A system for simulating and analyzing the Doppler signal of air-target fuse is established by constructing two parts： Doppler signal testing with simulation and Doppler signal analysis. The first part establishes the...A system for simulating and analyzing the Doppler signal of air-target fuse is established by constructing two parts： Doppler signal testing with simulation and Doppler signal analysis. The first part establishes the near-field target characteristic model where the Doppler spectrum in different encounter condition is obtained. The second part mainly deals with a general purpose hardware platform to obtain and process the Doppler signal as well as a software to estimate the Doppler spectrum. The model and the result of Doppler spectrum analysis were verified by experiments.展开更多
In order to diagnose the cerebral infarction, a classification system based on the ARMA model and BP (Back-Propagation) neural network is presented to analyze blood flow Doppler signals from the carotid artery. In thi...In order to diagnose the cerebral infarction, a classification system based on the ARMA model and BP (Back-Propagation) neural network is presented to analyze blood flow Doppler signals from the carotid artery. In this system, an ARMA model is first used to analyze the audio Doppler blood flow signals from the carotid artery. Then several characteristic parameters of the pole's distribution are estimated. After studies of these characteristic parameters' sensitivity to the textcolor cerebral infarction diagnosis, a BP neural network using sensitive parameters is established to classify the normal or abnormal state of the cerebral vessel. With 474 cases used to establish the appropriate neural network, and 52 cases used to test the network, the results show that the correct classification rate of both training and testing are over 94%. Thus this system is useful to diagnose the cerebral infarction.展开更多
A computer simulation method for pulsed Doppler signals from vortices was pro- posed to generate simulated vortex Doppler signals under various given circumstances. The relative waveforms, such as the maximum frequenc...A computer simulation method for pulsed Doppler signals from vortices was pro- posed to generate simulated vortex Doppler signals under various given circumstances. The relative waveforms, such as the maximum frequency waveform, the mean frequency waveform and the bandwidth waveform, were obtained using the short time Fourier analysis of those simulated signals. The relations were studied between several spectrum parameters obtained from these waveforms and given simulation conditions, such as the position and the size of the sample volume, the distance between two vortices, the free stream velocity and the maximum tangent velocity of the vortex. The sensitive parameters were found to detect vortices using the pulsed Doppler techniques.展开更多
在未来的通信网络中,被广泛期待的第6代移动通信系统(The Sixth Generation of Mobile Communications System,6G)技术将面临诸多挑战,其中包括在高速移动场景下的超高可靠通信问题。正交时频空间(Orthogonal Time Frequency Space,OTFS...在未来的通信网络中,被广泛期待的第6代移动通信系统(The Sixth Generation of Mobile Communications System,6G)技术将面临诸多挑战,其中包括在高速移动场景下的超高可靠通信问题。正交时频空间(Orthogonal Time Frequency Space,OTFS)调制技术克服了传统通信系统在高速移动环境下多径和多普勒效应的影响,为实现6G超高可靠通信提供了新的可能性。该文首先介绍了OTFS的基本原理、数学模型、干扰与优势分析。然后,归纳分析了OTFS技术在同步、信道估计、信号检测技术上的研究现状。接着,从车联网、无人机、卫星通信、海洋通信4个典型应用场景分析了OTFS的应用趋势。最后,从降低多维匹配滤波器、相位解调和信道估计、硬件实现的复杂度和提高对时频资源的高度利用4个角度探讨了未来研究OTFS需要克服的困难和挑战。展开更多
文摘A system for simulating and analyzing the Doppler signal of air-target fuse is established by constructing two parts： Doppler signal testing with simulation and Doppler signal analysis. The first part establishes the near-field target characteristic model where the Doppler spectrum in different encounter condition is obtained. The second part mainly deals with a general purpose hardware platform to obtain and process the Doppler signal as well as a software to estimate the Doppler spectrum. The model and the result of Doppler spectrum analysis were verified by experiments.
基金This work was supported by the KeyTeacherFundsofEducationMinistryofChina.
文摘In order to diagnose the cerebral infarction, a classification system based on the ARMA model and BP (Back-Propagation) neural network is presented to analyze blood flow Doppler signals from the carotid artery. In this system, an ARMA model is first used to analyze the audio Doppler blood flow signals from the carotid artery. Then several characteristic parameters of the pole's distribution are estimated. After studies of these characteristic parameters' sensitivity to the textcolor cerebral infarction diagnosis, a BP neural network using sensitive parameters is established to classify the normal or abnormal state of the cerebral vessel. With 474 cases used to establish the appropriate neural network, and 52 cases used to test the network, the results show that the correct classification rate of both training and testing are over 94%. Thus this system is useful to diagnose the cerebral infarction.
基金This work is supported by the Outstanding Young Teacher Funds of Chinese Ministry of Education.
文摘A computer simulation method for pulsed Doppler signals from vortices was pro- posed to generate simulated vortex Doppler signals under various given circumstances. The relative waveforms, such as the maximum frequency waveform, the mean frequency waveform and the bandwidth waveform, were obtained using the short time Fourier analysis of those simulated signals. The relations were studied between several spectrum parameters obtained from these waveforms and given simulation conditions, such as the position and the size of the sample volume, the distance between two vortices, the free stream velocity and the maximum tangent velocity of the vortex. The sensitive parameters were found to detect vortices using the pulsed Doppler techniques.
文摘在未来的通信网络中,被广泛期待的第6代移动通信系统(The Sixth Generation of Mobile Communications System,6G)技术将面临诸多挑战,其中包括在高速移动场景下的超高可靠通信问题。正交时频空间(Orthogonal Time Frequency Space,OTFS)调制技术克服了传统通信系统在高速移动环境下多径和多普勒效应的影响,为实现6G超高可靠通信提供了新的可能性。该文首先介绍了OTFS的基本原理、数学模型、干扰与优势分析。然后,归纳分析了OTFS技术在同步、信道估计、信号检测技术上的研究现状。接着,从车联网、无人机、卫星通信、海洋通信4个典型应用场景分析了OTFS的应用趋势。最后,从降低多维匹配滤波器、相位解调和信道估计、硬件实现的复杂度和提高对时频资源的高度利用4个角度探讨了未来研究OTFS需要克服的困难和挑战。
