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See detailSoftwarization of SCADA: Lightweight Statistical SDN-Agents for Anomaly Detection
Rinaldi, Giulia UL; Adamsky, Florian UL; Soua, Ridha UL et al

in 10th International Conference on Networks of the Future (NoF) (2019, October 04)

The increasing connectivity of restricted areas suchas Critical Infrastructures (CIs) raises major security concernsfor Supervisory Control And Data Acquisition (SCADA) systems,which are deployed to ... [more ▼]

The increasing connectivity of restricted areas suchas Critical Infrastructures (CIs) raises major security concernsfor Supervisory Control And Data Acquisition (SCADA) systems,which are deployed to monitor their operation. Given the impor-tance of an early anomaly detection, Intrusion Detection Systems(IDSs) are introduced in SCADA systems to detect malicious ac-tivities as early as possible. Agents or probes form the cornerstoneof any IDS by capturing network packets and extracting relevantinformation. However, IDSs are facing unprecedented challengesdue to the escalation in the number, scale and diversity of attacks.Software-Defined Network (SDN) then comes into play and canprovide the required flexibility and scalability. Building on that,we introduce Traffic Agent Controllers (TACs) that monitor SDN-enabled switches via OpenFlow. By using lightweight statisticalmetrics such as Kullback-Leibler Divergence (KLD), we are ableto detect the slightest anomalies, such as stealth port scans, evenin the presence of background traffic. The obtained metrics canalso be used to locate the anomalies with precision over 90%inside a hierarchical network topology. [less ▲]

Detailed reference viewed: 207 (15 UL)
See detailDer Sohn ist aus den Fugen. Posthistorische Zeiterfahrungen bei David Wagner und Thomas von Steinaecker.
Pause, Johannes UL

in Gisbertz, Anna-Katharina; Ostheimer, Michael (Eds.) Geschichte – Latenz – Zukunft. Zur narrativen Modellierung von Zeit im neueren Generationenroman, Hannover (2017)

Detailed reference viewed: 41 (0 UL)
See detailSoi et les langues
Hu, Adelheid UL; Lévy, Danielle

in Zarate, G.; Lévy, D.; Kramsch, C. (Eds.) Précis du Plurilinguisme et Pluriculturalisme (2008)

Detailed reference viewed: 61 (2 UL)
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See detailSoil Fatigue Due To Cyclically Loaded Foundations
Pytlik, Robert Stanislaw UL

Doctoral thesis (2016)

Cyclic loading on civil structures can lead to a reduction of strength of the used materials. A literature study showed that, in contrast to steel structures and material engineering, there are no design ... [more ▼]

Cyclic loading on civil structures can lead to a reduction of strength of the used materials. A literature study showed that, in contrast to steel structures and material engineering, there are no design codes or standards for fatigue of foundations and the surrounding ground masses in terms of shear strength reduction. Scientific efforts to study the fatigue behaviour of geomaterials are mainly focused on strain accumulation, while the reduction of shear strength of geomaterials has not been fully investigated. It has to be mentioned that a number of laboratory investigation have been done and some models have been already proposed for strain accumulation and pore pressure increase which can lead to liquefaction. Laboratory triaxial tests have been performed in order to evaluate the fatigue of soils and rocks by comparing the shear strength parameters obtained in cyclic triaxial tests with the static one. Correlations of fatigue with both, the number of cycles and cyclic stress ratio have been given. In order to apply cyclic movements in a triaxial apparatus, a machine setup and configuration was made. A special program was written in LabVIEW to control the applied stresses and the speed of loading, which allowed simulating the natural loading frequencies. Matlab scripts were also written to reduce the time required for the data processing. Both cohesive and cohesionless geomaterials were tested: artificial gypsum and mortar as cohesive geomaterials, and sedimentary limestone, and different sands, as cohesionless and low-cohesive natural materials. The artificial gypsum, mortar and natural limestone exhibit mostly brittle behaviour, where the crumbled limestone and other sand typical ductile one. All the sands as well as the crumbled limestone were slightly densified before testing therefore; they can be treated as dense sands. The UCS for the crumbled limestone is 0.17 MPa and standard error of estimate σest = 0.021 MPa, where for mortar UCS = 9.11 MPa with σest = 0.18 MPa and for gypsum UCS = 6.02 MPa with standard deviation = 0.53. All triaxial tests were conducted on dry samples in the natural state, without presence of water (no pore pressure). The range of the confining pressure was between 0 MPa and 0.5 MPa. The cyclic tests carried out were typical multiple loading tests with constant displacement ratio up to a certain stress level. The frequency was kept low to allow for precise application of cyclic load and accurate readings. What is more, the frequency of the cyclic loading corresponds to the natural loading of waves and winds. The number of applied cycles was from few cycles up to few hundred thousand (max number of applied cycles was 370 000). Due to the complex behaviour of materials and high scatter of the results, many tests were required. Two different strategies were used to investigate fatigue of geomaterials: 1) the remaining shear strength curve; after a given number of cycles, a final single load test was done until failure in order to measure the remaining shear strength of the sample. 2) the typical S-N curve (Wöhler curves); there is simply a constant loading until failure. The remaining shear strength (or strength reduction) curve has been compared with the standard S-N curve, and is found to be very similar because the cyclic stress ratio has little influence. The cyclic loading on geomaterials, being an assemblage of different sizes and shapes of grains with voids etc., showed different types of effects. Cohesionless materials show a shear strength increase during the cyclic loading, while cohesive ones show a shear strength decrease. For the cohesive materials the assumption was made that the friction angle remains constant; so, the fatigue of geomaterials can be seen as a reduction of the cohesion. In this way, the fatigue of a cohesive geomaterial can be described by a remaining cohesion. The imperfections in the artificial gypsum have a significant impact on the results of the (especially cyclic) strength tests. Therefore another man made materials was used – a mixture of sand and cement (mortar). As the first static test results were very promising, mortar was used in further tests. The cyclic tests, however, presented similar, high scatter of results as for artificial gypsum. An unexpected observation for both materials was a lack of dependency of the remaining shear strength on the cyclic stress ratio. The strain-stress relationship in cyclic loading shows that the fatigue life of the geomaterials can be divided into three stages, just as for creep. The last phase with a fast increase in plastic strains could be an indicator of an incoming failure. The accumulation of strains and increase of internal energy could be good indicators too, but no strong correlation, has been found. Similar to the shear strength, the stiffness changes during cyclic loading; for cohesive materials the stiffness increase, while for cohesionless it decreases. This could help to predict the remaining shear strength of a geomaterial by using a non-destructive method. [less ▲]

Detailed reference viewed: 576 (5 UL)
See detailSoil Mechanics
Verruijt, A; Van Baars, Stefan UL

Book published by VSSD (2007)

Detailed reference viewed: 282 (5 UL)
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See detailThe soil of Luxembourg and the weak Rhaetian clay
Van Baars, Stefan UL

in Cahier Scientifique - Revue Technique Luxembourgeoise (2014), 2013(2), 34-37

Luxembourg is geologically divided into two parts: Oesling in the North and Gutland in the Middle and South. Oesling is part of the Ardennes plateau. Gutland was formed in the Triassic and Jurassic ages ... [more ▼]

Luxembourg is geologically divided into two parts: Oesling in the North and Gutland in the Middle and South. Oesling is part of the Ardennes plateau. Gutland was formed in the Triassic and Jurassic ages and is much younger than Oesling. It consists mainly of sedimentary rocks. Luxembourg has a variety of interesting, weak or problematic soils, such as the swelling gypsum layers, the layered schists of Wiltz and especially the weak Keuper-Rhaetian-clay. The Rhaetian clay layer is mostly rather thin and is found at a relatively constant altitude and the band where it comes to the surface is identified by the varying erosion erratically found throughout Gutland. Approximately two third of all landslides are found along this line. Hence it was decided to investigate the Rhaetian clay in the geotechnical laboratory of the University of Luxembourg. Samples were taken from a pit at Rue de Mühlenbach on the north side of the city of Luxembourg and from a sliding slope of a building pit in Schutrange. The friction angle was found to be phi = 8° at Mühlenbach and phi = 13° at Schuttrange, which are both record low friction angles, which explains the high number of landslides in Luxembourg. [less ▲]

Detailed reference viewed: 331 (13 UL)
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See detailSojourn time dimensions of fractional Brownian motion
Nourdin, Ivan UL; Peccati, Giovanni UL; Seuret, Stéphane

E-print/Working paper (2018)

Detailed reference viewed: 91 (11 UL)
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See detailSoK: Secure E-Voting with Everlasting Privacy
Haines, Thomas; Mueller, Johannes UL; Mosaheb, Rafieh UL et al

in Proceedings on Privacy Enhancing Technologies (PoPETs) (2023)

Vote privacy is a fundamental right, which needs to be protected not only during an election, or for a limited time afterwards, but for the foreseeable future. Numerous electronic voting (e-voting ... [more ▼]

Vote privacy is a fundamental right, which needs to be protected not only during an election, or for a limited time afterwards, but for the foreseeable future. Numerous electronic voting (e-voting) protocols have been proposed to address this challenge, striving for everlasting privacy. This property guarantees that even computationally unbounded adversaries cannot break privacy of past elections. The broad interest in secure e-voting with everlasting privacy has spawned a large variety of protocols over the last three decades. These protocols differ in many aspects, in particular the precise security properties they aim for, the threat scenarios they consider, and the privacy-preserving techniques they employ. Unfortunately, these differences are often opaque, making analysis and comparison cumbersome. In order to overcome this non-transparent state of affairs, we systematically analyze all e-voting protocols designed to provide everlasting privacy. First, we illustrate the relations and dependencies between all these different protocols. Next, we analyze in depth which protocols do provide secure and efficient approaches to e-voting with everlasting privacy under realistic assumptions, and which ones do not. Eventually, based on our extensive and detailed treatment, we identify which research problems in this field have already been solved, and which ones are still open. Altogether, our work offers a well-founded reference point for conducting research on secure e-voting with everlasting privacy as well as for future-proofing privacy in real-world electronic elections. [less ▲]

Detailed reference viewed: 19 (6 UL)
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See detailSoK: Techniques for Verifiable Mix Nets
Mueller, Johannes UL

in Haines, Thomas; Mueller, Johannes (Eds.) IEEE Computer Security Foundations Symposium (2020)

Detailed reference viewed: 55 (5 UL)
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See detailSolar Lasers: Another Dimension in Renewable Energy Applications
Singh, Ajay UL

Learning material (2016)

Detailed reference viewed: 50 (6 UL)
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See detailSolar pumped Nd:YAG laser systems
Singh, Ajay UL; Gupta, Mayank; Mehta, Dalip Singh

in Tezpur University (2016, November)

Solar radiation from sunlight is abundant on our earth during daytime. In order to utilise it, here we report a new design and development of solar pumped Nd:YAG laser system. Sun Light is collected using ... [more ▼]

Solar radiation from sunlight is abundant on our earth during daytime. In order to utilise it, here we report a new design and development of solar pumped Nd:YAG laser system. Sun Light is collected using a large Fresnel lens concentrator of diameter 46 cm, which is then used for side pumping of the Nd:YAG laser rod. Horizontal cavity design with a variable cavity length of 14 cm to 25 cm is proposed in which it accommodates mirror, output coupler, laser rod as well the cooling mechanism. Water cooling is employed to remove extra heat generated around the laser rod. The developed system is low cost and portable. Experimental results of the measurement are solar radiation spectrum, laser line width and output power of laser. Successfully Nd:YAG laser emissions with Full Width Half Maximum of about 1.67 nm at 1064 nm wavelength and Output power of the system has been achieved up to 200 mW. The potential applications of the solar powered laser are laboratory experiments, generation of second harmonic and imaging. [less ▲]

Detailed reference viewed: 42 (1 UL)
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See detailThe solar shakeout – Capital market reactions to bankrupcty announcements in the German solar industry
Kaspereit, Thomas UL; Lopatta, Kerstin UL

in Zeitschrift für Energiewirtschaft (2016), 40(3), 139-158

This paper investigates how bankruptcy announcements in the German solar industry affect the stock market returns of announcing firms and their competitors. We show that German solar firms experience ... [more ▼]

This paper investigates how bankruptcy announcements in the German solar industry affect the stock market returns of announcing firms and their competitors. We show that German solar firms experience negative capital market reactions to their own bankruptcy announcements and to the announcements of their competitors. Cross-sectional analysis reveals that these negative Information externalities are magnified by higher leverage. Further analysis also indicates that these negative Information externalities are valuable predictors in short-term default probability models. [less ▲]

Detailed reference viewed: 92 (4 UL)
Peer Reviewed
See detailSolarthermische Energie in Andalusien - Hindernisse bei der Nutzung eines endogenen Potentials
Helfer, Malte UL

in Geographische Rundschau (1997), 49(6), 348-354

Detailed reference viewed: 68 (0 UL)
See detailDe soldaten van de Eerste Poolse Pantserdivisie. Hun geschiedenis.
Venken, Machteld UL; Pools Institut in Brussel

Article for general public (2014)

Detailed reference viewed: 21 (3 UL)
See detailLes soldats de la Wehrmacht d'Eupen-Malmedy
Brüll, Christoph UL

Scientific Conference (2021, October 14)

Detailed reference viewed: 40 (1 UL)
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See detailSoLeMiO: Semantic Integration of Learning Material in Office
Grevisse, Christian UL; Manrique, Rubén; Mariño, Olga et al

in Proceedings of E-Learn: World Conference on E-Learning in Corporate, Government, Healthcare, and Higher Education 2018 (2018, October 15)

Learners throughout different educational levels and study domains use a significant amount of time to consult learning material. In addition to the resources given by their teachers, further information ... [more ▼]

Learners throughout different educational levels and study domains use a significant amount of time to consult learning material. In addition to the resources given by their teachers, further information might be required by the learner. However, leaving the study context to search for related material may lead to distraction or even abandonment of the learning task. Furthermore, traditional learning resources do not foster active learning. In this paper, we present SoLeMiO, a plugin for Office applications, which identifies key concepts in a document and thereby integrates related, heterogeneous resources from an open corpus. We employ concept recognition tools to determine concepts from different domains. Thereupon, resources from different repositories are suggested to the learner and can be consulted from within the current document. Aside from traditional learning resources, active learning is fostered through gamification activities. We showcase the applicability of our approach in multiple disciplines with concrete examples. [less ▲]

Detailed reference viewed: 90 (14 UL)
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See detailSolfège à la luxembourgeoise. Strength, Weakness and Challenges for Music Education
Sagrillo, Damien UL

Presentation (2014, April 30)

At the beginning of the 20th century, music schools in Luxembourg founded with the focal objective to form young musicians for amateur orchestras and choirs. Given that this was quiet a challenging goal ... [more ▼]

At the beginning of the 20th century, music schools in Luxembourg founded with the focal objective to form young musicians for amateur orchestras and choirs. Given that this was quiet a challenging goal, reality proved that it was difficult to assume. In 1998, after many years of discussion, the parliament of Luxembourg finally voted a law of music education. The aim was to offer an equal level of music education in every region of the country and to motivate more children to attend music courses. Politics facilitated unconsciously, but surely not unwillingly a renaissance of amateur music. But these obvious advantages were lessened by some serious problems. An important part of the students gave up and were disgusted by music practice. In my paper I will describe, how the artistic performance level in amateur ensembles increased, but did not lead to more musicians. But this was not only due to music education, but also to new facilities in practicing music. I will describe, by presenting the statistics of the last few years, that the Luxembourgian system of music education has become elitist in the sense of being well adopted for talented students, but that it does not suit at all for average pupils, who want to make music just for leisure. Only a minor part of young people attend music schools, with an important number beginning musical training at the age of eight years or even earlier, but with a decreasing number completing their musical instruction. Nevertheless, general music education is offered for everybody in primary and secondary schools, i.e. one obligatory hour per week for every pupil from six to fourteen years. However, few students older than fourteen make use of a more specialised offer of music education in secondary schools. Most of the future music students, the elite, opt for this possibility. Music education in Luxembourg is based on the francophone system of solfège, a method for future singers and professional musicians. It is also partially transferred to some instrumental disciplines. However, during the last two decades, in these countries – France and Belgium – solfège is replaced by a less rigorous and better-adapted method of musical training. My paper will also give an historical insight into the system of “solfège” and its didactics over the centuries. [less ▲]

Detailed reference viewed: 145 (9 UL)