Efficient numerical schemes for viscoplastic avalanches. Part 2: the 2D case

This paper deals with the numerical resolution of a shallow water viscoplastic flow model. Viscoplastic materials are characterized by the existence of a yield stress: below a certain critical threshold in the imposed stress, there is no deformation and the material behaves like a rigid solid, but when that yield value is exceeded, the material flows like a fluid. In the context of avalanches, it means that after going down a slope, the material can stop and its free surface has a non-trivial shape, as opposed to the case of water (Newtonian fluid). The model involves variational inequalities associated with the yield threshold: finite volume schemes are used together with duality methods (namely Augmented Lagrangian and Bermúdez–Moreno) to discretize the problem. To be able to accurately simulate the stopping behavior of the avalanche, new schemes need to be designed, involving the classical notion of well-balancing. In the present context, it needs to be extended to take into account the viscoplastic nature of the material as well as general bottoms with wet/dry fronts which are encountered in geophysical geometries. Here we derive such schemes in 2D as the follow up of the companion paper treating the 1D case. Numerical tests include in particular a generalized 2D benchmark for Bingham codes (the Bingham–Couette flow with two non-zero boundary conditions on the velocity) and a simulation of the avalanche path of Taconnaz in Chamonix—Mont-Blanc to show the usability of these schemes on real topographies from digital elevation models (DEM)

Validation and Adaptation of the Prosocial and Antisocial Behavior in Sport Scale to the Spanish context of Physical Education

Physical education (PE), by its own characteristics, is a subject where social communication is especially promoted. However, it is necessary to have tools that evaluate the social behaviour of students during PE classes. For this reason, we propose to validate and adapt the Prosocial and Antisocial Behavior in Sport Scale to the Spanish context of PE classes. The study involved 1081 students aged 12 to 18 (M = 14.83; SD = 1.27). The psychometric properties of the Prosocial Behavior Scale were analyzed through several statistical analyses. The results of the confirmatory factorial analysis and the exploratory factorial analysis supported the internal structure of the questionnaire. In addition, the scale was invariant to gender. Cronbach’s alpha values were higher than 0.70 in the factors and sub-factors, finally showing adequate levels of temporal stability. Taking into account the results achieved in the present study, PE teachers have an effective tool to assess the social and antisocial behaviour of their students’ students during PE classes

Efficient numerical schemes for viscoplastic avalanches. Part 1: The 1D case.

This paper deals with the numerical resolution of a shallow water viscoplastic flow model. Viscoplastic materials are characterized by the existence of a yield stress: below a certain critical threshold in the imposed stress, there is no deformation and the material behaves like a rigid solid, but when that yield value is exceeded, the material flows like a fluid. In the context of avalanches, it means that after going down a slope, the material can stop and its free surface has a non-trivial shape, as opposed to the case of water (Newtonian fluid). The model involves variational inequalities associated with the yield threshold: finite-volume schemes are used together with duality methods (namely Augmented Lagrangian and Bermúdez–Moreno) to discretize the problem. To be able to accurately simulate the stopping behavior of the avalanche, new schemes need to be designed, involving the classical notion of well-balancing. In the present context, it needs to be extended to take into account the viscoplastic nature of the material as well as general bottoms with wet/dry fronts which are encountered in geophysical geometries. We derived such schemes and numerical experiments are presented to show their performances

On-board quality preservation of megrim (Lepidorhombus whiffiagonis) by a novel ozonised-slurry ice system

6 páginas, 3 tablas.-- The final publication is available at www.springerlink.comThe use of a combined ozonised-slurry ice system was investigated as a new refrigeration system for the on-board storage of megrim (Lepidorhombus whiffiagonis), a fish species that is usually stored aboard fishing vessels for 1 to 2 weeks. The time elapsed between the catch and unloading at the harbour affects its quality and commercial value directly. Microbiological, chemical and sensory analyses were carried out in megrim after 2 weeks of onboard storage in ozonised slurry ice, slurry ice or flake ice, and for an additional period of 6 days. Sensory analyses revealed that megrim specimens stored in ozonised slurry ice (oSI600 batch) maintained A quality even after 20 days of storage, while counterpart batches stored in flake ice showed B quality at unloading, after 14 days of on-board storage. Storage in ozonised slurry ice (oSI600 batch) also led to significantly (p<0.05) lower counts of aerobic mesophiles, psychrotrophic bacteria, Enterobacteriaceae and proteolytic microorganisms in megrim muscle as compared with flake ice. Biochemical analyses revealed that the use of ozonised-slurry ice or slurry ice alone slowed down the formation of total volatile base-nitrogen (TVBN) and trimethylamine-nitrogen (TMA-N) in comparison with storage in flake ice, also allowing a better control of pH. Lipid hydrolysis and oxidation events also occurred at a lower rate in the ozonised-slurry ice and slurry ice batches than in the flake ice batch. The present study demonstrates that the combination of slurry ice and ozone for the on-board storage of megrim is advisable, thus improving the quality and extending the shelf life of this fish species.This work was supported through a project grant by the Secretar´ıa Xeral de I+D from the Xunta de Galicia (Project PGIDIT04TAL015E).Peer reviewe

Desigualdad, bienestar y estadísticos ordenados

En este trabajo se definen, a partir de las distribuciones de los estadísticos ordenados, funciones que cumplen las propiedades adecuadas para representar las preferencias sociales en relación a las distribuciones de renta. Ello permite, aplicando el enfoque de Yaari (1987, 1988), construir un conjunto de funciones de bienestar social, de las que se derivan sus correspondientes índices de desigualdad. Las medidas así obtenidas incorporan criterios normativos muy diversos, con diferentes grados de preferencia por la igualdad. Se obtienen, como casos particulares, los índices de Gini generalizados (Kakwani (1980), Donaldson y Weymarck (1980, 1983), Yitzhaki (1983)) y la familia de índices propuesta en Aaberge (2000). El enfoque utilizado demuestra que cada una de estas familias de índices caracteriza la distribución de la renta, salvo un cambio de escal

Some applications of quasi-velocities in optimal control

In this paper we study optimal control problems for nonholonomic systems defined on Lie algebroids by using quasi-velocities. We consider both kinematic, i.e. systems whose cost functional depends only on position and velocities, and dynamic optimal control problems, i.e. systems whose cost functional depends also on accelerations. The formulation of the problem directly at the level of Lie algebroids turns out to be the correct framework to explain in detail similar results appeared recently (Maruskin and Bloch, 2007). We also provide several examples to illustrate our construction.Comment: Revtex 4.1, 20 pages. To appear in Int. J. Geom. Meth. Modern Physic

Precautionary savings as an instrument to hedge the risk of hydrological drought in irrigated agriculture

This paper explores the use of precautionary savings as a new risk management instrument that can be implemented to hedge hydrological drought risk in irrigated agriculture, a risk currently not covered by any policy instrument. For this purpose, the Drought Savings Account (DSA) is proposed as a personal savings account to which farmers make regular contributions, with withdrawals allowed in the event of irrigation water supply gaps in order to guarantee a minimum income. The implementation of the DSA is empirically assessed in a Mediterranean-climate irrigation district using an innovative simulation approach. Based on the results obtained, the DSA has proved to be a theoretically suitable policy instrument that can overcome the problems hindering the implementation of agricultural insurance, managing the risk in a more cost-effective way. This cost-effectiveness is a key advantage of precautionary savings over agricultural insurance, since the former instrument minimizes moral hazard and adverse selection problems, and the transaction costs of risk-sharing. Moreover, in this context, precautionary savings may play a significant role as an efficient climate change adaptation measure since the self-insurance strategy adopted does not distort the signals underlying farmers’ own risk exposure, leading to better individual assessment and an adequate management of water supply gaps

Promoting higher added value to a finfish species rejected to sea

332 páginas.-- José Ramón Fuertes ... et al.This project aimed to the development of the research and the technology necessary to promote higher added value to fishing activity. This is to be achieved by obtaining profit from a finfish species (“Rockcod”, Patagonotothen spp.) not known to consumers and currently discarded by the EU fishing fleet operating in the South West Atlantic, in order to supply the EU seafood industry with a good quality raw material for human food manufacturing. Use of this species, caught as a by-catch in the existing fisheries targeting hakes and cephalopods, should also increase the profitability of the fleet, contribute to maintaining employment and help to counterbalance the negative effects of fishing activity and discards in the ecosystem. The main scientific-technological objectives and expected achievements were the following: - Description of the fisheries - Improved knowledge of the biology of the species - Biomass assessment - Estimation of catches and discards - Analysis of the spatial and temporal distribution of the resource. Fishery forecasting and testing - Sensorial, Microbiological, Nutritional and Biochemical Evaluation of Rock cod - Development of the technical modifications on board commercial vessels - Development of new processed products from frozen Rock codContract number Q5CR-2002-71709Peer reviewe