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)

Derivation of a multilayer approach to model suspended sediment transport: application to hyperpycnal and hypopycnal plumes

We propose a multi-layer approach to simulate hyperpycnal and hypopycnal plumes in flows with free surface. The model allows to compute the vertical profile of the horizontal and the vertical components of the velocity of the fluid flow. The model can describe as well the vertical profile of the sediment concentration and the velocity components of each one of the sediment species that form the turbidity current. To do so, it takes into account the settling velocity of the particles and their interaction with the fluid. This allows to better describe the phenomena than a single layer approach. It is in better agreement with the physics of the problem and gives promising results. The numerical simulation is carried out by rewriting the multi-layer approach in a compact formulation, which corresponds to a system with non-conservative products, and using path-conservative numerical scheme. Numerical results are presented in order to show the potential of the model

Assessment of geodiversity in the southern part of the Central Iberian Zone (Jaén Province): usefulness for delimiting and managing natural protected areas

To explore the relationship between geodiversity and borders of natural protected areas, we studied the northern part of Jaén Province (southern Spain), where the southern sector of the Central Iberian Massif, the Betic Cordillera and the Guadalquivir foreland basin come together. Moreover, several natural protected areas (NPAs) are located here. To approach the topic, we defined the geodiversity index as the sum of partial indices: lithological, geomorphological, palaeontological, pedological, minerals, hydrology and geosites. This made it possible to derive a map of the geodiversity index and a map of geodiversity gradient. Analysis of their distribution shows that almost 80% of the territory has values of medium, high and very high geodiversity, but these zones are situated outside the borders of the NPAs. A similar study considering two biological indices (endangered species and biodiversity) shows a good correlation between the limits of NPAs and the higher values of these indices. Thus, an absence of correlation between the geodiversity index and biological indices is clearly detected. These results are not in agreement with the definition of NPAs in the current Spanish laws of nature conservation.This research was funded by the Project Evaluación de la geodiversidad y del patrimonio geológico. Utilidad para la delimitación y gestión de espacios naturales protegidos. Aplicación en parques y monumentos naturales del norte de la Provincia de Jaén (Centre for Advanced Studies in Earth Sciences, University of Jaén, Spain) and by the Research Group RNM-200 (Junta de Andalucía)

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

Threading Through Macrocycles Enhances the Performance of Carbon Nanotubes as Polymer Fillers

In this work we study the reinforcement of polymers by mechanically interlocked derivatives of single-walled carbon nanotubes (SWNTs). We compare the mechanical properties of fibers made of polymers and of composites with pristine single-walled carbon nanotubes (SWNTs), mechanically interlocked derivatives of SWNTs (MINTs) and the corresponding supramolecular models. Improvements of both Young's modulus and tensile strength of up to 200 % were observed for the polystyrene-MINTs samples with an optimized loading of just 0.01 wt.%, while the supramolecular models with identical chemical composition and loading showed negligible or even detrimental influence. This behavior is found for three different types of SWNTs and two types of macrocycles. Molecular dynamics simulations show that the polymer adopts an elongated conformation parallel to the SWNT when interacting with MINT fillers, irrespective of the macrocycle chemical nature, whereas a more globular structure is taken upon facing with either pristine SWNTs or supramolecular models. The MINT composite architecture thus leads to a more efficient exploitation of the axial properties of the SWNTs and of the polymer chain at the interface, in agreement with experimental results. Our findings demonstrate that the mechanical bond imparts distinctive advantageous properties to SWNT derivatives as polymer fillers.Comment: 39 pages, 19 figure

A Hybrid Parameterization Technique for Speaker Identification

Classical parameterization techniques for Speaker Identification use the codification of the power spectral density of raw speech, not discriminating between articulatory features produced by vocal tract dynamics (acoustic-phonetics) from glottal source biometry. Through the present paper a study is conducted to separate voicing fragments of speech into vocal and glottal components, dominated respectively by the vocal tract transfer function estimated adaptively to track the acoustic-phonetic sequence of the message, and by the glottal characteristics of the speaker and the phonation gesture. The separation methodology is based in Joint Process Estimation under the un-correlation hypothesis between vocal and glottal spectral distributions. Its application on voiced speech is presented in the time and frequency domains. The parameterization methodology is also described. Speaker Identification experiments conducted on 245 speakers are shown comparing different parameterization strategies. The results confirm the better performance of decoupled parameterization compared against approaches based on plain speech parameterization

Geometric Phases and Mielnik's Evolution Loops

The cyclic evolutions and associated geometric phases induced by time-independent Hamiltonians are studied for the case when the evolution operator becomes the identity (those processes are called {\it evolution loops}). We make a detailed treatment of systems having equally-spaced energy levels. Special emphasis is made on the potentials which have the same spectrum as the harmonic oscillator potential (the generalized oscillator potentials) and on their recently found coherent states.Comment: 11 pages, harvmac, 2 figures available upon request; CINVESTAV-FIS GFMR 11/9

Evaluación de la asignatura Exploración Topográfica Manual

[Resumen] En este artículo exponemos los objetivos generales y específicos, los contenidos y la metodología de enseñanzas y evaluación de una asignatura de libre configuración ofertada por la Escuela Universitaria de Fisioterapia de la Universidad de A Coruña, cuyo título es Exploración Topográfica Manual[Abstract] A description is made o/ the general and specific aims, content, teaching method and evaluation of an optinal course offered at the University School o/ Physical Therapy o/ La Coruña, Spain, known as Manual Topographic Examination

A Course of Thermodynamics for an Industrial Engineering Degree using New Methodologies and Technologies

This paper presents the experience carried out at the Industrial Engineering School (ETSII) of the Universidad Politécnica de Madrid (UPM) for teaching Thermodynamics science using new methodologies and technologies. During the last two years a special course on Thermodynamics has been given to those students who failed to pass the ordinary examination. This group was made of around thirty students with some level of knowledge of the subject. Nontraditional teaching methodologies have been applied to this group stretching the potential of new technologies to the maximum possible extent. A complete e-learning system developed by our University called Aula Web was used to produce a weekly schedule for each individual student. Aula Web consists of several modules. News and Forum channel the communications with the student.“Contents” is a repository holding various types of learning material such us presentations, theoretical texts and problems with solutions. “Activities” assigns homework to the student who can submit it electronically. Finally, “Self-assessment” composes bespoke self-assessment tests resorting to a wide database of questions and short problems. A totally personalized long problem was programmed using MATLAB. The problem is structured in ten steps that help the student to progress towards his/her learning target. Upon conclusion of the learning program the student should have acquired all foreseen knowledge of the subject. Observed results are very satisfactory. Throughout the whole process the level of motivation of the students has been very high. The Universidad Politécnica de Madrid supports education innovation experiences through special programs whose main target is the convergence at the European Higher Education Space