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Detection of rapidly developing convection using rapid scan data from a geostationary satellite

REMOTE SENSING LETTERS 2015年第8期6卷 604-612页

作者： Liu, Jia Liu, Chuancai Gu, Xingjian Qin, Danyu Nanjing Univ Sci & Technol Sch Comp Sci & Engn Dept Intelligent Sci & Technol Nanjing Jiangsu Peoples R China China Meteorol Adm Inst Meteorol Natl Satellite Meteorol Ctr Beijing Peoples R China

Accurate rapidly developing convection (RDC) detection is an essential part of a severe weather warning. A novel algorithm called object track and identification (OTI) is proposed for detecting RDC using infrared image sequences from geostationary meteorology satellite. Convective cells are computed using extended maxima transform-based region growing algorithm. Firstly, a novel area overlap-based object tracking method is proposed to track convective cells in successive images. Secondly, the lowest 25% of overall brightness temperature of the same convective cloud is averaged in order to preserve the extremum information of evolution of cloud. Thirdly, a new identification criterion, which contains three subcriteria, is developed to detect RDC. Contingency table approach applied to various case studies over China shows that the OTI algorithm is efficient and accurate.

关键词： GEOSTATIONARY satellites CONVECTION (Meteorology) OBJECT tracking (computer vision) computer algorithms INFRARED imaging WEATHER forecasting CONVECTIVE clouds

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Map Matching Based on Conditional Random Fields and Route Preference Mining for Uncertain Trajectories

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MATHEMATICAL PROBLEMS IN ENGINEERING 2015年第1期2015卷 1-13页

作者： Xu, Ming Du, Yiman Wu, Jianping Zhou, Yang Beijing Univ Posts & Telecommun Sch Comp Sci Beijing 100876 Peoples R China Tsinghua Univ Sch Civil Engn Beijing 100084 Peoples R China

In order to improve offline map matching accuracy of uncertain GPS trajectories, a map matching algorithm based on conditional random fields (CRF) and route preference mining is proposed. In this algorithm, road offset distance and the temporal-spatial relationship between the sampling points are used as features of GPS trajectory in a CRF model, which integrates the temporal-spatial context information flexibly. The driver route preference is also used to bolster the temporal-spatial context when a low GPS sampling rate impairs the resolving power of temporal-spatial context in CRF, allowing the map matching accuracy of uncertain GPS trajectories to get improved significantly. The experimental results show that our proposed algorithm is more accurate than existing methods, especially in the case of a low-sampling-rate.

关键词： MAPS RANDOM fields TRAJECTORIES (Mechanics) GLOBAL Positioning System computer algorithms

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Decentralized Identification and Control in Real-Time of a Robot Manipulator via Recurrent Wavelet First-Order Neural Network

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MATHEMATICAL PROBLEMS IN ENGINEERING 2015年第1期2015卷 1-12页

作者： Vazquez, Luis A. Jurado, Francisco Alanis, Alma Y. Inst Tecnol La Laguna Tecnol Nacl Mexico Torreon 27000 Coah Mexico Univ Guadalajara CUCEI Guadalajara 44430 Jal Mexico

A decentralized recurrent wavelet first-order neural network (RWFONN) structure is presented. The use of a wavelet Morlet activation function allows proposing a neural structure in continuous time of a single layer and a single neuron in order to identify online in a series-parallel configuration, using the filtered error (FE) training algorithm, the dynamics behavior of each joint for a two-degree-of-freedom (DOF) vertical robot manipulator, whose parameters such as friction and inertia are unknown. Based on the RWFONN subsystem, a decentralized neural controller is designed via backstepping approach. The performance of the decentralized wavelet neural controller is validated via real-time results.

关键词： DECENTRALIZATION in management ROBOTS WAVELETS (Mathematics) computer algorithms DEGREES of freedom

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Discrete-Time Nonlinear Control of VSC-HVDC System

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MATHEMATICAL PROBLEMS IN ENGINEERING 2015年第1期2015卷 p1-11页

作者： Qian, TianTian Miao, ShiHong Huazhong Univ Sci & Technol State Key Lab Adv Electromagnet Engn & Technol Wuhan 430074 Peoples R China

Because VSC-HVDC is a kind of strong nonlinear, coupling, and multi-input multioutput (MIMO) system, its control problem is always attracting much attention from scholars. And a lot of papers have done research on its control strategy in the continuous-time domain. But the control system is implemented through the computer discrete sampling in practical engineering. It is necessary to study the mathematical model and control algorithm in the discrete-time domain. The discrete mathematical model based on output feedback linearization and discrete sliding mode control algorithm is proposed in this paper. And to ensure the effectiveness of the control system in the quasi sliding mode state, the fast output sampling method is used in the output feedback. The results from simulation experiment in MATLAB/SIMULINK prove that the proposed discrete control algorithm can make the VSC-HVDC system have good static, dynamic, and robust characteristics in discrete-time domain.

关键词： DISCRETE-time systems NONLINEAR control theory HIGH-voltage direct current transmission computer algorithms

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Research and Application of Improved AGP Algorithm for Structural Optimization Based on Feedforward Neural Networks

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MATHEMATICAL PROBLEMS IN ENGINEERING 2015年第1期2015卷 1-6页

作者： Wang, Ruliang Sun, Huanlong Zha, Benbo Wang, Lei Guangxi Teachers Educ Univ Comp & Informat Engn Coll Nanning 530023 Peoples R China

The adaptive growing and pruning algorithm (AGP) has been improved, and the network pruning is based on the sigmoidal activation value of the node and all the weights of its outgoing connections. The nodes are pruned directly, but those nodes that have internal relation are not removed. The network growing is based on the idea of variance. We directly copy those nodes with high correlation. An improved AGP algorithm (IAGP) is proposed. And it improves the network performance and efficiency. The simulation results show that, compared with the AGP algorithm, the improved method (IAGP) can quickly and accurately predict traffic capacity.

关键词： STRUCTURAL optimization FEEDFORWARD neural networks CORRELATION (Statistics) computer algorithms COMPARATIVE studies

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Observer-based open transistor fault diagnosis and fault-tolerant control of five-phase permanent magnet motor drive for application in electric vehicles

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IET POWER ELECTRONICS 2015年第1期8卷 76-87页

作者： Salehifar, Mehdi Salehi Arashloo, Ramin Moreno-Eguilaz, Manuel Sala, Vicent Romeral, Luis UPC Dept Elect Engn Terrassa 08222 Spain

To meet increasing demand for higher reliability in power electronics converters applicable in electric vehicles, fault detection (FD) is an important part of the control algorithm. In this study, a model-based open transistor fault diagnsosis method is presented for a voltage-source inverter (VSI) supplying a five-phase permanent magnet motor drive. To realise this goal, a model-based observer is designed to estimate model parameters. After that, the estimated parameters are used to design a sliding mode observer in order to estimate the phase current in an ideal model. Subsequently, the proposed FD technique measures the similarity between the estimated current and real current using cross-correlation factor. This factor is used for the first time in this study to define a FD index in VSI. The presented FD scheme is simple and fast;also, it is able to detect multiple open switch or open phase faults in contrast to conventional methods. On the other side, in order to track reference current of the motor, the estimated parameters are used to design a proportional resonant controller. The FD technique is used to operate a multiphase fault-tolerant brushless direct current (BLDC) motor drive. Experimental results on a five-phase BLDC motor with in-wheel outer rotor applicable in electrical vehicles are conducted to validate the theory.

关键词： Transistor Device Component fault-tolerant control FOCAL LENGTH sliding mode observer voltage source inverter Phase current computer algorithms reference current Electric vehicles Power electronics brushless direct current motor Permanent magnet synchronous machines

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Non-Gaussian Hybrid Transfer Functions: Memorizing Mine Survivability Calculations

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MATHEMATICAL PROBLEMS IN ENGINEERING 2015年第1期2015卷 1-18页

作者： Ansong, Mary Opokua Huang, Jun Steed Yeboah, Mary Ann Dun, Han Yao, Hongxing Jiangsu Univ Fac Sci Inst Syst Engn Zhenjiang 212013 Peoples R China Kumasi Polytech Fac Sci Appl Dept Comp Sci Kumasi Ghana Jiangsu Univ Suqian Coll Comp Sci & Technol Zhenjiang 223800 Jiangsu Peoples R China Kumasi Polytech Sch Appl Sci Dept Math & Stat Kumasi Ghana Jiangsu Univ Coll Finance & Econ Zhenjiang 212013 Peoples R China

Hybrid algorithms and models have received significant interest in recent years and are increasingly used to solve real-world problems. Different from existing methods in radial basis transfer function construction, this study proposes a novel nonlinear-weight hybrid algorithm involving the non-Gaussian type radial basis transfer functions. The speed and simplicity of the non-Gaussian type with the accuracy and simplicity of radial basis function are used to produce fast and accurate on-the-fly model for survivability of emergency mine rescue operations, that is, the survivability under all conditions is precalculated and used to train the neural network. The proposed hybrid uses genetic algorithm as a learning method which performs parameter optimization within an integrated analytic framework, to improve network efficiency. Finally, the network parameters including mean iteration, standard variation, standard deviation, convergent time, and optimized error are evaluated using the mean squared error. The results demonstrate that the hybrid model is able to reduce the computation complexity, increase the robustness and optimize its parameters. This novel hybrid model shows outstanding performance and is competitive over other existing models.

关键词： GAUSSIAN function TRANSFER functions (Mathematics) NUMERICAL calculations computer algorithms PROBLEM solving RADIAL basis functions

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Design and simulation of a finite control set model predictive control system for a regenerative grid simulator

Design and simulation of a finite control set model predicti...

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8th IET International Conference on Power Electronics, Machines and Drives (PEMD 2016)

作者： D.F.F. Ferreira S.M.A. Cruz A.M.S. Mendes Universidade de Coimbra Coimbra Coimbra PT

ISBN: (纸本)9781510825666

This paper presents the power converters topology and the corresponding control systems of a three-phase regenerative grid simulator. The proposed system consists in three identical single-phase units, each one consisting in two H-bridge power converters sharing a common dc-bus. The mathematical model of the two converters is developed and based on them, a finite control set model predictive control strategy was developed for the grid simulator. Simulation results demonstrate the very good dynamic performance of the developed grid simulator under all operating conditions and for all types of loads, as well as the adequacy of predictive control algorithms for the application in question.

关键词： Regenerative grid simulator Finite control set model predictive control Harmonic voltage control Voltage dips voltage sags Predictive control control set simulator control systems Model predictive control grids Grid computer algorithms Regenerative power conversion unit dynamic characteristics simulating

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Control Algorithm for Bidirectional Fly-back Active Cell Balancer with Interleaved Transformer Connections

Control Algorithm for Bidirectional Fly-back Active Cell Bal...

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IEEE Power and Energy Society General Meeting

作者： Mojtaba Saleh Mohammad A. S. Masoum Lindsay Meek Masoud Abshar Department of Electrical and Computer Engineering Curtin University Magellan Powertronics Pty Ltd.

ISBN: (纸本)9781509041695

Fly-back converter has proved a promising option for effective bidirectional active cell balancing in series connected battery stacks. The stack could be organized as a number of subsets to facilitate an interleaved connection across consecutive subsets at the high-voltage side of transformers so that the voltage rating of components will be reduced accordingly. This structure features expandable modular attribute, however, creates more complicated charge transfer between cells which has to be taken into account in the control scheme. This paper sets out the operation principals and proposes a control strategy handling intra-subset imbalance as well as inter-subset uneven charge distribution. The results of simulation study confirms the effectiveness of the proposed control method in both charge and discharge cycles.

关键词： Active cell balancer Charge equalization Series-connected battery string Fly-back converter computer algorithms Transformer Bidirectional Control Methods Nominal Voltage Connections Cells discharge period Converters control strategy Connections Simulation results charge transfer Batteries

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Attitude Determination and Control System for Nadir Pointing Using Magnetorquer and Magnetometer

Attitude Determination and Control System for Nadir Pointing...

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IEEE Aerospace Conference

作者： Nobuo Sugimura Toshinori Kuwahara Kazuya Yoshida Dept. of Aerospace Engineering Tohoku University 6-6-11 AramakiAoba Aoba-ku Sendai Miyagi 9808579 Japan

ISBN: (纸本)9781467376778

A low-cost attitude determination and control system (ADCS) is proposed for nadir-pointing control. This system comprises three-axis magnetorquers and magnetometers. The aim for developing this system is to establish a nadir-pointing control method using only low-cost spacecraft components for active control. Recently, low-cost and reliable development has become a required for spacecraft development. Generally, star trackers, reaction wheels, and thrusters are used for accurate attitude determination and spacecraft control. They have high reliability but their cost becomes a barrier for low-cost spacecraft realization. Contrarily, ADCS, having only magnetorquers and magnetometers, can be low-cost due to their simple composition. Although the magnetic torque generated by magnetorquers is low, nadir-pointing control with magnetorquers can be performed using optimal control algorithm. A Kalman filter for a gyroless spacecraft is applied for attitude determination with a magnetometer. These systems are combined and can realize the pointing accuracy against nadir direction as well as gravity gradient stabilization. Theoretically, spacecraft attitude control with magnetic torque is a well-known singularity problem. Herein, PD control based on an attitude control algorithm, which includes a Singularity Robust (SR) inverse matrix, is proposed as a solution. A PD controller calculates the control torque against attitude error and then an SR inverse matrix is used for computing output magnetic moment. The role of SR inverse matrix is to avoid singularity of the pseudoinverse matrix. Optimal magnetic moment is given by measured magnetic-field value and reference control torque. This study considered two different types of magnetorquers: one with fixed output current and another with variable current. The maximum output is defined with an assumption that this system is used for micro satellites. A fixed output magnetorquer is controlled by a method that is similar to pulse-wid

关键词： Attitude Determination Control System Nadir Pointing Using Magnetorquer Position measurement control systems magnetometers Magnetic moment Star trackers THRUSTER computer algorithms Inverse matrix

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