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See detailBeware: Nobody Wants to Be Lonely
Tkalec, Igor UL

Article for general public (2018)

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See detailSteuerrecht und Daten - Die virtuelle Betriebsstätte
Sinnig, Julia UL

Presentation (2018, January 12)

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See detailAttacks and Countermeasures for White-box Designs
Biryukov, Alex UL; Udovenko, Aleksei UL

E-print/Working paper (2018)

In the traditional symmetric cryptography, the adversary has access only to the inputs and outputs of a cryptographic primitive. In the white-box model the adversary is given full access to the ... [more ▼]

In the traditional symmetric cryptography, the adversary has access only to the inputs and outputs of a cryptographic primitive. In the white-box model the adversary is given full access to the implementation. He can use both static and dynamic analysis as well as fault analysis in order to break the cryptosystem, e.g. to extract embedded secret key. Implementations secure in such model have many applications in industry. However, creating such implementations turns out to be a very challenging if not an impossible task. Recently, Bos et al. proposed a generic attack on white-box primitives called differential computation analysis (DCA). This attack applies to most existent white-box implementations both from academia and industry. The attack comes from side-channel cryptanalysis method. The most common method protecting against such side-channel attacks is masking. Therefore, masking can be used in white-box implementations to protect against the DCA attack. In this paper we investigate this possibility and present multiple generic attacks against masked white-box implementations. We use the term “masking” in a very broad sense. As a result, we deduce new constraints that any secure white-box implementation must satisfy. We suggest partial countermeasures against the attacks. Some of our attacks were successfully applied to the WhibOx 2017 challenges. [less ▲]

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See detailSurmonter les barrières linguistiques avec « MaGrid » - un outil de formation de pré-mathématiques pour un contexte scolaire multilingue
Cornu, Véronique UL; Pazouki, Tahereh UL; Schiltz, Christine UL et al

Scientific Conference (2018, January 11)

Le contexte scolaire luxembourgeois est caractérisé par le multilinguisme et une population scolaire hétérogène, ce qui nécessite la mise en place de pratiques pédagogiques qui prennent en compte ... [more ▼]

Le contexte scolaire luxembourgeois est caractérisé par le multilinguisme et une population scolaire hétérogène, ce qui nécessite la mise en place de pratiques pédagogiques qui prennent en compte l’hétérogénéité des élèves. Dans le domaine des mathématiques, qui semble être non-verbal à première vue, des résultats scientifiques montrent que les enfants dont la langue maternelle est différente de la langue d’instruction, atteignent sur des tests d’aptitudes pré-mathématiques des résultats significativement inférieurs à ceux de leurs camarades natifs. Ceci est d’autant plus inquiétant, sachant que ces aptitudes pré-mathématiques sont prédictives des apprentissages ultérieurs. Par conséquent, nous avons développé l’outil de formation de pré-mathématiques non-verbale « MaGrid ». « MaGrid » permet à chaque enfant de bénéficier pleinement d’une instruction préscolaire en mathématiques, indépendamment de ses compétences langagières. Cet outil se caractérise par sa nature visuelle et il est implémenté sur tablette tactile. Jusqu’à présent, nous avons implémenté et évalué « MaGrid » lors de deux études scientifiques. Les résultats quantitatifs des évaluations empiriques sont prometteurs, comme ils montrent des effets positifs sur les habilités entraînées chez les enfants ayant utilisé cet outil comparé à un groupe contrôle. Dans une première étude, l’outil a été utilisé auprès de cinq classes durant 10 semaines, comprenant deux séances de 20 minutes par semaine. Les résultats lors de petites épreuves spécifiques ont été comparés aux résultats d’élèves de cinq classes n’ayant pas d’entraînement spécifique, et des effets d’intervention ont été observés. Dans une deuxième étude, nous nous sommes focalisés sur un groupe d’enfants de langue minoritaire (le portugais). « MaGrid » a été utilisé lors d’un programme d’intervention de pré-mathématiques s’étendant sur les deux années scolaires de l’école préscolaire. Les analyses préliminaires ont abouti à des résultats positifs. Des effets bénéfiques se sont manifestés sur différentes mesures de pré-mathématiques chez les enfants ayant suivi notre programme par rapport aux enfants du groupe contrôle. [less ▲]

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See detailTransforming Time Series for Efficient and Accurate Classification
Li, Daoyuan UL

Doctoral thesis (2018)

Time series data refer to sequences of data that are ordered either temporally, spatially or in another defined order. They can be frequently found in a variety of domains, including financial data ... [more ▼]

Time series data refer to sequences of data that are ordered either temporally, spatially or in another defined order. They can be frequently found in a variety of domains, including financial data analysis, medical and health monitoring and industrial automation applications. Due to their abundance and wide application scenarios, there has been an increasing need for efficient machine learning algorithms to extract information and build knowledge from these data. One of the major tasks in time series mining is time series classification (TSC), which consists of applying a learning algorithm on labeled data to train a model that will then be used to predict the classes of samples from an unlabeled data set. Due to the sequential characteristic of time series data, state-of-the-art classification algorithms (such as SVM and Random Forest) that performs well for generic data are usually not suitable for TSC. In order to improve the performance of TSC tasks, this dissertation proposes different methods to transform time series data for a better feature extraction process as well as novel algorithms to achieve better classification performance in terms of computation efficiency and classification accuracy. In the first part of this dissertation, we conduct a large scale empirical study that takes advantage of discrete wavelet transform (DWT) for time series dimensionality reduction. We first transform real-valued time series data using different families of DWT. Then we apply dynamic time warping (DTW)-based 1NN classification on 39 datasets and find out that existing DWT-based lossy compression approaches can help to overcome the challenges of storage and computation time. Furthermore, we provide assurances to practitioners by empirically showing, with various datasets and with several DWT approaches, that TSC algorithms yield similar accuracy on both compressed (i.e., approximated) and raw time series data. We also show that, in some datasets, wavelets may actually help in reducing noisy variations which deteriorate the performance of TSC tasks. In a few cases, we note that the residual details/noises from compression are more useful for recognizing data patterns. In the second part, we propose a language model-based approach for TSC named Domain Series Corpus (DSCo), in order to take advantage of mature techniques from both time series mining and Natural Language Processing (NLP) communities. After transforming real-valued time series into texts using Symbolic Aggregate approXimation (SAX), we build per-class language models (unigrams and bigrams) from these symbolized text corpora. To classify unlabeled samples, we compute the fitness of each symbolized sample against all per-class models and choose the class represented by the model with the best fitness score. Through extensive experiments on an open dataset archive, we demonstrate that DSCo performs similarly to approaches working with original uncompressed numeric data. We further propose DSCo-NG to improve the computation efficiency and classification accuracy of DSCo. In contrast to DSCo where we try to find the best way to recursively segment time series, DSCo-NG breaks time series into smaller segments of the same size, this simplification also leads to simplified language model inference in the training phase and slightly higher classification accuracy. The third part of this dissertation presents a multiscale visibility graph representation for time series as well as feature extraction methods for TSC, so that both global and local features are fully extracted from time series data. Unlike traditional TSC approaches that seek to find global similarities in time series databases (e.g., 1NN-DTW) or methods specializing in locating local patterns/subsequences (e.g., shapelets), we extract solely statistical features from graphs that are generated from time series. Specifically, we augment time series by means of their multiscale approximations, which are further transformed into a set of visibility graphs. After extracting probability distributions of small motifs, density, assortativity, etc., these features are used for building highly accurate classification models using generic classifiers (e.g., Support Vector Machine and eXtreme Gradient Boosting). Based on extensive experiments on a large number of open datasets and comparison with five state-of-the-art TSC algorithms, our approach is shown to be both accurate and efficient: it is more accurate than Learning Shapelets and at the same time faster than Fast Shapelets. Finally, we list a few industrial applications that relevant to our research work, including Non-Intrusive Load Monitoring as well as anomaly detection and visualization by means for hierarchical clustering for time series data. In summary, this dissertation explores different possibilities to improve the efficiency and accuracy of TSC algorithms. To that end, we employ a range of techniques including wavelet transforms, symbolic approximations, language models and graph mining algorithms. We experiment and evaluate our approaches using publicly available time series datasets. Comparison with the state-of-the-art shows that the approaches developed in this dissertation perform well, and contribute to advance the field of TSC. [less ▲]

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See detailHistoriker und die Konstruktion von Zeitgenossenschaft. Eine Projektskizze am Beispiel der Militärverwaltung Belgien-Nordfrankreich im Zweiten Weltkrieg
Brüll, Christoph UL

Presentation (2018, January 09)

Gegenstand des Projekts ist die Konstruktion des Zeitzeugendiskurses mehrerer führender Mitglieder der deutschen Militärverwaltung in Brüssel. Arbeitshypothese ist, dass die Konstruktion in drei Phasen ... [more ▼]

Gegenstand des Projekts ist die Konstruktion des Zeitzeugendiskurses mehrerer führender Mitglieder der deutschen Militärverwaltung in Brüssel. Arbeitshypothese ist, dass die Konstruktion in drei Phasen verlief: Der „Generalprozess“ (1950-1951) gegen Alexander von Falkenhausen und Eggert Reeder (gefolgt von einer Reihe anderer Prozesse bis in die 1980er Jahre hinein). Die Legitimierungs- und Verteidigungsdiskurse einiger Akteure gegenüber Anschuldigungen, die ihre Tätigkeiten während des Krieges betrafen. Ihre Tätigkeit als Zeitzeuge für belgische und deutsche Historiker und Journalisten seit den 1970er Jahren. [less ▲]

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See detailProceedings - 2017 ILILAS Distinguished Lectures
Bouvry, Pascal UL; Bisdorff, Raymond; Schommer, Christoph UL et al

Report (2018)

The Proceedings summarizes the 12 lectures that have taken place within the ILIAS Dinstguished Lecture series 2017. It contains a brief abstract of the talks as well as some additional information about ... [more ▼]

The Proceedings summarizes the 12 lectures that have taken place within the ILIAS Dinstguished Lecture series 2017. It contains a brief abstract of the talks as well as some additional information about each speaker. [less ▲]

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See detailBrexit Seen from Luxembourg
Högenauer, Anna-Lena UL

E-print/Working paper (2018)

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See detailThe Temporary Reintroduction of Border Controls Inside the Schengen Area: Towards a Spatial Perspective
Evrard, Estelle UL; Nienaber, Birte UL; Sommarribas, Adolfo UL

in Journal of Borderlands Studies (2018)

Following the terrorist attacks in Paris (November 2015) and Brussels (March 2016), several EU Member States have decided to re-establish border controls or to build walls inside the Schengen Area ... [more ▼]

Following the terrorist attacks in Paris (November 2015) and Brussels (March 2016), several EU Member States have decided to re-establish border controls or to build walls inside the Schengen Area. Although these decisions are temporary and legally framed by the Schengen code, their extent disrupts the free movement within the Schengen Area, in particular in border areas. While lawyers and economists have analyzed the impacts of this situation, the spatial perspective has remained rather neglected. This exploratory contribution aims to address this gap in the literature by outlining the spatial significance of reintroduced controls for border areas inside the Schengen Area. This contribution firstly undertakes a literature review of the different conceptual tools at hand. These are then compared with a set of exploratory empirical materials. The article focuses more precisely on the Greater Region where France and Germany have reintroduced border controls, thus disrupting in particular daily cross-border flows with Luxembourg and Belgium. The analysis demonstrates that the border acts as a filter, disrupting cross-border flows and cooperation. Also, it sheds some light on the important role played by the ideational perception of the border for practitioners and decision-makers. This contribution concludes by suggesting several paths for a future research agenda. [less ▲]

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See detailImpact of the height imperfections of masonry blocks on the load bearing capacity of dry-stack masonry walls
Chewe Ngapeya, Gelen Gael UL; Waldmann, Danièle UL; Scholzen, Frank UL

in in press ELSEVIER Construction and Building Materials (TOP10 journal) (2018)

Dry-stacked masonry walls gives rise to geometric imperfections: the height variation of different masonry blocks ΔH and the roughness of the support area Δh. This paper studies the effect of ΔH on the ... [more ▼]

Dry-stacked masonry walls gives rise to geometric imperfections: the height variation of different masonry blocks ΔH and the roughness of the support area Δh. This paper studies the effect of ΔH on the structural response and the load bearing capacity of masonry walls by highlighting the load percolation. Furthermore, an algorithm was developed to define a stress multiplier coefficient respecting the imperfections ΔH. The algorithm allowed predicting 77% of the amplified stress compared to the FE analysis and showed that the geometric imperfections govern the load percolation in a wall as well as the cracking mode and the bearing capacity. [less ▲]

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See detailGeschwindigkeitskontrollen im Strassenverkehr - eine wirksame repressive Methode?
Steffgen, Georges UL

Article for general public (2018)

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See detailAlonso and the scaling of urban profiles
Delloye, Justin; Lemoy, Rémi UL; Caruso, Geoffrey UL

E-print/Working paper (2018)

Urban characteristics scaling with total population has become an important urban research field since one needs to better understand the benefits and disadvantages of urban growth and fur- ther ... [more ▼]

Urban characteristics scaling with total population has become an important urban research field since one needs to better understand the benefits and disadvantages of urban growth and fur- ther population concentration. Urban scaling research, however, is largely disconnected from the empirics and theory of intra-urban structure for it considers averaged attributes and ignores resi- dential choice trade-offs between transport and housing costs within cities. Using this fundamental trade-off, the monocentric model of Alonso provides theory to urban density profiles. However, it is silent about how these profiles scale with population, thus preventing empirical scaling studies to anchor in a strong micro-economic theory. This paper fixes this gap by introducing power laws for land and for population density in the Alonso model. From an augmented model with land use, we derive the conditions at which equilibrium profiles match recent empirical findings about the scaling of urban land and population density profiles in European cities. We find that the Alonso model is theoretically compatible with the observed scaling of population density profiles and leads to a satisfactory representation of European cities. The conditions for this compatibility refine current understanding of wage and transport costs elasticities with population. Although they require a scaling power of the profile of the share of urbanised land that is different from what is observed, it is argued that alternatives specifications of transport cost functions could solve this issue. Thus our results call for revisiting theories about land development and housing processes as well as the empirics of agglomeration benefits and transport costs. [less ▲]

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See detailDevelopment of a test track for driverless cars: vehicle design, track configuration, and liability considerations
Szalay, Zsolt; Tettamanti, Tamás; Esztergár-Kiss, Domokos et al

in Periodica Polytechnica Transportation Engineering (2018), 46(1), 29-35

The Research Center for Autonomous Road Vehicles (RECAR) was founded in 2015 upon the initiative of the Faculty of Transportation Engineering and Vehicle Engineering of Budapest University of Technology ... [more ▼]

The Research Center for Autonomous Road Vehicles (RECAR) was founded in 2015 upon the initiative of the Faculty of Transportation Engineering and Vehicle Engineering of Budapest University of Technology and Economics. The research center is supported by industrial partners and other academic partners targeting research and educational purposes. In complement to this project, the construction of a new automotive test track is also under development especially for autonomous road vehicle testing serving as automotive proving ground in Zalaegerszeg, Hungary. Accordingly, an intensive research has been started in RECAR center in the field of autonomous vehicle technology. The paper’s goal is to share the main practical and methodological experiences with the scientific audience as well as the industrial sector. Based on the initial research actions we intend to enlighten the upcoming research challenges of driverless vehicles and automated intelligent transport system. Basically, three main topics are concerned. Firstly, the main issues concerning autonomous vehicle research are summarized. Secondly, the requirements for autonomous test track design are concluded. Thirdly, the legal questions that emerge with the appearance of driverless vehicles are investigated, especially concerning liability. [less ▲]

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See detailProperty and the Cloud
Bartolini, Cesare UL; Santos, Cristiana; Ullrich, Carsten UL

in Computer Law Security Review (2018)

Data is a modern form of wealth in the digital world, and massive amounts of data circulate in cloud environments. While this enormously facilitates the sharing of information, both for personal and ... [more ▼]

Data is a modern form of wealth in the digital world, and massive amounts of data circulate in cloud environments. While this enormously facilitates the sharing of information, both for personal and professional purposes, it also introduces some critical problems concerning the ownership of the information. Data is an intangible good that is stored in large data warehouses, where the hardware architectures and software programs running the cloud services coexist with the data of many users. This context calls for a twofold protection: on one side, the cloud is made up of hardware and software that constitute the business assets of the service provider (property of the cloud); on the other side, there is a definite need to ensure that users retain control over their data (property in the cloud). The law grants protection to both sides under several perspectives, but the result is a complex mix of interwoven regimes, further complicated by the intrinsically international nature of cloud computing that clashes with the typical diversity of national laws. As the business model based on cloud computing grows, public bodies, and in particular the European Union, are striving to find solutions to properly regulate the future economy, either by introducing new laws, or by finding the best ways to apply existing principles. [less ▲]

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See detailKinder in Deutschland 2018. 4. World Vision Kinderstudie
World Vision Deutschland e.V.; Andresen, Sabine; Neumann, Sascha UL et al

Book published by Beltz (2018)

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See detailCognitive pitfalls in dealing with sustainability
Sonnleitner, Philipp UL

in König, Ariane (Ed.) Sustainability science: Key issues (2018)

Main summary points: • Environmental conditions in which human ancestors evolved, strongly shaped human thinking • Two complementary cognitive systems can be distinguished whose interplay causes ... [more ▼]

Main summary points: • Environmental conditions in which human ancestors evolved, strongly shaped human thinking • Two complementary cognitive systems can be distinguished whose interplay causes systematic errors, especially in situations including uncertainty or complexity • These cognitive pitfalls have tremendous consequences in the context of sustainability • Leveraging cognitive biases and knowledge about them by improving education and training is vital to address ecological problems [less ▲]

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See detailInput and Output Additionality of R&D Subsidies
Czarnitzki, Dirk; Hussinger, Katrin UL

in Applied Economics (2018), 50(12), 1324-1341

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See detailAutomated Generation of Constraints from Use Case Specifications to Support System Testing
Wang, Chunhui UL; Pastore, Fabrizio UL; Briand, Lionel UL

in Proceedings of the 11th IEEE Conference on Software Testing, Validation and Verification (2018)

System testing plays a crucial role in safety-critical domains, e.g., automotive, where system test cases are used to demonstrate the compliance of software with its functional and safety requirements ... [more ▼]

System testing plays a crucial role in safety-critical domains, e.g., automotive, where system test cases are used to demonstrate the compliance of software with its functional and safety requirements. Unfortunately, since requirements are typically written in natural language, significant engineering effort is required to derive test cases from requirements. In such a context, automated support for generating system test cases from requirements specifications written in natural language would be highly beneficial. Unfortunately, existing approaches have limited applicability. For example, some of them require that software engineers provide formal specifications that capture some of the software behavior described using natural language. The effort needed to define such specifications is usually a significant deterrent for software developers. This paper proposes an approach, OCLgen, which largely automates the generation of the additional formal specifications required by an existing test generation approach named UMTG. More specifically, OCLgen relies on semantic analysis techniques to automatically derive the pre- and post-conditions of the activities described in use case specifications. The generated conditions are used by UMTG to identify the test inputs that cover all the use case scenarios described in use case specifications. In practice, the proposed approach enables the automated generation of test cases from use case specifications while avoiding most of the additional modeling effort required by UMTG. Results from an industrial case study show that the approach can automatically and correctly generate more than 75% of the pre- and post-conditions characterizing the activities described in use case specifications. [less ▲]

Detailed reference viewed: 68 (8 UL)