Last 7 days
Bookmark and Share    
Full Text
Peer Reviewed
See detailDesign model for dry-stacked and demountable masonry blocks
Chewe Ngapeya, Gelen Gael; Waldmann, Daniele UL

in POWERSKIN Conference Proceedings (2021, April 09)

The construction industry around the world produces a large part of inert wastes mainly coming from building demolitions. Facing to this envi-ronmental challenge and considering the new policy initiatives ... [more ▼]

The construction industry around the world produces a large part of inert wastes mainly coming from building demolitions. Facing to this envi-ronmental challenge and considering the new policy initiatives supporting the designing of sustainable buildings, dry-stacked masonry comes forward as a promising solution since components can be dismantled, saved in a component bank and reassembled on new sites. The speedy growth of the construction industry, the increasing importance given to the complete life cycle of buildings and the evolution of construction technics have led to the development of dry-stacked masonry structures. Mortarless masonry structures minimise skilled labour requirements and improve construction productivity. However, despite these advantages, there are no design standards providing guidelines to assess the load-bearing capacity of dry-stacked masonry block, which therefore limits its use in construction. In an attempt to fill this lack, the current paper investigates the load-bearing capacity of dry-stacked masonry and its influencing parameters. The effects of the geometric imperfections such as height imperfections and bed-joint roughness have been analysed as well as a mitigation strategy. Then, based on experimental evidence, a design method has been proposed for dry-stacked masonry solicited by axial compression. The developed design methodology provided promising results, with 93% of accuracy in the prediction of the dry-stacked masonry’s’ load-bearing capacity. [less ▲]

Detailed reference viewed: 50 (1 UL)
Full Text
Peer Reviewed
See detailEco-construction for sustainable development: Concept of a Material and Component Bank
JAYASINGHE, Laddu Bhagya; Waldmann, Daniele UL

in POWERSKIN Conference Proceedings (2021, April 09)

The European Commission has recently promulgated the concept of Circular Economy as a new pathway towards sustainability, in particular through new policy initiatives such as the Circular Economy Action ... [more ▼]

The European Commission has recently promulgated the concept of Circular Economy as a new pathway towards sustainability, in particular through new policy initiatives such as the Circular Economy Action Plan (CEAP). Since the environmental impact of the construction industry with the depletion of natural resources and the raising CO2 emissions will have to be reduced in the future, the need of recycling and even reusing entire building components supporting the principles of circular economy have been identified. The direct reuse of components extracted from old deconstructed buildings presents an energy-efficient and environmental-friendly solution. However, the reuse of components can be hindered by e.g. the lack of information on the availability of decommissioned structural components and uncertainties on the warranty of structural components. To handle this process an additional independent institution acting as Material and Component (M&C) Bank is needed. This entity assures activities such as e.g. the identification of reusable components in buildings which are proposed for selective dismantling; the condition assessment; the data management and the data transfer from a previously deconstructed building to a new building; and finally, an official certification of the components’ conformity for another service life in a new application. In the current paper, a concept for such a M&C bank is presented. This study investigates the potential of a M&C bank in the framework of circular economy concepts for the planning of sustainable and circular buildings with a reduced eco-footprint by focusing on the reuse of decommissioned structural components. The concept, main businesses and work operation of the bank are discussed. Furthermore, a digital representation of the bank as BIM-based M&C bank needed to publicize the availability of the reusable components to the market and to enable circular business models by showing their circular pathways are described. [less ▲]

Detailed reference viewed: 48 (1 UL)
Full Text
See detailDes formations hybrides à défaut de mobilité
Lejot, Eve UL; Molostoff, Leslie UL

Presentation (2021, April 09)

Detailed reference viewed: 25 (0 UL)
Full Text
Peer Reviewed
See detailDesigning EMI lecturer training programmes: what and how
Deroey, Katrien UL

Scientific Conference (2021, April 08)

This workshop will provide insights into designing and delivering English Medium Instruction (EMI) lecturer training. Although universities have been slow to organize EMI lecturer support, an increasing ... [more ▼]

This workshop will provide insights into designing and delivering English Medium Instruction (EMI) lecturer training. Although universities have been slow to organize EMI lecturer support, an increasing awareness of the challenges faced by EMI lecturers and their students now appears to be boosting the demand for EMI lecturer training and support initiatives. Consequently, EAP practitioners can increasingly expect requests to design and deliver such programmes. However, the efficient design and delivery of EMI lecturing training and support is a complex challenge. First, the EMI context is very varied and initiatives should be adapted to the local cultural, educational, linguistic and institutional contexts (Herington, 2020; Martinez & Fernandes, 2020; Tuomainen, 2018). Second, most literature highlights the need for language, pedagogical and intercultural components (e.g. Fortanet Gómez, 2020). Third, we need to be sensitive to lecturers’ attitudes towards EMI and EMI training (Tsui, 2018). Fourth, there are practical considerations such as the timely provision of support (Guarda & Helm, 2017), promoting participation, facilitating learning transfer to lectures, and optimizing the support in view of what are often heterogeneous participant groups in terms of English proficiency, (EMI) lecturing experience and discipline (Ball & Lindsay, 2013). Finally, the design of these programmes typically needs to happen with very limited institutional resources, few (if any) published materials and relatively little published research on lecture discourse and EMI lecturer training. The workshop will start with an overview of published training initiatives with their reported successes and challenges (Deroey, 2021). Next, participants will work in small groups, brainstorming ideas for an EMI support programme based on a brief we have recently received at the multilingual University of Luxembourg Language Centre. Finally, these proposals will be discussed in the whole group and key ideas summarized to consolidate the insights gained. Ball, P., & Lindsay, D. (2013). Language demands and support for English-medium instruction in tertiary education. Learning from a specific context In A. Doiz, D. Lasagabaster, & J. M. Sierra (Eds.), English-medium instruction at universities: Global challenges (pp. 44-61). Bristol: Multilingual Matters. -Deroey, K. L. B. (2021). Lecturer training for English Medium Instruction: what and how? In B. D. Bond, A. & M. Evans (Ed.), Innovation, exploration and transformation. Proceedings of the 2019 BALEAP Conference. Reading: Garnet. -Fortanet Gómez, I. (2020). The dimensions of EMI in the international classroom: training teachers for the future university. In M. Del Mar Sánchez-Pérez (Ed.), Teacher training for English-medium instruction in higher education (pp. 1-20). Hershey: IGI Global. -Guarda, M., & Helm, F. (2017). A survey of lecturers’ needs and feedback on EMI training. In K. Ackerley, M. Guarda, & F. Helm (Eds.), Sharing perspectives on English-medium instruction (pp. 167-194). Bern: Peter Lang. -Herington, R. (2020). Observation as a tool to facilitate the professional development of teaching faculty involved in English as a Medium of Instruction: trainer and trainee perspectives. In M. L. Carrió-Pasto (Ed.), Internationalising Learning in Higher Education (pp. 65-82). Hershey: IGI Global. -Martinez, R., & Fernandes, K. (2020). Development of a teacher training course for English medium instruction for higher education professors in Brazil. In M. Del Mar Sánchez-Pérez (Ed.), Teacher Training for English-Medium Instruction in Higher Education (pp. 125-152). Hershey: IGI Global. -Tuomainen, S. (2018). Supporting non-native university lecturers with English-medium instruction. Journal of Applied Research in Higher Education. 10(3), 230-242. -Tsui, C. (2018). Teacher efficacy: a case study of faculty beliefs in an English-medium instruction teacher training program. Taiwan Journal of TESOL, 15(1), 101-128. [less ▲]

Detailed reference viewed: 36 (0 UL)
Full Text
Peer Reviewed
See detailDesigning and managing an online, personalised research writing course for postgraduates
Deroey, Katrien UL; Skipp, Jennifer

Scientific Conference (2021, April 08)

This paper describes and evaluates an online research article writing course at the University of Luxembourg. Participants were self-referred PhD students from different disciplines. The aim of the ten ... [more ▼]

This paper describes and evaluates an online research article writing course at the University of Luxembourg. Participants were self-referred PhD students from different disciplines. The aim of the ten-week course is to improve insight into the structural, stylistic and rhetorical features of research articles as well as the writing and publication process. It also provides tools for students to develop their own writing. We will situate our course rationale and design within the literature, then compare these to both the reality of managing and delivering the course online as well as participants’ feedback as reflected in 30 surveys. We will focus on the following results: • The practicability of including multiple pedagogical elements in an online course was challenging. We wanted to integrate both independent and collaborative work, production and reflection. However, results of the surveys and our own experience show that the multiplicity of elements was often seen as complex and difficult to manage and multiple submission deadlines problematic. • Students favoured working alone over working together and uptake of writing groups (Aitchison, 2009) was poor. Multi-disciplinary peer groups were, however, positively reviewed (cf. Hyland, 2012). • The flexibility of the online environment was seen as positive, yet many reported problems finding time to write. However, participants did see the benefit in having to write regularly. Tools of reflection did not score highly. • The personalisation of learning input scored highly in the survey, but this was time-consuming to implement. Whilst instructor-student consultations were offered to further personalise feedback, these had a low uptake (8/30). • We wanted to create a course which included guidance on the writing and publication process (Starfield & Paltridge, 2016) as well as increased genre awareness (Swales, 1990) to prepare students for publication. However, tasks on language and structure were rated more useful by more students than this content. • More participants commented on the benefit of working through their language issues in live sessions over learning how to address language issues through the corpus-tools that were integrated into the course (Charles, 2018). Through sharing this information, we hope to generate a discussion with the audience about ways to optimise online writing courses and manage some of the problems associated with online delivery. Aitchison, C. (2009). Writing groups for doctoral education. Studies in Higher Education, 34(8), 905-916. Charles, M. (2018) Corpus-assisted editing for doctoral students: More than just concordancing. Journal of English for Academic Purposes, 36, 15-26. Charles, M. (2018). Using do-it-yourself-corpora in EAP: A tailor-made resource for teachers and students. Teaching English for Specific and Academic Purposes, 6(2), 217-224. Hyland, K. (2012). Disciplinary Identities: Individuality and Community in Academic Discourse. Cambridge: Cambridge University Press. Nesi, H. & Gardener, S. (2012). Genres across the disciplines: Student writing in higher education. Cambridge: Cambridge University Press. Paltridge, B., & Starfield, S. (2016). Getting published in academic journals: Navigating the publication process. Ann Arbor: University of Michigan Press. Swales, J. (1990). Genre analysis: English in academic and research settings. Cambridge: Cambridge University Press. [less ▲]

Detailed reference viewed: 46 (0 UL)
Peer Reviewed
See detailSocial Inequality in Education: Academic Achievement of First-, Second-, and Later-Generation Immigrant Students in Luxembourg
Rivas, Salvador UL; Reichel, Yanica UL; Krämer, Charlotte UL et al

Scientific Conference (2021, April 08)

Students with immigrant backgrounds are often disadvantaged in public educational systems. In Luxembourg, about 50% of primary and secondary school students have an immigrant background, most notably from ... [more ▼]

Students with immigrant backgrounds are often disadvantaged in public educational systems. In Luxembourg, about 50% of primary and secondary school students have an immigrant background, most notably from Italy, the former Yugoslavia and Portugal. Using data from Luxembourg’s national school monitoring program, we investigate and document for the first time, existing and emerging differences in academic achievement among different immigrant generations of students. Our results indicate that student achievement in Math, German and French is differentially affected by immigrant generational status and language spoken at home. In addition, we find secondary effects of student social background. [less ▲]

Detailed reference viewed: 35 (5 UL)
Full Text
Peer Reviewed
See detailDifferent concepts for creating antibacterial yet biocompatible surfaces: adding bactericidal element, grafting therapeutic agent through COOH plasma polymer and their combination
Permyakova, Elizaveta S.; Manakhov, Anton M.; Kiryukhantsev-Korneev, Philipp V. et al

in Applied Surface Science (2021)

Antibacterial coatings have become a rapidly developing field of research, strongly stimulated by the increasing urgency of identifying alternatives to the traditional administration of antibiotics. Such ... [more ▼]

Antibacterial coatings have become a rapidly developing field of research, strongly stimulated by the increasing urgency of identifying alternatives to the traditional administration of antibiotics. Such coatings can be deposited onto implants and other medical devices and prevent the inflammations caused by hospital-acquired infections. Nevertheless, the design of antibacterial yet biocompatible and bioactive surfaces is a challenge that biological community has faced for many years but the “materials of dream” have not yet been developed. In this work, the biocompatible yet antibacterial multi-layered films were prepared by a combination of magnetron sputtering (TiCaPCON film), ion implantation (Ag-doped TiCaPCON film), plasma polymerization (COOH layer), and final immobilization of gentamicin (GM) and heparin (Hepa) molecules. The layer chemistry was thoroughly investigated by means of FTIR and X-ray photoelectron spectroscopies. It was found that the immobilization of therapeutic components occurs throughout the entire thickness of the plasma-deposited COOH layer. The influence of each type of bactericide (Ag+ ions, GM, and Hepa) on antibacterial activity and cell proliferation was analyzed. Our films were cytocompatible and demonstrated superior bactericidal efficiency toward antibiotic-resistant bacterial E. coli K261 strain. Increased toxicity while using the combination of Ag nanoparticles and COOH plasma polymer is discussed. [less ▲]

Detailed reference viewed: 18 (0 UL)
See detailPopulismes et fabrique des droits économiques et sociaux dans le cadre des droits de l'Homme. Le Front national et l'Union démocratique du centre (1992-2013)
Albert, Frédéric UL

Doctoral thesis (2021)

Since the 1990’s, with the development of Europeanisation, globalisation and the installation of the neo-liberal paradigm, we observe in Europe the non-application of economic and social rights, despite ... [more ▼]

Since the 1990’s, with the development of Europeanisation, globalisation and the installation of the neo-liberal paradigm, we observe in Europe the non-application of economic and social rights, despite being aspired by the States of the human rights continent after the Second World War. At the same time, "national-populist" parties are gaining more and more support and are establishing themselves in the political landscape as a "right-wing third way", which would provide the answers that the governing parties do not seem to be able to find, in the context of an actual crisis of the welfare state. The aim of our research is to provide a comparative analysis of the discourses of the "Front National" in France, now Rassemblement National ("RN") and the "Union Démocratique du Centre" in Switzerland ("UDC/SVP") on economic and social rights, in order to confront them with the changes and public policies observed in our societies as a result of the neo-liberal paradigm. Using a cross-cutting analytical grid that identifies the characteristics of socio-economic discourse of a "national-populist" nature, this work is made up of numerous sources from both parties, studied over a period of twenty years : work that constitutes the boundaries between 1992, when the Maastricht Treaty developing the "European market" was signed, and 2013, with the start of negotiations for the signing of the transatlantic treaty opening the "European market" to the "US market". The research work is also based on original interviews with key figures from both parties and the creation of an online questionnaire aimed at elected representatives with responsibilities on a smaller scale (at regional level). Thus, the cross-referencing of our qualitative and quantitative data has enabled us to produce original results and to construct a new category of populist parties called : "national-populist parties opposed to human rights". Among other things, the latter develop in their socio-economic approach a will to defend economic and social rights but only for nationals, rejecting the universality of human rights. At the same time, they propose a hybrid form of capitalism with nuances between the "FN/RN" and the "UDC", combining a dose of protectionism but also a more or less sought-after integration into the "market". Furthermore, it is interesting to compare the discourses of a party outside government (the "RN") that has not yet participated in executive authority at the national level and a party associated with federal authority, the "UDC", both "inside and outside". Ultimately, in both cases, it is sovereignism and anchoring in so-called right-wing policies that seem to dominate the socio-economic DNA of the two populist parties studied. With the help of our research work, we can thus ask ourselves in what way does the "national-populist" discourse point to the failure of states on the human rights continent to implement economic and social rights as they intend ? [less ▲]

Detailed reference viewed: 41 (13 UL)
See detailRegional Development Banks in the World Economy
Howarth, David UL; Clifton, Judith; Diaz Fuentes, Daniel

Book published by Oxford University Press (2021)

Regional development banks (RDB) have become increasingly important in the world economy, but have also been relatively under-researched to date. This timely volume addresses this lack of attention by ... [more ▼]

Regional development banks (RDB) have become increasingly important in the world economy, but have also been relatively under-researched to date. This timely volume addresses this lack of attention by providing a comprehensive, comparative, and empirically informed analysis of their origins, evolution, and contemporary role in the world economy through to the second decade of the twenty-first century. In Regional Development Banks in the World Economy, the editors provide an analytical framework that includes a revised categorisation of RDB by geographic operation and function. Part one offers detailed analyses of the origins, evolution, and contemporary role of the major RDB, including the Inter-American Development Bank, the African Development Bank, the Asian Development Bank, the European Investment Bank, the Central American Bank, the Andean Development Corporation, the European Bank for Reconstruction and Development, and the Asian Infrastructure Investment Bank. Part two offers comparative analyses of key topics on RDB, examining their initial design and their changing business models, their shifting role in promoting policies supported by the United States as hegemon and the private sector. The volume ends with a critical reflection on the role played by RDB to date and a strong defence of the need for these banks in an increasingly complex world economy. [less ▲]

Detailed reference viewed: 92 (6 UL)
Full Text
Peer Reviewed
See detailRegional Development Banks in the World Economy
Howarth, David UL; Clifton, Judith; Diaz Fuentes, Daniel

in Clifton, Judith; Diaz Fuentes, Daniel; Howarth, David (Eds.) Regional Development Banks in the World Economy (2021)

In this introduction, we present the categories and the analytical framework that we apply to examine Regional Development Banks, and specifically a form of rational choice institutionalism—Principal ... [more ▼]

In this introduction, we present the categories and the analytical framework that we apply to examine Regional Development Banks, and specifically a form of rational choice institutionalism—Principal-Agent analysis. We apply the categories and framework to each Regional Development Bank in its specific political economy context, with a view to setting out and analysing the similarities and differences among Regional Development Bank. We demonstrate and explain an important evolution in the main objectives of Regional Development Bank lending activities over three distinct periods: from regional integration and development, to market promotion and development, and then to geographical expansion—and multi-polarity promotion for some Regional Development Banks—and a more strategic interventionism in the market, that includes market shaping activities including industrial policy. We explain this evolution in terms of the agency of the Regional Development Banks in relation to their multiple principal—the shareholder national governments. [less ▲]

Detailed reference viewed: 38 (2 UL)
Full Text
Peer Reviewed
See detailRegional Development Banks and the promotion of Public-Private Partnerships: the EIB as a case study
Howarth, David UL; Liebe, Moritz

in Clifton, Judith; Diaz Fuentes, Daniel; Howarth, David (Eds.) Regional Banks in the World Economy (2021)

Most Regional Development Banks in the world have engaged in the increased promotion and use of Public Private Partnerships (PPPs). To explain this rapid and ubiquitous spread of Public Private ... [more ▼]

Most Regional Development Banks in the world have engaged in the increased promotion and use of Public Private Partnerships (PPPs). To explain this rapid and ubiquitous spread of Public Private Partnership promotion and use, this chapter argues that Regional Development Banks can be seen to have acted as agents engaged in slippage. Most—if not all—of their shareholding national governments and loan recipient countries had limited or no prior experience with and knowledge of PPP financing. This activism on the part of Regional Development Banks can also be seen in both Multilateral Development Bank and National Development Bank promotion of PPPs and reinforces wider claims in the literature. More generally, Gavin and Rodrik (1995) argue that International Financial Institutions (IFIs) bolster their long-acquired skills in technical and information expertise in order to remain relevant—a claim that this chapter explores with regard to PPPs in particular. The promotion of PPPs should also be seen in terms of Regional Development Banks operating as agents to move beyond the correction of market failure towards the creation and/or shaping of markets through a particular financing mechanism and with specific market actors (Mazzucato and Penna 2016: 305). [less ▲]

Detailed reference viewed: 55 (0 UL)
Full Text
Peer Reviewed
See detailA Discrete Element Framework for Modeling the Mechanical Behaviour of Snow PART I: Mechanical Behaviour and Numerical Model
Kabore, Brice Wendlassida UL; Peters, Bernhard UL; Michael, Mark et al

in Granular Matter (2021), 23(2), 42

A framework for investigating the mechanics of snow is proposed based on an advanced micro-scale approach. Varying strain rates, densities and temperatures are taken into account. Natural hazards i.e ... [more ▼]

A framework for investigating the mechanics of snow is proposed based on an advanced micro-scale approach. Varying strain rates, densities and temperatures are taken into account. Natural hazards i.e. snow avalanches are triggered by snow deforming at low rates, while a large group of industrial applications concerning driving safety or winter sport activities require an understanding of snow behaviour under high deformation rates. On the micro-scale, snow is considered to consist of ice grains joined by ice bonds to build a porous structure. Deformation and failure of bonds and the inter-granular collisions of ice grains determine the macroscopic response under mechanical load. Therefore, this study proposes an inter-granular bond and collision model for snow based on the discrete element method (DEM) to describe interaction on a grain-scale. It aims at predicting the mechanical behaviour of ice particles under different strain rates using a unified approach. Thus, the proposed algorithm predicts the displacement of each individual grains due to inter-granular forces and torques that derive from bond deformation and grain collision. For this purpose, the inter-granular characteristics are approximated by an elastic viscous-plastic material law which is based on the temperature-dependent properties of poly-crystalline ice Ih. [less ▲]

Detailed reference viewed: 79 (15 UL)
Full Text
Peer Reviewed
See detailA Discrete Element Framework for Modeling the Mechanical Behaviour of Snow PART II: Model Validation
Peters, Bernhard UL; Kabore, Brice Wendlassida UL; Mark, Michael et al

in Granular Matter (2021), 23(2), 43

A micro-scale modelling approach of snow based on the extension of the classical discrete element method (DEM) has been presented in the first part of this study. This modelling approach is employed to ... [more ▼]

A micro-scale modelling approach of snow based on the extension of the classical discrete element method (DEM) has been presented in the first part of this study. This modelling approach is employed to predict the mechanical response of snow under compression dependent on strain rate, initial density and temperature. Results obtained under a variety of conditions are validated with experimental data for both micro- and macro-scale, in particular the broad range between ductile i.e.~low deformation rates and brittle i.e.~high deformation rates regimes are investigated. For this purpose snow is assumed to be composed of ice grains that are inter-connected by a network of bonds between neighbouring grains. This arrangement represents the micro-scale of which the interaction is described by inter-granular collision and bonding. Hence, the response on a macro-scale is largely determined by inter-granular collisions and deformation and failure of bonds during a loading cycle. Consequently, validation was first carried out on micro-scale deformations at different loading rates and temperatures. Hereafter, macro-scale simulations of confined and unconfined, deformation-controlled compression tests have been predicted and were successfully compared to experimental data reported in literature. [less ▲]

Detailed reference viewed: 55 (11 UL)
Full Text
Peer Reviewed
See detailActor‑critic learning‑based energy optimization for UAV access and backhaul networks
Yuan, Yaxiong UL; Lei, Lei UL; Vu, Thang Xuan UL et al

in EURASIP Journal on Wireless Communications and Networking (2021)

In unmanned aerial vehicle (UAV)-assisted networks, UAV acts as an aerial base station which acquires the requested data via backhaul link and then serves ground users (GUs) through an access network. In ... [more ▼]

In unmanned aerial vehicle (UAV)-assisted networks, UAV acts as an aerial base station which acquires the requested data via backhaul link and then serves ground users (GUs) through an access network. In this paper, we investigate an energy minimization problem with a limited power supply for both backhaul and access links. The difficul- ties for solving such a non-convex and combinatorial problem lie at the high compu- tational complexity/time. In solution development, we consider the approaches from both actor-critic deep reinforcement learning (AC-DRL) and optimization perspectives. First, two offline non-learning algorithms, i.e., an optimal and a heuristic algorithms, based on piecewise linear approximation and relaxation are developed as benchmarks. Second, toward real-time decision-making, we improve the conventional AC-DRL and propose two learning schemes: AC-based user group scheduling and backhaul power allocation (ACGP), and joint AC-based user group scheduling and optimization-based backhaul power allocation (ACGOP). Numerical results show that the computation time of both ACGP and ACGOP is reduced tenfold to hundredfold compared to the offline approaches, and ACGOP is better than ACGP in energy savings. The results also verify the superiority of proposed learning solutions in terms of guaranteeing the feasibility and minimizing the system energy compared to the conventional AC-DRL. [less ▲]

Detailed reference viewed: 31 (3 UL)
Full Text
Peer Reviewed
See detailImprovements to Deep-Learning-based Feasibility Prediction of Switched Ethernet Network Configurations
Mai, Tieu Long UL; Navet, Nicolas UL

in The 29th International Conference on Real-Time Networks and Systems (RTNS2021) (2021, April 07)

Graph neural network (GNN) is an advanced machine learning model, which has been recently applied to encode Ethernet configurations as graphs and predict their feasibility in terms of meeting deadlines ... [more ▼]

Graph neural network (GNN) is an advanced machine learning model, which has been recently applied to encode Ethernet configurations as graphs and predict their feasibility in terms of meeting deadlines constraints. Ensembles of GNN models have proven to be robust to changes in the topology and traffic patterns with respect to the training set. However, the moderate prediction accuracy of the model, 79.3% at the lowest, hinders the application of GNN to real-world problems. This study proposes improvements to the base GNN model in the construction of the training set and the structure of the model itself. We first introduce new training sets that are more diverse in terms of topologies and traffic patterns and focus on configurations that are difficult to predict. We then enhance the GNN model with more powerful activation functions, multiple channels and implement a technique called global pooling. The prediction accuracy of the ensemble GNN model with a combination of the suggested improvements increases significantly, up to 11.9% on the same 13 testing sets. Importantly, these improvements increase only marginally the time it takes to predict unseen configurations, i.e., the speedup factor is still from 50 to 1125 compared to schedulability analysis, which allows a far more extensive exploration of the design space. [less ▲]

Detailed reference viewed: 119 (9 UL)
Full Text
See detailTransition from traditional to hybrid to online courses for pre-service elementary school teachers at the University of Luxembourg: STEAM integrated approach in the project MathEduc @ BScE
Kreis, Yves UL; Haas, Ben

Scientific Conference (2021, April 07)

During the past year, technology has started enabling new forms of teaching and learning in higher education in Luxemburg. Thus, to be able to work more closely with elementary school pre-service teachers ... [more ▼]

During the past year, technology has started enabling new forms of teaching and learning in higher education in Luxemburg. Thus, to be able to work more closely with elementary school pre-service teachers, we shifted our mathematics education course during the past years to flipped classroom approaches and worked with synchronous and asynchronous teaching on- and off-campus modes. Furthermore, due to the restrictions of the COVID-19 pandemic, we decided to shift our teaching to entirely online flipped classroom approaches together with outdoor mathematical trails with STEAM integrated assessments. This final shift to a fully online flipped classroom, with self-paced, student-centred teachings and learnings, showed strong positive effects on pre-service elementary school teachers in mathematics teaching. In this presentation, we will outline results of this transition period and describe results from different studies. [less ▲]

Detailed reference viewed: 67 (5 UL)
Full Text
See detailTaming Android App Crashes
Kong, Pingfan UL

Doctoral thesis (2021)

App crashes constitute an important deterrence for app adoption in the android ecosystem. Yet, Android app developers are challenged by the limitation of test automation tools to ensure that released apps ... [more ▼]

App crashes constitute an important deterrence for app adoption in the android ecosystem. Yet, Android app developers are challenged by the limitation of test automation tools to ensure that released apps are free from crashes. In recent years, researchers have proposed various automation approaches in the literature. Unfortunately, the practical value of these approaches have not yet been confirmed by practitioner adoption. Furthermore, existing approaches target a variety of test needs which are relevant to different sets of problems, without being specific to app crashes. Resolving app crashes implies a chain of actions starting with their reproduction, followed by the associated fault localization, before any repair can be attempted. Each action however, is challenged by the specificity of Android. In particular, some specific mechanisms (e.g., callback methods, multiple entry points, etc.) of Android apps require Android-tailored crash-inducing bug locators. Therefore, to tame Android app crashes, practitioners are in need of automation tools that are adapted to the challenges that they pose. In this respect, a number of building blocks must be designed to deliver a comprehensive toolbox. First, the community lacks well-defined, large-scale datasets of real-world app crashes that are reproducible to enable the inference of valuable insights, and facilitate experimental validations of literature approaches. Second, although bug localization from crash information is relatively mature in the realm of Java, state-of-the-art techniques are generally ineffective for Android apps due to the specificity of the Android system. Third, given the recurrence of crashes and the substantial burden that they incur for practitioners to resolve them, there is a need for methods and techniques to accelerate fixing, for example, towards implementing Automated Program Repair (APR). Finally, the above chain of actions is for curative purposes. Indeed, this "reproduction, localization, and repair" chain aims at correcting bugs in released apps. Preventive approaches, i.e., approaches that help developers to reduce the likelihood of releasing crashing apps, are still absent. In the Android ecosystem, developers are challenged by the lack of detailed documentation about the complex Android framework API they use to develop their apps. For example, developers need support for precisely identifying which exceptions may be triggered by APIs. Such support can further alleviate the challenge related to the fact that the condition under which APIs are triggered are often not documented. In this context, the present dissertation aims to tame Android crashes by contributing to the following four building blocks: Systematic Literature Review on automated app testing approaches: We aim at providing a clear overview of the state-of-the-art works around the topic of Android app testing, in an attempt to highlight the main trends, pinpoint the main methodologies applied and enumerate the challenges faced by the Android testing approaches as well as the directions where the community effort is still needed. To this end, we conduct a Systematic Literature Review (SLR) during which we eventually identified 103 relevant research papers published in leading conferences and journals until 2016. Our thorough examination of the relevant literature has led to several findings and highlighted the challenges that Android testing researchers should strive to address in the future. After that, we further propose a few concrete research directions where testing approaches are needed to solve recurrent issues in app updates, continuous increases of app sizes, as well as the Android ecosystem fragmentation. Locating Android app crash-inducing bugs: We perform an empirical study on 500 framework-specific crashes from an open benchmark. This study reveals that 37 percent of the crash types are related to bugs that are outside the crash stack traces. Moreover, Android programs are a mixture of code and extra-code artifacts such as the Manifest file. The fact that any artifact can lead to failures in the app execution creates the need to position the localization target beyond the code realm. We propose ANCHOR, a two-phase suspicious bug location suggestion tool. ANCHOR specializes in finding crash-inducing bugs outside the stack trace. ANCHOR is lightweight and source code independent since it only requires the crash message and the apk file to locate the fault. Experimental results, collected via cross-validation and in-the-wild dataset evaluation, show that ANCHOR is effective in locating Android framework-specific crashing faults. Mining Android app crash fix templates: We propose a scalable approach, CraftDroid, to mine crash fixes by leveraging a set of 28 thousand carefully reconstructed app lineages from app markets, without the need for the app source code or issue reports. We develop a replicative testing approach that locates fixes among app versions which output different runtime logs with the exact same test inputs. Overall, we have mined 104 relevant crash fixes, further abstracted 17 fine-grained fix templates that are demonstrated to be effective for patching crashed apks. Finally, we release ReCBench, a benchmark consisting of 200 crashed apks and the crash replication scripts, which the community can explore for evaluating generated crash-inducing bug patches. Documenting framework APIs' unchecked exceptions: We propose Afuera, an automated tool that profiles Android framework APIs and provides information on when they can potentially trigger unchecked exceptions. Afuera relies on a static-analysis approach and a dedicated algorithm to examine the entire Android framework. With Afuera, we confirmed that 26739 unique unchecked exception instances may be triggered by invoking 5467 (24%) Android framework APIs. Afuera further analyzes the Android framework to inform about which parameter(s) of an API method can potentially be the cause of the triggering of an unchecked exception. To that end, Afuera relies on fully automated instrumentation and taint analysis techniques. Afuera is run to analyze 50 randomly sampled APIs to demonstrate its effectiveness.Evaluation results suggest that Afuera has perfect true positive rate. However, Afuera is affected by false negatives due to the limitation of state-of-the-art taint analysis techniques. [less ▲]

Detailed reference viewed: 85 (7 UL)
Full Text
See detailRussians in Luxembourg: Drei Leben der Bildhauerin Nina Grach-Jascinsky
Ganschow, Inna UL

Article for general public (2021)

Portrait of the sculptor of the emblematic monument DATZEMISCH in front of the oldest school Luxembourgs, the Athenee – Nina Grach-Jascinsky, born 1903 in Russia.

Detailed reference viewed: 52 (0 UL)
Full Text
See detailThe STEAM skilled child: How children can learn to apply STEAM skills to their living environment
Haas, Ben; Kreis, Yves UL; Lavicza, Zsolt

Scientific Conference (2021, April 01)

Detailed reference viewed: 34 (4 UL)