Behavior of downstand simply supported steel-concrete composite beam applying friction based demountable shear connection

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 ▲]

Optimization of cost and capacity of broadband satellite system and resources management using Machine Learning techniques

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 ▲]

Analysis of MaaS membership attributes: an agent-based approach

in Transportation Research Procedia (2021)

The 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

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 ▲]

Detection of fluid level in bores for batch size one assembly automation using convolutional neural network

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 ▲]

Beyond the pandemic: Shaping of futures in (even more?) diverse educational settings - Critical discussion of contributions of invited symposium SIG 21

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 ▲]

New Estimates of Inequality of Opportunity Across European Cohorts (and Some Insights on the Long-term Impact of Educational Policy)

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 ▲]

Distribution of kinks in an Ising ferromagnet after annealing and the generalized Kibble-Zurek mechanism

in Physical Review Research (2021)

We consider the annealing dynamics of a one-dimensional Ising ferromagnet induced by a temperature quench in finite time. In the limit of slow cooling, the asymptotic two-point correlator is analytically ... [more ▼]

We consider the annealing dynamics of a one-dimensional Ising ferromagnet induced by a temperature quench in finite time. In the limit of slow cooling, the asymptotic two-point correlator is analytically found under Glauber dynamics, and the distribution of the number of kinks in the final state is shown to be consistent with a Poissonian distribution. The mean kink number, the variance, and the third centered moment take the same value and obey a universal power-law scaling with the quench time in which the temperature is varied. The universal power-law scaling of cumulants is corroborated by numerical simulations based on Glauber dynamics for moderate cooling times away from the asymptotic limit, when the kink-number distribution takes a binomial form. We analyze the relation of these results to physics beyond the Kibble-Zurek mechanism for critical dynamics, using the kink-number distribution to assess adiabaticity and its breakdown.We consider linear, nonlinear, and exponential cooling schedules, among which the last provides the most efficient shortcuts to cooling in a given quench time. The nonthermal behavior of the final state is established by considering the trace norm distance to a canonical Gibbs state. [less ▲]

Autour des possessions luxembourgeoises dans le comté de Hainaut sous le règne de Jean, roi de Bohême et comte de Luxembourg (1310-1346)

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 ▲]

Ergebnisse des Jugendberichtes 2020

in Ergebnisse des Jugendberichtes 2020 (2021)