检索结果-南通市图书馆

Research and application of stochastic resonance in quad-stable potential system

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第7期31卷 169-181页

作者： Li-Fang He Qiu-Ling Liu Tian-Qi Zhang school of Communication and information Engineering Chongqing University of Posts and Telecommunications(CQUPT)Chongqing 400065China

To solve the problem of low weak signal enhancement performance in the quad-stable system,a new quad-stable potential stochastic resonance(QSR)is ***,under the condition of adiabatic approximation theory,the stationary probability distribution(SPD),the mean first passage time(MFPT),the work(W),and the power spectrum amplification factor(SAF)are derived,and the impacts of system parameters on them are also extensively ***,numerical simulations are performed to compare QSR with the classical Tri-stable stochastic resonance(CTSR)by using the genetic algorithm(GA)and the fourth-order Runge–Kutta *** shows that the signal-to-noise ratio(SNR)and mean signal-to-noise increase(MSNRI)of QSR are higher than CTSR,which indicates that QSR has superior noise immunity than ***,the two systems are applied in the detection of real bearing *** experimental results show that QSR is superior to CTSR,which provides a better theoretical significance and reference value for practical engineering application.

关键词： bearing fault detection QSR weak signal detection SAF W

An Enhanced LDPC Coded Partial Incremental Redundancy HARQ Scheme

在线全文

学校读者我要写书评

暂无评论

Journal of Beijing Institute of Technology 2008年第1期17卷 71-75页

作者：贾民丽何遵文匡镜明 school of information Science and Technology Beijing Institute of Technology

An enhanced scheme is proposed for high code rate low density parity check （LDPC） coded partial incremental redundancy （PIR） hybrid automatic repeat request （HARQ）. It employs the unequal error protection （UEP） technique for incremental redundancy bits and uses the constellation rearrangement （CoRe） technique for information bits in retransmissions so as to reduce the reliability variances of all encoded bits after soft combining. Simulation results show that the proposed scheme applies to both regular LDPC and irregular LDPC cases and can efficiently improve frame error rate （FER） performance and throughput performance.

关键词： partial incremental redundancy (PIR) low density parity check (LDPC) code unequal error protection (UEP) constellation rearrangement (CoRe)

Texture image classification with discriminative neural networks

在线全文

学校读者我要写书评

暂无评论

Computational Visual Media 2016年第4期2卷 367-377页

作者： Yang Song Qing Li Dagan Feng Ju Jia Zou Weidong Cai school of information Technologies the University of Sydney school of Computing Engineering and MathematicsWestern Sydney University

Texture provides an important cue for many computer vision applications, and texture image classification has been an active research area over the past years. Recently, deep learning techniques using convolutional neural networks(CNN) have emerged as the state-of-the-art: CNN-based features provide a significant performance improvement over previous handcrafted features. In this study, we demonstrate that we can further improve the discriminative power of CNN-based features and achieve more accurate classification of texture images. In particular, we have designed a discriminative neural network-based feature transformation(NFT) method, with which the CNN-based features are transformed to lower dimensionality descriptors based on an ensemble of neural networks optimized for the classification objective. For evaluation, we used three standard benchmark datasets(KTH-TIPS2, FMD, and DTD)for texture image classification. Our experimental results show enhanced classification performance over the state-of-the-art.

关键词： texture classification neural networks feature learning feature transformation

Blockchain-Empowered Token-Based Access Control System with User Reputation Evaluation

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第12期77卷 3163-3184页

作者： Yuzheng Yang Zhe Tu Ying Liu Huachun Zhou school of Electronic and information Engineering Beijing Jiaotong UniversityBeijing100044China

Currently,data security and privacy protection are becoming more and more *** control is a method of authorization for users through predefined ***-based access control(TBAC)enhances the manageability of authorization through the ***,traditional access control policies lack the ability to dynamically adjust based on user access *** user reputation evaluation into access control can provide valuable feedback to enhance system security and *** a result,this paper proposes a blockchain-empowered TBAC system and introduces a user reputation evaluation module to provide feedback on access *** TBAC system divides the access control process into three stages:policy upload,token request,and resource *** user reputation evaluation module evaluates the user’s token reputation and resource reputation for the token request and resource request stages of the TBAC *** proposed system is implemented using the Hyperledger Fabric *** TBAC system is evaluated to prove that it has high processing *** user reputation evaluation model is proved to be more conservative and sensitive by comparative study with other *** addition,the security analysis shows that the TBAC system has a certain anti-attack ability and can maintain stable operation under the Distributed Denial of Service(DDoS)attack environment.

关键词： Access control reputation evaluation feedback blockchain

Novel Sequential Neural Network Learning Algorithm for Function Approximation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Beijing Institute of Technology 2007年第2期16卷 197-200页

作者：康怀祺史彩成何佩琨李晓琼 school of information Science and Technology Beijing Institute of Technology

A novel sequential neural network learning algorithm for function approximation is presented. The multi-step-ahead output predictor of the stochastic time series is introduced to the growing and pruning network for constructing network structure. And the network parameters are adjusted by the proportional differential filter （PDF） rather than EKF when the network growing criteria are not met. Experimental results show that the proposed algorithm can obtain a more compact network along with a smaller error in mean square sense than other typical sequential learning algorithms.

关键词： sequential learning predictor proportional differential filter (PDF) neural network

A photometric study of the K-type contact binary EI CVn

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2011年第2期11卷 181-190页

作者： Yuan-Gui Yang school of Physics and Electronic information,Huaibei Normal University,Huaibei 235000,China school of Physics and Electronic information Huaibei Normal University Huaibei 235000 China

We present charge-coupled device （CCD） photometry for the short-period K-type binary EI CVn,observed on 2009 February 28 at the Xinglong Station of National Astronomical Observatories,Chinese Academy of *** using the Wilson-Devinney program,the photometric solution was first deduced from our V R *** results show that EI CVn is a W-type weak-contact binary with a mass ratio of qph=0.2834（±0.0010） and an overcontact degree of f=20.0%（±0.7%）.The distorted light curves were modeled by a dark spot on the cool primary component,whose area was up to 1.9% of the area of the *** on the period analysis,it is found that there exists a weak secular decrease at a rate of dP/dt= 3.11（±0.03） × 10-7 d yr-1,which may be attributed to mass transfer from the primary to the *** mass transfer occurring,the separation between both components will shrink,which may cause the degree of overcontact to ***,the weak-contact binary EI CVn may evolve into a deep-contact configuration.

关键词： stars: binaries: close -- stars: binaries: eclipsing -- stars: individual: EICVn

Study on autonomous navigation based on pulsar timing model

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2009年第2期52卷 303-309页

作者： LI JianXun KE XiZheng school of Automation and information Engineering Xi′an University of TechnologyXi’an 710048China

The basic principle of pulsar timing model was introduced, and the general relativistic corrections were analyzed when pulse time of arrival (TOA) was transferred to coordinate TOA at the Solar System Barycentre. Based on the shifting, an iterative method of autonomous position determination for spacecraft was developed. Accordingly, the linear form of the position offset equation was evolved. Using the initial estimated value of spacecraft’s position as the input of pulsar timing equation, through calculation of the offset between measured or transferred and predicted TOA, the position offset can be solved by Least Squares. At last, the main error sources including modeling error and parameters error were discussed.

关键词： X-ray pulsar pulsar timing model autonomous navigation TOA measurement

On the Probability Density Function of the Real and Imaginary Parts in WFRFT Signals

在线全文

学校读者我要写书评

暂无评论

China Communications 2016年第9期13卷 44-52页

作者： Xiaolu Wang Lin Mei Zhenduo Wang Naitong Zhang Communications Research Center School of Electronics and Information EngineeringHarbin Institute Technology

Recently a Hybrid Carrier （HC） scheme based on Weighted-type Fractional Fourier Transform （WFRFT） was proposed and developed, which contains Single Carrier （SC） and Multi-Carrier （MC） synergetie transmission. The wide interest is primarily due to its appealing characteristics, such as the robust performances in different types of selective fading channels and a great deal of potential for secure communications. According to the literatures, the HC signal and SC or MC signal probability distributions are different. In particular, some benefits of this HC scheme are brought by the quasi-Gaussian distribution of WFRFT signals. However, until now researchers have only presented statistic properties through computer simulations, and the accurate expressions of signals are not derived yet. In this paper, we derive the accu- rate and rigorously established closed-form expressions of Probability Density Function （PDF） of WFRFT signal real and imaginary parts with a large number of QPSK subcarriers, and this PDF can describe the behavior of data modulated by WFRFT, avoiding the complex computation for extensive computer simulations. Furthermore, the components of PDF expression are described and analyzed, and it is revealed that the tendency of signal quasi-Gaussian changes with the increasing of the parameter a （a in （0,1]）. To validate the analytical results, extensive simulations have been conducted, showing a very good match between the analytical results and the real situations. The contribution of this paper may be useful to deduce the closed form expressions of Bit Error Ratio （BER）, the Complementary Cumulative Distribution Function （CCDF） of Peak to Average Power Ratio （PAPR）, and other analytical studies which adopt the PDF.

关键词： weighted-type fractional Fourier transform probability density function single carrier multi-carrier hybrid carrier

Building and application of multipath model for meter-wave radar in elevation estimation

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2010年第6期17卷 741-745页

作者：陈迪沈一鹰 school of Electronics and information Technology Harbin Institute of Technology

A research is done for multipath effects of low-angle tracking in meter-wave radar, and the theory of multi-scattering centers of complex target is discussed as well as the character of reflected echoes. This points out that the distribution and scattering properties of scattering centers are the prime reasons which cause the variation of muhipath effects, and all the changes of position, motion and attitude of the target can influence the muhipath effects. By building of muhipath model for multi-scattering centers for target, the analysis above is verified and a new method of elevation estimation for low-angle target is presented. The new method uses canceling vectors obtained by searching to cancel reflected waves in echoes and reduce the influence of reflected com- ponents, which can improve the accuracy of elevation estimation of low-angle target and the performance of low- angle tracking in meter-wave radar. Experimental results verify the availability of the method.

关键词： multi-scattering centers muhipath model target elevation estimation ~~