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Probabilistic Stability Analysis of a Railway Embankment on Dispersive Strata Subjected to Periodic Rainfall Conditions with Various Patterns
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
The importance of rainfall pattern in assessing embankment stability and deformation is widely known. However, many studies have examined an embankment with simple rainfall patterns or used average and maximum ones. The importance of diverse rainfall patterns has also been overlooked in the study of divergent soil stability in the previous study. Therefore, the hydraulic properties of a natural soil with and without salinity potential and the stability analysis of the railway embankment located on this type of soil under various rainfall patterns are investigated. The study area is part of the Zahedan Chabahar National Railway Project, which is located on divergent soil and has high...
An IGBT-Based high-voltage crowbar for minimizing the fault current interruption time and injected fault energy during the vacuum arc fault in microwave tubes
, Article IEEE Transactions on Plasma Science ; Volume 49, Issue 6 , 2021 , Pages 1941-1947 ; 00933813 (ISSN) ; Kaboli, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In conventional high-voltage power supplies used for driving the microwave tubes, the shunt crowbar, which generally consists of series-connected thyristors, protects the microwave tube against the vacuum arc fault. In the case of arc fault, the thyristor-based crowbar is closed as a parallel path and diverts the fault current through itself. It avoids serious damage to the microwave tube. However, thyristor switches usually have a limited rate of rise of ON-state current (di/dt), which necessitates placing a series inductor in the crowbar path. Thus, satisfying all protection limits of microwave tubes-including the injected fault energy and the fault current interruption time-is a...
An updated Lagrangian finite element formulation for large displacement dynamic analysis of three-dimensional flexible riser structures
, Article Ocean Engineering ; Volume 38, Issue 5-6 , 2011 , Pages 793-803 ; 00298018 (ISSN) ; Bahai, H ; Mirtaheri, M ; Sharif University of Technology
Abstract
An updated Lagrangian finite element formulation of a three-dimensional annular section beam element is presented for large displacement and large rotation dynamic analyses of flexible riser structures. In this formulation a new linearization method is used to avoid inaccuracies normally associated with other linearization schemes. The effects of buoyancy force as well as steady state current loading are considered in the finite element solution for riser structures response. The formulation has been implemented in a nonlinear finite element code and the results are compared with those obtained from other schemes reported in the literature
Fabrication of sensitive glutamate biosensor based on vertically aligned CNT nanoelectrode array and investigating the effect of CNTs density on the electrode performance
, Article Analytical Chemistry ; Volume 84, Issue 14 , June , 2012 , Pages 5932-5938 ; 00032700 (ISSN) ; Shahrokhian, S ; Iraji Zad, A ; Mohajerzadeh, S ; Vosoughi, M ; Darbari, S ; Koohsorkhi, J ; Mehran, M ; Sharif University of Technology
2012
Abstract
In this report, the fabrication of vertically aligned carbon nanotube nanoelectrode array (VACNT-NEA) by photolithography method is presented. Electrochemical impedance spectroscopy as well as cyclic voltammetry was performed to characterize the arrays with respect to different diffusion regimes. The fabricated array illustrated sigmoidal cyclic voltammogram with steady state current dominated by radial diffusion. The fabricated VACNT-NEA and high density VACNTs were employed as electrochemical glutamate biosensors. Glutamate dehydrogenase is covalently attached to the tip of CNTs. The voltammetric biosensor, based on high density VACNTs, exhibits a sensitivity of 0.976 mA mM-1 cm-2 in the...