1,721,492 research outputs found
Community of scientist optimization: An autonomy oriented approach to distributed optimization
No full textA novel optimization paradigm, Community of Scientists Optimization (CoSO), is presented in this
paper. The approach is inspired to the behaviour of a community of scientists interacting, pursuing for research results and foraging the funds needed to held their research activities. The CoSO metaphor can be applied to general optimization domains, where optimal solutions emerge from the collective behaviour of a distributed community of interacting autonomous entities.
The CoSO framework presents analogies and remarkable differences with other evolutionary optimization
approaches: swarm behaviour, foraging and selectionmechanism based on research funds competition, dynamically evolving multicapacity communication channels realized by journals and evolving population size regulated by research management strategies.
Experiments and comparisons on benchmark problems show the effectiveness of the approach for numerical
optimization. CoSO, with the design of appropriate foraging and competition strategies, also represents a great potential as a general meta-heuristic for applications in non-numerical and agent-based domains.A novel optimization paradigm, called Community of Scientists Optimization (CoSO), is presented in this paper. The approach is inspired to the behaviour of a community of scientists interacting, pursuing for research results and foraging the funds needed to held their research activities. The CoSO metaphor can be applied to general optimization domains, where optimal solutions emerge from the collective behaviour of a distributed community of interacting autonomous entities. The CoSO framework presents analogies and remarkable differences with other evolutionary optimization approaches: swarm behaviour, foraging and selection mechanism based on research funds competition, dynamically evolving multicapacity communication channels realized by journals and evolving population size regulated by research management strategies. Experiments and comparisons on benchmark problems show the effectiveness of the approach for numerical optimization. CoSO, with the design of appropriate foraging and competition strategies, also represents a great potential as a general meta-heuristic for applications in non-numerical and agent-based domains. © 2012 - IOS Press and the authors. All rights reserved
On the asymptotic behavior of semilinear wave equations with degenerate dissipation and source terms
No full textWe investigate the asymptotic behavior of weak solutions to the semilinear non autonomous wave equation utt - Δu + ut|ut|p-1 = V(t)u|u|p-1 + f(.,t), where V(t) is a positive time dependent potential satisfying V(t) = O((1 + t)-λ) as t → +∞ and ft decays to 0 as t → +∞. We show that for 0 ≤ λ ≤ p there are initial values such that the energy norm of the corresponding solutions grows at least polynomially as t → +∞, while if λ > p the energy norm remains uniformly bounded for any choice of initial values; moreover, in certain cases there is an absorbing ball for the orbits
Regolazione ottima di un'intersezione stardale per la salvaguardia della qualità dell'aria
No full textChaotic orbit determination in the context of the JUICE mission
No full textTidal dissipation within Io and Jupiter leads to a migration of the Galilean satellites. In fact, the resonant interaction between Io, Europa and Ganymede spreads the dissipative effects from Io to the orbits of the other moons. The amount of the loss of energy and the consequent rate of the orbital evolution was determined in (Lainey et al., 2009), along with the dissipative parameters k2/Q of Io and Jupiter. Although this could be considered the most reliable result in literature, there are other articles with different solutions of the moons migration. In this context, the future ESA space mission JUICE can play a key role: during its flybys tour of the Galilean satellites and an orbiting phase around Ganymede, it will provide new extremely accurate observations of the Jovian system, with which it will be possible to constrain moons’ physical properties and orbits. In particular, in this study we investigate the possibility of performing an independent estimation of the k2/Q parameters using JUICE data. However, the multiple flybys trajectory is well known to be chaotic, raising critical issues both in the design of the mission and in the orbit determination experiments. In this article we present the results of simulations using JUICE data from two different experiments (3GM and PRIDE). Differently from (Dirkx et al., 2017), we perform a simultaneous estimation of the spacecraft and Galilean satellites’ orbits, along with some dynamical parameters of interest. We will show that adopting the constrained multi-arc strategy during the chaotic phase, we manage to improve the determination of the dissipative parameters, as expected by (Serra et al., 2018). Although a complete estimation of all the relevant parameters will be addressed in future works, in this preliminary study we find a formal uncertainty of the two k2/Q of the same order of (Lainey et al., 2009). This implies that the content of information provided by JUICE is similar to the one hundred years astrometric observations used in the same article. Therefore, with JUICE data we will be able to check results and theories of previous studies about the dissipation in the Jovian system, and once added to the other available data sets, we could get a more accurate solution, covering a time span greater than the 4 years of the mission
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
- …
