FRFT与PTS联合降低OFDM系统峰均功率比的方法

针对OFDM系统的高PAPR,提出了将FRFT与PTS相结合的方法解决这一问题。首先利用FRFT代替FFT,使得系统的PAPR在适当的阶次下有了一定的下降。为更加有效地降低系统PAPR,将FRFT与PTS法相结合应用到OFDM中,并根据FRFT的酉性,简化了最优阶次的搜索算法,寻找出当系统阶次为0.006时其PAPR性能达到最优。仿真结果表明,当CCDF=10-4时,最优阶次下的OFDM系统将其PAPR降低了约7 dB,比使用传统PTS法时降低了约4 dB。     

A framework for predictive modeling of anatomical deformations

A framework for modeling and predicting anatomical deformations is presented, and tested on simulated images. Although a variety of deformations can be modeled in this framework, emphasis is placed on surgical planning, and particularly on modeling and predicting changes of anatomy between preoperative and intraoperative positions, as well as on deformations induced by tumor growth. Two methods are examined. The first is purely shape-based and utilizes the principal modes of co-variation between anatomy and deformation in order to statistically represent deformability. When a patient's anatomy is available, it is used in conjunction with the statistical model to predict the way in which the anatomy will/can deform. The second method is related, and it uses the statistical model in conjunction with a biomechanical model of anatomical deformation. It examines the principal modes of co-variation between shape and forces, with the latter driving the biomechanical model, and thus predicting deformation. Results are shown on simulated images, demonstrating that systematic deformations, such as those resulting from change in position or from tumor growth, can be estimated very well using these models. Estimation accuracy will depend on the application, and particularly on how systematic a deformation of interest is.     

民用导航型C／A码GPS接收机动态定位的强跟踪卡尔曼滤波研究

本文提出了一种改进的强跟踪卡尔曼滤波算法,应用于ＧＰＳ动态定位获得明显效果,首先建立了一种新的ＧＰＳ动态定位滤波模型,该模型与以往采用的非线性卡尔曼滤波模型相比,滤波精度得到提高,且模型简单,系统运算量降低,实时性较好,然后,为了进一步提高滤波器的动态性能,改进了文献中的强跟踪滤波器,大大提高了滤波器的跟踪能力。     

有限放大倍数下磁透镜的球差和色差系数

磁透镜的球差和色差系数可表为放大倍数的多项式，本文通过计算给出了多项式的系数，并拟合出精度较高的表达式，可以方便地计算出有限放大倍数下的球差和色差系数。     

石墨掺杂对B/KNO_3点火药的激光点火特性的影响

用光声检测的实验方法研究石墨掺杂对B／KNO3点火药的激光点火性能的影响。根据对光声谱的分析，指出了石墨掺入B／KNO3会略降低B／KNO3的激光吸收能力并且掺入量增加时，药剂的光吸收能力会有所改善。石墨掺杂会增长B／KNO3的激光点火延迟期，这一规律与石墨掺杂对B／KNO3的吸光性能的影响规律一致。     

视频点播系统(VOD)现状与未来

本文介绍了两种VOD系统的框架结构、工作原理，阐述了VOD的关键技术问题：机顶盒、视频服务器技术，并对VOD的发展作了预测。     

片式叠层压敏电阻器及其应用

用流延工艺把电极层和半导体陶瓷交错排布，经烧结而成的片式叠层压敏电阻器，其结构类似多层陶瓷电容器。通过与氧化锌压敏电阻器及其他压敏电阻器比较表明，片式叠层压敏电阻器具有优良的性能。并论述这类压敏电阻器在ＩＣ保护、ＣＭＯＳ器件保护、汽车电路系统保护等方面的应用。     

舰载雷达抗反辐射导弹的有关问题

首先论述舰载雷达抗反辐射导弹的特点,接着给出了两点源干扰法对抗反辐射导弹的理论分析。在反幅射导弹雷达导引头天线方向图函数线性近似的条件下,对相干两点源和非相干两点源,导出了导引头的角跟踪误差公式。在此基础上,讨论了实现两点源干扰如何配置两个干扰源问题,以及两辐射源的天线波束、脉冲延迟、信号强度和相对相位应满足的条件。最后,简述了抗反辐射导弹的其它措施。     

水轮机动态模型试验微机测控

利用微机测控水轮机动态模型试验台，可以实现参数率定，用键盘控制导叶、桨叶开关，和自动检测转速、扭矩、轴向力、水压力，导叶、桨叶行程等参量，同时，还能任意选择导叶关闭规律，自动生成试验数据图表．测控软件采用菜单模式，汉字提示，通过键盘人机对话进行操作．软件分初始化软件、人机对话软件和时钟中断软件．初始化软件用于硬件初始化及中断矢量的设置；人机对话软件用于功能选择；实时钟中断软件由硬件8253－1的OUT1定时启动，完成有定时要求的各任务的计时．微机测控试验，测量精度高，试验质量高，速度快，值得推广．     

CLTC: a cluster-based topology control for ad hoc networks

The topology of an ad hoc network has a significant impact on its performance in that a dense topology may induce high interference and low capacity, while a sparse topology is vulnerable to link failure and network partitioning. Topology control aims to maintain a topology that optimizes network performance while minimizing energy consumption. Existing topology control algorithms utilize either a purely centralized or a purely distributed approach. A centralized approach, although able to achieve strong connectivity (k-connectivity for k /spl ges/ 2), suffers from scalability problems. In contrast, a distributed approach, although scalable, lacks strong connectivity guarantees. We propose a hybrid topology control framework, cluster-based topology control (CLTC) that achieves both scalability and strong connectivity. By varying the algorithms utilized in each of the three phases of the framework, a variety of optimization objectives and topological properties can be achieved. In this paper, we present the CLTC framework; describe topology control algorithms based on CLTC and prove that k-connectivity is achieved using those algorithms; analyze the message complexity of an implementation of CLTC, namely, CLTC-A, and present simulation studies that evaluate the effectiveness of CLTC-A for a range of networks.