中尺度对流系统影响下的空域容量评估研究

气象因素是影响空域容量的主要不可控因素之一。为了探讨强对流等恶劣天气的识别结合空域容量评估模型的可行性,并完成容量预测工作。采用引导滤波方法对葵花8气象卫星云图降噪处理,判定中尺度对流云团,依据网络最大流理论建立空域容量模型,使用动态阻塞系数表示中尺度对流系统对容量的动态影响,结合湖南管制空域及其气象信息对模型进行算例...     

空间遥感器大口径反射镜支撑结构型式综述

文章针对空间遥感器大口径反射镜（口径大于500mm）总结了影响支撑结构设计的主要因素，介绍了几种主要的支撑结构型式，并讨论了支撑结构设计中所需要考虑的若干问题。     

红外多光谱扫描仪在发射段的结构可靠性

用Ｇ莱希纳和Ｂ贝尔契（德）提出的结构系统可靠性分析通用方法（以下简称ＧＢ法），详细分析了某多光谱扫描仪的结构特点、工作环境与受力情况，并根据航天器受载特点建立了遥感器部分在发射阶段的可靠度数学模型，以一次二阶矩法为主要算法对红外扫描仪主体在发射阶段的结构可靠性进行了分析和评估。     

大口径SiC反射镜背部筋板布局设计研究

背部筋板布局在大口径反射镜轻量化设计中占有重要地位。在工程上，反射镜构型只能从有限的种类和数量中选取。为了进一步提高优化效率，文章对大口径SiC反射镜背部拓扑构型的分类方法进行了研究，提出了三角形筋板构型分类方法。文章按照分类进行了实例设计和计算，结果说明这种分类对大口径SiC反射镜背部筋板的布局设计有很好的指导作用。     

某型飞机翼盒结构多约束优化设计

将翼盒尺寸设计中多学科设计要求,包括应力、稳定性、气动弹性、变形和制造等要求转化为优化设计过程中和结构尺寸相关联的约束条件,从而将翼盒尺寸多学科优化设计(MDO)问题转化为多约束优化设计(MCO)问题。基于Hyperworks优化设计平台,建立了某型飞机翼盒有限元模型并利用TCL\TK语言将多学科约束嵌入到翼盒尺寸优化设计过程中,定义了多约束优化设计模型。优化设计结果减重7.4%,有效指导了翼盒结构详细设计。     

Ti-Mo合金β结构稳定性及理论强度的第一性原理研究

应用基于密度泛函理论的第一性原理赝势平面波法和超晶胞法对Mo含量(原子分数)为6.25%～37.5%的Ti-Mo二元合金的结合能和电子结构进行了计算;通过晶胞拉伸变形过程中单原子结合能随拉伸方向晶格常数的变化曲线计算出了合金成分为Ti15Mo1,Ti14Mo2,Ti13Mo3,Ti12Mo4,Ti11Mo5和Ti10Mo6的Ti-Mo二元合金在单向拉伸状态下的理论强度。研究了Mo元素对增强β钛合金稳定性,提高β钛合金强度的作用及作用机理。结果表明:随着Mo元素含量的增加,Ti-Mo二元合金β相的稳定性和理论强度都有明显提高;态密度的分析表明,Ti,Mo成键作用的加强导致了合金理论强度的提高。     

Study on extraction of crop information using time-series MODIS data in the Chao Phraya Basin of Thailand

In order to acquire the crop-related information in Chao Phraya Basin, time-series MODIS data were used in this paper. Although the spatial resolution of MODIS data is not very high, it is still useful for detecting very large-scale phenomenon, such as changes in seasonal vegetation patterns. After the data processing a general crop-related LULC (land use and land cover) map, cropping intensity map and cropping patterns map were produced. Analysis of these maps showed that the main land use type in the study area was farmland, most of which was dominated by rice. Rice fields mostly concentrated in the flood plains and double or triple rice-cropping system was commonly employed in this area. Maize, cassava, sugarcane and other upland crops were mainly distributed in the high alluvial terraces. Because these area often have water shortage problem particularly in the dry season which can support only one crop in a year, the cropping intensity was very low. However, some upland areas can be cultivated twice a year with crops which have short growing seasons. The crop information extracted from MODIS data sets were assessed by CBERS data, statistic data and so on. It was shown that MODIS derived crop information coincided well with the statistic data at the provincial level. At the same time, crop information extracted by MODIS data sets and CBERS were compared with each other which also showed similar spatial patterns.     

Laser Shock Peening of Aluminum Alloy 7050 for Fatigue Life Improvement

The effects of laser shock peening (LSP) on improving fatigue life of aluminum alloy 7050 are investigated.Surface hardness is increased corresponding to a high dislocation density induced by LSP.The X-ray diffraction stress measurement shows that LSP results in prominent increase of surface compressive stress,quasi-symmetrically distributed in the laser peened region.The fatigue life of the alloy 7050 in rivet fastener hole structure is notably improved owing to LSP.The sequence of LSP and fastener hole preparation also influence the fatigue cycle life of the alloy.     

卫星云图上自动识别追踪MCS方法

中尺度对流系统(MCS)常伴有冰雹、雷暴、飑线和龙卷等强对流天气的发生,不仅对机体结构造成巨大破坏,还对飞行机组及乘客人身安全产生严重威胁。准确有效地识别和追踪MCS所在位置和发展趋势一直以来都是MCS研究的重点和难点。根据前人所改进的MCS识别与追踪判定标准,将Matlab图像处理技术运用到MCS的识别追踪中。通过使用Matlab软件对国家卫星气象中心提供的卫星数据加工处理,并对其特征参数进行计算分析。实验证明,该方法不仅可以实现MCS自动识别,还可实现多时次MCS连续有效追踪,为危险天气下航路规避、改航路径划设、航线智能选择提供了有效的理论依据和实用参考标准。     

Chirp雷达的两种有效积累算法的研究

分析了Chirp雷达系统中包络走动对积累检测的影响,然后提出了两种有效的积累算法:时移包络补偿积累算法和包络插值移位补偿积累算法,分析了其原理、步骤及运算量。仿真结果显示后者的性能要优于前者。这两种方法在低信噪比条件下都能够实现较长时间的有效积累。