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See detailPartial shear diagram of slim-floor beams
Zhang, Qingjie UL; Schäfer, Markus UL

in Burgess, Ian (Ed.) Special Issue: Proceedings of Eurosteel 2021: Sheffield - Steel's coming home (2021, September)

Slim-floor beams which have the steel sections fully or partially integrated into the concrete slab lead to a significant reduction of the construction height. Due to its flat lower surface, it provides ... [more ▼]

Slim-floor beams which have the steel sections fully or partially integrated into the concrete slab lead to a significant reduction of the construction height. Due to its flat lower surface, it provides favourable solution for technical installation. According to EN1994-1-1, for composite beams plastic moment resistance is assumed. In the case of slim-floor sections, due to the reduced construction height by the integration of the steel beam in the concrete and its extended bottom flange, a large compression zone height may be expected, thus concrete failure in the compression zone may happen before reaching the plastic moment resistance Mpl,Rd. Here, strain limit resistance becomes decisive. For design with partial shear connection, EN1994-1-1 provides the partial shear diagram based on the plastic bending resistance Mpl,Rd which is not always suitable for slim-floor beams. Based on strain limited method, the more suitable partial shear diagram of different slim-floor beams can be developed. From parametric studies of different types of slimfloor beams, the impacts of critical parameters on the design are highlighted, and the limitations of the current plastic resistance based partial shear diagram are suggested. A simplified calculation method for situation beyond the limitation are also proposed to guarantee an economical design of those beams. [less ▲]

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See detailNon-linear Analysis of Circular Composite Columns
Anwaar, Omer; Schäfer, Markus UL; Zhang, Qingjie UL

in Burgess, Ian (Ed.) Special Issue: Proceedings of Eurosteel 2021: Sheffield - Steel's coming home (2021, September)

Composite columns provide many advantages for the application in multi-story and high-rise buildings. However, EN 1994-1-1 does not provide rules for the design of circular concrete sections with fully ... [more ▼]

Composite columns provide many advantages for the application in multi-story and high-rise buildings. However, EN 1994-1-1 does not provide rules for the design of circular concrete sections with fully encased steel profiles according to the simplified methods. Normally, the simplified method for the design of composite columns is based on a normal force-moment interaction diagram which assumes plastic cross-section resistance. However, the moment resistance is to be reduced by a reduction factor M, considering among other the difference between strain-limited and plastic moment resistance. This reduction factor is developed and calibrated for composite compression members with concrete encased sections, partially encased sections and concrete filled rectangular and circular tubes. Comparison of plastic moment resistance to results based on strain limitation show that the application for circular section with encased steel section but without a steel tube may lead to unsafe results. The paper discusses different approaches for the determination of the N-M Interaction curve and the design on cross-section level. The results obtained from these methods are then compared to each other for different dimensions of cross-sections of circular columns; and for different ratios of reinforcements, various steel grades and for normal and high strength concretes. Furthermore, the investigation focuses on the validation of the reduction factor alfa_M and shows for which section types the values according to Eurocode 4 cannot be applied. [less ▲]

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See detailNumerical investigation for the design of rectangular concrete encased steel composite columns
Ergun, Ozgun UL; Schäfer, Markus UL

in Burgess, Ian (Ed.) Special Issue: Proceedings of Eurosteel 2021: Sheffield - Steel's coming home (2021, September)

Advanced design methods are becoming more important for the structural analysis. However, their results depend strongly on the quality of the numerical model and its underlying assumptions. Current ... [more ▼]

Advanced design methods are becoming more important for the structural analysis. However, their results depend strongly on the quality of the numerical model and its underlying assumptions. Current Eurocode 4 does not provide clear guidance for this analysis type. A literature review on the compression tests conducted on concrete encased steel composite columns is presented. It was found out that there is a lack in the literature when it comes to the testing of slender composite columns as opposed to numerous tests done on stub columns. A selection of existing specimen tests are then simulated using finite element analysis software ABAQUS. Nonlinearity in the model was defined through materials and geometry. The interface modelling between steel and concrete as well as the modelling of load introduction are discussed. The finite element model was intended to be as generic as possible so that it can be taken as a basis for future parameter studies. Moreover, the column resistance check using interaction curves was discussed. Different approaches to form interaction curves namely strain limitation and plastic section capacity were compared. [less ▲]

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See detailBehavior of downstand simply supported steel-concrete composite beam applying friction based demountable shear connection
Fodor, Jovan UL; Schäfer, Markus UL

in Burgess, Ian (Ed.) Special Issue: Proceedings of Eurosteel 2021: Sheffield - Steel's coming home (2021, September)

In order to improve sustainability of composite structures and promote the principles of circular economy in construction industry, novel demountable shear connector based on the frictional behavior was ... [more ▼]

In order to improve sustainability of composite structures and promote the principles of circular economy in construction industry, novel demountable shear connector based on the frictional behavior was developed within the framework of Work package 2 of parent project ECON4SD (Eco Construction for Sustainable Development) at the University of Luxembourg. The demountable composite floor system is composed out of modular concrete one-way solid slabs with equidistantly embedded Halfen HTA-CE rail channels, double symmetric steel I section and demountable connector device assembly based on HV high strength structural bolts for preloading that provides the demountable shear connection. In this paper trilinear behavior model is proposed for the force-slip behavior of aforementioned connector device complying to the results of the push test experimental campaign and the results of FEA simulations. Afterwards, parametric study is performed on the range of simply supported composite beams in propped and unpropped condition under uniformly distributed load applying the aforementioned shear connection validating the predictability of the composite beam bending behavior in accordance with the rules of EN 1994-1-1. [less ▲]

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See detailRobotix-Academy Conference for Industrial Robotics (RACIR) 2021
Müller, Rainer; Plapper, Peter UL; Bruls, Olivier et al

Book published by Shaker (2021)

The Robotix-Academy Conference for Industrial Robotics (RACIR) is held on September 22, 2021 at Trier University of Applied Sciences, Environmental Campus Birkenfeld, Germany as a hybrid conference. The ... [more ▼]

The Robotix-Academy Conference for Industrial Robotics (RACIR) is held on September 22, 2021 at Trier University of Applied Sciences, Environmental Campus Birkenfeld, Germany as a hybrid conference. The topics concerned by RACIR are: robot design, robot kinematics/dynamics/control, system integration, sensor/ actuator networks, distributed and cloud robotics, bio-inspired systems, service robots, robotics in automation, biomedical applications, autonomous vehicles (land, sea and air), robot perception, manipulation with multifinger hands, micro/nano systems, sensor information, robot vision, multimodal interface and human-robot interaction. [less ▲]

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See detailOptimization of cost and capacity of broadband satellite system and resources management using Machine Learning techniques
Ortiz Gomez, Flor de Guadalupe UL

Doctoral thesis (2021)

Very High Throughput Satellite (VHTS) systems have an important role to play as a complement to future 5G terrestrial networks to meet the growing traffic demand. In the near future, VHTS systems are ... [more ▼]

Very High Throughput Satellite (VHTS) systems have an important role to play as a complement to future 5G terrestrial networks to meet the growing traffic demand. In the near future, VHTS systems are expected to reach a transmission capacity of 1 Tbps based on frequency reuse/polarization and multibeam coverage schemes. However, the traffic demand in the service area is not uniform and is also changing throughout the day. This means that with a traditional payload, some beams have insufficient resources and others have wasted resources. One solution to this problem is flexible payloads that allow satellite resources to be modified according to traffic demand. According to operators, the main challenges in Satellite Communications (SatComs) is to achieve new generation VHTS systems capable of satisfying traffic demand and to know how to manage resources in an optimal and autonomous way, thus emerging the problem of Dynamic Resource Management (DRM). With this in mind, this thesis studies the optimization for the design of new generation VHTS systems. The study is divided into two parts, satellites with fixed payload and satellites with flexible payload. For the first part, an optimization method is developed that minimizes the cost per Gbps in orbit and maximizes the capacity per beam, as a function of the number of beams, user G/T and annual availability. As an intermediate step between flexibility and a fixed system, the possibility of having a payload that provides coverage with irregularly sized beams depending on traffic demand is studied. While, for flexible systems, new optimization techniques belonging to Machine Learning are studied to manage resources dynamically and autonomously in the system. The results of this thesis provide new contributions for the design of new generations of VHTS broadband satellites and open a possibility for new research lines [less ▲]

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See detailAnalysis of MaaS membership attributes: an agent-based approach
Cisterna, Carolina UL; Bigi, Federico UL; Tinessa, Fiore et al

in Transportation Research Procedia (2021)

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See detailConvolutional Neural Networks for Flexible Payload Management in VHTS Systems
Ortiz Gomez, Flor de Guadalupe UL; Tarchi, Daniele; Martinez, Ramon et al

in IEEE Systems Journal (2021), 15(3), 4675-4686

Very high throughput satellite (VHTS) systems are expected to have a large increase in traffic demand in the near future. However, this increase will not be uniform throughout the service area due to the ... [more ▼]

Very high throughput satellite (VHTS) systems are expected to have a large increase in traffic demand in the near future. However, this increase will not be uniform throughout the service area due to the nonuniform user distribution, and the changing traffic demand during the day. This problem is addressed using flexible payload architectures, enabling the allocation of the payload resources in a flexible manner to meet traffic demand of each beam, leading to dynamic resource management (DRM) approaches. However, DRM adds significant complexity to the VHTS systems, which is why in this article, we are analyzing the use of convolutional neural networks (CNNs) to manage the resources available in flexible payload architectures for DRM. The VHTS system model is first outlined, for introducing the DRM problem statement and the CNN-based solution. A comparison between different payload architectures is performed in terms of DRM response, and the CNN algorithm performance is compared by three other algorithms, previously suggested in the literature to demonstrate the effectiveness of the suggested approach and to examine all the challenges involved. [less ▲]

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See detailThe Safety of Bilateral Simultaneous Hip and Knee Arthroplasty versus Staged Arthroplasty in a High-Volume Center Comparing Blood Loss, Peri- and Postoperative Complications, and Early Functional Outcome
Ley, Christophe UL; Najfeld, Michael; Kalteis, Thomas et al

in Journal of Clinical Medicine (2021)

Purpose: In recent years, there has been increasing interest in the use of simultaneous hip and knee arthroplasty compared to staged procedures in patients with bilateral pathology. The aim of this study ... [more ▼]

Purpose: In recent years, there has been increasing interest in the use of simultaneous hip and knee arthroplasty compared to staged procedures in patients with bilateral pathology. The aim of this study was to compare simultaneous and staged hip and knee arthroplasty in patients with bilateral pathology by assessing the transfusion rate, postoperative hemoglobin drop, length of stay (LOS), in-hospital complications, 30-day readmissions and early functional outcome. Methods: We conducted a retrospective cohort study that included all patients who were undergoing primary TKA, THA and UKA by a single surgeon in a high-volume arthroplasty center between 2015 and 2020 as simultaneous or staged procedures. Staged bilateral arthroplasties were performed within 12 months and were stratified by the time between procedures. Data were acquired through the electronic files at the Orthopädische Chirurgie München (OCM). For functional outcome, the ability of the patients to walk independently on the ward was compared with the ability to walk a set of stairs alone, which was recorded daily by the attending physiotherapist. Results: In total n = 305 patients were assessed for eligibility and included in this study. One hundred and forty-five patients were allocated to the staged arthroplasty group. This group was subdivided into a hip and a knee group, whereas the knee group was split into TKA and UKA. The second staged procedure was performed within 12 months of the first procedure. One hundred and sixty patients were allocated to the simultaneous arthroplasty group. This group was also subdivided into a hip and knee group, whereas the knee group was split again into a TKA and UKA group. No statistical difference was found between the two groups regarding demographic data. Primary outcome measurements: There was no significant difference in the transfusion rate or complication rate. Secondarily, no statistically significant difference was found between the postoperative hemoglobin drop and the functional outcome, or in the length of stay (LOS) between both groups. Walking the stairs showed a significant difference in the knee group. Conclusions: There were no significant differences observed in the transfusion rate in-hospital complications, or readmission rate between both groups. The early functional outcome showed no significant difference in mobility for all groups. Simultaneous arthroplasty for knee or hip is as safe as a staged procedure, with no higher risk for the patient, in a specialized high-volume center. Level of evidence: Level IV. [less ▲]

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See detailKontext und Praktiken der Circular Economy in Luxemburg
Hild, Paula UL

Doctoral thesis (2021)

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See detailDetection of fluid level in bores for batch size one assembly automation using convolutional neural network
Simeth, Alexej UL; Plaßmann, Jessica; Plapper, Peter UL

in Advances in Production Management Systems. Artificial Intelligence for Sustainable and Resilient Production Systems. (2021, August 31), 632

Increased customization and shortening product life cycles pose a challenge for automation, especially in assembly. In combination with the nature of assembly tasks, which may require high level of ... [more ▼]

Increased customization and shortening product life cycles pose a challenge for automation, especially in assembly. In combination with the nature of assembly tasks, which may require high level of perception, skill, and logical thinking, these tasks are often conducted manually, especially in certain industries (e.g. furniture, power tools) or small and medium-sized enterprises. One of such tasks is the liquid level monitoring in gluing processes. Existing non-manual solutions are based on conventional and less flexible algorithms to detect the current liquid level. In production environments with highly individualized products, a need for more performant models arises. With artificial intelligence (AI) it is possible to deduct decisions from unknown multidimensional correlations in sensor data, which is a key enabler for assembly automation for products with high degree of customization. In this paper, an AI-based model is proposed to automate a gluing process in a final assembly. Images of a gluing process are taken with a camera and a convolutional neural network is used to extract images features. The features are applied to train a support vector machine classifier to identify the liquid level. The developed model is tested and validated with a Monte-Carlo-simulation and used on a demonstrator to automate a gluing process. The developed model classifies images of liquid levels with over 98% accuracy. Similar results are achieved on the demonstrator. [less ▲]

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See detailEffects of the COVID-pandemic:The role of family culture and effects on well-being
Minelli, Anne; Murdock, Elke UL; Albert, Isabelle UL

Scientific Conference (2021, August 27)

During the COVID pandemic governments across the globe put restrictions in place to curb the spread of the virus. During the strict lock-down phase, people were only permitted to leave the house for ... [more ▼]

During the COVID pandemic governments across the globe put restrictions in place to curb the spread of the virus. During the strict lock-down phase, people were only permitted to leave the house for essential reasons, and visiting of family members living in a different household was not allowed. The aim of the present study was to investigate possible effects of these COVID restrictions on well-being according to different family models. Extending Kağitçibasi’s (2007, 2013) postulated family model by Manzi et al.’s (2006) aspects of family cultures (enmeshment, cohesion, autonomy and social support) we first explored, if these family models can be replicated in Luxembourg. We then tested, if lock-down restrictions affected family models differently in terms of well-being. A total of N = 244 (Mage = 35 years, SD = 12.2; 73% female) completed our online questionnaire at the time of the strict lockdown in April-Mai 2020 in Luxembourg. To capture the impact of the pandemic, the questionnaire was divided into two parts. First, participants answered questions about their well-being, family culture and closeness to their parents in general. Participants were then reminded of COVID lockdown restrictions and asked to answer under these restrictions. Using cluster analysis we identified three family models, namely psychologically interdependent families (focus on cohesion and social support), independent families (focus on autonomy), and interdependent families (focus: enmeshment, cohesion and social support). The independent family cluster showed lower well-being before and during the pandemic compared to psychologically interdependent families. Our findings suggest that different family models as postulated by Kağitçibasi are indeed affected differently by the pandemic. Furthermore, there appears to be a particular association between cohesion and well-being. Implications of these findings will be discussed also in the family model framework. [less ▲]

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See detailBeyond the pandemic: Shaping of futures in (even more?) diverse educational settings - Critical discussion of contributions of invited symposium SIG 21
Max, Charles UL

Scientific Conference (2021, August 27)

Looking at SIG 21’s mission statement, the diversity of learning and education (which is / was ?) a granted element in educational research, seems to hail from a post/past century, where not everyone was ... [more ▼]

Looking at SIG 21’s mission statement, the diversity of learning and education (which is / was ?) a granted element in educational research, seems to hail from a post/past century, where not everyone was doing learningonline, remotely via the same tools and devices (i.e. zoom, etc.) Therefore, we wonder ifthe diversity still can be looked at in similar ways, and if so, which other ways of looking at the « new normal » should be developed, both from a practical, empirical research point of view, but also from a theoretical and epistemic perspective, underlying new research (or research into the new normal).Following this first line of thought, which questions could determine future research into education, educational settings and learning as such? This seems of particular interest, as the current ways of looking into education are heavily biased by concerns of technological infrastructure, investment and structural fitness (i.e., teachers as appexperts, networks, online setups, disregarding actual learners). Moreover, other ways of looking into formerly accepted « groups » (i.e., gender, age, background) seem to fall apart and disintegrate, making the issue of heterogeneity even more challenging to grapple with. Finally, when looking at the landscape of educational contexts and their societal anchorage at large (i.e., learning settings, formal/informal settings, mobility, development of professionals …) one aspect seems of particular interest: Is there learning in and from the actual situation ? How sustainable are the developments? Which perspectives can be drawn beyond the short term? [less ▲]

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See detailNew Estimates of Inequality of Opportunity Across European Cohorts (and Some Insights on the Long-term Impact of Educational Policy)
Andreoli, Francesco; Fusco, Alessio; Kyzyma, Iryna et al

Scientific Conference (2021, August 25)

This paper provides a set of new estimates of inequality of opportunity (IOp) in Europe, using the European Union Statistics on Income and Living Condition (EU-SILC). Unlike previous research, we estimate ... [more ▼]

This paper provides a set of new estimates of inequality of opportunity (IOp) in Europe, using the European Union Statistics on Income and Living Condition (EU-SILC). Unlike previous research, we estimate inequality of opportunity within birth cohorts, which we argue is the most appropriate population level for inequality of opportunity analysis. Most IOp measures require estimation of the conditional distribution of the outcome of interest given circumstances. With multiple circumstances and the sample sizes available in EU-SILC, we use distribution regression methods combined with local kernel weighting and show how these can be used to estimate a large set of IOp measures. Endowed with cohort-level estimates of IOp, we finally examine the relationship between educational policy variables measured at the time of parental education and offspring generation inequality of opportunity in adulthood. We find a negative relationship between the duration of compulsory education of the parents and IOp among offspring, but the relationship is not very strong. [less ▲]

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See detailSoftware for the frontiers of quantum chemistry: An overview of developments in the Q-Chem 5 package
Evgeny Epifanovsky; Andrew T. B Gilbert; Xintian Feng et al

in Journal of Chemical Physics (2021)

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See detail„Raum für Mehrsprachigkeit geben!“
Heinzel, Friederike; Schüler, Liz; Kirsch, Claudine UL et al

in Die Grundschulzeitschrift (2021)

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See detailAutour des possessions luxembourgeoises dans le comté de Hainaut sous le règne de Jean, roi de Bohême et comte de Luxembourg (1310-1346)
Pettiau, Hérold UL

Scientific Conference (2021, August 20)

The purpose of this contribution is to open what appeared at first sight to be a small dossier, devoted to the heritage held in the county of Hainaut for several decades at the beginning of the 14th ... [more ▼]

The purpose of this contribution is to open what appeared at first sight to be a small dossier, devoted to the heritage held in the county of Hainaut for several decades at the beginning of the 14th century between 1304 and 1343, and even afterwards, by the counts of the Luxembourg dynasty (Henry VII and his son John the Blind, King of Bohemia), of which I have presented the main items and the interest that their study (and publication) could bring. This file is interesting in more than one way: It is- on the Luxembourg side at least, little known - even if important documents have been published and available for a long time - these 'outlying' possessions have not been much taken into consideration by researchers working on the territorialisation of the principality or on the 'finances' of John of Bohemia. It also concerns a period during which documentary writing developed in the management of the possessions of the principalities of the Low Countries - including, of course, Hainaut (in union with Zealand Holland), which has been very well studied by Valeria Van Camp. In Luxembourg, a first cartulary, currently called liber foeodorum, was drawn up in 1308-1309, and subsequently completed; a second in 1343, and also a censary (or Urbar) noting the revenues of the various components of the possessions of the Luxembourgs by provostship, land, and castellany in the years 1306-1317, subsequently completed in the years 1322-1327. This file raises questions about the practical management of such possessions, which were quite remote, beyond the administrative organisation of the county. [less ▲]

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See detailErgebnisse des Jugendberichtes 2020
Schumacher, Anette UL; S

in Ergebnisse des Jugendberichtes 2020 (2021)

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