基于亚像素图像平移叠加提高大倾角同步卫星信噪比的方法研究          下载免费PDF全文

欧阳旖旎  罗浩  唐正宏  李岩  王瑞 《天文学报》2021,62(4):43

大倾角地球同步轨道(GEO)卫星相对地面并非完全静止,其星下点做南北方向的"8"字周期运动,倾角越大运动范围越大.这会降低地面望远镜对其进行凝视观测时的有效曝光时间,无法获得较高的信噪比.对地球同步轨道的监测中,在硬件条件不变的前提下,提出亚像素图像平移叠加方法.根据目标的运动速度和相邻帧图像的时间间隔,在亚像素尺度平移并对齐多幅图像,使GEO目标星象在图像序列中的位置重合,通过叠加多幅序列图像来提高目标信噪比,从而达到提升整个系统探测能力的目的.实测图像叠加结果表明,该方法可以显著提高该类目标的信噪比.叠加5幅图像时,整数像素叠加图像的信噪比约为原图像的1.7倍,而亚像素叠加图像的信噪比是原图像的2倍左右.  相似文献   

Tectonic implications of paleomagnetic data from upper Cretaceous sediments in the Oyubari area, central Hokkaido, Japan     

Machiko  Tamaki  Yasuto  Itoh 《Island Arc》2008,17(2):270-284

Abstract   Paleomagnetic studies provide constraints on the geometric configuration of the eastern Eurasian margin on geological time scales. Characteristic remanent magnetization components were isolated from eight sites by progressive demagnetization executed on samples from 25 sites in the Oyubari area, central Hokkaido where the Late Cretaceous Yezo Group is distributed. After tilt-correction, all sites show normal polarity site-mean directions, and well-clustered directions pass a positive fold test and a correlation test. Planktonic foraminifera indicate an age range of Cenomanian to Turonian, and the studied section is correlated to the geomagnetic polarity chron C34n. Reliable formation-mean directions that have been corrected for post-depositional shallowing (D = 7.5°, I = 65.9°, α₉₅ = 6.6°) are characterized by inclination data indicative of no significant latitudinal translation since the Late Cretaceous. Central Hokkaido has, therefore, been situated adjacent to easternmost Mongolia including Sikhote Alin around the present latitude since the Late Cretaceous. Declination data require significant differential rotation between Hokkaido and the eastern Asian margin, which may be indicative of rearrangement of crustal blocks along the continental margin.  相似文献   

输电线路倾斜铁塔原位加固纠偏关键技术研究   总被引：1，自引：0，他引：1  

刘毓氚  刘祖德 《岩土力学》2008,29(1):173-176

输电线路铁塔属高耸结构,不同于一般建筑物,输电线路电塔加固纠偏有其特殊性。结合厦门电业局所辖110 kV输电线路倾斜铁塔加固纠偏工程实例,深入探讨了输电线路倾斜铁塔加固纠偏关键技术。分析了铁塔倾斜原因,应用FEM技术研究基础倾斜对塔身的应力和变形的影响机制,分析了倾斜铁塔的健康状况,在此基础上提出经济有效的加固纠偏设计方案;对加固纠偏设计计算方法、加载控制指标分析及信息化施工控制等关键技术展开了讨论,并指出需要进一步研究的问题。  相似文献   

三维测量光流恢复算法结合BIM对震后建筑倾斜度测量的研究          下载免费PDF全文

谷伟  董婧蒙 《地震工程学报》2019,41(4):1086-1091

震后危险建筑倾斜度的移动测量过程较为复杂,常规测量方法会存在对称偏差。为了提高震后危险建筑倾斜度测量的准确性,设计三维测量光流恢复算法结合BIM的震后建筑倾斜度测量方法。采用BIM技术采集并整合全部建筑倾斜度信息,构建危险建筑信息模型;采用三维测量光流恢复算法获取所构建建筑信息模型内多个目标特征点,设计震后危险建筑倾斜度的三维测量模型。仿真实验说明,所提方法测量震后危险建筑三维坐标值误差率均小于0.4%,平均评估时间仅为2.5 s,说明该方法可提高建筑倾斜度评估效果。  相似文献   

改进的斜导数方法及应用   总被引：4，自引：2，他引：2  

郭华  于长春  吴燕冈 《物探与化探》2009,33(2):212-216

系统阐述了斜导数方法在边界提取上的优势,在此基础上又提出新的概念——非绝对值斜导数的水平导数,对研究地质体的产状问题有了新的认识。针对这一新方法进行了理论模型设计,指出了斜导数方法存在的问题。运用斜导数方法对某地区重力数据进行研究,得到比较理想的结果。  相似文献   

Influence of inclination angles and confining pressures on mechanical behavior of rock materials containing a preexisting crack     

Cheng Zhao  Yimeng Zhou  Qingzhao Zhang  Chunfeng Zhao  Hiroshi Matsuda 《国际地质力学数值与分析法杂志》2020,44(3):353-370

To deeply understand the cracking mechanical behavior of brittle rock materials, numerical simulations of a rock specimen containing a single preexisting crack were carried out by the expanded distinct element method (EDEM). Based on the analysis of crack tips and a comparison between stress- and strain-based methods, the strain strength criterion was adopted in the numerical models to simulate the crack initiation and propagation processes under uniaxial and biaxial compression. The simulation results indicated that the crack inclination angle and confining pressure had a great influence on the tensile and shear properties, peak strength, and failure behaviors, which also showed a good agreement with the experimental results. If the specimen was under uniaxial compression, it was found that the initiation stress and peak strength first decreased and then increased with an increasing inclination angle α. Regardless of the size of α, tensile cracks initiated prior to shear cracks. If α was small (such as α ≤ 30°), the tensile cracks dominated the specimen failure, the wing cracks propagated towards the direction of uniaxial compression, and the propagation of shear cracks was inhibited by the high concentration of tensile stress. In contrast, if α was large (such as α ≥ 45°), mixed cracks dominated the specimen failure, and the external loading favored the further propagation of shear cracks. Analyzing the numerical results of the specimen with a 45° inclination angle under biaxial compression, it was revealed that lateral confinement had a significant influence on the initiation sequence and the mechanical properties of new cracks.  相似文献   

前方交会在建筑倾斜和水平位移监测中的应用探讨     

凌锋  薛世新 《现代测绘》2011,34(2):38-41

本文简单叙述了如何使用三种前方交会法测定房屋倾斜和水平位移时的成果计算和精度分析,并对前方交会测点时的最佳交会图形进行了案例分析,得出了一些实践结论。  相似文献   

钻孔灌注桩成孔质量检测技术开发应用研究   总被引：1，自引：0，他引：1       下载免费PDF全文

胡朝彬  王宝勋  罗冬华  刘圣勋  宋冠樟  张维国 《探矿工程》2014,41(8):46-49

充分利用JJC-1D型钻孔灌注桩成孔质量检测系统,对所测孔径范围进行了扩展,运用分方位四次测量法提高了孔斜度检测精度,并通过实测泥浆电阻率、沉渣（大浓度泥浆）的电阻率,进行试验室研究、对比、分析,形成了检测沉渣厚度的经验参数,取得了较好的应用效果。  相似文献   

The Role of the Inclination in the Captures in External Resonances in the Three Body Problem     

Sylvie Jancart  Anne Lemaitre  Vincent Letocart 《Celestial Mechanics and Dynamical Astronomy》2003,86(4):363-383

Interested in the role of the inclination in our results (Jancart and Lemaitre, 2001), we analyze the process of resonance trapping due to general dissipation forces in the frame of the spatial restricted three body problem and in the case of external mean motion resonances. We compute our simulations by using the three-dimensional Extended Schubart Averaging integrator developed by Moons (1994) for all mean motion resonances. We complete it by adding the averaged contributions of general dissipative forces like Murray has proposed in the article (1994). The behavior of the inclination is especially pointed out.  相似文献   

受控定向孔钻进用自动导航系统的分析研究          下载免费PDF全文

汤凤林  赵荣欣  周欣  段隆臣  Чихоткин В.Ф. 《探矿工程》2022,49(2):67-76

钻探工程中常用受控定向孔钻进。在受控定向孔钻进中,及时了解并掌握钻孔顶角、方位角、造斜器安装角度和孔底实时位置（孔深）等参数非常重要。俄罗斯钻探工作者研发的定向钻进用信息、工艺、自动导航集身于一体的自动导航,对于提高定向钻进效率、保证钻孔质量、提高钻探技术经济指标具有重要意义,值得我们参考。  相似文献