一般访问结构上无可信中心的群签名方案

针对矢量空间秘密共享方案和离散对数问题的难解性问题,提出一个一般访问结构上的无可信中心的群签名方案.该方案无需可信的密钥分发中心KDC的参与,将群签名的应用范围推广到一般访问结构上.不仅可以克服现有门限签名方案在实际应用中的局限性,而且避免KDC对参与者的欺骗.在方案的执行过程中,部分签名和群签名都可以得到有效验证.分...     

具有多维特征的WSN路由协议研究

为实现不同地理维数数据类型的合理融合,提出一种基于通用搜索树(GiST)的分簇拓扑结构。利用叶节点的位置信息建立簇,通过GiST体系结构算法对区域内的所有簇进行分块组织,建立树形拓扑结构。仿真结果表明,GiST体系结构算法具有良好的多维特性,可快速进行不同维数结构间的融合。建立的结构与其他拓扑结构相比,网络传输效率较高,网络生命周期较长。     

基于算法组合的人员排班方法研究

排班问题是现实生活中的常见问题.从国内某货航实际情况出发,提出了一种初步排班流程.首先采用线性规划建立班制,再依据班制用贪心算法构建班制串矩阵,以回溯方法将具体班填入班制串,进行微调后完成排班.实验表明了排班方法的合理性.     

基于双曲线映射签名的高效可分电子现金系统

基于双曲线映射的签名设计了一种新型可分电子现金方案,方案中有效地加入了压缩支付和批处理支付,计算时间复杂度较小,从而使得系统的整体效率较高。另外,方案中无需可信第三方(TTP)的参与,因而系统的整体开销较小。方案的安全性基于q-SDK假设、计算离散对数困难性假设以及单向散列函数存在性假设。     

A local construction of the Smith normal form of a matrix polynomial

We present an algorithm for computing a Smith form with multipliers of a regular matrix polynomial over a field. This algorithm differs from previous ones in that it computes a local Smith form for each irreducible factor in the determinant separately and then combines them into a global Smith form, whereas other algorithms apply a sequence of unimodular row and column operations to the original matrix. The performance of the algorithm in exact arithmetic is reported for several test cases.     

Superconvergence and Extrapolation Analysis of a Nonconforming Mixed Finite Element Approximation for Time-Harmonic Maxwell’s Equations

In this paper, a nonconforming mixed finite element approximating to the three-dimensional time-harmonic Maxwell’s equations is presented. On a uniform rectangular prism mesh, superclose property is achieved for electric field E and magnetic filed H with the boundary condition E×n=0 by means of the asymptotic expansion. Applying postprocessing operators, a superconvergence result is stated for the discretization error of the postprocessed discrete solution to the solution itself. To our best knowledge, this is the first global superconvergence analysis of nonconforming mixed finite elements for the Maxwell’s equations. Furthermore, the approximation accuracy will be improved by extrapolation method.     

Numerical inversions of a source term in the FADE with a Dirichlet boundary condition using final observations

This paper deals with an inverse problem of determining a source term in the one-dimensional fractional advection-dispersion equation (FADE) with a Dirichlet boundary condition on a finite domain, using final observations. On the basis of the shifted Grünwald formula, a finite difference scheme for the forward problem of the FADE is given, by means of which the source magnitude depending upon the space variable is reconstructed numerically by applying an optimal perturbation regularization algorithm. Numerical inversions with noisy data are carried out for the unknowns taking three functional forms: polynomials, trigonometric functions and index functions. The reconstruction results show that the inversion algorithm is efficient for the inverse problem of determining source terms in a FADE, and the algorithm is also stable for additional data having random noises.     

Ring signature scheme based on multivariate public key cryptosystems

The ring signature scheme is an important cryptographic primitive that enables a user to sign a message on behalf of a group in authentic and anonymous way, i.e. the recipient of the message is convinced that the message is valid and it comes from one of the group members, but does not know who the actual signer is. Currently, all the existing ring signatures are based on traditional cryptosystems. However, the rapid advances in the field of quantum computing indicate a growing threat to traditional cryptosystems. Multivariate public key cryptosystems (MPKCs) is one of the promising alternatives which may resist future quantum computing attacks. In this work, we propose a novel ring signature scheme based on multivariate polynomials with the security model for the first time. Our ring signature scheme has a great advantage in efficiency compared to many existing ring signature schemes, and currently it seems to be immune to quantum computing attacks.     

Extension to the analytical model of the interdigital electrodes capacitance for a multi-layered structure

Interdigital electrodes (IE) are one of the most used transducers in different technical and analytical applications with the particular importance in the field of chemical and biological sensors. With the recent demand for lab-on-a-chip devices and the need for sensors miniaturization it becomes common the use of such transducers in structures with several dielectric layers (either substrates or superstrates). In a previous a work we proposed a model for the computation of the capacitance of these multi-layered structures using the techniques of conformal mapping and partial capacitance. Until now, that model has been used in applications where the permittivity of consecutive layers monotonically decreases from layer to layer (as we move away from the electrodes plane) giving excellent results. New applications, such as the use of Si/SiO₂ substrates (to promote very smooth surfaces for electrodes deposition) or the use of passivation layers for the protection of electrodes (e.g. from liquids), among others, represent a new challenge for the computation of the overall capacitance since in these devices the permittivity can decrease from layer to layer. Under these conditions the original partial capacitance technique needs to be modified to include these new configurations. In this work we will discuss a new approach, splitting the concept of partial capacitance in parallel partial capacitance and serial partial capacitance where new conformal mapping transformations are proposed for the latter case. Hence this novel approach will extend our previous analytical model in order to account for the cases where there is a decrease in the permittivity from layer to layer. The results are compared with finite element simulation and experimental results.