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See detailRadio Frequency Interference Detection Using Nonnegative Matrix Factorization
Silva, Felipe B.; Cetin, Ediz; Alves Martins, Wallace UL

in IEEE Transactions on Aerospace and Electronic Systems (2021)

This work proposes a new pre-correlation interference detection technique based on nonnegative matrix factorization (NMF) for global navigation satellite system (GNSS) signals. The proposed technique uses ... [more ▼]

This work proposes a new pre-correlation interference detection technique based on nonnegative matrix factorization (NMF) for global navigation satellite system (GNSS) signals. The proposed technique uses NMF to extract the time and frequency properties of the received signal from its spectrogram. The estimated spectral shape is then compared with the spectrogram’s time slices by means of a similarity function to detect the presence of radio frequency interference (RFI). In the presence of RFI, the NMF estimated spectral shape tends to be well-defined, resulting in high similarity levels. In contrast, in the absence of RFI, the received signal is solely comprised of noise and GNSS signals resulting in a noise like spectral shape estimate, leading to considerably reduced similarity levels. The proposal exploits this different similarity levels to detect the presence of interference. Simulation results indicate that the proposed technique yields increased detection capability with low false alarm rate even in low jammer-to-noise ratio environments for both narrow and wideband interference sources without requiring fine-tuning of parameters for specific RFI types. In addition, the proposal has reduced computational complexity, when compared with an existing statistical-based detector. [less ▲]

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See detailOn performance characterization of cascaded multiwire-PLC/MIMO-RF communication system
Ai, Yun; Kong, Long; Cheffena, Michael et al

in 2021 29th European Signal Processing Conference (EUSIPCO) (2021)

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See detailAutomation, Growth, and Factor Shares in the Era of Population Aging
Irmen, Andreas UL

Presentation (2021)

How does population aging affect economic growth and factor shares in times of increasingly automatable production processes? The present paper addresses this question in a new macroeconomic model of ... [more ▼]

How does population aging affect economic growth and factor shares in times of increasingly automatable production processes? The present paper addresses this question in a new macroeconomic model of automation where competitive firms perform tasks to produce output. Tasks require labor and machines as inputs. New machines embody superior technological knowledge and substitute for labor in the performance of tasks. Automation is labor-augmenting in the reduced-form aggregate production function. If wages increase then the incentive to automate becomes stronger. Moreover, the labor share declines even though the aggregate production function is Cobb–Douglas. Population aging due to a higher longevity reduces automation in the short and promotes it in the long run. It boosts the growth rate of absolute and per-capita GDP in the short and the long run, lifts the labor share in the short and reduces it in the long run. Population aging due to a decline in fertility increases automation, reduces the growth rate of GDP, and lowers the labor share in the short and the long run. In the short run, it may or may not increase the growth rate of per-capita GDP, in the long run it unequivocally accelerates per-capita GDP growth. [less ▲]

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See detailZitat
Busch, Christopher; Dembeck, Till UL

in Jaeger, Friedrich (Ed.) Enzyklopädie der Neuzeit Online (2021)

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See detailDemand-Aware Beam Design and User Scheduling for Precoded Multibeam GEO Satellite Systems
Jubba Honnaiah, Puneeth UL; Lagunas, Eva UL; Maturo, Nicola et al

in 25th International ITG Workshop on Smart Antennas (WSA 2021) (2021)

For many years, satellite footprints have been fixed from the design phase until the last day of the satellite operational life. Flexibility in coverage by means of reconfigurable beams is becoming ... [more ▼]

For many years, satellite footprints have been fixed from the design phase until the last day of the satellite operational life. Flexibility in coverage by means of reconfigurable beams is becoming increasingly popular thanks to the recent developments in active antenna systems. On the other hand, spatial frequency reuse combined with precoding has been shown to boost the spectral efficiency while lowering the cost per bit. In this context, and motivated by the unbalanced demand requests of the satellite users, we propose a shift from the traditional system-throughput maximization design towards a demand-Aware design, where a new beam shaping technique and user scheduling are combined to satisfy the users’ demands. Supporting numerical results are provided that validate the effectiveness of the proposed beam planning and scheduling and quantify the benefits over conventional rigid techniques. [less ▲]

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See detailClustering-based Adaptive Beam Footprint Design for 5G Urban Macro-Cell
Jubba Honnaiah, Puneeth UL; Lagunas, Eva UL; Maturo, Nicola et al

in 2021 IEEE 4th 5G World Forum (5GWF) - Track 1: 5G Technologies (2021)

In a dense 5G urban-eMBB environment, the user density and traffic loads follow a spatiotemporal variability. To meet high traffic demands, the 5G base stations exploit spatial multiplexing by means of ... [more ▼]

In a dense 5G urban-eMBB environment, the user density and traffic loads follow a spatiotemporal variability. To meet high traffic demands, the 5G base stations exploit spatial multiplexing by means of Active Antenna Systems (AAS) and beamforming. However, pedestrian and vehicular users are highly mobile, rendering non-dynamic beamforming designs totally inefficient in terms of meeting the users’ demand requests. In particular, the latter results in either overload or underutilized beams in a cell. Hence, a practical approach to meet such spatio-temporal heterogeneous demand is to consider dynamic and adaptive beam footprint design that takes into account both the actual users’ position as well as the traffic loads. In this paper, we first study and evaluate the state-of-the-art fixed cell beamforming (based on ITU-R M.2412-0) in a test environment and highlight its drawbacks. Next, we propose a adaptive macro-cell beam footprint design where the beams are dynamically shaped based on the spatial users distribution and their demand requests. Numerical simulations demonstrate the high system performance achieved by the proposed methodology. [less ▲]

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See detailCentral limit theorem for a birth-growth model with Poisson arrivals and random growth speed.
Bhattacharjee, Chinmoy UL; Molchanov, Ilya; Turin, Riccardo

E-print/Working paper (2021)

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See detailFace au “Heraus!” Regards allemands sur la Belgique (1918-1920)
Brüll, Christoph UL

in Dumoulin, Michel; Lanneau, Catherine (Eds.) La Belgique et les traités de paix. De Versailles à Sèvres (1919-1920) (2021)

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See detailLimit theorems for additive functionals of the fractional Brownian motion
Jaramillo, Arturo; Nourdin, Ivan UL; Nualart, David et al

E-print/Working paper (2021)

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See detailSpätlese. Aufsätze aus den ersten beiden Jahrzehnten des 21. Jahrhunderts. Festgabe für Franz Irsigler zum 80. Geburtstag
Uhrmacher, Martin UL; Pauly, Michel UL; Embach, Michael et al

Book published by Verlag für Geschichte und Kultur (2021)

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See detailLes relations belgo-luxembourgeoises depuis 1919. Perspectives historiques et historiographiques
Brüll, Christoph UL

in Clément, Franz (Ed.) Belgique - Luxembourg : 100 ans de collaboration (2021)

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See detailTHE EU SUSTAINABLE FINANCE FRAMEWORK IN LIGHT OF INTERNATIONAL STANDARDS
Bodellini, Marco UL

E-print/Working paper (2021)

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See detailDifferentiation of primary CNS lymphoma and glioblastoma using Raman spectroscopy and machine learning algorithms
Klamminger, Gilbert Georg; Klein, Karoline; Mombaerts, Laurent UL et al

in Free Neuropathology (2021), 2

Objective and Methods: Timely discrimination between primary CNS lymphoma (PCNSL) and glioblastoma is crucial for diagnostics and therapy, but most importantly also determines the intraoperative surgical ... [more ▼]

Objective and Methods: Timely discrimination between primary CNS lymphoma (PCNSL) and glioblastoma is crucial for diagnostics and therapy, but most importantly also determines the intraoperative surgical course. Advanced radiological methods allow this to a certain extent but ultimately, biopsy is still necessary for final diagnosis. As an upcoming method that enables tissue analysis by tracking changes in the vibrational state of molecules via inelastic scattered photons, we used Raman Spectroscopy (RS) as a label free method to examine specimens of both tumor entities intraoperatively, as well as postoperatively in formalin fixed paraffin embedded (FFPE) samples. Results: We applied and compared statistical performance of linear and nonlinear machine learning algorithms (Logistic Regression, Random Forest and XGBoost), and found that Random Forest classification distinguished the two tumor entities with a balanced accuracy of 82,4% in intraoperative tissue condition and with 94% using measurements of distinct tumor areas on FFPE tissue. Taking a deeper insight into the spectral properties of the tumor entities, we describe different tumor-specific Raman shifts of interest for classification. Conclusions: Due to our findings, we propose RS as an additional tool for fast and non-destructive, perioperative tumor tissue discrimination, which may augment treatment options at an early stage. RS may further serve as a useful additional tool for neuropathological diagnostics with little requirements for tissue integrity. [less ▲]

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See detailProgress at Snail’s Pace? Regional Involvement and Treaty Changes since 1990
Högenauer, Anna-Lena UL

in Abels, Gabriele (Ed.) From Takers to Shapers? Challenges for Regions in a Dynamic EU Polity (2021)

From the mid-1980s, the sub-state level has become increasingly recognized as a political actor in European Union (EU) politics. Starting with the Treaty of Maastricht, a series of EU Treaty changes have ... [more ▼]

From the mid-1980s, the sub-state level has become increasingly recognized as a political actor in European Union (EU) politics. Starting with the Treaty of Maastricht, a series of EU Treaty changes have recognized the democratic role of regions and local authorities and have created consultative mechanisms for them. However, the very regions that pushed for these changes – namely the strong legislative regions like the German Länder and the Belgian regions – became dissatisfied with the innovations of the Treaty of Maastricht almost as soon as they were implemented. As a result, their strategy focused increasingly on limiting transfers of competences to the European level in areas of importance to regions. The aim of this contribution is therefore to examine the evolution of the demands of strong legislative regions and their rights on the European level. It argues that the diversity of European regions has made it difficult to reconcile European integration with the status and functioning of strong legislative regions. [less ▲]

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See detailCrowdsourced COVID-19 Collections: A brief overview
Zumthurm, Tizian UL

in International Public History (2021)

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See detailREFERENCE MEASUREMENTS AND SIMULATIONS OF STATIC AND DYNAMIC CHARACTERISTICS OF PRESTRESSED CONCRETE BRIDGES UNDER OUTDOOR CONDITIONS FOR STRUCTURAL HEALTH MONITORING
Kebig, Tanja UL

Doctoral thesis (2021)

Today’s traffic infrastructure, including its engineering structures such as bridges, is stressed not only by natural ageing and corrosion but also by fatigue. The fatigue of material is accelerated by ... [more ▼]

Today’s traffic infrastructure, including its engineering structures such as bridges, is stressed not only by natural ageing and corrosion but also by fatigue. The fatigue of material is accelerated by the steadily growing traffic volume and heavier vehicles. Many bridges were built after World War 2 using the prestressed concrete construction method that emerged at that time. Some bridges are close to the end of the planned service life and show damage such as spalling, cracking and corrosion. In addition, some bridges have not yet reached the end of their planned service life and already exhibit damage. These bridges require special attention and control, knowing that this issue is highly safety and cost relevant at the same time. Structural Health Monitoring (SHM) of bridges aims to detect and localise damage as early as possible to take countermeasures to reach at least the planned service life or even more. Therefore, control systems are needed to support the engineers in addition to the visual bridge inspection. Permanent control systems can allow real time controlling of the bridge behaviour but generate high effort and cost. One approach in SHM is damage detection based on stiffness changes. Damage can alter both the static and modal properties of a structure. It leads to a loss of stiffness and, consequently, to greater static deflection and, in dynamics, to a decrease of eigenfrequencies. A prerequisite for early damage detection is essential information about the bridge structure, best knowledge and understanding of the individual bridge behaviour already in the undamaged state to track changes. This information can be obtained with experiments on a bridge and, in parallel, by simulation with a Finite Element (FE) model. In the next step, the FE model is updated to the measurements so that the reference state of the structure is well matched. The aim of the simulation is not the ultimate load bearing analysis, but the simulation of changes in the deflection line, eigenfrequencies, mode shapes and in the best case, also in the static or dynamic flexibility matrix and even better stiffness matrix due to damage. For this purpose, recurring measurements and simulations are compared with the initial measurements. If changes in the properties occur, model updating can be used to detect, localise and quantify damage. For the described approach, the detection and localisation of damage depend on the best possible reference state’s characteristics acquisition. The most commonly used construction method for bridges is prestressed concrete. Therefore, the main focus of this work is the recording of the undamaged reference state of a post tensioning bridge beam. The test object was a 26 m long prestressed concrete T-beam, which was saved before the demolition of the real bridge. It was subsequently installed outdoors on the campus of the University of Luxembourg as a simple supported real size test beam. Since the changes in static and dynamic system properties are not only due to damage but can also occur, for example, as a result of temperature fluctuations, the work focuses as well on the recording and assessment of influences arising from bearing and real environmental conditions in the undamaged reference state. For the temperature acquisition, the tests were carried out over around 2 years. Moreover, the influence of bearing conditions was tested by three interchangeable movable bearing types. The reference condition was recorded by static, quasi-static and dynamic tests. Throughout the observation period, the temperature and deflection of the bridge were continuously measured at different positions. For the deflection measurements, a commercial system was used that requires contact with the bridge. In addition, two new non-contact measurement approaches were tested. One is a camera-based system and the other is a laser-based system. The laser-based measurement method was improved during the recordings and tested by a second laser based system at the beam. Through the various tests, the deflections, eigenfrequencies and mode shapes of the bridge were determined. With the information of the experimental part, an FE model was created and best fitted to the reference state. The FE model consists mainly of solid elements. For a future model updating, a special FE model was created, offering a slice-by-slice adjustment of the beam stiffness. The model was used to perform static deformation and modal analysis. Then, the static and dynamic flexibility matrix was calculated and compared based on the experimental and numerical results. Finally, and in view of the subsequent artificial damage of the beam, damage scenarios are proposed based on the calculated cracking moment. [less ▲]

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See detailIntelligent Reflecting Surface-assisted MU-MISO Systems with Imperfect Hardware: Channel Estimation and Beamforming Design
Papazafeiropoulos, Anastasios; Pan, Cunhua; Kourtessis, Pandelis et al

Poster (2021)

Intelligent reflecting surface (IRS), consisting of lowcost passive elements, is a promising technology for improving the spectral and energy efficiency of the fifth-generation (5G) and beyond networks ... [more ▼]

Intelligent reflecting surface (IRS), consisting of lowcost passive elements, is a promising technology for improving the spectral and energy efficiency of the fifth-generation (5G) and beyond networks. It is also noteworthy that an IRS can shape the reflected signal propagation. Most works in IRSassisted systems have ignored the impact of the inevitable residual hardware impairments (HWIs) at both the transceiver hardware and the IRS while any relevant works have addressed only simple scenarios, e.g., with single-antenna network nodes and/or without taking the randomness of phase noise at the IRS into account. In this work, we aim at filling up this gap by considering a general IRS-assisted multi-user (MU) multiple-input single-output (MISO) system with imperfect channel state information (CSI) and correlated Rayleigh fading. In parallel, we present a general computationally efficient methodology for IRS reflect beamforming (RB) optimization. Specifically, we introduce an advantageous channel estimation (CE) method for such systems accounting for the HWIs. Moreover, we derive the uplink achievable spectral efficiency (SE) with maximal-ratio combining (MRC) receiver, displaying three significant advantages being: 1) its closed-form expression, 2) its dependence only on large-scale statistics, and 3) its low training overhead. Notably, by exploiting the first two benefits, we achieve to perform optimization with respect to the that can take place only at every several coherence intervals, and thus, reduces significantly the computational cost compared to other methods which require frequent phase optimization. Among the insightful observations, we highlight that uncorrelated Rayleigh fading does not allow optimization of the SE, which makes the application of an IRS ineffective. Also, in the case that the phase drifts, describing the distortion of the phases in the RBM, are uniformly distributed, the presence of an IRS provides no advantage. The analytical results outperform previous works and are verified by Monte-Carlo (MC) simulations. [less ▲]

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See detailThermalization Induced by Quantum Scattering
Jacob, Samuel L.; Esposito, Massimiliano UL; Parrondo, Juan M. R. et al

in PRX Quantum (2021), 2

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See detailLinear response in large deviations theory: a method to compute non-equilibrium distributions
Freitas, Nahuel; Falasco, Gianmaria UL; Esposito, Massimiliano UL

in New J. Phys. (2021), 23(9), 093003

Detailed reference viewed: 42 (0 UL)