Orbital angular momentum(OAM)conversion is critical in understanding interactions between a structural sound field and a planar lattice.Herein,we explore the evolution of a monochromatic acoustic vortex beam(AVB)that ...Orbital angular momentum(OAM)conversion is critical in understanding interactions between a structural sound field and a planar lattice.Herein,we explore the evolution of a monochromatic acoustic vortex beam(AVB)that is scattered by a phononic crystal(PnC)or a correlated random lattice.The phenomenon is ascribed to the enhanced orbit–orbit angular momentum coupling induced by the band structure.By modifying the coupling condition,accurate and continuous micromanipulation of AVBs can be achieved,including the transverse/lateral gravity shift,the dynamics of the phase singularities,and the spatial distribution of acoustic pressure,etc.This research provides insight to the inhomogeneous coupling of AVBs with both propagating Bloch waves and localized Anderson modes,and may facilitate development of novel OAM-based acoustic devices for active sound field manipulation.展开更多
The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular mom...The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular momentum(OAM)modes in different non-line-of-sight situations are simulated.The errors of target accelerations in detection are calculated and compared based on the OAM spectra spreading by using two combinations of composite OAM modes in the keyhole space.According to the research,the effects about spectrum spreads of higher OAM modes are more obvious.The error in detection is mainly affected by OAM spectrum spreading,which can be reduced by reasonably using different combinations of OAM modes in different practical situations.The above results provide a reference idea for investigating keyhole effect when vortex electromagnetic wave is used to detect accelerations.展开更多
The fast and convenient demultiplex of optical vortex(OV) mode is crucial for its further application. We propose a novel approach that combines classic Young's doublet with an OV source to effectively identify th...The fast and convenient demultiplex of optical vortex(OV) mode is crucial for its further application. We propose a novel approach that combines classic Young's doublet with an OV source to effectively identify the OV mode through the analysis of interference patterns. The interference patterns of the OV source incident on the double slits can be perfectly illustrated by using both the classical double-slit interference method and the Huygens–Fresnel principle. The interference fringes will twist along the negative or positive direction of x axis when topological charge(TC)l>0 or l<0, and the degree of the movement varies with the TC, allowing for a quantitative display of the OV characteristics through the interference patterns. Additionally, we deduce analytically that the zeroth-order interference fringe has a linear relationship with the TC and the vertical position. These findings highlight the ability to identify the OV mode by analyzing the interference patterns produced by Young's doublet.展开更多
The vector vortex beam(VVB)has attracted significant attention due to its intrinsic diversity of information and has found great applications in both classical and quantum communications.However,a VVB is unavoidably a...The vector vortex beam(VVB)has attracted significant attention due to its intrinsic diversity of information and has found great applications in both classical and quantum communications.However,a VVB is unavoidably affected by atmospheric turbulence(AT)when it propagates through the free-space optical communication environment,which results in detection errors at the receiver.In this paper,we propose a VVB classification scheme to detect VVBs with continuously changing polarization states under AT,where a diffractive deep neural network(DDNN)is designed and trained to classify the intensity distribution of the input distorted VVBs,and the horizontal direction of polarization of the input distorted beam is adopted as the feature for the classification through the DDNN.The numerical simulations and experimental results demonstrate that the proposed scheme has high accuracy in classification tasks.The energy distribution percentage remains above 95%from weak to medium AT,and the classification accuracy can remain above 95%for various strengths of turbulence.It has a faster convergence and better accuracy than that based on a convolutional neural network.展开更多
Ion temperature gradient(ITG)-driven turbulence with embedded static magnetic islands is simulated by utilizing a gyrokinetic theory-based global turbulence transport code(GKNET)in this work.Different from the traditi...Ion temperature gradient(ITG)-driven turbulence with embedded static magnetic islands is simulated by utilizing a gyrokinetic theory-based global turbulence transport code(GKNET)in this work.Different from the traditional equilibrium circular magnetic-surface average(EMSA)method,an advanced algorithm that calculates the perturbed magnetic-surface average(PMSA)of the electric potential has been developed to precisely deal with the zonal flow component in a non-circular magnetic surface perturbed by magnetic islands.Simulations show that the electric potential vortex structure inside islands induced by the magnetic islands is usually of odd parity when using the EMSA method.It is found that the odd symmetry vortex can transfer into an even one after a steep zonal flow gradient,i.e.the flow shear has been built in the vicinity of the magnetic islands by adopting the PMSA algorithm.The phase of the potential vortex in the poloidal cross section is coupled with the zonal flow shear.Such an electric potential vortex mode may be of essential importance in wide topics,such as the turbulence spreading across magnetic islands,neoclassical tearing mode physics,and also the interaction dynamics between the micro-turbulence and MHD activities.展开更多
We propose a new method to generate terahertz perfect vortex beam with integer-order and fractional-order. A new optical diffractive element composed of the phase combination of a spherical harmonic axicon and a spira...We propose a new method to generate terahertz perfect vortex beam with integer-order and fractional-order. A new optical diffractive element composed of the phase combination of a spherical harmonic axicon and a spiral phase plate is designed and called spiral spherical harmonic axicon. A terahertz Gaussian beam passes through the spiral spherical harmonic axicon to generate a terahertz vortex beam. When only the topological charge number carried by spiral spherical harmonic axicon increases, the ring radius of terahertz vortex beam increases slightly, so the beam is shaped into a terahertz quasi-perfect vortex beam. Importantly, the terahertz quasi-perfect vortex beam can carry not only integer-order topological charge number but also fractional-order topological charge number. This is the first time that vortex beam and quasi-perfect vortex beam with fractional-order have been successfully realized in terahertz domain and experiment.展开更多
The perfect hybrid vector vortex beam(PHVVB)with helical phase wavefront structure has aroused significant concern in recent years,as its beam waist does not expand with the topological charge(TC).In this work,we inve...The perfect hybrid vector vortex beam(PHVVB)with helical phase wavefront structure has aroused significant concern in recent years,as its beam waist does not expand with the topological charge(TC).In this work,we investigate the spatial quantum coherent modulation effect with PHVVB based on the atomic medium,and we observe the absorption characteristic of the PHVVB with different TCs under variant magnetic fields.We find that the transmission spectrum linewidth of PHVVB can be effectively maintained regardless of the TC.Still,the width of transmission peaks increases slightly as the beam size expands in hot atomic vapor.This distinctive quantum coherence phenomenon,demonstrated by the interaction of an atomic medium with a hybrid vector-structured beam,might be anticipated to open up new opportunities for quantum coherence modulation and accurate magnetic field measurement.展开更多
Existing studies contend that latent heating(LH)will replace sensible heating(SH)to become the dominant factor affecting the development of the Tibetan Plateau vortex(TPV)after it moves off the Tibetan Plateau(TP).How...Existing studies contend that latent heating(LH)will replace sensible heating(SH)to become the dominant factor affecting the development of the Tibetan Plateau vortex(TPV)after it moves off the Tibetan Plateau(TP).However,in the process of the TPV moving off the TP requires that the airmass traverse the eastern slope of the Tibetan Plateau(ESTP)where the topography and diabatic heating(DH)conditions rapidly change.How LH gradually replaces SH to become the dominant factor in the development of the TPV over the ESTP is still not very clear.In this paper,an analysis of a typical case of a TPV with a long life history over the ESTP is performed by using multi-sourced meteorological data and model simulations.The results show that SH from the TP surface can change the TPV-associated precipitation distribution by temperature advection after the TPV moves off the TP.The LH can then directly promote the development of the TPV and has a certain guiding effect on the track of the TPV.The SH can control the active area of LH by changing the falling area of the TPV-associated precipitation,so it still plays a key role in the development and tracking of the TPV even though it has moved out of the main body of the TP.展开更多
A relatively high aerodynamic drag is an important factor that hinders the further acceleration of high-speed trains.Using the shear stress transport(SST)k-ωturbulence model,the effect of various vortex generator typ...A relatively high aerodynamic drag is an important factor that hinders the further acceleration of high-speed trains.Using the shear stress transport(SST)k-ωturbulence model,the effect of various vortex generator types on the aerodynamic characteristics of an ICE2(Inter-city Electricity)train has been investigated.The results indi-cate that the vortex generators with wider triangle,trapezoid,and micro-ramp arranged on the surface of the tail car can significantly change the distribution of surface pressure and affect the vorticity intensity in the wake.This alteration effectively reduces the resistance of the tail car.Meanwhile,the micro-ramp vortex generator with its convergent structure at the rear exhibits enhancedflow-guiding capabilities,resulting in a 15.4%reduction in the drag of the tail car.展开更多
In high harmonic generation(HHG),Laguerre–Gaussian(LG) beams are used to generate extreme ultraviolet(XUV)vortices with well-defined orbital angular momentum(OAM),which have potential applications in fields such as m...In high harmonic generation(HHG),Laguerre–Gaussian(LG) beams are used to generate extreme ultraviolet(XUV)vortices with well-defined orbital angular momentum(OAM),which have potential applications in fields such as microscopy and spectroscopy.An experimental study on the HHG driven by vortex and Gaussian beams is conducted in this work.It is found that the intensity of vortex harmonics is positively correlated with the laser energy and gas pressure.The structure and intensity distribution of the vortex harmonics exhibit significant dependence on the relative position between the gas jet and the laser focus.The ring-like structures observed in the vortex harmonics,and the interference of quantum paths provide an explanation for the distinct structural characteristics.Moreover,by adjusting the relative position between the jet and laser focus,it is possible to discern the contributions from different quantum paths.The optimization of the HH vortex field is applicable to the XUV,which opens up a new way for exploiting the potential in optical spin or manipulating electrons by using the photon with tunable orbital angular momentum.展开更多
We revisited the vortex states of 2H-NbSe_(2) towards zero fields by a low-temperature scanning tunneling microscope.Fine structures of the anisotropic vortex states were distinguished, one is a spatially non-splittin...We revisited the vortex states of 2H-NbSe_(2) towards zero fields by a low-temperature scanning tunneling microscope.Fine structures of the anisotropic vortex states were distinguished, one is a spatially non-splitting zero bias peak, and the other is an in-gap conductance anomaly resembling evolved crossing features around the center of the three nearest vortices.Both of them distribute solely along the next nearest neighboring direction of the vortex lattice and become unresolved in much higher magnetic fields, implying an important role played by the vortex–vortex interactions. To clarify these issues,we have studied the intrinsic vortex states of the isolated trapped vortex in zero fields at 0.45 K. It is concluded that the anisotropic zero bias peak is attributed to the superconducting gap anisotropy, and the spatially evolved crossing features are related to the vortex–vortex interaction. The vortex core size under the zero-field limit is determined. These results provide a paradigm for studying the inherent vortex states of type-II superconductors especially based on an isolated vortex.展开更多
An electron vortex beam(EVB) carrying orbital angular momentum(OAM) plays a key role in a series of fundamental scientific researches, such as chiral energy-loss spectroscopy and magnetic dichroism spectroscopy. So fa...An electron vortex beam(EVB) carrying orbital angular momentum(OAM) plays a key role in a series of fundamental scientific researches, such as chiral energy-loss spectroscopy and magnetic dichroism spectroscopy. So far, almost all the experimentally created EVBs manifest isotropic doughnut intensity patterns. Here, based on the correlation between local divergence angle of electron beam and phase gradient along azimuthal direction, we show that free electrons can be tailored to EVBs with customizable intensity patterns independent of the carried OAM. As proof-of-concept, by using computer generated hologram and designing phase masks to shape the incident free electrons in the transmission electron microscope, three structured EVBs carrying identical OAM are tailored to exhibit completely different intensity patterns. Furthermore, through the modal decomposition, we quantitatively investigate their OAM spectral distributions and reveal that structured EVBs present a superposition of a series of different eigenstates induced by the locally varied geometries. These results not only generalize the concept of EVB, but also demonstrate an extra highly controllable degree of freedom for electron beam manipulation in addition to OAM.展开更多
The dynamics of spin–orbit-coupled Bose–Einstein condensate with parity-time symmetry through a moving obstacle potential is simulated numerically. In the miscible two-component condensate, the formation of the K...The dynamics of spin–orbit-coupled Bose–Einstein condensate with parity-time symmetry through a moving obstacle potential is simulated numerically. In the miscible two-component condensate, the formation of the Kármán vortex street is observed in one component, while ‘the half-quantum vortex street' is observed in the other component. Other patterns of vortex shedding, such as oblique vortex dipoles, V-shaped vortex pairs, irregular turbulence, and combined modes of various wakes, can also be found. The ratio of inter-vortex spacing in one row to the distance between vortex rows is approximately0.18, which is less than the stability condition 0.28 of classical fluid. The drag force acting on the obstacle potential is simulated. The parametric regions of Kármán vortex street and other vortex patterns are calculated. The range of Kármán vortex street is surrounded by the region of combined modes. In addition, spin–orbit coupling disrupts the symmetry of the system and the gain-loss affects the local particle distribution of the system, which leads to the local symmetry breaking of the system, and finally influences the stability of the Kármán vortex street. Finally, we propose an experimental protocol to realize the Kármán vortex street in a system.展开更多
This paper investigates a new vortex wave imaging approach to improve the imaging quality of small metal targets of size less than 1.5 mm.Antennas with different spiral phase plates are designed to efficiently transmi...This paper investigates a new vortex wave imaging approach to improve the imaging quality of small metal targets of size less than 1.5 mm.Antennas with different spiral phase plates are designed to efficiently transmit vortex beams with orbital angular momentums(OAMs).By analyzing the OAM spectrum of the target,it was discovered that the predominant reflection contains a particular OAM mode that carries abundant azimuthal information.This can be explained by the OAM selectivity of the target and the guidance of the vortex transmitting beam.A simple reflection vortex imaging system was designed to capture the phase information.Measurement results show that the high image contrast reaches 14.9%,which is twice as high as that of the imaging without OAM.Both of simulations and experiments demonstrate that the vortex phase imaging approach proposed in this paper can effectively improve the imaging quality at 80 GHz.This approach is suitable for other millimeter wave imaging systems and is helpful to improve the resolution in anti-terrorism security checks.展开更多
The Northeastern China cold vortex(NCCV)is one type of strong cyclonic vortex that occurs near Northeastern China(NEC),and NCCV activities are typically accompanied by a series of hazardous weather.This paper employed...The Northeastern China cold vortex(NCCV)is one type of strong cyclonic vortex that occurs near Northeastern China(NEC),and NCCV activities are typically accompanied by a series of hazardous weather.This paper employed an automatic algorithm to identify the NCCVs from 1979 to 2018 and analyzed their circulation patterns and climatic impacts by using the defined NCCV intensity index(NCCVI).The analysis revealed that the NCCV activities in summer exhibited a strong inter-annual variability,with an obvious periodicity of 3-4 years and 6-7 years,but without significant trends.In years when the NCCVI was high,NEC experienced negative geopotential height anomalies,cyclonic circulation,and cooler temperature anomalies,which were conducive to the maintenance and development of NCCV activities.Furthermore,large amounts of water vapor converged in NEC through two transportation routes as the NCCVs intensified,leading to a significant positive(negative)correlation with the summer precipitation(surface temperature)in NEC.The Atlantic sea surface temperature(SST)anomalies were closely related to summer NCCV activities.As the Atlantic SST rose,large amounts of surface sensible and latent heat flux were transported into the lower troposphere,inducing a positive geopotential height anomaly that occurred on the east side of the heat source.As a result,an eastward diverging flow was formed in the upper troposphere and propagated downstream,i.e.,the eastward propagating Rossby wave train,which eventually led to a coupled circulation in the Ural Mountains and NEC,as well as more intensive NCCV activities in summer.展开更多
Mass plays a role in many physical phenomena, including the behavior of subatomic particles, the formation and behavior of stars and galaxies, and gravitational interactions between objects. The density of vacuum, 9.5...Mass plays a role in many physical phenomena, including the behavior of subatomic particles, the formation and behavior of stars and galaxies, and gravitational interactions between objects. The density of vacuum, 9.5 × 10−27 kg/m3, is a crucial parameter in the theory of cosmic inflation and is responsible for the accelerated expansion of the universe in its early stages. This vacuum energy interacts with matter and manifests itself as mass, which can be described as flow and vortex formation using the laws of hydrodynamics. The vortex model of elementary particles, in conjunction with the laws of hydrodynamics, provides an elegant explanation for the origin of mass and the relationship between mass and energy, with profound implications for the behavior of objects at high velocities and strong gravitational fields. The vacuum behaves as a compressible superfluid, thus elementary particles can be described as vortices of the vacuum. The equations of hydrodynamics for vortices can be applied to describe the nature and value of the mass of particles. The implications of understanding the nature of mass are vast and profound. From elucidating the fundamental properties of particles to informing the design of advanced materials and technologies, this knowledge is indispensable. It drives advancements across numerous fields, transforming both our theoretical understanding and practical capabilities. Continued research into the nature of mass promises to unlock further insights, fostering innovation and expanding the frontiers of science and technology.展开更多
Drawing upon the electromagnetic conversion formulas in a continuous conductive medium,an extensive examination for total current law and Faraday’s law of electromagnetic induction(Faraday’s law)is undertaken to exp...Drawing upon the electromagnetic conversion formulas in a continuous conductive medium,an extensive examination for total current law and Faraday’s law of electromagnetic induction(Faraday’s law)is undertaken to expound on the laws of electromagnetic induction and conversion.The longitudinal wave term of Faraday’s law is reinstated to render it suitable for theoretical derivation of the LEM(Longitudinal Electromagnetic Wave)equation.Subsequently,we formulate the wave and energy equations for electric P-wave based on reevaluated total current law and modified Faraday’s law;meanwhile proposing a propagation mode that reveals its mechanisms absorbing free energy for LEM waves in a conductor predicated on interaction between scalar electric field and vortex magnetic field.Furthermore,through theoretical derivations based on LEM waves,insights into concealed relationships between electric P-wave and electromagnetism scalar potential are disclosed alongside the constraint equation between the wave velocities of LEM wave and TEM(Transverse Electromagnetic)waves,unveiling the significance of LEM wave.展开更多
BACKGROUND A previous study compared vortexing and Maki techniques for the diagnosis of catheter-related bloodstream infection(CRBSI),and concluded that vortexing was not superior to Maki method.AIM To determine wheth...BACKGROUND A previous study compared vortexing and Maki techniques for the diagnosis of catheter-related bloodstream infection(CRBSI),and concluded that vortexing was not superior to Maki method.AIM To determine whether the combined use of vortexing and Maki techniques provides profitability versus the Maki technique for the diagnosis of catheter tip colonization(CTC)and CRBSI.METHODS Observational and prospective study carried out in an Intensive Care Unit.Patients with suspected catheter-related infection(CRI)and with one central venous catheter for at least 7 days were included.The area under the curve(AUC)of the Maki technique,the vortexing technique and the combination of both techniques for the diagnosis of CTC and CRBSI were compared.RESULTS We included 136 episodes of suspected CRI.We found 21 cases of CTC of which 10 were also CRBSI cases.Of the 21 CTC episodes,18(85.7%)were diagnosed by Maki technique and vortexing technique,3(14.3%)only by the technique of Maki,and none only by technique of vortexing.Of the 10 CRBSI episodes,9(90.0%)were diagnosed by the techniques of Maki and vortexing,1(10.0%)was diagnosed only by the technique of Maki,and none only by the technique of vortexing.We no found differences in the comparison of AUC between the technique of Maki and the combination of Maki and vortexing techniques for the diagnosis of CTC(P=0.99)and CRBSI(P=0.99).CONCLUSION The novel finding of our study was that the combined use of vortexing and Maki techniques did not provide profitability to the technique of Maki alone to CRBSI diagnosis of.展开更多
Background:Shear stress-induced erythrocyte damage,namely hemolysis,is an important problem in the development of blood-contacting medical devices such as mechanical circulatory support devices.Computational fluid dyn...Background:Shear stress-induced erythrocyte damage,namely hemolysis,is an important problem in the development of blood-contacting medical devices such as mechanical circulatory support devices.Computational fluid dynamics simulation combined with hemolysis prediction models have been widely used to predict hemolysis.With the development of hemolysis prediction models,the new hemolysis prediction model requires more experimental data to verify.In addition,the difference of in vitro blood-shearing device also affect the accuracy of hemolysis prediction.Methods:To address these problems,a new in vitro blood-shearing device(vortex oscillator)was used to further verify the accuracy of the hemolysis prediction models,and to guide the optimal design of blood-contacting medical devices such as mechanical circulatory support devices.Firstly,the flow field information such as wall stress and velocity of the vortex oscillator under different speeds was analyzed.Secondly,different hemolysis prediction models were used to calculate hemolysis,and the predicted data was compared with the experimental data.Results and Conclusion:In this study,the flow field information inside the vortex oscillator at high rotational speeds was systematically investigated,and the prediction of hemolysis was carried out.The results showed that the predicted data of hemolysis was significantly different from the experimental data,which indicated that it was urgent to establish a standardized in vitro blood-shearing platform to provide a reference for accurate hemolysis prediction.展开更多
基金the National Natural Sciencefoundation of China (Grant No. 12174085)the FundamentalResearch Funds for the Central Universities (GrantNo. B220202018)+1 种基金the Basic Science (Natural Science) ResearchProject for the Universities of Jiangsu Province (GrantNo. 23KJD140002)Natural Science Foundation of Nantong(Grant No. JC2023081).
文摘Orbital angular momentum(OAM)conversion is critical in understanding interactions between a structural sound field and a planar lattice.Herein,we explore the evolution of a monochromatic acoustic vortex beam(AVB)that is scattered by a phononic crystal(PnC)or a correlated random lattice.The phenomenon is ascribed to the enhanced orbit–orbit angular momentum coupling induced by the band structure.By modifying the coupling condition,accurate and continuous micromanipulation of AVBs can be achieved,including the transverse/lateral gravity shift,the dynamics of the phase singularities,and the spatial distribution of acoustic pressure,etc.This research provides insight to the inhomogeneous coupling of AVBs with both propagating Bloch waves and localized Anderson modes,and may facilitate development of novel OAM-based acoustic devices for active sound field manipulation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11804073 and 61775050).
文摘The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular momentum(OAM)modes in different non-line-of-sight situations are simulated.The errors of target accelerations in detection are calculated and compared based on the OAM spectra spreading by using two combinations of composite OAM modes in the keyhole space.According to the research,the effects about spectrum spreads of higher OAM modes are more obvious.The error in detection is mainly affected by OAM spectrum spreading,which can be reduced by reasonably using different combinations of OAM modes in different practical situations.The above results provide a reference idea for investigating keyhole effect when vortex electromagnetic wave is used to detect accelerations.
基金Project supported by the National Key Research and Development Program of China (Grant Nos.2020YFA0710100 and 2023YFA1407100)the National Natural Science Foundation of China (Grant Nos.92050102 and 12374410)+2 种基金the Jiangxi Provincial Natural Science Foundation (Grant No.20224ACB201005)the Fundamental Research Funds for the Central Universities (Grant Nos.20720230102 and 20720220033)China Scholarship Council (Grant No.202206310009)。
文摘The fast and convenient demultiplex of optical vortex(OV) mode is crucial for its further application. We propose a novel approach that combines classic Young's doublet with an OV source to effectively identify the OV mode through the analysis of interference patterns. The interference patterns of the OV source incident on the double slits can be perfectly illustrated by using both the classical double-slit interference method and the Huygens–Fresnel principle. The interference fringes will twist along the negative or positive direction of x axis when topological charge(TC)l>0 or l<0, and the degree of the movement varies with the TC, allowing for a quantitative display of the OV characteristics through the interference patterns. Additionally, we deduce analytically that the zeroth-order interference fringe has a linear relationship with the TC and the vertical position. These findings highlight the ability to identify the OV mode by analyzing the interference patterns produced by Young's doublet.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62375140 and 62001249)the Open Research Fund of National Laboratory of Solid State Microstructures(Grant No.M36055).
文摘The vector vortex beam(VVB)has attracted significant attention due to its intrinsic diversity of information and has found great applications in both classical and quantum communications.However,a VVB is unavoidably affected by atmospheric turbulence(AT)when it propagates through the free-space optical communication environment,which results in detection errors at the receiver.In this paper,we propose a VVB classification scheme to detect VVBs with continuously changing polarization states under AT,where a diffractive deep neural network(DDNN)is designed and trained to classify the intensity distribution of the input distorted VVBs,and the horizontal direction of polarization of the input distorted beam is adopted as the feature for the classification through the DDNN.The numerical simulations and experimental results demonstrate that the proposed scheme has high accuracy in classification tasks.The energy distribution percentage remains above 95%from weak to medium AT,and the classification accuracy can remain above 95%for various strengths of turbulence.It has a faster convergence and better accuracy than that based on a convolutional neural network.
基金partially supported by the National Key R&D Program of China(No.2019YFE0300002)by National Natural Science Foundation of China(Nos.U1967206 and 12275071)。
文摘Ion temperature gradient(ITG)-driven turbulence with embedded static magnetic islands is simulated by utilizing a gyrokinetic theory-based global turbulence transport code(GKNET)in this work.Different from the traditional equilibrium circular magnetic-surface average(EMSA)method,an advanced algorithm that calculates the perturbed magnetic-surface average(PMSA)of the electric potential has been developed to precisely deal with the zonal flow component in a non-circular magnetic surface perturbed by magnetic islands.Simulations show that the electric potential vortex structure inside islands induced by the magnetic islands is usually of odd parity when using the EMSA method.It is found that the odd symmetry vortex can transfer into an even one after a steep zonal flow gradient,i.e.the flow shear has been built in the vicinity of the magnetic islands by adopting the PMSA algorithm.The phase of the potential vortex in the poloidal cross section is coupled with the zonal flow shear.Such an electric potential vortex mode may be of essential importance in wide topics,such as the turbulence spreading across magnetic islands,neoclassical tearing mode physics,and also the interaction dynamics between the micro-turbulence and MHD activities.
基金Project supported by the Fundamental Research Funds for the Central Universities,China (Grant No.2017KFYXJJ029)。
文摘We propose a new method to generate terahertz perfect vortex beam with integer-order and fractional-order. A new optical diffractive element composed of the phase combination of a spherical harmonic axicon and a spiral phase plate is designed and called spiral spherical harmonic axicon. A terahertz Gaussian beam passes through the spiral spherical harmonic axicon to generate a terahertz vortex beam. When only the topological charge number carried by spiral spherical harmonic axicon increases, the ring radius of terahertz vortex beam increases slightly, so the beam is shaped into a terahertz quasi-perfect vortex beam. Importantly, the terahertz quasi-perfect vortex beam can carry not only integer-order topological charge number but also fractional-order topological charge number. This is the first time that vortex beam and quasi-perfect vortex beam with fractional-order have been successfully realized in terahertz domain and experiment.
基金Project supported by the Youth Innovation Promotion Association CASState Key Laboratory of Transient Optics and Photonics Open Topics (Grant No. SKLST202222)
文摘The perfect hybrid vector vortex beam(PHVVB)with helical phase wavefront structure has aroused significant concern in recent years,as its beam waist does not expand with the topological charge(TC).In this work,we investigate the spatial quantum coherent modulation effect with PHVVB based on the atomic medium,and we observe the absorption characteristic of the PHVVB with different TCs under variant magnetic fields.We find that the transmission spectrum linewidth of PHVVB can be effectively maintained regardless of the TC.Still,the width of transmission peaks increases slightly as the beam size expands in hot atomic vapor.This distinctive quantum coherence phenomenon,demonstrated by the interaction of an atomic medium with a hybrid vector-structured beam,might be anticipated to open up new opportunities for quantum coherence modulation and accurate magnetic field measurement.
基金supported by the National Natural Science Foundation of China(Grant Nos.42175002,42030611,42075013)the Natural Science Foundation of Sichuan,China(Grant No.2023NSFSC0242)the Innovation Team Fund of Southwest Regional Meteorological Center,China Meteorological Administration(Grant No.XNQYCXTD-202202)。
文摘Existing studies contend that latent heating(LH)will replace sensible heating(SH)to become the dominant factor affecting the development of the Tibetan Plateau vortex(TPV)after it moves off the Tibetan Plateau(TP).However,in the process of the TPV moving off the TP requires that the airmass traverse the eastern slope of the Tibetan Plateau(ESTP)where the topography and diabatic heating(DH)conditions rapidly change.How LH gradually replaces SH to become the dominant factor in the development of the TPV over the ESTP is still not very clear.In this paper,an analysis of a typical case of a TPV with a long life history over the ESTP is performed by using multi-sourced meteorological data and model simulations.The results show that SH from the TP surface can change the TPV-associated precipitation distribution by temperature advection after the TPV moves off the TP.The LH can then directly promote the development of the TPV and has a certain guiding effect on the track of the TPV.The SH can control the active area of LH by changing the falling area of the TPV-associated precipitation,so it still plays a key role in the development and tracking of the TPV even though it has moved out of the main body of the TP.
基金supported by the National Natural Science Foundation of China(12372049)Sichuan Science and Technology Program(2023JDRC0062)+1 种基金Science and Technology Program of China National Accreditation Service for Conformity Assessment(2022CNAS15)the Independent Project of State Key Laboratory of Rail Transit Vehicle System(2023TPL-T06).
文摘A relatively high aerodynamic drag is an important factor that hinders the further acceleration of high-speed trains.Using the shear stress transport(SST)k-ωturbulence model,the effect of various vortex generator types on the aerodynamic characteristics of an ICE2(Inter-city Electricity)train has been investigated.The results indi-cate that the vortex generators with wider triangle,trapezoid,and micro-ramp arranged on the surface of the tail car can significantly change the distribution of surface pressure and affect the vorticity intensity in the wake.This alteration effectively reduces the resistance of the tail car.Meanwhile,the micro-ramp vortex generator with its convergent structure at the rear exhibits enhancedflow-guiding capabilities,resulting in a 15.4%reduction in the drag of the tail car.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974137,92250306,and 12304302)the National Key Program for Science and Technology Research and Development(Grant No.2019YFA0307700)+1 种基金the Natural Science Foundation of Jilin Province,China(Grant Nos.YDZJ202101ZYTS157 and YDZJ202201ZYTS314)the Scientific Research Foundation of Jilin Provincial Education Department,China(Grant No.JJKH20230283KJ)。
文摘In high harmonic generation(HHG),Laguerre–Gaussian(LG) beams are used to generate extreme ultraviolet(XUV)vortices with well-defined orbital angular momentum(OAM),which have potential applications in fields such as microscopy and spectroscopy.An experimental study on the HHG driven by vortex and Gaussian beams is conducted in this work.It is found that the intensity of vortex harmonics is positively correlated with the laser energy and gas pressure.The structure and intensity distribution of the vortex harmonics exhibit significant dependence on the relative position between the gas jet and the laser focus.The ring-like structures observed in the vortex harmonics,and the interference of quantum paths provide an explanation for the distinct structural characteristics.Moreover,by adjusting the relative position between the jet and laser focus,it is possible to discern the contributions from different quantum paths.The optimization of the HH vortex field is applicable to the XUV,which opens up a new way for exploiting the potential in optical spin or manipulating electrons by using the photon with tunable orbital angular momentum.
基金Project supported by the National Key R&D Program of China (Grant No. 2022YFA1403203)the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302802)+3 种基金the National Natural Science Foundation of China (Grant Nos. 12074002, 12374133, and 11804379)the Major Basic Program of Natural Science Foundation of Shandong Province (Grant No. ZR2021ZD01)the supports of the National Natural Science Foundation of China (Grant No. 12274001)the Natural Science Foundation of Anhui Province (Grant No. 2208085MA09)。
文摘We revisited the vortex states of 2H-NbSe_(2) towards zero fields by a low-temperature scanning tunneling microscope.Fine structures of the anisotropic vortex states were distinguished, one is a spatially non-splitting zero bias peak, and the other is an in-gap conductance anomaly resembling evolved crossing features around the center of the three nearest vortices.Both of them distribute solely along the next nearest neighboring direction of the vortex lattice and become unresolved in much higher magnetic fields, implying an important role played by the vortex–vortex interactions. To clarify these issues,we have studied the intrinsic vortex states of the isolated trapped vortex in zero fields at 0.45 K. It is concluded that the anisotropic zero bias peak is attributed to the superconducting gap anisotropy, and the spatially evolved crossing features are related to the vortex–vortex interaction. The vortex core size under the zero-field limit is determined. These results provide a paradigm for studying the inherent vortex states of type-II superconductors especially based on an isolated vortex.
基金This work is supported in part by the Key Research and Development Program from Ministry of Science and Technology of China(2022YFA1205000)National Natural Science Foundation of China(12274217 and 62105142)+1 种基金Natural Science Foundation of Jiangsu Province(BK20220068 and BK20212004)Fundamental Research Funds for Central Universities.
文摘An electron vortex beam(EVB) carrying orbital angular momentum(OAM) plays a key role in a series of fundamental scientific researches, such as chiral energy-loss spectroscopy and magnetic dichroism spectroscopy. So far, almost all the experimentally created EVBs manifest isotropic doughnut intensity patterns. Here, based on the correlation between local divergence angle of electron beam and phase gradient along azimuthal direction, we show that free electrons can be tailored to EVBs with customizable intensity patterns independent of the carried OAM. As proof-of-concept, by using computer generated hologram and designing phase masks to shape the incident free electrons in the transmission electron microscope, three structured EVBs carrying identical OAM are tailored to exhibit completely different intensity patterns. Furthermore, through the modal decomposition, we quantitatively investigate their OAM spectral distributions and reveal that structured EVBs present a superposition of a series of different eigenstates induced by the locally varied geometries. These results not only generalize the concept of EVB, but also demonstrate an extra highly controllable degree of freedom for electron beam manipulation in addition to OAM.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12065022 and 12147213)。
文摘The dynamics of spin–orbit-coupled Bose–Einstein condensate with parity-time symmetry through a moving obstacle potential is simulated numerically. In the miscible two-component condensate, the formation of the Kármán vortex street is observed in one component, while ‘the half-quantum vortex street' is observed in the other component. Other patterns of vortex shedding, such as oblique vortex dipoles, V-shaped vortex pairs, irregular turbulence, and combined modes of various wakes, can also be found. The ratio of inter-vortex spacing in one row to the distance between vortex rows is approximately0.18, which is less than the stability condition 0.28 of classical fluid. The drag force acting on the obstacle potential is simulated. The parametric regions of Kármán vortex street and other vortex patterns are calculated. The range of Kármán vortex street is surrounded by the region of combined modes. In addition, spin–orbit coupling disrupts the symmetry of the system and the gain-loss affects the local particle distribution of the system, which leads to the local symmetry breaking of the system, and finally influences the stability of the Kármán vortex street. Finally, we propose an experimental protocol to realize the Kármán vortex street in a system.
基金Science,Technology and Innovation Project of Xiongan New Area (Grant No.2022XAGG0181)LiaoNing Revitalization Talents Program (Grant No.XLYC2007074)+1 种基金Shenyang Young and Middle-aged Science and Technology Innovation Talent Support Program (Grant No.RC220523)Natural Science Foundation of Liaoning Province of China (Grant Nos.2022-YGJC-03 and 2022-MS-034)to provide fund for conducting experiments。
文摘This paper investigates a new vortex wave imaging approach to improve the imaging quality of small metal targets of size less than 1.5 mm.Antennas with different spiral phase plates are designed to efficiently transmit vortex beams with orbital angular momentums(OAMs).By analyzing the OAM spectrum of the target,it was discovered that the predominant reflection contains a particular OAM mode that carries abundant azimuthal information.This can be explained by the OAM selectivity of the target and the guidance of the vortex transmitting beam.A simple reflection vortex imaging system was designed to capture the phase information.Measurement results show that the high image contrast reaches 14.9%,which is twice as high as that of the imaging without OAM.Both of simulations and experiments demonstrate that the vortex phase imaging approach proposed in this paper can effectively improve the imaging quality at 80 GHz.This approach is suitable for other millimeter wave imaging systems and is helpful to improve the resolution in anti-terrorism security checks.
基金National Natural Science Foundation of China(41975073,42274215)Wuxi University Research Start-up Fund for Introduced Talents (2023r037)+1 种基金Qinglan Project of Jiangsu Province for DING Liu-guan"333"Project of Jiangsu Province for DING Liu-guan
文摘The Northeastern China cold vortex(NCCV)is one type of strong cyclonic vortex that occurs near Northeastern China(NEC),and NCCV activities are typically accompanied by a series of hazardous weather.This paper employed an automatic algorithm to identify the NCCVs from 1979 to 2018 and analyzed their circulation patterns and climatic impacts by using the defined NCCV intensity index(NCCVI).The analysis revealed that the NCCV activities in summer exhibited a strong inter-annual variability,with an obvious periodicity of 3-4 years and 6-7 years,but without significant trends.In years when the NCCVI was high,NEC experienced negative geopotential height anomalies,cyclonic circulation,and cooler temperature anomalies,which were conducive to the maintenance and development of NCCV activities.Furthermore,large amounts of water vapor converged in NEC through two transportation routes as the NCCVs intensified,leading to a significant positive(negative)correlation with the summer precipitation(surface temperature)in NEC.The Atlantic sea surface temperature(SST)anomalies were closely related to summer NCCV activities.As the Atlantic SST rose,large amounts of surface sensible and latent heat flux were transported into the lower troposphere,inducing a positive geopotential height anomaly that occurred on the east side of the heat source.As a result,an eastward diverging flow was formed in the upper troposphere and propagated downstream,i.e.,the eastward propagating Rossby wave train,which eventually led to a coupled circulation in the Ural Mountains and NEC,as well as more intensive NCCV activities in summer.
文摘Mass plays a role in many physical phenomena, including the behavior of subatomic particles, the formation and behavior of stars and galaxies, and gravitational interactions between objects. The density of vacuum, 9.5 × 10−27 kg/m3, is a crucial parameter in the theory of cosmic inflation and is responsible for the accelerated expansion of the universe in its early stages. This vacuum energy interacts with matter and manifests itself as mass, which can be described as flow and vortex formation using the laws of hydrodynamics. The vortex model of elementary particles, in conjunction with the laws of hydrodynamics, provides an elegant explanation for the origin of mass and the relationship between mass and energy, with profound implications for the behavior of objects at high velocities and strong gravitational fields. The vacuum behaves as a compressible superfluid, thus elementary particles can be described as vortices of the vacuum. The equations of hydrodynamics for vortices can be applied to describe the nature and value of the mass of particles. The implications of understanding the nature of mass are vast and profound. From elucidating the fundamental properties of particles to informing the design of advanced materials and technologies, this knowledge is indispensable. It drives advancements across numerous fields, transforming both our theoretical understanding and practical capabilities. Continued research into the nature of mass promises to unlock further insights, fostering innovation and expanding the frontiers of science and technology.
文摘Drawing upon the electromagnetic conversion formulas in a continuous conductive medium,an extensive examination for total current law and Faraday’s law of electromagnetic induction(Faraday’s law)is undertaken to expound on the laws of electromagnetic induction and conversion.The longitudinal wave term of Faraday’s law is reinstated to render it suitable for theoretical derivation of the LEM(Longitudinal Electromagnetic Wave)equation.Subsequently,we formulate the wave and energy equations for electric P-wave based on reevaluated total current law and modified Faraday’s law;meanwhile proposing a propagation mode that reveals its mechanisms absorbing free energy for LEM waves in a conductor predicated on interaction between scalar electric field and vortex magnetic field.Furthermore,through theoretical derivations based on LEM waves,insights into concealed relationships between electric P-wave and electromagnetism scalar potential are disclosed alongside the constraint equation between the wave velocities of LEM wave and TEM(Transverse Electromagnetic)waves,unveiling the significance of LEM wave.
文摘BACKGROUND A previous study compared vortexing and Maki techniques for the diagnosis of catheter-related bloodstream infection(CRBSI),and concluded that vortexing was not superior to Maki method.AIM To determine whether the combined use of vortexing and Maki techniques provides profitability versus the Maki technique for the diagnosis of catheter tip colonization(CTC)and CRBSI.METHODS Observational and prospective study carried out in an Intensive Care Unit.Patients with suspected catheter-related infection(CRI)and with one central venous catheter for at least 7 days were included.The area under the curve(AUC)of the Maki technique,the vortexing technique and the combination of both techniques for the diagnosis of CTC and CRBSI were compared.RESULTS We included 136 episodes of suspected CRI.We found 21 cases of CTC of which 10 were also CRBSI cases.Of the 21 CTC episodes,18(85.7%)were diagnosed by Maki technique and vortexing technique,3(14.3%)only by the technique of Maki,and none only by technique of vortexing.Of the 10 CRBSI episodes,9(90.0%)were diagnosed by the techniques of Maki and vortexing,1(10.0%)was diagnosed only by the technique of Maki,and none only by the technique of vortexing.We no found differences in the comparison of AUC between the technique of Maki and the combination of Maki and vortexing techniques for the diagnosis of CTC(P=0.99)and CRBSI(P=0.99).CONCLUSION The novel finding of our study was that the combined use of vortexing and Maki techniques did not provide profitability to the technique of Maki alone to CRBSI diagnosis of.
基金supported by 2023 Kunshan Science and Technology Association youth science and technology talent lifting project(Project name:Mechanism study of mechanical damage of coagulation factor VWF based on in vitro blood-shearing experimental platform).
文摘Background:Shear stress-induced erythrocyte damage,namely hemolysis,is an important problem in the development of blood-contacting medical devices such as mechanical circulatory support devices.Computational fluid dynamics simulation combined with hemolysis prediction models have been widely used to predict hemolysis.With the development of hemolysis prediction models,the new hemolysis prediction model requires more experimental data to verify.In addition,the difference of in vitro blood-shearing device also affect the accuracy of hemolysis prediction.Methods:To address these problems,a new in vitro blood-shearing device(vortex oscillator)was used to further verify the accuracy of the hemolysis prediction models,and to guide the optimal design of blood-contacting medical devices such as mechanical circulatory support devices.Firstly,the flow field information such as wall stress and velocity of the vortex oscillator under different speeds was analyzed.Secondly,different hemolysis prediction models were used to calculate hemolysis,and the predicted data was compared with the experimental data.Results and Conclusion:In this study,the flow field information inside the vortex oscillator at high rotational speeds was systematically investigated,and the prediction of hemolysis was carried out.The results showed that the predicted data of hemolysis was significantly different from the experimental data,which indicated that it was urgent to establish a standardized in vitro blood-shearing platform to provide a reference for accurate hemolysis prediction.
