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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 detailModel-Driven Trace Diagnostics for Pattern-based Temporal Specifications
Dou, Wei UL; Bianculli, Domenico UL; Briand, Lionel UL

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

Offline trace checking tools check whether a specification holds on a log of events recorded at run time; they yield a verification verdict (typically a boolean value) when the checking process ends. When ... [more ▼]

Offline trace checking tools check whether a specification holds on a log of events recorded at run time; they yield a verification verdict (typically a boolean value) when the checking process ends. When the verdict is false, a software engineer needs to diagnose the property violations found in the trace in order to understand their cause and, if needed, decide for corrective actions to be performed on the system. However, a boolean verdict may not be informative enough to perform trace diagnostics, since it does not provide any useful information about the cause of the violation and because a property can be violated for multiple reasons. The goal of this paper is to provide a practical and scalable so- lution to solve the trace diagnostics problem, in the settings of model-driven trace checking of temporal properties expressed in TemPsy, a pattern-based specification language. The main contributions of the paper are: a model-driven approach for trace diagnostics of pattern-based temporal properties expressed in TemPsy, which relies on the evaluation of OCL queries on an instance of a trace meta-model; the implementation of this trace diagnostics procedure in the TemPsy-Report tool; the evaluation of the scalability of TemPsy-Report, when used for the diagnostics of violations of real properties derived from a case study of our industrial partner. The results show that TemPsy-Report is able to collect diagnostic information from large traces (with one million events) in less than ten seconds; TemPsy-Report scales linearly with respect to the length of the trace and keeps approximately constant performance as the number of violations increases. [less ▲]

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See detailSecurity, reliability and regulation compliance in Ultrascale Computing System
Bouvry, Pascal UL; Varrette, Sébastien UL; Wasim, Muhammad Umer UL et al

in Carretero, J.; Jeannot, E. (Eds.) Ultrascale Computing Systems (2018)

Ultrascale Computing Systems (UCSs) are envisioned as large-scale complex systems joining parallel and distributed computing systems that will be two to three orders of magnitude larger than today’s ... [more ▼]

Ultrascale Computing Systems (UCSs) are envisioned as large-scale complex systems joining parallel and distributed computing systems that will be two to three orders of magnitude larger than today’s systems (considering the number of Central Process Unit (CPU) cores). It is very challenging to find sustainable solutions for UCSs due to their scale and a wide range of possible applications and involved technologies. For example, we need to deal with heterogeneity and cross fertilization among HPC, large-scale distributed systems, and big data management. One of the challenges regarding sustainable UCSs is resilience. Another one, which attracted less interest in the literature but becomes more and more crucial with the expected convergence with the Cloud computing paradigm, is the notion of regulation in such system to assess the Quality of Service (QoS) and Service Level Agreement (SLA) proposed for the use of these platforms. This chapter covers both aspects through the reproduction of two articles: [1] and [2]. [less ▲]

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See detailA Full-Cost Model for Estimating the Energy Consumption of Computing Infrastructures
Orgerie, Anne-Cecile; Varrette, Sébastien UL

in Carretero, J.; Jeannot, E. (Eds.) Ultrascale Computing Systems (2018)

Since its advent in the middle of the 2000’s, the Cloud Computing (CC) paradigm is increasingly advertised as a price-effective solution to many IT problems. This seems reasonable if we exclude the pure ... [more ▼]

Since its advent in the middle of the 2000’s, the Cloud Computing (CC) paradigm is increasingly advertised as a price-effective solution to many IT problems. This seems reasonable if we exclude the pure performance point of view as many studies highlight a non-negligible overhead induced by the virtualization layer at the heart of every Cloud middleware when subjected to an High Performance Computing (HPC) workload. When this is the case, traditional HPC and Ultrascale computing systems are required, and then comes the question of the real cost-effectiveness, especially when comparing to instances offered by the Cloud providers. In this section, and inspired by the work proposed in [1], we propose a Total Cost of Ownership (TCO) analysis of an in-house academic HPC facility of medium-size (in particular the one operated at the University of Luxembourg since 2007, or within the Grid’5000 project [2]), and compare it with the investment that would have been required to run the same platform (and the same workload) over a competitive Cloud IaaS offer. [less ▲]

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See detailReport: The European Commission's e-Evidence Proposals
Robinson, Gavin UL

in European Data Protection Law Review (2018), (3),

In April 2018, the European Commission presented a legislative package intended to enable, foster and formalise cross-border access by national judicial authorities to electronic evidence controlled by ... [more ▼]

In April 2018, the European Commission presented a legislative package intended to enable, foster and formalise cross-border access by national judicial authorities to electronic evidence controlled by private service providers.1 In particular the public-private character of the ‘cooperation’ envisaged in the proposed set-up raises several questions at the interface of criminal procedure and data protection law. This report provides a brief overview of the proposed EUlegislation and an introduction to themost salient attendant legal and policy-related issues. [less ▲]

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See detailShared Access Satellite-Terrestrial Reconfigurable Backhaul Network Enabled by Smart Antennas at MmWave Band
Artiga, Xavier; Pérez-Neira; Baranda et al

in IEEE Network (2018)

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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)

Detailed reference viewed: 21 (6 UL)
See detailForum Choice and Cybercrime
Robinson, Gavin UL

in Ligeti, Katalin; Robinson, Gavin; European Law Institute (Eds.) Preventing and Resolving Conflicts of Jurisdiction in EU Criminal Law (2018)

Detailed reference viewed: 6 (1 UL)
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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 detailVerlet buffer for broad phase interaction detection in Discrete Element Method
Mainassara Chekaraou, Abdoul Wahid UL; Rousset, Alban UL; Besseron, Xavier UL et al

Poster (2018, September 24)

The Extended Discrete Element Method (XDEM) is a novel and innovative numerical simulation technique that extends the dynamics of granular materials or particles as described through the classical ... [more ▼]

The Extended Discrete Element Method (XDEM) is a novel and innovative numerical simulation technique that extends the dynamics of granular materials or particles as described through the classical discrete element method (DEM) by additional properties such as the thermodynamic state, stress/strain for each particle. Such DEM simulations used by industries to set up their experimental processes are complexes and heavy in computation time. Therefore, simulations have to be precise, efficient and fast in order to be able to process hundreds of millions of particles. To tackle this issue, such DEM simulations are usually parallelized with MPI. One of the most expensive computation parts of a DEM simulation is the collision detection of particles. It is classically divided into two steps: the broad phase and the narrow phase. The broad phase uses simplified bounding volumes to perform an approximated but fast collision detection. It returns a list of particle pairs that could interact. The narrow phase is applied to the result of the broad phase and returns the exact list of colliding particles. The goal of this research is to apply a Verlet buffer method to (X)DEM simulations regardless of which broad phase algorithm is used. We rely on the fact that such DEM simulations are temporal coherent: the neighborhood only changes slightly from the last time-step to the current time-step. We use the Verlet buffer method to extend the list of pairs returned by the broad phase by stretching the particles bounding volume with an extension range. This allows re-using the result of the broad phase for several time-steps before an update is required once again and thereby its reduce the number of times the broad phase is executed. We have implemented a condition based on particles displacements to ensure the validity of the broad phase: a new one is executed to update the list of colliding particles only when necessary. This guarantees identical results because approximations introduced in the broad phase by our approach are corrected in the narrow phase which is executed at every time-steps anyway. We perform an extensive study to evaluate the influence of the Verlet extension range on the performance of the execution in terms of computation time and memory consumption. We consider different test-cases, partitioners (ORB, Zoltan, METIS, SCOTCH, ...), broad phase algorithms (Link cell, Sweep and prune, ...) and grid configurations (fine, coarse), sequential and parallel (up to 280 cores). While a larger Verlet buffer increases the cost of the broad phase and narrow phase, it also allows skipping a significant number of broad phase execution (> 99 \%). As a consequence, our first results show that this approach can speeds up the total .execution time up to a factor of 5 for sequential executions, and up to a factor of 3 parallel executions on 280 cores while maintaining a reasonable memory consumption. [less ▲]

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See detailTeachers´ attitudes towards inclusion: Effects of a training module
Pit-Ten Cate, Ineke UL; Krischler, Mireille Gilberte Pauline UL

Scientific Conference (2018, September 17)

The success of implementing inclusive practice depends on teachers´ competence as well as their attitudes. Attitudes are defined as psychological tendencies expressed by evaluating a particular entity ... [more ▼]

The success of implementing inclusive practice depends on teachers´ competence as well as their attitudes. Attitudes are defined as psychological tendencies expressed by evaluating a particular entity with some degree of favor or disfavor. Research has provided mixed results concerning teachers´ attitudes toward students with SEN and inclusive practice, whereby teachers generally have more positive attitudes toward the inclusion of students with mild SEN than toward students with complex needs. Training, especially modules focusing on the cognitive processes underlying judgment, can facilitate positive change in attitudes toward inclusion of students with SEN. In a pre–post-test design, data were collected for a sample of 33 experienced primary school teachers attending a course (2x4hr) on inclusion with a focus on the role of attitudes in decision-making and behavior. We assessed general attitudes toward the inclusion of students with SEN as well as teachers´ emotional reactions, stereotypes and behavioural intentions. Results of a repeated measures ANOVA, with time (pre vs. post) and general attitude toward inclusion (4 subscales) as within group factors only showed a main effect for attitudes, reflecting variations between the subscale scores. The training course did not result in changes in general attitudes. Further analyses revealed a positive pre-post course change in teachers´ emotional reactions concerning the inclusion of a student with SEN in their class. Teachers´ stereotype ratings indicated they perceived students with learning difficulties as less competent but warm, whereas students with challenging behavior were perceived as relatively competent but average in warmth. Finally, teachers´ behavioral intentions shifted from focusing on finding solutions within the classroom to more cooperation with colleagues, parents and experts to provide the best support for the student with SEN. In sum, the training course impacted both the affective and conative components of attitudes, whereas general attitudes toward inclusion remained unchanged. [less ▲]

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See detailChanges in preservice teachers´ attitudes toward inclusion: the role of competence
Pit-Ten Cate, Ineke UL; Krischler, Mireille Gilberte Pauline UL

Scientific Conference (2018, September 13)

Following policies to promote a more equitable and inclusive educational system, the question arises how to prepare teachers to accommodate an increasingly heterogeneous student population. As teachers´ ... [more ▼]

Following policies to promote a more equitable and inclusive educational system, the question arises how to prepare teachers to accommodate an increasingly heterogeneous student population. As teachers´ competence concerning inclusion is grounded in their training (e.g. Baker-Ericzen et al. 2009), courses focussing on inclusion as an educational practice could reduce uncertainties (e.g. Carroll et al. 2003). However, inclusion not only depends on teachers´ competence but also on their attitudes. Teachers’ attitudes may be pivotal for the success of inclusive education as they can elicit differential expectations and behaviors, which can enhance or limit the successful inclusion of students with special educational needs (SEN). Avramidis and Norwich (2002) stressed the importance of training in the formation of positive attitudes toward the integration of students with SEN. Although several studies have reported positive changes in attitudes following a course on inclusive education (e.g. Shade & Stewart, 2001), the relationship between competence and attitudes is less clear. Therefore, this study aimed to evaluate the effect of a course on inclusive pedagogy on competence and attitudes and the association between these constructs. Data were collected for 69 preservice teachers enrolled in a course on inclusive pedagogy. Attitudes toward the inclusion of students with SEN were assessed before and after the course, using the German version of The Opinions Relative to Integration of Students with Disabilities questionnaire (ORI; Benoit & Bless, 2014). In addition, at the end of the course students indicated to what extend the course had helped them to gain knowledge, skills and strategies concerning teaching a heterogeneous student population. Results of a repeated measures 2×4 ANOVA, with time (pre vs. post) and attitude towards inclusion (ORI subscales) as within group factors showed a main effect for attitudes, reflecting variations between the subscale scores. A significant time × attitudes interaction effect indicated positive attitude changes over time, but only in the domain of educational and social progression of students with SEN. Results of a regression analysis indicated that, after controlling for pre-course attitude ratings, perceived competence predicted attitude ratings at the end of the course. This study shows that teacher training can positively affect both teachers´ competence and attitudes concerning inclusive education, whereby perceived competence contributed to positive attitude change. [less ▲]

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See detailSocial media analysis
Schafer, Valerie UL; Clavert, Frédéric UL; Grandjean, Martin

Presentation (2018, September 12)

Digital social media have become so pervasive that historians can no longer ignore them, not only as a means of communication but also as a potential source for their research. This training session will ... [more ▼]

Digital social media have become so pervasive that historians can no longer ignore them, not only as a means of communication but also as a potential source for their research. This training session will be divided into three parts: feedback on previous research projects and experiences, a "hands-on" session in which participants can make their first Twitter data collection and analysis, and finally a critical perspective on digital social media as a source in humanities and social sciences. [less ▲]

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See detailA new invariance identity and means
Devillet, Jimmy UL; Matkowski, Janusz

in Results in Mathematics (2018), 73(4), 130

The invariance identity involving three operations D_{f,g} : X x X -> X of the form D_{f,g} (x,y) = (f o g)^{-1} (f (x) + g (y)) , is proposed. The connections of these operations with means is ... [more ▼]

The invariance identity involving three operations D_{f,g} : X x X -> X of the form D_{f,g} (x,y) = (f o g)^{-1} (f (x) + g (y)) , is proposed. The connections of these operations with means is investigated. The question when the invariance equality admits three means leads to a com- posite functional equation. Problem to determine its continuous solutions is posed [less ▲]

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See detailScarring Due to Unemployment by Gender: Evidence from a Cross-Country Factorial Survey
Gutfleisch, Tamara Rebecca UL; Samuel, Robin UL

Presentation (2018, September 07)

The allocation of individuals to occupations is a main mechanism of social reproduction and social stratification. Many studies elucidated the individual antecedents and consequences of this process. An ... [more ▼]

The allocation of individuals to occupations is a main mechanism of social reproduction and social stratification. Many studies elucidated the individual antecedents and consequences of this process. An interest has often been in how social origin moderates the transition from education to employment. However, empirical evidence on the role of recruiters in this fundamental social process is scarce. Against this backdrop, we examine how these gatekeepers evaluate hiring chances of young job applicants. In our contribution, we specifically focus on scarring due to unemployment in the health sector. Drawing on human capital theory and signalling theory, we expect variation in the hiring chances of male vs. female job seekers with respect to the length of previous and current unemployment spells. Using data from a recent large-scale factorial survey of recruiters in four European countries (N ≈ 2,000) and employing multilevel linear regression models, we find, overall, evidence for heterogeneous scarring effects. Young male job applicants who were unemployed received less favourable assessments compared to their female counterparts. Having been unemployed or being currently unemployed was not associated with hiring chances in young females. Our preliminary findings constitute new evidence on gender differences in scarring due to unemployment. They further contribute to the literature on transitions to employment. [less ▲]

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See detailCollective Power: Minimal Model for Thermodynamics of Nonequilibrium Phase Transitions
Herpich, Tim UL; Thingna, Juzar; Esposito, Massimiliano UL

in Physical Review. X (2018), 8(3), 031056

We propose a thermodynamically consistent minimal model to study synchronization which is made of driven and interacting three-state units. This system exhibits at the mean-field level two bifurcations ... [more ▼]

We propose a thermodynamically consistent minimal model to study synchronization which is made of driven and interacting three-state units. This system exhibits at the mean-field level two bifurcations separating three dynamical phases: a single stable fixed point, a stable limit cycle indicative of synchronization, and multiple stable fixed points. These complex emergent dynamical behaviors are understood at the level of the underlying linear Markovian dynamics in terms of metastability, i.e. the appearance of gaps in the upper real part of the spectrum of the Markov generator. Stochastic thermodynamics is used to study the dissipated work across dynamical phases as well as across scales. This dissipated work is found to be reduced by the attractive interactions between the units and to nontrivially depend on the system size. When operating as a work-to- work converter, we find that the maximum power output is achieved far-from-equilibrium in the synchronization regime and that the efficiency at maximum power is surprisingly close to the linear regime prediction. Our work shows the way towards building a thermodynamics of nonequilibrium phase transitions in conjunction to bifurcation theory. [less ▲]

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See detailSocial participation and peer relationships of students with special educational needs
Pit-Ten Cate, Ineke UL

Scientific Conference (2018, September 06)

Detailed reference viewed: 4 (0 UL)