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In smart grid, how to establish a communication paradigm among the customers, smart meter and utilities is an important challenge, which requires access control, data encryption, and authentication to ensure message integrity and confidentiality. In this paper, we present a communication architecture based on Attribute Based Cryptosystem to secure the communications in smart grids. In this paper,...
The surveillance for data collection in wireless sensor networks (WSNs) setting is recognized as an important application of WSNs. Given an area of interest and a number of wireless sensors, typical problems to be addressed are covering the whole area while prolonging the network lifetime. It is explicitly observed that most existing studies focus on limited case in which the interested area is static...
Coastal discharge plume is one of the most important pollution hazards for the heavily polluted estuaries in Shenzhen, China. Due to their dynamic and episodic nature, these pollutions are difficult to sample adequately using traditional in situ measurement methods. This paper introduces a plume extraction method using fully polarimetric synthetic aperture radar (SAR) image. TerraSAR data acquired...
Synthetic Aperture Rader (SAR), with all-weather and all-time imaging capabilities, provides a stable data resource for environmental monitoring. In water related applications, obtaining precise water areas from SAR data is essential. This paper presents a high accuracy water extraction scheme based on Object-Oriented technique. First, a watershed segmentation is used for preserve waterlines. Then,...
To give full play to the advantages of case-based reasoning and ontology, this paper combines them effectively. The method of e-government case representation is introduced in detail. A comprehensive ontology similarity calculation approach is used on the case query network. Finally the e-government discipline inspection and supervision case-based reasoning system is developed. We use the ontology...
As the interest towards wind energy becomes a great concern, it's significant to model wind speed accurately and smoothly for the simulation of wind power system in laboratory. In view of this, an improved wind speed model with 4 components has been established by Matlab/Simulink platform, which shows well performance in describing real wind characteristics of gust, gradual change wind and random...
As wind turbine rated power increase, the potential danger of the vibration is serious result of the rotor diameter and the hub height is longer and higher. Wind turbine vibrations will cause futile mechanical loads, such vibration loads maybe result to serious damage of wind turbine. In order to achieve vibration suppression, taking the uncertainty of turbulence which the operate environment of wind...
In order to determine the stability regions of wind turbine generators in the process of operation, and make wind turbine generators can be faster to stable through add some necessary control link (as V function). In this paper, theorems and applications of the Lure Lyapunov function are given, the generalized mathematical model of tower system are established by a series of physical analysis and...
With new energy requirements increase in power market environment, wind power development has played a very significant role in renewable energy area for improving the energy structure, climate change and energy security issues. The dispatching of grid-connected wind turbines impacts the stability of the power system to a large degree. In recent years, there are many wind power dispatching studies...
As the most widely used wind turbine generating system, the Doubly-fed induction generators, whose output characteristics is worth studying in depth when connected to the grid. In order to study output characteristics of Doubly-fed wind turbines, simulate the response characteristics of the units' main parameters under different wind conditions with the aid of Bladed software. The establishment of...
The finite difference time domain (FDTD) method is widely implemented for numerical simulations of acoustic fields. When the size of the model is too large, the amount of the grid points in the computational region is huge, the simulation will cost a lot of calculation time when using CPU in a serial program. The paralleled method as MPI is not so convenient to be applied in the practical engineering...
This paper applies panel methodology to examine the short-run dynamics, the long-run equilibrium relationships and the causal relationship between energy consumption and economic growth. It is based on China's 37 industrial sectors over the period 1998 to 2010. Tests for panel unit roots, co integration in heterogeneous panels and panel causality are employed in a bivariate panel vector error correction...
The finite difference time domain (FDTD) method is widely used in numerical simulations of acoustic fields. When the size of the model is too large, the amount of the grid points in the computational region is correspondingly huge, then the simulation will cost a lot of calculation time using CPU in a serial program. In this paper we use the graphic processing unit (GPU) to solve this problem. First,...
Many collapse cases of wind turbines which operated in wind farms are caused by the event that blade tip hits the tower. So, one of the important indicators in wind turbine design is the tip deflection estimation. The distance from tip to the outside of the tower determines the safety of wind turbines. Usually the maximum tip deflection (also known as displacement) possibly occurs in some extreme...
Pitch actuator endures complex load during operation process of wind turbine, and its load-bearing capacity influences the safe operation of whole wind turbine. In this paper, according to the operation control requirements of wind turbine, all kinds of complex operation conditions of pith actuator are taken into account, and GL-bladed software is used to calculate the load of pitch actuator. And...
This paper, based on the reduced version of Beddoes-Leishman dynamic stall model, makes deeply research about airfoil dynamic stall for wind turbines. Considering about the operating environment of wind turbine, the model, constructed in this paper, neglects the compressibility of airflow, and mainly considers attached flow, trailing edge separation and vortex lift. This paper uses fourth-order Runge-Kutta...
The technique of nonlinear modeling for environmental clutter has been widely used in the application of radar. This article mainly generalizes various kinds of techniques of the nonlinear modeling for environmental clutter. Then, the article gives several suggestions based on our country's status of the technique of the modeling for environmental clutter.
Although there have been recent extensive research cooperation network and online community, have very limited knowledge of the actual development of online social networks. In the paper, we consider the structural evolution of a large online social networks. The theoretical analysis and simulation results show that, the evolution of the social networks model with scale-free and small-world properties...
Desire for super maneuverability and agility for modern air vehicles has resulted in high angles of attack flights. Different dynamic instability phenomenon may arise at high angles of attack. Wing rock, which is self excited limit cycle oscillations in roll mainly, is amongst one of these. Experiments have been carried out at sub-critical Reynolds number to investigate un-commanded free-to-roll (FTR)...
We studied the influence of external electric field on two-wave mixing feature in a Ce: KNSBN crystal using a non-simultaneous readout device on the best writing conditions (with best polarization of writing beam). The effective gain and diffraction efficiency of two-wave mixing increased as well as the response time decreased as positive electric field increased applied along the c-axis of the crystal...
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