199 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
- View/download PDF
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
- View/download PDF
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 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
20. 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
- View/download PDF
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