A debat : la lectura al segle XXI

La lectura al segle XXI és un tema que per als bibliotecaris inclou molts aspectes apassionants i difícils d'aglutinar en una hora i mitja. En aquesta ocasió, hem volgut parlar no només amb bibliotecaris, sinó també amb altres actors involucrats en aquest sector. El resultat ha estat un debat ric i divers, que ha abastat aspectes com el comportament del lector, l'accés a la informació, els canvis en la lectura, el llibre electrònic o el paper de les institucions i la societat.

A Factor analysis of hidrochemical composition of Llobregat river basin

Hydrogeological research usually includes some statistical studies devised to elucidate mean background state, characterise relationships among different hydrochemical parameters, and show the influence of human activities. These goals are achieved either by means of a statistical approach or by mixing modelsbetween end-members. Compositional data analysis has proved to be effective with the first approach, but there is no commonly accepted solution to the end-member problem in a compositional framework.We present here a possible solution based on factor analysis of compositions illustrated with a case study.We find two factors on the compositional bi-plot fitting two non-centered orthogonal axes to the most representative variables. Each one of these axes defines a subcomposition, grouping those variables thatlay nearest to it. With each subcomposition a log-contrast is computed and rewritten as an equilibrium equation. These two factors can be interpreted as the isometric log-ratio coordinates (ilr) of three hiddencomponents, that can be plotted in a ternary diagram. These hidden components might be interpreted as end-members.We have analysed 14 molarities in 31 sampling stations all along the Llobregat River and its tributaries, with a monthly measure during two years. We have obtained a bi-plot with a 57% of explained totalvariance, from which we have extracted two factors: factor G, reflecting geological background enhanced by potash mining; and factor A, essentially controlled by urban and/or farming wastewater. Graphicalrepresentation of these two factors allows us to identify three extreme samples, corresponding to pristine waters, potash mining influence and urban sewage influence. To confirm this, we have available analysisof diffused and widespread point sources identified in the area: springs, potash mining lixiviates, sewage, and fertilisers. Each one of these sources shows a clear link with one of the extreme samples, exceptfertilisers due to the heterogeneity of their composition.This approach is a useful tool to distinguish end-members, and characterise them, an issue generally difficult to solve. It is worth note that the end-member composition cannot be fully estimated but only characterised through log-ratio relationships among components. Moreover, the influence of each endmember in a given sample must be evaluated in relative terms of the other samples. These limitations areintrinsic to the relative nature of compositional data

Quantifying rock fabrics: a test of autocorrelation of the spatial distribution of cristals

A novel test of spatial independence of the distribution of crystals or phases in rocksbased on compositional statistics is introduced. It improves and generalizes the commonjoins-count statistics known from map analysis in geographic information systems.Assigning phases independently to objects in RD is modelled by a single-trial multinomialrandom function Z(x), where the probabilities of phases add to one and areexplicitly modelled as compositions in the K-part simplex SK. Thus, apparent inconsistenciesof the tests based on the conventional joins{count statistics and their possiblycontradictory interpretations are avoided. In practical applications we assume that theprobabilities of phases do not depend on the location but are identical everywhere inthe domain of de nition. Thus, the model involves the sum of r independent identicalmultinomial distributed 1-trial random variables which is an r-trial multinomialdistributed random variable. The probabilities of the distribution of the r counts canbe considered as a composition in the Q-part simplex SQ. They span the so calledHardy-Weinberg manifold H that is proved to be a K-1-affine subspace of SQ. This isa generalisation of the well-known Hardy-Weinberg law of genetics. If the assignmentof phases accounts for some kind of spatial dependence, then the r-trial probabilitiesdo not remain on H. This suggests the use of the Aitchison distance between observedprobabilities to H to test dependence. Moreover, when there is a spatial uctuation ofthe multinomial probabilities, the observed r-trial probabilities move on H. This shiftcan be used as to check for these uctuations. A practical procedure and an algorithmto perform the test have been developed. Some cases applied to simulated and realdata are presented.Key words: Spatial distribution of crystals in rocks, spatial distribution of phases,joins-count statistics, multinomial distribution, Hardy-Weinberg law, Hardy-Weinbergmanifold, Aitchison geometry

Estudi antropològic de les restes humanes medievals del cementiri parroquial de Sant Pere de Montfullà

El treball que es presenta a continuació és un estudi antropològic de les restes humanes procedents del cementiri parroquial de Sant Pere de Montfullà, al municipi de Bescanó. L’any 2004 es va dur a terme una campanya d’excavació arqueològica al jaciment deSant Pere de Montfullà, dins el marc d’un projecte de recerca dissenyat per l’Institut delPatrimoni Cultural de la Universitat de Girona. En aquesta excavació es varen excavarun total de trenta-una tombes. Les restes humanes recuperades no varen ser estudiadesen aquell moment i van ser dipositades al Laboratori d’Arqueologia de la Universitat deGirona

L'Església de Santa Helena de Rodes: recerca arqueològica i restauració arquitectònica

Descripció de l’estudi arqueològic i la restauració arquitectònica de l’Església de Santa Helena o Santa Creu de Rodes realitzats a principis dels anys 90

Curriculum sequencing for an e-learning system based on learning styles

This work shows the use of adaptation techniques involved in an e-learning system that considers students' learning styles and students' knowledge states. The mentioned e-learning system is built on a multiagent framework designed to examine opportunities to improve the teaching and to motivate the students to learn what they want in a user-friendly and assisted environment

Theoretical study of the second-order vibrational Stark effect

The behaviour of the harmonic infrared frequency of diatomic molecules subjected to moderate static uniform electric fields is analysed. The potential energy expression has been developed as a function of a static uniform electric field, which brings about a formulation describing the frequency versus field strength curve. With the help of the first and second derivatives of the expressions obtained, which correspond to the first- and second-order Stark effects, it was possible to find the maxima of the frequency versus field strength curves for a series of molecules using a Newton-Raphson search. A method is proposed which requires only the calculation of a few energy derivatives at a particular value of the field strength. At the same time, the expression for the dependence of the interatomic distance on the electric field strength is derived and the minimum of this curve is found for the same species. Derived expressions and numerical results are discussed and compared with other studi

Modeling of hybrid systems by piecewise decomposition

Piecewise linear models systems arise as mathematical models of systems in many practical applications, often from linearization for nonlinear systems. There are two main approaches of dealing with these systems according to their continuous or discrete-time aspects. We propose an approach which is based on the state transformation, more particularly the partition of the phase portrait in different regions where each subregion is modeled as a two-dimensional linear time invariant system. Then the Takagi-Sugeno model, which is a combination of local model is calculated. The simulation results show that the Alpha partition is well-suited for dealing with such a system

An LMI approach to H∞ synchronization of second-order neutral master-slave systems

The H∞ synchronization problem of the master and slave structure of a second-order neutral master-slave systems with time-varying delays is presented in this paper. Delay-dependent sufficient conditions for the design of a delayed output-feedback control are given by Lyapunov-Krasovskii method in terms of a linear matrix inequality (LMI). A controller, which guarantees H∞ synchronization of the master and slave structure using some free weighting matrices, is then developed. A numerical example has been given to show the effectiveness of the method

When zero doesn't mean it and other geomathematical mischief

There is almost not a case in exploration geology, where the studied data doesn’tincludes below detection limits and/or zero values, and since most of the geological dataresponds to lognormal distributions, these “zero data” represent a mathematicalchallenge for the interpretation.We need to start by recognizing that there are zero values in geology. For example theamount of quartz in a foyaite (nepheline syenite) is zero, since quartz cannot co-existswith nepheline. Another common essential zero is a North azimuth, however we canalways change that zero for the value of 360°. These are known as “Essential zeros”, butwhat can we do with “Rounded zeros” that are the result of below the detection limit ofthe equipment?Amalgamation, e.g. adding Na2O and K2O, as total alkalis is a solution, but sometimeswe need to differentiate between a sodic and a potassic alteration. Pre-classification intogroups requires a good knowledge of the distribution of the data and the geochemicalcharacteristics of the groups which is not always available. Considering the zero valuesequal to the limit of detection of the used equipment will generate spuriousdistributions, especially in ternary diagrams. Same situation will occur if we replace thezero values by a small amount using non-parametric or parametric techniques(imputation).The method that we are proposing takes into consideration the well known relationshipsbetween some elements. For example, in copper porphyry deposits, there is always agood direct correlation between the copper values and the molybdenum ones, but whilecopper will always be above the limit of detection, many of the molybdenum values willbe “rounded zeros”. So, we will take the lower quartile of the real molybdenum valuesand establish a regression equation with copper, and then we will estimate the“rounded” zero values of molybdenum by their corresponding copper values.The method could be applied to any type of data, provided we establish first theircorrelation dependency.One of the main advantages of this method is that we do not obtain a fixed value for the“rounded zeros”, but one that depends on the value of the other variable.Key words: compositional data analysis, treatment of zeros, essential zeros, roundedzeros, correlation dependency

Robust control of structures subject to uncertain disturbances and actuator dynamics

The objective the present research is try to find some control design strategies, which must be effective and closed to the real operation conditions. As a novel contribution to structural control strategies, the theories of Interval Modal Arithmetic, Backstepping Control and QFT (Qualitative Feedback Theory) will be studied. The steps to follow are to develop first new controllers based on the above theories and then to implement the proposed control strategies to different kind of structures. The report is organized as follows. The Chapter 2 presents the state-of-the-art on structural control systems. The chapter 3 presents the most important open problems found in field of structural control. The exploratory work made by the author, research proposal and working plan are given in the Chapter 4

Eines de detecció de vulnerabilitats en aplicacions web : Control de dades d'entrada

Aquest document proposa, per una banda, la tria d'una eina de codi lliure, com és Skipfish, i per una altra, una eina, una aplicació web, que proporcioni una interfície d'usuari més amigable així com un complement a l'informe que genera Skipfish, afegint explicacions i referències a les vulnerabilitats a més de propostes de solució a aquests.

Disseny i implementació de la base de dades d'un sistema de descàrrega d'aplicacions per a mòbils intel·ligents

L'associació de desenvolupadors d'aplicacions per a mòbils intel·ligents ha encarregat l'implementació d'una base de dades per gestionar les aplicacions, les descàrregues, els usuaris... Aquest projecte realitza una proposta de disseny segons els requeriments demanats i la seva implementació en un sistema de gestió de bases de dades, que en aquesta ocasió és Oracle.

Model d'adequació de l'hàbitat del llop a Catalunya

Des de l’any 2000 es té constància de la presencia del llop a Catalunya. Des de llavors, com a mínim 14 llops diferents han entrat i sortit del territori català, encara que cap d’ells s’ha assentat de manera permanent. L’estudi analitza l’entorn català utilitzant GIS, creant un model d’adequació de l’hàbitat tenint en compte les següents variables: la distància a la carretera més propera, la biomassa disponible a la zona, l’altitud i el tipus i tant per cent de recobriment. El model es basa en la informació obtinguda mitjançant la consulta a experts tant del llop com del territori català, així com en una recerca bibliogràfica sobre l’adequació de l’hàbitat del llop. L’enquesta que es dirigí als experts té en compte els valors que cada variable pot prendre dins l’àrea d’estudi, estableix rangs dels valors de cada variable i pregunta als experts com cada rang pot afectar a l’adequació de l’hàbitat pel llop. Els resultats mostren com bona part de la zona Nord de Catalunya té unes condicions adequades perquè el llop pugui arribar a reproduir-s’hi. Es desenvolupa també una anàlisi dels possibles punts de conflicte humà-llop i una superposició dels espais protegits amb les zones més adequades per l’establiment del llop.

Ampliació i millora d'un sistema avançat de compartició de vehicle

Actualment el cotxe és un dels mitjans de transport més utilitzats,comportant problemes de trànsit i aparcament, contaminació acústica i ambiental i una important despesa econòmica. Ja fa uns anys, i davant d'aquesta nova realitat, va sorgir la idea del carpooling, un sistema de transport privat compartit protagonitzat per particulars i que pot esdevenir una molt bona alternativa de mobilitat sostenible. Tot i això, els projectes de carpooling són actualment poc dinàmics I majoritàriament acotats a portals web. Molt pocs disposen de portals adaptats adispositius mòbils i, encara menys, disposen d’aplicacions natives. Amb tot, avui en dia elsaparells mòbils, ja siguin smartphones o PDAs, obren un ventall de possibilitats encara noexplotat en aquest camp.Per altra banda, compartir un viatge amb algú desconegut i de qui no se’n tenenreferències és quelcom que ens fa sentir insegurs, però això es pot resoldre gràciesal trust i reputation, un sistema basat en les valoracions dels usuaris que ja han viscutl’experiència, i que per tant, ens permet conèixer la reputació i confiança de que disposaun usuari dins el sistema. A tots aquests punts, cal afegir-hi la importància que té avui endia rebre en tot moment una informació clara i actualitzada.Aquest projecte vol exprimir aquestes oportunitats donant una plataforma d’accésusable per aquesta mena de dispositius, per tal de que no hi hagi cap barrera per estarconnectat al sistema en qualsevol lloc i moment. A més a més, aquests terminals donen lapossibilitat de saber la seva localització en temps real, cosa que pot resultar molt útil per agent que comparteix viatges i que s’està movent d’un lloc a un altre.Així doncs, partint de totes aquestes possibilitats de millora, es van idear una sèried’estratègies per a un projecte de carpooling ja existent anomenat e-hitchhiking, dotant aaquest sistema d’una major comunicació, protecció i seguretat per a que l’experiència del’usuari sigui molt més gratificant, on a més, hi ha la possibilitat de rebre informaciótotalment veraç i actualitzada en certs dispositius mòbils.Per tant la motivació principal per dur a terme aquest projecte és, a part de lesesmentades anteriorment, la de dotar un sistema de compartició de vehicle d’un majordinamisme, més realisme, més fiabilitat i fer-lo més sociable. El sistema s’implanta oficialment al setembre del 2011 amb la creació de lacomunitat UdG