共查询到20条相似文献,搜索用时 0 毫秒
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Zaitsev B.D. Ermolenko A.V. Fedorenko V.A. Kalinin V.Y. Kuznetsova I.E. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1996,43(1):30-35
A microwave electric field intensity meter for single high-power radiowave pulses is described. A surface acoustic wave (SAW) dielectric acoustic line is used which has nonlinear electroacoustic properties and is comprised of two transducers. The first (nonlinear) transducer is affected by a microwave electric field and provides the SAW excitation due to nonlinear effects. A delayed SAW signal, carrying information about the electric field strength, is received by a linear interdigital transducer 相似文献
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Ken Xu Bingxin Jie 《IEEE transactions on instrumentation and measurement》1997,46(5):1081-1083
A two-core feedback-controlled transductor for measuring large dc currents is presented. It is capable of measuring bidirectional dc currents with the accuracy of 100 ppm and of returning to its normal operating condition once it is stuck in the false balance state. It can be applied to the situation in which the abrupt jumps of the busbar current take place frequently 相似文献
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O. D. Bychkov 《Measurement Techniques》1967,10(12):1461-1464
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Precision ranger for measuring large mechanical components 总被引:3,自引:0,他引:3
We present a precision laser ranger system for the measurement of large manufactured components and structures. The system was developed based on a beat-wave interferometry principle. The light source of this system is a frequency-stabilized laser with a frequency stability of 1 x 10(-7) (in open air) or 10(-8) (in the laboratory). The laser operates in two longitudinal modes, and the two modes are generated in common resonator; therefore the two beams are naturally coaxial. The precision ranger system does not need a long guide or any heavy machinery. In this system an adaptive filter and a wavelet-transform program are used to improve the measurement accuracy. The system described here has a measuring range of 0-20 m and a measuring uncertainty of 30 microm/10 m. 相似文献
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J. Gonzalez-Molina J. Riegler P. Southern D. Ortega C. C. Frangos Y. Angelopoulos S. Husain M. F. Lythgoe Q. A. Pankhurst R. M. Day 《Journal of the Royal Society Interface》2012,9(76):3008-3016
Delivery of cells into tubular tissue constructs with large diameters poses significant spatial and temporal challenges. This study describes preliminary findings for a novel process for rapid and uniform seeding of cells onto the luminal surface of large tubular constructs. Fibroblasts, tagged with superparamagnetic iron oxide nanoparticles (SPION), were directed onto the luminal surface of tubular constructs by a magnetic field generated by a k4-type Halbach cylinder device. The spatial distribution of attached cells, as measured by the mean number of cells, was compared with a conventional, dynamic, rotational cell-delivery technique. Cell loading onto the constructs was measured by microscopy and magnetic resonance imaging. The different seeding techniques employed had a significant effect on the spatial distribution of the cells (p < 0.0001). The number of attached cells at defined positions within the same construct was significantly different for the dynamic rotation technique (p < 0.05). In contrast, no significant differences in the number of cells attached to the luminal surface were found between the defined positions on the construct loaded with the Halbach cylinder. The technique described overcomes limitations associated with existing cell-delivery techniques and is amenable to a variety of tubular organs where rapid loading and uniform distribution of cells for therapeutic applications are required. 相似文献
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Conclusions The above instrument was used for the first time in 1959 for measuring leakage currents in electrolyte jets at two plants. Over 300 measurements were made [4]. The insrument was calibrated before each set of measurements (10 times during 6 months) without observing any deviations in it.Designed on the principle of a magnetic amplifier, the inrument provides measuremens of small dc currents in electrolyte jets and suitable for production conrol of leakage currents in operating elecrolytic installations. It can also be adapted for measuring direct currents in electrolyte jets under different conditions.The insrumen is of a relatively small size and is simple to use. 相似文献
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R. Klein S. Jacquey 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,236(1):117-122
This report describes a new method for measuring fast high voltage electric pulses based on one particular application of the Kerr effect. This work was carried out in order to further the development of optical particle detectors. At the present time with our method, the minimum risetime of the measured pulse reaches the nanosecond domain while the maximum voltage is limited only by the physical dimension of the electro-optical transducer.The measuring principle chosen requires a new calibration method in order to reconstruct the observed signal.The use of nitrobenzol as the active liquid allows the continuous modification of the cell sensitivity over a ratio of 1 to 3 without changing the geometry of the cell. 相似文献