Open Access Short Research Article

Igor Samkhan

In this paper we describe the peculiarities of the thermodynamics of the absorption heat transformers (AHTs) pointing to the possibility of examining the AHT models from the standpoint not only of the equilibrium thermodynamics, as it usually is, but also of the non-equilibrium one. In the well-known models of absorption refrigerators commonly represented by a combination of the reversible Carnot cycles, the absorption effects are not taken into account. At that, the mechanical energy required for operation of the refrigerator in such a model is superior to its real value, such as in cycles with solutions of H_{2}O / LiBr and NH_{3} / H_{2}O in several times. The examination of another AHT model represented by new cycles for a concurrent generation of electric power and cold shows that it also does not quite correlate with the earlier known models of the equilibrium (classical) thermodynamics. The evaluation of the performance of such cycles with the CH_{3}OH/LiBr and NH_{3}/LiNO_{3} solutions shows that under certain circumstances it can exceed the performance of the corresponding Carnot cycles. The application in this event of the non-equilibrium thermodynamics to a greater extent conforms to the physical model of the absorption cycles and creates prerequisites for further improvement of the performance of the combined cycles for generation of energy and cold.

Open Access Original Research Article

Kiranta Kumari, P. K. Gupta, G. Shanker

In this paper, we apply Differential Transform Method (DTM) coupled with Laplace Transform Method to solve wave equations and wave-like equations which arise very frequently in physical problems related to engineering and applied sciences. It is observed that the proposed technique works very well and gives rapidly converging series solutions. Several examples are given to re-confirm the efficiency of the suggested algorithm. The graphs were performed by using Mathematica-8.

Open Access Original Research Article

Mohamed Abdelsabour Fahmy

The time-stepping DRBEM modeling was proposed to study the 2D dynamic response of functionally graded anisotropic plate (FGAP) subjected to a moving heat source. The FGAP is assumed to be graded through the thickness. A Gaussian distribution of heat flux using a moving heat source with a conical shape is used for analyzing the temperature profiles. The main aim of this paper is to evaluate the difference between Green and Lindsay (G-L) and Lord and Shulman (L-S) theories of coupled thermo-elasticity in rotating FGAP subjected to a moving heat source. The accuracy of the proposed method was examined and confirmed by comparing the obtained results with those known previously.

Open Access Original Research Article

Piero Chiarelli

In this work the quantum gravitational equations are derived by using the quantum hydrodynamic approach that allows to define the energy-impulse tensor density of the gravitational equation. The outputs of the work show that the quantum uncertainty principle opposes itself to the gravitational collapse so that an equilibrium condition becomes possible. In this case, when the maximum collapse is reached, all the mass is inside the gravitational radius of the black hole if it is larger than the Planck's one.

The quantum-gravitational equations of motion show that the quantum potential generates a repulsive force that opposes itself to the gravitational collapse. The eigenstates in a central symmetric black hole realize themselves when the repulsive force of the quantum potential becomes equal to the gravitational one. The work shows that, in the case of maximum collapse, the mass of the black hole is concentrated inside a sphere whose radius is two times its Compton length. The mass minimum is determined requiring that the gravitational radius is bigger than or at least equal to the radius of the state of maximum collapse.

Open Access Original Research Article

D. L. Nascimento, A. L. A. Fonseca

We present a two-dimensional analysis of the two-electron problem which comes from the classical conservation theorems and from which we obtain a version of the Dirac equation for the helium atom. Approximate solutions for this equation are discussed in two different methods, although in principle it can be solved analytically. One method is variational, of the Hylleraas type, the execution of which is left for a later communication. In contrast, the other method will have a more complete treatment, in which the set of equations will be separated into its angular and radial components. Furthermore, an exact solution for the angular component will be displayed as well as an approximate solution for the radial component, valid only for the fundamental state of the atom.

Open Access Original Research Article

Antero Ollila

The author has developed a dynamic model (DM) to simulate the surface temperature change (ΔT) caused by the eruption of Mount Pinatubo. The main objectives have been 1) to test the climate sensitivity parameter (λ) values of 0.27 K/(Wm^{-2}) and 0.5 K/(Wm^{-2}), 2) to test the time constants of a simple first-order dynamic model, and 3) to estimate and to test the downward longwave radiation anomaly (ΔLWDN). The simulations show that the calculated ΔT of DM follows very accurately the real temperature change rate. This confirms that theoretically calculated time constants of earlier studies for the ocean (2.74 months) and for the land (1.04 months) are accurate and applicable in the dynamic analyses. The DM-predicted ΔT values are close to the measured value, if the λ-value of 0.27 K/(Wm^{-2}) has been applied but the λ-value of 0.5 K/(Wm^{-2}) gives ΔT values, which are about 100% too large. The main uncertainty in the Mount Pinatubo analyses is the ΔLWDN flux, because there are no direct measurements available during the eruption. The author has used the measured ERBS fluxes and has also estimated ΔLWDN flux using the apparent transmission measurements. This estimate gives the best and most consistent results in the simulation. A simple analysis shows that two earlier simulations utilising General Circulation Models (GCM) by two research groups are depending on the flux value choices as well as the measured ΔT choices. If the commonly used minimum value of -6 Wm^{-2} would have been used for the shortwave anomaly in the GCM simulations, instead of -4 Wm^{-2}, the ΔT values would differ from the measured ΔT values almost 100%. The main reason for this error seems be the λ-value of 0.5 K/(Wm^{-2}).