Single-step continuous-tone computer-generated holograms

A method of computing and recording a continuous-tone hologram is described in the letter. Certain limitations of binary computer generated holograms, arising from coarse quantisation of amplitude and phase, are overcome in this simple single-step technique.     

约束Delaunay四面体剖分

文章研究了约束Delaunay四面体网格生成算法,引入了优化的网格算法,提高了四面体剖分单元的质量;重点研究了指定区域的边界边与边界面的一致性这两个Delaunay三角化算法迫切需要解决的关键性问题。结果表明,文章提出的约束Delaunay三角化算法适用性、效率及网格单元质量等方面都得到了提高,且该算法易于实现。     

Single-step digital backpropagation for nonlinearity mitigation

Nonlinearity mitigation based on the enhanced split-step Fourier method (ESSFM) for the implementation of low-complexity digital backpropagation (DBP) is investigated and experimentally demonstrated. After reviewing the main computational aspects of DBP and of the conventional split-step Fourier method (SSFM), the ESSFM for dual-polarization signals is introduced. Computational complexity, latency, and power consumption of DBP based on the SSFM and ESSFM algorithms are estimated and compared. Effective low-complexity nonlinearity mitigation in a 112 Gb/s polarization-multiplexed QPSK system is experimentally demonstrated by using a single-step DBP based on the ESSFM. The proposed DBP implementation requires only a single step of the ESSFM algorithm to achieve a transmission distance of 3200 km over a dispersion-unmanaged link. In comparison, a conventional DBP implementation requires 20 steps of the SSFM algorithm to achieve the same performance. An analysis of the computational complexity and structure of the two algorithms reveals that the overall complexity and power consumption of DBP are reduced by a factor of 16 with respect to a conventional implementation, while the computation time is reduced by a factor of 20. Similar complexity reductions can be obtained at longer distances if higher error probabilities are acceptable. The results indicate that the proposed algorithm enables a practical and effective implementation of DBP in real-time optical receivers, with only a moderate increase in the computational complexity, power consumption, and latency with respect to a simple feed-forward equalizer for bulk dispersion compensation.     

Matlab程序单步调试方法及样例分析

针对单步调试法在程序调试中的重要作用,引用了一个具体的样例,进行Matlab程序单步调试法的分析并逐步检验,根据运行结果与实际计算结果的比较,验证了该方法在程序调试中的重要地位,并且该实验结果还可以应用于复杂的算法验证中,具有很大的实用意义。     

Application-layer multicasting with Delaunay triangulation overlays

Application-layer multicast supports group applications without the need for a network-layer multicast protocol. Here, applications arrange themselves in a logical overlay network and transfer data within the overlay. We present an application-layer multicast solution that uses a Delaunay triangulation as an overlay network topology. An advantage of using a Delaunay triangulation is that it allows each application to locally derive next-hop routing information without requiring a routing protocol in the overlay. A disadvantage of using a Delaunay triangulation is that the mapping of the overlay to the network topology at the network and data link layer may be suboptimal. We present a protocol, called Delaunay triangulation (DT protocol), which constructs Delaunay triangulation overlay networks. We present measurement experiments of the DT protocol for overlay networks with up to 10 000 members, that are running on a local PC cluster with 100 Linux PCs. The results show that the protocol stabilizes quickly, e.g., an overlay network with 10 000 nodes can be built in just over 30 s. The traffic measurements indicate that the average overhead of a node is only a few kilobits per second if the overlay network is in a steady state. Results of throughput experiments of multicast transmissions (using TCP unicast connections between neighbors in the overlay network) show an achievable throughput of approximately 15 Mb/s in an overlay with 100 nodes and 2 Mb/s in an overlay with 1000 nodes.     

2008年度创意

[GLOBUS] GLOBUS是一个不错的移动办公平台。底座下安装有滑轮可以任意推动,当圆球打开后就形成了一个旋转座椅和一个半遮的笔记本电脑工作台。对于拥有小户型房间的人来说也是值得考虑的电脑桌。     

Single-step buried waveguides in glass by field-assisted copper ion-exchange

Symmetric profile buried waveguides can be fabricated in glass by single-step electromigration of Cu/sup 2+/ ions from thin solid films. The theory of this process is given. The controllable process needs a molten multi-ionic anode to keep the glass surface background composition unchanged.<>     

基于Delaunay 三角化的有效角点匹配算法

基于同一幅图像角点集Delaunay三角形网的唯一性和相同场景不同视角图像角点的Delaunay三角形网的相似性,本文提出了一种改进的SUSAN角点检测算法和基于Delaunay三角化的角点匹配算法,同时提出了一个模糊阈值的三角形相似度计算方法。对实际图像的实验结果表明了本文的算法对有视角变化的平移、缩放和旋转图像的有效性。     

一种基于DT分割及自适应DCT的图像编码方法

提出了一种结合ＤＴ（Ｄｅｌａｕｎａｙ Ｔｒｉａｎｇｕｌａｔｉｏｎ）分割及任意形状自适应ＤＣＴ（ＳＡＤＣＴ）的图像编码方法。使用基于图像内容的ＤＴ分割及ＤＴ内的线性插值来逼近原始图像,然后在每一ＤＴ三角形内使用ＤＣＴ变换来编码逼近误差。模拟结果表明：与传统的ＤＣＴ方法相比,这种编码方法明显改善了恢复图像的质量     

一种新的带特征约束的Delaunay三角剖分算法

本文提出了一种新的带特征的约束条件的散乱数据Delaunay三角剖分算法.本算法通过在特征线上加入若干数据点,使得在保留特征线的同时,最终的剖分结果也满足全局Delaunay特性.与现有同类算法相比,本算法更充分地利用了Delaunay三角剖分中的圆准则,从而大大减少了所需加入的附加点数.实验结果证实了本算法的这一特性.     

Automatic mesh generation using a modified Delaunay tessellation

The authors begin by discussing the Delauny triangulation and algorithms for its construction. Degeneracy and the convexity check are then considered together with the preservation of edge boundaries. Swapping in two and three dimensions, edge subdivisions, mesh smoothing techniques and the mesh generation algorithm are also discussed     

基于德劳内三角剖分的彩色图像加权直方图表示及检索技术

经典的颜色直方图方法存在诸多缺陷，例如它不能表示图像中颜色的空间分布信息。为了进一步的提高图像检索能力，在分析图像特征的基础上，文章给出了一种基于角度图的直方图加权的图像表示方法。这种方法不仅保持了图像直方图简单方便的特点，同时又有效地将颜色的空间分布信息集成到直方图中。实验结果表明，对比经典直方图表示这种彩色图像的表示方法能获得更好的检索效果。     

结合Delaunay三角网的图像分割

为了有效消除图像噪声影响,提出结合Delaunay三角网的图像分割方法。首先,将像素灰度看作定义在像素格点上的‘高程’,并在此三维图像表达上构建Delaunay三角网,该三角网在图像域上的投影将图像域划分成若干个子区域,形成超像素,再对每个子区域内像素灰度值做均值化处理,由此将原图像转换为均值图像;最后在均值图像上进行图像分割,可以很好地削弱噪声对图像分割的影响。采用本文思想,基于Intel(R) Core(TM) 3.20GHz/2G内存/Matlab2015a平台,以经典的模糊C均值（Fuzzy C-means, FCM）图像分割算法为例,分别对Berkeley标准测试图像和遥感图像进行了分割实验。生成一幅具有三个同质区域的模拟图像,分别采用对比算法和本文算法对模拟图像进行分割测试,对比算法1（基于ENVI平台的ISODATA分割算法）的三个同质区域（1-3）的用户精度、产品精度、总精度和Kappa值分别为74.87%/55.72%/73.64%、83.98%/37.87%/85.38%、70.25%和0.54;对比算法2（基于中值滤波的FCM分割方法）的三个同质区域（1-3）的用户精度、产品精度、总精度和Kappa值分别为98.16%/70.54%/99.73%、88.10%/99.16%/87.87%、89.93%和0.84;本文算法的三个同质区域（1-3）的用户精度、产品精度、总精度和Kappa值分别为96.25%/80.35%/99.49%、99.76%/94.53%/86.67%、93.30%和0.89。定性和定量的测试结果验证了本文方法的有效性、可靠性和准确性。      

Delaunay三角形剖分约束下的图像配准算法

针对一般的特征点匹配只考虑了特征点本身蕴含的信息,容易发生误匹配的问题,给出一种基于Delaunay三角形剖分(Delaunay Triangulation, DT)的图像匹配算法。该算法对参考图和感知图中可能的正确匹配点进行DT剖分,对剖分后的图形进行对比并找出一致的结构,进而得到正确匹配点。实验结果表明该算法可以有效地抑制SURF（Speed Up Robust Feature,SURF）中的错误匹配,增强匹配可靠性,与RANSAC（Random Sample Consensus, RANSAC）法相比,可以大幅缩短计算时间,在基于点的图像配准方面具有较高的应用价值。      

基于Delaunay三角网模型的点军标群聚合显示方法

从视觉分辨原则出发,以空间邻近图为支撑几何构造,提出点状军标群聚合显示新方法。该方法首先以Delaunay三角网为工具,计算点状军标群空间邻近关系,生成空间邻近图,而后基于利用视觉分辨原则,基于空间邻近图通过连接边剪枝、群组聚类和显示替换等步骤实现聚合显示。仿真实验结果表明,该方法能够有效解决点状军标空间占位冲突,而且在多比例尺聚合显示条件下,保持聚合结果层次性,符合视觉认知规律。     

针对路面建模的Delaunay三角网格分治算法

为了对路面进行三维建模,使用Delaunay三角网分治算法处理路面点云数据,根据路面点云的特点,对点云进行划分中不考虑z坐标.使用Delaunay三角网分治算法处理不同规模的点云数据并记录生成三角网所需的时间,收集一段路面的点云数据并使用Delaunay三角网算法进行处理,观察生成的三角网是否和扫描的路面匹配.Delaunay三角网分治算法能够较快地生成三角网,但是在处理大规模点云数据时仍需消耗很多时间,同时针对路面三维建模问题,Delaunay三角网分治算法所生成的三角网能够很好地拟合路面.     

Fractal image compression based on Delaunay triangulation andvector quantization

Presents a new scheme for fractal image compression based on adaptive Delaunay triangulation. Such a partition is computed on an initial set of points obtained with a split and merge algorithm in a grey level dependent way. The triangulation is thus fully flexible and returns a limited number of blocks allowing good compression ratios. Moreover, a second original approach is the integration of a classification step based on a modified version of the Lloyd algorithm (vector quantization) in order to reduce the encoding complexity. The vector quantization algorithm is implemented on pixel histograms directly generated from the triangulation. The aim is to reduce the number of comparisons between the two sets of blocks involved in fractal image compression by keeping only the best representative triangles in the domain blocks set. Quality coding results are achieved at rates between 0.25-0.5 b/pixel depending on the nature of the original image and on the number of triangles retained.     

带断层海量数据的Delaunay三角剖分算法研究

海量地震数据网格化是三维地质建模的常用方法.断层是普遍的地质现象,带断层的海量数据三角剖分在建模中较为复杂.提出一种简单的可以解决带断层Delaunay三角剖分有效算法.该算法首先对数据边界进行初始Delaunay三角剖分,然后将其变尺度加密,生成较均匀三角网,最后将断层边强行嵌入三角网,实现了三角网格化.     

Broadband service creation and operations

Three challenges for deploying broadband services are the time-consuming process of service creation, the interoperability over heterogeneous platforms, and the gap between the needs of service management and the functionalities of network management. We describe a methodology to attack the first two challenges, namely, to simplify the process of service creation and provide a platform-independent framework for service operations. A set of broadband service-independent building blocks (SIBs) are designed and used to create and customize SIB graphs for broadband services. During service running time, the service agent interprets a SIB graph and executes SIB procedures which are all downloaded from the service provider. Web, Java, and CORBA are the technological elements of this methodology. Two examples, video conferencing and video on demand, are given to demonstrate the feasibility of this approach