The technique of quasi-lossless compression of the remote sensing image

In this paper, the technique of quasi-lossless compression based on the image restoration is presented. The technique of compression described in the paper includes three steps, namely bit compression, correlation removing and image restoration based on the theory of modulation transfer function (MTF). The quasi-lossless compression comes to a high speed. The quality of the reconstruction image under restoration is up to par of the quasi-lossless with higher compression ratio. The experiments of the TM and SPOT images show that the technique is reasonable and applicable.     

Spatial and temporal change in landslide hazard by future climate change scenarios using probabilistic-based frequency ratio model

The aims of this study were to apply, verify and compare a frequency ratio model for landslide hazards, considering future climate change and using a geographic information system in Inje, Korea. Data for the future climate change scenario (A1B), topography, soil, forest, land cover and geology were collected, processed and compiled in a spatial database. The probability of landslides in the study area in target years in the future was then calculated assuming that landslides are triggered by a daily rainfall threshold. Landslide hazard maps were developed for the two study areas, and the frequency ratio for one area was applied to the other area as a cross-check of methodological validity. Verification results for the target years in the future were 82.32–84.69%. The study results, showing landslide hazards in future years, can be used to help develop landslide management plans.     

利用重力/地形导纳和岩石圈单一薄层模型的月球物理参数反演

针对月震数据分布不均,传统反演方法不易搜索全局最优解等问题,提出联合使用重力/地形导纳和非线性粒子群PSO算法同时反演月球物理参数的方法。结果表明,该方法构建的表面地形载荷模型和内部异常密度载荷模型合理,粒子群PSO算法能同时求解月球物理参数及其全局最优解.将方法运用于月球物理参数的反演,可为月球内部结构研究提供一定的参考。     

抛物线拟合的高斯投影长度比计算方法

针对传统的高斯投影长度比计算公式存在的次数高、参数多、计算过程复杂等不足,该文提出利用抛物线拟合法计算高斯投影长度比。首先,对高斯投影规律进行全面分析,得出高斯投影长度比与距离中央子午线横坐标值的变化成抛物线关系。然后,以点在高斯平面直角坐标系中距离中央子午线的横坐标值为参数计算高斯投影长度比。实验结果表明,采用该文方法计算高斯投影长度比运算简便、精度高,与传统公式计算的长度比差值在整个高斯投影带均达百万分之一量级,对完善高斯投影长度变形规律的研究以及实际计算均具有一定的参考价值。     

极化SAR影像弱散射地物统计分类

针对Wishart分类器对功率具有较强的依赖性, 不易区分极化SAR影像上水体、道路、裸土、阴影等弱后向散射地物的问题, 提出一种利用极化目标分解和假设检验的弱散射地物统计分类方法。即在H-α初始化的基础上, 使用似然比检验得出像元与每个类中心的相似性, 并将其作为像元与类中心的距离测度。根据第一类错误概率和统计量的概率分布, 将相似性很小的强散射点归为拒绝类, 减少对分类的影响;对不能显著拒绝的像元归入具有最小统计量的类别中。通过使用E-SAR L波段和Radarsat-2 C波段全极化数据进行实验, 结果表明本文方法有利于弱散射地物极化信息的利用, 能够实现水体、道路、裸露的土壤和阴影等的精确分类。     

THE TECHNIQUE OF QUASI-LOSSLESS COMPRESSION OF THE REMOTE SENSING IMAGE

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利用接收函数、背景噪声频散和Rayleigh波ZH振幅比联合反演青藏高原东北缘及周边地区地壳结构

本文对在青藏高原东北缘及邻近地区架设的571套宽频带流动地震台站记录到的连续波形数据进行处理,通过联合反演P波接收函数、背景噪声频散和Rayleigh波ZH振幅比,获得了研究区高分辨率三维地壳S波速度（V_S）结构.研究结果显示,松潘—甘孜块体和西秦岭造山带以及北祁连造山带下方15~40 km的深度范围内存在很显著的S波低速异常体.其中,松潘—甘孜块体和西秦岭造山带下方的低速异常体很可能与部分熔融有关,且造成部分熔融的原因除了剪切加热外,还有可能是软流圈物质上涌和地壳内部的放射生热.而北祁连造山带的低速异常体则可能由地表隆升和地壳增厚所造成.阿拉善块体内部分布有很多不太显著的低速异常体,这可能与阿拉善块体经历了复杂的构造变形有关.在银川—河套地堑下方20~35 km的深度范围内同样观测到了相对不太显著的低速异常体,这更可能与基性岩浆的底侵作用有关.

     

Simultaneous measurements of compressional wave and shear wave velocities, Poisson's ratio, and Vp/Vs under deep crustal pressure and temperature conditions: Example of silicified pelitic schist from Ryoke Belt, Southwest Japan

The ultrasonic technique for measuring travel times of compressional and shear waves using dual-mode transducers was adapted to a piston cylinder apparatus, allowing simultaneous measurements of travel times of compressional and shear waves of island arc samples under the high pressure and temperature conditions of island arcs. This method enables us to determine elastic properties and their pressure and temperature derivatives simultaneously. Furthermore, Vp/Vs can be directly determined from travel times of compressional and shear waves independently of length change due to compression or thermal expansion of rock samples under deep crustal conditions, providing more accurate Vp/Vs values than those determined from individual measurements of travel times of both elastic wave types using single-mode transducers. Experimental techniques and results are demonstrated using data on silicified pelitic schist from the Ryoke Belt to 0.6 GPa. The simultaneous measurement gives Vp  = 5.60 km/s, ∂ Vp /∂ P  = 0.090 (km/s)/GPa, Vs  = 3.37 km/s, ∂ Vs /∂ P  = 0.05 (km/s)/GPa, σ  = 0.216, and Vp / Vs  = 1.66 at ambient conditions. The temperature derivatives were constrained from fitting using linear functions of temperature, yielding ∂ Vp /∂ T  = −0.518 × 10⁻³ (km/s)/K and ∂ Vs /∂ T  = −0.182 × 10⁻³ (km/s)/K. Performing simultaneous measurements of travel times of compressional and shear waves using dual-mode transducers, it is possible to accurately determine Vp / Vs and Poisson's ratio of crustal minerals and rocks at deep crustal conditions to study the composition of the crustal interior, e.g. rock types and fluids below the hypocentral region of earthquakes or around bright spots.     

后土桥台数字化地磁前兆异常的研究

利用后土桥台地磁数字化资料,分析了磁通门所观测的分钟值日变形态,计算了5日幅值比和日幅值比。结果显示,往往地震前5日幅值比会出现高值异常,同时日幅值比也会出现一簇异常,且有逐渐增高趋势。结果表明,利用地磁数字化的高频资料进行地震短临预测预报具有一定的意义。