城市景观遥感影像融合质量对小波基选取的响应

应用IHS和小波变换结合的融合算法时,小波基的选取是影响融合图像质量的关键,而且包含不同地物信息的影像融合质量对小波基的响应特征有待深入探讨。该文以SPOT全色和多光谱影像为数据源,选取大量高、低密度建筑城市景观影像样本,用信息量、平均梯度和偏差指数3个指标定量评价融合质量,分析不同小波簇下两类融合图像之间的质量差异。研究表明:融合质量与影像所含地物特征密切相关;相对于其它小波簇,rbioNr.Nd表现出较强的变异性;两类融合图像在各小波簇上的波动性差异明显,并呈分段特征;根据质量需求和具体景观特征影像,可以在分解层数固定的情况下选取最佳小波基,以获取高质量融合图像。     

NNFFC-adaptive output feedback trajectory tracking control for a surface ship at high speed

An adaptive output feedback controller based on neural network feedback-feedforward compensator (NNFFC) which drives a surface ship at high speed to track a desired trajectory is designed. The tracking problem of the surface ship at low speed has been widely investigated. However, the coupling interactions among the forces from each degree of freedom (DOF) have not been considered in general. Furthermore, the influence of the hydrodynamic damping is also simplified into a linear form or neglected. On the contrary, coupling interactions and the nonlinear characteristics of the hydrodynamic damping can never be neglected in high speed maneuvering situation. For these reasons, the influence of the nonlinear hydrodynamic damping on the tracking precision is considered in this paper. Since the hydrodynamic coefficients of the surface ship at high speed are very difficult to be accurately estimated as a prior, it will be compensated by NNFFC as an unknown part of the tracking dynamics system. The stability analysis will be given by the Lyapunov theory. It indicates that the proposed control scheme can guarantee that all the signals in the closed-loop system are uniformly ultimately bounded (UUB), and numerical simulations can illustrate the excellent tracking performance of the surface ship at high speed under the proposed control scheme.     

深水高弯度水道-堤岸沉积体系形态及特征

在海底扇研究及油气勘探中,不断发现一种形态类似曲流河的高弯度水道-堤岸沉积体系,其在形态及沉积特征方面与海底扇有较大差异.在国内外研究成果的基础上,结合对重力流的实际研究工作,对该体系的沉积模式及沉积特征等开展了进一步的研究,并从沉积环境、流体类型、形态等方面与曲流河进行比较.深水高弯度水道-堤岸沉积体系主要包括水道、...     

煤矿三维地震勘探技术发展趋势

我国煤田三维地震勘探经过20余年的发展,已成为当前煤田地质勘探的主流技术,随着煤矿采掘现代化及安全保障系统对勘探精度要求的提高,三维地震勘探技术也须与之相适应,不断地探索与发展。参考近年来相关研究成果与勘探实例,对可在煤田地质勘探中大面积推广应用的三维地震勘探技术进行了介绍,其中包括：高密度空间采样、数字检波器、高精度静校正技术、叠前时间（深度）偏移技术、分频解释技术、波阻抗反演技术、相干体技术,同时也简要介绍了在煤田勘探方面有发展前景的多分量及各向异性技术。     

基于高空间分辨率的红树林卫星遥感监测技术进展

卫星遥感技术是红树林生态系统监测的重要手段。文章系统地总结了红树林的光谱特征,给出了目前应用于红树林生态监测的高空间分辨率卫星包括IRS-P6、SPOT-5、IKONOS、OrbView-3、QuickBird的主要技术参数以及它们在红树林遥感监测中的应用程度,叙述了目视解译法、波段组合法、图像分类法、专家分类法、模糊分类法和面向对象分类法等遥感监测技术方法在红树林的生态参数包括类外区分和类内区分、生物量和健康状况等的遥感提取的应用和精度对比情况。另外,对应用高分辨率卫星遥感资料监测红树林的技术发展趋势进行了讨论。     

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The Cambrian metamorphic history of Tasmania: The Metapelites

The metamorphic complexes of Tasmania formed during the Cambrian (ca 510 Ma) as a result of rapid compression in a subduction zone setting followed by rapid exhumation, which brought various fault-bounded metamorphic complexes back to the surface in less than 5 Ma. The two highest grade complexes, the Franklin Metamorphic Complex, and the Port Davey Metamorphic Complex, experienced initial growth of metamorphic garnets at ～560°C, ～0.56 GPa. However, their subsequent metamorphic histories diverge, with the FMC displaying a marked increase in pressure (to 1.4 GPa at peak P/T), while the PDMC shows only a slight increase in pressure (to ～0.7 GPa). Both complexes show only a minor increase in temperature (～100°C) between initial garnet growth and peak metamorphic conditions. Rapid exhumation of these complexes can be accounted for by a slab-breakoff model. However, the difference in peak pressure between these complexes requires either continued subduction of the FMC while the PDMC had already begun its return towards the surface or that the subduction zone geometry resulted in significantly different pressures occurring contemporaneously within portions of the channel, which are not far removed from one another.     

时空域相关性的快速HEVC帧问模式判决方法

高性能视频编码（HEVC）相比目前的国际视频编码标准H．264／AVC有着更高的视频压缩比,但同时也带来了更大的编码计算复杂度。为了降低该计算复杂度,提出了一种快速HEVC帧间预测模式。统计了HEVC中最大出现概率的预测单元（PU）模式,分析了相邻两帧之间的编码单元（CU）和Pu之间的时域相关性,分析了对应CU分块与其空间上相邻的4个CU之间的相关性。根据分析的最大出现概率的Pu模式,以及时域相关性和空域相关性,跳过当前最大编码单元中各层CU中冗余的Pu模式,从而降低了编码的计算复杂度。实验结果显示,与HEVC测试模型HM7．0相比,该算法能在保持视频质量和视频压缩比基本不变的情况下,降低32．2％～52．4％的编码时间。     

一个储量可再生的石油地质模型

最新石油地质基础研究表明,目前正在开采的油气藏可能存在大规模的油气补充,以往勘探地质模型、开发地质模型、三次采油地质模型都没有考虑到储量可增长的因素,可能需要修正。建议国家有关部门设立专项研究,以期为油气勘探开发部署和后期调整提供可靠的地质依据。     

夏季副高与海温的相互关系及副高预测

通过分析夏季西太平洋副高与前期12月至后期11月的赤道太平洋和北太平洋海温的相关系数分布图,综合比较副高面积指数、西伸脊点和脊线位置与海温的相关关系,讨论副高对海温的反馈作用以及海温与夏季副高的物理联系模型,为副高预测提供依据.