Low-Dimensional Modelling for optimal streaks in the blasius boundary layer

This paper is concerned with the low dimensional structure of optimal streaks in the Blasius boundary layer. Optimal streaks are well known to exhibit an approximate self-similarity, namely the streamwise velocity re-scaled with their maximum remains almost independent of both the spanwise wavenumber and the streamwise coordinate. However, the reason of this self-similar behavior is still unexplained as well as unexploited. After revisiting the structure of the streaks near the leading edge singularity, two additional approximately self-similar relations involving the velocity components and their wall normal derivatives are identified. Based on these properties, we derive a low dimensional model with two degrees of freedom. The comparison with the results obtained from the linearized boundary layer equations shows that this model is consistent and provide good approximations.

Automatic generation of real-time deformable parametric model of the aorta for a VR-based catheterism guidance system

The purpose of this work is twofold: first, to develop a process to automatically create parametric models of the aorta that can adapt to any possible intraoperative deformation of the vessel. Second, it intends to provide the tools needed to perform this deformation in real time, by means of a non-rigid registration method. This dynamically deformable model will later be used in a VR-based surgery guidance system for aortic catheterism procedures, showing the vessel changes in real time.

E-MIS validity applied to TELMA enhanced learning environment

Enhanced learning environments are arising with great success within the field of cognitive skills training in minimally invasive surgery (MIS) because they provides multiple benefits since they avoid time, spatial and cost constraints. TELMA [1,2] is a new technology enhanced learning platform that promotes collaborative and ubiquitous training of surgeons. This platform is based on four main modules: an authoring tool, a learning content and knowledge management system, an evaluation module and a professional network. TELMA has been designed and developed focused on the user; therefore it is necessary to carry out a user validation as final stage of the development. For this purpose, e-MIS validity [3] has been defined. This validation includes usability, contents and functionality validities both for the development and production stages of any e-Learning web platform. Using e-MIS validity, the e-Learning is fully validated since it includes subjective and objective metrics. The purpose of this study is to specify and apply a set of objective and subjective metrics using e-MIS validity to test usability, contents and functionality of TELMA environment within the development stage.

Agile user stories enriched with usability

Usability is a critical quality factor. Therefore, like traditional software teams, agile teams have to address usability to properly catch their users experience. There exists an interesting debate in the agile and usability communities about how to achieve this integration. Our aim is to contribute to this debate by discussing the incorporation of particular usability recommendations into user stories, one of the most popular artifacts for communicating agile requirements. In this paper, we explore the implications of usability for both the structure of and the process for defining user stories. We discuss what changes the incorporation of particular usability issues may introduce in a user story. Although our findings require more empirical validation, we think that they are a good starting point for further research on this line.

Aircraft flight trajectory deviation in the standard instrument departures. Operators penalties.

In the recent years many problems are emerging due to the aircraft noise on the airport surrounding areas. The solution to this problem is not easy considering that the neighbourhood asks for the reduction of the number of aircraft operations and the airlines ask for a growing demand in the number of operations in the major airports. So the airport and regulatory authorities try to get a solution imposing a fine to the aircraft which its actual trajectory differs from the nominal one more than a lateral deviation. But, which is the value of this deviation?. The current situation is that many operators have to pay a lot of money for exceeding a deviation which has been established without operational criteria. This paper presents the results of a research program which is being carried out by the authors which aims to determine the "delta" deviation to be used for this purpose. In addition it is proposed a customized method per SID and per airport to be used for determining the maximum allowed lateral deviation by which if the aircraft is within it, then none fine will be imposed.

Stresses and stability of a mine paste fill

Se describe el comportamiento de los rellenos de pasta de las cámaras primarias de la mina de Aguas Teñidas y se calcula la resistencia que deben tener dichos rellenos para que no se desmoronen las paredes de los mismos que quedan expuestas al extraer las cámaras secundarias.Abstract:This article presents the study carried out at an underground mine to understand the stress distribution in the paste fills and to calculate the stability of the paste walls. The mine is operated using sublevel stopes. Three-dimensional numerical models designed with the FLAC 3D software are used to study the distribution of the vertical stresses in the paste. The numerical models have demonstrated that an arc-like effect is produced in the paste fills of the primary stopes. This effect relieves the vertical stresses and increases the stability of the exposed paste wall fill. Based on the results of the numerical models, in the 30m high secondary stopes, the arc effect starts to be evident only in paste walls with a width/height ratio lower than 0.8. 3-D calculations show that the use of Mitchell, R. J. et al. (1982) formula may be risky when estimating the fill stability in secondary stopes.

Influence of the semantic content of urban sounds in the identity of outer spaces

This paper shows the influence of the semantic content of urban sounds in the subjective evaluation of outer spaces. The study is based on the analysis conducted in three neighboring and integrated urban spaces with a different form of social ownership in the city of Cordoba, Argentina. It shows that the type of sound source present at each site influence, by its semantic content, in the user´s identification and permanence in the place. The noise present in a soundscape is able to have a high semantic content, and therefore the sound has a particular meaning for the perceiver. Every particular social group influences the production of their own sounds and how they perceive them. This allows to consider the sound as one of the factors that define the sense of "place" or "no place" of a certain urban space. Evidently the sounds, and their ability to evoke and characterize the environment, cannot be ignored in the construction and recovery of anthropological sites. This urban culture is unique and specific to every society. Thepublic spaces, with their soundscape, are part of the construction of the urban identity of a city. It is shown that for identical general sound levels present in each of the spaces, the level of annoyance or discomfort, in relation to the subjective acoustic quality, is different. This is the result of the influence of semantic content of the sounds present in each urban space. Coinciding with other similar research, the level of discomfort or annoyance decreases as the presence of natural sounds such as water, the wind in the trees or the birds singing increases, even when the objective values of noise level of natural sounds are higher.

Perfect imaging of point sources with positive refraction

The capability of a device called the Spherical Geodesic Waveguide (SGW) to produce images with details below the classic Abbe diffraction limit (super-resolution) is analyzed here. The SGW is an optical system equivalent (by means of Transformation Optics) to the Maxwell Fish Eye (MFE) refractive index distribution. Recently, it has been claimed that the necessary condition to get super-resolution in the MFE and the SGW is the use of a Perfect Point Drain (PPD). The PPD is a punctual receptor placed in the focal point that absorbs the incident wave, without reflection or scattering. A microwave circuit comprising three elements, the SGW, the source and the drain (two coaxial lines loaded with specific impedances) is designed and simulated in COMSOL. The super-resolution properties have been analyzed for different position of the source and drain and for two different load impedances: the PPD and the characteristic line impedance. The results show that in both cases super-resolution occurs only for discrete number of frequencies. Out of these frequencies, the SGW does not show SR in the analysis carried out.

Sistemas de control de ventilación en túneles

La entrada en vigor del R.D. 635 del año 2006, sobre los requisitos mínimos de seguridad en túneles de carreteras establece la necesidad de profundizar en las características y prestaciones a exigir para los sistemas informáticos de control de ventilación en túneles tanto para las situaciones de servicio como de incendio. En general, este tipo de sistemas tienen como objetivo fundamental lograr la reducción de los tiempos de respuesta por parte de los sistemas y del personal de explotación, a la vez que aportar la mayor flexibilidad posible en las pautas de actuación manuales y automáticas. Sin embargo, las aplicaciones informáticas a implementar precisan tener en cuenta las diferencias en las tipologías de los sistemas de ventilación y las condiciones distintas que se pueden dar en la explotación del túnel, como por ejemplo, el tráfico denso o fluido en el interior del túnel en caso de incidente. Esto requiere estrategias de ventilación complejas que en algunos casos pueden ser predefinidas en el sistema de control. Con el objetivo de optimizar el funcionamiento de la ventilación es posible desarrollar algoritmos de control que establecen actuaciones sobre los distintos equipos en función de las condiciones previas al inicio del incidente pero también la evolución de las mismas durante el mismo. En consecuencia, el presente artículo intenta reflejar las tendencias y alternativas que puedan contemplarse para el control de los humos en caso de túneles planteados desde un punto de vista tanto teórico, en función de las recomendaciones internacionales, como práctico al incorporar resultados de medida in situ obtenidas en la verificación de sistemas de este tipo implementados sistemas de control de túneles en explotación.

Reparación de los desagües de fondo de la presa de la Fuensanta utilizando las válvulas de seguridad como escudos frontales

La presa de la Fuensanta se construyó hace más de 75 años. Los desagües de fondo, alojados en el tapón de cierre del túnel de desvío del río, son dos conductos rectangulares de sección abocinada, maniobrados con válvulas de compuerta que evacuan directamente el vertido a la galería. Dada la antigüedad de los equipos mecánicos, y su estado de deterioro, se ha procedido a su renovación. Los problemas habituales de estas actuaciones (existencia de sedimentos y desprendimientos en el área de la embocadura, falta de conocimiento de las formas geométricas de las zonas ocultas por el agua, defectos de construcción no documentados, deterioro de los blindajes, dificultad de acceso, etc) se han resuelto en esta obra acondicionando las antiguas válvulas de seguridad de los conductos para utilizarlas como escudos frontales, lo que ha permitido sustituir y ampliar los blindajes de acero, e instalar las nuevas compuertas de aguas abajo.

Mars: a personalised mobile activity recognition system

Mobile activity recognition focuses on inferring the current activities of a mobile user by leveraging the sensory data that is available on today’s smart phones. The state of the art in mobile activity recognition uses traditional classification learning techniques. Thus, the learning process typically involves: i) collection of labelled sensory data that is transferred and collated in a centralised repository; ii) model building where the classification model is trained and tested using the collected data; iii) a model deployment stage where the learnt model is deployed on-board a mobile device for identifying activities based on new sensory data. In this paper, we demonstrate the Mobile Activity Recognition System (MARS) where for the first time the model is built and continuously updated on-board the mobile device itself using data stream mining. The advantages of the on-board approach are that it allows model personalisation and increased privacy as the data is not sent to any external site. Furthermore, when the user or its activity profile changes MARS enables promptly adaptation. MARS has been implemented on the Android platform to demonstrate that it can achieve accurate mobile activity recognition. Moreover, we can show in practise that MARS quickly adapts to user profile changes while at the same time being scalable and efficient in terms of consumption of the device resources.

On the Degree of Team Cooperation in CD Grammar Systems.

In this paper, we introduce a dynamical complexity measure, namely the degree of team cooperation, in the aim of investigating "how much" the components of a grammar system cooperate when forming a team in the process of generating terminal words. We present several results which strongly suggest that this measure is trivial in the sense that the degree of team cooperation of any language is bounded by a constant. Finally, we prove that the degree of team cooperation of a given cooperating/distributed grammar system cannot be algorithmically computed and discuss a decision problem.

Mechanical properties of peanut varieties

On the efforts for rationalizing the production of peanuts in Spain, one of the objectives was to obtain a well adapted variety, suitable for mechanization. We tried to get information on the characteristics that would condition the suitability of a variety to mechanized production, principally mechanical harvesting. All the characters studied would then be taken into account in a breeding program.

Impact bruises in pomaceae fruits: Evaluation methods and structural features.

Using a laboratory impact tester, impacts were applied to fruits of different varieties of apples and pears. The response to impact was analized, and many parameters were recorded, to be correlated to bruise susceptibility and to ripeness changes. Different methods for the detection and evaluation of the bruised Area and its features were studied, using direct observation and various reactives. Different types of bruises were established.

Facing informatics via three level complexity views

In informatics there is one kind of complexity that is perceived by everyone. It is the complexity of a concrete, isolated object, normally situated completely within one of the branches universally recognized by the scientific and technical community. Examples of this are the complexity of integrated electronic circuits, the complexity of lgorithms and the complexity of software. The first complexity deals with the number of circuit components, the second with computation time and the third with the number of necessary mental discriminations. In arder to illustrate my point, I will take up the last complexity, which, m o reo ver, is the least well-known.