Measurements of the XUV mass absorption coefficient of an overdense liquid metal

The increase in the XUV mass absorption coefficient of liquid aluminium, produced by high-power-laser shock-compression, is measured using XUV laser radiography. At a photon energy of 63 eV a change in the mass absorption coefficient by up to a factor of similar to2.2 is determined at densities close to twice that of solid and electron temperatures of the order of 1 eV. Comparison with hydrodynamic simulations indicate that the absorption coefficient scales with density as rho (1.3 +/-0.2).

Coefficient of consolidation by plotting velocity against displacement

A method is presented for estimating the initial compression, the final compression and the coefficient of consolidation from an observed, experimental consolidation response, using a plot of velocity versus displacement and the conventional Taylor plot of compression versus the square root of time. Goodness of fit measures indicate that the method produces good agreement between fitted and measured displacement values, at least up until the point where the impact of secondary compression on the overall displacement response becomes significant.

The coefficient of restitution of different representative types of granules

Gas fluidised beds have many applications in a wide range of industrial sectors and it is important to be able to predict their performance. This requires, for example, a deeper appreciation of the flow of the particles in such systems using both empirical and numerical methods. The coefficient of restitution is an important collisional parameter that is used in some granular flow models in order to predict the velocities and positions of the particles in fluidised beds. The current paper reports experimental data involving the coefficients of restitution of three different representative types of granule viz. melt, wet and binderless granules. They were measured at various impact velocities and the values were compared with those calculated from different theoretical models based on quasi-static contact mechanics. This required knowledge of the Young's moduli and yield stresses, which were measured quasi-statically using diametric compression. The results show that the current theoretical models for the coefficient of restitution explored here lead to either an over- or an under-estimation of the measured values. The melt granules exhibited the greatest values of the coefficient of restitution, Young's modulus and yield stress. The differences in these values were consistent with the nature of the interparticle bonding for each of the three granule types. A new model for the calculation of the coefficient of restitution of granular material was developed that takes account of the work hardening of the granules during impact. Generally, this model provides an improved prediction of the measured values. (c) 2006 Elsevier Ltd. All rights reserved.

Absorption coefficient of particulate matter on the south-west coast of Europe: a contribution to the validation of the MERIS-Medium Resolution Imaging Spectrometer sensor

Dissolved oxygen (DO) is one of the most important environmental variables of water quality, especially for marine life. Consequently, oxygen is one of the Chemical Quality Elements required for the implementation of European Union Water Framework Directive. This study uses the example of the Ria Formosa, a meso-tidal lagoon on the south coast of Portugal to demonstrate how monitoring of water quality for coastal waters must be well designed to identify symptoms of episodic hypoxia. New data from the western end of the Ria Formosa were compared to values in a database of historical data and in the published literature to identify long-term trends. The dissolved oxygen concentration values in the database and in the literature were generally higher than those found in this study, where episodic hypoxia was observed during the summer. Analysis of the database showed that the discrepancy was probably related with the time and the sites where the samples had been collected, rather than a long-term trend. The most problematic situations were within the inner lagoon near the city of Faro, where episodic hypoxia (<2 mg dm3 DO) occurred regularly in the early morning. These results emphasise the need for a balanced sampling strategy for oxygen monitoring which includes all periods of the day and night, as well as a representative range of sites throughout the lagoon. Such a strategy would provide adequate data to apply management measures to reduce the risk of more persistent hypoxia that would impact on the ecological, important natural resource. economic and leisure uses of this important natural resource.

Salting coefficient of hydroxybenzoic acids

The Setschenow parameter and thermodynamic parameters of transfer of 2- and 4- hydroxybenzoic acids from water to salt solutions have been reported. The data have been rationalised by considering the structure breaking effects of the ions of the salts, the localized hydrolysis model, the internal pressure theory and the theory of water structure due to Symons.

Estimating the reliability coefficient of tests in presence of missing values

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