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EN
The study of the flow characteristics of the solid-fluid two phase flow in the cutter suction dredger is very important for exploring the slurry formation mechanism and optimizing the operational parameters. In this study, standard k-ε model and Multiple Reference Frame are applied to numerically simulate flow field in and around the cutting system, then with the steady convergent result of the simulation as the initial condition, Discrete Phase Mode is used to solve the particle motion equation by fully coupling the continuous phase and the particles . The influence of suction flow velocity and cutter’s rotating speed on particles suction are analyzed, and effectively suctioned particles numbers are also quantitatively studied. The simulation result shows that the DPM model is able to simulate the movement of particles in and around the cutter suction dredger’s cutting system, in the fluid flow filed velocity vector and pressure distribution on different planes show different characteristics, and under higher suction velocity and lower cutter rotating speed more particles are suctioned into the suction inlet. The results can help better understand flow characteristics of solidfluid 2-phase-flow of cutter suction dredger’s cutting system, and provide theoretical support for relative system design and operational parameters optimization.
EN
To overcome the depth-of-field limitation of an optical microscope image, a three-dimensional measurement method with a superior depth-of-field is proposed. In the proposed method, light-field information of different angles is obtained by moving the aperture and the three-dimensional scene is reconstructed by using a computational reconstruction technology. First, stereo matching of different aperture position images is performed to obtain the multi-aperture imaging deviation. The focal plane moving distance is thereby estimated. Then, the relational expression between the image coordinates and the focal plane moving distance is determined according to the image coordinates. Two dimensional coordinates of the space point are obtained by the expression coefficients. Finally, the depth coordinates are computed, and three-dimensional reconstruction of the spatial points is completed. Experiments of three-dimensional measurements of the calibration board with different angles and circuit boards are conducted. The results show that the maximum error of the distance measurement is controlled into 0.84%, and the maximum angle measurement error is controlled into 4.56%.
EN
A disparity servoing based fast autofocusing method is proposed for stereomicroscopes according to linear relationship between the disparity change in stereomicroscopic images and the move distance of a motorized translation stage. For a certain stereomicroscope, the calibration of a disparity range of clear images at each magnification is implemented offline. After that, the disparity of the stereomicroscopic image is used as an index to represent the sharpness of an arbitrary image. If the disparity does not satisfy the requirement, move steps and direction of a step motor are calculated by utilizing the linear relationship between the disparity change and the move distance of the stage. The iteration will be continued until the disparity of the captured stereomicroscopic image approximates to the clearest disparity. The experimental results show that the proposed method only requires a few iterations and less time to reach the focus position, and the disparity error is less than 0.5 pixel.
EN
A super depth of field height measurement method is proposed to measure the object height with the optical stereoscopic microscope. The quasi-Euclidean epipolar rectification algorithm is utilized on the original stereoimage to obtain rectified stereoimages and calibrate two camera parameters. Then, feature points are obtained by the SURF (speed up robust feature) algorithm and their corresponding disparities are calculated. The disparity-depth of field curve is fitted by combining the step height values of a stepper motor. Moreover, through local disparity value got from feature points on the object, the relative shift height is calculated through regression analysis. Finally, according to binocular vision geometry, the thickness of the object can be calculated. Experimental results show that the measurement error in Z direction is from 1.51% to 7.71%, which indicates that the proposed method is able to measure the height of a microobject beyond depth of field within a tolerant error.
EN
The electrical test method (ETM) is used to measure the junction temperature Tj of high brightness LEDs. NI 5922 digitizer and Keithley S2400 source meter were used to build the measurement system. Various measurement currents were used under 1MHz sampling rate. Results of different measurement currents are found to be the same under the same sampling rate and measurement error can be found under low sampling rates. When sampling rate is down to 0.2kHz, measurement error is up to 13.7%.
PL
Zaproponowano metodę pomiaru temperatury złącza diody LED. Określono błąd metody dla różnych częstotliwości próbkowania.
6
Content available remote EMC Requirements and Test Methods for Light Emitting Diodes
EN
EMC test is important for the reliability improvement of LEDs and their application products. This paper introduces the EMC requirements for LED chips, LED devices and LED application products, focusing on electrostatic discharge, electrical fast transient, thunder stroke surge, voltage dip, conductive interference and radio frequency interference. Corresponding test methods are also given. These EMC requirements and test methods are valuable for LED manufacturer and end users.
PL
W artykule przedstawiono wymagania EMC w stosunku do LEDów oraz urządzeń z nimi współpracujących, takich jak wyładowania elektrostatyczne, stany przejściowe, skoki napięcia, interferencje. Przedstawiono odpowiednie metody badawcze. (Wymagania elektrokompatybilności i metody badania układów LED)
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