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See detailCondition assessment of concrete structures and bridges using vibration monitoring in comparison to changes in their static properties
Bungard, Volker UL

Doctoral thesis (2010)

The thesis deals with the non-destructive condition assessment of civil engineering structures made of reinforced and prestressed concrete as well as bridges and concentrates on a comparison of static and ... [more ▼]

The thesis deals with the non-destructive condition assessment of civil engineering structures made of reinforced and prestressed concrete as well as bridges and concentrates on a comparison of static and dynamic investigation methods. The main questions discuss the sensitivity of changes in static as well as in dynamic properties during the mechanical lifetime of those types of structures under laboratory conditions, the sensitivity of these changes when testing in-situ and the dimension of undesired environmental influences on the dynamic properties. Therefore, a gradually loaded laboratory reinforced concrete beam (cp. chapter 7) and a reinforced as well as a prestressed concrete slab (cp. chapter 8) are investigated for changes in their static and dynamic parameters until reaching their ultimate loads. Furthermore, a successively damaged and stepwise loaded laboratory reinforced concrete slab and a prestressed concrete slab (cp. also chapter 8) are under investigation and also compared in changes in their static as well as in dynamic properties during their lifetimes. By means of static and dynamic tests on a successively damaged and stepwise loaded prestressed concrete bridge (cp. chapter 9) it was possible to investigate the amount of changes in static and dynamic properties for a real in-situ object. A long-term measurement of a composite bridge (cp. chapter 10) demonstrates the environmental influences on the static and dynamic properties of a system which have to be considered when conducting comparative non-destructive condition assessment techniques on real objects. All tests are calculated respectively simulated by the method of the integration of stress (cp. chapter 6) or the finite element method by using the softwares ANSYS and SOFISTIK. Furthermore, measured eigenfrequencies and modeshapes are used to adapt finite element models with the aim to improve the model or to locate and quantify damaged areas. The work is a contribution to the application of non-destructive static and dynamic condition assessment methods on civil engineering structures made of concrete in the sector of civil engineering. [less ▲]

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See detailConception, synthèse et évaluation biologique de dérivés coumariniques en tant qu'agents anticancéreux potentiels
Hemmer, Marc UL

Doctoral thesis (2010)

IK9 was recently reported to be a potent inhibitor of cancer cell invasion and angiogenesis. It markedly reduced in vitro invasion of human HT1080 fibrosarcoma cells through collagen-coated porous ... [more ▼]

IK9 was recently reported to be a potent inhibitor of cancer cell invasion and angiogenesis. It markedly reduced in vitro invasion of human HT1080 fibrosarcoma cells through collagen-coated porous membranes (Boyden chamber assay) and in vivo tumour growth in athymic nude mice. It was furthermore able to decrease angiogenesis ex vivo in a rat aortic ring assay and in vivo in a choroidal neovascularisation mice model. It nevertheless presents some water solubility and stability problems, which should be taken into account for further investigations. In the first part of the project, we synthesized original IK9 derivatives, modulated at the 3- and 6-positions, by introducing functional groups able to improve water solubility and metabolic stability. Their in vitro anti-invasive potency was screened and the generated results highlighted some structure-activity relationships. A second part of the project was devoted to the elucidation of the actually unknown mechanism of action of IK9. Anti-invasive or anti-proliferative effects against endothelial cells, main actors of the angiogenic process, were not emphasised. We showed that IK9 acts likely not as an inhibitor of receptor tyrosine kinases (EGFR, PDGFR and VEGFR). The compound generates a weak decrease of mRNA coding for MMP 2 and 9, and on the other hand a substantial diminution of MMP 2 and 9 secretions by HT1080 fibrosarcoma cells. In conclusion, the consideration of anti-invasive properties together with the worked out solubility and stability profiles highlights several series, notably 6-hydroxycoumarins, 6-hydroxymethylcoumarins and coumarin-3-sulfonamides, whose interest as potential successors to IK9 is undeniable. [less ▲]

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See detailMethods for Extracting Meta-Information from bibliographic databases
Biryukov, Maria UL

Doctoral thesis (2010)

Due to intensive growth of the electronically available publications, bibliographic databases have become widespread. They cover a large variety of knowledge fields and provide a fast access to the wide ... [more ▼]

Due to intensive growth of the electronically available publications, bibliographic databases have become widespread. They cover a large variety of knowledge fields and provide a fast access to the wide variety of data. At the same time they contain a wealth of hidden knowledge that requires steps of extra processing in order to infer it. In this work we focus on extraction of such meta knowledge from the research bibliographic databases by looking at them from sociolinguistic, text mining and bibliometric perspectives. We choose the Digital Library and Bibliographic Database as a testbed for our experiments. In the framework of the sociolinguistic analysis we build a statistical system for the language identification of personal names. We show also that extension of a purely statistical model with the co-authors network boosts the system's performance. In the text mining scenario, we perform a number of experiments that focus on topic identification and ranking. While our topic detection approach remains generic and can be used for any kind of textual data, the topic ranking metrics are built upon the information provided by the bibliographic databases. The goal of our bibliometric study is to create a researcher's profile on DBLP and analyze some of the research communities defined by the different conferences, in terms of the publication activity, interdisciplinarity of research, collaboration trends and population stability. We also aim at exploring to what extent these aspects correlate with the conference rank. Each of the above topics constitutes a method of meta information extraction from bibliographic databases and other similarly structured data sources. [less ▲]

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See detailGeometry and Stochastic Calculus on Wasserstein spaces
Selinger, Christian UL

Doctoral thesis (2010)

P ([0, 1])) with respect to the Skorohod topology. In the last chapter we restrict ourselves to the space of histograms on the unit interval. We calculate the Wasserstein distances numerically and obtain ... [more ▼]

P ([0, 1])) with respect to the Skorohod topology. In the last chapter we restrict ourselves to the space of histograms on the unit interval. We calculate the Wasserstein distances numerically and obtain a Riemannian metric on the simplex. We investigate explosion behaviour of the respective diffusion processes in dimension 1 and 2. [less ▲]

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See detailPeer interactions in the primary classroom
Meyer, Anne UL

Doctoral thesis (2010)

The present research focuses on peer interactions engaged with the accomplishment of learning activities in the primary classroom. It is driven by the interest and need to understand learning and social ... [more ▼]

The present research focuses on peer interactions engaged with the accomplishment of learning activities in the primary classroom. It is driven by the interest and need to understand learning and social interaction taking place in peer group-s, and how the participants orient to the sequential organization of social interaction. The research draws on audio and video data stemming from the primary classroom in Luxembourg, and aims at 1) describing and analyzing the interactional organization of learning activities, 2) describing and analyzing the resources and methods, i.e. expert-novice-practices mobilized by young learners when orienting to the accomplishment of a learning activity, and 3) describing the opportunities for participation and for learning that may take place when learners orient to the accomplishment of a learning activity in peer interaction. Peer interaction is depicted as one form of a community of practice within which learning is situated and observable as learners in and through the deployment of expert-novice-practices orient to, and adapt to micro-shifts in the participation framework when accomplishing a learning activity. Results point to the fact that not only are expert-novice-practices deployed when young learners work in interaction, but these practices are also found to be inextricably linked to the constitution of expert-novice identities - this again has implications for how the learners orient to the accomplishment of a learning activity. [less ▲]

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See detailLocal Languaging: Literacy Products and Practices in Gambian Society
Juffermans, Kasper UL

Doctoral thesis (2010)

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See detailEvaluation of GNSS as a Tool for Monitoring Tropospheric Water Vapour
Ahmed, Furqan UL

Bachelor/master dissertation (2010)

Global Navigation Satellite Systems have the potential to become a significant tool in climate research ... [more ▼]

Global Navigation Satellite Systems have the potential to become a significant tool in climate research due to the fact that GNSS data can be processed in order to estimate the propagation delay experienced by the signal in atmosphere. If the ground pressure and temperature is known, the signal propagation path delay can be related to the amount of water vapour in the atmosphere. This thesis project focuses on the evaluation of GNSS as a tool for atmospheric water vapour estimation. In the first part of the project, various GNSS data processing software packages were compared by processing the same set of data and performing a statistical comparison of the estimates of zenith total delay obtained by each package. The software packages compared are GIPSY‐OASIS, Bernese GNSS Processing Software, GAMIT and magicGNSS. Also different strategies and methods, such as double‐differencing and precise point positioning,  are  investigated.  The  output from the  packages  is  validated  using  delay measurements obtained from ECMWF and RCA numerical models. It was observed that the output from climate models agrees with that from the software packages and the output from various software packages have a similarity between each other within 3 millimeters. In the second part of the project, simulations of new GNSS are carried out using in‐house software developed at Chalmers and SP Technical Research Institute of Sweden in order to investigate new methods and possible future improvements. The effect of local errors on atmospheric delay estimates from GPS, GLONASS and Galileo was studied through simulations. A hypothetical system formed by combination of the constellations of GPS, GLONASS and Galileo was also simulated and it was found to be least susceptible to local errors. Simulations were performed by varying some Keplerian orbital elements for Galileo system and it was observed that an orbit inclination between 60 degree and 65 degree would have been optimum for Galileo system. [less ▲]

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See detailPain modulation induced by Heterotopic Noxious Counter-Stimulation (HNCS) : psychophysiological assessment of adequate stimulation paradigms and sex-related effects
Streff, Anouk UL

Doctoral thesis (2010)

This work comprises three studies whose main concern was to find a valid tonic pain model able to trigger a genuine diffuse noxious pain inhibition. All studies were performed in healthy, drug-free ... [more ▼]

This work comprises three studies whose main concern was to find a valid tonic pain model able to trigger a genuine diffuse noxious pain inhibition. All studies were performed in healthy, drug-free volunteers and whereas the first two are validation studies, the third is an application study of the previous two. The aim of the first study was to characterize the cold pressor (CPT) and hot water immersion test (HIT) from a physiological and a psychophysical point of view. A second issue was to clarify the origin of potential autonomic responses during both tests; are they related to baroreflex activity or rather a consequence of the pain experience per se? The study was performed in 30 volunteers aged 19-57 (median 24) years, and consisted of a single session including one CPT (4 ± 0.2°C) and one HIT (47 ± 0.5°C) with a cut-off-point of 5 minutes. Participants were randomly assigned to sequence order (the sequence of both trials was alternated) and groups were paralleled with respect to gender. Cardiovascular, respiratory and electrodermal activities as well as subjective pain intensity were continuously monitored. Pain detection and tolerance thresholds as well as pain unpleasantness and nervous tension were assessed additionally. Both tests were found to be comparable with respect to intensity of subjective pain and time course, but a significantly higher blood pressure increase during CPT could be observed, compared to the HIT. In conclusion, the HIT appears to be less confounded with baroreflex activity and hence seems to be a more adequate tonic pain model. The second study tested the internal validity of inter-digital web pinching (IWP) with regard to its potential as DNIC-trigger. 24 gender-matched participants, aged 21-54 (median 25) years, volunteered for the controlled study. The protocol included the assessment of thermal and mechanical perceptual wind-up (WU) before and after a HIT (47.5 °C) or an IWP (15 N) of 2 minutes duration each. WU pain was induced by 10 repetitive (1 Hz) contact heat (max. 49°C; 5 5 mm thermode) or 10 ballistic impact stimuli (0.5 g at 9m/s) on the phalanges of the non-dominant hand. Cardiovascular and corrugator muscle activity as well as pain experience were permanently monitored. Both heterotopic noxious counter-stimulation (HNCS) types produced a similar pain experience, but a more pronounced cardiovascular activity was observed for the HIT. Painful water immersion is though accompanied by a stronger baroreceptor activity. WU pain was significantly reduced for both pain modalities, although the inhibition was somewhat stronger for the HIT than the IWP. The IWP, being practically uncontaminated by baroreflex sensitivity (BRS), proved its validity as DNIC-trigger. The third study investigated temporal characteristics of electrically elicited pain and nocifensive RIII-reflex activity in a gender-balanced sample of 28 volunteers aged 21-38 (median 27) years, using IWP as HNCS, a tonic pain model previously validated to be BRS-unrelated. Sex-related differences in the post HNCS time courses of pain perception were identified with women demonstrating a more rapid return to baseline compared to men. Interestingly, an opposite pattern was observed regarding nociceptive reflex activity with a steeper return rate of electromyographic responses in males, whereas those of women remained attenuated over the entire observation period. These findings may reflect a stronger defensive response to pain in women. [less ▲]

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See detailState Aid, Subsidy and Tax Incentives under EU and WTO Law
Micheau, Claire UL

Doctoral thesis (2010)

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See detailRobust Dominating Set based Virtual Backbones for Wireless Ad hoc Networks
Schleich, Julien UL

Doctoral thesis (2010)

Ad hoc networks are infrastructure-less spontaneous networks generally composed of wireless and mobile devices. From a practical point of view, ad hoc technologies offer solutions when infrastructure ... [more ▼]

Ad hoc networks are infrastructure-less spontaneous networks generally composed of wireless and mobile devices. From a practical point of view, ad hoc technologies offer solutions when infrastructure-based network are too costly, damaged or not suitable. Despite a wide panel of scenarios and the huge number of ad hoc capable devices currently in use, this technology is not widely used because of technical considerations mainly related to the lack of a global coordinator. In this thesis, we propose two different approaches to create virtual backbones in order to organize ad hoc networks. In a first time, we propose a centralized algorithm based on DC programming and DCA to solve the Min m-Vertex Dominating Set Problem and in a second part, we develop distributed and asynchronous algorithms, relying on 2-hop knowledge only, to build k-Vertex Connected m-Vertex Dominating Set-based Virtual Backbones. A global overview of the domain is provided through an extensive state-of-the-art and a hierarchical classification. The efficiency of both approaches is demonstrated with a wide panels of simulations, from randomly generated graphs to more realistic scenarios. [less ▲]

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See detailSignaling legitimacy for small and medium-size enterprises in transition environments - The case of the Bulgarian IT sector
Ivanova, Olga UL

Doctoral thesis (2010)

The process of institutional transition from one coordination mechanism to another one is an important period in the evolution of any society. Transitions are associated with fundamental political, legal ... [more ▼]

The process of institutional transition from one coordination mechanism to another one is an important period in the evolution of any society. Transitions are associated with fundamental political, legal, economic and social changes (Danis et al. 2010) affecting all aspects of life (Peng 2003). The transition from planned to open-market economy that has taken place in Central and Eastern Europe (CEE), East Asia, and the newly independent states of the former Soviet Union represents an institutional transition. An environment that goes through transition is characterized by high level of vulnerability and uncertainty which impacts all actors evolving in it, including the organizations (Peng 2003). The dynamic relationship environment-organization is reflected in the concept of legitimacy. Legitimacy is a pertinent concept to study the transition stage since it exists on the borderline between the organization and its environment. In transition environments, the processes of deinstitutionalization of the old structures and the reinstitutionalization of the new ones coexist. This leads to a lack of institutional framework to guide behavior of actors or a situation called institutional vacuum. Since institutions regulate economic exchanges (North 1990), the lack of them leads to elevated costs for all actors due to the proliferation of opportunistic behavior (Meyer 2001). In such environments, demonstrating legitimacy becomes crucial for the survival of structures and actors. Legitimation is sought by new elites (Raychev and Stoichev 2008), the government (Peng 2000a), the new laws, decrees and regulations (Stark 1992), and the private organizations (Peng 2000a). The success of the transition directly depends on the strategies of organizations evolving in such environments (Peng 2000). Small and medium-size enterprises (SMEs) play an important role as catalysts of the process of change (McIntyre 2003: 1) since they are expected to spur economic growth and employment (Peng 2000a), and maintain social peace (McIntyre 2003: 1). Despite their central role in transition environments, little is known about the challenges SMEs face and the actions that can be undertaken in order to overcome them (Danis, Chaburu and Lyles 2010). One of the main challenges of SMEs in transition environments is to demonstrate that they are legitimate players implying that they comply with the expectations of relevant stakeholders’ groups. The main objective of this study is to shed some light on how SMEs in transition environments gain organizational legitimacy necessary for obtaining stakeholders’ support. The interest of the study lies in the fact that if organizational legitimacy is problematic for all organizations due to changing norms, beliefs, and stakeholders’ expectations over time (Ashforth and Gibbs 1990), it is even more problematic for small organizations in transition environments since the norms, beliefs and expectations are not clearly defined. In order to address the legitimacy needs of small organizations in transition environments, I propose a signaling theory of legitimacy, which postulates that the legitimacy-claiming entities can rely on valid signals in order to demonstrate (communicate) their adherence to the requirements of the evaluating audiences. In general, the signaling theory of legitimacy should hold for any organization facing a liability - the discount the evaluating audiences place on it in comparison to its potential competitors. Organizations in transition environments face liability of origin (Bartlett and Ghoshal 2000) – a discount that the evaluating audiences (both domestic and foreign) may place on them based on their context of origin. For small organizations , the challenges resulting from liability of origin are even bigger because of their size, they are more prone to import instability from the environment. The higher level of vulnerability of small firms encourages them to engage in opportunistic behavior. Hence, demonstrating their legitimacy is a key issue for SMEs operating in transition environments. Organizational legitimacy becomes especially important when organizations engage in long-term arrangements since this requires an assessment of the organization not only in terms of its products/services but also in terms of its ongoing access to resources and capabilities as well as its reliability as a partner. In order to address the legitimacy needs of small firms evolving in transition environments and trying to obtain long-term partnerships, a new legitimacy typology is proposed. It is comprised of two types – functional and relational legitimacy. Functional legitimacy represents the adherence to the evaluating audiences’ requirements regarding relevant resources and capabilities. Relational legitimacy is the conformity with the evaluating audiences’ expectations regarding the reliability of an organization as a partner. Hence, this study addresses two research questions: 1. What are the dimensions (and valid signals) of functional and relational legitimacy (for small organizations in transition environment)? 2. Does using signals of specific types of legitimacy (depending on the liability faced) enhance organizational legitimacy? This doctoral research examines the legitimacy challenges of SMEs in transition environments trying to obtain long-term arrangements. In the first part of the study, the two types of legitimacy - functional and relational legitimacy - are constructed. Similar to organizational legitimacy (Deephouse and Carter 2005), functional and relational legitimacy are also multidimensional constructs comprised of different facets. In the second part, I examine whether the signals of functional and relational legitimacy help SMEs in transition environment gain organizational legitimacy. The research model is tested on data collected from the information technology (IT) sector in Bulgaria. Based on the data analysis and results, this research has several theoretical and methodological contributions. The results also have practical implications for the managers of small organizations in transition environments as well as the public policy agents. The theoretical contributions are associated mainly with the signaling theory of legitimacy. It looks at how organizations can overcome certain liabilities by communicating their adherence to the expectations of relevant stakeholders’ groups. Organizations can demonstrate their conformity to the evaluating audiences’ requirements by using valid signals – organizational characteristics that can be observed, are costly to imitate and are based on shared meaning between the sending and the receiving party. In addition, the study contributes to the literature on transition environments by looking at the particular case of SMEs and their attempt to demonstrate that they are legitimate players when trying to engage in long-term arrangements. The methodological contribution lies in the way the two types of legitimacy (functional and relational) are measured via formative measurement constructs (Diamantopoulos and Winklhofer 2001; Jarvis et al. 2003) under the partial least squares (PLS) technique. Formative constructs are associated with causality that goes from the manifest (directly observable) variable to the latent construct or in other words, the manifest variables cause/build the latent construct (Diamantopoulos 1999). This made possible to match the legitimacy claims of organizations from once side based on the functional and relational signals and the legitimacy granted by relevant stakeholders’ groups, on the other side. In addition, the research contributes to the growing number of studies in strategic management that use PLS as a structural equation modeling technique (Birkinshaw et al. 1995; Cool et al. 1989; Fornell et al. 1990; Johansson and Yip 1994; Tsang 2002). The practical implications of this research shed some light on which signals (organizational characteristics) are important for managers of small organizations in transition environments. Signals are costly and since all organizations (and especially small firms) have limited resources, managers have to know which signals to invest in. It is important to note that many managers disregard the relational aspect of their legitimacy claims which (based on the results of the study) are more important in the communication process between the legitimacy-claiming and legitimacy-granting entities. Overall, this study represents a fertile area for future research. Researchers can test the signaling theory of legitimacy in other contexts – i.e., other transition environments (Eastern Europe vs. China), as well as compare the signals used by organizations in transition environments and developed economies. Researchers can also test the signaling theory of legitimacy on organizations facing different liabilities (i.e. liability of market newness) and try to extend the existing legitimacy typologies. In addition, future studies can focus on issues of meaning construction (based on signals) in the communication process between organizations. [less ▲]

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See detailDie nationalsozialistische Kunst- und Kulturpolitik im Grossherzogtum Luxembourg 1934-1944
Lorent, Catherine UL

Doctoral thesis (2010)

This study is about the art and history in Luxembourg from 1934-1944. This decade where Luxembourg was occupied by Nazi Germany from 1940 to 1944, has not yet been represented focusing on the visuals arts ... [more ▼]

This study is about the art and history in Luxembourg from 1934-1944. This decade where Luxembourg was occupied by Nazi Germany from 1940 to 1944, has not yet been represented focusing on the visuals arts facing the national socialist oppressions and propaganda due to the tabooization of these years. After an incipient view about the development of the arts in Luxembourg during the 1930’s, the influence of the german propaganda through the Gesellschaft für Deutsche Literatur und Kunst and about the reception of the Nazi art politics in the Luxembourgish press, the national-socilalist politics of art culture and the effects on the Luxembourgish art scene are presented. during the occupation by the Hitler State. The aim is to gain a particular view about the germanisation of Luxembourgish art, artists and cultural institutions while Luxembourg had become a part of Gau Moselland. The themes pictured by the artists are analyzed in a way to show the propagandistic value of the caracteristics of a « regional » art for national-socialist art politics. Two Major questions are examined : How the artists dealed with the political and social upheavals in their country and : Were collaboration or resistance the only options to face the cultural oppressions of the Nazis ? [less ▲]

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See detailCarbon Lock-in in der Automobilindustrie?
Maier, Urs UL

Doctoral thesis (2010)

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See detailEfficient Data Dissemination Techniques For Multi-Hop Wireless Networks Applied to Vehicular Communications
Frank, Raphaël UL

Doctoral thesis (2010)

Multi-Hop Wireless Networks (MHWN) are composed of devices called nodes, which communicate in an ad hoc fashion. Such networks allow the relaying of transmissions over multiple wireless hops to provide an ... [more ▼]

Multi-Hop Wireless Networks (MHWN) are composed of devices called nodes, which communicate in an ad hoc fashion. Such networks allow the relaying of transmissions over multiple wireless hops to provide an extended service area. There are two main classes of MHWN. The first includes all networks that have a static network topology, e.g. Wireless Mesh Networks and Wireless Sensor Networks. The second specifies networks with a dynamic or mobile topology, e.g. Vehicular Networks. For both types, collaborative applications are of great importance. In such a scenario, information needs to be made available to multiple, or sometimes all nodes in the network. The trivial method, pure network flooding, is to retransmit the information at every hop exactly once. In previous studies it has been shown that such an approach considerably lowers the overall performance of the network by saturating the shared communication channel. In this thesis, we present two different approaches that perform efficient data dissemination among collaborative nodes in MHWNs. The primarily objective is to reduce the number of redundant retransmissions by selecting only a subset of nodes to be responsible for relaying the information without compromising global delivery. We propose one approach for each of the two classes using different methodologies. For static network topologies, we present a novel heuristic based on the Minimum Connected Dominating Set problem. This approach allows the election of a near-optimal set of relays that are able to reach every other node in the network, thus minimizing the number of retransmissions. We theoretically and experimentally validate our approach and compare it to other state-of-the-art dissemination techniques. For dynamic network topologies, we focus primarily on Vehicular Networks. We present a new routing protocol that makes use of an efficient dissemination technique to find robust communication paths between two vehicles. Strategic vehicles are elected as relays based on their position and on information about the local neighborhood. The protocol is evaluated using a novel simulation framework that takes into account specific characteristics of vehicular networks in urban environments, e.g. mobility of the vehicles and signal propagation. The performance evaluation shows that our protocol introduces only a low control overhead and provides robust communication paths that achieve high delivery ratios. [less ▲]

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See detailAnalysis and modelling of the noise generation during vibratory pile driving and determination of the optimization potential
Hanus, Vincent UL

Doctoral thesis (2010)

Impact driving, pressing and vibrodriving are the three main methods to drive sheet piles. The sound level generated during vibrodriving varies almost between the very high level of an impact driving and ... [more ▼]

Impact driving, pressing and vibrodriving are the three main methods to drive sheet piles. The sound level generated during vibrodriving varies almost between the very high level of an impact driving and the lowest sound level of a pressing. In the first part of this doctoral thesis, sound measurements feasibility is thoroughly studied. Particular attention is paid to the measurement conditions on construction sites and to the measurement methods (sound power level, beamforming and thermography). These methods are outlined and the provided results are compared. In addition, the different causes of noise are analysed and the influence of various parameters is quantified. In the second part, the acceleration measurements of the full-scale experiments are used to calibrate a Finite Element model. A parametric study analyses how the most important mechanical parameters influence the noise level. This research has shown that a decrease of the noise generation on construction sites can be obtained by two ways: by recommendations for installation of sheet piles at the construction site, and by requirement of constructive measures that significantly reduce the noise level. [less ▲]

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See detailUnderstanding and leveraging the social web for information retrieval
Noll, Michael UL

Doctoral thesis (2010)

Detailed reference viewed: 39 (1 UL)
See detailTree-Based computation in probalistic models
Ignac, Tomasz UL

Doctoral thesis (2010)

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See detailJanus kinases as targets for small molecule inhibitors
Kaczor, Jakub UL

Doctoral thesis (2010)

Many cytokines transduce signals by employing receptor/Janus kinase (Jak) complexes that, once activated, promote phosphorylation of several signaling proteins such as STAT transcription factors. The Jak ... [more ▼]

Many cytokines transduce signals by employing receptor/Janus kinase (Jak) complexes that, once activated, promote phosphorylation of several signaling proteins such as STAT transcription factors. The Jak/STAT pathway is normally tightly modulated by regulatory mechanisms preventing its over-activation. However, a number of genetic alterations in Jak kinase genes have been found in myeloproliferative neoplasms and leukemia that render the Jaks hyperactive and cytokine-independent. In the present thesis pharmacologic and genetic approaches were applied to study aspects of both the cytokine-dependent and -independent activation of the Jak/STAT pathway. We applied a chemical genetics approach to Janus kinases and generate analogue-sensitive Jak1 and Jak2 mutants. With these tools we could for the first time specifically inhibit either Jak1 or Jak2 and investigate their relative contributions in IFN signaling. Single inhibition of either Jak by an inhibitor analogue showed differential effects on IFN-mediated STAT1 phosphorylation, Jak2 inhibition having a stronger suppressive effect. Furthermore, we identified STAT1 and IRF1 as genes, whose increased expression upon IFN stimulation strongly depends on active Jak2 but not on Jak1. Most of the IFN-regulated genes, however, depend on both Jak1 and Jak2 activity. Exploiting this quick and reversible pharmacological inhibition of analogue-sensitive kinases we address the temporal requirement of Jak activity and the importance of different phases of the IFN response. Moreover, we further characterized constitutively active Jak2 mutants and show that SOCS proteins seem to be directly involved in their proteasome-mediated degradation. There is an increasing interest in developing small molecule inhibitors targeting Jaks and Jak mutants. We show that Erlotinib, an inhibitor targeting EGFR which is already used in the clinic to treat lung and pancreatic cancer, can have a beneficial additional effect if combined with a Jak-specific inhibitor on cell growth suppression and apoptosis of Jak2-V617F- or Jak3-A572V-positive leukemic cells. Erlotinib, in contrast to Jak inhibitors targeting Jaks directly affects the eIF2/ATF4 pathway in leukemic cells. This is of general interest since Erlotinib treatment in conjunction with other kinase inhibitors could be an interesting approach also in other kinase-dependant leukemias (e.g. BCR-ABL-positive CML). [less ▲]

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See detailEssays in international finance
Vermeulen, Robert John Gerard UL

Doctoral thesis (2010)

Detailed reference viewed: 63 (2 UL)
See detailL'investisseur face aux réseaux de distribution d' OPCVM
Borissova, Miroslava Andonova UL

Doctoral thesis (2010)

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See detailCompatibilités et incompatibilités liants cimentaires / superplastifiants
Nicolas, Edwige UL

Doctoral thesis (2010)

Currently required concrete strength imposes a lower water/cement ratio and use of superplasticizer to make easier the fresh material implementation. Polycarboxylate type products are very effective in ... [more ▼]

Currently required concrete strength imposes a lower water/cement ratio and use of superplasticizer to make easier the fresh material implementation. Polycarboxylate type products are very effective in the short term but can lead to a fast loss of workability in case of binder/superplasticizer incompatibility. The object of this work is the identification of cementitous phases involved in these rheological variations. Initially, flow of various superplasticized pastes is evaluated by a rheometer fitted with a ball measuring system. Compatible combinations flow like a Bingham’s fluid. An incompatibility results in an increase of yield stress and plastic viscosity or rheological properties evolution into Herschel-Bulkley’s fluid. Then, cement/superplasticizer combinations are characterized by rheological tests. Stiffening assessment of pastes and chemical characterisation of hydrated cements show that consistency is associated with amount and microstructure of formed ettringite. These parameters depend on initially present aluminate phase and calcium sulphates. Finally, study of synthetic cementitous systems states that calcium sulphates solubility, in presence of superplasticizer, is increased probably because Ca2+ ions complexation by polycarboxylates. As for the orthorhombic variety of aluminate phase, more reactive than cubic variety, it leads to a large amount of needle-shaped ettringite. [less ▲]

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See detailNew approaches to the cryptanalysis of symmetric primitives
Khovratovich, Dmitry UL

Doctoral thesis (2010)

Detailed reference viewed: 70 (5 UL)
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See detailMechanische und thermische Untersuchungen zur Entwicklung eines Wärmedämmsteines aus Leichtbeton
Leufgens, Nadine UL

Doctoral thesis (2010)

The current discussion about the necessity of sustainable reduction of primary energy for heating of housing structures and of CO2 – emissions led the University of Luxembourg to issue a project to ... [more ▼]

The current discussion about the necessity of sustainable reduction of primary energy for heating of housing structures and of CO2 – emissions led the University of Luxembourg to issue a project to develop hybrid light-weight concrete blocks with high heat-insulating properties. Therefore, the demand for wall constructions limiting the heat flow through the outer wall was steadily growing. Because of the progressing standard of national and European Energy Saving Regulations for housing structures and office buildings in the past years, most of the producers of bricks and concrete masonry blocks were forced to develop new, innovative wall materials and constructions. For assessing the real actual state of the art of masonry blocks, 15 different bricks and blocks were taken from European free market as samples. It was shown, that especially for highly-heat insulating masonry lightweight concrete blocks (e.g. Vbl SW 2) with dry densities below 800 kg/m3 an optimization potential still exists. A relevant aspect for a critical estimation of a wall construction is the knowledge of mechanical and thermal lightweight aggregate concrete (LAC) parameters. The present work describes investigations for determining design limit values of the thermal and mechanical properties of LAC. Based on this, a mathematical approach to describe the strength, the thermal conductivity and for e.g. the stress-strain-relationship linked to the dry density in a range between 500 and 2000 kg/m3 was derived. For studying the material behavior of LAC, specimens were produced in laboratory tests as well as in the production line by fabricating solid lightweight concrete blocks without inner air holes. Due to the unsatisfying results of the market study, further investigations had to be done to determine the influence of size and slenderness effects on the strength of solid specimen and masonry blocks with inner air holes made of LAC. Additionally, combined influencing factors were studied on block sections cut out of hollow and solid masonry blocks. In the following, the experimental results were verified by simulations with the Finite-Element-Method using the commercial software ANSYS© for modeling different LAC-specimen geometries and the influence of the kind of load applications by a contact zone between steel plates and specimen. Subsequently, the results of these investigations and the achieved knowledge of the influencing factors on the load carrying capacity of the block structures lead to an analytical model approach for design purpose of masonry blocks based on the elasticity theory. This model allows quantitative predictions of the load bearing strength of hollow and solid masonry blocks with inner air holes arranged in a grid system. The analytical model is verified by comparison of experimental results of different block geometries. Finally, the knowledge of the load carrying behavior of different LAC specimen geometries achieved by various experimental and numerical results contribute to the construction of new prototypes of heat insulating masonry blocks made of LAC. Based on the results of the market study and numerical parameter studies, it is revealed that it is suggestive to separate the load bearing from the thermal function of the block by developing 3-layered Sandwich and composite blocks made of an insulating and load bearing part. [less ▲]

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See detailHydrological effects on gravity at the station of Walferdange, Luxembourg
Lampitelli, Carmine UL

Doctoral thesis (2010)

In this study, we look at the physical relationship between water storage variations driven by local precipitation events and local gravity changes at Walferdange, in the Grand Duchy of Luxembourg. A ... [more ▼]

In this study, we look at the physical relationship between water storage variations driven by local precipitation events and local gravity changes at Walferdange, in the Grand Duchy of Luxembourg. A synthesis of the different approaches that can be found in recent literature is proposed. Then, a new and simple scheme is provided to remove the effects of precipitation events in the gravity observations, For the gravity observations, we use the data collected by the superconducting gravimeter CT040 (SG) located in the Walferdange Underground Laboratory for Geodynamics (WULG), which provides high resolution relative gravity measurements from December 2003. In addition, a statistical analysis is presented to determine the correlation between the gravity signal variations registered by the SG and the water level of the nearby flowing Alzette River. The idea is that the gravity variation due to the precipitation should appear before the change in river level. Contrarily to the simple precipitation data, the gravity observation should also contain information on the degree of soil saturation, which depends on processes having a seasonal variability, as evapotranspiration, and on hydrogeological parameters like hydraulic conductivity. Understanding the relationship and temporal dependence between the observed precipitation and the gravity changes might improve the capacity to predict extreme events like flooding. [less ▲]

Detailed reference viewed: 136 (11 UL)
See detailLe transfert des sûretés
Westendorf, Hannes UL

Doctoral thesis (2010)

Detailed reference viewed: 85 (1 UL)
See detailLaw-aware access control for international financial environments
Stieghahn, Michael UL

Doctoral thesis (2010)

Detailed reference viewed: 84 (1 UL)
See detailIntroduction à la théorie des espaces symétriques
Korvers, Stéphane UL

Bachelor/master dissertation (2010)

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See detailLes télomères: télomères et télomérase chez l'homme
Bernard, Nicolas UL

Bachelor/master dissertation (2010)

Les télomères sont les extrémités des chromosomes, nécessaires pour la stabilité de ceux-ci. Leur longueur est cruciale pour la cellule : trops courts, ils déclenchent son entrée en sénescence, voire sa ... [more ▼]

Les télomères sont les extrémités des chromosomes, nécessaires pour la stabilité de ceux-ci. Leur longueur est cruciale pour la cellule : trops courts, ils déclenchent son entrée en sénescence, voire sa mort. Ce vieillissement des cellules est corrélé avec celui de l’organisme qu’elles composent. Un enzyme, la télomérase, permet d’allonger les télomères ou d’empêcher leur raccourcissement. Chez l’homme, cet enzyme n’est actif que dans certaines cellules, qui doivent continuer à se multiplier au long de la vie. Toutefois, la télomérase est également impliquée dans les cancers : pour continuer à croître, ceux-ci doivent empêcher le raccourcissement des télomères, qui intervient normalement à chaque division cellulaire. Si l’activation de la télomérase est constatée dans la majorité des cancers, d’autres mécanismes existent aussi. Dans ce document, nous dressons un état des lieux succinct des connaissances sur les télomères et la télomérase, et sur leurs liens avec le vieillissement et le cancer, avant d’évoquer les espoirs thérapeutiques suscités par la compréhension de ces mécanismes. [less ▲]

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See detailAdaptive high-gain extended kalman filter and applications
Boizot, Nicolas UL

Doctoral thesis (2010)

The work concerns the ``observability problem” --- the reconstruction of a dynamic process's full state from a partially measured state--- for nonlinear dynamic systems. The Extended Kalman Filter (EKF ... [more ▼]

The work concerns the ``observability problem” --- the reconstruction of a dynamic process's full state from a partially measured state--- for nonlinear dynamic systems. The Extended Kalman Filter (EKF) is a widely-used observer for such nonlinear systems. However it suffers from a lack of theoretical justifications and displays poor performance when the estimated state is far from the real state, e.g. due to large perturbations, a poor initial state estimate, etc… We propose a solution to these problems, the Adaptive High-Gain (EKF). Observability theory reveals the existence of special representations characterizing nonlinear systems having the observability property. Such representations are called observability normal forms. A EKF variant based on the usage of a single scalar parameter, combined with an observability normal form, leads to an observer, the High-Gain EKF, with improved performance when the estimated state is far from the actual state. Its convergence for any initial estimated state is proven. Unfortunately, and contrary to the EKF, this latter observer is very sensitive to measurement noise. Our observer combines the behaviors of the EKF and of the high-gain EKF. Our aim is to take advantage of both efficiency with respect to noise smoothing and reactivity to large estimation errors. In order to achieve this, the parameter that is the heart of the high-gain technique is made adaptive. \textit{Voila}, the Adaptive High-Gain EKF. A measure of the quality of the estimation is needed in order to drive the adaptation. We propose such an index and prove the relevance of its usage. We provide a proof of convergence for the resulting observer, and the final algorithm is demonstrated via both simulations and a real-time implementation. Finally, extensions to multiple output and to continuous-discrete systems are given. [less ▲]

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See detailTolérance aux fautes et reconfiguration dynamique pour les applications distribuées à grande échelle
Besseron, Xavier UL

Doctoral thesis (2010)

This work deals with high performance computing on large scale platforms like computing grids. Computing grids are characterized by (1) frequent changes in execution context and, especially, by (2) a high ... [more ▼]

This work deals with high performance computing on large scale platforms like computing grids. Computing grids are characterized by (1) frequent changes in execution context and, especially, by (2) a high failure probability caused by the large number of components. Running an application efficiently in such an environment requires to consider these parameters. Our research work is based on the abstract representation of the application as a data flow graph from the parallel and distributed programming model Athapascan/Kaapi. This abstract representation is used to provide solutions for (1) dynamic reconfiguration and (2) fault tolerance issues. - First, we propose a dynamic reconfiguration mechanism that manages, transparently for the reconfiguration programmer, concurrent operations on the application state and mutual consistency of states for distributed reconfiguration. - Secondly, we present an original fault tolerance protocol that allows partial rollback of the application in case of failure. For this purpose, the set of strictly required computation tasks to recover is computed. These contributions are evaluated through the Kaapi and X-Kaapi software on the Grid'5000 computing platform. [less ▲]

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See detailPRISMA: A Software Product Line-oriented Process for the Requirements Engineering of Flexible Transaction Models
Gallina, Barbara UL

Doctoral thesis (2010)

Engineering the requirements of the right transaction model (right with respect to the business goals of the application to be supported) is a hard task since it involves the critical choice of the right ... [more ▼]

Engineering the requirements of the right transaction model (right with respect to the business goals of the application to be supported) is a hard task since it involves the critical choice of the right degree of ACIDity, that is the right selection of requirements in terms of Atomicity, Consistency, Isolation and Durability, which altogether are fundamental to ensure dependability and, more specifically, reliability. Up to now, this task is definitively not supported by a process. This thesis provides a novel process, called PRISMA. PRISMA is a Process for Requirements Identification, Specification and Machine-supported Analysis that targets transaction models. PRISMA is helpful as a prism in the identification of fundamental and constituting properties of transaction models to achieve, as a result of the PRISMA process, a correct and valid requirements specification. The main idea behind PRISMA is that transaction models may be considered as a product line and that variabilities and commonalities may be identified to distinguish similarities and differences among "products". Specifically, PRISMA is conceived for engineering the specification of a transaction model by placing the effort in revealing its Atomicity, Consistency, Isolation and Durability requirements, which represent the variabilities of the product line. PRISMA contributes on one hand in increasing quality, in particular dependability, and on the other hand in reducing time to market and cost by intensifying reusability. [less ▲]

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See detailReliable information acquisition in the presence of malicious sources
Staab, Eugen Valentin UL

Doctoral thesis (2010)

In distributed systems in which autonomous entities exchange information with each other, these entities have the freedom to provide incorrect information. This becomes especially relevant in scenarios ... [more ▼]

In distributed systems in which autonomous entities exchange information with each other, these entities have the freedom to provide incorrect information. This becomes especially relevant in scenarios where entities have incentives to do so, e.g., in peer-to-peer networks or volunteer computing systems. Cryptographic mechanisms can help to ensure data integrity and authenticity. However, while these mechanisms achieve a reliable transmission of information, they do not prevent the creation of incorrect information in the first place. Therefore, additional mechanisms are necessary to enable an entity to assess the correctness of acquired information. In specific applications, the correctness of acquired information can be verified, or be assessed by means of plausibility checks. This is not possible in general, though. Often the explicit verification of information is infeasible, for instance due to high costs. In this thesis, we investigate different generic approaches to ensure the correctness of information without explicitly verifying it. More precisely, we propose three mechanisms, each of which is suitable for certain scenarios and tasks: a spot-checking mechanism that uses known facts to ensure the correctness of acquired information; an evidence-based trust model that learns – based on past experience – to exclusively select trustworthy sources; and a collusion detection algorithm that addresses the main threat to mechanisms that ensure the correctness of information by means of redundancy. The proposed mechanisms are validated, theoretically and/or experimentally, against plausible attack strategies of malicious sources. We show that our mechanisms are able to deal with different kinds of attack strategies, and that our trust model and the collusion detection algorithm successfully identify malicious sources. [less ▲]

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See detailContribution à l'étude de la notion de crime organisé en Europe: L'exemple de la France et de la Grèce
Rodopoulos, Ioannis UL

Doctoral thesis (2010)

The presented study examines the juridical, socio-political and epistemological implications, caused by the insertion of the concept of organised crime into the European penal legislations, precisely the ... [more ▼]

The presented study examines the juridical, socio-political and epistemological implications, caused by the insertion of the concept of organised crime into the European penal legislations, precisely the French and Greek ones. Firstly, the study concerns the process by which the preexistent legal notions concerning criminal participation and group-based offenses have gradually been replaced by an allegedly univocal notion of organised crime, as well as the consequences of this substitution for the concerned juridical systems. This study of the “sein” of contemporary policy towards organised crime, invites us to think also about its “sollen”. The serious legal-dogmatic problems and the semantic entropy inherent to the concept, combined with the justified worries about the politico-philosophical orientations of contemporary criminal policy systems, lead us to rethink not only the utility of the juridicisation of a concept which is ontologically inappropriate for scientific treatment, but also the latent manichean tendencies behind this process; tendencies which, much more than organised crime itself, threaten the declared values of our societies and our justice systems. [less ▲]

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See detailNew tools for conviviality. Masks, norms, ontology, requirements and measures. Bridging the conviviality gap between policy and informatics
Caire, Patrice UL

Doctoral thesis (2010)

The notion of conviviality has an intuitive meaning for human society, which is to feel welcome in a community and at ease with its members. We believe it also has particular significance for the design ... [more ▼]

The notion of conviviality has an intuitive meaning for human society, which is to feel welcome in a community and at ease with its members. We believe it also has particular significance for the design of artificial social systems. Traditionally conviviality has been shown to be useful in human interactions, thus the abundance of artificial social systems is likely to benefit from its application. In this thesis, we explore the possibility of developing the concept of conviviality in artificial social systems in depth. We provide a number of tools to help designers of artificial social systems to include conviviality at the onset of their design. First, we identify what we believe to constitute a promising field of research. Second, we abstract the notion of conviviality. Starting from the philosophical notion proposed by Illich, “individual freedom realized in personal interdependence”. Using Taylor’s intuition about a conviviality mask, we advance a formalization in terms of interdependence of agents and their goals, and the social norms that determine that interdependence. Third, we operationalize conviviality for the development of artificial social systems. We establish correspondence between software engineering and social science domains. We formalize the interdependence between members of a group with dependence networks, and use the stakeholder-agent concept to pro- vide individual agents’ points of view. Fourth, we propose a way to elicit conviviality requirements during the early phase of the development of artificial social systems, using the Tropos agent methodology. Finally, we provide a glimpse of the type of conviviality properties that can be measured in artificial social systems, and thus define the convivial quality of the system. Throughout this thesis we illustrate our arguments with two running examples, one from Second Life, the other from the city of Luxembourg. [less ▲]

Detailed reference viewed: 140 (10 UL)
See detailAlgorithms mapping into elliptic curves and applications
Icart, Thomas UL

Doctoral thesis (2010)

Detailed reference viewed: 93 (7 UL)
See detailK-Anonymity in Mobile Ad-Hoc Networks
Spiewak, Dagmara UL

Doctoral thesis (2010)

Detailed reference viewed: 60 (4 UL)
See detailAnalyse harmonique sur certains groupes de Lie à croissance polynomiale
Lahiani, Raza UL

Doctoral thesis (2010)

Detailed reference viewed: 46 (1 UL)
See detailApproaches for collaborative filtering in distributed environments
Gratz, Patrick UL

Doctoral thesis (2010)

Detailed reference viewed: 42 (3 UL)
See detailTopology dynamics and secure routing for predictable mobile networks
Fischer, Daniel UL

Doctoral thesis (2010)

Detailed reference viewed: 259 (3 UL)
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See detailLa médiation de l’archéologie à la télévision : la construction d’une relation au passé.
Schall, Céline UL

Doctoral thesis (2010)

À l’heure actuelle, les occasions de « rencontrer » des hommes du passé (ou du moins leurs représentants) se multiplient : l’exposition d’archéologie ne présente plus seulement des objets, mais fait ... [more ▼]

À l’heure actuelle, les occasions de « rencontrer » des hommes du passé (ou du moins leurs représentants) se multiplient : l’exposition d’archéologie ne présente plus seulement des objets, mais fait découvrir au visiteur le mode de vie des anciens habitants d’un lieu ; les reconstitutions historiques font « revivre » des hommes du passé et mettent en scène courses de chars, artisanat et autres gestes « ancestraux » devant les yeux du public ; et enfin, les guides de monuments historiques prennent les traits de personnages-types, favorisant l’immersion et l’attachement au lieu. De la même manière, les émissions de télévision sur l’archéologie semblent de plus en plus effacer le scientifique et les vestiges du dispositif ; proposant ainsi une relation plus directe au passé et à l’homme du passé (c’est le cas par exemple de docufictions comme Homo Sapiens de Jacques Malaterre). Cette recherche questionne ainsi la relation au passé, proposée par les émissions de télévision sur l’archéologie. Comment ces films peuvent-ils créer une relation à la fois scientifique et symbolique au passé et à « l’autre » ? Quels sont les effets de cette nouvelle forme de médiation qui feint de s’effacer ? À l’inverse, quels sont les effets de l’affirmation du dispositif de médiation (dans les documentaires et les reportages) ? Pour répondre à ces questions, nous avons adopté une démarche « feuilletée », en « entonnoir ». Un corpus de référence réunit d’abord toutes les émissions sur l’archéologie diffusées entre 1995 et 2008, sur la télévision hertzienne française. Son analyse statistique permet de dégager des tendances générales quant à la représentation de l’archéologie à la télévision. Ensuite, l’analyse sémiopragmatique d’un corpus test de 13 émissions sur Pompéi, mène à la constitution d’un modèle d’analyse de la médiation du passé et d’un outil permettant la systématisation du recueil de données sur un grand nombre d’émissions. Enfin, un troisième corpus de 51 émissions permet la vérification de ce modèle et aboutit à l’identification de quatre types de construction de la relation au passé. L’apport de l’étude est triple : 1) elle génère des connaissances sur l’objet de recherche lui-même, c’est-à-dire sur les représentations les plus courantes de l’archéologie à la télévision ; 2) elle propose une méthodologie et un modèle d’analyse de la médiation fondés sur des outils issus de la sémiopragmatique ; 3) enfin, d’un point de vue théorique, la recherche permet d’envisager la médiation, non comme un lien sociétal ou un « entre-deux », mais comme une stratégie de modulation de la distance, possible notamment grâce à l’intervention de « figures » de médiation. Ces figures sont des éléments référentiels qui cristallisent des représentations sociales et qui ont des rôles à jouer dans l’énonciation et la narrativité de l’émission. [less ▲]

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See detailSemiotik der digitalen Medienkunst: Eine funktionale Kunstbetrachtung
Huemer, Birgit UL

Doctoral thesis (2010)

Art-forms, which use digital technologies for production and design and which reflect these technologies critically, are becoming increasingly popular. Caused by technological development, art production ... [more ▼]

Art-forms, which use digital technologies for production and design and which reflect these technologies critically, are becoming increasingly popular. Caused by technological development, art production and design has changed considerably during the last years. Nowadays digital artworks are generated multimodally and integrate the visitor and the environment as represented and interactive participants into their work. In order to explore the meaning making potential of these artworks, I develop a systemic functional framework of analysis. This framework combines a sociological and a formal approach and offers an alternative perspective to enrich our knowledge and perception when engaging with art. It enables researchers to relate art and culture with communicative events and to analyse the interaction and exchange going on between artist, artwork, visitor and environment by describing semiotic resources that are used to generate digital artworks. The developed framework is a multimodal approach, based on semiotics and functional theory, which applies a sociological concept and functional categories to the analysis of multimodal texts. This multimodal approach enables researchers to explain how different semiotic systems or modes (language, image, sound, body language, facial expression and three-dimensional spaces, etc.) are related to each other in different genres such as every day language, scientific texts and art to realise meanings. Hitherto multimodal analysis has basically focused on the combination and relation of only two modes in a text (i.e. language and image). By analysing artworks that are generated of verbal, visual and acoustic modes of communication as well as physical objects in three-dimensional space the multimodal approach is extended in this thesis. Thus this work will contribute to multimodal research and art and media theory. With this framework of analysis major principles of design in digital art, that have become significant within the last years, can be explained. Principles that are addressed in this thesis are: transformation, modification and translation from one mode into another, virtual environments and telepresence, creating new visitor perspectives and interactive concepts as well as cohesion in digital art. [less ▲]

Detailed reference viewed: 76 (2 UL)
See detailSocial Spatial Difference Delimiting Borders in Berlin
Carr, Constance UL

Doctoral thesis (2010)

Detailed reference viewed: 94 (7 UL)
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See detailSparse Channel Estimation based on Compressed Sensing Theory for Ultra-Wideband Systems
Lagunas, Eva UL

Bachelor/master dissertation (2010)

Detailed reference viewed: 67 (4 UL)
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See detailExperts going transnational: education at world exhibitions during the second half of the nineteenth century
Dittrich, Klaus UL

Doctoral thesis (2010)

This thesis investigates the educational sections of the great international exhibitions of the latter half of the nineteenth century. This thesis takes into account the participation of actors from ... [more ▼]

This thesis investigates the educational sections of the great international exhibitions of the latter half of the nineteenth century. This thesis takes into account the participation of actors from France, Germany, Japan and the United States. Focusing on education experts, this thesis is a contribution to a sociocultural history of an intellectual and administrative elite in an age of early globalisation. World exhibitions were one of the major media for the transnational circulation of educational knowledge. The central question is why education experts from these four countries invested so many resources in order to prepare and visit world exhibitions. Why did they go transnational? The thesis proposes two answers. Firstly, education experts used world exhibitions in order to appropriate the most advanced pedagogical models for their own institutional contexts. The concept of cultural transfers is a useful tool to analyse these appropriations. Knowledge circulation at world exhibitions made a crucial contribution to the institutionalisation of primary education and technical education. Secondly, education experts used world exhibitions to stage their own institutions on an international stage. The proud representation of the educational achievements of one’s own context was the final phase of successful cultural transfers. Educational displays became increasingly embedded in nationalist discourses. During the 1870s pedagogical know-how circulated relatively easily. Towards the turn of the century the self-representation of institutions became predominant. This original approach aims at furthering the understanding of globalisation in the nineteenth century. Still, the thesis argues that world exhibitions were in a large measure media for transnational professional discourses in many fields, including education. [less ▲]

Detailed reference viewed: 304 (18 UL)
See detailBearing capacity of steel fiber reinforced concrete flat slabs
Michels, Julien UL

Doctoral thesis (2009)

Detailed reference viewed: 180 (9 UL)
See detailJeunesses et respect dans une société fragmentée En quoi respect et reconnaissance sont au cœur des constructions identitaires des jeunes et de leur intégration dans la société ?
Kerivel, Aude UL

Doctoral thesis (2009)

La société s’interroge sur les actes irrespectueux de certains jeunes et ces derniers demandent du respect. Un paradoxe qui nous amène à donner la parole aux jeunes afin de comprendre le sens qu’ils ... [more ▼]

La société s’interroge sur les actes irrespectueux de certains jeunes et ces derniers demandent du respect. Un paradoxe qui nous amène à donner la parole aux jeunes afin de comprendre le sens qu’ils donnent au respect. D’un point de vue théorique et empirique, le respect se caractérise par sa pluralité de sens (dans la forme et le fond) et se définit souvent par son contraire : l’irrespect. Les deux sont directement liés : agir de manière irrespectueuse peut être un moyen de tenir l’autre en respect. L’irrespect subit par les jeunes nous conduit alors à considérer ces expériences en tant que relation intersubjective au travers de l’identité de l’offenseur et de l’offensé. Perçue comme égalitaire et réciproque, la relation de respect implique dans les discours des jeunes une hiérarchie ; celle ci nous amenant à interroger la notion d’autorité. L’autorité, autrefois inhérente au rapport entre adultes et jeunes, est aujourd’hui tantôt contestée, tantôt perçue comme une nécessité. Dans le contexte d’une société que l’on peut qualifier de fragmentée, la quête de respect nous semble au cœur des constructions identitaires des jeunes et de leur intégration. Les jeunes se trouvent au centre de multiples paradoxes : une liberté restreinte parmi des possibles déterminés, une égalité inaccessible dans la distribution de l’estime et une fraternité remise en cause par la lutte des places. Pour les jeunes, le respect serait le langage de la reconnaissance permettant la mobilité dans l’espace-temps. Une mobilité conditionnée par le fait d’avoir été considéré comme valable dans le regard de l’Autre et donc la possibilité de se percevoir comme respectable. [less ▲]

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See detailNichtgleichgewichtsphänomene, Strukturbildung und Grenzflächeneinflüsse in netzwerkbildenden Systemen aus optischer und akustischer Sicht.
Philipp, Martine UL

Doctoral thesis (2009)

Isostructural phase transitions occurring under non-equilibrium conditions are investigated using technologically relevant epoxies. The evolution of the hypersonic and optical properties during the ... [more ▼]

Isostructural phase transitions occurring under non-equilibrium conditions are investigated using technologically relevant epoxies. The evolution of the hypersonic and optical properties during the genesis of the polymeric network leads to deeper insight into the chemically induced sol-gel transition and glass transition, as demonstrated e.g. by the elastic anharmonicity and the generalised Cauchy relation. During gelation the refractive index versus chemical conversion behaves in an unexpected manner, indicating that in addition to the mass density an excess polarisability seems to contribute to the optical polarisability. The clarification of the isostructural phase transitions is impeded by the demixing tendency of the epoxy components which leads to different types of epoxy inhomogeneities on the nano- to mesoscopic scale. Taking benefit from a sample arrangement where both epoxy components are layered, the spatio-temporal evolution of acoustic properties gives supplementary information about trans-interfacial transport and structure formation processes. Of special technological relevance, but also of fundamental interest, is the influence of nanoscopic disturbances placed into the epoxy matrix. So-called interphases surrounding the nanoparticles modify and complicate the epoxy network formation, leading to long-lived metastable morphologies and properties. The role of the mixing sequence of the epoxy resin, the hardener and the nanoparticles for the polymerised epoxy state and the transient states during network formation, as well as the isostructural phase transitions is further elucidated. [less ▲]

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See detailZur Rotationskapazität von Verbundanschlüssen bei der Bemessung nach dem Fließgelenkverfahren
Hahn, Christoph UL

Doctoral thesis (2009)

The present work deals with the load bearing and rotational behaviour of composite connections in steel and concrete constructions. For typical buildings, composite connections are assumed to be rigid or ... [more ▼]

The present work deals with the load bearing and rotational behaviour of composite connections in steel and concrete constructions. For typical buildings, composite connections are assumed to be rigid or pinned. This assumption can lead to uneconomic structures. A design concept for the estimation of the available rotation capacity, the initial stiffness and the moment bearing capacity of semi-rigid connections is presented. On the basis of the plastic hinge theory diagrams were developed to prove the load carrying capacity and the serviceability of composite beams with semi-rigid connections. The presented design model is based on the evaluation of 9 self conducted tests and on the evaluation of 74 tests on composite connections from all over Europe. The availability of the model was proved by intensive nonlinear finite element simulations. [less ▲]

Detailed reference viewed: 78 (8 UL)
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See detailOn the physical security of cryptographic implementations
Rivain, Matthieu UL

Doctoral thesis (2009)

In modern cryptography, an encryption system is usually studied in the so-called black-box model. In this model, the cryptosystem is seen as an oracle replying to message encryption (and/or decryption ... [more ▼]

In modern cryptography, an encryption system is usually studied in the so-called black-box model. In this model, the cryptosystem is seen as an oracle replying to message encryption (and/or decryption) queries according to a secret value: the key. The security of the cryptosystem is then defined following a simple game. An adversary questions the oracle about the encryption (and/or decryption) of messages of its choice and, depending on the answers, attempts to recover the value of the secret key (or to encrypt/decrypt a message for which he did not query the oracle). If by following an optimal strategy the adversary only has a negligible chance of winning, the system is considered as secure. Several cryptosystems have been proved secure in the black-box model. However, this model is not always sufficient to ensure the security of a cryptosystem in practice. Let us consider the example of smart cards which are used as platforms for cryptosystems in various applications such as banking, access control, mobile telephony, pay TV, or electronic passport. By the very nature of these applications, a cryptosystem embedded on a smart card is physically accessible to potential attackers. This physical access invalidates the modeling of the cryptosystem as a simple encryption oracle since it allows the adversary to observe and disrupt its physical behavior. New attacks then become possible which are known as physical cryptanalysis. Physical cryptanalysis includes two main families of attacks: side channel attacks and fault attacks. The purpose of side channel attacks is to analyze the different physical leakages of a cryptographic implementation during its computation. Chief among these rank timing, power consumption, and electromagnetic radiation. Observing these so-called side channels provides sensitive information about the cryptographic computation. The secret key value can then be easily recovered by statistical treatment although the cryptosystem is secure in the black-box model. The access to a cryptographic implementation enables more than a simple observation of its physical behavior; it is also possible to disrupt its computation. Working on this assumption, fault attacks consist in corrupting cryptographic computations so that they produce erroneous results. Surprisingly, these results can be used in order to recover information about the secret key. This thesis focuses on physical cryptanalysis as well as on the secure implementation of cryptographic primitives. We examine in the first part side channel attacks from a theoretical viewpoint. Various techniques of attack based on different statistical tools are addressed. We analyze their success rate, we compare their efficiency and we propose some improvements. Our analyses are illustrated by results of simulated attacks as well as practical attacks on smart cards. The second part of this thesis is devoted to one of the most widely used countermeasures to side channel attacks: data masking. Our investigations concentrate on generic masking schemes for block ciphers such as the encryption standards DES and AES. We analyze existing schemes, exhibiting some attacks against certain of them and we propose new designs. The third and last part of this thesis deals with fault attacks. First, we describe a new attack on the DES cipher which exhibits some requirements to its secure implementation. We then provide a case study based on the RSA cryptosystem where we propose a new countermeasure which can also be applied to secure any exponentiation algorithm. We finally address an important issue for practical security: the implementation of coherence checks. [less ▲]

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See detailSecurity matters: Privacy in Voting and Fairness in Digital Exchange
Jonker, Hugo UL

Doctoral thesis (2009)

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See detailAnonymity and Unlinkability in Electronic Communications
Fusenig, Volker UL

Doctoral thesis (2009)

Imagine a set of communication partners wants to keep their communication links secret. Consider the case where untrustworthy parties are able to observe every communication, which implies not only that ... [more ▼]

Imagine a set of communication partners wants to keep their communication links secret. Consider the case where untrustworthy parties are able to observe every communication, which implies not only that they can detect the content of the communication, but also who is communicating and who is listening. Using this information, the untrustworthy parties try to link communicating parties. This, in a nutshell, is the problem of anonymous and unlinkable communication in computer networks. By use of encryption techniques the content of messages can be kept private. However, the communication links can still be detected. Since the addresses of sending and receiving parties are contained in the header of every message sent over the network, an untrustworthy party needs only to eavesdrop a single message of the communication in order to link sender and receiver. Additional techniques have to be used to hide this information. We address this problem in this thesis. We define measures for anonymity and unlinkability that are based on the information theoretic notion of entropy. These measures are used first to evaluate different approaches for anonymous and unlinkable communication and second, to show the effectiveness of attacks on these protocols. We present existing techniques for anonymous and unlinkable communication and highlight weak points of these techniques by applying attacks to them. In these attacks, known as traffic analysis attacks, the attacker basically tries to collect as much information about the communication as possible and then makes deductions concerning the communication links. We show that these traffic analysis attacks are applicable to many existing techniques. Furthermore, we introduce a new traffic analysis attack, namely the slotted packet-counting attack. Motivated by these findings, we present a protocol for unlinkable communication in computer networks. We prove that this protocol leaks no information on communication links in the case where attackers are able to observe any communication in the network. By this means, the protocol guarantees a user-defined degree of unlinkability. We also show that the protocol generates a minimal amount of extra messages for achieving a given degree of receiver anonymity, i.e. where an attacker is not able to detect the receiver of a message. [less ▲]

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See detailRégulation de la position d'une bille sur un plateau inclinable
Bernard, Nicolas UL

Bachelor/master dissertation (2009)

Le but de ce projet était d'étudier la régulation de la position d'une bille sur un plateau mobile, celui-ci devant être préalablement construit. Ce plateau est mobile en ceci qu'il peut s'incliner selon ... [more ▼]

Le but de ce projet était d'étudier la régulation de la position d'une bille sur un plateau mobile, celui-ci devant être préalablement construit. Ce plateau est mobile en ceci qu'il peut s'incliner selon ses deux axes, l'inclinaison étant contrôlable par des moteurs. Le plateau est constitué (ou, comme ici, recouvert) d'une dalle tactile qui permet de connaître la position de la bille. Dans la fabrication de ce projet, il y a trois parties distinctes: - la partie mécanique; - la partie électronique; - la partie informatique, c'est-à-dire la programmation de la puce (un microcontrôleur dsPIC) qui contrôle le système. Toutefois, avant de parler de la fabrication elle-même, nous allons commencer par étudier ce système de manière théorique. C'est l'objet du premier chapitre. [less ▲]

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See detailOn noncommutative deformations, cohomology of color-commutative algebras and formal smoothness
Gohr, Aron Samuel UL

Doctoral thesis (2009)

The main topic under study in the present work is the deformation theory of color algebras. Color algebras are generalized analogues of associative superalgebras, where the underlying grading can be over ... [more ▼]

The main topic under study in the present work is the deformation theory of color algebras. Color algebras are generalized analogues of associative superalgebras, where the underlying grading can be over an arbitrary abelian group and the Koszul sign is replaced by a bicharacter from the group into the base ring. A special case of particular interest are color-commutative algebras, which satisfy a commutation identity similar to (but much more general than) supercommutative algebras. Examples of color-commutative algebras include commutative and supercommutative superalgebras, the quaternions and para-quaternions, full matrix algebras over suitable base rings, Clifford algebras, and group rings over certain nonabelian groups. In the present work, Gerstenhaber-type formal deformations of these algebras are studied. In doing so, we extend previous work by Scheunert and provide a different approach to noncommutative deformation theory as introduced by Pinczon and Nadaud. In preparation of developing deformation theory for color algebras, we adapt a number of tools from ungraded Hochschild theory to our setting: among them, we derive an adapted Ext-functor, a color Gerstenhaber bracket, twisted graded versions of pre-Lie-algebras and pre-Lie-systems and colored analogs of the classical results linking infinitesimal deformations and obstructions to extension of deformations to second and third Hochschild cohomology. Additionally, we discuss the impact of some decisions in the construction of the trivial deformation object (color power series rings of given degree) on the resulting deformation theory. Finally, color-commutative deformations of color-commutative algebras are discussed and a suitable version of Harrison cohomology is developed. Also, the problem of classifying the color-commutative structures compatible with a given ungraded algebra is discussed and one nontrivial example is studied in detail. In support of all of these efforts, a number of structure theorems about color-commutative algebras are shown. [less ▲]

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See detailSESAME: a Model-Driven Process for the Test Selection of Small-size Safety-related Embedded Software
Ries, Benoît UL

Doctoral thesis (2009)

Embedded software applications are part of our daily lives, some of which have safety implications on human beings. It is thus important to trust this type of software. In our industrial context, testing ... [more ▼]

Embedded software applications are part of our daily lives, some of which have safety implications on human beings. It is thus important to trust this type of software. In our industrial context, testing is the most widely-spread technique used for that purpose. The state of practice is divided in two main categories. Explicit test selection techniques that enumerate the test cases to be exercised, but do not offer large coverage of the system’s behavior; and implicit techniques that encompass fully automated test generation techniques, which tend to hide the test selection information from engineers. The problem that we aim at solving in this thesis is the definition of a test selection approach that is capable of helping test engineers to better reach a delimited and verifiable test set with respect to some given test requirements and project specificities taking into account different test stakeholders.<br /><br />The SESAME process is composed of the four following tasks: specification of the system for testing purposes; specification of a test selection that constrains the system specification; evaluation of the test selection; generation of test cases derived from the constrained system specification. As a validation of our approach, we apply the SESAME process to a case study taken from an industrial project. This industrial application has shown the applicability of our approach on a small-size safety-related embedded system. [less ▲]

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See detailWorking Memory and Learning A 3-Year Longitudinal Study of Children Growing Up In a Multilingual Environment
Engel de Abreu, Pascale UL

Doctoral thesis (2009)

This thesis presents the findings of a 3-wave, latent variable longitudinal study, exploring variations and the development of working memory in young children and its contributions to learning in the key ... [more ▼]

This thesis presents the findings of a 3-wave, latent variable longitudinal study, exploring variations and the development of working memory in young children and its contributions to learning in the key domains of language, literacy, and mathematics. A sample of 119 Luxembourgish children, learning German and French as secondary languages, were followed from kindergarten to second grade and completed multiple assessments of working memory, short-term memory, phonological awareness, fluid intelligence, vocabulary, language comprehension, foreign language knowledge, reading, spelling, and mathematics. Results indicate that relations between the measures were best characterized by a model consisting of two related but separable constructs - corresponding to shortterm storage and a central executive - that were highly stable across the years. Whereas verbal short-term memory was more specifically linked to early language development and vocabulary in particular, the central executive appeared to support learning in a wide range of domains, including language comprehension, literacy, and mathematics. The findings reinforce previous evidence indicating that verbal short-term memory is one of the main contributors to vocabulary development by supporting the formation of stable phonological representations of new words in long-term memory. Furthermore, the findings fit well with the position that the central executive makes general rather then specific contributions to learning - possibly in terms of an attentional control system that actively maintains crucial information and regulates controlling processes during complex cognitive activities. In conclusion, the findings indicate that different components of the working memory system can be reliably assessed in children as young as 5; that individual differences in these abilities are highly stable over time; and that working memory assessments are predictive of future learning in key academic domains. This reinforces the value of early screening of working memory abilities to identify children who are at a present and future educational risk. [less ▲]

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See detailUne approche adaptative pour la recherche d'information sur le web
Pruski, Cédric UL

Doctoral thesis (2009)

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See detailExterne Evaluation als Impulsgeber für Schulentwicklung? Eine explorative Untersuchung
Weis, Daniel UL

Bachelor/master dissertation (2009)

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See detailTwo Neighbors, One Vision? The Impact of the European Union's Accession on the Development of Sociology in the Common Border Region Slovenia and Southern Austria. PhD thesis, University of Graz.
Hoenig, Barbara UL

Doctoral thesis (2009)

This dissertation thesis in the sociology of knowledge investigates the impact of European Union's research policies on the formation of sociology as a scientific discipline. From a comparative ... [more ▼]

This dissertation thesis in the sociology of knowledge investigates the impact of European Union's research policies on the formation of sociology as a scientific discipline. From a comparative perspective, Slovenia and Austria as two small Central European neighbour states and their common border region are taken as a case study, applying a mixed methods design. Based on extensive empirical data analyses with a strong focus on scientific institutions, findings show enabling and constraining effects of opportunity structures given by Europeanization of research policies. Transnational cooperation of scholars contributes to a stock of knowledge more and more known as European sociology. [less ▲]

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See detailAlgebraic approach to modal extensions of Łukasiewicz logics
Teheux, Bruno UL

Doctoral thesis (2009)

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See detailTheories of National Social Policy in Light of Emerging Global Social Policy Patterns
Zapp, Mike UL

Bachelor/master dissertation (2009)

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