Dynamic phase transition features of the cylindrical nanowire driven by a propagating magnetic field

Magnetic response of the spin-$1/2$ cylindrical nanowire to the propagating magnetic field wave has been investigated by means of Monte Carlo simulation method based on Metropolis algorithm. The obtained microscopic spin configurations suggest that the studied system exhibits two types of dynamical phases depending on the considered values of system parameters: Coherent propagation of spin bands and spin-frozen or pinned phases, as in the case of the conventional bulk systems under the influence of a propagating magnetic field. By benefiting from the temperature dependencies of variances of dynamic order parameter, internal energy and the derivative of dynamic order parameter of the system, dynamic phase diagrams are also obtained in related planes for varying values of the wavelength of the propagating magnetic field. Our simulation results demonstrate that as the strength of the field amplitude is increased, the phase transition points tend to shift to the relatively lower temperature regions. Moreover, it has been observed that dynamic phase boundary line shrinks inward when the value of wavelength of the external field decreases.Comment: 7 pages, 4 figure

Dynamic phase transitions in a ferromagnetic thin film system: A Monte Carlo simulation study

Dynamic phase transition properties of ferromagnetic thin film system under the influence both bias and time dependent magnetic fields have been elucidated by means of kinetic Monte Carlo simulation with local spin update Metropolis algorithm. The obtained results after a detailed analysis suggest that bias field is the conjugate field to dynamic order parameter, and it also appears to define a phase line between two antiparallel dynamic ordered states depending on the considered system parameters. Moreover, the data presented in this study well qualitatively reproduce the recently published experimental findings where time dependent magnetic behavior of a uniaxial cobalt films is studied in the neighborhood of dynamic phase transition point.Comment: 15 pages, 5 Figure

Nonequilibrium dynamics of a mixed spin-1/2 and spin-3/2 Ising ferrimagnetic system with a time dependent oscillating magnetic field source

Nonequilibrium phase transition properties of a mixed Ising ferrimagnetic model consisting of spin-1/2 and spin-3/2 on a square lattice under the existence of a time dependent oscillating magnetic field have been investigated by making use of Monte Carlo simulations with single-spin flip Metropolis algorithm. A complete picture of dynamic phase boundary and magnetization profiles have been illustrated and the conditions of a dynamic compensation behavior have been discussed in detail. According to our simulation results, the considered system does not point out a dynamic compensation behavior, when it only includes the nearest-neighbor interaction, single-ion anisotropy and an oscillating magnetic field source. As the next-nearest-neighbor interaction between the spins-1/2 takes into account and exceeds a characteristic value which sensitively depends upon values of single-ion anisotropy and only of amplitude of external magnetic field, a dynamic compensation behavior occurs in the system. Finally, it is reported that it has not been found any evidence of dynamically first-order phase transition between dynamically ordered and disordered phases, which conflicts with the recently published molecular field investigation, for a wide range of selected system parameters.Comment: 10 pages, 7 figure

Nonequilibrium dynamics of a spin-3/2 Blume Capel model with quenched random crystal field

The relaxation and complex magnetic susceptibility treatments of a spin-3/2 Blume-Capel model with quenched random crystal field on a two dimensional square lattice are investigated by a method combining the statistical equilibrium theory and the thermodynamics of linear irreversible processes. Generalized force and flux are defined in irreversible thermodynamics limit. The kinetic equation for the magnetization is obtained by using linear response theory. Temperature and also crystal field dependencies of the relaxation time are obtained in the vicinity of phase transition points. We found that the relaxation time exhibits divergent treatment near the order-disorder phase transition point as well as near the isolated critical point whereas it displays cusp behavior near the first order phase transition point. In addition, much effort has been devoted to investigation of complex magnetic susceptibility response of the system to changing applied field frequencies and it is observed that the considered disordered magnetic system exhibits unusual and interesting behaviors. Furthermore, dynamical mean field critical exponents for the relaxation time and complex magnetic susceptibility are calculated in order to formulate the critical behavior of the system. Finally, a comparison of our observations with those of recently published studies is represented and it is shown that there exists a qualitatively good agreement.Comment: 13 pages, 8 figure

Script: Handful of Fate

It\u27s a special day in town. They are getting ready to welcome their first foreign teacher. However, Julia, an accidental tourist is mistaken for her. And a wind of change starts to blow in the town. Handful of Fate, tells three stories on this very day. Young Ahmet plans to run away with his forbidden lover from the village. Everything falls apart as he is assigned to be Julia\u27s English guide. But she doesn\u27t speak English. Pharmacist Zeynep\u27s story is about her struggle with her lover Celal and the townspeople over leaving for the city. With Volkan\u27s arrival at the pharmacy, it\u27s another chance for the townspeople to spread the rumor to separate them. And there\u27s little Sherlock Ragip who is on a quest with little Sevgi from the village for a love letter that he wrote to Zeynep, but got stolen from his pocket at the foreign teacher\u27s welcoming ceremony. Handful of Fate aims to present the modest acts for change of the townspeople despite the social repression

3D reconstruction using a spherical spiral scan camera

Thesis (Master)--Izmir Institute of Technology, Computer Engineering, Izmir, 2006Includes bibliographical references (leaves: 48-49)Text in English; Abstract: Turkish and Englishviii, 50 leavesConstruction of 3D models representing industrial products/objects is commonly used as a preliminary step of production process. These models are represented by a set of points which can be combined by planar patches (i.e. triangulation) or by smooth surface approximtions. In some cases, we may need to construct the 3D models of real objects. This problem is known as the 3D reconstruction problem which is one of the most important problems in the field of computer vision. In this thesis, a sytem has been developed to transform images of real objects into their 3D models automatically. The system consists of a PC, an inexpensive camera and an electromechanical component. The camera attached to this component moves around the object over a spiral trajectory and observes it from different view angles. At the same time, feature points of object surface are tracked using a tracking algorithm over object images. Then tracked points are reconstructed in 3D space using a stereo vision technique. A surface approximation is fitted to this 3D point set as a last step in the process. Open source .Intel®-OpenCV. C library is used both in image capturing and in image processing