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frequency selectivity Analysis Based on Inductively Coupled Channel for Current Transmission Through Seawater

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China Ocean Engineering 2021年第4期35卷 622-630页

作者： ZHENG Yu FEI Chen LU Yan-fang LI Hong-zhi School of Life Sciences Tiangong UniversityTianjin 300387China School of Electrical and Electronic Engineering Tiangong UniversityTianjin 300387China National Ocean Technology Center Tianjin 300112China

Inductively coupled channels are based on the electromagnetic induction principle and realize long-distance current signal transmission through *** to a few difficulties in performing actual experiments,it is unclear how the seawater medium affects the frequency selectivity of the current *** this paper,a dual dipole model of the inductively coupled seawater transmission channel is established for the traditional short-distance current field transmission *** transmission characteristics of electrical signals in seawater are theoretically derived.A platform is used to measure the amplitude-frequency and phase-frequency characteristics of the current signal transmission in seawater with transmission frequencies ranging from 30 kHz to 1 MHz,and transmission distances in the vertical range of 4 *** COMSOL Multiphysics simulation and practical test analysis are carried out to analyze the frequency selectivity of seawater *** is proved that the seawater resistance increases as the frequency increases,which is the key problem that affects the current *** study provides an important theoretical support and experimental evidence for improving the transmission performance of long-distance underwater current signals.

关键词： inductively coupled channel seawater medium current signal frequency selectivity electrical conductivity

Controlling Ion Conductance and Channels to Achieve Synapticlike frequency selectivity

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Nano-Micro Letters 2015年第2期7卷 121-126页

作者： Siheng Lu Fei Zeng Wenshuai Dong Ao Liu Xiaojun Li Jingting Luo Laboratory of Advanced Materials (MOE) School of Materials Science and Engineering Tsinghua University Institute of Thin Film Physics and Applications Shenzhen Key Laboratory of Sensor Technology Shenzhen University

Enhancing ion conductance and controlling transport pathway in organic electrolyte could be used to modulate ionic kinetics to handle signals. In a Pt/Poly(3-hexylthiophene-2,5-diyl)/Polyethylene?Li CF3SO3/Pt hetero-junction, the electrolyte layer handled at high temperature showed nano-fiber microstructures accompanied with greatly improved salt solubility. Ions with high mobility were confined in the nano-fibrous channels leading to the semiconducting polymer layer,which is favorable for modulating dynamic doping at the semiconducting polymer/electrolyte interface by pulse *** a device realized synaptic-like frequency selectivity, i.e., depression at low frequency stimulation but potentiation at high-frequency stimulation.

关键词： Ions migration Nano-channels frequency selectivity Semiconducting polymer Organic electrolyte Dynamic doping

Response analyses on the drill-string channel for logging while drilling telemetry

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Petroleum Science 2023年第5期20卷 2796-2808页

作者： Ao-Song Zhao Xiao He Hao Chen Xiu-Ming Wang State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China Beijing Engineering Research Center of Sea Deep Drilling and Exploration Institute of AcousticsChinese Academy of SciencesBeijing100190China

Downhole acoustic telemetry(DAT),using a long drill string with periodical structures as the channel,is a prospective technology for improving the transmission rate of logging while drilling(LWD)*** studies only focused on the acoustic property of a free drill string and neglected the coupling between pipes and fluid-filled *** addition to the drill-string waves,a series of fluid waves are recorded in the DAT channel,which has not been investigated *** channel characteristics result in lower transmission rates and stability than ***,a more realistic channel model is needed considering the fluid-filled *** this paper,we propose a hybrid modeling method to investigate the response characteristics of the DAT *** combining the axial wavenumbers and excitation functions of mode waves in radially layered LWD structures,the channel model is approximated to the 1-D propagation,which considers transmission,reflection,and interconversion of the drillstring and fluid *** proposed 1-D approximation has been well validated by comparing the 2-D finite-difference *** is revealed that the transmitted and converted fluid waves interfere with the drill-string wave,which characterizes the DAT channel as a particular coherent multi-path *** a fluid-filled borehole surrounds the drill string,the channel responses exhibit considerable delay as well as strong frequency selectivity in amplitude and *** new findings suggest that the complexity of the channel response has been underestimated in the past,and therefore channel measurements on the ground are *** address these channel characteristics,we apply a noncoherent demodulation *** transmission rate for synthetic data reaches 15 bps in a 94.5 m long channel,indicating that the acoustic telemetry is promising to break the low-speed limitation of mud-pulse telemetry.

关键词： Logging while drilling Borehole geophysics Downhole acoustic telemetry Channel modeling frequency selectivity

Explosive synchronization enhances selectivity： Example of the cochlea

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Frontiers of physics 2017年第5期12卷 241-249页

作者： Chao-Qing Wang Alain Pumir Nicolas B. Garnier Zong-Hua Liu Department of Physics East China Normal University Shanghai 200241 China Laboratoire de Physique de I'ENS de Lyon CNRS UMR 5672 46 Allde d'Italie F-69364 Lyon France

Acoustical signal transduction in the cochlea is an active process that involves nonlinear amplification and spontaneous otoacoustic emissions. Signal transduction involves individual subunits composed of globally coupled hair cells, which can be modeled as oscillators close to a Hopf bifurcation. The coupling may induce a transition toward synchronization, which in turn leads to a strong nonlinear response. In the model studied here, the synchronization transition of the subunit is discontinuous （explosive） in the absence of an external stimulus. We show that, in the presence of an external stimulus and for a coupling strength slightly lower than the critical value leading to explosive synchronization, the response of the subunit has better frequency selectivity and a larger signal-to-noise ratio. From physiological observations that subunits are themselves coupled together, we further propose a model of the complete cochlea, accounting for the ensemble of frequencies that the organ is able to detect.

关键词： cochlea frequency selectivity periodical forcing explosive synchronization

A Possible Neural Mechanism Explaining How the Big Brown Bat Recognizes its Own Echoes

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A Possible Neural Mechanism Explaining How the Big Brown Bat...