基于PCA-Logistic模型的围岩稳定性分类研究

为了建立易于理解和应用的围岩稳定性分类模型,采用主成分分析法对围岩样本数据进行降维处理,以Logistic模型来描述围岩稳定性影响因素与围岩稳定性之间的经验关系。选取影响围岩分类的5个主要因素,根据分类标准,采用在每级标准中随机内插的方法,得到100个标准样本,用于建立PCA-Logistic模型。分析结果显示,PCA-Logistic模型拟合效果良好,对工程实例的预测结果同投影寻踪模型和分形-插值模型完全一致,表明该模型在围岩稳定性评价中具有可行性和有效性。     

Performance comparison of reduced models for leak detection in water distribution networks

This paper presents a methodology for comparing the performance of model-reduction strategies to be used with a diagnostic methodology for leak detection in water distribution networks. The goal is to find reduction strategies that are suitable for error-domain model falsification, a model based data interpretation methodology. Twelve reduction strategies are derived from five strategy categories. Categories differ according to the manner in which nodes are selected for deletion. A node is selected for deletion according to: (1) the diameter of the pipes; (2) the number of pipes linked to a node; (3) the angle of the pipes in the case of two-pipe nodes; (4) the distribution of the water demand; and, (5) a pair-wise combination of some categories.The methodology is illustrated using part of a real network. Performance is evaluated first by judging the equivalency of the reduced network with the initial network (before the application of any reduction procedure) and secondly, by assessing the compatibility with the diagnostic methodology. The results show that for each reduction strategy the equivalency of networks is verified. Computational time can be reduced to less than 20% of the non-reduced network in the best case. Results of diagnostic performance show that the performance decreases when using reduced networks. The reduction strategy with the best diagnostic performance is that based on the angle of two-pipe nodes, with an angle threshold of 165°. In addition, the sensitivity of the performance of the reduced networks to variation in leak intensity is evaluated. Results show that the reduction strategies where the number of nodes is significantly reduced are the most sensitive.Finally this paper describes a Pareto analysis that is used to select the reduction strategy that is a good compromise between reduction of computational time and performance of the diagnosis. In this context, the extension strategy is the most attractive.     

基于改进FAHP的电力通信网可靠性评估方法研究

论文阐述了可靠性的一般评估方法,在借鉴TMN管理模型的基础上,对电力通信网可靠性进行了分层,构建了可靠性综合评估指标体系.为减少指标体系权重的主观性,提高评估结果的客观性和可信性,提出了一种改进的FAHP综合可靠性评估方法.该方法基于对数最小二乘法(LLSM)进行模糊权重计算,利用限位系数法来实现评估结果的解模糊过程,实例评估验证了该方法的有效性和可行性.最后对电力通信网可靠性的研究方向给出了建议.     

浅析网络异常流量分析检测研究与实现

伴随着互联网技术与网络业务的快速发展,网络规模逐渐扩大,网络运用开始逐步朝多元化、多样化以及复杂化的方向发展.现今,网络流量监测已经逐渐发展为计算机网络运用当中一个必不可少的内容与环节.文章将对网络异常流量加以说明,并对网络异常流量检测技术研究与实现进行分析与研究.     

探讨计算机网络专业学生的实训教学课程设置

计算机网络专业的学生的实训内容通常是与今后的工作相关联的,这种关联的程度越高,说明实训的效果越好,也可以从一个侧面说明教学越成功。所以,实训项目不应该是凭空设想的,也不应该是几年如一日的照搬照抄的,应该是符合市场需求的,与时俱进的。     

浅议网络体系结构与相关技术研究

随着高新科学技术的发展,互联网的规模也不断扩大.人们对互联网需求也越来越多,而现有的网络体系结构开始难以满足人们的需求.本文主要通过讨论现今网络体系结构存在的问题,对相关技术进行研究.     

On input‐to‐state stability‐based design for leader/follower formation control with measurement delays

This paper addresses the design of low‐level controllers for leader–follower formations of nonholonomic vehicles in the presence of bounded measurement delays. The concept of input‐to‐state stability is extended to encompass the effect of bounded delays and restrictions on the input. A method is proposed to integrate a Smith predictor in a backstepping design on the basis of nested saturations and nonlinear small‐gain assignment, which allows for time delays in the feedback loop. Robustness analysis under uncertain bounded time delays is provided, and design tradeoffs resulting from the use of bounded controls are discussed. Illustrative simulations are shown to validate the design and robustness analysis in the context of a simple leader–follower trailing control problem. Copyright © 2012 John Wiley & Sons, Ltd.     

赞比亚Lunzua水电站施工控制网的建立

文章结合工程实例,介绍南半球国家施工控制网的建立、平差与投影变形的解决方法.     

A High-Precision Time Handling Library

An appropriate assessment of end-to-end network performance presumes highly efficient time tracking and measurement with precise time control of the stopping and resuming of program operation. In this paper, a novel approach to solving the problems of highly efficient and precise time measurements on PC-platforms and on ARM-architectures is proposed. A new unified High Performance Timer and a corresponding software library offer a unified interface to the known time counters and automatically identify the fastest and most reliable time source, available in the user space of a computing system. The research is focused on developing an approach of unified time acquisition from the PC hardware and accordingly substituting the common way of getting the time value through Linux system calls. The presented approach provides a much faster means of obtaining the time values with a nanosecond precision than by using conventional means. Moreover, it is capable of handling the sequential time value, precise sleep functions and process resuming. This ability means the reduction of wasting computer resources during the execution of a sleeping process from 100% （busy-wait） to 1-1.5%, whereas the benefits of very accurate process resuming times on long waits are maintained.