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See detailDeveloping composite nanofibre fabrics using electrospinning, ultrasonic sewing, and laser cutting technologies
Trejo, Nidia; Reyes, Catherine UL; Sanchez, Vanessa et al

in International Journal of Fashion Design, Technology and Education (2016), 9(3), 192-200

In this study, we combine Nylon 6 nanomembranes with tulle and organza fashion fabrics to construct a full-scale, flying kite. For the first time, this work demonstrates the processing of electrospun ... [more ▼]

In this study, we combine Nylon 6 nanomembranes with tulle and organza fashion fabrics to construct a full-scale, flying kite. For the first time, this work demonstrates the processing of electrospun nanofabrics using laser cut and ultrasonic technologies. The composite fabrics were analysed for their morphological and mechanical properties. The fracture strain of the nanomembrane–tulle composites increased 58–171% compared to the control samples due to nanofibre entanglements on the open weave structure of tulle. The ultrasonic sewn fabric regions endured 169% greater applied stress with the addition of the organza fabric and the seaming process compared to the nanomembrane–tulle composite. [less ▲]

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See detailDevelopment and Application of an Asymptotic Level Transport Pollution Model for Luxembourg Energy Air Quality Project
Aleluia Da Silva Reis, Lara UL

Doctoral thesis (2013)

The connections between air pollution and the increase of respiratory diseases, are well known. In Europe, many efforts have been carried out towards the mitigation of the pollutants’ emissions over the ... [more ▼]

The connections between air pollution and the increase of respiratory diseases, are well known. In Europe, many efforts have been carried out towards the mitigation of the pollutants’ emissions over the last decades. The European Union supports the implementation of structural planning measures to control air pollution. The assessment and evaluation of these air quality policies must be carried out with the help of dedicated integrated assessment models. The use of integrated assessment models, which combine models from different fields, raises the need for developing specific modelling concepts in order to provide results to support policy decisions within a practical time frame. This work presents the methodology and the development of a dedicated air quality model for an integrated assessment model. This approach has been designed for the Luxembourg Energy and Air Quality, LEAQ, integrated assessment model. It combines an air quality model, AUSTAL2000-AYLTP, with a techno-economic model, ETEM, which computes ozone precursors emissions related to energy consumption. The models are coupled via an optimization engine, which minimizes the total energy cost for a given ozone level. AUSTAL2000, a Lagrangian transport model, has been adapted to receive a photochemical module, the AsYmptotic Level Transport Pollution, AYLTP. This module consists of a Look-Up Table of quasi-linear reaction rates. A balance has been found that gives an acceptable level of accuracy, given the reduction of computational time. The results of the air quality model have been compared with measurements, and with the regional model LOTOS-EUROS and are considered satisfactory for this type of approach. Regarding the LEAQ framework, two study cases have been simulated, one including only the national emissions from Luxembourg country, and a second one for the Luxembourg region, including the neighbouring countries emissions. [less ▲]

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See detailDevelopment of an integrated omics in silico workflow and its application for studying bacteria-phage interactions in a model microbial community
Narayanasamy, Shaman UL

Doctoral thesis (2017)

Microbial communities are ubiquitous and dynamic systems that inhabit a multitude of environments. They underpin natural as well as biotechnological processes, and are also implicated in human health. The ... [more ▼]

Microbial communities are ubiquitous and dynamic systems that inhabit a multitude of environments. They underpin natural as well as biotechnological processes, and are also implicated in human health. The elucidation and understanding of these structurally and functionally complex microbial systems using a broad spectrum of toolkits ranging from in situ sampling, high-throughput data generation ("omics"), bioinformatic analyses, computational modelling and laboratory experiments is the aim of the emerging discipline of Eco-Systems Biology. Integrated workflows which allow the systematic investigation of microbial consortia are being developed. However, in silico methods for analysing multi-omic data sets are so far typically lab-specific, applied ad hoc, limited in terms of their reproducibility by different research groups and suboptimal in the amount of data actually being exploited. To address these limitations, the present work initially focused on the development of the Integrated Meta-omic Pipeline (IMP), a large-scale reference-independent bioinformatic analyses pipeline for the integrated analysis of coupled metagenomic and metatranscriptomic data. IMP is an elaborate pipeline that incorporates robust read preprocessing, iterative co-assembly, analyses of microbial community structure and function, automated binning as well as genomic signature-based visualizations. The IMP-based data integration strategy greatly enhances overall data usage, output volume and quality as demonstrated using relevant use-cases. Finally, IMP is encapsulated within a user-friendly implementation using Python while relying on Docker for reproducibility. The IMP pipeline was then applied to a longitudinal multi-omic dataset derived from a model microbial community from an activated sludge biological wastewater treatment plant with the explicit aim of following bacteria-phage interaction dynamics using information from the CRISPR-Cas system. This work provides a multi-omic perspective of community-level CRISPR dynamics, namely changes in CRISPR repeat and spacer complements over time, demonstrating that these are heterogeneous, dynamic and transcribed genomic regions. Population-level analysis of two lipid accumulating bacterial species associated with 158 putative bacteriophage sequences enabled the observation of phage-host population dynamics. Several putatively identified bacteriophages were found to occur at much higher abundances compared to other phages and these specific peaks usually do not overlap with other putative phages. In addition, there were several RNA-based CRISPR targets that were found to occur in high abundances. In summary, the present work describes the development of a new bioinformatic pipeline for the analysis of coupled metagenomic and metatranscriptomic datasets derived from microbial communities and its application to a study focused on the dynamics of bacteria-virus interactions. Finally, this work demonstrates the power of integrated multi-omic investigation of microbial consortia towards the conversion of high-throughput next-generation sequencing data into new insights. [less ▲]

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See detailDevelopments in Mesh-Moving and Mesh-Update Schemes for Space-Time Finite Element Dicretisations of Fluid Flows
Schippke, Henning; Zilian, Andreas UL

Scientific Conference (2011)

Space-time discretisations of physical problems involving moving and deforming bodies, boundaries and interfaces have been shown to offer advantageous properties, while being methodologically uniform and ... [more ▼]

Space-time discretisations of physical problems involving moving and deforming bodies, boundaries and interfaces have been shown to offer advantageous properties, while being methodologically uniform and flexible. Well-known phenomena, which are ideally suited to be analysed by space-time methods, are fluid-structure interaction problems in general as well as fluid flows with subdomain phase boundaries or immersed moving objects. In this contribution existing mesh-moving and mesh-update techniques are comparatively discussed within the framework of finite element discretisations of the Navier-Stokes equations in space and time. The investigation is based on a SUPG/PSPG velocity-pressure formulation on the deforming space-time do- main. Developments of mesh reconnection at fluid-solid interfaces due to mesh-moving/reconnecting proce- dures for space-time discretisations of fluid flows are presented. Furthermore mesh-update/reconnecting techniques are examined occurring in engineering problems involving sliding or rotating space-time fluid meshes. The presented techniques are accompanied by numerical examples of translational fluid flow as well as fluid flow with immersed rotating fluid bodies. The quality of the approximative solution on the moving and deforming mesh as well as its conservation properties are investigated. [less ▲]

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See detailDevice-free indoor localization using ambient radio signals
Popleteev, Andrei UL

in UbiComp-2013 Adjunct proceedings (2013)

This paper investigates feasibility of device-free indoor localization using single passive receiver. Instead of local wireless nodes sharing one frequency channel, this work leverages multiple ambient FM ... [more ▼]

This paper investigates feasibility of device-free indoor localization using single passive receiver. Instead of local wireless nodes sharing one frequency channel, this work leverages multiple ambient FM radio stations. Experimental results demonstrate feasibility of the proposed approach and highlight the role of frequency diversity for passive localization. [less ▲]

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See detailDigital History Projects As Boundary Objects
Kemman, Max UL

Scientific Conference (2017)

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See detailDimensions of Digital History Collaborations
Kemman, Max UL

Scientific Conference (2016)

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See detailDirect image-analysis methods for surgical simulation and mixed meshfree methods
Hale, Jack UL; Bordas, Stéphane UL; Kerfriden, Pierre et al

Presentation (2014, May 28)

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See detailDirectionality of Attacks in Natural Language Argumentation
Cramer, Marcos UL; Guillaume, Mathieu UL

in CEUR Workshop Proceedings (2018)

In formal (abstract and structured) argumentation theory, a central notion is that of an attack between a counterargument and the argument that it is challenging. Unlike the notion of an inconsistency ... [more ▼]

In formal (abstract and structured) argumentation theory, a central notion is that of an attack between a counterargument and the argument that it is challenging. Unlike the notion of an inconsistency between two statements in classical logic, this notion of an attack between arguments can be asymmetric, i.e. an argument A can attack an argument B without B attacking A. While this property of the formal systems studied by argumentation theorist has been motivated by considerations about the human practice of argumentation in natural language, there have not been any systematic studies on the connection between the directionality of attacks in argumentation-theoretic formalisms and the way humans actually interpret conflicts between arguments in a non-symmetric way. In this paper, we report on the result of two empirical cognitive studies that aim at filling this gap, one study with ordinary adults (undergraduate students) and one study with adult experts in formal argumentation theory. We interpret the results in light of the notions and distinctions defined in the ASPIC+ framework for structured argumentation, and discuss the relevance of our findings to past and future empirical studies about the link between human argumentation and formal argumentation theory. [less ▲]

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See detailDiscrete mechanical models and upscaling techniques for discrete materials
Beex, Lars UL; Bordas, Stéphane UL

Poster (2016)

Numerous natural and man-made materials are essentially discrete structures at the mesoscale or microscale (see Fig. 1). Discrete mechanical models can be formulated to capture typical mechanical ... [more ▼]

Numerous natural and man-made materials are essentially discrete structures at the mesoscale or microscale (see Fig. 1). Discrete mechanical models can be formulated to capture typical mechanical phenomena arising from this discreteness. Failure in these materials, which often starts with the fracture of an individual bond, can be predicted based on the small-scale mechanics with these models. For failure, but also for non-local mechanics, no phenomenological descriptions are required in these models. This makes them more predictive than constitutive material models for this type of materials. [less ▲]

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See detailDiscrete Multiscale Modelling and Future Research Plans concerning Metals
Beex, Lars UL; Bordas, Stéphane UL; Rappel, Hussein UL et al

Presentation (2014, October 14)

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See detailA discrete-continuous approach to describe CaCO3 decarbonation in non-steady thermal conditions
Copertaro, Edoardo UL; Chiariotti, Paolo; Estupinan Donoso, Alvaro Antonio et al

in Powder Technology (2015), 275

In cement production, direct measurements of thermal and chemical variables are often unfeasible as a consequence of aggressive environments, moving parts and physical inaccessibility, and therefore ... [more ▼]

In cement production, direct measurements of thermal and chemical variables are often unfeasible as a consequence of aggressive environments, moving parts and physical inaccessibility, and therefore prediction models are essential tools in these types of industrial applications. This article addresses the problem of the numerical prediction of the CaCO3 calcination process, which is the first and the most energy expensive process in clinker production. This study was conducted using the Extended Discrete Element Method (XDEM), a framework which allows a Eulerian approach for the gas phase to be combined with a Lagrange one for the powder phase. A detailed validation of the numerical model was performed by comparison to non-isothermal TG curves for mass loss during the CaCO3 decarbonation process. The complex three-dimensional predictions for solid and gas phases are believed to represent a first step towards a new insight into the cement production process. Thus, the high accuracy and detailed description of the problem addressed, serve as a basis to assess the uncertainty of more simplified models such as those used in soft sensors. [less ▲]

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See detailDiscretisation and Model Selection for Interface Problems in Mechanics
Bordas, Stéphane UL

in International Journal of Computational Methods (2017, August 04)

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See detailDistributed attitude synchronization control
Thunberg, Johan UL; Montijano, E.; Hu, X.

in Proceedings of the 50th IEEE Conference on Decision and Control and European Control Conference (CDC-ECC) (2011)

In this paper we consider the problem of constructing feedback control laws for a system of n agents that shall synchronize their attitudes in SO(3). We propose distributed controllers for two ... [more ▼]

In this paper we consider the problem of constructing feedback control laws for a system of n agents that shall synchronize their attitudes in SO(3). We propose distributed controllers for two synchronization problems, in which the objective is the same, to synchronize the orientations, but what the agents can perceive or communicate differs. In the first problem the agents can measure their orientation to a common reference object, and either communicate with the neighbors or estimate the relative orientation to their neighbors. In the second problem the agents can, without communication, only measure the relative orientation to the neighbors. For the first problem we present a controller which will lead to synchronization, provided the neighborhood graph is connected. For the second problem we present a controller that will lead to synchronization provided the neighborhood graph is connected and the agents initially are contained within a geodesic ball of radius π/2, which is the maximal convex set in SO(3). [less ▲]

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See detailDistributed attitude synchronization control of multi-agent systems with directed topologies
Thunberg, Johan UL; Song, W.; Hong, Y. et al

in the proceedings of the 10th World Congress on Intelligent Control and Automation (2012)

In the present paper we consider the problem of attitude synchronization for a system of rigid body agents. We provide distributed kinematic control laws for two different synchronization problems. In the ... [more ▼]

In the present paper we consider the problem of attitude synchronization for a system of rigid body agents. We provide distributed kinematic control laws for two different synchronization problems. In the two problems the objective is the same, i.e., to synchronize the orientations of the agents, but what is assumed to be measurable by the agents differs. In problem 1 the agents measure their own orientations in a global reference frame, and obtain the orientations of their neighbors by means of communication. In problem 2 the agents only measure the relative orientations to their neighbors. By using the axis-angle representation of the orientation, we show that simple linear control laws solve both synchronization problems. Moreover we show that our proposed control laws work for directed and connected topologies on almost all SO(3) for problem 1 and on convex balls in SO(3) for problem 2. [less ▲]

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See detailDistributed attitude synchronization control of multi-agent systems with switching topologies
Thunberg, Johan UL; Song, W.; Montijano, E. et al

in Automatica (2014), 50(3), 832-840

This paper addresses the attitude synchronization problem in multi-agent systems with directed and switching interconnection topologies. Two cases for the synchronization problem are discussed under ... [more ▼]

This paper addresses the attitude synchronization problem in multi-agent systems with directed and switching interconnection topologies. Two cases for the synchronization problem are discussed under different assumptions about the measurable information. In the first case the agents can measure their rotations relative to a global reference coordinate frame, whilst in the second case they can only measure the relative rotations between each other. Two intuitive distributed control laws based on the axis–angle representations of the rotations are proposed for the two cases, respectively. The invariance of convex balls in SO(3) is guaranteed. Moreover, attitude synchronization is ensured under the well-known mild switching assumptions, the joint strong connection for the first case and joint quasi-strong connection for the second case. To show the effectiveness of the proposed control schemes, illustrative examples are provided. [less ▲]

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See detailDistributed attitude synchronization control of multi-agent systems with time-varying topologies
Song, W.; Thunberg, Johan UL; Hong, Y. et al

in Proceedings of the 10th World Congress on Intelligent Control and Automation (2012)

This paper addresses the attitude synchronization problem of multiple rigid body agents in SO(3) with directed and switching interconnection topologies. Using the axis-angle representation of the ... [more ▼]

This paper addresses the attitude synchronization problem of multiple rigid body agents in SO(3) with directed and switching interconnection topologies. Using the axis-angle representation of the orientation, a distributed controller based on differences between the orientations of agents in a global frame is proposed. In the case of the balanced interconnection graph, the attitude synchronization is achieved with the well-known mild assumption (that is, uniform joint strong connection). To demonstrate the effectiveness of the proposed control scheme, an illustrative example is provided. [less ▲]

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See detailDistributed attitude synchronization using backstepping and sliding mode control
Thunberg, Johan UL; Song, W.; Hong, Y. et al

in Control Theory and Technology (2014), 12(1), 48-55

We consider the problem of attitude synchronization for systems of rigid body agents with directed topologies. Two different scenarios for the rotation matrices of the agents are considered. In the first ... [more ▼]

We consider the problem of attitude synchronization for systems of rigid body agents with directed topologies. Two different scenarios for the rotation matrices of the agents are considered. In the first scenario, the rotations are contained in a convex subset of SO(3), which is a ball of radius less than π/2, whereas in the second scenario the agents are contained in a subset of SO(3), which is a ball of radius less than π. Using a control law based on backstepping and sliding mode control, we provide distributed, semi-global, torque control laws for the agents so that the rotations asymptotically synchronize. The control laws for the agents in the first scenario only depend on the relative rotations between neighboring agents, whereas the control laws in the second scenario depend on rotations defined in a global coordinate frame. Illustrative examples are provided where the synchronization is shown for both scenarios. [less ▲]

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