1,721,246 research outputs found
Non-Stationary Abstract Friedrichs Systems
No full textInspired by the results of Ern et al. (Commun Partial Differ Equ 32:317–341, 2007) on the abstract theory for Friedrichs symmetric positive systems, we give the existence and uniqueness result for the initial- (boundary) value problem for the non-stationary abstract Friedrichs system. Despite the absence of the well-posedness result for such systems, there were already attempts for their numerical treatment by Burman et al. (SIAM J Numer Anal 48:2019–2042, 2010) and Bui-Thanh et al. (SIAM J Numer Anal 51:1933–1958, 2013). We use the semigroup theory approach and prove that the operator involved satisfies the conditions of the Hille–Yosida generation theorem. We also address the semilinear problem and apply the new results to a number of examples, such as the symmetric hyperbolic system, the unsteady div–grad problem, and the wave equation. Special attention was paid to the (generalised) unsteady Maxwell system. © 2016, Springer International Publishing
On generalisation of H-measures
Full text linkIn some applications it is useful to consider variants of H-measures different from those introduced in the classical or the parabolic case. We introduce the notion of admissible manifold and define variant H-measures on R^d×P for any admissible manifold P. In the sequel we study one special variant, fractional H-measures with orthogonality property, where the corresponding manifold and projection curves are orthogonal, as it was the case with classical or parabolic H-measures, and prove the localisation principle. Finally, we present a simple application of the localisation principle
Localisation principle for one-scale H-measures
No full textMicrolocal defect functionals (H-measures, H-distributions, semiclassical measures etc.) are objects which determine, in some sense, the lack of strong compactness for weakly convergent L^p sequences. Recently, Luc Tartar introduced one-scale H-measures, a generalisation of H-measures with a characteristic length, which also comprehend the notion of semiclassical measures.
We present a self-contained introduction to one-scale H-measures, carrying out some alternative proofs, and strengthening some results, comparing these objects to known microlocal defect functionals. Furthermore, we develop the localisation principle for these objects in a rather general form, from which we are able to derive the known localisation principles for both H-measures and semiclassical measures. Moreover, it enables us to obtain a variant of compactness by compensation suitable for equations with a characteristic length
Estimates for mild solutions to semilinear Cauchy problems
Full text linkThe existence (and uniqueness) results on mild solutions of the abstract
semilinear Cauchy problems in Banach spaces are well known.
Following the results of Tartar (2008) and Burazin (2008) in the case of
decoupled hyperbolic systems, we give an alternative proof, which enables
us to derive an estimate on the mild solution and its time of existence.
The nonlinear term in the equation is allowed to be time-dependent.
We discuss the optimality of the derived estimate by testing it on three
examples: the linear heat equation, the semilinear heat equation that
models dynamic deflection of an elastic membrane, and the semilinear
Schrodinger equation with time-dependent nonlinearity, that appear
in the modelling of numerous physical phenomena
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
Plan and Working Methods in Football School for Kids from 6 to10 Years of Age : Undergraduate Thesis
No full textPrimarni cilj ovog rada je predstavljanje osnovnog plana i metoda rada za razvoj nogometaša U9 i U11 uzrasne kategorije kroz četiri različite vrste priprema poštujući faze motoričkog razvoja. Pored toga, sekundarni cilj rada je detekcija razlika u planu i metodama rada između ovih dvaju kategorija, kao i detekcija razlika u sadržaju i vremenskoj zastupljenosti pojedinih priprema. Nakon uvodnog dijela u kojem su predstavljene faze motoričkog razvoja nogometaša, u radu su predstavljena određena dosadašnja znanstvena istraživanja koja nam daju uvid u specifičnosti razvoja ovih dvaju uzrasnih kategorija. U glavnom dijelu rada predstavljen je osnovni plan i metode rada U9, a potom i U11 uzrasne kategorije, a kao njegov vrhunac istaknuti su primjeri treninga pojedinih tehničkih elemenata kao što su: vođenje lopte, primanje lopte, dodavanje lopte, dribling i udarac lopte sredinom hrpta stopala, a među kojima se ističu razlike u treningu između ovih dvaju uzrasnih kategorija. Raspravom u završnom dijelu rada autor dolazi do zaključka kako postoje istaknute razlike u planu i metodama rada između U9 i U11 uzrasne kategorije.The primary objective of this paper is to present the basic plan and training methods for the development of players of U9 and U11 age categories through four different types of preparation respecting the stages of motor development. In addition, the secondary objective of the paper is to detect differences in the plan and training methods between the two categories, as well as to detect differences in the content and timing of individual preparations. After the introductory part in which the stages of motor development of football players are presented, the paper presents some scientific researches so far that give us insight into the specifics of the development of these two age categories. The main part of the paper presents the basic plan and training methods of the U9 and U11 age categories, as his highlight examples of training of certain technical elements, such as: running with the ball, receiving the ball, passing the ball, dribbling and shooting the ball with the middle of the foot, and highlighting the differences in training between the two age categories. In the discussion in the final part of the paper the author concludes that there are prominent differences in the plan and training methods between the U9 and U11 age categories
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
Relative age effect, morphological status and physical performance of U-15 Croatian football players
Full text linkThe relative age effect (RAE) refers to the unequal quartal-to-quartal birth distribution in competitive sports, leading to more athletes being born earlier in the selection period. This effect results in relatively older players, who are often physically more developed, being overrepresented in youth academies and professional levels, as they receive more attention and opportunities due to their advanced biological maturation and superior physical performance compared to their younger peers. This study involved 177 U-15 football players from Dalmatia, Croatia, averaging 14.1 ± 0.9 yrs of age and 6.6 ± 1.9 yrs of training experience. Anthropometric characteristics, motor-functional abilities, and specific abilities with the ball were measured over two days, using standardised equipment and procedures, and the data were analysed with descriptive statistics, one-way analysis of variance, and post hoc least significant difference tests to identify differences across quartiles. The study found statistically significant differences in the distribution and characteristics of players born in different quartiles of the year, with 63.3% born in the first two quartiles. RAE influenced young football players’ birth distribution and physical characteristics, with a higher proportion born in the first quartile of the year (Q1) and showing superior morphological development and physical performance. Q1 players were significantly taller and heavier and performed better in explosiveness tests (medium effect sizes) compared to other quartiles. Furthermore, small to medium effect differences occurred in circumferences, 20-m, 30-m sprints and ball-kicking velocities in favour of Q1. As these abilities and characteristics are key to success in football, players born in the first quartile have an advantage in the selection process. This highlights the need for coaches to focus on potential talent rather than current performance despite the competitive pressure to win.</p
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