Identifying areas of high economic-potential copper mineralization using ASTER data in the Urumieh–Dokhtar Volcanic Belt,Iran

This study investigates the application of spectral image processing methods to ASTER data for mapping hydrothermal alteration zones associated with porphyry copper mineralization and related host rock. The study area is located in the southeastern segment of the Urumieh–Dokhtar Volcanic Belt of Iran. This area has been selected because it is a potential zone for exploration of new porphyry copper deposits. Spectral transform approaches, namely principal component analysis, band ratio and minimum noise fraction were used for mapping hydrothermally altered rocks and lithological units at regional scale. Spectral mapping methods, including spectral angle mapper, linear spectral unmixing, matched filtering and mixture tuned matched filtering were applied to differentiate hydrothermal alteration zones associated with porphyry copper mineralization such as phyllic, argillic and propylitic mineral assemblages.     

非接触高温测量技术发展与现状

非接触高温测量技术已经成为2 000℃以上高温目标温度测量的主要手段,其发展水平直接制约着国防科技工业尤其是高速飞行器热防护及隐身性能等关键技术领域的发展。本文综述了当前各类非接触高温测量技术的研究现状、技术优缺点及应用前景,并对未来非接触高温测量技术的发展进行了展望。     

基于数值微分方法的卫星陀螺故障诊断(英文)

提出一种基于数值微分的卫星陀螺故障诊断方法。通过引入代数可观测的概念,将故障诊断问题转化为求解数值微分问题。并根据卫星姿态运动学方程证明了陀螺故障的代数可观性。然后通过高增益观测器的方法来近似姿态敏感器测量输出的数值导数,并利用李雅普诺夫理论分析和设计高增益观测器。基于陀螺故障的代数可观性和星敏感器测量输出的数值微分,可以直接得到陀螺组件的故障估计值。最后,通过突变、缓变和并发故障等仿真算例验证了算法的有效性,仿真结果表明所提出的方法不仅可以检测故障的发生,而且能够估计故障幅值。     

高精度VLBI技术在深空探测中的应用

介绍了适合单探测器测定轨的高精度VLBI技术和适合多探测器测定位的同波束VLBI技术的研究进展。利用"嫦娥3号"着陆器的ΔDOR型VLBI观测,得到了误差0.67ns的VLBI群时延数据。利用"嫦娥3号"着陆器和月球车的同波束VLBI观测,得到了随机误差0.3ps的差分相时延数据,以数厘米的灵敏度监测出月球车的移动、转弯等动作,并把月球车的相对定位精度提高至1m。针对深空探测,提出了使VLBI时延测量精度进一步提高所需要开展的部分研究内容。     

复杂薄壁构件自适应加工工艺几何模型重构

随着制造理念和制造水平的不断提高,大量复合制造工艺背景下的近净成形叶片被应用到现役或在研的航空发动机中。该类叶片是典型的复杂薄壁结构零件,无精确定位基准,且成形一致性差。采用传统叶身定位,加工后的前/后缘、榫齿形状和位置精度均难以保证,从而导致产品一致性差,易超差与合格率低。针对以上问题,提出一种面向自适应加工的复杂薄壁结构零件工艺几何模型重构方法。首先,建立复杂曲面的采样点分布模型,快速获取叶片精确成型区域的位置和形状;其次,提出基于特征曲线相似变形的模型重构算法,精确重构前/后缘非精确成型区域的工艺几何模型;最后,通过精锻叶片自适应加工试验进行验证。试验结果表明：该方法可有效满足以精锻叶片为代表的复杂薄壁构件自适应加工要求。     

Aerial-BiSeNet: A real-time semantic segmentation network for high resolution aerial imagery

The aircraft system has recently gained its reputation as a reliable and efficient tool for sensing and parsing aerial scenes. However, accurate and fast semantic segmentation of high-resolution aerial images for remote sensing applications is still facing three challenges: the requirements for limited processing resources and low-latency operations based on aerial platforms, the balance between high accuracy and real-time efficiency for model performance, and the confusing objects with large intra-class variations and small inter-class differences in high-resolution aerial images. To address these issues, a lightweight and dual-path deep convolutional architecture, namely Aerial Bilateral Segmentation Network (Aerial-BiSeNet), is proposed to perform real-time segmentation on high-resolution aerial images with favorable accuracy. Specifically, inspired by the receptive field concept in human visual systems, Receptive Field Module (RFM) is proposed to encode rich multi-scale contextual information. Based on channel attention mechanism, two novel modules, called Feature Attention Module (FAM) and Channel Attention based Feature Fusion Module (CAFFM) respectively, are proposed to refine and combine features effectively to boost the model performance. Aerial-BiSeNet is evaluated on the Potsdam and Vaihingen datasets, where leading performance is reported compared with other state-of-the-art models, in terms of both accuracy and efficiency.     

基于卫星监视几何精度因子的UDRE值估计方法

星基增强导航系统(SBAS,Satellite Based Augmentation System)通过向用户提供用户差分距离误差(UDRE,User Differential Range Error),来保证广播星历和星钟改正数的精度并增强用户的完好性性能.给出了一种用于主控站的UDRE计算方法,提出了卫星监视几何精度因子(SSDOP,Satellite Surveillance Dilution of Precision)的概念.基于UDRE和SS-DOP的表达式,通过数学推导发现UDRE受到SSDOP和限制因子的影响,而限制因子可以用其统计平均值0.7438来替代,建立了由SSDOP估计UDRE的表达式.仿真结果表明:利用SS-DOP估计出的UDRE值,其误差不超过0.8 m,能够反映出当前卫星UDRE的特性,可以作为用户在无法接收完好性信息时快速推算UDRE的一种可行手段.     

反TBM拦截弹杀伤增强器综合设计模型及其应用

针对反战术弹道式导弹(TBM)拦截弹杀伤增强器设计方法中存在的不足,提出了拦截平面内最优合成迎角数学模型,在此基础上建立了拦截弹杀伤增强器综合设计模型.该模型以杀伤增强器参数为输入量,可在设计拦截弹时对其进行可用过载估计与制导精度限制,并通过最优合成迎角控制来近一步增强拦截弹对TBM的杀伤性能.以PAC-3拦截弹及某典型TBM弹头为例进行仿真验证,结果表明采用综合设计模型后PAC-3杀伤概率平均高于原弹约7％,使用该模型对PAC-3杀伤增强器进行优化,优化结果明显提高了PAC-3拦截弹的作战性能.     

Investigation of longitudinal aerodynamic parameters identification method for fly-by-wire passenger airliners

The flight control system of a fly-by-wire （FBW） passenger airliner with a complex frame-work and high feedback gain augmentation would change the original characteristic of a loaded signal and suppress the excitation of an airplane＇s pertinent motion modes. Taking a research example of an FBW passenger airliner model with longitudinal relaxed-static-stability, a new method of signal type selection and signal parameter design is proposed, through analysis of signal energy distribution and plane body＇s frequency response. According to CCAR60--the Appraisal and Use Regulation of Flight Simulator Device, the simulation validation of the FBW passenger airliner＇s longitudinal aerodynamic parameters identification is put forward. The validation result indicates that the designed signal could excite the longitudinal motion mode of the FBW passenger airliner adequately and the multiparameter comparison in simulation meets the objective test request of CCAR60. Meanwhile, the relative errors of aerodynamic parameters are less than 10%.