基于矩阵乘法的可压缩门限图像共享方案

基于矩阵乘法秘密共享思想,提出了一种新的可压缩的图像秘密共享方案.本方案利用可压缩矩阵乘法算法直接生成影子图像,有效地克服了秘密图像需进行置乱预处理的缺陷,并且方案的复杂度较低.本方案生成的影子图像仅为原秘密图像的1/t,有效地压缩了影子图像的尺寸.     

基于SWAT模型模拟乌江三岔河生态系统产流服务及其空间变异

产流是生态系统水源涵养服务的重要内容,也是保水固土等服务的关键驱动。脆弱的喀斯特生态系统叠加人类活动的影响引起生态退化,在此背景下亟需深刻理解喀斯特地区产流服务空间格局及其影响因子。选择典型的喀斯特峰丛洼地流域,基于率定校准的SWAT水文模型,对喀斯特流域产流服务（包括地表、地下以及总径流量）进行模拟,并结合空间梯度分析和局部回归模型,剖析不同服务变量的空间变异特征。结果表明：研究区产流量空间分异规律明显,总径流系数约为70.0%;地表径流整体处于较低水平,地下径流量丰富（约为地表径流量的2~3倍）。地形因子对喀斯特流域产流服务具有宏观控制作用,随海拔和坡度升高,总径流量、地下径流量显著增加;植被分布特征对地表径流有重要影响,在上游林地和下游园地分布区存在空间差异,在植被因素的影响下随坡度的增加呈现转折性的变化趋势。此外,空间叠加分析表明林地总径流及地下径流最大：一方面是由于森林生态系统更强的土壤水分涵养能力以及水分快速入渗的地质背景特征;另一方面反映了地表覆盖与地形特征的复合效应,即林地大多分布在相对海拔和坡度较大之处。本文有助于推进喀斯特生态系统服务研究领域的发展与创新,并为生态恢复建设提供科技支撑。     

海洋环境大数据系统建设研究进展

海洋环境大数据是诸多学科研究领域的基础,也是实施海洋强国战略和建设海洋强国奋斗目标的先决条件。文章从全球海洋环境观测计划及系统出发,探讨现阶段全球海洋环境大数据观测、国家数据库建设、数据质控方法以及数据应用现状,阐明了海洋环境大数据在国家发展中的重要性,客观地分析了目前海洋环境大数据发展在基础设施、数据处理及数据质控能力建设等方面面临的关键问题与挑战,以期为将来海洋环境大数据在多尺度、多学科、多行业的深入发展与深度融合提供可靠的资料与建议。     

陕西2次强飑线天气卫星云图特征分析

通过对2003和2004年6月发生在陕西的2次强飑线天气的卫星云图特征进行分析,发现影响陕西的2次强飑线天气均出现在冷涡云系后部的晴空区,单个云团的水平尺度最大约在200~250km左右,16—18时为飑线最强盛阶段。飑线云带距冷涡云系后边界的距离,是影响强飑线天气降水强弱的一个因素。对此类灾害性天气的预报有一定指示意义。     

关于端基分析法测定壳低聚糖的相对数均分子质量问题的探讨

为使端基分析法更具合理性。文中以铁氰化钾为显色剂。以盐酸氨基葡萄糖和N-乙酰基-D-葡萄糖胺为还原糖的标准品,建立了端基分析法测定低聚糖相对数均分子质量的标准曲线。实验结果证明：通过不同浓度的标准溶液绘制的标准曲线,测得壳低聚糖的相对数均分子质量差别比较大。以凝胶色谱法测定的相对数均分子质量为对照,经分析得：以盐酸氨基葡萄糖为标准品建立的标准曲线方程和以N-乙酰基-D-葡萄糖胺为标准品建立的标准曲线方程更为合理。     

THE FINE CRUSTAL STRUCTURE OF THE SOUTHERN MARGIN OF NORTH CHINA BLOCK REVEALED BY DEEP SEISMIC REFLECTION PROFILE

The study area is located at the junction of the northern margin of the Qinling orogenic belt and the southern margin of the North China Block. In order to study the fine crustal structure and the deep-shallow structural features of faults in this area, we conducted deep seismic reflection profiling with the seismic profile of 100km long, directing NE-SW in Zhumadian City, Henan Province, and got clear lithospheric structure images along the profile. As regards the data acquisition, we applied the geometry of 25m group interval, 1000 recording channels and more than 60 folds. Seismic wave exploding applies the 30kg shots of dynamite source with the borehole depth of 25m. The shot interval is 200m. In data processing, we focused on improving the signal-to-noise ratio. Data processing methods mainly include first break removal, tomographic static correction, abnormal amplitude elimination, amplitude compensation, pre-stack denoising, surface consistent deconvolution, velocity analysis, several iterations of the residual static correction, dip moveout, post-stack time migration and post-stack denoising, etc. The profile with high signal-to-noise ratio was obtained. The reflection wave group characteristics is obvious in the crust, which reflects abundant information about geological structure. Along the profile, the crust is characterized by double-layer reflection structure, and the Moho surface is composed of a series of laminated arc-shaped strong reflections. The thickness of the upper crust is about 14.8~20.7km, and the total thickness of the crust is about 32.0~35.1km. The upper crust is dominated by the inclined, densely stratified or arc-shaped reflections. The lower crust is dominated by arc-shaped and inclined reflection, and there is a reflective transparent zone under the Moho surface. The reflection sequences with different directions and shapes in the upper crust constitute the nappe structure in southwest segment and the structural model of two concaves with one uplift in NE segment, which correspond to the north Qinling nappe, Zhumadian-Huaibin depression, Pingyu-Xiping uplift and a secondary depression, respectively. There are abundant arc-shaped reflection sequences in the lower crust, which may represent multi-stage magmatic activities. The deep seismic reflection profile shows that faults in the upper crust are well developed. According to the characteristics of reflected wave field in the profile, four groups of fault structure which contain ten faults with different scales are interpreted. Among them, faults F_P1, F_P2 and F_P3 constitute the thrust fault system in the northern margin of Qinling Mountains, and F_P5 and F_P7 are boundary faults of Zhumadian-Huaibin depression. These faults are all developed within the upper crust. In addition, the Fault F_PM is a large fault that cuts through the lower crust and Moho surface. The deep seismic reflection profile reveals the crustal structure and deep-shallow structural features of faults at the junction of the northern margin of the Qinling orogenic belt and the southern margin of the North China block, which provides seismological evidence for the analysis of structural differences, the deep earth's interior processes and deep-shallow structural relationships between the Qinling-Dabie orogenic belt and the southern margin of the North China block. The lower crust of the study area is divided into two parts by deep faults that dislocate the Moho surface. These two parts have distinct reflective structures, suggesting that the area has experienced intense complex tectonic movements. The faults in the upper crust control the formation of basin-mountain structure and stratigraphic deposition of this area. And deep faults in the crust that disrupt Moho surface create conditions for the upwelling and energy exchange of deep materials. All of these have regulated the composition of material and the distribution of energy in the crust. The deep faults cutting through the lower crust and Moho surface and the south-dipping arc-shaped and inclined strong reflection sequences developed in the lower crust should indicate the large-scale subduction of the southern margin of the North China block towards the south-trending Qinling orogenic belt.     

内蒙古北山地区哈日阿玛岛弧花岗岩地球化学、年代学特征及其地质意义

哈日阿玛岛弧花岗岩出露于北山造山带公婆泉岛弧带内,与奥陶纪—志留纪公婆泉组弧火山岩伴生,包含闪长岩、石英闪长岩、斜长花岗岩、英云闪长岩等.LA-ICP-MS锆石U-Pb测年表明闪长岩、英云闪长岩分别就位于430.9±4.7 Ma和452.5±3.2 Ma,为晚奥陶世—早志留世.岩石地球化学分析结果显示,这些花岗岩属钙碱...     

基于动力学模态分解的200 hPa急流模态特征分析

提出基于动力学模态分解（Dynamic Mode Decomposition,DMD）的大气运动数据分析方法,目的是改进对大气运动特征的认识。首先,采用DMD方法对200 hPa急流运动流场进行模态分析,从中得到了急流天气系统运动变化过程中的主要模态和对应频率以及模态随时间衰减/增长等信息。这些模态是对流场演化特征的低维描述,反映了蕴含在流场中的动力学特征,可用于实现高维复杂流场的低维近似表示。其次,建立了200 hPa急流运动流场演化的动力学降阶模型,能够重构和预测急流运动流场的动态发展过程。结果表明：通过对前6阶主要模态所包含的流场信息进行对比分析,DMD方法成功捕捉到了200 hPa急流运动流场不同尺度的流动结构,直观地显示了不同频率流场之间的差别,表明了DMD方法在对复杂大气动力学系统进行模态分解时的优势。通过不同时刻,模态叠加的重构流场与真实流场的直观比较,表明DMD方法只由前面6阶模态就能基本包含原始流场的流动信息,从而实现流场的准确重构。     

苏北浅滩筏架附生绿藻群落结构变化及与环境因子的相关性探究

苏北浅滩是研究浒苔绿潮早期形成机制的重要区域,该区域紫菜养殖筏架上附生绿藻的群落结构变化对浒苔绿潮的发生具有重要影响,环境因素在其中发挥了重要作用.为了探明导致苏北浅滩绿藻群落结构变化的主要环境因素,本文通过分子生物学和种群生态学方法对筏架附生绿藻群落结构进行了研究,结果表明:(1)苏北浅滩筏架附生绿藻群落主要由浒苔(...     

小天体离散元仿真软件的搭建与测试

小天体探测是当今太阳系探测的一大热点, 对小行星演化的研究有助于人们了解太阳系的起源. 演化研究的一项重要内容是小天体结构的演化, 即小天体在多种力学机制作用下自身形状与结构的演化. 在小天体碎石堆结构的假设之下, 一种比较常见的模拟小天体结构演化的方法是离散元仿真算法(Discrete Element Method, DEM), 目前国内外有数个团队开发了相关算法软件. 本文介绍了团队开发的《基于DEM仿真算法的多粒子系统模拟软件》的基础理论、实现方法以及加速算法, 并使用二体接触模型、声速传播仿真、小行星内部压强、小行星旋转稳定性仿真算例验证了算法的可靠性.