Hybrid Active-and-Passive Relaying Model for 6G-IoT Greencom Networks with SWIPT

in Sensors (2021), 21

In order to support a massive number of resource-constrained Internet-of-Things (IoT) devices and machine-type devices, it is crucial to design a future beyond 5G/6G wireless networks in an energy ... [more ▼]

In order to support a massive number of resource-constrained Internet-of-Things (IoT) devices and machine-type devices, it is crucial to design a future beyond 5G/6G wireless networks in an energy-efficient manner while incorporating suitable network coverage expansion methodologies. To this end, this paper proposes a novel two-hop hybrid active-and-passive relaying scheme to facilitate simultaneous wireless information and power transfer (SWIPT) considering both time-switching (TS) and power-splitting (PS) receiver architectures, while dynamically modelling the involved dual-hop time-period (TP) metric. An optimization problem is formulated to jointly optimize the throughput, harvested energy, and transmit power of a SWIPT-enabled system with the proposed hybrid scheme. In this regard, we provide two distinct ways to obtain suitable solutions based on the Lagrange dual technique and Dinkelbach method assisted convex programming, respectively, where both the approaches yield an appreciable solution within polynomial computational time. The experimental results are obtained by directly solving the primal problem using a non-linear optimizer. Our numerical results in terms of weighted utility function show the superior performance of the proposed hybrid scheme over passive repeater-only and active relay-only schemes, while also depicting their individual performance benefits over the corresponding benchmark SWIPT systems with the fixed-TP. [less ▲]

Dynamic Pricing Strategies in the Carsharing Business, Profit Maximization and Equity Considerations

Doctoral thesis (2021)

In the last two decades the development of mobile technology and the ease of access to an internet connection helped the consolidation of the sharing economy paradigm. This new way of purchasing goods and ... [more ▼]

In the last two decades the development of mobile technology and the ease of access to an internet connection helped the consolidation of the sharing economy paradigm. This new way of purchasing goods and services differs from old traditional business models since it enables a shared use of resources in order to save money and generate profit. As an important player in the sharing economy, sharing mobility continues, nowadays, to shape urban mobility with the introduction of different modes of shared transport such as carsharing, bike sharing, ride sourcing, and other collective mobility services. Different stakeholders participate in the creation and exploitation of these new mobility services: governmental agencies, customers, and private companies. Each of them has a specific purpose that can affect and stir the benefit of sharing platforms. Focusing on the carsharing service, on the business side and on the user side, profit and customer satisfaction are usually the main goals even if, at times, both difficult to pursue together. Competition on today's landscape leaves little room for both established and less established businesses. Opportunities to increase corporate profit become scarcer and more refined systems to better manage carsharing operations are needed to guarantee commercial viability. Evaluating business models for carsharing is no trivial task. Several methods are used for assessing the quality of changes in some operations or to evaluate possible approaches. Combinatorial and stochastic optimization are used to answer decision-making problems in the case of deterministic or uncertain problems. The shortcoming of these approaches is that they are limited at solving problems related to fleet management or service planning as it is more difficult to have an overview in which multiple properties (e.g., demography, territorial distribution, specificity of the fleet, ...) of both supply and demand are considered. This happens because car sharing is a highly complex service that has many interdependent factors. Given this complexity, a more favorable approach to estimate the demand for the service - together with all its peculiarities - and to help operators in the decision-making process, is the simulation one. This criterion allows the interaction of multiple factors which, through functional relationships between the decision-making parameters of the supplier, can introduce indicators to evaluate the quality of the solutions that cannot be easily derived analytically. This dissertation focuses on a simulation-based approach that aims to create a decision support system for carsharing business. This decision support system aims to use demographic and land use data as input, once the provider's needs are known, and to return solutions regarding the optimization of the carsharing service. The development of this thesis is conceived from the point of view of the service provider, even if considerations regarding the equity of the various strategies proposed therein for the service customers constitute an integral and fundamental part of the construction of this system of support for decisions. In this manuscript, we discuss the introduction of different dynamic pricing strategies that aim to increase the profit of the carsharing service, along with other indicators such as the number of bookings and utilization time of vehicles. By developing different price models, the introduction of dynamic prices based on the quantity of vehicles present in the station at the time of booking is evaluated and the output of the implementation of a dynamic price based on the time of the day is examined. In the first part of this thesis, we discuss how it is possible to evaluate the quality of a carsharing service from the point of view of its members, focusing on how different strategies generate or can reduce inequalities due to different wages or purchasing powers. Furthermore, using data collected by a car-sharing company operating in Germany and the United Kingdom, Oply, we implement these same strategies in a scenario calibrated with real data. Finally, we propose a methodology for calibrating carsharing scenarios in an agent-based environment.Moreover, we use these scenarios to demonstrate how it is possible, once there is complete knowledge of the demand and the status of the offer, to attribute a certain price to a single booking that maximizes the profit of the service. The overall results show that the introduction of dynamic pricing strategies does not always benefit all segments of the population and that the goals of a carsharing company are not always compatible with those of its members. Furthermore, they show how it is possible to increase the profit of a carsharing company accordingly to its position on the market, whether it has a total knowledge of the territory or not, whether it is an established company or not yet fully established. As we will also see in the final chapter of this thesis, the product of this work does not consist only in a practical contribution aimed mostly at carsharing companies, but also in a scientific counterpart that outlines new research directions. [less ▲]

Keynote: Transnational Families and Childhood throughout the 20th Century

Presentation (2021, September 03)

Inventing the cross-border region. New and old border practices in cross-border cooperation and cartography

Presentation (2021, September 01)

Avant-propos

in Frisoni, Claude; Reuter, Raymond (Eds.) Les rouges et le noir (2021)

Denis Scuto has written a foreword for the catalogue of the exhibition realised by writer Claude Frisoni and photographer Raymond Reuter on the history of the antifascist Italian mining workers in the ... [more ▼]

Denis Scuto has written a foreword for the catalogue of the exhibition realised by writer Claude Frisoni and photographer Raymond Reuter on the history of the antifascist Italian mining workers in the ARBED mine Montrouge overlapping the French-Luxembourgish frontier and their persecution during Nazi occupation, also presenting the testimonies of some of their children and grand-children: Norbert and Roland Rutili, sons of Vittorio Rutili, arrested by Gestapo on February 3 1944, killed in concentration camp of Schorzinger (Struthof), Raymond Peruzzi, son of Luigi Peruzzi, arrested by Gestapo on September 9 1942, deported to SS-camp Hinzert (near Trier) and forced labourer for Siemens in Berlin, Aurélie Filippetti, grand-daughter of Tommaso Filippetti, arrested by Gestapo on February 3 1944 and who died in concentration camp of Bergen-Belsen on April 12 1945, Jean-Pierre Barboni, grand-son of Domenico Bordicchia, arrested on October 23 1942 and deported to Hinzert and Ventotene. [less ▲]

Stability of Value-Added Models: Comparing Classical and Machine Learning Approaches

Scientific Conference (2021, September)

Background: What is the value that teachers or schools add to the evolution of students’ performance? Value-added (VA) modeling aims to answer this question by quantifying the effect of pedagogical ... [more ▼]

Background: What is the value that teachers or schools add to the evolution of students’ performance? Value-added (VA) modeling aims to answer this question by quantifying the effect of pedagogical actions on students’ achievement, independent of students’ backgrounds (e.g., Braun, 2005). A plethora of VA models exist, and several outcome measures are in use to estimate VA scores, yet without consensus on the model specification (Everson, 2017; Levy et al., 2019). Furthermore, it is unclear whether the most frequently used VA models (i.e., multi-level, linear regression, and random forest models) and outcome measures (i.e., language and mathematics achievement) indicate a similar stability of VA scores over time. Objectives: Drawing from the data of a highly diverse and multilingual school setting, where leveling out the influence of students’ backgrounds is of special interest, we aim to (a) clarify the stability of school VA scores over time; (b) shed light on the sensitivity toward different statistical models and outcome variables; and (c) evaluate the practical implications of (in)stable VA scores for individual schools. Method: Utilizing the representative, longitudinal data from the Luxembourg School Monitoring Programme (LUCET, 2021), we examined the stability of school VA scores. We drew on two longitudinal data sets of students who participated in the standardized achievement tests in Grade 1 in 2014 or 2016 and then again in Grade 3 two years later (i.e., 2016 and 2018, respectively), with a total of 5875 students in 146 schools. School VA scores were calculated using classical approaches (i.e., linear regression and multilevel models) and one of the most commonly used machine learning approaches in educational research (i.e., random forests). Results and Discussion: The overall stability over time across the VA models was moderate, with multilevel models showing greater stability than linear regression models and random forests. Stability differed across outcome measures and was higher for VA models with language achievement as an outcome variable as compared to those with mathematics achievement. Practical implications for schools and teachers will be discussed. [less ▲]

Adaptive Practice Quizzing in a University Lecture: A Pre-Registered Field Experiment

in Journal of Applied Research in Memory and Cognition (2021)

Providing quiz questions has emerged as a powerful means to support learning. However, it is still unclear whether adaptive practice quizzing will enhance beneficial effects in authentic contexts. To ... [more ▼]

Providing quiz questions has emerged as a powerful means to support learning. However, it is still unclear whether adaptive practice quizzing will enhance beneficial effects in authentic contexts. To address this question, university students (N = 188; n = 155 female) were randomly assigned to employ either adaptive practice quizzing, nonadaptive practice quizzing, or note-taking following three consecutive sessions of a standard psychology university lecture for undergraduate pre-service teachers. In the adaptive practice quizzing condition, quiz questions were adapted to learners’ expertise via cognitive demand ratings, whereas in the non-adaptive condition quiz questions followed a fixed sequence. Students in the adaptive practice quizzing condition outperformed those in the nonadaptive condition after a two-week delay, but not after a one-week delay. Exploratory mediation analyses show that performance on the quiz questions during the learning phase seems to be partly responsible for this effect. [less ▲]

Meta-Analytic Structural Equation Models of Executive Functions and Math Intelligence in Preschool Children

Scientific Conference (2021, September)

BACKGROUND: Response inhibition, attention shifting, and working memory updating are the three core executive functions (EFs; Miyake et al., 2000) underlying other cognitive skills that are relevant for ... [more ▼]

BACKGROUND: Response inhibition, attention shifting, and working memory updating are the three core executive functions (EFs; Miyake et al., 2000) underlying other cognitive skills that are relevant for learning and everyday life. For example, they have shown to be differentially related to the mathematical component of intelligence (i.e., math intelligence) in school students and adults. While researchers suppose these three EFs to become more differentiated from early childhood to adulthood, neither the link of these constructs nor their structure has been conclusively established in preschool children yet. Primary studies on path models connecting EFs and math intelligence diverge in the exact relation of EFs and math intelligence. It remains unclear whether inhibition, shifting, and updating exhibit distinct but correlated constructs with respect to their relation to math intelligence. OBJECTIVES: With our meta-analysis, we aimed to (a) synthesize the relation between the three EFs and math intelligence in preschool children; and (b) compare plausible models of the effects of EFs on math intelligence. METHODS/RESULTS: Synthesizing data from 47 studies (363 effect sizes, 30,481 participants) from the last two decades via novel multilevel and multivariate meta-analytic models (Pustejovsky & Tipton, 2020), we found the three core EFs to be significantly related to math intelligence: Inhibition ("r" ̅ = .30, 95 % CI [.25, .35]), shifting ("r" ̅ = .32, 95 % CI [.25, .38]), and updating ("r" ̅ = .36, 95 % CI [.31, .40]). Looking at the three core EFs as one construct, the correlation was "r" ̅ = .34, 95 % CI [.31, .37]. Utilizing correlation-based, meta-analytic structural equation modeling (Jak & Cheung, 2020), our results exhibited significant relations of all EFs to math intelligence. These relations did not differ between the three core EFs. DISCUSSION: Our findings corroborate the positive link between EFs and math intelligence in preschool children and are similar to other age groups. From the model testing, we learned that representing EFs by a latent variable, thus capturing the covariance among the three core EFs, explained substantially more variation in math intelligence than representing them as distinct constructs. [less ▲]

Ingeborg Bachmanns Simultan und die Frage der Rechtsbindung in Zeiten von Multilingualität und Transkulturalität

in Walter, Tonio; Schramm, Edward (Eds.) Dichtung und Wahrheit - und Recht (2021)

Luxemburger Geschichte revisited. Überlegungen zu meta- und transnationaler Geschichtsschreibung

in Hemecht: Zeitschrift für Luxemburger Geschichte (2021), 73(3), 261-264