共查询到20条相似文献,搜索用时 62 毫秒
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1 引言 多普勒效应是指当波源和接收器之间有相对运动时,所接收到的频率不等于波源振动频率的现象.这一现象是1842年由奥地利物理学家多普勒(Christian Doppler)首先在声学上发现的.1930年左右开始将这一规律运用到电磁波范围,1950年左右研制出了第一代多普勒雷达.下面简要介绍多普勒效应及其在雷达中的应用. 相似文献
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多普勒和多普勒效应的起源 总被引:9,自引:0,他引:9
介绍了奥地利物理学家多普勒的生平,回顾了多普勒对波源和观测者之间有相对运动时接收到的波频率改变的效应即多普勒效应的最初论述,以及人们早期对多普勒效应在声学、天文学及光学领域的实验验证情况.论述了多普勒效应的历史作用和纪念多普勒的现实意义. 相似文献
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基于数字存储示波器的超声多普勒效应实验系统的研究与应用 总被引:1,自引:0,他引:1
介绍了一种基于数字存储示波器的超声多普勒效应实验系统.该系统利用现有的超声声速测量设备,以频移信号处理电路和数字存储示波器作为数据测量单元的核心,通过与系统底座和运动控制单元相配合,开展与多普勒效应相关的多项综合性、设计性实验.实验中信号的转换、传输和处理过程清晰透明,有利于培养学生的自主动手能力和观察分析问题的能力.该实验系统结构简单,无需复杂的软件编程,各实验室均可自行完成制作,同时又可实现实验资源共享,提高仪器设备的利用率,具有较高的实用和推广价值. 相似文献
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声波多普勒效应演示实验 总被引:4,自引:2,他引:2
利用声波多普勒效应导致声强变化的特性,设计了声波多普勒效应实验装置,该装置将声音信号转变成电信号,并用信号大器进行放大,驱动发光二极管发光演示了声波的多普勒效应. 相似文献
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声波多普勒效应综合实验 总被引:2,自引:2,他引:2
利用运动物体反射声波与原声波合成后产生拍,用数字存储示波器测定拍频,从而测定空气中的声速或运动物体的速度,并给出了相应的实验装置、实验方法。 相似文献
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Michael Ph. Pyshnyi Svetlana V. Pyshnaya Galina S. Nechitailo Anatoly A. Kuznetsov 《Journal of magnetism and magnetic materials》2009,321(10):1552-1556
We considered applicability of acoustic imaging technology for the detection of magnetic microparticles and nanoparticles inside soft biological tissues. Such particles are widely used for magnetically targeted drug delivery and magnetic hyperthermia. We developed a new method of ultrasonic synchronous tissue Doppler imaging with magnetic modulation for in vitro and in vivo detection and visualization of magnetic ultradisperse objects in soft tissues. Prototype hardware with appropriate software was produced and the method was successfully tested on magnetic microparticles injected into an excised pig liver. 相似文献
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Guéron M 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,160(2):151-156
An NMR sample may be subject to motions, such as those due to sample spinning or to liquid flow. Is the spectrum of such a sample affected by the Doppler effect? The question arises because, instrumental dimensions being much shorter than the wavelength, it is the near-field of the precessing magnetic moment which couples to the receiver coil, rather than the radiated far-field. We expand the near-field into plane propagating waves. For each such wave there is another one with the same amplitude, propagating in the opposite direction. The Doppler shifts are therefore equal and opposite. In the model case of a small fluid sample moving with constant velocity, this leads to a distribution of Doppler shifts which is symmetrical with respect to the unshifted frequency: there is no net spectral shift. We examine the possibility of observing the Doppler distribution in this case. We also consider the case of thermal motion of a gas. We draw attention to the resolved Doppler splitting of molecular rotational transitions in a supersonic burst as observed in a microwave resonator. We also mention briefly the Doppler effect in molecular beam spectroscopy. 相似文献