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Small-Signal Equivalent Circuit Modeling of a Photodetector Chip 被引量:1
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作者 苗昂 李轶群 +4 位作者 吴强 崔海林 黄永清 黄辉 任晓敏 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第12期1878-1882,共5页
A small-signal equivalent circuit model and the ted. The equivalent lumped circuit, which takes the main extraction techniques for photodetector chips are presen- factors that limit a photodetector's RF performance i... A small-signal equivalent circuit model and the ted. The equivalent lumped circuit, which takes the main extraction techniques for photodetector chips are presen- factors that limit a photodetector's RF performance into consideration,is first determined based on the device's physical structure. The photodetector's S parameters are then on-wafer measured, and the measured raw data are processed with further calibration. A genetic algorithm is used to fit the measured data, thereby allowing us to calculate each parameter value of the model. Experimental resuits show that the modeled parameters are well matched to the measurements in a frequency range from 130MHz to 20GHz, and the proposed method is proved feasible. This model can give an exact description of the photodetector chip's high frequency performance,which enables an effective circuit-level prediction for photodetector and optoelectronic integrated circuits. 展开更多
关键词 small-signal equivalent circuit model of photodetector parameter extraction high frequency meas-urement genetic algorithm
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Research on hydraulic slotting technology controlling coal-gas outbursts 被引量:2
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作者 魏国营 单智勇 张子敏 《Journal of Coal Science & Engineering(China)》 2008年第1期67-72,共6页
Measured to control serious coal-gas outburst in coal seam were analyzed by theory and experimented in test site.A new technique to distress the coal-bed and drain methane,called hydraulic slotting,was described in de... Measured to control serious coal-gas outburst in coal seam were analyzed by theory and experimented in test site.A new technique to distress the coal-bed and drain methane,called hydraulic slotting,was described in detail,and the mechanism of hydrau- lic slotting was put forward and analyzed.The characteristic parameter of hydraulic slotting was given in Jiaozuo mining area and the characteristic of validity,adaptability and secu- rity was evaluated.The results show that the stress surrounding the strata and the gas in coal seam is released efficiently and thoroughly while new techniques are taken,as slot- ting at heading face by high pressure large diameter jet.The resistance to coal and gas outbursts is increased dramatically once the area of slotting is increased to a certain size. In the process of driving 2 000 m tunnel by hydraulic slotting excavation,coal and gas outburst never occurre.The technique could be used to prevent and control potential coal-gas outburst in the proceeding of tunnel driving,and the speed tunneling could be as high as more than 2 times. 展开更多
关键词 coal-gas outburst hydraulic slotting outburst prevention and control meas-ures high pressure large diameter jet heading excavation
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Automatic Liver Segmentation Scheme for MRI Images Based on Cellular Neural Networks 被引量:1
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作者 Zhang Qun Min Lequan +1 位作者 Zhang Jie Zhang Min 《China Communications》 SCIE CSCD 2012年第9期89-95,共7页
Currently, the processing speed of exist-ing autormtic liver segmentation for Magnetic Res-onance Imaging (MRI) images is rehtively slow. An automatic liver segmentation scheme for MRI irmges based on Cellular Neura... Currently, the processing speed of exist-ing autormtic liver segmentation for Magnetic Res-onance Imaging (MRI) images is rehtively slow. An automatic liver segmentation scheme for MRI irmges based on Cellular Neural Networks (CNN) is presented in this paper. It ensures the validity of this scheme and at the same time completes the im-age segmentation faster to accurately calculate the liver volume by using parallel computing in real time. In order to facilitate the CNN irmge process-hag, firstly, three-dimensional liver MRI images should be transformed into binary images; second- ly, an appropriate template parameter of the Global Connectivity Detection CNN (GCD CNN) shall be selected to probe the connectivity of the liver to extract the entire liver; and then the Hole-Filler CNN (HF CNN) are used to repair the entire extracting liver and improve the accuracy of fiver segmentation; final-ly, the liver volume is obtained. Results show that the scheme can ensure the accuracy of the automatic seg-mentation of the liver, and it can also improve the processing speed at the same time. The liver volume calculated is in line with the clinical diagnosis. 展开更多
关键词 MRI liver segmentation volume meas-urement CNN Bevel theory
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Understanding BitTorrent Through Real Measurements
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作者 Wojciech Mazurczyk Pawe Kopiczko 《China Communications》 SCIE CSCD 2013年第11期107-118,共12页
In this paper, we present the resuks of the BitTorrent measurement study. Two sources of BitTorrent data were utilised: meta- data files and the logs of one of the currently most popular BitTorrent clients--gTorrent.... In this paper, we present the resuks of the BitTorrent measurement study. Two sources of BitTorrent data were utilised: meta- data files and the logs of one of the currently most popular BitTorrent clients--gTorrent. Experimental data were collected for fifteen days from the popular torrent-discovery site thepiratebay.org (more than 30 000 torrents were captured and analysed). During this pe- riod the activity and logs of an unmodified version of μTorrent client downloading ses- sions were also captured. The obtained ex- perimental results are swarm-oriented, which allows us to look at BitTorrent and its users from an exchanged resources perspective. Moreover, comparative analysis of the clients' connections with and without the μTP proto- col is carried out to verify the extent to which μTP improves BitTorrent transmissions. To the authors' best knowledge, none of the previous studies have addressed these issues. 展开更多
关键词 BitTorrent traffic analysis meas-urement study meta-data files μTorrent μTP
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