五点二重逼近细分法

提出了一种新的构造曲线的算法——五点二重逼近细分法。利用细分格式 的生成多项式讨论了该细分格式的一致收敛性及Ck 连续性。该细分格式带有一个张力参数 μ, 通过选取不同的μ值,可以分别生成C1~C5 连续的极限曲线。特别是当μ=9/256 时, 细 分格式生成的极限曲线可以达到C7 连续。最后给出了五点二重逼近曲线细分的实例,表明 了这种细分格式是有效的。     

A new interpolation subdivision scheme for triangle/quad mesh

In this paper, we present a new interpolation subdivision scheme for mixed triangle/quad meshes that is C¹ continuous. The new scheme is capable of reproducing the well-known four-point based interpolation subdivision in the quad region but does not reproduce Butterfly subdivision in the triangular part. The new scheme defines rules that produce surfaces both at the regular quad/triangle vertices and isolated, extraordinary points. We demonstrate the visually satisfying of our surfaces through several examples.     

A subdivision scheme for Poisson curves and surfaces

The de Casteljau evaluation algorithm applied to a finite sequence of control points defines a Bézier curve. This evaluation procedure also generates a subdivision algorithm and the limit of the subdivision process is this same Bézier curve. Extending the de Casteljau subdivision algorithm to an infinite sequence of control points defines a new family of curves. Here, limits of this stationary non-uniform subdivision process are shown to be equivalent to curves whose control points are the original data points and whose blending functions are given by the Poisson distribution. Thus this approach generalizes standard subdivision techniques from polynomials to arbitrary analytic functions. Extensions of this new subdivision scheme from curves to tensor product surfaces are also discussed.     

A connectionist model for corner detection in binary and grayimages

For a given binary/gray image, each pixel in the image is assigned with some initial cornerity (our measurable quantity) which is a vector representing the direction and strength of the corner. These cornerities are then mapped onto a neural-network model which is essentially designed as a cooperative computational framework. The cornerity at each pixel is updated depending on the neighborhood information. After the network dynamics settles to stable state, the dominant points are obtained by finding out the local maxima in the cornerities. Theoretical investigations are made to ensure the stability and convergence of the network. It is found that the network is able to detect corner points: even in the noisy images and for open object boundaries. The dynamics of the network is extended to accept the edge information from gray images as well. The effectiveness of the model is experimentally demonstrated in synthetic and real-life binary and gray images.     

The linear complexity of new generalized cyclotomic binary sequences of order four

Whiteman generalized cyclotomic sequences are proven to exhibit a number of good randomness properties. In this paper we determine the linear complexity of some newly generalized cyclotomic sequences, of order four with period pq which are defined by Ding and Helleseth. The results show that all of these sequences have high linear complexity.     

基于逆细分的自由曲线分解与重建*

针对自由曲线的多分辨率表示,选取了双参数Chaikin细分法,基于几何逆向思想提出了相应的逆细分算法,建立了双参数可控的自由曲线渐近分解规则,通过分析双参数对曲线分解的影响,寻找出最优分解参数值,实现了自由曲线的最优分解,通过渐近分解时建立的误差向量,最终实现了自由曲线的完全重建。该算法比以往方法构造过程简单,几何意义明显,易于推广到其他细分模式上。     

A new data hiding scheme for binary image authentication with small image distortion

A new data hiding scheme for binary image authentication that has a small distortion of the cover image is proposed in this paper. Using the data-embedding algorithm that is based on Hamming codes, the proposed scheme embeds authentication information into the cover image with flipping only a small number of pixels. A special type of the pixels are selected and flipped by a new algorithm to minimize visual distortion. This new algorithm is based on ELSSM (Edge Line Segment Similarity Measure). Randomly shuffling the bit-order of the authentication information to be embedded, the information can only be extracted by the designated receiver who has the symmetric key. We employ two measurement metrics: miss detection rates for the degree of security and PSNR (Peak Signal-to-Noise Ratio) and ELSSM for the degree of the image distortion to demonstrate the feasibility of the proposed scheme. Using these metrics, we analyze the proposed scheme and the previous schemes. The analysis reveals that the proposed scheme requires less image distortion than the previous schemes whilst achieving the same level of the miss detection rate. Experimental results demonstrate that the proposed scheme is more resilient against recent steganalysis attacks than the previous schemes.     

点对核值匹配的角点检测

针对SUSAN法检测X型角点能力较弱的问题,提出一种新的角点检测算法。在圆形模板区域内引入点对的概念,通过建立核值与点对的匹配规则来检测角点。给出了一个模板响应公式,加大了各点模板响应值的差别,提高了算法的抗干扰能力。实验结果表明,该算法对复杂的X型角点和普通角点均具有较好的检测效果。     

分割逼近法快速求解点到复杂平面曲线最小距离

建立了点到复杂平面曲线最小距离的数学模型,提出了快速计算点到复杂平面曲线最小距离的分割逼近算法。大量算例验证了该算法的有效性,其计算精确度高,可以达到任意给定的精度,非常适用于三坐标测量机的点相关数据处理,在工程上具有重要的实用价值。     

一个改进的多消息多接收者混合签密方案

指出王彩芬等人的基于离散对数的多消息多接收者混合签密方案存在着密钥泄露问题。为了克服该私钥泄漏问题,结合双线性对和基于身份密钥机制提出了一个改进的多消息多接收者混合签密方案。利用双线性对的对称性和基于身份密钥机制的密钥生成方式避免了原方案中存在的密钥泄露问题。最后,基于DBDH难题和CDH难题,在随机预言机模型下证明了改进方案的机密性和不可伪造性。     

基于哈希表和平衡二叉树的证书撤销方案

分析了基于哈希算法的证书撤销方案和基于剩余有效期游标树的证书撤销方案,研究了两种方法的优缺点。提出了基于哈希表和平衡二叉树的证书撤销方案,并分析了该方案的有效性和安全性。通过三种方案的性能比较,得出基于哈希表和平衡二叉树的证书撤销方案降低了查找证书的通信成本。     

Optimal cutting design and analysis for fault-tolerant scheme of redundant memories

Fault-tolerant design for memory production is beginning to play an important role in increasing the yield rate of manufacturing. To improve the reliability of memory manufacturing, there are many methods that have been proposed. One of the most used technologies is replacing the faulty cells with spare memory interleaved in the memory. Nowadays, laser-cutting technology improves the yield of memories because of the enhancement of the use of spare lines. However, the issue of choosing a cutting location significantly affects the utilisation of spare lines. A bad cutting location can even render it useless. To use spare lines more efficiently, this article proposes two algorithms. The first one is designed to seek out a good cutting location. It corrects some defects of previous algorithms and provides a better approach to finding cutting candidates. In addition, because most heuristic solution-finding algorithms do not work properly under the condition of cutting memory, the second algorithm, called modification of most-repair is proposed to help make the decision as to whether or not a solution exists for the faulty pattern. We can find an optimal solution by combing these two algorithms. The experimental results show that our proposed algorithms increase the reparable percentage of a 1024-by-1024 memory from 55 to 100% and also improve both the reliability of memory manufacturing and the flexibility of spare lines.     

Pierce point minimization and optimal torch path determination in flame cutting

This paper addresses the problem of sequencing a torch for the cutting of a stock sheet nested with regular or irregular parts. The image of the nesting is reduced to an equivalent graph, and the objective is to traverse this graph with a minimum number of pierce points, or blowthroughs. If the graph has $\text{2k}$ vertices of odd degree, then $\text{k}$ pierce points are necessary and sufficient to traverse the graph. The torch path problem formulation includes manufacturing cost, efficiency, and distortion considerations. We present three algorithms for the problem. The first algorithm shows how to determine the $\text{k}$ torch paths, and is optimal in run time complexity. The second algorithm uses trim margin edges to investigate further reduction in the number of pierce points. The third algorithm guarantees that for the special case where a torch path has no vertices of odd degree, no piece will be dropped that needs further interior cuts. Some possible extensions to this work are also addressed.     

改进的高效云存储数据去重方案

针对Chen等人提出的云存储数据去重方案BL-MLE的计算开销过大的问题,对其方案进行了改进,提出了一种更高效的数据去重方案。首先对BL-MLE方案进行了分析,指出其在计算效率等方面的不足;随后通过使用hash函数和标签决策树对BL-MLE的块标签生成过程以及块标签比较过程进行改进;最后,实验仿真了改进的方案。结果表明,改进后的方案在块标签比较所需次数更少,且块标签生成上时间开销更低,能更好地适应当前的云存储环境。     

The binary consistency checking scheme and its applications toseismic horizon detection

For a given set of n tuples, the binary consistency checking scheme generates a subset wherein no two elements intersect. The application of this scheme is illustrated by two problems in seismic horizon detection; seismic skeletonization and loop tying. After a brief introduction to seismic interpretation, these two examples are used to demonstrate how to cast an application problem into the formulism of the scheme. A comparison of this scheme to the dynamic programming approach to string matching due to S.Y. Lu (1982) is included     

A multi-touch platform based on four corner cameras and methods for accurately locating contact points

This paper presents a low-cost and scalable multi-touch platform which uses four cameras to reduce occlusion. Three methods are provided for locating contact points on this platform, including the lookup table, vanishing point, and 3D reconstruction. With each of these methods, respectively, the contact point is located using the projection center and the reference point, the projection center and the vanishing point, and the back-projected rays of epipolar geometry. If the four directing lines of a contact point intersect, the contact point is considered to be real; if the lines do not intersect, the point is rejected. Experimental results indicate that all three methods are capable of locating contact points even under conditions of occlusion. The lookup table and vanishing point methods are, respectively, best suited to small and large platforms, while the accuracy of 3D reconstruction method has been found to be sensitive to the physical setup. The approach proposed here can be directly installed on existing display platforms and thus should be of practical applicability in the near future.     

一种AES S盒改进方案及其硬件设计

为提高高级加密标准（advanced encryption standard,AES）算法的安全性,提出了一种新的S盒生成方案。在分析了现有S盒存在的问题后,基于S盒的构造原理和密码学性质,通过选择新的不可约多项式和仿射变换对,同时调整仿射变换与乘法逆的运算顺序,构造出一种新的S盒;对生成的新S盒与AES 的S盒以及其他改进S盒在代数式项数、严格雪崩标准距离等方面进行了比较,结果显示新S盒具有更好的代数性质,能够有效抵御代数攻击;还对新S盒进行了硬件设计并优化,DC综合结果显示新S盒复域优化实现消耗的资源比传统复域实现少12%,比查找表法实现少41%。新S盒在安全性方面优于现有S盒,将其应用于AES软件设计和硬件设计,并通过仿真测试验证了其正确性。     

一种感应信号控制的改进方案及其仿真研究

提出一种改进的感应信号控制算法,并以交叉口平均车辆延误以及平均排队长度作为评价控制算法的指标,采用Paramics为仿真软件;将该算法与传统感应信号控制算法及Synchro 7优化的定时控制方案进行仿真对比。仿真结果表明提出的算法改进效果十分显著,尤其是当交叉口交通流量较大、饱和度较高时,传统算法已经没有改进效果,而该算法改进效果依然显著。     

一种对称斜置式四陀螺惯导冗余配置方案

针对惯性器件冗余数量少,捷联惯导系统可靠度提升少的问题,首先分析了冗余优化准则的等价性,给出了最优冗余配置的充要条件。在基于四陀螺的正交方案、斜置方案和圆锥方案可靠度对比分析的基础上,提出一种对称斜置式方案,能进一步提高四陀螺方案的捷联惯导系统可靠度,而且该方案在陀螺出现故障时,系统精度具有很好的一致性,仿真结果表明：对称斜置式方案是陀螺数量为4个时的最优配置方案之一。该方案对于冗余数量较少的舰船惯导系统设计具有较强的借鉴意义。