Torkaman H.,Young Researchers Club |
Afjei E.,Shahid Beheshti University
Progress in Electromagnetics Research | Year: 2010
This paper proposes magnetostatic analysis of Switched Reluctance Motor (SRM) under angular misalignment fault to evaluate the performance of the motor under different operating conditions. In this analysis three-dimensional finite element method (FEM) is used to simulate reliable and precise model by considering the complex motor magnetic geometry, end effects, axial fringing effects as well as nonlinear properties of the magnetic materials. The FE analysis is performed to obtain the static magnetic characteristics of SRM including flux density, flux linkages, terminal inductance and mutual inductance profile under different rotor positions for different varying degree of faults. Consequently, it presents assessing the features of mutual inductance in inactive phases to study the variations of diagnosis index. The results obtained present useful information regarding the detection of fault and its direction as well as the amount of angular misalignment fault in the motor. To the best knowledge of the authors, such an analysis has not been carried out previously.
Ahmadi M.,University of Tehran |
Amiri B.M.,University of Tehran |
Abdoli A.,Shahid Beheshti University |
Fakharzade S.M.E.,University of Tehran |
Hoseinifar S.H.,Young Researchers Club
Environmental Biology of Fishes | Year: 2011
This study investigates sex steroids, gonadal histology and some biological indices of fall and spring spawning migrants of Caspian lamprey Caspiomyzon wagneri (Kessler, 1870). Blood and gonad samples were collected from 15 migrants during fall and spring. Serum sex steroid levels including testosterone (T), 17β-estradiol (E2) and progesterone (P) were determined with ELISA and gonadal development was studied using conventional histological methods. Our results showed serum E2 level in females were similar in the two seasons but in males, fall migrants had higher serum E2 concentrations. No differences were found in T levels in fall and spring migrants. Serum P concentration in fall migrant males were significantly higher than spring migrant males while spring migrant females had higher serum P levels compare to fall migrant females. Gonads in both fall and spring migrants were in the final stage of maturity. Fall and spring migrant males had similar HSI and GSI; fall migratory female had significantly higher HSI and GSI. Sex ratios were close to 1:1 in both seasons. There was a significant relationship between fecundity and length in both seasons. Comparison of fecundity and egg diameter between fall and spring seasons showed no significant difference. These results indicate that both fall and spring migrants Caspian lamprey were ready for spawning. Further studies are needed to clarify when spawning occurs in Caspian lamprey. © 2011 Springer Science+Business Media B.V.
Yazdanpanah S.,Islamic Azad University at Mashhad |
Yazdanpanah S.,Young Researchers Club |
Baghizadeh A.,HIGH-TECH |
Abbassi F.,Islamic Azad University at Mashhad
African Journal of Agricultural Research | Year: 2011
Water is one of the most important environmental factors that regulate plant growth and development, and water deficit is considered the most important restricted factor for plant products, in that several chemical materials have been used to reduce the harmful effects of water deficit. Some of these compounds (for instance, ascorbic and salicylic acid) have antioxidant effects in plants. In order to study the interaction between drought stress with salicylic and ascorbic acid on some biochemical criteria of Satureja hortensis, a factorial experiment with a completely randomized design in three replications and different combination of three levels of irrigation (1/3, 2/3 and total field capacity), three levels of salicylic acid (0, 1 and 3 mM) and three levels of ascorbic acid (0, 1 and 3 mM) under green house conditions was conducted. Results, revealed under aridity, sugar content and protein content of S. hortensis, were decreased; however, proline and lipid per oxidation increased. The results concluded that when drought stress affected the plants, the protective mechanism was activated. The reduction of protein content in this condition showed that drought stress affected protein synthetic and degradation. The reduction of sugar content showed that stress affected the photosynthetic process. On the other hand, in the presence of both salicylic and ascorbic acids, the harsh influences of water deficit reduced and some growth parameters increased. It seemed that two external acids were able to enhance the tolerant ability of the plant to aridity stress. © 2011 Academic Journals.
Hosseini M.,Islamic Azad University at Tehran |
Abizadeh Sh.,Young Researchers Club
From Materials to Structures: Advancement Through Innovation - Proceedings of the 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2012 | Year: 2013
In this study, at first an aboveground rectangular reinforced concrete tank with common dimensions and tapered walls was designed based on the ACI 350 code. Then, by performing several cases of time history analyses, using a finite element analysis program, in which the flexibility of the tank walls, water-tank interaction and sloshing were taken into consideration, the hydro-dynamic pressure on the tank walls, the base shear force in various directions, and the maximum water level increase due to sloshing phenomenon were studied. The PGA value of the main components of all used earthquakes were adjusted to 0.400 g, however those of the vertical components were varying from 0.135 g to 0.59 g. Results show that in case of near-source earthquakes the amount of hydro-dynamic pressure on the tank wall increases, while no major difference is observed in base shear and water level increase, due to increase in the PGA of vertical ground motion. © 2013 Taylor & Francis Group.
Mohammadpour M.,Islamic Azad University at Fasa |
Rostampour M.,Young Researchers Club
Proceedings of 2012 International Conference on Multimedia Computing and Systems, ICMCS 2012 | Year: 2012
In this paper a novel compensation method for low power two-stage operational Amplifiers is proposed. The proposed model is used 50 nm CMOS technology and employs a 50 femto Farad capacitor as the compensation capacitor. Although the method uses Miller effect compensation as the compensation method, the compensation capacitor plays its rule in an indirect way. The proposed method has simulated and the results has compared to the conventional cascode and an improved miller compensation model. Simulation results show that the proposed method is made a proper stability, bandwidth and settling time, where the other methods are unstable in the same technology. © 2012 IEEE.