Dissipative dynamics of a particle in a vibrating periodic potential: Chaos and control

The dissipative chaotic dynamics of a particle subjected to a horizontally vibrating periodic potential is characterized theoretically and confirmed numerically in the case of an external chaos-controlling periodic excitation also acting on the particle. Theoretical predictions concerning the chaotic threshold in parameter space are deduced from the application of Melnikov's method that fully determine the chaos-control scenario. Also, the structure of diverse regularization regions in parameter space is explained theoretically with the aid of an energy analysis. It was found that the phase difference between the two periodic excitations involved plays a crucial role in the chaos-control scenario, with the particular feature that its optimal value depends upon the ratio between the damping coefficient and the excitation frequency. This constitutes a genuine feature of the chaos-control scenario associated with nonsteady potentials which is in contrast to the case of steady potentials. Additionally, we demonstrate the robustness of the chaos-control scenario against the presence of low-intensity Gaussian noise and reshaping of chaos-suppressing excitations.R.C. and J.A.M. acknowledge financial support from the Ministerio de Economía y Competitividad (MINECO, Spain) through Project No. FIS2012-34902 cofinanced by FEDER funds. R.C. acknowledges financial support from the Junta de Extremadura (JEx, Spain) through Project No. GR15146. P.J.M. acknowledge financial support from the Ministerio de Economía y Competitividad (MINECO, Spain) through Project No. FIS2011-25167 cofinanced by FEDER funds.Peer Reviewe

¿Se acaba la Crisis del Coronavirus? Carencias en la Sanidad y en la Política: Is the Coronavirus Crisis Over? Gaps in Healthcare and Politics.

The coronavirus crisis we are suffering globally should soon be over. As of this writing (4/17/2020), there have been 150,000 deaths accounted for due to this cause and almost one million confirmed cases worldwide. Due to the lack of diagnostic testing and health politics to carry out analysis, mainly to those who are admitted to hospitals with symptoms, we still do not know the actual number of affected individuals, but it must be much higher than reported cases. The authors themselves have affected family members, even in Intensive Care Units (ICU). The healthcare and political authorities continue to say that the worst is yet to come. And certainly, very important, that we all stay at home. Once the national state of emergency is declared by governments, physical distancing compliance should be taken as an obligation for all.La crisis del coronavirus que sufrimos globalmente pronto debiera acabar. En el momento de escribir estetexto (17/4/2020), en el mundo se contabilizan más de 150 000 muertos por esta causa, y casi un millón decasos confirmados. Por la carencia de tests diagnósticos y por la política sanitaria de efectuar análisis, principalmente a los queingresan con respiratorios en los hospitales, se desconoce la cifra real de afectados, que debe ser muchomayor a los casos contabilizados. Nosotros, autores de esta carta al editor tenemos familiares afectados,incluso en Unidades de Cuidados Intensivos (UCI). Las autoridades sanitarias y políticas no paran de decirque lo peor está por llegar, y ciertamente, ciertamente, algo importante, que todos nos quedemos encasa. Una vez decretado por los Gobiernos el estado de alarma nacional, el cumplimiento del aislamientodebemos tomarlo como una obligación para todos

Design of a 35 kW Solar Cooling Demonstration Facility for a Hotel in Spain

[EN] Solar cooling systems have the advantage of the coincidence between the hours of cooling demand and the hours of solar radiation availability, and they can contribute to reduce the energy consumption in buildings. However, the high cost of thermal solar cooling facilities with absorption chillers, maintenance issues, legionella risk and water consumption (associated to the necessary cooling tower) have limited the use of these systems to demonstration projects. A simplified Transient System Simulation Tool (TRNSYS) model was developed to provide the owner of the demonstration facility the information he needs for design decision-making. This model was validated with experimental data registered in a solar cooling system designed and built by the authors. Different collector field surfaces, hot water storage tank volumes, and absorption machine driving temperatures were analyzed for a hotel demonstration facility. In terms of the energy delivered to the absorption chiller the optimum dimensioning corresponded to the lowest values of the driving temperature (75 °C) and specific storage volume (15 Lm2). From an economic point of view, the saving of 1515 euros per year when compared with an electric compression chiller does not compensate the investment of 3000 euros per kW of cooling capacity that cost the thermal solar cooling facility.This research was funded by (MINECO/AEI/FEDER, UE), grant number ENE2017-83729-C3-1-R.Martínez, PJ.; Martínez, P.; Soto Francés, VM.; Bujedo, LA.; Rodríguez, J. (2020). Design of a 35 kW Solar Cooling Demonstration Facility for a Hotel in Spain. Applied Sciences. 10(496):1-13. https://doi.org/10.3390/app10020496S1131049

El estrecho de las cuevas de La Encarnación (Caravaca)

Primer premio 2ª edición de Premios a la Elaboración de Materiales de Estudio sobre la Región de Murcia, modalidad Educación SecundariaEn la port.: IES Oróspeda-Archive

Regresión no lineal mediante la evolución de modelos Híbridos de Redes Neuronales

El presente trabajo es una primera aproximación a la formación de modelos de redes neuronales con unidades ocultas de tipo híbrido (sigmoides, producto) que siendo aproximadores universales, puedan utilizarse como modelos no lineales de regresión cuando las características del espacio de las variables independientes lo aconsejen. Dada la dificultad que presenta la aplicación de algoritmos de aprendizaje de búsqueda local para esta tipología de modelos, se utiliza un algoritmo de programación evolutiva donde se definen operadores de mutación específicos. Los experimentos realizados con cuatro funciones de prueba, las tres funciones de Friedman y una propuesta por los autores, muestran resultados muy prometedores en esta direcció

Hierarchical Up/Down Routing Architecture for Ethernet backbones and campus networks

We describe a new layer two distributed and scalable routing architecture. It uses an automatic hierarchical node identifier assignment mechanism associated to the rapid spanning tree protocol. Enhanced up/down mechanisms are used to prohibit some turns at nodes to break cycles, instead of blocking links like the spannning tree protocol does. The protocol performance is similar or better than other turn prohibition algorithms recently proposed with lower complexity O(Nd) and better scalability. Simulations show that the fraction of prohibited turns over random networks is less than 0.2. The effect of root bridge election on the performance of the protocol is limited both in the random and regular networks studied. The use of hierarchical, tree-descriptive addresses simplifies the routing, and avoids the need of all nodes having a global knowleddge of the network topology. Routing frames through the hierarchical tree at very high speed is possible by progressive decoding of frame destination address, without routing tables or port address learning. Coexistence with standard bridges is achieved using combined devices: bridges that forward the frames having global destination MAC addresses as standard bridges and frames with local MAC frames with the proposed protocol.Publicad

Density functional theories of hard particle systems

95 pages, 21 figures.-- Chapter in "Theory and Simulation of Hard-Sphere Fluids and Related Systems" (Lecture Notes in Physics 753/2008), http://dx.doi.org/10.1007/978-3-540-78767-9MR#: MR2503511This chapter deals with the applications of the density functional (DF) formalism to the study of inhomogeneous systems with hard core interactions. It includes a brief tutorial on the fundamentals of the method, and the exact free energy DF for one-dimensional hard rods obtained by Percus. The development of DF approximations for the free energy of hard spheres (HS) is presented through its milestones in the weighted density approximation (WDA) and the fundamental measure theory (FMT). The extensions of these approaches to HS mixtures include the FMT treatment of polydisperse systems and the approximations for mixtures with non-additive core radii. The DF treatment of non-spherical hard core systems is presented within the generic context of the study of liquid crystals phases. The chapter is directed to the potential users of these theoretical techniques, with clear explanations of the practical implementation details of the most successful approximations

Intra- and inter-speaker variability of sibilant fricative /s/ in Argentine Spanish

En este trabajo se propone estudiar y valorizar el poder discriminativo de la fricativa sibilante /s/, de manera de incorporar este conocimiento en futuros sistemas automáticos de reconocimiento de hablantes. Se seleccionó esta fricativa por ser la principal consonante de acuerdo a la frecuencia de aparición en el corpus. Se determinó un ranking de los parámetros acústicos de dicho fonema que mejor discriminan a un hablante, teniendo en cuenta la menor variabilidad intrahablante y la máxima variabilidad inter-hablante. El material de evaluación fue extraído de la base de datos SpeechDat, con muestras de habla de telefonía fija en Español de Argentina. Los parámetros con mejor puntaje fueron: la Intensidad, el tercer formante (F3), el primer formante (F1) y el primer momento espectral o Centro de Gravedad (CG). El poder discriminante de la fricativa sibilante /s/, con respecto al resto de los fonemas, ha quedado corroborado por su importante aporte a la tasa de reconocimiento de hablantes obtenida, siendo el sexto fonema en importancia después de las vocales /e/, /a/, /o/ y /i/, y la nasal /n/. La tasa de igual error, empleando solamente este fonema, resultó un 35% menor que la media del total de los 30 fonemas involucrados.This paper focuses on the analysis of the discriminative power of the sibilant fricative /s/, in order to incorporate this knowledge in future automatic speaker recognition systems. The selected fricative is the most frequent consonant in the corpus. An acoustical parameter ranking of /s/ was performed based on minor intra-speaker variability and maximun inter-speaker variability. Evaluation is performed on Argentine-Spanish voice samples from the SpeechDat database recorded on a fixed phone environment. The intensity, the third formant (F3), the first formant (F1) and the first spectral moment or Center of Gravity (CG) were the best ranked parameters. The sibilant fricative /s/, considered in isolation, has a speaker recognition equal error rate (EER) of 35% lower than the average of the total of 30 phonemes involved, confirming the importance of this phoneme for the discrimination of speakers as the sixth phoneme in importance, preceded by the vowels /e/, /a/, /o/ and /i/, and the nasal /n/