22,247 research outputs found
The Redner - Ben-Avraham - Kahng cluster system
We consider a coagulation model first introduced by Redner, Ben-Avraham and
Krapivsky in [Redner, Ben-Avraham, Kahng: Kinetics of 'cluster eating', J.
Phys. A: Math. Gen., 20 (1987), 1231-1238], the main feature of which is that
the reaction between a j-cluster and a k-cluster results in the creation of a
|j-k|-cluster, and not, as in Smoluchowski's model, of a (j+k)-cluster. In this
paper we prove existence and uniqueness of solutions under reasonably general
conditions on the coagulation coefficients, and we also establish
differenciability properties and continuous dependence of solutions. Some
interesting invariance properties are also proved. Finally, we study the
long-time behaviour of solutions, and also present a preliminary analysis of
their scaling behaviour.Comment: 24 pages. 2 figures. Dedicated to Carlos Rocha and Luis Magalhaes on
the occasion of their sixtieth birthday
The Redner - Ben-Avraham - Kahng coagulation system with constant coefficients: the finite dimensional case
We study the behaviour as of solutions to the
Redner--Ben-Avraham--Kahng coagulation system with positive and compactly
supported initial data, rigorously proving and slightly extending results
originally established in [4] by means of formal arguments.Comment: 13 pages, 1 figur
Metodologia cientÃfica para extração de DNA de amostras de sangue (aves e quelônios).
bitstream/item/56378/1/ComTec228.pd
Seismic vulnerability assessment of the old city centre of Seixal, Portugal
The seismic vulnerability assessment of old traditional masonry building stocks, in a seismic risk mitigation perspective, is truly essential not only for buildings with recognized historical and patrimonial value, but also, in relation to regular buildings. In this sense, this paper approaches the issue of the seismic vulnerability assessment of masonry buildings through the application of a simplified methodology to building stock of the old city centre of Seixal, Portugal. This methodology is based on a vulnerability index, suitable in the evaluation of damage and in the creation of large scale loss scenarios (economical and human). Over 500 buildings were evaluated in accordance with the referred methodology and the results obtained were then integrated into a Geographical Information System tool. The integration of this kind of vulnerability and loss results into a GIS tool allows that city councils or regional authorities make their decisions based on a global view of the site under analysis, which led to more accurate and faster decisions either in terms of risk mitigation strategies or rehabilitation plans. This tool can also assumes great importance in the construction of safety and rescue plans
Vulnerability assessment of urban building stock: a hierarchic approach
In the last decades the evaluation of the seismic risk are of rising concern, considered essential in the activity and
definition of strategy planning and urban management. The evaluation of the seismic vulnerability of the existent building stock
in the perspective of the seismic risk mitigation should not be placed only in relation to the isolated buildings of relevant
historical and cultural importance, but also, in relation to the agglomerate of buildings in urban centres. The chronological
construction process frequently results in characteristic heterogeneity of masonry and wall connection quality. In addition,
buildings do not constitute independent units given that they share the mid-walls with adjacent buildings and the façade walls are
aligned. This way, as post-seismic observations proved, buildings do not have an independent structural behaviour, but they
interact amongst themselves, mainly for horizontal actions and so the structural performance should be studied at the level of the
aggregate and not only for each isolated building. In most cases, for masonry structures there is no need for sophisticated
dynamic analyses for seismic resistance verification or vulnerability assessment. This is even more relevant when an assessment
at the level of a city centre is pursued. In this work, the results of evaluation of the vulnerability will be presented in accordance
to three proposed methodologies based on a vulnerability index that consequently allows the evaluation of damage and creation
of loss scenarios (economical and human) not only at the level of the building and its façade walls but also at the level of the
aggregates. It will be discussed and evaluated the application of the referred methodologies and its integration in an SIG
platform
Efeito de micorrizas arbusculares sobre o crescimento e nutrição mineral de Brachiaria brizantha c.v Marandu.
O efeito da inoculação de micorrizas arbusculares (MA) sobre o crescimento ...., foi avaliado sob condições de casa-de-vegetação. Foram avaliados oito espécies de MA: Glomus mossaea, G. fasciculatum, G. etunicatum, G. macrocarpum, Gigaspora margarita, Scutellospora heterogama, Acaulospora laevis e A. muricata.bitstream/item/67179/1/FOL-5289-5879id-.pd
- …