船用超声液位传感器的分析与设计

介绍了一种船用某型超声液位传感器的基本结构和工作原理。在对脉冲式超声探头的轴向声压分布特点及其声透射强度分析研究的基础上,给出了该传感器的超声信号发射端与接收端之间距离d和压电晶片保护膜的壁厚δ值的确定方法。最后设计了一套超声液位传感器性能测试实验平台,对上述理论研究结论进行了实验验证。     

Dynamical process of cavitation bubble adsorbed in gold nanoparticle under combined irradiations of laser and ultrasound

Under combined irradiation of laser and ultrasound,cavitary bubbles are generated on the surface of gold nanoparticle.The laser-induced thermal effect,ultrasonic cavitation effect and the synergistic effect of laser and ultrasound are studied by means of the investigation of the dynamical process for the vibration of the cavitation bubble,with different external conditions such as laser power,ultrasound intensity,etc.It is found that dynamical process of the cavitation bubble can be modified by the irradiation of laser or ultrasound.The enhancement of laser power can increase the critical radius of the cavitation bubble,while that of ultrasound may intensify the vibration.Cavitation bubble may become more stable due to the synergistic effect of laser and ultrasound.It is also found that variation of the coupling between laser and ultrasound can affect synergistic effect.     

Characterizing the properties of ultrasonics propagating on the surface of materials with defect by Laser-ultrasonics method

A laser ultrasonics method is used to characterize the propagation properties of surface wave traveling on the surface of materials with sub-surface defect in 2D.Linear and nonlinear propagation properties of ultrasonics caused by the defects have been detected in experiment. A theoretical model is proposed and used to study the linear and nonlinear properties of ultrasonics caused by the defect.The numerical results indicate that the nonlinear ultrasonic wave will be excited when a finite amplitude ultrasonics propagates on the surface of materials with sub-surface defect.The theoretical analysis confirms that the nonlinear wave is caused by the "clapping"of the interface of defect instead of the mode conversions of ultrasonics.     

Analysis of ultrasonic guided waves propagating in long bones and cortical thickness based on time-frequency methods

The ultrasonic signals in long bones contain multiple guided modes which are mutual superposed.The velocities of guided waves in long bones are very sensitive to cortical thickness (CTh).In this paper,Hilbert-Huang transform(HHT) was proposed to analyze multi-mode guided waves,which can decompose superposed waves into many independent modes.Then the group velocity of each mode was obtained at corresponding frequency,which was compared with the results of short time Fourier transform(STFT).The CTh was also obtained by comparing with the theoretical calculation.The results showed that the experimental determined thickness was in agreement with the actual CTh,indicating that measuring the velocity of the guided mode can be used to estimate the CTh.The HHT is an effective method to identify multimode guided waves.     

第15届固态传感器、传动器与微系统国际会议(Ⅱ)

本届会议的专题报告按日程安排分述如下:(1)T Wacharalindu:以液态半导体为基础的微功率源--采用反射能量转换;(2)C M Waits,MMc Carthy,R Ghodea:供小规模动力系统中输送燃料用的、微电动机械系统的涡轮泵;(3)I D Block、P c Mcthals、M Ganoch:增强荧光与无标记成像联用仪;(4)L H Loo、Y D Lau:应用微结构的流体动力学偶联方法进行微型悬臂的质量因子的调谐;(5)K Imagawa,H Horilauchi,K Ikoda:应用心脏肌肉细胞的药物模拟方法的自给加热与流体泵送凝胶;(6)N Suhkl:供模拟在任何硅取向的表面组织与几何形态用的连续分格自动化技术.     

怎样选用元器件讲座（二十九）：超声波传感器

超声波传感器是常用的敏感器件之一。是测距、遥控、报警常用的探头,为家庭电子爱好者所青睐。超声波传感器由外壳、屏蔽网、支架、基座、激励器、谐振片、引线等构成。超声波传感器常见型号有T/R40—12、T/R40—16、T/R40—18A、T/R40—24A等。图1给出了T/R40—16型的频率特性曲线。由图1可知,其声压能级、灵     

用ADuC812设计超声波非接触液位计

本文阐述了超声波非接触液位计测量的原理，给出了硬件电路和软件编程的设计方法，对其应用也作了简单介绍。     

诊断用超声波设备更小、更快、更有用

超声波机器中的信号路径是一个多信道收发系统，数据速率快得令人瞠目。工程师们在设计这些复杂机器时，需要权衡众多选项。     

佳能24mm F1.4LⅡ USM

全幅绝配广角定焦 和EOS 5D MarkⅡ一起发布的，还有一支全新的L镜阵营新成员，这支24mm F1．4LⅡ USM定焦红圈头由10组13枚镜片组成，包括两片高精度非球面镜片和两片UD镜片，USM超声波马达让对焦平稳而迅速。同时，因为采用了佳能SWC技术，镜头能够有效地控制重像和色散，