检索结果-南通市图书馆

Electrostatic Nonlinear structures in Dissipative Electron-Positron-Ion quantum Plasmas

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2008年第12期25卷 4329-4332页

作者： s. A. Khan q. haque Department of Physics COMSATS Institute of Information Technology Islamabad Pakistan and Department of Physics Government College Bagh 12500 AJK Pakistan Theoretical Plasma Physics Division PINSTECH P. O. Nilore Islamabad Pakistan

Low frequency （in comparison to ion plasma frequency） ion-acoustic shocks and solitons in superdense electronpositron-ion quantum plasmas are studied. The quantum hydrodynamic model is used incorporating quantum Bohm forces and Fermi-Dirac statistical corrections to derive the deformed Korteweg de Vries-Burgers （dKdVB） equation in weakly nonlinear limit. The travelling wave solution of dKdVB equation is presented and results are discussed in different limits. It is found that shock height increases with increase of quantum pressure, positron concentration and dissipation. Further, it is seen that the width of soliton decreases with increase of quantum pressure

关键词： Nonlinear structure Ion quantum Plasmas

On Identical Problems of Natural Convection in Enclosures and Applications of the Identity Character

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 Thermal science 1993年第2期2卷 116-125页

作者： Yang, M. Tao, W.q. Wang, q.W. Lui, s.s. Xi'an Jiaotong Univ Xi'an China

In this paper, a concept of 'identical problems' of natural convection in enclosures is presented. A pair of problems of natural convection in enclosures is said to be identical if they look different in appearance but with appropriate selection of coordinates and appropriate definition of dimensionless variables for each problem, they will have identical geometric configurations and identical dimensionless governing equations and related boundary conditions. The identical characteristics of a pair of problems of natural convection in enclosures with an internal isolated island are demonstrated via dimensionless mathematical formulation and flow visualization results. Numerical computations are performed and the predicted streamlines agree with the flow visualization results. A number of other possible pairs of identical problems are also presented. Applications of the identical character are provided and assumptions under which the identical problems may exist are discussed.

关键词： natural convection enclosure flow identical problems

Cascaded sliding-mode Observer and Its Applications in Output Feedback Control Part I:Observer Design and stability Analysis

在线全文

学校读者我要写书评

暂无评论

CsEE Journal of Power and Energy systems 2021年第2期7卷 295-306页

作者： Tianhao Wen Yang Liu q.h.Wu Luonan qiu school of Electric Power Engineering South China University of TechnologyGuangzhou 510640China

This paper proposes a cascaded sliding-mode observer for systems with high relative degree and studies its applications in output feedback controller *** part I,the working principle and parameter design of the proposed observer are discussed in *** is proved that,within a sufficiently short period of time,the states of the proposed observer will reach the intersection of all the sliding *** sliding surfaces,the observation error of the proposed observer will converge to sufficiently small *** with traditional high-gain observers,the proposed observer has smaller gain *** addition,the peaking-phenomenon occurred in the proposed observer is less ***,the proposed observer has a convergence rate of observation error as fast as that of traditional high-gain *** studies are carried out on a fifth-order system to verify the properties of the proposed observer.

关键词： sliding-mode observer stability output feedback control

A hybrid signal Processing Method Combining Mathematical Morphology and Walsh Theory for Power quality Disturbance Detection and Classification

在线全文

学校读者我要写书评

暂无评论

CsEE Journal of Power and Energy systems 2024年第2期10卷 584-592页

作者： Zhi Ding Tianyao Ji Mengshi Li q.h.Wu school of Electric Power Engineering South China University of Technology(SCUT)Guangzhou 510641China

In this paper, a novel signal processing method combining mathematical morphology (MM) and Walsh theory is proposed, which uses Walsh functions to control the structuring element (sE) and MM operators. Based on the Walsh-MM method, a scheme for power quality disturbances detection and classification is developed, which involves three steps: denoising, feature extraction and morphological clustering. First, various evolution rules of Walsh function are used to generate groups of sEs for the multiscale Walsh-ordered morphological operation, so the original signal can be denoised. Next, the fundamental wave of the denoised signal is suppressed by hadamard matrix;thus, disturbances can be extracted. Finally, the Walsh power spectrum of the waveform extracted in the previous step is calculated, and the parameters of which are taken by morphological clustering to classify the disturbances. simulation results reveal the proposed scheme can effectively detect and classify disturbances, and the Walsh-MM method is less affected by noise and only involves simple calculation, which has a potential to be implemented in hardware and more suitable for real-time application.

关键词： hadamard matrix mathematical morphology morphological clustering power quality disturbance Walsh theory

Generative Adversarial Network Based heuristics for sampling-Based Path Planning

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica sinica 2022年第1期9卷 64-74页

作者： Tianyi Zhang Jiankun Wang Max q.-h.Meng Department of Electronic and Electrical Engineering Southern University of Science and TechnologyShenzhen 518055China

sampling-based path planning is a popular methodology for robot path *** a uniform sampling strategy to explore the state space,a feasible path can be found without the complex geometric modeling of the configuration ***,the quality of the initial solution is not guaranteed,and the convergence speed to the optimal solution is *** this paper,we present a novel image-based path planning algorithm to overcome these ***,a generative adversarial network(GAN)is designed to take the environment map(denoted as RGB image)as the input without other preprocessing *** output is also an RGB image where the promising region(where a feasible path probably exists)is *** promising region is utilized as a heuristic to achieve non-uniform sampling for the path *** conduct a number of simulation experiments to validate the effectiveness of the proposed method,and the results demonstrate that our method performs much better in terms of the quality of the initial solution and the convergence speed to the optimal ***,apart from the environments similar to the training set,our method also works well on the environments which are very different from the training set.

关键词： Generative adversarial network(GAN) optimal path planning robot path planning sampling-based path planning

Fault Identification in Power Network Based on Deep Reinforcement Learning

在线全文

学校读者我要写书评

暂无评论

CsEE Journal of Power and Energy systems 2022年第3期8卷 721-731页

作者： Mengshi Li huanming Zhang Tianyao Ji q.h.Wu school of Electric Power Engineering South China University of TechnologyGuangzhou510641China

With the integration of alternative energy and renewables,the issue of stability and resilience of the power network has received considerable *** basic necessity for fault diagnosis and isolation is fault identification and *** conventional intelligent fault identification method needs supervision,manual labelling of characteristics,and requires large amounts of labelled *** enhance the ability of intelligent methods and get rid of the dependence on a large amount of labelled data,a novel fault identification method based on deep reinforcement learning(DRL),which has not received enough attention in the field of fault identification,is investigated in this *** proposed method uses different faults as parameters of the model to expand the scope of fault *** addition,the DRL algorithm can intelligently modify the fault parameters according to the observations obtained from the power network environment,rather than requiring manual and mechanical tuning of *** methodology was tested on the IEEE 14 bus for several scenarios and the performance of the proposed method was compared with that of population-based optimization methods and supervised learning *** obtained results have confirmed the feasibility and effectiveness of the proposed method.

关键词： Artificial intelligence deep q network deep reinforcement learning fault diagnosis fault identification parameter identification power network

Interface defeat studies of long-rod projectile impacting on ceramic targets

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2020年第1期16卷 50-68页

作者： Y.X.Zhai h.Wu q.Fang Amy Engineering University of PLA Nanjing210007China Research Institute of structural Engineering and Disaster Reduction College of Civil EngineeringTongji UniversityShanghai200092China

The interface defeat phenomenon always occurs when a long-rod projectile impacting on the ceramic target with certain velocity,i.e.,the projectile is forced to flow radially on the surface of ceramic plates for a period of time without significant *** defeat has a direct effect upon the ballistic performance of the armor piercing projectile,which is studied numerically and theoretically at ***,by modeling the projectiles and ceramic targets with the sPh(smoothed Particle hydrodynamics)particles and Lagrange finite elements,the systematic numerical simulations on interface defeat are performed with the commercial finite element program *** different responses,i.e.,complete interface defeat,dwell and direct penetration,are reproduced in different types of ceramic targets(bare,buffered,radially confined and oblique).Furthermore,by adopting the validated numerical algorithms,constitutive models and the corresponding material parameters,the influences of projectile(material,diameter,nose shape),constitutive models of ceramic(Jh-1 and Jh-2 models),buffer and cover plate(thickness,constraints,material),as well as the prestress acted on the target(radial and hydrostatic) on the interface defeat(transition velocity and dwell time) are syste matically ***,based on the energy conservation approach and taking the strain rate effect of ceramic material into account,a modified model for predicting the upper limit of transition velocity is proposed and *** present work and derived conclusions can provide helpful reference for the design and optimization of both the long-rod projectile and ceramic armor.

关键词： Interface defeat Ceramic Transition velocity Numerical simulation Parametric study

Fault Location in Distribution system Using Convolutional Neural Network Based on Domain Transformation

在线全文

学校读者我要写书评

暂无评论

CsEE Journal of Power and Energy systems 2021年第3期7卷 472-484页

作者： Yang Yu Mengshi Li Tianyao Ji q.h.Wu school of Electric Power Engineering South China University of TechnologyGuangzhou 510640China

Distribution lines are integral parts of the modern power system,which can affect the security and stability of power supply *** effective power system protection scheme should be able to detect all occurring faults as soon as *** are two tasks in fault *** is the fault classification,where high accuracy rates have already ***,this paper focuses on the other task,*** *** by Fourier transform,this paper proposes an online data-driven method,which transforms signals from time domain to image domain through signal-to-image(sIG)algorithm and then process the transformed images with framework based on convolutional neural network(CNN).On the one hand,we can extract more crucial characteristic and information from image *** the other hand,the CNN-based structure is much smaller than *** needs less memory space and would be easier to be transplanted to hardware ***,the proposed algorithm does not require synchronous *** numerical comparison shows that the proposed sIG-CNN fault location model achieves robust and accurate results compared with other data-driven algorithms.

关键词： Convolutional neural network distribution lines domain transformation fault location

Using sPOT 5 fusion-ready imagery to detect Chinese tamarisk(saltcedar)with mathematical morphological method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2014年第3期7卷 217-228页

作者： q.s.Liu G.h.Liu C.huang C.J.Xie state Key Laboratory of Resources and Environmental Information system Institute of Geographic Science and Natural Resources ResearchChinese Academy of SciencesBeijingChina

Chinese tamarisk(saltcedar)is a deciduous shrub that occurs widely across the Yellow River Delta in *** spatial structure of Chinese tamarisk is believed to have an influence on the landscape and habitats of rare *** this study,first,Chinese tamarisk is detected using Canny edge detector and mathematical morphological operators based on sPOT 5 fusion-ready *** the numbers,areas,locations,and patch spacing of Chinese tamarisk patches are *** experiments show that the detection accuracy of Chinese tamarisk patches is about 93.4%after the disconnection of connected *** distribution orientation of about 70%of the patches is approximately *** 91%of the minimum distances among the patches are between 12.5 and 57.5 *** rose graph indicates that the main azimuth between patches is north--northwest,and the second is northeast and *** present study indicates that the integrating Canny edge detector with the algorithms for extracting circular and elliptical objects based on mathematical morphology is simple and effective for detecting Chinese tamarisk patches and is easy to identify the spatial structure of Chinese tamarisk patches,which reduces the time and labor for the visual interpretation of Chinese tamarisk patches.

关键词： sPOT 5 Chinese tamarisk spatial structure mathematical morphology patch