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Employing Multi-Phase DG Sources as Active Power Filters, Using Fuzzy Logic Controller
Ghadimi, Ali Asghar,Ebadi, Mazdak The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5
By placing distributed generation power sources beside a big nonlinear load, these sources can be used as a power quality enhancer, while injecting some active power to the network. In this paper, a new scheme to use the distributed generation power source in both operation modes is presented. In this scheme, a fuzzy controller is added to adjust the optimal set point of inverter between compensating mode and maximum active power injection mode, which works based on the harmonic content of the nonlinear load. As the high order current harmonics can be easily rejected using passive filters, the DG is used to compensate the low order harmonics of the load current. Multilevel transformerless cascade inverters are preferred in such utilization, as they have more flexibility in current/voltage waveform. The proposed scheme is simulated in MATLAB/SIMULINK to evaluate the circuit performance. Then, a 1kw single phase prototype of the circuit is used for experimental evaluation of the paper. Both simulative and experimental results prove that such a circuit can inject a well-controlled current with desired harmonics and THD, while having a smaller switching frequency and better efficiency, related to previous 3-phase inverter schemes in the literature.
Multiple Crack Identification in Euler Beams using Extreme Learning Machine
Siamak Ghadimi,Seyed Sina Kourehli 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.1
In this paper, a novel method proposed for multiple crack identification in Euler beams using extreme learning machine (ELM). For this purpose, the extreme learning machine used the modal strain energy and natural frequencies of cracked beam as input and crack states in beam elements as output. To illustrate the performance of the presented method in crack detection, Euler beam with different support conditions consist of cantilever, simply supported and fixed simply supported with single or several cracks in beam elements has been investigated. In other work, a validation study has been done using a simply supported beam. Also, noise effect on the measured modal data has been investigated. The obtained results show the capability of the proposed method for crack detection using ELM.
Employing Multi-Phase DG Sources as Active Power Filters, Using Fuzzy Logic Controller
Ali Asghar Ghadimi,Mazdak Ebadi 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5
By placing distributed generation power sources beside a big nonlinear load, these sources can be used as a power quality enhancer, while injecting some active power to the network. In this paper, a new scheme to use the distributed generation power source in both operation modes is presented. In this scheme, a fuzzy controller is added to adjust the optimal set point of inverter between compensating mode and maximum active power injection mode, which works based on the harmonic content of the nonlinear load. As the high order current harmonics can be easily rejected using passive filters, the DG is used to compensate the low order harmonics of the load current. Multilevel transformerless cascade inverters are preferred in such utilization, as they have more flexibility in current/voltage waveform. The proposed scheme is simulated in MATLAB/SIMULINK to evaluate the circuit performance. Then, a 1kw single phase prototype of the circuit is used for experimental evaluation of the paper. Both simulative and experimental results prove that such a circuit can inject a well-controlled current with desired harmonics and THD, while having a smaller switching frequency and better efficiency, related to previous 3-phase inverter schemes in the literature.
Crack identification in Timoshenko beam under moving mass using RELM
Seyed Sina Kourehli,Siamak Ghadimi,Reza Ghadimi 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.3
In this paper, a new method has been proposed to detect crack in beam structures under moving mass using regularized extreme learning machine. For this purpose, frequencies of beam under moving mass used as input to train machine. This data is acquired by the analysis of cracked structure applying the finite element method (FEM). Also, a validation study used for verification of the FEM. To evaluate performance of the presented method, a fixed simply supported beam and two span continuous beam are considered containing single or multi cracks. The obtained results indicated that this method can provide a reliable tool to accurately identify cracks in beam structures under moving mass.
Investigation of ship collision with floating pier structures
Chegenizadeh, Amin,Ghadimi, Behzad,Nikraz, Hamid Techno-Press 2014 Coupled systems mechanics Vol.3 No.3
This study investigated the collision of ships withfloating pier structures. The nature of the collision phenomenon is complex, and the understanding of it has developed through the modelling of offshore structures. ABAQUS software was used to investigate the collision phenomenon. The interaction between the ship and structural system was modelled, and the stress distribution both at thetime of collision and afterwardswasobserved and modelled. The strain energy absorption by different structural partswas calculated and comparisonswere made.
Dideban, Mohammadhosein,Ghadimi, Noradin,Ahmadi, Mohammad Bagher,Karimi, Mohammmad The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.5
In this work, Self-adaptive Differential Evolutionary (SaDE) algorithm is proposed to solve Optimal Location and Size of Capacitor (OLSC) problem in radial distribution networks. To obtain the SaDE algorithm, two improvements have been applied on control parameters of mutation and crossover operators. To expand the study, three load conditions have been considered, i.e., constant, varying and effective loads. Objective function is introduced for the load conditions. The annual cost is fitness of problem, in addition to this cost, CPU time, voltage profile, active power loss and total installed capacitor banks and their related costs have been used for comparisons. To confirm the ability of each improvements of SaDE, the improvements are studied both in separate and simultaneous conditions. To verify the effectiveness of the proposed algorithm, it is tested on IEEE 10-bus and 34-bus radial distribution networks and compared with other approaches.
A novel two-dimensional approach to modelling functionally graded beams resting on a soil medium
Chegenizadeh, Amin,Ghadimi, Behzad,Nikraz, Hamid,Simsek, Mesut Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.5
The functionally graded beam (FGB) is investigated in this study on both dynamic and static loading in case of resting on a soil medium rather than on the usual Winkler-Pasternak elastic foundation. The powerful ABAQUS software was used to model the problem applying finite element method. In the present study, two different soil models are taken into account. In the first model, the soil is assumed to be an elastic plane stress medium. In the second soil model, the Drucker-Prager yield criterion, which is one of the most well-known elastic-perfectly plastic constitutive models, is used for modelling the soil medium. The results are shown to evaluate the effects of the different soil models, stiffness values of the elastic soil medium on the normal and shear stress and free vibration properties. A comparison was made to those from the existing literature. Numerical results show that considering real soil as a continuum space affects the results of the bending and the modal properties significantly.
Investigation of ship collision with floating pier structures
Chegenizadeh, Amin,Ghadimi, Behzad,Nikraz, Hamid Techno-Press 2014 Interaction and multiscale mechanics Vol.7 No.1
This study investigated the collision of ships withfloating pier structures. The nature of the collision phenomenon is complex, and the understanding of it has developed through the modelling of offshore structures. ABAQUS software was used to investigate the collision phenomenon. The interaction between the ship and structural system was modelled, and the stress distribution both at thetime of collision and afterwardswasobserved and modelled. The strain energy absorption by different structural partswas calculated and comparisonswere made.
Farsi, Mohammad,Ghadimi, Parviz The Society of Naval Architects of Korea 2014 International Journal of Naval Architecture and Oc Vol.6 No.3
Main aim of this paper is to find the best combination of numerical schemes for 2-D SPH simulation of wedge water entry. Diffusion term is considered as laminar, turbulent, and artificial viscosity. Density filter that seriously affects the pressure distribution is investigated by adopting no filter, first order filter, and second order filter. Validation of the results indicates that turbulent model and first order density filter can lead to more reasonable solutions. This simulation was then conducted for wedge water entry with wide range of deadrise angles including 10 degrees, 20 degrees, 30 degrees, 45 degrees, 60 degrees and 81 degrees, with extreme deadrise angles of 10 degrees, 60 degrees and 81 degrees being considered. Comparison of SPH results with BEM solutions has displayed favorable agreement. In two particular cases where experimental data are available, the SPH results are shown to be closer to the experiments than BEM solution. While, accuracy of the obtained results for moderate deadrise angles is desirable, numerical findings for very small or very large deadrise angles are also very reasonable.