Pseudospectral versus finite-differences schemes in the numerical integration of stochastic models of surface growth

We present a comparison between finite differences schemes and a pseudospectral method applied to the numerical integration of stochastic partial differential equations that model surface growth. We have studied, in 1+1 dimensions, the Kardar, Parisi and Zhang model (KPZ) and the Lai, Das Sarma and Villain model (LDV). The pseudospectral method appears to be the most stable for a given time step for both models. This means that the time up to which we can follow the temporal evolution of a given system is larger for the pseudospectral method. Moreover, for the KPZ model, a pseudospectral scheme gives results closer to the predictions of the continuum model than those obtained through finite difference methods. On the other hand, some numerical instabilities appearing with finite difference methods for the LDV model are absent when a pseudospectral integration is performed. These numerical instabilities give rise to an approximate multiscaling observed in the numerical simulations. With the pseudospectral approach no multiscaling is seen in agreement with the continuum model.Comment: 13 single column pages, RevTeX, 6 eps fig

Ley general de aguas, la amenaza que se desechó... por ahora

Texto que celebra con cautela el triunfo ante la clase política mexicana, tras el intento fallido de mercantilizar el agua. Se exponen las razones por las que el dictamen de la Ley General de Aguas vulneraba el derecho humano al acceso al líquido y su saneamiento, y se explica por qué la iniciativa favorecía el interés particular para su gestión frente al interés público y social.ITESO, A.C

Scaling of Local Slopes, Conservation Laws and Anomalous Roughening in Surface Growth

We argue that symmetries and conservation laws greatly restrict the form of the terms entering the long wavelength description of growth models exhibiting anomalous roughening. This is exploited to show by dynamic renormalization group arguments that intrinsic anomalous roughening cannot occur in local growth models. However some conserved dynamics may display super-roughening if a given type of terms are present.Comment: To appear in Phys. Rev. Lett., 4 pages in RevTeX style, no fig

Interpretación de los valores de microdureza de la recta de Gahm. Aplicación del método al estudio de la dureza de la hematites y de la cobaltina

The description of how to obtain the experimental data of the hardness at microscopical scale in hematites and cobal- tirie and of the respective equipments used is given. The graphics of the data obtained are exposed according to Gahm, to obtain the best straight line. The conclusions and recomtnendations on doing the research work on the hardness of the minerals, are stablished

SpectroscopicTechniques and DFT Calculations to Understand Charge Transport Mechinisms in OFETs

The organic electronics research field has advanced tremendously in the last decades, but there is still an incomplete understanding of the main mechanisms governing charge injection and transport in such devices. The performance of organic semiconductors is governed not only by their molecular structures but also by their intermolecular assembly in the solid state. Here we use a combination of Raman spectroscopy and charge modulation spectroscopy (CMS) to gather information on molecular and supramolecular levels, of organic semiconductors [1,2] (Figure 1) [3]. This last one is an optical-spectroscopy technique conducted on a real OFETs, that allows us to study in situ the charge carriers present at the semiconductor-dielectric interface, where the largest contribution to charge transport occurs. [3] In this communication we will present the study of the bithiophene imide (BTIn) molecules which exhibit encouraging electron mobilities in OFETs [1,2], by using the spectroscopic techniques presented above, supported by DFT quantum chemical calculations in order to shed light on the mechanism of charge transport in OFETs.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Cálculo de sistemas de climatización marinos con base en ahorros energéticos

The development of ship propulsion in the areas of Economic Operation, Environmental Protection and Ship Efficiency (Triple E - Economy, Environment, Efficiency) is the comparison standard of the manufacturers of contemporary ships. The standard is based on the application of a more modern design of the diesel engines, the wide use of waste heat and the efficient operation of the ship.In accordance with the Economic Operation, the need to evaluate the design of air conditioning systems has been identified in order to determine the possible savings, which are represented by a decrease in fuel consumption, as a result of: the significant impact of this consumption in the operation of the ship, the current high costs of this energy, the periodic increase in the price of the same, and the international policies for the reduction of emissions to the atmosphere and preservation of the environment.By means of the energy diagnosis of the air conditioning system it is possible to determine the possible opportunities of energy saving during the operation of the ship.The results indicate that the thermal load and the cooling capacity required by the air conditioned spaces have a difference between their maximum and average value of 14%. This justifies the need to use a conditioning system with a variable volume of air supplied to the air conditioned space.El desarrollo de la propulsión de los buques en los aspectos de Operación Económica, Protección del Medio Ambiente y Eficiencia de la Propulsión del buque (Triple E- Economy, Environment, Efficiency) constituye el estándar de comparación de los fabricantes de buques contemporáneos. El estándar está basado en la aplicación de un  diseño más moderno de los motores (máquinas) diésel, en la utilización amplia del calor de desecho y en la operación eficiente del barco.En correspondencia con la Operación Económica se ha identificado la necesidad de evaluar el diseño de los sistemas de aire acondicionado con el objetivo de determinar  los  posibles ahorros, que se vean representados en disminución del consumo de combustible, dado por: el significativo impacto de este consumo en la operación del buque, los altos costos de este energético en la actualidad, el incremento periódico en el precio del mismo, y las políticas internacionales para la reducción de emisiones a la atmósfera y preservación del medio ambiente.Mediante el diagnóstico energético del sistema de aire acondicionado se puede determinar  las posibles oportunidades de ahorro energético durante la operación de la embarcación.Los resultados indican que, la carga térmica y la capacidad de enfriamiento requerida por los espacios acondicionados tienen una diferencia entre su valor máximo y medio del 14 %. Esto justifica la necesidad de utilizar un sistema de acondicionamiento con volumen variable del aire suministrado al espacio acondicionado

Finding a widest empty 1-corner corridor

Given a set of n points in the plane, we consider the problem of computing a widest empty 1-corner corridor. We star giving a characterization of the 1-corner corridors that we call locally widest. Our approach to finding a widest empty 1-corner corridor consists of identifying a set of 1-corner corridors locally widest, that is guaranteed to contain a solution. We describe an algorithm that solves the problem in O(n4 log n) time and O(n) space.Ministerio de Ciencia y TecnologíaNational Science FoundationGeneralitat de Cataluny

Imaging Sciences R&D Laboratories in Argentina

We use the term imaging sciences to refer to the overarching spectrum of scientific and technological contexts which involve images in digital format including, among others, image and video processing, scientific visualization, computer graphics, animations in games and simulators, remote sensing imagery, and also the wide set of associated application areas that have become ubiquitous during the last decade in science, art, human-computer interaction, entertainment, social networks, and many others…Fil: Delrieux, Claudio Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Ballarin, Virginia Laura. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones Científicas y Tecnológicas en Electrónica; ArgentinaFil: Garcia Bauza, Cristian Dario. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Grupo de Plasmas Densos Magnetizados. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Grupo de Plasmas Densos Magnetizados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: López, Mario A.. University of Denver.; Estados Unido