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Study on the propagation velocity of internal solitary waves in the Andaman Sea using Terra/Aqua-MODIS remote sensing images

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Journal of Oceanology and Limnology 2021年第6期39卷 2195-2208页

作者： Lina SUN Jie ZHANG Junmin MENG First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China Technology Innovation Center for Ocean Telemetry Ministry of Natural ResourcesQingdao 266061China

The Andaman Sea has been a classic study region for internal solitary waves(ISWs)for several decades,and extraordinarily large ISWs are characteristic of the Andaman Sea in the Indian *** paper presents results on the estimation of the propagation velocity of ISWs in the Andaman Sea that were tracked using 195 image pairs acquired by MODIS National Aeronautics and Space Administration(NASA)Terra/Aqua satellites between January 2014 and December 2018.A total of 562 ISWs were identified during the period,and the results of the propagation velocity distribution of ISWs in the Andaman Sea are *** estimated propagation velocity of ISWs agrees well with the theoretical results derived from the Korteweg-de Vries(KdV)equation using monthly climatology stratification data and local *** ISW propagation velocity decreases as they propagate from deep to shallow water;the maximum propagation velocity of 3.27 m/s was estimated on the western side of the Nicobar Islands and minimum speed of 0.54 m/s occurred in the shallow water region of the southeastern Andaman *** results show that the ISW propagation characteristics differ in the northern,central,and southern regions of the Andaman *** the northern Andaman Sea,the velocity of ISWs propagating westward was greater than that of ISWs propagating eastward at the same water *** the central Andaman Sea,the propagation velocity of the ISWs differed over a small area at a depth of 2500 m,and the velocity of ISWs in the deep mixing layer in winter was higher than that in the shallow mixing layer in *** variations in ISW propagation velocity were analyzed in the southern Andaman Sea,and the velocity of ISWs differed greatly in shallow water and was not significantly different in deep *** depth and monthly stratification play vital roles in controlling the phase speed of ISWs in the Andaman *** study will provide a basis for the propagation and prediction of ISWs in the Anda

关键词： internal solitary waves propagation velocity remote sensing Andaman Sea

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An electromagnetic view of relay time in propagation of neural signals

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Chinese Physics B 2021年第2期30卷 589-594页

作者： Jing-Jing Xu San-Jin Xu Fan Wang Sheng-Yong Xu School of Microelectronics Shandong UniversityJi'nan 250100China Department of Electronics School of Electronics Engineering and Computer SciencePeking UniversityBeijing 100871China

We review the experimental and computational data about the propagation of neural signals in myelinated axons in mice,cats,rabbits,and frogs published in the past five *** contrast to the natural assumption that neural signals occur one by one in time and in space,we figure out that neural signals are highly overlapped in time between neighboring *** phenomenon was occasionally illustrated in some early reports,but seemed to have been overlooked for some *** shift in time between two successive neural signals from neighboring nodes,defined as relay timeτ,was calculated to be only 16.3μs-87.0μs,i.e.,0.8%-4.4%of the average duration of an action potential peak(roughly 2 ms).We present a clearer picture of the exact physical process about how the information transmits along a myelinated axon,rather than a whole action potential peak,what is transmitted is only a rising electric field caused by transmembrane ion *** in the paper,τrepresents the waiting time until the neighboring node senses an attenuated electric field reaching the threshold to trigger the open *** mechanisms addressed in this work have the potential to be universal,and may hold clues to revealing the exact triggering processes of voltage-gated ion channels and various brain functions.

关键词： neural signal relay propagation velocity electromagnetic field model ion channels

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Investigation on the shockwave induced by surface arc plasma in quiescent air

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Chinese Physics B 2014年第3期23卷 396-403页

作者：金迪李应红贾敏李凡玉崔巍孙权张百灵李军 Science and Technology on Plasma Dynamics Laboratory Air Force Engineering University

The shockwave induced by surface direct-current （DC） arc discharge is investigated both experimentally and numer- ically. In the experiment, the shockwave generated by rapid gas heating is clearly observed from Schlieren images. The peak velocity of the shockwave is measured to be over 410 m/s; during its upright movement, it gradually falls to about 340 m/s; no remarkable difference is seen after changing the discharge voltage and the pulse frequency. In the modeling of the arc plasma, the arc domain is not simulated as a boundary condition with fixed temperature or pressure, but a source term with a time-varying input power density, which could better reflect the influence of the heating process. It is found that with a reference power density of 2.8× 1012 W/m2, the calculated peak velocity is higher than the measured one, but they quickly （in 30 Its） become agreed with each other. The peak velocity also rises while increasing the power density, the maximum velocity acquired in the simulation is over 468 m/s, which is expected to be effective for high speed flow control.

关键词： surface arc pulsed DC discharge shockwave propagation velocity

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Bridging Atomistic/Continuum Scales in Solids with Moving Dislocations

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Chinese Physics Letters 2007年第1期24卷 161-164页

作者：唐少强 LIU Wing K KARPOV Eduard G. 侯一钊 LTCS Department of Mechanics and Aerospace Engineering Peking University Beijing 100871 Department of Mechanical Engineering Northwestern University Evanston IL 60208 USA Applied and Computational Mathematics California Institute of Technology Pasadena CA 91125 USA

We propose a multiscale method for simulating solids with moving dislocations. Away from atomistic subdomains where the atomistic dynamics are fully resolved, a dislocation is represented by a localized jump profile, superposed on a defect-free field. We assign a thin relay zone around an atomistic subdomain to detect the dislocation profile and its propagation speed at a selected relay time. The detection technique utilizes a lattice time history integral treatment. After the relay, an atomistic computation is performed only for the defect-free field. The method allows one to effectively absorb the fine scale fluctuations and the dynamic dislocations at the interface between the atomistic and continuum domains. In the surrounding region, a coarse grid computation is adequate.

关键词： INCIPIENT PLASTICITY ATOMISTIC MECHANISMS BOUNDARY-CONDITIONS SIMULATIONS DYNAMICS NANOINDENTATION DEFECTS MODEL Nanoindentation relay simulating dynamics solids propagation velocity Boundary conditions

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Factors other than fibrosis that increase measured shear wave velocity

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World Journal of Gastroenterology 2022年第46期28卷 6512-6521页

作者： Hiroko Naganuma Hideaki Ishida Department of Gastroenterology Yokote Municipal HospitalYokote 013-8602Japan Department of Gastroenterology Akita Red Cross HospitalAkita 010-1495Japan

Shear wave elastography(SWE)is now becoming an indispensable diagnostic tool in the routine examination of liver *** particular,accuracy is required for shear wave propagation velocity measurement,which is directly related to diagnostic *** is generally accepted that the liver shear wave propagation velocity reflects the degree of fibrosis,but there are still few reports on other factors that increase the shear wave propagation *** this study,we reviewed such factors in the literature and examined their *** SWE measures propagation velocity based on the assumption that the medium has a homogeneous structure,uniform density,and is purely ***,the measurement is subject to *** other(confounding)factors that we routinely experience are primarily:(1)Conditions that appear to increase the viscous component;and(2)Conditions that appear to increase tissue ***,the former includes acute hepatitis,congested liver,biliary obstruction,etc,and the latter includes diffuse infiltration of malignant cells,various storage diseases,tissue necrosis,*** any case,it is important to evaluate SWE in the context of the entire clinical picture.

关键词： Liver Shear wave elastography propagation velocity Viscoelasticity Artifact Ultrasound

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Scholte wave dispersion and particle motion mode in ocean and ocean crust

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Applied Geophysics 2022年第1期19卷 132-142,146页

作者： Xu Xin Wan Yong-Ge Li Zhen-Yue Sheng Shu-Zhong Institute of Disater Prevention of Science and Technology Sanhe 065201China University of Science and Technology of China Hefei 230026China Institute of Geophysics China Earthquake AdministrationBeijing 100081China School of Geophysics and Measurement-control Technology East China University of TechnologyNanchang 330013China

The dispersion equation of the Scholte wave was reviewed using the homogeneous elastic half-space covered by a liquid layer,and the range of the Scholte wave propagation velocity was examined using the dispersion *** displacement expressions of the Scholte waves in liquid and solid were ***,the mode of motion of Scholte waves in liquid and solid and their variation with depth was *** following results were obtained:The dispersion equation shows that the propagation velocity of the fundamental Scholte wave was greater than the P-wave in liquid and less than that of the Scholte wave in homogeneous elastic *** contrast,the velocity of higher-order Scholte waves was greater than that of P waves in liquid and S-waves in *** the fundamental Scholte wave has no cutoff *** Scholte wave at the liquid surface moved only vertically,while the particles inside the liquid medium moved *** amplitude variation with depth in the solid medium caused the particle motion to change from a retrograde ellipse to a prograde *** above results imply the study of Scholte waves in the ocean and oceanic crust and help estimate ocean depths.

关键词： Scholte waves in the ocean and oceanic crust dispersion equation propagation velocity amplitude,mode of motion

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Design Mode Analysis of Array Signal Simulators Based on Cable Delays

Design Mode Analysis of Array Signal Simulators Based on Cab...

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第三届中国卫星导航学术年会

作者： Qiwei Han*, Pengpeng Li, Junwei Nie, Feixue Wang Satellite Navigation R&D Center, National Univ. of Defense Technology, Changsha, China

Array simulators based on cable delays plays an important role in array antenna testing and research. However, electromagnetic waves propagate at a relatively lower velocity in transmission lines than that in air, which results in some problems in design of array simulators. In this paper, the velocity difference is studied deeply, which has been employed in an array simulator with good angle resolution based on cable delays. A method of extending simulated angle range in beamforming by adjusting element spacing was proposed and studied, which provided a way for fully utilization of delay lines.

关键词： Array Simulation propagation velocity Angle of incidence Electromagnetic Waves

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