中国科学院机构知识库网格
Chinese Academy of Sciences Institutional Repositories Grid
首页 机构 成果 学者
  
  1. CAS IR Grid
机构
采集方式
内容类型
发表日期
学科主题
筛选

浏览/检索结果: 共10条，第1-10条 帮助

条数/页： 排序方式：
An adaptive atmospheric correction algorithm for the effective adjacency effect correction of submeter-scale spatial resolution optical satellite images: Application to a WorldView-3 panchromatic image 期刊论文  OAI收割
REMOTE SENSING OF ENVIRONMENT, 2021, 卷号: 259
作者:  Wang, Tao;  Du, Lili;  Yi, Weining;  Hong, Jin;  Zhang, Liming
  |  收藏  |  浏览/下载：36/0  |  提交时间：2021/06/15
Local rise of phylogenetic diversity due to invasions and extirpations leads to a regional phylogenetic homogenization of fish fauna from Chinese isolated plateau lakes 期刊论文  OAI收割
ECOLOGICAL INDICATORS, 2019, 卷号: 101, 期号: 1, 页码: 388-398
作者:  Jiang, Xiaoming;  Ding, Chengzhi;  Brosse, Sebastien;  Pan, Baozhu;  Lu, Yan
  |  收藏  |  浏览/下载：110/0  |  提交时间：2019/07/25
Far-field focusing of laser beam based on digital image processing techniques (EI CONFERENCE) 会议论文  OAI收割
Optoelectronic Imaging and Multimedia Technology, October 18, 2010 - October 20, 2010, Beijing, China
作者:  Zhao S.;  Tian Y.-Z.;  Liu L.-S.;  Guo J.;  Zhang H.-Y.
收藏  |  浏览/下载：27/0  |  提交时间：2013/03/25
In order to lead the laser beam transmit in the atmosphere convergently  an experiment of laser focus at the distance of 450m and 300m has been operated in the outdoor place. The actual manipulations are as follows: Firstly  the laser was collimated by a beam expander  then the near-parallel laser beam was transmitted with a Galileo telescope system  and the distance between the concave lens and the convex lens can be tuned through a precise displacement platform  so the focus of the system changed due to the tiny displacement of the concave lens. Secondly  the average power of the laser spot can be measured using power meter  the power is 47.67mW and the standard deviation is 0.67mW while the focal length is 450m. Thirdly  the energy distribution was found through the laser beam analyzer. The spot images were saved using the beam analyzer  then the saved image can be processed with Matlab software afterwards. The function named EDGE and Sobel operator was used in the pre-processing of the saved image  then method of median filter was used in the course of image de-noising and 53H filter was adopted in the signal analysis. The diameter of laser spot was obtained by the method above  the diameter is 5.56mm and the standard deviation is 0.24mm. The spot center excursion is 0.56mm  it is 10.43% of the total diameter of the laser spot. At last  the key factors of the energy dissipation in the focusing system can be summarized as follows: restriction of the diffraction limit  attenuation in the atmosphere  geometrical aberration of optical system  and the diffraction limit and the geometrical aberration are significant in the three factors above  so we can reduce the impact of the both factors during the design of optical system. The reliable referenced data of the system design can be acquired through the primary experiment research. 2010 SPIE.  
颅颌运动仿真系统(牙合)接触精度初探 期刊论文  OAI收割
中华口腔医学杂志, 2010, 卷号: 45, 期号: 2, 页码: 98-101
陈磊; 张豪; 冯海兰; 张驰; 张凤军
  |  收藏  |  浏览/下载：17/0  |  提交时间：2011/05/23
Analysis of laser jamming to satellite-based detector (EI CONFERENCE) 会议论文  OAI收割
International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging, June 17, 2009 - June 19, 2009, Beijing, China
作者:  Guo L.-H.;  Guo R.-H.;  Wang S.-W.
收藏  |  浏览/下载：29/0  |  提交时间：2013/03/25
The reconnaissance satellite  communication satellite and navigation satellite used in the military applications have played more and more important role in the advanced technique wars and already become the significant support and aid system for military actions. With the development of all kinds of satellites  anti-satellite laser weapons emerge as the times require. The experiments and analyses of laser disturbing CCD (charge coupled detector) in near ground have been studied by many research groups  but their results are not suitable to the case that using laser disturbs the satellite-based detector. Because the distance between the satellite-based detector and the ground is very large  it is difficult to damage it directly. However the optical receive system of satellite detector has large optical gain  so laser disturbing satellite detector is possible. In order to determine its feasibility  the theoretical analyses and experimental study are carried out in the paper. Firstly  the influence factors of laser disturbing satellite detector are analyzed in detail  which including laser power density on the surface of the detector after long distance transmission  and laser power density threshold for disturbing etc. These factors are not only induced by the satellite orbit  but dependence on the following parameters: laser average power in the ground  laser beam quality  tracing and aiming precision and atmospheric transmission. A calculation model is developed by considering all factors which then the power density entering into the detector can be calculated. Secondly  the laser disturbing experiment is performed by using LD (laser diode) with the wavelength 808 nm disturbing CCD 5 kilometer away  which the disturbing threshold value is obtained as 3.5510-4mW/cm2 that coincides with other researcher's results. Finally  using the theoretical model  the energy density of laser on the photosensitive surface of MSTI-3 satellite detector is estimated as about 100mW/cm2  which is largely exceed the disturbing threshold and therefore verify the feasibility of using this kind of laser disturbing the satellite-based detector. According to the results. using the similar laser power density absolutely saturate the requirements to laser disturbing satellite-based detector. If considering the peak power of pulsed laser  even decrease laser average power  it is also possible to damage the detector. This result will provide the reliable evidences to evaluate the effect of laser disturbing satellite-based detector. 2009 SPIE.  
The synthesis and field emission property of carbon nanotubes on carbon fibers substrate (EI CONFERENCE) 会议论文  OAI收割
Technical Digest of the 20th International Vacuum Nanoelectronics Conference, IVNC 07, July 8, 2008 - July 12, 2008, Chicago, IL, United states
Leyong Z.; Weibiao W.; Jingqiu L.; Yuxue X.; Da L.; Song C.; Haifeng Z.
收藏  |  浏览/下载：33/0  |  提交时间：2013/03/25
Using ferrocene as catalyst precursor  C2H2 as carbon source  carbon nanotubes (CNTs) with uniform density were synthesized on carbon fibers substrate by floating catalyst method. The morphology and microstructure were characterized by field emission scanning electron microscope (FESEM) and high-resolution transmission electron microscopy (HRTEM). The observation showed that the length of CNTs is about 2 m  the average space between adjacent CNTs is about 300 nm and the diameter of CNT is about 45 nm. The less dense "short and stubby" aligned CNTs films should have good electron field emission characteristics. The results of field emission showed that the emission current of CNTs/carbon fibers was 5 A at the field of 2.5 V/m  and the emission current can be 280 A with a field of 7 V/m (the specimen area is 0.25 cm2 and the distance between cathode and anode is 200 m). The calculation based on the F-N plot indicated that the field enhancement factor of CNTs tip is 499122. Using the conductivity and chemical stability of carbon fibers and the uniform and sparse density distribution of CNTs on carbon fibers substrate  the tip predominance of carbon nanotubes can be exerted  and simultaneously the effect of screening effects between adjacent carbon nanotubes on the field emission performance can also be effectively decreased. The CNTs synthesized on carbon fibers substrate has many predominances for the fabrication of cold cathode devices. For example  using the removability of carbon fibers  the cathode of CNTs/carbon fibers can be arbitrarily moved  enlaced or combined to form different patterns  and the cathode of CNTs/carbon fibers can be also fabricated in large size. Therefore  CNTs/carbon fibers may have potential application in field emission displays.  
Scaling argument of anisotropic random walk 期刊论文  OAI收割
COMMUNICATIONS IN THEORETICAL PHYSICS, 2005, 卷号: 43, 页码: 449-454
作者:  Xu, BZ;  Jin, GJ;  Wang, FF
  |  收藏  |  浏览/下载：17/0  |  提交时间：2018/05/31
A relation between the average Hamming distance and the average Hamming weight of binary codes 期刊论文  OAI收割
JOURNAL OF STATISTICAL PLANNING AND INFERENCE, 2001, 卷号: 94, 期号: 2, 页码: 413-419
作者:  Zhang, ZZ
  |  收藏  |  浏览/下载：16/0  |  提交时间：2018/07/30
CORRELATION OF FE2+ ISOMER-SHIFT WITH AVERAGE ATOM DISTANCE IN SILICATE MINERALS 期刊论文  OAI收割
CHINESE SCIENCE BULLETIN, 1995, 卷号: 40, 期号: 12, 页码: 1017-1021
作者:  LI, Z
  |  收藏  |  浏览/下载：15/0  |  提交时间：2018/09/26
CORRELATION OF FE2+ ISOMER-SHIFT WITH AVERAGE ATOM DISTANCE IN SILICATE MINERALS 期刊论文  OAI收割
CHINESE SCIENCE BULLETIN, 1995, 卷号: 40, 期号: 12, 页码: 1017-1021
作者:  LI, Z
  |  收藏  |  浏览/下载：13/0  |  提交时间：2018/09/26