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Optimal Adaptive Controller Based on STATCOM and UPFC
Reza Hemmati,Hamidreza Koofigar,Mohammad Ataei 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.5
In this paper, an advanced and modified MRAS technique is utilized for controller design in electric power systems. The weighting factors of the proposed MRAS are tuned by using PSO. This optimal-adaptive controller is also normalized by normalization techniques to guarantee the system stability. The proposed MRAS then is applied to design STATCOM stabilizer and UPFC power flow controller. STATCOM stabilizer is a regulatory controller, while the power flow controller of UPFC is a tracking one. Therefore, the ability of the proposed MRAS technique to design regulatory and tracking controllers is investigated. In order to indicate the effectiveness of the proposed method, it is evaluated against the conventional methods. Simulation results demonstrate the validity of the method, under uncertainties and different disturbances.
Mohammad Reza Hemmati,Mohammad Ali Khodagholi 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.12
Gas to Liquid has recently become of great interest. In this technology slurry bubble column reactors are favored for many reasons. Separation of liquid wax from the slurry is still a major problem that may be done by internal or external filtration. A system of sintered metal candle filters are designed and operated to collect experimental data of internal filtration. Data for 4 and 8 micron filter elements with different pressure differences and kinematic viscosity were collected. Data analysis revealed that these data could be correlated as a simple function of time, pressure drop and kinematic viscosity. This new and efficient correlation shows excellent ability to reproduce original data at moderate filtration conditions, but it is less precious in severe conditions. It was understood that main reason for this behavior is different filtrate flux regimes through filter media pores, led to inability of a single correlation to fit both regimes properly.
Reza Nazeran,Ali Hemmati,Hasan Haji Kazemi 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.5
Since the cost of reconstruction is very high and the structure may have been damaged by an earthquake, we must retrofit the structure. Therefore, the importance of studying this issue is very high in order to achieve the desired resistance against the regulations. The present study involved the numerical and experimental analysis of nine concrete frames, consisting of three concrete frames, three concrete frames with bracing, and three concrete frames with a TADAS damper. The purpose of this study is to strengthen the damaged concrete frame using braces and TADAS dampers. Observations were made of the frames as they were subjected to controlled displacement. Also, ABAQUS software was used to compare numerical and experimental results. According to the results, the software was sufficiently capable of modeling the studied frames. Additionally, a parametric study was conducted on the thickness and number of bending plates. Thickness increases from 8 mm to 12 mm, 8 mm to 15 mm, and 8 mm to 20 mm, increasing the base shear by about 6.7%, 11.1%, and 25%, respectively. Furthermore, increasing the number of plates from 4 to 5, 4 to 6, and 4 to 7 increased base shears by about 4.5%, 8.4%, and 14%, respectively.
Abdolhamid Salahi,Toraj Mohammadi,Reza Mosayebi Behbahani,Mahmood Hemmati 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.6
Hollow fiber membranes were prepared from polyethersulfone/additives/NMP&DMSO system via phase inversion induced by precipitation in non-solvent coagulation bath. The interaction effects of polyethylene-glycol (PEG), propionic-acid (PA), Tween-20, PEG molecular weight and polyvinyl-pyrrolidone (PVP) on morphology and performance of synthesized membranes were investigated. Taguchi method (L16 orthogonal array) was used initially to plan a minimum number of experiments. 32 membranes were synthesized (with two replications) and their permeation flux and TOC rejection properties to oily wastewater treatment were studied. The obtained results indicated that addition of PA to spinning dope decreases flux while it increases TOC rejection of prepared membranes. Also, the result shows that addition of PVP, Tween-20 and PEG content in spinning dope enhances permeation flux while reducing TOC rejection. The obtained results indicated that the synthesized membranes was effective and suitable for treatment of the oily wastewater to achieve up to 92.6, 98.2, and 98.5% removal of TOC, TSS, and OGC, respectively with a flux of 247.19 L/(m2h). Moreover, Hermia’s models were used for permeation flux decline prediction. Experimental data and models predictions were compared. The results showed that there is reasonable agreement between experimental data and the cake layer model followed by the intermediate blocking model.