Algorithms for Delay Performance Inference Based on Network Tomography

网络测量对认识网络行为以便更合理有效管理网络具有重要意义，但网络的分布化、不协作、异质等特点使得网络测量极具挑战性。传统的网络测量方法具有需要网络内部节点的参与协作，或需要在网络中部署测量设备，存储和分析包头信息，存在信息安全、隐私和机密问题，且增加网络负载等局限性。为此，一些研究学者把计算机层析技术原理应用于网络测量领域，从而提出了网络层析技术，它是一个新兴发展的网络测量技术，它是基于端到端的测量结果，利用统计推断技术来估计网络内部链路的性能参数，如链路的时延、丢包率等。因为它克服了传统网络测量方法的局限性，所以网络层析技术已成当前网络测量领域的一个研究热点。 时延层析是网络层析技术的一个...Network measurement is important for us to examine the action of network so that the network can be managed more reasonably and more effectively. However, because of its distributive,no corporative and heterogeneous characteristic, accurate measurement of such a network is very difficult. Traditional measurement methods have some limitations such as with the participation and collaboration of inte...学位：工学博士院系专业：信息科学与技术学院电子工程系_电路与系统学号：2312007015348

An Algorithm of Network Loss Ratio Based on Multicast

网络层析是近年新兴的一个网络研究领域,它利用端到端的性能测试结果推导网络内部性能特征或拓扑结构,克服了传统网络测量技术的一些缺陷。丢包率层析的主要方法是利用最大似然估计(MlE),但是计算复杂度高且计算时间较长;基于伪似然估计(PMlE)方法可以较快估计各链路丢包率,但是在非叶节点链路的误差较大。为了克服以上缺点,本文基于多播网络的端对端测量,结合MlE和PMlE提出一种推算网络内部各链路的丢包率算法。通过仿真证实该算法估测的结果能真实地反应网络内部丢包趋势,在推测精度较好的情况下,计算量减少,计算复杂度降低。Network tomography is an emerging network research area in recent years.They use end-to-end performance measurement result to derive network internal performance distribution or topology,thus it overcomes traditional network measurement's shortcomings.The arithmetic described in this paper is based on multicast network tomography end-to-end measurement,computing the loss rate.Through comparison and simulation,it is obtained that the loss inferences correctly show the network loss trend

Algorithm for Network Delay Estimation Based on End-to-End Data Moment

现有时延层析算法大多考虑离散时延模式,但算法效率比较低。为此,提出一种连续时延估计算法,假定链路时延为某参数的函数分布,根据多播特征并基于端到端数据的矩,利用非线性最小二乘法估计链路时延分布函数的参数,并在每步迭代中用一维牛顿搜索确定最优步长,达到快速收敛。应用MATlAb和nS2仿真软件得到的数据表明,该算法所需的存储量少,算法简单且效率较高。The up-to-date algorithms on delay tomography are based on the discrete delay mode,but it is low efficiency in this mode.This paper proposes a continuous delay mode,whose delay is distributed on a function with some parameters.According to the rule of multicast and based on end-to-end moments,the parameters can be estimated using nonlinear least squares and the best step is chosen by the one-dimension Newton search in iteration.Experimental results on Matlab and NS2 simulation show that the algorithm needs little storage and is simple with high efficiency.国家自然科学基金资助项目(41074077;40774065

A Case Report of a Large Epulis Gravidarum

In this paper a case of epulis gravidarum appeared in a 26-year-old woman, 10 months pregnant, has been presented The tumor, hen\u27s egg-sized, having a tendency to bleed easily, attached with a pedicle to the buccal gingiva of the left molar region of the mandible. The epulis was excised with adjacent decayed teeth at 1 month after parturition. Postoperative course was uneventful and have showed no recurrence 6 months after the operation. It was diagnosed histopathologically as epulis fibrosa teleangiectaticum

Circumstances of Mountain Accidents in Japan : Problems of Senior-aged Persons

Fatal mountain accidents in Japan in the year 1994 was the worst record in years, because a total of 206 persons in 774 incidents lost their lives. Our concern of "Record Number of Accidents" is entirely due to a large increase of accidents that involve senior-aged persons. In comparison with the year 1979, the proportion of senior-aged persons as victims increased from 23% to 67%. This is because a mountaineering boom came with the decrease in labor hours from 1988 and with the increased interest in nature. A number of papers and reports for researching the mountain accidents, however, are very poor except for a lot of mountaineering guide-books and monthly magazines. Moreover, the authors of guide-books who believe in their own evidence have sometimes made comments on the mountain accidents without hard data of accidents. In this study, the data by the police headquarters ,which were collected from all branches in each prefecture in Japan, helped to analyze the circumstances of mountain accidents. Main items used in the police data were cause, activity, terrain, victim identities, and ages. The increment rate of incidents of senior-aged persons was 3.2% each year. So more increase of the senior aged victims persons will be expected in the near future because the baby-boom generation is getting older. The most common causes in mountain accidents were falls and slips for those under the ,age of 55, while the cause for people over 55 was getting lost. The parameters of getting lost will be a useful index to explain the spatial recognition ability in the mountain accidents from childhood to old age. The statistics analyzed for mountain accidents could pointed out the problems involved in considering a group of people over the age of 40 as only one group and will be a indicator how to consider the mountain accidents and aging process of hikers and climbers

頭頸部の細網肉腫 : その放射線治療成績と若干の問題について

Article信州医学雑誌 27(1): 32-36(1979)journal articl