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See detailLSPnet: A 2D Localization-oriented Spacecraft Pose Estimation Neural Network
Garcia Sanchez, Albert UL; Mohamed Ali, Mohamed Adel UL; Gaudilliere, Vincent UL et al

in Conference on Computer Vision and Pattern Recognition Workshops. Proceedings (in press)

Being capable of estimating the pose of uncooperative objects in space has been proposed as a key asset for enabling safe close-proximity operations such as space rendezvous, in-orbit servicing and active ... [more ▼]

Being capable of estimating the pose of uncooperative objects in space has been proposed as a key asset for enabling safe close-proximity operations such as space rendezvous, in-orbit servicing and active debris removal. Usual approaches for pose estimation involve classical computer vision-based solutions or the application of Deep Learning (DL) techniques. This work explores a novel DL-based methodology, using Convolutional Neural Networks (CNNs), for estimating the pose of uncooperative spacecrafts. Contrary to other approaches, the proposed CNN directly regresses poses without needing any prior 3D information. Moreover, bounding boxes of the spacecraft in the image are predicted in a simple, yet efficient manner. The performed experiments show how this work competes with the state-of-the-art in uncooperative spacecraft pose estimation, including works which require 3D information as well as works which predict bounding boxes through sophisticated CNNs. [less ▲]

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See detailDe la naissance de l’État luxembourgeois. Analyse et historique de la problématique
Heuschling, Luc UL

in Actes de la Section des sciences morales et politiques, Institut grand-ducal (in press)

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See detailEnergy Efficiency Optimization Technique for SWIPT-enabled Multi-Group Multicasting Systems with Heterogeneous Users
Gautam, Sumit UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in The international Conference on Acoustics, Speech, & Signal Processing (ICASSP) (2021, June)

We consider a multi-group (MG) multicasting (MC) system wherein a multi-antenna transmitter serves heterogeneous users capable of either information decoding (ID) or energy harvesting (EH), or both. In ... [more ▼]

We consider a multi-group (MG) multicasting (MC) system wherein a multi-antenna transmitter serves heterogeneous users capable of either information decoding (ID) or energy harvesting (EH), or both. In this context, we investigate a precoder design framework to explicitly serve the ID and EH users categorized within certain MC and EH groups. Specifically, the ID users are categorized within multiple MC groups while the EH users are a part of single (last) group. We formulate a problem to optimize the energy efficiency in the considered scenario under a quality-of-service (QoS) constraint. An algorithm based on Dinkelback method, slack-variable replacement, and second-order conic programming (SOCP)/semi-definite relaxation (SDR) is proposed to obtain a suitable solution for the above-mentioned fractional-objective dependent non-convex problem. Simulation results illustrate the benefits of proposed algorithm under several operating conditions and parameter values, while drawing a comparison between the two proposed methods. [less ▲]

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See detailEvaluation of the Molecular Pathogenesis of Adrenocortical Tumors by Whole-Genome Sequencing
Neininger, Kerstin UL; May, Patrick UL; Altieri, Barbara et al

in Journal of the Endocrine Society (2021, May 03), 5(Issue Supplement_1), 68

Pathogenesis of autonomous steroid secretion and adrenocortical tumorigenesis remains partially obscure. Our aim was to identify novel genetic alterations in adrenocortical adenomas (ACA) without somatic ... [more ▼]

Pathogenesis of autonomous steroid secretion and adrenocortical tumorigenesis remains partially obscure. Our aim was to identify novel genetic alterations in adrenocortical adenomas (ACA) without somatic mutations in known driver genes. Whole-genome sequencing was performed on 26 ACA/blood-derived DNA pairs without driver mutations in PRKACA, GNAS and CTNNB1 genes at previous WES (ENSAT study JCEM 2016). These included 12 cortisol-producing adenomas with Cushing syndrome (CS-CPAs), 7 with mild autonomous cortisol secretion (MACS-CPAs), and 7 endocrine-inactive ACAs (EIAs). Seven adrenocortical carcinomas (ACC) were added to the cohort. We developed a bioinformatics pipeline for a comprehensive genome analysis and to reveal differences in variant distribution. Strelka, VarScan2 and ANNOVAR software and an in-house confidence score were used for variant calling and functional annotation. Combined Annotation-Dependent-Depletion (CADD) values were used to prioritize pathogenic variants. Additional focus relied on variants in pathogenically known pathways (Wnt/β-catenin, cAMP/PKA pathway). NovoBreak algorithm was applied to discover structural variations. Two hypermutated CS-CPA samples were excluded from further analysis. Using different filters, we detected variants in driver genes not observed at WES (one p.S45P in CTNNB1 and one p.R206L in PRKACA in two different CS-CPAs). In total, we report 179,830 variations (179,598 SNVs; 232 indels) throughout all samples, being more abundant in ACC (88,954) compared to ACA (CS-CPAs: 31,821; MACS-CPAs: 35,008; EIAs: 29,963). Most alterations were in intergenic (>50%), followed by intronic and ncRNA intronic regions. A total of 32 predicted pathogenic variants were found in both coding (CADD values ≥ 15) and non-coding (CADD values ≥ 5) regions. We found 3,301 possibly damaging and recurrent variants (intergenic mutations removed) (CS-CPAs: 1,463; MACS-CPAs: 1,549; EIAs: 1,268; ACC: 1,660), mostly accumulated in intronic regions. Some of these were detected in members of the Wnt/β-catenin (CS-CPAs: 6; MACS-CPAs: 2; EIA: 1) and cAMP/PKA (CS-CPAs: 6; MACS-CPAs: 7; EIA: 4) pathways (e.g. ADCY1, ADCY2, GNA13, PDE11A). We also found a slightly higher number of structural variations in EIA (3,620) and ACC (3,486) compared to CS-CPAs (977) and MACS-CPAs (2,119). In conclusion, still unrevealed genetic alterations, especially in intronic regions, may accompany early adrenal tumorigenesis and/or autonomous cortisol secretion. [less ▲]

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See detailModeling and Optimization of RF-Energy Harvesting-assisted Quantum Battery System
Gautam, Sumit UL; Sharma, Shree Krishna UL; Chatzinotas, Symeon UL et al

in Proceedings of 2021 IEEE 93rd Vehicular Technology Conference: VTC2021-Spring (2021, April)

The quest for finding a small-sized energy supply to run the small-scale wireless gadgets, with almost an infinite lifetime, has intrigued humankind since past several decades. In this context, the ... [more ▼]

The quest for finding a small-sized energy supply to run the small-scale wireless gadgets, with almost an infinite lifetime, has intrigued humankind since past several decades. In this context, the concept of Quantum batteries has come into limelight more recently to serve the purpose. However, the main issue revolving around the closed-system design of Quantum batteries is to ensure a loss-less environment, which is extremely difficult to realize in practice. In this paper, we present the modeling and optimization aspects of a Radio-Frequency (RF) Energy Harvesting (EH) assisted Quantum battery, wherein several EH modules (in the form of micro- or nano- sized integrated circuits (ICs)) help each of the involved Quantum sources achieve the so-called quasi-stable state. Specifically, a micro-controller manages the overall harvested energy from the RF-EH ICs and a photon emitting device, such that the emitted photons are absorbed by the electrons in the Quantum sources. In order to precisely model and optimize the considered framework, we formulate a transmit power minimization problem for an RF-based wireless system to optimize the number of RF-EH ICs under the given EH constraints at the Quantum battery-enabled wireless device. We obtain an analytical solution to the above-mentioned problem using a rational approach, while additionally seeking another solution obtained via a non-linear program solver. The effectiveness of the proposed technique is reported in the form of numerical results by taking a range of system parameters into account. [less ▲]

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See detailSynchronized Preprocessing of Sensor Data
Tawakuli, Amal UL; Kaiser, Daniel UL; Engel, Thomas UL

in 2020 IEEE International Conference on Big Data (2021, March 19)

Sensor data whether collected for machine learning, deep learning or other applications must be preprocessed to fit input requirements or improve performance and accuracy. Data preparation is an expensive ... [more ▼]

Sensor data whether collected for machine learning, deep learning or other applications must be preprocessed to fit input requirements or improve performance and accuracy. Data preparation is an expensive, resource consuming and complex phase often performed centrally on raw data for a specific application. The dataflow between the edge and the cloud can be enhanced in terms of efficiency, reliability and lineage by preprocessing the datasets closer to their data sources. We propose a dedicated data preprocessing framework that distributes preprocessing tasks between a cloud stage and two edge stages to create a dataflow with progressively improving quality. The framework handles heterogenous data and dynamic preprocessing plans simultaneously targeting diverse applications and use cases from different domains. Each stage autonomously executes sensor specific preprocessing plans in parallel while synchronizing the progressive execution and dynamic updates of the preprocessing plans with the other stages. Our approach minimizes the workload on central infrastructures and reduces the resources used for transferring raw data from the edge. We also demonstrate that preprocessing data can be sensor specific rather than application specific and thus can be performed prior to knowing a specific application. [less ▲]

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See detailA Private Language Argument to elucidate the relation between mind and language
Fraissler, Hannes UL

in Unisinos Journal of Philosophy (2021, March 15), 22(1), 48-58

I will defend the claim that we need to differentiate between thinking and reasoning in order to make progress in understanding the intricate relation between language and mind. The distinction between ... [more ▼]

I will defend the claim that we need to differentiate between thinking and reasoning in order to make progress in understanding the intricate relation between language and mind. The distinction between thinking and reasoning will allow us to apply a structural equivalent of Ludwig Wittgenstein’s Private Language Argument to the domain of mind and language. This argumentative strategy enables us to show that and how a certain subcategory of cognitive processes, namely reasoning, is constitutively dependent on language. The final outcome and claim of this paper can be summarized as follows: We can think without language, but we cannot reason without language. While this still leaves several questions about the relation between mind and language unanswered, I hold that the insights defended in this paper provide the basis and proper framework for further investigation about the relationship between language and the mind. [less ▲]

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See detailComparing elementary cellular automata classifications with a convolutional neural network
Comelli, Thibaud; Pinel, Frederic UL; Bouvry, Pascal UL

in Proceedings of International Conference on Agents and Artificial Intelligence (ICAART) (2021, February 05)

Elementary cellular automata (ECA) are simple dynamic systems which display complex behaviour from simple local interactions. The complex behaviour is apparent in the two-dimensional temporal evolution of ... [more ▼]

Elementary cellular automata (ECA) are simple dynamic systems which display complex behaviour from simple local interactions. The complex behaviour is apparent in the two-dimensional temporal evolution of a cellular automata, which can be viewed as an image composed of black and white pixels. The visual patterns within these images inspired several ECA classifications, aimed at matching the automatas’ properties to observed patterns, visual or statistical. In this paper, we quantitatively compare 11 ECA classifications. In contrast to the a priori logic behind a classification, we propose an a posteriori evaluation of a classification. The evaluation employs a convolutional neural network, trained to classify each ECA to its assigned class in a classification. The prediction accuracy indicates how well the convolutional neural network is able to learn the underlying classification logic, and reflects how well this classification logic clusters patterns in the temporal evolution. Results show different prediction accuracy (yet all above 85%), three classifications are very well captured by our simple convolutional neural network (accuracy above 99%), although trained on a small extract from the temporal evolution, and with little observations (100 per ECA, evolving 513 cells). In addition, we explain an unreported ”pathological” behaviour in two ECAs. [less ▲]

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See detailCorrelation of Optical Signal During Laser Fusion Welding of Copper to Aluminum
Mathivanan, Karthik UL; Plapper, Peter UL

in Journal of Laser Applications (2021, January 05), 33(1),

Laser joining of dissimilar metals, copper and aluminum, allows for the precise delivery of laser energy and high process speed. The keyhole-based process is very efficient for welding Al–Cu, considering ... [more ▼]

Laser joining of dissimilar metals, copper and aluminum, allows for the precise delivery of laser energy and high process speed. The keyhole-based process is very efficient for welding Al–Cu, considering the high reflectivity and thermal conductivity of the materials joined. For the Al–Cu system, the formation of detrimental intermetallic compounds is the main issue. Fusion welding with laser as a heat source involves the melting of metals. However, the high speed of the laser welding process is advantageous for terminating the excessive melting of Al and Cu and eventually controlling the detrimental intermetallic phases. Therefore, information pertaining to melted material is an important criterion for achieving joint strength. In this paper, the photodiode signal measured during the laser welding of Cu to Al is investigated as a process monitoring technique. In welding from Cu to Al, the melting of Al (bottom sheet) is very critical for joint strength. The amount of Al material that can be intermixed in Cu depends on the solubility limit of the Al–Cu system. The plasma plume emission during laser welding is used to extract the rapid melting of Al. This study shows the correlation of the Al characteristic peak at a wavelength of 396 nm with the shear strength of the joint. [less ▲]

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See detailWhat is problematic about binary questions on gender in health surveys – a missing answer analysis
Heinz, Andreas UL; Költő, András; Godeau, Emmanuelle et al

in Cogent Medicine (2020, December 04)

Background: In many studies, participants who do not state their gender are excluded from the analysis. This may be appropriate if they do not answer the questionnaire seriously. However, some ... [more ▼]

Background: In many studies, participants who do not state their gender are excluded from the analysis. This may be appropriate if they do not answer the questionnaire seriously. However, some participants may have understandable reasons for not reporting their gender, e.g. questioning their gender identity. Research question: How many students and which students do not answer the question on gender? Methods: We analyzed data of the Health Behaviour in School-aged Children study from Ireland, France, Hungary, Scotland, Belgium (Flemish) and Luxembourg (n = 40,053). To explore the reasons for non-response, we divided the participants into 3 groups: 1. Responders answered both socio- demographic questions (age and gender) 2. age non-responders did not answer the question on age. 3. Gender non-responders answered the question on age, but not the one on gender. Results: 311 out of 40,053 (0.8%) pupils aged 11–18 did not report their gender. About 40% of them did not answer the age question either. However, the other 60% belong to the group of gender non-responders and this group is disadvantaged compared to responders: they report lower self-rated health, more health complaints, less family support and more substance use (alcohol, tobacco, cannabis). 1.9% of pupils did not answer the question about age. These age non-responders answered the questionnaire more selectively overall and skipped more questions. Conclusion: The data suggest that the reasons for age non-response and gender non-response are different. For age non-responders, the fear of de-anonymization seems to be the reason for not indicating their age. Not answering the question on gender is rare. If the participants answered the question on age, but not the question on gender, then the variable gender is missing not at random. The health problems of gender non-responders correspond to the health problems of gender non-conforming adolescents. Thus, the question arises if the group of gender non-responders should be included in the analysis and if the question on gender should be asked differently in the future [less ▲]

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See detailMeasuring sex and gender identity in a cross-national adolescent population survey: Perspectives of adolescent health experts from 44 countries
Költő, András; Heinz, Andreas UL; Moreno-Maldonado, Concepcion et al

in Cogent Medicine (2020, December 04)

Introduction: The Health Behaviour in School-aged Children (HBSC) is a World Health Organization collaborative cross-cultural study of adolescents aged 11–15 years, from 50 countries and regions in Europe ... [more ▼]

Introduction: The Health Behaviour in School-aged Children (HBSC) is a World Health Organization collaborative cross-cultural study of adolescents aged 11–15 years, from 50 countries and regions in Europe, North America and the former Soviet republics. Since 1983 (the first survey round), the sex/gender of the respondents have been categorised with the question “Are you a boy or a girl?”, the response options being “a boy” and “a girl”. In the light of lived experiences of young people and contemporary theoretical and empirical approaches to the measurement of sex assigned birth and gender identity, this item is contested.Research Questions: What are HBSC National Research Teams’ experiences with using this item? What is their position on any potential change or amendment of the item? Have they already made any changes? Do they see potential drawbacks and benefits in changing the item? Method: In Summer 2019, an online survey was conducted with HBSC National Teams, to under-stand member countries’ position on the measurement of sex and gender in the HBSC survey. Results: Of the 50 research teams, 44 responded to the online questionnaire. Opinions on potential changes or amendments of the item were polarised, with 19 teams (43%) not supporting any changes, 15 teams (34%) agreeing with a change, and 10 teams (23%) indicating they don’t know or not sure if changes are necessary. Various arguments were raised for and against any changes or amendments. Six national teams already implemented a change, by adding a third response option, replacing the item, or using additional items. Conclusions: The results demonstrate that the issue of sex and gender in HBSC needs to be addressed, but methodological, political and cultural implications need to be considered. The complexity of this problem makes it impossible to suggest a “one-size-fits-all” solution. [less ▲]

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See detailSensitivity Analysis on Regularity Based Driver Advisory Systems
Laskaris, Georgios; Seredynski, Marcin; Viti, Francesco UL

in 2020 IEEE 23rd International Conference on Intelligent Transportation Systems (ITSC) (2020, December)

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See detailA cascading Kalman filtering framework for real-time urban network flow estimation
Rinaldi, Marco UL; Viti, Francesco UL

in 2020 IEEE 23rd International Conference on Intelligent Transportation Systems (ITSC) (2020, December)

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See detailPractical Implementation of Functionally Graded Lattice Structures in a Bicycle Crank Arm
Decker, Thierry UL; Kedziora, Slawomir UL; Wolf, Claude UL

in 850th International Conference on Science, Technology, Engineering and Management (2020, November 25)

Functionally graded lattice structures (FGLS) were studied thoroughly for the past years, mostly focusing on specific synthetic tests in the context of additive manufacturing while rarely being actually ... [more ▼]

Functionally graded lattice structures (FGLS) were studied thoroughly for the past years, mostly focusing on specific synthetic tests in the context of additive manufacturing while rarely being actually applied outside of this specific domain. This paper examines a way to practically implement them in a commonly used appliance and study their potential for its improvement. A bicycle crank arm was chosen for this purpose, and a solid aluminium reference model (Shimano FC-R450-453) is used as a performance baseline. The novel design is composed of a hollow body containing a beam-based, non-stochastic, functionally graded lattice structure and is planned to be manufactured on a Markforged Metal X system using 17-4 PH stainless steel. It aims to increase the total stiffness under EN ISO 4210-8 norm loading conditions compared to the reference model while limiting mass and stress values to acceptable degrees. Two crank arm variants, containing a face-centred cubic (FCC) and re-entrant auxetic lattice respectively, are optimised by locally altering their beam radii in eight separate regions. The displacement at the load application point is minimised using Altair OptiStruct and HyperStudy. The reference crank, weighing 213g, exhibits a deflection magnitude of 7.1mm in the most demanding load case while the newly designed and optimised versions only showed displacements of 2.52mm (FCC lattice, 340g) and 2.58mm (re-entrant lattice, 339g) respectively. In addition, the stress distribution was significantly enhanced compared to the reference model, as the latter would not pass the fatigue tests required by the norm. This demonstrates that FGLS, in combination with high-strength materials and additive manufacturing, can increase the performance of many parts, although in this case, with a trade-off in terms of its mass. In future projects, it might be considerably reduced by utilising alternative lattice types lattices or other materials while preserving the benefits of FGLS. [less ▲]

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See detailReduction of temperature effects for bridge health monitoring
Nguyen, Viet Hà; Kebig, Tanja UL; Golinval, Jean-Claude et al

in Eccomas Proceedia (2020, November 23)

Structural health monitoring of concrete bridges can be achieved by tracking static load-testing results or dynamic properties as for example eigenfrequencies. Deviations from a healthy reference state ... [more ▼]

Structural health monitoring of concrete bridges can be achieved by tracking static load-testing results or dynamic properties as for example eigenfrequencies. Deviations from a healthy reference state can be used as damage indicators and even more, help to localize zones of stiffness reduction, i.e. cracking. However, outdoor temperature effects also lead to changes of monitored physical characteristics in the same order of magnitude as damage. Hence, temperature effects need to be removed prior to any condition analysis. The present paper presents a new two-step approach by applying physical compensation first, before using a statistical method based of Principal Component Analysis (PCA) or more exactly on principal vectors and singular values. This technique is here applied to eigenfrequencies, first of a new bridge without damage, but with extreme temperature variation due to thick asphalt layer and special bearing constraints, thus showing strong sensitivity along seasonal temperatures in the intact state. The second object is the Z24 Bridge in Switzerland, which is well documented in literature and where artificial damage was applied prior to demolition. The proposed techniques allow removing noise and temperature effects in a coherent and efficient way. The corrected measurement data can then be used in subsequent steps for its definite purpose, i.e. detection and localization of damage for instance by updating a numerical finite element model which allows assessing a stiffness loss. [less ▲]

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See detailDesigning of the module envelope of a hybrid modular building to meet the passive house standards in Luxembourg
Rakotonjanahary, Tahiana Roland Michaël UL; Scholzen, Frank UL; Ferreira Silva, Marielle UL et al

in IOP Conference Series: Earth and Environmental Science (2020, November 20), 588(5), 052026

To face the challenges of climate change, new buildings need to be further greener while being able to ensure a minimum comfort to the tenants. Nonetheless, extensibility and flexibility could be added to ... [more ▼]

To face the challenges of climate change, new buildings need to be further greener while being able to ensure a minimum comfort to the tenants. Nonetheless, extensibility and flexibility could be added to buildings. In this context, the architect jointly with the team of this research project have designed a hybrid modular construction called “slab building” which is composed of a permanent concrete structure and several removable wooden modules. A module offers 27m² of living space but larger housings can be realized by combining two up to four modules. The aim of this paper is to design the walls of the modules to meet the criteria of nZEB. The thicknesses of the studied thermal insulations, namely rock wool, wood wool, polyurethane and aerogel, have been determined in accordance with the passive house requirements in Luxembourg. The embodied energy of the building materials has also been considered in the designing of the modules. Steady state calculations revealed that a wall thickness of 40 cm, comprising 31cm of insulation is sufficient but according to the LCA outcomes, there is no environmental benefit in having the modules comply with the AAA energy class requirements at reasonable wall thicknesses. [less ▲]

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See detailBorrowing your enemy's arrows: the case of code reuse in android via direct inter-app code invocation
Gao, Jun UL; li, li; Kong, Pingfan UL et al

in ESEC/FSE 2020: Proceedings of the 28th ACM Joint Meeting on European Software Engineering Conference and Symposium on the Foundations of Software Engineering (2020, November)

{The Android ecosystem offers different facilities to enable communication among app components and across apps to ensure that rich services can be composed through functionality reuse. At the heart of ... [more ▼]

{The Android ecosystem offers different facilities to enable communication among app components and across apps to ensure that rich services can be composed through functionality reuse. At the heart of this system is the Inter-component communication (ICC) scheme, which has been largely studied in the literature. Less known in the community is another powerful mechanism that allows for direct inter-app code invocation which opens up for different reuse scenarios, both legitimate or malicious. This paper exposes the general workflow for this mechanism, which beyond ICCs, enables app developers to access and invoke functionalities (either entire Java classes, methods or object fields) implemented in other apps using official Android APIs. We experimentally showcase how this reuse mechanism can be leveraged to â plagiarize" supposedly-protected functionalities. Typically, we were able to leverage this mechanism to bypass security guards that a popular video broadcaster has placed for preventing access to its video database from outside its provided app. We further contribute with a static analysis toolkit, named DICIDer, for detecting direct inter-app code invocations in apps. An empirical analysis of the usage prevalence of this reuse mechanism is then conducted. Finally, we discuss the usage contexts as well as the implications of this studied reuse mechanism [less ▲]

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See detailThe Framework of Security-Enhancing Friction: How UX Can Help Users Behave More Securely
Distler, Verena UL; Lenzini, Gabriele UL; Lallemand, Carine UL et al

in New Security Paradigms Workshop (2020, October 26)

A growing body of research in the usable privacy and security community addresses the question of how to best influence user behavior to reduce risk-taking.We propose to address this challenge by ... [more ▼]

A growing body of research in the usable privacy and security community addresses the question of how to best influence user behavior to reduce risk-taking.We propose to address this challenge by integrating the concept of user experience (UX) into empirical usable privacy and security studies that attempt to change risktaking behavior. UX enables us to study the complex interplay between user-related, system-related and contextual factors and provides insights into the experiential aspects underlying behavior change, including negative experiences. We first compare and contrast existing security-enhancing interventions (e.g., nudges, warnings, fear appeals) through the lens of friction. We then build on these insights to argue that it can be desirable to design for moments of negative UX in security-critical situations. For this purpose, we introduce the novel concept of security-enhancing friction, friction that effectively reduces the occurrence of risk-taking behavior and ensures that the overall UX (after use) is not compromised. We illustrate how security-enhancing friction provides an actionable way to systematically integrate the concept of UX into empirical usable privacy and security studies for meeting both the objectives of secure behavior and of overall acceptable experience. [less ▲]

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See detailA Security and Privacy Focused KYC Data Sharing Platform
Norvill, Robert UL; Cyril, Cassagnes; Wazen, Shbair et al

in Proceedings of the 2nd ACM International Symposium on Blockchain and Secure Critical Infrastructure (2020, October)

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See detailMeasuring the Contextual Dimension of User Experience: Development of the User Experience Context Scale (UXCS)
Lallemand, Carine UL; Koenig, Vincent UL

in Proceedings of the 11th Nordic Conference on Human-Computer Interaction: Shaping Experiences, Shaping Society (2020, October)

The context of use has been highlighted for a long time as being a key factor impacting User Experience (UX). Yet current UX evaluation tools, especially questionnaires, rarely encompass an explicit ... [more ▼]

The context of use has been highlighted for a long time as being a key factor impacting User Experience (UX). Yet current UX evaluation tools, especially questionnaires, rarely encompass an explicit investigation of the context. With the ever-growing trend for mobile products and ubiquitous computing, the absence of a dedicated measurement tool becomes critical. Based on a review of relevant literature and a fine-grained categorization of contextual factors, we developed the UX Context Scale (UXCS), a 30-items instrument allowing for a measure of context properties, as perceived by the user. We report on the development of the scale and present a first validation study (N = 137). A principal component analysis on the subjective items reveals a 6-components structure: Physical Context, Social Context, Internal Context, Perceived Resources, Task Context, and Temporal Context. Reliability of each subscale is high and further analyses confirm the relevance of this tool for UX evaluation. [less ▲]

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See detailDissociated face- and word-selective intracerebral responses in the human ventral occipito-temporal cortex
Hagen, Simen; Lochy, Aliette UL; Jacques, Corentin et al

in Journal of Vision (2020, October), 20(11),

The extent to which faces and written words share neural circuitry in the human brain is actively debated. We provide an original contribution to this debate by comparing face-selective and word-selective ... [more ▼]

The extent to which faces and written words share neural circuitry in the human brain is actively debated. We provide an original contribution to this debate by comparing face-selective and word-selective responses in a large group of patients (N=37) implanted with intracerebral electrodes in the ventral occipito-temporal cortex (VOTC). Both face-selective (i.e., significantly different responses to faces vs. nonface objects) and word-selective (i.e., significantly different responses to words vs. pseudofonts) neural activity is isolated through frequency-tagging (Jonas et al., 2016; Lochy et al., 2018, respectively). Critically, this approach allows disentangling category-selective neural responses from general visual responses. Overall, we find that 69.26% of significant contacts show either face- or word-selectivity, with the expected right and left hemispheric dominance, respectively (Fig.1A,B). Moreover, the center of mass for word-contacts is more lateral than for face-contacts, with no differences in postero-anterior axis (Fig.2A). Spatial dissociations are also found within core regions of face and word processing, with a medio-lateral dissociation in the fusiform gyrus (FG) and surrounding sulci (FG+sulci;Fig.2B), while a postero-anterior dissociation is found in the inferior occipital gyrus (IOG;Fig.2C). Despite their spatial dissociations in the FG+sulci and IOG, most overlap in category-selective responses is found in these regions (Fig.1C). Critically, in the overlap-contacts, across the whole brain or specifically in the FG+sulci, between-category (word-face) selective-amplitudes showed no-to-weak correlations, despite strong correlations for within-category (face-face, word-word) selective-amplitudes (Fig.3A), and a strong correlation in non-selective general-amplitudes to words-faces. Moreover, substantial overlap and no-to-weak correlations were observed between faces and a control category (houses) known to be functionally dissociated from faces. Overall, we conclude that category-selectivity for faces and words is largely dissociated in the human VOTC, with a limited spatial overlap likely due to the distant recording of dissociated populations of neurons rather than to shared category-selective representations. [less ▲]

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See detailSDR IMPLEMENTATION OF A TESTBED FOR SYNCHRONIZATION OF COHERENT DISTRIBUTED REMOTE SENSING SYSTEMS
Merlano Duncan, Juan Carlos UL; Querol, Jorge UL; Martinez Marrero, Liz UL et al

in Proceedings of IEEE International Geoscience and Remote Sensing Symposium 2020 (2020, September 26)

Remote Sensing from distributed platforms has become attractive for the community in the last years. Phase, frequency, and time synchronization are a crucial requirement for many such applications as ... [more ▼]

Remote Sensing from distributed platforms has become attractive for the community in the last years. Phase, frequency, and time synchronization are a crucial requirement for many such applications as multi-static remote sensing and also for distributed beamforming for communications. The literature on the field is extensive, and in some cases, the requirements an complexity of the proposed synchronization solution may surpass the ones set by the application itself. Moreover, the synchronization solution becomes even more challenging when the nodes are flying or hovering on aerial or space platforms. In this work, we discuss the synchronization considerations for the implementation of distributed remote sensing applications. The general framework considered is based on a distributed collection of autonomous nodes that synchronize their clocks with a common reference using inter-satellite links. For this purpose, we implement a synchronization link between two nodes operating in a full-duplex fashion. The experimental testbed uses commercially available SDR platforms to emulate two satellites, two targets, and the communication channel. The proposal is evaluated considering phase and frequency errors for different system parameters. [less ▲]

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See detailActor-Critic Deep Reinforcement Learning for Energy Minimization in UAV-Aided Networks
Yuan, Yaxiong UL; Lei, Lei UL; Vu, Thang Xuan UL et al

in 2020 European Conference on Networks and Communications (EuCNC) (2020, September 21)

In this paper, we investigate a user-timeslot scheduling problem for downlink unmanned aerial vehicle (UAV)-aided networks, where the UAV serves as an aerial base station. We formulate an optimization ... [more ▼]

In this paper, we investigate a user-timeslot scheduling problem for downlink unmanned aerial vehicle (UAV)-aided networks, where the UAV serves as an aerial base station. We formulate an optimization problem by jointly determining user scheduling and hovering time to minimize UAV’s transmission and hovering energy. An offline algorithm is proposed to solve the problem based on the branch and bound method and the golden section search. However, executing the offline algorithm suffers from the exponential growth of computational time. Therefore, we apply a deep reinforcement learning (DRL) method to design an online algorithm with less computational time. To this end, we first reformulate the original user scheduling problem to a Markov decision process (MDP). Then, an actor-critic-based RL algorithm is developed to determine the scheduling policy under the guidance of two deep neural networks. Numerical results show the proposed online algorithm obtains a good tradeoff between performance gain and computational time. [less ▲]

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See detailAutomatic Detection of Nigrosome Degeneration in Susceptibility-Weighted MRI for Computer-Aided Diagnosis of Parkinson’s Disease Using Machine Learning
Garcia Santa Cruz, Beatriz UL; Husch, Andreas UL; Hertel, Frank UL

in Movement Disorders: Volume 35, Number S1, September 2020 (2020, September 12)

Objective: Automatize the detection of ‘swallow-tail’ appearance in substantia nigra dopaminergic neurons using MRI for more robust tests on Parkinson’s disease (PD) diagnosis. Background: Differential ... [more ▼]

Objective: Automatize the detection of ‘swallow-tail’ appearance in substantia nigra dopaminergic neurons using MRI for more robust tests on Parkinson’s disease (PD) diagnosis. Background: Differential diagnosis of PD is challenging even in specialized centers. The use of imaging techniques can be bene cial for the diagnosis. Although DaTSCAN has been proven to be clinically useful, it is not widely available and has radiation risk and high-cost associated. Therefore, MRI scans for PD diagnosis offer several advantages over DaTSCAN [1]. Recent literature shows strong evidence of high diagnostic accuracy using the ‘swallow-tail’ shape of the dorsolateral substantia nigra in 3T – SWI [2]. Nevertheless, the majority of such studies rely on the subjective opinion of experts and manual methods for the analysis to assess the accuracy of these features. Alternatively, we propose a fully automated solution to evaluate the absence or presence of this feature for computer-aided diagnosis (CAD) of PD. Method: Restrospective study of 27 PD and 18 non-PD was conducted, including standard high-resolution 3D MRI – T1 & SWI sequences (additionally, T2 scans were used to increase the registration references). Firstly, spatial registration and normalization of the images were performed. Then, the ROI was extracted using atlas references. Finally, a supervised machine learning model was built using 5-fold-within-5-fold nested cross-validation. Results: Preliminary results show signi cant sensitivity (0.92) and ROC AUC (0.82), allowing for automated classi cation of patients based on swallow-tail biomarker from MRI. Conclusion: Detection of nigrosome degeneration (swallow-tail biomarker) in accessible brain imaging techniques can be automatized with signi cant accuracy, allowing for computer-aided PD diagnosis. References: [1] Schwarz, S. T., Xing, Y., Naidu, S., Birchall, J., Skelly, R., Perkins, A., ... & Gowland, P. (2017). Protocol of a single group prospective observational study on the diagnostic value of 3T susceptibility weighted MRI of nigrosome-1 in patients with parkinsonian symptoms: the N3iPD study (nigrosomal iron imaging in Parkinson’s disease). BMJ open, 7(12), e016904. [2] – Schwarz, S. T., Afzal, M., Morgan, P. S., Bajaj, N., Gowland, P. A., & Auer, D. P. (2014). The ‘swallow tail’ appearance of the healthy nigrosome –a new accurate test of Parkinson’s disease: a case-control and retrospective cross-sectional MRI study at 3T. PloS one, 9(4). [less ▲]

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See detailA Quantitative Analysis of Security, Anonymity and Scalability for the Lightning Network
Tikhomirov, Sergei UL; Moreno-Sanchez, Pedro; Maffei, Matteo

in Proceedings of 2020 IEEE European Symposium on Security and Privacy (EuroS&P) (2020, September)

Payment channel networks have been introduced to mitigate the scalability issues inherent to permissionless decentralized cryptocurrencies such as Bitcoin. Launched in 2018, the Lightning Network (LN) has ... [more ▼]

Payment channel networks have been introduced to mitigate the scalability issues inherent to permissionless decentralized cryptocurrencies such as Bitcoin. Launched in 2018, the Lightning Network (LN) has been gaining popularity and consists today of more than 5000 nodes and 30000 payment channels that jointly hold 895 bitcoins (7.6M USD as of February 2020). This adoption has motivated research from both academia and industry. Payment channels suffer from security vulnerabilities, such as the wormhole attack, anonymity issues, and scalability limitations related to the upper bound on the number of concurrent payments per channel, which have been pointed out by the scientific community but never quantitatively analyzed. In this work, we first analyze the proneness of the LN to the wormhole attack and attacks against anonymity. We observe that an adversary needs to control only 2% of LN nodes to learn sensitive payment information (e.g., sender, receiver and payment amount) or to carry out the wormhole attack. Second, we study the management of concurrent payments in the LN and quantify its negative effect on scalability. We observe that for micropayments, the forwarding capability of up to 50% of channels is restricted to a value smaller than the overall channel capacity. This phenomenon not only hinders scalability but also opens the door for DoS attacks: We estimate that a network-wide DoS attack costs within 1.5M USD, while isolating the biggest community from the rest of the network costs only 225k USD. Our findings should prompt the LN community to consider the security, privacy and scalability issues of the network studied in this work when educating users about path selection algorithms, as well as to adopt multi-hop payment protocols that provide stronger security, privacy and scalability guarantees. [less ▲]

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See detailKnowledgezooclient: Constructing knowledge graph for android
Li, Li; Gao, Jun UL; Kong, Pingfan UL et al

in The 3rd International Workshop on Advances in Mobile App Analysis (2020, September)

In this work, we describe the design and implementation of a reusable tool named KnowledgeZooClient targeting the construction, as a crowd-sourced effort, of a knowledge graph for Android apps ... [more ▼]

In this work, we describe the design and implementation of a reusable tool named KnowledgeZooClient targeting the construction, as a crowd-sourced effort, of a knowledge graph for Android apps. KnowledgeZooClient is made up of two modules: (1) the Metadata Extraction Module (MEM), which aims at extracting metadata from Android apps and (2) the Metadata Integration Module (MIM) for importing and integrating extracted metadata into a graph database. The usefulness of KnowledgeZooClient is demonstrated via an exclusive knowledge graph called KnowledgeZoo, which contains information on over 500,000 apps already and still keeps growing. Interested users can already benefit from KnowledgeZoo by writing advanced search queries so as to collect targeted app samples. [less ▲]

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See detailAnaerobe Vergärung von (synthetischem) Küchenabfall in zweistufigem Semi-Konti-Betrieb
Sobon, Elena UL; Schlienz, Markus UL; Greger, Manfred UL

in Chemie Ingenieur Technik (2020, August 28), 92(9), 1267-1268

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See detailRIVER MORPHOLOGY MONITORING OF A SMALL-SCALE ALPINE RIVERBED USING DRONE PHOTOGRAMMETRY AND LIDAR
Backes, Dietmar UL; Smigaj, Magdalena; Schimka, Marian et al

in The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (2020, August 12), XLIII-B2-2020 Article Metrics Related articles(1017), 1024

An efficient alternative to labour-intensive terrestrial and costly airborne surveys is the use of small, inexpensive Unmanned Aerial Vehicles (UAVs) or Remotely Piloted Aerial Systems (RPAS). These low ... [more ▼]

An efficient alternative to labour-intensive terrestrial and costly airborne surveys is the use of small, inexpensive Unmanned Aerial Vehicles (UAVs) or Remotely Piloted Aerial Systems (RPAS). These low-altitude remote sensing platforms, commonly known as drones, can carry lightweight optical and LiDAR sensors. Even though UAV systems still have limited endurance, they can provide a flexible and relatively inexpensive monitoring solution for a limited area of interest. This study investigated the applicability of monitoring the morphology of a frequently changing glacial stream using high-resolution topographic surface models derived from low-altitude UAV-based photogrammetry and LiDAR. An understanding of river-channel morphology and its response to anthropogenic and natural disturbances is imperative for effective watershed management and conservation. We focus on the data acquisition, processing workflow and highlight identified challenges and shortcomings. Additionally, we demonstrate how LiDAR data acquisition simulations can help decide which laser scanning approach to use and help optimise data collection to ensure full coverage with desired level of detail. Lastly, we showcase a case study of 3D surface change analysis in an alpine stream environment with UAV-based photogrammetry. The datasets used in this study were collected as part of the ISPRS Summer School of Alpine Research, which will continue to add new data layers on a biyearly basis. This growing data repository is freely available for research. [less ▲]

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See detailLeveraging eBPF to preserve user privacy for DNS, DoT, and DoH queries
Rivera, Sean UL; Gurbani, Vijay; Lagraa, Sofiane UL et al

in Proceedings of the 15th International Conference on Availability, Reliability and Security (2020, August)

The Domain Name System (DNS), a fundamental protocol that controls how users interact with the Internet, inadequately provides protection for user privacy. Recently, there have been advancements in the ... [more ▼]

The Domain Name System (DNS), a fundamental protocol that controls how users interact with the Internet, inadequately provides protection for user privacy. Recently, there have been advancements in the field of DNS privacy and security in the form of the DNS over TLS (DoT) and DNS over HTTPS (DoH) protocols. The advent of these protocols and recent advancements in large-scale data processing have drastically altered the threat model for DNS privacy. Users can no longer rely on traditional methods, and must instead take active steps to ensure their privacy. In this paper, we demonstrate how the extended Berkeley Packet Filter (eBPF) can assist users in maintaining their privacy by leveraging eBPF to provide privacy across standard DNS, DoH, and DoT communications. Further, we develop a method that allows users to enforce application-specific DNS servers. Our method provides users with control over their DNS network traffic and privacy without requiring changes to their applications while adding low overhead. [less ▲]

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See detailReservoir Computing with Random Chemical Systems
Nguyen, Hoang; Banda, Peter UL; Stefanovic, Darko et al

in ALIFE 2020: The 2020 Conference on Artificial Life (2020, July 14)

Top-down engineering of biomolecular circuits to perform specific computational tasks is notoriously hard and time-consuming. Current circuits have limited complexity and are brittle and application ... [more ▼]

Top-down engineering of biomolecular circuits to perform specific computational tasks is notoriously hard and time-consuming. Current circuits have limited complexity and are brittle and application-specific. Here we propose an alternative: we design and test a bottom-up constructed Reservoir Computer (RC) that uses random chemical circuits inspired by DNA strand displacement reactions. This RC has the potential to be implemented easily and trained for various tasks. We describe and simulate it by means of a Chemical Reaction Network (CRN) and evaluate its performance on three computational tasks: the Hamming distance and a short- as well as a long-term memory. Compared with the deoxyribozyme oscillator RC model simulated by Yahiro et al., our random chemical RC performs 75.5% better for the short-term and 67.2% better for the long-term memory task. Our model requires an 88.5% larger variety of chemical species, but it relies on random chemical circuits, which can be more easily realized and scaled up. Thus, our novel random chemical RC has the potential to simplify the way we build adaptive biomolecular circuits. [less ▲]

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See detailThe Unsecure Side of (Meta)Data in IoT Systems
Chiara, Pier Giorgio UL

in Ambient Intelligence and Smart Environments (2020, July), 28

The exponential spreading and deployment of emerging digital technologies such as the Internet of Things (IoT) has been remarkable: the IoT market is expected to triple, at least, from USD 170.57 billion ... [more ▼]

The exponential spreading and deployment of emerging digital technologies such as the Internet of Things (IoT) has been remarkable: the IoT market is expected to triple, at least, from USD 170.57 billion in 2017 to USD 561.04 billion by 2022. IoT technologies collect, generate and communicate a huge amount of different data and metadata, through an increasing number of interconnected devices and sensors. Current EU legislation on data protection classifies data into personal and non-personal. The paper aims at charting the resulting entanglements from an interdisciplinary perspective. The legal analysis, integrated with a technical perspective, will address firstly the content of IoT communications, i.e. “data”, and the underlying distinction between personal and non-personal. Secondly, the focus will shift on the metadata related to communications. Through a technical analysis of the highly sensitive nature of metadata, even when the content is encrypted, I will argue that metadata are likely to undermine even more the ontological and sharp division between personal and non-personal data upon which the European legal frameworks for privacy and data protection have been built. The incoming ePrivacy Regulation shall provide metadata, which should be considered always personal data, the same level of protection of “content” data. This interpretation might broaden the scope of application of GDPR and the connected obligations and responsibilities of data controllers and data processors too much. [less ▲]

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See detail'Being a space mining crew': How participants jointly discover their complementary resources while engaging into a serious game at an interactive tabletop
Arend, Béatrice UL; Sunnen, Patrick UL; Heuser, Svenja UL et al

in L.Gomez Chova, A. Lopez Martinez, I. Candel Torres: Proceedings, International Conference on Education and New Learning Technologies 2020 (2020, July)

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See detailConnecting the real world to mathematical models in elementary schools in Luxemburg
Haas, Ben; Kreis, Yves UL; Lavicza, Zsolt

in Proceedings of the British Society for Research into Learning Mathematics (2020, July), 40(2), 1-6

In the Luxemburgish national curriculum for elementary schools (MENFP, 2011) experimentations and discoveries of mathematics concepts in courses are strongly recommended. Elementary school teachers should ... [more ▼]

In the Luxemburgish national curriculum for elementary schools (MENFP, 2011) experimentations and discoveries of mathematics concepts in courses are strongly recommended. Elementary school teachers should engage students in active mathematical modelling approaches, where they can develop processes and content skills through discoveries. Moreover, learned skills should be connected to real-world problems and situations to foster a better understanding of students’ living environments. Nevertheless, this teaching culture in mathematics is unusual in elementary schools and teachers tend to teach based on textbooks. Students mostly learn mathematics by imitation and repetition rather than through modelling mathematics with real-world problems and situations. Thus, to develop new methodologies in teaching mathematics and to meet the requirements of the national curriculum, we designed different technology-enhanced teaching and learning methods to engage students in experimental approaches within and outside classrooms. Moreover, we conducted three studies with digital and physical modelling, augmented reality, and a tutoring system in elementary school mathematics courses. Based on our collected data, we identified settings and tasks likely to support active mathematical modelling approaches. [less ▲]

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See detailPIAF: Developing Computational and Algorithmic Thinking in Fundamental Education
Parmentier, Yannick; Reuter, Robert UL; Higuet, Sarah et al

in Proceedings of EdMedia + Innovate Learning (2020, June 23), 2020(1), 315-322

In this article, we present the objectives and first achievements of the PIAF project supported by the European Union and aiming at developing computational and algorithmic thinking in basic education ... [more ▼]

In this article, we present the objectives and first achievements of the PIAF project supported by the European Union and aiming at developing computational and algorithmic thinking in basic education. This project brings together researchers in educational sciences and computer science from four countries (Belgium, France, Germany and Luxembourg) around the theme of teacher training. More concretely, the aim is to define a framework (competency framework, pedagogical scenarios) enabling teachers to (i) appropriate the concept of computational and algorithmic thinking and (ii) implement learning activities that promote the development of this kind of thinking in children. [less ▲]

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See detailDecision Triggered Data Transmission and Collection in Industrial Internet of Things
He, Jiguang; Kong, Long UL; Frondelius, Tero et al

in 2020 IEEE Wireless Communications and Networking Conference (WCNC) (2020, June 19)

We propose a decision triggered data transmission and collection (DTDTC) protocol for condition monitoring and anomaly detection in the industrial Internet of things (IIoT). In the IIoT, the collection ... [more ▼]

We propose a decision triggered data transmission and collection (DTDTC) protocol for condition monitoring and anomaly detection in the industrial Internet of things (IIoT). In the IIoT, the collection, processing, encoding, and transmission of the sensor readings are usually not for the reconstruction of the original data but for decision making at the fusion center. By moving the decision making process to the local end devices, the amount of data transmission can be significantly reduced, especially when normal signals with positive decisions dominate in the whole life cycle and the fusion center is only interested in collecting the abnormal data. The proposed concept combines compressive sensing, machine learning, data transmission, and joint decision making. The sensor readings are encoded and transmitted to the fusion center only when abnormal signals with negative decisions are detected. All the abnormal signals from the end devices are gathered at the fusion center for a joint decision with feedback messages forwarded to the local actuators. The advantage of such an approach lies in that it can significantly reduce the volume of data to be transmitted through wireless links. Moreover, the introduction of compressive sensing can further reduce the dimension of data tremendously. An exemplary case, i.e., diesel engine condition monitoring, is provided to validate the effectiveness and efficiency of the proposed scheme compared to the conventional ones. [less ▲]

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See detailThe rise of eBPF for non-intrusive performance monitoring
Cassagnes, Cyril UL; Trestioreanu, Lucian Andrei UL; Joly, Clement UL et al

in IEEE Xplore (2020, June 08)

In this paper, we explain that container engines are strengthening their isolation mechanisms. Therefore, nonintrusive monitoring becomes a must-have for the performance analysis of containerized user ... [more ▼]

In this paper, we explain that container engines are strengthening their isolation mechanisms. Therefore, nonintrusive monitoring becomes a must-have for the performance analysis of containerized user-space application in production environments. After a literature review and background of Linux subsystems and container isolation concepts, we present our lessons learned of using the extended Berkeley packet filter to monitor and profile performance. We carry out the profiling and tracing of several Interledger connectors using two full-fledged implementations of the Interledger protocol specifications. [less ▲]

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See detailValidated Variational Inference via Practical Posterior Error Bounds
Huggins, Jonathan; Kasprzak, Mikolaj UL; Campbell, Trevor et al

in Proceedings of the 23rd International Conference on Artificial Intelligence and Statistics (AISTATS) (2020, June)

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See detailEffects of Annealing and Light on Co-evaporated Methylammonium Lead Iodide Perovskites using Kelvin Probe Force Microscopy in Ultra-High Vacuum
Gallet, Thibaut UL; Martin Lanzoni, Evandro UL; Redinger, Alex UL

in 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) (2020, February 06)

Careful surface analysis is essential to understand the electronic and ionic behaviors in perovskite absorbers. In this contribution we discuss Kelvin probe force microscopy performed in ultra-high vacuum ... [more ▼]

Careful surface analysis is essential to understand the electronic and ionic behaviors in perovskite absorbers. In this contribution we discuss Kelvin probe force microscopy performed in ultra-high vacuum on as-grown and annealed co-evaporated methylammonium lead iodide perovskite thin films. By comparing the contact potential difference upon annealing and illumination, we find that annealing increases the average workfunction, indicating a change either in doping or in surface composition. Illumination also increases the average workfunction, indicating a p-type absorber, by reducing band bending as the photo-generated carriers screen the surface states. The effect of light shows a two-step process, with a first fast trend, linked to the surface photovoltage and a second slower trend indicating a possible redistribution of mobile charges. [less ▲]

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See detailEvolving a Deep Neural Network Training Time Estimator
Pinel, Frédéric UL; Yin, Jian-xiong; Hundt, Christian UL et al

in Communications in Computer and Information Science (2020, February)

We present a procedure for the design of a Deep Neural Net- work (DNN) that estimates the execution time for training a deep neural network per batch on GPU accelerators. The estimator is destined to be ... [more ▼]

We present a procedure for the design of a Deep Neural Net- work (DNN) that estimates the execution time for training a deep neural network per batch on GPU accelerators. The estimator is destined to be embedded in the scheduler of a shared GPU infrastructure, capable of providing estimated training times for a wide range of network architectures, when the user submits a training job. To this end, a very short and simple representation for a given DNN is chosen. In order to compensate for the limited degree of description of the basic network representation, a novel co-evolutionary approach is taken to fit the estimator. The training set for the estimator, i.e. DNNs, is evolved by an evolutionary algorithm that optimizes the accuracy of the estimator. In the process, the genetic algorithm evolves DNNs, generates Python-Keras programs and projects them onto the simple representation. The genetic operators are dynamic, they change with the estimator’s accuracy in order to balance accuracy with generalization. Results show that despite the low degree of information in the representation and the simple initial design for the predictor, co-evolving the training set performs better than near random generated population of DNNs. [less ▲]

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See detailModel and Solution Methods for the Mixed-Fleet Multi-Terminal Bus Scheduling Problem
Picarelli, Erika; Rinaldi, Marco UL; D'Ariano, Andrea et al

in Transportation Research Procedia (2020, January), 47

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See detailInferring Urban Mobility and Habits from User Location History
Cantelmo, Guido; Vitello, Piergiorgio UL; Toader, Bogdan et al

in Transportation Research Procedia (2020, January), 47

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See detailInferring Urban Mobility and Habits from User Location History
Cantelmo, Guido; Vitello, Piergiorgio UL; Toader, Bogdan et al

in Transportation Research Procedia (2020, January), 47

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See detailA Look into Privacy-Preserving Blockchains
Khan, Nida UL; Nassar, Mohamed

in IEEE BCA @AICCSA 2019 - Workshop on Blockchain and it's Applications (2020)

Blockchain is a revolutionary technology promising a new generation of decentralized, transparent and tamper-proof database systems. However, one of the main challenges of the emerging blockchain systems ... [more ▼]

Blockchain is a revolutionary technology promising a new generation of decentralized, transparent and tamper-proof database systems. However, one of the main challenges of the emerging blockchain systems remains to address data privacy. While in Bitcoin and similar e-cash systems, privacy was limited to anonymity and addressed by using cryptographic pseudonyms for identification and authentication of parties, the question of privacy has more breadth in systems maintaining actual data such as medical records or energy meters. In this paper, we look into recently proposed privacy-preserving blockchains, analyze their strengths and weaknesses, and highlight research questions requiring future investigation. We conclude that privacy-preserving blockchains are still in their infancy and more research is definitely needed in this area. [less ▲]

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See detailFederated Learning For Cyber Security: SOC Collaboration For Malicious URL Detection
Khramtsova, Ekaterina; Hammerschmidt, Christian; Lagraa, Sofiane UL et al

in IEEE International Conference on Distributed Computing Systems (ICDCS) (2020)

Managed security service providers increasingly rely on machine-learning methods to exceed traditional, signature- based threat detection and classification methods. As machine- learning often improves ... [more ▼]

Managed security service providers increasingly rely on machine-learning methods to exceed traditional, signature- based threat detection and classification methods. As machine- learning often improves with more data available, smaller orga- nizations and clients find themselves at a disadvantage: Without the ability to share their data and others willing to collaborate, their machine-learned threat detection will perform worse than the same model in a larger organization. We show that Feder- ated Learning, i.e. collaborative learning without data sharing, successfully helps to overcome this problem. Our experiments focus on a common task in cyber security, the detection of unwanted URLs in network traffic seen by security-as-a-service providers. Our experiments show that i) Smaller participants benefit from larger participants ii) Participants seeing different types of malicious traffic can generalize better to unseen types of attacks, increasing performance by 8% to 15% on average, and up to 27% in the extreme case. iii) Participating in Federated training never harms the performance of the locally trained model. In our experiment modeling a security-as-a service setting, Federated Learning increased detection up to 30% for some participants in the scheme. This clearly shows that Federated Learning is a viable approach to address issues of data sharing in common cyber security settings. [less ▲]

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See detailMaking Encryption Feel Secure: Investigating how Descriptions of Encryption Impact Perceived Security
Distler, Verena UL; Lallemand, Carine UL; Koenig, Vincent UL

in The 5th European Workshop on Usable Security (EuroUSEC 2020) (2020)

When communication about security to end users is ineffective, people frequently misinterpret the protection offered by a system. The discrepancy between the security users perceive a system to have and ... [more ▼]

When communication about security to end users is ineffective, people frequently misinterpret the protection offered by a system. The discrepancy between the security users perceive a system to have and the actual system state can lead to potentially risky behaviors. It is thus crucial to understand how security perceptions are shaped by interface elements such as text-based descriptions of encryption. This article addresses the question of how encryption should be described to non-experts in a way that enhances perceived security. We tested the following within-subject variables in an online experiment (N=309): a) how to best word encryption, b) whether encryption should be described with a focus on the process or outcome, or both c) whether the objective of encryption should be mentioned d) when mentioning the objective of encryption, how to best describe it e) whether a hash should be displayed to the user. We also investigated the role of context (between subjects). The verbs “encrypt” and “secure” performed comparatively well at enhancing perceived security. Overall, participants stated that they felt more secure not knowing about the objective of encryption. When it is necessary to state the objective, positive wording of the objective of encryption worked best. We discuss implications and why using these results to design for perceived lack of security might be of interest as well. This leads us to discuss ethical concerns, and we give guidelines for the design of user interfaces where encryption should be communicated to end users. [less ▲]

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See detailExamining the Interplay of Generalized and Personal Views on Aging on Physical and Mental Health Across 2.5 Years
Brothers, Allyson; Kornadt, Anna Elena UL; Nehrkorn-Bailey, Abigail et al

in Innovation in Aging (2020), 4(Supplement_1), 588-588

It remains unknown how distinct types of views on aging (VoA) are related to one another, and to aging outcomes. We used a latent-variable structural equation model to test the hypothesis that generalized ... [more ▼]

It remains unknown how distinct types of views on aging (VoA) are related to one another, and to aging outcomes. We used a latent-variable structural equation model to test the hypothesis that generalized views on aging (assessed as Age Stereotypes (AS)) would influence personal views on aging (assessed as Self-Perceptions of Aging (SPA)), which in-turn would influence later physical and mental health. Data came from a longitudinal survey on VoA (N= 537, MageT1 = 64.13, age rangeT1 = 40-98). As expected, SPA mediated the effect of AS on physical (loss-SPA: β = .23, p< .001; gain-SPA: β = .06, p< .001; R2 = .62) and mental health (loss-SPA: β = .13, p< .001; gain-SPA: β = .03, p< .01, ; R2 = .31). Congruent with theoretical assumptions, our findings provide empirical support for a directional pathway by which generalized views on aging affect health outcomes via personal views of aging. [less ▲]

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See detailThe Runner's Journey: Identifying Design Opportunities for Running Motivation Technology
Menheere, D.; Lallemand, Carine UL; Van Der Spek, E. et al

in ACM International Conference Proceeding Series (2020)

Running is a popular recreational sport, yet for many amateur runners it remains challenging to turn intentions into sustainable running behavior. Although the market offers a myriad of running-related ... [more ▼]

Running is a popular recreational sport, yet for many amateur runners it remains challenging to turn intentions into sustainable running behavior. Although the market offers a myriad of running-related devices that aim to motivate runners, these often focus on the training itself and not on overcoming the barriers experienced prior to the run. A better understanding of these barriers to running is essential to identify design opportunities for technologies supporting amateur runners. We conducted two complementary studies among participants of a women-only running event. Combining an online survey (N = 114) and a journey mapping activity (N = 13), we investigated the influence of motivational barriers and enablers in runners' rituals. Based on our findings, we created the Runner's Journey, a visual narrative highlighting actionable design opportunities for running motivation technology. We propose five design recommendations to overcome barriers among amateur runners. © 2020 ACM. [less ▲]

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See detailFaye: An Empathy Probe to Investigate Motivation Among Novice Runners
Menheere, D.; Lallemand, Carine UL; Funk, M. et al

in Communications in Computer and Information Science (2020), 1294

The popularity of recreational sports such as running, has increased substantially due to its low threshold to start and it is attractive for a wide range of people. However, despite the growing ... [more ▼]

The popularity of recreational sports such as running, has increased substantially due to its low threshold to start and it is attractive for a wide range of people. However, despite the growing popularity, running has a high drop-out rate due to injuries and motivational loss, especially among novice runners. To investigate factors influencing motivation among novice runners and design opportunities, we deployed an empathy probe at a women-only running event. Faye is a running shirt that reveals motivational feedback on the shirt, during the warm-up phase of the run. In this paper, we both inform on the impact of motivational feedback while warming up on running motivation and reflect on the use of an empathy probe to investigate motivational strategies among novice runners. © 2020, Springer Nature Switzerland AG. [less ▲]

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See detailThe hub: Facilitating walking meetings through a network of interactive devices
Damen, Ida; Kok, Anika; Vink, Bas et al

in DIS 2020 Companion - Companion Publication of the 2020 ACM Designing Interactive Systems Conference (2020)

Walking meetings are a promising means to improve healthy behavior at work. By providing a physically active way of working, walking meetings can reduce our sitting time. Several obstacles that limit the ... [more ▼]

Walking meetings are a promising means to improve healthy behavior at work. By providing a physically active way of working, walking meetings can reduce our sitting time. Several obstacles that limit the social acceptance and wider adoption of walking meeting practice have been highlighted in previous research. Amongst these, the difficulty to take notes or present files is a recurring concern for office workers. To address these barriers, we designed the Hub, a network of stand-up meeting stations that accommodate different work-related tasks during walking meetings. We report on two pilot user tests investigating users' experiences and ideas for improvement, and present future research steps. We discuss the usefulness and relevance of the Hub concept to overcome the obstacles associated with walking meetings. © 2020 Owner/Author. [less ▲]

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See detailPrevalence of Mild Cognitive Impairment in Latin America and the Caribbean: A Systematic Review
Ribeiro, Fabiana UL; Teixeira-Santos, Carolina; Leist, Anja UL

in Innovation in Aging (2020), 4(S1), 897898

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See detailExamining the Relation Among Subjective Age and Working Memory in Old Age on a High-Frequency Basis Across 7 Days
Lücke, Anna; Siebert, Jelena; Schilling, Oliver et al

in Innovation in Aging (2020), 4(Supplement_1), 598-598

While increasing longitudinal evidence suggests that negative age views accelerate cognitive decline and increase dementia risk, we know little about such co-variance dynamics on a daily basis. We make ... [more ▼]

While increasing longitudinal evidence suggests that negative age views accelerate cognitive decline and increase dementia risk, we know little about such co-variance dynamics on a daily basis. We make use of subjective age and working memory performance data obtained six times a day over seven consecutive days as people went about their daily routines from 123 young-old (aged 66-69 years, 47.2% women) and 42 old-old (aged 86-90 years, 55.8% women) adults. Notably, multilevel models revealed considerably-sized short-term intra-individual variation of subjective age and working memory within days and these short-term within-day fluctuations in subjective age and working memory were coupled as expected. Hence, increased subjective age went along with lowered working memory confirming previous research. However, the respective between-day associations appeared reversed. Given this evidence of correlated short-term variability, we also discuss implications of different change dynamics that might explain moment-to-moment versus day-to-day associations between subjective age and working memory. [less ▲]

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See detailThe low-dimensional algebraic cohomology of the Witt and the Virasoro algebra with values in natural modules
Ecker, Jill Marie-Anne UL; Schlichenmaier, Martin UL

in Banach Center Publications (2020)

The main aim of this contribution is to compute the low-dimensional algebraic cohomology of the Witt and the Virasoro algebra with values in the adjoint and the trivial module. The last section includes ... [more ▼]

The main aim of this contribution is to compute the low-dimensional algebraic cohomology of the Witt and the Virasoro algebra with values in the adjoint and the trivial module. The last section includes results for the general tensor densities modules, presented without proof. One of our main results is that the third algebraic cohomology of the Witt algebra with values in the adjoint module vanishes, while it is one-dimensional for the Virasoro algebra. The first and the second algebraic cohomology of the Witt and the Virasoro algebra with values in tensor densities modules vanish for almost all modules. In the case they do not vanish, we give explicit expressions for the generating cocycles. In our work, we consider algebraic cohomology and not only the sub-complex of continuous cohomology, meaning we do not put any continuity constraints on the cochains. Consequently, our results are independent of any choice of an underlying topology, and valid for any concrete realizations of the considered Lie algebras. [less ▲]

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See detailKummer theory for number fields
Perucca, Antonella UL; Sgobba, Pietro UL; Tronto, Sebastiano UL

in Proceedings of the Roman Number Theory Association (2020)

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See detailInterpretation of Support among Arguments
Yu, Liuwen; Markovich, Réka UL; van der Torre, Leon UL

in Legal Knowledge and Information Systems – Frontiers in Artificial Intelligence and Application Series (2020)

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See detailSocial Isolation, Loneliness and Well-being in the Covid-19 Crisis: A Look at Nursing Home Residents in Luxembourg
Albert, Isabelle UL; Hoffmann, Martine; Kornadt, Anna Elena UL et al

in Innovation in Aging (2020), 4(Supplement_1), 957-958

During the COVID-19 crisis, older adults, in particular those with underlying health conditions, were at a special risk for severe illness and mortality, and efforts were made to shield them from exposure ... [more ▼]

During the COVID-19 crisis, older adults, in particular those with underlying health conditions, were at a special risk for severe illness and mortality, and efforts were made to shield them from exposure to the virus. While measures of physical distancing and reduction of in-person contacts were necessary to prevent contraction, they hit residents of care settings particularly hard since visits from family and friends were banned and the risk for loneliness and social isolation increased. In the present study, we therefore gave the voice to nursing home residents and focused on their perceived loneliness and subjective well-being during the crisis. We were both interested in difficulties but also in personal resources and resilience factors that might protect older adults from negative mental health outcomes and help to maintain subjective well-being. A sample of N = 76 residents in care homes in the Grand Duchy of Luxembourg were interviewed by use of a standardized questionnaire during July and August 2020. Participants reported on their loneliness and life satisfaction during the crisis, on their self-regulatory strategies as well as on personal and social resources (e.g. self-efficacy, generativity, social support). Data will be analyzed by use of regression analysis to predict loneliness and well-being by risk and protective factors. Results will be discussed applying a life-span developmental and systemic perspective to understand the mutual interplay of individual, social and institutional resources to mitigate negative side effects of protective measures on care home residents. [less ▲]

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See detailViews on Aging and Well-Being in the Covid Crisis – A Longitudinal Study in Luxembourg
Kornadt, Anna Elena UL; Hoffmann, Martine; Murdock, Elke UL et al

in Innovation in Aging (2020), 4(Supplement_1), 961-961

During the Covid-Crisis, stereotypes of older adults as helpless and vulnerable were spread, and intergenerational conflict was stirred more or less openly. We thus focused on perceived ageism during the ... [more ▼]

During the Covid-Crisis, stereotypes of older adults as helpless and vulnerable were spread, and intergenerational conflict was stirred more or less openly. We thus focused on perceived ageism during the crisis and its effects on well-being and health of older adults. Since views on aging are multifaceted and can be both, risk and resource for individual development, we assessed people’s self-perceptions of aging (SPA) as social loss, continued growth and physical decline and subjective age (SA). We hypothesized that people with SPA of social loss and physical decline would be more susceptible to negative effects of perceived ageism, whereas those with SPA of continued growth and younger SA would be less affected. NT1 = 611 community-dwelling adults aged 60 – 98 (Mage = 69.92 years) were recruited in June 2020 online and via phone in Luxembourg. In September 2020, participants will be contacted again for a follow-up. Analyses with cross-sectional data show that participants who felt more discriminated reported lower life satisfaction after the onset of the crisis (r = -.35) and worse subjective health (r = -.14). SPA of social loss and higher SA increased the negative effect of ageism on well-being (beta = -.57) and subjective health (beta = -.53), respectively. Our results point to mid- and long-term consequences of age discriminatory and stereotype-based crisis communication for the well-being of older adults and the importance of individual SPA in critical situations. [less ▲]

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See detailSocial Roles, Subjective Age, and Gender: Exploring the Links in Later Life
Kornadt, Anna Elena UL

in Innovation in Aging (2020), 4(Supplement_1), 556-556

Subjective age (SA) is strongly linked to positive developmental outcomes and successful aging. The social roles people assume are supposed to impact SA, since they incorporate age-graded social ... [more ▼]

Subjective age (SA) is strongly linked to positive developmental outcomes and successful aging. The social roles people assume are supposed to impact SA, since they incorporate age-graded social experiences and age-stereotypic role expectations. Social roles are also strongly gendered, providing the opportunity to understand gender-specific processes of SA. This study investigates a broad range of social roles and their relation to older men and women’s SA in later life. N = 285 participants aged 50 to 86 years (Mage = 65.04, SD = 8.88) reported on 19 social roles and their SA. Higher commitment to social roles of continued development and engagement was related to a younger subjective age, above and beyond sociodemographic variables, physical and mental health, but only for younger men. Commitment to family roles was related to a younger subjective age only for older men. Implications for the gender-specific understanding of antecedents of SA are discussed. [less ▲]

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See detailThe office jungle: A vision for wildness to turn offices into jungles
Nieuweboer, I.; Damen, I.; Brombacher, H. et al

in DIS 2020 Companion - Companion Publication of the 2020 ACM Designing Interactive Systems Conference (2020)

The Office Jungle is an experimental office environment designed to make offices more "wild". Through this demonstration and associated design vision, we make a first attempt to reflect on and to define ... [more ▼]

The Office Jungle is an experimental office environment designed to make offices more "wild". Through this demonstration and associated design vision, we make a first attempt to reflect on and to define what characterizes wildness and how it could empower people in more playful and active lifestyles, particularly in the workplace. In our understanding, wildness is not an exclusive property of nature, but rather a condition that can be designed for. How wildness can be designed is described here in a set of design principles called "Design for Wildness", inspired by the work of Gibson. The Office Jungle, a large geodesic sphere of 2 meters in diameter, is part and parcel of these design principles and can be used as a tool to design other wild environments. Such environments could benefit people working in the office, many of whom have been suffering the consequences of a sedentary lifestyle. © 2020 Owner/Author. [less ▲]

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See detailThe influence of well-being, social support, media use and sociodemographic factors on problematic social media sue among Luxembourgish adolescents
van Duin, Claire UL; Heinz, Andreas UL; Willems, Helmut Erich UL

in Cogent Medicine (2020), 7(1),

Background: Adolescents spend an increasing amount of time communicating online. Previous research has indicated that electronic media communication has been associated with positive outcomes on ... [more ▼]

Background: Adolescents spend an increasing amount of time communicating online. Previous research has indicated that electronic media communication has been associated with positive outcomes on adolescent well-being and development, however, problematic social media use is on the rise. This study investigates factors that influence problematic social media use (PSMU), based on previous empirical research and the Differential Susceptibility to Media Effects Model by Valkenburg and Peter (2013). Methods: The data used in this study stems from the 2018 Health Behaviour for School-aged Children (HBSC) study in Luxembourg. Data from elementary and secondary school students aged 11 to 18 was used (N = 6164), which was collected through a written survey. A four-stage hierarchical multiple regression analysis was conducted using SPSS, with problematic social media use as the dependent variable. 14 independent variables were included in the model, added in four blocks: sociodemographic factors, social support factors, well-being factors and media use factors.Results: The results indicate that in stage one of the hierarchical regression, the sociodemographic predictors accounted for 3% of the variation in problematic social media use. The addition of the social support factors to the model in stage two explained an additional 7% of the variation in problematic social media use, and the addition of the well-being factors in stage three an additional 5.3%. In stage four of the hierarchical regression media use factors were added to the model, and the four blocks of predictors accounted for 22.2% of the variation in problematic social media use (Adjusted R2 = 0.222). The most important predictors for problematic social media use were preference for online social interaction (β = 0.205, p < .001), the intensity of electronic media communication (β = 0.155, p < .001), psychosomatic complaints (β = 0.136, p < .001), perceived stress (β = 0.122, p < .001) and cyberbullying perpetration (β = 0.117, p < .001). Conclusions: The block of sociodemographic factors contributed minimally to the explanation of the variance in problematic social media use in the model. The most important predictors for problematic social media use were preference for online social interaction, the intensity of electronic media communication, psychosomatic complaints, perceived stress and cyberbullying perpetration. This suggests that there are several starting points for the prevention of problematic social media use among adolescents. [less ▲]

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See detailSecurity and Privacy in Resource-Constrained Devices
Chiara, Pier Giorgio UL

in CEUR Workshop Proceedings (2020), 2598

Recent adversarial attacks have been shown IoT devices weaknesses due to their limited computing power. Given also their ubiquitous presence, lower costs and limitations in keeping security measures up ... [more ▼]

Recent adversarial attacks have been shown IoT devices weaknesses due to their limited computing power. Given also their ubiquitous presence, lower costs and limitations in keeping security measures up-todate, resource-constrained devices represent a growing risk for the security of IT infrastructure. The scope of the research is to investigate the weaknesses of resource-constrained IoT devices. The methodology for the investigation is the legal analysis of existing legal frameworks regulating IoT cybersecurity and data security; afterwards it will be carried out a critical evaluation of the existing best practices. This critical analysis should face the twofold challenge of increasing transparency and trust in resource-constrained systems. Users and companies are two faces of the same coin: accountability of data collectors and user awareness are crucial in the security and data protection debate. Thus, a comprehensive overview of the relevant legal frameworks and guidelines would increase the understanding of risks of the users, whilst data controllers (especially of small and medium enterprises) may have an instrument to implement properly security measures. [less ▲]

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See detailIvy: Reading a critical design for sedentary behavior in the office context
Damen, Ida; Menheere, Daphne; Lallemand, Carine UL et al

in DIS 2020 Companion - Companion Publication of the 2020 ACM Designing Interactive Systems Conference (2020)

In this paper, we present and discuss Ivy, a critical artifact offering a novel design perspective on interventions that aim to reduce sedentary behavior in office workers. Ivy is an interactive office ... [more ▼]

In this paper, we present and discuss Ivy, a critical artifact offering a novel design perspective on interventions that aim to reduce sedentary behavior in office workers. Ivy is an interactive office chair that represents the amount of sitting time through growing ivy strands. Using the matrix of common argument types by Bardzell et al., we propose a structured "reading" of Ivy, as an example supporting reasoned and accessible conversations about criticality in design. Our reading of Ivy emphasized that its criticality emerges mainly from data physicalization as a new form of interactivity intended to trigger reflectiveness. The insights of this design study contribute towards a critical perspective on designing interventions to reduce sedentary time and spark discussion amongst designers and researchers in the field of Human-Computer Interaction. © 2020 Owner/Author. [less ▲]

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See detailPrevalence of memory impairment 2000-2015 in Sao Paolo, Brazil
Ribeiro, Fabiana UL; de Oliveira Duarte, Yeda; Santos, Jair Licio Ferreira et al

in Alzheimer's and Dementia: the Journal of the Alzheimer's Association (2020), 16

Background: Decreases in prevalence of memory impairment and dementia over the last two decades have been observed in different countries for cohorts entering older age. We sought to explore the changes ... [more ▼]

Background: Decreases in prevalence of memory impairment and dementia over the last two decades have been observed in different countries for cohorts entering older age. We sought to explore the changes in prevalence of cognitive impairment across four waves of the Health, Welfare and Aging survey (SABE) with data collected in Sao Paolo, Brazil, in 2000, 2006, 2010, and 2015. Method: Mini Mental State Exam (MMSE) scores and covariate values were available for 5,191 respondents (62.4% female) aged 60 to 99 across four waves. Cognitive impairment was defined as having <=12 points on a 19-point abbreviated version of the MMSE. Age group, educational attainment (no formal schooling, primary, secondary, post-secondary), self-reported heart disease, stroke, diabetes, hypertension, and BMI (<18.5, 18.5-24.9, 25-29.9, 30+) were adjusted for. Result: In more recent waves, prevalence of cognitive impairment was higher for respondents aged 60-64 years (9.0% in 2015 vs. 4.6% in 2000), 65-69 years (9.7% in 2015 vs. 5.8% in 2006) and 70-74 years (13.9% in 2015 vs. 5.8% in 2006). Between 2015 and 2000, respondents were increasingly more likely to report some formal education (90.8% vs. 75.3%), secondary (17.6% vs. 7.3%) or postsecondary education (11.4% vs. 4.3%). Respondents were increasingly more likely to report hypertension (66.5% vs. 54.2%), diabetes (28.7% vs. 17.8%), and be overweight/obese (74.1% vs. 58.9%). In age-adjusted logistic regressions, respondents in 2015 were more likely to show cognitive impairment compared to 2000 (OR 1.84, CI 1.20-2.82). Conclusion: SABE respondents showed higher prevalence of cognitive impairment in 2015 compared to respondents of the same age in earlier waves, but differences disappeared after adjusting for chronic disease burden and educational attainment. [less ▲]

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See detailMental health impact of the confinement measures during the COVID-19 pandemic
Pauly, Claire UL; Schroeder, Valerie; Pauly, Laure UL et al

in Innovation in Aging (2020), 4(S1), 952

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See detailLarge Intelligent Surface for Positioning in Millimeter Wave MIMO Systems
He, Jiguang; Wymeersch, Henk; Kong, Long UL et al

in 2020 IEEE 91st Vehicular Technology Conference (VTC2020-Spring) (2020)

Millimeter-wave (mmWave) multiple-input multiple-output (MIMO) system for the fifth generation (5G) cellular communications can also enable single-anchor positioning and object tracking due to its large ... [more ▼]

Millimeter-wave (mmWave) multiple-input multiple-output (MIMO) system for the fifth generation (5G) cellular communications can also enable single-anchor positioning and object tracking due to its large bandwidth and inherently high angular resolution. In this paper, we introduce the newly invented concept, large intelligent surface (LIS), to mmWave positioning systems, study the theoretical performance bounds (i.e., Cramér-Rao lower bounds) for positioning, and evaluate the impact of the number of LIS elements and the value of phase shifters on the position estimation accuracy compared to the conventional scheme with one direct link and one non-line-of-sight path. It is verified that better performance can be achieved with a LIS from the theoretical analyses and numerical study. [less ▲]

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See detailPositionPeak: Stimulating position changes during meetings
Damen, Ida; Heerkens, Lidewij; Van Den Broek, Annabel et al

in Conference on Human Factors in Computing Systems - Proceedings (2020)

In office environments, workers spend the majority of their workday sitting in a static position behind a desk or around a meeting table. Prolonged sitting time and sedentary behavior have severe negative ... [more ▼]

In office environments, workers spend the majority of their workday sitting in a static position behind a desk or around a meeting table. Prolonged sitting time and sedentary behavior have severe negative health effects. Through this explorative study, we studied how different postures can be stimulated during meetings. We designed PositionPeak: three pieces of furniture aimed at composing a 'dynamic meeting room', subtly encouraging participants to avoid static postures. We video-recorded 5 meetings (N=16) and coded the number of position changes per participant. Participants also filled out a pre- and post-questionnaire about their experience. Our findings show that PositionPeak triggers people to adopt a variety of postures. Participants on average experienced a more efficient meeting but reported physical discomfort with some objects. We discuss the influence of PositionPeak on the meetings' social dynamics, the acceptance of new conventions and design recommendations for new meeting facilities. © 2020 Owner/Author. [less ▲]

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See detailUsing cohort data to emulate lifestyle interventions: Long-term beneficial effects of initiating physical activity on cognitive decline and dementia
Leist, Anja UL; Muniz-Terrera, Graciela; Solomon, Alina

in Alzheimer's and Dementia: the Journal of the Alzheimer's Association (2020), 16

Background: Intervention studies have shown beneficial short-term effects of physical activity on cognitive decline and reduced risk of dementia. However, randomized controlled trial data of lifestyle ... [more ▼]

Background: Intervention studies have shown beneficial short-term effects of physical activity on cognitive decline and reduced risk of dementia. However, randomized controlled trial data of lifestyle interventions over long time spans are not available due to lack of resources, feasibility or ethical reasons. Drawing from the principles of emulating a ‘target trial’, which apply design principles of randomized trials to the analysis of observational data, cohort data of a large European survey were analyzed to understand the long-term effects of physical activity changes. Method: Biennial assessments of the economic, social, and health situation of respondents aged 50 and older came from the Survey of Health, Ageing and Retirement in Europe (2004-2017). Cognitive functioning (immediate recall, delayed recall, and verbal fluency) and self-reported diagnosis of dementia were assessed at each follow-up. The target trial included sedentary respondents at t1 who, at follow-up (t2), stayed sedentary (“control group”) or newly reported vigorous physical activity more often than once a week (initiators, “treatment group”). Inclusion and exclusion criteria were implemented as close as possible to those of the FINGER trial. Inverse-probability weighting accounted for the probability of initiating physical activity with a large set of predictor variables. Selecting respondents aged 50-85 years old who met the target trial inclusion and exclusion criteria, assessments of cognitive functioning and self-reported diagnosis of dementia were available for 8,781 respondents at t3 (on average 3.02 years later), 3,858 respondents at t4 (5.84 years), and 2,304 respondents at t5 (7.72 years). A total of 304 respondents reported a diagnosis of dementia. Result: Initiators of vigorous physical activity had higher cognitive functioning at two follow-ups compared to non-initiators (t3: “average treatment effect on the treated”, ATET=0.059, CI: 0.028, 0.090), which remained significant after implementing inclusion and exclusion criteria. Initiators had lower risk of dementia compared to non-initiators at all three follow-ups (t3: ATET=-0.009, CI: -0.015, -0.005, relative risk decrease -46.7%), remaining significant after implementing inclusion and exclusion criteria. Conclusion: Emulating a target trial showed long-term benefits of initiating physical activity for cognitive functioning and dementia risk. Multidomain interventions related to nutrition, social, cognitive activities etc. can be similarly emulated. [less ▲]

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See detailIvy: A qualitative interface to reduce sedentary behavior in the office context
Menheere, Daphne; Damen, Ida; Lallemand, Carine UL et al

in DIS 2020 Companion - Companion Publication of the 2020 ACM Designing Interactive Systems Conference (2020)

This paper describes Ivy, an office chair that represents sitting time of an office worker through growing ivy strands. The longer one sits, the more strands will grow onto the chair. By means of a ... [more ▼]

This paper describes Ivy, an office chair that represents sitting time of an office worker through growing ivy strands. The longer one sits, the more strands will grow onto the chair. By means of a qualitative interface called Ivy, we illustrate a design approach that is currently underrepresented in sedentary behavior interventions. With this approach, we counter the current trend of digitalization and quantification of health interventions. Instead of graphs and numbers, Ivy uses data physicalization as a qualitative interface that represents sitting. We describe the design, the process, and future research steps of Ivy as a critical perspective on sedentary behavior interventions. We aim to spark discussion amongst designers and researchers in the field of Human-Computer Interaction to use qualitative interfaces as a promising approach to deepen the user's relationship with the targeted behavior and enrich the ability to construct meaning from the feedback. © 2020 Owner/Author. [less ▲]

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See detailLinear system identification from ensemble snapshot observations
Aalto, Atte UL; Goncalves, Jorge UL

in Proceedings of the IEEE Conference on Decision and Control (2019, December)

Developments in transcriptomics techniques have caused a large demand in tailored computational methods for modelling gene expression dynamics from experimental data. Recently, so-called single-cell ... [more ▼]

Developments in transcriptomics techniques have caused a large demand in tailored computational methods for modelling gene expression dynamics from experimental data. Recently, so-called single-cell experiments have revolutionised genetic studies. These experiments yield gene expression data in single cell resolution for a large number of cells at a time. However, the cells are destroyed in the measurement process, and so the data consist of snapshots of an ensemble evolving over time, instead of time series. The problem studied in this article is how such data can be used in modelling gene regulatory dynamics. Two different paradigms are studied for linear system identification. The first is based on tracking the evolution of the distribution of cells over time. The second is based on the so-called pseudotime concept, identifying a common trajectory through the state space, along which cells propagate with different rates. Therefore, at any given time, the population contains cells in different stages of the trajectory. Resulting methods are compared in numerical experiments. [less ▲]

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See detailHardware Precoding Demonstration in Multi-Beam UHTS Communications under Realistic Payload Characteristics
Merlano Duncan, Juan Carlos UL; Querol Borras, Jorge UL; Maturo, Nicola UL et al

in Proceedings of the 37th International Communications Satellite Systems Conference (2019, November 01)

In this paper, we present a new hardware test-bed to demonstrate closed-loop precoded communications for interference mitigation in multi-beam ultra high throughput satellite systems under realistic ... [more ▼]

In this paper, we present a new hardware test-bed to demonstrate closed-loop precoded communications for interference mitigation in multi-beam ultra high throughput satellite systems under realistic payload and channel impairments. We build the test-bed to demonstrate a real-time channel aided precoded transmission under realistic conditions such as the power constraints and satellite-payload non-linearities. We develop a scalable architecture of an SDR platform with the DVB-S2X piloting. The SDR platform consists of two parts: analog-to-digital (ADC) and digital-to-analog (DAC) converters preceded by radio frequency (RF) front-end and Field-Programmable Gate Array (FPGA) backend. The former introduces realistic impairments in the transmission chain such as carrier frequency and phase misalignments, quantization noise of multichannel ADC and DAC and non-linearities of RF components. It allows evaluating the performance of the precoded transmission in a more realistic environment rather than using only numerical simulations. We benchmark the performance of the communication standard in realistic channel scenarios, evaluate received signal SNR, and measure the actual channel throughput using LDPC codes. [less ▲]

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See detailAuto-encoding Robot State against Sensor Spoofing Attacks
Rivera, Sean UL; Lagraa, Sofiane UL; Iannillo, Antonio Ken UL et al

in International Symposium on Software Reliability Engineering (2019, October)

In robotic systems, the physical world is highly coupled with cyberspace. New threats affect cyber-physical systems as they rely on several sensors to perform critical operations. The most sensitive ... [more ▼]

In robotic systems, the physical world is highly coupled with cyberspace. New threats affect cyber-physical systems as they rely on several sensors to perform critical operations. The most sensitive targets are their location systems, where spoofing attacks can force robots to behave incorrectly. In this paper, we propose a novel anomaly detection approach for sensor spoofing attacks, based on an auto-encoder architecture. After initial training, the detection algorithm works directly on the compressed data by computing the reconstruction errors. We focus on spoofing attacks on Light Detection and Ranging (LiDAR) systems. We tested our anomaly detection approach against several types of spoofing attacks comparing four different compression rates for the auto-encoder. Our approach has a 99% True Positive rate and a 10% False Negative rate for the 83% compression rate. However, a compression rate of 41% could handle almost all of the same attacks while using half the data. [less ▲]

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See detailParametric study on non-ductile demountable shear connectors
Odenbreit, Christoph UL; Kozma, Andras UL

in ce/papers (2019, September), 3(3-4), 283-288

The basic principle of the circular economy is to reduce or totally eliminate waste and carbon dioxide production with the help of a multiple, efficient usage of resources. The application of reusable ... [more ▼]

The basic principle of the circular economy is to reduce or totally eliminate waste and carbon dioxide production with the help of a multiple, efficient usage of resources. The application of reusable structural elements plays an important role and can contribute essentially to a low-carbon future. Within the European research project REDUCE (Grant Agreement number: 710040), composite beams and steel-based flooring systems, which are demountable and reusable, have been developed and investigated. The experimental investigations showed that the structural behaviour of the newly developed shear connectors differs from the behaviour of the traditionally applied welded studs. Some behave in a non-ductile way. In order to assess, how far the regulations of EN1994-1-1 for shear connections can still be applied, parametric studies have been conducted. The respective numerical models were developed with the use of the commercially available finite element software ABAQUS® and were validated against the experimental observations. The effects of the lack of ductility of the shear connectors on the structural behaviour of the entire composite beam was examined with different types of shear connectors, shear connector layouts and material grades. This contribution presents the underlying laboratory tests as well as the results of the supplementing numerical parameter studies. The outcome provides valuable information for future design guidance concerning the use of demountable shear connectors in composite beams. [less ▲]

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See detailVisualization of AE's Training on Credit Card Transactions with Persistent Homology
Charlier, Jérémy Henri J. UL; Petit, François UL; Ormazabal, Gaston et al

in Proceedings of the International Workshop on Applications of Topological Data Analysis In conjunction with ECML PKDD 2019 (2019, September)

Auto-encoders are among the most popular neural network architecture for dimension reduction. They are composed of two parts: the encoder which maps the model distribution to a latent manifold and the ... [more ▼]

Auto-encoders are among the most popular neural network architecture for dimension reduction. They are composed of two parts: the encoder which maps the model distribution to a latent manifold and the decoder which maps the latent manifold to a reconstructed distribution. However, auto-encoders are known to provoke chaotically scattered data distribution in the latent manifold resulting in an incomplete reconstructed distribution. Current distance measures fail to detect this problem because they are not able to acknowledge the shape of the data manifolds, i.e. their topological features, and the scale at which the manifolds should be analyzed. We propose Persistent Homology for Wasserstein Auto-Encoders, called PHom-WAE, a new methodology to assess and measure the data distribution of a generative model. PHom-WAE minimizes the Wasserstein distance between the true distribution and the reconstructed distribution and uses persistent homology, the study of the topological features of a space at different spatial resolutions, to compare the nature of the latent manifold and the reconstructed distribution. Our experiments underline the potential of persistent homology for Wasserstein Auto-Encoders in comparison to Variational Auto-Encoders, another type of generative model. The experiments are conducted on a real-world data set particularly challenging for traditional distance measures and auto-encoders. PHom-WAE is the first methodology to propose a topological distance measure, the bottleneck distance, for Wasserstein Auto-Encoders used to compare decoded samples of high quality in the context of credit card transactions. [less ▲]

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See detailDifferent load‐bearing mechanisms in headed stud shear connections in composite beams with profiled steel sheeting
Vigneri, Valentino UL; Odenbreit, Christoph UL; Lam, Dennis

in ce/papers (2019, September), 3(3-4), 231-236

The current regulations of EN1994-1-1 for headed stud shear connections in composite beams with profiled sheeting lead, for some configurations, to an over-estimation of the load-bearing capacity. Since ... [more ▼]

The current regulations of EN1994-1-1 for headed stud shear connections in composite beams with profiled sheeting lead, for some configurations, to an over-estimation of the load-bearing capacity. Since these design equations are based on empirical considerations, they are not able to capture the real mechanical behaviour of the connector and they do not consider appropriately the influence of the geometry of sheeting on the shear capacity. For this reason, the load-bearing mechanisms of the shear connection are identified in this work with the support of experimental and numerical results. According to the static system presented, the concrete rib is modelled as a system of diagonal struts acting simultaneously in combination with the stud in bending. It is observed that at 2÷4 mm slip, a ?Strut and beam? mechanism prevails where the resistance of the connector depends mostly on the plastic hinges activated in the stud and on the capacity of the diagonal strut in front of it. By increasing the slip (ca. 4÷10 mm), the surrounding concrete progressively crushes while the tensile stresses at the edge of the rib reach the tensile strength of the material. As a consequence of this loss of rotational stiffness, the bending capacity developed in the stud reduces and the upper hinges gradually moves towards the slab. At higher displacements (ca. 20÷40 mm), due to nonlinear geometric effects, high tensile forces develop in the stud and the load is carried through a ?Strut and Tie? resistance mechanism, if the embedment of the stud is sufficient. By further increasing the slip, the whole rib rotates or the failure occurs either for concrete pull-out or stud rupture. This contribution describes the sequence of the activated load-bearing mechanisms in headed stud shear connections with profiled steel sheeting at different displacements. [less ▲]

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See detailMQLV: Optimal Policy of Money Management in Retail Banking with Q-Learning
Charlier, Jérémy Henri J. UL; Ormazabal, Gaston; State, Radu UL et al

in Proceedings of the Fourth Workshop on MIning DAta for financial applicationS (MIDAS 2019) co-located with the 2019 European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML-PKDD 2019) (2019, September)

Reinforcement learning has become one of the best approach to train a computer game emulator capable of human level performance. In a reinforcement learning approach, an optimal value function is learned ... [more ▼]

Reinforcement learning has become one of the best approach to train a computer game emulator capable of human level performance. In a reinforcement learning approach, an optimal value function is learned across a set of actions, or decisions, that leads to a set of states giving different rewards, with the objective to maximize the overall reward. A policy assigns to each state-action pairs an expected return. We call an optimal policy a policy for which the value function is optimal. QLBS, Q-Learner in the Black-Scholes(-Merton) Worlds, applies the reinforcement learning concepts, and noticeably, the popular Q-learning algorithm, to the financial stochastic model of Black, Scholes and Merton. It is, however, specifically optimized for the geometric Brownian motion and the vanilla options. Its range of application is, therefore, limited to vanilla option pricing within the financial markets. We propose MQLV, Modified Q-Learner for the Vasicek model, a new reinforcement learning approach that determines the optimal policy of money management based on the aggregated financial transactions of the clients. It unlocks new frontiers to establish personalized credit card limits or bank loan applications, targeting the retail banking industry. MQLV extends the simulation to mean reverting stochastic diffusion processes and it uses a digital function, a Heaviside step function expressed in its discrete form, to estimate the probability of a future event such as a payment default. In our experiments, we first show the similarities between a set of historical financial transactions and Vasicek generated transactions and, then, we underline the potential of MQLV on generated Monte Carlo simulations. Finally, MQLV is the first Q-learning Vasicek-based methodology addressing transparent decision making processes in retail banking. [less ▲]

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See detailARCHITECTURES AND SYNCHRONIZATION TECHNIQUES FOR COHERENT DISTRIBUTED REMOTE SENSING SYSTEMS
Merlano Duncan, Juan Carlos UL; Querol Borras, Jorge UL; Camps, Adriano et al

in 2019 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) (2019, August 31)

Phase, frequency and time synchronization is a crucial requirement for many applications as such as multi-static remote sensing and distributed beamforming for communications. The literature on the field ... [more ▼]

Phase, frequency and time synchronization is a crucial requirement for many applications as such as multi-static remote sensing and distributed beamforming for communications. The literature on the field is very wide, and in some cases, the requirements of the proposed synchronization solution may surpass the ones set by the application itself. Moreover, the synchronization solution becomes even more challenging when the nodes are flying or hovering on aerial or space platforms. In this work, we compare and classify the synchronization technologies available in the literature according to a common proposed framework, and we discuss the considerations of an implementation for distributed remote sensing applications. The general framework considered is based on a distributed collection of autonomous nodes that try to synchronize their clocks with a common reference. Moreover, they can be classified in non-overlapping, adjacent and overlapping frequency band scenarios [less ▲]

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See detailPANAS- Project: Heat Transfer Model Development for Passive Safety Systems,
Leyer, Stephan UL; Hampel; Schuster, C et al

in NURETH-18 (2019, August 18)

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See detailDISPUTool -- A tool for the Argumentative Analysis of Political Debates
Haddadan, Shohreh UL; Villata, Serena; Cabrio, Elena

in Proceedings of the Twenty-Eighth International Joint Conference on Artificial Intelligence, {IJCAI-19} (2019, August 14)

Political debates are the means used by political candidates to put forward and justify their positions in front of the electors with respect to the issues at stake. Argument mining is a novel research ... [more ▼]

Political debates are the means used by political candidates to put forward and justify their positions in front of the electors with respect to the issues at stake. Argument mining is a novel research area in Artificial Intelligence, aiming at analyzing dis-course on the pragmatics level and applying a certain argumentation theory to model and automatically analyze textual data. In this paper, we present DISPUTool, a tool designed to ease the work of historians and social science scholars in analyzing the argumentative content of political speeches. More precisely, DISPUTool allows to explore and automatically identify argumentative components over the 39 political debates from the last 50 years of US presidential campaigns (1960-2016). [less ▲]

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See detailGet to know your geek: towards a sociological understanding
Karadeniz, Oguz Özgür; Schiffner, Stefan UL

in Data for Better Living: AI and Privacy (2019, August)

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See detailSurface characterization of epitaxial Cu-rich CuInSe2 absorbers
Martin Lanzoni, Evandro UL; Spindler, Conrad UL; Ramirez Sanchez, Omar UL et al

in IEEE Photovoltaic Specialists Conference. Conference Record (2019, July)

We investigated the electrical properties of epitaxial Cu-rich CuInSe 2 by Kelvin probe force microscopy (KPFM) under ambient and ultra-high vacuum conditions. We first measured the sample under ambient ... [more ▼]

We investigated the electrical properties of epitaxial Cu-rich CuInSe 2 by Kelvin probe force microscopy (KPFM) under ambient and ultra-high vacuum conditions. We first measured the sample under ambient conditions before and after potassium cyanide (KCN) etching. In both cases, we do not see any substantial contrast in the surface potential data; furthermore, after the KCN etching we observed outgrowths with a height around 2nm over the sample surface. On the other hand, the KPFM measurements under ultra-high vacuum conditions show a work function dependence according to the surface orientation of the Cu-rich CuInSe 2 crystal. Our results show the possibility to increase the efficiency of epitaxial Cu-rich CuInSe 2 by growing the materials in the appropriated surface orientation where the variations in work function are reduced. [less ▲]

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See detailA Model-driven Approach to Trace Checking of Temporal Properties with Aggregations
Boufaied, Chaima UL; Bianculli, Domenico UL; Briand, Lionel UL

in Journal of Object Technology (2019, July), 18(2), 151-21

The verification of complex software systems often requires to check quantitative properties that rely on aggregation operators (e.g., the average response time of a service). One way to ease the ... [more ▼]

The verification of complex software systems often requires to check quantitative properties that rely on aggregation operators (e.g., the average response time of a service). One way to ease the specification of these properties is to use property specification patterns, such as the ones for “service provisioning”, previously proposed in the literature. In this paper we focus on the problem of performing offline trace checking of temporal properties containing aggregation operators. We first present TemPsy-AG, an extension of TemPsy—an existing pattern-based language for the specification of temporal properties—to support service provisioning patterns that use aggregation operators. We then extend an existing model-driven procedure for trace checking, to verify properties expressed in TemPsy-AG. The trace checking procedure relies on the efficient mapping of temporal properties written in TemPsy-AG into OCL constraints on a meta-model of execution traces. We have implemented this procedure in the TemPsy-Check-AG tool and evaluated its performance: our approach scales linearly with respect to the length of the input trace and can deal with much larger traces than a state-of-the-art tool. [less ▲]

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See detailTogether or Alone: The Price of Privacy in Collaborative Learinig
Pejo, Balazs UL; Tang, Qiang; Biczók, Gergely

in Proceedings on Privacy Enhancing Technologies (2019, July)

Machine learning algorithms have reached mainstream status and are widely deployed in many applications. The accuracy of such algorithms depends significantly on the size of the underlying training ... [more ▼]

Machine learning algorithms have reached mainstream status and are widely deployed in many applications. The accuracy of such algorithms depends significantly on the size of the underlying training dataset; in reality a small or medium sized organization often does not have the necessary data to train a reasonably accurate model. For such organizations, a realistic solution is to train their machine learning models based on their joint dataset (which is a union of the individual ones). Unfortunately, privacy concerns prevent them from straightforwardly doing so. While a number of privacy-preserving solutions exist for collaborating organizations to securely aggregate the parameters in the process of training the models, we are not aware of any work that provides a rational framework for the participants to precisely balance the privacy loss and accuracy gain in their collaboration. In this paper, by focusing on a two-player setting, we model the collaborative training process as a two-player game where each player aims to achieve higher accuracy while preserving the privacy of its own dataset. We introduce the notion of Price of Privacy, a novel approach for measuring the impact of privacy protection on the accuracy in the proposed framework. Furthermore, we develop a game-theoretical model for different player types, and then either find or prove the existence of a Nash Equilibrium with regard to the strength of privacy protection for each player. Using recommendation systems as our main use case, we demonstrate how two players can make practical use of the proposed theoretical framework, including setting up the parameters and approximating the non-trivial Nash Equilibrium. [less ▲]

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See detailUser Experience challenges for designing and evaluating Computer-Based Assessments for children
Lehnert, Florence Kristin UL

in IDC '19 Proceedings of the 18th ACM International Conference on Interaction Design and Children (2019, June 12)

Computer-Based Assessment (CBA), i.e., the use of computers instead of paper & pencil for testing purposes is now increasingly used, both in education and in the workforce. Along with this trend, several ... [more ▼]

Computer-Based Assessment (CBA), i.e., the use of computers instead of paper & pencil for testing purposes is now increasingly used, both in education and in the workforce. Along with this trend, several issues regarding the usage of computers in assessment can be raised. With respect to CBA, test validity and acceptance appear at stake during interacting with a complex assessment system. For instance, individual differences in computer literacy (i.e. ability to handle technology) might cause different outcomes that are not related to the problem-solving task. Prior investigation has shown that there is a scarcity of research on the User Experience (UX) in the context of CBA, also due to a focus on adult users. This doctoral thesis aims to adapt and develop new evaluation methods from the Human-Computer Interaction (HCI) field, applied in the context of CBA. The contributions will result in the development of best practices guidelines for both research and practitioners by adopting design and evaluation methods drawn from the field of Child-computer Interaction (CCI). [less ▲]

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See detailTowards a high-resolution drone-based 3D mapping dataset to optimise flood hazard modelling
Backes, Dietmar UL; Schumann, Guy; Teferle, Felix Norman UL et al

in International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (2019, June), XLII-2/W13

The occurrence of urban flooding following strong rainfall events may increase as a result of climate change. Urban expansion, ageing infrastructure and an increasing number of impervious surfaces are ... [more ▼]

The occurrence of urban flooding following strong rainfall events may increase as a result of climate change. Urban expansion, ageing infrastructure and an increasing number of impervious surfaces are further exacerbating flooding. To increase resilience and support flood mitigation, bespoke accurate flood modelling and reliable prediction is required. However, flooding in urban areas is most challenging. State-of-the-art flood inundation modelling is still often based on relatively low-resolution 2.5 D bare earth models with 2-5m GSD. Current systems suffer from a lack of precise input data and numerical instabilities and lack of other important data, such as drainage networks. Especially, the quality and resolution of the topographic input data represents a major source of uncertainty in urban flood modelling. A benchmark study is needed that defines the accuracy requirements for highly detailed urban flood modelling and to improve our understanding of important threshold processes and limitations of current methods and 3D mapping data alike. This paper presents the first steps in establishing a new, innovative multiscale data set suitable to benchmark urban flood modelling. The final data set will consist of high-resolution 3D mapping data acquired from different airborne platforms, focusing on the use of drones (optical and LiDAR). The case study includes residential as well as rural areas in Dudelange/Luxembourg, which have been prone to localized flash flooding following strong rainfall events in recent years. The project also represents a cross-disciplinary collaboration between the geospatial and flood modelling community. In this paper, we introduce the first steps to build up a new benchmark data set together with some initial flood modelling results. More detailed investigations will follow in the next phases of this project. [less ▲]

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See detailPredicting Sparse Clients' Actions with CPOPT-Net in the Banking Environment
Charlier, Jérémy Henri J. UL; State, Radu UL; Hilger, Jean UL

in 32nd Canadian Conference on Artificial Intelligence Proceedings (2019, May)

The digital revolution of the banking system with evolving European regulations have pushed the major banking actors to innovate by a newly use of their clients' digital information. Given highly sparse ... [more ▼]

The digital revolution of the banking system with evolving European regulations have pushed the major banking actors to innovate by a newly use of their clients' digital information. Given highly sparse client activities, we propose CPOPT-Net, an algorithm that combines the CP canonical tensor decomposition, a multidimensional matrix decomposition that factorizes a tensor as the sum of rank-one tensors, and neural networks. CPOPT-Net removes efficiently sparse information with a gradient-based resolution while relying on neural networks for time series predictions. Our experiments show that CPOPT-Net is capable to perform accurate predictions of the clients' actions in the context of personalized recommendation. CPOPT-Net is the first algorithm to use non-linear conjugate gradient tensor resolution with neural networks to propose predictions of financial activities on a public data set. [less ▲]

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See detailComparison of boundary treatments in thermal Lattice Boltzmann simulations of moving particles in fluids
Rosemann, T; Kravets, B; Kruggel-Emden, H et al

in Particle Technology Series (2019, April 09)

Various numerical schemes have been developed in recent years to simulate particle-laden flows. The Lattice Boltzmann method (LBM) has emerged as an efficient tool for direct numerical simulations in ... [more ▼]

Various numerical schemes have been developed in recent years to simulate particle-laden flows. The Lattice Boltzmann method (LBM) has emerged as an efficient tool for direct numerical simulations in which the flow field around the particles can be fully resolved. In the thermal Lattice Boltzmann method not only the flow field but also the temperature field is calculated by using one distribution function for the fluid density and one for the fluid temperature. The treatment of curved solid-fluid boundaries is crucial for the simulation of particulate flows with this method. While several aspects of moving boundaries have been discussed in previous studies for the non-thermal LBM, it remains unknown to what extend these findings are transferable to the thermal LBM. In this work, we consider a 3D thermal LBM with a multiple-relaxation-time (MRT) collision operator and compare different techniques that can be applied to handle the moving boundary. There are three key aspects in the LBM that need to be considered at the boundary: the momentum exchange method calculating the drag force acting upon particles, the bounce-back scheme determining the bounce-back of density distribution functions at a boundary, and the refilling algorithm assigning a value to the unknown density distribution functions at lattice nodes uncovered by the particle. First, we demonstrate how the choice of the technique to address these problems in the flow field impacts the results for the temperature field in the thermal LBM. In a second step, we focus on the thermal side where similar techniques need to be applied. We compare different refilling strategies and bounce-back schemes for the temperature distribution functions and assess heat transfer calculation methods for the particle surface. The performance of these implementations is evaluated by comparing the simulation results in terms of accuracy and stability for a moving particle in a channel flow with a Galilean invariant reference system in which the particle’s position is fixed. We conduct this analysis for various Reynolds and Prandtl numbers to test the applicability of the individual techniques to varying flow conditions. Moreover, we demonstrate the potential of the implementation found to be superior by considering a more complex flow field in a particle packing. Our findings serve as a guideline for choosing suitable moving boundary treatments in thermal LBM simulations of particle-laden flows. [less ▲]

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See detailAn interface resolved immersed boundary method in XDEM for particulate flow simulations
Wu, Mingqiu UL; Peters, Bernhard UL; Rosemann, Tony et al

in International Congress on Particle Technology (2019, April 09)

immersed boundary method (IBM) has recently been used for particulate flows and complex fluid-solid interaction problems. The IBM was first introduced by Peskin to simulate blood flow in a beating heart ... [more ▼]

immersed boundary method (IBM) has recently been used for particulate flows and complex fluid-solid interaction problems. The IBM was first introduced by Peskin to simulate blood flow in a beating heart. Later it has been extended for a different range of applications. The advantages of IBM over the body-fitted method is that it substantially simplified grid generation for immersed geometries, and it is easier to handle moving boundary situations. IBM even allows the use of a stationary and non-deformation background mesh, as well as it reduces the cost of computation by avoiding generation of a body-fitted mesh for each time step. However, the IBM approach is not straightforward to implement and it requires special techniques for cut-off boundary cells as well as special techniques for data point interpolations. Generally, the IBM is classified into two approaches based on the methods of imposing the boundary condition in the immersed body. The first approach is called fictitious domain method with continuous forcing scheme which employs a distributed forcing function to impose a rigidity boundary condition in the solid particle domain. The second one is the discrete forcing approach, which enables a sharp interface to represent the immersed surface. The IBM discussed in this work is a combination of these above two approaches: we first employ the continuous forcing scheme to get a first-step approximation of the immersed body, then use an interpolation polynomial to impose a desired accurate physical boundary for each immersed boundary point based on a least square interpolation reconstruction scheme. Particle motions can be calculated and tracked by solving Newton’s equations of motions using the extended discrete element method (XDEM) while the data of fluid flow properties are obtained by solving the Navier-Stokes equations which govern the fluid phase. Combined this leads to the basic concept of DEM-CFD coupling. Therefore, a particle interface resolved simulation solver is developed by coupling the XDEM and IBM approaches together. Consequently, this solver is then used to handle both static and dynamic particle problems as well as particle packed bed simulations. The validation of the solver can be performed by setting one static sphere in a channel and evaluate the drag coefficients and Strouhal number (when shedding occurs) at various Reynolds [less ▲]

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See detailSecurity – Visible, Yet Unseen? How Displaying Security Mechanisms Impacts User Experience and Perceived Security
Distler, Verena UL; Zollinger, Marie-Laure UL; Lallemand, Carine UL et al

in Proceedings of ACM CHI Conference on Human Factors in Computing Systems (CHI2019) (2019, April)

An unsolved debate in the field of usable security concerns whether security mechanisms should be visible, or blackboxed away from the user for the sake of usability. However, tying this question to ... [more ▼]

An unsolved debate in the field of usable security concerns whether security mechanisms should be visible, or blackboxed away from the user for the sake of usability. However, tying this question to pragmatic usability factors only might be simplistic. This study aims at researching the impact of displaying security mechanisms on user experience (UX) in the context of e-voting. Two versions of an e-voting application were designed and tested using a between-group experimental protocol (N=38). Version D displayed security mechanisms, while version ND did not reveal any security-related information. We collected data on UX using standardised evaluation scales and semi-structured interviews. Version D performed better overall in terms of UX and need fulfilment. Qualitative analysis of the interviews gives further insights into factors impacting perceived security. Our study adds to existing research suggesting a conceptual shift from usability to UX and discusses implications for designing and evaluating secure systems. [less ▲]

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See detailTranslingual Discursive Spaces in Language and Arts Lessons
Degano, Sarah UL

in Literacy Information and Computer Education Journal (2019, March), 10(1), 3094-3102

Flexible multilingual pedagogies such as translanguaging pedagogies are promising stepping stones towards a more equitable access to educational resources for students of different backgrounds. Recent ... [more ▼]

Flexible multilingual pedagogies such as translanguaging pedagogies are promising stepping stones towards a more equitable access to educational resources for students of different backgrounds. Recent research in Luxembourgish preschool, Year 1 and Year 2 classes, show that teachers have begun to implement such pedagogies by encouraging the deployment of the students’ full linguistic repertoires, including their home languages. Little attention has however been paid to the later years of primary school where the achievement gap between students with and without a migration background is particularly high. The present qualitative longitudinal study focusses on students in Years 4 and 5 and examines to what extent they deploy their linguistic repertoires in interaction with their peers. Drawing on observations, recordings and interviews, this paper explores the language use of two Portuguese-speaking 4th graders in Language and Arts lessons. Findings show that the students mobilize their linguistic and cultural resources to different extents and, hereby, open or close translingual discursive spaces for further exchange. The findings should contribute to the understanding of multilingual students’ language practices and provide insight into how their linguistic and cultural resources can be capitalized on. [less ▲]

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See detailFunctional Interpretation of Single Amino Acid Substitutions in 1,330 Disease-Associated Genes
Iqbal, Sumaiya; Jespersen, Jakob Berg; Perez-Palma, Eduardo et al

in Biophysical Journal (2019, February 15), 116(3), 420-421

Elucidating molecular consequences of amino-acid-altering missense variants at scale is challenging. In this work, we explored whether features derived from three-dimensional (3D) protein structures can ... [more ▼]

Elucidating molecular consequences of amino-acid-altering missense variants at scale is challenging. In this work, we explored whether features derived from three-dimensional (3D) protein structures can characterize patient missense variants across different protein classes with similar molecular level activities. The identified disease-associated features can advance our understanding of how a single amino acid substitution can lead to the etiology of monogenic disorders. For 1,330 disease-associated genes (>80%, 1,077/1,330 implicated in Mendelian disorders), we collected missense variants from the general population (gnomAD database, N=164,915) and patients (ClinVar and HGMD databases, N=32,923). We in silico mapped the variant positions onto >14k human protein 3D structures. We annotated the protein positions of variants with 40 structural, physiochemical, and functional features. We then grouped the genes into 24 protein classes based on their molecular functions and performed statistical association analyses with the features of population and patient variants. We identified 18 (out of 40) features that are associated with patient variants in general. Specifically, patient variants are less exposed to solvent (p<1.0e-100), enriched on b-sheets (p<2.37e-39), frequently mutate aromatic residues (p<1.0e-100), occur in ligand binding sites (p<1.0e-100) and are spatially close to phosphorylation sites (p<1.0e-100). We also observed differential protein-class-specific features. For three protein classes (signaling molecules, proteases and hydrolases), patient variants significantly perturb the disulfide bonds (p<1.0e-100). Only in immunity proteins, patient variants are enriched in flexible coils (p<1.65e-06). Kinases and cell junction proteins exhibit enrichment of patient variants around SUMOylation (p<1.0e-100) and methylation sites (p<9.29e-11), respectively. In summary, we studied shared and unique features associated with patient variants on protein structure across 24 protein classes, providing novel mechanistic insights. We generated an online resource that contains amino-acid-wise feature annotation-track for 1,330 genes, summarizes the patient-variant-associated features on residue level, and can guide variant interpretation. [less ▲]

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See detailDismountable Flooring Systems for Multiple Use
Odenbreit, Christoph UL; Kozma, Andras UL

in IOP Conference Series: Earth and Environmental Science (2019, February), 225

Steel shapes our modern world as an integral part of the global construction economy. In the last decades, the sustainability of steel grew and turned from a linear to a circular business, where the ... [more ▼]

Steel shapes our modern world as an integral part of the global construction economy. In the last decades, the sustainability of steel grew and turned from a linear to a circular business, where the material is fully recovered and recycled after use. The RFCS Research Project “REDUCE” of the European Commission goes one step beyond the mere material recycling and investigates, how the circular economy’s philosophy can be used to reduce the carbon footprint furthermore. On that basis, one target of the research was to develop basic modular and standardised structural load bearing elements which can be adapted in the building or assembled, properly disassembled and partly or entirely be reused again in a subsequent building. This paper presents the respective research results of demountable flooring- and beam systems: 15 large scale push-out tests and two large scale composite beam tests as well as numerous finite element simulations with ABAQUS have been performed at the Laboratory of the ArcelorMittal Chair of Steel and Façade Engineering. The suitability for dis- and re-assembly as well as the strength, stiffness, slip capacity and ductility have been determined. The investigated systems included pre-stressed and epoxy injected systems, as well as solid slabs and composite slabs with profiled decking. The results showed sometimes higher resistances and smaller displacement capacities than conventional systems. The numerical simulation results were presented as well as the results of the laboratory tests. First assessments were given about the respective consequences and about how these consequences could be considered in the layout of future steel composite structures. [less ▲]

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See detailHow to Assess the Usability Metrics of E-Voting Schemes
Marky, Karola; Zollinger, Marie-Laure UL; Funk, Markus et al

in Lecture Notes in Computer Science (2019, February)

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See detailSC2Share: Smart Contract for Secure Car Sharing
Akash, Madhusudan; Symeonidis, Iraklis UL; A. Mustafa, Mustafa et al

in International Conference on Information Systems Security and Privacy (ICISSP) (2019, January 24)

This paper presents an efficient solution for the booking and payments functionality of a car sharing system that allows individuals to share their personal, underused cars in a completely decentralized ... [more ▼]

This paper presents an efficient solution for the booking and payments functionality of a car sharing system that allows individuals to share their personal, underused cars in a completely decentralized manner, annulling the need of an intermediary. Our solution, named SC2Share, leverages smart contracts and uses them to carry out secure and private car booking and payments. Our experiments on SC2Share on the Ethereum testnet guarantee high security and privacy to its users and confirm that our system is cost-efficient and ready for practical use. [less ▲]

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See detailNovel Opportunities by Laser Welding of Dissimilar Materials
Schiry, Marc UL; Plapper, Peter UL

in Proceedings of International Conference on Competitive Manufacturing COMA'19 (2019, January)

The Laser Technology Competence Centre (LTCC) of the University of Luxembourg provides skills in joining material combinations, which are considered being non-weld able with traditional methods or at ... [more ▼]

The Laser Technology Competence Centre (LTCC) of the University of Luxembourg provides skills in joining material combinations, which are considered being non-weld able with traditional methods or at least challenging to join (e.g. Copper and Aluminium, Aluminium and Polyamide (PA), Titanium and PEEK, steel and tungsten hard alloy). Related accomplishments include minimal intermetallic compounds, convincing mechanical and superior electrical properties of the laser-welded specimen. With defined spatial and temporal modulation of the laser beam, an accurately defined temperature profile is created on the lower side of the upper material in the two dimensional directions, which enable joining of dissimilar materials in overlap configurations, despite challenging thermal properties. To weld butt-joint geometries with minimal heat affected volume, the temperature profiles were expanded in the third dimension, which can be achieved through controlled laser energy guidance. The scientific methods to accomplish these convincing results are explained, with selected industrial use cases ranging from automotive industry, energy storage, and medical implants. An outlook with unsolved challenges is intended to ignite discussions about upcoming research topics. [less ▲]

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See detailAggregation of MQTT Topics over Integrated Satellite Terrestrial Networks
Palattella, Maria Rita UL; Soua, Ridha UL; Stemper, André UL et al

in ACM SIGMETRICS Performance Evaluation Review (2019, January)

The MQTT application protocol was originally designed for monitoring a oil pipeline through the desert by collecting sensor data via satellite link. Thus, by design MQTT is very suitable for data ... [more ▼]

The MQTT application protocol was originally designed for monitoring a oil pipeline through the desert by collecting sensor data via satellite link. Thus, by design MQTT is very suitable for data collection over integrated satellite-terrestrial networks. Leveraging on the MQTT Bridge functionality, in this work we propose a novel architecture with two MQTT Brokers located at the satellite terminal and the satellite gateway. By using the topic pattern option, supported by the bridge, a subscriber can request several topics within a single request. To reduce the amount of traffic ex-changed over the satellite return channel, we introduce in the architecture a new entity, namely MQTT message aggregation filter, which aggregates all the MQTT topics matching the topic pattern in the same response. [less ▲]

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See detailBorder-Making and its Consequences: A Global Overview.
Venken, Machteld UL; Fellner, Astrid; Dorfman, Adriana et al

in Eurasia Border Review (2019, January), 10(1), 59-69

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See detailElucidation of influencing parameters of the laser butt welding process of dissimilar steel to tungsten alloy sheets
Schiry, Marc UL; Plapper, Peter UL

in Proceedings: International Conference on Competitive Manufacturing COMA'19 (2019, January)

Laser welding of steel - tungsten alloy joints requires deep understanding of the impact of the laser parameters on the welding process. Due to the dissimilar thermal and metallurgical properties of both ... [more ▼]

Laser welding of steel - tungsten alloy joints requires deep understanding of the impact of the laser parameters on the welding process. Due to the dissimilar thermal and metallurgical properties of both materials, a defined heat input and a precise temperature control in the weld interface is required. In the presented work, the influence of different laser parameter (e.g. laser power, focal position, scanner speed etc.) on the joint quality of laser welded steel / tungsten alloy butt-joints were investigated. By using statistical methods, the influencing process parameters were defined and optimized. It is shown that the horizontal focal position is the main parameter for the welding process in a butt-joint configuration. Additionally, manipulation of the heat input leads to modifications of the weld bead profile. By obtaining vertical seam boundaries in the sheet metal, a homogenous temperature profile at the interface of the materials to be welded was achieved. Due to the complete bonding and low amount of intermetallic phases, high shear strength accompanied with a low variance were the result. [less ▲]

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See detailMethodological Aspects of Software Engineering, Assurance, Quality, and Reliability Engineering (MAS/AQR) 2019 Welcome from the Minitrack Co-Chairs
Tenbergen, Bastian; Ries, Benoît UL

in Proceedings of the 52nd Hawaii International Conference on System Sciences (HICSS) (2019, January)

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See detailSOCIAL ROLES AND PERSONALITY IN LATER LIFE
Kornadt, Anna Elena UL; Kornadt, Anna Elena UL

in Innovation in Aging (2019), 3(Supplement_1), 729-730

Despite considerable stability of the Big Five personality traits, there is evidence for personality plasticity and change across the lifespan. In younger years, the investment in social roles, such as ... [more ▼]

Despite considerable stability of the Big Five personality traits, there is evidence for personality plasticity and change across the lifespan. In younger years, the investment in social roles, such as entering worklife or starting a family has been shown to drive personality change. With regard to personality in later life, the investigation of social roles has so far been neglected. A questionnaire was developed to assess a large number of social roles that can be assumed in the second half of life. N = 306 participants aged 50 to 86 years reported on their social roles and rated their personality traits. Results show that assuming and investing in certain social roles (e.g. friend, retiree, volunteer) mediated the effects of age on the Big Five, especially for the oldest participants and in the domains openness and extraversion. The findings support the importance of social roles for personality also in later life. [less ▲]

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See detailUsing data from the HBSC study for evidence-based suicide prevention in Luxembourg
van Duin, Claire UL; Heinz, Andreas UL; Catunda, Carolina UL et al

in European Journal of Public Health (2019), 29

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