1,720,979 research outputs found
Non-Singular Method of Fundamental Solutions based on Laplace decomposition for 2D Stokes flow problems
No full textIn this paper, a solution of Two-Dimensional (2D) Stokes flow problem, subject to Dirichlet and fluid traction boundary conditions, is developed based on the Non-singular Method of Fundamental Solutions (NMFS). The Stokes equation is decomposed into three coupled Laplace equations for modified components of velocity, and pressure. The solution is based on the collocation of boundary conditions at the physical boundary by the fundamental solution of Laplace equation. The singularities are removed by smoothing them on disks around them. The derivatives on the boundary in the singular points are calculated through simple reference solutions. In NMFS, no artificial boundary is needed, as in the classical Method of Fundamental Solutions (MFS). Numerical examples include driven cavity flow on a square, analytically solvable solution on a circle and channel flow on a rectangle. The accuracy of the results is assessed by comparison with the MFS solution, and analytical solutions. The main advantage of the approach is its simple, boundary only meshless character of the computations, and possibility of straightforward extension of the approach to Three-Dimensional (3D) problems, moving boundary problems and inverse problems
Numerical modelling of coupled groundwater flow and heat extraction from subsoil.
No full textThe subsoil can be used to store or extract heat for cooling or heating buildings, respectively, via a ground-coupled heat pump (GCHP) and the Ground heat exchanger (GHE) commonly used consist of HPDE pipes. The present contribution deals with the role of groundwater flow in the
performance of GHEs installed in vertical boreholes. A mathematical model in 2D space is
introduced, comprising a pair of partial differential equations of parabolic and elliptic type for soil temperature and ground water velocity field, respectively. The equations have been solved numerically by mean of Difference Finite method and Finite Element Method. The numerical model has been validated by comparing the results with the solutions of Moving infinite line source (MILS) model. The soil temperatures established in a sand around GHE operating in heat mode are
calculated either assuming a uniform velocity field and by taking into account the correct seepage around the GHEs to investigate how much the proper modelling of groundwater flow around the borehole affects the results
The effect of gas-surface model on thermal creep flow
No full textNumerical analysis of the nonlinear rarefied gas flow caused by temperature gradient in a direction tangential to the wall through a planar channel of finite length is carried out based on the S- model kinetic equation under a range of Knudsen number from free-molecular to slip regime. Cercignani- Lampis solid boundary condition is chosen at channel walls. An implicit scheme is applied; the algorithm is optimized via massive parallelization in both physical and velocity spaces. Results showed that the gas-surface scattering model plays distinguished role for highly rarefied conditions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Modelling of phase transformations in heat treatment processes
No full textThe two-domain approach and the phase-field approach, the two distinct physical models, for simulation of phase transformations in heat treatment processes are presented. Special attention is paid for linking data from a thermodynamic database to the physical models. The general procedure for linking thermodynamic data in the two-domain approach is presented. The interpolation by the radial basis functions of the thermodynamic data in the phase-field model is proposed. The physical models are applied to homogenisation of aluminum alloys. The JMatPro software for aluminium alloys is used as the thermodynamic database. The dissolution kinetics of stoichiometric and nonstoichiometric primary particles in binary and multicomponent aluminium systems is estimated. The isothermal diffusion-controlled dissolutions of the theta phase, S phase and Mg2Si phase in aluminium phase in Al-Cu, Al-Cu-Mg and Al-Mg-Si systems are computed, respectively. A comparison of the numerical results computed by the physical models are in excellent agreement. The very nice agreement between the numerical results computed by the phase-field model and previously derived the Vermolen model for the dissolution of multicomponent particles in homogenisation of aluminium alloys is demonstrated
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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