Detection accuracy of target accelerations based on vortex electromagnetic wave in keyhole space

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.

Optimization of extreme ultraviolet vortex beam based on high harmonic generation

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.

Unraveling the Quantum Web: The Vortex Theory of Mass and Matter Formation

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.

Improving millimeter-wave imaging quality using the vortex phase method

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.

净水污泥固定化硫氧化菌去除河道中AVS污染的试验研究

目的 研究净水污泥固定化硫氧化菌去除河道中的酸可挥发性硫化物污染方法,为净水污泥资源化利用提供一种新的思路。方法 通过高温焙烧的方法制备净水污泥固定化载体,采用XRD、SEM、BET对载体进行表征,使用净水污泥、绿沸石、活性炭3种载体对硫氧化菌进行固定化,分析其对底泥中AVS的去除效果以及固定化效果的影响,并通过高通量测序技术分析其对微生物种群变化的影响。结果 净水污泥固定化载体的最佳焙烧温度为600℃,无论是单一载体,还是固定化硫氧化菌,净水污泥组对于AVS的去除效果均要优于绿沸石和活性炭;同时硫氧化菌在温度为30℃、pH=6、固定化时间为24 h条件下的固定化效果最好;净水污泥固定化硫氧化菌的加入有利于降解硫化物优势菌种的群居,抑制了硫酸盐还原菌的生长繁殖。结论 净水污泥固定化硫氧化菌能有效去除河道中的AVS污染,降低底泥生物种群的多样性,有利于去除AVS优势菌种的群聚,抑制硫酸盐还原菌的繁殖,促进水体黑臭环境的改善。

Vortex模型对气道管理质控的提示作用

困难气道的处理是气道管理工作中的重要挑战之一,目前许多气道管理协会制定的困难气道管理指南在临床实践中的依从性和可操作性较差,原因包括指南内容复杂以及缺乏具体决策指导。为了提高指南的依从性和执行率,Vortex模型应运而生。Vortex模型由Nicholas Chrimes于2013年提出,是一种补充现有困难气道管理指南的认知辅助工具,目的在于提供一个简洁的管理思维模型,通过视觉化的漩涡结构帮助气道管理团队成员形成共同的情境认知,从而提高困难气道管理时的沟通和决策能力。本文旨在对Vortex模型的概念、特点及应用方法进行全面的综述,以期对目前临床上气道管理的质控工作提供可借鉴的经验。

Mesoscale Barotropic Instability of Vortex Rossby Waves in Tropical Cyclones

In this study, the barotropic stability of vortex Rossby waves （VRWs） in 2D inviscid tropical cyclone （TC）-like vortices is explored in the context of rotational dynamics on an f-plane. Two necessary instable conditions are discovered： （a） there must be at least one zero point of basic vorticity gradient in the radial scope; and （b） the relative propagation velocity of perturbations must be negative to the basic vorticity gradient, which reflects the restriction relationship of instable energy. The maximum growth rate of instable waves depends on the peak radial gradient of the mean vorticity and the tangential wavenumber （WN）. The vortex-semicircle theorem is also derived to provide bounds on the growth rates and phase speeds of VRWs. The typical basic states and different WN perturbations in a tropical cyclone （TC） are obtained from a high resolution simulation. It is shown that the first necessary condition for vortex barotropic instability can be easily met at the radius of maximum vorticity （RMV）. The wave energy tends to decay （grow） inside （outside） the RMV due mainly to the negative （positive） sign of the radial gradient of the mean absolute vorticity. This finding appears to help explain the developemnt of strong vortices in the eyewall of TCs.

The Energy Budget of a Southwest Vortex With Heavy Rainfall over South China

Energy budgets were analyzed to study the development of an eastward propagating southwest vortex (SWV) associated with heavy rainfall over southern China(11-13 June 2008).The results show that kinetic energy(KE) generation and advection were the most important KE sources,while friction and sub-grid processes were the main KE sinks.There was downward conversion from divergent to rotational wind KE consistent with the downward stretching of SWVs.The Coriolis force was important for the formation and maintenance of the SWV.Convergence was also an important factor for maintenance,as was vertical motion during the mature stage of the SWV and the formation stage of a newly formed vortex(vortex B).The conversion from available potential energy(APE) to KE of divergent wind can lead to strong convection.Vertical motion influenced APE by dynamical and thermal processes which had opposite effects. The variation of APE was related to the heavy rainfall and convection;in this case,vertical motion with direct thermal circulation was the most important way in which APE was released,while latent heat release and vertical temperature advection were important for APE generation.

Study on a Mesoscale Convective Vortex Causing Heavy Rainfall during the Mei-yu Season in 2003

The strong heavy rainfall on 3–5 July 2003 causing the severe flooding in Huaihe River basin （HRB）, China is studied. It is noted that there are sometimes mesoscale convective vortex （MCV） in East Asia during the mei-yu season. Simulation results from the ARPS （Advanced Regional Prediction） data analysis system （ADAS） and WRF model were used to study the development of the mesoscale convective system （MCS） and mesoscale convective vortex （MCV）. It is confirmed that the MCV formed during the development of a previous severe MCS. A closed vortex circulation can be found below 600 hPa with a vorticity maximum in the middle troposphere. The evolution process of the MCV can be divided into three stages： initiation, maturation, and dissipation. During the mature stage of the MCV, a downdraft occurred in the center of the MCV and new convection developed in southeast of the MCV. The convergence and the tilting in the lower troposphere convergence and vertical advection in the middle troposphere were the main vorticity sources in the MCV initiation stage. Finally, a conceptual model between the mei-yu front and the embedded MCS and MCV is proposed. The mei-yu front was the background condition for the development of the MCS and MCV. A low level jet （LLJ） transported moisture and the weak cold air invasion via a trough aloft in the middle troposphere and triggering the severe convection. Furthermore, the intensified jet was able to result in the initiation of new ＂secondary＂ areas of convection in the eastern part of the MCV.

Dynamic and Numerical Study of Waves in the Tibetan Plateau Vortex

In terms of its dynamics, The Tibetan Plateau Vortex （TPV） is assumed to be a vortex in the botmdary layer forced by diabatic heating and friction. In order to analyze the basic characteristics of waves in the vortex, the governing equations for the vortex were established in column coordinates with the balance of gradient wind. Based on this, the type of mixed waves and their dispersion characteristics were deduced by solving the linear model. Two numerical simulations with triple-nested domains--one idealized large-eddy simulation and one of a TPV that took place on 14 August 2006---were also carried out. The aim of the simulations was to validate the mixed wave deduced from the governing equations. The high-resolution model output data were analyzed and the results showed that the tangential flow field of the TPV in the form of center heating was cyclonic and convergent in the lower levels and anticyclonic and divergent in the upper levels. The simulations also showed that the vorticity of the vortex is uneven and might have shear flow along the radial direction. The changing vorticity causes the formation and spreading of vortex Rossby （VR） waves, and divergence will cause changes to the n^otion of the excitation and evolution of inertial gravity （IG） waves. Therefore, the vortex may contain what we call mixed ：inertial gravity-vortex Rossby （IG-VR） waves. It is suggested that some strongly developed TPVs should be studied in the future, because of their effects on weather in downstream areas.

The Role of Stationary and Transient Planetary Waves in the Maintenance of Stratospheric Polar Vortex Regimes in Northern Hemisphere Winter

Using 1958-2002 NCEPNCAR reanalysis data, we investigate stationary and transient planetary wave propagation and its role in wave-mean flow interaction which influences the state of the polar vortex （PV） in the stratosphere in Northern Hemisphere （NH） winter. This is done by analyzing the Eliassen-Palm （E-P） flux and its divergence. We find that the stationary and transient waves propagate upward and equatorward in NH winter, with stronger upward propagation of stationary waves from the troposphere to the stratosphere, and stronger equatorward propagation of transient waves from mid-latitudes to the subtropics in the troposphere. Stationary waves exhibit more upward propagation in the polar stratosphere during the weak polar vortex regime （WVR） than during the strong polar vortex regime （SVR）. On the other hand, transient waves have more upward propagation during SVR than during WVR in the subpolar stratosphere, with a domain of low frequency waves. With different paths of upward propagation, both stationary and transient waves contribute to the maintenance of the observed stratospheric PV regimes in NH winter.

A Study of Structure and Mechanism of a Meso-beta-scale Convective Vortex and Associated Heavy Rainfall in the Dabie Mountain Area Part I: Diagnostic Analysis of the Structure

An analysis was conducted on the evolutional process of a mesoscale convective vortex （MCV） and associated heavy rainfall in the Dabie Mountain area on 21-22 June 2008,as well as their structural characteristics in different stages,by using the mesoscale reanalysis data with 3 km and 1 h resolution generated by the Local Analysis and Prediction System （LAPS） in the Southern China Heavy Rainfall Experiment.The results showed that the latent heat released by convection in the midtroposphere was the main energy source for the development of a low-level vortex.There was a positive feedback interaction between the convection and the vortex,and the evolution of the MCV was closely related to the strength of the positive interaction.The most typical characteristics of the thermal structure in different stages were that,there was a relatively thin diabatic heating layer in the midtroposphere in the formative stage;the thickness of diabatic heating layer significantly increased in the mature stage;and it almost disappeared in the decay stage.The characteristics of the dynamic structure were that,in the formative stage,there was no anticyclonic circulation at the high level;in the mature stage,an anticyclonic circulation with strong divergence was formed at the high level;in the decay stage,the anticyclonic circulation was damaged and the high-level atmosphere was in a disordered state of turbulence.Finally,the structural schematics of the MCV in the formative and mature stage were established respectively.

Numerical Prediction of Tip Vortex Cavitation for Marine Propellers in Non-uniform Wake

Tip vortex cavitation is the first type of cavita- tion to take place around most marine propellers. But the numerical prediction of tip vortex cavitation is one of the challenges for propeller wake because of turbulence dis- sipation during the numerical simulation. Several parame- ters of computational mesh and numerical algorithm are tested by mean of the predicted length of tip vortex cav- tiation to validate a developed method. The predicted length of tip vortex cavtiation is on the increase about 0.4 propeller diameters using the developed numerical method. The predicted length of tip vortex cavtiation by RNG k - e model is about 3 times of that by SST k - ~o model. Therefore, based on the validation of the present approach, the cavitating flows generated by two rotating propellers under a non-uniform inflow are calculated further. The distributions of axial velocity, total pressure and vapor volume fraction in the transversal planes across tip vortex region are shown to be useful in analyzing the feature of the cavitating flow. The strongest kemel of tip vortex cavitation is not at the position most close to blade tip but slightly far away from the region. During the growth of tip vortex cavitation extension, it appears short and thick, and then it becomes long and thin. The pressure fluctuations at the positions inside tip vortex region also validates the conclusion. A key finding of the study is that the grids constructed especially for tip vortex flows by usingseparated computational domain is capable of decreasing the turbulence dissipation and correctly capturing the fea- ture of propeller tip vortex cavitation under uniform and non-uniform inflows. The turbulence model and advanced grids is important to predict tip vortex cavitation.

Mechanism of wavy vortex and sign laws in flow past a bluff body:vortex-induced vortex

As reported in a previous work by Lin et al.(Acta Meeh Sin, 2018. https://doi.org/10.1007/s 10409-018-0758-z), an interesting phenomenon was discovered based on the analysis of wavy vortex and vorticity distribution in the shear layers and near wake of a peak-perforated conic shroud, and two sign laws were summarized. In the present paper, the theory of a vortex-induced vortex is introduced to explore mechanisms in a wavy vortex and applicable sign laws for uniform and incompressible flow past a fixed bluff body. Based on the analysis of the nearest-wall How, two vortex-induced models for streamwise and vertical vortex pairs, respectively, are proposed under two boundary cases, denoting the induced vorticity introduced or distributed on and near the walls. As a result, the first sign law, for only streamwise and vertical components of vorticity, and the second sign law, for three components of vorticity, are obtained under their own particular conditions. The first sign law reveals the intrinsic physical relationship between streamwise and vertical vorticities, independent of the distribution of spanwise vortices in the whole flow field. It is also confirmed that the spanwise vortices, as well as the shear layers and wake width, distributed wavily across the span, are attributed to the introduced streamwise or vertical vortices. The two sign laws for vorticity are independent of the disturbed spanwise wavelength and the Reynolds number. Through the analysis of flow past the conic shroud, the two sign laws are successfully used to summarize typical spacial distributions of vorticity in three flow regions: on and near the front cylinder surfaces, the separated shear layers and the near wake.

Flow Separation and Vortex Dynamics in Waves Propagating over A Submerged Quartercircular Breakwater

The interactions of cnoidal waves with a submerged quartercircular breakwater are investigated by a ReynoldsAveraged Navier–Stokes(RANS) flow solver with a Volume of Fluid(VOF) surface capturing scheme(RANSVOF) model. The vertical variation of the instantaneous velocity indicates that flow separation occurs at the boundary layer near the breakwater. The temporal evolution of the velocity and vorticity fields demonstrates vortex generation and shedding around the submerged quartercircular breakwater due to the flow separation. An empirical relationship between the vortex intensity and a few hydrodynamic parameters is proposed based on parametric analysis. In addition, the instantaneous and time-averaged vorticity fields reveal a pair of vortices of opposite signs at the breakwater which are expected to have significant effect on sediment entrainment, suspension, and transportation,therefore, scour on the leeside of the breakwater.

The Possible Mechanism of a Type of Vortex Heavy Rainfall during the Pre-Rainy Season in South China

In this paper,NCEP reanalysis data,intensive observation data collected from field experiment,model simulation data,and topographic trial data are fully analyzed to study a severe heavy rainfall event during 5 6 June 2008 in South China.Unlike most warm region rainfall cases,this one is associated with an obvious vortex system,which draws in water vapor and energy from the southwest monsoon surges ahead of a low trough above the Bengal Bay (BLT,Bengal Low Trough).At the lower troposphere,three currents,especially the southwest current and the east current,converge into the southeast of the vortex.Thus,the distributions of strong vorticity,water vapor,and ascending motion cause frequently occurrence and growth of convection there.The possible reasons for this rainfall event are summarized as a conceptual model.

Numerical simulation of vortex evolution based on adaptive wavelet method

The application of the wavelet method to vortex motion prediction is investigated. First, the wavelet method is used to solve two initial boundary problems so as to verify its abilities of controlling numerical errors and capturing local structures. Then, the adaptive wavelet method is used to simulate the vortex emerging process. The results show that the wavelet method can control numerical errors easily, can capture local structures adaptively, and can predict the vortex fluctuation evolution. Therefore, the application of the wavelet method to turbulence is suggested.

Investigation on the Flow Behavior of Side Channel Pumps Based on Vortex Identification

The momentum flow exchange between the impeller and side channel produces highly turbulent flows in side channel pumps.The turbulent flows feature complex patterns of vortex structures that are partly responsible for the dissipation of energy losses and unsteady pressure pulsations.The concept of turbulent flows in side channel pumps requires a reliable vortex identification criterion to capture and predict the effects of the vortex structures on the performance.For this reason,the current study presents the application of the new Ω-criterion to a side channel pump model in comparison with other traditional methods such as Qand λ2 criteria.The 3D flow fields of the pump were obtained through unsteady Reynolds-averaged Navier-Stokes(RANS)simulations.Comparative studies showed that the Ω-criterion identifies the vortex of different intensities with a standard threshold,Ω=0.52.The Q and λ2 criteria required different thresholds to capture vortex of different intensities thus leads to subjective errors.Comparing theΩ-criterion intensity on different planes with the entropy losses and pressure pulsation,the longitudinal vortex plays an important role in the momentum exchange development which increases the head performance of the pump.However,the rate of exchange is impeded by the axial and radial vortices restricted in the impeller.Therefore,the impeller generates the highest entropy loss and pressure pulsation intensities which lower the output efficiency.Finally,the findings provide a fundamental background to the morphology of the vortex structures in the turbulent flows which can be dependent upon for efficiency improvement of side channel pumps.

Diagnostic Analysis on Heavy Rain Process of the Northeast-moving Southwest Vortex

The moving path of southwest vortex and the mechanism of heavy rain in the north were studied in order to find out the forecasting point of the northern heavy rain,so as to improve the forecasting ability of the heavy rain disastrous weather.A large-scale heavy rain process in northern China from 18 to 21 July 2010 was diagnostically analyzed using meteorological conventional and intensified observation data and NCEP 1°× 1° reanalysis data.The result showed that the southwest vortex moved northeastward under the guidance of southwest airflow in the periphery of subtropical high,which was the direct influence system of the heavy rainfall.The heavy rainfall occurred on the east side of the symmetrical axis of the 700 hPa low vortex.The southwest jet provided abundant water vapor and potential instability energy for the occurrence of heavy rainfall.The changes of vorticity advection and temperature advection in the lower and middle troposphere were the leading causes of affecting the development and movement of the low vortex.The low vortex moved along the positive vorticity advection increasing region and the warm advection increasing region.The dry and cold air intruded into the low vortex from the middle layer,which promoted the generation and development of the unstable stratification of upper cold and lower warm,and provided unstable and triggering conditions for heavy rain.The water vapor transport from the Yellow Sea and the Bohai Sea was very abundant,and the water vapor flux was very high,reaching 30 g/(s·cm·hPa).It was the main reason for the maximum precipitation in Liaoning Province,which was the farthest from the southwest vortex source.The study deepened the understanding of the structural characteristics of the southwest vortex and revealed the dynamic mechanism of the northeast movement and development of the southwest vortex as well as the cause of rainstorm induced by interaction with other weather systems.It can provide some forecasting ideas and useful references for forecasting the movement of the southwest vortex and the heavy rain weather in the north.

Computational and Empirical Investigation of Propeller Tip Vortex Cavitation Noise

In this study,non-cavitating and cavitating flow around the benchmark DTMB 4119 model propeller are solved using both viscous and potential based solvers.Cavitating and non-cavitating propeller radiated noises are then predicted by using a hybrid method in which RANS(Reynolds-averaged Navier-Stokes)and FWH(Ffowcs Williams Hawkings)equations are solved together in open water conditions.Sheet cavitation on the propeller blades is modelled by using a VOF(Volume of Fiuld)method equipped with Schnerr-Sauer cavitation model.Nevertheless,tip vortex cavitation noise is estimated by using two different semi-empirical techniques,namely Tip Vortex Index(TVI,based on potential flow theory)and Tip Vortex Contribution(TVC).As the reference distance between noise source and receiver is not defined in open water case for TVI technique,one of the outputs of this study is to propose a reference distance for TVI technique by coupling two semi-empirical techniques and ITTC distance normalization.At the defined distance,the starting point of the tip vortex cavitation is determined for different advance ratios and cavitation numbers using potential flow solver.Also,it is examined that whether the hybrid method and potential flow solver give the same noise results at the inception point of tip vortex cavitation.Results show that TVI method based on potential flow theory is reliable and can practically be used to replace the hybrid method(RANS with FWH approach)when tip vortex cavitation starts.