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See detailPerformance and Security of Low-Latency Anonymisation Systems
Ries, Thorsten UL

Doctoral thesis (2012)

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See detailIn Silico prediction of transcription factor binding sites by probabilistic models
Wienecke-Baldacchino, Anke UL

Doctoral thesis (2012)

The characterization of in silico detected transcription factor binding sites represents a fundamental problem in the field of regulatory gene expression analysis. Several approaches have been proposed to ... [more ▼]

The characterization of in silico detected transcription factor binding sites represents a fundamental problem in the field of regulatory gene expression analysis. Several approaches have been proposed to model DNA-protein-interactions, composed by two main classes: qualitative models considering a consensus sequence and quantitative models providing a measure of binding affinity. The latter can be further subdivided in models assuming an independent contribution of the nucleotides forming a potential binding site and more flexible ones implicating a positional interdependence. In this work the applicability of three probabilistic models to predict transcription factor binding sites has been investigated: (i) the simple position weight matrix (PWM), assuming independence, and two flexible models capturing positional interdependencies represented by a (ii) Chow-Liu Tree and (iii) Ensemble of Trees model. The training and validation of the models on the Mus musculus subset of the UniPROBE database revealed that complex models provide a better predictive power suggesting a high amount of transcription factors binding motifs being affected by positional interdependencies. Additionally, numerous transcription factors were detected, for which the Ensemble of Trees model outperformed both, the Chow-Liu Tree and PWM model. The UniPROBE-based trained models have been applied in a biological context - the prediction of differential binding profiles in five different ChIP-seq samples, followed by the detection of causative regulatory SNPs. The chosen set-up involved family trio data, meaning genotype data from a family composed of father, mother and daughter, providing internal validation. The models provide strong power to correctly classify true negatives in an independent biological sample, represented by a high specificity. The applied approach to detect causative regulatory SNPs, resulted in a candidate list of 20 SNPs. Those gain strong support by epigenetic markers and both, model-based predicted binding affinity of the comprising binding site and significant p-values, describing the effect of the nucleotide exchange. [less ▲]

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See detailIndividual adaptability : validation and application of the concept
Hamtiaux, Armanda UL

Doctoral thesis (2012)

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See detailEtude de propriétés dynamiques linéaires et non-linéaires de deux liquides colloïdaux modèles par rhéologie: DGEBA/Al2O3 et DGEBA/SiO2
Thomassey, Matthieu UL

Doctoral thesis (2012)

The dynamic mechanical behaviors of two model colloidal suspensions are compared in order to highlight microstructural changes in the suspensions. differentiate between the topological and physico ... [more ▼]

The dynamic mechanical behaviors of two model colloidal suspensions are compared in order to highlight microstructural changes in the suspensions. differentiate between the topological and physico-chemical impact of nanoparticles. For both systems the matrix material consists of the technologically relevant epoxy resin diglycidil ether of bisphenol A (DGEBA). The suspended nanoparticles are hydrophilic alumina and hydrophobic silica respectively. It will be shown that beside the classical α process an additional low-frequency relaxator exists whose qualitative frequency behavior is attributed to the pure presence of nanoparticles. The fine structure of the low-frequency relaxator depends on the physico-chemical surface properties of the nanoparticles. Similar to the α process the additional low-frequency relaxator shows cooperative behavior. Astonishingly, on the lines of the pure resin DGEBA, both colloidal suspensions show terminal behavior at very low frequency excitations. The nanoparticles are also shown to be responsible for non-linear dynamic and flow behaviors as well as for the emergence of free surface and volume instabilities. The transient character of flow is induced. [less ▲]

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See detailNumerical Investigation into the Primary Breakup of Liquid Jets and Sheets
Kannan, Kumar UL

Doctoral thesis (2012)

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See detailOpen-world Software: Specification, Verification and Beyond
Bianculli, Domenico UL

Doctoral thesis (2012)

Open-world software systems are built by composing heterogeneous,third-party components, whose behavior and interactions cannot be fully controlled or predicted; moreover, the environment they interact ... [more ▼]

Open-world software systems are built by composing heterogeneous,third-party components, whose behavior and interactions cannot be fully controlled or predicted; moreover, the environment they interact with is characterized by frequent, unexpected, and welcome changes. This class of software exhibits new features that often demand for rethinking and extending the traditional methodologies and the accompanying methods and techniques. In this thesis we deal with a particular class of open- world software, represented by service-based applications (SBAs). We focus on three specific aspects related to the development and provisioning of SBAs: specification, verification, and reputation management. With respect to these aspects, we provide methods and techniques that are i) suitable to deal with aspects such as change, evolution, and reliance on third- parties, and ii) able to improve the overall quality of the systems they are applied to. More specifically, concerning specification, we report on the findings of a study that analyzed requirements specifications of SBAs developed in research settings and in industrial settings. These findings have then driven the design of SOLOIST, a language used to specify the interactions of SBAs. Regarding verification, our contribution is twofold; we propose: i) a technique for automatically generating the behavioral interfaces of the partner services of a service composition, by decomposing the requirements specification of the composite service; ii) a framework for the definition of verification procedures (encoded as synthesis of semantic attributes associated with a grammar) that are made incremental using an approach based on incremental parsing and attributes evaluation techniques. Finally, as for reputation management, we present a reputation-aware service execution infrastructure, which manages the reputation of services used by composite SBAs in an automated and transparent manner. [less ▲]

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See detailMythe et mémoire. Une relecture du discours jonasien sur Dieu
Borghese, Ester UL

Doctoral thesis (2012)

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See detailGestural Interfaces for Elderly Users - Help or Hindrance?
Stossel, Christian UL

Doctoral thesis (2012)

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See detailProvable Security and Indifferentiability
Mandal, Avradip UL

Doctoral thesis (2012)

In this thesis we consider different problems related to provable security and indifferentiability framework. Ideal primitives such as random oracles, ideal ciphers are theoretical abstractions of ... [more ▼]

In this thesis we consider different problems related to provable security and indifferentiability framework. Ideal primitives such as random oracles, ideal ciphers are theoretical abstractions of cryptographic hash functions and block ciphers respectively. These idealized models help us to argue security guarantee for various cryptographic schemes, for which standard model security proofs are not known. In the first part of this thesis we consider the problems related to ideal primitive construction starting from a different ideal primitive. We adopt the indifferentiability framework proposed by Maurer et. al. in TCC’04 for this purpose. The indifferentiability framework helps us to preserve the security guarantee of cryptographic schemes when the ideal primitives are replaced by indifferentiable constructions, even when the ideal primitives are used in a public manner. At first, we consider the problem of ideal cipher domain extension. We show the 3-round Feistel construction, built using n-bit ideal ciphers are actually indifferentiable from a 2n-bit ideal cipher. We also consider other related issues such as, why 2-round Feistel is not sufficient, security analysis in standard indistinguishability model for both 2 and 3 round constructions, etc. Afterwards, we consider the open problem: whether 6-round Feistel construction using random round functions is indifferentiable from a random invertible permutation or not. We give a partial positive answer to this question. We show the construction is actually publicly-indifferentiable (which is a restricted version of full indifferentiability) from an in- vertible random permutation. In the later part of the thesis, we concentrate on some issues related to the security of Probabilistic Signature Scheme (PSS). PSS with RSA trapdoor is a widely deployed randomized signature scheme. It is known to be secure in Random Oracle model. However, recently randomized signature scheme such as iso/iec 9796-2 is shown to be susceptible to hardware fault attacks. In this work we show, PSS is actually secure against random fault attacks in random oracle model. Afterwards, we consider the openproblem related to standard model security of PSS. We give a general negative result in this direction. We rule out existence of any black box proof technique showing security of PSS in standard model. [less ▲]

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See detailImpact of chromatin organization on the regulation of vitamin D receptor target genes expression in human prostate cells
Zimna, Anna Ewa UL

Doctoral thesis (2012)

Vitamin D Receptor (VDR) belongs to the superfamily of nuclear receptors that are in total 48 ligand-activated transcription factors that bind to the DNA and are involved in the regulation of gene ... [more ▼]

Vitamin D Receptor (VDR) belongs to the superfamily of nuclear receptors that are in total 48 ligand-activated transcription factors that bind to the DNA and are involved in the regulation of gene expression. The active form of vitamin D3, hormone 1α,25-dihydroxyvitaminD3 (1α,25(OH)2D3), is a natural ligand for VDR. The generally described physiological functions of 1α,25(OH)2D3-activated VDR target genes are stimulation of metabolism as well as differentiation and inhibition of inflammation and cellular proliferation. In this study we focus primarily on the target genes of VDR that could potentially have a positive role in cancer prevention. Microarrays were performed of human non-malignant prostate RWPE1 cells after 4 h and 24 h treatment with 100 nM 1α,25(OH)2D3 and among several hundred responsive genes, we identified multiple members of the kallikrein (KLK) gene family as putative primary VDR targets. The KLKs are serine proteases that have been shown to be deregulated in various cancers. The 15 genes in the KLK family cluster together on human chromosome 19 span roughly 270 kB. KLK6 was the most responsive gene (16-fold induction after 4h treatment), followed by its neighboring KLK5, KLK7, KLK8 and KLK9. This effect of 1α,25(OH)2D3 was confirmed by real-time quantitative PCR and loss-of-function experiments. Interestingly, the VDR-mediated induction of the KLK genes was less pronounced in the cancer than in non-malignant prostate cells. In addition, we analyzed the genomic sequence of the KLK cluster in silico and identified a number of putative VDR binding sites (VDREs) as well as putative insulator CTCF binding sites. Chromatin regions containing putative binding sites were analyzed by chromatin immunoprecipitation assays to assess their functionality in RWPE1 cells. Six VDREs were associated with VDR whereas validation of detected CTCF binding sites showed increased occupancy of CTCF upon 1α,25(OH)2D3 stimulation. These results allow describing the changes in chromatin architecture on the KLK locus after VDR activation. Taken together, our study shows that 1α,25(OH)2D3-activated VDR has an impact on the regulation of the whole KLK gene cluster in prostate cells. [less ▲]

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See detailRelations entre maîtres de forges, autorités communales et gouvernementales au Grand-Duché de Luxembourg, de 1850 à 1914 – une étude de cas : Differdange et Dudelange
Kovacs, Stéphanie UL

Doctoral thesis (2012)

Our research relates to the relations between municipalities, ironmasters and central power during the initial phase of the process of industrialisation (1870-1914) and ensuing urban development. This ... [more ▼]

Our research relates to the relations between municipalities, ironmasters and central power during the initial phase of the process of industrialisation (1870-1914) and ensuing urban development. This topic will be studied through a series of questions, to which the archives will try to give answers. The originality of this research lies in the fact that the question of the industrialisation is analysed under aspects which differ from those usually covered by Luxembourgish historiography, especially the impact of municipal finances on the relationship between local authorities and ironmasters. The study concludes that the rhythm of industrialisation of a municipality and the management of related impacts varies according to the degree of interaction between municipal authorities and ironmasters, which depends on a certain number of factors: the state of municipal finances following the settlement of steel factories, the nationality of the leaders of the factories, the weight of employers' paternalism, and finally, the socio-professional composition of the municipal bodies. The study also shows that the governmental authorities are reluctant to intervene in the relationship between municipal bodies and ironmasters, for fear they could offend Luxembourg's main providers of wealth. The study also shows that the government's involvement remains limited to specific cases. [less ▲]

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See detailMean Values and Functional Equations
Dascal, Judita UL

Doctoral thesis (2012)

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See detailThe territorial link as a condition to create a permanent establishment
Schaffner, Jean UL

Doctoral thesis (2012)

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See detailLow-energy Secondary Ion Mass Spectrometry: Investigation of buried interfaces in multi-layer organic thin films
Ngo, Khanh Quyen UL

Doctoral thesis (2012)

Recently, the application of conjugated organic compounds increases significantly in optoelectronic devices. The main performances of these devices such as charge and energy transport, operational ... [more ▼]

Recently, the application of conjugated organic compounds increases significantly in optoelectronic devices. The main performances of these devices such as charge and energy transport, operational lifetime and energy conversion efficiency depend strongly on the doping and the interface structure. Therefore, in this project we develop dynamic SIMS analysis conditions using low energy primary ion beam to analyse multi-layered samples used in organic optoelectronic devices. The objective of this thesis is to study the different artefacts and mechanisms, which may arise in the low-energy depth profiling of organic materials and to optimize the SIMS conditions for interface resolution. For the objectives, in chapter I and II, a general introduction about the organic molecules, the fabrication techniques as well as fundamental aspects of the SIMS technique and the analysis conditions are presented. In chapter III, a study of the fragmentation of different organic films during sub-keV bombardment is performed. The typical secondary ions of different organic molecule are identified and chosen for depth profiling. Chapter IV is a study about air-contact induced topography change on Cs+ sputtered surface. This is useful to avoid artefacts when characterizing the Cs+ sputtered surfaces by AFM or by other techniques. The ability of low-energy SIMS to characterize the metal/organics interfaces is investigated in chapter V and VI. Chapter V is about the SIMS depth resolution and sputter-induced surface roughness studied on a series of metal – organic layered samples. In chapter VI, the diffusion of metal into organic layer seen in SIMS depth profiles is characterized. [less ▲]

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See detailEmpirical Essays on Commodity Prices
Carpantier, Jean-Francois UL

Doctoral thesis (2012)

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See detailHistorische Geographie Phnom Penhs: Stadtentwicklung zwischen Planung und spontaner Ordnung, 1860-2010
Kolnberger, Thomas UL

Doctoral thesis (2012)

This thesis offers an analysis of Phnom Penh`s urban space in the longue durée, examining the concurrence of planning ‘from above’ and spontaneous order ‘from below’. By privileging the spatial point of ... [more ▼]

This thesis offers an analysis of Phnom Penh`s urban space in the longue durée, examining the concurrence of planning ‘from above’ and spontaneous order ‘from below’. By privileging the spatial point of view, the investigation attempts to overcome the false dichotomy of ‘planned’ versus ’unplanned’ order in urban development. Using Phnom Penh as a case-study for city development in a pre-colonial, colonial and post-colonial context, the production of space as a social process is identified in two ways: first ‘literally’ by a historical-critical analysis of the chronological course of urban construction based on archival records and, second, ‘visually’ by scrutinizing master and city plans as well as photographical veduta (i.e. aerial and satellite photography, photos of cityscapes or other relevant urban situations) of past and present. Structure: The thesis consists of five chapters (A-E), organised in three parts (Erster, Zweiter, Dritter Teil). After an introductory chapter (A), dealing with the research topic in general, the first part (chapters B-C) of the investigation follows a morphological approach. It presents the local building and historical town planning traditions of the lower Mekong region in pre-historical times onwards, analysing the pre-colonial times, followed by the French colonial era. The second part (chapter D) deals with the local development during the Cold War, subdivided in two distinct phases: the independence of decolonization (1954-1970s) and the civil war and Khmer Rouge-time (1970s-1989). The third part (chapter E) specifically examines the situation after the fall of the Pol Pot-regime: the ‘new’ independence after the Vietnamese and UN-intervention. The appendix is ex-tensive, but ‘tailor-made’ providing datasheets and detailed background information, e.g. on climate, to allow the interested reader to further deepen some topics. Research questions: Three questions run like a thread through the thesis as recurrent themes: (1) To what extent is the city development a ‘planned’ or ‘unplanned’ process, and which interactions between the two dynamics can be discerned? (2) What power politics from ‘above’ and ‘below’ make up the political economy of space? (3) What kind of continuities and discontinuities can be identified as persistency and change in the cityscape? Social engineering projects ‘from above’ (by diverse governments and power groups) have continuously been challenged, partly evaded and actively counteracted in their own interest ‘from below’ (by the ‘common man’, informal settlers), thus characterizing the social space of Phnom Penh as a ‘common field of action’ (gemeinsamer Aktionsraum). Since colonial times, the physical engineering of space (aligning the urban morphology into a grid-pattern; dividing the city space in [marketable] plots) has been both a transfer from abroad and a quasi-continuity of local proceedings in urban construction. From thispoint of view the transformation of the royal residence-town into a colonial city and the subsequent change from a colonial administration centre of lesser importance within the French Indochinese Union to a dominant capital city of an independent state are revealing a complex pattern of competing interests of all ‘spatial’ actors: rich and poor, mighty and weak, officials and individuals, military and civilian, singles and families. Attempts of social engineering by the use of the built environment and the imple-mentation of physical change to it, however, have also been producing ‘frictions’ (Friktionen) ever since. As result, a third degree of order, besides the intended and non-intended, has emerged: epiphenomena (Epiphänomene; Phänomene der dritten Art). The self-organisation through the ‘auto-agglomeration’ of businesses during the resettlement process after the fall of the Khmer Rouge is examined as an example for this kind of spatial (re)ordering. Concluding the longue durée-analysis of Phnom Penh, the spatial distribution is analysed and presented in full detail as economy of espionage and imitation in chapter (E). Methodology: In order to achieve the primary object of this undertaking to write a historical geography of the production of Phnom Penh’s space, a multidisciplinary approach was necessary, combining historical-critical analysis (Historisch-kritische Methode); geography (spatial analysis, urban morphology) and sociology (questionnaires and interviews, ‘observing participation’). The very heterogeneous mixture of archival sources and newly generated data that informs this study required a reflexive grounded theory. [less ▲]

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See detailDependency of network traffic monitoring
Wang, Shaonan UL

Doctoral thesis (2012)

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See detailSecurity and Network monitoring based on Internet flow measurements
Wagner, Cynthia UL

Doctoral thesis (2012)

Today's networks face continuously arising new threats, making analysis of network data for the detection of anomalies in current operational networks essential. Network operators have to deal with the ... [more ▼]

Today's networks face continuously arising new threats, making analysis of network data for the detection of anomalies in current operational networks essential. Network operators have to deal with the analysis of huge volumes of data. To counter this main issue, dealing with IP flows (also known as Netflows) records is common in network management. However in modern networks, even Netflow records still represent a high volume of data. Interest in traffic classification as well as attack and anomaly detection in network monitoring and security related activities has become very strong. This thesis addresses the topic of Netflow record analysis by introducing simple mechanisms for the evaluation of large quantities of data. The mechanisms are based on spatially aggregated Netflow records. These records are evaluated by the use of a kernel function. This similarity function analyses aggregated data on quantitative and topological pattern changes. By the use of machine learning techniques the aim is to use the aggregated data and classify it into benign traffic and anomalies. Besides the detection of anomalies in network traffic, traffic is analyzed from the perspective of an attacker and a network operator by using a game-theoretical model in order to define strategies for attack and defence. To extend the evaluation models, information from the application layer has been analyzed. An occurring problem with application flows is that in some cases, network flows cannot be clearly attributed to sessions or users, as for example in anonymous overlay networks. A model for the attribution of flows to sessions or users has been defined and related to this, the behaviour of attack and defence mechanisms is studied in the framework of a game. [less ▲]

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See detailSensor Fusion Combining 3-D and 2-D for Depth Data Enhancement
Garcia Becerro, Frederic UL

Doctoral thesis (2012)

Time-of-Flight (ToF) cameras are known to be cost-efficient 3-D sensing systems capable of providing full scene depth information at a high frame rate. Among many other advantages, ToF cameras are able to ... [more ▼]

Time-of-Flight (ToF) cameras are known to be cost-efficient 3-D sensing systems capable of providing full scene depth information at a high frame rate. Among many other advantages, ToF cameras are able to provide distance information regardless of the illumination conditions and with no texture dependency, which makes them very suitable for computer vision and robotic applications where reliable distance measurements are required. However, the resolution of the given depth maps is far below the resolution given by standard 2-D video cameras which, indeed, restricts the use of ToF cameras in real applications such as those for safety and surveillance. In this thesis, we therefore investigate how to enhance the resolution of ToF data and how to reduce the noise level within distance measurements. To that end, we propose to combine 2-D and ToF data using a low-level data fusion approach that enhances the low-resolution depth maps up to the same resolution as their corresponding 2-D images. [less ▲]

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See detailPhoto-Hall measurements on CuInSe2
Altenhofer, Georg UL

Doctoral thesis (2012)

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See detailAssessment of implicit and explicit algorithms in numerical simulation of granular matter
Samiei, Kasra UL

Doctoral thesis (2012)

The objectives of this dissertation are to investigate and demonstrate the potentials of implicit integration methods in predicting the dynamics of granular media and to describe the granular dynamics on ... [more ▼]

The objectives of this dissertation are to investigate and demonstrate the potentials of implicit integration methods in predicting the dynamics of granular media and to describe the granular dynamics on forward and backward acting grates by discrete element method. Traditionally, explicit integration methods are employed within the context of Discrete Element Method. Generally, explicit equations are simpler to solve than the implicit ones but they require a small time step to be utilized. In this study, an implicit Numerov integration scheme is employed to integrate the equations of motion. The implicit method is verified in different test cases starting from simple cases to more complicated cases including hundreds of particles. Comparing the results with the results of the explicit method, it is shown that the implicit method exhibits a distinguished advantage only at very large time steps. Taking into account the overhead of solving non-linear equations at each time step, it is concluded that implicit methods are computationally too expensive for their limited gains. Addressing the second objective of this study, the residence time distribution of granular particles on forward and backward acting grates are numerically predicted. Very good agreement between the predictions and the available experimental results is achieved. It can be concluded that the Discrete Element Method is highly capable of predicting the dynamics of solid fuel particles on grate systems. Future work shall include coupling of the method with computational fluid dynamics in order to account for thermal conversion of the fuel particles. [less ▲]

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See detailJudgement aggregation for multiagent systems
Slavkovik, Marija UL

Doctoral thesis (2012)

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See detailInvestment Fund Governance: An empirical investigation of Luxembourg UCITS
Hazenberg, Jan UL

Doctoral thesis (2012)

Investment funds potentially suffer from the conflict of interest between investors and fund management companies. Fund boards could help mitigate this conflict. In Luxembourg, the second largest fund ... [more ▼]

Investment funds potentially suffer from the conflict of interest between investors and fund management companies. Fund boards could help mitigate this conflict. In Luxembourg, the second largest fund domicile globally, fund boards are not required to have independent board members. Nevertheless, many firms have independent board members on their fund boards. The research question investigated is whether or not boards with (more) independent board members are more effective for investors, leading to lower costs (Total Expense Ratio) and/or better investment performance (Carhart alpha). With a multiple regression analysis, the relationship is analysed of the level of fund costs and performance with the funds’ governance characteristics, controlling for various other promoter, umbrella and fund variables. This approach did not provide consistent evidence that independent governance contributes to lower costs or better performance. The survey among board members showed that irrespective of whether or not the boards have independent board members, fund boards in the sample prioritise risk management and compliance aspects. Lower priority is given to investment performance and costs. Both for the level of costs and performance, whether or not the promoter had affiliated distribution in the group seems to be a more important driver than the composition of the fund board. [less ▲]

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See detailCuInSe2 thin film solar cells synthesised from electrodeposited binary selenide precursors
Fischer, Johannes UL

Doctoral thesis (2012)

The box must contain a summary in a maximum of 1,700 characters, spaces included. The fabrication of a CuInSe2 thin film solar cell from an electrodeposited precursor stack consisting of indium selenide ... [more ▼]

The box must contain a summary in a maximum of 1,700 characters, spaces included. The fabrication of a CuInSe2 thin film solar cell from an electrodeposited precursor stack consisting of indium selenide and copper selenide layers is demonstrated. A best conversion efficiency of 5.5% was achieved, a higher efficiency than previously reported in literature. The thesis focuses on three main parts: (i) electrochemistry of indium selenide: The incorporation of indium in the deposit requires the presence of selenium species. The obtained film consists of both amorphous In2Se3 and elemental Se. The Se/In ratio depends on the applied potential, although the deposition is mass transport controlled limited by the selenium ion concentration. The potential controls the balance of reduction kinetics between the In2Se3 and elemental Se and both compete for the same intermediate selenium species. (ii) phase reactions during annealing: The small interface area between the electrodeposited indium selenide and the copper selenide layer slows down the interdiffusion during the annealing process. Therefore the temperature required to react the precursor is higher than reported for similar stacks in literature. Copper selenide is retained at the surface for a longer time during the annealing process, where it undergoes the transitions CuSe2 => CuSe => Cu2Se. (iii) loss mechanisms in the solar cell: The highest solar cell conversion efficiency was obtained from a stoichiometric precursor compromising the advantages and disadvantages of Cu-poor and Cu-rich growth. The Cu-poor grown absorber showed a reverse pn-junction at the backside due to an incomplete reaction of the stack. The efficiency of the Cu-rich grown solar cell was limited by high interface recombination. [less ▲]

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See detailKesterite Equilibrium Reaction and the Discrimination of Secondary Phases from Cu2ZnSnS4
Berg, Dominik UL

Doctoral thesis (2012)

Kesterite (Cu2ZnSnS4 - CZTS) based thin films are of increasing interest in the field of thin film photovoltaics. In recent developments, mixed S-Se kesterite devices have shown power conversion ... [more ▼]

Kesterite (Cu2ZnSnS4 - CZTS) based thin films are of increasing interest in the field of thin film photovoltaics. In recent developments, mixed S-Se kesterite devices have shown power conversion efficiencies of more than 10 %, but yet a major challenge is the fabrication of single phase kesterite material for high quality solar cells. In this thesis, two aspects of the growth of single phase kesterite films have been studied in more detail. The first part focuses on the identification of secondary phases (e.g. ZnS and Cu2SnS3) and their discrimination from CZTS. Hereby, grazing incidence X-ray diffraction and Raman spectroscopy measurements were used to quantitatively identify secondary phases on a mixed, CZTS containing sample. Experimental results show, that in a measurement series a minimum of 7 % of ZnS or 28 % of Cu2SnS3 must be present in order to be identifiable. The second part of this thesis focuses on finding a way to grow absorber layers for high quality CZTS thin film solar cells. Hereby, it could be shown that it is important for the quality of the absorber layer to keep the equilibrium position of the formation reaction of CZTS close to the CZTS side throughout the annealing. To achieve this, it is suggested to anneal the precursors in the presence of sulfur and tin sulfide. A study showed that this novel annealing strategy helped to improve the power conversion efficiency of a device based on a vapor-deposited precursor from 0 % to 6.1 %. Within this context, a novel route to form CZTS from a simplified, only Cu and Zn containing precursor, has been introduced and a model of the formation reaction of CZTS from this simplified precursor has been suggested. [less ▲]

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See detailContribution à la résolution de la conjecture S-adique
Leroy, Julien UL

Doctoral thesis (2012)

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See detailSocial network analysis over dynamic graphs and application to urban mobile ad hoc networks
Herbiet, Guillaume-Jean UL

Doctoral thesis (2012)

Wireless mobile ad hoc networks (MANET) are composed of mobile communicating devices that self-organize to ubiquitously exchange information over the air. Envisioned applications for such networks cover ... [more ▼]

Wireless mobile ad hoc networks (MANET) are composed of mobile communicating devices that self-organize to ubiquitously exchange information over the air. Envisioned applications for such networks cover disaster relief situations, battlefield deployment and more generally any use-case that makes the deployment of wired or infrastructure-based networks too costly or simply unsuitable. Lately, new applications for MANETs are developing in the urban environment, namely mobile social networks and vehicular ad hoc networks. Despite this large spectrum of possible applications and the large number of wireless-capable devices available today, mobile ad hoc networks remain confidential. One important reason is the lack of reliability of wireless communications, especially on long path. In this thesis, we propose to cope with this problem by creating virtual structures that will group together limited set of users that are densely and reliably connected in order to favor the dynamic and robust exchange of information. Our proposal uses the concept of community, that first appeared in social network analysis. After reviewing the main concepts taken from this branch of graph theory and justifying the application by underlining the specificities of MANETs in the urban context, we formally present our contribution, based on epidemic propagation of community labels. Then we exhibit its applications on concrete communication systems and how it can benefit more generally to improve the management of wireless ad hoc networks topology. [less ▲]

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See detailBuild Operate and Transfer (BOT) Projects - Contribution à l’étude juridique d’une modalité de partenariat public-privé à la lumière de l'approche Law and Economics
Tatofie, Roger UL

Doctoral thesis (2012)

Infrastructures and utility services are fundamental to economic and human development. Therefore, investment in these areas is critical to economic growth, quality of life, poverty reduction, access to ... [more ▼]

Infrastructures and utility services are fundamental to economic and human development. Therefore, investment in these areas is critical to economic growth, quality of life, poverty reduction, access to education and health care and achieving many of the objectives of a robust economy. Yet, whereas the public sector provides the vast majority of financing for infrastructure services, investments have not matched demand, public funds or borrowings are insufficient and governments are seeking methods to improve the efficient procurement of infrastructure services. Private sector participation in public projects is increasingly becoming a reliable source of investment and, as far as public policies are concerned, an unavoidable feature of our contemporary society even in “core public policies” (for example, greater responsibility for financial planning and welfare provision is being increasingly shifted by the states to the private sector and individuals). In the area of infrastructures and utility services, Public-Private Partnerships (PPP), despite some of their challenging features, are one of the tools in a policy maker’s arsenal which help to increase investment in infrastructure services and improve its efficiency. One of the main advantages of PPP is that, unlike privatization, the government retains strategic control over the project and the ownership of its assets. PPP offers multiple options or structures. As shown in this study, Build, Operate and Transfer (BOT) Projects are one of the numerous options offered by PPP. In a BOT project, a private entity is given the right to design, finance, build and operate for a defined period (“concession period”) a facility that would normally be built by the government. The operation of the project generates revenues and the private entity uses these revenues to service debt and provide the investors with a return. At the end of the defined period, the private entity turns over the facility to the government. In practice, a number of parties - each with sometimes different interests, levels of sophistication and available resources - will be involved in a BOT project: the grantor/host government, the sponsors (generally throughout the project company), the lenders and the contractors (construction contractor, operator, offtake purchaser, input supplier) and the BOT approach can be used for different and various projects (power generation, water treatment, airports, roads, tunnels, bridges…) and, hence, has many variants such as BOO (Build, Own and Operate), BOOT (Build, Own, Operate and Transfer), BTO (Build, Transfer and Operate) etc. The BOT approach is not, however, a panacea for the host government and may involve some disadvantages. In effect, BOT projects are highly complex (from both financial and legal points of view), commercially driven projects, requiring extensive documentation and negotiation and a suitable political, legal, regulatory and economic environment. Nevertheless, it has many potential advantages and still is a viable alternative in most countries to the more traditional approach to public projects. For policy makers, practitioners, investors and, above all, the targeted populations to fully benefit from these advantages, the BOT concept must however be clarified and lifted from the fuzziness in which it has been plunged by commentators. There has actually been a dual view of the BOT concept: On one hand, some commentators consider the BOT concept as a simple public procurement modality, comparable to the concession model, and hence to be subjected to classical public law concepts, practices and requirements such as the public services, public ownership and standards and rules of public budget and accountancy. On the other hand, some other commentators view the BOT concept as a modality of project financing which should therefore be subjected to the requirements of profitability and risks sharing. However, if this dual view presents the BOT concept under two specialized lenses and tends to protect certain interests - i.e. public interests and private interests - it is in fact non satisfactory conceptually as well as practically. In fact, this dual view describes a unique reality which an economic cooperation characterized by harmony and conflict, change and equilibrium. The ambition and objective of this study is therefore to give a full understanding of the BOT concept and to shed light on its originality and its unity. The BOT concept is therefore considered as an economic cooperation device, demonstration made in this study principally under the light of law and economics approach. In effect, structuring a BOT project requires the use of (free) market tools (especially economic and financial tools), which render the law and economic approach perfectly suitable to analyze the BOT concept and reveal its rationality and coherence. Hence, the use of the (strategic) game theory to underline the mutual gains resulting from the cooperation between partners involved in a BOT project; the use of the incomplete contract theory to explain the special care needed to design the BOT contract and its possible adjustments; the use of the theory of the firm and financial contracting to explain the functions of coordination and integration of the project company; or also the use of the public choice theory to analyze the notion of general interest which has led to the conclusion that BOT projects are a combination of public and private interests in order to achieve optimality and mutual gains. More generally however, this study has adopted a pragmatic view, using various and different methods, because analyzing the relationships between State and market requires taking into account a great range of fields, considerations and expertise. This pragmatic approach suggested the study be carried out as a genealogic enterprise, such a process allowing a criticizing stance and a formulation of a new and global theoretical frame presenting the relics and the transformations of the current (dual) views of the BOT concept from which its originality and its unity derive. This study has therefore shown that the contractual, structural, economic and financial interdependence of the BOT project makes it an undeniable economic cooperation device. The BOT concept therefore acquires a conceptual unity which reinforces its functional and practical nature and adds a guarantee of legal security to its use. Besides, it has also been demonstrated that BOT is a signaling and an accountability tool for the partners involved in those operations. Ultimately, as regard to public projects, the BOT concept introduces a bit of rationality in equity and humanity to efficiency. [less ▲]

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See detailDesign and Modeling of Privacy-Friendly Reputation
Schiffner, Stefan UL

Doctoral thesis (2012)

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See detailViral regulation of nutrient assimilation by algae and prokaryotes
Sheik, Abdul UL

Doctoral thesis (2012)

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See detailSuccess and well-being of young persons in Switzerland
Samuel, Robin UL

Doctoral thesis (2012)

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See detailSociality and Self-Organisation in Next-Generation Distributed Environments
Botev, Jean UL

Doctoral thesis (2011)

The proliferation of computationally powerful, interconnected devices entails a new generation of networked applications and social utilities characterized by a strong growth in scale and dynamics.<br ... [more ▼]

The proliferation of computationally powerful, interconnected devices entails a new generation of networked applications and social utilities characterized by a strong growth in scale and dynamics.<br />Distributed virtual environments constitute a privileged example, involving a high degree of interactivity as well as tightened constraints and requirements. As a response to these issues, this dissertation explores and substantiates sociality as a fundamental principle both in and for the design of such systems.<br />A specialized, dual peer-to-peer architecture is introduced, combining a highly-structured backbone overlay with a loosely-structured geometric client overlay synergistically complementing each other. To enable a global-scale, single-instanced environment, it is imperative to include as many client-side resources as possible and unburden the backbone. The focus of this dissertation therefore lies upon the latter, geometric overlay.<br />By taking an interdisciplinary perspective and leveraging different aspects of sociality, a series of self-organized approaches addressing major problem areas are proposed: a collaborative filtering mechanism for the handling of information overload created from the soaring amounts of users and objects; a confidentiality framework for the protection of sensitive data more likely exposed due to an increased interactivity; and two resource allocation schemes for fairly distributing surplus capacities in the face of critical regional surges.<br />Detailed evaluations show that these decentralized algorithms operate robustly and effectively, while yielding well-converging results in comparison to optimal, global-knowledge scenarios. [less ▲]

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See detailThe reading and mathematics performance of language-minority children in Luxembourg, Serbia and Europe: Is school instruction in their mother tongue important?
Aleksic, Gabrijela UL

Doctoral thesis (2011)

In order to explore the complex reality of the importance of mother tongue for the reading and mathematics performance of language-minority children, I conducted three studies. The aims of the studies ... [more ▼]

In order to explore the complex reality of the importance of mother tongue for the reading and mathematics performance of language-minority children, I conducted three studies. The aims of the studies were threefold: a) to investigate the reading and mathematics performance of language-minority preschool children in Luxembourg and Serbia (Study I). b) to identify predictors for early reading performance in the majority language (Study II). c) to conduct a meta-analysis on the effectiveness of bilingual as opposed to submersion programs in promoting the academic achievement of language-minority children (Study III). All three studies were theoretically anchored in the psycholinguistic constructs of Jim Cummins, as in OECD (2006, 2010) results reporting the underachievement of minority students in Europe. On the strength of this theory and drawing from empirical evidence, I propose three hypotheses: a) Hypothesis 1: language-minority children will score significantly lower in both reading and mathematics than language-majority children (Study I). b) Hypothesis 2: the significant predictors for early reading will be whether the test was conducted in the child’s mother tongue or not, the child’s gender, the level of education of the child’s parents, the child’s range of vocabulary, the child’s phonological awareness, competence in mathematics and the child’s behaviour (Study II). c) Hypothesis 3: bilingual education programs that include language-minority children’s mother tongue in school instruction are superior to submersion programs that exclude the children’s mother tongue in school instruction in promoting their academic achievement (Study III). International data show that those language-minority students who do not speak the school language of instruction at home are, on average, one year behind their native peers (Stanat & Christensen, 2007). This gap hampers student’s academic achievement, which in turn restrict the student’s opportunities in the labour market. The purpose of Study I was, therefore, to investigate the performance in reading and mathematics of language-minority preschool children in Luxembourg (N=174) and Serbia (N=159). MANOVA results showed that in Luxembourg, Portuguese children performed significantly lower than both native Luxembourgish children and other minority children. However, with regard to the testing of vocabulary and rhyming words - sections of the test which are evidently loaded with Luxembourgish-specific words - Portuguese and other minority children scored significantly lower than Luxembourgish children. I speculate that language of instruction can be one of the reasons for their possible low performance. In Serbia, Roma performed significantly lower than Hungarians, Serbs and other minority children. This finding may suggest that there are other variables, such as the socio-economic backgrounds of the children that may contribute to the low performance of both the Portuguese and Roma as language-minority groups at school. Thus, Hypothesis 1 is partly confirmed. Reading skills provide a crucial foundation for children’s success at school (Lonigan, Burgess, & Anthony, 2000) and beyond (Miles & Stipek, 2006). Good progress in reading and mathematics in the earliest years constitute the most important factors which continue to play a role at the age of 11 (Tymms, Jones, Albone, & Henderson, 2007). Study II, involving preschool children from Serbia (N=159) and Luxembourg (N=174), examines the predictive value of the child’s gender, the child’s mother tongue, the level of education of the child’s parents, the child’s range of vocabulary, the child’s phonological awareness, competence in mathematics and the child’s behaviour for early reading skills. For the Serbian sample, multilevel models showed that whether the test was administered in the child’s mother tongue at the age of 5 or not and competence in mathematics were the most significant predictors for early reading at the age of 7 after controlling for age, gender, vocabulary, phonics and behaviour. For the Luxembourgish sample, gender, vocabulary, phonological awareness and competence in mathematics at the age of 5 were significant predictors for reading at the same age, after controlling for age and the mother tongue. The level of parental education in the Serbian sample and the children’s behaviour in both samples proved not to be significant. Thus, Hypothesis 2 is partly confirmed. The education of language-minority children becomes increasingly important in today’s society. Five previous meta-analyses investigated the effectiveness of bilingual programs in promoting academic achievement of language-minority children in the United States. The present meta-analysis (Study III) investigates seven European studies on the topic. Results indicate a small positive effect (g=0.23) for bilingual over submersion programs on the academic achievement of language-minority children (also see Rolstad, Mahoney & Glass, 2005, 2008). This meta-analysis, therefore, appears to support bilingual education in Europe, the education that includes the mother tongue of language-minority children in the school instruction. Thus, Hypothesis 3 is confirmed. However, the results are restricted due to the small number of studies. More published studies in bilingual education in Europe are needed. [less ▲]

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See detailAnalysis of resynchronization mechanisms of stream ciphers
Priemuth-Schmid, Deike UL

Doctoral thesis (2011)

Stream ciphers are cryptographic primitives belonging to symmetric key cryptography to ensure data confidentiality of messages sent through an insecure communication channel. This thesis presents attacks ... [more ▼]

Stream ciphers are cryptographic primitives belonging to symmetric key cryptography to ensure data confidentiality of messages sent through an insecure communication channel. This thesis presents attacks on several stream ciphers, especially against their initialization methods. The first targets are the stream ciphers Salsa20 and Trivium. For both ciphers slid pairs are described. Salsa20 can be distinguished from a random function using only the slid pair relation. When a slid pair is given for Salsa20 both secret keys can be recovered immediately if the nonces and counters are known. Also an efficient search for a hidden slid pair in a large list of ciphertexts is shown. The efficiency of the birthday attack can be increased twice using slid pairs. For the cipher Trivium a large related-key class which produces identical keystreams up to a shift is presented. Then the resynchronization mechanism of the stream ciphers SNOW 3G and SNOW 2.0 is analyzed. Both ciphers are simplified by replacing all additions modulo 32 with XORs. A known IV key-recovery attack is presented for SNOW 3G and SNOW 2.0 where both ciphers have no feedback from the FSM. This attack works for any amount of initialization clocks. Then in both ciphers the feedback from the FSM is restored and the number of 33 initialization clocks is reduced. Chosen IV key-recovery attacks on SNOW 3G with 12 to 16 initialization clocks and SNOW 2.0 with 12 to 18 initialization clocks are shown. In a similar way versions of the stream cipher K2 are attacked. This cipher is simplified by replacing all additions modulo 32 with XORs as well. Chosen IV key-recovery attacks on versions with reduced initialization clocks from five to seven out of 24 are presented. For the version with seven initialization clocks also a chosen IV distinguishing attack is shown. The last part deals with a linear key-IV setup and known feedback polynomials of the shrinking generator. It is shown that this linear initialization results in a very weak cipher as only a few known IVs are required to recover the secret key. The original design of the shrinking generator does not include any initialization method so the initial state was assumed to be the secret key. [less ▲]

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See detailDe Bonn à Berlin : territoires, mémoires et échelles du politique
Laporte, Antoine UL

Doctoral thesis (2011)

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See detailAn Alternative approach to extreme-risk management
Laube, Falk UL

Doctoral thesis (2011)

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See detailInhomogeneities of epitaxial chalcopyrites studied by photoluminescence
Larsen, Jes K. UL

Doctoral thesis (2011)

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See detailLipid and Immune Functions of the Liver X Receptors in Human Macrophages
Diwo, Janine UL

Doctoral thesis (2011)

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See detailParallel hybrid optimization methods for permutation based problems
Mehdi, Malika UL

Doctoral thesis (2011)

Solving efficiently large benchmarks of NP-hard permutation-based problems requires the development of hybrid methods combining different classes of optimization algorithms. The key challenge here is how ... [more ▼]

Solving efficiently large benchmarks of NP-hard permutation-based problems requires the development of hybrid methods combining different classes of optimization algorithms. The key challenge here is how to find connections between the divergent search strategies used in each class of methods in order to build efficient hybridization strategies. Genetic algorithms (GAs) are very popular population-based metaheuristics based on stochastic evolutionary operators. The hybridization of GAs with tree-based exact methods such as Branch-and-Bound is a promising research trend. B&B algorithms are based on an implicit enumeration of the solution space represented as a tree. Our hybridization approach consists in providing a common solution and search space coding and associated search operators enabling an efficient cooperation between the two methods. The tree-based representation of the solution space is traditionally used in B&B algorithms to enumerate the solutions of the problem at hand. In this thesis, this special representation is adapted to metaheuristics. The encoding of permutations as natural numbers, which refer to their lexicographic enumeration in the tree, is proposed as a new way to represent the solution space of permutation problems in metaheuristics. Mapping functions between the two representations and special search operators are defined for general permutation problems. This common representation allows the design of efficient cooperation strategies between GAs and B&B algorithms. The proposed hybrid schemes have been parallelized and validated on standard benchmarks of the 3D quadratic assignment problem (Q3AP) using the computational grid Grid5000. [less ▲]

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See detailThe principle of equality of arms in international criminal justice
Bengüsu, Özge UL

Doctoral thesis (2011)

Detailed reference viewed: 45 (8 UL)
See detailLie-admissible structures on Witt type algebras and automorphic algebras
Chopp, Mikael UL

Doctoral thesis (2011)

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See detailApplication of the Storing Matter technique to organic samples: fundamentals, applications, and evaluation of the analytical potential
Becker, Nora UL

Doctoral thesis (2011)

SIMS is a sensitive surface analysis method that is commonly used for a wide range of applications in various domains. Its major drawback is the so-called matrix effect, which is due to a change of the ... [more ▼]

SIMS is a sensitive surface analysis method that is commonly used for a wide range of applications in various domains. Its major drawback is the so-called matrix effect, which is due to a change of the ionization efficiency as a function of the chemical environment of the considered atom or molecule and which makes quantitative analysis very difficult. The Storing Matter technique was developed in order to circumvent the matrix effect while still keeping an excellent sensitivity: in a first step, the sample surface is sputtered by an ion beam and the emitted matter is deposited at sub-monolayer level onto a dedicated collector. Then the collector is transferred under UHV conditions to a SIMS instrument where the deposit is analyzed. If the deposit coverage is in the sub-monolayer range, all the deposited particles are surrounded by the same matrix, i.e. the collector material. The main goal of this work was the study and setup of experimental conditions for the application of the Storing Matter technique to organic samples. In this case, it is particularly important that molecular information is preserved. The key parameters of the technique were studied in detail and the optimal conditions with regard to high ionization efficiency and low fragmentation could be defined. [less ▲]

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See detailSecurity of RFID protocols
Van Deursen, Ton UL

Doctoral thesis (2011)

Radio-frequency identification (RFID) is a technology that uses radio waves to exchange data between RFID readers and tags. The low manufacturing costs and small size and the lack of need of a power ... [more ▼]

Radio-frequency identification (RFID) is a technology that uses radio waves to exchange data between RFID readers and tags. The low manufacturing costs and small size and the lack of need of a power source make RFID tags useful in many applications, but also impose a strong need for secure RFID protocols. The first part of this thesis considers the analysis of untraceability of RFID protocols. We start by designing a formal syntax and semantics for security protocols. We define untraceability as a property on the traces of a protocol. We find new untraceability flaws in a number of RFID protocols. Furthermore, we show that indistinguishability-based proof models are incomparable to unpredictability-based proof models. The second part of this thesis is concerned with authentication of RFID protocols. Authentication ensures that agents can not be impersonated. We categorize new authentication attacks into algebraic replay attacks, man-in-the-middle attacks, compositionality attacks, and cryptanalytic attacks. The third part of this thesis deals with formalizing ownership in RFID systems and related security properties. In dynamic environments where RFID tags are exchanged, sold, or traded, the owner of a tag may change. We define secure ownership, exclusive ownership, secure ownership transfer, and desynchronization resistance. The fourth part of this thesis describes the problem of recovering memory structures of systems. We define the carving problem as recovering the structure of the memory, based on an attributed dump set. We design and implement algorithms to find commonalities and dissimilarities and apply them to a deployed RFID system.   [less ▲]

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See detailHachage vers les courbes elliptiques et cryptanalyse de schémas RSA
Tibouchi, Mehdi UL

Doctoral thesis (2011)

This thesis consists of two independent parts, devoted to both aspects of cryptology: construction and analysis. Contributions to cryptography proper, on the one hand, address open questions in algebraic ... [more ▼]

This thesis consists of two independent parts, devoted to both aspects of cryptology: construction and analysis. Contributions to cryptography proper, on the one hand, address open questions in algebraic curve-based cryptography, particularly the problem of encoding and hashing to elliptic curves. We derive some quantitative results on curve-valued encoding functions, and give a satisfactory construction of hash functions based on those encodings, using a range of mathematical techniques from function field arithmetic, the algebraic geometry of curves and surfaces, and character sums. We also worked on a more implementation-related problem in elliptic curve cryptography, namely the construction of fast addition and doubling formulas. Our cryptanalytic work, on the other hand, focuses on RSA-based cryptosystems—mostly encryption and signature schemes. We have obtained and carried out new attacks on standardized padding schemes that remain in widespread use, including ISO/IEC 9796-2 for signatures and PKCS#1 v1.5 for encryption. We also propose new physical fault attacks on RSA signature schemes using the Chinese Remainder Theorem, and a stronger attack on RSA schemes relying on small hidden-order subgroups. The tools involved include index calculus, lattice reduction techniques and efficient arithmetic of large degree polynomials. [less ▲]

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See detailDesign and Implementation of a Reliable Distributed Energy Management System
Hoben, Ralf UL

Doctoral thesis (2011)

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See detailLe rapatriement prématuré: analyse des déterminants psychosociaux, de la qualité de vie, des compétences relatives à l'employabilité et des capacités à gérer des problèmes auprès des militaires des Forces canadiennes stationnés en Europe. De la conception à l'évaluation d'une intervention psychosociale pour le prévenir
Blackburn, Dave UL

Doctoral thesis (2011)

Introduction. Early repatriation of Canadian Forces personnel deployed to Europe, mainly to NATO, defines military members unable to complete their postings. This is a recent problem and its reoccurrence ... [more ▼]

Introduction. Early repatriation of Canadian Forces personnel deployed to Europe, mainly to NATO, defines military members unable to complete their postings. This is a recent problem and its reoccurrence and prohibitive costs have a psychological and social impact at individual, family and institutional levels and therefore, have become a research priority. This thesis includes a group of doctorate studies whose innovative character undoubtedly helps understand this phenomenon and the factors contributing to its persistence or continuity. Goals. 1) Identify the determining factors (personal, interpersonal, environmental, institutional and social) involved with early repatriation; 2) Analyze over a period of three months the connection between quality of life, employability skills and problem management capabilities; secondly, identify the links between psychological quality of life and the factors that are mentioned, as well as the sense of belonging and socio-demographic characteristics; 3) Develop a program of preventive psychosocial actions for CF members serving in Europe (Programme d’actions préventives psychosociales destiné aux militaires des FC affectés en Europe (PAPFCE)); 4) Assess, with a group of participants, the quality and usefulness of the different components involved in the psychosocial intervention program and analyze over a three month period, the relationship between quality of life, employability skills and problem management capabilities for one group of participants and two groups not participating in the program. Method. In order to reach our goals, 343 CF members were invited to participate in various investigations. 1) Comments from soldiers that repatriated to Canada were analyzed. 2) A questionnaire based on previously established scales, was built to measure quality of life, employability skills, ability to manage problems and sense of belonging for newcomers of summer 2009. 3) Creation of the PAPFCE was designed and submitted to the newcomers of summer 2010. 4) A data comparison was carried out between the non participating military members and those who participated in the psychosocial intervention. Furthermore, using an evaluation grid, military members subjected to psychosocial intervention were questioned about the usefulness and quality of the different parts of the program. Results. A total of 74 military members participated in the project (participation rate 22%). The participants were men (81.1%), average age of 41.8 years [from 23 years to 56 years], using English at home (59.5%) and reported living as married (81.1%). Their job profile is as follows: 20.7 years of service in the CF [from 5 years to 38 years], non commissioned officers (52.7%) and Germany as place of employment (54.1%). The main contributing factors to early repatriation are: 1) deficiencies in the military selection process and its application, 2) occurrence or development of psychosocial problems, 3) application of disciplinary or administrative actions (such as revealing psychosocial imbalance), 4) expectations that were unfulfilled by the posting. After the first three months of deployment, quality of life, employability skills and capability to manage problems have not changed. The military member’s psychological quality of life is positively associated with "physical" and "social" aspects, the extent of "acquisition of social support" and the "restructuring" of the capability to manage problems. A data comparison between military personnel who participated in the PAPFCE and the non participants neither confirms its effectiveness nor significant contribution. However, for most participants, the quality of components and their satisfaction with the program were positively assessed, although the program did not seem to be able to prevent the occurrence of psychosocial problems, major factors for premature repatriation. Conclusion. The analysis of the determining factors involved in the success or failure of a military posting to Europe has led to a better understanding of the complexity of the cultural and professional adjustment process necessary by the members and their families. This work provides site specific realities to reflect upon and possible intervention methods that can be adopted to improve the posting or deployment support and encourages a more critical observation of challenges and issues that may have an impact on the future of the CF. [less ▲]

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See detailResource-Aware routing in delay and disruption tolerant networks
Sandulescu, Gabriel UL

Doctoral thesis (2011)

In recent years a new class of networks, known as delay- and disruption-tolerant networks (DTNs), have emerged with applications in vehicular communications, emergency response and the military, to ... [more ▼]

In recent years a new class of networks, known as delay- and disruption-tolerant networks (DTNs), have emerged with applications in vehicular communications, emergency response and the military, to mention a few. This thesis studies the resource-aware routing problem in DTNs along four lines. First, the thesis presents the design and comparative evaluation of a delay-tolerant routing protocol (ORWAR) which optimises message transmission and bandwidth usage during opportunistic encounters. This is done through the estimation of contact duration between nodes, selection of the most suitable message to forward at any contact opportunity, and message differentiation. Second, the thesis proposes a hybrid scheme whereby opportunistic and infrastructure-based communication can be combined to overcome network partitions and packet losses. Collaboration between two networks characterised by different capacities, costs, and performance levels has been shown to be not only cost-effective, but also capable of increasing network survivability in the combined network. Third, it proposes and evaluates a mathematical model that can be used to compute the optimal level of redundancy and replication of a routing protocol as a function of message characteristics. Fourth, a holistic approach to resources is proposed, where variations in the spatial and temporal distribution of various resources can feed strategies to reduce resource consumption. Using estimates of vicinity resources, a routing protocol may not only use up fewer resources overall, but may also consume resources preferentially from nodes with higher resource levels, sparing whenever possible those with limited supplies. [less ▲]

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See detailPhysical Security of Cryptographic Algorithm Implementations
Kizhvatov, Ilya UL

Doctoral thesis (2011)

This thesis deals with physical attacks on implementations of cryptographic algorithms and countermeasures against these attacks. Physical attacks exploit properties of an implementation to recover secret ... [more ▼]

This thesis deals with physical attacks on implementations of cryptographic algorithms and countermeasures against these attacks. Physical attacks exploit properties of an implementation to recover secret cryptographic keys. Particularly vulnerable to physical attacks are embedded devices. In the area of side-channel analysis, this thesis addresses attacks that exploit observations of power consumption or electromagnetic leakage of the device and target symmetric cryptographic algorithms. First, this work proposes a new combination of two well-known attacks that is more efficient than each of the attacks individually. Second, this work studies attacks exploiting leakage induced by microprocessor cache mechanism, suggesting an algorithm that can recover the secret key in the presence of uncertainties in cache event detection from side-channel acquisitions. Third, practical side-channel attacks are discovered against the AES engine of the AVR XMEGA, a recent versatile microcontroller. In the area of fault analysis, this thesis extends existing attacks against the RSA digital signature algorithm implemented with the Chinese remainder theorem to a setting where parts of the signed message are unknown to the attacker. The new attacks are applicable in particular to several widely used standards in modern smart card applications. In the area of countermeasures, this work proposes a new algorithm for random delay generation in embedded software. The new algorithm is more efficient than the previously suggested algorithms since it introduces more uncertainty for the attacker with less performance overhead. The results presented in this thesis are practically validated in experiments with general-purpose 8-bit AVR and 32-bit ARM microcontrollers that are used in many embedded devices. [less ▲]

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See detailEnergieeffizienz neuer Schul-und Bürogebäude in Luxemburg basierend auf Verbrauchsdaten und Simulationen
Thewes, Andreas UL

Doctoral thesis (2011)

In Luxemburg, energy consumption in the building and housing sector has been significantly increasing over the last years. An assessment of the energy saving potential of buildings requires a ... [more ▼]

In Luxemburg, energy consumption in the building and housing sector has been significantly increasing over the last years. An assessment of the energy saving potential of buildings requires a comprehensive data basis with real consumption figures that are not yet available. One focus of this study was to create a priori a detailed energy consumption database for new “School and Administrative Buildings” for Luxembourg. These are both groups cover a major part of the building and housing sector in Luxembourg besides residential buildings. Based on the samples collected, it was able to expand the figures to the entire country using mathematical methods and the medium heat and electricity consumption of these two types of buildings could determined. After collecting some details about each object, it was able to analyze the influence of different parameters, such as building age, size, type, glass fraction etc., on energy consumption using multivariate statistical methods. A posteriori, the results from the database were verified using parameter studies to existing objects and one object still under construction. Based on this, important key parameters relevant for both energy savings and thermal comfort could be found. This knowledge are necessary to understand energy flows within buildings better and, based on this, to be able meeting the nearly zero energy buildings requirements as set out by the EU Directive in the years to come. As conclusion, the central-European climatic zone provides opportunities to design energy-saving office and school buildings (primary energy consumption < 100 kWh/m2a) without mechanical cooling and ventilation systems that still guarantee appropriate degrees of thermal comfort. Unfortunately, the real average primary energy consumption figures of new school (187 kWh/m2a) and office buildings (677 kWh/m2a) in Luxemburg are still significantly higher. [less ▲]

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See detailLa détresse financière des entreprises: trajectoire du déclin et traitement judiciaire du défaut
Fimayer, Agnès UL

Doctoral thesis (2011)

This thesis aims to evaluate the efficiency of bankruptcy laws on an ex ante and ex post point of view according to three criteria: their financial efficiency, their social efficiency and their ... [more ▼]

This thesis aims to evaluate the efficiency of bankruptcy laws on an ex ante and ex post point of view according to three criteria: their financial efficiency, their social efficiency and their macroeconomic coherence. First, we analyze the economic and financial path of default and its legal treatment in order to determine the potential costs induced by the social objectives (employment preservation) of French bankruptcy law in terms of recoveries for creditors. We find that the legal treatment of default is in France implemented in the spirit of the objectives defined and hierarchized by the law, and that the court undertakes measures in order to also protect financial interests; this result invalidates our hypothesis that these two objectives are incompatible. Subsequently, we adopt a Law and Finance approach in order to bind bankruptcy codes to national environments. We offer an appreciation of the macroeconomic degree of coherence of default, which is in our opinion an element of its efficiency. [less ▲]

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See detailZur Anwendung der statistischen Formanalyse
Giebel, Stefan UL

Doctoral thesis (2011)

In the following work we propose an introduction to Statistical Shape Analysis and adapt the procedures to three and four dimensional objects. Especially, in the case of four dimensional objects we show ... [more ▼]

In the following work we propose an introduction to Statistical Shape Analysis and adapt the procedures to three and four dimensional objects. Especially, in the case of four dimensional objects we show one possible approach of Dynamical Shape Analysis. In Shape Analysis we use parameters of the distribution as the mean shape, a representative shape of a group, to test the possibility of discriminating different kind of groups of objects. First-time we are using in the concept of Shape Analysis the variance. Furthermore we combine the Neural Networks with the Shape Analysis and also the tests used for discriminating groups with Answer Tree. To classify the objects well known procedures as Logistic Regression, Neural Networks, Discriminant Analysis and Answer Tree are used. For the application more than one hundred renal tumors in childhood, also more than one hundred electronic nose sensor data for different kind of odor quality and concentration as well as the behaviour of around fifty sexual serial murderer are measured and used. In all the disciplines a new approach in measurement of data is shown. The work shows furthermore, that all three fields Shape Analysis is applicable. The results of Shape Analysis and the classification afford the discrimination of different kind of objects. Shape Analysis could be one answer for classifying image data in the light of increasing image data. [less ▲]

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See detailSelf-Adaptive Honeypots Coercing and Assessing Attacker Behaviour
Wagener, Gerard UL

Doctoral thesis (2011)

Information security communities are always talking about "attackers" or "blackhats", but in reality very little is known about their skills. The idea of studying attacker behaviors was pioneered in the ... [more ▼]

Information security communities are always talking about "attackers" or "blackhats", but in reality very little is known about their skills. The idea of studying attacker behaviors was pioneered in the early nineties. In the last decade the number of attacks has increased exponentially and honeypots were introduced in order to gather information about attackers and to develop early-warning systems. Honeypots come in different flavors with respect to their interaction potential. A honeypot can be very restrictive, but this implies only a few interactions. However, if a honeypot is very tolerant, attackers can quickly achieve their goal. Choosing the best trade-off between attacker freedom and honeypot restrictions is challenging. In this dissertation, we address the issue of self-adaptive honeypots that can change their behavior and lure attackers into revealing as much information as possible about themselves. Rather than being allowed simply to carry out attacks, attackers are challenged by strategic interference from adaptive honeypots. The observation of the attackers' reactions is particularly interesting and, using derived measurable criteria, the attacker's skills and capabilities can be assessed by the honeypot operator. Attackers enter sequences of inputs on a compromised system which is generic enough to characterize most attacker behaviors. Based on these principles, we formally model the interactions of attackers with a compromised system. The key idea is to leverage game-theoretic concepts to define the configuration and reciprocal actions of high-interaction honeypots. We have also leveraged machine learning techniques for this task and have developed a honeypot that uses a variant of reinforcement learning in order to arrive at the best behavior when facing attackers. The honeypot is capable of adopting behavioral strategies that vary from blocking commands or returning erroneous messages, right up to insults that aim to irritate the intruder and serve as a reverse Turing Test distinguishing human attackers from machines. Our experimental results show that behavioral strategies are dependent on contextual parameters and can serve as advanced building blocks for intelligent honeypots. The knowledge obtained can be used either by the adaptive honeypots themselves or to reconfigure low-interaction honeypots. [less ▲]

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See detailRisk Management in the petrochemical industry - a game theoretic approach
Hansen, Michael UL

Doctoral thesis (2011)

The thesis studies risk management and the complex human interactions in the petrochemical industry using game theoretic methods. In a first step, the risk management problem is described as a ... [more ▼]

The thesis studies risk management and the complex human interactions in the petrochemical industry using game theoretic methods. In a first step, the risk management problem is described as a simultaneous inspection game, in which the management of a model petrochemical company makes a decision of safety rule enforcement and the worker faces a trade-off between not violating or violating these rules. Violating leads to a gain if rules are not enforced, and to a loss if enforced. In this simple model, comparative statics analyses show how increased punishment and increased management commitment increase safety standards in the company. The cost and benefit parameters of the analysis are adapted from the “real world”. In a second step, the risk management problem is described as an enhanced, sequential inspection game in which incident risks are considered. The equilibrium results are used to develop a graphical risk management tool, the “Petrochemical Organisation Risk Triangle” (PORT). The PORT demonstrates how an enhancement of safety culture in the industry decreases the risk of incident. Comparative statics analyses including the effects of technological progress, safety culture incentives, increased punishment, management commitment and external contractors are then discussed using the PORT. It is concluded that in improving a company’s safety culture, management commitment is more effective than increased punishment and that contractors are key players in achieving good safety performance. Finally, the thesis presents an economic cost and benefit analysis of a model company to quantify and evaluate current risk management practices based on industrial data. [less ▲]

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See detailDynamic modelling of ground antennas
Breyer, Laurent UL

Doctoral thesis (2011)

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See detailDas Verhältnis von Lebenswelt und Wissenschaft
Primc, Nadia UL

Doctoral thesis (2011)

The PhD thesis aims at the clarification of the relationship between our commonsense experience and the scientific explanation of the world around us. The sciences claim to provide knowledge of a special ... [more ▼]

The PhD thesis aims at the clarification of the relationship between our commonsense experience and the scientific explanation of the world around us. The sciences claim to provide knowledge of a special quality. The indication ‘scientifically proven’ for instance refers to the outstanding reliability of the findings and the verification procedures of the sciences. If this claim is not to be taken as an empty promise, it has to be shown wherein this particular quality of the scientific knowledge consists and in which way it differs from our ‘everyday’ knowledge. In conclusion, the thesis argues for the following view of the relationship between commonsense and scientific knowledge: Our everyday conceptions take their origin in the different practices that are pursued within our life-world. They are to be judged according their ability to back our everyday practices. The adequacy of these concepts does not reside in some correspondence to reality but in their appropriateness to the realisation of the different ends and practices that constitute our everyday business. The sciences have to be judged as well according their ability to back practices, namely the experimental and laboratory practices. The sciences are in addition subjected to the demand of a distinct and situation-invariant reproducibility of their results. For this purpose a standardisation of the scientific concepts is needed, which can rely on commonsense distinctions and concepts as its methodological starting point. As the particular quality of the sciences is located in this claim to distinctness and situation-invariance they cannot be regarded as per definition superior to our everyday knowledge. [less ▲]

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See detailPhotoluminescence measurements on solar cell materials: chalcopyrites and kesterites
Hones, Katja UL

Doctoral thesis (2011)

The chalcopyrite Cu(In,Ga)Se2 is by now an established semiconductor for thin film solar cells. Its electrical properties is governed by native defects as for example copper vacancies VCu. However despite ... [more ▼]

The chalcopyrite Cu(In,Ga)Se2 is by now an established semiconductor for thin film solar cells. Its electrical properties is governed by native defects as for example copper vacancies VCu. However despite the good efficiencies, not much is known about the chemical nature of the defects responsible for the doping. The symmetry of the defects might be one way to determine their chemical nature. The symmetry of the defects will be investigated in this Ph.D. thesis by polarisation dependent photoluminescence measurements on epitaxial CuInSe2 and CuGaSe2 samples and on a CuInSe2 crystal. One major concern in fabricating thin film solar cells from the chalcopyrite Cu(In,Ga)Se2 is the indium price. One possibility to overcome this drawback is to replace the group III element indium by isoelectrical substitution by more abundant elements like zinc and tin, from the second and fourth group of the periodic table. This leads from the chalcopyrite CuInSe2 to the kesterite Cu2ZnSnSe4. However, synthesizing a quaternary compound, additional secondary and ternary phases become an important issue. In this Ph.D. thesis photoluminescence and X-ray diffraction results will be presented and their strengths and limits in the identification of secondary and ternary phases will be discussed. As kesterite is expected to be, similar to the chalcopyrites, a natively doped semiconductor, the defects will play a crucial role for the device properties. Therefore, in the third part of the Ph.D. thesis photoluminescence results on defects in kesterites, measured on PVD grown kesterite samples, will be discussed. [less ▲]

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See detailJustice distributive: La question des brevets entre libéralisme et libertarisme
Lasalle, Matthieu UL

Doctoral thesis (2011)

The patent system as we know it is the only legal monopolistic system in the world. If collusion between different corporations in order to control the price of some ressources or produces is illegal ... [more ▼]

The patent system as we know it is the only legal monopolistic system in the world. If collusion between different corporations in order to control the price of some ressources or produces is illegal, there is almost nothing on the opposite side that exists in order to control the monopolistic system of the patents. When it comes to entertainment or inventions that aren't necessaries to our survival, the patent system, though failed, is not as problematic as when one owns for over 20 years the exclusivity on something that is vital to the survival of many. The knot of the problem is located between the patent that protects the creative minds from getting their ideas stolen and the problem that this protection causes by its monopolistic system. The aim of this work was to scrutinize deeper this complex problematic through a libertarian approach that claims that one shall dispose of what he wants the way he wants it and a rawlsian type of liberal approach that claims that we should consider patents as wealth that should be as well be subdued under some conditions to a form of redistribution as well. [less ▲]

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See detailInsider dealing and criminal law: les liaisons dangereuses?
Seredynska, Iwona UL

Doctoral thesis (2011)

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See detailEnhancing Project Robustness: A Risk Management Perspective
Gericke, Kilian UL

Doctoral thesis (2011)

Product development projects are challenging management tasks. The complexity and dynamics of requirements and goals, the novelty of design tasks, and polytely (striving for multiple goals) can all affect ... [more ▼]

Product development projects are challenging management tasks. The complexity and dynamics of requirements and goals, the novelty of design tasks, and polytely (striving for multiple goals) can all affect the course of a project. Frequent consequences of these boundary conditions are unwanted events which inhibit a successful project. This work shall provide a better understanding of project robustness, its barriers and enablers. To achieve this goal, the work was conducted following a research approach based on the Design Research Methodology proposed by Blessing and Chakrabarti. The work is based on a comprehensive literature study which resulted in a model describing the causality of project failures. The underlying assumption of the project failure causality model, that companies which treat risks preventively and proactively are more likely to successfully finish their product development projects than other companies, is examined by an analysis of data from 141 small and medium sized enterprises (SMEs). Design methodologies, project management, risk management and maturity models such as the Capability Maturity Model Integration (CMMI) are proposed in order to support product development. The study validates the importance of the use of these systematic approaches to support product development projects, but none of the considered approaches on its own will secure project success. This suggests that the expected benefit (a robust project) can only be achieved using different approaches conjointly. While design methodologies and project management offer a rich support for development activities, risk management supports the project specific selection of appropriate risk treatment measures. A result of this work is a support for the pre-selection of risk treatment strategies based on the project failure causality model and its link to the proposed categorisation of risk treatment strategies. In this dissertation it is shown that the proposed categorisation of risk treatment strategies, the categorisation of the risk impact evolvement, and the question based support were easily understood by industrial experts. Their feedback validates the applicability and acceptance of the question based support as helpful for risk treatment strategy pre-selection, but also lead to a revision of the proposed support. The result is a matrix based support, intended to contribute to an enhancement of project robustness by supporting the process of risk treatment strategy selection which is currently only insufficiently supported. The matrix based support considers, in addition to traditional risk characteristics (likelihood of occurrence and severity of impact) the time-dependent evolvement of risk impacts. [less ▲]

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