Sharif Digital Repository

Much research has been done in the electromagnetic levitation process, but there is not any information about carrying out this process to refine steel continuously. In this study inclusion behavior of molten steel in contact with slag, in the presence of an electeomagnetic field, has been investigated. The steel sample, in an elliptical section, was levitated in an electromagnetic field, in a chamber containing slag consisting of CaF2-Al2O3-CaO, in order to achieve a continuous process, and changes in time, temperature and slag composition parameters in this process were studied. According to ASTM E45 standard, after performing metallographic process on melted samples, using light... 

Carbon Nanotube webs exhibit interesting properties when used as thermo-acoustic projectors. This work studies thermo-acoustic phenomena of these sound sources both in near and far field regions. Our three-dimensional simulation and experimental data show pressure waves are highly affected by dimensions of sound sources in near field due to interference effects. Although pressure amplitude increases with increasing frequencies, maximum pressure amplitude reached in lower frequencies may become larger than its maximum amount at higher frequencies because of interference effects. Measurement of different surface area sources shows generation of sound waves in far field is independent of... 

In the first part of this thesis, the application of core-shell magnetic nanoparticles supported V(V), Mo(VI) and Mn(III) complexes in the catalytic oxidation and reduction reactions was discussed. A magnetically recyclable vanadium(V) catalyst was synthesized by covalent anchoring of VO(salen)Cl on silica coated Fe3O4 nanoparticles. These nanoparticles were efficient catalysts for selective oxidation of sulfides to corresponding sulfoxides with urea hydrogen peroxide in excellent yields. Leaching and recycling experiments revealed that the nanocatalyst can be applied for nearly complete oxidation of sulfides for at least five successive cycles. A manganese(III) complex was immobilized on... 

According to Haldane Conjecture Antiferromagnetic Heisenberg Spin Chain with integer spin has an energy gap, and exponential decay of correlation functions , while half integer spin chains are gapless with algebraic decay of correlation functions. A spin chain with two types of spins and Heisenberg interaction shows a mixture of both types of behavior. A ferrimagnet which is composed of two spins (S, s) has two bands of energy, the lower band is gapless and ferromagnetic property while the upper one is gapful with antiferromagnetic behavior. In the present work we have studied the anisotropic ferrimagnet in the presence of a transverse magnetic field. We have shown that the spin wave theory... 

In the present paper we construct stock price processes with the same marginal log- normal law as that of a geometric Brownian motion and also with the same transition density (and returns’ distributions) between any two instants in a given discrete-time grid. We then illustrate how option prices based on such processes differ from Black and Scholes’, in that option prices can be either arbitrarily close to the option intrinsic value or arbitrarily close to the underlying stock price. We also explain that this is due to the particular way one models the stock-price process in between the grid time instants which are relevant for trading
 

Nowadays, the lattice Boltzmann method has been widely used by scientists and engineers as an alternative to conventional numerical solvers for the Naiver-Stokes equations. The drag force decrease on the surfaces in industrial applications special in transport industries has always been of special importance. In the current research, the effects of the drag decrease has been investigated by making some rectangular grooves on the millimeter and micrometer scale on a flat surface that has been under external laminar flow of a single-phase fluid with the uniform type. Making grooves on the surfaces usually lead to change the contact area from the solid-fluid to fluid-fluid in the grooves area....