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See detailInteraktive Transitionsforschung und Wissensgenerierung im Bereich nachhaltiges Bauen
JUNG ép. PRELLER, Bérénice UL; Affolderbach, Julia UL; Schulz, Christian UL et al

in PND online (2014), 2014(2), 1-14

Basierend auf den Erfahrungen eines internationalen Forschungsprojekts zu den institutionellen Rahmenbedingungen für Innovativität im nachhaltigen Bauen illustriert der Beitrag das Potenzial interaktiver ... [more ▼]

Basierend auf den Erfahrungen eines internationalen Forschungsprojekts zu den institutionellen Rahmenbedingungen für Innovativität im nachhaltigen Bauen illustriert der Beitrag das Potenzial interaktiver Methoden für die Produktion von »Transitionswissen«. Die frühe Einbindung von lokalen Praktikern, Unternehmern, Wissenschaftlern, politischen Entscheidungsträgern und Vertretern von Nichtregierungsorganisationen dient dabei nicht nur den Forschenden zur Exploration des jeweiligen Forschungskontexts, sondern schafft eine Plattform für produktiven Austausch von Wissen. Methodisch unterstützt durch interaktive Workshops sowie Delphi-basierte Feedback- und Validierungsrunden entsteht über die Projektlaufzeit ein wechselseitiger Lernprozess, der zusätzlich durch den Austausch von Erfahrungen aus vier Fallstudienregionen in Europa, Australien und Kanada inspiriert wird. Er liefert für alle Beteiligten wichtige Erkenntnisse über die Gestaltbarkeit von nachhaltigkeitsorientierten Transitionsprozessen im Baubereich. [less ▲]

Detailed reference viewed: 202 (12 UL)
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See detailInterdisciplinary Ignorance
Kemman, Max UL

Scientific Conference (2017)

Detailed reference viewed: 56 (9 UL)
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See detailAn Interdisciplinary Methodology to Validate Formal Representations of Legal Text Applied to the GDPR
Bartolini, Cesare UL; Lenzini, Gabriele UL; Santos, Cristiana

Scientific Conference (2018, November 12)

The modelling of a legal text into a machine-processable form, such as a list of logic formulæ, enables a semi-automatic reasoning about legal compliance but might entail some anticipation of legal ... [more ▼]

The modelling of a legal text into a machine-processable form, such as a list of logic formulæ, enables a semi-automatic reasoning about legal compliance but might entail some anticipation of legal interpretation in the modelling. The formulæ need therefore to be validated by legal experts, but it is unlikely that they are familiar with the formalism used. This calls for an interdisciplinary validation methodology to ensure that the model is legally coherent with the text it aims to represent but that could also close the communication gap between formal modellers and legal evaluators. This paper discusses such a methodology, providing an human-readable representation that preserves the formulæ's meaning but that presents them in a way that is usable by non-experts. We exemplify the methodology on a use case where Articles of the GDPR are translated in the Reified I/O logic encoded in LegalRuleML. [less ▲]

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See detailInterfence mitigation and synchronization for satellite communications
Grotz, Joel UL

Doctoral thesis (2008)

Detailed reference viewed: 103 (4 UL)
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See detailInterference Mitigation and Synchronization for Satellite Communications
Grotz, Joel UL

Book published by KTH (2008)

Within this thesis, the satellite broadcast scenario of geostationary satellites is reviewed. The densely crowded geostationary arc in the common broadcast frequencies may create significant interference ... [more ▼]

Within this thesis, the satellite broadcast scenario of geostationary satellites is reviewed. The densely crowded geostationary arc in the common broadcast frequencies may create significant interference from adjacent satellites (ASI). The possible use of multiple-input receivers and of interference processing techniques is analyzed in this specific context. In addition the synchronization problem is studied under interference limited conditions for broadcast as well as broadband satellite systems.We address fixed satellite broadcast reception with the goal of decreasing the aperture of the receiving antenna. The front-end antenna size is commonly defined by the presence of interference from adjacent satellites. A small antenna aperture leads to interference from neighboring satellites utilizing the same frequency bands. We propose a multi-input reception system with subsequent joint detection which provides reliable communication in the presence of multiple interfering signals. An iterative least square technique is adopted combining spatial and temporal processing. This approach achieves robustness against pointing errors and against changing interference scenarios. Different temporal interference processing methods are evaluated, including Minimum Mean Square Error (MMSE) based iterative soft-decision interference cancellation as well as Iterative Least Square with Projection (ILSP) based approaches, which include spatial and temporal iterations. Furthermore the potential of an additional convolutional channel decoding step in the interference cancellation mechanism is verified.Also, we demonstrate how to accurately synchronize the signals as part of the detection procedure. The technique is evaluated in a realistic simulation study representing the conditions encountered in typical broadcast scenarios.In a second part of the thesis the problem of synchronization is reviewed in the context of interference limited scenarios for broadband satellite return channels. Spectral efficiency is of great concern in the return channel of satellite based broadband systems. In recent work the feasibility of increased efficiency by reducing channel spacing below the Symbol Rate was demonstrated using joint detection and decoding for a synchronized system. We extend this work by addressing the critical synchronization problem in the presence of adjacent channel interference (ACI) which limits performance as carrier spacing is reduced.A pilot sequence aided joint synchronization scheme for a multi-frequency time division multiple access (MF-TDMA) system is proposed. Based on a maximum likelihood (ML) criterion, the channel parameters, including frequency, time and phase are jointly estimated for the channel of interest and the adjacent channels. The impact of ACI on the synchronization and detection performance is investigated. It is shown that joint channel parameter estimation outperforms single carrier synchronization with reasonable additional computational complexity in the receiver. Based on the proposed synchronization scheme in conjunction with an appropriate joint detection mechanism the carrier spacing can be reduced significantly compared to current systems providing a substantial increase in spectral efficiency. [less ▲]

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See detailAn internal version of epistemic logic
Aucher, Guillaume UL

in Studia Logica (2010), 94(1), 1-22

Representing an epistemic situation involving several agents obviously depends on the modeling point of view one takes. We start by identifying the types of modeling points of view which are logically ... [more ▼]

Representing an epistemic situation involving several agents obviously depends on the modeling point of view one takes. We start by identifying the types of modeling points of view which are logically possible. We call the one traditionally followed by epistemic logic the perfect external approach, because there the modeler is assumed to be an omniscient and external observer of the epistemic situation. In the rest of the paper we focus on what we call the internal approach, where the modeler is one of the agents involved in the situation. For this approach we propose and axiomatize a logical formalism based on epistemic logic. This leads us to formalize some intuitions about the internal approach and about its connections with the external ones. Finally, we show that our internal logic is decidable and PSPACE-complete. [less ▲]

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See detailThe Introduction of a Design Heuristics Extraction Method
Matthews, P. C.; Blessing, Lucienne UL; Wallace, K. M.

in Advanced Engineering Informatics (2002), 16

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See detailIntroduction of the European Association for Data Science
Krolak-Schwerdt, Sabine; Böhmer, Matthias UL

Scientific Conference (2015, November)

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See detailIntroduction to the special issue on data science in Europe
Flach, Peter; Spiliopoulou, Myra; Allegrezza, Serge et al

in International Journal of Data Science and Analytics (2018)

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See detailInvestigating Breakdowns in Human Robot Interaction: A Conversation Analysis Guided Single Case Study of a Human-NAO Communication in a Museum Environment
Arend, Béatrice UL; Sunnen, Patrick UL; Caire, Patrice UL

in International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering (2017), 11(5), 839-845

In a single case study, we show how a conversation analysis (CA) approach can shed light onto the sequential unfolding of human-robot interaction. Relying on video data, we are able to show that CA allows ... [more ▼]

In a single case study, we show how a conversation analysis (CA) approach can shed light onto the sequential unfolding of human-robot interaction. Relying on video data, we are able to show that CA allows us to investigate the respective turn-taking systems of humans and a NAO robot in their dialogical dynamics, thus pointing out relevant differences. Our fine grained video analysis points out occurring breakdowns and their overcoming when humans and a NAO-robot engage in a multimodally uttered multi-party communication during a sports guessing game. Our findings suggest that interdisciplinary work opens up the opportunity to gain new insights into the challenging issues of human robot communication in order to provide resources for developing mechanisms that enable complex HRI. [less ▲]

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See detailIsogeometric analysis of functionally graded carbon nanotube-reinforced composite plates using higher-order shear deformation theory
P., Phung-Van; M., Abdel-Wahab; K.M., Liew et al

in Composite Structures (2015), 123

This paper presents a simple and effective formulation based on isogeometric Analysis (IGA) and higher-order shear deformation theory (HSDT) to investigate the static and dynamic vibration behaviour of ... [more ▼]

This paper presents a simple and effective formulation based on isogeometric Analysis (IGA) and higher-order shear deformation theory (HSDT) to investigate the static and dynamic vibration behaviour of functionally graded carbon nano-reinforced composite plates. The material properties of functionally graded carbon nanotube-reinforced composites (FG-CNTRCs) are assumed to be graded through the thickness direction according to several linear distributions of the volume fraction of carbon nanotubes. The governing equation is approximated according to the HSDT model using isogeometric elements based on Non-Uniform Rational B-Spline (NURBS) basis functions. This achieves naturally any desired degree of continuity through the choice of the interpolation order, so that the method easily fulfils the C1-continuity requirement of the HSDT model. The accuracy and reliability of the proposed method is verified by comparing its numerical predictions with those of other available numerical approaches. [less ▲]

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See detailIsogeometric analysis of functionally graded plates using a refined plate theory
Nguyen-Xuan, H.; Tran, L. V.; Thai, C. H. et al

in Composites : Part B, Engineering (2014), 64

We present in this paper a simple and effective approach that incorporates isogeometric finite element analysis (IGA) with a refined plate theory (RPT) for static, free vibration and buckling analysis of ... [more ▼]

We present in this paper a simple and effective approach that incorporates isogeometric finite element analysis (IGA) with a refined plate theory (RPT) for static, free vibration and buckling analysis of functionally graded material (FGM) plates. A new inverse tangent distributed function through the plate thickness is proposed. The RPT enables us to describe the non-linear distribution of shear stresses through the plate thickness without any requirement of shear correction factors (SCF). IGA utilizes basis functions namely B-splines or non-uniform rational B-splines (NURBS) which reach easily the smoothness of any arbitrary order. It hence satisfies the C1 requirement of the RPT model. The present method approximates the displacement field with four degrees of freedom per each control point allowing an efficient solution process. [less ▲]

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See detailIsogeometric Analysis of Laminated Composite Plates Using the Higher-Order Shear Deformation Theory
Thai, Chien H.; Nguyen-Xuan, H.; Bordas, Stéphane UL et al

in Mechanics of Advanced Materials and Structures (2015), 22(6), 451-469

Isogeometric analysis (IGA) aims at simplifying the computer aided design (CAD) and computer aided engineering (CAE) pipeline by using the same functions to describe the geometry (CAD) and the unknown ... [more ▼]

Isogeometric analysis (IGA) aims at simplifying the computer aided design (CAD) and computer aided engineering (CAE) pipeline by using the same functions to describe the geometry (CAD) and the unknown fields (Analysis). IGA can be based on a variety of CAD descriptions, the most widely used today being non-uniform rational B-splines (NURBS). In this article, the suitability of NURBS-based isogeometric analysis within a third-order shear deformation theory for the simulation of the static, dynamic, and buckling response of laminated composite plates is investigated. The method employs NURBS basis functions to both represent the geometry (exactly) and the unknown field variables. One of the main advantages of the present method is directly inherited from IGA, that is to easily increase the approximation order. To avoid using a shear correction factor, a third-order shear deformation theory (TSDT) is introduced. It requires C1-continuity of generalized displacements and the NURBS basis functions are well suited for this requirement. Several numerical examples are used to demonstrate the performance of the present method compared with other published ones. [less ▲]

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See detailIsogeometric analysis of thin Reissner-Mindlin plates and shells: Locking phenomena and generalized local B-bar method
Hu, Qingyuan UL; Xia, Yang; Natarajan, Sundararajan et al

E-print/Working paper (2017)

We propose a generalized local $\bar{B}$ framework, addressing locking in degenerated Reissner-Mindlin plate and shell formulations in the context of isogeometric analysis. Parasitic strain components are ... [more ▼]

We propose a generalized local $\bar{B}$ framework, addressing locking in degenerated Reissner-Mindlin plate and shell formulations in the context of isogeometric analysis. Parasitic strain components are projected onto the physical space locally, i.e. at the element level, using a least-squares approach. The formulation is general and allows the flexible utilization of basis functions of different order as the projection bases. The present formulation is much cheaper computationally than the global $\bar{B}$ method. Through numerical examples, we show the consistency of the scheme, although the method is not Hu-Washizu variationally consistent. The numerical examples show that the proposed formulation alleviates locking and yields good accuracy for various thicknesses, even for slenderness ratios of $1 \times 10^5$, and has the ability to capture deformations of thin shells using relatively coarse meshes. From the detailed numerical study, it can be opined that the proposed method is less sensitive to locking and mesh distortion. [less ▲]

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See detailIsogeometric analysis using polynomial splines over hierarchical T-meshes for two-dimensional elastic solids
Nguyen-Thanh, N.; Nguyen-Xuan, H.; Bordas, Stéphane UL et al

in Computer Methods in Applied Mechanics & Engineering (2011), 200(21-22), 1892-1908

Isogeometric analysis has become a powerful alternative to standard finite elements due to its flexibility in handling complex geometries. One of the major drawbacks of NURBS-based isogeometric finite ... [more ▼]

Isogeometric analysis has become a powerful alternative to standard finite elements due to its flexibility in handling complex geometries. One of the major drawbacks of NURBS-based isogeometric finite elements is the inefficiency of local refinement. In this study, we present an alternative to NURBS-based isogeometric analysis that allows for local refinement. The idea is based on polynomial splines and exploits the flexibility of T-meshes for local refinement. The shape functions satisfy important properties such as non-negativity, local support and partition of unity. Several numerical examples are used to demonstrate the reliability of the present method. [less ▲]

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See detailIsogeometric analysis: an overview and computer implementation aspects
Nguyen, Vinh-Phu; Anitescu, Cosmin; Bordas, Stéphane UL et al

Learning material (2013)

Isogeometric analysis (IGA) represents a recently developed technology in computational mechanics that offers the possibility of integrating methods for analysis and Computer Aided Design (CAD) into a ... [more ▼]

Isogeometric analysis (IGA) represents a recently developed technology in computational mechanics that offers the possibility of integrating methods for analysis and Computer Aided Design (CAD) into a single, unified process. The implications to practical engineering design scenarios are profound, since the time taken from design to analysis is greatly reduced, leading to dramatic gains in efficiency. The tight coupling of CAD and analysis within IGA requires knowledge from both fields and it is one of the goals of the present paper to outline much of the commonly used notation. In this manuscript, through a clear and simple Matlab⃝R implementation, we present an introduction to IGA applied to the Finite Element (FE) method and related computer implementation aspects. Furthermore, implemen- tation of the extended IGA which incorporates enrichment functions through the partition of unity method (PUM) is also presented, where several examples for both two-dimensional and three-dimensional fracture are illustrated. The open source Matlab⃝R code which accompanies the present paper can be applied to one, two and three-dimensional problems for linear elasticity, linear elastic fracture mechanics, structural mechanics (beams/plates/shells including large displacements and rotations) and Poisson problems with or without enrichment. The B ́ezier extraction concept that allows FE analysis to be performed efficiently on T-spline geometries is also incorporated. The article includes a summary of recent trends and developments within the field of IGA. [less ▲]

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See detailIsogeometric and multi-scale fracture
Bordas, Stéphane UL

Presentation (2015, July 31)

Detailed reference viewed: 160 (10 UL)