一种基于GSM的低码率语音信息隐秘传输方法

本文描述了一种将一路低码率2．4kb／s混合激励线性预测（MELP）语音信息隐藏在另一路GSM编码的语音中,通过公共信道隐秘传输的方法。可将机密数据嵌入GSM语音中对人耳不敏感的比特,每（2L＋1）可修改比特,可嵌入2三比特数据而最多只修改其中的三比特,具有较高的嵌入率。隐藏在GSM语音中的低码率信息码率最高可达3．4kb／s。该方法,计算复杂度不高,易于硬件实现,从而可满足实时隐秘传输的要求。该方法已用微型机在局域网进行了模拟实验,获得了较好的结果。     

基于改进人工鱼群-蛙跳算法优化LSSVM参数短期负荷预测

短期电力负荷预测在电力系统安全调度、经济运行方面起到关键作用。在用最小二乘支持向量机进行负荷预测时,参数选择将直接影响预测精度。为了提高LSSVM负荷预测精度,文中提出一种基于Levy变异自适应视野人工鱼群-蛙跳算法对LSSVM进行参数优化的方法。以某县负荷、天气等历史数据对LSSVM进行训练,建立LAVAFSA-SFLA-LSSVM、AFSA-LSSVM、LAFSA-SFLA-LSSVM共3种预测模型,对该地区某日24 h的电力负荷进行预测。算例结果表明,LAVAFSA-SFLA-LSSVM预测精度比AFSA-LSSVM和LAFSA-SFLA-LSSVM更高,预测误差更小。     

一种基于Kd-tree射线追踪法的卫星RCS预估方法

针对空间卫星目标的雷达散射截面（RCS）预估问题,提出了一种基于Kd-tree射线追踪法的 改进物理光学（PO）方 法,实现了对具有较强耦合结构的卫星目标电磁特性计算。基于卫星目标的三维面元模型, 建 立了其对应的Kd-tree空间分割描述结构,将其用于射线追踪,结合PO方法就可以得到给定 模型的RCS预估值。数值计算结果表明,改进方法和MoM方法相比,具有相同计算精度但计算 效率高得多,相比单纯PO方法,改进方法也更接近测量值。     

移动通信2G向3G演进分析与策略

本文在描述ＧＳＭ和窄带ＣＤＭＡ向３Ｇ演进过程之后,从电信制造和移动运营两个市场层面上对３Ｇ国际市场演进情况进行了分析。在我国巨大的移动市场上,作者认为目前网络情况出发,向ＷＣＤＭＡ演进在网络覆盖、保护投资、国内支持等方面具有优势。     

一种用于TCM系统的均衡方法

本文介绍了一种适合于网格编码调制（ＴＣＭ）系统的均衡方法。这种方法基于预均衡结构,回避了网格译码不能提供判决反馈均衡（ＤＦＥ）所需的可靠的零时延判决的问题。本文从迫零判决反馈均衡器出发,利用网络编码市制的格形（Ｌａｔｔｉｃｅ）分割原理,推导出这种均衡器的结构。这种均衡器不但能够对带限符号间干扰信道进行均衡,而且当传输速度。较高时时,所采用的预均衡结构不影响预均衡器的输入序列的分布特性。因而可以支持     

侵彻过程中的墙角效应

对侵彻火箭弹的引信中发火决策方式进行总结。利用有限元动力学仿真软件Ls-Dyna完成对火箭弹以不同角度斜侵彻复杂目标过程中遇到墙角时的动力学仿真。根据仿真得到的位移,加速度数据,对单传感器的火箭弹侵彻引信进行讨论,发现其中存在的一些问题,如无法分辨水平和竖直目标,无法探测跳弹等情况,即墙角效应对于侵彻引信的影响,同时根据仿真数据分析了引信中利用两个传感器测量的优势。     

A signal adaptive diffusion filter for video coding: Mathematical framework and complexity reductions

In this paper we combine video compression and modern image processing methods. We construct novel iterative filter methods for prediction signals based on Partial Differential Equation (PDE) based methods. The mathematical framework of the employed diffusion filter class is given and some desirable properties are stated. In particular, two types of diffusion filters are constructed: a uniform diffusion filter using a fixed filter mask and a signal adaptive diffusion filter that incorporates the structures of the underlying prediction signal. The latter has the advantage of not attenuating existing edges while the uniform filter is less complex. The filters are embedded into a software based on HEVC with additional QTBT (Quadtree plus Binary Tree) and MTT (Multi-Type-Tree) block structure. In this setting, several measures to reduce the coding complexity of the tool are introduced, discussed and tested thoroughly. The coding complexity is reduced by up to 70% while maintaining over 80% of the gain. Overall, the diffusion filter method achieves average bitrate savings of 2.27% for Random Access having an average encoder runtime complexity of 119% and 117% decoder runtime complexity. For individual test sequences, results of 7.36% for Random Access are accomplished.     

Clustering‐based scheduling: A new class of scheduling algorithms for single‐hop lightwave networks

In wavelength division multiplexing (WDM) star networks, the construction of the transmission schedule is a key issue, which essentially affects the network performance. Up to now, classic scheduling techniques consider the nodes' requests in a sequential service order. However, these approaches are static and do not take into account the individual traffic pattern of each node. Owing to this major drawback, they suffer from low performance, especially when operating under asymmetric traffic. In this paper, a new class of scheduling algorithms for WDM star networks, which is based on the use of clustering techniques, is introduced. According to the proposed Clustering‐Based Scheduling Algorithm (CBSA), the network's nodes are organized into clusters, based on the number of their requests per channel. Then, their transmission priority is defined beginning from the nodes belonging to clusters with higher demands and ending to the nodes of clusters with fewer requests. The main objective of the proposed scheme is to minimize the length of the schedule by rearranging the nodes' service order. Furthermore, the proposed CBSA scheme adopts a prediction mechanism to minimize the computational complexity of the scheduling algorithm. Extensive simulation results are presented, which clearly indicate that the proposed approach leads to a significantly higher throughput‐delay performance when compared with conventional scheduling algorithms. We believe that the proposed clustering‐based approach can be the base of a new generation of high‐performance scheduling algorithms for WDM star networks. Copyright © 2008 John Wiley & Sons, Ltd.     

一种高并行度的H.264帧内预测器的VLSI设计

分析了帧内预测的17种模式,对于每个4×4大小块的16个像素点的不同模式的预测公式之间的相同运算,采用数字强度缩减的方法去除计算的冗余,提出了一种高并行度的帧内预测器,可以每个时钟周期处理16个像素点的预测值。基于SMIC0.18μm工艺,用verilog对该设计进行了VLSI实现,综合后的电路的关键路径最大时延为10ns,电路规模不超过1.4万门,数据吞吐率可以达到1600Msamples/s。从实现结果来看,与采用可重构方法的设计相比,该设计在相同的并行度下减小了电路面积,简化了控制逻辑。     

软件风险管理过程的研究与应用

软件风险是导致软件项目延迟、超预算或者失败的重要因素,风险管理是项目管理中一个重要的部分,自从巴里.鲍伊姆(Barry Boehm)把风险管理引入软件界以来,软件风险管理已经成为软件工程界的一个热点问题。针对风险管理的过程提出了多个模型,以其中得到广泛应用的持续风险管理模型为基础,介绍了风险管理过程,在此基础上重点讨论了对传统的风险计算公式的改进,并引入趋势分析进行风险预测。