Elliptic harbor wave model with perfectly matched layer and exterior bathymetry effects

Standard strategies for dealing with the Sommerfeld condition in elliptic mild-slope models require strong assumptions on the wave field in the region exterior to the computational domain. More precisely, constant bathymetry along (and beyond) the open boundary, and parabolic approximations–based boundary conditions are usually imposed. Generally, these restrictions require large computational domains, implying higher costs for the numerical solver. An alternative method for coastal/harbor applications is proposed here. This approach is based on a perfectly matched layer (PML) that incorporates the effects of the exterior bathymetry. The model only requires constant exterior depth in the alongshore direction, a common approach used for idealizing the exterior bathymetry in elliptic models. In opposition to standard open boundary conditions for mild-slope models, the features of the proposed PML approach include (1) completely noncollinear coastlines, (2) better representation of the real unbounded domain using two different lateral sections to define the exterior bathymetry, and (3) the generation of reliable solutions for any incoming wave direction in a small computational domain. Numerical results of synthetic tests demonstrate that solutions are not significantly perturbed when open boundaries are placed close to the area of interest. In more complex problems, this provides important performance improvements in computational time, as shown for a real application of harbor agitation.Peer ReviewedPostprint (author's final draft

Quid Pro Quo: A Mechanism for Fair Collaboration in Networked Systems

Collaboration may be understood as the execution of coordinated tasks (in the most general sense) by groups of users, who cooperate for achieving a common goal. Collaboration is a fundamental assumption and requirement for the correct operation of many communication systems. The main challenge when creating collaborative systems in a decentralized manner is dealing with the fact that users may behave in selfish ways, trying to obtain the benefits of the tasks but without participating in their execution. In this context, Game Theory has been instrumental to model collaborative systems and the task allocation problem, and to design mechanisms for optimal allocation of tasks. In this paper, we revise the classical assumptions and propose a new approach to this problem. First, we establish a system model based on heterogenous nodes (users, players), and propose a basic distributed mechanism so that, when a new task appears, it is assigned to the most suitable node. The classical technique for compensating a node that executes a task is the use of payments (which in most networks are hard or impossible to implement). Instead, we propose a distributed mechanism for the optimal allocation of tasks without payments. We prove this mechanism to be robust event in the presence of independent selfish or rationally limited players. Additionally, our model is based on very weak assumptions, which makes the proposed mechanisms susceptible to be implemented in networked systems (e.g., the Internet).Comment: 23 pages, 5 figures, 3 algorithm

La caja de Pandora: dialogía y crítica a partir del Quijote

[email protected] vez planteado que el pulso de la dialogía constituye la existencia y la práctica de todo lenguaje como territorio común entre hablante y oyente, el autor apela al Quijote, convertido en una suerte de antigénero autorreflexivo y plurilógico, para someter a crítica los postulados de la modernidad, atrapada entre la fantasmagoría que cumple en Frankenstein la función de una amenaza trágica y la afirmación de soberanía encarnada en Robinson Crusoe en virtud de su nueva definición universalista e individualista de la subjetividad.Once raised that the pulse of the dialogia constitutes the existence and the practice of any language as common territory between speaker and listener, the author appeals to the Quixote, turned into a luck of self-reflective and plurilogic antigenre, to submit to critique the approaches of the modernity, caught between the phantasmagoria that fulfills in Frankenstein the function of a tragic threat and the affirmation of sovereignty personified in Robinson Crusoe by virtue of his new universalistic and individualistic definition of subjectivity

El proceso de creación de juegos de golpeo y fildeo mediante la hibridación de modelos de enseñanza

The initial occasional experiences designed to promote the invention of games by the students in physical education settings have evolved towards the creation of more structured and extensive teaching units. In the design of these new units, teachers tend to use various teaching models in order to increase the educational potential and the desired results. In this article, we review the existing literature on the design of games and we show the elements of each instructional model that articulate our proposal. Finally,we present and comment an experience carried out with students of 1º ESO (first year of Secondary Compulsory Education), where studentswere invited to create sports games of hitting and fielding. Under the framework of the Sport Education Model, the structure of the teaching unit responded to an eclectic approach that emphasized understanding, cooperation and creativity.Las experiencias puntuales dirigidas a la creación de juegos deportivos por el alumnado de Educación Física han dado paso a unidades didácticas más estructuradas y extensas abordadas bajo la combinación de varios modelos de enseñanza que permiten aumentar su potencial didáctico y multiplicar los resultados deseados. En este artículo realizamos una revisión de los trabajos dirigidos al diseño de juegos por el alumnado, mostramos los elementos de los modelos de enseñanza que articulan nuestra propuesta e informamos de una experiencia realizada con alumnado de 1º de ESO al que invitamos a crear juegos deportivos de golpeo y fildeo en una unidad didáctica estructurada bajo el marco del Modelo de "Sport Education" y a través de los enfoques de enseñanza comprensivo, cooperativo y creativo

Bailando con la destrucción. Sobre cultura común y música popular en la Transición Española (1977-1987)

Resumen; El artículo analiza desde una perspectiva crítica el legado musical de los años de la llamada Transición, poniendo el foco en las relaciones entre música y sociedad que tan poca consideración han tenido desde la crítica musical y la musicología, áreas desde las que se han realizado aproximaciones partiendo de una visión de la música como un ámbito estético autónomo más que como una práctica social. El artículo pone el acento en los espacios de conflicto generados por las prácticas musicales de la época y en las estrategias de borramiento de ese conflicto con las que se ha tratado de abordar, en los últimos años, el periodo y su escena musical. Palabras Clave: Transición Española, música, sociedad, práctica social.  Abstract: This article analyzes the musical legacy of the Spanish Transition to democracy from a critical perspective. Musical criticism and Musicology have studied music as an autonomous aesthetic field, instead of a social praxis. Remarkably, the academic world has not paid much attention to the relationship between music and society. This article stresses out the space of conflict generated by musical experiences during that period of time and the strategies that have been applied over the past few decades in what we consider to be an attempt to erase it.Key Words: Spanish Transition to Democracy, music, society, social practice

Sobre la interiorización del espacio social.

El autor explora la dinámica y relaciones entre el mundo exterior y el mundo interior en los diferentes tipos de mensajes y productos de los medios de comunicación, revisando las raíces culturales, ideológicas, sociales que los distintos tipos de expresión de esa relación indican. Las distintas formas de reproducción cultural van creando pasajes y espacios virtuales que mediatizan el espacio para vincularlo con el mundo interior. Sobre todo, encuentra el autor que la mediatización o informatización del espacio público debe vincularse con la voluntad de poder propia del capitalismo moderno en su vertiente expansionista y privatizante, y es necesario estudioar a fondo los fenómenos que conectan la expansión de los espacios culturales de mediación y la expansión de los fenómenos de interiorización del espacio público.The author explores the relationships between the exterior world and the inner world in the diverse types of messages and reproducing products of the mass media, analyzing the cultural roots, the ideological, political, and social features that these relationships show. The different reproducing cultural forms create passages and virtual spaces which mediates the space to link it with the inner life. Above all, the author finds that the meditating and informative processing of the public space has a direct link with the modern capitalism in its expansive and privatizing tendency, and it is essential to study today into depth the processes which connect the expansion pf cultural and informative spaces with the insight of the public [email protected]

The profitability of value-added products in dairy farm diversification initiatives

A more open and competitive dairy market has encouraged certain dairy farms to adopt value-adding strategies in order to achieve a higher profitability, which may be important for farms’ survival. This paper investigated the role of some product characteristics in the profitability of value-added products in these farms. For this purpose, we used a unique database of 265 different products commercialized by 49 Spanish dairy farms that offers information on nine attributes of each product. Using hedonic models as a baseline, we examined the influence of these attributes on the margin per liter (ML) of the products. The results of the regression indicated that cheese and yogurt generated 0.688 and 1.518 € more of margin per liter than liquid milk. Similarly, we found a set of attributes that have a positive influence on ML, including possession of a certificate of protected designation of origin (PDO), the milk-type composition (proportion of sheep milk), a longer expiration period, and involvement in direct marketing strategies (DMS). However, other recognized attributes such as organic labeling, maturation period, size of the sales unit and returnable packaging did not have a significant influence on ML. Our findings also showed that firms producing more elaborated products as cheese and yogurt need a lower percentage of their production to cover the fixed costs associated to transformation and commercialization. Overall, our results revealed that the elaboration of value-added dairy products improves the profitability of dairy farms