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大相对口径大线视场光学系统的设计 被引量:8
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作者 潘君骅 《中国工程科学》 2000年第8期89-90,共2页
文章论述了用于红外远距离探测的光学应是全反射式的大相对口径、大视场的离轴非球面系统。给出了一个通光口径为60 0mm ,相对口径 1∶1 67,线视场为± 5°的设计结果。
关键词 红外探测 相对口径 光学系统 设计 离轴非球面系统 通光口径 线视场
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大视场线阵CCD图像灰度均匀化 被引量:2
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作者 章秀华 叶鹏 +1 位作者 王万里 钟庆 《光电工程》 CAS CSCD 北大核心 2015年第7期62-66,共5页
针对大视场线阵CCD图像不均匀现象,提出了一种基于图像像素灰度补偿的均匀化方法。首先分析并计算线形目标上不同坐标位置的微小面元在线阵CCD上产生的辐射照度,并由此推导线阵CCD面元上不同像素灰度值与中心像素灰度值之间的关系,进而... 针对大视场线阵CCD图像不均匀现象,提出了一种基于图像像素灰度补偿的均匀化方法。首先分析并计算线形目标上不同坐标位置的微小面元在线阵CCD上产生的辐射照度,并由此推导线阵CCD面元上不同像素灰度值与中心像素灰度值之间的关系,进而建立大视场线阵CCD像面上像素的灰度补偿模型,实现大视场线阵CCD图像快速均匀化的目的。对大量线阵CCD采集的高速路面图像进行了处理,结果表明我们提出的方法具有较强的可行性、鲁棒性和实用性。 展开更多
关键词 线阵CCD 光辐照度 像素灰度补偿模型 图像灰度均匀化
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Mosaic line-scan camera based on FPGA 被引量:2
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作者 夏湖培 苏新彦 +1 位作者 刘培珍 刘宾 《Journal of Measurement Science and Instrumentation》 CAS 2014年第4期57-61,共5页
Because single line-scan camera loses light in the edge of the sensor when the field of view is large, a mosaic cam- era based on field programmable gate array (FPGA) is presented by putting multiple cameras arrange... Because single line-scan camera loses light in the edge of the sensor when the field of view is large, a mosaic cam- era based on field programmable gate array (FPGA) is presented by putting multiple cameras arranged in a straight line to share the field of view and reduce the view angle of every camera. For detecting doping micro particles with the designed mosaic line-scan camera, a detection algorithm of the target's location in FPGA is proposed. Finally, the practicability and stability of the system were validated experimentally. The results of the experiment show that the camera can get images clearly with less light loss and can accurately distinguish the target and the background. 展开更多
关键词 large field of view line-scan camera field programmable gate array (FPGA) threshold segmentation
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EFFECT OF FEED ARRAY CONFIGURATION ON THE FIELD-OF-VIEW OF RADIO TELESCOPE ANTENNA
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作者 Wu Yang Du Biao +1 位作者 Liu Xiaomeng Jin Chengjin 《Journal of Electronics(China)》 2013年第4期362-367,共6页
Phased Array Feed (PAF) is a small two-dimensional phased array antenna, playing a role as the multi-beam feed for the reflector antenna. The prominent capability of large continuous Field-of-View (FoV) coverage and f... Phased Array Feed (PAF) is a small two-dimensional phased array antenna, playing a role as the multi-beam feed for the reflector antenna. The prominent capability of large continuous Field-of-View (FoV) coverage and fast survey speed makes PAF the promising feed for radio telescopes. In this paper, the effect of feed array of PAF on the gain fluctuations over FoV is analyzed on a sim- plified model of the Five-hundred-meter Spherical Aperture radio Telescope (FAST), including illu- mination pattern edge taper, element spacing, element arrangement and element amount. And the differences between rectangular and hexagonal array arrangements are compared. The relationship between the FoV and array configuration are concluded at last. 展开更多
关键词 Radio telescope Phased Array Feed (PAF) MULTI-BEAM GAIN
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A rapid on-site calibration method for measuring dynamic envelope curve of high-speed trains
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作者 LIU Chang-jie YANG Du-juan +1 位作者 FU Lu-hua WANG Zhong 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2017年第3期205-214,共10页
Dynamic envelope curve is a significant parameter to assess the running safety of high-speed trains.Up to now the method based on binocular stereo vision is the only way available to measure the dynamic envelope curve... Dynamic envelope curve is a significant parameter to assess the running safety of high-speed trains.Up to now the method based on binocular stereo vision is the only way available to measure the dynamic envelope curve of a train,the speed of which is over200km/h.Nevertheless the method has two limitations,one is large field-〇f-view(FO V),the other is calibration time.Hence portable calibration equipment,easy-t〇-build target and rapid calibration algorithm are required to complete the calibration.In this paper,a new rapid on-site calibration method with large FOV based on binocular stereo vision is proposed.To address these issues,a light target has been designed,the rail coordinate system(RCS)is represented by40fixed retroreflective points on the target,and they are utilized to calibrate the parameters of two cameras.In addition,two cameras merely capture a single image of the target simultaneously,and the intrinsic and extrinsic parameters of the cameras can be calculated rapidly.To testify the proposed method,the experiments have been conducted and the results reveal that the accuracy can reach+1mm,which can meet the measurement requirement. 展开更多
关键词 high-speed train dynamic envelope curve on-site calibration field-〇f-view (FOV)
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Case Study on Hybrid Business Model: KT's Olleh TV Skylife
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作者 Minzheong Song 《Journalism and Mass Communication》 2012年第3期491-502,共12页
This paper aims to analyze a case of a telecom operator, Korea Telecom (KT)'s hybrid business model---Olleh TV Skylife (OTS). This case is KT's new hybrid network and set-top-box (STB) which combines Internet ... This paper aims to analyze a case of a telecom operator, Korea Telecom (KT)'s hybrid business model---Olleh TV Skylife (OTS). This case is KT's new hybrid network and set-top-box (STB) which combines Internet Protocol TV (IPTV) with Direct-To-Home (DTH) satellite reception and business. It serves now as a guideline to better understanding hybrid consumer behavior and their needs. This paper shows how KT's OTS has been formulated as a new business model, how it has changed the market structure, and how it has experienced a successful market performance with new business idea and innovative technology. Before analyzing this case, it firstly discusses about the technological situation and the industrial organization (IO) theory. After this, it shows the previous service offerings of cable TV, satellite TV, and IPTV, before launching OTS and shows that the mixed service portfolio of satellite TV and IPTV is the perfect service combination to beat the cable TV in terms of hybrid consumer needs. After explanation about OTS, this paper verifies whether this hybrid business model really changes market and generates a good market performance and operating synergy with KT's other businesses of content, network, and marketing. In conclusion, this paper expects future growth potential of OTS and KT Skylife in terms of subscription fee, home shopping, and advertising sales based on the total subscriber base. 展开更多
关键词 hybrid business model IPTV satellite TV industrial organization theory
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A Model for Periodic Nonlinear Electric Field Structures in Space Plasmas
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作者 M.N.S. Qureshi SHI Jian-Kui LIU Zhen-Xing 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第7期149-154,共6页
In this study,we present a physical model to explain the generation mechanism of nonlinear periodic waveswith a large amplitude electric field structures propagating obliquely and exactly parallel to the magnetic fiel... In this study,we present a physical model to explain the generation mechanism of nonlinear periodic waveswith a large amplitude electric field structures propagating obliquely and exactly parallel to the magnetic field.The'Sagdeev potential' from the MHD equations is derived and the nonlinear electric field waveforms are obtained when theMach number,direction of propagation,and the initial electric field satisfy certain plasma conditions.For the parallelpropagation,the amplitude of the electric field waves with ion-acoustic mode increases with the increase of initial electricfield and Mach number but its frequency decreases with the increase of Mach number.The amplitude and frequency ofthe electric field waves with ion-cyclotron mode decrease with the increase of Mach number and become less spiky,andits amplitude increases with the increase of initial electric field.For the oblique propagation,only periodic electric fieldwave with an ion-cyclotron mode obtained,its amplitude and frequency increase with the increase of Mach number andbecome spiky.From our model the electric field structures show periodic,spiky,and saw-tooth behaviours correspondingto different plasma conditions. 展开更多
关键词 nonlinear waves electric field solitary structures
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Numerical Investigation of Centerline Curvature Effects on a Compact S-shaped Intake 被引量:1
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作者 Enliang Huang Shengfeng Zhao +3 位作者 Zhijun Lei Jianxiong Kang Xingen Lu Junqiang Zhu 《Journal of Thermal Science》 SCIE EI CAS CSCD 2012年第5期413-419,共7页
Taking into account stealth, structure and maintenance, ultra-compact S-shaped intake has been widely used in modem vehicles. In this paper a series of steady numerical simulation were carried out to investigate the c... Taking into account stealth, structure and maintenance, ultra-compact S-shaped intake has been widely used in modem vehicles. In this paper a series of steady numerical simulation were carried out to investigate the complex flow mechanism in s-shaped intake, particular attention was given to examining the effect of centerline curvature on the performance and flowfield of an ultra-compact S-shaped intake. In order to validate the multi-block model, the computational results for Royal Aircraft Establishment intake 2129-M2129 which had modest centerline cur- vature distribution were corrected with available experimental test data. The numerical simulation results agreed fairly well with the experimental data, and the computational method was then used to investigate the effects of different centerline curvature distributions on performance and flow field in compact S-shaped intake. Detailed analyses of the flow visualization had exposed the different flow topologies between the cases with different cen- terline curvature. It was found that different centerline curvature distributions changed the initial location and the size of separation bubble, as well as the strength of two counter-rotating vortices at the entrance of engine. 展开更多
关键词 S-shaped Intake Secondary Flow Centerline Curvature Separation bubble Counter-rotating Vortices
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