52 resultados para Theory of science
Resumo:
Los rankings de productividad científica resultan cada vez más relevantes, tanto a nivel individual como institucional. Garantizar que se basan en información confiable y exhaustiva es, por tanto, importante. Este estudio indica que la posición de los individuos en esa clase de ranking puede cambiar sustancialmente cuando se consideran diversos indicadores bibliométricos internacionalmente reconocidos. Se usa, como ilustración, el caso de los diez profesores del área de ‘Personalidad, Evaluación y Tratamiento Psicológico’ consignados en el reciente análisis de Olivas-Ávila y Musi-Lechuga (Psicothema 2010. Vol. 22, nº 4, pp. 909-916).
Resumo:
In his version of the theory of multicomponent systems, Friedman used the analogy which exists between the virial expansion for the osmotic pressure obtained from the McMillan-Mayer (MM) theory of solutions in the grand canonical ensemble and the virial expansion for the pressure of a real gas. For the calculation of the thermodynamic properties of the solution, Friedman proposed a definition for the"excess free energy" that is a reminder of the ancient idea for the"osmotic work". However, the precise meaning to be attached to his free energy is, within other reasons, not well defined because in osmotic equilibrium the solution is not a closed system and for a given process the total amount of solvent in the solution varies. In this paper, an analysis based on thermodynamics is presented in order to obtain the exact and precise definition for Friedman"s excess free energy and its use in the comparison with the experimental data.
Resumo:
The extensional theory of arrays is one of the most important ones for applications of SAT Modulo Theories (SMT) to hardware and software verification. Here we present a new T-solver for arrays in the context of the DPLL(T) approach to SMT. The main characteristics of our solver are: (i) no translation of writes into reads is needed, (ii) there is no axiom instantiation, and (iii) the T-solver interacts with the Boolean engine by asking to split on equality literals between indices. As far as we know, this is the first accurate description of an array solver integrated in a state-of-the-art SMT solver and, unlike most state-of-the-art solvers, it is not based on a lazy instantiation of the array axioms. Moreover, it is very competitive in practice, specially on problems that require heavy reasoning on array literals
Resumo:
New economic and enterprise needs have increased the interest and utility of the methods of the grouping process based on the theory of uncertainty. A fuzzy grouping (clustering) process is a key phase of knowledge acquisition and reduction complexity regarding different groups of objects. Here, we considered some elements of the theory of affinities and uncertain pretopology that form a significant support tool for a fuzzy clustering process. A Galois lattice is introduced in order to provide a clearer vision of the results. We made an homogeneous grouping process of the economic regions of Russian Federation and Ukraine. The obtained results gave us a large panorama of a regional economic situation of two countries as well as the key guidelines for the decision-making. The mathematical method is very sensible to any changes the regional economy can have. We gave an alternative method of the grouping process under uncertainty.
Resumo:
We present a theory of the surface noise in a nonhomogeneous conductive channel adjacent to an insulating layer. The theory is based on the Langevin approach which accounts for the microscopic sources of fluctuations originated from trapping¿detrapping processes at the interface and intrachannel electron scattering. The general formulas for the fluctuations of the electron concentration, electric field as well as the current-noise spectral density have been derived. We show that due to the self-consistent electrostatic interaction, the current noise originating from different regions of the conductive channel appears to be spatially correlated on the length scale correspondent to the Debye screening length in the channel. The expression for the Hooge parameter for 1/f noise, modified by the presence of Coulomb interactions, has been derived
Resumo:
Electron transport in a self-consistent potential along a ballistic two-terminal conductor has been investigated. We have derived general formulas which describe the nonlinear current-voltage characteristics, differential conductance, and low-frequency current and voltage noise assuming an arbitrary distribution function and correlation properties of injected electrons. The analytical results have been obtained for a wide range of biases: from equilibrium to high values beyond the linear-response regime. The particular case of a three-dimensional Fermi-Dirac injection has been analyzed. We show that the Coulomb correlations are manifested in the negative excess voltage noise, i.e., the voltage fluctuations under high-field transport conditions can be less than in equilibrium.