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See detailDevice simulation of all-perovskite four-terminal tandem solar cells: towards 33% efficiency
Singh, Ajay UL; Gagliardi, Alessio

in EPJ Photovoltaics (2021), 12(4),

Inorganic–organic hybrid perovskites offer wide optical absorption, long charge carrier diffusion length, and high optical-to-electrical conversion, enabling more than 25% efficiency of single-junction ... [more ▼]

Inorganic–organic hybrid perovskites offer wide optical absorption, long charge carrier diffusion length, and high optical-to-electrical conversion, enabling more than 25% efficiency of single-junction perovskite solar cells. All-perovskite four-terminal (4T) tandem solar cells have gained great attention because of solution-processability and potentially high efficiency without a need for current-matching between subcells. To make the best use of a tandem architecture, the subcell bandgaps and thicknesses must be optimized. This study presents a drift-diffusion simulation model to find optimum device parameters for a 4T tandem cell exceeding 33% of efficiency. Optimized subcell bandgaps and thicknesses, contact workfunctions, charge transport layer doping and perovskite surface modification are investigated for all-perovskite 4T tandem solar cells. Also, using real material and device parameters, the impact of bulk and interface traps is investigated. It is observed that, despite high recombination losses, the 4T device can achieve very high efficiencies for a broad range of bandgap combinations. We obtained the best efficiency for top and bottom cell bandgaps close to 1.55 eV and 0.9 eV, respectively. The optimum thickness of the top and bottom cells are found to be about 250 nm and 450 nm, respectively. Furthermore, we investigated that doping in the hole transport layers in both the subcells can significantly improve tandem cell efficiency. The present study will provide the experimentalists an optimum device with optimized bandgaps, thicknesses, contact workfunctions, perovskite surface modification and doping in subcells, enabling high-efficiency all-perovskite 4T tandem solar cells. [less ▲]

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See detailComparing software frameworks of Augmented Reality solutions for manufacturing
Kolla, Sri Sudha Vijay Keshav UL; Sanchez, Andre UL; Plapper, Peter UL

in Procedia Manufacturing (2021, November 03), 55

Augmented reality (AR) is a technology that allows overlaying of virtual elements on top of the physical environment. This enhances the perception and conveys additional information to the user. With the ... [more ▼]

Augmented reality (AR) is a technology that allows overlaying of virtual elements on top of the physical environment. This enhances the perception and conveys additional information to the user. With the emergence of industry 4.0 concepts in manufacturing landscape, AR found its way to improve existing Human-Machine Interfaces (HMI) on the shop-floor. The industrial setting has a wide variety of application opportunities from AR, ranging from training and digital work instructions to quality inspection and remote maintenance. Even though its implementation in the industry is rising in popularity, it is still mainly restricted to large companies due the limited availability of resources in Small and Medium Size Enterprises (SME). However, SMEs can benefit from AR solutions in its production processes. Therefore, this research aims to develop and present the results of comparison of two simple and cost-effective AR software frameworks for Hand Held Device (HHD) and a Head Mounted Device (HMD), which can be applied for developing AR applications for manufacturing. Two AR applications are developed using these software frameworks which are presented in the case study section. Android device is chosen as a HHD and HoloLens is the HMD used in the case study. The development structure can be reproduced by a wider range of enterprises with diverse needs and resource availability. [less ▲]

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See detailWARCnet WG2 activities: a report
Schafer, Valerie UL

Scientific Conference (2021, November 03)

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See detailIntroduction to Digital History
Zaagsma, Gerben UL

Presentation (2021, November 03)

Introduction to digital history for C²DH internal training program, focusing on the history of digital history and the ways in which digitised and digital heritage affects historical research (politics of ... [more ▼]

Introduction to digital history for C²DH internal training program, focusing on the history of digital history and the ways in which digitised and digital heritage affects historical research (politics of digitisation). [less ▲]

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See detailAnalysis of flow induced texturing in complex fluids with Brillouin Rheology - a proof of concept
Lehr, Claudius Moritz UL

Doctoral thesis (2021)

The aim of this work is to study the flow induced texturing of molecules (complex fluids) in a shear field. This is done by measuring phonons with photons [1] in a commercially available rotational ... [more ▼]

The aim of this work is to study the flow induced texturing of molecules (complex fluids) in a shear field. This is done by measuring phonons with photons [1] in a commercially available rotational rheometer. The optical experimental method of transferring momentum and energy between phonons and photons is generally known as Inelastic Light Scattering (ILS) [2]. Brillouin Light Scattering (BLS) [3] has a quite small energy transfer compared to Raman spectroscopy [4] but with a high performance multi-pass Vernier tandem Fabry-Perot interferometer [5] and a sophisticated optical set-up, it is possible to achieve information about the texture (like entanglement of molecules) of complex fluids inside a rheometer gap while shearing. This can be acquired for any position in the sample, in contrast to the rheological experiments were an average over a whole sample is used. Here we successfully demonstrate an optical set-up that couples a BLS with rotational rheology in order to simultaneously measure the high-frequency longitudinal elastic modulus in a classical rheometer along with the zero-shear viscosity during the flow of complex fluids. BLS gives the possibility for contactless determination of local elastic properties, while the designed optical set-up is introduced as boundary conditions to control temperature gradients in the sample, and the position and dimension of the scattering volume. This method was tested for a range of temperatures, and well as for an applied shear field and different radial positions of the scattering volume in the sample using a plate-plate rheometer geometry. Measurements of a dilute polymer system suggest a homogeneous orientation of polymer molecules throughout the sample as soon as a critical shear rate has been reached at one spatial position. [less ▲]

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See detailCANMatch: A Fully Automated Tool for CAN Bus Reverse Engineering based on Frame Matching
Buscemi, Alessio UL; Turcanu, Ion; Castignani, German et al

in IEEE Transactions on Vehicular Technology (2021)

Controller Area Network (CAN) is the most frequently used in-vehicle communication system in the automotive industry today. The communication inside the CAN bus is typically encoded using proprietary ... [more ▼]

Controller Area Network (CAN) is the most frequently used in-vehicle communication system in the automotive industry today. The communication inside the CAN bus is typically encoded using proprietary formats in order to prevent easy access to the information exchanged on the bus. However, it is still possible to decode this information through reverse engineering, performed either manually or via automated tools. Existing automated CAN bus reverse engineering methods are still time-consuming and require some manual effort, i.e., to inject diagnostic messages in order to trigger specific responses. In this paper, we propose CANMatch a fully automated CAN bus reverse engineering framework that does not require any manual effort and significantly decreases the execution time by exploiting the reuse of CAN frames across different vehicle models. We evaluate the proposed solution on a dataset of CAN logs, or traces, related to 479 vehicles from 29 different automotive manufacturers, demonstrating its improved performance with respect to the state of the art. [less ▲]

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See detailAnisotropic Interlayer Force Field for Transition Metal Dichalcogenides: The Case of Molybdenum Disulfide
Wengen, Ouyang; Reut, Sofer; Xiang, Gao et al

in Journal of Chemical Theory and Computation (2021)

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See detailActive matter in infinite dimensions: Fokker–Planck equation and dynamical mean-field theory at low density
Manacorda, Alessandro UL

in Journal of Chemical Physics (2021)

We investigate the behavior of self-propelled particles in infinite space dimensions by comparing two powerful approaches in many-body dynamics: the Fokker-Planck equation and dynamical mean-field theory ... [more ▼]

We investigate the behavior of self-propelled particles in infinite space dimensions by comparing two powerful approaches in many-body dynamics: the Fokker-Planck equation and dynamical mean-field theory. The dynamics of the particles at low densities and infinite persistence time is solved in the steady-state with both methods, thereby proving the consistency of the two approaches in a paradigmatic out-of-equilibrium system. We obtain the analytic expression for the pair distribution function and the effective self-propulsion to first order in the density, confirming the results obtained in a previous paper and extending them to the case of a non-monotonous interaction potential. Furthermore, we obtain the transient behavior of active hard spheres when relaxing from equilibrium to the nonequilibrium steady-state. Our results show how collective dynamics is affected by interactions to first order in the density, and point out future directions for further analytical and numerical solutions of this problem. [less ▲]

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See detailAutomatic Integration of Numerical Formats Examined with Frequency-tagged EEG
Marinova, Mila UL; Georges, Carrie UL; Guillaume, Mathieu et al

in Scientific Reports (2021)

How humans integrate and abstract numerical information across different formats is one of the most debated questions in human cognition. We addressed the neuronal signatures of the numerical integration ... [more ▼]

How humans integrate and abstract numerical information across different formats is one of the most debated questions in human cognition. We addressed the neuronal signatures of the numerical integration using an EEG technique tagged at the frequency of visual stimulation. In an oddball design, participants were stimulated with standard sequences of numbers (<5) depicted in single (digits, dots, number words) or mixed notation (dots – digits, number words – dots, digits – number words), presented at 10Hz. Periodically, a deviant stimulus (>5) was inserted at 1.25 Hz. We observed significant oddball amplitudes for all single notations, showing for the first time using this EEG technique, that the magnitude information is spontaneously and unintentionally abstracted, irrespectively of the numerical format. Significant amplitudes were also observed for digits – number words and number words – dots, but not for digits – dots, suggesting an automatic integration across some numerical formats. These results imply that direct and indirect neuro-cognitive links exist across the different numerical formats. [less ▲]

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See detailTowards a Framework to Evaluate Cooperative Perception for Connected Vehicles
Hawlader, Faisal UL; Frank, Raphaël UL

in Proceedings of the 13th IEEE Vehicular Networking Conference 2021 (2021)

Over the past few years, Connected and Autonomous Vehicles (CAVs) have gained significant research attention. With the recent deployment of 5G networks in many metropolitan areas, new cooperative driving ... [more ▼]

Over the past few years, Connected and Autonomous Vehicles (CAVs) have gained significant research attention. With the recent deployment of 5G networks in many metropolitan areas, new cooperative driving concepts are emerging. One of those is cooperative perception, where vehicles exchange sensory information via a V2X network to maximize their awareness horizon without the need for additional and potentially expensive sensors. The idea is to distribute the processing of the sensor information to find the best trade-off between data transmission and processing time. To experimentally evaluate the performance of cooperative perception schemes is time-consuming and costly due to the expensive hardware it involves. To the best of our knowledge there is to date no open- source simulation framework that allows to transfer realistic sensor data between multiple simulated vehicles via a V2X network. In this work-in-progress paper, we address this issue by proposing an extension of the well-known CARLA open- source simulator for automated driving research. We implement a basic communication channel on top of the existing client-server architecture of CARLA and show how sensor information can be exchanged. Transferring realistic sensor information between multiple vehicles opens up a wide range of experiments to test and evaluate novel approaches to collaborative driving in simulation. [less ▲]

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See detailCorrelates of resilience of older people in times of crisis
Albert, Isabelle UL; Hoffmann, Martine; Murdock, Elke UL et al

in Innovation in Aging (2021, November), 5(S 1), 723

Since the beginning of the Covid-19 pandemic, efforts have been made to shield older adults from exposure to the virus due to an age-related higher risk for severe health outcomes. While a reduction of in ... [more ▼]

Since the beginning of the Covid-19 pandemic, efforts have been made to shield older adults from exposure to the virus due to an age-related higher risk for severe health outcomes. While a reduction of in-person contacts was necessary in particular during the first months of the pandemic, concerns about the immediate and longer-term secondary effects of these measures on subjective well-being were raised. In the present study, we focused on self-reported resilience of older people in a longitudinal design to examine risk and protective factors in dealing with the restrictions. Data from independently living people aged 60+ in Luxembourg were collected via a telephone/online survey after the first lockdown in June (N = 611) and September/October 2020 (N = 523), just before the second pandemic wave made restrictions necessary again. Overall, results showed an increase in life-satisfaction from T1 to T2, although life-satisfaction was still rated slightly lower than before the crisis. Also, about a fifth of participants indicated at T2 difficulties to recover from the crisis. Participants who reported higher resilience to deal with the Covid-19 crisis at T2 showed higher self-efficacy, agreed more strongly with measures taken by the country and felt better informed about the virus. In contrast, participants who reported more difficulties in dealing with the pandemic, indicated reduced social contacts to family and friends at T2, and also felt lonelier. Results will be discussed applying a life-span developmental and systemic perspective on risk and protective factors in dealing with the secondary impacts of the pandemic. [less ▲]

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See detailPoster: Commercial 5G Performance: A V2X Experiment
Frank, Raphaël UL; Hawlader, Faisal UL

in Proceedings of the 13th Vehicular Networking Conference 2021 (2021)

This poster paper presents the results of a 4G/5G measurements campaign conducted in Luxembourg City in August 2021. We test the performance of both network technologies while stationary and on the move ... [more ▼]

This poster paper presents the results of a 4G/5G measurements campaign conducted in Luxembourg City in August 2021. We test the performance of both network technologies while stationary and on the move. We report the results for download and upload throughputs, as well as the Round-trip Time (RTT). We briefly discuss the results in the context of Vehicle-to-Everything (V2X) applications. [less ▲]

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See detail“I Felt so Old This Morning.” Short-Term Variations in Subjective Age and the Role of Trait Subjective Age: Evidence from the ILSE/EMIL Ecological Momentary Assessment Data
Kornadt, Anna Elena UL; Weiss, David; Gerstorf, Denis et al

in Psychology and Aging (2021), 36(3), 373-382

Subjective age, how old people feel compared to their chronological age, is a central indicator of age identity and highly predictive for developmental outcomes. While mostly used as a trait-like concept ... [more ▼]

Subjective age, how old people feel compared to their chronological age, is a central indicator of age identity and highly predictive for developmental outcomes. While mostly used as a trait-like concept in previous research, recent studies employing experimental designs and daily assessments suggest that subjective age can vary after experimental manipulations or between days. However, less is known about whether subjective age varies over even shorter time frames such as within moments on a given day, how such short-term variability differs by age and its association with trait subjective age. We examined these questions with data obtained from 123 young–old (Mage = 67.19 years) and 47 old–old adults (Mage = 86.59 years) who reported their momentary subjective age six times a day over 7 consecutive days as they were going about their everyday lives. Participants felt younger on a large majority of occasions, and 25% of the total variability in subjective age could be attributed to within-person variation. Within-person variability in subjective age amounted to an average of about 3 years from one moment to the next and did not differ between age groups. However, those with younger trait subjective ages exhibited larger moment-to-moment variation. Our findings extend the literature on subjective age by showing that how old people feel can vary on a momentary basis and that state and trait components of subjective age are related. Further research should investigate the contextual predictors of variability in subjective age and the links between trait and state concepts and developmental outcomes. [less ▲]

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See detailLongitudinal Relations Between Views on Aging and Perceived Stress: Evidence for Mutual Associations
Wahl, Hans-Werner; Kornadt, Anna Elena UL; Wettstein, Markus

in Innovation in Aging (2021, November), 5(Supplement_1), 287-287

We investigated the reciprocal longitudinal relation between perceived stress and three established domains of views on aging (VoA): (1) subjective age; (2) attitude toward own aging [ATOA]; and (3) aging ... [more ▼]

We investigated the reciprocal longitudinal relation between perceived stress and three established domains of views on aging (VoA): (1) subjective age; (2) attitude toward own aging [ATOA]; and (3) aging-related cognitions including social loss, physical decline, and continuous growth. We also examined the potentially moderating role of chronological age. Data of the German Ageing Survey, comprising two measurement occasions (2014 and 2017) and a sample of 4,588 individuals aged between 40 and 95 years, were analyzed. Controlling for socio-demographic and health-related indicators, cross-lagged models indicated mutual longitudinal relations between VoA and stress. Whether the pathway from stress to VoA or the opposite pathway was stronger varied depending on the VoA considered. With increasing age, most VoA domains were less strongly associated with subsequent perceived stress. Our findings suggest that less favorable VoA predict higher perceived subsequent stress, but they are also preceded and predicted by higher levels of perceived stress. [less ▲]

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See detailSDN for Gateway Diversity Implementation in Satellite Networks
Minardi, Mario UL; Politis, Christos; Zimmer, Frank et al

in International Symposium on Networks, Computers and Communications (ISNCC), Dubai 31 Oct.-2 Nov. 2021 (2021, November)

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See detailDownlink Transmit Design in Massive MIMO LEO Satellite Communications
Li, Ke-Xin; You, Li; Want, Jiaheng et al

in IEEE Transactions on Communications (2021)

Low earth orbit (LEO) satellite communication systems have attracted extensive attention due to their smaller pathloss, shorter round-trip delay and lower launch cost compared with geostationary ... [more ▼]

Low earth orbit (LEO) satellite communication systems have attracted extensive attention due to their smaller pathloss, shorter round-trip delay and lower launch cost compared with geostationary counterparts. In this paper, the downlink transmit design for massive multiple-input multiple-output (MIMO) LEO satellite communications is investigated. First, we establish the massive MIMO LEO satellite channel model where the satellite and user terminals (UTs) are both equipped with the uniform planar arrays. Then, the rank of transmit covariance matrix of each UT is shown to be no larger than one to maximize ergodic sum rate, which reveals the optimality of single-stream precoding for each UT. The minorization-maximization algorithm is used to compute the precoding vectors. To reduce the computation complexity, an upper bound of ergodic sum rate is resorted to produce a simplified transmit design, where the rank of optimal transmit covariance matrix of each UT is also shown to not exceed one. To tackle the simplified precoder design, we derive the structure of precoding vectors, and formulate a Lagrange multiplier optimization (LMO) problem building on the structure. Then, a low-complexity algorithm is devised to solve the LMO, which takes much less computation effort. Simulation results verify the performance of proposed approaches. [less ▲]

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See detailThe Right to an Effective Remedy under the First Paragraph of Article 47 of the Charter
Hofmann, Herwig UL

in Peers, Steve; Harvey, Tamara; Kenner, Jeff (Eds.) et al The EU Charter of Fundamental Rights - A Commentary (2021)

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See detailCohesion and Disability in Adolescents – a Theoretical Approach
Stöcker, Anne UL

Presentation (2021, November)

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