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signal perception during plant-bacteria interactions: from chemicals to physical signals

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Science China(Life Sciences) 2020年第2期63卷 305-307页

作者： Bao-Zhen Ren Wei Qian State Key Laboratory of Plant Genomics Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China College of Biological Sciences University of Chinese Academy of SciencesBeijing 100049China Center for Excellence of Biotic Interactions Chinese Academy of SciencesBeijing 100101China College of Advanced Agricultural Sciences University of Chinese Academy of SciencesBeijing 100049China

During interactions between host plants and microbes, discrimination between "self" and "nonself" is at the center of many biological relationships and determines the success of infection by microbial pathogens or imm... 详细信息

关键词： signal immunity signals

Micromagnetics and signal Analysis of Shielded Spin-Valve Multilayer

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Chinese Physics Letters 1996年第6期13卷 469-472页

作者： ZHANG Huai-wu YANG Shi-qing LIU Ying-li WANG Hao-cai H.J.Kim Institute of Materials and Information Engineering University of Electronic Science and TechnologyChengdu 610054 Magnetic Alloy Laboratory Metals DivisionKorea Institute of Science and TechnologyP.O.Box 131ChenogryangSeoulKorea

In order to linearize a spin-valve giant magnetoresistance head,the exchanges layer sputtered at fringe area or a permanent magnet layer longitudinal biasing for domain stabilization based on a physical calculated model may be *** correlations between the head performance characteristic and head geometric parameters have been simulated by putting the head on a suitable front-end electric *** simulative results show that the optimal sensing current is from 10 to 40mA and the linear geometric parameteres for gap width are at the range of G_(1)+G_(2)≤0.5μm.

关键词： stabilization permanent signal

Moving horizon based wavelet de-noising method of dual-observed geomagnetic signal for nonlinear high spin projectile roll positioning

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Defence Technology（防务技术） 2020年第2期16卷 417-424页

作者： Ting-ting Yin Fang-xiu Jia Xiao-ming Wang ZNDY of Ministerial Key Laboratory Nanjing University of Science and TechnologyNanjing210094China

Phase-frequency characte ristics of approximate sinusoidal geomagnetic signals can be used fo r projectile roll positioning and other high-precision trajectory correction *** sinusoidal geomagnetic signal deforms in the exposed and magnetically contaminated *** order to preciously recognize the roll information and effectively separate the noise component from the original geomagnetic sequence,based on the error source analysis,we propose a moving horizon based wavelet de-noising method for the dual-observed geomagnetic signal filtering where the captured rough roll frequency value provides reasonable wavelet decomposition and reconstruction level selection basis for sampled sequence;a moving horizon window guarantees real-time performance and non-cumulative calculation *** complete geomagnetic data in full ballistic range and three intercepted paragraphs are used for performance *** positioning performance of the moving horizon wavelet de-noising method is compared with the band-pass *** results show that both noise reduction techniques improve the positioning accuracy while the wavelet de-noising method is always better than the band-pass *** results suggest that the proposed moving horizon based wavelet de-noising method of the dual-observed geomagnetic signal is more applicable for various launch conditions with better positioning performance.

关键词： High-spin projectile roll positioning Dual-observed geomagnetic signal Wavelet de-noising Discrete wavelet transform

Towards a simple and safe Objective Caml compiling framework for the synchronous language signal

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Frontiers of Computer Science 2019年第4期13卷 715-734页

作者： Zhibin YANG Jean-Paul BODEVEIX Mamoun FILALI School of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 211106 China State Key Laboratory of Software Development Environment Beijing 100191 China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing 211106 China IRIT-CNRS Universite de Toulouse Toulouse 31062 France

This paper presents a simple and safe compiler, called Minsignal, from a subset of the synchronous dataflow language signal to C, as well as its existing en? hancements. The compiler follows a modular architecture, and can be seen as a sequence of source-to-source transformations applied to an intermediate representation which is named Synchronous Clocked Guarded Actions (S-CGA) and translation to sequential imperative code. Objective Caml (OCaml) is used for the implementation of Minsignal. As a modem functional language, OCaml is adapted to symbolic computation and so, particularly suitable for compiler design and implementation of formal analysis tools. In particular, the safety of its type checking allows to skip some verification that would be mandatory with other languages. Additionally, this work is a basis for the formal verification of the compilation of signal with a theorem prover such as Coq.

关键词： synchronous languages signal Synchronous Clocked Guarded Actions (S-CGA) Objective Caml functional programming

Noise cancellation of a multi-reference full-wave magnetic resonance sounding signal based on a modified sigmoid variable step size least mean square algorithm

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Journal of Central South University 2017年第4期24卷 900-911页

作者： TIAN Bao-feng ZHOU Yuan-yuan ZHU Hui JIANG Chuan-dong YI Xiao-feng Key Laboratory of Geo-Exploration Instrumentation Ministry of Education (Jilin University)Changchun 130026 China College of Instrumentation and Electrical Engineering Jilin University Changchun 130026 China

Nano-volt magnetic resonance sounding(MRS) signals are sufficiently weak so that during the actual measurement, they are affected by environmental electromagnetic noise, leading to inaccuracy of the extracted characteristic parameters and hindering effective inverse interpretation. Considering the complexity and non-homogeneous spatial distribution of environmental noise and based on the theory of adaptive noise cancellation, a model system for noise cancellation using multi-reference coils was constructed to receive MRS signals. The feasibility of this system with theoretical calculation and experiments was analyzed and a modified sigmoid variable step size least mean square(SVSLMS) algorithm for noise cancellation was presented. The simulation results show that, the multi-reference coil method performs better than the single one on both signal-to-noise ratio(SNR) improvement and signal waveform optimization after filtering, under the condition of different noise correlations in the reference coils and primary detecting coils and different SNRs. In particular, when the noise correlation is poor and the SNR<0, the SNR can be improved by more than 8 dB after filtering with multi-reference coils. And the average fitting errors for initial amplitude and relaxation time are within 5%. Compared with the normalized least mean square(NLMS) algorithm and multichannel Wiener filter and processing field test data, the effectiveness of the proposed method is verified.

关键词： magnetic resonance sounding signal multi-reference coils adaptive noise cancellation sigmoid variable step size least mean square (SVSLMS)

Efficient signal Separation Method Based on Antenna Arrays for GNSS Meaconing

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Tsinghua Science and Technology 2019年第2期24卷 216-225页

作者： Jiaqi Zhang Xiaowei Cui Hailong Xu Sihao Zhao Mingquan Lu Department of Electronic Engineering Tsinghua University

As an effective deceptive interference technique for military navigation signals, meaconing can be divided into two main types: those that replay directly and those that replay after signal separation. The latter can add different delays to each satellite signal and mislead the victim receiver with respect to any designated position,thus has better controllability and concealment capability. A previous study showed there to be two main spatial processing techniques for separating military signals, whereby either multiple large-caliber antennas or antenna arrays are used to form multiple beams that align with all visible satellites. To ensure sufficient spatial resolution,the main lobe width of the antenna or beam must be sufficiently narrow, which requires the use of a large antenna aperture or a large number of array elements. In this paper, we propose a convenient and effective signal separation method, which is based on an antenna array with fewer elements. While the beam of the array is pointing to a specified satellite, the other satellite signals are regarded as interference and their power is suppressed to a level below the receiver's sensitivity. With this method, the number of array elements depends only on the number of visible satellites, thus greatly reducing the hardware cost and required processing capacity.

关键词： GNSS meaconing antenna array beamforming signal separation

A Squared-Chebyshev wavelet thresholding based 1D signal compression

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Defence Technology（防务技术） 2019年第3期15卷 426-431页

作者： Hanan A.R. Akkar Wael A.H. Hadi Ibraheem H. Al-Dosari Electronic Engineering in University of Technology Iraq Communication Engineering in University of Technology Iraq Electronic Engineering at Al-Rafidain University College Iraq

In this paper a square wavelet thresholding method is proposed and evaluated as compared to the other classical wavelet thresholding methods (like soft and hard). The main advantage of this work is to design and implement a new wavelet thresholding method and evaluate it against other classical wavelet thresholding methods and hence search for the optimal wavelet mother function among the wide families with a suitable level of decomposition and followed by a novel thresholding method among the existing methods. This optimized method will be used to shrink the wavelet coefficients and yield an adequate compressed pressure signal prior to transmit it. While a comparison evaluation analysis is established, A new proposed procedure is used to compress a synthetic signal and obtain the optimal results through minimization the signal memory size and its transmission bandwidth. There are different performance indices to establish the comparison and evaluation process for signal compression;but the most well-known measuring scores are: NMSE, ESNR, and PDR. The obtained results showed the dominant of the square wavelet thresholding method against other methods using different measuring scores and hence the conclusion by the way for adopting this proposed novel wavelet thresholding method for 1D signal compression in future researches.

关键词： PDR (percentage root mean squared difference) RMSE (root mean square error) signal compression Square wavelet thresholding

A Lamb wave signal reconstruction method for high-resolution damage imaging

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Chinese Journal of Aeronautics 2019年第5期32卷 1087-1099页

作者： Xiaopeng WANG Jian CAI Zhiquan ZHOU State Key Lab of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

In Lamb wave-based Structural Health Monitoring(SHM), a high-enough spatial resolution is highly required for Lamb wave signals to ensure the resolution and accuracy of damage detection. However, besides the dispersion characteristic, the signal spatial resolution is also largely restricted by the space duration of excitation waveforms, i.e., the Initial Spatial Resolution(ISR)for the signals before travelling. To resolve the problem of inferior signal spatial resolution of Lamb waves, a Lamb Wave signal Reconstruction(LWSR) method is presented and applied for highresolution damage imaging in this paper. In LWSR, not only a new linearly-dispersive signal is reconstructed from an original Lamb wave signal, but also the group velocity at the central frequency is sufficiently decreased. Then, both dispersion compensation and ISR improvement can be realized to achieve a satisfying signal spatial resolution. After the frequency domain sensing model and spatial resolution of Lamb wave signals are firstly analyzed, the basic idea and numerical realization of LWSR are discussed. Numerical simulations are also implemented to preliminarily validate LWSR. Subsequently, LWSR-based high-resolution damage imaging is developed. An experiment of adjacent multiple damage identification is finally conducted to demonstrate the efficiency of LWSR and LWSR-based imaging methods.

关键词： Damage imaging Dispersion compensation High resolution Lamb waves signal reconstruction

Use of a coded voltage signal for cable switching and fault isolation in cabled seafloor observatories

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Frontiers of Information Technology & Electronic Engineering 2018年第11期19卷 1328-1339页

作者： Zhi-feng ZHANG Yan-hu CHEN De-jun LI Bo JIN Can-jun YANG Jun WANG State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang University

Cabled seafloor observatories play an important role in ocean exploration for its long-term, real-time, and in-situ observation characteristics. In establishing a permanent, reliable, and robust seafloor observatory, a highly reliable cable switching and fault isolation method is essential. After reviewing the advantages and disadvantages of existing switching methods, we propose a novel active switching method for network configuration. Without additional communication path requirements, the switching method provides a way to communicate with a shore station through an existing power transmission path. A coded voltage signal with a distinct sequence is employed as the communication medium to transmit commands. The analysis of the maximum bit frequency of the voltage signals guarantees the accuracy of command recognition. A prototype based on the switching method is built and tested in a laboratory environment, which validated the functionality and reliability of the method.

关键词： Cabled seafloor observatories Cable switching and fault isolation Coded voltage signal Maximum bit frequency