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Temperature Determination (temperature + determination)
Selected AbstractsA New Method of Electron Temperature Determination in Unmagnetized and Magnetized RF Plasmas without RF Compensating CircuitCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7-8 2004Y.-S. Choi Abstract Collected current versus applied voltage(I-V) curve of Langmuir probe in RF plasma is severely distorted by RF fluctuations leading to overestimation of electron temperature. RF compensation circuit has been used to obtain the undistorted I-V curve, yet it produces time-averaged one. A new and simple method is proposed to get time-resolved I-V curve by picking the synchronized RF signals with digital oscilloscope and Labview program. This technique is tested in magnetized helicon plasmas and unmagnetized capacitive coupled RF plasmas [source] Lower critical solution temperature determination of smart, thermosensitive N -isopropylacrylamide- alt -2-hydroxyethyl methacrylate copolymers: Kinetics and physical propertiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Mohammad M. Fares Abstract The lower critical solution temperatures (LCSTs) were verified and determined for different molar feed ratios of N -isopropylacrylamide (NIPAAm) and 2-hydroxyethyl methacrylate (HEMA) monomers with ultraviolet spectroscopy and differential scanning calorimetry techniques. Increases in the NIPAAm monomer content played a crucial role in the LCST, which increased up to 36.7°C at 50 mol %. However, a further increase in the NIPAAm monomer content steadily reduced the LCST, which decreased to 33°C at 100 mol % NIPAAm [i.e., pure poly(N -isopropylacrylamide)]. The rate of copolymerization, assessed by the conventional conversion (%),time method, and the apparent activation energies were determined. The reactivity ratios of the monomers, determined by the Kelen,Tudos and Fineman,Ross techniques, together with the results of an equation, showed that the copolymer which formed was an alternating copolymer. The Q,e values for the NIPAAm monomer were determined. The equation showed the linear Arrhenius behavior of ln(r1r2) versus the reciprocal of the temperature (where r1 and r2 are the reactivity ratios of NIPAAm and HEMA, respectively): the activation energy difference [i.e., (E12 + E21) , (E11 + E22), where E12, E21, E11, and E22 are various activation energies] was found to be ,109 kJ/mol. The copolymers were characterized with 1H-NMR, 13C-NMR, Fourier transform infrared, ultraviolet,visible, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy techniques. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Comparison of Raman spectroscopic methods for the determination of supercooled and liquid water temperatureJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2005Dubravko Risovi Abstract Raman spectroscopy provides an efficient method for non-contact determination of liquid water temperature with high spatial resolution. It can be also used for remote in situ determination of subsurface water temperature. The method is based on temperature-dependent changes of the molecular OH stretching band in the Raman spectra of liquid water. These in turn are attributed to a decrease in intermolecular hydrogen-bonding interactions with increase in temperature. Here, the results of an experimental study employing three different approaches in the determination of temperature from recorded OH stretching band in the Raman spectra of liquid and supercooled water are presented and discussed. The first two methods are based on deconvolution of the spectral band into Gaussian components whose intensities and associated specific spectral markers are temperature dependent, and the third approach is based on Raman difference spectroscopy (RDS). The presented measurements were conducted on distilled and deionized supercooled and liquid water in the temperature range between ,12.5 and +32.5 °C. The results are compared in terms of linearity of response, sensitivity and accuracy. It is shown that the method based on RDS even in the supercooled temperature range provides better accuracy (the standard deviation from the true temperature is ±0.4 K) and linearity in temperature determination than more complicated methods based on Gaussian deconvolution of the OH stretching band. Copyright © 2005 John Wiley & Sons, Ltd. [source] Seismological studies of ZZ Ceti stars , I. The model grid and the application to individual starsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008B. G. Castanheira ABSTRACT We calculate and explore an extensive adiabatic model grid for pulsating white dwarfs with hydrogen-dominated atmospheres, the ZZ Ceti stars. We also compared the computed modes with the observed ones for five ZZ Ceti stars that are a representative sample of the whole class of pulsators. We describe our new approach for seismological studies, using the relative observed amplitudes to give weights for the periods in the fit and the external mass and temperature determinations as a guide. Our seismological study is clear evidence that seismology is indeed a powerful tool in the study of stellar structure and evolution. [source] | ||||||||||