基于样图的肝脏体纹理合成与映射方法

为了能够在虚拟手术仿真系统中,可以清楚地看到肝脏的内部真实情况,增强用户的视觉临场感,将体纹理的原理与方法引入到肝脏的真实感绘制中。首先对样本集进行了处理,采用多样本的体纹理合成方法合成肝脏体纹理。其次,为了提高图形硬件的映射效率,将纹理地图集引入体纹理的映射中,采用基于三角形包围盒高度递减排序的方法填充纹理地图集,提高了纹理地图集的填充率。实验结果表明,映射之后的肝脏模型能够清晰地展示肝脏的内部纹理结构。研究成果对于虚拟肝脏手术的真实感绘制具有重要的意义,也为其它人体器官的体纹理合成与映射提供了思路。     

基于矢量量化压缩的大规模体数据直接绘制

针对大规模体数据通常不适合于硬件三维纹理加速绘制的问题,使用基于区域分裂的LBG算法对大规模体数据进行矢量量化压缩,使得其压缩编码适合硬件纹理空间大小.并在图形硬件的可编程渲染器中对压缩后的三维纹理体数据进行实时地矢量解码和绘制,在解码过程中通过设定掩码纹理给出了大规模体数据的局部感兴趣区域的体绘制.实验结果表明,在不同压缩比和信噪比下,大规模体数据绘制的图像仍然具有较高的质量且维持高帧速率,绘制性能满足实时交互.     

结合网格编码量化的小波包纹理图像压缩算法

为了提高对纹理丰富图像的压缩效果，首先用小波包变换对纹理丰富的图像进行完全分解，再用一种与后续编码器相关联的代价函数进行最佳基搜索，以提高对纹理图像的表达能力。为了提高编码算法的率－失真性能，对搜索出来的最佳基所对应的小波包系数采用变块尺寸方法进行分类，再对分类结果采用网格编码量化器进行量化，最后对量化结果进行熵编码。仿真结果表明，所构造的编码器与SPIHT算法相比，峰值信噪比提高了0．5－2dB，可用于对指纹、遥感等图像的压缩。     

基于小波和匹配跟踪的分层图像编码算法

提出了一种基于小波和匹配跟踪的分层图像编码算法. 该算法将原始图像划分成包含不同结构特征的平滑边缘层和纹理层,采用不同的压缩算法对不同的图像层进行编码,从而达到对整幅图像最优编码的目的. 实验结果表明,该算法不仅能够有效地捕捉图像中所包含的边缘和纹理等具有高频窄带的信号特征,而且在极低位率下的重建图像质量要优于单一小波图像编码算法.     

图像纹理分析与纹理测度

为了从更深层次上进行系统的纹理分析 ,首先概括了纹理分析中的困难并从寻找纹理的本质入手 ,回答了纹理图像与普通数字图像间的差异、成像尺度与图像纹理间的关系、窗函数的选取等问题并给出了计算一幅具体图像纹理性大小的算法。从采样频率和成像尺度的角度来看待图像纹理在该领域内尚属首次。仿真实验对Brodatz像册中全体纹理图求取了纹理性因子的大小并进行了排序 ,试验表明该求取纹理性因子的算法与视觉感受趋于一致。对图像纹理理论探讨的欠缺是纹理分析的瓶颈 ,该文是在一这方面努力尝试的结果     

基于主动表观模型的人脸图像描述与编码

利用主动表观模型(AAM)来对人脸图像进行描述和编码,该方法不仅对人脸形状进行建模,同时又建立了反映人脸灰度变化的纹理模型,并将纹理模型与形状模型合理地结合起来,反映了整个人脸形状及纹理。实验表明了AAM方法进行人脸描述和编码的有效性。     

基于多分辨率小波和高斯混合模型的纹理图像分割

提出了一个基于多分辨率小波采样和高斯混合模型的纹理图像分割方法。该方法首先对图像进行必要的预处理,然后对图像进行小波“金字塔”分解。分解后的小波系数和图像共同组成了相应像素的特征向量,然后利用高斯混合模型进行分割。分割的实验结果表明,该算法具有较强的分割能力。     

基于分维特征的肝脏CT图像识别

目前分形理论已被广泛应用于医学图像识别.本文利用了改进的差分盒计数法对肝脏CT图像进行了分形维数的分析,表征了肝脏图像的纹理特征,则可识别医学图像肿瘤信息.医学图像识别的结果可以直观的方式显示给临床医生,从而辅助医生提高医疗诊断的准确性和科学性.     

图像纹理特征的提取方法

纹理特征是图像分析的重要线索,纹理特征的提取方法层出不穷,本文重点介绍了几种借助纹理统计特性的提取方法,并对其算法进行了比较.这些方法包括:1、基于图像灰度直方图的特征提取;2、基于图像灰度差值直方图的特征提取;3、基于图像灰度共生矩阵的特征提取.     

基于Curvelet和小波变换的纹理图像识别

提出了一种基于Curvelet变换与小波变换相结合的纹理图像分类算法.小波变换在分析点奇异信号时具有良好的性能,而Curvelet变换更适合分析图像中的曲线或直线状边缘特征.算法通过提取两者分解子波段的统计学和灰度共生矩阵特征,采用支持向量机对纹理图像进行分类.实验结果表明,和单一的多分辨率变换特征提取相比,该算法具有更高的分类准确率.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.