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.
The ability to detect the primary user’s signal is one of the main performances for cognitive radio networks. Based on the multi-different-cyclic-frequency characteristics of the cyclostationary primary user’s signal and the cooperation detection advantage of the multi-secondary-user, the paper presents the weighted cooperative spectrum detection algorithm based on cyclostationarity in detail. The core of the algorithm is to detect the primary user’s signal by the secondary users’ cooperation detection to the multi-different-cyclic-frequency, and to make a final decision according to the fusion data of the independent secondary users’ detection results. Meanwhile, in order to improve the detection performance, the paper proposes a method to optimize the weight on basis of the deflection coefficient criterion. The result of simulation shows that the proposed algorithm has better performance even in low signal-to-noise ratio (SNR).
A proposed circular patch antenna with notch-cut fed by a simple microstrip line is described in this paper. It is designed for ultra-wideband (UWB) wireless communications and applications over the band 3.1–10.6 GHz. This antenna consists of a circular patch with notch-cut fed by a microstrip line, one transition step, and a partial ground plane. The 2:1 voltage standing wave ratio (VSWR) bandwidth (
In this paper, a fundamental advancement of the basic helix design which expands to array having good bandwidth is proposed. The helix is inserted in a cavity. The result is a new antenna design that offers the performance characteristics and advantages of the conventional helix but in a much more compact physical size envelope. A 4-element rectangular helical array has been designed. For miniaturization and impedance matching, the helical wire is replaced by a rectangular cross sectioned strip. It has been observed that when the helix is inserted in a cavity, it behaves differently from a normal helical antenna. The effects of the cavity on the number of turns, the impedance of total antenna, and the reflection coefficient have been analyzed. The array is designed for 2.4 GHz. The return loss obtained is less than -10 dB and the bandwidth is more than 1.3 GHz for the array.
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 (
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
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.
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.
The main objective of this paper is to develop PI and fuzzy controllers to analyze the performance of instantaneous real active and reactive power (p-q) control strategy for extracting reference currents of shunt active filters (SHAFs) under balanced, unbalanced, and balanced non-sinusoidal conditions. When the supply voltages are balanced and sinusoidal, both controllers converge to the same compensation characteristics. However, if the supply voltages are distorted and/or unbalanced sinusoidal, these controllers result in different degrees of compensation in harmonics. The p-q control strategy with PI controller is unable to yield an adequate solution when source voltages are not ideal. Extensive simulations were carried out with balance, unbalanced, and non-sinusoidal conditions. Simulation results validate the superiority of fuzzy logic controller over PI controller. The three-phase four-wire SHAF system is also implemented on a real-time digital simulator (RTDS hardware) to further verify its effectiveness. The detailed simulation and RTDS hardware results are included.
In this paper, digital signal processor (DSP) based fuzzy controller for series parallel resonant converter (SPRC) has been estimated, and the performance of the converter is analyzed by using state space model. The method to predict the steady-state and dynamic performance of the converter with load independent operation has been presented. The proposed converter has been analyzed with the closed-loop and open-loop conditions. The simple form of transfer function for SPRC is developed, and it is used to analyze the stability of the converter with closed-loop operation. The stability analysis of the converter is carried out by using frequency response plan. The fuzzy controller regulates the output voltage with change supply voltage and load disturbance. The controller performance of inductance capacitance inductance – T network (LCL-T) SPRC is compared with inductance inductance capacitance – T network (LLC-T) SPRC through simulation and experimental studies using TMS320F2407 processor.
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.
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.
This paper describes an adaptive gain sliding mode observer for brushless DC motor for large variations in speed. Sensorless brushless DC motor based on sliding mode observer exhibits multiple zero crossing in back electromotive force (EMF) which leads to commutation problems at low speed. In this paper, a modified sliding mode observer incorporating a speed component in the estimation of back EMF is proposed. It is found that after incorporating the speed component in the back EMF observer gain, multiple zero crossings at low speeds and phase shift at higher speeds are eliminated. The trapezoidal back EMF observer is implemented experimentally on a digital signal processor (DSP) board. The effectiveness of the proposed method is demonstrated through simulations and experiments.
In this article an artificial neural network (ANN) has been designed for the control of DC series motor through a DC chopper (DC-DC buck converter). The proportional-integral-derivative (PID)-ANN speed controller controls the motor voltage by controlling the duty cycle of the chopper thereby the motor speed is regulated. The PID-ANN controller performances are analyzed in both steady-state and dynamic operating condition with various set speeds and various load torques. The rise time, maximum overshoot, settling time, steady-state error, and speed drops are taken for comparison with conventional PID controller and existing work. The training samples for the neuron controller are acquired from the conventional PID controller. The PID-ANN controller performances are analyzed in respect of various load torques and various speeds using MATLAB simulation. Then the designed controllers were experimentally verified using an NXP 80C51 based microcontroller (P89V51RD2BN). It was found that the hybrid PID-ANN controller with DC chopper can have better control compared with conventional PID controller.