Autor: Gouveia, L. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Determining hop-constrained spanning trees with repetitive heuristics
Autorzy:: Fernandes, M.
Gouveia, L.
Voß, S.
Powiązania:: https://bibliotekanauki.pl/articles/308588.pdf
Data publikacji:: 2007
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: hop-constrained spanning tree problem
metaheuristics
pilot method
rollout method
Opis:: The hop-constrained minimum spanning tree problem is the problem of determining a rooted spanning tree of minimum cost in which each path from the root node to any other node contains at most H hops or edges. This problem relates to the design of centralized tree networks with quality of service requirements (in telecommunications) and has a close relation with other tree problems. In this paper we investigate the adaptation of some well-known "repetitive" heuristics used for the capacitated minimum spanning tree problem to the hop-constrained minimum spanning tree problem and investigate some simple look ahead mechanisms for enhancing the quality of a savings heuristic. Computational results for a set of benchmark tests with up to 80 nodes are presented.
Źródło:: Journal of Telecommunications and Information Technology; 2007, 4; 16-22
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Lignin-based polyurethane and epoxy adhesives: a short review
Autorzy:: dos Santos, D.J.
Tavares, L.B.
Gouveia, J.R.
Batalha, G.F.
Powiązania:: https://bibliotekanauki.pl/articles/2175803.pdf
Data publikacji:: 2021
Wydawca:: Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:: engineering polymers
adhesives
polyurethane
lignin
polimery inżynieryjne
kleje
poliuretan
lignina
Opis:: Purpose: of this paper was to review and summarize significant papers related to the development and characterization of lignin-containing adhesives: polyurethane and epoxy types. In the last decades, several efforts have been dedicated on the development of renewable raw materials for polymer synthesis, mainly due to petroleum depletion and sustainability. In this context, lignin emerged as a potential candidate to substitute fossil-based raw materials in adhesive synthesis and formulations. Design/methodology/approach: Recent and other relevant papers were reviewed, aiming to identify the main advantages and limitations involved in lignin incorporation into epoxy and polyurethane adhesives formulations. First, effects of unmodified lignin addition were presented. Afterwards, the main lignin chemical modification methods were presented and discussed, based on thermomechanical results. Findings: Incorporation of unmodified lignin usually is limited to 30 %wt., otherwise mechanical properties are drastically affected as consequence of poor lignin solubility and excessive brittleness. Lignin chemical modification can be used to increase the reactivity of hydroxyl groups and/or add new moieties in its molecular structure, improving solubility and thermomechanical properties of cured adhesives. Practical implications: In the last years, some industrial plants started to operate and produce technical grade lignin at industrial scale, with reproducible properties and controlled molecular structure. Therefore, increasing efforts have been dedicated from researchers and chemists to develop lignin-based technologies, in which this work can directly contribute with. Originality/value: As consequence of the high content of phenol groups in its molecular structure, lignin was mostly applied on the development of phenolic resins applied as wood adhesives. For the first time in the literature, this work summarizes the advances related to synthesis and characterization of polyurethane and epoxy, applied as adhesives. Results can support the development and application of biobased, as well as contribute to the revalorization of this valuable and readily available biomass.
Źródło:: Archives of Materials Science and Engineering; 2021, 107, 2; 56--63
1897-2764
Pojawia się w:: Archives of Materials Science and Engineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Phytochemical potential of Ficus species for the control of the phytonematode Meloidogyne javanica
Autorzy:: Alves, J.R.
De Assis, J.N.
Padua, C.C.A.
Balbino, H.M.
Lima, L.L.
De Souza Gouveia, A.
Vital, C.E.
Buonicontro, D.S.
De Freitas, L.G.
Leite, J.P.V.
De Oliveira Ramos, H.J.
Powiązania:: https://bibliotekanauki.pl/articles/2082765.pdf
Data publikacji:: 2020
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: gas chromatography/mass spectrometry (GC/MS)
metabolite profiling
pest
control
phytochemistry
Opis:: Root-knot nematodes, genus Meloidogyne, are among the most plant damaging pathogens worldwide. The action of natural products against plant pathogens has been investigated to assess their effectiveness in the control of diseases. Thus, the present study aimed to evaluate the phytochemistry potential of the Ficus species for the control of Meloidogyne javanica. In vitro inhibitory activity assays were performed with crude ethanolic extracts of leaves and branches from 10 Ficus species. Among these, Ficus carica extracts exhibited strong paralysis activity against second stage juveniles (J2) (EC50 = 134.90 μg ∙ ml–1 ), after 72 hours. In addition, high efficacy was observed in egg-hatching inhibition at different embryonic stages. Microscopy analysis revealed severe morphological alterations in the nematode tissues at the J2 stage, as well as immotility of juveniles released from eggs in the presence of F. carica extracts. The efficacy of the treatments for the other species was very low. These differences were supported by the variation in the compound classes, mainly for alkaloids and metabolite profiles by Gas Chromatography/Mass Spectrometry (GC/MS) when F. carica was compared with the other species. The results indicated that F. carica is a promising source for the isolation and identification of molecules capable of acting in the control of M. javanica.
Źródło:: Journal of Plant Protection Research; 2020, 60, 2; 193-206
1427-4345
Pojawia się w:: Journal of Plant Protection Research
Dostawca treści:: Biblioteka Nauki

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