检索结果-南通市图书馆

Novel Nano Structure for Green Energy Harvesting at 10μm Thermal Radiation

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 Electronic Science and Technology 2016年第3期14卷 242-248页

作者： Mohd Khairul Hisham Ismail Mazlina Esa Mohd Fairus Mohd Yusoff Noor Asniza Murad National Space Agency Banting 42700Malaysia the faculty of electrical engeering Universiti Teknologi MalaysiaJohor Bahru 81310Malaysia

In recent years, the potential of renewable green energy sources has been extensively studied. The proven technology which is photovoltaic solar cells strictly depends on daylight and produces low-efficiently. To overcome the restrictions, one technology studied is through harvesting the thermal radiation energy which can provide a 24-hour energy source. The continuity of energy sources promises very good energy conversion especially for military applications. This article presents a new structure that can harvest the abundant thermal radiation energy into usable energy at the wavelength of l0 lum. A rectangular structure with a perturbation slit was designed to integrate with a rectifier circuit for green energy conversion. The slit tunnel junction guided the electromagnetic field into a junction where the energy could be collected and converted. An enhancement factor of approximately 110.6 can be achieved by a perturbation slit length of 1.0 μm. The results extracted from the proposed design promise a better candidate to overcome the disadvantages of photovoltaic solar cells for energy harvesting devices.

关键词： Enhancement factor green energy harvesting renewable thermal radiation.

electrical Resistance Behavior of Vinylester Composites Filled with Glass-carbon Hybrid Fibers

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2009年第2期24卷 295-299页

作者：王钧 School of Materials Science and engeering Wuhan University of Technology

Vinylester （bismethacryloxy derivative with glass-carbon hybrid fibers （CF-GF） weight fraction of a bisphenol-A type EP resin, VE） composites of 50%, were prepared by the compress molding method. The distribution of carbon fiber in the hybrids was observed by stereomicroscope. The electrical resistance behavior of the composites filled with different carbon fiber （CF） weight contents （0.5% to 20%） was studied. The experimental results show that the electrical resistance behaviors of CF-GF/VE composites are different with those of CF/VE composites because carbon fibers＇ conducting networks are broken by the glass fibers in the CF-GF/VE composites. The carbon fibers distribute uniformly in the networks of glass fibers （GF） like single silk and form the semi-continuous conducting networks. Composite filled with GF-CF hybrid has a higher percolation threshold than that filled with pure CF. At that time, the resistivity of CF-GF/VE composites varies little with the temperature increasing. The temperature coefficient of resistivity in GF-CF/VE composite is less than 317 ppm and the variation of the resistivity after ten thermal cycles from 20℃ to 240 ℃is less than 1.96%.

关键词： conducting composite hybrid fibers resistivity-temperature coefficient synergy effect

Automatic landing system using neural networks and radio-technical subsystems

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2017年第1期30卷 399-411页

作者： Romulus Lungu Mihai Lungu University of Craiova Faculty of Electrical Engineering

The paper focuses on the design of a new automatic landing system（ALS） in longitudinal plane; the new ALS controls the aircraft trajectory and longitudinal velocity. Aircraft control is achieved by means of a proportional-integral（PI） controller and the instrumental landing system– the first phase of landing（the glide slope） and a proportional-integral-derivative（PID） controller together with a radio-altimeter – the second phase of landing（the flare）; both controllers modify the reference model associated with aircraft pitch angle. The control of the pitch angle and longitudinal velocity is performed by a neural network adaptive control system, based on the dynamic inversion concept, having the following as components： a linear dynamic compensator, a linear observer, reference models, and a Pseudo control hedging（PCH） block. The theoretical results are software implemented and validated by complex numerical simulations; compared with other ALSs having the same radio-technical subsystems but with conventional or fuzzy controllers for the control of aircraft pitch angle and longitudinal velocity, the architecture designed in this paper is characterized by much smaller overshoots and stationary errors.

关键词： Adaptive control Automatic landing Neural network PID Reference model

Fast Convergence Resource Allocation in IEEE 802.16 OFDMA Systems with Minimum Rate Guarantee

在线全文

学校读者我要写书评

暂无评论

China Communications 2016年第12期13卷 120-131页

作者： Mohammad Mostafavi Javad Musevi Niya Hosein Mohammadi Behzad Mozaffari Tazehkand faculty of electrical and Computer Engineering University of Tabriz faculty of electrical and Computer Engineering University of Zanjan

Resource allocation in the context of OFDMA-based systems is challenging, given a combinatorial nature of the problem. In the context of IEEE 802.16 systems this problem is further exacerbated by additional constraints that are faced with its two dimensional frame nature. The main challenges associated with resource allocation in these systems are: mapping the allocated bandwidth resources to users in this two dimensional frame, power and frequency allocation, and Qo S guarantee. This optimization problem can usually be solved by an iterative algorithm. The solutions proposed have a constant step size in iterations which causes a long convergence time. For this reason, the solutions proposed are not applicable in IEEE 802.16 systems. In this paper we propose a novel resource allocation algorithm in IEEE 802.16 systems which has an adaptive step size in iterations while taking into account the minimum rate guarantee for users.

关键词： burst pack channel aware la grangian function OFDMA power allocation sub-channel allocation

Robust pre-specified time synchronization of chaotic systems by employing time-varying switching surfaces in the sliding mode control scheme

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第8期25卷 86-93页

作者： Alireza Khanzadeh Mahdi Pourgholi faculty of electrical Engineering Shahid Beheshti University

In the conventional chaos synchronization methods, the time at which two chaotic systems are synchronized, is usually unknown and depends on initial conditions. In this work based on Lyapunov stability theory a sliding mode controller with time-varying switching surfaces is proposed to achieve chaos synchronization at a pre-specified time for the first time. The proposed controller is able to synchronize chaotic systems precisely at any time when we want. Moreover, by choosing the time-varying switching surfaces in a way that the reaching phase is eliminated, the synchronization becomes robust to uncertainties and exogenous disturbances. Simulation results are presented to show the effectiveness of the proposed method of stabilizing and synchronizing chaotic systems with complete robustness to uncertainty and disturbances exactly at a pre-specified time.

关键词： chaos synchronization finite time synchronization sliding mode controller time varying switching surfaces

Histogram of the node strength and histogram of the edge weight: two new features for RGB-D person re-identification

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2018年第9期61卷 112-125页

作者： Zeynab IMANI Hadi SOLTANIZADEH electrical and Computer Engineering faculty Semnan Univercity

Person re-identification is a classical task for any multi-camera surveillance system. Most of the existing researches on re-identification are based on features extracted from RGB images. However,there are many deficiencies in RGB image processing, some of which are requiring a lot of illumination and high computation. In this paper, novel features are proposed for RGB-D person re-identification. First, the complex network approach in texture recognition is modified and its threshold function is changed for using in depth images extracted by RGB-D sensors. Then, two novel measurements named the histogram of the edge weight(HEW) and the histogram of the node strength(HNS) are introduced on complex *** features fit both single-shot and multi-shot person re-identification. In the single-shot case, the HNS is extracted from only one frame while for the multi-shot case it is extracted from both one frame and multi-frames. These proposed measurements are called histogram of the spatial node strength(HSNS)and histogram of the temporal node strength(HTNS) respectively. Subsequently, these measurements are combined with skeleton features using score-level fusion. The method is evaluated using two benchmark databases and the results show that ours outperforms some state-of-the-art methods.

关键词： complex network edge weight graph node strength person re-identification skeleton features

Global Optimum-Based Search Differential Evolution

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2019年第2期6卷 379-394页

作者： Yang Yu Shangce Gao Yirui Wang Yuki Todo the faculty of Engineering University of Toyama the faculty of electrical and Computer Engineering Kanazawa University

In this paper, a global optimum-based search strategy is proposed to alleviate the situation that the differential evolution(DE) usually sticks into a stagnation, especially on complex problems. It aims to reconstruct the balance between exploration and exploitation, and improve the search efficiency and solution quality of DE. The proposed method is activated by recording the number of recently consecutive unsuccessful global optimum updates. It takes the feedback from the global optimum,which makes the search strategy not only refine the current solution quality, but also have a change to find other promising space with better individuals. This search strategy is incorporated with various DE mutation strategies and DE variations. The experimental results indicate that the proposed method has remarkable performance in enhancing search efficiency and improving solution quality.

关键词： Differential evolution(DE) global optimum memetic algorithm

Numerical Analysis of MHD Accelerator with Non-Equilibrium Air Plasma

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2012年第12期14卷 1110-1115页

作者： M.ANWARI H.H.QAZI SUKARSAN N.HARADA electrical Engineering Department Umm Al-Qura University faculty of electrical Engineering Universiti Teknologi Malaysia faculty of electrical Engineering Universitas Islam "45" Bekasi Department of electrical Engineering Nagaoka University of Technology

Magnetohydrodynamic （MHD） accelerator is proposed as a next generation propulsion system. It can be used to increase the performance of a propulsion system. The objective of this study is to investigate the performance of MHD accelerator using non-equilibrium air plasma as working gas. In this study, the fundamental performance of MHD accelerator such as flow performance and electrical performance is evaluated at different levels of applied magnetic field using I-D numerical simulation. The numerical simulation is developed based on a set of differential equations with MHD approximation. To solve this set of differential equations the MacCormack scheme is used. A specified channel designed and developed at NASA Marshall Space Flight Centre is used in the numerical simulation. The composition of the simulated air plasma consists of seven species, namely, N2, N, O2, O, NO, NO＋, and e-. The performance of the non-equilibrium MHD accelerator is also compared with the equilibrium MHD accelerator.

关键词： MHD accelerator Faraday type connection non-equilibrium air plasma

Effects of Location,Size and Number of Wind Turbine Receptors on Blade Lightning Protection

在线全文

学校读者我要写书评

暂无评论

电力系统自动化 2012年第8期36卷 122-127页

作者： Hossein Kazemi KAREGAR Hossein BAGHERIAN faculty of electrical &Computer Engineering Shahid Beheshti University

Electric and magnetic fields generated by lightning cause a serious hazard to various *** wind turbine installations with higher power capacity are *** power capacity requires higher height and so there is more probability of lightning *** are the most probable components to be struck by *** most common lightning protection system for the blades consists of several metallic receptors on the blade *** are connected to the ground by metallic down-conductors placed inside the blade *** paper studies effects of the receptor configurations on protecting the blade against lightning *** this purpose,an analysis procedure based on finite element method(FEM)in COMSOL Multiphysics software environment is *** voltage distribution around the blade is simulated for various configurations of *** best configuration is *** are performed on the blade model of a special wind turbine,which isVESTAS V47".

关键词：风力发电机组受体刀片防雷叶片表面位置最佳配置发电能力