Results 41 to 50 of about 4,619,884 (143)
Characterizing isochronous points and computing isochronous sections [PDF]
, 2009 We consider two-dimensional autonomous systems of differential equationsx˙=−y+λx+P(x,y),y˙=x+λy+Q(x,y), where λ is a real constant and P and Q are smooth functions of order greater than or equal to two. These systems, so-called centre-focus type systems,
Algaba, A., Reyes, M.
core +1 more source
Centers and Isochronous Centers for Two Classes of Generalized Seventh and Ninth Systems [PDF]
Journal of Dynamics and Differential Equations, 2010 We classify new classes of centers and of isochronous centers for polynomial differential systems in R2 of arbitrary odd degree d ≥ 7 that in complex notation z = x + iy can be written as z˙=(λ+i)z+(zz)d-7-2j/2 (Az5+jz2+j+Bz4+jz3+j+Cz3+jz4+j+Dz7+2j), where j is either 0 or 1, λ ∈ R and A,B,C ∈ C. Note that if j = 0 and d = 7 we obtain a special case of
Llibre, Jaume, Valls, Clàudia
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Managing and visualising geochemical data for tephra correlation with the IntChron Integration Tool
Journal of Quaternary Science, EarlyView.ABSTRACT There is now a wealth of glass‐shard geochemical data for volcanic ash (tephra) layers from a wide range of volcanoes and eruptions, providing invaluable datasets for tephrochronology. However, compilation of published data to assess tephra correlations leads to large files and requires careful management.
Victoria C. Smith +5 more
wiley +1 more source
Journal of Quaternary Science, EarlyView.ABSTRACT Volcanic ash (tephra) provides an important chronostratigraphic framework for correlating Quaternary records. In ultra‐distal ( > $\gt $1500 km) settings such as ice cores and marine sediments, deposits are typically preserved as cryptotephra composed of glass shards ≤ 20 μ $\le 20\,\mu
Celeste Smith +6 more
wiley +1 more source
Linearization of analytic isochronous centers from a given commutator [PDF]
, 2008 In this paper we propose an algorithmic way to get the change of variables that linearizes an analytic isochronous center from a given commutator. Moreover, we use this method in order to obtain the linearization of some isochronous centers of the ...
Maza, Susanna +3 more
core +1 more source
Journal of Quaternary Science, EarlyView.ABSTRACT In this study, we report the first documented occurrence of the Icelandic Vedde Ash (VA) in the Bohemian Forest, identified within palaeolake sediments from Stará Jímka, Czechia, representing the first Icelandic tephra layer identified in Czechia.
Verena Meier +3 more
wiley +1 more source
On the critical periods of perturbed isochronous centers
Journal of Differential Equations, 2007 "Vegeu el resum a l'inici del document del fitxer adjunt".
Gasull, Armengol +2 more
openaire +4 more sources
Rounded Monodisperse Fluorescent Nanodiamonds
Small, EarlyView.Nanodiamond (ND) shape control using rapid molten‐nitrate etching is studied as a scale‐up method for monodispersed rounded particles. Optimal etching condition (567°C for 6 min) yields NDs with atomically stepped surfaces and reduced sp2 content. Compared to angular control, rounded NDs exhibit an increased proportion of luminescent particles (66% vs.
Helena Raabova +7 more
wiley +1 more source
Appraisal of Six Natural Mica Reference Materials for In Situ Rb‐Sr Geochronology
Geostandards and Geoanalytical Research, EarlyView.Key Points Evaluated six natural mica reference materials for in situ LA‐ICP‐MS/MS Rb‐Sr geochronology using geochemical, microstructural and isotopic characterisation. Identified robust primary reference materials: Mount Dromedary biotite (99.37 Ma) and Mica‐Fe biotite (307.75 Ma). La Posta biotite and Högsbo muscovite are suitable secondary reference
Hugo K.H. Olierook +38 more
wiley +1 more source
Isochronicity of centers in a switching Bautin system
Journal of Differential Equations, 2012 Isochronicity of centers for a class of discontinuous differential system, simply called switching system, is discussed. Some sufficient conditions for the system to have a regular isochronous center at the origin are given and a switching system with an irregular isochronous center at the origin is constructed.
Chen, Xingwu, Zhang, Weinian
openaire +2 more sources