Coste de los protocolos de seguridad en redes MANET

Los mecanismos de seguridad son uno de losrequisitos fundamentales para el buen funcionamiento de los protocolos de redes ad hoc móviles. En este artículo se analizan los problemas de seguridad de los protocolos de encaminamiento básicos, se describen las soluciones de seguridad existentes, y se hace un estudio del coste computacional y energético que supone para el sistema la inclusión de mecanismosde seguridad.

Joint physical-MAC layer design of the broadcast channel protocol in adhoc networks

Broadcast transmission mode in ad hoc networks is critical to manage multihop routing or providing medium accesscontrol (MAC)-layer fairness. In this paper, it is shown that ahigher capacity to exchange information among neighbors may beobtained through a physical-MAC cross-layer design of the broadcastprotocol exploiting signal separation principles. Coherentdetection and separation of contending nodes is possible throughtraining sequences which are selected at random from a reducedset. Guidelines for the design of this set are derived for a lowimpact on the network performance and the receiver complexity.

La intervenció educativa en el procés d'inserció laboral

La inserció laboral és un procés d' intervenció educati va, com un procés d'aprenentatge progressiu d 'habits personals, d 'habi litats socials, de competencies bas iques, professionals i transversals per al desenvolupament d' una ocupació que ha de portar la persona a la integració social i a una vida autonoma. La inserció laboral per competenc ies es proposa com a metodologia d' intervenc ió. Es fa una revisió de les competenc ies necessaries deis professionals de la inserció laboral encarregats d' aquesta intervenció i que acompanyen en els diferents moments de presa de decisions sobre I' itinerari professional de les persones amb dificultats d' inserc ió laboral.

Agenda deportiva

Aquesta memòria recull el procés seguit per al desenvolupament i implementació d’una aplicació Software. Aquest procés s’inicia amb la presentació del tema, estat de l’art i planificació temporal per continuar amb l’anàlisi de requeriments de l’aplicació —identificació dels interessats, entitats existents i les relacions d’aquestes...— el disseny de la mateixa —mètode de desenvolupament emprat, arquitectura...— la implementació de l’aplicació i les proves corresponents. Finalment la memòria es completa amb les conclusions i vies de continuació així com la bibliografia i annexos complementaris.

WiBed, A Platform for Commodity Wireless Testbeds

Testbeds are a stage between the simulation and the production stages. To this end they must be as close as possible to production environments (i.e. real hardware, on the field deployments) while also keeping the traits of experimentation facilities (i.e. fault tolerance, ease of deployment, testing and data collection). This paper presents WiBed, a FOSS platform for WiFi testbeds based on OpenWRT Linux made to run oncommodity IEEE802.11 WiFi routers part of the Community-lab.net project, a global testbed for Community networks. WiBedhas been designed to support realistic low layer network exper-iments (according to the OSI model). This work recolects thedetails of the architecture, design and implementation of WiBed consolidated during its operation as a testbed. In addition to a set of routing experimentation results obtained during the Wireless Battlemesh v7 where WiBed was used as testbed platform.

Estudi comparatiu dels filtres de Kalman i IMM per a navegació

Els sistemes híbrids de navegació integren mesures de posició i velocitat provinents de satèl·lits (GPS) i d’unitats de mesura inercials (IMU).Les dades d’aquests sensors s’han de fusionar i suavitzar, i per a aquest propòsit existeixen diversos algorismes de filtratge, que tracten les dades conjuntament o per separat. En aquest treball s’han codificat en Matlab els algorismes dels filtres de Kalman i IMM, i s’han comparat les seves prestacions en diverses trajectòries d’un vehicle. S’han avaluat quantitativament els errors dels dos filtres, i s’han sintonitzat els seus paràmetres per a minimitzar aquests errors. Amb una correcta sintonia dels filtres, s’ha comprovat que el filtre IMM és superior al filtre de Kalman, tant per maniobres brusques com per maniobres suaus, malgrat que la complexitat i el temps de càlcul requerit són majors.

Some of the challenges and experiences of formal education in a Mobile-Centric Society (MCS) = Algunos retos y experiencias de la educación formal en la Sociedad Móvil-Céntrica (SMC)

The aim of the paper is to describe some of the challenges faced by schools, or by formal education in general, as a consequence of today"s mobilecentric society (henceforth MCS), the term we will use to denote the new, networked learning ecology that has arisen from the massive penetration of digital media in everyday life. After revisiting some of the ideas of McLuhan and Vygotsky in the light of this new technological scenario, we describe five traits of the MCS and the challenges illustrated through educational practices that we believe schools will face if they wish to preserve their function of individualization and socialization. We believe that despite the emergence of the MCS, the main function of the school is still to provide the"box of tools" (a set of psychological instruments, such as reading, writing, mathematical notation, digital literacy, etc.) that enables people to develop their learning skills and life projects and to become part of communities and groups. However, the complexity and mobility of the new learning environments means that the position held by schools needs to be reevaluated in the face of the informal learning paths and experiences both online and offline to which learners now have access. We also need to reevaluate the meaning of the school itself as an institution and the model of learner it should be training

El estudio de los itinerarios escolares y post-escolares como pauta de reflexión en la construcción de una escuela y una sociedad para todos

La consecuencia lógica de la integración de las personas con necesidades educativas especiales en la institución escolar tendría que ser la anexión de estas a ámbitos normalizados de su colectividad una vez finalizada la escolaridad obligatoria. El discurso de la integración, por tanto, no se tendría que situar única y exclusivamente en el ámbito escolar, sino que debería extrapolarse a todos los ámbitos donde la persona se desarrolla. En este trabajo analizamos los itinerarios escolares y post-escolares que siguen las personas con discapacidad psíquica en la comarca del Segrià (Cataluña), apuntamos las posibles causas por las que se configuran unos itinerarios u otros y, a partir de ahí, establecemos pautas de reflexión para ir construyendo una escuela y una sociedad para todos.

Using vegetation to characterize the avalanche to Canal del Roc Roig, Vall de Núria (Eastern Pyrenees, Spain)

Avalanche hazard maps of high accuracy are difficult to produce. For land-use planning and management purposes, a good knowledge of extreme run-out zones and frequencies of avalanches is required. In the present work, vegetation recognition (especially focused on Pinus uncinata trees) and dendrochronological techniques are used to characterize avalanches that have occurred in historical times, helping to determine both the extent of large or extreme avalanches and their occurrence in time. Vegetation was studied at the Canal del Roc Roig (eastern Pyrenees, Spain) avalanche path. The avalanches descending this path affect the railway that reaches the Vall de Núria resort and the run-up to the opposite slope. During winter 1996, two important avalanches affecting this path were well documented. These are compared with the results of the vegetation study, consisting of an inventory of flora, the recording of vegetation damages along eight transverse profiles at different altitudes on the path and a dendrochronological sampling campaign. The data obtained contributed to a characterization of the predominant snow accumulation in the starting zone, the 1996 avalanches and the range of frequencies of large avalanches. Also, traces of avalanches that increase the path mapped in the avalanche paths map published by the Institut Cartogràfic de Catalunya in 2000 were identified, improving the initial existing information.

Using vegetation to characterize the avalanche to Canal del Roc Roig, Vall de Núria (Eastern Pyrenees, Spain)

Avalanche hazard maps of high accuracy are difficult to produce. For land-use planning and management purposes, a good knowledge of extreme run-out zones and frequencies of avalanches is required. In the present work, vegetation recognition (especially focused on Pinus uncinata trees) and dendrochronological techniques are used to characterize avalanches that have occurred in historical times, helping to determine both the extent of large or extreme avalanches and their occurrence in time. Vegetation was studied at the Canal del Roc Roig (eastern Pyrenees, Spain) avalanche path. The avalanches descending this path affect the railway that reaches the Vall de Núria resort and the run-up to the opposite slope. During winter 1996, two important avalanches affecting this path were well documented. These are compared with the results of the vegetation study, consisting of an inventory of flora, the recording of vegetation damages along eight transverse profiles at different altitudes on the path and a dendrochronological sampling campaign. The data obtained contributed to a characterization of the predominant snow accumulation in the starting zone, the 1996 avalanches and the range of frequencies of large avalanches. Also, traces of avalanches that increase the path mapped in the avalanche paths map published by the Institut Cartogràfic de Catalunya in 2000 were identified, improving the initial existing information.

Dynamic and quasistatic trajectories in quasifission reactions and particle emission

We show that the quasifission paths predicted by the one-body dissipation dynamics, in the slowest phase of a binary reaction, follow a quasistatic path, which represents a sequence of states of thermal equilibrium at a fixed value of the deformation coordinate. This establishes the use of the statistical particle-evaporation model in the case of dynamical time-evolving systems. Pre- and post-scission multiplicities of neutrons and total multiplicities of protons and α particles in fission reactions of 63Cu+92Mo, 60Ni+100Mo, 63Cu+100Mo at 10 MeV/u and 20Ne+144,148,154Sm at 20 MeV/u are reproduced reasonably well with statistical model calculations performed along dynamic trajectories whose slow stage (from the most compact configuration up to the point where the neck starts to develop) lasts some 35×10−21 s.

Tailoring the surface density of silicon nanocrystals embedded in SiOx single layers

In this article, we explore the possibility of modifying the silicon nanocrystal areal density in SiOx single layers, while keeping constant their size. For this purpose, a set of SiOx monolayers with controlled thickness between two thick SiO2 layers has been fabricated, for four different compositions (x=1, 1.25, 1.5, or 1.75). The structural properties of the SiO x single layers have been analyzed by transmission electron microscopy (TEM) in planar view geometry. Energy-filtered TEM images revealed an almost constant Si-cluster size and a slight increase in the cluster areal density as the silicon content increases in the layers, while high resolution TEM images show that the size of the Si crystalline precipitates largely decreases as the SiO x stoichiometry approaches that of SiO2. The crystalline fraction was evaluated by combining the results from both techniques, finding a crystallinity reduction from 75% to 40%, for x = 1 and 1.75, respectively. Complementary photoluminescence measurements corroborate the precipitation of Si-nanocrystals with excellent emission properties for layers with the largest amount of excess silicon. The integrated emission from the nanoaggregates perfectly scales with their crystalline state, with no detectable emission for crystalline fractions below 40%. The combination of the structural and luminescence observations suggests that small Si precipitates are submitted to a higher compressive local stress applied by the SiO2 matrix that could inhibit the phase separation and, in turn, promotes the creation of nonradiative paths.

Labor Mobility of the Chinese Graduates from British and Spanish Universities: What Happens to the "Talent Migration"?

The scholarship on migration in Europe heavily focuses on the integration of economically vulnerable migrants. In the age of commercialization of education, however, the European Union attracts a rising number of highly skilled non-EU migrants that take up studies across the continent. Despite economic downturn, the EU universities experience a rapid growth in the number of Chinese students, many of whom settle in Europe upon graduation. Surprisingly, although the number of Chinese students in the EU increases, scholars largely ignore the labor paths that these highly skilled migrants take upon graduating from European universities. This study aims to fill this gap by exploring the variation in the Chinese graduates’ labor incorporation patterns and in their spatial mobility. In this project, I also examine macro-level hypotheses predicting that the EU and host states’ labor market institutions, changes in the EU policies on the highly skilled and the outburst of economic crisis matter for the Chinese highly skilled social and spatial mobility. Seizing on surveys, interviews and on the bodies of literature on stratification and social mobility, economic incorporation, social capital and human capital, I look at the Chinese students that graduated from universities in Great Britain and Spain. These states differ in the university tuition fees, migration policies towards the highly skilled workers and in the period of the Chinese students’ influx, thus providing an economically and socially diverse sample. My research will contribute to the literature on the relations between migrants’ social mobility, class and status background and spatial mobility, at the same time adding a transnational level perspective to the study of highly skilled Asian migration.

Gestió dels residus alimentaris municipals procedents de les activitats comercials del municipi de Montmeló per tal de reduir, reutilitzar i reciclar-los

En el present treball es proposa com lluitar contra el malbaratament alimentari que es genera al llarg de tota la cadena alimentària, sent aquest degut a causa d'una planificació poc adequada. L'objectiu principal és planificar i implantar un sistema de gestió per tal de recuperar l'excedent alimentari que es genera als comerços i les indústries del municipi de Montmeló, elaborant així un protocol per tal de poder redistribuir aquest aliment als sectors de la població en situacions econòmiques més precàries. Com a objectius secundaris, es pretén conscienciar, fomentar i potenciar el treball en xarxa entre els diferents agents implicats, com ara: la ciutadania, les entitats socials (Càritas Parroquial Montmeló), sector privat (establiments alimentaris del municipi, mercat municipal, indústries del sector alimentari) i el sector públic (departament de serveis socials, medi ambient, comerç i brigada municipal). A l'hora de planificar i implantar un sistema de gestió per tal de recuperar l'excedent alimentari, s'ha analitzat i valorat el camí que hi realitza, des d'on es genera fins al beneficiari final. Aquest s'ha gestionat per etapes, en les que s'han identificat els generadors, el tipus i quantitat d'aliment que malbaraten. S'ha proposat un nou sistema de recollida d'informació i les pautes que han de seguir per garantir el bon estat de l'aliment com: una taula de conservació, un protocol de funcionament, un document d'entrega i una fitxa de control de les condicions d'higiene. Per tal d'assolir una bona coordinació entre totes les parts, s'han realitzat reunions conjuntes entre els generadors, serveis socials i Càritas on s'ha acabat signant un acord de col·laboració. Entre les conclusions més rellevants cal destacar que ha servit per establir un precedent d'aprofitament alimentari al municipi de Montmeló, aconseguint alimentar a un gran nombre de famílies amb greus problemes econòmics. A més s'ha arribat a disminuir la quantitat de residus generats, amb el conseqüent estalvi de recursos econòmics i materials on s'ha recuperat un total de 5.760 Kg d'aliments aptes pel consum.

Experimental evaluation of anonymous protocols under the JXTA middleware

JXTA is a peer-to-peer (P2P) middleware whichhas undergone successive iterations through its 10 years of history, slowly incorporating a security baseline that may cater to different applications and services. However, in order to appeal to a broader set of secure scenarios, it would be interesting to take into consideration more advanced capabilities, such as anonymity.There are several proposals on anonymous protocols that can be applied in the context of a P2P network, but it is necessary to be able to choose the right one given each application¿s needs. In this paper, we provide an experimental evaluation of two relevant protocols, each one belonging to a different category of approaches to anonymity: unimessage and split message. Webase our analysis on two scenarios, with stable and non-stable peers, and three metrics: round trip-time (RTT), node processing time and reliability.