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Co-regulated gene module detection for time series gene expression data
Wanwan TANG, Rui LI, Shao LI, Yanda LI
Front Elect Electr Eng. 2012, 7 (4): 357-366.
https://doi.org/10.1007/s11460-012-0207-x
It is important to detect interaction effect of multiple genes during certain biological process. In this paper, we proposed, from systems biology perspective, the concept of co-regulated gene module, which consists of genes that are regulated by the same regulator(s). Given a time series gene expression data, a hidden Markov model-based Bayesian model was developed to calculate the likelihood of the observed data, assuming the co-regulated gene modules are known. We further developed a Gibbs sampling strategy that is integrated with reversible jump Markov chain Monte Carlo to obtain the posterior probabilities of the co-regulated gene modules. Simulation study validated the proposed method. When compared with two existing methods, the proposed approach significantly outperformed the conventional methods.
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Experimental investigation on frequency-dependent critical current of HTS tapes
Changhui DAI, Yinshun WANG, Xiaojie ZHANG, Weijie ZHAO, Xiao LI
Front Elect Electr Eng. 2012, 7 (4): 386-390.
https://doi.org/10.1007/s11460-012-0209-8
Based on characteristics of alternating current (AC) critical current of high temperature superconducting (HTS) tapes on the frequency, this paper focuses on AC voltage-current (U-I) behaviors of two kinds of high temperature superconducting tapes, by which BSCCO and YBCO carrying different frequency AC currents are tested in liquid nitrogen temperature of 77 K. It is shown that the AC U-I characteristic curves of different tapes consist of two parts, that is, the resistive part and the hysteresis part. Additionally, the n values of the two parts and the relationship between AC critical current and frequency are obtained through experiments. The experimental results agree with calculated ones well, which is useful for the application of HTS tapes to power technology.
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The fusion of classifier outputs to improve partial discharge classification
R. AMBIKAIRAJAH, B. T. PHUNG, J. RAVISHANKAR
Front Elect Electr Eng. 2012, 7 (4): 391-398.
https://doi.org/10.1007/s11460-012-0208-9
The detection of partial discharge signals and classifying its patterns is an area of interest in the analysis of defects in high voltage cables. This paper investigates a filter-bank based approach to extract frequency domain based features to represent partial discharge signals. By applying the fast Fourier transform, the sampled partial discharge data are mapped into equivalent discrete frequency bins, which are then grouped into N equal sub-bands and also octave sub-bands, each providing N-dimensional features for partial discharge pattern classification. Two classifiers, namely, the support vector machine and the sparse representation classifier, are implemented and their outputs are fused, in order to improve the accuracy of classifying partial discharge. Classification accuracy is also compared with wavelet domain based octave frequency sub-band features.
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Multi-objective allocation of measuring system based on binary particle swarm optimization
Khalil Gorgani FIROUZJAH, Abdolreza SHEIKHOLESLAMI, Taghi BARFOROUSHI
Front Elect Electr Eng. 2012, 7 (4): 399-415.
https://doi.org/10.1007/s11460-012-0213-z
Due to the size and complexity of power network and the cost of monitoring and telecommunication equipment, it is unfeasible to monitor the whole system variables. All system analyzers use voltages and currents of the network. Thus, monitoring scheme plays a main role in system analysis, control, and protection. To monitor the whole system using distributed measurements, strategic placement of them is needed. This paper improves a topological circuit observation method to minimize essential monitors. Besides the observability under normal condition of power networks, the observability of abnormal network is considered. Consequently, a high level of system reliability is carried out. In terms of reliability constraint, identification of bad measurement data in a given measurement system by making theme sure to be detectable is well done. Furthermore, it is maintained by a certain level of reliability against the single-line outages. Thus, observability is satisfied if all possible single line outages are plausible. Consideration of these limitations clears the role of utilizing an optimization algorithm. Hence, particle swarm optimization (PSO) is used to minimize monitoring cost and removing unobservable states under abnormal condition, simultaneously. The algorithm is tested in IEEE 14 and 30-bus test systems and Iranian (Mazandaran) Regional Electric Company.
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Improving power system dynamic performance using attuned design of dual-input PSS and UPFC PSD controller
Yashar HASHEMI, Rasool KAZEMZADEH, Mohammad Reza AZIZIAN, Ahmad SADEGHI YAZDANKHAH
Front Elect Electr Eng. 2012, 7 (4): 416-426.
https://doi.org/10.1007/s11460-012-0219-6
The objective of this work is the coordinated design of controllers that can enhance damping of power system swings. With presence of flexible AC transmission system (FACTS) device as unified power flow controller (UPFC), three specific classes of the power system stabilizers (PSSs) have been investigated. The first one is a conventional power system stabilizer (CPSS); the second one is a dual-input power system stabilizer (dual-input PSS); and the third one is an accelerating power PSS model (PSS2B). Dual-input PSS and PSS2B are introduced to maintain the robustness of control performance in a wide range of swing frequency. Uncoordinated PSS and UPFC damping controller may cause unwanted interactions; therefore, the simultaneous coordinated tuning of the controller parameters is needed. The problem of coordinated design is formulated as an optimization problem, and particle swarm optimization (PSO) algorithm is employed to search for optimal parameters of controllers. Finally, in a system having a UPFC, comparative analysis of the results obtained from application of the dual-input PSS, PSS2B, and CPSS is presented. The eigenvalue analysis and the time-domain simulation results show that the dual-input PSS & UPFC and the PSS2B & UPFC coordination provide a better performance than the conventional single-input PSS & UPFC coordination. Also, the PSS2B & UPFC coordination has the best performance.
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Optimal location of interline power flow controller for controlling multi transmission line: A new integrated technique
B. KARTHIK, I. ALAGARASAN, S. CHANDRASEKAR
Front Elect Electr Eng. 2012, 7 (4): 447-458.
https://doi.org/10.1007/s11460-012-0216-9
In this paper, an interline power flow controller (IPFC) is used for controlling multi transmission lines. However, the optimal placement of IPFC in the transmission line is a major problem. Thus, we use a combination of tabu search (TS) algorithm and artificial neural network (ANN) in the proposed method to find out the best placement locations for IPFC in a given multi transmission line system. TS algorithm is an optimization algorithm and we use it in the proposed method to determine the optimum bus combination using line data. Then, using the optimum bus combination, the neural network is trained to find out the best placement locations for IPFC. Finally, IPFC is connected at the best locations indicated by the neural network. Furthermore, using Newton-Raphson load flow algorithm, the transmission line loss of the IPFC connected bus is analyzed. The proposed methodology is implemented in MATLAB working platform and tested on the IEEE-14 bus system. The output is compared with the genetic algorithm (GA) and general load flow analysis. The results are validated with Levenberg-Marquardt back propagation and gradient descent with momentum network training algorithm.
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Line-start permanent magnet synchronous motors versus induction motors: A comparative study
Majid Ghasemi KAHRISANGI, Arash Hassanpour ISFAHANI, Sadegh VAEZ-ZADEH, Mohammad Rajabi SEBDANI
Front Elect Electr Eng. 2012, 7 (4): 459-466.
https://doi.org/10.1007/s11460-012-0217-8
Line-start permanent magnet synchronous motors are suitable candidates for substitution of induction motors in many constant-speed applications. This paper compares steady-state and dynamic performances of these motors. The efficiency, power factor, stator currents, and rotor bars currents are considered for steady-state performance analysis whereas the rotor speed, electromagnetic torque, and stator and rotor currents are investigated for dynamic performance analysis. For this purpose, time stepping finite element method is used to analyze the performance of motors in both full-load and no-load conditions. Results demonstrate the superior performance of the line-start permanent magnet synchronous motor in steady-state condition and the improved dynamic performance of the induction motor. Finally, economic calculations indicate that the extra cost of the line-start permanent magnet synchronous motor with respect to the induction motor is rapidly compensated by energy saving due to a more efficient operation.
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