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See detailSimultaneous finite element analysis of circuit-integrated piezoelectric energy harvesting from fluid-structure interaction
Ravi, Srivathsan; Zilian, Andreas UL

in Mechanical Systems & Signal Processing (2019), 114

Flow-driven piezoelectric energy harvesting is a strongly coupled multiphysics phenomenon that involves complex three-way interaction between the fluid flow, the electromechanical effect of the ... [more ▼]

Flow-driven piezoelectric energy harvesting is a strongly coupled multiphysics phenomenon that involves complex three-way interaction between the fluid flow, the electromechanical effect of the piezoelectric material mounted on a deformable substrate structure and the controlling electrical circuit. High fidelity computational solution approaches are essential for the analysis of flow-driven energy harvesters in order to capture the main physical aspects of the coupled problem and to accurately predict the power output of a harvester. While there are some phenomenological and numerical models for flow-driven harvesters reported in the literature, a fully three-dimensional strongly coupled model has not yet been developed, especially in the context of flow-driven energy harvesting. The weighted residuals method is applied to establish a mixed integral equation describing the incompressible Newtonian flow, elastic substrate structure, piezoelectric patch, equipotential electrode and attached electric circuit that form the multiphysics fluid-structure interaction problem. A monolithic numerical solution method is derived that provides consistent and simultaneous solution to all physical fields as well as to fluid mesh deformation. The approximate solution is based on a mixed space-time finite element discretization with static condensation of the auxiliary fields. The discontinuous Galerkin method is utilized for integrating the monolithic model in time. The proposed solution scheme is illustrated in the example of a lid driven cavity with a flexible piezoelectric bottom wall, demonstrating quantification of the amount of electrical energy extractable from fluid flow by means of a piezoelectric harvester device. The results indicate that in order to make reliable predictions on the power output under varying operational states, the realization of strong multiphysics coupling is required for the mathematical model as well as the numerical solution scheme to capture the characteristics of flow-driven energy harvesters. [less ▲]

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See detailReductions of elliptic curves
Perucca, Antonella UL

in Proceedings of the Roman Number Theory Association (2019), 4

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See detailStriking a balance between competitiveness and social fairness: what can we expect from the European Pillar of Social Rights?
Muñoz, Susana UL

in Chiocchetti, Paolo; Allemand, Frédéric (Eds.) Competitiveness and Solidarity in the European Union: Interdisciplinary Perspectives (2019)

The solemnly proclaimed European Pillar of Social Rights provides a meaningful response to the process of building a deeper, fairer European Union in the aftermath of the crisis. This chapter aims to ... [more ▼]

The solemnly proclaimed European Pillar of Social Rights provides a meaningful response to the process of building a deeper, fairer European Union in the aftermath of the crisis. This chapter aims to provide a critical assessment of the nature, scope, rationale, purpose, content and effectiveness of the Pillar in the light of its potential contribution to foster social fairness and competitiveness in the EU. The Pillar complements and develops the EU’s social acquis and reinforces standards which may provide a fairer and more socially-balanced competitiveness in the EU. Progress has been made, but further efforts are needed to build a sense of common purpose to strengthen the social foundations of the Union. [less ▲]

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See detailSocial Change for Sustainable Localized Food Sovereignty. Convergence between Prosumers and Ethical Entrepreneurs.
Reckinger, Rachel UL

in Sociologia del Lavoro (2018), 152(4),

Recently, some resourceful community-driven initiatives for local food production and retail have arisen in Luxembourg, where low organic agricultural rates are paradoxically paired with high consumer ... [more ▼]

Recently, some resourceful community-driven initiatives for local food production and retail have arisen in Luxembourg, where low organic agricultural rates are paradoxically paired with high consumer demands. This niche of social innovators is combining agro-ecology with circular economy practices. Four cases of alternative food networks are of interest – studied with qualitative interviews and participant observation. One has been established since the 1980s with 200 employees, partly in social insertion measures. The more recent and smaller initiatives are characterized by a cooperative governance, a community-supported agricultural outlook, hands-on workshops and time-banks, all enabled by social media. These initiatives are more radical in their agro-ecological or permaculture practices, focusing on regenerative land use without relying on imports and fostering the integration of consumers with varying degrees of prosumer involvement, as a politicized step further than mere (possibly industrialized) organic production. [less ▲]

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See detailSequential Resource Distribution Technique for Multi-User OFDM-SWIPT based Cooperative Networks
Gautam, Sumit UL; Lagunas, Eva UL; Chatzinotas, Symeon UL et al

Scientific Conference (2018, December)

In this paper, we investigate resource allocation and relay selection in a dual-hop orthogonal frequency division multiplexing (OFDM)-based multi-user network where amplify-and-forward (AF) enabled relays ... [more ▼]

In this paper, we investigate resource allocation and relay selection in a dual-hop orthogonal frequency division multiplexing (OFDM)-based multi-user network where amplify-and-forward (AF) enabled relays facilitate simultaneous wireless information and power transfer (SWIPT) to the end-users. In this context, we address an optimization problem to maximize the end-users’ sum-rate subjected to transmit power and harvested energy constraints. Furthermore, the problem is formulated for both time-switching (TS) and power-splitting (PS) SWIPT schemes.We aim at optimizing the users’ SWIPT splitting factors as well as sub-carrier–destination assignment, sub-carrier pairing, and relay–destination coupling metrics. This kind of joint evaluation is combinatorial in nature with non-linear structure involving mixed-integer programming. In this vein, we propose a sub-optimal low complex sequential resource distribution (SRD) method to solve the aforementioned problem. The performance of the proposed SRD technique is compared with a semi-random resource allocation and relay selection approach. Simulation results reveal the benefits of the proposed design under several parameter values with various operating conditions to illustrate the efficiency of SWIPT schemes for the proposed techniques. [less ▲]

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See detailHITECS: A UML Profile and Analysis Framework for Hardware-in-the-Loop Testing of Cyber Physical Systems
Shin, Seung Yeob UL; Chaouch, Karim UL; Nejati, Shiva UL et al

in Proceedings of ACM/IEEE 21st International Conference on Model Driven Engineering Languages and Systems (MODELS’18) (2018, October)

Hardware-in-the-loop (HiL) testing is an important step in the development of cyber physical systems (CPS). CPS HiL test cases manipulate hardware components, are time-consuming and their behaviors are ... [more ▼]

Hardware-in-the-loop (HiL) testing is an important step in the development of cyber physical systems (CPS). CPS HiL test cases manipulate hardware components, are time-consuming and their behaviors are impacted by the uncertainties in the CPS environment. To mitigate the risks associated with HiL testing, engineers have to ensure that (1) HiL test cases are well-behaved, i.e., they implement valid test scenarios and do not accidentally damage hardware, and (2) HiL test cases can execute within the time budget allotted to HiL testing. This paper proposes an approach to help engineers systematically specify and analyze CPS HiL test cases. Leveraging the UML profile mechanism, we develop an executable domain-specific language, HITECS, for HiL test case specification. HITECS builds on the UML Testing Profile (UTP) and the UML action language (Alf). Using HITECS, we provide analysis methods to check whether HiL test cases are well-behaved, and to estimate the execution times of these test cases before the actual HiL testing stage. We apply HITECS to an industrial case study from the satellite domain. Our results show that: (1) HITECS is feasible to use in practice; (2) HITECS helps engineers define more complete and effective well-behavedness assertions for HiL test cases, compared to when these assertions are defined without systematic guidance; (3) HITECS verifies in practical time that HiL test cases are well-behaved; and (4) HITECS accurately estimates HiL test case execution times. [less ▲]

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See detailEnabling Model Testing of Cyber-Physical Systems
Gonzalez Perez, Carlos Alberto UL; Varmazyar, Mojtaba UL; Nejati, Shiva UL et al

in Proceedings of ACM/IEEE 21st International Conference on Model Driven Engineering Languages and Systems (MODELS’18) (2018, October)

Applying traditional testing techniques to Cyber-Physical Systems (CPS) is challenging due to the deep intertwining of software and hardware, and the complex, continuous interactions between the system ... [more ▼]

Applying traditional testing techniques to Cyber-Physical Systems (CPS) is challenging due to the deep intertwining of software and hardware, and the complex, continuous interactions between the system and its environment. To alleviate these challenges we propose to conduct testing at early stages and over executable models of the system and its environment. Model testing of CPSs is however not without difficulties. The complexity and heterogeneity of CPSs renders necessary the combination of different modeling formalisms to build faithful models of their different components. The execution of CPS models thus requires an execution framework supporting the co-simulation of different types of models, including models of the software (e.g., SysML), hardware (e.g., SysML or Simulink), and physical environment (e.g., Simulink). Furthermore, to enable testing in realistic conditions, the co-simulation process must be (1) fast, so that thousands of simulations can be conducted in practical time, (2) controllable, to precisely emulate the expected runtime behavior of the system and, (3) observable, by producing simulation data enabling the detection of failures. To tackle these challenges, we propose a SysML-based modeling methodology for model testing of CPSs, and an efficient SysML-Simulink co-simulation framework. Our approach was validated on a case study from the satellite domain. [less ▲]

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See detailPreventing and Resolving Conflicts of Jurisdiction in EU Criminal Law
Ligeti, Katalin UL; Robinson, Gavin UL; European Law Institute

Book published by Oxford University Press (2018)

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See detailTUNA: TUning Naturalness-based Analysis
Jimenez, Matthieu UL; Cordy, Maxime UL; Le Traon, Yves UL et al

in 34th IEEE International Conference on Software Maintenance and Evolution, Madrid, Spain, 26-28 September 2018 (2018, September 26)

Natural language processing techniques, in particular n-gram models, have been applied successfully to facilitate a number of software engineering tasks. However, in our related ICSME ’18 paper, we have ... [more ▼]

Natural language processing techniques, in particular n-gram models, have been applied successfully to facilitate a number of software engineering tasks. However, in our related ICSME ’18 paper, we have shown that the conclusions of a study can drastically change with respect to how the code is tokenized and how the used n-gram model is parameterized. These choices are thus of utmost importance, and one must carefully make them. To show this and allow the community to benefit from our work, we have developed TUNA (TUning Naturalness-based Analysis), a Java software artifact to perform naturalness-based analyses of source code. To the best of our knowledge, TUNA is the first open- source, end-to-end toolchain to carry out source code analyses based on naturalness. [less ▲]

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See detailKünstliche Intelligenz - die nächste Revolution (The Artificial Intelligence Revolution)
Glauner, Patrick UL

in Plugmann, Philipp (Ed.) Innovationsumgebungen gestalten (2018)

Es vergeht mittlerweile kein Tag, an welchem wir nicht von künstlicher Intelligenz (KI) (Artificial Intelligence (AI)) hören: autonom fahrende Autos, Spamfilter, Siri, Schachcomputer, Killerroboter und ... [more ▼]

Es vergeht mittlerweile kein Tag, an welchem wir nicht von künstlicher Intelligenz (KI) (Artificial Intelligence (AI)) hören: autonom fahrende Autos, Spamfilter, Siri, Schachcomputer, Killerroboter und vieles mehr. Was genau steckt jedoch hinter KI? In diesem Kapitel bieten wir einen Überblick zu KI und stellen moderne KI-Anwendungen vor. Anschließend stellen wir ein Innovationsökosystem vor, in dem wir momentan ein Forschungsprojekt zur Erkennung von Elektrizitätsdiebstahl in Entwicklungs- und Schwellenländern mit Hilfe von KI betreiben. [less ▲]

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See detailOn the impact of tokenizer and parameters on N-gram based Code Analysis
Jimenez, Matthieu UL; Cordy, Maxime UL; Le Traon, Yves UL et al

Scientific Conference (2018, September)

Recent research shows that language models, such as n-gram models, are useful at a wide variety of software engineering tasks, e.g., code completion, bug identification, code summarisation, etc. However ... [more ▼]

Recent research shows that language models, such as n-gram models, are useful at a wide variety of software engineering tasks, e.g., code completion, bug identification, code summarisation, etc. However, such models require the appropriate set of numerous parameters. Moreover, the different ways one can read code essentially yield different models (based on the different sequences of tokens). In this paper, we focus on n- gram models and evaluate how the use of tokenizers, smoothing, unknown threshold and n values impact the predicting ability of these models. Thus, we compare the use of multiple tokenizers and sets of different parameters (smoothing, unknown threshold and n values) with the aim of identifying the most appropriate combinations. Our results show that the Modified Kneser-Ney smoothing technique performs best, while n values are depended on the choice of the tokenizer, with values 4 or 5 offering a good trade-off between entropy and computation time. Interestingly, we find that tokenizers treating the code as simple text are the most robust ones. Finally, we demonstrate that the differences between the tokenizers are of practical importance and have the potential of changing the conclusions of a given experiment. [less ▲]

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See detailModel-driven Run-time Enforcement of Complex Role-based Access Control Policies
Ben Fadhel, Ameni UL; Bianculli, Domenico UL; Briand, Lionel UL

in Proceeding of the 2018 33rd ACM/IEEE International Conference on Automated Software Engineering (ASE ’18) (2018, September)

A Role-based Access Control (RBAC) mechanism prevents unauthorized users to perform an operation, according to authorization policies which are defined on the user’s role within an enterprise. Several ... [more ▼]

A Role-based Access Control (RBAC) mechanism prevents unauthorized users to perform an operation, according to authorization policies which are defined on the user’s role within an enterprise. Several models have been proposed to specify complex RBAC policies. However, existing approaches for policy enforcement do not fully support all the types of policies that can be expressed in these models, which hinders their adoption among practitioners. In this paper we propose a model-driven enforcement framework for complex policies captured by GemRBAC+CTX, a comprehensive RBAC model proposed in the literature. We reduce the problem of making an access decision to checking whether a system state (from an RBAC point of view), expressed as an instance of the GemRBAC+CTX model, satisfies the constraints corresponding to the RBAC policies to be enforced at run time. We provide enforcement algorithms for various types of access requests and events, and a prototype tool (MORRO) implementing them. We also show how to integrate MORRO into an industrial Web application. The evaluation results show the applicability of our approach on a industrial system and its scalability with respect to the various parameters characterizing an AC configuration. [less ▲]

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See detailRare coding variants in genes encoding GABAA receptors in genetic generalised epilepsies: an exome-based case-control study
May, Patrick UL; Girard, Simon; Harrer, Merle et al

in Lancet Neurology (2018), 17(8), 699-708

Background Genetic generalised epilepsy is the most common type of inherited epilepsy. Despite a high concordance rate of 80% in monozygotic twins, the genetic background is still poorly understood. We ... [more ▼]

Background Genetic generalised epilepsy is the most common type of inherited epilepsy. Despite a high concordance rate of 80% in monozygotic twins, the genetic background is still poorly understood. We aimed to investigate the burden of rare genetic variants in genetic generalised epilepsy. Methods For this exome-based case-control study, we used three different genetic generalised epilepsy case cohorts and three independent control cohorts, all of European descent. Cases included in the study were clinically evaluated for genetic generalised epilepsy. Whole-exome sequencing was done for the discovery case cohort, a validation case cohort, and two independent control cohorts. The replication case cohort underwent targeted next-generation sequencing of the 19 known genes encoding subunits of GABAA receptors and was compared to the respective GABAA receptor variants of a third independent control cohort. Functional investigations were done with automated two-microelectrode voltage clamping in Xenopus laevis oocytes. Findings Statistical comparison of 152 familial index cases with genetic generalised epilepsy in the discovery cohort to 549 ethnically matched controls suggested an enrichment of rare missense (Nonsyn) variants in the ensemble of 19 genes encoding GABAA receptors in cases (odds ratio [OR] 2·40 [95% CI 1·41–4·10]; pNonsyn=0·0014, adjusted pNonsyn=0·019). Enrichment for these genes was validated in a whole-exome sequencing cohort of 357 sporadic and familial genetic generalised epilepsy cases and 1485 independent controls (OR 1·46 [95% CI 1·05–2·03]; pNonsyn=0·0081, adjusted pNonsyn=0·016). Comparison of genes encoding GABAA receptors in the independent replication cohort of 583 familial and sporadic genetic generalised epilepsy index cases, based on candidate-gene panel sequencing, with a third independent control cohort of 635 controls confirmed the overall enrichment of rare missense variants for 15 GABAA receptor genes in cases compared with controls (OR 1·46 [95% CI 1·02–2·08]; pNonsyn=0·013, adjusted pNonsyn=0·027). Functional studies for two selected genes (GABRB2 and GABRA5) showed significant loss-of-function effects with reduced current amplitudes in four of seven tested variants compared with wild-type receptors. Interpretation Functionally relevant variants in genes encoding GABAA receptor subunits constitute a significant risk factor for genetic generalised epilepsy. Examination of the role of specific gene groups and pathways can disentangle the complex genetic architecture of genetic generalised epilepsy. [less ▲]

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See detailLes blockchains en 50 questions: comprendre le fonctionnement et les enjeux de cette technologie innovante
Dumas, J.-G.; Lafourcade, P.; Tichit, A. et al

Book published by Dunod - 1er (2018)

Depuis l’apparition de bitcoin, les innovations liées à la blockchain sont en plein essor. Ce livre tente d'expliquer le fonctionnement de cette technologie innovante mais aussi ses applications au ... [more ▼]

Depuis l’apparition de bitcoin, les innovations liées à la blockchain sont en plein essor. Ce livre tente d'expliquer le fonctionnement de cette technologie innovante mais aussi ses applications au travers de 50 questions comme: • Qu’est-ce qu’une blockchain ? • Quel est le lien entre le bitcoin et les blokchains ? • Qui sont les mineurs et que font-ils ? • Quelle est aujourd’hui la part des cryptomonnaies dans l’économie mondiale ? • Qu’est-ce qu’un smart contract (contrat intelligent) ? • Peut-on faire une blockchain sans bloc ? • Comment les blockchains vont-elles révolutionner le monde ? Voici quelques-unes des questions dont vous trouverez les réponses dans ce livre [less ▲]

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See detailResource Allocation and Relay Selection for Multi-User OFDM-Based Cooperative Networks with SWIPT
Gautam, Sumit UL; Lagunas, Eva UL; Chatzinotas, Symeon UL et al

Scientific Conference (2018, August)

In this paper, we investigate resource allocation and relay selection in a two-hop relay-assisted multi-user network, where the end users support Simultaneous Wireless Information and Power Transfer ... [more ▼]

In this paper, we investigate resource allocation and relay selection in a two-hop relay-assisted multi-user network, where the end users support Simultaneous Wireless Information and Power Transfer (SWIPT). In particular, we consider single source assisted by a set of spatially distributed relays able to amplify-and-forward orthogonal frequency division multiplexing (OFDM) signals carrying both data and power at the same time. The users are assumed to implement a power splitting technique where the received signal is orthogonally split in two streams of different power levels, where one signal stream is sent to the power harvesting module while the other is converted to baseband for information decoding. We aim at optimizing the users’ power splitting ratios as well as the relay, carrier and power assignment so that the end-users’ sum-rate is maximized subject to transmitted and harvested power constraints. Such joint optimization is combinatorial in nature with a non-convex structure. Therefore, we present a sub-optimal low complex solution based on the harmonic mean of the two-hop relay channel coefficients. Simulation results reveal that the proposed algorithm provides significant performance gains in comparison with a semi-random resource allocation and relay selection approach. [less ▲]

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See detailAutomated Extraction of Semantic Legal Metadata Using Natural Language Processing
Sleimi, Amin UL; Sannier, Nicolas UL; Sabetzadeh, Mehrdad UL et al

in the 26th IEEE International Requirements Engineering Conference, Banff, Alberta, 20-24 August 2018 (2018, August)

[Context] Semantic legal metadata provides information that helps with understanding and interpreting the meaning of legal provisions. Such metadata is important for the systematic analysis of legal ... [more ▼]

[Context] Semantic legal metadata provides information that helps with understanding and interpreting the meaning of legal provisions. Such metadata is important for the systematic analysis of legal requirements. [Objectives] Our work is motivated by two observations: (1) The existing requirements engineering (RE) literature does not provide a harmonized view on the semantic metadata types that are useful for legal requirements analysis. (2) Automated support for the extraction of semantic legal metadata is scarce, and further does not exploit the full potential of natural language processing (NLP). Our objective is to take steps toward addressing these limitations. [Methods] We review and reconcile the semantic legal metadata types proposed in RE. Subsequently, we conduct a qualitative study aimed at investigating how the identified metadata types can be extracted automatically. [Results and Conclusions] We propose (1) a harmonized conceptual model for the semantic metadata types pertinent to legal requirements analysis, and (2) automated extraction rules for these metadata types based on NLP. We evaluate the extraction rules through a case study. Our results indicate that the rules generate metadata annotations with high accuracy. [less ▲]

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