Influência do parcelamento de diferentes fontes de nitrogênio no teor de proteína em milho QPM e normal.

bitstream/item/58850/1/Pesq.And.-36-1.pd

Some thoughts about nonequilibrium temperature

The main objective of this paper is to show that, within the present framework of the kinetic theoretical approach to irreversible thermodynamics, there is no evidence that provides a basis to modify the ordinary Fourier equation relating the heat flux in a non-equilibrium steady state to the gradient of the local equilibrium temperature. This fact is supported, among other arguments, through the kinetic foundations of generalized hydrodynamics. Some attempts have been recently proposed asserting that, in the presence of non-linearities of the state variables, such a temperature should be replaced by the non-equilibrium temperature as defined in Extended Irreversible Thermodynamics. In the approximations used for such a temperature there is so far no evidence that sustains this proposal.Comment: 13 pages, TeX, no figures, to appear in Mol. Phy

Questioning the validity of non-extensive thermodynamics for classical Hamiltonian systems

We examine the non-extensive approach to the statistical mechanics of Hamiltonian systems with $H=T+V$ where $T$ is the classical kinetic energy. Our analysis starts from the basics of the formalism by applying the standard variational method for maximizing the entropy subject to the average energy and normalization constraints. The analytical results show (i) that the non-extensive thermodynamics formalism should be called into question to explain experimental results described by extended exponential distributions exhibiting long tails, i.e. $q$-exponentials with $q>1$, and (ii) that in the thermodynamic limit the theory is only consistent in the range $0\leq q\leq1$ where the distribution has finite support, thus implying that configurations with e.g. energy above some limit have zero probability, which is at variance with the physics of systems in contact with a heat reservoir. We also discuss the ($q$-dependent) thermodynamic temperature and the generalized specific heat.Comment: To appear in EuroPhysics Letter