一种基于P圈的单链路故障启发式算法研究

文章针对传统P圈保护算法计算时间长、资源利用率低的缺点,提出一种新的启发式算法,该算法以冗余度为评价标准,结合了未保护链路比率,在未保护链路数少的情况下能有效地约束P圈的扩张,只需一步就能计算出高效的P圈并100%保护光网络.通过在泛欧COST239网络和新泽西州LATA网络上仿真,表明该算法可以有效地减少配置P圈的数量,减少计算时间,提高网络的资源利用率.     

Single‐Crystalline Dodecahedral and Octodecahedralα‐Fe2O3 Particles Synthesized by a Fluoride Anion–Assisted Hydrothermal Method

Despite significant advances in iron oxide nanoparticles, it is still a challenge to synthesize regular polyhedral single‐crystalline α‐Fe₂O₃ particles because the surface energies of several low‐index planes are fairly similar. In the work presented here, well‐dispersed and single‐crystalline dodecahedral and octodecahedral α‐Fe₂O₃ particles are synthesized by a facile hydrothermal method with the aid of F^? anions. The crystalline structure of the polyhedral particles is disclosed by various characterization techniques. The dodecahedral particles are of hexagonal bipyramidal shape and enclosed by twelve equivalent (101) planes. The octodecahedral particles are formed by adding six equivalent (111) planes on the two tips of a dodecahedral particle, that is, they are enclosed by twelve (101) planes and six (111) planes. The existence of F^? anions plays a crucial role in the control of polyhedral particle shape. The function of F^? anions in the shape formation of the polyhedral particles is proposed as follows: 1) A high concentration of exposed Fe³⁺ cations induces preferential adsorption of F^? anions on the (100) plane and leads to the slowest growth along the [100] direction. When the concentration of F^? anions is higher than 24 mM , a stable speed ratio of growth along the [001] and [100] directions results in the exposure of (101) planes. 2) With a lower concentration of F^? anions, six symmetrical (111) planes with low concentration of exposed Fe³⁺ cations are present at the tops of a dodecahedral particle to form an octodecahedron. Furthermore, the dodecahedral and octodecahedral α‐Fe₂O₃ particles show much stronger magnetism than the previously reported α‐Fe₂O₃ nanostructures, having coercivities of 4986 Oe and 6512 Oe, respectively. Such high coercivities are attributed to a large local magnetic anisotropy, which might be induced by the polyhedron with equivalent crystallographic planes and/or the presence of F^? anions.     

SaaS安全技术研究

研究了SaaS模式的基本思想、特点和典型的体系架构,在此基础上分析了SaaS在实际应用中存在的安全问题,并分别从物理安全、数据存储、数据传输和身份管理认证四个方面对SaaS安全技术进行了研究.     

浅谈PTN技术在构建全业务承载的IP城域网中的应用与部署

随着电信运营商全业务运营战略的深入实施,在城域层面构建有QoS保障的综合业务传送网有其必要性,而在这样的进程中PTN技术以其固有的优势将发挥着重要作用。本文将分析构建全业务承载的IP城域网的相关驱动力、优化演进的路径等,探讨PTN技术的特性以及相关适用性,然后在上述基础上简析该技术在IP城域网优化演进中的应用场景和部署。     

面向公共安全监测的物联网技术与应用探讨

物联网的发展如火如荼,作为新兴高技术产业的重要组成部分,物联网技术广泛应用于各行各业。介绍物联网在公共安全领域的应用,对现阶段面向公共安全监测的物联网的网络架构、关键技术、应用现状以及发展中的若干问题进行了分析,同时对面向公共安全监测的物联网的发展前景进行了探讨,着重探讨了技术、应用发展方向。     

An improved SAR-GMTI method based on eigen-decomposition of the sample covariance matrix

An improved two-channel Synthetic Aperture Radar Ground Moving Target Indication (SAR-GMTI) method based on eigen-decomposition of the covariance matrix is investigated. Based on the joint Probability Density Function (PDF) of the Along-Track Interferometric (ATI) phase and the similarity between the two SAR complex images, a novel ellipse detector is presented and is applied to the indication of ground moving targets. We derive its statistics and analyze the performance of detection process in detail. Compared with the approach using the ATI phase, the ellipse detector has a better performance of detection in homogenous clutter. Numerical experiments on simulated data are presented to validate the improved performance of the ellipse detector with respect to the ATI phase approach. Finally, the detection capability of the proposed method is demonstrated by measured SAR data.     

VOIP在嵌入式终端中的实现

随着VOIP技术的成熟,通过互联网去实现一个即时通信已成为人们一种省钱方便的选择。本文研究了在嵌入式终端实现一个基于SIP协议软电话功能的方法。其中详细讨论了利用S3C2440与UDA1341TS在IIS总线下搭建一个硬件环境及相应的驱动方法,进而为实现声音通信服务。同时讨论了SIP软电话的详细移植过程。     

LDPC code design for asynchronous Slepian-Wolf coding

We consider asynchronous Slepian-Wolf coding where the two encoders may not have completely accurate timing information to synchronize their individual block code boundaries, and propose LDPC code design in this scenario. A new information-theoretic coding scheme based on source splitting is provided, which can achieve the entire asynchronous Slepian-Wolf rate region. Unlike existing methods based on source splitting, the proposed scheme does not require common randomness at the encoder and the decoder, or the construction of super-letter from several individual symbols. We then design LDPC codes based on this new scheme, by applying the recently discovered source-channel code correspondence. Experimental results validate the effectiveness of the proposed method.     

A Novel Test Point Selection Method for Analog Fault Dictionary Techniques

Most of the recently reported test point selection algorithms for analog fault dictionary techniques are based on integer-coded table (ICT) technique. Hence, the accuracy of these algorithms is closely related to the accuracy of the ICT technique. Unfortunately, this technique is not accurate, especially when the size of fault dictionary is large. This paper proposes an accurate fault-pair Boolean table technique for the test point selection problem. First, the approach to transform the fault dictionary into a fault-pair Boolean table is introduced. Then, a test point selection algorithm based on the fault-pair Boolean table is proposed. Thirdly, several example circuits are used to illustrate the proposed algorithm. Simulated results indicate that the proposed method is more accurate than the other methods. Therefore, it is a good solution for minimizing the size of the test point set.