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See detailLa construction de la nationalité luxembourgeoise (1839-1940). Une histoire sous influence française, belge et allemande
Scuto, Denis UL

Doctoral thesis (2009)

Modern states have introduced complex legal mechanisms to address the membership or not of an individual to the nation-state. Denis Scuto's doctoral thesis analyzes the construction of Luxembourg ... [more ▼]

Modern states have introduced complex legal mechanisms to address the membership or not of an individual to the nation-state. Denis Scuto's doctoral thesis analyzes the construction of Luxembourg nationality, the Civil Code to today, clearing the influences of Belgian legislation, French and German. Far from being limited to only part of Luxembourg, his approach, enriches reflection on the various forms taken by the construction of citizenship in Europe in modern times. Methodogically, questions of nationality are here not reduced to the legislative aspect; they are intimately linked to the practices and discourse relating to migration and migrants. Should European states open them or not access to nationality? How is the perspective of migrants themselves? The social study of hundreds of naturalization records reveals both motivations and hopes of migrants. The thesis tackles a key challenge faced by the country today who, like Luxembourg, experience strong immigration: how to include the right of the most possible people nationality in a political and social project of common future? [less ▲]

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

Doctoral thesis (2009)

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

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

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

Doctoral thesis (2009)

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See detailENGOs and environmental bargains: A comparative analysis of forest conflicts in Tasmania and British Columbia
Affolderbach, Julia UL

Doctoral thesis (2008)

This thesis focuses on environmental non-governmental organizations (ENGOs) and their roles in forest conflicts in Tasmania, Australia, and British Columbia (BC), Canada. ENGOs challenge vested economic ... [more ▼]

This thesis focuses on environmental non-governmental organizations (ENGOs) and their roles in forest conflicts in Tasmania, Australia, and British Columbia (BC), Canada. ENGOs challenge vested economic interests in order to give greater priority to environmental values. These challenges are often highly conflictual especially with regard to resource use. EN GOs use conflicts and more cooperative forms of behaviour to create environmental bargains with other institutions, notably business, government, labour, and Aboriginal peoples, to achieve their goals. This thesis compares and contrasts environmental bargaining in the forest economies of Tasmania and Be. Conceptually, the thesis elaborates on the theme of environmental bargaining from an institutional perspective that identifies ENGOs as central actors. Environmental bargaining is context sensitive and features the integration of multiple perspectives, dimensions, and voices. Processes and outcomes are interpreted along two dimensions, distribution of power between actors and forms of decision-making ranging from non-participatory to participatory forms. Empirically, the thesis draws upon interviews with over 80 representatives of ENGOs, companies, governmental agencies, and other NGOs in Tasmania and Be. In both places, environmental bargaining was characterized by high levels of conflict and played out on multiple spatial levels led by increasingly global ENGOs. While ENGOs in BC increased their bargaining power through international markets campaigns, Tasmanian environmental groups used national and international support to strengthen their power base. In BC environmental bargaining became more consensual and participatory over time leading to considerable changes in management practices and conservation but also changes in underlying values and perspectives. In Tasmania bargaining was dominated by non­ participatory forms of decision-making that did not reduce conflict potential even though the remapping of Tasmania's forests from industrial uses to protected area status has been relatively greater. In general, ENGOs are important in restructuring and remapping resource peripheries from economic to environmental imperatives as reflected in the bargaining outcomes. Moreover, environmental bargaining is contingent on place and a closer look at the cultural, economic, and political characteristics of the two regions offers explanations as to why environmental bargaining and outcomes differ. [less ▲]

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See detailHyWercs: A middleware for backbone- assisted mobile ad hoc networks
Andronache, Adrian UL

Doctoral thesis (2008)

Detailed reference viewed: 77 (1 UL)
See detailInterfence mitigation and synchronization for satellite communications
Grotz, Joel UL

Doctoral thesis (2008)

Detailed reference viewed: 106 (4 UL)
See detailTowards a framework for application support in mobile networks
Wehling, Ulf UL

Doctoral thesis (2008)

Detailed reference viewed: 87 (3 UL)
See detailArtefact-based annotations. Theory and applications
Hoff, Christian UL

Doctoral thesis (2008)

Detailed reference viewed: 65 (3 UL)
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See detailNon-observabilité des communications à faible latence
Bernard, Nicolas UL

Doctoral thesis (2008)

This thesis is built around two parts, both related to the protection of privacy in computer networks, and more precisely on the Internet. In the first part, we propose a system allowing the establishment ... [more ▼]

This thesis is built around two parts, both related to the protection of privacy in computer networks, and more precisely on the Internet. In the first part, we propose a system allowing the establishment of unobservable interactive communications, unobservable meaning an observer can neither pinpoint the destination(s) of those communications, nor, in fact, know if there are real communications in the first place ! This system aims to provide an unequaled level of protection, as even a very powerful observer should not be able to bypass it. This protection is based on Onion-Routing and adds innovative methods against traffic analysis. In the second part, we take a closer look at the DNS protocol. While it is possible to protect it with our proposition described in the first part, this degrades performance, specifically latency, which has an impact on those protocols using DNS. In this part, we propose a DNS specific solution, providing both a good level of protection and better performance. These two systems can be combined of course, but they can also be used as separate bricks with other privacy enhancing mechanisms too. [less ▲]

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See detailCapacity constraints and enhancements in wireless mesh networks
Scherer, Thomas UL

Doctoral thesis (2008)

Detailed reference viewed: 37 (2 UL)
See detailLiberta, male, speranza, nel Kant precritico
Bules, Layla UL

Doctoral thesis (2008)

Detailed reference viewed: 58 (4 UL)
See detailNetwork security through artificial immunity with SANA
Hilker, Michael UL

Doctoral thesis (2008)

Detailed reference viewed: 166 (94 UL)
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See detailIFDMA for uplink mobile radio communication systems
Arkhipov, Alexander UL

Doctoral thesis (2008)

An application of interleaved frequency-division multiple-access (IFDMA) for mobile communications has become an active field of research since 1998. The special interest has been given to the uplink of ... [more ▼]

An application of interleaved frequency-division multiple-access (IFDMA) for mobile communications has become an active field of research since 1998. The special interest has been given to the uplink of mobile communication since low peak-to-average power ratio makes IFDMA attractive for hand-held mobile devices allowing an application of cheap amplifiers. The IFDMA signal can be generated simply by compression and repetition of the transmit data sequence, without usage of fast Fourier transformation. Due to the periodic nulls in transmit spectrum, other users may utilize the same frequency band allowing multiple access. This work contributes to the state of the art in the field of IFDMA in the following areas: data detection, PAPR reduction of multi-carrier systems, an estimation of frequency offsets in multicarrier uplink, where many users are simultaneously active. [less ▲]

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See detailOccupants using 3D range images
Devarakota, Pandu UL

Doctoral thesis (2008)

Detailed reference viewed: 32 (7 UL)
See detailLes pratiques discursives œnophiles entre normativité et appropriation. Contribution à une sociologie des cultures alimentaires
Reckinger, Rachel UL

Doctoral thesis (2008)

Owing to the fact that wine consumption is becoming ever more culturalised, I have adopted a micro-sociological approach to contemporary œnophile discursive practices, in Luxembourg, by concentrating on ... [more ▼]

Owing to the fact that wine consumption is becoming ever more culturalised, I have adopted a micro-sociological approach to contemporary œnophile discursive practices, in Luxembourg, by concentrating on inherent normativity (moral and aesthetic) and ordinary appropriation (ethical and hedonistic). The context for this articulation is provided by wine tasting lessons ‘for beginners’. The analytical tools that food studies offer are pertinent for tracing the historical evolution of œnophile discursive practices – being singularised, aesthetic and reflexive –, viewed through their rationalisation processes (legislative regulation, scientific consolidation and media diffusion). Through this cristallisation, œnophily has brought about a governmentality of consumption ; its concrete institutionalisation, in the form of state-organised evening-classes, conveys a specific type of normativity. It will be shown that the publics of this institution – mainly male and affluent – have both ‘operational’ and ‘hedonistic’ motivations, thus enhancing a form of governmentality and an interior orientation of experiences. Appropriations of the œnophile normativity are reactive – either positively or negatively : interviewees adopt tactical usages of specific dispositions and of tactical courses of action, related to vertical differenciations (social trajectory and position), but also and mainly to horizontal ones (milieus, interactions and experiments carried out through various projects of subjectivation). These dispositions and tactics are linked to the domestic œnophile logics of action – which are active, strategic and hedonistic. Contrasting with the œnophile normativity (focusing on wine), ordinary discursive practices relate to preoccupations with one’s personal and social life, rather than to wine. Nonetheless, it is the aesthetic-based œnophile canonisation that contains essential prerequisites of subjectivation, even if it is appropriated in a hedonistic, socio- or egocentric way. This shows the consubstantial and flexible interweaving of norms and pleasure, leading to a personal and social empowerment (with a potential that is mainly ethical, but also distinctive), via the discursive usage of one particular food item. [less ▲]

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See detailUltra-high Precision, Absolute, Earth Gravity Measurements PhD Thesis
Rothleitner, Christian UL

Doctoral thesis (2008)

Within the framework of this thesis two apparatuses for an absolute measurement of gravity were designed, constructed, and tested for the purpose of detecting long-term variations of gravity, determining ... [more ▼]

Within the framework of this thesis two apparatuses for an absolute measurement of gravity were designed, constructed, and tested for the purpose of detecting long-term variations of gravity, determining the absolute gravity value for metrological applications, and for research in fundamental physics. The work includes a stationary gravimeter, which functions as a highly accurate reference system and a portable gravimeter, which is aimed for field measurements. The principle these gravimeters use to determine the gravity value is based on the relation between the falling distance, the falling time, and the acceleration due to gravity. A Michelson interferometer measures the distance change between a falling object mirror and an inertial reference mirror with a Helium-Neon laser (633 nm). The whole fringe signal is digitized by a high-speed ADC, which is disciplined by a rubidium frequency standard. This fringe recording is novel compared to common gravimeters, which use an analogue zero-crossing determination. [less ▲]

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See detailTopology control and small-worlds in hybrid wireless networks
Brust, Matthias R. UL

Doctoral thesis (2007)

Detailed reference viewed: 110 (9 UL)
See detailCONTEXTE DE TRAVAIL ET ANALYSE DE L’EXPÉRIENCE. Conception d’une méthode d’aide à l’analyse de l’expérience en contexte.
Pignault, Anne UL

Doctoral thesis (2007)

Insertion et réinsertion dans l’emploi, employabilité, parcours professionnels sont devenus ces dernières années des thèmes prépondérants dans le domaine du travail. Les difficultés connues sur le marché ... [more ▼]

Insertion et réinsertion dans l’emploi, employabilité, parcours professionnels sont devenus ces dernières années des thèmes prépondérants dans le domaine du travail. Les difficultés connues sur le marché du travail, l’augmentation de la précarité, les exigences en termes de polyvalence et de flexibilité, amènent à réexaminer la situation de travail et à s’interroger sur des éléments de transversalité et transférabilité entre différents emplois. Un nombre considérable d’études menées dans différents champs de la psychologie ont permis de mettre en évidence le caractère contextualisé de l’action. Toutefois, la notion de contexte de travail, largement présente dans la littérature, demeure encore largement absente des pratiques d’insertion et d’orientation professionnelle. La présente recherche défend l’idée selon laquelle l’analyse et la prise en compte des contextes de travail peut améliorer l’efficacité des démarches d’aide à la construction de parcours et multiplier les hypothèses d’évolution professionnelle. La démarche qui a contribué à tester cette hypothèse s’est déroulée en trois étapes : la mise au point d’une typologie d’éléments caractéristiques du contexte des emplois-métiers de trois secteurs d’activité différents ; la conception d’une méthode d’analyse de l’expérience intégrant ces éléments de contexte ; la mise en œuvre de la méthode et le suivi de 137 travailleurs et de 22 conseillers emploi et orientation. Les résultats obtenus confirment l’intérêt qu’il y a à prendre en compte l’expérience du contexte pour la construction de parcours professionnels. Cette recherche permet aussi d’aborder la notion de contexte subjectif. Elle relève les différences perceptions individuelles du contexte et fournit des éléments d’explication à ce phénomène. [less ▲]

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See detailOperations on Finite Sets, Functional Composition, and Ordered Sets
Lehtonen, Erkko UL

Doctoral thesis (2007)

The unifying theme of this research work is functional composition. We study operations on a nonempty set A, an important particular case being that of Boolean functions when A = {0, 1}. A class of ... [more ▼]

The unifying theme of this research work is functional composition. We study operations on a nonempty set A, an important particular case being that of Boolean functions when A = {0, 1}. A class of operations is a subset of the set of all operations on A. A clone on A is a class of operations on A that contains all projection maps and is closed under functional composition. The first part of this thesis is a study of compositions of the clones of Boolean functions. The clone of all Boolean functions can be decomposed in various ways into minimal clones, and we observe that such decompositions correspond to different normal form systems: the disjunctive normal form (DNF), conjunctive normal form (CNF), Zhegalkin polynomial, dual Zhegalkin polynomial, and so-called median normal form. These normal form systems are compared in terms of efficiency, and we establish that the median normal form system provides in a certain sense more efficient representations than the other four normal form systems mentioned above. The second part of this thesis is a study of certain order relations on the set of all operations on A. For a fixed class C of operations on A, we say that f is a C-subfunction of g, if f can be obtained by composing g from inside with operations from C. We say that f and g are C-equivalent, if f and g are C-subfunctions of each other. The C-subfunction relation is a quasiorder (a reflexive and transitive relation) on the set of all operations on A if and only if the parametrizing class C is a clone. The simplest example of C-subfunction relations is obtained when C is the smallest clone I of projections on A. Forming I-subfunctions corresponds to simple manipulation of variables, namely addition and deletion of dummy variables, permutation of variables, and identification of variables. None of these operations increases the number of essential variables, and only variable identification may decrease this number. We study more carefully the effect of variable identification on the number of essential variables of operations on finite base sets. We then study certain order-theoretical properties of various C-subfunction partial orders defined by larger clones C on finite base sets A. We are mostly concerned about the descending chain condition and the existence of infinite antichains, and as it turns out, these properties on the defining clone C. Homomorphisms of labeled posets (or k-posets) are applied in our analysis of subfunction relations defined by clones of monotone functions. The third part of this thesis is a study of the homomorphicity order of finite k-posets on its own right. We establish that this order is a distributive lattice, and furthermore, it is universal in the sense that every countable poset can be embedded into it. This result implies universality of the subfunction partial orders defined by clones of monotone functions on finite sets of more than two elements. In this way, we also obtain a new proof for the well-known universality of the homomorphicity order of graphs. [less ▲]

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See detailProgressive methods in multiple criteria decision analysis
Meyer, Patrick UL

Doctoral thesis (2007)

Our work mainly focusses on the study and the development of progressive methods in the field of Multiple Criteria Decision Analysis, i.e., iterative procedures presenting partial conclusions to the ... [more ▼]

Our work mainly focusses on the study and the development of progressive methods in the field of Multiple Criteria Decision Analysis, i.e., iterative procedures presenting partial conclusions to the Decision Maker that can be refined at further steps of the analysis. The thesis is divided into three parts. The first one is intended to be a general analysis of the concept of progressiveness. The last two parts develop progressive methods related first to Multiattribute Value Theory and second to outranking methods. [less ▲]

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See detailPrudent ranking rules: Theoretical contributions and applications
Lamboray, Claude UL

Doctoral thesis (2007)

The subject of this PhD thesis is about ordinal ranking rules. An ordinal ranking rule is a procedure which combines several initial rankings into a global ranking. Given the difficulty and ambiguity of ... [more ▼]

The subject of this PhD thesis is about ordinal ranking rules. An ordinal ranking rule is a procedure which combines several initial rankings into a global ranking. Given the difficulty and ambiguity of aggregating ordinal data, it is worthwhile studying ranking rules which, depending on the initial data, do not lead to one, but to several global rankings, hence leaving some indeterminateness about the final result. It appears that the concept of a prudent order, initially introduced by Arrow and Raynaud, is a possible answer from such a perspective. In this approach, pairwise majority margins are computed which count for any two alternatives the number of initial rankings that prefer the first over the second alternative. A prudent order is then defined as a linear order which maximizes the smallest pairwise majority margin. It was our main objective in this thesis to gain a better understanding of the family of prudent ranking rules. According to our definition, a prudent ranking rule is a rule which outputs only prudent orders. To achieve this goal, we pursued different strategies: i) axiomatic characterizations which highlight the distinctive features of a ranking rule, ii) comparison of the properties or results of prudent ranking rules to those of other ranking rules, and iii) empirical simulations allowing for more quantitative conclusions. The thesis is divided into 3 parts. Part I contains an introduction to the ordinal ranking problem. Our main theoretical contributions can be found in Part II. Finally, Part III illustrates the use of prudent ranking rules in two fields of applications. [less ▲]

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See detailStrafgesetzlichkeit als völkerstrafrechtliches Legitimationsprinzip
Deffert, Dietmar UL

Doctoral thesis (2007)

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See detailGlobal and Local Gravity Field Recovery from Satellite-to-Satellite Tracking
Weigelt, Matthias UL

Doctoral thesis (2007)

The main objective of this thesis is the gravity field recovery using satellite-to-satellite tracking methods. Based on new technologies like the global positioning system and accelerometers satellite-to ... [more ▼]

The main objective of this thesis is the gravity field recovery using satellite-to-satellite tracking methods. Based on new technologies like the global positioning system and accelerometers satellite-to-satellite tracking yields a dramatic improvement in the de- termination of the Earth gravity field. Two dedicated satellite missions, namely the CHAllenging Minisatellite Payload (CHAMP) and the Gravity Recovery And Climate Experiment (GRACE) are underway. This work describes the processing of the satel- lite data from CHAMP and GRACE based on the energy balance approach. The first part discusses the global gravity field recovery from CHAMP. Specifically, it aims at a reprocessing of kinematic position data and at a refinement of the data processing strategies. Although the energy balance approach is theoretically simple, its imple- mentation proved to be quite challenging. By refining the processing techniques an improvement of up to 30\% is reached for the low degree spherical harmonic coefficients. Nevertheless, the solutions still depend strongly on the variability of the groundtrack. The quality of the monthly solutions can vary up to one order of magnitude. To ad- dress this challenge, an in-depth analysis gives new insight into the phenomenon, and a new and unique combination method with GRACE data is presented, which yields a more homogeneous set of solutions and reaches the edge of the recoverability of a time-variable gravity signal from high-low satellite-to-satellite tracking missions. In the second part the energy balance approach is applied to the GRACE mission. Pre- vious attempts of expressing the kinetic energy in terms of the K-band measurement make use of an approximation. In this work, an exact representation is introduced and is validated by simulations. In the third part, the aim is to make optimal usage of the data distribution in the high latitude area. For this, interpolation and downward continuation techniques are investigated and an improvement, compared to the global solutions, is achieved. Overall, the analysis provides new and valuable insight into the data processing of satellite-to-satellite tracking data using the energy balance approach. [less ▲]

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See detailRelating to Nature: The Performative Spaces of Icelandic Tourism
Olafsdottir, Gunnthora UL

Doctoral thesis (2007)

Detailed reference viewed: 104 (0 UL)
See detailZum Tragverhalten von Flachdecken mit integrierten hohlkastenförmigen Stahlprofilen
Schäfer, Markus UL

Doctoral thesis (2007)

Due to the demand for slim constructions and improvement of erection methods on building site composite slim-floor systems become more important. In the present european and national codes do not include ... [more ▼]

Due to the demand for slim constructions and improvement of erection methods on building site composite slim-floor systems become more important. In the present european and national codes do not include complete design rules for slim-floor constructions. Therefore the objective of this thesis is concentrated on the development of design rules for slim-floor girders. During the erection stage the elastic design resistance of the steel girder is decisive. Because of the slight plate thickness and sometimes considerable torsional stressing the influence of the shape deformation becomes more important and has to be considered. In this approach the steel sections are filled with concrete in the final state. Thereby the concrete in the openings, arranged in the web or upper flange, work concurrently as concrete dowels. The determination of moment resistance follows the rules for composite structures, respectively whereas in many cases the strain limited design is relevant and additionally the influences from transverse bending in the bottom flange have to be considered. Because of the sheathing of the concrete encasement by the steel section a hybrid truss model with a compression strut in the concrete section is developed, increasing the shear of the section. In case of fire, the directly flamed bottom flange can be substituted by longitudinal reinforcement bars and a high fire resistance period can be realized without any additional activities. For the analysis in case of fire, a design-method is extracted according to EN 1994-1-2. Based on a transient analysis, thermal analytic functions are developed to describe the temperature distribution in the cross section. The crack behaviour of the concrete slab has already a significant impact on the girder deformation in the serviceability limit state. The concrete flange adopts a remarkable part of the bending-moment. Compared to general treatment of common composite girders, the neglecting of these bending influences can lead to unrealistic camber of the girder. Therefore, an approximation procedure is derived that considers the bearing of the resilience of composite connector and the crack behaviour on the structure deformation. [less ▲]

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See detailUse of commercial simulation software for analyzing the dynamics of an injection-molding clamp unit
Hostert, Claude UL

Doctoral thesis (2006)

Today, the interest in integrated dynamic analysis of mechatronic systems increases. Different approaches are possible depending on the nature of the system, on the required complexity of the model, or ... [more ▼]

Today, the interest in integrated dynamic analysis of mechatronic systems increases. Different approaches are possible depending on the nature of the system, on the required complexity of the model, or simply on the tools available to the engineer. During this work, the aim was to implement specialized commercial simulation software packages and to combine them in order to simulate the dynamic behavior of mechatronic systems as for example an injection molding machine. The multi-body simulation software is the backbone of the current analysis as it inherently models large non-linear motions. It is possible to account for the flexibility of components in the MBS model if necessary. Furthermore, other simulation codes were used to model the hydraulic and controls systems. The case studies show the interest and the potential of a combined analysis of mechatronic systems. Once the different sub-models, generated with the adequate simulation tool, have been successfully linked and validated by measurements, various scenarios can be simulated and analyzed. The model provides the engineer with an additional insight into the overall system and thus with a better understanding of its dynamic characteristics. The interactions between the subsystems, which may be of very distinctive nature, can be investigated. Generally, it is difficult to predict such relations intuitively. Finally, the model allows to simulate with different design parameters and to asses the effect of modifications to these on the overall performance of the machine. This helps to identify the significant parameters that are crucial for an optimized functioning. [less ▲]

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See detailDie Rolle der Landwirtschaft in der Eigenständigen Regionalentwicklung der Region "West" Irlands
Sprenger, Birte UL

Doctoral thesis (2005)

Die Bedeutung der Landwirtschaft für die Eigenständige Regionalentwicklung unter Berücksichtigung der Multifunktionalität der landwirtschaft am Fallbeispiel der peripherem agrarstrukturell geprägten ... [more ▼]

Die Bedeutung der Landwirtschaft für die Eigenständige Regionalentwicklung unter Berücksichtigung der Multifunktionalität der landwirtschaft am Fallbeispiel der peripherem agrarstrukturell geprägten region West in der Republik Irland wird untersucht und bewertet. [less ▲]

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See detailFamily adjustment to disability and chronic illnessin children
Pit-Ten Cate, Ineke UL

Doctoral thesis (2004)

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See detailDie bakterielle Signalverarbeitung am Beispiel des Sucrose Phosphotransferasesystems in Escherichia coli : Modellierung und experimentelle Überprüfung
Sauter, Thomas UL

Doctoral thesis (2003)

Bacterial signal processing was investigated concerning the sucrose phosphotransferase system (sucrose PTS) in the bacterium Escherichia coli as an example. The about 20 different phosphotransferase ... [more ▼]

Bacterial signal processing was investigated concerning the sucrose phosphotransferase system (sucrose PTS) in the bacterium Escherichia coli as an example. The about 20 different phosphotransferase systems (PTSs) of the cell fulfil besides the transport of various carbohydrates, also the function of one signal processing system. Extra- and intracellular signals are converted within the PTS protein chain to important regulatory signals affecting e.g. carbon metabolism and chemotaxis. A detailed dynamical model of the sucrose PTS was developed describing transport and signal processing function. It was formulated using a detailed description of complex formation and phosphate transfer between the chain proteins. Model parameters were taken from literature or were identified with own experiments. Using a formal algorithm including cluster analysis, PTS and glycolysis could be identified as biological functional units with limited autonomy. Simulation studies together with experimental hints showed that the dynamic behaviour of phosphate transfer in the PTS runs within one second. Therefore a description of steady state characteristics is sufficient for describing the signaling properties of the sucrose PTS. A steady state characteristic field describes the degree of phosphorylation of the PTS protein EIIACrr as a function of the input variables extracellular sucrose concentration and intracellular PEP:pyruvate ratio. The model has been validated with different experiments performed in a CSTR using an sucrose positive Escherichia coli W3110 derivative. A method for determining intracellular metabolite concentrations has been developed. A sample preparation technique using a boiling ethanol buffer solution was successfully applied. The PTS output signal degree of phosphorylation of EIIACrr was also measured. Steady state conditions with varying dilution rate and dissolved oxygen concentration and dynamical variations applying different stimuli to the culture were considered. Pulse, and stop feeding experiments with limiting sucrose concentrations were performed. Simulation and experimental results matched well. The same holds for the expanded sucrose PTS and glycolysis model. [less ▲]

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See detailDas modale Zeitgedächtnis
Klapproth, Florian UL

Doctoral thesis (2003)

Detailed reference viewed: 34 (2 UL)
See detailBenetzung in ternären Flüssigkeitsmischungen
Schilling, Tanja UL

Doctoral thesis (2001)

Detailed reference viewed: 65 (5 UL)
See detailMotologie zwischen objektiver und subjektiver Sinnesphysiologie
Wantz, Marc UL

Doctoral thesis (2000)

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See detailAggregation Operators for Multicriteria Decision Aid
Marichal, Jean-Luc UL

Doctoral thesis (1998)

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See detailDiscrete element analysis of granular materials
Van Baars, Stefan UL

Doctoral thesis (1996)

Discrete Element Analysis of Granular Materials During oil and gas production, several years after drilling a borehole, sand particles and small sandstone particles start to break away from the borehole ... [more ▼]

Discrete Element Analysis of Granular Materials During oil and gas production, several years after drilling a borehole, sand particles and small sandstone particles start to break away from the borehole surface. These particles can damage the transport pipes and other equipment in a short period of time. By simulating this borehole behaviour with the thick-walled cylinder test, four phenomena were found which cannot be explained by conventional continuum mechanics: 1. Despite the compressive stress, failure occurs on the micro level due to tension cracks. 2. These cracks are not diagonal to, but parallel to, the borehole surface. 3. These cracks cause two diametrically opposite breakouts. 4. The functional failure of the borehole starts at a higher radial pressure than predicted. In 1979, Cundall developed a computer model, based on the basic elements of granular materials, i.e. the grains themselves and their interactions, to describe the behaviour of these materials. Lindhout tried, in 1992, to use this model to describe the cylinder test. Due to compaction problems, stability problems and the large computational time, this could not be achieved. Therefore a new model was developed by the author, which does not use the equations of motion, but the equations of equilibrium, to calculate the new grain positions. This model can be used both for non-cohesive grains (sand) and for cohesive grains (sandstone). The results can generally be described by an advanced Mohr-Coulomb model. However, there are a few exceptions. Firstly, during loading of a granular structure, many contacts between the grains will collapse, not due to shear deformation as Coulomb suggests, but due to tension failure. Secondly, these micro cracks always occur in the direction of the major principal stress, which might be another direction than the observed failure surface. In this way, the axial micro cracks form a diagonal failure surface during a biaxial test, but the axial micro cracks in a cylinder test may form a failure surface parallel to the borehole surface. During the formation of natural sandstone, the difference between the horizontal and vertical stress causes anisotropy in the strength behaviour of this material. This or other anisotropies may explain the diametrically opposite breakouts. The conclusion that a borehole fails at a higher radial pressure than predicted, originates from the definition difference between local failure and functional failure and the large rest capacity of a thick-walled cylinder. [less ▲]

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See detailSequenz und Sequenz-Struktur Vergleiche und deren Anwendung für die Struktur- und Funktionsvorhersage von Proteinen
Schneider, Reinhard UL

Doctoral thesis (1994)

Zusammenfassung der Inaugural-Dissertation Name: Reinhard Schneider Titel: Sequenz und Sequenz-Struktur Vergleiche und deren Anwendung für die Struktur- und Funktionsvorhersage von Proteinen Betreuer ... [more ▼]

Zusammenfassung der Inaugural-Dissertation Name: Reinhard Schneider Titel: Sequenz und Sequenz-Struktur Vergleiche und deren Anwendung für die Struktur- und Funktionsvorhersage von Proteinen Betreuer: Prof. Dr. K. C. Holmes (MPI für medizinische Forschung, Heidelberg) Durch die sogenannten Genomprojekte wird es in den nächsten Jahren zu einer enormen Vergrößerung der biologischen Sequenzdatenbanken kommen. Eine unabdingbare Voraussetzung zur Nutzung dieses Rohmaterials stellt dabei die Analyse dieser Sequenzdaten mit Hilfe rechnergestützter Methoden dar. Eines der Hauptanwendungsgebiete von Rechnern für die Funktions- und Strukturvorhersage von Proteinen werden dabei selektive Datenbanksuche nach biologisch signifikanten Ähnlichkeiten sein. Zur Signifikanzabschätzung eines Proteinsequenzvergleiches (Alignment) wurde ein empirisch abgeleiteter Homologieschwellenwert definiert. Wichtigstes Merkmal ist dabei eine starke Abhängigkeit von der Länge des betreffenden Alignments. Diese Signifikanzabschätzung ermöglicht sowohl den Ausschluß von nicht verwandten Proteinen, wie auch die Detektion von schwachen Sequenzverwandtschaften. Aufgrund der Allgemeingültigkeit des Homologieschwellenwertes kann er als einfacher und effizienter zusätzlicher Filter für andere Methoden, wie z.B. schnelle Datenbanksuchen, verwendet werden. Es wurde ein neuer Algorithmus für den multiplen Sequenzvergleich entwickelt, der eine relativ geringe rechnerische Komplexität besitzt. Das Hauptmerkmal dieses Algorithmus besteht in der Ableitung von sogenannten positionsabhängigen Konservierungsgewichten, die als zusätzliche Parameter im dynamischen Programmieralgorithmus verwendet werden und zu einer deutlich gesteigerten Sensitivität bei Datenbanksuchen führt. Die programmiertechnische Auslegung des Algorithmus erlaubt die zukünftige Erweiterung auf den Vergleich einer Sequenz gegen ein Sequenzprofil bzw. den Vergleich zweier Sequenzprofile. Um auch zukünftig sensitive Datenbanksuchen in einer vertretbaren Rechenzeit durchführen zu können,, wurde das Programm auf parallele Rechner portiert. Die Ergebnisse zeigen, daß mit den heute verfügbaren massiv parallelen Rechnern ein beinahe interaktives Arbeiten möglich ist. Aufbauend auf dieser Arbeit wird derzeit im Rahmen eines europäischen Projektes die Implementierung der Profilmethoden auf Parallelrechner der neuesten Generation durchgeführt und der Nutzen für das industrielle “Protein design” bestimmt. Mit Hilfe des Homologieschwellenwertes konnte eine Datenbank für homologie-abgeleitete Proteinstrukturen (HSSP) entwickelt werden. Diese Datenbank wird der Öffentlichkeit auf verschiedenen Wegen zugänglich gemacht und hat sich als ein gewisser Standard etabliert. Die Datenbank findet dabei Verwendung im automatisierten dreidimensionalen Modellbau von Proteinstrukturen, sowie als Hilfsmittel und Datengrundlage für ein weitgestecktes Feld von statistischen und anderen theoretischen Arbeiten. Die Verwendung der Datenbank hat einen entscheidenden Beitrag bei der Entwicklung des derzeit besten Programms zur Vorhersage der Sekundärstruktur von Proteinen geleistet. Diese Vorhersagemethode basiert auf einem neuronalen Netzwerk, das die Informationen eines multiplen Sequenzvergleichs ausnutzt. Zur Berechnung der multiplen Sequenzalignments und der dazu notwendigen Datenbanksuche wird das in dieser Arbeit entwickelte Programm verwendet. Die Methode wurde in Form eines Vorhersagedienstes, der über internationale Datenleitungen verfügbar ist, der Öffentlichkeit zugänglich gemacht. Einen neuen Ansatz für die Vorhersage von Proteinstruktur bei fehlender Sequenzverwandtschaft zu einer bereits bekannten Struktur stellt die Methode für das Sequenz-Strukturalignment (“threading”) dar. Dazu wird eine dreidimensionale Struktur in Form von interatomaren Kontakten beschrieben und mit Hilfe von Präferenzparametern die Tauglichkeit einer Sequenz in eine Struktur bewertet. Die Ergebnisse zeigen, daß sowohl eine Verbesserung der abstrahierten Beschreibung für eine dreidimensionale Proteinstruktur, wie auch ein verbesserter Alignmentalgorithmus notwendig ist. Ein in der Praxis vielversprechender Ansatz ist die Verwendung von Methoden, die einerseits eine abstrahierte 3D-Beschreibung zulassen und zusätzlich einen gewissen Grad an Sequenzinformation, etwa in Form eines Sequenzprofils mit einbeziehen. Am Beispiel eines kompletten Chromosoms aus Hefe wurde eine komplexe funktionelle Genomanalyse durchgeführt. Hierbei konnten eine Reihe von biologisch interessanten Sequenzverwandtschaften aufgedeckt werden, waren jedoch mit einem hohen Arbeitsaufwand verbunden. Dabei stellte sich die ungenügende Integration der vorhanden Methoden und heterogenen Datenbanken als Hauptproblem heraus. Die dabei gesammelten Erfahrungen fließen derzeit in die Entwicklung eines integrierten Softwarepackets ein, mit dessen Hilfe es möglich sein wird, den Arbeitsaufwand, der zur Analyse von großen Datenmengen notwendig ist, drastisch zu reduzieren. [less ▲]

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