大高差变化区域GNSS高程转换模型与方法的优选

在地形起伏变化大的山区,基于GNSS技术实测的大地高和高精度几何水准实测的正常高数据,将线状拟合、平面拟合、曲面拟合等多种GNSS高程转换数学模型分别应用到GNSS/水准拟合法和EGM2008模型的"移去-恢复"法中,讨论了各模型方法在山区的高程转换应用情况及转换精度。利用Alltrans EGM2008 Calculator计算得到的地球重力场模型高程异常值,由于综合考虑了高程异常的几何和物理特性,使EGM2008模型的解算精度高于GNSS/水准拟合法精度。并通过实例证明,EGM2008"移去-恢复"法的曲面拟合模型适用于大高差山区cm级GNSS测高。     

层序成因动力学中的构造因素研究

本文以层序－盆地－构造为主线，对层序成因动力学中的构造控制进行了研究。结果表明，层序发育的构造控制主要表现为：1）构造控制盆地边界，进而控制层序充填轮廓；2）构造级次控制层序和层序级别；3)构造属性控制盆地性质，进而控制层序成因格架和界面成因类型；4)随着层序规模和界面级别的增大，构造控制的意义和痕迹越明显；5)同沉积断裂活动控制层序的内部构型；6)构造基底活动形式控制着层序容纳空间和结构型式；7)构造演化控制着盆地演化及性质，进而控制着层序充填样式和组合类型。     

分形理论在空间网络分布特征研究中的应用

探讨了以图论为基础的空间网络的测度方法,以及以分形理论为基础的表达空间网络分布特征的几种分维数,并阐述了各种分维数的地理意义,最后对于分维数的测算进行了评述.     

长江口北支上段岸滩侵蚀及保护实施效果分析

受上下游工程、来水来沙影响,长江口北支上段近期岸滩侵蚀后退严重。为揭示北支上段近期演变机理,控制河势变化和保护生态基底,收集2001年以来长江口北支全河道水下地形资料,并开展了2017—2020年工程区段水下地形精细实测,基于水动力数学模型研究了岸滩保护措施合理性,以分形理论评价了保护措施实施后效果。结果表明：①长江口北支进口江心洲发育,导致上段“S”形主轴弯曲度加大,加剧了暗沙、江心洲和岸滩动荡;②在冲刷最严重的岸滩采用丁坝群加护坎可有效阻止岸滩侵蚀后退;③多年水下地形实测和分形理论计算评价,岸滩趋于稳定,生态基底得以恢复。鉴于新江心沙洲发育和岸滩、深槽变化加剧了北支上段演变的复杂性,建议尽快成立综合协调部门,统筹提出满足水利、防洪、供水、航运、生态等多目标需求的综合整治方案。     

跨海高程传递方法的评价

针对跨海高程传递的最新进展,介绍了几种高程传递的实用方法,对优缺点和适用范围进行了分析与评价。初步试验结果分析表明,对于10km内的高程传递,几种方法均满足三等水准的精度要求,对于更远距离的跨海高程传递还需进一步研究。     

北斗区域系统国外典型地区定位性能分析

为掌握北斗区域系统在国外典型区域内的定位性能,利用STK软件仿真建立了该系统"5GEO+5IGSO+4MEO"星座,在此基础上对关岛、索马里、堪培拉等地区的卫星可见性和几何精度因子进行了系统分析。结果表明,北斗区域系统足以全天候满足上述区域内用户的导航定位需求。     

Airborne geometry correction method for marine multispectrum data without attitude information

Marine airborne multispectrum scanner (MAMS) onboard the China marine surveillance plane can be used to survey marine environment, resources and disaster and provide the technical support for high-frequency, high-efficiency and high-resolution remote sensing monitoring for the coastal management. MAMS did not have the IMU/POS equipment, so it brought severe challenge for the geometry correction. One airborne geometry correction method is introduced for marine multispectrum data without the attitude information. First, it is the coarse geometry correction, which simulates the roll angle and pitch angle of plane according to the ideal flying model; the second step is the precise geometry correction by using the SPOT orthogonal projected data as the reference of registration, based on maximization of alignment metric method. With the validation, relative error of coarse correction is 81.42 m compared with SPOT data, and 11.3 m for precise correction. This method provides the high precision localization information for the oceanic remote sensing and application, and establishes the foundation for monitoring the marine resource and environment.     

海杂波微弱目标分形检测

The target on the sea surface is complex and difficult to detect due to the interference of backscattered returns from the sea surface illuminated by the radar pulse. Detrended fluctuation analysis （DFA） has been used successfully to extract the time-domain Hurst exponent of sea-clutter series. Since the frequency of the sea clutter mainly concentrates around Doppler center so that we consider to extract frequency-do- main fractal characterization and then detect a weak target within sea clutter by using the difference of frequency-domain fractal characterization. The generalized detrended fluctuation analysis （GDFA） is more flexible than traditional DFA owing to its smoothing action for the clutters. In this paper, we apply the GDFA to evaluate the generalized Hurst exponent of sea-clutter series in the frequency domain. The difference of generalized Hurst exponents between different sea-clutter range bins would be used to determine whether the target exists. Moreover, some simulations with the real IPIX radar data have also been demonstrated in order to suooort this conclusion.     

海冰对北极海冰边缘区大洋光学观测的影响评估

Diffuse attenuation coefficient(DAC) of sea water is an important parameter in ocean thermodynamics and biology, reflecting the absorption capability of sea water in different layers. In the Arctic Ocean, however, sea ice affects the radiance/irradiance measurements of upper ocean, which results in obvious errors in the DAC calculation. To better understand the impacts of sea ice on the ocean optics observations, a series of in situ experiments were carried out in the summer of 2009 in the southern Beaufort Sea. Observational results show that the profiles of spectral diffuse attenuation coefficients of seawater near ice cover within upper surface of 50 m were not contaminated by the sea ice with a solar zenith angle of 55°, relative azimuth angle of 110°≤φ≤115° and horizontal distance between the sensors and ice edge of greater than 25 m. Based on geometric optics theory, the impact of ice cover could be avoided by adjusting the relative solar azimuth angle in a particular distance between the instrument and ice. Under an overcast sky, ice cover being 25 m away from sensors did not affect the profiles of spectral DACs within the upper 50 m either. Moreover, reliable spectral DACs of seawater could be obtained with sensors completely covered by sea ice.     

1995—2017年福建省海岸线时空变化分析

利用遥感影像和GIS技术相结合获取福建省1995、2001、2010、2017年共4期海岸线的时空分布情况,并结合网格法计算各时期海岸线的分形维数,结合获取数据分析海岸线的时空变化特征、海岸线长度变化与分形维数变化之间的关系以及影响海岸线变化的原因.结果表明:1995—2017年福建省海岸线长度呈持续增加趋势,共增加3...