搜索到385076篇“ WAVES“的相关文章
Shoaling Internal Solitary Waves and the Formation of Boluses
2024年
An internal solitary wave of elevation in a two-layer density stratified system of an incompressible, viscous and homogeneous fluid was studied. The run-up of a wave of elevation encountering different slopes was investigated numerically based on solving the continuity, Navier-Stokes and convective-diffusion equations within the Boussinesq approximation. The commercial software COMSOL Multiphysics was used to conduct the numerical simulations. For gradual shoals, a bolus formed that transported dense fluid up the shoal. The bolus disappeared when it reached its maximum height on the slope due to the draining of the dense fluid. Various shoal angles were simulated to detect the critical angle above which a bolus does not form. An angle of 30 or less resulted in the formation of a bolus. In addition, the simulations demonstrated that the size of the bolus induced by shallower slopes was larger and that the vertical height traveled by the bolus was insensitive to the slope of the shoal.
Hooman EnayatiBrian T. Helenbrook
磁重联与等离子体波动被引量:1
2024年
磁场重联与等离子体波动之间存在显著的联系.其中准静态波动、激波和动力学阿尔芬波的本征模是磁重联结构的重要组成部分.而其它的高频波动,不仅能吸收粒子的自由能,还可以导致粒子的加热和反常电阻的产生.这些多尺度的波动过程揭示了磁重联中能量转换的多尺度性质.本文探讨了地球磁层磁重联过程中的各种等离子体波动,涵盖了动力学阿尔芬波、低混杂波、哨声波、静电孤波、离子声波以及电子尺度的高频静电波,并分析了它们在磁重联中的特性和作用.近期的研究成果表明,动力学阿尔芬波(kinetic Alfven wave,KAW)能够描述磁重联区域的微观结构,其中包括霍尔磁场、霍尔电场、平行电场、霍尔电流以及场向电流.在这一过程中,霍尔电场作用于离子,有助于提高重联速率.低混杂波主要在电流片的密度梯度较大处被激发,并对电子进行平行加热.而哨声波是由朗道共振和回旋共振机制驱动的.据当前研究所示,低混杂波和哨声波对于重联过程中的反常电阻效应的影响是次要的.静电孤波多在磁重联分界线区域出现,其对等离子体的加热效应仍需进一步研究.与此同时,关于高频静电波(例如高混杂波和电子伯恩斯坦波)的研究重点在于磁重联的扩散区,这些波被认为对该区域中的电子能量转换过程起到了关键作用.这些最新研究成果为深化我们对磁重联以及等离子体波动的理解提供了宝贵的参考.
任勇戴磊王赤周猛王荣生
关键词:磁场重联低混杂波哨声波
Detection of Gravitational Waves with Semi Classical Features and Resulting Cosmological Implications
2024年
The author argues in this document that initial vacuum state values possibly responsible for GW generation in relic conditions in the initial onset of inflation may have a temporary unsqueezed, possibly even coherent initial value, which would permit in certain models classical coherent initial gravitational wave states. Furthermore, several arguments pro and con as to if or not initial relic GW should be high frequency will be presented, with the reason given why earlier string models did NOT favor low frequency relic GW from the big bang. What is observed is that large higher dimensions above our 4 Dimensional space time, if recipients of matter-energy from collapse and re birth of the universe are enough to insure low relic GW. The existence of higher dimensions, in itself if the additional dimensions are small and compact will have no capacity to lower the frequency limit values of relic GW, as predicted by Giovannini, et al. in 1995.
Andrew Walcott Beckwith
关键词:DM
Isolated Hyperacute T-Waves in West Nile Encephalitis Indicating Atypical Variant of Stress-Induced Cardiomyopathy
2024年
Several cardiac outcomes have been reported with West Nile-encephalitis;however, the underlying pathophysiology remains complex. We present a 42-year-old female, with multiple sclerosis, whose neurological symptoms and respiratory decline were finally explained by the diagnosis of West Nile-encephalitis. During her admission, the isolated peaked T-waves indicated the underlying stress-induced cardiomyopathy. The absence of all other causes of hyperacute T-waves, their subsequent resolution with the resolution of infection and improvement in wall motion abnormalities, further supported the association. This case highlights the importance of considering hyperacute T-waves in an approach towards the diagnosis of WNV-encephalitis related atypical variant of stress-induced cardiomyopathy.
Soomal RafiqueNadeem KhanMomin Siddique
关键词:WNV
Existence and Stability of Standing Waves for the Nonlinear Schrödinger Equation with Combined Nonlinearities and a Partial Harmonic Potential
2024年
In this paper, we study the existence of standing waves for the nonlinear Schrödinger equation with combined power-type nonlinearities and a partial harmonic potential. In the L2-supercritical case, we obtain the existence and stability of standing waves. Our results are complements to the results of Carles and Il’yasov’s artical, where orbital stability of standing waves have been studied for the 2D Schrödinger equation with combined nonlinearities and harmonic potential.
Wei Wang
Observation of optical rogue waves in 2D optical lattice
2024年
We use a broad Gaussian beam with perturbations to motivate rogue waves(RWs)in a two-dimensional optical-induced lattice.In a linear situation,we fail to observe RWs.Nevertheless,under a nonlinear condition,the probability of RWs in the lattice is less than that in a homogeneous medium.Additionally,we obtain a shorter long-tail distribution of probability density function in an optical lattice.
Meng LiJie SongFuqiang LiCibo Lou
基于涡旋电磁波的无线通信技术(特邀)
2024年
介绍了无线通信和涡旋电磁波的基本概念及相关技术,详细回顾了近年来基于涡旋电磁波的无线通信技术实验研究进展,包括微波涡旋电磁波通信、太赫兹涡旋电磁波通信、中红外涡旋电磁波通信、近红外涡旋电磁波通信和可见光涡旋电磁波通信等。同时,介绍了卫星涡旋激光通信技术的理论研究进展以及拓展结构光(如贝塞尔光和矢量光等)通信在抵抗障碍物和湍流影响方面的实验研究进展。最后也讨论了涡旋电磁波无线通信技术的挑战与展望。多频段和多维度融合的涡旋电磁波及拓展结构化电磁波,可以为多场景、跨尺度、大容量、远距离、高鲁棒性的无线通信提供潜在解决方案,也有望应用于未来卫星通信中。
王健王仲阳刘劲峰汪朔
关键词:无线通信自由空间光通信轨道角动量卫星通信
RS堆积体滑坡涌浪特征数值模拟研究
2024年
库区滑坡涌浪是滑坡产生的次生灾害,严重威胁库区工程安全及大坝稳定运行.澜沧江RM水电站RS堆积体方量巨大,且位于近坝区,开展RMRS堆积体滑坡涌浪特征研究对大坝工程安全设计和施工至关重要.本文建立RS堆积体滑坡涌浪远近场计算模型,基于光滑粒子流体动力学方法及浅水方程,研究RM工程正常蓄水位2895m情况下RS堆积体滑动产生的涌浪特征,并与经验公式法进行对比.研究表明:分析所采用的数值模拟方法在研究滑坡涌浪中具有优势,该方法可准确模拟滑坡体入水产生的非线性流固耦合过程,准确捕捉涌浪传播过程中受到复杂地形影响以及爬升过程中的地形相关性.研究结果可为评估RMRS堆积体滑坡涌浪对工程安全的影响提供参考.
湛正刚程瑞林张合作马行生胡大儒王照英王环玲
关键词:滑坡涌浪光滑粒子流体动力学涌浪传播
基于超声导波的积冰量辨识及定位方法
2024年
为实现飞机结冰区域化定量探测能力,提出了一种基于Lamb波的冰层定位和定量辨识方法。首先,建立了压电耦合的波动力学仿真模型,通过三维有限元数值计算分析了Lamb波在铝板、冰层中的传播特性及模态转换过程,选取S0/B1模态作为结冰监测模态,并建立了一种基于小波变换的信号分析方法以提取S0/B1模态波的时间延迟特征量。进一步,研究分析了不同冰层结构尺寸对Lamb波信号的影响规律。结果表明,随着冰层长度(波导传播方向上的积冰量)的增大,B1模态波的时延比线性增大;冰层宽度(波导传播展向垂直方向上的积冰量)对B1模态波时延存在一个影响区域,在影响区域内(冰层宽度不大于40 mm),时延比与冰层宽度成线性关系;冰层厚度与B1模态波时延比总体上具有正相关变化趋势,冰层厚度在1.5 mm以内时,其与时延比之间具有较好的线性关系。基于此,建立了Lamb波压电阵列定位成像的数值计算模型,并提出了一种自适应阈值概率重构算法,进一步采用时延比来表征探测区域内的积冰程度,最终验证了冰层的定位成像、结冰定量辨识的可行性,提升了超声导波结冰在线快速评估的能力,为超声导波结冰区域化定量探测奠定了基础。
张晏鑫张鸿健熊建军赵照冉林易贤
关键词:超声导波LAMB波
Simulating the evolution of focused waves by a two-layer Boussinesq-type model
2024年
Accurate simulation of the evolution of freak waves by the wave phase focusing method requires accurate linear and nonlinear properties,especially in deep-water conditions.In this paper,we analyze the ability to simulate deep-water focused waves of a two-layer Boussinesq-type(BT)model,which has been shown to have excellent linear and nonlinear performance.To further improve the numerical accuracy and stability,the internal wavegenerated method is introduced into the two-layer Boussinesq-type model.Firstly,the sensitivity of the numerical results to the grid resolution is analyzed to verify the convergence of the model;secondly,the focused wave propagating in two opposite directions is simulated to prove the symmetry of the numerical results and the feasibility of the internal wave-generated method;thirdly,the limiting focused wave condition is simulated to compare and analyze the wave surface and the horizontal velocity of the profile at the focusing position,which is in good agreement with the measured values.Meanwhile the simulation of focused waves in very deep waters agrees well with the measured values,which further demonstrates the capability of the two-layer BT model in simulating focused waves in deep waters.
Ping WangZhongbo LiuKezhao FangWenfeng ZouXiangke DongJiawen Sun

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张婧
作品数:31被引量:48H指数:4
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