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See detailFlow characteristics of metallic powder grains for additive manufacturing
Peters, Bernhard UL; Pozzetti, Gabriele UL

in EPJ Web of Conferences (2017), 13001

Directed energy deposition technologies for additive manufacturing such as laser selective melting (SLM) or electron beam melting (EBM) is a fast growing technique mainly due to its flexibility in product ... [more ▼]

Directed energy deposition technologies for additive manufacturing such as laser selective melting (SLM) or electron beam melting (EBM) is a fast growing technique mainly due to its flexibility in product de- sign. However, the process is a complex interaction of multi-physics on multiple length scales that are still not entirely understood. A particular challenging task are the flow characteristics of metallic powder ejected as jets from a nozzle and shielded by an inert turbulent gas flow. Therefore, the objective is to describe numerically the complex interaction between turbulent flow and powder grains. In order to include both several physical processes and length scales an Euler-Lagrange technology is applied. Within this framework powder is treated by the Discrete-Element-Method, while gas flow is described by Euler approaches as found in classical Compu- tational Fluid Dynamics (CFD). The described method succeeded in delivering more accuracy and consistency than a standard approach based on the volume averaging technique and therefore, is suited for the solution of problems within an engineering framework. [less ▲]

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See detailParkinson's disease: Evaluation of a neuroprotective target and identification of candidate biomarker signatures using murine models
Ashrafi, Amer UL

Doctoral thesis (2017)

Parkinson's disease (PD) is one of the most common age-related neurologic diseases. While existing therapeutic approaches, focusing on dopamine replacement, can alleviate some of the cardinal symptoms ... [more ▼]

Parkinson's disease (PD) is one of the most common age-related neurologic diseases. While existing therapeutic approaches, focusing on dopamine replacement, can alleviate some of the cardinal symptoms, they are associated with severe adverse effects in the long-term. Therefore, identification of new therapeutic interventions to reverse, stop or slow down the progression of Parkinson’s disease is a major focus of PD research. Similarly, identifying reliable biomarkers that would enable early therapeutic intervention is another key area of current research. Here, we evaluated a recently proposed non-dopaminergic protein drug target for PD, Regulator of G-Protein Signaling 4 (RGS4), and performed preliminary studies aimed at the identification of novel biomarker signatures using two murine models of Parkinson’s disease. Recent research on new non-dopaminergic PD drug targets has indicated that inhibition of RGS4, a member of the RGS family of proteins that inactivate G-proteins, could be an effective adjuvant treatment option. However, the effectiveness of RGS4 inhibition for an array of PDlinked functional and structural neuroprotection endpoints had not yet been demonstrated. Here, we used the 6-Hydroxydopamine (6-OHDA) lesioning mouse model to address this question. We observed, using a battery of behavioral and pathological measures, that mice deficient for RGS4 are not protected from 6-OHDA induced injury, and showed enhanced susceptibility in some measures of motor function. Our results suggest that inhibition of RGS4 as a non-dopaminergic target for PD should be approached with caution. In the second part of this study, two alpha-synuclein based PD mouse models, human E46K mutated overexpressed alpha-synuclein and alpha-synuclein fibril spreading models, were used to investigate early pathological events in PD and identify novel candidate biomarker signatures for subsequent validation. Two different time points, before disease onset, and at peak disease manifestation, were analyzed in the two models. Using multiple histopathology and molecular biology techniques, we were able to identify complex changes in patterns of gene expression at early stages of the disease, well before neurodegeneration is detectable. These findings might open venues for new therapeutic strategies and provide insights on the molecular perturbations occurring during the earliest stages of the disease, paving the way for the development of a biomarker signatures for early diagnosis of Parkinson’s disease. [less ▲]

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See detailFermi energy dependence of the optical emission in core/shell InAs nanowire homostructures
Möller, Michael; Oliveira, DS; Sahoo, PK et al

in Nanotechnology (2017), 28

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See detailFast Stochastic Non-linear Model Predictive Control for Electric Vehicle Advanced Driver Assistance Systems
Sajadi Alamdari, Seyed Amin UL; Voos, Holger UL; Darouach, Mohamed

in 13th IEEE International Conference on Vehicular Electronics and Safety, Vienna, Austria 27-28 June 2017 (2017, June 27)

Semi-autonomous driving assistance systems have a high potential to improve the safety and efficiency of the battery electric vehicles that are enduring limited cruising range. This paper presents an ... [more ▼]

Semi-autonomous driving assistance systems have a high potential to improve the safety and efficiency of the battery electric vehicles that are enduring limited cruising range. This paper presents an ecologically advanced driver assistance system to extend the functionality of the adaptive cruise control system. A real-time stochastic non-linear model predictive controller with probabilistic constraints is presented to compute on-line the safe and energy-efficient cruising velocity profile. The individual chance-constraint is reformulated into a convex second-order cone constraint which is robust for a general class of probability distributions. Finally, the performance of proposed approach in terms of states regulation, constraints fulfilment, and energy efficiency is evaluated on a battery electric vehicle. [less ▲]

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See detailHow Mobile Phone Handovers reflect Urban Mobility: A Simulation Study
Derrmann, Thierry UL; Frank, Raphaël UL; Engel, Thomas UL et al

in Derrmann, Thierry; Frank, Raphaël; Engel, Thomas (Eds.) et al How Mobile Phone Handovers reflect Urban Mobility: A Simulation Study (2017, June 26)

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See detailKeynote: Cultural heritage, musical diversity and functionality of music education
Sagrillo, Damien UL

in Andrea Kárpáti (Ed.) New landscapes in science and art - in focus: teaching Visual Culture. Book of Proceedings (2017, June 23)

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See detailCauses as Difference-Makers for Processes
Loew, Christian UL

in Philosophy and Phenomenological Research (2017)

It is natural to think of causes as difference-makers. What exact difference causes make, however, is an open question. In this paper, I argue that the right way of understanding difference-making is in ... [more ▼]

It is natural to think of causes as difference-makers. What exact difference causes make, however, is an open question. In this paper, I argue that the right way of understanding difference-making is in terms of causal processes: causes make a difference to a causal process that leads to the effect. I will show that this way of understanding difference-making nicely captures the distinction between causing an outcome and helping determine how the outcome happens and, thus, explains why causation is not transitive. Moreover, the theory handles tricky cases that are problematic for competing accounts of difference-making. [less ▲]

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See detailLa papauté et les communautés religieuses en Lorraine (Xe - XIIe siècles)
Engl, Hannes UL

Presentation (2017, June 14)

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See detailA Scalable Parallel Cooperative Coevolutionary PSO Algorithm for Multi-objective Optimization
Atashpendar, Arash UL; Dorronsoro, Bernabé; Danoy, Grégoire UL et al

in Journal of Parallel & Distributed Computing (2017)

We present a parallel multi-objective cooperative coevolutionary variant of the Speed-constrained Multi-objective Particle Swarm Optimization (SMPSO) algorithm. The algorithm, called CCSMPSO, is the first ... [more ▼]

We present a parallel multi-objective cooperative coevolutionary variant of the Speed-constrained Multi-objective Particle Swarm Optimization (SMPSO) algorithm. The algorithm, called CCSMPSO, is the first multi-objective cooperative coevolutionary algorithm based on PSO in the literature. SMPSO adopts a strategy for limiting the velocity of the particles that prevents them from having erratic movements. This characteristic provides the algorithm with a high degree of reliability. In order to demonstrate the effectiveness of CCSMPSO, we compare our work with the original SMPSO and three different state-of-the-art multi-objective CC metaheuristics, namely CCNSGA-II, CCSPEA2 and CCMOCell, along with their original sequential counterparts. Our experiments indicate that our proposed solution, CCSMPSO, offers significant computational speedups, a higher convergence speed and better or comparable results in terms of solution quality, when evaluated against three other CC algorithms and four state-of-the-art optimizers (namely SMPSO, NSGA-II, SPEA2, and MOCell), respectively. We then provide a scalability analysis, which consists of two studies. First, we analyze how the algorithms scale when varying the problem size, i.e., the number of variables. Second, we analyze their scalability in terms of parallelization, i.e., the impact of using more computational cores on the quality of solutions and on the execution time of the algorithms. Three different criteria are used for making the comparisons, namely the quality of the resulting approximation sets, average computational time and the convergence speed to the Pareto front. [less ▲]

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See detailKeynote: Music, heritage, function, and diversity
Sagrillo, Damien UL

Scientific Conference (2017, June 02)

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See detailThe vocabulary of Learner-Space Interactions - Understanding learning spaces experience through the repertory grid method
Lallemand, Carine UL; Koenig, Vincent UL

in Interaction Design & Architecture(s) (2017), 32

Higher education institutions are facing new educational challenges and are striving for an evolution in pedagogical practices. This evolution is accompanied by the need for innovative learning spaces to ... [more ▼]

Higher education institutions are facing new educational challenges and are striving for an evolution in pedagogical practices. This evolution is accompanied by the need for innovative learning spaces to support students in the development of “21st century skills”. Designing these spaces requires a deep understanding of learners’ needs and experiences. User-centered design therefore appears as an adequate process to understand learning experiences in relation to spatial design. In this paper, we describe how the repertory grid method has been used to explore students’ perceptions of learning environments (N = 26). We identified 381 personal constructs (contrasted word pairs) associated with learning spaces and grouped them into seven categories (22 subcategories), ranked by number of occurrences. This study provides a basis for the development of a vocabulary of learners-spaces interactions, in support of the design and assessment of learning space experiences. [less ▲]

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See detailSide-Channel Attacks meet Secure Network Protocols
Biryukov, Alex UL; Dinu, Dumitru-Daniel UL; Le Corre, Yann UL

in Gollmann, Dieter; Miyaji, Atsuko; Kikuchi, Hiroaki (Eds.) Applied Cryptography and Network Security - 15th International Conference, ACNS 2017, Kanazawa, Japan, July 10-12, 2017. Proceedings (2017, June)

Side-channel attacks are powerful tools for breaking systems that implement cryptographic algorithms. The Advanced Encryption Standard (AES) is widely used to secure data, including the communication ... [more ▼]

Side-channel attacks are powerful tools for breaking systems that implement cryptographic algorithms. The Advanced Encryption Standard (AES) is widely used to secure data, including the communication within various network protocols. Major cryptographic libraries such as OpenSSL or ARM mbed TLS include at least one implementation of the AES. In this paper, we show that most implementations of the AES present in popular open-source cryptographic libraries are vulnerable to side-channel attacks, even in a network protocol scenario when the attacker has limited control of the input. We present an algorithm for symbolic processing of the AES state for any input configuration where several input bytes are variable and known, while the rest are fixed and unknown as is the case in most secure network protocols. Then, we classify all possible inputs into 25 independent evaluation cases depending on the number of bytes controlled by attacker and the number of rounds that must be attacked to recover the master key. Finally, we describe an optimal algorithm that can be used to recover the master key using Correlation Power Analysis (CPA) attacks. Our experimental results raise awareness of the insecurity of unprotected implementations of the AES used in network protocol stacks. [less ▲]

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See detailSilicone sealants: A Finite Fracture Mechanics failure model for non-linear materials
Rosendahl, Philipp L.; Staudt, Yves UL; Odenbreit, Christoph UL et al

in 14th International Conference on Fracture (ICF 14) (2017, June)

A finite fracture mechanics failure model for hyperelastic silicone sealants is presented. The model is in very good agreement with simple shear tests of different adhesive joint geometries.

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See detailVERHALTEN AUSGEWÄHLTER NANOPARTIKEL IN KOMMUNALEN KLÄRANLAGEN UNTER BESONDERER BERÜCKSICHTIGUNG DER ANAEROBEN SCHLAMMBEHANDLUNG
Rahimi, Anahita Bahareh UL

Doctoral thesis (2017)

The increasing use of nanoparticles and the market to commercialize this innovative technology requires a deeper understanding of the behavior of nanoparticles (NPs) and the resulting consequences in an ... [more ▼]

The increasing use of nanoparticles and the market to commercialize this innovative technology requires a deeper understanding of the behavior of nanoparticles (NPs) and the resulting consequences in an environmentally The increasing use of nanoparticles and the market to commercialize this innovative technology requires a deeper understanding of the behavior of nanoparticles (NPs) and the resulting consequences in an environmentally relevant matrix. However, since the fate and behavior of nanoparticles is largely unknown to the environment, this study was done to investigate the key properties of nanoparticles, parameters to describe them and to discuss how these parameters can influence their fate and behavior in the natural environment. The core goal of this discussion is to relate sludge treatment to relevant properties of the nanoparticle, which may interact with a range of substances naturally present in wastewater treatment plants (WWTPs) and activated sludge. Understanding these properties is necessary for interpreting the fate of nanoparticles and predicting their effects in the actual environment. Environmentally matrix are challenging to investigate, for instance as in sludge and anaerobic sludge stabilization. According to the literature, it will be assumed that about 95% of the NPs entering the WWTP end up in the sludge. This work reports on the investigation and observation of NPs behavior in the different stages, using different experiments and metering devices. The different experiments include (i) characterization of NPs before their application (NanoSight), (ii) behavior analysis in terms of kinetic transformations (Turbiscan), (iii) long- and short-term analysis of NPs effects on anaerobic sludge stabilization (laboratory fermentation plants). The characterization represents the current size distribution of the NPs in a controlled environment (H2O). Size is one of the defining properties of NPs, which causes changes in physical and chemical properties of NPs compared to their original materials. The results show that the distribution of NPs depends on the type of particle, surface coating and dispersion concentration. These parameters are subject to permanent changes in sludge. That is why an exact allocation to the effects seems almost impossible. Characterization is indispensable for the subsequent comprehension of the effects, and for the understanding of findings, which may result from the behavioral analysis, as well as from the effect analysis. The behavioral analysis was carried out by Turbiscan technology to consider relevant sludge parameters and substances (Chemical Oxygen Demand COD, Polymers, Humic acids, digestion process) to the behavior of NPs in sludge. The initial aim was to progressively add of representative substances to approximate the experiment to natural conditions. The phase separation detection identified a clear sedimentation behavior in all samples. To explain this and the kinetic modification as well as the resultant kinetic instability, the NPs’ diameter (particle size detection) were studied. The more instable samples had often smaller diameters. The substances within the sludge seem to influence the kinetic stability of NPs. This could be caused by the dynamic corona (active interaction with environment) and hard corona (strongly bound and restrained interaction with environment) formation, as well as agglomeration or modification of surface charges. Changes in kinetic stability means changes in the behavior and fate of NPs in such an environmental media like sludge. However, since the sludge is filtered for the behavioral analysis, the microorganism’s role is neglected. In order to complete the behavioral analysis considering the microorganism’s contribution, the consequences of the NP-behavior are measured as effects under various realistic conditions. The effects of NPs’ behavior on the anaerobic microorganisms were investigated based on their potential and efficiency in anaerobic sludge stabilization for gaining additional insights. The long-term effects of NPs in sludge treatment plants (STP) were investigated using four parallel pilot reactors operated under identical conditions, with daily feeding (substrate and two different NP-concentration). There was a temporary decrease of Biogas especially at the third phase (second concentration) except for the ZnO-reactor while the proportion of methane remained stable. Based on the knowledge obtained from the characterization and behavioral analysis, this might be due to the kinetic transformation of NPs. When the particle size for instability is exceeded as a consequence of surface changes and agglomerations, rapid sedimentation occurs. After eliminating the NP-reactivity and obtaining NP-agglomerations, NPs are extracted from the digestion system (sedimentation). Due to that, the microorganisms are able to operate to their full potential and efficiency, which is an indication of extracellular inhibition and preclude probably the intracellular inhibition caused by ions release. The short-term effects of ENPs in batch experiments were investigated under identical conditions. Furthermore, oxygen was used as an inhibitor to intensify the NP’s effects on the anaerobic microorganisms and digestion process. Oxygen is toxic for anaerobic microorganisms and enhance the release of ions. NP-effects were evaluated for methane yield. It will be assumed that the corona formations created by the sludge substances, reduce the release of ions and the NP-toxicity, even after decreasing the biomass. In addition, the NPs are able to eliminate O2 as an inhibitor, as well as positively influence the production dynamics and methane yield. To sum up, the growing interest in nanoparticles and their potential has presented many challenges for science, in toxicology and innovative technologies. These challenges bring new questions related to understanding NPs and their interplay with certain circumstances. A considerable contribution has been made for understanding the behavior of nanoparticles in the environmentally relevant media. However, a partial understanding for the fate of nanoparticles in complex matrices has been gained. As the nanoparticles themselves are such a complex matter, they require more research in developing a more complete understanding of the way they function. Having this knowledge would enable to explore progressively their behavior and fate in complex matrices.. [less ▲]

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