Search results for "equation"

High-pressure structural and elastic properties of Tl2O3

2014

The structural properties of Thallium (III) oxide (Tl2O3) have been studied both experimentally and theoretically under compression at room temperature. X-ray powder diffraction measurements up to 37.7 GPa have been complemented with ab initio total-energy calculations. The equation of state of Tl2O3 has been determined and compared to related compounds. It has been found experimentally that Tl2O3 remains in its initial cubic bixbyite-type structure up to 22.0 GPa. At this pressure, the onset of amorphization is observed, being the sample fully amorphous at 25.2 GPa. The sample retains the amorphous state after pressure release. To understand the pressure-induced amorphization process, we h…

On the equation of state for thermal polymer solutions and melts with attractive interaction

1996

We perform Monte Carlo simulations of a lattice model for polymer melts, i. e., the bond fluctuation model in three dimensions. By using an energy parameter that prefers relatively long bonds, the model exhibits a glass transition at low temperatures, in close qualitative similarity to experiment. We modify this model by adding an attractive interaction of variable strength. We demonstrate that a small interaction strength has only a very small effect on the static properties of the melt. For a fixed strength of the potential, the chemical potential is measured by a modified particle-insertion method over a large range of temperatures and densities. The osmotic pressure is obtained by therm…

Experimental P-T-ro Measurements of Supercritical Mixtures of Carbon Dioxide, Carbon Monoxide, and Hydrogen and Semiquantitative Estimation of Their …

2007

The P-T-ρ behavior of the CO2-CO-H2 system was studied in the supercritical region under operative conditions close to those adopted to perform hydrogenation and hydroformylation reactions in dense CO 2, thus providing new interesting information on this fluid mixture. Experiments were performed in a fixed volume reactor in the temperature range from 298 K to 343 K changing the density and the composition of the fluid phase. The one-component (Hildebrand) solubility parameter of the mixture was estimated from experimentally measured P vs T profiles, and its dependence on the density and composition of the system was analyzed to study the antisolvent effect of the permanent gases. We have fo…

Pressure Impact on the Stability and Distortion of the Crystal Structure of CeScO3

2017

[EN] The effects of high pressure on the crystal structure of orthorhombic (Pnma) perovskite-type cerium scandate were studied in situ under high pressure by means of synchrotron X-ray powder diffraction, using a diamond-anvil cell. We found that the perovskite-type crystal structure remains stable up to 40 GPa, the highest pressure reached in the experiments. The evolution of unit-cell parameters with pressure indicated an anisotropic compression. The room-temperature pressure¿volume equation of state (EOS) obtained from the experiments indicated the EOS parameters V0 = 262.5(3) Å3 , B0 = 165(7) GPa, and B0¿ = 6.3(5). From the evolution of microscopic structural parameters like bond distan…

Extended Skyrme Equation of State in asymmetric nuclear matter

2015

We present a new equation of state for infinite systems (symmetric, asymmetric, and neutron matter) based on an extended Skyrme functional that has been constrained by microscopic Brueckner-Bethe-Goldstone results. The resulting equation of state reproduces the main features of microscopic calculations very accurately and is compatible with recent measurements of two times Solar-mass neutron stars. We provide all necessary analytical expressions to facilitate a quick numerical implementation of quantities of astrophysical interest.

Thermodynamics of Rubber Elasticity

2001

A thermodynamic study of an isotropic rubber band under uniaxial stress is presented on the basis of its equation of state. The behavior of the rubber band is compared with both that of an ideal elastomer and that of an ideal gas, considering the generalized Joule's law as the ideality criterion.

A modular approach in teaching thyristor rectifiers with equation-oriented softwares

2014

This article is devoted to some issues of teaching power electronics in university courses. In the modern education system the students are expected to be no longer subject of passive learning, but that, within a certain extent, they collaborate in their training interactively with the teacher to develop the applications and the topics of the studied framework. For this purpose, this article presents a modular approach for teaching module regarding three-phase thyristor rectifiers. A simulator based on the MATLAB equation solver has been developed by considering the detailed physical operation of such converters. In particular, the realized simulator takes various aspects into account, incl…

Improved GNSS positioning exploiting a vehicular P2P infrastructure

2010

This paper considers the possibility to exploit external altitude measurements to improve the performance of a Kalman based GNSS receiver. The altitude measurements are provided by means of a peer to peer network, that is supposed to be based on the evolution of the 802.11 standard for the vehicular environment, namely the WAVE (802.11p). The performance of such a system are investigated for different characteristics of the aiding measurement and for a different number and disposals of the aiding peers. The aiding measurement is obtained starting from the altitude measurements that the other peers in the network send to the aided user. The experiments highlight the need for a parameter that…

On the use of SPH for Mechanical Engineering structural analyses: an elastic linear case

2011

Existence and uniqueness of solution to several kinds of differential equations using the coincidence theory

2015

The purpose of this article is to study the existence of a coincidence point for two mappings defined on a nonempty set and taking values on a Banach space using the fixed point theory for nonexpansive mappings. Moreover, this type of results will be applied to obtain the existence of solutions for some classes of ordinary differential equations. Ministerio de Economía y Competitividad Junta de Andalucía