复杂环境下微小飞行器惯性/激光雷达Robust-SLAM方法

针对微小型飞行器在巡检、探测和地图构建等应用中关键的自主导航技术,提出了一种基于惯性辅助的激光雷达Robust-SLAM方法用于微小型飞行器自主导航。相对于传统的激光雷达SLAM方法,该方法在SLAM框架中引入了感知环境突变检测方法,并且加强了惯性与SLAM的组合程度,有效地解决了高程方向感知环境发生突变时激光雷达SLAM定位误差大的问题。室内车库实际飞行实验结果表明,该方法能够实现微小型飞行器在三维空间中实时可靠的自主导航,具有较好的工程应用价值。     

Blank Panel Design of Integral Wing Skin Panels Based on Feature Mapping Methods

A blank panel design algorithm based on feature mapping methods for integral wing skin panels with supercritical airfoil surface is presented.The model of a wing panel is decomposed into features,and features of the panel are decomposed into information of location,direction,dimension and Boolean types.Features are mapped into the plane through optimal surface development algorithm.The plane panel is modeled by rebuilding the mapped features.Blanks of shot-peen forming panels are designed to identify the effectiveness of the methods.     

无人机载SAR一体化显控系统的设计研究

阐述了无人机载SAR一体化显控系统的设计,对系统实现中应用到的一些关键技术进行了详细说明,就多位面技术、多线程技术及内存映射技术进行了探讨。     

Simulation study on slant-to-vertical deviation in two dimensional TEC mapping over the ionosphere equatorial anomaly

With the rapid increase of GPS/GNSS receivers being deployed and operated in China, real-time GPS data from nearly a thousand sites are available at the National Center for Space Weather, China Meteorology Administration. However, it is challenging to generate a high-quality regional total electron content (TEC) map with the traditional two-dimensional (2-D) retrieval scheme because a large horizontal gradient has been reported over east–south Asia due to the northern equatorial ionization anomaly. We developed an Ionosphere Data Assimilation Analysis System (IDAAS), which is described in this study, using an International Reference Ionosphere (IRI) model as the background and applying a Kalman filter for updated observations. The IDAAS can reconstruct a three-dimensional ionosphere with the GPS slant TEC. The inverse slant TEC correlates well with observations both for GPS sites involved in the reconstruction and sites that are not involved. Based on the IDAAS, simulations were performed to investigate the deviation relative to the slant-to-vertical conversion (STV). The results indicate that the relative deviation induced by slant-to-vertical conversion may be significant in certain instances, and the deviation varies from 0% to 40% when the elevation decreases from 90° to 15°, while the relative IDAAS deviation is much smaller and varies from −5% to 15% without an elevation dependence. Compared with ‘true TEC’ map derived from the model, there is large difference in STV TEC map but no obvious discrepancy in IDAAS map. Generally, the IDAAS TEC map is much closer to the “true TEC” than is STV TEC map is.     

Spectral transformation of ASTER and Landsat TM bands for lithological mapping of Soghan ophiolite complex,south Iran

Spectral transformation methods, including correlation coefficient (CC) and Optimum Index Factor (OIF), band ratio (BR) and principal component analysis (PCA) were applied to ASTER and Landsat TM bands for lithological mapping of Soghan ophiolitic complex in south of Iran. The results indicated that the methods used evidently showed superior outputs for detecting lithological units in ophiolitic complexes. CC and OIF methods were used to establish enhanced Red–Green–Blue (RGB) color combination bands for discriminating lithological units. A specialized band ratio (4/1, 4/5, 4/7 in RGB) was developed using ASTER bands to differentiate lithological units in ophiolitic complexes. The band ratio effectively detected serpentinite dunite as host rock of chromite ore deposits from surrounding lithological units in the study area. Principal component images derived from first three bands of ASTER and Landsat TM produced well results for lithological mapping applications. ASTER bands contain improved spectral characteristics and higher spatial resolution for detecting serpentinite dunite in ophiolitic complexes. The developed approach used in this study offers great potential for lithological mapping using ASTER and Landsat TM bands, which contributes in economic geology for prospecting chromite ore deposits associated with ophiolitic complexes.     

陆海激光卫星高程测量的思考

为满足新形势下陆海激光卫星高程测量的需求,分析了高精度高程控制点数据获取、森林生物量估算、浅海及海岛礁地形测绘、"三极"区域高程变化监测等方面的需求,提出了发展多波束激光卫星测高的初步设想,并就高精度激光指向测量技术、距离门宽度动态适应调整技术等关键技术问题进行了探讨。     

Analytical solutions of cracks emanating from an elliptical hole under shear

Based on the complex variable method, the analytical solutions of stress functions and stress intensity factors（SIFs） are provided for the plane problem of two collinear edge cracks emanating from an elliptical hole in an infinite plate under shear. The stress distribution along the horizontal axis is given in graphical forms, which conforms to Saint-Venant＇s principle. The influences of crack length and ellipse shape on the stress intensity factors are evaluated. Comparing the analytical solutions with finite element method（FEM） results shows good coincidence. These numerical examples show that the present solutions are accurate.     

基于区域地址映射的NAND Flash静态磨损均衡算法

在区域地址映射机制基础上,提出了一种延长NAND flash有效使用寿命的静态磨损均衡算法。算法以区域为单位进行冷热数据迁移,使用区域的平均擦除次数和部分平均擦除次数度量区域磨损程度,选取磨损程度最小区域的块与系统预留块进行冷热数据交换。算法将擦除次数上限与当前最大擦除次数的差值作为动态阈值的基数,以减少磨损均衡的开销,保证NAND flash的平均读写性能。通过测试,证明算法能够有效提高flash存储器的磨损均衡效果。     

局部凸空间中的压缩映射

本文将压缩映射原理推广到Ｈａｕｓｄｏｒｆｆ局部凸空间，证明了几个不动点定理。     

一种新的非扩张映像不动点的复合迭代算法

在Banach空间中．引进了一种新的逼近非扩张映像不动点的复合隐迭代格式。证明了一些弱收敛和强收敛定理。并给出了相对收敛率的估计。本研究结果改进了已有同类的结果。