共查询到18条相似文献,搜索用时 421 毫秒
1.
多普勒计程仪采用相控阵进行声波信号的发射和接收,不仅能够大大缩小换能器的体积,提高计程仪的适装性,还能依托相控阵本身的物理特性,无需进行声速补偿,所以在低频段获得了较多的应用。首先介绍了一维线阵波束形成的基本原理,然后分析了一维线阵的波束形成,获取多普勒计程仪发射波束及接收波束的方法,最后利用自制平面相控阵的水池测试结果与理论计算进行对比,结果表明,自制的相控阵满足多普勒计程仪的使用需求,为宽带大深度多普勒计程仪的制作奠定了基础。 相似文献
2.
相对于活塞式声学多普勒流速剖面仪,相控阵声学多普勒流速剖面仪的换能器体积大大缩小,并且依托相控阵本身的物理特性,无需进行声速补偿。利用窄带相控阵声学多普勒流速剖面仪系统进行编码信号的发射与接收,从而提高相控阵声学多普勒流速剖面仪的设备性能。首先介绍了相控阵ADCP的波束形成方法,然后分别介绍了相控阵的相移波束形成和时延波束形成原理,对编码信号相移相控波束形成情况下,相控阵发射和接收信号波束开角进行了对比,并对作用距离、测量精度、系统复杂度等系统性能进行了分析。分析结果表明:窄带相控阵声学多普勒流速剖面仪可以进行编码信号的发射和接收,能够提高系统的空间分辨率和测量精度,从而提高相控阵声学多普勒流速剖面仪的性能。 相似文献
3.
4.
5.
6.
近年来,船用多卜勒计程仪在军民用上得到了较大的发展.本文介绍了国内外的一些发展概况,从按Janus法配置的基阵一直到相控阵,同时将本单位研制的多卜勒计程仪与国内外的计程仪作了比较. 相似文献
7.
声学多普勒计程仪(Doppler velocity log, DVL)是一种能为水面或水下载体提供定位和导航信息的重要设备。传统的DVL通常采用Janus配置方式,向海底发射沿载体前后左右方向的4个波束,并利用多普勒频移来计算载体的速度。而对于传统相控阵DVL,阵元布阵间距通常为二分之一波长,同一方向两波束间夹角为60°。该研究在传统相控阵DVL的基础上,提出一种八波束的相控阵DVL,在两个互相垂直的方向上,各形成4个波束,即双Janus配置方式。根据仿真对比分析,确定阵元布阵间距为0.35倍波长,同一方向上4个波束所对应的角度分别是±43.56°和±20.16°,这样,在两个互相垂直的方向上,4个与水平面方向夹角较小的波束,可以提供更大的水平分量,更有利于进行多普勒频移的计算;4个与水平面方向夹角较大的波束,有着更大的垂直分量,使接收的回波信号有较大的信号强度,两种波束优势互补。同时,制作了一个八波束换能器,并进行了水池测试,指向性波束夹角分别为±43.49°和±20.10°,与仿真结果较好吻合,对应发送电压响应分别为170.2 dB和170.6 dB。 相似文献
8.
国内相控阵ADCP技术的开发研究 总被引:5,自引:0,他引:5
声学多普勒海流剖面仪(ADCP)是海洋勘测领域的一项高新技术,ADCP的相控阵技术在换能器阵体积重量不增大的条件下进一步提高了测量范围和测速精度。本文着重介绍我们开发相控阵ADCP的情况及实时处理的湖上试验结果。试验表明相控阵ADCP测流原理是可行的,测量精度可达到1cm/s。 相似文献
9.
10.
介绍了一种小型化线列阵,阵结构与常规线列阵最大的不同在于阵元间距小于四分之一波长。通过理论分析和仿真计算优化了各阵元的最佳权系数,获得了良好的指向性,得到了实验的证明。小型化线列阵的指向性图具有四大特点:①单向性:仅在半空间出现一个轴对称的主波束,无栅瓣和次瓣。②端射特性:主波束出现在线阵的轴射方向。③超指向性:在阵的尺寸远小于二分之一波长条件下不仅可以获得良好的指向性图,并且波束宽度随阵元间距的减小而减小。④恒定束宽特性:在阵元间距小于八分之一波长条件下,波束宽度随频率变化非常平缓。这种小型化基阵也可用于大型基阵如拖曳阵和展开式体积阵的子基阵,进行低频宽带信号的检测。 相似文献
11.
针对阿基米德螺旋相控阵换能器焦点声压不足的问题,通过有限元仿真,分别讨论了换能器阵元形状和频率改变与声场的变化关系,从焦点声压、偏转范围、栅瓣水平、焦域大小等方面进行了研究。结果表明,相同频率下,扇形阵元阿基米德螺旋相控阵换能器的焦点声压比圆形阵元时的焦点声压提高了32.28%,偏转范围为20 mm×20 mm×40 mm;在扇形阵元形状的情况下,频率选择0.9~1.0 MHz,不仅能获得较高的焦点声压,同时还能保证改善聚焦性能。文章的仿真结果为阿基米德螺旋相控阵换能器提高焦点声压,满足深部组织消融治疗需要的高功率要求提供了有用的设计参考。 相似文献
12.
Sound field calculations for an ultrasonic linear phased array with a spherical liquid lens 总被引:1,自引:0,他引:1
Yoon YJ Benkeser PJ 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1992,39(2):268-272
Lenses are often used to provide focusing in the elevation dimension of ultrasonic linear phased-array transducers. The use of a liquid lens in this application adds a variable geometric focusing capability, determined by the radius of curvature of the lens surface and speed of sound in the liquid, to the electronic focusing produced by the linear phased array. An efficient method to calculate the sound field radiated from the linear phased-array transducer through the liquid lens is presented. It treats the lens surface as a secondary source distribution according to Huygens's principle, and employs a modified form of the rectangular radiator method to calculate the field. The appropriate phases for the array elements to focus and steer the beam are calculated by considering the refraction on the lens surface. Comparisons of computer simulations and experimental measurements of the field intensity distribution of a prototype linear array transducer with a liquid lens demonstrate the accuracy of the proposed method. 相似文献
13.
Real-time angular scatter imaging system for improved tissuecontrast in diagnostic ultrasound images
Robinson M.T. von Ramm O.T. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1994,41(1):44-52
A new type of real-time ultrasound imaging system has been developed. In contrast to conventional systems, which process only echoes scattered directly back from tissue to form an image, this system images tissue by displaying energy scattered at other angles. In its present form, the system uses one 32 element, 2.4 MHz phased array transducer in transmit and a second, spatially separate 32 element, 2.4 MHz phased array transducer in receive, to detect sound which is scattered away from the transmit transducer. In order to form an image line, the transmit transducer sends into the body a steered pulse, which is tracked dynamically from the side by the receive transducer. The signal detected by the receive transducer is processed in the same manner as in a standard B-mode phased array system. The final display format is a gray scale sector originating from the transmit transducer. Real-time angular scatter images of phantom and in vivo targets have been formed and compared to standard backscatter B-mode images of the same targets 相似文献
14.
曲面构件被广泛应用在各个领域的关键部位,一旦出现质量问题将造成不可估量的后果,为确保曲面构件在服役期间安全可靠,对其定期进行无损检测尤为重要。因超声相控阵技术检测灵敏度高、速度快,适用于曲面构件的快速检测,特别是柔性相控阵换能器的成功研制满足了复杂曲面构件的检测需求,但目前仍缺乏相应的理论支撑。因此,提出了复杂曲面柔性相控阵动态聚焦理论,并建立有限元声场时域仿真模型。结果表明,基于所提出的聚焦理论,采用柔性相控阵换能器可解决复杂曲面构件内部微小缺陷检测难题,为柔性相控阵换能器参数设计提供了理论依据,推动了柔性相控阵换能器的应用与发展。 相似文献
15.
16.
Nock LF Trahey GE 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1992,39(4):489-495
The use of a synthetic receive aperture (SRA) system to increase the resolution, of a phased-array imaging system severalfold, by utilizing the available number of parallel receiver channels to address a larger number of transducer elements through a multiplexer system, is considered. Recent studies indicate that transducers with a very large number of elements will improve the detectability of small or low contrast targets when adaptive focusing is used to compensate for the effects of acoustic velocity inhomogeneities in tissue. With the effectively increased transducer element count afforded by an SRA system, a 1-by-N phased array could be split into an M-by-N array in order to improve resolution in the elevation dimension. Simulation results illustrate the lateral resolution achievable with several types of imaging systems: SRA, synthetic focus, and conventional phased array. Simulated images demonstrate the improvement in contrast resolution achievable using SRA. Experimental results show the improvement in beam width achieved by an experimental SRA system. 相似文献
17.
Frank Mielentz 《Journal of Nondestructive Evaluation》2008,27(1-3):23-33
An innovative application of ultrasonic testing using phased arrays for concrete components was investigated. A low frequency ultrasonic phased array consisting of ten transducers was used. This configuration allowed the variation and control of the sound field directivity during the measurement. The measurements were carried out on concrete test specimens using a scanning laservibrometer in through transmission mode. The laboratory measurements were compared to theoretical calculations to investigate the influence of shape and dimension of the transducer on the resulting sound field patterns. The technique was successfully implemented to detect an ungrouted tendon duct in a concrete block. 相似文献