改进的滑动窗最大后验译码

信道编码理论中，最大后验（Maxmum A Posteriori）译码算法用于卷积码的译码算法需要大量的存贮空间，并且具有较大的译码时延，为了减少存贮空间，并且减小译码时延提出了改进的滑动窗最大后验译码算法。     

改进的滑动窗最大后验译码

信道编码理论中，最大后验(Maxmum A Posteriori)译码算法用于卷积码的译码算法需要大量的存贮空间，并且具有较大的译码时延，为了减少存贮空间，并且减小译码时延提出了改进的滑动窗最大后验译码算法。     

UMTS Turbo码的滑动窗-线性-Log-MAP算法及VLSI设计

本文讨论UMTS中turbo码的设计,提出采用前向状态度量作为初始化精确值的滑动窗方法和改进的Log-MAP（线性Log-MAP）相结合的算法(称为滑动窗-线性-Log-MAP算法),设计出turbo码的VLSI结构,且在归一化处理时,介绍一种可节约12.5%存储量的方法。FPGA设计结果显示在BER= 时,与最优算法Log-MAP相比,性能损失0.2dB,硬件资源节约30%,译码时延小,吞吐量大。     

Turbo码译码器VLSI结构的研究

探讨了Turbo码Log—MAP译码算法的VLSI实现技术。着重研究了计算状态度量的加比选结构以及实现MAP算法的滑窗法，并对整体译码方案进行了描述。还提出了可行的实现方案。通过实验仿真表明所用的方案能够达到精度要求。     

次最优软输出算法的高效存储策略

具有优秀误码性能的迭代接收机在实现中面临的一个关键问题就是译码算法对内存的过大需求。滑动窗法可以有效地减少内存以及处理时延。利用算法递归值的单次可利用性,进一步优化该法：通过对网格中状态度量进行实时的释放与更新,使内存消耗又缩减一倍;通过将似然比计算嵌入到双向递归的过程,使处理时延只为传统窗法的1/3;通过保留两个后向递归器结构,经实验表明接收机在优化实现后整体误码性能不减。     

滑动窗口协议分析及其在微机上的模拟实现

阐述了滑动窗口的概念及模型。首重分析了滑动窗口协议和差错控制的策略,最后给出模拟后退Ｎ连续ＡＲＱ的滑窗协议和选择重发连续ＡＲＱ滑窗协议的程序计算结果及其分析。     

滑动时间窗算法的Matlab实现

滑动时间窗算法是飞机终端区排序算法中非常重要的一种。介绍了飞机终端区排序中滑动时间窗算法的思想,实现了滑动时间窗算法的Matlab编程,给出了编程代码,为进一步研究滑动时间窗算法提供了基础,通过算例仿真验证了所设计算法的有效性、优越性。     

LDPC比特翻转译码算法的分析与改进

利用统计译码思想由LDPC（Low Density Parity Check）码校验矩阵通过矢量的线性组合构造出一个新的低密度校验矢量集合，并结合LDPC码并行比特翻转译码算法的环检测等特点的分析，提出了一种新的硬判决译码方案。仿真结果表明：改进算法在译码性能上接近BP算法，又保持了并行比特翻转算法迭代次数少的优点。     

SAR图像结构信息和自适应滑动窗的联合降噪

针对合成孔径雷达（SAR）图像降噪算法中滑动窗的选择问题,提出了同时考虑结构信息和自适应滑动窗的联合降噪算法,联合算法先对局部区域进行自适应增长。然后利用比值模板对得到的滑动窟进行结构检测,最后对结构特征区域进行自适应增长,从而获得完整的结构信息．仿真图像和SAR图像的降噪实验表明,联合降噪算法在有效滤除噪声的同时对边缘纹理等细节信息具有较强的保持作用．     

约束维特比译码算法的性能研究

维特比译码是一种最大似然译码，在数字通信系统中得到广泛的应用。约束维特比算法是利用已知的正确信息．对维特比算法进行改进。本文针对约束维特比算法进行了探讨，并对其性能进行了仿真实验。仿真结果证明，在二进制均衡信道中当采用约束维特比算法时．性能得到了较大的提高。     

两个可证明安全盲签名方案的密码学分析

最近,Liao等人提出了一个基于双线性时的在标准模型下可证明安全的盲签名方案;Chen等人提出了一个在随机预言机模型下可证明安全的限制性盲签名方案.在本文中,给出了这两个方案的密码学分析,指出它们都是不安全的.Liao等人的方案和Chen等人的方案都不满足不可伪造的特性.同时,Liao等人的方案也不满足盲性,Chen等人的方案不满足限制性.     

一种新的可验证的多秘密分享方案

2005年,Q．Li．Z．Wang,X．Mu等人基于Asmuth的模可验证秘密分享（modular verifiable secret sharing）出了一种新的可验证的秘密分享方案。但该秘密分享算法并不实用,此方案也不是多秘密分享方案。提出了一个新的可验证的多秘密分享方案,该方案可以同时恢复多个秘密．秘密份额可以重用。     

Vertex rankings of chordal graphs and weighted trees

In this paper we consider the vertex ranking problem of weighted trees. We show that this problem is strongly NP-hard. We also give a polynomial-time reduction from the problem of vertex ranking of weighted trees to the vertex ranking of (simple) chordal graphs, which proves that the latter problem is NP-hard. In this way we solve an open problem of Aspvall and Heggernes. We use this reduction and the algorithm of Bodlaender et al.'s for vertex ranking of partial k-trees to give an exact polynomial-time algorithm for vertex ranking of a tree with bounded and integer valued weight functions. This algorithm serves as a procedure in designing a PTAS for weighted vertex ranking problem of trees with bounded weight functions.     

Fast randomized algorithm for center-detection

Recently, Cauchie et al. presented an adaptive Hough transform-based algorithm to successfully solve the center-detection problem which is an important issue in many real-world problems. This paper presents a fast randomized algorithm to solve the same problem. With similar memory requirement and accuracy, the computational complexity analysis and comparison show that our proposed algorithm performs much better in terms of efficiency. We have tested our algorithm on 13 real images. Experimental results indicated that our algorithm has 38% execution-time improvement over Cauchie et al.'s algorithm. The extension of the proposed algorithm to detect multiple centers is also addressed.     

PRGA的初始状态与RC4算法的安全性

PRGA初始状态的取值情况对RC4算法的安全性具有决定意义,分析了PRGA初始状态的取值情况与RC4算法安全性的关系。在猜测赋值分析方法的基础上,提出了新的复杂度计算方法,从而解决了PRGA初始状态取值情况对应的破译RC4算法的复杂度问题。在已知初始状态的部分取值的情况下,该方法能够非常有效地计算出破译RC4算法的复杂度。     

基于可变大小模板的改进图像修复算法

Criminisi等人提出的基于模板的图像修复算法是该领域最重要的贡献之一。在保持Criminisi基本算法框架不变的基础上,本文提出了一些改进思想。主要贡献是设计了基于可变大小模板的块匹配程序以使模板搜索更准确灵活。此外,对信度更新方式进行了修正,并结合局部搜索以提高算法的综合性能。实验结果证实了改进的有效性。     

Self-tuning controller design for systems with arbitrary time delays Part 2. Algorithms and simulation examples

Recent theoretical developments in the self-tuning control of multivariable systems with arbitrary time delays have been considered in Part 1 of this work (Tade et al. 1988) and a simple time delay extraction procedure has been proposed. In this paper, that procedure is used to derive an adaptive controller based on the generalized minimum variance criterion. The computation count for the proposed self-tuning control algorithm is compared with those for two other algorithms, one proposed by Prager and Wellstead (1981) and the other by Dugard et al. (1984). Assuming that all computation requirements for other stages of the implementation of these algorithms are equal, the results indicate that the proposed algorithm requires less computational effort for updating the control action at each sampling interval. Simulation examples are presented to demonstrate the performance of the proposed algorithm.     

一个安全的多群签名方案

基于Kim等人的可转换群签名的思想，提出了一个安全的多群签名方案,该方案不仅能实现单群签名，而且能实现多群签名，并且能抵抗Li和Wang等人对Kim等人方案提出的攻击．此外，新方案还具有注销群成员的特性.     

Two improved two-party identity-based authenticated key agreement protocols

Many authenticated key agreement protocols based on identity information were published in recent years. Hsieh et al. presented their protocol in 2002. However, Tseng et al. found a flaw in the protocol which resulted in a key compromise impersonation attack. Later, Tseng proposed his protocol conforming which conforms to all desirable security properties and is efficient. In this paper we propose two new two-party identity-based authenticated key agreement protocols. The first is based on Hsieh et al.'s protocol and makes it immune against Tseng et al.'s attack, while the second is an efficiently improved protocol based on Tseng's protocol.     

Mixture inventory model involving variable lead time and controllable backorder rate

This paper allows the backorder rate as a control variable to widen applications of Ouyang et al.'s model [J. Oper. Res. Soc. 47 (1996) 829]. In this study, we assume that the backorder rate is dependent on the length of lead time through the amount of shortages. We discuss two models that are perfect and partial information about the lead time demand distribution, that is, we first assume that the lead time demand follows a normal distribution, and then remove this assumption by only assuming that the first and second moments of the probability distribution of lead time demand are known. For each case, we develop an algorithm to find the optimal ordering strategy. Three numerical examples are given to illustrate solution procedure.