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See detailDeliberate and Accidental Gas-Phase Alkali Doping of Chalcogenide Semiconductors: Cu(In,Ga)Se2
Colombara, Diego UL; Berner, Ulrich; Ciccioli, Andrea et al

in Scientific Reports (2017), 7

Alkali metal doping is essential to achieve highly efficient energy conversion in Cu(In,Ga)Se2 (CIGSe) solar cells. Doping is normally achieved through solid state reactions, but recent observations of ... [more ▼]

Alkali metal doping is essential to achieve highly efficient energy conversion in Cu(In,Ga)Se2 (CIGSe) solar cells. Doping is normally achieved through solid state reactions, but recent observations of gas phase alkali transport in the kesterite sulfide (Cu2ZnSnS4) system (re)open the way to a novel gas-phase doping strategy. However, the current understanding of gas-phase alkali transport is very limited. This work (i) shows that CIGSe device efficiency can be improved from 2% to 8% by gas-phase sodium incorporation alone, (ii) identifies the most likely routes for gas-phase alkali transport based on mass spectrometric studies, (iii) provides thermochemical computations to rationalize the observations and (iv) critically discusses the subject literature with the aim to better understand the chemical basis of the phenomenon. These results suggest that accidental alkali metal doping occurs all the time, that a controlled vapor pressure of alkali metal could be applied during growth to dope the semiconductor, and that it may have to be accounted for during the currently used solid state doping routes. It is concluded that alkali gas-phase transport occurs through a plurality of routes and cannot be attributed to one single source. [less ▲]

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See detailDemand and Interference Aware Adaptive Resource Management for High Throughput GEO Satellite Systems
Abdu, Tedros Salih UL; Kisseleff, Steven UL; Lagunas, Eva UL et al

in IEEE Open Journal of the Communications Society (2022)

The scarce spectrum and power resources, the inter-beam interference, together with the high traffic demand, pose new major challenges for the next generation of Very High Throughput Satellite (VHTS ... [more ▼]

The scarce spectrum and power resources, the inter-beam interference, together with the high traffic demand, pose new major challenges for the next generation of Very High Throughput Satellite (VHTS) systems. Accordingly, future satellites are expected to employ advanced resource/interference management techniques to achieve high system spectrum efficiency and low power consumption while ensuring user demand satisfaction. This paper proposes a novel demand and interference aware adaptive resource management for geostationary (GEO) VHTS systems. For this, we formulate a multi-objective optimization problem to minimize the total transmit power consumption and system bandwidth usage while matching the offered capacity with the demand per beam. In this context, we consider resource management for a system with full-precoding, i.e. all beams are precoded; without precoding, i.e. no precoding is applied to any beam; and with partial precoding, i.e. only some beams are precoded. The nature of the problem is non-convex and we solve it by jointly using the Dinkelbach and Successive Convex Approximation (SCA) methods. The simulation results show that the proposed method outperforms the benchmark schemes. Specifically, we show that the proposed method requires low resource consumption, low computational time, and simultaneously achieves a high demand satisfaction. [less ▲]

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See detailDemontage von Elektroantrieben mit Assistenzrobotern zum wirtschaftlichen Recycling
Jungbluth, Jan UL; Plapper, Peter UL; Gerke, Wolfgang

in Tagungsband AALE 2016 (2016)

Die zerstörungsfreie Demontage zum Zweck der Refrabrikation oder des höherwertigem Produktrecyclings findet nur selten im industriellen Umfeld Anwendung. Allerdings ist mit einem Anstieg dieses trennenden ... [more ▼]

Die zerstörungsfreie Demontage zum Zweck der Refrabrikation oder des höherwertigem Produktrecyclings findet nur selten im industriellen Umfeld Anwendung. Allerdings ist mit einem Anstieg dieses trennenden Fertigungsverfahrens in naher Zukunft zu rechnen da die immer stärker begrenzten und zugänglichen Ressourcen durch strengere Gesetze im Rahmen der Abfallwirtschaft gesichert werden müssen. Zum Beispiel wurden durch das Kreislaufwirt-schaftsgesetz der europäischen Union [1] die Hersteller dazu verpflichtet Rücknahmesysteme für elektrische und elektronische Geräte zu schaffen um sie einer weiteren wirtschaftlichen Nutzung oder umweltgerechten Entsorgung zugänglich zu machen. Für die umweltgerechte Entsorgung ist eine wertstoffgerechte Trennung der Produktkomponenten vorgesehen. Aus wirtschaftlichen Gründen erfolgt diese Materialtrennung meist verfahrenstechnisch durch Zerkleinern und Sortieren der Wertstoffe. Die weitere wirtschaftliche Nutzung ganzer Kompo-nenten wird, trotz hoher Einsparpotenziale [2], durch den Aufwand der Refabrikation kaum in Betracht gezogen. Denn die zerstörungsfreie Trennung kann bisher meist nur manuell und damit kostenintensiv erfolgen. In der Folge werden gerade im Bereich der Elektroschrottver-wertung häufig illegale Entsorgungswege über das außereuropäische Ausland gewählt [3]. Zur Verbesserung der Wirtschaftlichkeit der Demontage bietet oft die Automatisierung Lösun-gen. Um diesen Sektor der Automatisierung zugänglich zu machen, erfolgten bereits For-schungsaktivitäten zur Automatisierung der Demontage von Fernsehgeräten [4] und PCs [5]. Das Ergebnis dieser Studien zeigt, dass durch die hohe Variation der Produktgestalt oder aufgrund von Beschädigungen der Produkte, der [less ▲]

Detailed reference viewed: 342 (11 UL)
See detaildenmpc
Dentler, Jan Eric UL

Software (2017)

This package is providing an object oriented real-time nonlinear model predictive control (NMPC) framework which developed at the Automation & Robotics Research Group http://wwwde.uni.lu/snt/research ... [more ▼]

This package is providing an object oriented real-time nonlinear model predictive control (NMPC) framework which developed at the Automation & Robotics Research Group http://wwwde.uni.lu/snt/research/automation_robotics_research_group at the University of Luxembourg. It features a modularization for multi-agent systems which allows the on-line change of agents, control objectives, constraints and couplings, triggered by ROS-messages. [less ▲]

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See detailDerivative recovery and a posteriori error estimate for extended finite elements
Bordas, Stéphane UL; Duflot, M.

in Computer Methods in Applied Mechanics and Engineering (2007), 196(35-36), 3381-3399

This paper is the first attempt at error estimation for extended finite elements. The goal of this work is to devise a simple and effective local a posteriori error estimate for partition of unity ... [more ▼]

This paper is the first attempt at error estimation for extended finite elements. The goal of this work is to devise a simple and effective local a posteriori error estimate for partition of unity enriched finite element methods such as the extended finite element method (XFEM). In each element, the local estimator is the L2 norm of the difference between the raw XFEM strain field and an enhanced strain field computed by extended moving least squares (XMLS) derivative recovery obtained from the raw nodal XFEM displacements. The XMLS construction is tailored to the nature of the solution. The technique is applied to linear elastic fracture mechanics, in which near-tip asymptotic functions are added to the MLS basis. The XMLS shape functions are constructed from weight functions following the diffraction criterion to represent the discontinuity. The result is a very smooth enhanced strain solution including the singularity at the crack tip. Results are shown for two- and three-dimensional linear elastic fracture mechanics problems in mode I and mixed mode. The effectivity index of the estimator is close to 1 and improves upon mesh refinement for the studied near-tip problem. It is also shown that for the linear elastic fracture mechanics problems treated, the proposed estimator outperforms one of the superconvergent patch recovery technique of Zienkiewicz and Zhu, which is only C0. Parametric studies of the general performance of the estimator are also carried out. © 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailDeriving essential components of lean and industry 4.0 assessment model for manufacturing SMEs
Kolla, Sri Sudha Vijay Keshav UL; Minoufekr, Meysam UL; Plapper, Peter UL

in 52nd CIRP Conference on Manufacturing Systems (CMS) (2019), 81

Quantifying lean and ICT architecture related to Industry 4.0 is a new challenge in Small and Medium Scale Enterprises (SMEs) that needs to be addressed by both research as well as enterprises themselves ... [more ▼]

Quantifying lean and ICT architecture related to Industry 4.0 is a new challenge in Small and Medium Scale Enterprises (SMEs) that needs to be addressed by both research as well as enterprises themselves. Especially in the manufacturing sector, SMEs need to transform themselves into emerging trends such as industry 4.0 while practicing existing manufacturing philosophies such as Lean Production Systems (LPS) to be competitive in global markets. The major concern is that there are many assessment models available to measure the status of an enterprise related to either LPS or Industry 4.0. Often, these models are complex and don’t fulfill the requirements of manufacturing SMEs. On the other hand, most of the models only consider either lean or industry 4.0 elements. The outcomes of this research help to develop a hybrid model including both lean and industry 4.0 features suitable for manufacturing SMEs. The main objective of this research is to provide state of the art literature on existing assessment models and consequently map lean and industry 4.0 components to the specific characteristics of manufacturing SMEs. The paper concludes with a summary and outlook for our future research. [less ▲]

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

Doctoral thesis (2011)

Detailed reference viewed: 81 (6 UL)
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See detailDesign Automation With the Characteristics Properties Model and Property Driven Design for Redesign
Qureshi, Ahmed Jawad UL; Eisenbart, Boris UL; Dantan, Jean-Yves et al

in Abramovici, Michael, Stark, Rainer (Ed.) Smart Product Engineering (2013)

This paper presents a framework consisting of a mathematical model and an algorithm for representation, analysis and exploration of the design space in redesign problems. The framework develops and ... [more ▼]

This paper presents a framework consisting of a mathematical model and an algorithm for representation, analysis and exploration of the design space in redesign problems. The framework develops and extends the existing formalism of the Characteristics Properties Model (CPM) and Property Driven Design (PDD). A platform independent quantitative model based on formal log-ic is presented to map the characteristics and properties, as well as the relations and dependencies between them, along with the necessary conditions for solu-tion evaluation. The model is based on generalization of existing mathematical design models and is supported by the development of an algorithm enabling property driven design. The resulting framework offers a rich and flexible syn-tax and vocabulary along with a mathematical and computational tool applica-ble to mechanical product redesign. [less ▲]

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See detailDesign process ingredients: a comparison between group and individual work
Dwarakanath, S.; Blessing, Lucienne UL

in Cross, N.; Christiaans, H.; Dorst, K. (Eds.) Analysing Design Activity (1994)

In this paper a comparison is made between the design processes of an individually working designer and of a group of designers based on protocol analysis. The analysis focused on the differences and ... [more ▼]

In this paper a comparison is made between the design processes of an individually working designer and of a group of designers based on protocol analysis. The analysis focused on the differences and similarities in the ingredients of the two processes. The basic ingredients used for the analysis were: Issues, Arguments, Alternatives, Criteria, Decisions, External information, and Others. Comparisons have been made between: the group as a whole and the individual designer; the individual group members; the individual group members and the individual designer. The results provide a first step towards a better understanding of the differences between group and individual work. The paper also discusses some of the limitations of this type of study. [less ▲]

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See detailDesigning collaborative scenarios on tangible tabletop interfaces - insights from the implementation of paper prototypes in the context of a multidisciplinary design workshop
Sunnen, Patrick UL; Arend, Béatrice UL; Heuser, Svenja UL et al

in Proceedings of the 17th European Conference on Computer-Supported Cooperative Work: The International Venue on Practice-centred Computing and the Design of Cooperation Technologies - Exploratory Papers, Reports of the European Society for Socially Embedded Technologies (2019, June)

Within the context of the research project ORBIT (Overcoming Breakdowns in Teams with Interactive Tabletops), we design and study a joint problem-solving activity at an interactive tabletop, that gives ... [more ▼]

Within the context of the research project ORBIT (Overcoming Breakdowns in Teams with Interactive Tabletops), we design and study a joint problem-solving activity at an interactive tabletop, that gives participants the opportunity to develop their collaboration methods. To gain design insights for the development of a scenario soliciting participants to collaborate, we set up a multidisciplinary design workshop. During the latter, we explored and discussed three different collaborative scenarios, implemented as paper prototypes. In this paper, we report on first results gained from an exploratory analysis of the video data that was recorded in the context of this workshop. [less ▲]

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See detailDesigning Meaning to Change Consumer Behaviour: An Exploration
Waltersdorfer, Gregor UL; Gericke, Kilian UL; Blessing, Lucienne UL

in Chakrabarti, Amaresh (Ed.) ICoRD’15 – Research into Design Across Boundaries Volume 1: Theory, Research Methodology, Aesthetics, Human Factors and Education (2015)

The focus of our research is to support designers in fostering a more sustainable behaviour of consumers by creating meaning in products and services. The paper describes the results of a literature study ... [more ▼]

The focus of our research is to support designers in fostering a more sustainable behaviour of consumers by creating meaning in products and services. The paper describes the results of a literature study into the process of meaning making and the mechanisms through which meaning affects consumer behaviour. Meaning is defined as a mental representation of possible relationships. An initial model, the Meaning-Behaviour Model, is presented, integrating the mechanisms found in literature. Five possible interventions, derived from the model, show how designers can use meaning as a lever to foster enduring behavioural change. The paper contributes to the discussion of introducing meaning through design by exploring the link between meaning and behaviour. [less ▲]

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See detailDesigning Sustainable Technologies, Products and Policies
Benetto, Enrico; Gericke, Kilian UL; Guiton, Mélanie

Book published by Springer (2018)

This book provides insight into the implementation of Life Cycle approaches along the entire business value chain, supporting environmental, social and economic sustainability related to the development ... [more ▼]

This book provides insight into the implementation of Life Cycle approaches along the entire business value chain, supporting environmental, social and economic sustainability related to the development of industrial technologies, products, services and policies; and the development and management of smart agricultural systems, smart mobility systems, urban infrastructures and energy for the built environment. The book is based on papers presented at the 8th International Life Cycle Management Conference that took place from September 3-6, 2017 in Luxembourg, and which was organized by the Luxembourg Institute of Science and Technology (LIST) and the University of Luxembourg in the framework of the LCM Conference Series. [less ▲]

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See detailDesigning with Genius Loci: An Approach to Polyvocality in Interactive Heritage Interpretation
Tsenova, Violeta UL; Wood, Gavin; Kirk, David

in Multimodal Technologies and Interaction (2022), 6(6), 41

Co-design with communities interested in heritage has oriented itself towards designing for polyvocality to diversify the accepted knowledges, values and stories associated with heritage places. However ... [more ▼]

Co-design with communities interested in heritage has oriented itself towards designing for polyvocality to diversify the accepted knowledges, values and stories associated with heritage places. However, engagement with heritage theory has only recently been addressed in HCI design, resulting in some previous work reinforcing the same realities that designers set out to challenge. There is need for an approach that supports designers in heritage settings in working critically with polyvocality to capture values, knowledges, and authorised narratives and reflect on how these are negotiated and presented in the designs created. We contribute “Designing with Genius Loci” (DwGL)—our proposed approach to co-design for polyvocality. We conceptualised DwGL through long-term engagement with volunteers and staff at a UK heritage site. First, we used ongoing recruitment to incentivise participation. We held a series of making workshops to explore participants’ attitudes towards authorised narratives. We built participants’ commitments to collaboration by introducing the common goal of creating an interactive digital design. Finally, as we designed, we enacted our own commitments to the heritage research and to participants’ experiences. These four steps form the backbone of our proposed approach and serve as points of reflexivity. We applied DwGL to co-creating three designs: Un/Authorised View, SDH Palimpsest and Loci Stories, which we present in an annotated portfolio. Grounded in research through design, we reflect on working with the proposed approach and provide three lessons learned, guiding further research efforts in this design space: (1) creating a conversation between authorised and personal heritage stories; (2) designing using polyvocality negotiates voices; and (3) designs engender existing qualities and values. The proposed approach places polyvocality foremost in interactive heritage interpretation and facilitates valuable discussions between the designers and communities involved. [less ▲]

Detailed reference viewed: 26 (1 UL)
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See detailDetecting User Mode Linux Honeypots is fine ... but it's better to crash them.
Wagener, Gerard UL; Raynal, Frédéric; Dulaunoy, Alexandre et al

Scientific Conference (2008)

Detailed reference viewed: 59 (0 UL)
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See detailDetection of fluid level in bores for batch size one assembly automation using convolutional neural network
Simeth, Alexej UL; Plaßmann, Jessica; Plapper, Peter UL

in Advances in Production Management Systems. Artificial Intelligence for Sustainable and Resilient Production Systems. (2021, August 31), 632

Increased customization and shortening product life cycles pose a challenge for automation, especially in assembly. In combination with the nature of assembly tasks, which may require high level of ... [more ▼]

Increased customization and shortening product life cycles pose a challenge for automation, especially in assembly. In combination with the nature of assembly tasks, which may require high level of perception, skill, and logical thinking, these tasks are often conducted manually, especially in certain industries (e.g. furniture, power tools) or small and medium-sized enterprises. One of such tasks is the liquid level monitoring in gluing processes. Existing non-manual solutions are based on conventional and less flexible algorithms to detect the current liquid level. In production environments with highly individualized products, a need for more performant models arises. With artificial intelligence (AI) it is possible to deduct decisions from unknown multidimensional correlations in sensor data, which is a key enabler for assembly automation for products with high degree of customization. In this paper, an AI-based model is proposed to automate a gluing process in a final assembly. Images of a gluing process are taken with a camera and a convolutional neural network is used to extract images features. The features are applied to train a support vector machine classifier to identify the liquid level. The developed model is tested and validated with a Monte-Carlo-simulation and used on a demonstrator to automate a gluing process. The developed model classifies images of liquid levels with over 98% accuracy. Similar results are achieved on the demonstrator. [less ▲]

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See detailDeterministic analysis of distributed order systems using operational matrix
Duong, Pham UL

in Applied Mathematical Modelling (2016), 40(3), 1929-1940

"Recently, distributed order systems as a generalized concept of fractional order have been a" "major focus in science and engineering areas, and have rapidly extended application across a wide range of ... [more ▼]

"Recently, distributed order systems as a generalized concept of fractional order have been a" "major focus in science and engineering areas, and have rapidly extended application across a wide range of disciplines. However, only a few numerical methods are available for analyzing the distributed order systems. This paper proposes a novel numerical scheme to analyze the behavior of single input single output linear systems in the time domain with a single dis- tributed order differentiator/integrator by using operational matrix technique. The proposed method reduces different analysis problems to a system of algebraic equations by using block pulse functions, which makes it easy to handle an arbitrary input. Numerical examples were used to illustrate the accuracy and computational efficiency of the proposed method. The pro- posed method was found to be an efficient tool for analyzing linear distributed order systems." [less ▲]

Detailed reference viewed: 153 (7 UL)
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See detailDeveloping an Interactive Tabletop Mediated Activity to Induce Collaboration by Implementing Design Considerations Based on Cooperative Learning Principles
Sunnen, Patrick UL; Arend, Béatrice UL; Heuser, Svenja UL et al

in Stephanidis, Constantine; Antona, Margherita (Eds.) HCI International 2020 - Posters (2020, July)

Constructive collaboration can be a difficult matter. For this reason, we are implementing and studying an interactive-tabletop-mediated activity that aims at inducing collaboration among participants ... [more ▼]

Constructive collaboration can be a difficult matter. For this reason, we are implementing and studying an interactive-tabletop-mediated activity that aims at inducing collaboration among participants. The resulting activity ‘Orbitia’ is designed as a serious game. Participants are asked to act as a space- mining crew, which has to collect minerals with a rover and rely on a camera- drone for reconnaissance, while keeping the rover out of harm and managing limited resources. In this paper we provide an account of how we designed Orbitia’s pedagogical structuring by relying on the Johnsons’ cooperative learning approach whose fundamental concept is “positive interdependence”. More particularly, we show how we worked on resource, role and task inter- dependence to design three collaboration-inducing ‘flagship’ devices: the rover- steering-device (RSD), the item-locating-device (ILD) and the responsibility- activating-device (RAD). [less ▲]

Detailed reference viewed: 94 (2 UL)