Sharif Digital Repository

The flexible magnetic robot is used for minimally invasive surgeries where there is a complex environment. Precise control of the position of the end of the robot and quick adaptation of the robot to uncertainties are among the most important challenges in this field, where the controller is responsible for compensating the error and controlling the position of the end of the robot. Now, is it possible to create a kind of memory in the system that when faced with the same or similar errors in the same situations or close to previous errors, the system uses its past and compensates the error? The importance of this work is that the response speed of the system is increased and the system can... 

In this research, a facile, two-step synthesis was reported for 34-LCysteine- nanocomposites. The first step comprises the preparation of LCysteine functionalized magnetic nanoparticles (MNPs) core-shell structures via co-precipitation method. In the second step, graphene quantum dots (GQDs), which were synthesized by citric acid carbonization, added to the functionalized MNPs and finally refluxed at the appropriate time and temperature. LCysteine as a biocompatible, natural amino acid were used to link MNPs with GQDs. This nanocomposite was characterized by various techniques. XRD and FT-IR were used to investigate the formation of MNPs and LCysteine existence on the MNPs surface. XPS... 

In this investigation, effect of processing parameters on the soft magnetic properties of nanocrystalline Fe85Si10Ni5 (at. %)-phenolic resin composites were studied. The nanostructured powders were obtained by mechanical milling in a high-energy vibratory disc mill. Annealing was performed to decrease internal strains and density of dislocations. The microstructure, morphology and DC magnetic properties of the milled powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and a vibrating sample magnetometer (VSM). Bulk samples were obtained by compaction in different pressures and temperatures. The effects of different compaction treatments and annealing... 

In this study, an alkaline bath for co-deposition of Fe and Pd was selected. In order to investigate the mechanism of deposition, each of the metals iron and palladium electrodeposited from selected bath separately; and the kinetics of electrodeposition by electrochemical techniques such as linear voltammetry, cyclic voltammetry, chronoamperometry and chronopotentiometry were evaluated. Electrodeposition processes of Fe, Pd and their alloy were irreversible and under diffusion of reducing agents are controlled. Moreover the electroreduction of palladium from utilized bath was performed in two steps. At following, the mechanism of iron– palladium alloy electrocrystallization was discussed and... 

A356 Aluminium alloy has an abundant application in the aerospace and automobile industries. One of the most important problems of the alloy is in it’s microstructure after solidification with long dendrite grain of Aluminium.It is stated that solidied grains can be refined by electromagnetic vibration and an alternative electric feild applied simultaneously. To make electric field, electric current passed through the specimen. In order to change in microstructure, electromagnetic vibration was used. Then the effect of intensity of electromagnetic field and alternative electric current on microstructure was examined.Grain refining carried out at electric current 80A and magnetic flux of 13,... 

In this research, soft magnetic-soft composite of iron-borosilicate was prepared by cold compression and then heat treatment at 850 ° C. In order to prepare the initial mixture, the pure iron powder was mixed with different particles of 2% by weight of borosilicate and pressed at 400, 800 and 1200 MPa, and then subjected to thermal treatment at 850 ° C for one hour. After examining the density, electrical resistance, magnetic properties of DC, the magnetic properties of these materials were studied in the frequency range of 10-1000 kHz at room temperature and at 300 ° C. The results show that increasing the particle size increases the saturation magnetization and magnetism and reduces the... 

Finemet soft magnetic alloys in the form of toroidally winded ribbons are not suitable for industrial applications where a large volume of magnetic materials is required. Production of Finemet bulk alloy by powder metallurgy techniques is an applicable method to produce complex component with isotropic magnetic properties which are the same as ribbons. In this research, Finemet bulk magnetic alloy with composition of has been produced by consolidation of amorphous powders obtained by milling of melt-spun ribbons. At the all stages, the structure and magnetic properties were studied using X-ray diffraction, differential scanning calorimetry, transmission electron microscopy, scanning... 

In this study, soft magnetic composite properties of iron base with insulation magnetite nanoparticles have been studied. First magnetite nanoparticles were prepared by co-precipitation method. The iron and magnetite particles with different weights were dissolved in acetone until the acetone evaporates and the composition uniformity of iron and magnetite powder was obtained. Then press the button on the 4 samples of 400, 600, 800, 1000 MPa, and the weight of Magnetite 1, 3, 5, 7 and 10 percent were cold. X-ray diffraction and scanning electron microscope test results showed that iron and magnetite are homogenous distributed. The measurement of AC magnetic properties also suggest that by... 

The ternary 122-type AeFe2As2 (Ae=Ba,Sr,Ca) compounds are antiferromagnetic metals with the orthorhombic lattice structure at ambient pressure and low temperature. By applying mechanical pressure, structural, magnetic and superconducting transitions occur in these compounds. The isovalent doping of Ba with Sr and Ca elements induces chemical pressure and reduces the onset pressure of these transitions. The main purpose of this thesis is to investigate and compare the effects of mechanical and chemical pressures on the structural and magnetic phase transition in the 122 compounds. To achieve this purpose, we have done first-principle calculations for many properties such as the structural... 

The most important researchers’ purposes in superconductivity are achievement of the room temperature superconductivity and to understand the high temperature superconductivity mechanism. Researchers’ goal in to increase the transition temperature by applying pressure, changing oxygen content, different doping, and changing stoichiometry in the families of the high temperature superconductors. In this research, which has been carried out in the Magnet Research Laboratary of Sharif University of Technology, samples of Y3Ba5Cu8O18, Gd3Ba5Cu8O18, and Pr3Ba5Cu8O18 have been synthesized by the standard solid-state reaction technique, the structure, electrical and magnetic properties of the...