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Simple Fraunhofer approximation was unsuitable for analysing acoustic field of transducer arrays in tissue because linear array B- scanners image in near and middle field. But for a single element, far-field conditions easily satisfy most imaging area and a simpler distribution of acoustic field can be deduced by means of Fraunhofer approximation. The sonic field of the array is the superposition of fields of elements. Much less EPU times are required for calculating the superposing acoustic field... Simple Fraunhofer approximation was unsuitable for analysing acoustic field of transducer arrays in tissue because linear array B- scanners image in near and middle field. But for a single element, far-field conditions easily satisfy most imaging area and a simpler distribution of acoustic field can be deduced by means of Fraunhofer approximation. The sonic field of the array is the superposition of fields of elements. Much less EPU times are required for calculating the superposing acoustic field than calculating the classical Fresnel integral. The results indicate that the unfocused sonic fields of arrays are similar to that of rectangular plate radiator. Just the right dedays can effectively converge the beam of a transducer array to realize electronic focus. The minimum focus range is decided by the width of elements. The receiving of back scattering signals is the contrary procedu reof the ultrasonic transmitting and can be discribed by the same function as the transmitting, and also can be focused by proper delays to improve the ultrasonic image. 线阵B超的成象区域都是在近中场,用简单的Fraunhofer近似研究组织中的声场分布是不恰当的。然而,整个阵列的激励声场是各单个阵元的激励声场的迭加,而且单个阵元的声场在大部分成象区域内都满足远场条件,可以用Fraunhofer近似处理得到较简单的声场分布函数。用单阵元分布函数迭加所得的换能器声场分布的数值计算,比计算经典的Fresnel积分的运算量要小得多。计算结果表明:换能器阵列在成象区域内的非聚焦声场与矩形平板换能器声场的近中场分布规律相近,适当引入延时可以使阵列换能器的声束有效会聚而实現电子聚焦。当换能器口径一定时,电子聚焦的最小焦距受阵元宽度限制。超声仪器对组织后向散射信号的接收是发射的逆过程,可以用相同的函数描述。同样,也可以通过适当的延时实現电子聚焦,从而进一步提高成象的分辨力。 The sonic field transmission matrixes of perforated absorbent pipe is given after the transmission performance of perforated pipe is studied. Based on the defination of insortion loss, the mathematic model of muffler is set up in this paper, the tendency of accoustic performance of perforated absorbent pipe with different parameters is analysed through verify consistency of theory and experiment. 本文通过声波在穿孔声管中传播特性的研究,导出了声波在穿孔声管中传播的声场传递矩阵。文中运用插入损失的定义,建立了消声器消声性能的数学模型,并在实验验证基础上,分析了各种参数对穿孔声管消声器消声性能影响的变化规律。 Some experimental results and analyses from the measurements of the sound field in a single transonic axial compressorr inlet duct with single plastic glass lining are presented.The plastic glass linings are designed and made by ourselves (two kinds of perforate rating,σ 1=2 85% and σ 2=5 85%).The experimental results are firstly obtained in China from the real sonic fields in a single transonic axial compressor at high sound... Some experimental results and analyses from the measurements of the sound field in a single transonic axial compressorr inlet duct with single plastic glass lining are presented.The plastic glass linings are designed and made by ourselves (two kinds of perforate rating,σ 1=2 85% and σ 2=5 85%).The experimental results are firstly obtained in China from the real sonic fields in a single transonic axial compressor at high sound pressure conditions (>150dB).The experimental results and conclusions provide some reference for the further investigation on design of the acoustic treatment assemblies in aeroengine nacells and turbomachinery duct. 介绍用有机玻璃制作的两套结构尺寸不同的微穿孔消声声衬试件，在单级跨音压气机台上进行的３次降噪实验。目前国内尚无人获得微穿孔消声声衬在跨音、大流量、高声压级模拟声源环境条件下的噪声测试数据。通过实验，为进一步合理地设计声衬提供了参考数据，并看到了这种降噪方法在流体机械管道消声方面的应用前景。
sonic field
声场
Influence of Sonic Field on Growth of Sucrose Crystals 声场对蔗糖晶体生长的影响 短句来源 Under the condition of the inhalable particles of burned coal being subject to the action of a high intensity sonic field studied was the impact of different acoustic intensity and particle retention time in sonic field on the change of particle diameter distribution prior to and after the acoustic agglomeration. 研究了燃煤可吸入颗粒物在高强度声波场作用下,不同声波强度和声场停留时间对于声波团聚前后颗粒粒径分布变化的影响。 短句来源 This lecture simply introduces the relation between wave and vibration, the classification of ultrasonicwave, the trarsmission character of ultrasonicwave and the sonic field characteristic parameters. 简要介绍了波与振动的关系，超声波的分类，超声波的传播特性与声场特征量。 短句来源 The temperature of the sugar saturated solution is decreased from 60℃ to 40℃quickly, and the solut ion is affected by sonic field, the stabillty of sugar saturatedsolution drops. 将60℃下的过饱和糖液迅速冷却至40℃，并附加一个声场，过饱和糖液的稳定性降低。 短句来源 Through a theoretical analysis of a plane standing-wave sonic field a test rig on acoustic agglomeration and removal characteristics of burned coal inhalable particles has been designed and set up. 通过对平面驻波声场的理论分析,设计并建立了燃煤可吸入颗粒物声波团聚清除特性的实验台。 短句来源 更多 “sonic field”译为未确定词的双语例句
Study on the Mechanism of Stability of Sugar Saturated Solution affected by Sonic Field 声场影响过饱和糖液稳定性的机理研究 短句来源 Influence of Sonic Field on ZrO_2 Gel by Sol-gel 声场影响氧化锆纳米粉体溶胶-凝胶制备过程的研究 短句来源 相似匹配句对
Influence of Sonic Field on Growth of Sucrose Crystals 声场对蔗糖晶体生长的影响 短句来源 Theoretical Studying of Sound Field of Sonic Cleaning 锅炉声波吹灰的声场特性研究 短句来源 There is reinfection in field. 鱼腥草紫斑病在田间具多次再侵染。 短句来源 field by using it . 结果证明该方法简便适 用. 短句来源 Sonic Sootblowing Technology 声波除灰技术 短句来源 
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Convective heat transfer in response to a sonic field in saturated sand
With the objective of a preferably diffuse distributed sonic field we applied frequency modulated ultrasound to the material.
Milk droplets with uniform dimensions are also produced by creating a sonic field at a constant frequency in the vicinity of the atomizer.
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