channels for demultiplexing and eventually increases crosstalk in communication.Here,we propose a novel scattering-matrix-assisted retrieval technique(SMART)to demultiplex OAM channels from highly scattered optical fields and achieve an experimental crosstalk of -13.8 dB in the parallel sorting of 24 OAM channels after passing through a scattering medium.The SMART is implemented in a self-built data transmission system that employs a digital micromirror device to encode OAM channels and realize reference-free calibration simultaneously,thereby enabling a high tolerance to misalignment.We successfully demonstrate highfidelity transmission of both gray and color images under scattering conditions at an error rate of <0.08%.This technique might open the door to high-performance optical communication in turbulent environments. | Lei Gong Qian Zhao Hao Zhang Xin-Yao Hu Kun Huang Jia-Miao Yang Yin-Mei Li | 2019 | Light(Science & Applications)2019，8，1： | 9 |
| 7 | DISCHARGE DISTRIBUTION IN STRAIGHT COMPOUND CHANNELS显示文摘The existing methods of computing the flow distribution in compound channels with flood plains have been summarized in this paper. Due to the lower precision of hydraulic computation for a compound cross-section with two flood plains, a new method called the momentum-exchange method herein, is presented and verified with experimental and field data. The results show that the new method is more effective than the previous ones. | Wang, Wei Cai, Jinde Xu, Weilin | 1998 | Journal of Hydrodynamics1998，10，4： | 8 |
| 8 | Deep-learning-assisted, two-stage phase control method for high-power mode-programmable orbital angular momentum beam generation显示文摘High-power mode-programmable orbital angular momentum(OAM)beams have received substantial attention in recent years.They are widely used in optical communication,nonlinear frequency conversion,and laser processing.To overcome the power limitation of a single beam,coherent beam combining(CBC)of laser arrays is used.However,in specific CBC systems used to generate structured light with a complex wavefront,eliminating phase noise and realizing flexible phase modulation proved to be difficult challenges.In this paper,we propose and demonstrate a two-stage phase control method that can generate OAM beams with different topological charges from a CBC system.During the phase control process,the phase errors are preliminarily compensated by a deep-learning(DL)network,and further eliminated by an optimization algorithm.Moreover,by modulating the expected relative phase vector and cost function,all-electronic flexible programmable switching of the OAM mode is realized.Results indicate that the proposed method combines the characteristics of DL for undesired convergent phase avoidance and the advantages of the optimization algorithm for accuracy improvement,thereby ensuring the high mode purity of the generated OAM beams.This work could provide a valuable reference for future implementation of high-power,fast switchable structured light generation and manipulation. | TIANYUE HOU YI AN QI CHANG PENGFEI MA JUN LI LIANGJIN HUANG DONG ZHI JIAN WU RONGTAO SU YANXING MA PU ZHOU | 2020 | Photonics Research2020，8，5： | 8 |
| 9 | Planetary Stationary Waves in the Atmosphere Part I: Orographic Stationary Waves显示文摘It is proposed that the orographic stationary waves are required by long-term balance of momentum in the atmosphere with zonally asymmetric orographic forcing. This hypothesis may be confirmed successfully with the theoretical model of geostrophic waves. In the Part I, we will explain the observed phase distributions of orographic stationary waves at middle and high latitudes of the Northern Hemisphere, according to the long-term balance of zonal momentum over the stationary orographic forcing. It is revealed that the geographic distribution of stationary waves depends not only on local topgraphy but also on mean circulation fields and angular momentum flux in the atmosphere. So these waves cannot be simulated by the models in a restricted area. | Yong. L. McHall | 1991 | Advances in Atmospheric Sciences1991，8，2： | 7 |
| 10 | An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow显示文摘The stall mechanism of the NASA Rotor 37 is investigated through the analysis of the critical flow structures near the stall under the transonic condition. The performance of the rotor with Circumferential Grooves Casing Treatment (CGCT) is also studied based on the Reynolds-Averaging Navier-Stokes approach. The study finds that stall margin improvement can be achieved without significant penalty on the efficiency for the two CGCT configurations applied. The effects of circumferential grooves on the critical flow structures are studied through the analysis of the tip leakage mass and momentum transport that further re-veal the CGCT mechanism. | HUANG XuDong,CHEN HaiXin,SHI Ke & FU Song School of Aerospace,Tsinghua University,Beijing 100084,China | 2010 | Science China(Physics,Mechanics & Astronomy)2010，53，2： | 7 |
| 11 | The research on the quantum tunneling characteristics and the radiation spectrum of the stationary axisymmetric black hole显示文摘At the event horizon and the cosmological horizon of the stationary axisymmetric Kerr-Newman black hole in the de Sitter space-time background, the tunneling rate of the charged particles is relevant with Bekenstein-Hawking entropy and the real radiation spectrum is not strictly pure thermal, but consistent with the underlying unitary theory in quantum mechanics. This is a feasible interpretation for the paradox of the black hole information loss. Taking the self-gravitation action, energy conservation, angular momentum conservation and charge conservation into account, the derived radiation spectrum is a correct amendment to the Hawking pure thermal spectrum. | YANG ShuZheng LI HuiLing JIANG QingQuan LIU MenQuan | 2007 | Science China(Physics,Mechanics & Astronomy)2007，50，2： | 7 |
| 12 | Measuring high orbital angular momentum of vortex beams with an improved multipoint interferometer显示文摘A multipoint interferometer(MI),uniformly distributed point-like pinholes in a circle,was proposed to measure the orbital angular momentum(OAM)of vortex beams[Phys.Rev.Lett.101,100801(2008)],which can be used for measuring OAM of light from astronomical sources.This is a simple and robust method;however,it is noted that this method is only available for low topological charge because the diffracted intensity patterns for vortex beams with higher OAM will repeat periodically.Here,we propose an improved multipoint interferometer(IMI)for measuring the OAM of an optical vortex with high topological charge.The structure of our IMI is almost the same as the MI,but the size of each pinhole is larger than a point in the MI.Such a small change enables each pinhole to get more phase information from the incident beams;accordingly,the IMI can distinguish any vortex beams with different OAM.We demonstrate its viability both theoretically and experimentally. | QI ZHAO MIAO DONG YIHUA BAI YUANJIE YANG | 2020 | Photonics Research2020，8，5： | 7 |
| 13 | Orbital angular momentum of the laser beam and the second order intensity moments显示文摘From the wave equation of a generalized beam the orbital angular momentum is studied. It is shown that the orbital angular momentum exists not only in the Laguerre-Gaussian beam, but in any beam with an angular-dependent structure. By calculating the second order intensity moments of the beam the relation between the orbital angular momentum and the second order moments 〈xθy〉, 〈yθx〉 is given. As an example the orbital angular momentum of the general astigmatic Gaussian beam is studied. | 高春清 魏光辉 HorstWeber | 2000 | Science China Mathematics2000，43，12： | 6 |
| 14 | Twisted optical communications using orbital angular momentum显示文摘Angular momentum, a fundamental physical quantity, can be divided into spin angular momentum(SAM) and orbital angular momentum(OAM) in electromagnetic waves. Helically-phased or twisted light beams carrying OAM that exploit the spatial structure physical dimension of electromagnetic waves have benefited wide applications ranging from optical manipulation to quantum information processing. Using the two distinct properties of OAM, i.e., inherent orthogonality and unbounded states in principle, one can develop OAM modulation and OAM multiplexing techniques for twisted optical communications. OAM multiplexing is an alternative space-division multiplexing approach employing an orthogonal mode basis related to the spatial phase structure. In this paper, we review the recent progress in twisted optical communications using OAM in free space and fiber. The basic concept of momentum, angular momentum, SAM, OAM and OAM-carrying twisted optical communications,key techniques and devices of OAM generation/(de)multiplexing/detection, high-capacity spectrally-efficient free-space OAM links, fiber-based OAM links, and OAM processing functions are presented. Ultra-high spectral efficiency and petabit-scale freespace data links are achieved benefiting from OAM multiplexing. The key techniques and challenges of twisted optical communications are also discussed. Twisted optical communications using OAM are compatible with other existing physical dimensions such as frequency/wavelength, amplitude, phase, polarization and time, opening a possible way to facilitate continuous increase of the aggregate transmission capacity and spectral efficiency through N-dimensional multiplexing. | Jian Wang | 2019 | Science China(Physics,Mechanics & Astronomy)2019，62，3： | 5 |
| 15 | Orbital angular momentum mode logical operation using optical diffractive neural network显示文摘Optical logical operations demonstrate the key role of optical digital computing,which can perform general-purpose calculations and possess fast processing speed,low crosstalk,and high throughput.The logic states usually refer to linear momentums that are distinguished by intensity distributions,which blur the discrimination boundary and limit its sustainable applications.Here,we introduce orbital angular momentum(OAM)mode logical operations performed by optical diffractive neural networks(ODNNs).Using the OAM mode as a logic state not only can improve the parallel processing ability but also enhance the logic distinction and robustness of logical gates owing to the mode infinity and orthogonality.ODNN combining scalar diffraction theory and deep learning technology is designed to independently manipulate the mode and spatial position of multiple OAM modes,which allows for complex multilight modulation functions to respond to logic inputs.We show that few-layer ODNNs successfully implement the logical operations of AND,OR,NOT,NAND,and NOR in simulations.The logic units of XNOR and XOR are obtained by cascading the basic logical gates of AND,OR,and NOT,which can further constitute logical half-adder gates.Our demonstrations may provide a new avenue for optical logical operations and are expected to promote the practical application of optical digital computing. | PEIPEI WANG WENJIE XIONG ZEBIN HUANG YANLIANG HE ZHIQIANG XIE JUNMIN LIU HUAPENG YE YING LI DIANYUAN FAN SHUQING CHEN | 2021 | Photonics Research2021，9，10： | 5 |
| 16 | The Structure of A Turbulent Jet in A Crossflow-Effect of Jet-Crossflow Velocity显示文摘A comprehensive numerical study on the three-dimensional structure of a turbulent jet in crossflow is performed. Thejet-to-crossflow velocity ratio (R) varies in the range of 2 ~ 16; both vertical jets and inclined jets without excess streamwisemomentum are considered. The numerical results of the standard two-equation k-~ model show that the turbulent structurecan be broadly categorised according to the jet-to-crossflow velocity ratio. For strong to moderate jet discharges, i.e. R >4, the jet is characterized by a longitudinal transition through a bent-over phase during which the jet becomes almost parallelwith the main freestream, to a sectional vortex-pair flow with double concentration maxima; the computed flow details andscalar mixing characteristics can be described by self-similar relations beyond a dimensionless distance of around 20 ~ 60.The similarity coefficients are only weakly dependent on R. The cross-section scalar field is kidney-shaped and bifurcated,with distinct double concentration maxima; the aspect ratio is found to be around 1.2. A loss in vertical momentum is ob-served and the added mass coefficient of the jet motion is found to be approximately 1. On the other hand, for weak jets instrong crossflow, i.e. R≤ 2, the lee of the jet is characterized by a negative pressure region. Although the double vortexflow can still be noted, the scalar field becomes more symmetrical and no longer bifurcated. The similarity coeffcients are al-so noticeably different. The predicted jet flow characteristics and mixing rates are well supported by experimental and field | 李行伟 匡翠萍 陈国谦 | 2002 | China Ocean Engineering2002，17，1： | 5 |
| 17 | Computing equations of water hammer in pseudo-homogeneous solid-liquid flow and their verification显示文摘In engineering practice, single-phase water hammer models are still employed to analyze the water hammer of solid-liquid flow. According to the characteristics of solid-liquid flow, continuity equations and momentum equations of pseudo-homogeneous flows are deduced, and a pseudo-homogeneous water hammer model is thus built and verified with experiment results. The characteristics of solid-liquid flow’s viscosity, resistance and wave velocity are considered in the model. Therefore, it has higher precision than a single-phase model. | 韩文亮 董曾南 柴宏恩 韩军 | 2000 | Science China(Technological Sciences)2000，43，2： | 5 |
| 18 | A review of multiple optical vortices generation: methods and applications显示文摘Optical vortices carrying orbital angular momentum(OAM)have attracted increasing interest in recent years.Optical vortices have seen a variety of emerging applications in optical manipulation,optical trapping,optical tweezers,optical vortex knots,imaging,microscopy,sensing,metrology,quantum information processing,and optical communications.In various optical vortices enabled applications,the generation of multiple optical vortices is of great importance.In this review article,we focus on the methods of multiple optical vortices generation and its applications.We review the methods for generating multiple optical vortices in three cases,i.e.,1-to-N collinear OAM modes,1-to-N OAM mode array and N-to-N collinear OAM modes.Diverse applications of multiple OAM modes in optical communications and non-communication areas are presented.Future trends,perspectives and opportunities are also discussed. | Long ZHU Jian WANG | 2019 | Frontiers of Optoelectronics2019，12，1： | 5 |
| 19 | Blocking Distributions in the Atmosphere显示文摘The zonal momentum generation in forced stationary waves may exceed the requirement for momentum balance after long, if the waves do not change their patterns. This suggests that the changes in stationary wave patterns would be required by maintenance of momentum balance over the external forcings. It will be found that the low frequency anomalies like blocking regimes may produce reversed zonal momentum variations, if they happen in the observed centre areas. The zonal momentum balance in the stationary waves may be maintained effectively by alternation between the normal and blocking circulation regimes. Thus, from the point of long-term zonal momentum balance, we may explain the geographical distributions of the blocking centres and the seasonal variations in blocking areas and frequencies. | Yong. L. McHall | 1991 | Advances in Atmospheric Sciences1991，8，3： | 4 |
| 20 | New technologies accelerate the exploration of non-coding RNAs in horticultural plants显示文摘Non-coding RNAs(ncRNAs),that is,RNAs not translated into proteins,are crucial regulators of a variety of biological processes in plants.While protein-encoding genes have been relatively well-annotated in sequenced genomes,accounting for a small portion of the genome space in plants,the universe of plant ncRNAs is rapidly expanding.Recent advances in experimental and computational technologies have generated a great momentum for discovery and functional characterization of ncRNAs.Here we summarize the classification and known biological functions of plant ncRNAs,review the application of next-generation sequencing(NGS)technology and ribosome profiling technology to ncRNA discovery in horticultural plants and discuss the application of new technologies,especially the new genome-editing tool clustered regularly interspaced short palindromic repeat(CRISPR)/CRISPR-associated protein 9(Cas9)systems,to functional characterization of plant ncRNAs. | Degao Liu Ritesh Mewalal Rongbin Hu Gerald A Tuskan Xiaohan Yang | 2017 | Horticulture Research2017，4，1： | 4 |
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