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See detailMachine Learning-based Methods for Driver Identification and Behavior Assessment: Applications for CAN and Floating Car Data
Jafarnejad, Sasan UL

Doctoral thesis (2020)

The exponential growth of car generated data, the increased connectivity, and the advances in artificial intelligence (AI), enable novel mobility applications. This dissertation focuses on two use-cases ... [more ▼]

The exponential growth of car generated data, the increased connectivity, and the advances in artificial intelligence (AI), enable novel mobility applications. This dissertation focuses on two use-cases of driving data, namely distraction detection and driver identification (ID). Low and medium-income countries account for 93% of traffic deaths; moreover, a major contributing factor to road crashes is distracted driving. Motivated by this, the first part of this thesis explores the possibility of an easy-to-deploy solution to distracted driving detection. Most of the related work uses sophisticated sensors or cameras, which raises privacy concerns and increases the cost. Therefore a machine learning (ML) approach is proposed that only uses signals from the CAN-bus and the inertial measurement unit (IMU). It is then evaluated against a hand-annotated dataset of 13 drivers and delivers reasonable accuracy. This approach is limited in detecting short-term distractions but demonstrates that a viable solution is possible. In the second part, the focus is on the effective identification of drivers using their driving behavior. The aim is to address the shortcomings of the state-of-the-art methods. First, a driver ID mechanism based on discriminative classifiers is used to find a set of suitable signals and features. It uses five signals from the CAN-bus, with hand-engineered features, which is an improvement from current state-of-the-art that mainly focused on external sensors. The second approach is based on Gaussian mixture models (GMMs), although it uses two signals and fewer features, it shows improved accuracy. In this system, the enrollment of a new driver does not require retraining of the models, which was a limitation in the previous approach. In order to reduce the amount of training data a Triplet network is used to train a deep neural network (DNN) that learns to discriminate drivers. The training of the DNN does not require any driving data from the target set of drivers. The DNN encodes pieces of driving data to an embedding space so that in this space examples of the same driver will appear closer to each other and far from examples of other drivers. This technique reduces the amount of data needed for accurate prediction to under a minute of driving data. These three solutions are validated against a real-world dataset of 57 drivers. Lastly, the possibility of a driver ID system is explored that only uses floating car data (FCD), in particular, GPS data from smartphones. A DNN architecture is then designed that encodes the routes, origin, and destination coordinates as well as various other features computed based on contextual information. The proposed model is then evaluated against a dataset of 678 drivers and shows high accuracy. In a nutshell, this work demonstrates that proper driver ID is achievable. The constraints imposed by the use-case and data availability negatively affect the performance; in such cases, the efficient use of the available data is crucial. [less ▲]

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See detailThe ALMA-Yactul Ecosystem: A Holistic Approach for Student-centered Integration of Learning Material
Grevisse, Christian UL

Doctoral thesis (2020)

Digital learning resources play a key role in technology enhanced learning, yet their organization poses a challenge to both learners and teachers. Students are confronted with an ever-growing amount of ... [more ▼]

Digital learning resources play a key role in technology enhanced learning, yet their organization poses a challenge to both learners and teachers. Students are confronted with an ever-growing amount of available resources in an open, heterogeneous corpus. Finding relevant learning material for a given context or task, such as an exercise, is non-trivial, especially for novices in a complex domain, who often lack specific search skills. In addition, there is often no direct link between the learning material and the task at hand, and the constant interruption of the task in order to search for resources may have an impact on the cognitive load. Moreover, from the perspective of teachers and instructional designers, authoring high-quality learning material is a time-intensive task. Hence, reusing the authored material in multiple contexts would be beneficial. This dissertation addresses these issues by proposing the ALMA-Yactul ecosystem, a holistic approach for student-centered integration of learning material. Learners can benefit from scaffolding support to retrieve learning material relevant to their current context at a fine-grained level and across the boundaries of individual courses. This integration is showcased in multiple applications and domains, such as a plugin for an Integrated Development Environment or an enhanced sketchnoting app. While the former provides novices in computer programming the necessary tools to scaffold the search for heterogeneous documents on fine-grained syntactical elements, the latter allows for suggesting further information while taking notes in class. In both cases, it is not necessary for learners to leave their current study environment. To implicitly link learning resources and tasks, Semantic Web technologies such as ontologies are used to annotate documents. For this purpose, an extensible and lightweight modular domain ontology for programming languages has been created. While the main study domain in this work is computer science with a special focus on programming, the transferability of the proposed approach to other domains is demonstrated through multiple examples. Furthermore, to foster the active engagement of students in the learning process, Yactul, a game-based platform for continuous active learning has been developed. Apart from its use in the classroom, the platform also provides formative assessment to the individual learner by keeping track of her performance on a per-concept basis. Yactul activities are a key element in the ecosystem, both benefitting from and contributing to the integration of learning material. Finally, teachers are assisted in semantically enhancing their resources through semi-automatic annotation support within popular authoring tools. A Knowledge Graph-based approach is employed for core concept identification. Apart from analysing the usage of this ecosystem and evaluating the user satisfaction in university courses, an experiment with high school pupils lacking prior knowledge in programming yielded positive results with respect to the proposed scaffolding support. [less ▲]

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See detailThe Schwarz-Voronov embedding of Z_2^n - manifolds
Bruce, Andrew UL; Ibarguengoytia, Eduardo UL; Poncin, Norbert UL

in Symmetry, Integrability and Geometry: Methods and Applications (2020), 16(002), 47

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See detailPrevention of Electrostatic Charge Generation in Filtration of Low-Conductivity Oils by Surface Modification of Modern Filter Media
Staudt, Johannes; Duchowski, Johan; Leyer, Stephan UL

in Tribology Transactions (2020)

The electrostatic charging behavior of filter elements operating in various hydraulic and lubricating fluids has been re-examined from the perspective of fundamental material properties of the two ... [more ▼]

The electrostatic charging behavior of filter elements operating in various hydraulic and lubricating fluids has been re-examined from the perspective of fundamental material properties of the two materials participating in the event. In contrast to the previously proposed mechanisms that focused predominantly on fluid and material conductivities, new evidence strongly suggests that the relative placement of the substrates in the triboelectric series must be taken into account. The positions occupied in the triboelectric series account for the donor/acceptor tendencies exhibited by the materials when brought close together in close proximity ( 10 nm). Nevertheless, this behavior is only an outward manifestation of the deeper underlying characteristics that include material surface energies and, looking even deeper, the associated electron work functions of the interacting materials. Herein we provide several examples of the enhanced understanding of the electrostatic charging/discharging (ESC/ESD) phenomena as they occur in the course of filtration of hydraulic and lubricating fluids through modern filter elements constructed of synthetic glass fiber and polymer materials. [less ▲]

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See detailPunched Cards in Accounting at Helena Rubinstein
van Herck, Sytze UL

Presentation (2020, January 08)

Placing the design and use of computing devices into a broader context, I focus on the societal, business, and labour developments at the basis of new computer models. One of five carefully selected case ... [more ▼]

Placing the design and use of computing devices into a broader context, I focus on the societal, business, and labour developments at the basis of new computer models. One of five carefully selected case studies considers the use of Powers-Samas and later I.C.T. punched card equipment in accounting at the Helena Rubinstein make-up concern in London during the 1950s. For each case my research looks into changes in occupations after the introduction of new computer models, as well as its influence on the work space and workflow of employees. Finally, I study gender stereotypes in advertisements of the computers, and in this case of the punched card equipment. During the Work in Progress session I will briefly introduce my overall research approach and demonstrate which sources are available, and what is still missing for the punched card equipment case study. [less ▲]

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See detailThe authority of science and the legitimacy of international organisations: OECD, UNESCO andWorld Bank in global education governance
Zapp, Mike UL

in Compare: A Journal of Comparative Education (2020)

International organisations’ (IOs) legitimacy in global educational governance is commonly seen as a function of their regulative or normative power. By contrast, this paper stresses the increasing ... [more ▼]

International organisations’ (IOs) legitimacy in global educational governance is commonly seen as a function of their regulative or normative power. By contrast, this paper stresses the increasing importance of scientific research and policy-relevant knowledge and its strategic production, dissemination and transfer by IOs. The article examines knowledge work at OECD, UNESCO and World Bank based on novel data from publication analyses, archival work and a number of interviews. Drawing on sociological institutionalism and constructivist international relations scholarship, this study is interested in the rationales, resources and capacities for knowledge production, the strategies of dissemination and transfer as well as the implications of science production for IOs’ position and relevance in global governance. Findings emphasise the authority of science as the primary source of legitimacy – and even survival – in an increasingly crowded and competitive field of global education governance. [less ▲]

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See detailBlockPGP: A Blockchain-based Framework for PGP Key Servers
Yakubov, Alexander UL; Shbair, Wazen UL; Khan, Nida UL et al

in International Journal of Networking and Computing (2020), 10(1), 1-24

Pretty Good Privacy (PGP) is one of the most prominent cryptographic standards offering end-to-end encryption for email messages and other sensitive information exchange. PGP allows to verify the identity ... [more ▼]

Pretty Good Privacy (PGP) is one of the most prominent cryptographic standards offering end-to-end encryption for email messages and other sensitive information exchange. PGP allows to verify the identity of the correspondent in information exchange as well as the information integrity. PGP implements asymmetric encryption with certificates shared through a network of PGP key servers. In this paper, we propose a new PGP management framework with the key servers infrastructure implemented using blockchain technology. Our approach offers fast propagation of certificate revocation among PGP key servers and elimination of man-in-the-middle risks. It also grants users the required access control to update their own PGP certificates, which is not the case with the current PGP key servers. A prototype has been implemented using Ethereum blockchain and an open source key server, named Hockeypuck. Finally, we evaluated the prototype with extensive experiments. Our results show that our solution is practical and it could be integrated with the existing public PGP key servers infrastructure. [less ▲]

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See detailCognitive Factors associated to Gaming Disorders
Billieux, Joël; Potenza, Marc; Maurage, Pierre et al

in Verdejo-Garcia, Antonio (Ed.) Cognition and addiction: A Researcher’s Guide From Mechanisms Towards Interventions (2020)

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See detailA newform theory for Katz modular forms
Berhanu, Daniel UL

E-print/Working paper (2020)

In this paper, a strong multiplicity one theorem for Katz modular forms is studied. We show that a cuspidal Katz eigenform which admits an irreducible Galois representation is in the level and weight old ... [more ▼]

In this paper, a strong multiplicity one theorem for Katz modular forms is studied. We show that a cuspidal Katz eigenform which admits an irreducible Galois representation is in the level and weight old space of a uniquely associated Katz newform. We also set up multiplicity one results for Katz eigenforms which have reducible Galois representation. [less ▲]

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See detailDie Landwirtschaft in der Provinz Gallia Narbonensis und die Frage nach dem Sozialstatus der Arbeitskräfte
Groff, Thierry UL

in Frankfurter elektronische Rundschau zur Altertumskunde (2020), 39(2019), 1-12

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See detailMagnetic Guinier law
Michels, Andreas UL; Malyeyev, Artem UL; Titov, Ivan UL et al

in IUCrJ (2020), 7

Small-angle scattering of x-rays and neutrons is a routine method for the determination of nanoparticle sizes. The so-called Guinier law represents the low-q approximation for the small-angle scattering ... [more ▼]

Small-angle scattering of x-rays and neutrons is a routine method for the determination of nanoparticle sizes. The so-called Guinier law represents the low-q approximation for the small-angle scattering curve from an assembly of particles. The Guinier law has originally been derived for nonmagnetic particle-matrix-type systems, and it is successfully employed for the estimation of particle sizes in various scientific domains (e.g., soft matter physics, biology, colloidal chemistry, materials science). An important prerequisite for it to apply is the presence of a discontinuous interface separating particles and matrix. Here, we introduce the Guinier law for the case of magnetic small-angle neutron scattering (SANS) and experimentally demonstrate its applicability for the example of nanocrystalline cobalt. It is well- known that the magnetic microstructure of nanocrystalline ferromagnets is highly nonuniform on the nanometer length scale and characterized by a spectrum of continuously varying long-wavelength magnetization fluctuations, i.e., these systems do not manifest sharp interfaces in their magnetization profile. The magnetic Guinier radius depends on the applied magnetic field, on the magnetic interactions (exchange, magnetostatics), and on the magnetic anisotropy-field radius, which characterizes the size over which the magnetic anisotropy field is coherently aligned into the same direction. In contrast to the nonmagnetic conventional Guinier law, the magnetic version can be applied to fully dense random-anisotropy-type ferromagnets. [less ▲]

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See detailHybrid Analog-Digital Transceiver Designs for Multi-User MIMO mmWave Cognitive Radio Systems
Tsinos, Christos UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in IEEE Transactions on Cognitive Communications and Networking (2020)

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See detailSuicide Prevention: Using the Number of Health Complaints as an Indirect Alternative for Screening Suicidal Adolescents
Heinz, Andreas UL; Catunda, Carolina UL; van Duin, Claire UL et al

in Journal of Affective Disorders (2020), 260

Background: Suicide is the second leading cause of death in adolescents. Screening for persons at risk usually includes asking about suicidal ideation, which is considered inappropriate in some societies ... [more ▼]

Background: Suicide is the second leading cause of death in adolescents. Screening for persons at risk usually includes asking about suicidal ideation, which is considered inappropriate in some societies and situations. To avoid directly addressing suicide, this paper investigates whether the Health Behaviour in School-aged Children Symptom Checklist (HBSC-SCL), a validated non-clinical measure of eight subjective health complaints (e.g. headache, feeling low), could be used as a tool for screening suicidal ideation and behavior in adolescents. Methods: 5262 secondary school students aged 12-18 answered the Luxembourgish HBSC 2014 survey, including the HBSC-SCL items and suicidal ideation and behavior questions. Results: Each HBSC-SCL item correlates with suicidal ideation and behavior. A sum score was calculated ranging from zero to eight health complaints to predict respondents who considered suicide (area under the ROC curve = .770). The ideal cut-off for screening students who consider suicide is three or more health complaints: sensitivity is 66.3%, specificity is 75.9% and positive predictive value is 32.9%. Limitations: One limitation is HBSC-SCL's low positive predictive value. This is a general problem of screening rare events: the lower the prevalence, the lower the positive predictive value. Sensitivity and specificity could be improved by taking age-, gender- and country-specific cut-off values, but such refinements would make the score calculation more complicated. Conclusions: The HBSC-SCL is short, easy to use, with satisfactory screening properties. The checklist can be used when suicide cannot be addressed directly, and also in a more general context, e.g. by school nurses when screening adolescents. [less ▲]

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See detailModel Uncertainty and Pricing Performance in Option Valuation
Bams, Dennis; Blanchard, Gildas; Lehnert, Thorsten UL

in The Journal of Derivatives (2020), 27(3), 31-49

The objective of this paper is to evaluate option pricing model performance at the cross sectional level. For this purpose, we propose a statistical framework, in which we in particular account for the ... [more ▼]

The objective of this paper is to evaluate option pricing model performance at the cross sectional level. For this purpose, we propose a statistical framework, in which we in particular account for the uncertainty associated with the reported pricing performance. Instead of a single figure, we determine an entire probability distribution function for the loss function that is used to measure option pricing model performance. This methodology enables us to visualize the effect of parameter uncertainty on the reported pricing performance. Using a data driven approach, we confirm previous evidence that standard volatility models with clustering and leverage effects are sufficient for the option pricing purpose. In addition, we demonstrate that there is short-term persistence but long-term heterogeneity in cross-sectional option pricing information. This finding has two important implications. First, it justifies the practitioner’s routine to refrain from time series approaches, and instead estimate option pricing models on a cross-section by cross-section basis. Second, the long term heterogeneity in option prices pinpoints the importance of measuring, comparing and testing option pricing model for each cross-section separately. To our knowledge no statistical testing framework has been applied to a single cross-section of option prices before. We propose a methodology that addresses this need. The proposed framework can be applied to a broad set of models and data. In the empirical part of the paper, we show by means of example, an application that uses a discrete time volatility model on S&P 500 index options. [less ▲]

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See detailThe politics of bank structural reform: Business power and agenda setting in the United Kingdom, France, and Germany
Howarth, David UL; James, Scott

in Business and Politics (2020), 22(1), 25-51

Following the financial crisis, the United Kingdom introduced major structural reforms to address concern about Too-Big-To-Fail (TBTF) banks, while France and Germany adopted much weaker reforms. This is ... [more ▼]

Following the financial crisis, the United Kingdom introduced major structural reforms to address concern about Too-Big-To-Fail (TBTF) banks, while France and Germany adopted much weaker reforms. This is puzzling given the presence of large universal banks engaged in market making activities in all three countries, which suffered significant losses during the international financial crisis, and given the commitments to reform made by political leaders in all three countries. The paper explains this policy divergence by analysing how dynamics of agenda setting contributed to the emergence of policy windows on structural reform. We explain the United Kingdom's decision to delegate the process to an independent commission as an example of venue shifting which helped to insulate the process from industry framing, and resulted in “conflict expansion” by mobilizing a wider coalition of actors in support of bank ringfencing. By contrast, in France and Germany the agenda was tightly managed through existing institutional venues, enabling industry to resist the framing of the issue around TBTF and limiting the role of non-business groups—a process we label as “conflict contraction.” We argue that analysis of agenda setting dynamics provides new insights into the cross-national variability of business power. [less ▲]

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See detailOptimized Collision Search for STARK-Friendly Hash Challenge Candidates
Udovenko, Aleksei UL

E-print/Working paper (2020)

In this note, we report several solutions to the STARK-Friendly Hash Challenge: a competition with the goal of finding collisions for several hash functions designed specifically for zero-knowledge proofs ... [more ▼]

In this note, we report several solutions to the STARK-Friendly Hash Challenge: a competition with the goal of finding collisions for several hash functions designed specifically for zero-knowledge proofs (ZKP) and multiparty computations (MPC). We managed to find collisions for 3 instances of 91-bit hash functions. The method used is the classic parallel collision search with distinguished points from van Oorshot and Wiener (1994). As this is a general attack on hash functions, it does not exhibit any particular weakness of the chosen hash functions. The crucial part is to optimize the implementations to make the attack cost realistic, and we describe several arithmetic tricks. [less ▲]

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See detailDie Minen und Steinbrüche der Provinz Gallia Narbonensis. Eine Untersuchung zu Abbau, Nutzung und Status der freien und unfreien Arbeitskräfte im römischen Südgallien
Groff, Thierry UL

in Marburger Beitraege zur Antiken Handels-, Wirtschafts- und Sozialgeschichte (2020), 37

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See detailCzechoslovak Jewish emigrants in the clutches of Luxembourg pre-war migration bureaucracy
Bronec, Jakub UL

in Malach Center for Visual History on its 10th Anniversary: Compendium of Papers of the Prague Visual History and Digital Humanities Conference 2020 (2020, January)

My contribution attempts to find answers to the following questions, among others: How did Luxembourg officials deal with Jewish refugees from Eastern European countries? Did the Luxembourgish authorities ... [more ▼]

My contribution attempts to find answers to the following questions, among others: How did Luxembourg officials deal with Jewish refugees from Eastern European countries? Did the Luxembourgish authorities distinguish or give priority to citizens of particular nations? Who was involved in the approval process? Who played the most active role and collected the most controversial information about Jewish immigrants? [less ▲]

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