Search results for "wave"
showing 9 items of 6009 documents
Oscillatory periodic pattern dynamics in hyperbolic reaction-advection-diffusion models
2022
In this work we consider a quite general class of two-species hyperbolic reaction-advection-diffusion system with the main aim of elucidating the role played by inertial effects in the dynamics of oscillatory periodic patterns. To this aim, first, we use linear stability analysis techniques to deduce the conditions under which wave (or oscillatory Turing) instability takes place. Then, we apply multiple-scale weakly nonlinear analysis to determine the equation which rules the spatiotemporal evolution of pattern amplitude close to criticality. This investigation leads to a cubic complex Ginzburg-Landau (CCGL) equation which, owing to the functional dependence of the coefficients here involve…
Synergistic effect of W incorporation and pulsed current mode on wear and tribocorrosion resistance of coatings grown by plasma electrolytic oxidatio…
2019
Ceramic coatings were grown by plasma electrolytic oxidation on 7075 Al alloy using unipolar and bipolar pulsed current waveforms with 20 and 40% cathodic duty cycles, from a silicate-based bath without and with the addition of Na2WO4. Pancake-like morphology was dominant on the coatings grown by unipolar waveform, while the bipolar waveforms promoted volcano-like morphology, increased the roughness of the coating surface and the formation of more compact layers. The coatings produced using the bipolar waveforms provided higher resistances toward both tribocorrosion and dry sliding conditions, while further improvement was achieved by the presence of tungsten. The coatings produced in tungs…
Les types de temps associés aux risques d’inondations et d’érosions en Camargue : éléments de diagnostic et de prospectives pour le 21e siècle (1993-…
2010
Les fortes surcotes marines et les fortes vagues sont les principaux aléas météo-marins associés aux risques de submersion et d’érosion du littoral camarguais. Sur la période 1993-2002, une forte fréquence mensuelle de très hautes surcotes marégraphiques est généralement associée à une forte fréquence de très hautes vagues. Ces deux phénomènes locaux se produisent principalement lorsqu'une dépression autour du Golfe de Gascogne est associée à des hautes pressions sur l’Europe Centrale. La fréquence mensuelle de ce type de temps nous renseigne sur la probabilité d’occurrence de fortes surcotes marégraphiques et vagues en Camargue. Au 21e siècle, la fréquence du type de temps associé aux plus…
Flexible and Efficient Computer-Aided Design Tool for Advanced Comb-Line Rectangular Waveguide Filters
2015
A very flexible and efficient computer-aided design (CAD) tool, specifically suited for advanced comb-line rectangular waveguide filters, is presented in this work. The developed software tool, which makes use of a full-wave analysis technique based on the Boundary Integral - Resonant Mode Expansion method, permits to load the considered comb-line resonators with any number of radially symmetrical partial-height metallic posts. The implemented CAD tool also allows for dealing with coupling windows of arbitrary cross-section, thus drastically enhancing the flexibility of the computer-aided design process. The excitation of the analyzed components, which is performed by using generalized coax…
First and second order rational solutions to the Johnson equation and rogue waves
2018
Rational solutions to the Johnson equation are constructed as a quotient of two polynomials in x, y and t depending on several real parameters. We obtain an infinite hierarchy of rational solutions written in terms of polynomials of degrees 2N (N + 1) in x, and t, 4N (N + 1) in y, depending on 2N − 2 real parameters for each positive integer N. We construct explicit expressions of the solutions in the cases N = 1 and N = 2 which are given in the following. We study the evolution of the solutions by constructing the patterns of their modulus in the (x, y) plane, and this for different values of parameters.
Interplay between the Belousov-Zhabotinsky reaction-diffusion system and biomimetic matrices
2007
Abstract Interactions between reaction–diffusion systems and restricted host environments are a subject of widespread interest. In this work the behaviour of the Belousov–Zhabotinsky reaction was investigated in lamellar phases formed by phospholipid bilayers with relevance for biological systems. The influence of the reactive medium on the structure of the lipid matrix and, in turn, the influence of the matrix on the dynamical evolution of chemical patterns, were studied by small angle scattering.
Nonlinearity measurement undergoing dispersion and loss
2023
Accurate knowledge of the nonlinear coefficient is extremely important to make reliable predictions about optical pulses propagating along waveguides. Nevertheless, determining this parameter when dispersion and loss are as important as nonlinear effects brings both theoretical and experimental challenges that have not yet been solved. A general method for measuring the nonlinear coefficient of waveguides under these demanding conditions is here derived and demonstrated experimentally in a kilometer-long standard silica fiber pumped close to 2 µm.
Feminisma loma Dienvidkorejā un tā ietekme uz Korejas sabiedrību 21. gadsimtā
2020
Darba nosaukums ir “Feminisma loma Dienvidkorejā un tā ietekme uz Korejas sabiedrību 21. gadsimtā’’. Saistībā ar 21. gadsimtā Korejas sabiedrībā pieaugošajiem protestiem par dzimumu jautājumiem, darbā tiks apskatīta feminisma lomas nozīmība Dienvidkorejā un tā radītās sekas. Autore vēlas atzīmēt, ka 21. gadsimts ir nodrošinājis jaunajam feminisma vilnim valstī daudz skaļāku un drosmīgāku formu, kas uz Korejas tradicionālo vērtību fona vēl vairāk polarizē dzimumus. Darba mērķis ir aplūkot un izanalizēt, kā jaunais feminisma vilnis valstī ir izraisījis sabiedrības reakciju dzimumu līdztiesības jautājumos, un tā nozīmīgumu īpaši šodien. Izšķiroša uzmanība tiek pievērsta abu dzimumu viedokļiem,…
Unraveling environmental histories from skeletal diaries — Advances in sclerochronology
2013
High-resolution proxy archives from aquatic settings are essential to better understand processes and mechanisms of global change. During the last decade, it has become increasingly evident that calcified tissues of bivalve mollusks and cold-water corals, in particular, can significantly increase our knowledge of seasonal to multi-decadal paleoclimate and paleoenvironmental variability in the extratropical oceans and coastal marine settings. Daily, tidal, fortnightly and annual growth patterns of periodically formed skeletal hard parts provide a means to place the proxy record in a precise temporal context. Their extreme longevity coupled with the running similarity between growth increment…