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智能机器人必须具有一种能觉察外部世界的方法。近年来,人们已相继开发了一些诸如利用光波、X射线、电磁波来识别物体的方法,然而,迄今还未有明确地选择并找到一种十分完美的机器人观察装置。 本文提出一种机器人超声波眼睛新系统。利用超声波观察至少有如下三方面的优点:第一,在光波难以观察的场合,如烟雾、黑暗或水下等能见度差的情况下,超声波便可大显身手;第二,利用超声波可检出被测物的相位信息,藉此,就能直接计算出该物体的三维结构,从而为再现被测物体的超声全息图奠定了基础;第三,与采用其它方法的机器人眼睛系统相比,超声波系统最为廉价和简单。 相似文献
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微波热致超声成像技术通过向物体发射微波脉冲, 导致物体吸收电磁波温度迅速升高, 产生瞬时压力波, 从而激发产生超声波信号, 通过传感器对产生的超声波信号进行采集并成像, 最终还原了反映物体吸收电磁波能量特性的图像, 由于此方法兼具了微波成像的高对比性和超声成像的高分辨率特点, 理论上验证了热声成像技术对早期乳腺肿瘤检测的可行性. 本实验兼顾系统成像深度和分辨率, 采用S波段的微波脉冲信号源对物体进行辐射, 利用圆形扫描方式对待测物体进行检测, 同时为了更好的验证成像性能, 本实验同时使用了肿瘤仿体及实际生物组织进行成像实验. 通过实验分析, 验证了该系统对肿瘤仿体和生物组织检测的有效性, 以及系统的高分辨率和高对比度特性, 为早期乳房肿瘤检测提供了进一步的理论支撑. 相似文献
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显微物镜的景深问题限制数字显微全息在大纵深视场中的应用. 本文充分利用数值重建的特点, 采取低频和高频系数子图上的最大亮度梯度的局部方差作为聚焦判据, 在小波分解域内对显微全息重建图像的景深扩展问题进行了研究. 对倾斜的连续物体碳纤维进行三维重建, 分析了重建距离与直径测量误差的关系. 以超声波雾化器生成的微液滴颗粒场为例, 对离散颗粒场的重建图像进行了景深扩展. 利用基于广义洛伦兹-米散射理论的模型分别模拟1-15 μm 的非透明与透明离散颗粒的显微全息图, 分析了该方法重建的颗粒场的纵深定位误差与夫琅禾费系数的关系, 对比了非透明与透明颗粒纵深定位误差的异同点. 实验和模拟结果显示出该方法对于连续物体和离散颗粒场的显微全息重建图像的景深扩展能力, 且能由此准确重建物体信息. 相似文献
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磁致伸缩超声波检测器可用于检测直线移动物体的位置,这是通过超声波传播的时间来计量的.它具有非接触计量的优点.由于超声波传播速度随温度变 相似文献
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设计了演示中心力场作用下物体运动的实验装置,利用圆形磁铁产生的磁场模拟了中心力场,力心的位置和数量可以改变,利用可磁化的金属球模拟运动物体,采用高速摄像机拍摄并用视频分析软件提取物体运动轨迹和速度.基于该装置获得的单中心和双中心力场中物体的运动情况与数值计算得到的结果相吻合. 相似文献
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A method of obtaining ultrasonic images of objects radiating ultrasonic acoustic waves in the air is proposed. Object images are retrieved by spatially matched filtering of the amplitude-phase distribution of the ultrasonic field measured in a planar rectangular region at a distance from the radiating object under investigation. The field is measured at different frequencies in a wide band, which allows one to reduce the level of noise and artifacts in the retrieved images by processing in a wide frequency band. 相似文献
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Cheng-Fu Yang 《中国物理 B》2022,31(8):84101-084101
Reusable reciprocal invisibility and phantom device is proposed and designed based on multi-folded transformation optics and equivalent components. In comparison with the reported reciprocal invisibility cloaks, the material parameters of the device presented here are homogeneous, and the hiding of the target object does not require any "anti-object" at all, which dramatically breaks through the limitations of the "anti-object" design in previous reciprocal cloak design. Perfectly illusion effect is also found by reasonably setting the material parameters of the restored medium of the device, which can be used to confuse detection radars while hiding target objects. Last but not least, the proposed device has an open structure, which enables the target object enclosed by the device to perform material exchange and simplex transfer of information with the outside world through open channels. In other words, the proposed device has a reusable function, enabling stealth or phantom of new target objects without changing any parameters of the device. 相似文献
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Images of optically inhomogeneous objects immersed into a cell with a scattering liquid through which orthogonal laser and ultrasonic beams pass are obtained upon measuring the scattered light modulated at the ultrasonic frequency. The alternating current from a photodetector recording the optical radiation emerging from the cell was used as a parameter of the acousto-optic visualization. The quality of the visualization is analyzed in relation to the registration conditions and the scattering parameter magnitude, as well as the size and shape of three-dimensional and planar objects. Under the experimental conditions used, the positions of objects immersed into the scattering liquid are detected fairly precisely, with a satisfactory contrast and sharpness of images in the plane perpendicular to the laser beam axis, whereas, along this axis, the object positions are not determined. The experiment was performed under conditions of transition from a regime without scattering to a regime of multiple scattering. 相似文献
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The main component of every device used for investigating internal object structure by Ultrasound Transmission Tomography (UTT) is a special ultrasonic probe. This paper presents the structure of model multielement ring probe for examining objects using this method in divergent ray projection geometry. The probe is made up of 1024 rectangular separate piezoelectric transducers working at frequency f=1.7 MHz, placed inside a ring with diameter D=30 cm and height h=9 cm. Each element of the probe is equipped with a quarter-wave matching layer. All the transducers function as transmitters and receivers, and can be joined in groups both during transmitting and during receiving. Some examples of admittance characteristics of a single piezoelectric transducer and examples of shapes of pulses generated and received by particular transducers were presented. Important factors affecting the measurement resolution are the sizes of the active surface of the transducers. 相似文献
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Nomura S Matula TJ Satonobu J Crum LA 《The Journal of the Acoustical Society of America》2007,121(3):1332-1336
A noncontact transport experiment in water using ultrasonic traveling waves was investigated. Acrylic, aluminum, and brass discs were used as test objects. Traveling waves were generated using two ultrasonic transducers attached at the ends of a vibrating plate. One side was used as the wave-source side and the other side was used as the wave-receiving side. Acrylic plates cemented to the sides of the vibrating plate formed a tank to hold water. Object transportation was accomplished by adding a small amount of water to the vibrating structure. The transport velocity of floating objects in water is faster than for floating transport in air because of buoyancy. The transport velocity of an object depends on water height. The minimum value of the velocity occurs when the disc thickness is equal to the water height. The transport velocity increases as the height of water increases. For very shallow depths, the largest velocity is obtained when cavitation-induced streaming occurs. 相似文献
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An underwater ultrasonic imaging system has been developed which can display the C-mode picture on a cathode ray tube in real time. The system contains a coaxial circular spherical array of 24 hydrophones and an analogue delay device developed for electronic scanning and focusing. The array has high directional sensitivity resulting from the additive, precision limiter and multiplicative processes. Experimental study on imaging an object located at 3 m from the array and irradiated with an ultrasonic wave of about 95 kHz has successfully been carried out in a water-filled tank. 相似文献
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D.W. Schindel 《Ultrasonics》1998,35(8):587-594
A variety of small solid objects have been imaged in atmospheric air using a focussed, micromachined air-coupled capacitance transducer. The transducer, which was capable of generating and receiving ultrasound in air over a large frequency bandwidth (< 100 kHz 1.5 MHz) was employed in a pulse-echo arrangement such that generated waves reflected off the surface of the object before returning to the same transducer for detection. By raster scanning the transducer in a plane and recording the detected ultrasonic echo amplitude as a function of transducer position, images of object surfaces were obtained. As the transducer had been fitted with a micromachined Fresnel zone-plate, the ultrasonic waves could be focussed to a spot-size of 680 μm so as to provide images of high lateral resolution. One of the key factors in making the Fresnel zone-plate function effectively in these imaging applications involved the inclusion of a second aperture in front of the zone-plate. This additional aperture blocked the zone-plate's side-lobes and reduced the appearance of multiple (diffracted) images. 相似文献
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Measurements of the sound absorption coefficient in test objects containing solid microparticles randomly distributed over the object volumes are carried out. Two methods are used for this purpose: the standard echo-pulse insert-substitution method and a modified method using phase conjugation of ultrasound. The test objects are made from gelatin, and the size of the particles introduced in it is chosen to allow measurements in both the long- and medium-wavelength scattering modes of the probing beam. It is shown that, in the first scattering mode, in which the presence of particles causes additional viscous and temperature losses, the two aforementioned methods give identical results. In the second scattering mode, in which the dominant mechanism of additional loss is elastic scattering, the use of phase conjugation allows an almost complete reconstruction of the scattered field and, hence, a more reliable upper estimate for the coefficient of ultrasonic absorption in the test objects. 相似文献
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为借助激光全息进行无损检测,获得位相物体的信息,对位相物体激光全息二次曝光法无损检测进行了研究,指出一般的二次曝光法测位相物体典型光路的缺点,提出了物光波2次通过样品的改进方案。利用此方案对一些位相物体(如普通玻璃和有机玻璃)作了无损检测实验,得到了较满意的实验结果。与普通检测方法相比,该方法具有精度高、结果直接可靠、不损伤物体等诸多优点。对改进方案稍作改动,即可用于塑料制品和玻璃制品生产线对加工产品进行在线产品质量监控。 相似文献