Showing 4 results for Moradi
M. Ebrahimi, M. Moradiyan, H. Moeshginkelk, M. Danesh, and M. Bayat,
Volume 25, Issue 1 (7-2006)
Abstract
This paper presents a method based on neural networks to detect broken rotor bars and end rings in squirrel cage induction motors. In the first part, detection methods are reviewed and traditional methods of fault detection as well as dynamic
model of induction motors are introduced using the winding function method. In this method, all stator and rotor bars are considered independently in order to check the performance of the motor for any faults in the parts. Then the frequency spectrum of current signals is derived using the Fourier transform and analyzed under various conditions. In the second part of the paper, an analytical discussion of the theoretical principles is presented to arrive at a simple algorithm for fault detection based on neural networks. The neural network has been trained using the information from a 1.1 KW induction motor. Finally, the system is tested with different values of load torque and is found capable of working on-line to detect all normal and ill-performing conditions.
M. Parvinzadeh, S. Moradian, A. Rashidi, M. E. Yazdanshenas,
Volume 31, Issue 2 (Dec 2012)
Abstract
Polyethylene terephthalate (PET) based nanocomposites containing three differently modified silica particles were prepared by melt compounding. The influence of type and amount of nanosilica on various properties of nanocomposite was studied using atomic force microscope, thermal degradation, thermal-mechanical properties, scanning electron microscope, and reflectance spectra. AFM test was used to study the roughness of composites which indicated that the roughness is related to hydrophilicity degree of silica, increasing with an increase in hydrophilicity of particles. SEM images were studied on the surface, confirming that the surface roughness of nanocomposite depends on the type of nano-silica used. Results of thermal analysis showed that the interaction between nanosilica particle and polyethylene terephthalate chains is effective in thermal stability of composite. UV-vis spectra of polyester nanocomposites indicated that the refraction of hydrophilic silica nanocomposites is more than hydrophobic one, indicating agglomeration of hydrophilic particles at the surface of nanocomposite compared with hydrophobic one.
R. Moradi, M. Roshanaee, H. Mostaan, F. Nematzadeh, M. Safari,
Volume 40, Issue 1 (Journal of Advanced Materials-Spring 2021)
Abstract
In this research, microstructure and mechanical properties of laser welded joints between 2304 duplex stainless steel and Inconel 718 nickel-based super alloy were investigated. Microstructural evolution in the various areas of welded joints and also the effect of welding parameters on the mechanical properties of dissimilar joints were studied. Response surface methodology based on the central composite design was used in order to find the optimum welding parameters. Effective parameters of the welding process including laser power, travel speed and defocusing distance were set in the range of 1000 to 1900 W, 1 to 5 mm/s and -1 to 1 mm, respectively. Uniaxial tensile test was used to evaluate the fracture force of weld joints. The microstructural observations and phase evolutions were studied using optical microscope. It was found that the fracture force of the weld joints firstly increased by travel speed and defocusing distance and then decreased by further increase. The maximum fracture force was obtained when laser power, travel speed and defocusing distance were 1900 W, 3 mm/s and 0 mm, respectively. The center line of weld metal was mainly consisted of equiaxed grains where, columnar grains were formed in the fusion line. The obtained results from the hardness measurement showed that the hardness of Inconel 718 was decreased due to dissolution of TiC and NbC particles.
N. Ghobadi, S. A. Hosseini Moradi, M. Amirzade,
Volume 40, Issue 4 (Journal of Advanced Materials-Winter 2022)
Abstract
In this research, cobalt ferrite powders (CoFe2O4) and cobalt ferrite/reduced graphene oxide composite (CoFe2O4/RGO) were synthesized by the co-precipitation method. The phase structure, morphology, magnetic properties, and microwave absorption properties of the produced samples were investigated through various techniques. X-ray diffraction test indicated the successful formation of pure CoFe2O4 and its composites with RGO. According to the Scanning electron microscopy (SEM) images, most pure and composite samples’ particles were formed in a semi-spherical shape. The VNA test results showed the saturation magnetization of CoFe2O4 and the composite containing 5 wt.% and 10 wt.% of RGO, 71.6, 56, and 37 emu/g, respectively. Also, the network analyzer results demonstrated the maximum reflective losses in the X-band range due to the impact of microwaves on CoFe2O4 te was -5.5 db. This amount reached 21.5 dB with the addition of 10 wt.% RGO. Also, the wave input increased from 41% for the pure CoFe2O4 to 99.5% for the sample containing 10 wt.% RGO.
