基于GMPLS的最优恢复路径选择算法

在总结、比较当前各种GMPLS恢复机制性能的基础上,结合了保护机制恢复时间快、恢复机制的资源利用率高的优点,提出了一种动态最优恢复路由选择算法.该算法不仅在出现多处网络故障的情况下,根据预留的恢复路径,动态寻找分配恢复路径,而且可以保证保护路径的资源利用率最优.     

一种面向多业务恢复的路由优化算法

讨论了在WDM光传送网中完成多业务恢复时所出现的恢复路由资源竞争问题，并提出了一种基于遗传算法的面向多业务恢复的路由优化算法。该算法可以有效地解决恢复路由资源竞争问题，得到全局最优恢复路由。通过对实际网络的计算，验证了该算法在解决多业务恢复路由优化问题上所具备的优势。     

一种基于多QoS约束的T-MPLS恢复算法

文章在分析传统算法存在的问题的基础上,提出一种基于多服务质量(QoS)约束的传送多协议标签交换(T-MPLS)恢复算法(MQCTR);为提高恢复路径建立的成功率,结合约束路由思想,提出了基于多QoS门限约束的路由机制;以网状网为例,对算法性能进行了仿真分析.该算法不仅支持多种恢复模式,而且具备多业务区分功能,对提高运营级T-MPLS网络的生存性和健壮性具有重要意义.     

一种SDN中基于SR的多故障恢复与规避机制

针对SDN中的多故障恢复问题,提出了一种基于分段路由的多故障恢复与规避机制.为实现故障的快速恢复,在数据平面通过SR技术预部署一个可对多故障提供快速恢复能力的链路环备份系统;为防止故障恢复时造成部分链路负载过重引发再故障,提出最优化流量平滑算法对负载超过设定阈值的链路实施流量均衡处理.实验结果表明,与已有的SDN多故障恢复机制OAM-Based和Fast Failover相比,所提机制的平均故障恢复成功率分别提高了6.7%和8.5%,且控制器通信开销仅为传统OpenFlow方案的9%,同时,所提机制对故障恢复时导致的链路负载过重问题进行了处理,从故障规避的角度为网络提供保护.     

基于遗传算法的WDM光传送网恢复优化算法

本文针对WDM光传送网的网络恢复问题,提出了一种基于遗传算法的恢复路由优化算法.在满足多重约束的条件下,该算法可处理不同故障情况下的多种最佳恢复路由的选取问题.通过对实际网络的计算,验证了该算法具有较强的实用性.     

WDM光网络的恢复技术

文章介绍了光网络的生存技术，并重点介绍了Mesh网络中的恢复技术，分析了恢复技术的特点，策略，各种路由和波长分配算法选择，并进行了性能比较，同时给出了恢复的时间分析。     

一种基于波长路由光网络的分布式恢复技术

简要介绍了对于Mesh网络中的单链路故障所采取的各种恢复技术,并在此基础之上提出了一种在具有波长路由能力的Mesh光网络中针对于单链路故障的分布式恢复技术。通过仿真分析可知,这种新技术在恢复时间和资源利用率方面均表现出优越的性能。     

不同网络技术融合的三种恢复机制的研究

介绍三种由不同网络技术融合的内层恢复机制:光恢复和MPLS TE FRR、SONET/SDH保护和IP路由、MPLS TE FRR和IP重路由.从恢复动作和所需备份容量的角度分别讨论这三种融合技术.     

移动自组网络中一种基于选播策略的路由恢复方法

独立于路由算法对路由恢复方法进行了研究,并在选播策略的基础上,提出了一种路由恢复方法。模拟测试表明该方法具有平均路由恢复延时较短和平均控制字节数较少的特点。     

应用于IP网络故障恢复的多拓扑生成算法研究

本文介绍了多拓扑路由(MTR)技术在IP网络故障恢复领域的应用,通过建立数学模型提出一种多拓扑生成方案,可在网络发生双链路失效时平衡拓扑负载.     

Efficient distributed restoration path selection for shared mesh restoration

In MPLS/GMPLS networks, a range of restoration schemes will be required to support different tradeoffs between service interruption time and network resource utilization. In light of these tradeoffs, path-based end-to-end shared mesh restoration provides a very attractive solution. However, efficient use of bandwidth for shared mesh restoration strongly relies on the procedure for selecting restoration paths. We propose an efficient restoration path selection algorithm for restorable connections over shared bandwidth in a fully distributed MPLS/GMPLS architecture. We also describe how to extend MPLS/GMPLS signaling protocols to collect the necessary information efficiently. To evaluate the algorithm's performance, we compare it via simulation with two other well-known algorithms on a typical intercity backbone network. The key figure of merit for restoration bandwidth efficiency is restoration overbuild, i.e., the extra bandwidth required to meet the network restoration objective as a percentage of the bandwidth of the network with no restoration. Our simulation results show that our algorithm uses significantly less restoration overbuild (63%-68%) compared with the other two algorithms (83%-90%).     

Broadband network restoration

In broadband networks, it is expected that at a given time there will be more data in the network than in narrowband networks, and therefore, to maintain the same quality of service, failures will need to be restored much faster. The purpose of this article is to demonstrate that broadband network technology, and in particular the asynchronous transfer mode (ATM), has factors that enable much faster restoration in broadband networks. These can be summarized as: (i) the higher-speed processing and larger-volume storage possible with today's technology as compared to what was available for narrowband networks, (ii) faster failure detection by making use of ATM cell header error checks, (iii) easier and faster rerouting simply by changing cell headers, (iv) easier and faster splitting of virtual paths by changing cell headers, (v) higher fill factors in the new digital hierarchy due to full termination at cross-connects and switches, and (vi) the statistical multiplexing advantage that can be exploited in a full ATM network configuration. The authors describe four basic characteristics of broadband network restoration, made faster and more efficient because of the factors listed above. These are (i) hitless protection switching, (ii) robust and fast failure detection, (iii) restoration alternatives in broadband networks, and (iv) fast topology update for multiple failures. By employing a combination of these methods, fast restoration of broadband networks can be achieved. The techniques described enable a B-ISDN/ATM network to be constructed that is highly self-healing (i.e., can recover from failures without human intervention) and very fast     

Digital image restoration

The article introduces digital image restoration to the reader who is just beginning in this field, and provides a review and analysis for the reader who may already be well-versed in image restoration. The perspective on the topic is one that comes primarily from work done in the field of signal processing. Thus, many of the techniques and works cited relate to classical signal processing approaches to estimation theory, filtering, and numerical analysis. In particular, the emphasis is placed primarily on digital image restoration algorithms that grow out of an area known as “regularized least squares” methods. It should be noted, however, that digital image restoration is a very broad field, as we discuss, and thus contains many other successful approaches that have been developed from different perspectives, such as optics, astronomy, and medical imaging, just to name a few. In the process of reviewing this topic, we address a number of very important issues in this field that are not typically discussed in the technical literature     

Image restoration in computed tomography: restoration of experimental CT images

It is pointed out that to restore experimental computed tomography (CT) images which have been blurred by a spatially variant point spread function (PSF), a quadrant symmetry method which simultaneously optimizes storage requirements for the estimated PSFs and computational speed is used. The quadrant symmetry approach required less than 0.579 Megawords of storage for 9x9 pixel spatially variant PSFs in a 256x256 pixel image, allowing image restoration in Cartesian coordinates. A locally adaptive restoration method formulated using a noise prewhitening filter derived from the measured noise power spectrum, the conjugate gradient method was used to obtain a numerical solution. Restored images for a resolution phantom and for a cadaver femur are presented.     

Edge-based image restoration.

In this paper, we propose a new image inpainting algorithm that relies on explicit edge information. The edge information is used both for the reconstruction of a skeleton image structure in the missing areas, as well as for guiding the interpolation that follows. The structure reconstruction part exploits different properties of the edges, such as the colors of the objects they separate, an estimate of how well one edge continues into another one, and the spatial order of the edges with respect to each other. In order to preserve both sharp and smooth edges, the areas delimited by the recovered structure are interpolated independently, and the process is guided by the direction of the nearby edges. The novelty of our approach lies primarily in exploiting explicitly the constraint enforced by the numerical interpretation of the sequential order of edges, as well as in the pixel filling method which takes into account the proximity and direction of edges. Extensive experiments are carried out in order to validate and compare the algorithm both quantitatively and qualitatively. They show the advantages of our algorithm and its readily application to real world cases.     

Constrained iterative restoration algorithms

This paper describes a rather broad class of iterative signal restoration techniques which can be applied to remove the effects of many different types of distortions. These techniques also allow for the incorporation of prior knowledge of the signal in terms of the specification of a constraint operator. Conditions for convergence of the iteration under various combinations of distortions and constraints are explored. Particular attention is given to the use of iterative restoration techniques for constrained deconvolution, when the distortion band-limits the signal and spectral extrapolation must be performed. It is shown that by predistorting the signal (and later removing this predistortion) it is possible to achieve spectral extrapolation, to broaden the class of signals for which these algorithms achieve convergence, and to improve their performance in the presence of broad-band noise.     

Multiple resolution image restoration

A new algorithm for solving the deconvolution problem is proposed. This algorithm uses the wavelet transform to induce a multiresolution approach to deconvolve a blurred signal/image. The low resolution part of a signal/image is restored first and then high resolution information is added successively into the estimation process. Two different ways to incorporate the image space positivity constraint, namely loosely and strictly, are discussed. In to most restoration algorithms, the positivity constraint is applied directly in the transformed domain. The performance of the algorithm in the presence of noise is also investigated     

图像复原算法研究

研究了几种经典图像复原算法,在已知系统退化模型的情况下,对观测图像分别使用逆滤波、维纳滤波、有约束的最小二乘方滤波算法进行复原,在这几种算法的参数选取上得到了丰富的经验数据,并对实验结果进行了分析总结.     

一种改进的数字图像修复方法

针对既含有划痕又含有大块缺失信息的数字图像,文中提出了一种基于改进BSCB模型和改进Criminisi算法的图像修复方法。首先,采用改进的BSCB模型修复图像中的划痕,然后再用一种改进优先级的Criminisi算法进行大块缺失信息的修复,最后将文中提出的修复方法与单独使用BSCB模型和单独使用Criminisi算法的修复效果进行对比,实验结果表明文中提出的方法的修复效果更好。