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结冰问题的研究对于民用飞机设计十分重要,采用结冰风洞试验是主要的方法之一,欧美国家有很多成熟的结冰风洞用于型号研究。结冰风洞中需要对很多参数进行控制,其中水雾参数精确控制的难度很大,而且一般通过间接方法来进行测试校准,往往误差较大,导致不同结冰风洞试验结果往往有所差异。文章介绍了在意大利宇航中心的IWT 结冰风洞完成的冰风洞校准试验,对结冰风洞水雾参数校准方法进行了阐述,为民机结冰风洞研究提供参考。 相似文献
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合理有效地确定机场地面运行容量对于统筹8规划机场建设工程具有重要意义.选取北京首都国际机场作为研究对象,应用Simmod仿真软件对机场3条平行跑道构型下,现状运行条件、东跑道夜间正常降落、缩小尾流间隔3种不同运行情况进行了仿真建模,分析了首都机场的正常地面运行容量和跑道起降架次.仿真结果表明,现状运行条件下,首都机场可满足的年旅客吞吐量约为8820万人次,日起降容量约为1718架次.东跑道夜间正常降落时高峰时段降落架次可提升约8%,缩小尾流间隔有助于提升机场整体运行容量,可满足的年旅客吞吐量约为9000万人次,日起降容量约为1738架次,高峰小时起降容量可提升约3%. 相似文献
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Malini Aggarwal H.P. Joshi K.N. Iyer Y.-S. Kwak J.J. Lee H. Chandra K.S. Cho 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The ionospheric total electron content (TEC) in the northern hemispheric equatorial ionization anomaly (EIA) crest region is investigated by using dual-frequency signals of the Global Positioning System (GPS) acquired from Rajkot (Geog. Lat. 22.29°N, Geog. Long. 70.74°E; Geom. Lat. 14.21°N, Geom. Long. 144.90°E), India. The day-to-day variability of EIA characteristics is examined during low solar activity period (F10.7∼83 sfu). It is found that the daily maximum TEC at EIA crest exhibits a day-to-day and strong semi-annual variability. The seasonal anomaly and equinoctial asymmetry in TEC at EIA is found non-existent and weaker, respectively. We found a moderate and positive correlation of daily magnitude of crest, Ic with daily F10.7 and EUV fluxes with a correlation coefficient of 0.43 and 0.33, respectively indicating an existence of a short-term relation between TEC at EIA and the solar radiation even during low solar activity period. The correlation of daily Ic with Dst index is also moderate (r = −0.35), whereas no correlation is found with the daily Kp index (r = 0.14) respectively. We found that the magnitude of EIA crest is moderately correlated with solar flux in all seasons except winter where it is weakly related (0.27). The magnitude of EIA crest is also found highly related with EEJ strength in spring (r = 0.69) and summer (r = 0.65) than autumn (0.5) and winter (r = 0.47), though EEJ is stronger in autumn than spring. 相似文献
56.
O.A. Oladipo Torben Schüler 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
A study of the performance of the NeQuick model and the Klobuchar model for GNSS single frequency range delay correction on a global scale was done using data for moderate solar activity. In this study NeQuick was used in the way intended for Galileo. This study is to assess the performance of the two models at each ionospheric geographic region during moderate solar activity as previously published studies were concentrated only on high solar activity. The results obtained showed that NeQuick outperformed Klobuchar for the whole year at the three geographical regions of the ionosphere. In terms of monthly root mean square of mismodeling, NeQuick outperformed Klobuchar by 15 TECU or more at low-latitudes, 5 TEC or more at mid-latitudes, and 1 TECU or more at high-latitudes. 相似文献
57.
针对航空弹药保障效率和可靠性要求高的问题,在分析保障流程的计划评审技术(PERT,Program Evaluation and Review Technique)网络图中各工序对任务完工影响程度的基础上,提取了工序关键度指标和重要度指标以及各方案下的按期完工概率,建立了保障人员配置方案评价指标体系,表示为评价函数形式.以基于蒙特卡洛方法的PERT网络仿真为核心,选择在遗传算法进化寻优框架下构建优化模型,该方法不仅得到了最优的保障人员配置方案,而且评估了需要注重的关键工序.算例实验证实了其有效性与实用性. 相似文献
58.
Analysis of the ionosphere/plasmasphere electron content variability during strong geomagnetic storm
Iu.V. Cherniak I.E. Zakharenkova D. Dzubanov A. Krankowski 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The ionosphere/plasmasphere electron content (PEC) variations during strong geomagnetic storms in November 2004 were estimated by combining of mid-latitude Kharkov incoherent scatter radar observations and GPS TEC data derived from global TEC maps. The comparison between two independent measurements was performed by analysis of the height-temporal distribution for specific location corresponding to the mid-latitudes of Europe. The percentage contribution of PEC to GPS TEC indicated the clear dependence from the time with maximal values (more than 70%) during night-time. During day-time the lesser values (30–45%) were observed for quiet geomagnetic conditions and rather high values of the PEC contribution to GPS TEC (up to 90%) were observed during strong negative storm. These changes can be explained by the competing effects of electric fields and winds, which tend to raise the layer to the region with lower loss rate and movement of the ionospheric plasma to the plasmasphere. 相似文献
在分析传统液压制动系统踏板特性的基础上,以试验得到的踏板特性为目标,设计了以弹性元件和液压单元为基本模拟单元的踏板模拟器;分析了"制动感觉"指数(BFI)评价指标;以AMESim和Matlab/Simulink为仿真平台,建立踏板模拟器仿真模型并进行了仿真计算.计算结果表明,模拟器输出的踏板反力随踏板行程的增加而增大,其踏板特性能够跟随目标踏板特性而变化;改变弹性元件的刚度和液压缸的压力,可以得到不同的踏板特性;对3种不同弹簧刚度的模拟器"制动感觉"进行评价,BFI达到92.4分,具有良好的制动感觉;通过调整模拟器参数,可以适应不同的车型或满足不同的驾驶员需求. 相似文献
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武器装备全面隐身化,隐身性能指标成为装备最重要的战技指标之一.隐身测试评估是实现装备隐身性能的关键指标和不可缺少的重要环节,涉及隐身装备从方案设计验证、研制方案筛选、部件和整机隐身效果评估、使用维护检定等全生命周期.综述了飞行器雷达隐身性能试验测试体系和测试评估方法,介绍了国内外典型的测试场及测量技术进展,详细分析了低散射诊断实验测试技术的最新成果,展望了飞行器隐身电磁特性测试技术未来发展趋势. 相似文献