miércoles 16 de abril de 2014

 

 



Soy un nuevo usuario

Olvidé mi contraseña

Entrada usuarios

Lógica Matemáticas Astronomía y Astrofísica Física Química Ciencias de la Vida
Ciencias de la Tierra y Espacio Ciencias Agrarias Ciencias Médicas Ciencias Tecnológicas Antropología Demografía
Ciencias Económicas Geografía Historia Ciencias Jurídicas y Derecho Lingüística Pedagogía
Ciencia Política Psicología Artes y Letras Sociología Ética Filosofía
 

rss_1.0 Clasificación por Disciplina

Nomenclatura Unesco > (22) Física > (2213) Termodinámica
(2213.01) Cambios de estado (2213.02) Física de la transmisión del calor
(2213.03) Altas presiones (2213.04) Altas temperaturas
(2213.05) Teoría cinética (2213.06) Bajas temperaturas
(2213.07) Cambio de fase (2213.08) Técnicas de medida del calor
(2213.09) Equilibrios termodinámicos (2213.10) Relaciones termodinámicas
(2213.11) Fenómenos de transporte (2213.99) Otras (especificar)

Mostrando recursos 1 - 20 de 2.057

1. TERMODINÂMICA METALÚRGICA - Oliveira, Grace Élen Prietsch; Malfatti, Célia de Fraga; Pilla, Fernanda; Silva, Aline Lima da

2. TERMODINÂMICA INTERATIVA PARA BIÓLOGOS - Braun, Thomas; Cunha, Sílvio L. Souza; Braun, Luci F. Motter; Alves, Tanise Nascimento Colpo; Mendes, Maurício Rocha; Melo, Ana Carolina C. de

3. Laboratório de Física Moderna e Termodinâmica Interativa para Biólogos - Braun, Thomas; Braun, Luci F. Motter; Alves, Tanise Nascimento Colpo; Melo, Ana Carolina Carvalho de

4. Termodinâmica Metalúrgica I - Oliveira, Grace Élen Prietsch; Müller, Iduvirges Lourdes

5. Laboratório de Física Moderna e Termodinâmica Interativa para Biólogos - Braun, Thomas; Braun, Luci F. Motter; Alves, Tanise Nascimento Colpo; Melo, Ana Carolina Carvalho de

6. Al rescate del experimento recreativo en el contexto de la antropogogía de la termodinámica y la fisicoquímica - Sierra Cuartas, Carlos Eduardo
Con suma frecuencia nos topamos a cada rato con vocablos mal empleados en extremo, al punto que reclaman borrón y cuenta nueva a fin de que puedan recuperar sus significados y fuerzas prístinas. Uno de tantos vocablos mal avenidos con el usa que se le suele dar es el de pedagogía. Literalmente, este término alude a la educación de los niños, por lo que, en principio, carece de sentido su uso en el real contexto universitario. En sentido estricto, en una universidad propiamente dicha se pretende formar hombres en el sentido más amplio del término. Por lo anterior, se ha...

7. Estudo termodinâmico da formação de inclusões não-metálicas no aço SAE 52100 - Oliveira Junior, José Carlos de

8. Predição de Propriedades Termodinâmicas de Soluções Poliméricas - Simões, Renata Lorencini

9. Influence of drawing on gas transport mechanism in LLDPE films - García Villaluenga, Juan Pedro; Seoane Rodríguez, Benjamín
Micrographs obtained using scanning electron microscopy reveal that the drawing of co-extruded linear low-density polyethylene (LLDPE) films produces numerous changes in their surface. It is necessary to analyse the effect of these changes on gas transport in LLDPE films in order to test their efficiency in the packaging industry. Permeability of He, O-2, N-2 and CO2 has been measured in a temperature range from 25 to 85 degrees C using the variable-pressure technique with the time-lag method. Results show that the drawing process does not have a significant effect on the gas transport mechanism. The influence of drawing on the...

10. Diffusional characteristics of coextruded linear low-density polyethylenes prepared from different conditions of processing - García Villaluenga, Juan Pedro; Seoane Rodríguez, Benjamín; Compañ, V.
The permeability and diffusivity of oxygen, carbon dioxide, nitrogen, and helium have been obtained for a range of linear low density polyethylene (LLDPE) films prepared from the same raw materials but with different processing conditions. The measurements were carried out by means of a permeation technique over the temperature interval where the alpha-relaxation processes were observed in earlier studies. The temperature dependence of the permeability and diffusion coefficients of gases shows 2 well-differentiated regions in all films. The break temperature of these regions is approximately located at the same temperature as the alpha-relaxation takes place. Both the permeability and their...

11. Local thermodynamics and the generalized Gibbs-Duhem equation in systems with long-range interactions - Latella, Iván; Pérez Madrid, Agustín
The local thermodynamics of a system with long-range interactions in d dimensions is studied using the mean-field approximation. Long-range interactions are introduced through pair interaction potentials that decay as a power law in the interparticle distance. We compute the local entropy, Helmholtz free energy, and grand potential per particle in the microcanonical, canonical, and grand canonical ensembles, respectively. From the local entropy per particle we obtain the local equation of state of the system by using the condition of local thermodynamic equilibrium. This local equation of state has the form of the ideal gas equation of state, but with the...

12. Method for recovering CO2 by means of cao and the exothermic reduction of a solid - Abanades García, Juan Carlos; Murillo Villuendas, Ramón
[ES] La presente invención describe un procedimiento cíclico de captación de CO2 presente en corrientes, en el que esta corriente gaseosa se hace reaccionar con CaO sólido y un segundo sólido o la forma oxidada de dicho segundo sólido caracterizado porque tiene una reacción de reducción muy exotérmica. El calor desprendido en esta reacción de reducción se aprovecha para la descomposición de CaC03 formado. Las características termodinámicas y cinéticas del procedimiento de la presente invención hacen que sea idóneo para la eliminación del CO2 presente en corrientes gaseosas procedentes de procesos tales como el de reformado de hidrocarburos o el de combustión de combustibles...

13. Estudio del impacto de los conceptos fundamentales de la termodinámica en el desarrollo de la máquina térmica y el surgimiento de la revolución industrial - Jaramillo Suárez, Mauricio
El presente trabajo está pensado para orientar la comprensión que el impacto de los conceptos fundamentales de la termodinámica tuvo en el desarrollo de la máquina térmica y sus vínculos con el surgimiento de la revolución industrial. Es indudable la relevancia de la revolución industrial para la construcción del mundo en el que vivimos y, por lo tanto, es justificable el estudio de esta temática, más cuando su estudio es encausado por jóvenes que se inician en el mundo de las ciencias. Con tal fin, se muestra la evolución histórica del surgimiento de la máquina térmica, tratando de evidenciar los...

14. Permeation of carbon dioxide through multiple linear low-density polyethylene films - García Villaluenga, Juan Pedro; Seoane Rodríguez, Benjamín
We have investigated the effect of stacking on the permeation of carbon dioxide through multilayer LLDPE films. The measurements were carried out using samples made up of one, two, four, eight and 12 films, respectively, over the temperature interval of 25-85 degrees C. The results indicate that the permeability coefficient P of carbon dioxide does not show any variation on the number of films stacked. In contrast, the time lag values increase in a non-linear way with increasing the number of films in the samples. The analysis of these results, according to gas permeation models through multilayer systems, shows that...

15. Experimental estimation of gas-transport properties of linear low-density polyethylene membranes by an integral permeation method - García Villaluenga, Juan Pedro; Seoane Rodríguez, Benjamín
In recent years, we have investigated gas-transport phenomena in coextruded linear low-density polyethylene (LLDPE) membranes. For the most part, coextruded LLDPE membranes were investigated because of their excellent mechanical properties, which explain their extensive use in the packaging industry. Because of the small thickness of coextruded LLDPE membranes, significant errors can be involved in the determination of the diffusion coefficient of gases in the membranes by the time-lag method. To obtain more precise transport parameters for LLDPE membranes, we determined the permeability and diffusion coefficients for O-2, CO2, He, and N-2 from 298 to 348 K by employing an alternative...

16. Pervaporation of alcohols and methyl tert-butyl ether through a dense poly(2,6-dimethyl-1,4-phenylene oxide) membrane - García Villaluenga, Juan Pedro; Godino Gómez, Mari Paz; Khayet Souhaimi, Mohamed; Seoane Rodríguez, Benjamín; Mengual Cabezón, Juan Ignacio
Pervaporation separation and swelling experiments of methanol/methyl tert-butyl ether mixtures were performed by using a flat-sheet, dense poly(2,6-dimethyl-1,4-phenylene oxide) membrane prepared from a chloroform casting solvent. The effect of the feed composition on the membrane performance was described by the permeability of the components, the separation factor, and the sorption selectivity. The effect of the feed temperature on the separation was also studied, and the Arrhenius activation energy for permeability was determined over the whole range of feed composition. Pervaporation operations offered a maximum methanol selectivity of 5.4 and an overall normalized flux of 110 kg(.)mum/m(2)-h. Pervaporation and sorption experiments...

17. Annealing-induced enhancement of the gas diffusivity in coextruded LLDPE films investigated by positron lifetime spectroscopy - García Villaluenga, Juan Pedro; Monge, M. A.; Muñoz, A.; Leguey, T.; Pareja, R.
The annealing effect on coextruded linear low-density polyethylene (LLDPE) films has been investigated by positron annihilation lifetime spectroscopy (PALS). From the continuous positron lifetime distribution found for these films, the size distribution of the free-volume holes in the amorphous phase is calculated, as well as their fractional free volume. Also, diffusivity measurements at 298 K for He, O-2, and N-2 and X-ray diffraction measurements have been performed. The results reveal that annealing induces changes in the hole size distribution and in the amorphous fractional free volume of the films, along with an enhancement of the gas diffusivity. The correlation found...

18. Simulación de una planta de captura de CO2 basada en ciclos de carbonatación-calcinación - Martínez Berges, Isabel
A lo largo del presente proyecto ha quedado demostrado que este sistema de captura de CO2 mediante ciclos de carbonatación-calcinación cuenta con importantes ventajas que la sitúan como una de las opciones de captura con más potencial de aplicación a centrales existentes a medio plazo. Esta técnica de captura cuenta con una ventana de operación muy amplia que permite alcanzar resultados de reducción de emisiones y penalización energética muy diversos, pero todos ellos dentro de unos límites más que competitivos dentro de la situación actual de las técnicas de captura. Así pues es posible conseguir reducir las emisiones de CO2 de una central...

19. Anomalias dinâmicas e termodinâmicas em um modelo puramente repulsivo de gás de rede - Bertolazzo, Andressa Antonini
A água é uma das substâncias mais importantes em nosso planeta. São conhecidas atualmente 70 anomalias para a água. Uma das principais anomalias da água é a anomalia na densidade, através da qual a densidade da água aumenta com a diminuição da temperatura e atinge um máximo. É devido a ela que o gelo flutua em água e assim animais aquáticos sobrevivem quando a temperatura ambiente é muito baixa. Podemos citar também a anomalia na difusão, na qual a molécula de água se difunde mais rapidamente quando o sistema está mais denso. Acredita-se que as anomalias da água surgem devido...

20. Effects of pressure ratio and pressure difference on the gas permeation properties of rubbery and glassy membranes - García Villaluenga, Juan Pedro; Tabe Mohammadi, A.
The dependence of permeance and ideal separation factor on pressure ratio and pressure difference across the membrane was studied for a rubbery and a glassy membrane. The membranes tested included commercially available silicone rubber and polyimide. The experimental gases included helium, oxygen, and nitrogen. The experiments were performed using an automated constant volume gas permeation system where the rise of the downstream pressure was accurately converted into permeance using a computer program. All experiments were performed at room temperature.The results indicated that the permeance of the rubbery membrane increased with pressure ratio and decreased with pressure difference. The ideal separation...

Página de resultados:
 

Busque un recurso