Studies the USB protocol, and develops a USB device (function) driver on RTOS. V model software engineering development method is applied. It successfully passed the test of USB device simulator. As a kind of new serial communication standard, USB integrates many network and communication technologies. It allows peripheral interfaces to connect easily with the computer and improves in communication speed.
Designed a system for the high gain laser pre-amplifier to evaluate the image quality. The system uses 4f imaging principle and Kepler type telescope was choiced, it has two advantages: avert optical distortion and eliminate aberration in the measurement system. Combined with the location of the lens inside of pre-amplifier such as the spatial filter , the near field imaging structure was designed. The structure can be reduced to 11.9 times the beam image, and clearly passed the image to the CCD target surface. The location of first positive lens focus is the location of far field image. In this article, one laser pre-amplifier was measured. The average measured near field modulation M=1.34, the average measured far field diffraction limit is 2.94. Experiments show that the stability of measuring system is less than±5%, it can meet the measurement requirements of ICF laser pre-amplifier parameters. Use this system we can discover the problem during the design and installation. There is great meaning for develop of laser pre-amplifier in ICF for further.
With the quickly development of electric vehicle and dc microgrid, the vehicle to dc microgrid technology has obtained widely attentions. The battery energy storage units are replaced by the dynamic energy storage units of electric vehicle, and the dc voltage coordinated control of vehicle to dc microgrid is one of the most important problems. In order to deal with the problems, an effective control method is proposed in the paper. The dc voltage coordinated control methods are analyzed under grid-connected operation, converter current limit and islanding operation conditions. The control method of electric vehicle can be switched to achieve short support for dc bus voltage. Finally, the simulation results verify the feasibility and effectiveness of proposed control method.
This article introduced the latest development of Embedded Linux,and attached importance to the mature and widely used GUI development environment Qtopia based on Qt/Embedded. Combining with the development experience,the procedure of Qtopia application development based on Embedded Linux was described in detail.
With the complexity of the structure of mechanical product,its static and dynamic property was influenced by more and more factors(or variables). Random and fuzziness of some variables are universal,and should be taken consideration as to make theory model accord with the fact. According to the fuzzy probability theory,the probability density distributing function of fuzzy variables of complex structure was obtained. Then,connected with other random variables,the statie fuzzy stress,fuzzy strain and mass of structure was calculated by probability finite element method(the dynamic parameters also can be got if needed). Use Hydraulic pressure machine as instance, the result values are very different from the values attained by traditional finite element method(FEM). It shown that for complicated structure, the result of static or dynamic property by traditional single FEM is not so reliable. Through this way,more reliable data can be obtained for structure reliability design.
By simulating numerically rotational wavepacket of O2 molecules in short pulse laser field,alignment of O2 drived by two-short-pulse laser is investigated theoretically.Compared to alignment of O2 drived by single pulse laser field,under the same temperature,the alignment degree of O2 molecules increase effectively by optimizing intensity ratio and delay time of two pulses.The results show that alignment could be maximum with intensity ratio 1∶3 approximately and delay time 11.73 ps.
In this paper, a novel fiber-optic liquid level sensor is proposed and experimentally completed through a cascaded multimode-single-mode-multimode (MSM) structure with the same length of 25 mm. Two typical in-line Mach-Zehnder interferometers (MZIs) are respectively formed in each MSM structure, but more cladding modes are excited in the second MZI. A multimode-interference-like fringe then is observed, due to the mismatched energy of two MZIs. The comprehensive tests are performed in terms of liquid (water) level and temperature. The experimental results show that obvious intensity variation is demonstrated in a continuous liquid level measurement, but with a slight wavelength drift (about ±0.522 nm). The liquid level sensitivity reaches 0.261 dB/mm in the range from 0 to 40 mm with the linearity of 0.98. Inversely, the temperature response exhibits a flat wavelength shift. The wavelength sensitivity is 43.27 pm/°C and the intensity change is merely 0.01 dB/°C In the range from 24 to 58 °C. So the calculated temperature crosstalk is about 0.04 mm/°C and the measured error is compressed within 0.02%. It is obvious that, owing to such low crosstalk, our senor has the potential in high discriminative simultaneous measurement of engineering application.
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