La organización a gran escala de canales turbulentos

En esta tesis se investigan el origen y la organización de las estructuras grandes que se encuentran en las regiones logarítmica y exterior de la turbulencia parietal. Estas estructuras contienen la mayor parte de la energia cinética turbulenta, son responsables de una fracción apreciable de la resistencia de fricción y juegan un papel fundamental en el transporte turbulento. A pesar de su relevancia, existe mucha menos información acerca de las estructuras grandes que acerca de las estructuras pequeñas de la región de la pared. Esto se debe a la dificultad que entraña su análisis. Para nuestro estudio hacemos uso de los resultados de nuevos experimentos numéricos del flujo turbulento en canales planos, realizados a números de Reynolds, ,más altos y en dominios computacionales más grandes que los existentes hasta la fecha. Parte de los resultados de estos experimentos está disponible en el sitio http://torroja.dmt.upm.es/ftp/channels. alojado en España, o en la réplica http://davinci.tam.uiuc.edu/data/channels. alojada en EE. UU. También es posible acceder a la base de datos completa siguiendo el procedimiento indicado en htlp://davinci.tam.uiuc.edu/content/Channeldata.html. Los resultados indican que las fluctuaciones turbulentas de velocidad en las direcciones paralelas a la pared se organizan formando estructuras muy grandes, cuyo tamaño escala con el espesor del flujo. Estas estructuras, que hemos denominado modos globales, penetran desde el centro del canal hasta la zona de la pared, lo cual explica el escalado incompleto del espectro de energía en esta región. Hemos mostrado que la escala de velocidad de los modos globales es la velocidad media en el centro del canal, llegando a un escalado mixto para en la región exterior, que se reduce a - para. Hemos estudiado las propiedades de semejanza del espectro de energía en la regióN intermedia del flujo, encontrando anomalías en la relación entre las longitudes yanchuras de las escalas grandes de . La forma del escalado anómalo, -, sugiere que las estructuras grandes de son estelas dejadas por objetos compactos de v y W, las cuales se difunden bajo el efecto de la viscosidad turbulenta -. Este fallo de semejanza conduce a correcciones logaritmicas en varios rangos del espectro clásico, que han sido comprobadas usando datos de nuestras simulaciones y de experimentos de laboratorio provenientes de distintos flujos de pared a números de Reynolds mayores que los nuestros. Se ha analizado el origen de las estructuras grandes de la capa logaritmica, hallando que este se encuentra en eyecciones intensas que provienen de la región de la pared. Para este análisis hemos desarrollado un método que permite aislar y clasificar las eyecciones, basándonos en la evidencia de que están asociadas a racimos de torbellinos arraigados en la pared que alcanzan la región intermedia. El campo de velocidad medio condicionado a cada una de estas eyecciones revela una estructura muy larga de,cuya geometría es consistente con el escalado anómalo del espectro en la región intermedia. Estos resultados proporcionan una base estructural para nuestro modelo basado en estelas

Extracting knowledge through friendsourcing: application to new financial services

Personalization has become a key factor for the success of new ICT services. However, the personal information required is not always available in a single site, but scattered in heterogeneous sources, and extracting knowledge from raw information is not an easy job. As a result, many organizations struggle to obtain knowledge on their users useful enough for their business purposes. This paper introduces a comprehensive personal data framework that opens the knowledge extraction process up to collaboration by the involvement of new actors, while enabling users to monitor and control it. The contributions have been validated in a financial services scenario where socioeconomic knowledge on some users is generated by tapping into their social network and used to assists them in raising money from their friends

Creating and modelling personal socio-economic networks in on-line banking

The banking industry is observing how new competitors threaten its millennial business model by targeting unbanked people, offering new financial services to their customer base, and even enabling new channels for existing services and customers. The knowledge on users, their behaviour, and expectations become a key asset in this new context. Well aware of this situation, the Center for Open Middleware, a joint technology center created by Santander Bank and Universidad Politécnica de Madrid, has launched a set of initiatives to allow the experimental analysis and management of socio-economic information. PosdataP2P service is one of them, which seeks to model the economic ties between the holders of university smart cards, leveraging on the social networks the holders are subscribed to. In this paper we describe the design principles guiding the development of the system, its architecture and some implementation details

A personal data framework for exchanging knowledge about users in new financial services

Personal data is a key asset for many companies, since this is the essence in providing personalized services. Not all companies, and specifically new entrants to the markets, have the opportunity to access the data they need to run their business. In this paper, we describe a comprehensive personal data framework that allows service providers to share and exchange personal data and knowledge about users, while facilitating users to decide who can access which data and why. We analyze the challenges related to personal data collection, integration, retrieval, and identity and privacy management, and present the framework architecture that addresses them. We also include the validation of the framework in a banking scenario, where social and financial data is collected and properly combined to generate new socio-economic knowledge about users that is then used by a personal lending service

Engineering privacy requirements valuable lessons from another realm

The Privacy by Design approach to systems engineering introduces privacy requirements in the early stages of development, instead of patching up a built system afterwards. However, 'vague', 'disconnected from technology', or 'aspirational' are some terms employed nowadays to refer to the privacy principles which must lead the development process. Although privacy has become a first-class citizen in the realm of non-functional requirements and some methodological frameworks help developers by providing design guidance, software engineers often miss a solid reference detailing which specific, technical requirements they must abide by, and a systematic methodology to follow. In this position paper, we look into a domain that has already successfully tackled these problems -web accessibility-, and propose translating their findings into the realm of privacy requirements engineering, analyzing as well the gaps not yet covered by current privacy initiatives

Protection of Personal Information in User-centric Converged Service Platforms.

The so-called User-Generated Services (UGS) provide users with the means to create and share their own advanced services that better fit their needs or those of their communities. Platforms supporting UGS for non-technically skilled users are becoming popular, both in the Internet and the Telecommunications domains. They provide creators with the means to include consumers' personal data or contextual information in order to generate attractive value-added services and also to improve the user-experience. However, the use and release of personal identifiable information poses several privacy and data protection concerns. In this paper we analyze the foreseeable problems and propose a solution for the protection of personal information on a UGS platform

Approaching unbanked people: a person-to-person payment application on Facebook

More than 2.5 billion people are still unbanked and they do not access or use financial services. In this paper, we present an innovative service that allows Santander University Smart Card holders to make person-to-person payments to their friends, using different social channels, such as Telegram, Facebook or Twitter. Our first implementation is based on Facebook, one of the most used social networks. This approach allows the service to reach a great number of potential users but the delivery and stability of the service depends on an external provider. We include the description of the service architecture, its implementation, tests, and the lessons learned from the development. We also discuss pros and cons of the third party service dependency from the technical and business viewpoints

A user-centric approach to service creation and delivery over next generation networks

Next Generation Networks (NGN) provide Telecommunications operators with the possibility to share their resources and infrastructure, facilitate the interoperability with other networks, and simplify and unify the management, operation and maintenance of service offerings, thus enabling the fast and cost-effective creation of new personal, broadband ubiquitous services. Unfortunately, service creation over NGN is far from the success of service creation in the Web, especially when it comes to Web 2.0. This paper presents a novel approach to service creation and delivery, with a platform that opens to non-technically skilled users the possibility to create, manage and share their own convergent (NGN-based and Web-based) services. To this end, the business approach to user-generated services is analyzed and the technological bases supporting the proposal are explained

Quantitative assessment and comparison of cloud service providers' privacy practices

The economic and technical advantages of cloud computing are widely recognized by the industry. However, the lack of knowledge on the privacy features offered by cloud service providers remains as one of the barriers for the adoption of cloud services. In this paper we describe a mechanism for the quantitative assessment of the privacy practices of different cloud service providers, so that cloud service clients can compare among them and choose the one that better fits their needs. Our contributions have been validated in three different scenarios

A User-Centric Service Creation Approach for Next Generation Networks

The architecture and technologies for the Next Generation Networks are well known. The service provision approach is not so clear though. While the Telecommunications killer application still remains to be found, new competitors in the new all-IP world threaten the traditional business models of telcos by providing their services directly to the operators' customers. An innovative paradigm has recently come about in the Internet which allows users to create and share their own services from the composition of other services. User-centric service creation environments improve the service offering with profitable, value-added services faster and cheaper than ever before. This paper presents the initial results of a research project that applies the user-centric approach to the creative combination of Web and network services over Next Generation Networks