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转辙机动作杆中光纤应力传感器的研究

铁道学报 2004年第6期26卷 120-122页

作者：孙强周虚北京交通大学电子信息工程学院北京100044 北京邮电大学电信工程学院北京100876

研究了非对称刻蚀光纤应力传感器的基本原理,将其应用在转辙机中,为转辙机动作杆应力的检测提供了一种新的测试方法。

关键词：光纤传感器转辙机动作杆应力

Strain distribution and electronic structures of the InAs/GaAs quantum ring molecule in an applied electric field

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1594-1599页

作者： JIA BoYong,YU ZhongYuan,LIU YuMin,YAO WenJie,YE Han & FENG Hao Key Laboratory of information Photonics and Optical communications(beijing university of posts and telecommunications),Ministry of Education,beijing 100876,china Ministry of Education Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications) Beijing China

The strain distribution and electronic structures of the InAs/GaAs quantum ring molecule are calculated via the finite element *** our model,three identical InAs quantum rings are aligned vertically and embedded in the cubic GaAs *** the band edge modification induced by the strain,the electronic ground state and the dependence of ground state energy on geometric parameters of the quantum ring molecule are *** change of localization of the wavefunction resulting from the applied electric field along the growth direction is *** ground state energy decreases as the electric field intensity increases in a parabolic-like *** electric field changes the monotonic dependence of the energy level on the inter-ring distance into a non-monotonic ***,the electric field has no effect on the relationships between the energy level and other geometric parameters such as the inner radius and outer radius.

关键词： strain distribution electronic structure quantum ring molecule applied electric field

Key MAC Layer Technologies of Cognitive Radio Network

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ZTE communications 2009年第2期7卷 21-26页

作者： Zeng Zhimin, Guo Caili (school of information and communication engineering , beijing university of posts and telecommunications , beijing 100876 , P . R . china )

As a smart spectrum sharing technology, Cognitive Radio (CR) is becoming a hot topic in the field of wireless telecommunications. Besides providing traditional services, the cognitive radio network Media Access Control (MAC) layer is required to perform an entirely new set of functions for effective reusing spectrum opportunity, without causing any harmful interference to incumbents. Spectrum sensing management selects and optimizes sensing strategies and parameters by the selection of sensing mode, sensing period, sensing time, sensing channel, and sensing quiet period. Access control avoids collision with primary users mainly by cooperation access and transparent access. Dynamic spectrum allocation optimizes the allocation of uncertain spectrum for binary interference model and accumulative interference model. Security mechanism adds authentication and encryption mechanisms to MAC frame to defense MAC layer security attacks. Cross-layer design combines MAC layer information with physical layer or higher layers information, such as network layer, transmission layer, to achieve global optimization.

关键词： MAC Key MAC Layer Technologies of Cognitive Radio Network Radio

Key Distribution Protocols for Mobile communication Systems

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The Journal of china Universities of posts and telecommunications 1998年第2期5卷 6-9页

作者： Zhan Banghua and Hu Zhengming (Department of information engineering beijing university of posts and telecommunications, beijing, 100876, P. R. china)

In this paper we propose a new key distribution protocol for mobile communication *** protocol KDP4, like KDP3 in [3], is still secure against Simmons' replay attack and the new attack in [3] without using timestamp... 详细信息

关键词： key distribution protocols mobile communication systems cryptology

Digital Content and Its Security

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ZTE communications 2007年第4期5卷 10-13页

作者： Guo Jun(school of information engineering,beijing university of posts and telecommunications,beijing,100876,china)

The digital content industry is becoming a new impetus for the development of the information industry as the infrastructure construction,including the optical fiber backbone transmission network and the wireless mobile access network,are being *** analysis and technical research of the digital content become more and more important in this *** content security technology is one of the three supporting technologies in the digital content *** key points to guarantee digital content security include the solutions for the following problems:sale of pirated digital content,damage and pollution of illegal and harmful content to the social environment,and the means for consumers’ security and reasonable *** issues involve a lot of challenging scientific and technical problems such as highly efficient multimedia encryption and hiding algorithms,multimedia content recognition and filtering algorithms on network,and heterogeneous network oriented micropayment protocols.

关键词： Digital Content and Its Security

A novel adaptive spectrum forming filter:Application in cognitive ultra-wideband

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Science china(information Sciences) 2010年第12期53卷 2584-2599页

作者： LI Bin ,ZHOU Zheng & ZOU WeiXia Key Lab of Universal Wireless communications,MOE.Wireless Network Lab,beijing university of posts and telecommunications,beijing 100876,china Key Lab of Universal Wireless communications MOE. Wireless Network Lab Beijing University of Posts and Telecommunications Beijing China

Ultra wideband impulse radio(UWB-IR) has important applications in high data rate communications,high precision positioning and penetrating target *** with cognitive radio(CR),UWB can also greatly alleviate the current spectrum ***,the existing UWB waveforms are faced with two *** spectrum utilization of UWB signal is rather low,which reduces the communication ***,it appears difficult for UWB-IR to avoid spectrum collision with other incumbent *** UWB will inevitably interfere other legal wireless *** by these considerations,we model the UWB waveform design into an interpolation *** on radial basis function neural network,a novel UWB pulse is presented in this *** UWB pulse is then realized though reasonable simplification on the already proposed theoretical *** designed UWB pulses can adaptively track the external spectral environment where UWB devices work and reconfigure its emission spectrum according to the state of primer users without any modification on *** frequency utilization is maximized when there is no active primary *** adequate spectrum avoidance has also been achieved without much spectrum utilization degradation within the non-primary *** and analysis show that our UWB-IR pulse is much superior to the other existing UWB signals in the frequency utilization,spectrum avoidance and in the transmission performance.

关键词： UWB-IR cognitive radio pulse design RBF network spectrum efficiency spectrum avoidance

Calculation of valence band structures of InAs/GaAs quantum ring and quantum dot:using numerical Fourier transform method

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The Journal of china Universities of posts and telecommunications 2010年第1期17卷 106-110页

作者： JIA Bo-yong,YU Zhong-yuan,LIU Yu-min,TIAN Hong-da Key Laboratory of information Photonics and Optical communications,Ministry of Education,beijing university of posts and telecommunications,beijing 100876,china Key Laboratory of information Photonics and Optical communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

This article puts forward a new method in calculating the band structures of low-dimensional semiconductor structures. In this study, the valence band structures of InAs/GaAs quantum ring and lens-shaped quantum dot are calculated with four-band model, in the framework of effective-mass envelope function theory. To determine the Hamiltonian matrix elements, this article develops the numerical Fourier transform method instead of the widely used analytical integral method. The valence band mixing is considered. The hole energy levels change dramatically with the geometrical parameters of the quantum ring and quantum dot. It is demonstrated that numerical Fourier transform method can be adopted in low-dimensional structures with any shape. The results of Fourier transform method are consistent with the ones of analytical integral in literature; and they are helpful for studying and fabricating optoelectronic devices.

关键词： valence band structures quantum ring quantum dot numerical Fourier transform

Research on Three Dimensional Computer Assistance Assembly Process Design System

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武汉理工大学学报 2006年第S3期28卷 1088-1092页

作者： HOU Wenjun YAN Yaoqi DUAN Wenjia SUN Hanxu Automation school,beijing university of posts & telecommunications,beijing 100876,china, Automation school Beijing University of Posts & TelecommunicationsBeijing 100876China

The computer aided process planning will certainly play a significant role in the success of enterprise information- ization.3-dimensional design will promote Tri-dimensional process *** article analysis nowadays situation and prob- lems of assembly process planning,gives a 3-dimensional computer aided process planning system(3D-VAPP),and researches on the product information extraction,assembly sequence and path planning in visual interactive assembly process design,dynamic emulation of assembly and process verification,assembly animation outputs and automatic exploding view generation,interactive craft filling and craft knowledge management,*** also gives a multi-layer collision detect and multi-perspective automatic camera switching *** were done to ualidate the feasibility of such technology and algorithm,which established the foundation of tri-dimensional computer aided process planning.

关键词： assembly craft information extraction collision detect craft plan components position and posture

Spectral integration and perception of Chinese back vowel /γ/

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Science china(information Sciences) 2010年第11期53卷 2300-2309页

作者： YU ShuiYuan1, CHEN YuDong2 & WU JieRu3 1school of Computer, communication university of china, beijing 100024, china 2International College for Chinese Language Studies, communication university of china, beijing 100024, china 3school of Presentation Art, communication university of china, beijing 100024, china school of Computer Communication University of China Beijing China International College for Chinese Language Studies Communication University of China Beijing China school of Presentation Art Communication University of China Beijing China

The first two formants of the back vowels of many languages, such as English, are often close in frequency within the critical 3.5-Bark distance and are phonetically equivalent to a single intermediate formant. This phenomenon is called spectral integration. The integrated spectral peak is related more directly to phonetic quality than to acoustic formants and is therefore an important cue for determining the phonetic quality of vowels. The Chinese vowel /γ/ is a back vowel, but its first two formants are commonly separated by more than the critical distance. What are the perceptual cues for this vowelDoes the spectral integration phenomenon influence its perceptionThis paper describes a series of identification experiments and rating experiments on the influences of the distance, spectral shape, and relative amplitude of the first two formants on the phonetic quality of /γ/. The results show that all stimuli with a two-peaked spectral shape are perceived as /γ/ whenever the first two formants are separated by the critical Bark distance or beyond. When the two formants are separated by roughly the critical distance, only those stimuli with sharp formants are perceived as /γ/, while stimuli with trapezoidal or single-peaked spectral shapes are not perceived as /γ/. Specifically, when the second formant is 10 dB higher than the first, the spectral integration phenomenon influences formant perception, and the stimulus is not perceived as /γ/; on the contrary, when the second formant is 0-20 dB lower than the first, the stimulus is perceived as /γ/, and spectral integration does not occur. That is to say, spectral integration occurs asymmetrically about the relative amplitudes of the first two formants. In a word, the Chinese vowel /γ/ is a back vowel, but spectral integration does not occur in the perception of its first two formants. Two individual formants are necessary for the phonetic color of the Chinese vowel /γ/. This vowel is different from the back vowels of w

关键词： spectral integration Chinese back vowel /γ/ back vowel critical distance