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A new lossless snubber for DC-DC converters with energy transfer capability
Shabnam Nasr Esfahani,Majid Delshad,Mohhamad Bagher Tavakoli 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.3
In this paper, a new passive lossless snubber circuit with energy transfer capability is proposed. The proposed lossless snubber circuit provides Zero-Current Switching (ZCS) condition for turn-on instants and Zero-Voltage Switching (ZVS) condition for turn-off instants. In addition, its diodes operate under soft switching condition. Therefore, no significant switching losses occur in the converter. Since the energy of the snubber circuit is transferred to the output, there are no significant conduction losses. The proposed snubber circuit can be applied on isolated and non-isolated converters. To verify the operation of the snubber circuit, a boost converter using the proposed snubber is implemented at 70W. Also, the measured conducted Efficiency Electromagnetic Interference (EMI) of the proposed boost converter and conventional ones are presented which show the effects of proposed snubber on EMI reduction. The experimental results confirm the presented theoretical analysis.
Buckling analysis of concrete plates reinforced by piezoelectric nanoparticles
Reza Taherifar,Maryam Mahmoudi,Mohammad Hossein Nasr Esfahani,Neda Ashrafi Khuzani,Shabnam Nasr Esfahani,Farhad Chinaei 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.4
In this paper, buckling analyses of composite concrete plate reinforced by piezoelectric nanoparticles is studied. The Halphin-Tsai model is used for obtaining the effective material properties of nano composite concrete plate. The nano composite concrete plate is modeled by Third order shear deformation theory (TSDT). The elastic medium is simulated by Winkler model. Employing nonlinear strains-displacements, stress-strain, the energy equations of concrete plate are obtained and using Hamilton's principal, the governing equations are derived. The governing equations are solved based on Navier method. The effect of piezoelectric nanoparticles volume percent, geometrical parameters of concrete plate and elastic foundation on the buckling load are investigated. Results showed that with increasing Piezoelectric nanoparticles volume percent, the buckling load increases.
Vibration response of smart concrete plate based on numerical methods
Reza Taherifar,Farhad Chinaei,Shahram Ghaedi Faramoushjan,Mohammad Hossein Nasr Esfahani,Shabnam Nasr Esfahani,Maryam Mahmoudi 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.4
This research deals with the vibration analysis of embedded smart concrete plate reinforced by zinc oxide (ZnO). The effective material properties of structure are considered based on mixture rule. The elastic medium is simulated by orthotropic visco-Pasternak medium. The motion equations are derived applying Sinusoidal shear deformation theory (SSDT). The differential quadrature (DQ) method is applied for calculating frequency of structure. The effects of different parameters such as volume percent of ZnO, boundary conditions and geometrical parameters on the frequency of system are shown. The results are compared with other published works in the literature. Results indicate that the ZnO have an important role in frequency of structure.