检索结果-南通市图书馆

Terahertz radiation sources based on free electron lasers and their applications

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(information Sciences) 2012年第1期55卷 1-15页

作者： TAN Ping1,HUANG Jiang2,LIU KaiFeng2,XIONG YongQian2&FAN MingWu1,2 1department of Electronic and information engineering,Huazhong university of Science and technology,Wuhan 430074,china 2College of Electrical and Electronic engineering,State Key Laboratory of Advanced Electromagnetic engineering and technology,Huazhong university of Science and technology,Wuhan 430074,china 1. department of Electronic and information engineering Huazhong University of Science and Technology Wuhan 430074 China2. College of Electrical and Electronic Engineering State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China

The tunability,high power and flexible picoseconds-pulse time structure of terahertz(THz)radiation make the THz free-electron laser(FEL)a very attractive THz source of coherent *** paper focuses on the development and perspectives of THz radiation sources based on the *** principles of the low gain THz FEL oscillator,the SASE THz FEL amplifier and the supperradiant THz FEL are reviewed briefly,and the key technologies of THz FEL,such as injector,accelerator,undulator and optical cavity,are discussed,*** current status of and future prospects for THz radiation sources based on the FEL are emphasized in this *** research and development have shown bright future in free-electron laser(FEL)THz radiation *** potential applications can be carried out in the field of imaging,material research,biology medicine,communication,diagnostics and many others.

关键词： terahertz source terahertz applications free electron laser

ESKD-A New Structure of Expert System Based on Knowledge Discovery

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 63-71页

作者： Bingru Yang Fasheng liu Jiangtao Shen information engineering School, university of Science and technology Beijing, Beijing, 100083, china information engineering School University of Science and Technology Beijing Beijing 100083 China

A new structure of ESKD (expert system based on knowledge discovery system KD (D&K)) is first presented on the basis of KD (D&K)-a synthesized knowledge discovery system based on double-base (database and knowledge base) cooperating mechanism. With all new features, ESKD may form a new research direction and provide a great probability for solving the wealth of knowledge in the knowledge base. The general structural frame of ESKD and some sub-systems among ESKD have been described, and the dynamic knowledge base based on double-base cooperating mechanism has been emphased on. According to the result of demonstrative experi- ment, the structure of ESKD is effective and feasible.

关键词： knowledge discovery expert system dynamic knowledge base, double-base cooperating mechanism

Corrosion science general-purpose data model and interface (Ⅱ): OOD design and corrosion data markup language (CDML)

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2008年第11期51卷 1850-1857页

作者： TANG ZiLong School of Materials Science and engineering, tianjin university, tianjin 300072, china School of Materials Science and engineering Tianjin University Tianjin China

With object oriented design/analysis, a general purpose corrosion data model (GPCDM) and a corrosion data markup language (CDML) are created to meet the increasing demand of multi-source corrosion data integration and sharing. "Cor- rosion data island" is proposed to model the corrosion data of comprehensiveness and self-contained. The island of tree-liked structure contains six first-level child nodes to characterize every important aspect of the corrosion data. Each first-level node holds more child nodes recursively as data containers. The design of data structure inside the island is intended to decrease the learning curve and break the acceptance barrier of GPCDM and CDML. A detailed explanation about the role and meaning of the first-level nodes are presented with examples chosen carefully in order to review the design goals and requirements proposed in the previous paper. Then, CDML tag structure and CDML application programming interface (API) are introduced in logic order. At the end, the roles of GPCDM, CDML and its API in the multi-source corrosion data integration and information sharing are highlighted and projected.

关键词： corrosion data model corrosion data markup language (CDML) application programming interface (API) information sharing

Series-based approximate approach of optimal tracking control for nonlinear systems with time-delay

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2008年第12期18卷 1571-1576页

作者： Gongyou Tang~a Mingqu Fan~(a,b) a College of information Science and engineering,Ocean university of china,Qingdao 266100,china b College of information and engineering,Shandong university of Science and technology,Jinan 250031,china [a]College of information Science and engineering Ocean University of China Qingdao 266100 China [b]College of information and engineering Shandong University of Science and Technology Jinan 250031 China

The optimal output tracking control (OTC) problem for nonlinear systems with time-delay is *** a series-based approx- imate approach,the original OTC problem is transformed into iteration solving linear two-point boundary value problems without time- *** OTC law obtained consists of analytical linear feedback and feedforward terms and a nonlinear compensation term with an infinite series of the adjoint *** truncating a finite sum of the adjoint vector series,an approximate optimal tracking control law is obtained.A reduced-order reference input observer is constructed to make the feedforward term physically *** exam- ples are used to test the validity of the series-based approximate approach.

关键词： Nonlinear systems Time-delay Tracking control Optimal control Observer

Coupling analysis of unsteady seepage and stress fields in discrete fractures network of rock mass in dam foundation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2011年第S1期54卷 133-139页

作者： CHAI JunRui 1,2 & XU WeiSheng 2 1 College of Hydraulic and Environmental engineering,china Three Gorges university,Yichang 443002,china 2 College of Hydropower engineering,Xi’an university of technology,Xi’an 710048,china 1. College of Hydraulic and Environmental engineering China Three Gorges University Yichang 443002 China2. College of Hydropower Engineering Xi’an University of Technology Xi’an 710048 China

The drag force of water flow through single fracture and the coupling characteristics of seepage and stress in single fracture surface are analyzed,and a three dimensional model of coupled unsteady seepage and stress fields is *** model is used to the analysis of foundation rock mass of a high *** the coupling effects are considered,the changes of boundary heads have less influence on the inner head of rock mass,and the strong permeability of main fractures *** the coupling effects are not considered,the fractures distribution affects the inner head more *** the upstream water head declines,the inner head of dam foundation slightly declines and the hydraulic gradient distribution becomes smoother.A bigger upstream water level declining velocity has a stronger lag effect,meanwhile the values of stress components change more *** the upstream water level declining velocity directly affects the stability of rock mass in dam foundation and we should take into account the above factors to make sure the safety of the dam during reservoir level fluctuation period.

关键词： hydraulic engineering unsteady seepage stress coupling fractures network rock mass

Performance analysis of network coding for multicast relay system over Nakagami-m fading channels

在线全文

学校读者我要写书评

暂无评论

Science china(information Sciences) 2011年第11期54卷 2338-2348页

作者： ZHAO Rui 1,YANG LvXi 2 & HUANG YongMing 2 1 School of information Science and engineering,Huaqiao university,Xiamen 361021,china 2 School of information Science and engineering,Southeast university,Nanjing 210096,china 1. School of information Science and engineering Huaqiao University Xiamen 361021 China2. School of Information Science and Engineering Southeast University Nanjing 210096 China

The outage probability performance of network coding for multicast relay system is analyzed in Nakagami-m fading *** transmission strategies,i.e.,complex field network coding (CFNC) and amplify-and-forward network coding (AFNC),are applied in the system,and the approximate expressions of outage probability are derived at high SNR and the conclusion is reached that the system diversity gains of two transmission strategies are both 2m,as is verified by numerical *** results also show that CFNC can outperform both AFNC and direct transmission without relay in the performances of system outage probability,sum rate and symbol error ratio.

关键词： multicast relay system network coding outage probability diversity gain

Corrosion science general-purpose data model and interface (Ⅲ):Data integration and management environment

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2008年第12期51卷 2089-2094页

作者： TANG ZiLong School of Materials Science and engineering,tianjin university,tianjin 300072,china School of Materials Science and engineering Tianjin University Tianjin China

A brand new Corrosion Data Integration and Management Environment(CDIME) is developed in Java programming language based on general-purpose corrosion data model(GPCDM) and corrosion data markup language(CDML) proposed in the previous *** general,the functionalities and features of CDIME meet most of design requirements including composition,inheritance,self-contained,relatively independence and so *** insight tutorial is introduced on the life circle of corrosion data islands from its creation,maintenance,and application like *** template feature makes the building of comprehensive data island as simple as a few mouse ***-only publishing of data as e-Book and PDF hold their own *** document can be imported and exported freely on any running *** achieving feature is addressed in detail because it is critical to data sharing and integration in *** the end,a real example is presented to help the understanding of data islands assembling and the advanced features offered by CDIME.

关键词： corrosion software data model information integration

Dynamics of the generalized 3x + 1 function determined by its fractal images

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2008年第2期18卷 217-223页

作者： Xingyuan Wang ,Xuejing Yu School of Electronic & information engineering,Dalian university of technology,Dalian 116024,china School of Electronic & information engineering Dalian University of Technology Dalian 116024 China

Two different complex maps were obtained by generalizing 3x + 1 function to the complex plane,and fractal images for these two complex maps were constructed by using escape time,stopping time and total stopping time arithmetic. The dynamics of the generalized 3x + 1 function based on the structural characteristics of the fractal images was studied. We found that: (1) the size and structure of the stable regions,stopping regions,total stopping regions,and divergent regions for the three types of fractal images depend on convergence rate of the map on the x and y axes. (2) The black stable regions constructed,respectively,by escape time and total stopping time are almost overlapped,demonstrating that 3x + 1 function converged steadily. (3) All of the three fractal images are symmetric to the real axis. The structures on the neighborhood of positive integer number are symmetric to a perpendicular line,which is corresponding to the point or its nearby points on the x axis. And the structures have complicated fractal structure characteristics. These findings indicate that the generalized 3x + 1 function on integer number and its neighborhood contains plentiful information in the complex plane.

关键词： Generalized 3x + 1 function Fractal images Dynamics

Lattice dynamical simulation of methane hydrate

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2010年第1期19卷 43-46页

作者： Lin Wang, Shunle Dong Physics department, College of information Science and engineering, Ocean university of china, Qingdao 266100, Shandong, china [a] Physics department College of Information Science and Engineering Ocean University of China Qingdao 266100 Shandong China

INS （Inelastic Neutron Scattering） spectrum of methane hydrate was measured on MARI （a direct-geometry chopper spectrometer） at Ruther-ford Appleton Laboratory, UK. Compared with ice Ih, it is found that the whole spectrum of methane hydrate moves toward high-energy by about 1.5 meV. Using lattice dynamical （LD） technique, computer simulations of methane hydrate were carried out. In the simulations, four potential models （BE TIP3P, TIP4P, MCY） were employed to calculate the phonon density of states （PDOS）. Comparing the calculated PDOS spectrum with the experimental spectrum, it is found that BF, TIP4P, and TIP3P potential lattices give out well-separated translational and librational bands while MCY potential lattice is unstable to do so and this model is not suitable to describe hydrate system.

关键词： methane hydrate inelastic neutron scattering lattice dynamical simulation