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从飞机制造工装工艺设计入手,结合计算机支持的协同工作方法,分析并论述了飞机工装协同工艺设计系统的框架模型,工作流管理机制。提出一种以工艺知识为支撑,基于网络的工装协同工艺设计系统的实现方案。 相似文献
364.
Statistical study of radio drifting pulsation structures with associated CMEs and other observations
Chengming Tan Y.H. Yan Y.Y. Liu Q.J. Fu S.J. Wang H.R. Ji Z.J. Chen H.R. Jing 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(6):969-975
Solar radio burst, especially the fine structures (FSs) and the drifting pulsation structures (DPSs), may be used as an important diagnostics tool to draw the evolution map of the flare loop in the initial phase of solar flares. In this work, 52 radio events were found accompanying with DPSs. They were all observed with the Solar Radio Spectrometers (0.625–7.6 GHz) of China during 1998–2004. Combining the radio observations with LASCO-C2, Goes-8 SXR, Hα, EUV and Trace observations, we analyzed all these events and obtained some statistic conclusions: First, 88% DPSs take place at the initial phase of the radio burst, and their rich spectrum characteristics are helpful to understand the events further. Second, 83% DPSs are associated with CMEs or ejection events, and all the events are accompanied by Goes SXR flare. Third, for CMEs and DPSs, which take the first step, there is no significant predominance of either of them. The relationship between the DPSs and CMEs is still not clear in this study because of the lack of spatial resolution in the centimeter–decimeter band. However, the EIT or Trace ejection happened during the onset/end time of DPSs. They are signatures of the initial phase of CMEs. Two events will be illustrated to explain this. 相似文献
365.
I. Molotov V. Agapov V. Titenko Z. Khutorovsky Yu. Burtsev I. Guseva V. Rumyantsev M. Ibrahimov G. Kornienko A. Erofeeva V. Biryukov V. Vlasjuk R. Kiladze R. Zalles P. Sukhov R. Inasaridze G. Abdullaeva V. Rychalsky V. Kouprianov O. Rusakov E. Litvinenko E. Filippov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(7):1022-1028
A joint team of researchers under the auspices of the Center for Space Debris Information Collection, Processing and Analysis of the Russian Academy of Sciences collaborates with 15 observatories around the world to perform observations of space debris. For this purpose, 14 telescopes were equipped with charge-coupled device (CCD) cameras, Global Positioning System (GPS) receivers, CCD frame processing and ephemeris computation software, with the support of the European and Russian grants. Many of the observation campaigns were carried out in collaboration with the Astronomical Institute of the University of Bern (AIUB) team operating at the Zimmerwald observatory and conducting research for the European Space Agency (ESA), using the Tenerife/Teide telescope for searching and tracking of unknown objects in the geostationary region (GEO). More than 130,000 measurements of space objects along a GEO arc of 340.9°, collected and processed at Space Debris Data Base in the Ballistic Center of the Keldysh Institute of Applied Mathematics (KIAM) in 2005–2006, allowed us to find 288 GEO objects that are absent in the public orbital databases and to determine their orbital elements. Methods of discovering and tracking small space debris fragments at high orbits were developed and tested. About 40 of 150 detected unknown objects of magnitudes 15–20.5 were tracked during many months. A series of dedicated 22-cm telescopes with large field of view for GEO survey tasks is in process of construction. 7 60-cm telescopes will be modernized in 2007. 相似文献
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近年来,硝胺推进剂的研究取得了长足的发展,本文介绍了国外现阶段硝胺推进剂点火模型研究的现状.根据出发点的不同,把点火模型分为两类:从理论角度出发着重于点火机理的研究及从工程角度出发着重于实际工程的应用,并分别对其代表性的模型进行了介绍. 相似文献
368.
N Desai M Durante Z W Lin F Cucinotta H Wu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(2):236-242
We investigated the spatial distribution of the induction of the phosphorylated form of the histone protein H2AX (gamma-H2AX), known to be activated by DSBs. Following irradiation of human fibroblast cells with 600 MeV/nucleon silicon and 600 MeV/nucleon iron ions we observed the formation of gamma-H2AX aggregates in the shape of streaks stretching over several micrometers in an x/y plane. Polyethylene shielding was used to achieve a Bragg curve distribution with beam geometry parallel to the monolayer of cells. We present data that highlights the formation of immunofluorescent gamma-H2AX tracks showing the ion trajectories across the Bragg peak of irradiated human fibroblast cells. Qualitative analyses of these distributions indicated potentially increased clustering of DNA damage before the Bragg peak, enhanced gamma-H2AX distribution at the peak, and provided visual evidence of high-linear energy transfer particle traversal of cells beyond the Bragg peak in agreement with one-dimensional transport approximations. Spatial assessment of gamma-H2AX fluorescence may provide direct insights into DNA damage across the Bragg curve for high charge and energy ions including the biological consequences of shielding and possible contributors to bystander effects. 相似文献
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370.
Adaptive boosting for SAR automatic target recognition 总被引:3,自引:0,他引:3
Sun Y. Liu Z. Todorovic S. Li J. 《IEEE transactions on aerospace and electronic systems》2007,43(1):112-125
The paper proposed a novel automatic target recognition (ATR) system for classification of three types of ground vehicles in the moving and stationary target acquisition and recognition (MSTAR) public release database. First MSTAR image chips are represented as fine and raw feature vectors, where raw features compensate for the target pose estimation error that corrupts fine image features. Then, the chips are classified by using the adaptive boosting (AdaBoost) algorithm with the radial basis function (RBF) network as the base learner. Since the RBF network is a binary classifier, the multiclass problem was decomposed into a set of binary ones through the error-correcting output codes (ECOC) method, specifying a dictionary of code words for the set of three possible classes. AdaBoost combines the classification results of the RBF network for each binary problem into a code word, which is then "decoded" as one of the code words (i.e., ground-vehicle classes) in the specified dictionary. Along with classification, within the AdaBoost framework, we also conduct efficient fusion of the fine and raw image-feature vectors. The results of large-scale experiments demonstrate that our ATR scheme outperforms the state-of-the-art systems reported in the literature 相似文献