124,678 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Energy-conserving discretization methods for the incompressible Navier-Stokes equations : application to the simulation of wind-turbine wakes
Get PDFIn this thesis numerical methods are developed for the simulation of turbulent flows governed by the incompressible Navier-Stokes equations. This is inspired by the need for accurate and efficient computations of the flow of air in windturbine wakes. The state-of-the-art in computing such flows is to use Large Eddy Simulation (LES) as a turbulence model. In LES the Navier-Stokes equations are filtered such that only the large, energy-containing scales of motion are simulated - the smaller scales are modeled. However, even with such a model, LES simulations remain expensive (not only in wind energy applications) and are typically ‘under-resolved’: the mesh is too coarse to resolve all important scales. Thus, an ongoing challenge is to construct numerical methods that are stable and accurate even on coarse meshes, and do not introduce false (‘artificial’) diffusion that can destroy the delicate features of turbulent flows. The approach taken is to construct high-order energy-conserving discretization methods. Such methods mimic an important property of the continuous incompressible Navier-Stokes equations, namely the conservation of kinetic energy in the limit of vanishing viscosity. The energy equation is, for incompressible flows, derived from the equations for conservation of mass and momentum. An energy-conserving discretization method is nonlinearly stable, independent of mesh, time step, or viscosity, and does not introduce artificial diffusion. The first part of this thesis addresses spatially energy-conserving discretization methods, in particular second and fourth order finite volume methods on staggered cartesian grids. Special attention is paid to the proper treatment of boundary conditions for high order methods. New boundary conditions are derived such that the boundary contributions to the discrete energy equation mimic the boundary contributions of the continuous equations. An important theoretical result is obtained: higher order energy-conserving finite volume discretizations are limited to second order global accuracy in the presence of boundaries. On properly chosen non-uniform grids, designed such that the maximum error is not at the boundary, fourth order accuracy can be recovered. The second part of this thesis addresses time integration of the incompressible Navier-Stokes equations with Runge-Kutta methods. Runge-Kutta methods are often applied to the spatially discretized incompressible Navier-Stokes equations, but order of accuracy proofs that address both velocity and pressure are missing. By viewing the spatially discretized Navier-Stokes equations as a system of differential-algebraic equations the order conditions for velocity and pressure are derived. Based on these conditions new explicit Runge-Kutta methods are derived, that have high-order accuracy for both velocity and pressure. These explicit methods are not strictly energy-conserving but can be efficient, depending when the time step is determined by accuracy instead of stability. However, for truly energy-conserving Runge-Kutta methods implicit methods need to be considered. High-order Runge-Kutta methods based on Gauss quadrature are proposed. In particular, the two-stage fourth order Gauss method is investigated and combined with the fourth order spatial discretization, resulting in a fourth order energy-conserving method in space and time, which is stable for any mesh and any time step. A disadvantage of the Gauss methods is that they are less suitable for integrating the diffusive terms, since they lack L-stability. Therefore, new additive Runge-Kutta methods are investigated: the diffusive terms are integrated with an L-stable Runge-Kutta method, and the convective terms with an energy-conserving Runge-Kutta method, both based on the same quadrature points. Unfortunately, their low stage order does not make them more efficient than the original Gauss methods. In practice, the second order Gauss method (implicit midpoint) is therefore the preferred time integration method. The third part of this thesis addresses actuator methods. Actuator methods are simplified models to represent the effect of a body (such as a wind turbine) on a flow field, without requiring the actual geometry of the body to be taken into account. Actuator forces introduce discontinuities in flow variables and should therefore be treated carefully. A new immersed interface method in finite volume formulation is proposed, which leads to a sharp, non-diffusive, representation of the actuator. This does not require the choice for a discrete Dirac function and regularization parameter. The ideas put forth in this thesis have been implemented in a new parallel 3D incompressible Navier-Stokes solver: ECNS (Energy-Conserving Navier-Stokes solver). The resulting method combines stability, no numerical viscosity and high-order accuracy. This makes it a valuable tool for simulating turbulent flow problems governed by the incompressible Navier-Stokes equations and suitable for the development and comparison of LES models. For the particular case of wind-turbine wake aerodynamics a number of simulations have been performed: flow over a wing as a model for a wind turbine blade, and flow through an array of actuator disks representing a wind farm
Pragmatic Case Studies as a Source of Unity in Applied Psychology
No full textTo unify or not to unify applied psychology: that is the question. In this article we review pendulum swings in the historical efforts to answer this question—from a comprehensive, positivist, “top-down,” deductive yes between the 1930s and the early 60s, to a postmodern no since then. A rationale and proposal for a limited, “bottom-up,” inductive yes in applied psychology is then presented, employing a case-based paradigm that integrates both positivist and postmodern themes and components. This paradigm is labeled “pragmatic psychology” and, its specific use of case studies, the “Pragmatic Case Study Method” (“PCS Method”). We call for the creation of peer-reviewed journal-databases of pragmatic case studies as a foundational source of unifying applied knowledge in our discipline. As one example, the potential of the PCS Method for unifying different angles of theoretical regard is illustrated in an area of applied psychology, psychotherapy, via the case of Mrs. B. The article then turns to the broader historical and epistemological arguments for the unifying nature of the PCS Method in both applied and basic psychology.Peer reviewe
Dr. Edwin Wright Collection: Author Unknown
Get PDFNotes - The author relates several short stories about his neighbours including Alex McDonell, homesteading and life around Meanook and Athabasca (1 page
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Energy-conserving Runge–Kutta methods for the incompressible Navier–Stokes equations
No full textEnergy-conserving methods have recently gained popularity for the spatial discretization of the incompressible Navier–Stokes equations. In this paper implicit Runge–Kutta methods are investigated which keep this property when integrating in time. Firstly, a number of energy-conserving Runge–Kutta methods based on Gauss, Radau and Lobatto quadrature are constructed. These methods are suitable for convection-dominated problems (such as turbulent flows), because they do not introduce artificial diffusion and are stable for any time step. Secondly, to obtain robust time-integration methods that work also for stiff problems, the energy-conserving methods are extended to a new class of additive Runge–Kutta methods, which combine energy conservation with L-stability. In this class, the Radau IIA/B method has the best properties. Results for a number of test cases on two-stage methods indicate that for pure convection problems the additive Radau IIA/B method is competitive with the Gauss methods. However, for stiff problems, such as convection-dominated flows with thin boundary layers, both the higher order Gauss and Radau IIA/B method suffer from order reduction. Overall, the Gauss methods are the preferred method for energy-conserving time integration of the incompressible Navier–Stokes equations
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
Get PDFThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
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