基于BP神经网络的心电图三分类     

杜智慧  张瑞民 《丽水学院学报》2006,28(2):14-17

研究了一种基于神经网络的心电图分类方法,该方法利用前向多层神经网络的反向传播算法(Back Propagation),即BP算法,采用MATLAB软件建立用于三分类的BP神经网络,并利用大量的心电图数据训练神经网络,使神经网络对未训练过的心电图有较好的分类能力。实验结果表明,用这种方法用于心电图的三分类取得较好的效果。  相似文献   

Mathematical Analysis of Energy Efficiency in IEEE 802.11 DCF     

高波杨宇航  马惠业 《天津大学学报(英文版)》2005,11(5):332-337

The standardized IEEE ,802. II distributed coordination function （ DCF） provides a contention-based distributed channel access mechanism for mobile stations to share the wireless medium. However, when stations are mobile or portable units, power consumption becomes a primary issue since terminals are usually battery driven. This paper proposes an analytical model that calculates the energy efficiency of both the basic and the RTS/CTS access mechanisms of the IEEE 802. II protocol. The model is validated with simulation results using NS-2 simulation package. The effects of the network size, the average packet length, the initial contention window and maximum backoff stages on the energy efficiency of both access mechanisms are also investigated. Results show that the basic scheme has low energy efficiency at large packet length and large network size, and depends strongly on the number of stations and the backoff procedure parameters. Conversely, the RTS/CTS mechanism provides higher energy efficiency when the network size is large, and is more robust to variations in the backoff procedure parameters.  相似文献   

学习策略在英语教学中的地位和应用     

欧阳敏  刘倩 《昆明师范高等专科学校学报》2003,25(1):78-81

近年来，学习策略已成了一个引人注目的研究领域。根据我们最近对学生的问卷调查，我们发现掌握好适合于自己的学习策略是提高学习效率，发展自主学习能力的保证。本从英语学习策略的基本理论出发，提出了在外语教学中，教师要重视对学生进行认知策略、记忆策略、元认知策略、情感策略和社交策略的培养。使学生用较少的“能源消耗”，来获取较多的知识。  相似文献   

三角债清理的图论模型分析     

陈爱珍 《忻州师范学院学报》2006,22(5):129-131

三角债是我国当前经济领域中存在的一个突出问题。文章建立了三角债的图论模型,并证明了任一债务网络皆可转换为最小债务网络,从而简化了三角债清理工作。  相似文献   

加强信息网络环境下的图书馆建设     

喻绍贤 《哈尔滨学院学报》2002,23(10):135-136

信息网络的迅速发展，对图书馆提出了严峻挑战的同时也带来机遇。图书馆要面对时代变化，不断进行自身建设，才能适应社会发展需要。  相似文献   

EBF网络特征映射和恢复及其在鲁棒话者识别中的应用     

李昕  郑宇  江芳泽 《上海大学学报(英文版)》2002,6(4)

The performance of speaker verification systems is often compromised under real-world environments. For example, variations in handset characteristics could cause severe performance degradation. This paper presents a novel method to overcome this problem by using a non-linear handset mapper. Under this method, a mapper is constructed by training an elliptical basis function network using distorted speech features as inputs and the corresponding clean features as the desired outputs. During feature recuperation, clean features are recovered by feeding the distorted features to the feature mapper. The recovered features are then presented to a speaker model as if they were derived from clean speech. Experimental evaluations based on 258 speakers of the TIMIT and NTIMIT corpuses suggest that the feature mappers improve the verification performance remarkably.  相似文献   

Metaphor,Transferred Epithet与Personification辨析     

于少萍  彭家玉 《十堰职业技术学院学报》2001,14(1):7-8

本文认为隐喻、移位法与拟人法这三个英语辞格是人类思维中三种性质不同的方式的产物，并分析了其表现形式的不同。  相似文献   

Modeling water and carbon fluxes above summer maize field in North China Plain with back-propagation neural networks     

Qin Z  Su GL  Yu Q  Hu BM  Li J 《Journal of Zhejiang University. Science. B》2005,6(5):418-426

INTRODUCTION Dynamics of carbon and water vapor fluxesexchange between the atmosphere and the ecosystembiosphere, depend on complex and non-liner interplayamong physiological, ecological, biochemical andedaphic factors and meteorological conditions (Jarvis,1995; Leuning et al., 1995). There are many studiesquantifying the fluxes across different time and spacescales as well as assessing the environment con-straints on them by some kinds of biophysical orempirical models whose resul…  相似文献   

移动自组网AODV多路径路由研究     

范业仙 《宁德师专学报(自然科学版)》2007,19(2):141-144

AODV协议是唯一通过IETF批准成为RFC文档的移动自组网按需控制路由协议．分析AODV路由协议工作过程及优缺点，并介绍了几种典型的基于AODV的多路径路由改进协议，最后对这些多路径协议进行优缺点分析及性能比较。  相似文献   

Hybrid ants-like search algorithms for P2P media streaming distribution in ad hoc networks     

ZUO Dong-hong DU Xu YANG Zong-kai 《浙江大学学报(A卷英文版)》2007,8(8):1191-1198

Media streaming delivery in wireless ad hoc networks is challenging due to the stringent resource restrictions,po-tential high loss rate and the decentralized architecture. To support long and high-quality streams,one viable approach is that a media stream is partitioned into segments,and then the segments are replicated in a network and served in a peer-to-peer(P2P) fashion. However,the searching strategy for segments is one key problem with the approach. This paper proposes a hybrid ants-like search algorithm(HASA) for P2P media streaming distribution in ad hoc networks. It takes the advantages of random walks and ants-like algorithms for searching in unstructured P2P networks,such as low transmitting latency,less jitter times,and low unnecessary traffic. We quantify the performance of our scheme in terms of response time,jitter times,and network messages for media streaming distribution. Simulation results showed that it can effectively improve the search efficiency for P2P media streaming distribution in ad hoc networks.  相似文献