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Thermal relaxation phenomena in mixed-type hysteretic systems are investigated by using recently developed mixed Preisach model and Monte Carlo technique. The anomalous hysteretic behavior observed in several heterogeneous materials, especially in nanoscale embedding, is also generating unconventional relaxation processes which may involve several steps before relaxing to the anhysteretic state. The medium-term relaxation behavior is studied under various noisy environments and applied magnetic fields, analyzing the influence of noise strength, noise bandwidth, and field values on the relaxation characteristics. [ABSTRACT FROM AUTHOR]

The spectral density of the output of a Preisach system affected by internal noise is discussed. The method for computing the spectral noise density has two main ingredients. First, the mathematical theory of stochastic processes on graph is used to overcome the difficulty that the output is not a Markovian process. Second, special techniques are used to appreciably simplify the expression for the spectral noise density. Various Preisach systems are considered and the corresponding spectral noise densities are computed and analyzed. Index Terms--Graph theory, Preisach model, spectral density, thermal relaxations.

The atom-phonon coupling model is employed to explain the different metastables electronic spin states that are observed in the spin-crossover materials. Cooperativity is shown to be of no help for obtaining hysteresis at high temperatures.

The multiscale approach to the magnetization dynamics driven by external magnetic fields is presented. The Landau-Liftshitz equations are represented in an equivalent form, where the magnetic free energy is used as one of the state variables and this form clearly separates fast and slow dynamics and consequently, it could be used for the development of perturbation and multiple scale techniques.

Precessional switching of magnetization in perpendicular media induced by short rectangular pulses applied at arbitrary angles with respect to anisotropy axis are studied. The expressions for critical magnetic fields and pulse durations that guarantee precessional magnetization reversals are derived.

The 'inverse problem' approach to the analysis of precessional switching of magnetization in perpendicular media is presented. This approach is purely algebraic in nature and it leads to the direct calculations of expressions for magnetic-field pulses that guarantee the precessional switching.

The influence of surface anisotropy is analyzed on the precessional switching of magnetization in nanoparticles. The approach is used to consider the multispin description of a nanoparticle and investigation of the multispin dynamics by using Landau-Lifshitz equation for each spin with the effective field derived from a Heisenberg-type Hamiltonian.

A method for the calculation of spectral density of hysteretic system driven by stochastic inputs is discussed. This technique is based on the mathematical machinery of stochastic processes on graphs.

Analytical solutions to the Landau-Lifshitz equation for 'damping' and 'precessional'magnetization switchings in ferromagnetic objects with uniaxial anisotropy are discussed. These solutions lead to the expressions for switching times and critical fields.

Micromagnetic simulation using the deterministic Landau-Lifshitz-Gilbert (LLG) equation is inadequate for predicting the coercivity of submicron patterned thin films. It is shown that stochastic micromagnetic simulation is necessary for submicron patterned thin films.

The effect of surface anisotropy on the hysteretic properties of a single domain spherical particle of simple cubic crystalline structure, uniaxial anisotropy in the core, and radial single site anisotropy for spins on the boundary is presented. Considering a spherical particle with simple cubic crystalline structure, a uniaxial anisotropy for core spins, and radial anisotropy on the surface, the hysteresis loop is computed by solving the local Landau-Lifshitz equations for classical spin vectors.

The mixed hysteresis behavior of counter-clockwise and clockwise loops has recently attracted the attention of the magnetics community, due to several experimental findings in inhomogeneous and hetero-structure magnetic systems. Various hybrid models are proposed here to address this behavior based on the superposition of standard hysteresis models and their newly developed clockwise variants. A special attention is also devoted to Bouc-Wen model, a typical clockwise often used by applied mechanics community, and to its relevance for mixed hysteresis. These clockwise and hybrid models have been implemented in an open-access academic software and their performance is illustrated by examples of hysteretic loops, first order reversal curves and diagrams simulated in this framework. [ABSTRACT FROM AUTHOR]

The “inverse problem” approach to the analysis of precessional switching of magnetization in thin films is presented. This approach leads to the explicit expressions for magnetic field pulses that guarantee the precessional switching. The effectiveness of the developed technique is illustrated by examples. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Our choice was justified by the fact that between the two countries exist some features that make them interesting to study from the employment point of view. Thus, both countries are Latin and this is why we consider they are comparable, because employment means people, more precisely mentalities and attitudes to work. We considered that it is interesting to see how the labour market from the east Latin Europe has evolved, in a comparable, crucial period, with its counterpart from west Latin Europe. First of all, we would like to point out the fact that our intention is to analyse the periods which from the economic history point of view have influenced in a decisive manner the present evolution of the two countries. The Portugal labour market is a subject of real scientific interest (we would like to mention that even Michael Porter was interested by this topic). Our paper tries to emphasize the common and different features of the two labour markets, in order to facilitate an experience sharing process on this topic. To achieve the paper’s objectives statistical and cluster analysis have been used. This is one of the best ways to capture the influence of determinant factors on labour market performance. The degree of originality is given by the assumed objectives, namely studying some very up-to-date problems from an interconnected perspective (historical similarities, structural changes, labour market performance) and analyzing the Romanian situation compared to other EU countries, i.e. Portugal. The main impact of the paper will be on the practical level through the model outcomes and conclusions. One of the objectives is to look for solutions to the problems identified and to persuade policy makers to give them a greater importance. Our main contribution is represented by the fact that we have approached this topic from an economic and historical perspective, trying to find explanations for the present situation in the modern past of the two nations.

The paper’s topic is focused on the Romanian labour market prospects, which is going to be affected by two main threats: aging and population decline. These two factors are supposed to dramatically change Romania’s economic structure. It is therefore necessary to know how they will evolve in the next decades, facts which represent the main objective of our article. These topics are debated at large scale at the European and national level, because they describe a process which implies European Union as a whole. The methodology used in order to quantify this phenomenon includes statistical methods (correlation analysis and descriptive statistics). We have used data available at national and European level in order to build a proper argumentation. The results obtained are worrying because there is a high risk to assist at an accelerated aging of the Romanian people, doubled by a very low birth rate. This might create huge problems in the economic and social system due to productivity decrease and the pressures on the pension’s funds. The paper offers scientific arguments for developing macroeconomic policies in order to prevent the negative situation in which we could be within less than 40 years. As a comparison term we brought into attention the Germany situation, country which offers economic equilibrium to the EU, but is also affected by aging. The manner in which this problem has been approached is an original one because we tried to put Romania’s situation into the context of the European Union general situation, the threat being emphasised by the fact that it is going to be a trend for the whole continent. Actually, if it is not taken adequate measures, we will be confronted with a demographic crisis, much worse than the current financial one, because the effort of the country to reverse a birth rate decreasing trend with an aged population will take decades.