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通过简要介绍利用声学多普勒水流剖面仪(ADCP)回波强度估算悬移质含沙量的基本原理,结合梧州水文站的应用实例,利用ADCP的回波强度数据和现场采集的水样含沙量建立相关关系,根据相关关系由回波强度反演估算的水体悬移质含沙量验证了利用ADCP的回波强度估算悬移质含沙量的可行性。应用于梧州水文站的实践表明,左河道推算的系统误差为-0.1%,右河道推算的系统误差为1.5%。这种方法具有不扰动流场、测量剖面同步性较好、数据空间分辨率较高的优点,与传统的取样过滤称量法相比,计算效率显著提高。 相似文献
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王英 《佳木斯工学院学报》2010,(2):225-227,231
研制成功的声频谱测井仪器在井下发射和接收三种频率的声波信号,其中发射和接收20kHz声波信号的声系有一个发射和四个接收探头,源距为2.1~2.568m,间距为0.156m;发射和接收40kHz声波信号的声系由一个发射和两个接收探头组成,源距1.0—1.5m,间距0.5m;发射和接收10kHz声波信号的声系由一个发射和两个接收探头组成,源距为2.168—2.668m,间距0.5m.用三种不同的频率的声波进行测量记录目的是获得井壁径向深度不同处介质的声学信息,而且不同频率的声波信号在岩石中传播过程中频谱变化也是井壁岩层的可用声学信息.在井下的信息采集、数据传输、地面记录和监控全部由计算机控制.该仪器已经在大庆油田的三口井中成功的进行了野外实验. 相似文献
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T. Nguyen-Ky Author Vitae J. Leis Author Vitae Author Vitae 《Computers & Electrical Engineering》2010,36(4):664-675
In this paper, we propose an new error estimate algorithm (NEEA) for stereophonic acoustic echo cancellation (SAEC) that is based on the error estimation algorithm (EEA) in [Nguyen-Ky T, Leis J, Xiang W. An improved error estimate algorithm for stereophonic acoustic echo cancellation system. In: International conference on signal processing and communication systems, ICSPCS’2007, Australia; December 2007]. In the EEA and NEEA, with the minimum error signal fixed, we compute the filter lengths so that the error signal may approximate the minimum error signal. When the echo paths change, the adaptive filter automatically adjusts the filter lengths to the optimum values. We also investigate the difference between the adaptive filter lengths. In contrast with the conclusions in [Khong AWH, Naylor PA. Stereophonic acoustic echo cancellation employing selective-tap adaptive algorithms. IEEE Trans Audio, Speech, Lang Process 2006;14(3):785-96, Gansler T, Benesty J. Stereophonic acoustic echo cancellation and two channel adaptive filtering: an overview. Int J Adapt Control Signal Process 2000;4:565-86, Benesty J, Gansler T. A multichannel acoustic echo canceler double-talk detector based on a normalized cross-correlation matrix. Acoust Echo Noise Control 2002;13(2):95-101, Gansler T, Benesty J. A frequency-domain double-talk detector based on a normalized cross-correlation vector. Signal Process 2001;81:1783-7, Eneroth P, Gay SL, Gansler T, Benesty J. A real-time implementation of a stereophonic acoustic echo canceler. IEEE Trans. Speech Audio Process 2001;9(5):513-23, Gansler T, Benesty J. New insights into the stereophonic acoustic echo cancellation problem and an adaptive nonlinearity solution. IEEE Trans. Speech Audio Process 2002; 10(5):257-67, Benesty J, Gansler T, Morgan DR, Sondhi MM, Gay SL. Advances in network and acoustic echo cancellation. Berlin: Springer-Verlag; 2001], our simulation results have shown that the filter lengths can be different. Our simulation results also confirm that the NEEA is better than EEA and SM-NLMS algorithm in terms of echo return loss enhancement. 相似文献
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Numerous attempts have been undertaken to apply the spectral subtraction method to cancel noise perturbations but these efforts have yet to produce an algorithm that is able to adapt well to the environmental changes in the perturbations. In addition, the variants of the spectral subtraction method so far proposed in the literature would require a non-voice activity detector (NVAD), for a single microphone system, to store the perturbation. This is used as an estimate for the reference signal. Inaccuracy in the perturbation estimates causes the cleaned speech to be corrupted by musical artifacts, which is unacceptable. Post processing of signals corrupted by the musical artifacts is very costly. This paper provides an alternative approach that employs associative memory for speech enhancement. Extensive comparison is made using the soft computing approaches for noise cancellation based on associative memories. A set of stereo microphones captures the corrupted speech in a vehicle and is used to point to the closest associative memory location. The Wiener filter approach is used to cancel the noise. The paper discusses novel examples of the associative memories using the cerebellum model for noise modeling. Experimental results show the potential of these novel soft computing architectures in generating and adapting the required Weiner filters to cancel perturbation even at signal to noise ratio (SNR) of less than −13 dB. 相似文献
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本文所阐述的水下无线技术即基于跳频技术和同步捕获技术的水声通信,由于声波在海水中的传播特性显著优越于电磁波和可见光,使得水声技术成为海洋高技术的主要研究领域之一 ,在国防领域也具有十分重要的研究意义.本文主要论述了水声通信中跳频技术和同步捕获技术的原理、具体算法的实现方案以及部分硬件设施的使用简述,并通过展示实验结果验证算法的可行性. 相似文献
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详细叙述了终端的音频指标要求和测试调试方法,之后基于Infineon平台的一个实际项目中,论述了如何测试和配置控制数据全过程,使读者能够全面了解GSM手机音频方面的技术标准和电路调试过程. 相似文献
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The aim of magnetization transfer is to saturate the protons of the macromolecule pool with a radiofrequency (RF) pulse leading
to differences in free water pool signal. Magnetization transfer (MT) contrast is difficult to achieve with the echo planar
imaging (EPI) technique, although its short acquisition time would be most beneficial. Indeed, the RF saturation pulses can
only be applied once before sampling the whole k-space in a single-short sequence. A possible solution to improve the sensitivity
of EPI to magnetization transfer consists in applying a train of several saturation RF pulses before image acquisition. The
different parameters of a RF pulse train and their influence on the MT rate have been tested to optimize an EPI clinical sequence.
Our experimental procedure makes it possible to obtain a MT map in about 1 second. The technique is evaluated by multiple
sclerosis lesion characterization.
Supported by grants from the French research ministry and Siemens medical France. 相似文献
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