Leonardo Silva de Lima

Bounds on the index of the signless Laplacian of a graph

A shock absorber apparatus connected in series relationship respective to the polished rod and bridle of a pumpjack unit. The shock absorber includes a housing within which there is supported a plurality of resilient packer members stacked in sandwiched relationship. The packer members have an axial passageway formed therethrough, with the passageway of each packer member being aligned with one another, so that the polished rod is telescopingly received therethrough. The bottom of the housing is supported by the bridle, while the polished rod is supported by a plate member which bears against the uppermost packer member. This places all of the resilient packer members in compression, with the force of the compression being proportional to the weight of the sucker rod.

Redes de colaboração científica na área de química no Brasil: um estudo baseado nas coautorias dos artigos da revista Química Nova

In this paper we built three co-authorship networks displaying the acquaintances between countries, universities and authors that have published papers in Quimica Nova from 1995 to 2008. Our research was conducted applying a bibliometric approach to 1782 papers and over 4200 authors. Centrality measures were used and the most significant actors of each network were pointed out. The results using the centrality metrics and the network structures indicated that Quimica Nova resembles a typical scientific community.

On the second largest eigenvalue of the signless Laplacian

Abstract Let G be a graph of order n, and let q 1 ( G ) ≥ ⋯ ≥ q n ( G ) be the eigenvalues of the Q-matrix of G, also known as the signless Laplacian of G. We give a necessary and sufficient condition for the equality q k ( G ) = n - 2 , where 1 k ≤ n . In particular, this result solves an open problem raised by Wang, Belardo, Huang and Borovicanin. We also show that q 2 ( G ) ≥ δ ( G ) and determine all graphs for which equality holds.

A área CTS no Brasil vista como rede social: onde aprendemos?

This paper aimed to assess 22 Brazilian Science Teaching journals and to identify the most cited works used as references. We gathered all papers where the words science, technology and society have appeared either in the abstract or in the keywords. Our research considered 88 articles and 394 citations where the 13 most cited papers were obtained. A citation network was built from the selected papers. From the results, we have drawn some conclusions: there is a predominance of citations to Brazilian authors and they are the main source in most of the journals and papers analyzed in this research; it is not possible to perceive inter-disciplinarity and contextualization, two STS distinctive attributes. Our partial results also confirmed the needed to know which source the key STS Brazilian authors are using as a foundation to their own study and its impact on STS production in Brazil.

Extremal graphs for the sum of the two largest signless Laplacian eigenvalues

Let G be a simple graph on

The clique number and the smallest Q -eigenvalue of graphs

n

A Mixed Graph Framework to evaluate the complementarity of communication Tools.

vertices and

A lower bound for the sum of the two largest signless Laplacian eigenvalues

e(G)

Evaluating temporal aggregation for predicting the sea surface temperature of the Atlantic Ocean

edges. Consider

The smallest eigenvalue of the signless Laplacian

Q(G) = D + A