Non-equılıbrıum Behavıor Of A Complex Orderıng System: Hysteresıs In The D=3 Isıng Spın-glass From Hard-spın Mean-fıeld Theory

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2007Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2007Üç boyutlu Ising spin-camı fazı içerisinde, bunalımı korumak üzere kurulmuş olan sert-spin ortalama-alan yöntemi kullanılarak histeresis eğrileri elde edilmiştir. Sistem zamana bağlı ve spin-camı düzenine eşlenik rasgele bir dış manyetik alan olan HQ ile sürülmektedir. Bu şekilde, spin-camı fazı içerisinde alan-kaynaklı bir birinci derece faz geçişi sağlanmıştır. Q-HQ eğrisinin histeresis çevrim alanı manyetik alanın sürülme hızı h ile A-Ao ~h^b şeklinde ölçeklenir. Spin-camı ve rasgele-bağ ferromanyetik fazlarında, sürülme hızı ölçeklenme üsteli b sıcaklık T’ye bağlı olarak değişmekte, fakat antiferromanyetik bağ yoğunluğu p den bağımsız gözükmektedir. Saf ferromanyetik fazda ise b diğer fazlardaki duruma ters bir şekilde T’den bağımsızdır ve ayrıca ciddi oranda farklı bir değer almaktadır.Hysteresis loops are obtained in the Ising spin-glass phase in d=3, using frustration-conserving hard-spin mean-field theory that yields the complete varigated micro-scopic ordering in this system at and away from equilibrium. The system is driven by a time-dependent random magnetic field HQ that is conjugate to the spin-glass order Q yielding a field-driven first-order phase transition through the spin-glass phase. The hysteresis loop area A of the Q-HQ curve scales with respect to the sweep rate h of magnetic field as A-Ao~h^b. In the spin-glass and random-bond ferromagnetic phases, the sweep-rate scaling exponent b changes with temperature T but appears not to change with antiferromagnetic bond concentration p. By contrast, in the pure ferromagnetic phase, b does not depend on T and has a sharply different value than in the two other phases.Yüksek LisansM.Sc

Field-Driven Hysteresis of the d=3 Ising Spin Glass: Hard-Spin Mean-Field Theory

Hysteresis loops are obtained in the Ising spin-glass phase in d=3, using frustration-conserving hard-spin mean-field theory. The system is driven by a time-dependent random magnetic field H_Q that is conjugate to the spin-glass order Q, yielding a field-driven first-order phase transition through the spin-glass phase. The hysteresis loop area A of the Q-H_Q curve scales with respect to the sweep rate h of magnetic field as A-A_0 = h^b. In the spin-glass and random-bond ferromagnetic phases, the sweep-rate scaling exponent b changes with temperature T, but appears not to change with antiferromagnetic bond concentration p. By contrast, in the pure ferromagnetic phase, b does not depend on T and has a sharply different value than in the two other phases.Comment: 5 pages, 8 figures, 1 table. Replaced with published versio

Phase Diagrams and Crossover in Spatially Anisotropic d=3 Ising, XY Magnetic and Percolation Systems: Exact Renormalization-Group Solutions of Hierarchical Models

Hierarchical lattices that constitute spatially anisotropic systems are introduced. These lattices provide exact solutions for hierarchical models and, simultaneously, approximate solutions for uniaxially or fully anisotropic d=3 physical models. The global phase diagrams, with d=2 and d=1 to d=3 crossovers, are obtained for Ising, XY magnetic models and percolation systems, including crossovers from algebraic order to true long-range order.Comment: 7 pages, 12 figures. Corrected typos, added publication informatio

Application of mid-infrared spectroscopy for the measurement of several quality parameters of alcoholic beverages, wine and raki

Mid-infrared (IR) spectroscopy, which is a rapid and relatively small amount of waste producing technique, was used to predict several quality parameters of two types of alcoholic beverages, wine and raki. Mid-infrared spectra of red, rose and white wines and a traditional aniseed alcoholic beverage, raki were collected and relations were established between measured chemical parameters (pH, brix, total phenol content, anthocyanin content, titratable acidity, sugar content, electrical conductivity and some colour parameters) of these beverages and their infrared spectra using chemometric techniques. Partial least square regression provided excellent prediction of total phenol (R 2 = 0. 97) and anthocyanin contents (R 2 = 0. 98) of wine samples and a good prediction of pH (R 2 = 0. 9), brix (R 2 = 0. 92) and colour intensity (R 2 = 0. 93) values were obtained. Brix, total phenol and sugar content of raki samples were also estimated very successfully (R 2 = 0. 99) for raki and good prediction was obtained with pH value. Mid-IR spectroscopy in combination with chemometrics could be a promising technique for determination of several quality parameters of alcoholic beverages simultaneously and rapidly