200 results
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2. Operational Demand Forecasting In District Heating Systems Using Ensembles Of Online Machine Learning Algorithms.
- Author
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Johansson, Christian, Bergkvist, Markus, Geysen, Davy, De Somer, Oscar, Lavesson, Niklas, and Vanhoudt, Dirk
- Abstract
Heat demand forecasting is in one form or another an integrated part of most optimisation solutions for district heating and cooling (DHC). Since DHC systems are demand driven, the ability to forecast this behaviour becomes an important part of most overall energy efficiency efforts. This paper presents the current status and results from extensive work in the development, implementation and operational service of online machine learning algorithms for demand forecasting. Recent results and experiences are compared to results predicted by previous work done by the authors. The prior work, based mainly on certain decision tree based regression algorithms, is expanded to include other forms of decision tree solutions as well as neural network based approaches. These algorithms are analysed both individually and combined in an ensemble solution. Furthermore, the paper also describes the practical implementation and commissioning of the system in two different operational settings where the data streams are analysed online in real-time. It is shown that the results are in line with expectations based on prior work, and mat the demand predictions have a robust behaviour within acceptable error margins. Applications of such predictions in relation to intelligent network controllers for district heating are explored and the initial results of such systems are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
3. Direct Torque Control Based Three Level Inverter-fed Double Star Permanent Magnet Synchronous Machine.
- Author
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Naas, Badreddine, Nezli, L., Naas, Bachir, Mahmoudi, M.O., and Elbar, M.
- Subjects
TORQUE ,ELECTRIC inverters ,ALGORITHMS ,PERMANENT magnets ,INDUSTRIAL applications ,SIMULATION methods & models - Abstract
Abstract: In this paper, direct torque control (DTC) algorithms for double star permanent magnet synchronous machine alimented by two inverters is described. The double star permanent magnet synchronous machine has two sets of three-phase stator windings spatially shifted up by an angle γ=30
0 . The double star permanent magnet synchronous is used in areas of high power industrial applications such as traction and naval propulsion. Because constitute an advantageous choice compared to classical synchronous machine, because of the relatively low torque produced. This machine is controlled by tree level direct torque with speed regulator PI, replaced by the sliding mode regulator to improve the results obtained. The implementation of the DTC multi-level applied to a double star permanent magnet synchronous machine is validated with simulated results. In this paper a method for modeling and simulation of double star permanent magnet synchronous motor drive MATLAB/Simulink. [Copyright &y& Elsevier]- Published
- 2012
- Full Text
- View/download PDF
4. Software Design of Dual CPU Controlled Digital Protection Device.
- Author
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Yang, Xiaohong, Xu, Yaoliang, Xia, Lei, Yang, Ning, and Zhang, Shaocheng
- Subjects
SOFTWARE architecture ,CENTRAL processing units ,MICROPROCESSORS ,ALGORITHMS ,ELECTRIC circuits ,COMPARATIVE studies - Abstract
Abstract: The requirements of device under the multi-mission of monitoring, protecting, controlling and communicating is discussed in this paper to bring forward a design of dual CPU structure with ARM & DSP for microprocessor protection. Via the comparative analysis of several common algorithms, the algorithm of FFT, which can make the controlling of calculation accuracy easier and has a filter feature inherently, is selected to analyze the sampling data of protector and calculates relative electrical parameters. Relevant program is written for distance protection in 110kV transmissions, then debugging on software and hardware is made. The results show that the design of DSP & ARM based-microprocessor protection presented in this paper is feasible; such a device has simple and reliable circuit structure and is expandable in both software and hardware. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
5. Research on Flow Diagram and Improved Algorithm Criteria of Control Mode Selection at Plane Intersection.
- Author
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He, Jian, Wu, Kehao, Du, Xiangru, Dai, Juanli, and Jin, Chunyu
- Subjects
ALGORITHMS ,INTERSECTION theory ,TRAFFIC flow ,ROAD visibility ,RELIABILITY in engineering ,QUANTUM groups - Abstract
Abstract: This paper modifies and improves the algorithm of sight distance triangle according to the traffic flow and geometric features of intersections. Using the modified crossable intervals and the traffic volume on the secondary road and the obstacles within the improved sight distance triangle as selection criteria, we put forward the control mode selection flow diagram of plane intersections in this paper, hoping to quantize the selection criteria, as well as normalize and visualize the selection process.Finally,this paper checks the accuracy and reliability of the model through the analysis of a case. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
6. Research on Harmonic Suppression in Power System Based on Improved Adaptive Filter.
- Author
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Zeng, Lingquan and Li, Xin
- Subjects
ELECTRIC power systems ,ADAPTIVE filters ,ALGORITHMS ,ELECTRIC potential ,HYSTERESIS ,SIMULATION methods & models - Abstract
Abstract: This paper described the structure of a Shunt Active Power Filter system and compared various methods of active power filter harmonic detection, then the improved adaptive algorithm was used in active power filter harmonic detection; as regards the control strategy, the control method that based on optimal voltage space vector hysteresis current was presented in this paper for tracking control, And by using Matlab/Simulink simulation software, the Adaptive filter detection system and control model of Three-phase three-wire Shunt Active Power Filter were established. Simulation results showed that the selected detection method and control strategy of harmonic current played a fairly good compensation role on the harmonics which was generated by nonlinear loads and had a good dynamic compensation performance. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
7. Electricity Load Profile Determination by using Fuzzy CMeans and Probability Neural Network.
- Author
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Anuar, Norhasnelly and Zakaria, Zuhaina
- Subjects
ELECTRICITY ,ARTIFICIAL neural networks ,FUZZY systems ,CLUSTER analysis (Statistics) ,ENERGY consumption ,POWER resources ,ALGORITHMS ,CONSUMERS - Abstract
Abstract: This paper shows the determination of typical load profiles (TLPs) by using Fuzzy C-Means (FCM) clustering and Probability Neural Network (PNN) classification method. Load profiles provide useful information on electricity consumption to both consumers and suppliers. Precise knowledge on consumer''s electricity consumption becomes essential for the suppliers to design tariffs, load balancing, load planning, etc. As for consumers, such knowledge is important for them to keep track of their electricity consumption and to enable them to take part in retail market especially for those who do not have appropriate metering equipment. Hence, an effective, fast and cheap method to obtain load profile has to be developed. Objectives of this paper are to obtain groups of TLPs by using FCM clustering and to assign TLPs using PNN algorithm. One of the main issues in FCM clustering is the determination of optimal number of cluster. This paper proposes optimal number of cluster determination by using Davies-Bouldin index. PNN network is trained to directly allocate the TLPs to the representative groups of consumers. The data used in this project are obtained from Tenaga Nasional Berhad (TNB). [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
8. Optimal Decentralized Load Frequency Control in a Parallel AC-DC Interconnected Power System Through HVDC Link Using PSO Algorithm.
- Author
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Selvakumaran, S., Parthasarathy, S., Karthigaivel, R., and Rajasekaran, V.
- Subjects
DIRECT currents ,INTERCONNECTED power systems ,PARTICLE swarm optimization ,ALGORITHMS ,PERFORMANCE evaluation ,PARAMETER estimation ,ELECTRIC controllers - Abstract
Abstract: A new design of decentralized load-frequency controller for interconnected power systems with ac-dc parallel using Particle Swarm Optimization (PSO) algorithm is proposed in this paper. A HVDC link is connected in parallel with an existing ac tie-line to stabilize the frequency oscillations of the ac system. Any optimum controller selected for load frequency control of interconnected power systems should not only stabilize the power system but also reduce the system frequency and tie line power oscillations and settling time of the output responses. In practice Load Frequency Control (LFC) systems use simple Proportional Integral (PI) or Integral (I) controller parameters are usually tuned based on classical or trial-and-error approaches, they are incapable of obtaining good dynamic performance for various load change scenarios in multi-area power system. For this reason, in this paper the PI and I control parameters are tuned based on PSO algorithm method for the LFC control in the two-area power system. A two area interconnected thermal power system is considered to demonstrate the validity of the proposed controller. The simulation results show that the proposed controller provides better dynamic responses with minimal frequency and tie-line power deviations, quick settling time and guarantees closed-loop stability margin. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
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9. Over-excitation Relaying for Digital Generator Protection using the 765 kV Power System Modeling Data in Korea.
- Author
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Won, Park Chul and Hyeon, Ban Woo
- Subjects
ELECTRIC generators ,AIR conditioning ,ALGORITHMS ,DENSITY functionals ,SIMULATION methods & models ,ELECTRONIC excitation ,ELECTRIC power ,MATHEMATICAL models - Abstract
Abstract: A large AC generator is an important component of the power system. Researches on the AC generator relaying for the next-generation ECMS and an efficient operation of protection control system are necessary. These require developments on detailed generator modeling and internal fault analysis, and prototyping for multifunctional IED device dedicated to next-generation production. In this paper, over-excitation relaying algorithm is one of the main protection elements which have an important role in DGPS(Digital Generator Protection System), was proposed. This paper first briefly introduces a principles of over-excitation and DFT-based gain compensation algorithm was adopted for the frequency measurement. Subsequently, protection scheme of over-excitation was presented. The 765[kV] modeling data of South Korea using EMTP-RV was used for simulations. The simulation result of over-excitation relaying are also provided. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
10. Modeling and testing of multi-resolution morphological gradient distance relay algorithm.
- Author
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Saad, A.A., El-Naggar, M.F., and Shehab_Eldin, E.H.
- Subjects
ALGORITHMS ,ELECTRIC lines ,COMPUTER software ,FAULT tolerance (Engineering) ,POWER system simulation ,COMPUTER networks - Abstract
Abstract: This paper describes modeling and testing of a digital distance relay for transmission line protection using MATLAB/SIMULINK. ATP is used for detailed modeling of a power system network and fault simulation. SIMULINK is used to implement multi-resolution morphological gradient (MMG) relaying algorithm. MMG modeling is an interactive simulation environment for relaying algorithm design and evaluation. The basic principles of MMG relaying algorithm and some related algorithms such as tripping and fault location scheme are also described in this paper. Test results show that MMG relaying algorithm can detect and define fault location accurately within 1 milli-second. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
11. Fast Algorithm Based on Projection and Normalized Cross Correlation for Embossing Flaws Detection.
- Author
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Kong, Honghong, Sun, Jian, Zhong, Shaojun, Xie, Min, and Fu, Yaqiong
- Subjects
ALGORITHMS ,CROSS correlation ,TEMPLATE matching (Digital image processing) ,INFORMATION technology ,MATHEMATICAL analysis ,FEATURE extraction - Abstract
Abstract: The detection system for frame embossing surface is discussed in this paper. According to the periodic feature of frame embossing surface, one periodic embossing is inspected once. Then a fast template matching algorithm based on projection and normalized cross correlation measure is proposed in this paper. The experimental results showed that the proposed algorithm was more efficient and faster than conventional image template matching algorithms. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
12. Compression Algorithm for Embedded Multimedia Instructions.
- Author
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Chen, Yuanzhi, Wang, Hongru, and Liu, Ruizhe
- Subjects
DATA compression ,ALGORITHMS ,EMBEDDED computer systems ,MULTIMEDIA systems ,EDUCATIONAL technology ,REMOTE control - Abstract
Abstract: Most of the current manual paper or electronic equipment production, but it will cause pollution of the environment .In this paper, the electronic multimedia device instructions are embedded into the processor module Flash to generate E-Manual which can be browsed in the display devices by the remote control. As Flash space provided by most of the multimedia processor module is very small, there is a high demanding for data compression. In this paper, compression problems of black and white pictures and other data embedding Flash are the main, we also do a detailed study to BI_RLE8, LZMA algorithm, and apply them to the set-top box platform that has good results. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
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13. Improved Technology of Surface-Surface Intersection Based on Delaunay Triangulation.
- Author
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Longbin, Shen and Jian, Chu
- Subjects
TRIANGULATION ,INTERSECTION theory ,ALGORITHMS ,SIMULATION methods & models ,WEIGHTED graphs ,SURFACE topography - Abstract
Abstract: This paper mainly focused on the surface-surface intersection problem in surface border modeling. This paper introduced the intersection testing algorithm to obtain the initial intersecting lines based on the Delaunay triangulation of two surfaces. After the detection of intersecting lines’ continuity, the “weighted surface border extension algorithm” was put forward to guarantee the continuity of intersecting lines. When the discrete data is deficiency, “weighted surface border extension algorithm” is applied to guarantee the existence of intersecting lines between the surfaces which have the tendency to intersect. This paper applied “weighted surface border extension algorithm” on the result of intersecting lines to guarantee that the endpoints of intersecting lines lie on the border of both surfaces, which can be convenient to the following Constrained Delaunay Triangulation and surface cutting steps. Simulation results showed the proposed algorithm was feasible. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
14. Calculation and Analysis of MTF of On-Orbit Satellite Images Based on Knife-Edge Method.
- Author
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Bu, Fan, Qiu, Yuehong, Qiao, Weidong, Yang, Jianfeng, and Yan, Xingtao
- Subjects
REMOTE-sensing images ,TRANSFER functions ,IMAGING systems ,ALGORITHMS ,LEAST squares ,PRECISION (Information retrieval) - Abstract
Abstract: Modulation transfer function (MTF) is more authoritative in evaluating the performance of optical imaging system. Therefore, measuring MTF directly from the information of remote sensing image is an important method to monitor on-orbit satellites. This paper chooses knife-method which is applicable for MTF measurement of on-orbit satellites. In the process of calculating MTF, a new-type nonlinear least squares iteration algorithm, instead of simulated annealing algorithm, is selected to approach ESF using the Fermi function. Simulation results show that the new algorithm has greater superiority in the precision and speed. Furthermore, on the basis of implementation of MTF measurement, this paper studies the influence of edge height, angle, and gray contrast on MTF, and tests the precision of the method. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
15. A Watermarking Algorithm for Remote Sensing Image based on DCT and Fractal.
- Author
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Li-li, Li and Jin-guang, Sun
- Subjects
DIGITAL watermarking ,ALGORITHMS ,REMOTE-sensing images ,DISCRETE cosine transforms ,FRACTALS ,COPYRIGHT - Abstract
Abstract: In this paper it proposes a meaningful digital watermarking algorithm for remote sensing image based on DCT and fractal theory. Firstly, it determines self-similar blocks for watermark embedding by using fractal technology, then scrambles the watermark with Arnold transformation and the scrambled watermark image next be scanned into onedimensional sequence, at last it applies DCT to the selected self-similar blocks and embedds the watermark into the blocks. Experiments have shown that the algorithm proposed in this paper has good invisibility, simple calculation, easy realization, and extracting watermark without the original remote sensing image. So it is robust against most geometric attacks and has some value for copyright protection of remote sensing images. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
16. Bidirectional Adaptations Workflow Management for the Route-choice Application.
- Author
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Yang, Lei and Cao, Yang
- Subjects
WORKFLOW ,ROUTE choice ,BIDIRECTIONAL associative memories (Computer science) ,ALGORITHMS ,INFORMATION processing ,MATHEMATICAL models - Abstract
Abstract: This paper tries to widen the notion of adaptation to take account of bidirectional adaptations between the context and activities so as to ensure not only the activity adaptation but also the adaptation of the context of the user to the requirements of the activities. What''s more, this paper presents a bidirectional adaptations workflow management algorithm (BAWM) for the route-choice of campus navigation, which can dynamically adjust workflow execution behaviors based on current context information and the user activities. This paper also manages to show that the correctness of the BAWM algorithm by formulating it as a Petri-net model. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
17. An Encryption Scheme of Smart Card Based on AES.
- Author
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Huang, He
- Subjects
DATA encryption ,SMART cards ,ADVANCED Encryption Standard ,ALGORITHMS ,PUBLIC key cryptography ,COMPUTER security - Abstract
Abstract: In order to improve the application security of smart card, this paper has proposed an encryption scheme of smart card combined with AES encryption algorithm and high-speed key generation algorithm. Furthermore, combined with the characteristics of M1 card, this paper has introduced the work of the program and implemented the program. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
18. An Ameliorated Algorithm of Spectral Recovery of Hadamard Transform Spectral Imager.
- Author
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Caifang, Liu, Bingliang, Hu, Liang, Kong, Qingming, Qian, and Peng, Yan
- Subjects
HADAMARD matrices ,ALGORITHMS ,RANDOM noise theory ,IMAGE quality analysis ,IMAGE color analysis ,MATHEMATICAL proofs - Abstract
Abstract: In order to make use of a great many blurred images captured by Hadamard Transform Spectral Imager(HTSI) in projects, an ameliorated algorithm of Spectral Recovery of Hadamard Transform(HT) has been proposed in this paper. The ameliorated algorithm has been deduced by bring the average of multiple images into the Adverse Hadamard Transform. The impact of this new method on Gaussian noise in images has been analyzed. The contribution of improving the quality of the false color image and added image has been proved and demonstrated in this paper. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
19. A kind of user behavior authentication model and analysis in cloud computing.
- Author
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Tian, Li-Qin, Lin, Chuang, Yang, Ni, and Duxiujuan
- Subjects
COMPUTER access control ,MATHEMATICAL models ,CLOUD computing ,COMPUTER security ,COMPUTER software ,ALGORITHMS ,INTERNET users ,PETRI nets - Abstract
Abstract: Currently, the cloud computing is welcome in scholars and enterprise, because of its good features such as low investment, easy maintenance, Flexibility and fast deployment, reliable service. However, when the cloud computing is implemented, the security and credibility is one of the biggest obstacles. In cloud computing, users directly use and operate software of cloud service providers, operating system, even programming environment and network infrastructure, so the impact and breakage users caused for cloud software and hardware resources more serious than the current Internet users to share resources. So whether the behavior and behavior subject is credible or not, how to authenticate and control user behavior, these are important parts of the cloud computing study. This paper presents the concept of user behavior authentication, discusses how to authenticate and control user behavior in the cloud computing environment according to the user''s behavior, include establishment of behavior authentication set, mechanisms of behavior authentication and control, corresponding mode of Stochastic Petri Nets, False Negative rates and algorithm performance etc. Paper lays the theoretical and practical foundation for the real application of cloud computing. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
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20. A New Framework for Fine Granularity Scalability Video Coding in AVS.
- Author
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Wang, Kunpeng, Zhao, Yong, Yuan, Yule, Bai, Xuhui, and Fang, Wei
- Subjects
SCALABILITY ,COMPUTER networks ,VIDEO coding ,MPEG (Video coding standard) ,AVATARS (Virtual reality) ,ALGORITHMS ,COMPUTER software - Abstract
Abstract: Fine scalable video coding is a common method for video quality scalable of H264 and MPEG-4, but it has not been used on AVS as yet. This paper presents a new algorithm of fine granularity scalability based on AVS. The DCT residue coefficients of the FGS enhancement layer proposed in this paper are firstly scanned by zigzag and then scaled with the energy distribution characteristic of frequency domain. Then, the scalable coefficients are coded by bit-plane coding and Exp-Golomb coding. Finally, we simulate the algorithm on the software codec model version rm52k of AVS-P2. The experimental results show that the ameliorated scalable coding method can improve the coding efficiency obviously compared with the original FGS in terms of average PSNR. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
21. A Novel Text Clustering Algorithm.
- Author
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Li, Cui-xia and Lin, Nan
- Subjects
K-means clustering ,ALGORITHMS ,ITERATIVE methods (Mathematics) ,COMPUTER simulation ,FUZZY logic ,PROBLEM solving - Abstract
Abstract: The partitional clustering algorithms are used more widely in text clustering. However, the traditional algorithms based on partition treat all the attributes equally in clustering process. They all suppose that the importance of each attribute is equal. These algorithms will have a lower accuracy. In order to handle this problem, this paper provides a new clustering algorithm-attribute weighted fuzzy c-means algorithm. During the iteration of this algorithm, it can find the important attributes. Moreover, this algorithm also can find the cluster structure hiding by the unimportant attributes. The simulation of this algorithm on test documents can prove the algorithm provided by this paper can gain a good computation speed, found the latent structure and can remark the different importance of each attribute. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
22. Moving Vehicle Detection in Dynamic Background from Airborne Monocular Camera.
- Author
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Li, Jing, Ai, Hong, and Cui, Jianzhu
- Subjects
EDGE detection (Image processing) ,IMAGE converters ,DIGITAL image processing ,BINARY large objects ,MONOCULARS ,CAMERAS ,AUTOMATIC vehicle location systems ,ALGORITHMS - Abstract
Abstract: Aerial imagery sensors can provide sufficient resolution to sense vehicle locations and movements across broader spatial and temporal scales. In this paper, an approach for collecting and analyzing aerial imagery is given. This paper presents a method to detect vehicle from a moving camera. The detection component involves a cascade of modules. First, road is detected based on edge detection and blob analysis, then our proposed motion detection (simplified Lucas-Kanade algorithm) is used to obtain motion vectors from two consecutive input frames. Third, frame differencing method based on obtained motion vectors is applied to generate differenced image. At last, moving vehicles are detected based on blob analysis. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
23. Prediction Algorithm of Terrorist Behavior Based on Bayesian Theorem.
- Author
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Xue, Anrong and Wang, Wei
- Subjects
PREDICTION theory ,ALGORITHMS ,TERRORISTS -- Psychology ,BAYES' theorem ,PROBABILITY theory ,PERFORMANCE evaluation - Abstract
Abstract: The algorithm based on context similarity has the drawback that it will cost more time if not all the attributes are detected, this paper views the context attributes as attribute stream and the BOAS (Bayesian on the Attributes Stream) algorithm based on context knowledge is proposed in this paper. BOAS algorithm firstly calculates the undetected attribute of terrorism group identifier, and then uses conditional probability and Bayesian theorem to predict the future terrorist behavior. In this way, it avoids handling the undetected attributes in the original algorithm, but also avoids computing the context similarity based on distance function repeatedly. Thus, it improves the performance efficiency. The experiment result shows that BOAS algorithm proposed in this paper reduces computation time while it assures the accuracy of the prediction. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
24. Ear Recognition based on Gabor Features.
- Author
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Yuan, Li, Mu, Zhichun, and Zeng, Hui
- Subjects
GABOR transforms ,FEATURE extraction ,DIGITAL image processing ,ALGORITHMS ,MATHEMATICAL models ,DISCRIMINANT analysis ,KERNEL functions - Abstract
Abstract: In this paper, we propose an ear recognition system based on 2D ear images which includes three stages: ear enrollment, feature extraction and ear recognition. Ear enrollment includes ear detection and ear normalization. The ear detection approach based on Gentle Adaboost algorithm detects the ear part under complex background using two steps: off-line cascaded classifier training and on-line ear detection. Then Active Shape Model is applied to segment the ear part and normalize all the ear images to the same size. For its eminent characteristics in spatial local feature exaction and orientation selection, Gabor-based ear is presented in this paper. Kernel Fisher Discriminant Analysis is applied for dimension reduction of the high-dimensional Gabor features. Then distance based classifier is applied for ear recognition. The experimental results on USTB ear database show effectiveness of the proposed approach. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
25. Generalization Bounds for Ordinal Regression Algorithms via Strong and Weak Stability.
- Author
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Xu, Tianwei, Zhang, Yungang, and Gao, Wei
- Subjects
GENERALIZATION ,MATHEMATICAL bounds ,REGRESSION analysis ,ALGORITHMS ,STABILITY theory ,INTEGERS ,TOPOLOGICAL spaces - Abstract
Abstract: Ordinal regression shares properties of both classification and regression, since the goal function maps the instance space into the integer set. In this paper, we studied generalization properties of ordinal regression algorithms, and we focused on the performance of goal function effecting on individual examples. The strong (weak) loss stabilities and strong (weak) score stabilities for standard regression algorithms we defined only consider changing one element of training set. With the definitions of stabilities for ordinal regression algorithms and the clipped loss function, four kinds of generalization bounds are given in this paper. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
26. Online Reputation Scoring from Historical Feedbacks Based on Partially-Ordered Similarity.
- Author
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Tang, Yin
- Subjects
ONLINE data processing ,STATISTICAL smoothing ,STABILITY theory ,PATTERN recognition systems ,FEEDBACK control systems ,ALGORITHMS - Abstract
Abstract: Online reputation evaluation has been implemented in many practices in different ways. Based on the evaluation of several reputation mechanisms, this paper proposes a reputation evaluation for scoring and monitoring the seller''s behavior. Second-order atomic patterns are defined, based on which we propose an algorithm named Partially- Ordered Pattern Scoring (POPS). A solution for reputation monitoring is discussed. This mechanism helps to prevent several cheating strategies. At the end of the paper, comparative experiments on accuracy with Double Exponential Smoothing and on stability with different lengths of cases have shown its advantages. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
27. Implementation of String Match Algorithm BMH on GPU Using CUDA.
- Author
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Zhou, Junrui, An, Hong, Li, Xiaomei, Xu, Min, and Zhou, Wei
- Subjects
STRING theory ,ALGORITHMS ,GRAPHICS processing units ,MULTIPROCESSORS ,MATHEMATICAL optimization ,PARALLEL programs (Computer programs) - Abstract
Abstract: String match algorithm is widely used in the area of data mining. In this paper, we present an approach for elevating the performance of this algorithm via GPU (Graphic Processing Unit). With the rapid development of Graphics Processing Unit to many-core multiprocessors, it shows great potential in many applications and high performance computing. Especially, the heterogeneous architecture CPU+GPU shows enthusiastic capacity to accelerate parallel applications. Till now, some research has been done for parallel implementation of string match algorithm on GPU. But there are some constraints for acceleration of this algorithm: firstly, if-branch exists in the algorithm which can cripple the performance of the parallel implementation; secondly, improper memory access may bring heavy latency generated by bank-conflict. This paper presents the optimization of global memory access, shared memory access and the elimination of if-branch for elevating the performance of string match algorithm BMH. Meanwhile, we explore the interesting characteristics of the parallel BMH string match algorithm implemented on GPU using CUDA. We found that the performance elevation is affected by the characteristic of pattern, which also proves the potential of GPU. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
28. Semantics and Relativity Expansion Based on Tag Recommendation with Time Degradation.
- Author
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Xiao, Jie and He, Liang
- Subjects
INTERNET ,TECHNOLOGICAL innovations ,SEMANTICS ,ALGORITHMS ,PROBLEM solving ,SCIENTIFIC observation - Abstract
Abstract: With the rapid development of the Intemet, information overload and isotropic becomes worse and worse. Personalized services system''s birth partly resolved this problem. The traditional recommendation methods, such as content based recommendation and collaborative filtering, do help a lot. However, to some extent, it couldn’t authentically understand the preference of users. Considered the limitations of the traditional methods, tag recommedation spring up. This paper makes expanded research based on tag reccommendation. With semantic matching, a certain tag turns to a similar tag set. Acording to co-occurence of tags, a tag is expended to a ralated tag set. Integrate these tag set to generate recommendation list is better than single tag recomendation by experimental observation. Besides, this paper also adopt time degradatioin aglorithm which improved the recommender''s accuracy and efficiency. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
29. Semi-supervised Cluster Ensemble Based on Normal Mutual Information.
- Author
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Wang, Hongjun, Yang, Dezhi, and Qi, Jianhuai
- Subjects
SUPERVISED learning ,CLUSTER analysis (Statistics) ,ALGORITHMS ,GENERALIZATION ,ROBUST control ,AUTOMATIC control systems - Abstract
Abstract: Semi-supervised cluster ensemble combines semi- supervised learning and cluster ensemble to increase the precision of clustering. And it conquers the disadvantages of the selectivity, bias, low precision and bad generalization. And conquers that unsupervised learning can’t take advantages of known information of datasets. As a result the precision, robustness and stability of cluster ensemble are increasing. Now semisupervised cluster ensemble is researched at the very outset. The paper''s main goal is to construct an algorithm of semi-supervised cluster ensemble. In this paper it includes as follows. First the advantages of semisupervised cluster ensemble are stated; Second the algorithm of semi-supervised cluster ensemble is established; Third the experiments of semi- supervised cluster ensemble, such as the results,the datasets, the types and the steps of experiments, are studied. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
30. Optimization of Rotor Speed Variations in Microturbines.
- Author
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Keshtkar, H., Alimardani, A., and Abdi, Babak
- Subjects
ROTORS ,SPEED ,MICROSTRUCTURE ,TURBINES ,MATHEMATICAL optimization ,DISTRIBUTED power generation ,SMART power grids ,ALGORITHMS - Abstract
Abstract: Distributed Generation (DG), and especially microturbine generation (MTG) system, plays a significant role in Smart Grids. One of the most important variables of a MTG system is the governer speed. This paper defines a problem on transient speed response of MTs for a step load. The aim is to optimize the speed governer parameters in order to minimize the transient response of MTG. Differential Evolutionary Algorithm (DEA) is employed to solve the problem. The stability issue of the MTG system is also discussed in the paper. The simulation results show the effectiveness of a fine-tuned speed governer by using the proposed method. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
31. Optimization of Fuel Consumption in Micro-Turbines.
- Author
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Alimardani, A., Keshtkar, H., and Abdi, Babak
- Subjects
ENERGY consumption ,TURBINES ,MICROSTRUCTURE ,DISTRIBUTED power generation ,SMART power grids ,ALGORITHMS ,MATHEMATICAL optimization - Abstract
Abstract: Distributed generation (DG), and especially microturbine generation (MTG) system, plays a significant role in Smart Grids. One of the most important variables of a MTG system is the fuel consumption. This paper defines a problem on fuel consumption of MTs for a sample load change that can be used for a 24-hour load change pattern. The aim is to optimize the speed governer parameters in order to minimize the fuel consumption of MTG. Differential Evolutionary Algorithm (DEA) is employed to solve the problem. The stability issue of the MTG system is also discussed in the paper. The simulation results show the effectiveness of a fine-tuned speed governer by using the proposed method. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
32. The Study of Fast Optimal Generator Shedding Based on Predictor-Corrector Method.
- Author
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Wang, Biao and Wang, Zhenghong
- Subjects
ELECTRIC generators ,ALGORITHMS ,SIMULATION methods & models ,ELECTRIC impedance ,CONTROL theory (Engineering) ,ELECTRIC power consumption - Abstract
Abstract: This paper presents a fast optimal generator shedding algorithm which is on the basis of predictor-corrector method and time domain simulation for transient stability. It includes two parts that are the fast time domain simulation and optimal generator shedding. On the basis of the generator''s classical model and load''s constant impedance model, this paper use fourth-order Hamming predictor-correction formula to compute differential equations of the system with large step length, in order to improve computing speed. The second part shows how to calculate the sensitivity of transient stability constraint function to control variables, by the application of optimal control theory. Combined with the discrete characteristics of generator shedding, “Micro-step discrete method” is proposed, which is fast, accurate and so on. The advantages of this method are verified by analysis results of New England 39-bus test system. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
33. Simulation and Control Strategy of a Micro-Turbine Generation System for Grid Connected and Islanding Operations.
- Author
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Guo, Xian and Guo, He
- Subjects
SIMULATION methods & models ,FEASIBILITY studies ,MICROSTRUCTURE ,ELECTRIC current rectifiers ,ELECTRIC inverters ,ELECTRIC circuits ,ALGORITHMS - Abstract
Abstract: The paper adopts the method of modularized modeling, creating an electro-mechanic simulation model for a Microturbine Generation System (MTGS), including the micro-turbine engine, permanent magnetic synchronous generator, rectifier and inverter. In this paper, control strategy for grid-connected and islanding operations of a micro-turbine generation system is researched, the former adopts output voltage control strategy to maintain the output voltage of the load, and the latter adopts a dual closed-loop control algorithm based on PQ decoupling. A new control strategy to regulate the output power of MTGS based on the combination of decoupled control of output voltage and hysteresis current control is also introduced. Simulations have been done, and result proves the feasibility of the strategy. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
34. Improved Mono-Window Algorithm to Retrieve Lake Surface Temperature Using HJ-IRS Thermal Infrared Data.
- Author
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Shanshan, Liang, Bing, Zhang, Junsheng, Li, Hao, Zhang, and Qian, Shen
- Subjects
ALGORITHMS ,OPTICS ,WATER temperature ,ARTIFICIAL satellites ,INFRARED radiation ,WATERSHEDS ,INFRARED imaging ,MICROSPACECRAFT - Abstract
Abstract: Remote sensing data has an important application value and scientific significance .in retrieval of lake surface temperature (LST). On September 6, 2008, China successfully launched two optical small satellites (respectively called HJ-1A, HJ-1B.) to monitor and predicate environment and disaster. HJ-1B satellite includes an infrared camera (IRS). The camera has a thermal infrared band which can dynamically monitor LST of large river basins in 4 days. HJ-IRS is a new sensor, so there are few papers researching on the retrieval of LST.The main goal of this paper is to introduce a practical method to obtain LST from HJ-IRS thermal data. In this paper, we reviewed primary algorithms of LST retrieval and mainly analyzed Qin′s mono-window algorithm retrieving LST from Landsat TM6 (Thematic Mapper) thermal data. This algorithm included two empirical relationships about atmospheric transmittance and atmospheric average temperature. But these relationships are only suitable for TM6. So on the basis of the spectral response function of HJ-IRS therma1 band we use radiance transfer software MODTRAN4 to simulate and calculate new coefficients in the two relationships. New algorithm requires three parameters: emissivity, vertical water vapor column and atmospheric temperature about 2 meters above the ground. We use two images of Lake Taihu to retrieve LST and validate the improved algorithm. Bias of LST retrieved from HJ-IRS data and the field measurements are smaller than 1.2K, which means this algorithm is applicable for HJ-IRS therma1 band to retrieve LST. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
35. Chaos Immune Optimization Algorithm in Distribution Service Restoration after Faults.
- Author
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Lei, Shaolan, Yang, Jing, Yang, Jia, Jiang, Dongrong, and Li, Shan
- Subjects
DISTRIBUTION (Probability theory) ,CHAOS theory ,MATHEMATICAL optimization ,ALGORITHMS ,AUTOMATION ,STOCHASTIC convergence ,PRECISION (Information retrieval) - Abstract
Abstract: Chaos immune optimization algorithm on distribution service restoration after faults is presented to improve the probability for optimal solution in this paper, which is integrated the characteristic of chaotic optimization with artificial immunity algorithm. In the proposed algorithm, excellent global search ability of chaotic optimization is regarded as “thick search” to initialize the antibody of immune algorithm, and local search of artificial immune algorithm is applied to replace “thin search” in the chaotic optimization, which assures the population diversity and avoids getting to stuck in local minima to a certain degree. A living example for a certain district distribution in Chongqing is analyzed by the method presented in this paper. The result shows that chaos immune optimization algorithm in the paper might improve convergence speed and precision of restoration and avoid premature convergence. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
36. Analytic Criterion and Algorithm for the Lowest Common Ancestor of Two Neighboring Nodes in a Complete Binary Tree.
- Author
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Xingbo, Wang and Jun, Zhou
- Subjects
GRAPH theory ,COMPUTER science ,COMPUTER programming ,ALGORITHMS ,C (Computer program language) ,CRITERION (Theory of knowledge) - Abstract
Abstract: Finding the lowest common ancestor (LCA) of two nodes in a binary tree has been focused both in graph theory and computer science. The paper puts forward and proves an analytic criterion for the LCA of two neighboring nodes in a complete binary tree. The criterion mainly concerns addition, subtraction and bitwise operations, needs no searching procedures and thus is easy to implement in software programming as well as hardware programming. An algorithm that has logarithmic time complexity is also presented with C-language implementation in the paper. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
37. New coupled models for transient pressure analysis in low permeability reservoirs.
- Author
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Liang, Huang and Shiqing, Cheng
- Subjects
RESERVOIRS ,PERMEABILITY ,NONLINEAR systems ,ITERATIVE methods (Mathematics) ,ALGORITHMS ,DARCY'S law - Abstract
Abstract: It is shown that the flow in the low permeability medium is nonlinear, which is quite different from the general Darcy flow. In this paper, we first present a survey of methods that has been used to analyze the low permeability well problems for the past 10 years, then we present two new coupled models that behaves better in complex situations. We assume that there are two different zones near the wellbore and the flow characteristics in the inner zone is different from that in the outer zone, and there is an connecting interface between them, as mentioned before, we called them coupled models. In this paper, we also give four different types of the typical curves for four different models and use the methods of alternating iteration algorithm to solve the nonlinear differential equation system. These four different types of the curves will cover the typical problems that will possibly be encountered when exploring the low permeability reservoirs. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
38. An Empirical Analysis for the Dynamic Relationship between China's Energy Consumption and Economic Growth--Based on Cointegration Analysis and State-Space Model.
- Author
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Ying, Ma, bin, Wang, and Long, Xue
- Subjects
ENERGY consumption ,ECONOMIC development ,MATHEMATICAL models ,EMPIRICAL research ,COINTEGRATION ,KALMAN filtering ,ALGORITHMS - Abstract
Abstract: Distinguished from former literature which focuses on the static or balanced analysis, this paper established the timevarying parameters model based on state space model to find the dynamic relationship between China''s energy consumption and economic growth. After applying Chow test, unit root test and cointegration test, this paper estimated the parameters of state space model with Kalman Filter Algorithm, then found and analyzed their internal regularity. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
39. Simulation of Annual Energy Saving Benefit of Solar Collector.
- Author
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Xuan, Wang, Min, Wang, Tao, He, Ruicheng, Zheng, Zhong, Li, Xinyu, Zhang, and Airong, Feng
- Subjects
SOLAR collectors ,SOLAR energy ,COMPUTER simulation ,ENERGY consumption ,HOT water ,TANKS ,ENERGY conservation ,ALGORITHMS - Abstract
Abstract: The paper introduced design flow chart and algorithm. By inputting solar hot water load, meteorology, solar fraction, system type, water tank volume etc., the software calculated the system annual energy saving benefit, the result was compared with Polysun software and analyzed. According to recent years’ testing date of National Center for Quality Supervision and Testing of Solar Heating System (Beijing), more than one hundred collectors were simulated to promote the solar collector energy efficiency certification. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
40. Development of the Prototype IP-Solar: A Web-based Monitoring and Diagnostics Tool for Solar Thermal Systems.
- Author
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Holter, Christian, Gerardts, Bernhard, Ohnewein, Philip, Dröscher, Angela, Feichtner, Franz, Schgaguler, Klaus, Meißner, Ernst, Luidolt, Peter, Köstinger, Alice, Heimrath, Richard, and Streicher, Wolfgang
- Subjects
SOLAR thermal energy ,PROTOTYPES ,MARKET segmentation ,COMPARATIVE studies ,FAULT location (Engineering) ,PERFORMANCE evaluation ,ALGORITHMS - Abstract
Abstract: Large solar thermal systems (LSTS) are a promising market segment for solar energy. However, the realization of LSTS is more challenging compared to smaller plants, in both technical and economical terms. Permanent monitoring, data evaluation and fault detection during the operation of LSTS has shown by Fink et al. [3] and Peuser et al. [13] to be crucial for ensuring optimal performance. The only cost-effective way for permanent surveillance of LSTS operation is to make use of a computer-aided tool that performs as many steps as possible in an automated mode. The R&D project ‘IP-Solar’ developed the scientific basis and the technical fundamentals for such a system. This paper presents the current state of development emphasizing the methodology of the operation diagnostics. In particular, the algorithm-based approach, its implementation and testing are described in detail. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
41. Use of LiFePO4 Batteries in Stand-Alone Solar System.
- Author
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Wang, Xingchi, Adelmann, Peter, and Reindl, Thomas
- Subjects
LITHIUM-ion batteries ,PHOTOVOLTAIC power generation ,ELECTRIC potential ,LITHIUM cells testing ,ALGORITHMS ,COST effectiveness - Abstract
Abstract: In this paper the use of lithium iron phosphate (LiFePO4) batteries for stand-alone photovoltaic (PV) applications is discussed. The advantages of these batteries are that they are environment-friendly, provide high safety, show long cycle life and hence relatively low lifetime costs. Different characteristics of batteries from various manufacturers have been studied in several battery testing experiments. Among the investigated properties are the relations of capacity, state of charge (SOC) and end-of-charge voltage as well as different charge-discharge durations. Differences between the capacities specified by manufacturers and the ones actually reached in experiments are reported. The tests show that LiFePO4 batteries are an ideal choice for stand-alone PV systems due to their high efficiencies and long cycle life, provided that they are operated with a charge control algorithm specifically targeted for long charge durations as they are typical in solar PV applications. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
42. Sensor Movement Correction for Direct Turbulence Measurements in the Marine Atmospheric Boundary Layer.
- Author
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Flügge, Martin, Edson, James B., and Reuder, Joachim
- Subjects
TURBULENCE ,ATMOSPHERIC boundary layer ,MARINE ecology ,WIND turbines ,MECHANICAL loads ,ALGORITHMS - Abstract
Abstract: Understanding of the turbulent exchange processes between the ocean and the overlying atmosphere is essential for wind shear and turbulence structure of the Marine Atmospheric Boundary Layer (MABL). This is highly relevant for the development of offshore wind projects with respect to the expected power output and acceptable structural loads and fatigue of turbines. This paper presents preliminary results from a recent field experiment off the coast of Martha''s Vineyard, Massachusetts. Turbulent fluxes have been measured from both a discus buoy and the Air Sea Interaction Tower (ASIT). Using the correction algorithm of Edson et al. (1998) the buoy data are corrected and compared with the ASIT measurements. The comparison shows that the corrected fluxes measured from the mooring are in good agreement with measured fluxes from the tower and that the direct covariance flux method is applicable for offshore turbulent flux measurements. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
43. Modeling and Control of Multi-Terminal VSC HVDC Systems.
- Author
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Beerten, Jef and Belmans, Ronnie
- Subjects
HIGH-voltage direct current converters ,CONTROL theory (Engineering) ,MATHEMATICAL models ,SIMULATION methods & models ,VOLTAGE regulators ,ALGORITHMS - Abstract
Abstract: This paper discusses the modeling and control of Voltage Source Converter High Voltage Direct Current (VSC HVDC) systems in a multi-terminal configuration (MTDC). Both steady-state interactions, as well as transient stability modeling and control are addressed. Simulation results show that adequately modelling the DC voltage droop characteristics or a distributed voltage control in both the power flow algorithm and in the transient stability models allows to simulate the steady-state results of the dynamic simulation by means of power flow software algorithms. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
44. Effect of Chemical Heterogeneity on Linear Adsorbed Solute Dispersion in fixed Bed.
- Author
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Kaabeche-Djerafi, K., Semra, S., and Bendjaballah-Lalaoui, N.
- Subjects
FIXED bed reactors ,DISPERSION (Chemistry) ,PARTIAL differential equations ,FINITE volume method ,ALGORITHMS ,HYDRODYNAMICS - Abstract
Abstract: The paper aims at investigating the importance of including chemical heterogeneity in fixed bed as it has been found to induce additional dispersion. A discrete chemical heterogeneity distribution has been considered in the one-dimensional advective-dispersive equation. The partial differential equation was solved using finite volumes method based on the Adam-Bashforth algorithm. Increased dispersion was estimated comparing breakthrough curves second order moments keeping identical hydrodynamic properties as well as medium global capacity. In the objective to prove the presence of chemical heterogeneity effect, we study in the first the transport in homogeneous and chemically heterogeneous medium without hydrodynamic dispersion. Then effect of medium capacity on linear adsorbed solute dispersion into chemically heterogeneous at constant bed length and at the same chemical heterogeneity distribution was investigated. After that, different distributions were considered at different bed lengths too. Effect of chemical heterogeneity was found has nonregular behavior with the medium size but depending on the distribution type though a constant mean value of the distribution. As a result, dispersion increase due to chemical heterogeneity witch depends essentially on the column size and on the nature of heterogeneity distribution causing dependence of the breakpoint time on both. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
45. Separate Powers Control Structure of Doubly Fed Induction Machine Based on Fractional Regulator.
- Author
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Ghoudelbourk, S., Bahi, T., Soufi, Y., and Lekhchine, S.
- Subjects
INDUCTION machinery ,ELECTRIC machinery ,ALGORITHMS ,ENERGY conversion ,ELECTRIC power ,PERFORMANCE evaluation - Abstract
Abstract: This paper shows that we can improve the performance of the auto-adjustable electric machines if a fractional dynamic is considered in the algorithm of the controlling order. This structure is particularly interested in the separate control of active and reactive power of the double-fed induction generator (DFIG) of wind power conversion chain. Fractional regulators are used in the regulation of chain of powers. Knowing that, usually, the source of DFIG is provided by converters through controlled rectifiers, all this system makes the currents of lines strongly polluted that can have a harmful effect for the connected loads and sensitive equipment nearby. The solution to remedy these problems is to replace the power of the rotor DFIG by a matrix converter which represents a THD less important. The structure of the adopted adjustment is tested using Matlab/Simulink and the results are presented and analyzed for a variable wind. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
46. Algorithm Research and Implementation of Power Quality Parameters Analysis.
- Author
-
Hui-juan, Zhang, Jun-jie, Han, Xiao-zhi, Gao, and Yan-ting, Wang
- Subjects
POWER electronics ,ALGORITHMS ,NONLINEAR theories ,ELECTRIC power systems ,ELECTRIC distortion ,ELECTRICAL harmonics ,NEWTON-Raphson method - Abstract
Abstract: In recent years, with the extensive application of power electronics technology, power electronic devices such as non-linear loads is used more and more in power systems, which is inevitable that related current and voltage waveforms have a greater degree of distortion, thus affecting the power quality. It created a greater impact on power system security and the economy. Therefore, Researching on harmonic voltage and current the impact of power quality has a strong practical significance. In order to achieve the analysis of power quality parameters, you need to combine harmonic analysis algorithms and power quality parameter calculation algorithms to achieve the intended purpose. This paper presents Newton''s algorithm for harmonic analysis, combined with power parameter calculation algorithm, achieved the power quality analysis purposes. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
47. An Improved Fourier Frequency Measurement Algorithm Based on Error Compensation.
- Author
-
Zhang, Jun and Cai, Xu
- Subjects
FREQUENCIES of oscillating systems measurement ,ALGORITHMS ,ELECTRIC power systems ,EMPIRICAL research ,ARC suppression ,SIMULATION methods & models ,LEAST squares - Abstract
Abstract: Frequency is an important parameter of a power system, and frequency measurement is a very important link in a power system measurement device. This paper compared the accuracy of the Fourier frequency measurement algorithm with different sampling period, chose the method of whole cycle to improve. Calculated based on the empirical model and used the least error squares fitting the error compensation curve to correct the result and get a new algorithm in frequency measurement which is convenient in calculation, high precision and real-time because it need only 2 sampling cycle and does not increase the complexity. The simulation results show the frequency value measured by improved algorithm is highly accurate and can be applied in a quick arc-suppressing system. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
48. Model Free Adaptive Predictive Control for Main Stream Pressure System of Power Plant.
- Author
-
Yu-chang, Feng and Dong-lin, Shi
- Subjects
ADAPTIVE control systems ,PREDICTIVE control systems ,POWER plants ,PID controllers ,ALGORITHMS ,CASCADE control - Abstract
Abstract: This paper is concerned with an improved model free adaptive predictive control (MFAPC) schemer. The controlled system is linearized dynamically to build a predictive model by using the notion of pseudo-partial-derivative. The new control method is applied to the main steam pressure cascade control system, which is a typical controlled process with large time constant and large time-delay parameters in a thermal power plant. The main control loop is implemented by the MFAPC algorithm and the inner control loop is implemented by a conventional PID controller. Simulation results have convinced that the MFAPC-PI cascade control method has good adaptability to overcome disturbances and track point. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
49. HVDC Intelligent Controller.
- Author
-
Lan, Hua, Yuan, Tian-gang, Zhang, Mu-Zi, and Liao, Zhi-min
- Subjects
INTELLIGENT control systems ,HIGH-voltage direct current converters ,ELECTRIC controllers ,ELECTRIC power transmission ,PID controllers ,ALGORITHMS ,SIMULATION methods & models ,FUZZY systems - Abstract
Abstract: The Purposes of this paper describes Gezhouba to Nanqiao rectifier direct current transmission project PI controller, through the intelligent control theory and the combination of the traditional PI controller are intelligent controller—HVDC fuzzy-PI controller, using the improved genetic algorithm domain Fuzzy- PI controller''s language of control theory. The result of improved intelligent controller has a simple structure, fast response characteristics. Using MATLAB / SIULIKMN the fuzzy toolbox and genetic algorithm toolbox for system simulation, simulation results show that the Conclusions of the intelligent controller has better adaptability and dynamic features to improve the robustness of the system and transient stability for the intelligent control of high voltage DC reference [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
50. A New Fault Diagnosis Method Based on Fault Tree and Bayesian Networks.
- Author
-
Duan, Rong-xing and Zhou, Hui-lin
- Subjects
FAULT-tolerant computing ,BAYESIAN analysis ,DECISION making ,MATHEMATICAL mappings ,SET theory ,DECISION trees ,ALGORITHMS - Abstract
Abstract: This paper presents a novel method for diagnosing faults using fault tree analysis and Bayesian networks (BN) to optimize system diagnosis. All minimal cut sets were generated via qualitative analysis of fault tree using an efficient zero-suppressed binary decision diagram (ZBDD), while the diagnostic importance factor (DIF) of components and minimal cut sets were calculated by mapping fault tree into equivalent BN. Also, these analysis results such as minimal cut sets and DIF were updated after receiving the evidence data from sensors and used to develop an efficient diagnostic decision algorithm. Furthermore, a diagnostic decision tree (DDT) was generated to guide the maintenance personnel to repair the system. Finally, a real example is given to demonstrate the efficiency of this method. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
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