82 research outputs found

    Darcy-Brinkman free convection about a wedge and a cone subjected to a mixed thermal boundary condition

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    The Darcy-Brinkman free convection near a wedge and a cone in a porous medium with high porosity has been considered. The surfaces are subjected to a mixed thermal boundary condition characterized by a parameter m; m=0, 1, ∞ correspond to the cases of prescribed temperature, prescribed heat flux and prescribed heat transfer coefficient respectively. It is shown that the solutions for different m are dependent and a transformation group has been found, through which one can get solution for any m provided solution for a particular value of m is known. The effects of Darcy number on skin friction and rate of heat transfer are analyzed

    Unsteady Flow Between Two Oscillating Plates

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    The flow of an incompressible viscous fluid between two infinite harmonically oscillating plates is considered, when an oscillatory body force (having the same frequency as that of the plates) is applied in the direction of motion problem, detailed analytical expressions for the velocity field of the fluid, volume flow rate and stress at the plates have been obtained. It is found that the fluid velocity oscillates in time with the same frequency as that of the plates or the body force, but with a phase difference

    DAS STRAHLUNGSVERMÖGEN DER DIESELMOTORISCHEN FLAMME

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    Stability of binary complexes of Pb(II), Cd(II) and Hg(II) with maleic acid in TX100-water mixtures

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    Binary complexes of maleic acid with toxic metal ions such as Pb(II), Cd(II) and Hg(II) have been studied in 0.0-2.5% v/v tritonX-100 (TX100) - water media at 303 K  at an ionic strength of 0.16 M. The active forms of the ligand are LH2, LH- and L2-. The derived ‘best fit’ chemical speciation models are based on crystallographic R-factors, χ2 and Skewness and Kurtosis factors. The predominant species formed are of the type ML2, ML2H and ML3. The trend in variation of complex stability constants with change in the mole fraction of the medium is explained on the basis of prevailing electrostatic and non-electrostatic forces. The species distribution as a function of pH at different compositions of TX100-water mixtures and plausible speciation equilibria are presented and discussed. KEY WORDS: Maleic acid, TritonX-100, Toxic metal ions, Mole fraction, Binary complexes Bull. Chem. Soc. Ethiop. 2014, 28(3), 383-391.DOI: http://dx.doi.org/10.4314/bcse.v28i3.

    Electronic and Vibrational Absorption Spectra in Nickelblodite

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    Online) An Open Access

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    ABSTRACT Two models are said to be non-nested models, if one can not be derived as a special case of another. Much attention in classical statistics has been devoted to testing non-nested regression models. Within the classical framework, there are three alternative general approaches to test non-nested models namely, the use of specification error tests; the use of comprehensive model method; and the use of procedures based upon Keywords: Non-Nested Model, Studentized Residuals INTRODUCTION The selection of a good model is an art. The basic idea in statistics is how to select a good model for the purpose of the study. Once a model is given, however, there are statistical criteria to judge whether the given model is bad or not. Since, many models can explain the same set of data about equally well, a given set of data can be used to screen out bad models but not to generate good models, whatever statistical techniques are used. The subject of model selection is treated in classical statistics, which deals with the two topics of estimation and testing of hypotheses. The problem of determining an appropriate model based on a subset of the original set of variables contains three basic ingredients namely, i) The computational technique used to provide the information for the analysis; ii) The criterion used to analyze the variables and select a subset, if that is an appropriate; and iii) The estimation of coefficients in the final model. In model selection criteria, there may be two important problems those arising from nested and nonnested model structures. The nested models arise with, for instance, two models specified in such a way that one model is a special case of the other; the non-nested model arise when neither model follows as a special case of the other. The model selection criterion is a problem of choice among competing models. The choice of a model follows some preliminary data search. In the context of the linear model, it leads to the specification of explanatory variables that appear to be the most important on prior grounds. Often, some explanatory variables appear in one model and reappear in another model gives rise to the nested models; often again neither model, in the case of two models appears to be a special case of the other model gives rise to the non-nested models. In the process of choosing models, statisticians have developed a variety of diagnostic tests. These tests have been classified into two categories: (i) Tests of Nested Regression models, and (ii) Tests of Non-nested Regression models If a modelI can be derived as a special case of another modelII then modelI is said to be nested model within modelII. Two models are said to be non-nested models, if one can not be derived as a special case of another

    Arthropod venom Hyaluronidases: biochemical properties and potential applications in medicine and biotechnology

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    Magnetogasdynamic thrust bearing with an axial pinch

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