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See detailWWI: Kosakenmütze und roter Stern: Russische Gefangene in Luxemburg 1918
Ganschow, Inna UL

E-print/Working paper (2018)

Die vorliegende Teiluntersuchung beschäftigt sich mit den 3.100 russischen Kriegsgefangenen, die 1918 Luxemburg passierten. Etwa 300 blieben nachweislich in Luxemburg, da die sowjetische Ideologie in ... [more ▼]

Die vorliegende Teiluntersuchung beschäftigt sich mit den 3.100 russischen Kriegsgefangenen, die 1918 Luxemburg passierten. Etwa 300 blieben nachweislich in Luxemburg, da die sowjetische Ideologie in ihrer neuen Heimat, die nun Russische Sowjetische Föderative Sozialistische Republik hieß, sie nicht ansprach. In einer mikrohistorischen Perspektive werden mehrere Schicksale vorgeführt, anhand derer man zum einen die Bedingungen dieser Emigration versteht, die sich zwar auf neutralen Boden vollzog, jedoch unter der stetigen Verfolgung durch die deutsche Armee, die die Unabhängigkeit Luxemburgs wenig kümmerte. Zum anderen wird gezeigt, wie “Russisch” immer mehr mit “Kommunistisch” assoziiert wurde und alle Russen unter Verdacht standen, “rot” zu sein. [less ▲]

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See detailThe PytEuk puzzle
Perucca, Antonella UL

Diverse speeches and writings (2018)

We present an original mathematical exhibit in form of a puzzle visualising Pythagoras' Theorem and also the property that the square on the hypothenuse, when cut by the altitude line, consists of two ... [more ▼]

We present an original mathematical exhibit in form of a puzzle visualising Pythagoras' Theorem and also the property that the square on the hypothenuse, when cut by the altitude line, consists of two rectangles that have the size of the two squares on the cathetes. [less ▲]

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See detailPAPR Minimization through Spatio-temporal Symbol-level Precoding for the Non-linear Multi-user MISO Channel
Spano, Danilo UL; Alodeh, Maha; Chatzinotas, Symeon UL et al

in 2018 International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2018) (2018, April 19)

Symbol-level precoding (SLP) is a promising technique which allows to constructively exploit the multi-user interference in the downlink of multiple antenna systems. Recently, this approach has also been ... [more ▼]

Symbol-level precoding (SLP) is a promising technique which allows to constructively exploit the multi-user interference in the downlink of multiple antenna systems. Recently, this approach has also been used in the context of non-linear systems for reducing the instantaneous power imbalances among the antennas. However, previous works have not exploited SLP to improve the dynamic properties of the waveforms in the temporal dimension, which are fundamental for non-linear systems. To fill this gap, this paper proposes a novel precoding method, referred to as spatio-temporal SLP, which minimizes the peak-to-average power ratio of the transmitted waveforms both in the spatial and in the temporal dimensions, while at the same time exploiting the constructive interference effect. Numerical results are presented to highlight the enhanced performance of the proposed scheme with respect to state of the art SLP techniques, in terms of power distribution and symbol error rate over non-linear channels. [less ▲]

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See detailDesigning Joint Precoding and Beamforming in a Multiple Gateway Multibeam Satellite System
Joroughi, Vahid; Shankar, Bhavani UL; Maleki, Sina UL et al

in IEEE WCNC 2018 (2018, April 18)

This paper aims to design joint on-ground precoding and on-board beamforming of a multiple gateway multibeam satellite system in a hybrid space-ground mode where full frequency reuse pattern is considered ... [more ▼]

This paper aims to design joint on-ground precoding and on-board beamforming of a multiple gateway multibeam satellite system in a hybrid space-ground mode where full frequency reuse pattern is considered among the beams. In such an architecture, each gateway serves a cluster of adjacent beams such that the adjacent clusters are served through a set of gateways that are located at different geographical areas. However, such a system brings in two challenges to overcome. First, the inter-beam interference is the bottleneck of the whole system and applying interference mitigation techniques becomes necessary. Second, as the data demand increases, the ground and space segments should employ extensive bandwidth resources in the feeder link accordingly. This entails embedding an extra number of gateways aiming to support a fair balance between the increasing demand and the corresponding required feeder link resources. To solve these problems, this study investigates the impact of employing a joint multiple gateway architecture and on-board beamforming scheme. It is shown that by properly designing the on-board beamforming scheme, the number of gateways can be kept affordable even if the data demand increases. Moreover, Zero Forcing (ZF) precoding technique is considered to cope with the inter-beam interference where each gateway constructs a part of block ZF precoding matrix. The conceived designs are evaluated with a close-to-real beam pattern and the latest broadband communication standard for satellite communications. [less ▲]

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See detailOptimal Relay Selection Strategy for Joint Data and Energy Transfer in Wireless Systems
Gautam, Sumit UL; Lagunas, Eva UL; Chatzinotas, Symeon UL et al

Presentation (2018, April 17)

We study a problem of relay selection in a two-hop amplify-and-forward (AF) enabled relaying network for facilitating simultaneous Wireless Transmission of Information and Energy (Wi-TIE) to a destination ... [more ▼]

We study a problem of relay selection in a two-hop amplify-and-forward (AF) enabled relaying network for facilitating simultaneous Wireless Transmission of Information and Energy (Wi-TIE) to a destination able to perform both information processing and energy harvesting concurrently. Considering the time switching (TS) and power splitting (PS) based Wi-TIE schemes, we formulate an optimization problem to maximize the overall user data rate while ensuring a minimum harvested power. In this context, we obtain suitable closed form solution and demonstrate through simulation results the Rate-Energy (R-E) trade-off in two different scenarios: (i) with only the relay assisted link, and (ii) with the direct link together with the relay assisted link. [less ▲]

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See detailRussians in Luxembourg, WWII: Поиски старого друга
Ganschow, Inna UL

E-print/Working paper (2018)

Спустя семьдесят лет после окончания Второй мировой войны бывший люксембургский военнопленный решил найти своего старого русского друга, которого пригнали на принудительные работы в сталелитейной ... [more ▼]

Спустя семьдесят лет после окончания Второй мировой войны бывший люксембургский военнопленный решил найти своего старого русского друга, которого пригнали на принудительные работы в сталелитейной промышленности и сельском хозяйстве Люксембурга наравне с другими 4.000 узниками. Судьбы двух пленных переплелись, как они переплетутся между советскими и люксембургскими поданными в Европе еще не раз ... [less ▲]

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See detailRussians in Luxembourg: Русские в Вильтце - история первых эмигрантов
Ganschow, Inna UL

E-print/Working paper (2018)

Люксембургская русская община ведет свой отсчет с 1927 года – десятой годовщины Февральской, а потом и Октябрьской, революции. Девяносто лет назад прибыли эмигранты, прошедшие Гражданскую войну и ... [more ▼]

Люксембургская русская община ведет свой отсчет с 1927 года – десятой годовщины Февральской, а потом и Октябрьской, революции. Девяносто лет назад прибыли эмигранты, прошедшие Гражданскую войну и Крымскую эвакуацию 1920-го, положившую конец сопротивлению Белого движения на Юге России. Приехали в Люксембург, думая, что ненадолго, а остались... навсегда. [less ▲]

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See detailJoint Wireless Information and Energy Transfer in Cache-assisted Relaying Systems
Gautam, Sumit UL; Vu, Thang Xuan UL; Chatzinotas, Symeon UL et al

Scientific Conference (2018, April 16)

We investigate the performance of time switching (TS) based energy harvesting model for cache-assisted simultaneous wireless transmission of information and energy (Wi-TIE). In the considered system, a ... [more ▼]

We investigate the performance of time switching (TS) based energy harvesting model for cache-assisted simultaneous wireless transmission of information and energy (Wi-TIE). In the considered system, a relay which is equipped with both caching and energy harvesting capabilities helps a source to convey information to a destination. First, we formulate based on the time-switching architecture an optimization problem to maximize the harvested energy, taking into consideration the cache capability and user quality of service requirement. We then solve the formulated problem to obtain closed-form solutions. Finally, we demonstrate the effectiveness of the proposed system via numerical results. [less ▲]

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See detailLa "souveraineté européenne" et la réforme de la zone euro: à la recherche d'un nouveau compromis franco-allemand
Allemand, Frederic UL

Article for general public (2018)

En deux discours prononcés, en septembre 2017, à Athènes puis à la Sorbonne, Emmanuel Macron a marqué le retour de la France au cœur de l’Europe, en appelant à la refondation du projet européen, sous la ... [more ▼]

En deux discours prononcés, en septembre 2017, à Athènes puis à la Sorbonne, Emmanuel Macron a marqué le retour de la France au cœur de l’Europe, en appelant à la refondation du projet européen, sous la forme d’une « Europe souveraine, unie et démocratique ». L’argument de la souveraineté est placé au service d’une rhétorique traditionnelle des exécutifs français d’une Europe qui protège, qui ne peut être qu’une « Europe puissance ». Les domaines d’expression de cette souveraineté découlent des défis géopolitiques, sécuritaires, sociétaux ou économiques pour la France et l’Europe : la défense, la sécurisation des frontières extérieures, les relations extérieures, la transition écologique, le numérique et la compétitivité économique. Cette dernière « marque de souveraineté » fonde une réflexion spécifique sur la réforme de la gouvernance de la zone euro. Ce dernier point concentrera notre attention : l’ambition française pointe un angle-mort de la gouvernance de la zone euro et cache une préoccupation récurrente depuis dix ans : le décrochage de compétitivité d’avec l’Allemagne et le financement des réformes nécessaires pour rattraper ce retard. [less ▲]

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See detailAnalysis and Comparison of Eurocodes and Chinese codes of Design
Santos Ferreira, Katia UL; Zhang, Qingjie UL; Schäfer, Markus UL

in Young Engineers Colloquium Munich 2018 (2018, April 13)

Eurocodes (EC) which were published in 2007 are one of the most advanced standards for structure design in the world. Today, Eurocodes are not only used in EU or EFTA countries, but also many other ... [more ▼]

Eurocodes (EC) which were published in 2007 are one of the most advanced standards for structure design in the world. Today, Eurocodes are not only used in EU or EFTA countries, but also many other countries use Eurocodes or align their National standards with them, which gives Eurocodes global influence. Chinese codes of practise, on the other hand, benefit from the recent fast developed construction industry and have a vast application base. In the recent years, half of the new building floor area worldwide is built in China. Thus, it is interesting to compare Eurocodes (one of the most used codes worldwide) with the Chinese codes of design (with which most buildings were recently built). [less ▲]

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See detailLongitudinal Shaer in Composite Beams
Zhang, Qingjie UL; Schäfer, Markus UL

in Young Engineers Colloquium Munich 2018 (2018, April 13)

Longitudinal shear has important influences on the performance of composite beams. According to Eurocode 4, with cross-section class 1 and 2 in combination with ductile shear connectors, a plastic method ... [more ▼]

Longitudinal shear has important influences on the performance of composite beams. According to Eurocode 4, with cross-section class 1 and 2 in combination with ductile shear connectors, a plastic method, considering redistribution of longitudinal shear force is allowed. The conditions therefore are full development of plastic moment resistance and sufficient slip at interface to reach the plateau of P-δ curve of the shear connectors. However, for slim-floor beams, it is to question if the above-mentioned method can be applied. To answer it, related topics still need further investigation, which is the focus of the author’s Ph.D work. This paper presents part of the first stage results on the theoretical analysis of longitudinal shear, considering the influence of plasticity of the beam. For composite beams with rigid shear connectors, non-linear shear stress distribution appears in the plastic region, which influences the shear connector arrangement. However, detailed theoretical research is still hard to be found. In this work, based on a simple beam partly in plastic zone, mathematical equations are developed to calculate the plastic zone height and longitudinal shear stress distribution. Benchmarks with ANSYS and existing tests are performed. [less ▲]

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See detailThermodynamically consistent coarse graining of biocatalysts beyond Michaelis–Menten
Wachtel, Artur UL; Rao, Riccardo UL; Esposito, Massimiliano UL

in New Journal of Physics (2018), 20(4), 042002

Starting from the detailed catalytic mechanism of a biocatalyst we provide a coarse-graining procedure which, by construction, is thermodynamically consistent. This procedure provides stoichiometries ... [more ▼]

Starting from the detailed catalytic mechanism of a biocatalyst we provide a coarse-graining procedure which, by construction, is thermodynamically consistent. This procedure provides stoichiometries, reaction fluxes (rate laws), and reaction forces (Gibbs energies of reaction) for the coarse-grained level. It can treat active transporters and molecular machines, and thus extends the applicability of ideas that originated in enzyme kinetics. Our results lay the foundations for systematic studies of the thermodynamics of large-scale biochemical reaction networks. Moreover, we identify the conditions under which a relation between one-way fluxes and forces holds at the coarse-grained level as it holds at the detailed level. In doing so, we clarify the speculations and broad claims made in the literature about such a general flux–force relation. As a further consequence we show that, in contrast to common belief, the second law of thermodynamics does not require the currents and the forces of biochemical reaction networks to be always aligned. [less ▲]

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See detailBelgien in Deutschland oder Belgier in Deutschland? Die Zeit der Präsenzpolitik (1945-1955)
Brüll, Christoph UL

Scientific Conference (2018, April 12)

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See detail100 Years of Prandtl's Wedge
Van Baars, Stefan UL

Book published by IOS Press (2018)

The biggest problem for a shallow foundation, just as for any other type of foundation, is a failure due to an overestimation of the bearing capacity. This means that the correct prediction of the bearing ... [more ▼]

The biggest problem for a shallow foundation, just as for any other type of foundation, is a failure due to an overestimation of the bearing capacity. This means that the correct prediction of the bearing capacity of the foundation is often the most important part of the design of a civil structure. That is why the publication by Prandtl in 1920 about the hardness of a plastic body, was a major step in solving the bearing capacity of shallow foundations, although it is well possible that he never realised this, because his solution was not made for civil engineering purposes, but for mechanical purposes. Over the last 100 years, a lot of extensions have been made, for example with inclination factors and shape factors. Also many laboratory experiments have been done and numerical calculations have been made. Some even try to extrapolate the failure mechanism for shallow foundations to the failure mechanism around the tip of a pile. All this scientific work leads back to the first publication by Ludwig Prandtl in 1920. This book, “100 Years of Prandtl’s Wedge”, is intended for all those who are interested in these fundamentals of foundation engineering and their history. The Appendices include a copy of Prandtl’s Über die Härte plastischer Körper and of Reissner’s publication of 1924, Zum Erddruckproblem. [less ▲]

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See detailTowards multiscale data fusion of high-resolution space borne and terrestrial datasets over Tristan da Cunha
Backes, Dietmar UL; Teferle, Felix Norman UL; Abraha, Kibrom Ebuy UL et al

Poster (2018, April 10)

Ever improving low cost, lightweight and easy to use sensing technologies are enabling the capture of rich 3D Datasets to support an unprecedented range of applications in Geosciences. Especially low-cost ... [more ▼]

Ever improving low cost, lightweight and easy to use sensing technologies are enabling the capture of rich 3D Datasets to support an unprecedented range of applications in Geosciences. Especially low-cost LiDAR systems as well as optical sensors, which can be deployed from terrestrial or low altitude aerial platforms, allow the collection of large datasets without detailed expert knowledge or training. Dense pointcloud derived from these technologies provide an invaluable source to fill the gap between highly precise and accurate terrestrial topographic surveys and large area Digital Surface Models (DSMs) derived from airborne and spaceborne sensors. However, the collection of reliable 3D pointclouds in remote and hazardous locations remains to be very difficult and costly. Establishing a reliable georeference, ensuring accuracy and data quality as well as merging such rich datasets with existing or space borne mapping provide additional challenges. The presented case study investigates the data quality and integration of a heterogeneous dataset collected over the remote island of Tristan da Cunha. High-resolution 3D pointclouds derived by TLS and drone Photogrammetry are merged with space borne imagery while preserving the accurate georeference provided by Ground Control derived from geodetic observations. The volcanic island of Tristan da Cunha located in the centre of the Southern Atlantic Ocean is one of the most remote and difficult to access locations on the planet. Its remote location, rough climatic conditions and consistent cloud coverage provides exceptional challenges for terrestrial, aerial as well as space borne data acquisition. Amongst many other scientific installations, the island also hosts a continuous GNSS station observation and monitoring facilities operated by the University of Luxembourg, which provided the opportunity to conduct a local terrestrial data acquisition campaign consistent with a terrestrial ground survey, Laserscanning and an image acquisition from a low-cost drone. The highly accurate Ground Control network, observed by GNSS and total station, provides a reliable georeference. Pointclouds were acquired around the area of the harbour using a Leica P20 terrestrial Laserscanner, as well as drone Photogrammetry based on images collected by a low-cost DJI Phantom3 drone. To produce a map of the complete island a comprehensive dataset of high-resolution space borne imagery based on the Digital Globe WorldView constellation was acquired which provided high resolution mapping information. The case study presents a cross-validation of terrestrial, low altitude airborne as well as spaceborne datasets in terms coregistration, absolute georeference, scale, resolution and overall data quality. Following the evaluation a practical approach to fuse this heterogeneous dataset is applied which aims to preserve overall data quality, local resolution and accurate georeference and avoid edge artefacts. The conclusions drawn from our preliminary results provide some good practice advice for similar projects. The final topographic dataset enables mapping and monitoring of local geohazards as, e.g. coastal erosion and recent landslides thus also supporting the local population. [less ▲]

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See detailLa place du « numérique » dans l’histoire du numérique
Schafer, Valerie UL

Presentation (2018, April 10)

Cette présentation revient sur l'histoire du numérique, sa fabrique et son écriture autour de 3 enjeux 1- Périmètres de recherche sur l'histoire du numérique 2- Les archives notamment nativement ... [more ▼]

Cette présentation revient sur l'histoire du numérique, sa fabrique et son écriture autour de 3 enjeux 1- Périmètres de recherche sur l'histoire du numérique 2- Les archives notamment nativement numériques 3- Les outils numériques au service de la recherche [less ▲]

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See detailEnabling Temporal-Aware Contexts for Adaptative Distributed Systems
Mouline, Ludovic UL; Benelallam, Amine; Hartmann, Thomas UL et al

in SAC 2018: SAC 2018: Symposium on Applied Computing , April 9--13, 2018, Pau, France (2018)

Distributed adaptive systems are composed of federated entities offering remote inspection and reconfiguration abilities. This is often realized using a MAPE-K loop, which constantly evaluates system and ... [more ▼]

Distributed adaptive systems are composed of federated entities offering remote inspection and reconfiguration abilities. This is often realized using a MAPE-K loop, which constantly evaluates system and environmental parameters and derives corrective actions if necessary. The OpenStack Watcher project uses such a loop to implement resource optimization services for multi-tenant clouds. To ensure a timely reaction in the event of failures, the MAPE-K loop is executed with a high frequency. A major drawback of such reactivity is that many actions, e.g., the migration of containers in the cloud, take more time to be effective and their effects to be measurable than the MAPE-k loop execution frequency. Unfinished actions as well as their expected effects over time are not taken into consideration in MAPE-K loop processes, leading upcoming analysis phases potentially take sub-optimal actions. In this paper, we propose an extended context representation for MAPE-K loop that integrates the history of planned actions as well as their expected effects over time into the context representations. This information can then be used during the upcoming analysis and planning phases to compare measured and expected context metrics. We demonstrate on a cloud elasticity manager case study that such temporal action-aware context leads to improved reasoners while still be highly scalable. [less ▲]

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See detailVertical Land Movements and Sea Level Changes around South Georgia Island
Teferle, Felix Norman UL; Hunegnaw, Addisu UL; Abraha, Kibrom Ebuy UL et al

Poster (2018, April 09)

South Georgia Island in the Southern Atlantic Ocean is a key location for the seismic, geomagnetic and oceanic global monitoring networks. In its sub-Antarctic location, the island is largely covered by ... [more ▼]

South Georgia Island in the Southern Atlantic Ocean is a key location for the seismic, geomagnetic and oceanic global monitoring networks. In its sub-Antarctic location, the island is largely covered by mountain glaciers which have been reported to be retreating due to climatic change. Furthermore, during past glaciation periods the island and its shelf area have been ice covered as was revealed by scarring of the sub-oceanic topography. Together with ongoing tectonics along the North Scotia Ridge, these processes have the ability to produce significant uplift on local to regional scales, affecting the measurements of the tide gauge (GLOSS ID 187) at King Edward Point (KEP). Furthermore, with its mid-ocean location, the tide gauge is of particular interest to satellite altimetry calibrations over the Southern Atlantic and Southern Oceans. With the establishment of five GNSS stations on the islands during 2013 to 2015 and the scientific analysis of these data within the global network of stations of the International GNSS Service Tide Gauge Benchmark Monitoring (TIGA) working group, it has now become possible to study present-day vertical land movements of the region and their impacts on, for example, regional sea level. Furthermore, together with four precise levelling campaigns of the KEP benchmark network in 2013, 2014 and two in 2017, it has also been possible to investigate the very local character of the vertical motions near KEP, ie. the stability of the jetty upon which the tide gauge is mounted. In this study, we will present the still preliminary results from the GNSS and levelling measurements and will discuss their impact on the sea level record from the KEP tide gauge. Our measurements show that while South Georgia Island and the area around KEP are rising, the jetty and tide gauge are subsiding, leading to a disagreement in the observed sea level change from the tide gauge and satellite altimetry. In order to improve the agreement between these sea level measurements both local and regional vertical land movements need to be monitored. [less ▲]

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See detailTemporalités du Centenaire de la Grande Guerre sur Twitter
Clavert, Frédéric UL

in Schafer, Valerie (Ed.) Temps et temporalités du Web (2018)

This chapter provides an analysis of the different temporalities that can be perceived in a large corpus of tweets relating to the Great War and its Centenary. In particular, it questions the effects of ... [more ▼]

This chapter provides an analysis of the different temporalities that can be perceived in a large corpus of tweets relating to the Great War and its Centenary. In particular, it questions the effects of information "wavelets" specific to digital social networks on these temporalities. [less ▲]

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