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2003年2月27日由国家药品监督管理局医疗器械司委托全国医用电器标准化技术委员会组织,在上海市举行了SJTU-1型医用超声设备声输出测量系统的技术成果鉴定会。由王威琪院士、冯若教授、张德俊教授为主任委员的鉴定委员会,对此项成果进行了测试和技术鉴定,认为SJTU-1型医用超声设备声输出测量系统的技术指标达到了同类系统的国际先进水平,某些功能优于国外同类系统。 相似文献
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国家药品监督管理局委托全国医用电器标准化技术委员会,于2003年2月27日主持对上海市医疗器械检验所委托上海交通大学研制的SJTU-1型医用超声设备声输出测量系统,进行了技术鉴定。鉴定会委员审阅了全部有关资料、认真听取了研制组负责人寿文德教授所作的研制报告和测试组提供的测试报告,并现场参观了该测量系统的实际操作与测量。通过认真讨论,取得如下一致鉴定意见。 1 SJTU-1型声输出测量系统的研制成功,对于贯彻超声诊断设备声输出的国家标准(与国际标准同)具有重要意义。 相似文献
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利用声致发光成像技术的液体中超声场动态分布的实时测量方法 总被引:4,自引:0,他引:4
根据超声空化原理,运用声致发光成像技术测量超声在液体中的动态分布。利用高灵敏度的ICCD成像系统记录水在超声作用下的声致发光图像,并且分析了声致发光的分布和强度与作用超声的关系。结果表明,超声作用下的发光图像能够反映该作用超声在水中的分布情况,从而提出利用声致发光成像技术测量液体中超声场的分布是一种动态测量声场强度的新方法。 相似文献
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复杂流场的超声-激光测量原理研究 总被引:1,自引:1,他引:0
本文从复杂流场—旋涡场参量的超声—激光测试方法的需要出发,论述了超声波产生的声相位光栅对激光产生的偏转效应.并研制了适用于产生空气超声相位光栅的大功率高频超声换能器、位移灵敏接收器、数字相位差测定仪等设备,采用了超声发射的匹配技术等,从而获得了明显的空气超声-激光偏转效应,并且测定了两光束的偏转时间差.本文的结果为利用超声-激光的空气声光偏转效应测量空气旋涡流场参量提供了实验依据. 相似文献
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超声吸收体的物理参数对利用水听器和红外热成像技术的高强度聚焦超声(High-Intensity Focused Ultrasound,HIFU)声场测量结果具有重要影响。为了探索超声吸收体的物理参数(密度、声速、衰减系数、热扩散系数、定压比热容)对测量结果的影响规律,本文根据层状模型计算出相同声源功率输出时不同物理参数对应的超声吸收体内部声场和热场,利用有限差分法计算出超声吸收体表面在辐照过程中的温度变化;利用基于水听器和红外热成像技术的聚焦声场测量方法测量出焦域内不同位置上声场特征值(轴线声强和-6 dB声束宽度),与通过理论计算得到的声源在纯水中声场特征值进行比较,分析了不同物理参数对测量结果的影响。超声吸收体的声、热学参数中除了声速外,其它物理参数的变化引起声场特征值的测量造成最大相对差异率小于15%。因为声波传播速度的改变会导致超声吸收体内部热场分布变化,使测量结果与理论计算值有较大偏差,其中-6 dB声束宽度和轴线声强最大相对差异率为95.37%和69.97%。因此在选择超声吸收体的声、热学参数时应重点关注声波在吸收体内声速的影响。超声吸收体的声学参数与水的声学参数相近时,可以在焦域内获得较好的测量结果。 相似文献
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用脉冲光声技术测量吸收系数 总被引:1,自引:1,他引:0
建立了由YAG激光器和超声探测器组成的利用脉冲光声技术测量样品吸收系数的实验系统,通过对测量的光声信号的拟合,可以计算出样品的吸收系数.用染色的琼脂进行了实验验证,测量误差为-5.2%~4.8%. 相似文献
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针对火车车轮检测中常规超声波探伤存在的检测灵敏度低、声束灵活性差、信噪比低等问题,研究了超声相控阵在火车车轮轮辋检测中的应用。本文介绍了超声相控阵检测技术的原理,并从超声相控阵换能器、硬件系统和软件系统三个方面阐述了火车车轮轮辋缺陷的超声相控阵检测系统的研究过程。最后通过人工模拟缺陷的相控阵检测实验,测试了该检测系统的性能,验证了相控阵检测设备具有灵敏度高、声束可控性好和可靠性高等优点。 相似文献
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FAN Li ZHANG Shuyi WANG Benren 《声学学报:英文版》2007,26(2):180-192
Piezoelectric loudspeakers have been used in thermoacoustic refrigerators for operating at the high frequency to miniaturize the system. Then the coupling between the piezoelectric loudspeaker and resonance pipe becomes an important factor for improving the performances of the system. By the equivalent circuit model, the expressions of the acoustic output power and electroacoustic transfer efficiency at a low operating frequency are obtained, and then the structures of the piezoelectric loudspeaker and resonance pipe, as well as the operating frequency, are optimized to achieve a high electroacoustic transfer efficiency and a large acoustic output power. It is also shown that when the total reactance of the system equals zero, the resonance frequency of the resonance pipe is the optimized operating frequency and a high acoustic output power can be achieved. However, the highest transfer efficiency and largest acoustic power cannot be obtained simultaneously, therefore a trade-off condition must be adopted. 相似文献
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Muhammad Taher Abuelma’atti 《Applied Acoustics》2007,68(6):616-627
A mathematical model for the open-circuit output voltage of a micromachined silicon condenser microphone with a single deeply corrugated diaphragm as a function of the applied acoustic pressure is presented. The model, basically a sine-series function, can easily yield closed-form expressions for the amplitudes of the output components resulting from a multisinusoidal input acoustic pressure. The special case of an equal-amplitude two-tone acoustic pressure input is considered in detail. The results show that the microphone generates only odd-order harmonic and intermodulation products. The results also show that the amplitudes of these components are strongly dependent on the microphone parameters, the corrugation depth and the ratio between the half-length of the diaphragm and its thickness. Moreover, the results show that the acoustic pressure required to produce a pre-specified output open-circuit voltage is strongly dependent on these parameters. 相似文献
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《声学学报:英文版》2016,(2)
The general corrosion and local corrosion of Q235 steel were tested by acoustic emission(AE) detecting system under 6%FeCl_3-6H_O solution to effectively detect the corrosion acoustic emission signal from complex background noise.The short-time fractal dimension and discrete fractional cosine transform methods are combined to reduce noise.The input SNR is 0~15 dB while corrosion acoustic emission signals being added with white noise,color noise and pink noise respectively.The results show that the output signal-to-noise ratio is improved by up to 8 dB compared with discrete cosine transform and discrete fractional cosine transform.The above-mentioned noise reduction method is of significance for the identification of corrosion induced acoustic emission signals and the evaluation of the metal remaining life. 相似文献
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G. Kossoff 《Ultrasonics》1969,7(4):249-251
The peak acoustic intensity generated by pulsed ultrasonic equipment is calculated from measurement of the transmitted acoustic pulse by a calibrated, small, high frequency transducer. The average acoustic output is then computed from the intensity waveform, the beamwidth and the pulse repetition rate. Alternatively, the acoustic pulse may be measured by an uncalibrated transducer and the intensity is then computed from the average acoustic output. 相似文献
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水声通信中后验符号概率密度分布及概率成形容量分析 总被引:1,自引:0,他引:1
考虑到实际水声信道复杂特性对水声通信的影响,对系统的通信容量进行计算分析,并研究了一种适用于水声信道的容量评估算法。文中通过对不同条件下的均衡器输出的后验符号特性进行统计分析,提出了一种基于后验高斯分布的符号方差分段转移函数模型。在此基础上,采用Maxwell-Boltzmann分布来改变均衡器输出符号的成形分布,即引入概率成形技术对实际的水声通信系统容量进行评估分析。最后通过对水池和湖试多径信道数据的处理,获得了不同调制方式下的通信容量。结果显示,在特定的信噪比区间内,概率成形技术比传统的等概率映射的容量提升最大可达0.5 bits/symbol。 相似文献
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The acoustic energy output of a magnetostrictive transducer unit has been observed by the calorimetric method. The object was to observe the energy output of the unit from low to high ultrasonic intensities under identical conditions of transducer frequency and acoustic load. The design and construction of the calorimeter and its mode of operation are discussed in some detail. 相似文献
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受限于加工工艺,目前多数的声表面波微流控芯片,主要依靠普通的直通道调节细胞流速,从而控制微球在通道中的排列。但其形成的声场通常无法满足低能量、多功能的微流控需要。本文在普通声表面波微流控芯片的基础上,分别在频域和时域内构建声学微结构,并改变微结构阵列中铜柱间距,模拟仿真了微流控芯片输出端的电势,发现其输出端电压得到了明显的改善。当输入电信号频率在0-30MHz时,输出端电势增加约0.25V;在0-1000ns内,输出端电势增加0.015V左右;进而可以探索开发性价比更高的声波微流控芯片,针对病理检测等所存在的问题进行分析优化,提出新的细胞分离等技术。 相似文献
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A set of narrowband tones (280, 370, 535, and 695 Hz) were transmitted by an acoustic source mounted on the ocean floor in 10 m deep water and received by a 64-element hydrophone line array lying on the ocean bottom 1.25 km away. Beamformer output in the vertical plane for the received acoustic tones shows evidence of Doppler-shifted Bragg scattering of the transmitted acoustic signals by the ocean surface waves. The received, scattered signals show dependence on the ocean surface wave frequencies and wavenumber vectors, as well as on acoustic frequencies and acoustic mode wavenumbers. Sidebands in the beamformer output are offset in frequency by amounts corresponding to ocean surface wave frequencies. Deviations in vertical arrival angle from specular reflection agree with those predicted by the Bragg condition through first-order perturbation theory using measured directional surface wave spectra and acoustic modes measured by the horizontal hydrophone array. 相似文献
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Environmental implications of acoustic aerosol agglomeration 总被引:2,自引:0,他引:2
Hoffmann TL 《Ultrasonics》2000,38(1-8):353-357
An overview is presented of acoustically induced agglomeration of fine particulates, potential industrial applications of the technology, and its environmental implications in terms of fine particle pollutants. Adverse health effects due to exposure to fine aerosols are discussed as well as recent legislation to reduce the output of such emissions. Based on this, the need for new, more efficient particle filtration technologies is demonstrated. It is shown that acoustic aerosol preconditioning meets all the requirements to reduce the fine particle output of conventional filter systems. The results of laboratory scale experiments are presented to illustrate the underlying mechanisms of the acoustic agglomeration process, while data from pilot scale testing are shown to prove the effectiveness of acoustic agglomeration systems in reducing the fine particle content of aerosols. Other filtration technologies are compared with acoustic agglomeration equipment. 相似文献
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An influence of acoustic wave diffraction on the modulation instability of the backward stimulated Brillouin scattering in fibers is numerically investigated, when a small feedback for the Stokes wave is present. The cases of acoustic waveguide and anti-waveguide fibers are considered. It is shown that a presence of acoustic diffraction may expand the region of occurrence of modulation instability and may lead to 2–5 times increasing the peak amplitude of output Stokes pulses. In this case, a stable train of short powerful Stokes pulses of nanosecond duration is produced at the output. 相似文献