A transmission near real-time digital holographic microscope with in-line and off-axis light path is presented, in which the parallel computing technology based on compute unified device architecture (CUDA) and digital holographic microscopy are combined. Compared to other holographic microscopes, which have to implement reconstruction in multiple focal planes and are time-consuming the reconstruction speed of the near real-time digital holographic microscope can be greatly improved with the parallel computing technology based on CUDA, so it is especially suitable for measurements of particle field in micrometer and nanometer scale. Simulations and experiments show that the proposed transmission digital holographic microscope can accurately measure and display the velocity of particle field in micrometer scale, and the average velocity error is lower than 10%.With the graphic processing units(GPU), the computing time of the 100 reconstruction planes(512×512 grids） is lower than 120ms, while it is 4.9s using traditional reconstruction method by CPU. The reconstruction speed has been raised by 40 times. In other words, it can handle holograms at 8.3 frames per second and the near real-time measurement and display of particle velocity field are realized. The real-time three-dimensional reconstruction of particle velocity field is expected to achieve by further optimization of software and hardware. Keywords: digital holographic microscope,
In the last years, several techniques have been developed for the measurement of the three velocity components in a fluid plane or volume.Digital holography particle tracing velocimetry(DHPTV)was applied to observe the chain transformation process of magnetorheological fluids (MR fluids) under an external magnetic field. With the help of correlation coefficient(CC)method, the focus plane of standard particle target was determined. The displacement of standard target mounted on a precise displacement measurement workbench was compared with the distance measured by difference of focal planes movement. Making use of a controlled rotating platform with constant revolving speed, the rotation speed of particles was obtained after extracting the coordinates from reconstruction images. The measured speed was compared with actual speed of particles,which can be worked out through rotation speed of platform. The transformation speed was measured when magnetic particle moved along with magnetic direction under an external magnetic field. The experiments showed that a visible part of 3D velocity field could be observed in the chain transformation process of MR fluids with DHPTV.
A new space and time resolved focusing elliptical curved crystal spectrometer has been developed and applied to
diagnose X-ray of laser-produced plasma in 0. 2~2 nm region. According to the theory of Bragg diffraction, four kinds
of crystal including LiF, PET, KAP, and MiCa were choosed as dispersive elements.The distance of crystal lattice
varies from 0.4 to 2.6 nm. Bragg angle is in the range of 30°~67.5°, the spectral detection angle is in 55.4°~134°. The
dispersive crystal sizes are 120×8×0.2mm.The characteristic of optical system is an elliptical geometry.The X-ray
source is located at the front focal point.The X-rays diffracted by the elliptically curved crystal are focused at the rear
focal point where a width-adjustable exit slit is positioned.The Curved crystal spectrometer mainly consists of dispersive
elements, vacuum configuration, aligning device, spectral detectors and three dimensional (3D) micro-adjustment
devices. The spectrographic experiment was carried out on the XG-2 laser facility.The PET and KAP crystals are
adopted as the dispersive elements,which measure X-ray in the 0.44~0.81 and 1.33~2.46nm region. Emission
spectrum of Al plasmas and Ti plasmas have been successfully recorded by using X-ray CCD camera. It is demonstrated
experimentally that the measured wavelength is accorded with the theoretical value. At the same time, experimental
result shows that spectral resolution of PET and KAP crystals is 956 and 1123.
Blood pressure reflects a person's health.It is proposed here that the method of detecting blood pressure may be the key to improving the precision of blood pressure measurements. The oscillometric blood pressure measurement technique is widely used in automatic blood pressure measurement instruments correctly. A method of blood pressure measurement by oscillometric method is first presented. In the oscillometric method, the basic principle of the "feature point" method and the "amplitude characteristic ratios" method is also explained and discussed here. A new method of blood pressure measurement, namely the coefficient difference comparative method, is proposed here,which is based on the feature point method and amplitude characteristic ratios method. The method is proved both effective and reliable through the analysis of many cases and clinical tests. Utilizing Visual C++, software for this new and novel method was developed and passed criterion simulation apparatus test. When applied in hospital situation, its error was ±5%. It is concluded that the oscillometric blood pressure measurement method can provide better means of blood pressure measurements reference for doctors.
The shape of rubber biaxial tensile specimen and the forms of specimen holding and the specimen holder were discussed. The mechanics characteristics of biaxial rubber tensile was correlated with the rubber fibre direction and loading direction. The rubber hardens or softens along with the load changing. The displacement transmutation percentage and the modulus of 50% maximum displacement are important parameters for biaxial tensile rubber. The failures of biaxial rubber tensile are correlated with the maximum shearing stress.