检索结果-内蒙古大学图书馆

Authenticating ourselves: Will we ever escape the password?

Network Security 2005年第3期2005卷 8-13页

作者： Furnell, Steven Network Research Group Sch. of Comp. Commun. and Electron. University of Plymouth Plymouth United Kingdom

Some problems involved with passwords and user authentication are discussed. Making poor password choices, which leave them vulnerable to password cracking tools and social engineering, is one common problem. Other problems include, sharing them with friends and colleagues, writing the information down, using the same password for long periods and using the same password on multiple systems. Other options for user authentication, such as biometrics, are also discussed.

关键词： Security of data

来源：评论

学校读者我要写书评

暂无评论

Improving TCP performance in ad hoc networks using signal strength based link management

引用

Ad Hoc Networks 2005年第2期3卷 175-191页

作者： Klemm, Fabius Ye, Zhenqiang Krishnamurthy, Srikanth V. Tripathi, Satish K. Sch. of Comp. and Commun. Sciences Swiss Fed. Institute of Technology 1015 Lausanne Switzerland Department of Electrical Engineering University of California Riverside CA 92521 United States Dept. of Comp. Sci. and Engineering University of California Riverside CA 92521 United States University at Buffalo State University of New York Buffalo NY 14260 United States

Mobility in ad hoc networks causes frequent link failures, which in turn causes packet losses. TCP attributes these packet losses to congestion. This incorrect inference results in frequent TCP re-transmission time-outs and therefore a degradation in TCP performance even at light loads. We propose mechanisms that are based on signal strength measurements to alleviate such packet losses due to mobility. Our key ideas are (a) if the signal strength measurements indicate that a link failure is most likely due to a neighbor moving out of range, in reaction, facilitate the use of temporary higher transmission power to keep the link alive and, (b) if the signal strength measurements indicate that a link is likely to fail, initiate a route re-discovery proactively before the link actually fails. We make changes at the MAC and the routing layers to predict link failures and estimate if a link failure is due to mobility. We also propose a simple mechanism at the MAC layer that can help alleviate false link failures, which occur due to congestion when the IEEE 802.11 MAC protocol is used. We comp.re the above proactive and reactive sch.mes and also demonstrate the benefits of using them together and along with our MAC layer extension. We show that, in high mobility, the goodput of a TCP session can be improved by as much as 75% at light loads (when there is only one TCP session in the network) when our methods are incorporated. When the network is heavily loaded (i.e., there are multiple TCP sessions in the network), the proposed sch.mes can improve the aggregate goodput of the TCP sessions by about 14-30%, on average. © 2004 Elsevier B.V. All rights reserved.

关键词： Packet networks

来源：评论

学校读者我要写书评

暂无评论

Low-loss 2-bit tunable bandpass filters using MEMS DC contact switches

Low-loss 2-bit tunable bandpass filters using MEMS DC contac...

引用

作者： Pothier, Arnaud Orlianges, Jean-Christophe Zheng, Guizhen Champeaux, Corinne Catherinot, Alain Cros, Dominique Blondy, Pierre Papapolymerou, John Res. Inst. Optical/Microwave Commun. 87060 Limoges Cedex France Proc. and Mat. Sciences Department University of Limoges 87060 Limoges Cedex France Sch. of Elec. and Comp. Engineering Georgia Institute of Technology Atlanta GA 30332 United States

This paper presents the development of tunable filters using ohmic contact microelectromechanical system switches. It is shown that this type of switch is very well suited for the fabrication of low-loss high tuning-range microwave filters. Two sets of tunable K u-band microstrip filters and resonators have been fabricated, with measured tuning ranges of 20% and 44%, and unloaded quality factors better than 75 in all cases. The 2-bit 5.7% fractional bandwidth, tunable bandpass filters exhibit insertion losses lower than 3.2 dB in all states.

关键词： Bandpass filters

来源：评论

学校读者我要写书评

暂无评论

Effect of aspect ratio on forward voltage drop in trench insulated gate bipolar transistor

Effect of aspect ratio on forward voltage drop in trench ins...

引用

作者： Moon, Jin-Woo Choi, Yearn-Ik Chung, Sang-Koo Process Development Group Product Technology Team Fairchild Semiconductor 82-3 Dodang-dong Wonmi-gu Bucheon Gyeoonggi-do Korea Republic of Sch. of Elec. and Comp. Engineering College of Information Technology Ajou University San 5 Wonchon Dong Youngtong Gu Su-Won City 443-749 Korea Republic of Division of Computer Electron. and Commun. Engineering Yanbian Univ. Sci. Technol. Yanji C. Jilin Province 133000 China

An analytical model for the carrier density at the accumulation layer of TIGBT (Trench Insulated Gate Transistor) is presented in terms of the aspect ratio with the influence of the depth of the trench gate below the P base taken into account. Based on the model, analytic expressions for the potential drop on the drift region are derived using a linear dependence of the carrier density on the aspect ratio. The analytical results for the forward voltage drop show a good agreement with the numerical simulations using MEDICI. © 2005 Elsevier Ltd. All rights reserved.

关键词： Insulated gate bipolar transistors

来源：评论

学校读者我要写书评

暂无评论

Universal parallel solver for convection-diffusion equations

引用

Parallel Processing Letters 2004年第1期14卷 107-117页

作者： Zhi, Xiaoli Lu, Rong Lu, Xinda Sch. of Comp. Sci. and Engineering Shanghai University 200072 China Shanghai Res. Ctr. Wireless Commun. 200050 China Dept. of Comp. Sci. and Engineering Shanghai Jiaotong University 200030 China

A parallel unconditionally stable solver for three-dimensional convection-diffusion equations is proposed by applying the upwind Crank-Nicolson difference sch.mes combined with alternating bar parallelization. This solver can be applied numerically to any variation of convection-diffusion equations with Dirichlet boundary conditions. Making use of a fractional step iteration technique for linear systems, this approach yields good runtime performance. To validate the accuracy and efficiency of the method, sample experiments are done on a software tool, Codie4D, which was implemented using the MPICH library.

关键词： Linear systems

来源：评论

学校读者我要写书评

暂无评论

Agent-based embedded monitoring system for ubiquitous networks environments

Agent-based embedded monitoring system for ubiquitous networ...

引用

Proceedings of the International Conference on Parallel and Distributed Processing Techniques and Applications, PDPTA'04

作者： Kang, Hyo-Sung Choi, Jong-Mu Kim, Jai-Hoon Ko, Young-Bae Grad. Sch. of Info. and Commun. Ajou University Korea Republic of Sch. of Info. and Comp. Engineering Ajou University Korea Republic of

ISBN: (纸本)1932415262

Contrary to current wireless network systems, ubiquitous network environment has quite dynamic and diversified devices which aim at best meeting the requirements of specific group of users for a specific purpose. In order to obtain the seamless transparency within mobile devices, accurate and efficient monitoring of dynamically changing environments is one of the most important requirements for ubiquitous network environments. In this paper, we describe the novel agent-based embedded monitoring systems for wireless network devices. By utilizing the light-weight mobile agent technology, our monitoring system can be a useful tool for ubiquitous network environments. This agent-based approach, moreover, provides seamless transparency. Our proposed monitoring system can automate the installation and updating process of monitoring code. We also implement our agent-based monitoring system on embedded Linux-based wireless ad hoc network testbed.

关键词： comp.ter networks

来源：评论

学校读者我要写书评

暂无评论

Characterization of digital medical images utilizing support vector machines

引用

BMC Medical Informatics and Decision Making 2004年第1期4卷 1-9页

作者： Maglogiannis, Ilias G. Zafiropoulos, Elias P. University of the Aegean Dept. of Info./Commun. Syst. Eng. Karlovasi Greece Sch. of Elec. and Comp. Engineering Natl. Technical University of Athens Athens Greece

Background: In this paper we discuss an efficient methodology for the image analysis and characterization of digital images containing skin lesions using Support Vector Machines and present the results of a preliminary study. Methods: The methodology is based on the support vector machines algorithm for data classification and it has been applied to the problem of the recognition of malignant melanoma versus dysplastic naevus. Border and colour based features were extracted from digital images of skin lesions acquired under reproducible conditions, using basic image processing techniques. Two alternative classification methods, the statistical discriminant analysis and the application of neural networks were also applied to the same problem and the results are comp.red. Results: The SVM (Support Vector Machines) algorithm performed quite well achieving 94.1% correct classification, which is better than the performance of the other two classification methodologies. The method of discriminant analysis classified correctly 88% of cases (71% of Malignant Melanoma and 100% of Dysplastic Naevi), while the neural networks performed approximately the same. Conclusion: The use of a comp.ter-based system, like the one described in this paper, is intended to avoid human subjectivity and to perform specific tasks according to a number of criteria. However the presence of an expert dermatologist is considered necessary for the overall visual assessment of the skin lesion and the final diagnosis.

关键词： Support Vector Machine Discriminant Analysis Kernel Function Thinness Ratio Support Vector Machine Algorithm

来源：评论

学校读者我要写书评

暂无评论

Intersecting a freeform surface with a ruled or a ringed surface

Intersecting a freeform surface with a ruled or a ringed sur...

引用

Proceedings - Geometric Modeling and Processing 2004

作者： Seong, Joon-Kyung Kim, Ku-Jin Kim, Myung-Soo Elber, Gershon Sch. of Comp. Sci. and Engineering Seoul National University Korea Republic of Grad. Sch. of Info. and Commun. Ajou University Korea Republic of Sch. of Comp. Sci. and Engineering Institute of Computer Technology Seoul National University Korea Republic of Dept. of CS Technion Israel Institute of Technology Haifa 32000 Israel

ISBN: (纸本)0769520782

We present efficient and robust algorithms for intersecting a freeform surface with a ringed surface or a ruled surface. A ringed surface is given as a one-parameter family of circles. By comp.ting the intersection between a freeform surface and each circle in the family, we can solve the intersection problem. We propose two approaches which are closely related to each other. The first approach detects certain critical points;and the intersection curve is constructed by connecting them in a correct topology. The second approach converts the intersection problem to that of finding the zero-set of two polynomial equations in the parameter space. The intersection between a freeform surface and a ruled surface can be comp.ted in a similar way.

关键词： comp.ter graphics

来源：评论

学校读者我要写书评

暂无评论

Subcarrier adaptation for multiuser OFDM systems

Subcarrier adaptation for multiuser OFDM systems

引用

GLOBECOM'04 - IEEE Global Telecommun.cations Conference

作者： Choe, Kwang Don Lim, Yeon Ju Park, Sang Kyu Sch. of Electron. Commun. and Info. Anyang Technical College Anyang Korea Republic of Div. of Elec. and Comp. Engineering Hanyang University Seoul Korea Republic of

Low comp.exity is very important for an adaptive loading algorithm used in OFDM systems in order to adapt the transmit power and the number of bits for each subcarrier within the coherence time of a wireless and mobile channel. In this paper, an adaptive subcarrier allocation algorithm for a multiuser OFDM system is considered. To overcome the weakness of a conventional allocation sch.me, a new adaptive allocation algorithm is proposed to reduce the comp.exity of the allocation algorithm. Consequently, in this paper it is shown that the proposed allocation algorithm has the lower comp.tational comp.exity than the conventional one, while the both algorithms have the almost same BER(Bit Error Rate) performances in a rayleigh fading environment. © 2004 IEEE.

关键词： Orthogonal frequency division multiplexing

来源：评论

学校读者我要写书评

暂无评论

Application of radial basis probability neural network to signal recognition

Application of radial basis probability neural network to si...

引用

WCICA 2004 - Fifth World Congress on Intelligent Control and Automation, Conference Proceedings

作者： Zhang, Gexiang Rong, Haina Hu, Laizhao Jin, Weidong School of Electrical Engineering Southwest Jiaotong University Chengdu Sichuan 610031 China Sch. of Comp./Commun. Engineering Southwest Jiaotong University Chengdu Sichuan 610031 China National EW Laboratory Chengdu Sichuan 610036 China

Radial basis probability neural network (RBPNN) was introduced to recognize radar emitter signals. The structure and training algorithm of RBPNN were firstly discussed. Then, a novel feature extraction approach called resemblance coefficient method and its detailed steps were presented. Finally, based on resemblance coefficient features, RBPNN was used to design classifer to identify 9 typical radar emitter signals. Because RBPNN inherits the advantages of both radial basis function neural network and probability neural network, RBPNN has the good characteristics of simple structure, fast learning speed and strong capabilities of pattern recognition and classification. Experimental results show that high accurate recognition rates are achieved and the introduced approach is effective and practical.

关键词： Intelligent control

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：