共查询到19条相似文献，搜索用时 250 毫秒
1.
海量存储系统中高扩展性元数据分布算法的研究 总被引：2，自引：2，他引：0
Distribution of metadata in a metadata server cluster is important in mass storage system. A good distribution algorithm has a significant influence on the system performance, availability and scalability. Subtree partition and hash are two traditional metadata distribution algorithms used in distributed file systems. They both have a defect in system scalability. This paper proposes a new directory hash （DH） algorithm. By treating directory as the key value of hash function, implementing concentrated storage of metadata, pipelining operations and prefetching technology, DH algorithm can enhance the system scalability on the premise without sacrificing system performance. 相似文献
2.
INTRODUCTION Research interest in immune system has in-creased over the past few years, and because of its special information processing capabilities, it has been applied to solve many problems (de Castro and Von Zuben, 1999; Hunt and Cooke, 1996). Among these research areas, network security is one of the hot spots and has been considered as analogous to im-munity in natural systems. Researchers at the Uni-versity of New Mexico did a lot of research in this area (Forrest et al., 199… 相似文献
3.
The batch extractive distillation (BED) process has the advantages of both batch and extractive distillation. It is one of the most promising means for the separation of azeotropic and close-boiling point systems. However, so far this process has not been applied in industry due to its over-complexity. A new shortcut model was proposed to simulate the operation of the batch extractive distillation operations. This algorithm is based on the assumption that the batch extractive distillation column can be considered as a continuous extractive distillation column with changing feed at any time. Namely, the whole batch process is simulated as a succession of a finite number of steady states of short duration, in which holdup is considered as constant mole. For each period of time the batch extractive distillation process is solved through the algorithm for continuous extractive distillation. Finally, the practical implementation of the shortcut model is discussed and data from the laboratory and literature are presented. It is found that this model has better adaptability, more satisfactory accuracy and less calculative load than previous rigorous model. Hence the algorithm for simulating BED is verified. 相似文献
4.
Li Y Luo ZY Yu CJ Luo D Xu ZA Cen KF 《Journal of Zhejiang University. Science. B》2005,6(11):1124-1129
INTRODUCTION The solid oxide fuel cell (SOFC) has attracted much attention as a promising source of electrical power generation because of its high efficiency in converting chemical energy to electrical power. De- velopment of SOFC with operating temperature of less than 800 °C has been extensively studied. SOFC has the potential to have the cost of its materials, cell fabrication, and corrosion of its stack components dramatically reduced. Gadolinia-doped ceria with the chemical fo… 相似文献
5.
In order to compensate for the limitation of conventional XY table used in semiconductor integrated circuits(IC) packaging and improve its speed and accuracy, a voice coil actuator (VCA) direct-drive high-speed and precision positioning XY table used in wire bonder was proposed. Also, a novel flexible decoupling mechanism was used in the positioning table, and the small moving mass enabled the positioning table to move at high speed and precision. XY table deformation interference caused by assembly error and instant interference generated by dynamic load moving with high speed and acceleration can be eliminated through the flexible decoupling mechanism. Considering the positioning table as lumped mass spring system,the dynamic equations of the mechanical system and the VCA were built according to the Newton mechanics principle and electromagnetic theory. Then the electromechanical coupling control model of the system was created through Laplace transform. Based on displacement PID controller, the loop-locked controlling algorithm of the positioning system was investigated. The dynamic control algorithm effectively improved the system dynamic performance. The precision test of the prototype machine was carried out, and the results validated the correctness of the model and the theory. Compared with traditional XY table, the table has higher speed, acceleration and positioning accuracy. 相似文献
6.
INTRODUCTION An Artificial Neural Network (ANN) is an in-formation-processing paradigm that is inspired by the way biological nervous systems, such as the brain, process information. It is composed of a large number of highly interconnected processing elements (neu-rons) working in unison to solve specific problems. In recent years, neural network has been widely applied in the field of engineering construction as a large dimensional nonlinear dynamic system, because of its support for … 相似文献
7.
Chen Weifeng Li Zhiwei Dong Xingxing Wang Xiaohong 《Journal of Zhejiang University. Science. B》2021,22(4):305-309
正Staphylococcal enterotoxin A (SEA) synthesized by Staphylococcus aureus is a foodborne and heatstable toxin, which is a great threat to human health (Pexara et al., 2010). Highly sensitive antibodies are a key factor in the immunological detection of SEA,which is one of the most effective ways to detect SEA because of its accuracy, agility, and efficiency (Nouri et al., 2018). 相似文献
8.
Evaluation of packet loss impairment on streaming video 总被引：1，自引：0，他引：1
《浙江大学学报(A卷英文版)》2006,(Z1)
Video compression technologies are essential in video streaming application because they could save a great amount of network resources. However compressed videos are also extremely sensitive to packet loss which is inevitable in today's best effort IP network. Therefore we think accurate evaluation of packet loss impairment on compressed video is very important. In this work, we develop an analytic model to describe these impairments without the reference of the original video (NR) and propose an impairment metric based on the model, which takes into account both impairment length and impairment strength. To evaluate an impaired frame or video, we design a detection and evaluation algorithm (DE algorithm) to compute the above metric value. The DE algorithm has low computational complexity and is currently being implemented in the real-time monitoring module of our HDTV over IP system. The impairment metric and DE algorithm could also be used in adaptive system or be used to compare different error concealment strategies. 相似文献
9.
Accuracy and fastness of iris localization are very important in automatic iris recognition. A new fast iris localization algorithm based on improved generalized symmetry transform (GST) was proposed by utilizing iris symmetry. GST was improved in three aspects: 1 ) A new distance weight function is defined. The new weight function, which is effective in iris localization, utilized the characteristic of irises that the iris is a circular object and it has one inner boundary and one outer boundary. 2) Each calculation of the symmetry measurement of a pair of symmetry points was performed by taking one point of a pair as the starting point of the transformation. This is the most important reason for fast iris localization, due to which, repetitious computation was largely excluded. 3) A new phase weight function was proposed to adjust GST to locate circle target much better because the inner part of iris is darker than the outer part. The edge map of iris image was acquired and GST was only implemented on the edge point, which decreased computation without loss of accuracy. The modification of distance weight function and phase weight function leads to the accuracy of localization, and other ideass peed up the localization. Experiments show that the average speed of new algorithm is about 7.0-8.5 times as high as traditional ones including integro-differential operator and Hough transform method. 相似文献
10.
While the enterprise resource planning (ERP) systems become more and more complex, the traditional tools such as DCOM, CORBA or EJB encounter more difficulties than before especially when heterogenous and distributed environment and multiple companies are involved. The newly bern international specification SOAP brings a new solution to ERP because of its simplicity and high extensibility. This paper analyses the techniques to extend basic SOAP to implement ERP system. The techniques, including data envelope, dynamically and loosely coupled remote process calling (RPC), support to the multiple communication protocol, and security and performance improvement, greatly enhance the ability of basic SOAP and make it capable to accomplish the integration task in large scale ERP systems. All the techniques we discusse here are successfully utilized in the ERP system in the Three Gorge Cascade Dispatch Center of China Three Gorge Project Corporation. 相似文献
11.
P2P与网格都是新型的分布式计算模型,在分析现有网格动态资源发现机制的基础上,将P2P的相关技术引入其中,提出了一种基于DHT的网格动态资源查找算法.该算法结合DHT技术和泛洪式查找技术,在实际的分布式网络之上建立一层结构化的Overlay层.实验结果表明,当用户需要在系统中获取信息时,通过该查找算法,查询只在一些特定的结点上进行,这样就避免了泛洪式查找的盲目性,因此大大提高了信息搜索的效率. 相似文献
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为解决传统协同过滤推荐算法数据稀疏、可扩展性差等问题,采用改进预测评分矩阵的协同过滤算法。首先使用基于线性回归分析的加权Slope One算法,在传统Slope One算法中加入可信度,提高共同评分基数;然后采用网上标准数据集movielens作为测试数据,结合协同过滤算法进行top-N推荐。实验结果表明,使用改进预测评分矩阵的协同过滤算法的MEA较小,在近邻数大于25时达到0.74,表明该算法改善了传统协同过滤算法数据稀疏、扩展性差问题,降低了推荐误差,提高了推荐系统准确度。 相似文献
13.
矿井瓦斯涌出量的遗传神经网络预测研究 总被引：1，自引：0，他引：1
矿井瓦斯涌出系统是非线性变化的复杂系统,传统的瓦斯涌出量预测方法存在一定的局限性。根据改进遗传算法（IGA）和BP算法的特点,将两者结合起来,利用改进遗传算法优化BP网络权重和阈值,形成IGA-BP混合算法,用于对矿井瓦斯涌出量进行科学预测。检验结果表明,基于IGA-BP混合算法的遗传神经网络模型可靠,预测精度高,效果良好。 相似文献
14.
将数据挖掘技术应用到入侵检测中，来自动生成入侵检测规则，实现入侵检测系统的智能化，并实现了一个智能化网络入侵检测系统的模型，阐述了该系统模型的结构及主要功能。该模型为开放的系统模型，具有很好的可伸缩性，可大大减少使用入侵检测系统的代价，有效解决入侵检测系统的环境适应性问题。 相似文献
15.
针对现有网络安全技术不能准确地对网络未来安全态势进行预测的问题,提出一种基于回声状态网络(ESN)进行态势预测的方法。对数据量庞大的安全态势值,利用回声状态网络可有效处理非线性系统辨识以及混沌时间序列预测问题。实验表明,由于训练简单,可根据不同网络环境自动优化网络参数,且算法本身在混沌时间序列预测方面的先天优势,使得 ESN 算法比传统神经网络方法在网络态势预测准确率方面有明显改善。 相似文献
16.
为了提高电力系统中故障预测效率及便捷性,提出一种基于FP-Growth算法的电力系统故障预测方法,无需先验知识及人工标注,便可从海量历史日志数据中快速提取出故障信息模式,并基于实时日志数据对未来可能发送的系统故障进行预测。该方法首先根据电力系统不同类型的日志特征对原始数据进行预处理,然后基于FP-Growth算法挖掘日志中与故障事件相关的关联规则,并使用关联规则进行故障匹配,从而达到预测效果。算法经过真实电力系统日志数据集测试,结果表明该故障预测方法平均准确率为89.5%,平均召回率为79.8%,且执行效率较高,节省了业务人员50%以上的时间。 相似文献
17.
ZHANG Ri-dong WANG Shu-qing 《浙江大学学报(A卷英文版)》2006,7(12):1984-1988
INTRODUCTION Bilinear systems are a kind of important nonlinear systems with relatively simple structure, and many industrial processes can be described as a bilinear system. Thus research on the control of this kind of systems is very important. On the other hand, model predictive control (MPC) (Clarke et al., 1987) has been widely used in industrial applications and many predictive control methods focusing on bilinear systems are emerging (Bloemen et al., 2001; Fontes et al., 2004; He… 相似文献
18.
邱涛 《襄樊职业技术学院学报》2013,12(4):8-11
传统的人工报名方式已经不足以满足现今的需求,在线报名系统凭借其高效性和准确性倍受青睐,并广泛应用于许多领域.基于J2EE平台,采用Mysql数据库和Tomcat服务器设计并实现了一个报名系统.系统主要服务于学生在线报名及学生信息管理,已通过测试并上线使用,为新疆大学各类考试报名提供便利. 相似文献
19.
王娟 《Journal of Zhangzhou Technical Institute》2011,13(3):6-10,15
近年来,随着信息技术的巨大发展和Internet的广泛应用,电子商务以其低成本、高效率的特点,逐渐取代传统的商务方式,成为新兴的商务模式和理念,走进人们的生活。由于电子商务基于开放的Internet,不可避免地会受到各种各样的攻击和安全威胁,严重限制了电子商务的发展。基于支付系统的总体设计,重点阐述了其中关键功能模块的实现,包括支付网关模块、安全模块、证书认证中心模块。实际测试结果表明,安全电子支付系统除具备应有的基本功能外,在安全性方面得到了很大的提高,较好地保证了电子支付的安全性和扩展性。 相似文献