Hydrodynamic fingering instability of driven wetting films: hindrance by diffusion

Recent experimental and theoretical efforts have revealed the existence of a fingering instability at the moving front of thin liquid films forced to spread under gravitational, rotational or surface shear stresses, as for example by using the Marangoni effect. The authors describe how the presence of a precursor film in front of the spreading macroscopic film, whether it is by prewetting the substrate or by surface diffusion or multilayer absorption, can prevent the development of the instability

RETRASO, a code for modeling reactive transport in saturated and unsaturated porous media

The code RETRASO (REactive TRAnsport of SOlutes) simulates reactive transport of dissolved and gaseous species in non-isothermal saturated or unsaturated problems. Possible chemical reactions include aqueous complexation (including redox reactions), sorption, precipitation-dissolution of minerals and gas dissolution. Various models for sorption of solutes on solids are available, from experimental relationships (linear KD, Freundlich and Langmuir isotherms) to cation exchange and surface complexation models (constant capacitance, diffuse layer and triple layer models). Precipitation-dissolution and aqueous complexation can be modelled in equilibrium or according to kinetic laws. For the numerical solution of the reactive transport equations it uses the Direct Substitution Approach. The use of the code is demonstrated by three examples. The first example models various sorption processes in a smectite barrier. The second example models a complex chemical system in a two dimensional cross-section. The last example models pyrite weathering in an unsaturated medium

Molecular Dynamics simulations of concentrated aqueous electrolyte solutions

Transport properties of concentrated electrolytes have been analyzed using classical molecular dynamics simulations with the algorithms and parameters typical of simulations describing complex electrokinetic phenomena. The electrical conductivity and transport numbers of electrolytes containing monovalent (KCl), divalent (MgCl$_2$), a mixture of both (KCl + MgCl$_2$), and trivalent (LaCl$_3$) cations have been obtained from simulations of the electrolytes in electric fields of different magnitude. The results obtained for different simulation parameters have been discussed and compared with experimental measurements of our own and from the literature. The electroosmotic flow of water molecules induced by the ionic current in the different cases has been calculated and interpreted with the help of the hydration properties extracted from the simulations

Analysis and design of a drain water heat recovery storage unit based on PCM plates

© 2016. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/This paper is focused on the detailed analysis of a PCM plate heat storage unit with a particular configuration, looking for the maximum contact area with the fluid (water) and the minimum volume to be used in a real household application. In that sense, a numerical study of the thermal and fluid dynamic behaviour of the water flow and the PCM melting-solidification processes, together with the thermal behaviour of the solid elements of the unit, has been carried out. On the other hand, an experimental set-up has been designed and built to validate the numerical model and characterise the performance of the heat storage unit. The purpose of the numerical and experimental study is to present a series of results to describe the heat storage unit performance in function of the time. Thus, after a preliminary design study three different cases have been simulated and tested. A 7.2% of discrepancy between numerical results and experimental data has been evaluated for the heat transfer. The PCM heat storage unit designed is capable to store approx. 75% of the thermal energy from the previous process wasted water heat, and recover part of it to supply around 50% of the thermal energy required to heat up the next process.Peer ReviewedPostprint (author's final draft

A Nonlinear Adiabatic Theorem for Coherent States

We consider the propagation of wave packets for a one-dimensional nonlinear Schrodinger equation with a matrix-valued potential, in the semi-classical limit. For an initial coherent state polarized along some eigenvector, we prove that the nonlinear evolution preserves the separation of modes, in a scaling such that nonlinear effects are critical (the envelope equation is nonlinear). The proof relies on a fine geometric analysis of the role of spectral projectors, which is compatible with the treatment of nonlinearities. We also prove a nonlinear superposition principle for these adiabatic wave packets.Comment: 21 pages, no figur

Nonlinear coherent states and Ehrenfest time for Schrodinger equation

We consider the propagation of wave packets for the nonlinear Schrodinger equation, in the semi-classical limit. We establish the existence of a critical size for the initial data, in terms of the Planck constant: if the initial data are too small, the nonlinearity is negligible up to the Ehrenfest time. If the initial data have the critical size, then at leading order the wave function propagates like a coherent state whose envelope is given by a nonlinear equation, up to a time of the same order as the Ehrenfest time. We also prove a nonlinear superposition principle for these nonlinear wave packets.Comment: 27 page

Karakteristik Perikanan Tangkap Di Perairan Laut Kabupaten Simeulue (Characteristics of Capture Fisheries in Simeulue Districts Sea Waters Area)

Simeulue Regency has ± 9.968,16 km2 marine waters area consist of 64 islands (large and small) with high potentials of capture fisheries. However, the management of sustainable fisheries in Simeulue Regency has not optimal yet. Informations about catch composition, diversity index and fishing gear productivity are needed as a reference in policy management decision. The purpose of this research are to determine the compositions of catch, to calculate the fish biodiversity and fishing gear productivity. The research was conducted in Simeulue Regency from December 2013 to January 2014. The method used was purposive sampling survey. Fishing units which observed such as lift net, beach seines, longlines and other collecting gears. Result in five research locations are Simeulue Timur, Teupah Selatan, Teluk Dalam, Simeulue Barat and Teupah Tengah, there were 50 fish species which dominated by Bali sardinella (Sardinella lemuru), slipmouths (Leiognathus spp), Indian anchovy (Stolephorus spp), scad (Selar spp) and frigate tuna (Auxis thazard). Biodiversity index (H ') value was beetween 1.40 to 2.67 with average of 1.87, it describes that biodiversity was in the moderate category. Furthermore, the evenness index (E) was in the category of relatively even from 0.58 to 0.89 with the average of 0.74. Dominance index values (D) was beetween 0.09 – 0.33 with average of 0.24, which means that there were not any dominating species. The highest value of productivity (CPUE) was lift net with 603.3 kg/trip and the lowest was lobster or sea cucumber collecting gears with 81.8 kg/trip

Robustness of the Blandford-Znajek mechanism

The Blandford-Znajek mechanism has long been regarded as a key ingredient in models attempting to explain powerful jets in AGNs, quasars, blazzars etc. In such mechanism, energy is extracted from a rotating black hole and dissipated at a load at far distances. In the current work we examine the behaviour of the BZ mechanism with respect to different boundary conditions, revealing the mechanism robustness upon variation of these conditions. Consequently, this work closes a gap in our understanding of this important scenario.Comment: 7 pages, accepted in CQ

La globalización alternativa y los 'novísimos' movimientos sociales

Las dos últimas décadas han sido testigos del surgimiento de un nuevo ciclo global de acción colectiva, organizada a través del internet y que se ha hecho visible durante protestas masivas, pero también ha sido configurado localmente por diversas organizaciones, redes, plataformas, y grupos. Con base en dos casos específicos en dos ciudades ibéricas –Barcelona y Lisboa–, argumentamos que este ciclo de protestas ha dado lugar a nuevos tipos de movimientos a los que aquí nos referimos como los ‘novísimos movimientos sociales’. Analizamos aspectos específicos de cada caso, pero también discutimos sus dimensiones europeas y globales. El artículo enfatiza el papel de la juventud, discute las características asociadas con la participación de los jóvenes en los ‘novísimos’ movimientos. Después de una breve introducción a la investigación sobre este tema, centrándonos en el surgimiento del ‘movimiento de la 'globalización alternativa' o ‘en contra de la globalización corporativa’ y sus implicaciones teóricas asociadas, ofrecemos una descripción de cuatro acontecimientos de protesta en Barcelona y Lisboa. A continuación, analizamos los contextos locales en los que se fundamentan estos acontecimientos. Finalmente, discutimos las principales características de los ‘novísimos movimientos sociales’, analizando los vínculos entre Barcelona y Lisboa y el contexto internacional más amplio que les da forma, prestando especial atención en las dinámicas contemporáneas de formación de redes

On the identity of the type species of the genus Telema (Araneae, Telemidae)

Telema tenella Simon, 1882, the type species of genus Telema, is the only species of family Telemidae reported from Europe and all other 39 congeners occur far from it. However, it has never been properly described. In this paper T. tenella is redescribed and illustrated