Compressive sensing with sparse domain division using probability

With the development of Compressive Sensing theory in recent years, many new algorithms have been introduced to this field. But still, these algorithms tend to judge the probability of the nonzero signal in each position of the sparse domain as the same, which is in fact not true. In this topic we discuss orthogonal coefficient distribution and divide the whole sparse domain into different parts using probability. With the method called Sparse domain Division using Probability (SDP), the reconstructed speed would increase 20～60 times without producing any negative effect on image quality at the same sampling rate.     

Study of high efficiency of evaluation of a PDP in authorization service

In authorization service, the efficiency of evaluation of a PDP(policy decision point) is a key issue that affects the efficiency of authorization service. However, the efficiencies of evaluation of many PDPs available are frequently influenced by the factors of conditions in rules. Said Marouf et al put forward a method in which the evaluation speed can be increased by adjusting the rules in policies according to user history access records. This paper analyzes the shortcomings of this method in real-time applications, and proposes that the rules order in policies can be instantaneously adjusted by user history access records and indexes as well as self-adaptation are added to a PDP so that the evaluation speed can be increased substantially. Experimental results indicate that when there are 9795 rules in a PDP, the evaluation time and the time consumption taken for a PDP applied with indexes and self-adaptation to complete an authorized operation call are shortened by 93.33％ and 76.32％ respectively, compared with those for a PDP which is not applied with indexes and self-adaptation. When the number of repeat visits from the same user is 7, the time consumption taken for a PDP applied with indexes and adaptation to complete an authorized operation call is shortened by 24.29％ compared with that for a PDP which is applied with indexes only.     

Motion compensation approach for airborne bistatic SAR imaging

In airborne bistatic synthetic aperture radar (BiSAR) imaging, not only the motion error of the airborne platform, but also the inaccuracy of data acquisition geometry will introduce an additional phase error that seriously degrades the focusing quality of the final image. For one-stationary BiSAR imaging, the influence of the inaccurate geometry is analyzed in detail and an applicable motion compensation approach is proposed. By using Doppler rates estimation, the phase error both from the motion error and the inaccurate geometry is appropriately compensated so that the focusing quality of the final image is consequently improved. Analyses of acquired raw data are presented to verify the proposal.     

扫描成像系统的回波信号检测方法

为实现对隐蔽性很强的、被动工作的红外系统的有效探测，讨论了光学系统的后向反射特性，提出应用单频调制的连续激光对扫描式红外热成像目标进行有效探测的新方法．针对目标回波信号特征，提出利用回波信号的相位信息，采用直接采样的数字正交检波技术实现对低信噪比回波信号的可靠检测．应用该方案对实际目标回波信号获得了满意的检测结果．     

应用于洋流探测的改进MUSIC方法

对传统的MUSIC方法进行修正估计洋流方位，即在应用MUSIC方法之前，将阵列的协方差矩阵Toeplitz化，理论分析和仿真表明这样可有效地减小信号之闻相关性的影响，从而大大提高谱估计的质量．通过对实测数据的处理表明修正的MUSIC方法可较好地进行洋流方位探测．     

宽带相控阵雷达发射波束零点形成方法

在发射为线性调频信号的基础上．提出了一种宽带子阵数字发射波束形成新方法．该方法用数字权和时变相位权代替传统宽带子阵延时线方法波束形成中的移相器和时延线．这就避免使用存在量化误差且昂贵的模拟时延单元．此外．子阵内数字权可通过窄带波束零点形成的方法来构造并加宽凹口．最终实现了宽带发射波束零点形成．最后．计算机仿真证明了宽带数字方法能保持发射波形距离高分辨率并且可在干扰方向形成零点．     

椭圆缺陷轮廓的成品率估计

现有成品率及关键面积估计模型中。假定缺陷轮廓为圆。而70％的实际缺陷轮廓接近于椭圆．提出了椭圆缺陷轮廓的成品率模型，该模型与圆模型相比更具有一般性．而圆模型轮廓的成品率模型仅为新模型的特例．比较了新模型与真实缺陷及其圆模型引起的成品率损失。表明新模型在成品率估计方面更加精确．     

一种在不完全排错条件下的最优软件发行管理模型

提出了一种在不完全排错条件下的最优软件发行管理模型。该模型综合考虑了软件的不完全排错过程、在排错过程中可能会引入新的故障以及由于排错经验的不断积累，软件的完全排错概率会增加的情况．在一定可靠度约束的条件下。该模型使得总的平均费用达到最小．分析并给出了在模型参数取不同值时的最优软件发行时间．     

基于子空间投影的干涉合成孔径雷达基线误差估计

针对干涉合成孔径雷达中存在的基线误差会严重影响高程测量的精度问题，提出了一种新的干涉合成孔径雷达基线及卫星平台高度误差估计方法。利用地面目标点的信息．通过子空间投影的方法估计精确的干涉相位进而得到估计的基线误差。该方法不需要迭代搜索，运算量小．估计精度较高．对解缠的干涉相位具有较高的稳健性．且对噪声具有良好的抑制作用。     

无线移动通信网络拓扑有效性的研究

主要研究无线移动通信网络中节点初始位置、覆盖半径和速度对链路和拓扑的影响，采用二维随机行走方法，构建基于移动性时元的随机移动模型，通过数学分析和推导获得节点在不同时刻的链路有效性测度，并在此基础之上研究一定覆盖下所有节点移动总体特性，采用数学推导方法得出了拓扑有效性测度函数，数值仿真结果表明所提出的有效性测度能够用来描述节点的移动特性对链路和拓扑的影响。