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61.
时间同步是传感器节点协同工作的基础.水下传感器网络由于采用水声通信方式,具有不同于陆地无线传感器网络的特点,为时间同步算法研究带来了新的挑战.论文首先说明同步问题与同步算法的形式化定义,然后讨论水下传感器网络不同于陆地传感器网络的特点,并指出相关特点对于同步问题的影响;接着综述陆地传感器网络同步算法的研究进展,分析相关算法用于水下环境的不足;进而介绍水下传感器网络同步算法的研究进展,并通过仿真实验完成了相关算法的性能对比;最后总结水下传感器网络时间同步的关键问题,指出进一步的研究方向. 相似文献
62.
声测定位技术的现状研究 总被引:1,自引:0,他引:1
声测定位技术是利用声学与电子装置接收声信号以确定声源位置的一种技术,具有隐蔽性好、保密性强、不易受干扰等特点。近年来受到各国的重视,并在军事领域得到长足的发展。重点介绍声测定位的关键技术,时延估计算法和声测阵列的选择是影响定位精度的主要因素。对几种广泛采用的声测阵列,给出相应的基本原理、定位计算方法并对各自特点进行比较。在声测定位系统中,利用时延估计对声信号进行处理是定位的重要环节,介绍了时延估计的基本理论、研究状况以及精度分析和比较,分析了影响定位精度的其他因素。 相似文献
63.
针对宽频声表面波的高灵敏度检测需求,研究设计搭建了基于偏振差分干涉技术的激光声表面波检测系统。实验中从干涉条纹可见度和差分信号的大小来评估系统的调试效果,利用压电陶瓷纳米位移台和SIOS干涉仪对检测系统进行测试和标定,得到系统的最小静态、动态检测位移;对系统各组成部分的噪声信号进行分析,并提出相应的抑制方法。最后对系统进行重复性测量,并对铝、硅样片上的激光声表面波信号进行检测。本研究为声表面波检测系统的性能评估提供了科学可行的方法,为声表面波技术在无损检测中的应用提供了一种可靠的测量手段。 相似文献
64.
65.
Sadaoki Furui 《The Journal of VLSI Signal Processing》2005,41(3):245-254
The principal cause of speech recognition errors is a mismatch between trained acoustic/language models and input speech due
to the limited amount of training data in comparison with the vast variation of speech. It is crucial to establish methods
that are robust against voice variation due to individuality, the physical and psychological condition of the speaker, telephone
sets, microphones, network characteristics, additive background noise, speaking styles, and other aspects. This paper overviews
robust architecture and modeling techniques for speech recognition and understanding. The topics include acoustic and language
modeling for spontaneous speech recognition, unsupervised adaptation of acoustic and language models, robust architecture
for spoken dialogue systems, multi-modal speech recognition, and speech summarization. This paper also discusses the most
important research problems to be solved in order to achieve ultimate robust speech recognition and understanding systems.
Dr. Sadaoki Furui is currently a Professor at Tokyo Institute of Technology, Department of Computer Science. He is engaged in a wide range
of research on speech analysis, speech recognition, speaker recognition, speech synthesis, and multimodal human-computer interaction
and has authored or coauthored over 450 published articles. From 1978 to 1979, he served on the staff of the Acoustics Research
Department of Bell Laboratories, Murray Hill, New Jersey, as a visiting researcher working on speaker verification. He is
a Fellow of the IEEE, the Acoustical Society of America and the Institute of Electronics, Information and Communication Engineers
of Japan (IEICE). He was President of the Acoustical Society of Japan (ASJ) from 2001 to 2003 and the Permanent Council for
International Conferences on Spoken Language Processing (PC-ICSLP) from 2000 to 2004. He is currently President of the International
Speech Communication Association (ISCA). He was a Board of Governor of the IEEE Signal Processing Society from 2001 to 2003.
He has served on the IEEE Technical Committees on Speech and MMSP and on numerous IEEE conference organizing committees. He
has served as Editor-in-Chief of both Journal of Speech Communication and the Transaction of the IEICE. He is an Editorial
Board member of Speech Communication, the Journal of Computer Speech and Language, and the Journal of Digital Signal Processing.
He has received the Yonezawa Prize and the Paper Awards from the IEICE (1975, 88, 93, 2003), and the Sato Paper Award from
the ASJ (1985, 87). He has received the Senior Award from the IEEE ASSP Society (1989) and the Achievement Award from the
Minister of Science and Technology, Japan (1989). He has received the Technical Achievement Award and the Book Award from
the IEICE (2003, 1990). He has also received the Mira Paul Memorial Award from the AFECT, India (2001). In 1993 he served
as an IEEE SPS Distinguished Lecturer. He is the author of “Digital Speech Processing, Synthesis, and Recognition” (Marcel
Dekker, 1989, revised, 2000) in English, “Digital Speech Processing” (Tokai University Press, 1985) in Japanese, “Acoustics
and Speech Processing” (Kindai-Kagaku-Sha, 1992) in Japanese, and “Speech Information Processing” (Morikita, 1998) in Japanese.
He edited “Advances in Speech Signal Processing” (Marcel Dekker, 1992) jointly with Dr. M.M. Sondhi. He has translated into
Japanese “Fundamentals of Speech Recognition,” authored by Drs. L.R. Rabiner and B.-H. Juang (NTT Advanced Technology, 1995)
and “Vector Quantization and Signal Compression,” authored by Drs. A. Gersho and R. M. Gray (Corona-sha, 1998). 相似文献
66.
67.
研究了基于G-N模型与三项延迟模型的热弹性波的传播特征.在各种广义热弹性理论中,热位移概念的引入使得G-N模型具有独特性质而引起广泛的关注和应用.基于G-N模型,最近一个三相延迟模型被提出.主要研究了这两种模型下第一和第二声波(耦合热弹性波)的色散和衰减特性,分析了温度场和位移场在两种模型下的振幅比和相位差.结果发现三... 相似文献
68.
Zhenxing Ji Peihua Jiang Haiyang Yi Zhuang Zhuo Chunyuan Li Zhide Wu 《Entropy (Basel, Switzerland)》2022,24(6)
The issue of monitoring and early warning of rock instability has received increasing critical attention in the study of rock engineering. To investigate the damage evolution process of granite under triaxial compression tests, acoustic emission (AE) tests were performed simultaneously. This study firstly introduced two novel parameters, i.e., the coefficient of variation (CoV) of the information entropy and correlation dimension of the amplitude data from the AE tests, to identify the precursor of the failure of granite. Then the relationship between the changes in these parameters and the stress-time curve was compared and analyzed. The results of this study show that: (1) There is a strong correlation between the CoV of the information entropy and the failure process of granite. The granite failed when the CoV curve raised to a plateau, which could be used as an indicator of rock instability. (2) The fluctuation of the correlation dimension indicates the different stages during the loading process, i.e., the initial compaction stage, the linear elastic stage, the yield stage, and the failure stage. Each stage contains a descending and a rising process in the correlation dimension curve, and the exhibited starting point or the bottom point at the correlation dimension curve could be selected as the indicator point for the rock instability. (3) The combined analysis of the Information entropy and Correlation dimension can improve the accuracy of rock instability prediction. This study provides new insights into the prediction of rock instability, which has theoretical implications for the stability of subsurface engineering rock masses. 相似文献
69.
70.
利用圆环类微带行波天线的辐射功率与等效行波磁流衰减常数之间的自洽关系,导出了计算衰减常数的迭代方程;为加快迭代速度,将辐射积分中的格林函数展开成柱面波函数,得到快速收敛的级数和.最后给出了方向图的计算曲线,与实验结果对比吻合良好,表明此方法模拟圆环类微带行波天线辐射特性的有效性. 相似文献