Search results for "THERMODYNAMICS"
showing 10 items of 2774 documents
Ageing of isotactic polypropylene due to morphology evolution, experimental limitations of realtime density measurements with a gradient column
2006
Abstract Ageing in crystalline polymers is responsible for the deterioration of physical properties leading, for example, to a decrease in toughness and to dimensional changes that are to some extent responsible for warpage and scrap production in injection molding. Since, it depends on the mutual transformation of stable and metastable phases, being always related to changes in morphological organization, it is here preferred to call it ‘Morphological ageing’. Although, one would expect the ageing regime to be determined by the complex morphology with amorphous phases of different mobility and eventually multiple crystalline phases, transformed into each other at an associated transition, …
Liquid–liquid equlibria of the mixture linalool+ethanol+water at different temperatures
2005
Abstract In this work, experimental liquid–liquid equilibria (LLE) data of the linalool + ethanol + water system are presented. The LLE of this system has been measured at 293.15, 303.15, 313.15 and 323.15 K. The equilibrium data presented are correlated using NRTL and UNIQUAC equations. Finally, the reliability of these models is tested by comparison with experimental results.
Measurements and correlation at different temperatures of liquid–liquid equilibria of 2-butanol or 2-methyl-2-butanol+1,2,3-propanetriol+water ternar…
2014
Abstract In this work, the experimental liquid–liquid equilibria (LLE) data of 2-methyl-2-butanol + 1,2,3-propanetriol (glycerol) + water and 2-butanol + 1,2,3-propanetriol (glycerol) + water systems at different temperatures are presented. The LLE of the systems has been measured between 283 and 323 K. The NRTL and UNIQUAC models were applied to the ternary systems. The interaction parameters obtained from both models successfully correlated the equilibrium compositions. The experimental tie lines were compared to the values predicted by the UNIFAC method. Finally, the solvent capability of both alcohols was checked in order to separate the mixture formed by glycerol and water.
Wireless power transfer system stability analysis for E-bikes application
2019
The present work reports the stability analysis of an Inductive Coupled Power Transfer (ICPT) System coupled to an electrical bike. The study has focused on two coupled coils with circular geometry and vertical disposition. In the first part of the work, the theoretical aspects related to the stability of wireless power systems are handled. In the second part, performing several simulations, varying the features of the considered configuration, the stability is looked for. In order to perform this process, the Ansys Maxwell software has been used, performing 3D simulations.
Heat to electricity conversion by cold carrier emissive energy harvesters
2015
This paper suggests a method to convert heat to electricity by the use of devices called cold carrier emissive energy harvesters (cold carrier EEHs). The working principle of such converters is explained and theoretical power densities and efficiencies are calculated for ideal devices. Cold carrier EEHs are based on the same device structure as hot carrier solar cells, but works in an opposite way. Whereas a hot carrier solar cell receives net radiation from the sun and converts some of this radiative heat flow into electricity, a cold carrier EEH sustains a net outflux of radiation to the surroundings while converting some of the energy supplied to it into electricity. It is shown that the…
Numerical study of photolithography system: electromagnetic differential method
2004
The R-matrix propagation algorithm is incorporated into the differential method to achieve an extended capability for modelling a photolithography systems. We show throughout this work the ability of the R-matrix algorithm and differential method to analyse gratings of arbitrary depth, profile, and conductivity without encountering numerical instabilities. We calculate the field intensity and the transmitted amplitudes in the 0 and −1 orders below different masks. We study also the influence of the various parameters (incidence, groove spacing, groove depth and index of refraction) on the field intensity maps and the transmittivity power. These results agree with the experimental patent: we…
Potentialities of microfibers for non linear optics
2010
Micro- and nanofibers present attractive optical properties and may be used in a variety of structures and devices. We report in this work the first global study on the non linear properties of these microfibers: an adequate source is built and its characteristics are described, our first results with a silica loop resonator are presented. Third harmonic generation is obtained in these conditions, however, the low intrinsic non linear index prevents the generation of large non linear effects. The use of highly non linear materials, such as soft glasses, is therefore discussed, with their potentialities and the challenges their integration with standard microfibers represent.
Spectroscopic studies of Tl containing high frequency electrodeless lamps
2014
In this work we estimate gas temperature from OH rotational spectrum at 306.4 nm and C 2 Swan band at 516.5 nm in thallium containing lamps during two working regimes: stable generation and self-modulation regime. The usage of both molecules allowed us to estimate gas temperature in different zones of the discharge. The measurement results show that the central part of discharge has temperature higher for about 400 K than in vicinity of lamp inner walls. The measurement results of self-modulation regime showed that rotational temperature variations are similar to that of atomic and molecular spectral line intensities with period being around 1 minute. More detailed analysis of temporal beha…
Gelchromatographische refraktionierung, molekulargewichtsabhängigkeit der axialen dispersionsfunktion
1979
The knowledge of axial dispersion is necessary for the determination of molecular weight distributions from gel permeation chromatograms. This work deals with the determination of the axial dispersion function and its dependence on the molecular weight using refractionation method. The results of a number of fractionated and unfractionated samples of polystyrene reveal that peak dispersion in GPC arises mainly from diffusion in the stationary phase on the basis of the theoretical expression proposed by Kubin.
Über die möglichkeiten zur bestimmung von mischungsenthalpien und -volumina aus der molekulargewichtsabhängigkeit der kritischen entmischungstemperat…
1977
Cloud-point curves and critical curves (Tc = f(p)) have been measured for the system trans-decahydronaphthalene/polystyrene and three different molecular weights of the polystyrene component (2,5 · 106; 3,9 · 105; 1,1 · 105). It turned out that by variation of the pressure the metastable region can be investigated up to the spinodal curve. A comparison of the theta-temperatures and the enthalpy contributions χH (to the Flory-Huggins interaction parameter χ) resulting from the measured critical temperatures according to Shultz-Flory, with the corresponding directly obtained literature data, demonstrates that, although the extrapolation of Tc to infinite molecular weight is feasible, χH obtai…