The timing jitter measurement scheme for low repetition rate pulse train is proposed. Measuring a spectrum of upconverted light generated from frequency mixing with a transform limited reference pulse and a linear-chi...
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ISBN:
(纸本)0819430862
The timing jitter measurement scheme for low repetition rate pulse train is proposed. Measuring a spectrum of upconverted light generated from frequency mixing with a transform limited reference pulse and a linear-chirped amplified pulse, a relative time lag between two pulses can be obtained. The measurable range and resolution with this method are discussed.
Liquid velocity and direction were measured by an electrochemical probe. The probe had three microelectrodes, and the two-dimensional direction and velocity were calculated from a cross-correlation function of the vol...
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Liquid velocity and direction were measured by an electrochemical probe. The probe had three microelectrodes, and the two-dimensional direction and velocity were calculated from a cross-correlation function of the voltage fluctuations. Measurements were done in a rotating basin, and the most suitable values of parameters-the distance between the electrodes and the time span of calculating the cross-correlation function-were decided. This probe can be constructed cheaply, and it can be used in dilute aqueous solutions of sodium chloride (0.01 M) and also mediums for cultivation of microorganisms without employing commonly used electrolytes such as ferricyanide.
The conventional, autocorrelationmethod (AM) to estimate the blood velocity for color flow imaging (CFI) is based on the phase estimation of the autocorrelation function, In this paper, a new extended autocorrelation...
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The conventional, autocorrelationmethod (AM) to estimate the blood velocity for color flow imaging (CFI) is based on the phase estimation of the autocorrelation function, In this paper, a new extended autocorrelationmethod (EAM) that uses both phase and magnitude of the two dimensional (depth and temporal direction) autocorrelation function for estimating the blood velocity is presented, It is shown that the EAM has similar performance as the cross-correlation method (CCM), Both of them have smaller estimation variance than the AM and have the ability to estimate velocities beyond the Nyquist velocity, but the EAM is more computationally efficient than the CCM, A 2-D blood flow signal with rectilinear velocity including the transit time effect has also been simulated and the results are presented in this paper, For comparison, the EAM and the CCM have been applied to the simulated signals in which the flow velocities are up to four times the Nyquist velocity, The EAM has been further verified by experimental RF data from the subclavian artery.
We report here for the first time, preparation of the ilmenite titanate MgTiO3 thin films on Si and SrTiO3 substrates by atmospheric pressure metalorganic chemical vapor deposition (APMOCVD) technique. Magnesium acety...
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We report here for the first time, preparation of the ilmenite titanate MgTiO3 thin films on Si and SrTiO3 substrates by atmospheric pressure metalorganic chemical vapor deposition (APMOCVD) technique. Magnesium acetylacetonate [Mg(acac)(2)] and titanium isopropoxide [TIP] were used as the Mg and Ti precursors, and O-2 was the oxidizing gas. The deposited films were investigated using scanning electron microscopy, X-ray energy dispersion analysis and X-ray diffraction technique. The experimental results showed that the films deposited on silicon substrate were single-phase randomly oriented MgTiO3, and on SrTiO3 substrate, only a (012) orientation was observed. The MgTiO3 films, prepared on SrTiO3(100) substrates at a growth temperature of 650 degrees C, were transparent in the visible and exhibited a sharp absorption edge at 380 nm in the ultraviolet. The birefringence of the MgTiO3 films was also measured at room temperature by the cross-correlation method.
An experimental study investigating the cyclic variation of the internal air motion has been conducted in a motored engine having a cup-in-piston combustion chamber. The engine used for this study has a transparent qu...
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An experimental study investigating the cyclic variation of the internal air motion has been conducted in a motored engine having a cup-in-piston combustion chamber. The engine used for this study has a transparent quartz liner and a transparent acryl piston. The continuous wave beam of a 4 watt argon ion laser was formed into a thin light sheet to define the measurement plane. The scattered light from the particles which were supplied to the intake air stream, were recorded by a NAC E-10 highspeed camera and the bulk flow fields inside the combustion chamber were measured at planes parallel and perpendicular to the piston crown by means of an image processing technique. We reveal, for the first time, continuous cycle-resolved two-dimensional bulk flow fields inside the combustion chamber around the compression TDC. Also, comparison between cycle-resolved and ensemble-averaged flow patterns has shown that the latter may become artificial ones if there exists a strong effect of cyclic variation. Moreover, by examining the rms of the variation component and the ratios of the rms to ensemble-averaged velocity with and without swirl, it is found that the ratios of the rms to ensemble-averaged velocity can be used for evaluating the effect of the cyclic variation on the how fields.
The present study proposes a new method of particle identification in three-dimensional particle-tracking velocimetry (3D PTV) using binary image data. It is based on the necessary condition for particle identificatio...
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The present study proposes a new method of particle identification in three-dimensional particle-tracking velocimetry (3D PTV) using binary image data. It is based on the necessary condition for particle identification and the 3D cross-correlation method for evaluating the similarity of particle distribution patterns in two spaces. Computer simulations are carried out to investigate the effects of the sizes of particles, search subregion and identification subregion on the particle identification performance. The method has two key advantages. One is quick and accurate particle identification performance and the other is that the computer memory required for the computation of particle identification is generally small compared to other methods.
One-dimensional propagation characteristics of the plasma disturbance which originates from the temperature disturbance at the inlet of a linear-type magnetohydrodynamic (MHD) channel were analysed numerically. It was...
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One-dimensional propagation characteristics of the plasma disturbance which originates from the temperature disturbance at the inlet of a linear-type magnetohydrodynamic (MHD) channel were analysed numerically. It was shown that the temperature fluctuation propagates with two different speeds. One is the mean flow convection speed and the other is the acoustic plus convection speed. Both waves appeared at the same time when a single-pulse temperature disturbance was induced adiabatically at the channel upstream. By contrast, the velocity wave excited inside the channel always propagates with the latter speed.
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