Amplitude equations for Rayleigh-Benard convective rolls far from threshold

An extension of the amplitude method is proposed. An iterative algorithm is developed to build an amplitude equation model that is shown to provide precise quantitative results even far from the linear instability threshold. The method is applied to the study of stationary Rayleigh-Benard thermoconvective rolls in the nonlinear regime. In particular, the generation of second and third spatial harmonics is analyzed. Comparison with experimental results and direct numerical calculations is also made and a very good agreement is found.Peer reviewe

Trophic relationships within intertidal communities of the Brittany Coasts: A stable carbon isotope analysis

More than 100 species belonging to plant and animal tars that are commonly observed in the intertidal zone were collected on both rocky and soft bottom shores of Brittany, France, to be analysed for their C-13/C-12 ratio. Plant material displayed a wide range of delta(13)C values (from -12 to -34 parts per thousand), with relatively distinct values among producer groups (Chlorophyce ae, Fucales, Laminariales, Rhodophyce ae seagrasses, plankton), and among strata of intertidal zonation. Animal delta(13)C range was narrower (-15 to -22 parts per thousand), and in general, values differed more between than within phyla or classes, according to the staple diet of organisms. A good correlation between the delta(13)C values of food and consumers was noted, together with a slight C-13- enrichment (approximate to 1 parts per thousand) with increasing trophic levels from suspension-feeders to predators

Onset of thermal ripples at the interface of an evaporating liquid under a flow of inert gas

peer reviewe

The Canonical Decomposition Fuzzy Comparative Methodology for Assessing Architectures

The challenge for system architects is to perform a realistic assessment of an inherently ambiguous system concept. Many existing assessment methods are available, but these are often subjective and unrepeatable. Repeatability, objectivity, and increased fidelity are desired. an architecture assessment methodology capable of achieving these objectives is possible by drawing on the strengths of existing approaches while addressing their collective weaknesses. the proposed methodology is the Canonical Decomposition Fuzzy Comparative approach. the theoretical foundations of this methodology are developed herein and tested through the assessment of three physical architectures for a peer-to-peer wireless network. an extensible modeling framework is established to decompose high-level system attributes into technical performance measures suitable for analysis via computational modeling. Canonical design primitives are used to assess antenna performance in the form of a comparative analysis between the baseline free space gain patterns and the installed gain patterns. Finally, a fuzzy inference system is used to interpret the comparative feature set and offer a numerical assessment. the results of this experiment support the assertion that the proposed methodology is well suited for exposing integration sensitivity and assessing coupled performance in physical architecture concepts. © 2010 IEEE

Square cells in gravitational and capillary thermoconvection

The onset of square convective cells in fluid layers heated from below is investigated. Amplitude equations an deduced from the Boussinesq equations and a standard stability analysis is performed. Square cells are shown to be preferred when the instability is mainly capillarity driven. The influence of the Prandtl and Blot numbers are examined. At small Pr, the Plot number has not very much influence and squares are always observed for thin enough layers. in large Prandtl number fluids, Pi must be larger than the limiting value 0.28 for squares to be stable