List of Articles
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Open Access Article
1 - Multipath Error Mitigation of Low-Cost GPS Receiver Using PSO-SVM and GA-SVM Hybrid Methods
Mohammad S. E. Abadi M. H. Refan A. DameshghiOne of the major errors that affect GPS accurately is the multi-path effect of each receiver. Multi-paths is receiving an antenna signal from more than one path, multi-path effect is a major source of unknown error in positioning and is not eliminated by differential me MoreOne of the major errors that affect GPS accurately is the multi-path effect of each receiver. Multi-paths is receiving an antenna signal from more than one path, multi-path effect is a major source of unknown error in positioning and is not eliminated by differential methods. This effect is largely dependent on the environment specific to each receiver and it is low-frequency effect. The geometry between GPS satellites and the specific location of each receiver is repeated on astronomical days, the multi-path effects tend to behave similarly on consecutive days. In this paper, a method for extracting the multi-path effects behavior was applied to the GPS-code observations, multi-path error mitigation increases the accuracy of positioning. In the proposed method, the residual signal is generated based on the dual difference (DD) and is used as the input of the proposed algorithm. Support Vector Machine (SVM) is used for multi-path approximation. To determine the basic parameters of SVM and its kernel function, particle optimization algorithms (PSO) and genetic algorithm (GA) were used. In order to evaluate the accuracy of the proposed method, simulation and experimental based on two stations (reference and user) and two low-cost receivers were designed. The proposed methods were tested based on practical data. The experiments showed that the multi-path error of the receiver of the user's station decreased by 70% in the static test based on the RMS criterion. Models of this paper have been compared with some recent models presented in the context of multi-path error reduction. The results showed that the proposed model had better performance than other methods. The result is high accuracy and stability in positioning results. Three-dimensional position accuracy improved by about 56% after using the proposed method, reaching 1.60 m. Manuscript profile -
Open Access Article
2 - LMI Robust Control Design for SIDO Boost Converter Based on SFG Modelling Method
M. Abbasi Mohammad Reza Alizadeh Pahlavani Ahmad AfifiA robust control design process based on a linear Matrix Inequalities (LMI) for a Single Inductor Multi Output (SIMO) boost converter has been presented in this paper. Considering complicated multi-stages operation of SIDO converter, Signal Flow Graph (SFG) modelling wa MoreA robust control design process based on a linear Matrix Inequalities (LMI) for a Single Inductor Multi Output (SIMO) boost converter has been presented in this paper. Considering complicated multi-stages operation of SIDO converter, Signal Flow Graph (SFG) modelling was used to predict all behavior of the converter. Using the SFG model, nonlinearities and uncertainties was modelled as a convex polytope for LMI design constraints. This method guarantees a certain perturbation rejection level and a region of pole location. The derived parameters from LMI were applied on state-feedback coefficients in Matlab/Simulink to show the validity of the presented LMI method. Finally, the obtained results have been compared with a conventional PI controller. Manuscript profile -
Open Access Article
3 - Torque Ripple Reduction Technique in SRM for Low Speed Range by Employing Fuzzy Logic for Dynamic Controlling of TSF
H. Moradi Cheshmeh-Beigi E. NouriIn this paper, in order to reduce torque ripple for low speed range in non-commutation region, instead of exciting by a DC current, a adjustable current according to rotor position is injected. Also, to reduce torque ripple in commutation region the modified torque shar MoreIn this paper, in order to reduce torque ripple for low speed range in non-commutation region, instead of exciting by a DC current, a adjustable current according to rotor position is injected. Also, to reduce torque ripple in commutation region the modified torque sharing function (TSF) method has been used. In the proposed method, TSF is modified by a feedback from the motor speed and applying it to a fuzzy controller according to speed value. In the proposed method, motor speed, torque error, and torque error derivative are used as fuzzy controller inputs, which Turn-On and overlap angles between the phases are changed as a function of motor speed. Also reference torque of adjacent phase is modified as a function of torque error and torque error derivative. In this method, TSF is modified dynamically and momentary. The exact simulation based on Matlab/Simulink for a 3-phase 6/4 SRM are carried out to verify the effectiveness of the proposed novel method for 0 to 1500rpm speed range. Manuscript profile -
Open Access Article
4 - Identification of Coherent Machines Based on Slow Coherency
S. H. Adeli A. RabieeTo study the stability of dynamic systems, it is neither practical nor necessary to model the entire interconnected system in details. In more specific application, such as dynamic security assessment and system control design, reduced order models of the entire system, MoreTo study the stability of dynamic systems, it is neither practical nor necessary to model the entire interconnected system in details. In more specific application, such as dynamic security assessment and system control design, reduced order models of the entire system, or part of it, are needed to satisfy computational or design constraints. In this paper, a dynamic reduction method based on coherency concept is developed and slow coherency identification is used to identify coherency machine. Despite its simplicity, the proposed method provides an effective approach to recognize coherence generators. Furthermore, a new clustering method is suggested in this paper to improve acceleration of coherence machines identification. Finally, the accuracy of proposed method is evaluated by time domain simulation and compared with other methods. The obtained results indicate that the new proposed grouping method works more quickly than the other methods in the area, concluding that, without loss of accuracy, it can be readily used in dynamic studies of power systems. Manuscript profile -
Open Access Article
5 - Nonlinear Analysis of Jitter Transfer in Charge Pump Phase-Locked loops regarding Channel Length Modulation Effect
H. Dehbovid H. Adarang M. B. TavakoliDue to the nonlinear behavior caused by the charge pump, charge pump phase-locked loops (CPPLLs) are nonlinear systems. In an ideal charge pump, the applied current is constant; however, in practice, it is not constant due to the transistor's non-ideal effects. In this MoreDue to the nonlinear behavior caused by the charge pump, charge pump phase-locked loops (CPPLLs) are nonlinear systems. In an ideal charge pump, the applied current is constant; however, in practice, it is not constant due to the transistor's non-ideal effects. In this paper, regarding the transistor's channel length modulation effect (CLM) on charge pump’s current, the non-linear differential equation of the system is obtained and shows that the phase lock loop is a nonlinear system with memory and Voltaire Series expansion can be used to analyze it. As a result, a method for estimating a jitter transfer with a second-order filter is proposed. System level simulation is used to validate the analytical results with particular emphasis on the jitter transfer characteristics. The effect of different loop parameters has also been studied. The experiments all show excellent conformance between analytical equations and simulation results. Manuscript profile -
Open Access Article
6 - The Effect of MIMO Channel Estimator in the Precoder Design of Wireless Sensor Networks
H. Rostami A. FalahatiOne of the most important applications of wireless sensor networks was to estimate the unknown phenomenon. The cooperative activities of wireless sensors and scattered information of sensor nodes over network are used to decentralized estimation. Precoder design done on MoreOne of the most important applications of wireless sensor networks was to estimate the unknown phenomenon. The cooperative activities of wireless sensors and scattered information of sensor nodes over network are used to decentralized estimation. Precoder design done on the sensor nodes in order to provide an optimal estimate of the actual amount. Precoder design is an optimization problem. Since the channel is wireless link on the wireless sensor networks. Therefore, assuming the access of full channel state information isn't correct in this network. Since the perfect channel state information is required in the precoder design process, so the effects of the channel estimation investigated on precoder design process. On the issue of channel estimation, channel estimated by using of the known training sequence method with LS and MMSE criteria. Since power restriction is the key subject in the wireless sensor networks, therefore in this study power restriction considered in the channel estimation and precoder design problem. Manuscript profile -
Open Access Article
7 - Covariance Matrix Design for SINR Enhancement in Presence of Signal-Dependent Interferers
M. Bolhasani S. Imani S. A. GhorashiIn this paper, the problem of covariance matrix design to increase signal-to-interference-plus-noise ratio (SINR) in receiver for multiple-input multiple-output (MIMO) radars is considered. Our goal is to design a covariance matrix which can suppress more interferers co MoreIn this paper, the problem of covariance matrix design to increase signal-to-interference-plus-noise ratio (SINR) in receiver for multiple-input multiple-output (MIMO) radars is considered. Our goal is to design a covariance matrix which can suppress more interferers compared to phased array radar and recent covariance matrix design methods. It can also result in a better SINR level compared to conventional MIMO radars. In this paper, maximum SINR of the proposed covariance matrix is calculated in closed form. Simulation results show that our proposed covariance matrix in addition to achieve better SINR performance, can suppress more interferers compared to phased array radar and recent covariance matrix design methods, by using waveform diversity with the same number of antennas. Simulation results also validate analytical achievements that presented in this paper. Manuscript profile -
Open Access Article
8 - Improving the Power System State Estimation Algorithm Based on the PMUs Placement and Voltage Angle Relationships
A. R. Sedighi M. Sayaf M. R. TabanTo optimize the operation of power systems, monitoring of network state variables is important. Because these variables play an important role in improving economic efficiency, network reliability and analyze system status.Therefore, state estimation algorithm have been MoreTo optimize the operation of power systems, monitoring of network state variables is important. Because these variables play an important role in improving economic efficiency, network reliability and analyze system status.Therefore, state estimation algorithm have been used to determine an accurate estimate of state variables with limited measurements. Since modern measuring devices, such as PMUs, in addition to the measurement of electrical quantities are able to measure bus voltage angle,in this paper, a new method is proposed to obtain a more accurate estimate of all network variable. The proposed algorithm determines number and location of the measuring devices (PMUs) in such a way that state variables and electrical quantities can be obtained in the most accurate estimate. Increasing the state estimation calculations accuracy is due to the use of the derivatives of the buses voltage angle equations along with the state estimation relations. Finally, the calculation of the state estimation is performed using the least squared weighted method (WLS). The calculations performed on the IEEE 14 bus network are done using MATLAB and MATPOWER software. The results show that the proposed method has been successful in increasing the accuracy of estimating state variables and reducing the number and proper location of PMUs . Manuscript profile