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浏览/检索结果: 共12条，第1-10条 帮助

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Common and unique multimodal covarying patterns in autism spectrum disorder subtypes 期刊论文  OAI收割
MOLECULAR AUTISM, 2020, 卷号: 11, 期号: 1, 页码: 15
作者:  Qi, Shile;  Morris, Robin;  Turner, Jessica A.;  Fu, Zening;  Jiang, Rongtao
  |  收藏  |  浏览/下载：54/0  |  提交时间：2021/01/06
Gimbal displacement error analysis on an electro-optical seeker (EI CONFERENCE) 会议论文  OAI收割
Optical Design and Testing IV, October 18, 2010 - October 20, 2010, Beijing, China
作者:  Zhang X.;  Zhang X.;  Zhang X.
收藏  |  浏览/下载：35/0  |  提交时间：2013/03/25
It is essential to analyze the gimbal displacement errors for a seeker due to the importance for cueing of targets and tracking for the final approach. Otherwise  for a seeker electro-driven with a concentric glass dome  the large errors will decrease the picking  pointing  and tracking precision rooted from the displacement errors existing between the rotation center of the optical system and the gimbal. And the gimbaled camera system displacement errors are never eliminated but reduced due to the geometric errors consists of geometric tolerances of gimbal structure  manufacture  installation and vibration coming from working environment. In this paper  the gimbal displacement errors in an electro-optically stabilized platform resulting from geometric errors and environment errors were analyzed and shown in detail. The mathematical modal of the gimbal displacement errors created based on multi-body dynamics demonstrated the connection between the gimbal displacement errors and the stabilized platform. Taking a visible light image seeker as a case  the diameter is 120mm  and the geometric tolerances came from the values of primary design and the vibration data came from the environmental vibration test on the pitch-yaw seeker  and at the same time  the errors resulting from installation were considered too. Based on calculating  the maximum gimbal displacement error will reach to 0.2mm for pitching angle smaller than 40 and yawing angle smaller than 60. However  the critical parts have been found out according to the probability theory and the reliability analysis successfully used in the paper  and finally  the maximum gimbal displacement error reduced to 0.1mm  which is acceptable corresponding to the picking  pointing and tracking precision for an optical imaging seeker. 2010 Copyright SPIE - The International Society for Optical Engineering.  
Real time tracking by LOPF algorithm with mixture model (EI CONFERENCE) 会议论文  OAI收割
MIPPR 2007: Automatic Target Recognition and Image Analysis; and Multispectral Image Acquisition, November 15, 2007 - November 17, 2007, Wuhan, China
Meng B.; Zhu M.; Han G.; Wu Z.
收藏  |  浏览/下载：27/0  |  提交时间：2013/03/25
A new particle filter-the Local Optimum Particle Filter (LOPF) algorithm is presented for tracking object accurately and steadily in visual sequences in real time which is a challenge task in computer vision field. In order to using the particles efficiently  we first use Sobel algorithm to extract the profile of the object. Then  we employ a new Local Optimum algorithm to auto-initialize some certain number of particles from these edge points as centre of the particles. The main advantage we do this in stead of selecting particles randomly in conventional particle filter is that we can pay more attentions on these more important optimum candidates and reduce the unnecessary calculation on those negligible ones  in addition we can overcome the conventional degeneracy phenomenon in a way and decrease the computational costs. Otherwise  the threshold is a key factor that affecting the results very much. So here we adapt an adaptive threshold choosing method to get the optimal Sobel result. The dissimilarities between the target model and the target candidates are expressed by a metric derived from the Bhattacharyya coefficient. Here  we use both the counter cue to select the particles and the color cur to describe the targets as the mixture target model. The effectiveness of our scheme is demonstrated by real visual tracking experiments. Results from simulations and experiments with real video data show the improved performance of the proposed algorithm when compared with that of the standard particle filter. The superior performance is evident when the target encountering the occlusion in real video where the standard particle filter usually fails.  
Key techniques of laser direct writing patterns on spherical substrate (EI CONFERENCE) 会议论文  OAI收割
3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies, AOMATT 2007: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems, July 8, 2007 - July 12, 2007, Chengdu, China
作者:  Zhao J.-L.;  Feng X.-G.
收藏  |  浏览/下载：26/0  |  提交时间：2013/03/25
Comparing with the writing method of plane pattern  spherical pattern' has some remarkable different on several points. Firstly  it is difficult to spin-coated a uniform photoresist film on a spherical substrate  especially the ratio of spherical radius to caliber is smaller  and the spin-coated way must match the ratio of spherical radius to caliber. Secondly  if the sphere couldn't be regarded as a plane  a so-called concentric optical scan movement way must be applied for the generation of spherical pattern  because the reflex of substrate will affect the quantity of illumination. Commonly  an alignment technique is indispensable with pattern generation of spherical surface by the concentric optical scan in order to ensure the orthogonal intersection of focusing laser beam and writing surface. Thirdly  a uniform velocity control must be considered for the laser direct writing method on a spherical substrate. Otherwise  the exposure time of photoresist will be different  and the line widths of pattern will be also different at different areas. Fourthly  commonly  because the errors of concentric machine and substrate surface shape are bigger  so focusing servo-control technique is also needful for writing a pattern on a spherical substrate. Focusing servo-control may keep the focal spot on the spherical surface by a focus detection and control system in the course of writing pattern. Using these techniques  we fabricated a line width of 7m and a period of 600m isometric mesh on the concave of a spherical substrate.  
Improvement in oxidation resistance of a Ni3Al-based superalloy IC6 by rhenium-based diffusion barrier coatings 期刊论文  OAI收割
Intermetallics, 2007, 卷号: 15, 期号: 4, 页码: 599-606
F. Lang; T. Narita
收藏  |  浏览/下载：22/0  |  提交时间：2012/04/13
Transient of alumina oxide scale on beta-NiAl coated on M38G alloy at 950 degrees C 期刊论文  OAI收割
Intermetallics, 2007, 卷号: 15, 期号: 10, 页码: 1285-1290
G. M. Liu; M. S. Li; M. Zhu; Y. C. Zhou
收藏  |  浏览/下载：22/0  |  提交时间：2012/04/13
High-accuracy real-time automatic thresholding for centroid tracker (EI CONFERENCE) 会议论文  OAI收割
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
作者:  Wang Y.;  Wang Y.;  Wang Y.;  Wang Y.;  Zhang Y.
收藏  |  浏览/下载：37/0  |  提交时间：2013/03/25
Many of the video image trackers today use the centroid as the tracking point. In engineering  we can get several key pairs of peaks which can include the target and the background around it and use the method of Otsu to get intensity thresholds from them. According to the thresholds  it give a great help for us to get a glancing size  a target's centroid is computed from a binary image to reduce the processing time. Hence thresholding of gray level image to binary image is a decisive step in centroid tracking. How to choose the feat thresholds in clutter is still an intractability problem unsolved today. This paper introduces a high-accuracy real-time automatic thresholding method for centroid tracker. It works well for variety types of target tracking in clutter. The core of this method is to get the entire information contained in the histogram  we can gain the binary image and get the centroid from it. To track the target  so that we can compare the size of the object in the current frame with the former. If the change is little  such as the number of the peaks  the paper also suggests subjoining an eyeshot-window  we consider the object has been tracked well. Otherwise  their height  just like our eyes focus on a target  if the change is bigger than usual  position and other properties in the histogram. Combine with this histogram analysis  we will not miss it unless it is out of our eyeshot  we should analyze the inflection in the histogram to find out what happened to the object. In general  the impression will help us to extract the target in clutter and track it and we will wait its emergence since it has been covered. To obtain the impression  what we have to do is turning the analysis into codes for the tracker to determine a feat threshold. The paper will show the steps in detail. The paper also discusses the hardware architecture which can meet the speed requirement.  the paper offers a idea comes from the method of Snakes  
Thermal barrier coatings with two layer bond coat on intermetallic compound Ni3Al based alloy 期刊论文  OAI收割
Intermetallics, 2005, 卷号: 13, 期号: 3-4, 页码: 295-299
S. K. Gong; D. B. Zhang; H. B. Xu; Y. F. Han
收藏  |  浏览/下载：31/0  |  提交时间：2012/04/14
Improving high-temperature oxidation resistance of TiAl-based alloys by MnCl2 surface treatment 期刊论文  OAI收割
Intermetallics, 2003, 卷号: 11, 期号: 7, 页码: 651-660
L. Xin; G. Shao; F. Wang; P. Tsakiropoulos; T. Li
收藏  |  浏览/下载：22/0  |  提交时间：2012/04/14
Influence of columnar microstructure of a sputtered NiAl coating on its oxidation behavior at 1000 degrees C 期刊论文  OAI收割
Intermetallics, 2002, 卷号: 10, 期号: 5, 页码: 467-471
S. L. Yang; F. H. Wang; Z. M. Sun; S. L. Zhu
收藏  |  浏览/下载：16/0  |  提交时间：2012/04/14