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See detailRobust topology management in DT-MANETs: An efficient tree-based decentralized and multi-objective approach
Piyatumrong, Apivadee UL

Doctoral thesis (2010)

Delay-tolerant mobile ad hoc network (DT-MANETs) feature frequent and long duration partitioned MANETs. It is a challenged environment where end-to-end connectivity cannot always be obtained. Furthermore ... [more ▼]

Delay-tolerant mobile ad hoc network (DT-MANETs) feature frequent and long duration partitioned MANETs. It is a challenged environment where end-to-end connectivity cannot always be obtained. Furthermore, communication in such network is heavily relying on collaboration between nodes since there is no central authority. Limited resources of communication nodes present another facet of problems in such network. Moreover, the communication is typically done using wireless technologies which are sharing among communication nodes. In order to provide a better quality of service in such environment, topology management technique is used to help controlling network topology. The aim is to manage network resource and to enhance efficiency of communication. In this work, we proposed to do it by constructing an efficient and robust tree-based topology. We model the environment using dynamic and partitioned graph. Under such circumstances, protocols must withstand topology and condition changing. In summary, doing topology management in DT-MANETs encounters the following issues: cooperation among nodes, limitation of resources of mobile node, sharing medium, dynamic and partitioned topology and unrealistic and unscalable approach of centralized algorithm in such environment. This study focuses on managing tree-based topology in DT-MANETs. A set of active links is managed such that the deterioration of network is avoid and the quality of service in DT-MANETs is enhanced. Efficiency and robustness metrics are proposed accordingly. This work proposed to use different quality criteria based on communication node and edge for the selection topology. Both single- and multi-objectives tree-based topology are studied. Algorithms for managing tree-based topology are proposed according to different objectives. All proposed algorithms are purely decentralized, asynchronous algorithm and use one-hop information. [less ▲]

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See detailModalités du développement professionnel d'enseignants du préscolaire et du primaire, dans le domaine du plurilinguisme: conception et évaluation d'une formation continue dans un pays plurilingue (Luxembourg)
Elcheroth, Sylvie UL

Doctoral thesis (2010)

This action-research consists in designing, implementing and evaluating the continuous teacher education programme ‘Ecole multilingue’. The programme is aimed at preschool and primary school teachers and ... [more ▼]

This action-research consists in designing, implementing and evaluating the continuous teacher education programme ‘Ecole multilingue’. The programme is aimed at preschool and primary school teachers and concerns the pedagogy of multilingualism. During the programme, video excerpts showing language learning practices at school were studied, multilingual projects were designed and implemented in the classes of the participants and discussions and exchanges took place within ten monthly meetings. The research questions are the following: What is the professional development that is realised throughout the programme? What are the characteristics of the programme that have afforded this development? The research positions itself within the framework of socio-constructivist and socio-cultural theories. The chosen methodology draws upon thematic analysis, grounded theory, analysis of interactions and analysis of practice. It implies the collection of different types of data: questionnaire, videotapes and transcriptions of the training meetings, logbook of the trainer-researcher, videotapes and descriptions of innovative practices. During the research process, description and analysis grids are used and designed, and research results are cut across. A reflexion about the double role of a trainer and a researcher is developed. The analysis reveals the representations about language learning, multilingual practices and institutional context, as well as the ways of analysing pupils’ learning processes, co-constructed by the participants. It characterises the innovative multilingual practices that the participants have developed in their classes, and it shows the process of accompanying-challenging by the trainer. It furthermore brings out the ways in which the different elements of the programme have contributed to the teachers’ development. It finally may inform a prospective, improved training programme. [less ▲]

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See detailBerezin symbols and Berezin transform revisited
Schlichenmaier, Martin UL

Scientific Conference (2010, December 14)

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See detailAlleviating the Mesh Burden in Computational Solid Mechanics
Bordas, Stéphane UL; Rabczuk, Timon; Ródenas, Juan-Jo et al

in Proceedings of ECT2010 (2010, December 12)

The goal of this chapter is to review recent avenues of investigation to alleviate meshing difficulties in computational mechanics and give a few exemplar applications. Keywords: meshing; enrichment ... [more ▼]

The goal of this chapter is to review recent avenues of investigation to alleviate meshing difficulties in computational mechanics and give a few exemplar applications. Keywords: meshing; enrichment; meshfree methods; extended finite element methods; isogeometric analysis; advanced remeshing techniques. [less ▲]

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See detailTous les chemins mènent à la Belle Inconnue
Freyermuth, Sylvie UL

Presentation (2010, December 11)

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See detailProlégomènes pour une étude du champ littéraire du Grand-Duché
Fehlen, Fernand UL

Presentation (2010, December 10)

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See detailCUBA: Artificial conviviality and user-behaviour analysis in web-feeds
Kaufmann, Sascha UL

Doctoral thesis (2010)

Conviviality is a concept of great depth that plays an important role in any social interaction. A convivial relation between individuals is one that allows the participating individuals to behave and ... [more ▼]

Conviviality is a concept of great depth that plays an important role in any social interaction. A convivial relation between individuals is one that allows the participating individuals to behave and interact with each other following a set of conventions that are shared, commonly agreed upon, or at least understood. This presupposes an implicit or an explicit regulation mechanism based on consensus or social contracts and applies to the behaviours and interactions of participating individuals. With respect to an intelligent web-based system, an applicable social contribution is the give of assistance to other users in situations that are unclear and in guiding him to find the right decision whenever a conflict arises. Such a convivial social biotope deeply depends on both implicit and explicit co-operation and collaboration of natural users inside a community. Here, the individual conviviality may benefit from “The Wisdom of Crowds”, which fosters a dynamic understanding of the user’s behaviour and a strong influence of an individual’s well being to another person(s). The web-based system CUBA focus on such a behavioural analysis through profiling and demonstrates a convivial stay within a web-based feed system. [less ▲]

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See detailEnvironmental indicators for the evaluation of consumption patterns: the case of Luxembourg
Hild, Paula UL; Mey, Morgane; Jury, Colin et al

Speeches/Talks (2010)

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See detailDT4BP: a Business Process Modelling Language for Dependable Time-Constrained Business Processes
Capozucca, Alfredo UL

Doctoral thesis (2010)

Today, numerous organisations rely on information software systems to run their businesses. The effectiveness of the information software system then, depends largely on the degree to which the ... [more ▼]

Today, numerous organisations rely on information software systems to run their businesses. The effectiveness of the information software system then, depends largely on the degree to which the organisation's business is accurately captured in the business model. The business model is an abstract description of the way an organisation's functions. Thus, the more precise the business model, the more accurate the requirement definition of the information software system to be engineered.There are an abundance of tools and notations available today to support the development of many types of business process. Many of these artifacts rely on the concept of a business process to describe a business model. A business process is commonly known as a set of one or more linked procedures or activities which collectively realise a business objective or policy goal, normally within the context of an organisational structure defining functional roles and relationships". This thesis is concerned with modelling business processes as a means to accurately capture an organisation's activities and thus, the requirements of the software system that supports these activities.Among the infinite set of possible business processes, this thesis targets only those characterized by the qualities of dependability, collaboration and time. Business processes having these specific dimensions are referred to as Dependable, Collaborative and Time-Constrained (DCTC) business processes. A dependable business process is one whose failures or the number of occurrences in which business process misses its goal are not unacceptably frequent or severe (from certain viewpoint). A collaborative business process is one that requires the interaction of multiple participants to attain its goal. A time-constrained business process is one that owns at least one property expressed in terms of an upper or lower time bound. This thesis investigates how DCTC business processes can be described such that the resulting model captures all the relevant aspects of each dimension of interest. In addition, the business model must be comprehensible to the stakeholders involved not only in its definition, but also in its further use throughout the software development life cycle.A revision and analysis of notations that exist for modelling business processes conducted in this thesis have revealed that today there does not exist any modelling language that provides comprehensible, suitable and sufficiently expressive support for the characteristics of dependability, collaboration and time in an integrated manner. Hence, a significant part of this thesis is devoted to the definition of a new business process modelling language named DT4BP. The aim of this new modelling language is to be comprehensible, suitable and expressive enough to describe DCTC business processes. The definition of this new modelling language implies that a concrete syntax, an abstract syntax, a semantic domain and a semantic mapping is provided. The definition of this new modelling language is given following the Model-Driven Engineering (MDE) approach, and in particular the metamodelling principles. Thus, meta-models and model transformations are used to precisely specify the abstract syntax and semantic mapping elements of the language definition, respectively. Since DT4BP is a textual modelling language, its concrete syntax is specified by a context-free grammar. The Coordinated Atomic Actions conceptual framework with real-time extensions (Timed-CaaFWrk) is used as the semantic domain as it covers a large part of the abstractions included in dependable collaborative time-constrained business processes. The formalisation of this semantic domain according to the metamodelling principles is also part of the material presented in this thesis. Since the business model is considered as a representation of the requirement document the software system to be developed, it is crucial to validate whether it captures the requirements as intended by the stakeholder before going further in the software development process. Hence, besides the comprehensibility, suitability and expressiveness of the modelling language with respect to the domain of interest, it is of special interest to provide a mechanism that allows modellers to ensure that the business model is correct with respect to the stakeholder's expectations. One way of achieving this goal is to provide the modelling language with an executable semantics. In this manner, any business model can be executed on sample input data, and its dynamic behaviour observed. The observation of the dynamic behaviour of the model may be considered as a simulation of the model based on the sample input data. By performing several simulations of the model, the modeller, in cooperation with the stakeholder, can judge whether the business model is correct. This thesis provides an executable semantics for Timed-CaaFWrk that, used in combination with the model transformation that defines the semantic mapping element of the language definition, allows DT4BP models to be validated by simulation. In this manner, the dynamic behaviour of a particular DT4BP model for a given sample input data can be observed by transforming it into a Timed-CaaFWrk model, which is then run thanks to the given executable semantics. [less ▲]

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See detailGesundheit und Wohlbefinden im Jugendalter: Ausgewählte Ergebnisse.
Residori, Caroline UL; Roob, Conny UL

Conference given outside the academic context (2010)

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See detailDie Konferenz an der Universität im Dorf
Sagrillo, Damien UL

in Revue Musicale (2010), (5), 43

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See detailStatistical Precoding with Decision Feedback Equalization over a Correlated MIMO Channel
Järmyr, Simon; Ottersten, Björn UL; Eduard, Jorswieck

in IEEE Transactions on Signal Processing (2010), 58(12), 6298-6311

The decision feedback (DF) transceiver, combining linear precoding and DF equalization, can establish point-to-point communication over a wireless multiple-input multiple-output channel. Matching the DF ... [more ▼]

The decision feedback (DF) transceiver, combining linear precoding and DF equalization, can establish point-to-point communication over a wireless multiple-input multiple-output channel. Matching the DF-transceiver design parameters to the channel characteristics can improve system performance, but requires channel knowledge. We consider the fast-fading channel scenario, with a receiver capable of tracking the channel-state variations accurately, while the transmitter only has long-term, channel-distribution information. The receiver design problem given channel-state information is well studied in the literature. We focus on transmitter optimization, which amounts to designing a statistical precoder to assist the channel-tailored DF equalizer. We develop a design framework that encompasses a wide range of performance metrics. Common cost functions for precoder optimization are analyzed, thereby identifying a structure of typical cost functions. Transmitter design is approached for typical cost functions in general, and we derive a precoder design formulation as a convex optimization problem. Two important subclasses of cost functions are considered in more detail. First, we explore a symmetry of DF transceivers with a uniform subchannel rate allocation, and derive a simplified convex optimization problem, which can be efficiently solved even as system dimensions grow. Second, we explore the tractability of a certain class of mean square error based cost functions, and solve the transmitter design problem with a simple algorithm that identifies the convex hull of a set of points in R2. The behavior of DF transceivers with optimal precoders is investigated by numerical means. [less ▲]

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