开放路由平台中OSPF Graceful Restart的研究与实现

GracefulRestart是一种旨在使路由协议重启的影响最小化的机制,其目的是尽量减少路由器重启导致的路由抖动,减少路由计算资源和网络带宽资源的浪费。在对GracefulRestart机制作深入研究的前提下,对开放路由平台Quagga进行了OSPFGracefulRestart扩展,实现了原型系统。

基于Deflation技术的预调制Restarted GMRES算法

电学层析成像的图像重建需要对逆问题进行求解,而求解过程中存在着非线性、欠定性以及病态性严重等难题,使得图像重建可能不收敛,或者致使收敛,但获得的图像分辨率较低。针对现有的一些图像重建算法,提出基于Deflation技术的预调制Restarted GMRES算法,在原有full GMRES算法基础上,提高了收敛速度以及图像成像分辨率,并通过仿真实验证明。

Oracle Restart在Oracle 19C中的应用

以Oracle 19C为例,阐述其在数据库软硬件出现故障时,尤其是数据库所在主机异常宕机重启后,通过Oracle Restart功能保障Oracle数据库实例、监听等关键组件在非人为干预下可以自动重启,使数据库持续、可靠地对外提供服务成为可能.

RESTART亚组分析:通过影像学特征评价脑出血后重启抗血小板治疗对卒中复发风险的影响

2019年5月Lancet Neurol杂志发表了RESTART研究的亚组分析,题目为"Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases:subgroup analyses of the RESTART randomised,open-label trial"。1研究介绍1.1研究背景既往研究提示具有脑出血和脑小血管病的影像学特征与脑出血复发风险增加有关。目前指南及一些学者等建议根据这些影像学特征可用于指导脑出血后是否重启抗血小板治疗。

Adaptive restarting method for LCC-HVDC based on principle of fault location by current injection

The existing LCC-HVDC transmission project adopts the fixed-time delay restarting method.This method has disadvantages such as non-selectivity,long restart process,and high probability of restart failure.These issues cause a secondary impact on equipment and system power fluctuation.To solve this problem,an adaptive restarting method based on the principle of fault location by current injection is proposed.First,an additional control strategy is proposed to inject a current detection signal.Second,the propagation law of the current signal in the line is analyzed based on the distributed parameter model of transmission line.Finally,a method for identifying fault properties based on the principle of fault location is proposed.The method fully considers the influence of the long-distance transmission line with earth capacitance and overcomes the influence of the increasing effect of the opposite terminal.Simulation results show that the proposed method can accurately identify the fault properties under various complex fault conditions and subsequently realize the adaptive restarting process.

A New Type of Restarted Krylov Methods

In this paper we present a new type of Restarted Krylov methods for calculating peripheral eigenvalues of symmetric matrices. The new framework avoids the Lanczos tridiagonalization process, and the use of polynomial filtering. This simplifies the restarting mechanism and allows the introduction of several modifications. Convergence is assured by a monotonicity property that pushes the eigenvalues toward their limits. The Krylov matrices that we use lead to fast rate of convergence. Numerical experiments illustrate the usefulness of the proposed approach.

Fault Handling in PLC-Based Industry 4.0 Automated Production Systems as a Basis for Restart and Self-Configuration and Its Evaluation

Industry 4.0 and Cyber Physical Production Systems (CPPS) are often discussed and partially already sold. One important feature of CPPS is fault tolerance and as a consequence self-configuration and restart to increase Overall Equipment Effectiveness. To understand this challenge at first the state of the art of fault handling in industrial automated production systems (aPS) is discussed as a result of a case study analysis in eight companies developing aPS. In the next step, metrics to evaluate the concept of self-configuration and restart for aPS focusing on real-time capabilities, fault coverage and effort to increase fault coverage are proposed. Finally, two different lab size case studies prove the applicability of the concepts of self-configuration, restart and the proposed metrics.

A RESTARTING DIRECTION FOR THE CONJUGATE GRADIENT METHOD

The main purpose of this paper is to provide a restarting direction for improving on the standard conjugate gradient method.If a drastic non-quadratic behaviour of the objective function is observed in the neighbour of xk,then a restart should be done.The scaling symmetric rank-one update with Davidon’s optimal criterion is applied to generate the restarting direction.It is proved that the conjugate gradient method with this strategy retains the quadratic termination.Numerical experiments show that it is successful.

一次SCALSVT RESTART故障的解决

对一次SCALSVTRESTART故障的查排过程进行了分析。

Biased random walk with restart for essential proteins prediction

Predicting essential proteins is crucial for discovering the process of cellular organization and viability.We propose biased random walk with restart algorithm for essential proteins prediction,called BRWR.Firstly,the common process of practice walk often sets the probability of particles transferring to adjacent nodes to be equal,neglecting the influence of the similarity structure on the transition probability.To address this problem,we redefine a novel transition probability matrix by integrating the gene express similarity and subcellular location similarity.The particles can obtain biased transferring probabilities to perform random walk so as to further exploit biological properties embedded in the network structure.Secondly,we use gene ontology(GO)terms score and subcellular score to calculate the initial probability vector of the random walk with restart.Finally,when the biased random walk with restart process reaches steady state,the protein importance score is obtained.In order to demonstrate superiority of BRWR,we conduct experiments on the YHQ,BioGRID,Krogan and Gavin PPI networks.The results show that the method BRWR is superior to other state-of-the-art methods in essential proteins recognition performance.Especially,compared with the contrast methods,the improvements of BRWR in terms of the ACC results range in 1.4%–5.7%,1.3%–11.9%,2.4%–8.8%,and 0.8%–14.2%,respectively.Therefore,BRWR is effective and reasonable.

Restarted Adomian Decomposition Method for Solving Volterra’s Population Model

In this paper, we used an efficient algorithm to obtain an analytic approximation for Volterra’s model for population growth of a species within a closed system, called the Restarted Adomian decomposition method (RADM) to solve the model. The numerical results illustrate that RADM has the good accuracy.

面向ForCES路由器结构的BGP Graceful Restart技术研究

本文在介绍转发控制分离体系结构和网络高可用性相关技术的基础上,系统地介绍了BGPGracefulRestart扩展技术。在GracefulRestart技术的支持下,路由器能够在控制系统故障重启后,在重新建立网络邻接关系的过程中保持转发平台继续转发数据,从而避免了暂时性的路由振荡。最后,文章重点描述了基于转发控制分离结构IPv6路由器平台环境的BGPGracefulRestart实现方案。

基于OSPF协议的GracefuI Restart技术的研究与实现

随着网络规模的不断扩大,网络速度的快速提升,网络与通信的新技术不断融入,用户越来越需要更丰富、更方便、更及时的网络应用和服务,互联网的这些特征导致新一代互联网概念的产生。为了提高网络可用性,IETF提出了对路由协议的扩展来减少由于路由协议失效造成的业务损失。在网络边缘路由器和其邻居路由器都支持OSPF平稳重启情况下,即使控制平面失效,数据平面也能够继续处理和转发报文。由于减少了路由抖动,平稳重启能够增加网络稳定性并减少控制平面资源的消耗。从而不单单增强了单台路由器的可用性,更提高了整个网络的可用性。

Restarted FOM Augmented with Ritz Vectors for Shifted Linear Systems

The restarted FOM method presented by Simoncini[7]according to the natural collinearity of all residuals is an efficient method for solving shifted systems,which generates the same Krylov subspace when the shifts are handled simultaneously.However,restarting slows down the convergence.We present a practical method for solving the shifted systems by adding some Ritz vectors into the Krylov subspace to form an augmented Krylov subspace. Numerical experiments illustrate that the augmented FOM approach(restarted version)can converge more quickly than the restarted FOM method.

Global Convergence of a New Restarting Conjugate Gradient Method for Nonlinear Optimizations

Conjugate gradient optimization algorithms depend on the search directions.with different choices for the parameters in the search directions.In this note,by combining the nice numerical performance of PR and HS methods with the global convergence property of the class of conjugate gradient methods presented by HU and STOREY(1991),a class of new restarting conjugate gradient methods is presented.Global convergences of the new method with two kinds of common line searches,are proved .Firstly,it is shown that,using reverse modulus of continuity funciton and forcing function,the new method for solving unconstrained optimization can work for a continously differentiable function with Curry-Altman's step size rule and a bounded level set .Secondly,by using comparing technique,some general convergence propecties of the new method with other kind of step size rule are established,Numerical experiments show that the new method is efficient by comparing with FR conjugate gradient method.

Global Convergence of a New Restarting Three Terms Conjugate Gradient Method for Non-linear Optimizations

在这笔记，由把 PR 和 HS 方法的好数字表演与 FR 方法的全球集中性质相结合，新重启的一个班三项条款结合坡度方法被介绍。有二种普通的线搜索的新方法的全球集中性质被证明。

An Implicitly Restarted Block Arnoldi Method in a Vector-Wise Fashion

In this paper, we develop an implicitly restarted block Arnoldi algorithm in a vector-wise fashion. The vector-wise construction greatly simplifies both the detection of necessary deflation and the actual deflation itself, so it is preferable to the block-wise construction. The numerical experiment shows that our algorithm is effective.

Optimal Rapid Restart of Heuristic Methods of NP Hard Problems

Many heuristic search methods exhibit a remarkable variability in the time required to solve some particular problem instances. Their cost distributions are often heavy-tailed. It has been demonstrated that, in most cases, rapid restart (RR) method can prominently suppress the heavy-tailed nature of the instances and improve computation efficiency. However, it is usually time-consuming to check whether an algorithm on a specific instance is heavy-tailed or not. Moreover, if the heavy-tailed distribution is confirmed and the RR method is relevant, an optimal RR threshold should be chosen to facilitate the RR mechanism. In this paper, an approximate approach is proposed to quickly check whether an algorithm on a specific instance is heavy-tailed or not. The method is realized by means of calculating the maximal Lyapunov exponent of its generic running trace. Then a statistical formula to estimate the optimal RR threshold is educed. The method is based on common nonparametric estimation, e.g., Kernel estimation. Two heuristic methods are selected to verify our method. The experimental results are consistent with the theoretical consideration perfectly.

真空泵用屏蔽电机无传感器残压重投控制策略

针对真空干泵机组故障、生产工艺需要等原因影响真空设备产线在线运行时间的问题,研究真空干泵用屏蔽式感应电机带速重投策略,寻求重投的有利时刻以保证带速重投的成功,对电机断电后的转速和定子失电残压特性展开研究。为此,根据屏蔽感应电机空间向量模型,建立基于电压电流混合磁链观测的无速度传感器估算模型、推导电机断电期间的转速估算方法以及定子失电残压解析式。通过重点研究定子残压和虚拟重投电压间幅值特性和相角特性,确定控制系统的首次重投点和其次重投点。以4 kW真空干泵用屏蔽感应电机机组为例,通过模型仿真和失电残压实验验证了该控制方法在泵类工程中有较好的适用性和准确性,重投阶段的转速稳定时间为0.5 s以内,重投阶段的冲击电流平均减小59.18%。