Fibonacci Oscillators in the Landau Diamagnetism problem

We address the issue of the Landau diamagnetism problem via $q$-deformed algebra of Fibonacci oscillators through its generalized sequence of two real and independent deformation parameters $q_1$ and $q_2$. We obtain $q$-deformed thermodynamic quantities such as internal energy, number of particles, magnetization and magnetic susceptibility which recover their usual form in the degenerate limit $q_1^2 + q_2^2$=1.Comment: Latex, 11 pages, two figures, version to appear in Physica

Thermal properties of a solid through q-deformed algebra

We address the study of the thermodynamics of a crystalline solid by applying q-deformed algebras. We based part of our study by considering both Einstein and Debye models. We have mainly explored the q-deformed thermal and electric conductivities as a function of the Debye specific heat. The results led to the interpretation of the q-deformation acting as a factor of disorder or impurity modifying the characteristics of a crystalline structure as, for example, in the case of semiconductors.Comment: 8 pages, twocolumn, 12 figures, Latex, version to appear in Physica

Playing with universality classes of Barkhausen avalanches

Many systems crackle, from earthquakes and financial market to Barkhausen effect in ferromagnetic materials. Despite the diversity in essence, the noise emitted in these dynamical systems consists of avalanche-like events with broad range of sizes and durations, characterized by power-law avalanche distributions and typical average avalanche shape that are signatures dependent on the universality class of the underlying dynamics. Here we focus on the crackling noise in ferromagnets and scrutinize the traditional statistics of Barkhausen avalanches in polycrystalline and amorphous ferromagnetic films having different thicknesses. We show how scaling exponents and average shape of the avalanches evolve with the structural character of the materials and film thickness. We find quantitative agreement between experiment and theoretical predictions of models for the magnetic domain wall dynamics, and then elucidate the universality classes of Barkhausen avalanches in ferromagnetic films. Thereby, we observe for the first time the dimensional crossover in the domain wall dynamics, and the outcomes of the interplay between system dimensionality and range of interactions governing the domain wall dynamics on Barkhausen avalanches.Comment: 6 figures, 2 table

Hard turning of AISI D6 tool steel under dry, wet and cryogenic conditions: An economic investigation aimed at achieving a sustainable machining approach

The aim of this study was to encourage cleaner production processes by investigating the economic feasibility of using LN2 as a cutting fluid in the turning of quenched and tempered AISI D6 tool steel using solid PCBN inserts. For this purpose, an LN2 supply system was developed to deliver liquid nitrogen to the tool rake and flank faces. In order to measure the LN2 mass flow rate, a system based on load cells was set up. Three different LN2 flow rates (79, 51 and 21 ​L/h) were investigated. For comparison, turning tests under dry and wet conditions using a mineral-based emulsion were also performed. Nose wear (VBC) was monitored and used as one of the input parameters for an economic analysis, which was performed based on a previous study. It was concluded that the LN2 delivery system and the method used for the LN2 flow rate measurement were effective in supplying liquid nitrogen to the cutting zone in a controlled way, and liquid nitrogen at the highest flow rates provided longer cutting tool life than dry and wet conditions. Furthermore, the use of an emulsion did not increase the cutting tool life in comparison with the dry condition and machining assisted by LN2 at the lowest flow rate presented no statistical difference as compared to the wet condition in terms of production cost. Thus, based on this case study, liquid nitrogen can be considered as a sustainable alternative to the use of mineral-based emulsions, without incurring economic losses