一种新的相似性度量及其在DNA序列相似性分析中的应用

衡量序列之问距离的传统方法是通过局部比对或者全局比对来实现的,其运算的时间复杂度和空间复杂度随着序列长度的增加而急剧上升.本文提出一种新的相似性度量.它是建立在Lempel-Ziv复杂度基础之上的,不需要通过序列之间的比对来实现,其时间和空间复杂度比传统方法降低了很多.用这种新的相似性度量的方法可以算出序列同的相似性矩阵,以此来刻画不同序列之间的距离.为了说明此方法的可靠性,最后对多个物种DNA序列作了相似性分析.     

改进的哈奇扬算法求解线性不等式组问题

本文研究了求解线性不等式组问题的哈奇扬算法, 发现算法中的不足, 并对其进行了改进; 运用改进后的算法求出了不等式组的解。     

Study on Complexity of Sutong Bridge’s Objectives system and its Meta-Synthesis Management

Objectives define the boundaries of complex engineering system. It is a hard work to determine the specific objectives of a complex engineering system. The objectives system development needs a complicated process, from nix to prototype, and to final definition. The total process will cover the following course: from chaos to well-ordered; from qualitativeness to combination of quantitativeness and qualitativenss, then to qualitativeness to quantitativeness (a recurrent process), expert experience and theoretical science, rationality and sensibility, synthetic analysis and meta-synthetic, routinization and non-routinization. Such process is explicit in phase development yet overlapped; mutually confined yet mutually independent; permeated conflicts yet pregnant in harmony. This article explores the complexity of Sutong bridge’s objectives development and the process of meta-synthesis in the Sutong Bridge engineering.     

带有优先约束的分批排序问题

对工件带有优先约束的分批排序问题进行了研究,其目标函数为最大完工时间．优先约束为：有一个树上包含有n个工件,其余的m-1条链上的工件数总和为常数,且工件的加工时间不限制．对于此种情况,给出了一个多项式时间算法．     

刚塑性有限元求解板带轧制过程的初速度场

用可压缩刚塑性有限元法,通过自行开发的计算程序对板带轧制过程进行了二维非线性求解.在保证计算精度的情况下,以缩短计算时间为目标,研究了初等方法、G函数法和改进细化网格法设定初速度场对计算时间和计算结果的影响.结果表明:轧制力计算结果和实测值吻合良好,满足精度要求;初等方法、G函数法和改进细化网格法的计算结果相对误差不超过3%,初速度场设定对轧制力求解影响较小;G函数法和改进细化网格法相对初等方法迭代步数较少,由于需要求解方程组,G函数法设定初速度场计算时间最长;改进细化网格法在保证计算精度情况下,减少了迭代步数,缩短了计算时间,提高了计算效率和求解稳定性.     

一种基于冲突跟踪的RFID防冲突算法

在射频识别系统中,防冲突技术是RFID技术必须解决的关键问题之一.针对查询树算法因逐位增加查询前缀而增加了阅读器时间复杂度和通信复杂度这一问题,给出了一种利用冲突位来更新查询前缀的改进算法--冲突跟踪树算法.通过构建冲突跟踪树,从理论上分析了改进算法的通信复杂度.在冲突位是连续的假设前提下,给出了计算阅读器通信复杂度的3个引理和一个定理,并对其做了详细证明.最后利用Matlab对相关算法性能进行了对比仿真.结果表明,在冲突位是连续的前提下,冲突跟踪树算法阅读器的通信复杂度优于查询树算法阅读器的通信复杂度,从而得出在一般情况下,冲突跟踪树算法更能有效改善阅读器的通信复杂度,节省系统的开销.     

Low complexity method for spreading sequence estimation of DSSS signal in non-cooperative communication systems

It is a necessary step to estimate the spreading sequence of direct sequence spread spectrum (DSSS) signal for blind despreading and demodulation in non-cooperative communications. Two innovative and effective detection statistics axe proposed to implement the synchronization and spreading sequence estimation procedure. The proposed algorithm also has a low computational complexity with only linear additions and modifications. Theoretical analysis and simulation results show that the algorithm performs quite well in low SNR environment, and is much better than all the existing typical algorithms with a comprehensive consideration both in performance and computational complexity.     

译码转发系统中一种半分布式用户选择策略

针对译码转发系统中传统的用户选择策略复杂度过高的问题,提出一种半分布式用户选择策(SDUS策略).该策略以最大化系统瞬时互信息量为目标,引入中继选择的判决门限,并根据此门限生成协作集,目的节点从协作集及源节点(当协作集为空集时)中选择信道质量最好的用户作为协作节点.SDUS策略不仅能够显著降低系统的运算复杂度,还能够改善系统的中断性能.仿真实验表明,当信噪比为20 dB且系统中的中继节点数为120时,SDUS策略的运算开销仅约为机会中继策略和选择协作策略的39.5%和51.1%.     

New algorithms for evaluating parametric surface

Through generalization of mathematical model of surface lofting program in the CONSURF system, the definitions for two generalized Ball surfaces and their recursive algorithms are given. Furthermore, the conversion al gorithms from Bézier surface to these two generalized Ball surfaces are presented. On the basis of these algorithms, two more efficient algorithms for evaluating parametric surfaces are also derived. One uses generalized Ball forms directly for evaluating surface, and the other converts the given Bézier surface to a generalized Ball surface firstly, and then evalu ates the surface. Both theoretical analysis and example computations show that the two new algorithms are more efficient than the de Casteljau algorithm. Especially when Wang-Ball surface is used, the time complexity is reduced from cubic to quadratic of the degree of the surface. If these algorithms are applied to displaying, interactive rendering, designing, intersection-finding, offsetting and approximating for surfaces, considerable economic results can be achieved.     

分形图像压缩的研究进展

分形图像压缩是一种具有独特优势且极有前途的数据压缩技术 ,至今未能广泛应用是由于其面临着高计算复杂度的困难。文中提出了克服这一困难的一些有效方法 ;同时 ,提出了改善重建图像视觉效果的措施 ,并探讨了分形图像编码的未来研究方向