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Proposed Correlation (proposed + correlation)
Selected AbstractsPHYLOGENETICALLY NESTED COMPARISONS FOR TESTING CORRELATES OF SPECIES RICHNESS: A SIMULATION STUDY OF CONTINUOUS VARIABLESEVOLUTION, Issue 1 2003NICK J. B. ISAAC Abstract., Explaining the uneven distribution of species among lineages is one of the oldest questions in evolution. Proposed correlations between biological traits and species diversity are routinely tested by making comparisons between phylogenetic sister clades. Several recent studies have used nested sister-clade comparisons to test hypotheses linking continuously varying traits, such as body size, with diversity. Evaluating the findings of these studies is complicated because they differ in the index of species richness difference used, the way in which trait differences were treated, and the statistical tests employed. In this paper, we use simulations to compare the performance of four species richness indices, two choices about the branch lengths used to estimate trait values for internal nodes and two statistical tests under a range of models of clade growth and character evolution. All four indices returned appropriate Type I error rates when the assumptions of the method were met and when branch lengths were set proportional to time. Only two of the indices were robust to the different evolutionary models and to different choices of branch lengths and statistical tests. These robust indices had comparable power under one nonnull scenario. Regression through the origin was consistently more powerful than the t -test, and the choice of branch lengths exerts a strong effect on both the validity and power. In the light of our simulations, we re-evaluate the findings of those who have previously used nested comparisons in the context of species richness. We provide a set of simple guidelines to maximize the performance of phylogenetically nested comparisons in tests of putative correlates of species richness. [source] Characteristics of transient heat transfer during quenching of a vertical hot surface with a falling liquid filmHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2007Hiroaki Matsueda Abstract An experimental study has been conducted to elucidate characteristics of transient heat transfer during quenching of a vertical hot surface with a falling liquid film. The experiment was done at atmospheric pressure for the following conditions: an initial surface temperature from 200 to 400°C, a subcooling of 20, 80 K, average velocity of 0.52, 1.24 m/s, and the block material is copper and carbon steel. The surface temperature and heat flux are estimated from the measured temperatures in the block during the quench by a two-dimensional inverse solution. It follows that as the position of wetting advances downward, the position at which the heat flux becomes a maximum also advances downward. The time at which the position of maximum heat flux begins to move is one of the most important parameters and can be predicted by a proposed correlation. In addition, it is revealed that the maximum heat flux for copper depends on the length to which it occurs from the leading edge. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(6): 345, 360, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20167 [source] Gas Hold-Up in Stirred Tank Reactors in the Presence of Inorganic ElectrolytesTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2002Archis A. Yawalkar Abstract Gas hold-up (,G) in air-aqueous electrolyte solutions in stirred tank reactors (STR) is correlated using a relative gas dispersion parameter, N/Ncd and a surface tension factor (STF), (c/z)(d,/dc)2. For electrolyte concentration below transition concentration (ct) a single correlation in the form of ,G = f(N/Ncd, vvm, STF) shows good agreement with gas hold-up data over a wide range of system and operating conditions. Above ct no effect of STF on gas hold-up is observed and the correlation obtained is of the form ,G = f(N/Ncd, vvm). Data available in the literature on large STR show good fit with the proposed correlation. On a corrélé la rétention de gaz (,G) dans un mélange air-solutions d'électrolytes aqueuses dans des réacteurs à réservoir agité (RRA) à l'aide d'un paramètre de dispersion de gaz, N/Ncd, et d'un facteur de tension de surface (FTS), (c/z)(d,/dc)2. Pour une concentration d'électrolytes en-dessous de la concentration de transition (ct), une corrélation simple sous la forme ,G = f(N/Ncd, vvm, STF) montre un bon accord avec les données de rétention de gaz pour une vaste gamme de conditions de systèmes et de fonctionnement. Au-dessus de ct, on observe aucun effet du STF sur la rétention de gaz et la corrélation obtenue est de la forme ,G = f(N/Ncd, vvm). Les données disponibles dans la littérature scientifique sur des RRA de grande taille montrent un bon accord avec la corrélation proposée. [source] Influence of magnetic field on two-phase flow convective boiling of some refrigerant mixturesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2005Samuel M. Sami Abstract In this paper, an experimental study on the influence of magnetohydrodynamic (MHD) on heat transfer characteristics of two-phase flow boiling of some refrigerant mixtures in air/refrigerant horizontal enhanced surface tubing is presented. Correlations were proposed to predict the impact of MHD on the heat transfer characteristics such as average heat transfer coefficients, and pressure drops of R-507, R-404A, R-410A, and R-407C in two-phase flow boiling inside enhanced surface tubing. In addition, it was found that the refrigerant mixture's pressure drop is a weak function of the mixture's composition. It was also evident that the proposed correlations for predicting the heat transfer characteristics were applicable to the entire heat and mass flux, investigated in the present study. The deviation between the experimental and predicted value using new and improved correlations for the heat transfer coefficient and pressure drop were less than ±20%, for the majority of data. Copyright © 2005 John Wiley & Sons, Ltd. [source] FLOW PROPERTIES AND TUBE FRICTION FACTOR OF MILK CREAM: INFLUENCE OF TEMPERATURE AND FAT CONTENTJOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2010RODRIGO DIAZ FLAUZINO ABSTRACT The rheological behavior of milk cream was studied for different fat contents (0.10 to 0.31) and for a wide temperature range (2 and 87C) using a rotational rheometer. Newtonian behavior was observed, except for fat content between 0.20 and 0.31 and temperature between 2 and 33C, where viscoplastic behavior was remarkable. The rheological parameters (Newtonian viscosity, plastic viscosity and yield stress) and density were well correlated to temperature and fat content. Tube friction factor during flow of cream was experimentally obtained at various flow rates, temperatures and tube diameters (86 , Re , 2.3 × 104, 38 , ReB , 8.8 × 103, 1.1 × 103 , He , 6.7 × 103). The proposed correlations for density and rheological parameters were applied for the prediction of friction factor for laminar and turbulent flow of cream using well-known equations for Newtonian and viscoplastic flow. The good agreement between experimental and predicted values confirms the reliability of the proposed correlations for describing the flow behavior of cream. PRACTICAL APPLICATIONS This paper presents correlations for the calculation of density and rheological parameters (Newtonian viscosity, Bingham plastic viscosity and yield stress) of milk cream as functions of temperature (2,87C) and fat content (0.10,0.31). Because of the large temperature range, the proposed correlations are useful for process design and optimization in dairy processing. An example of practical application is presented in the text, where the correlations were applied for the prediction of friction factor for laminar and turbulent tube flow of cream using well-known equations for Newtonian and viscoplastic flow, which are summarized in the text. The comparison with experimental data obtained at various flow rates, temperatures and tube diameters showed a good agreement, which confirms the reliability of the proposed correlations. [source] | |||||||||||||