Applications of the hard sphere DeSantis equation of state to the estimation of the density of compressed alternative refrigerants.

19th International Congress of Refrigeration. Proceedings The Hague, the Netherlands, august 20-25, 1995.The density of liquid refrigerants is very important for the design of compression cycles in the refrigeration and air conditioning industries. The increasing concern with the environmental protection leads the governments to legislate in order to banish in the short term the use of the CFC's and in the long run the HCFC's. Considering those decisions, the industries need to find new replacements for those compounds, and suitable substitutes seam to be HFC's, fluorinated ethers, their mixtures and mixtures with small quantities of HCFC's. The only problem in using those alternative refrigerants is the lack of knowledge about their properties. Among them, the density is one of the most important. It is the propose of this paper to show the use of a model that allows the user to estimate the liquid density for the refrigerants. The uncertainty of this model is of ± 2.0 % for reduced values of temperature less then 0.95 and reduced values of density less then 1.0. This model needs the information for the critical parameters and the pressure of the saturated liquid-vapour line. The Hard-Sphere DeSantis equation of state Ref. /1/ is use to give physical support to the model. The corrections to the attractive and repulsive part, a and b, have been calculated from a few experimental pure refrigerants Ref. /1/ (HCFC 152a, HCFC 22, HCFC 142b, HCFC 123, HCFC 114)

Prediction of the vapor pressure of environmentally acceptable halocarbons.

Copyright © 2000 Plenum Publishing Corporation.The vapor pressure and its dependence on temperature of halocarbons for 0.002< p R<1 have been analyzed in terms of universal behavior. Results for CFC-114, HCFC-123, HCFC-141b, HCFC-142b, HCFC-143a, HFC-23, HFC-32, HFC-134, HFC-125, HFC-134a, and HFC-152a for reduced temperatures between 0.55 and 1.0 show that the reduced vapor pressure can be expressed as a function of 1−T R by a Padé approximant. Deviations of the correlated data from the universal function do not amount to more than ±0.06 MPa, with an average deviation of 0.025 MPa. Predictions of the saturation vapor pressures of HCFC-124, HCFC-225ca, and HCFC-225cb, which are the systems used to test the capability of this scheme, agree within 0.025 MPa, that is, within the accuracy of the corresponding states correlation. However, for HFC-236ea, the deviations are as large as -0.07 MPa. The present scheme can be used to calculate the Pitzer acentric factor, and an average value of ω=0.269±0.015 is obtained for all the fluids

Stories and gaps : a study of narrative, discourse and musical awareness in a group of year six children's responses to music.

Music educators in the classroom aim to expose students to a variety of styles and genre of music through active listening. Engaging children in listening to music that is unfamiliar to them is problematic. This study sets out to explore what Year Six children respond to in the music they prefer and how this compares to their responses to examples of 'classical' music in an effort to find areas of commonality and transferability. A constructivist perspective underpins this study. In examining the children's responses to music in their own words, their understandings about music and how it shapes their lives becomes evident. Case study is used to examine the listening responses of Year Six children. Children express in their own terms what they listen to and for within music: music of their own choice, and then "classical" music. They share their expectations and give examples of "good" music. The findings that emerge from this study fall into two broad themes: those relating to children's choices, and those that relate to the nature and importance of the discourses about listening to music within the educational setting. These findings have a number of implications. Firstly, they indicate the importance of "stories" the children gained from the music listened to. Secondly, they suggest the significance of the relationship children form with music. Thirdly, they mark the importance of an awareness of the different perspectives and cultural settings from which music listening and appreciation is viewed. This study focuses on Year Six children's responses to and relationships with music. However, while it examines a single aspect of music education at this level, the implications may be explored within other levels and curriculum areas

On a shallow water model for the simulation of turbidity currents

We present a model for hyperpycnal plumes or turbidity currents that takes into account the interaction between the turbidity current and the bottom, considering deposition and erosion effects as well as solid transport of particles at the bed load due to the current. Water entrainment from the ambient water in which the turbidity current plunges is also considered. Motion of ambient water is neglected and the rigid lid assumption is considered. The model is obtained as a depth-average system of equations under the shallow water hypothesis describing the balance of fluid mass, sediment mass and mean ow. The character of the system is analyzed and numerical simulations are carried out using finite volume schemes and path-conservative Roe schemes

Influencia del tipo de directivo sobre la creación de valor: una aplicación a las empresas diversificadas españolas

El objetivo básico de este trabajo es analizar la relación existente entre el tipo de directivo que adopta la decisión de diversificar y la riqueza generada tras acometer dicho proceso de desarrollo. Para ello, tras revisar la literatura correspondiente, se distinguen dos grupos de directivos, agentes y servidores, en función de sus características psicológicas y situacionales. Seguidamente se contrasta una hipótesis que defiende que las empresas diversificadas gobernadas por directivos tipo servidor obtienen niveles de rentabilidad financiera significativamente superiores que aquellas a cargo de directivos tipo agente. Los resultados obtenidos a partir de una muestra de 118 empresas diversificadas españolas permiten verificar tal hipótesis e indican la conveniencia de contratar servidores para salvaguardar el valor de los accionistas.The main purpose of this paper is to analyse the existing relationship among the type of manager that chooses to diversify and the wealth effect of diversification. For that, after revising the corresponding literature, we cluster the managers en two different groups according to their psychological and situational characteristics. After that, we have tested one hypotheses related to the diversified firms managed by stewards reach bigger profitability than those controlled by agents. Results support that hypotheses on a sample of 118 Spanish diversified firms and affirm the convenience of contracting stewards to safeguard the shareholders´ value

A HLLC scheme for nonconservative hyperbolic problems. Application to turbidity currents with sediment transport.

This paper focuses on the generalization of the HLLC Riemann solver for nonconservative problems. First, the general ideas of the extension of the HLLC solvers for nonconservative systems are discussed. Then, two particular HLLC solvers are described for a turbidity current model with sediment transport. Some results concerning the positivity of the corresponding schemes are presented. Several numerical tests are performed to compare the two HLLC solvers among them and with a Roe method

Working Group Reports

Final report of the five Working Group (WG) meetings have been held in the frame of Nanouptake during the whole duration of the Actio

Efecto de la política nacional de subsidios a la innovación según la localización de la empresa

Este trabajo se fundamenta en la reciente visión de que la actividad innovadora es un fenómeno territorial estimulado por la cooperación entre actores e infraestructuras locales. El objetivo del trabajo es determinar sí la localización de una empresa influye sobre el efecto que la política nacional de innovación tiene sobre su intensidad en I+D. El análisis está dirigido a comparar el efecto de esta política entre empresas ubicadas en Madrid, Cataluña y el País Vasco, regiones que concentran cerca del 70% de la actividad innovadora en España. El tipo de análisis empleado permite llegar a una situación próxima que soluciona importantes problemas metodológicos en la práctica de la evaluación de la política. Los resultados permiten concluir que la región ejerce un importante efecto diferenciador en el resultado final de esta política. Por lo tanto, este estudio recomienda incluir la localización de la empresa en futuras prácticas de evaluación.Este trabajo se fundamenta en la reciente visión de que la actividad innovadora es un fenómeno territorial estimulado por la cooperación entre actores e infraestructuras locales. El objetivo del trabajo es determinar sí la localización de una empresa influye sobre el efecto que la política nacional de innovación tiene sobre su intensidad en I+D. El análisis está dirigido a comparar el efecto de esta política entre empresas ubicadas en Madrid, Cataluña y el País Vasco, regiones que concentran cerca del 70% de la actividad innovadora en España. El tipo de análisis empleado permite llegar a una situación próxima que soluciona importantes problemas metodológicos en la práctica de la evaluación de la política. Los resultados permiten concluir que la región ejerce un importante efecto diferenciador en el resultado final de esta política. Por lo tanto, este estudio recomienda incluir la localización de la empresa en futuras prácticas de evaluación