Undeniable signature scheme based over group ring

D. Chaum and H. van Antwerpen first introduced the concept of an undeniable signature scheme where the verification step is verified with the signer’s co-operation. In this paper, first we discuss a combination of Discrete Logarithm Problem (DLP) and Conjugacy Search Problem (CSP) analysing its security. Then we propose an undeniable signature scheme in a non-abelian group over group ring whose security relies on difficulty of the combination of the DLP and the CSP. The complexity and security of our proposed scheme has also been discussed.     

The front-tracking scheme for the one-dimensional freezing problem

The one-dimensional freezing problem can be solved numerically for the temperature distribution accompanied by explicit reference to the position of the freezing front at each time interval. A new front-tracking scheme provides accurate determination of the phase front, which is an essential requirement for the temperature distribution in the different phases of such problems. The front is made to coincide with a grid-node throughout the analysis. The scheme uses a combination of the finite difference and the finite element methods for obtaining the solution of the freezing problems.     

基于随机共振及图谱理论的齿轮故障特征提取

机车齿轮箱齿轮工作环境恶劣且极易出现齿轮损伤.齿轮箱齿根裂纹损伤检测是保证列车安全运行的有效措施.本文提出了一种基于随机共振以及图谱理论相结合的齿根裂纹故障提取方法.基于随机共振以及图谱理论的故障提取方法具体过程如下:首先,运用复Morlet小波梳状滤波器对原始信号进行解调处理;然后,运用图谱理论方法对仿真信号进行处理...     

Intelligent sampling decision scheme based on the AVM system

Wafer inspection plays a significant role in monitoring the quality of wafers production for continuous improvement. However, it requires measuring tools and additional cycle time to do real metrology, which is costly and time-consuming. Therefore, reducing sampling rate to as low as possible is a high priority to reduce production cost. Several sampling methods in the literature were proposed to achieve this goal. They utilised real sampling inspections as the representatives for the other related wafers to monitor the whole production process. Under the condition of stable manufacturing process, virtual metrology (VM) may be applied to monitor the quality of wafers, while real metrology is unavailable. Therefore, the sampling rate may further be reduced with a sampling decision scheme being designed according to reliable VM. Nevertheless, once a new production variation occurs between planned samplings and no real metrology is available during this period for updating the VM models, un-reliable VM predictions may be produced. The authors have developed the automatic virtual metrology (AVM) system for various VM applications. Therefore, this paper focuses on applying various indices of the AVM system to develop an intelligent sampling decision scheme for reducing sampling rate, while VM accuracy is still sustained.     

Group preserving scheme for the Cauchy problem of the Laplace equation

In this paper, we consider the Cauchy problem for the Laplace equation by group preserving scheme (GPS) which is an ill-posed problem, because the solution does not depend continuously on the data. For this, the Laplace equation, by using a semi-discretization method namely method of line, is converted to an ODEs system and then obtained ODEs system is considered by GPS. Stability of GPS for ill-posed Laplace equation is shown. The problem numerical results show the efficiency and power of this method.     

基于相位法的密集小波公共脊线提取方法

针对传统小波脊线提取方法对密集脊线的提取存在着分辨率不足等缺点,提出一种基于相位法的密集小波公共脊线提取方法。通过分析密集单频叠加信号和密集调频叠加信号的小波公共脊线的相位特点,利用小波脊线的相位法来提取信号的公共脊线。仿真算例结果表明:该方法能有效地提取出密集小波公共脊线,且方法简单、准确,具有较快的收敛性。将其应用于实际齿轮箱故障分析中,能有效地提取故障特征,诊断出齿轮箱故障。     

A scheme for solving two models of the two-dimensional inverse problem

Optimization and Engineering - Inverse problems are of great importance in some engineering texts and many industrial applications. Owing to this, we exhibit a method for numerically estimating two...     

基于调和修补模型的图像压缩方案

本文采用调和修补模型,给出了一种新的图像压缩方案。在图像编码端,采用边缘提取技术,仅对边缘扩展图像进行压缩编码,大大减少了需要编码的信息量。在图像解码端,采用调和修补模型来重建原始图像。通过对大量灰度和彩色图像进行实验,结果表明,该压缩方案能够在较少信息量的情况下得到很好的重建图像。     

一种基于软件无线电的频谱扫描技术

在无线电综合测试仪的设计中,频谱扫描是一项基础技术.将需要扫描的频谱划分成子带,进而提出了一种通过在模拟前端采用可变频率本振的混频器和低通滤波器实现子带信号分离,然后对子带信号进行采样并且变换到频域,最后将所有子带频谱拼接获得完整频谱的技术.为了实现该技术,设计了一个由软件无线电(Software-defined Radio,SDR)接收机和数字信号处理片上系统(System on Chip,SOC)组成的软件无线电平台.随后,在基于该平台实现的综测仪原型上对频谱分析技术进行了验证.仿真和实验表明,该方法和原型样机能够对0~6 GHz范围的频谱进行扫描,同时具有较低的噪声水平和较好的动态范围,且能够提供相位谱,因而适用于嵌入式频谱仪和无线电综测仪的应用场合.     

A note on cyclic groups,finite fields,and the discrete logarithm problem

We show how the discrete logarithm problem in some finite cyclic groups can easily be reduced to the discrete logarithm problem in a finite field. The cyclic groups that we consider are the set of points on a singular elliptic curve over a finite field, the set of points on a genus 0 curve over a finite field given by the Pell equation, and certain subgroups of the general linear group.     

一种基于偏好的查询扩展方法

为克服语言歧义性和用户使用简短查询语句的习惯对搜索引擎查询准确率造成的影响,提出了一种基于偏好的查询扩展方法.该方法将用户对网页的偏好转化为对知识库中概念的偏好,建立用户兴趣模型,在该模型基础上对原始查询结果进行分析,挑选出与用户偏好关联最紧密的关键词加入原查询,解决了基于局部分析的查询扩展方法在初次检索质量不高时性能恶化的问题.实验表明,本文提出的方法相对于传统的查询扩展算法可以大幅度提高查询精度.     

Secure video distribution scheme based on partial encryption

In TV program distribution, the receiver's identification information is embedded into video data in order to trace illegal distributors, and video data are encrypted in order to protect the confidentiality against unauthorized users. In traditional method, the TV program is firstly fingerprinted, then encrypted, and finally transmitted. For N receivers, N times of encryption, and N times of fingerprinting operations are required, which makes the sender of high loading. In another method, the media content is decrypted and fingerprinted simultaneously by the joint fingerprint embedding and decryption, which is difficult to obtain reasonable performances. In this article, a commutative encryption and fingerprinting scheme is proposed to reduce the sender's loading. In this scheme, the TV program is firstly encrypted, then fingerprinted, and finally transferred. When compared with the traditional method, in the proposed method, only once encryption and N times of fingerprinting are required, which reduces the sender's loading greatly. Based on MPEG2 videos, a commutative encryption and fingerprinting scheme is presented, whose performances including security, efficiency, robustness, and imperceptibility are evaluated. Experimental results show that the scheme obtains good performances and is suitable for TV program distribution. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 227–235, 2009     

基于软符号估值的估计转发无线中继模式

在研究已有的放大转发(AF)和解码转发(DF)这两种中继模式的基础上,根据估计转发(EF)的思想,提出了一种对软符号和相应噪声功率估值的新型EF无线中继模式,并设计了基于联立求解方程组来实现这种中继模式的简化算法.分析了这种EF模式相比于已有模式的特点和优势.在仿真实验中分别设定了两种协作场景,对上述3种转发模式的性能...     

An efficient reversible data hiding scheme based on SMVQ

Abstract

Data hiding technique can hide a certain amount of secret data into digital content such as image, document, audio or video. Reversible compressed image data hiding can loosely restore the cover image after extracting the secret data from the stego-image. In this paper, we present an efficient reversible image data hiding scheme based on side match vector quantisation. Mapping concept is useful for this scheme because it converts the ternary into binary. The proposed scheme significantly increases the payload size of a block, and the quality analysis of the proposed scheme showed that it contains a better peak signal to noise than other schemes.     

Fast auto-focus scheme based on optical defocus fitting model

An optical defocus fitting model-based (ODFM) auto-focus scheme is proposed. Considering the basic optical defocus principle, the optical defocus fitting model is derived to approximate the potential-focus position. By this accurate modelling, the proposed auto-focus scheme can make the stepping motor approach the focal plane more accurately and rapidly. Two fitting positions are first determined for an arbitrary initial stepping motor position. Three images (initial image and two fitting images) at these positions are then collected to estimate the potential-focus position based on the proposed ODFM method. Around the estimated potential-focus position, two reference images are recorded. The auto-focus procedure is then completed by processing these two reference images and the potential-focus image to confirm the in-focus position using a contrast based method. Experimental results prove that the proposed scheme can complete auto-focus within only 5 to 7 steps with good performance even under low-light condition.     

Enhanced dual-frequency pattern scheme based on spatial-temporal fringes method

One of the major challenges of employing a dual-frequency phase-shifting algorithm for phase retrieval is its sensitivity to noise. Yun et al proposed a dual-frequency method based on the Fourier transform profilometry, yet the low-frequency lobes are close to each other for accurate band-pass filtering. In the light of this problem, a novel dual-frequency pattern based on the spatial-temporal fringes (STF) method is developed in this paper. Three fringe patterns with two different frequencies are required. The low-frequency phase is obtained from two low-frequency fringe patterns by the STF method, so the signal lobes can be extracted accurately as they are far away from each other. The high-frequency phase is retrieved from another fringe pattern without the impact of the DC component. Simulations and experiments are conducted to demonstrate the excellent precision of the proposed method.     

Distributed K-coverage self-location estimation scheme based on Voronoi diagram

The success of many wireless sensor network (WSN) applications, such as moving target tracking or environment monitoring, is dependent upon achieving 'k-coverage' of the sensed area, that is every point in the surveillance area is monitored by at least k sensors. This study presents a novel distributed self-location estimation scheme based on a Voronoi diagram to achieve k-coverage in a WSN with mobile nodes. The simulation results show that the proposed scheme effectively to perform k-coverage within the sensing field and fast convergent to fulfil more than 88% k-coverage ratio following three movements for the minimal required sensor deployment.     

A colour image retrieval scheme based on Z-scanning technique

Abstract

This paper proposes a new colour image retrieval scheme using Z-scanning technique for content-based image retrieval (CBIR). In recent years, the CBIR is a popular research topic for image retrieval. This paper proposes a scheme which employs the Z-scanning technique to extract directional intensity features for measuring the similarity between query and database images. In the multiple channel images, each colour channel can be processed individually or combined into a grey channel Y. In order to extract the features by Z-scanning technique from all images, each channel of all images must be divided into several N×N blocks. In each block, F pairs of pixels are scanned by a ‘Z’ direction to obtain the texture features. Each colour channel can be obtained an M×M Z-scanning co-occurrence matrix (ZSCM) for storing the probability of each relationship of all closest blocks. At the similarity measure stage, the ZSCMs of query image and database images are compared to measure their similarity. The experimental results show that the proposed scheme is beneficial for image retrieval when the images include the same texture or object. On the other hand, the proposed scheme also can get better retrieval results and more efficiency than colour correlogram (CC) technique for colour texture images. Another technique uses motif co-occurrence matrix (MCM) as the feature in similarity measurement. The experimental results show the proposed ZSCM can get better retrieval results and higher recall and precision values than the CC and MCM techniques for public image databases.     

A scheme of reversible information hiding based on SMVQ

Abstract

In this paper, we propose two reversible information hiding schemes based on side-match vector quantisation (SMVQ). In 2006, Chang et al. proposed a data-hiding scheme based on SMVQ coding. In order to increase both the image quality and the embedding capacity, we improve their method by embedding multiple secret bits into a block and finding out the second selected codeword from the full codebook. In addition, we propose another reversible information hiding scheme whose output is a pure VQ index table. The weighted bipartite graph is used to model our scheme and the matching approach is used to find out the best solution. Compared with Chang et al.’s scheme, we have higher visual quality in the experimental results.     

基于提升格形态小波的生物芯片图像增强

提出一种使用提升格形态小波进行生物芯片图像滤波增强的方法。根据生物芯片图像的样点和噪声区域的大小选择合适的结构元素或者预测-升级算子,并通过形态学算子或者提升格构造形态小波分解和重构形式。利用形态小波的不同级连方式和高频系数的处理实现生物芯片图像的滤波增强。实验表明,该方法可以有效地结合形态学和小波滤波的优势,降低了运算量,取得良好的生物芯片图像增强效果。