西南某水电站谷底深厚覆盖层与卸荷松弛带特征及其成因机制分析

钻孔揭示,该水电站河谷谷底发育着深厚覆盖层及卸荷松弛带。深厚覆盖层纵向上可以分为3层:下部和上部为正常的河流相,中部为多成因堆积物加积层;谷底浅表部岩体结构松弛,完整性差,裂隙张开、泥质充填,裂面严重风化锈染。研究表明,谷底松弛是由于河流切至谷底时造成应力集中,导致岩体剪切破坏;并经过漫长的卸荷回弹及风化作用在谷底形成一定厚度的松弛带。     

机载视频叠加单元的设计与实现

视频叠加技术已经广泛应用于航空电子显示系统,高速飞行状态中的航空飞行器能否快速准确无抖动地显示特定目标成为视频显示技术领域研究的重点。传统的基于DSP的图像叠加技术,功耗较高,且图像实时传输效率低,随着航空电子技术的发展,其越来越难以满足航空飞行器视频信号的实时性显示。本设计在传统DSP视频处理硬件平台上[1],构造出一种改进的视频采集捕获平台,并提出相应的硬件实现逻辑以及实现结果,处理结果表明,本设计视频叠加显示技术画面流畅无抖动,具有良好的叠加效果。     

Overlay networking： applications and research challenges

Overlay networking is one of the perspective solutions to today‘s Internet challenges. At basic service level, overlay networks can serve as a supplement and enhancement of existing services, such as routing and addressing. At high application level, overlay networks can be used for applications, which are difficult to deploy in existing IP architecture with some specific reasons, e.g., they need high-level information, which is hard to obtain by underlying layers. To address the heterogeneity of today‘s Internet, overlay networks provide ways to service availability and desirable performance while retaining scalability. In contrast to changing the existing network layer, overlay networks allow bootstrapping, which is most important in the development of Internet infrastructure. Various applications of overlay networking are clarified in this paper. Research challenges including routing and searching in overlay networking are also identified.     

电子束曝光数据格式的改进设计与实现

根据中国科学院电工研究所研制的DY-2000型实用化电子束曝光系统对曝光图形数据格式的要求及用户的需要,对原曝光文件格式(EDF)进行了改进,利用VC++6.0开发环境实现了EDF格式文件的图形创建、结构体引用以及文件保存,同时增加了多层图形套刻和邻近效应修正数据处理的功能。实验结果表明,改进后的电子束曝光图形文件格式可满足用户的需求,便于用户新建版图文件,同时也提高了文件传输速度及曝光的效率。     

MMSE RAKE Reception for Asynchronous DS/CDMA Overlay Systems and Frequency-Selective Fading Channels

In this work the authors introduce and analyze a detection scheme for simultaneous suppression ofmultiaccess and digital narrowband interference (NBI) for an asynchronousDS/CDMA system operatingover a frequency-selective fading channel. The proposed detector may possibly consider a processing interval greater than the bit-interval, andamounts to a RAKE structure, wherein each branch is designed under an MMSE optimization strategy, followedby a propercombining rule. It is shown that narrowband interference rejection entails ingeneral a time-varyingdetection structure. As to the performance assessment, we give closed-form formulas for the systemBit Error Rate (BER),Near-Far Resistance and Signal-to-Interference Ratio (SIR).Numerical results show that the proposed receiver proves effective in suppressing interference, and that itlargely outperforms conventional multiuser detectors which do not account forthe presence of theNBI, at the price of little complexity increase.Finally, we provide a blind adaptive implementation of the proposedreceiver, based on the exponentially weighted Recursive-Least-Squares (RLS)algorithm, andrequiring knowledge of the relevant parameters of the desired user only, andof the NBI signaling time.     

Space-Time Optimum Combining for CDMA Overlay for Personal Communications Systems

The requirement to suppress narrowband interferences in CDMA communication stems from the overlay concept, i.e., coexistence of different types of signals in the same frequency band. This paper describes the performance analysis of a direct-sequence (DS) CDMA personal communication system sharing a common spectrum with narrowband microwave radio links in the 1.85 to 1.99 GHz band. The coexistence of these two systems within the same frequency band will improve the overall spectrum efficiency, but will also cause interference to both systems. In this paper it is shown that joint spatial and temporal optimum combining provides an efficient means of improving the performance of the DS-CDMA system through cancellation of the narrowband signal and the co-channel interferences. The proposed space-time architecture provides degrees of freedom for both diversity and interference cancellation. It is shown that the joint space-time receiver is robust with respect to the narrowband interference signal bandwidth and its carrier frequency offset from the DS-CDMA carrier frequency.     

物流中心选址的多目标优化模型

针对一个经纬型网络中的最优选址问题,借鉴选址问题的已有理论和方法,建立了一个新的数学模型.研究了该模型的实际可行算法,结果表明该算法所求解是最优的,为运输、供销、物流系统的实际部门提供了有效的方法.     

基于Gossip机制的自组织覆盖网络拓扑管理协议(英文)

Gossip-based protocols have attracted more and more attention because of their simplicity and reliability.They can be applied to large-scale overlays for solving problems such as topology management,information dissemination,and aggregation.However,previous works sample nodes by their indegrees,without considering the differences in capability among nodes,and result in losing global load balancing.This paper proposes a load balancing gossip protocol for self-organizing overlays-LBTMP(Load-Balancing Topology...     

卫星广播信号上重叠发射导航增强信号的方法

提出了一种在卫星广播信号上重叠发射卫星导航增强信号的方法,将差分校正数据经过扩频后发射出去,与卫星广播信号进行频谱重叠,一起经卫星转发。通过参数设计和性能仿真可知,差分增强信号对广播信号的接收解调影响很小,差分接收机可以通过串行干扰抵消的方法从混合信号中提取出差分增强信号,实现解扩与辅助测距,解扩得到的差分校正数据可直接用于差分定位。当混合功率比为26 dB时,捕获概率达99.99%,测距精度为10.67 m,表明了此方法的可行性。     

基于覆盖网络的多路径流量均衡研究

现有网络发送数据都集中在一条最优路径上,使得网络流量不均衡,拥塞不可避免.传统的IP网络难以拓展,文章在应用层上对覆盖网络进行流量均衡,利用覆盖网络之间的互动性给出了覆盖网络的多路径流量均衡模型,在该模型上研究了输入流量和输出流量的分配算法,并通过仿真实验说明了可以有效地减小网络的端到端延迟.