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See detailScattering theory without injectivity radius assumptions and spectral stability for the Ricci flow
Güneysu, Batu; Thalmaier, Anton UL

E-print/Working paper (2017)

We prove a completely new integral criterion for the existence and completeness of the wave operators W_{\pm}(-\Delta_h,-\Delta_g, I_{g,h}) corresponding to the (unique self-adjoint realizations of) the ... [more ▼]

We prove a completely new integral criterion for the existence and completeness of the wave operators W_{\pm}(-\Delta_h,-\Delta_g, I_{g,h}) corresponding to the (unique self-adjoint realizations of) the Laplace-Beltrami operators -\Delta_j, j=g,h, that are induced by two quasi-isometric complete Riemannian metrics g and h on an open manifold M. In particular, this result provides a criterion for the absolutely continuous spectra of -\Delta_g and -\Delta_h to coincide. Our proof relies on estimates that are obtained using a probabilistic Bismut type formula for the gradient of a heat semigroup. Unlike all previous results, our integral criterion only requires some lower control on the Ricci curvatures and some upper control on the heat kernels, but no control at all on the injectivity radii. As a consequence, we obtain a stability result for the absolutely continuous spectrum under a Ricci flow. [less ▲]

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See detailOpening remarks: From Tablet to Tablet – workshop Jewish Studies & Digital Humanities, Hamburg, 4-6 September 2017
Zaagsma, Gerben UL

Presentation (2017, September 05)

This is the written version of opening remarks I gave at From Tablet to Tablet, a workshop on Jewish Studies and Digital Humanities supported by the Rothschild Foundation Hanadiv Europe in co-operation ... [more ▼]

This is the written version of opening remarks I gave at From Tablet to Tablet, a workshop on Jewish Studies and Digital Humanities supported by the Rothschild Foundation Hanadiv Europe in co-operation with the Institute for the History of the German Jews that took place in Hamburg between 4-6 September 2017. [less ▲]

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See detailIntroduction to Detection of Non-Technical Losses using Data Analytics
Glauner, Patrick UL; Meira, Jorge Augusto UL; State, Radu UL et al

Scientific Conference (2017, September)

Electricity losses are a frequently appearing problem in power grids. Non-technical losses (NTL) appear during distribution and include, but are not limited to, the following causes: Meter tampering in ... [more ▼]

Electricity losses are a frequently appearing problem in power grids. Non-technical losses (NTL) appear during distribution and include, but are not limited to, the following causes: Meter tampering in order to record lower consumptions, bypassing meters by rigging lines from the power source, arranged false meter readings by bribing meter readers, faulty or broken meters, un-metered supply, technical and human errors in meter readings, data processing and billing. NTLs are also reported to range up to 40% of the total electricity distributed in countries such as Brazil, India, Malaysia or Lebanon. This is an introductory level course to discuss how to predict if a customer causes a NTL. In the last years, employing data analytics methods such as data mining and machine learning have evolved as the primary direction to solve this problem. This course will compare and contrast different approaches reported in the literature. Practical case studies on real data sets will be included. Therefore, attendees will not only understand, but rather experience the challenges of NTL detection and learn how these challenges could be solved in the coming years. [less ▲]

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See detailDie steuerrechtlichen Herausforderungen der digitalen Wirtschaft - Was passiert in Europa?
Sinnig, Julia UL

in Taeger, Juergen (Ed.) Tagungsband Herbstakademie 2017: Recht 4.0 - Innovationen aus den rechtswissenschaftlichen Laboren (2017, September)

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See detailComparing Broad-Phase Interaction Detection Algorithms for Multiphysics DEM Applications
Rousset, Alban UL; Mainassara Chekaraou, Abdoul Wahid UL; Liao, Yu-Chung UL et al

Scientific Conference (2017, September)

Collision detection is an ongoing source of research and optimization in many fields including video-games and numerical simulations [6, 7, 8]. The goal of collision detection is to report a geometric ... [more ▼]

Collision detection is an ongoing source of research and optimization in many fields including video-games and numerical simulations [6, 7, 8]. The goal of collision detection is to report a geometric contact when it is about to occur or has actually occurred. Unfortunately, detailed and exact collision detection for large amounts of objects represent an immense amount of computations, naivly n 2 operation with n being the number of objects [9]. To avoid and reduce these expensive computations, the collision detection is decomposed in two phases as it shown on Figure 1: the Broad-Phase and the Narrow-Phase. In this paper, we focus on Broad-Phase algorithm in a large dynamic three-dimensional environment. We studied two kinds of Broad-Phase algorithms: spatial partitioning and spatial sorting. Spatial partitioning techniques op- erate by dividing space into a number of regions that can be quickly tested against each object. Two types of spatial partitioning will be considered: grids and trees. The grid-based algorithms consist of a spatial partitioning processing by dividing space into regions and testing if objects overlap the same region of space. And this reduces the number of pairwise to test. The tree-based algorithms use a tree structure where each node spans a particular space area. This reduces the pairwise checking cost because only tree leaves are checked. The spatial sorting based algorithm consists of a sorted spatial ordering of objects. Axis-Aligned Bounding Boxes (AABBs) are projected onto x, y and z axes and put into sorted lists. By sorting projection onto axes, two objects collide if and only if they collide on the three axes. This axis sorting reduces the number of pairwise to tested by reducing the number of tests to perform to only pairs which collide on at least one axis. For this study, ten different Broad-Phase collision detection algorithms or framework have been considered. The Bullet [6], CGAL [10, 11] frameworks have been used. Concerning the implemented algorithms most of them come from papers or given implementation [less ▲]

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See detailFacts and Statements of the 12th FIEP European Congress
Bund, Andreas UL

Presentation (2017, September)

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See detailLaboratory experiment for damage assessment using the DAD-method
Erdenebat, Dolgion UL; Waldmann, Danièle UL; Teferle, Felix Norman UL

in Conference proceedings SMAR 2017 (2017, September)

In the following, a new analytical method, the Deformation Area Difference (DAD) method for damage assessment of bridge structures is applied using experimental test results of a statically loaded beam ... [more ▼]

In the following, a new analytical method, the Deformation Area Difference (DAD) method for damage assessment of bridge structures is applied using experimental test results of a statically loaded beam. An essential prerequisite for the application of this method is a high precise measurement of the deflection line. In this paper, the results from a laboratory experiment using modern measurement techniques such as photogrammetry and displacement sensors are discussed. A reinforced concrete beam is stepwise loaded until reaching the ultimate limit state. The DAD-method is applied to the resulting data from the measurements and the outcome is discussed for further optimisation of the method. In principle, the measured deflection line of the beam contains already essential information on discontinuities which occur due to cracking. These entries are processed and visualised using the DAD-method. This study shows that a high accuracy of the measurement techniques in combination with the DAD-method can become an effective tool for damage detection. [less ▲]

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See detailEmployable Middle Ages - MediävistInnen auf dem Arbeitsmarkt von morgen?
Bendheim, Amelie UL

Scientific Conference (2017, September)

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See detailZusammenhänge zwischen Zahlenstrahlschätzfähigkeit, Mathematikleistung und Schülercharakteristika: Eine Vollerhebung mit 6484 Luxemburgischen Neuntklässlern
Nurayadin, Sevim; Ugen, Sonja UL; Martin, Romain et al

Scientific Conference (2017, September)

In der Zahlenstrahlschätzaufgabe sehen die Probanden eine Zahl und einen leeren Zahlenstrahl, bei dem nur die erste und die letzte Position markiert und mit ihrem Wert beschriftet sind. Die Aufgabe der ... [more ▼]

In der Zahlenstrahlschätzaufgabe sehen die Probanden eine Zahl und einen leeren Zahlenstrahl, bei dem nur die erste und die letzte Position markiert und mit ihrem Wert beschriftet sind. Die Aufgabe der Probanden besteht darin, die Position der Zahl auf dem Strahl anzugeben. Der vorherrschende Ansatz in der Literatur geht davon aus, dass diese Aufgabe die Qualität der mentalen Repräsentation numerischer Größen erfasst. Diese gibt Lernen ein Verständnis von numerischen Größen und ihren Interrelationen, das eine wichtige Grundlage für den Erwerb anspruchsvollerer mathematischer Kompetenzen z.B. in Arithmetik oder Algebra darstellt. Zahlreiche Studien fanden positive Korrelationen zwischen der Zahlenstrahlschätzfähigkeit und der Mathematikleistung. Daher bietet es sich an, die Zahlenstrahlschätzaufgabe zur Diagnostik mathematischer Leistung und Entwicklung zu nutzen. Jedoch ist zum einen noch unklar, wie die Zahlstrahlschätzfähigkeit in der Population ausgeprägt und verteilt ist. Zum anderen ist offen, inwieweit die Korrelation mit der Mathematikleistung eine Scheinkorrelation darstellt, die auf den Einfluss anderer Personeneigenschaften zurückgeht. Um diese Punkte zu klären, analysierten wir Daten aus einer Vollerhebung aller Neuntklässler in Luxemburg (N = 6484). Die Schüler lösten die Zahlenstrahlschätzaufgabe mit ganzen Zahlen sowie Brüchen, absolvierten einen standardisierten Mathematikleistungstest und beantworteten zahlreiche Fragen zu domänenspezifischen (Matheängstlichkeit, Selbstkonzept, Interesse, Testmotivation) und domänenübergreifenden (Geschlecht, Immigrationsstatus, Gewissenhaftigkeit und elterlicher sozioökonomischer Status) Personenmerkmalen. Wir dokumentierten Mittelwerte und Verteilungseigenschaften der Zahlenstrahlschätzfähigkeit für diverse Subpopulationen (Jungen, Mädchen, Migranten, Schulformen etc.). Die Ergebnisse von Mehrebenenregressionsmodellen zeigten, dass die Zahlenstrahlschätzfähigkeit erheblich enger als alle anderen erhobenen Personeneigenschaften mit der Mathematikleistung zusammenhing. Der Zusammenhang war stärker für das Schätzen von Brüchen als ganzen Zahlen. Die Ergebnisse bestätigen die Annahme, dass die Zahlenstrahlschätzfähigkeit eine zentrale Komponente mathematischen Vorwissens erfasst, die weiteres Lernen leitet. In Anbetracht der einfachen Handhabung kann die Aufgabe vielfältig eingesetzt werden, um die mathematische Leistung in der Schule zu messen oder vorherzusagen. Zukünftige Studien sollten verstärkt die Nutzung der Aufgabe in Interventionen erproben. [less ▲]

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See detailThe axisymetric failure mechanism of circular shallow foundations and pile foundations in non-cohesive soils
Van Baars, Stefan UL

in Computations and Materials in Civil Engineering (2017), 2(1), 1-15

In 1920 Prandtl published an analytical solution for the bearing capacity of a centric loaded strip footing on a weightless in-finite half-space, based on a so-called Prandtl-wedge failure mechanism ... [more ▼]

In 1920 Prandtl published an analytical solution for the bearing capacity of a centric loaded strip footing on a weightless in-finite half-space, based on a so-called Prandtl-wedge failure mechanism. Reissner extended this solution for a surrounding surcharge and Keverling Buisman and Terzaghi for the soil weight. Meyerhof and other researchers presented correction factors for the shape of the shallow foundation, which would suggest that, the failure mechanism of circular shallow foundations, is related to the Prandtl-wedge failure mechanism. Meyerhof and Koppejan adapted this Prandtl-wedge failure mechanism also for pile foundations. The numerical calculations made in this article show that the Prandtl-wedge cannot be applied to circular shallow foundations and pile foundations in non-cohesive soils. The failure zone (plastic zone) below a loaded circular plate or pile tip, is far wider and deeper than the Prandtl-wedge. The calculations also show that there is, for these axisymmetric cases, failure both in and out of the standard x-y plane, but most of the failure is due to out-of-plane (tangential) failure. Therefore, this failure mechanism is different from the Prandtl-wedge failure mechanism. Also interesting are the circular and diagonal thin zones below the plate and around the pile tip, where there is no out-of-plane failure, although there is still in-plane failure. In these thin zones without out-of-plane failure, the tangential (out-of-plane) stresses are relatively high due to large shear strains, formed during previous shearing or sliding of the soil. [less ▲]

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See detailInterkulturelle Annäherung im Zeichen der Exogamie - Kommunikationsstrategien im König Rother
Bendheim, Amelie UL

Scientific Conference (2017, September)

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See detailDynamics of Income Rank Volatility: Evidence from Germany and the US
Chauvel, Louis UL; Hartung, Anne UL; Palmisano, Flaviana

E-print/Working paper (2017)

This paper presents a methodology for comparing income rank volatility profiles over time and across distributions. While most of the existing measures are affected by changes in marginal distributions ... [more ▼]

This paper presents a methodology for comparing income rank volatility profiles over time and across distributions. While most of the existing measures are affected by changes in marginal distributions, this paper proposes a framework that is based on individuals’ relative positions in the distribution, and is neutral in relation to structural changes that occur in the economy. Applying this approach to investigate rank volatility in Germany and the US over three decades, we show that while poorer individuals within both countries are the most volatile, the volatility trend for the middle class in each of these countries differs. [less ▲]

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See detailAutomated and Effective Security Testing for XML-based Vulnerabilities
Jan, Sadeeq UL

Doctoral thesis (2017)

Nowadays, the External Markup Language (XML) is the most commonly used technology in web services for enabling service providers and consumers to exchange data. XML is also widely used to store data and ... [more ▼]

Nowadays, the External Markup Language (XML) is the most commonly used technology in web services for enabling service providers and consumers to exchange data. XML is also widely used to store data and configuration files that control the operation of software systems. Nevertheless, XML suffers from several well-known vulnerabilities such as XML Injections (XMLi). Any exploitation of these vulnerabilities might cause serious and undesirable consequences, e.g., denial of service and accessing or modifying highly-confidential data. Fuzz testing techniques have been investigated in the literature to detect XMLi vulnerabilities. However, their success rate tends to be very low since they cannot generate complex test inputs required for the detection of these vulnerabilities. Furthermore, these approaches are not effective for real-world complex XML-based enterprise systems, which are composed of several components including front-end web applications, XML gateway/firewall, and back-end web services. In this dissertation, we propose several automated security testing strategies for detecting XML-based vulnerabilities. In particular, we tackle the challenges of security testing in an industrial context. Our proposed strategies, target various and complementary aspects of security testing for XML-based systems, e.g., test case generation for XML gateway/firewall. The development and evaluation of these strategies have been done in close collaboration with a leading financial service provider in Luxembourg/Switzerland, namely SIX Payment Services (formerly known as CETREL S.A.). SIX Payment Services processes several thousand financial transactions daily, providing a range of financial services, e.g., online payments, issuing of credit and debit cards. The main research contributions of this dissertation are: -A large-scale and systematic experimental assessment for detecting vulnerabilities in numerous widely-used XML parsers and the underlying systems using them. In particular, we targeted two common XML parser’s vulnerabilities: (i) XML Billion Laughs (BIL), and (ii) XML External Entities (XXE). - A novel automated testing approach, that is based on constraint-solving and input mutation techniques, to detect XMLi vulnerabilities in XML gateway/firewall and back-end web services. - A black-box search-based testing approach to detect XMLi vulnerabilities in front-end web applications. Genetic algorithms are used to search for inputs that can manipulate the application to generate malicious XML messages. - An in-depth analysis of various search algorithms and fitness functions, to improve the search-based testing approach for front-end web applications. - Extensive evaluations of our proposed testing strategies on numerous real-world industrial web services, XML gateway/firewall, and web applications as well as several open-source systems. [less ▲]

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See detailComparative Genomic Analysis of the Human Gut Microbiome Reveals a Broad Distribution of Metabolic Pathways for the Degradation of Host-Synthetized Mucin Glycans and Utilization of Mucin-Derived Monosaccharides
Ravcheev, Dmitry UL; Thiele, Ines UL

in Frontiers in Genetics (2017), 8

The colonic mucus layer is a dynamic and complex structure formed by secreted and transmembrane mucins, which are high-molecular-weight and heavily glycosylated proteins. Colonic mucus consists of a loose ... [more ▼]

The colonic mucus layer is a dynamic and complex structure formed by secreted and transmembrane mucins, which are high-molecular-weight and heavily glycosylated proteins. Colonic mucus consists of a loose outer layer and a dense epithelium-attached layer. The outer layer is inhabited by various representatives of the human gut microbiota (HGM). Glycans of the colonic mucus can be used by the HGM as a source of carbon and energy when dietary fibers are not sufficiently available. Both commensals and pathogens can utilize mucin glycans. Commensals are mostly involved in the cleavage of glycans, while pathogens mostly utilize monosaccharides released by commensals. This HGM-derived degradation of the mucus layer increases pathogen susceptibility and causes many other health disorders. Here, we analyzed 397 individual HGM genomes to identify pathways for the cleavage of host-synthetized mucin glycans to monosaccharides as well as for the catabolism of the derived monosaccharides. Our key results are as follows: (i) Genes for the cleavage of mucin glycans were found in 86% of the analyzed genomes, which significantly higher than a previous estimation. (ii) Genes for the catabolism of derived monosaccharides were found in 89% of the analyzed genomes. (iii) Comparative genomic analysis identified four alternative forms of the monosaccharide-catabolizing enzymes and four alternative forms of monosaccharide transporters. (iv) Eighty-five percent of the analyzed genomes may be involved in potential feeding pathways for the monosaccharides derived from cleaved mucin glycans. (v) The analyzed genomes demonstrated different abilities to degrade known mucin glycans. Generally, the ability to degrade at least one type of mucin glycan was predicted for 81% of the analyzed genomes. (vi) Eighty-two percent of the analyzed genomes can form mutualistic pairs that are able to degrade mucin glycans and are not degradable by any of the paired organisms alone. Taken together, these findings provide further insight into the inter-microbial communications of the HGM as well as into host-HGM interactions. [less ▲]

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See detailEuropean Unemployment Insurance – a good initiative missing proper foundation
Tkalec, Igor UL

Article for general public (2017)

The European Unemployment Insurance is a reawakened EU initiative imagined to function as a supranational coordination and stabilization mechanism. While its purpose is justified and its design viable, a ... [more ▼]

The European Unemployment Insurance is a reawakened EU initiative imagined to function as a supranational coordination and stabilization mechanism. While its purpose is justified and its design viable, a pre-condition that underpins such a scheme is currently absent. [less ▲]

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See detailDemocratic legitimacy [glossary]
Chiocchetti, Paolo UL

E-print/Working paper (2017)

A political institution is legitimate when it succeeds in persuading people of the normative necessity of its existence. In a democratic system, this can be based both on various forms of popular consent ... [more ▼]

A political institution is legitimate when it succeeds in persuading people of the normative necessity of its existence. In a democratic system, this can be based both on various forms of popular consent (democratic legitimacy) and on other kinds of foundations (generic legitimacy). With reference to the European Union, debates have focused on empirical support for the EU, the nature of its "democratic deficit", and the potential conflict between European integration and national democratic sovereignty. [less ▲]

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