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ORBi

Open Science @LCSB-ECI Schymanski, Emma Presentation (2021, June 17) Detailed reference viewed: 35 (1 UL)Open-Cell Aluminium Foams with Graded Coatings as Passively Controllable Energy Absorbers ; Beex, Lars ; et al in Materials and Design (2015), 87 Compared to most bulk materials, open-cell aluminium (Al) foams (OCAFs) are light-weight and can absorb a significant amount of energy in compression, e.g. during impact.When coatedwith nickel (Ni), OCAFs ... [more ▼] Compared to most bulk materials, open-cell aluminium (Al) foams (OCAFs) are light-weight and can absorb a significant amount of energy in compression, e.g. during impact.When coatedwith nickel (Ni), OCAFs can absorb even more energy, making them more appropriate for impacts at higher velocities than uncoated OCAFs. When Ni-coated OCAFs experience low-velocity impact however, the stopping distance during the impact is small compared to that of uncoated OCAFs and hence, deceleration occurs fast. This exposes devices (and possibly human beings) protected by OCAFs to large internal forces leading to internal damage. An OCAF that combines the properties of uncoated and coated OCAFs can absorb energy during both low-velocity and high-velocity impact scenarios. This contribution introduces two of such OCAFs which are created by partially and gradually coating OCAFs. The general mechanics of the two OCAFs are revealed using experimental and numerical observation methods. [less ▲] Detailed reference viewed: 673 (27 UL)Opportunities and challenges of using blockchain technology in public administration – Insights from the FLORA project of Germany’s Federal Office for Migration and Refugees ; ; et al Report (2022) Detailed reference viewed: 45 (5 UL)Optical measurement under space conditions Bremer, Mats Doctoral thesis (2022) The growing interest in space by governmental and private institutions has increased significantly in recent years. The issue of quality control plays an extremely important role in space travel, as ... [more ▼] The growing interest in space by governmental and private institutions has increased significantly in recent years. The issue of quality control plays an extremely important role in space travel, as possible defects can cause enormous damage. The present work deals with a possible method to improve already existing quality control procedures for space flight. With the help of a 3D scanner, different components are measured and evaluated under space conditions. In particular, the linear thermal expansions are analyzed. The work has shown that the elaborated procedure works for metallic materials. For composites or joints between different materials, positive approaches were shown, which, however, could not be validated within the scope of this work. Components made of pure carbon fiber material cannot be evaluated with the technical equipment used. [less ▲] Detailed reference viewed: 78 (6 UL)Optimal design of line replaceable units ; ; Arts, Joachim et al in Naval Research Logistics (2023) Detailed reference viewed: 23 (0 UL)Optimal dispatching of electric and hybrid buses subject to scheduling and charging constraints Rinaldi, Marco ; ; Laskaris, Georgios et al Scientific Conference (2018, November) We consider the problem of optimally determining the sequence of electric and hybrid buses departing from a multi-line bus terminal, considering both service constraints (schedule adherence) and energy ... [more ▼] We consider the problem of optimally determining the sequence of electric and hybrid buses departing from a multi-line bus terminal, considering both service constraints (schedule adherence) and energy constraints (electric bus charging status, bus recharging scheduling in capacitated facilities). The problem is formulated as a Mixed Integer Linear Program, with the objective of minimizing the total operational cost for the bus lines in question. System dynamics are captured by practical sets of constraints, ranging from scheduling adherence to discharge- recharge dynamics. Individual operational costs at the bus level and at the trip level are fully parametrized, allowing for extensive sensitivity analysis. We investigate a real-life case study based on the city of Luxembourg, where two charging stations have been installed in the central station’s bus terminal. Experimental results show that, while full electrification is indeed possible, the required fleet size depends strongly on the given line(s) timetable. [less ▲] Detailed reference viewed: 153 (8 UL)Optimal electrode coverage based on a new criterion for piezoelectric energy harvesters Shang, Lan ; ; Zilian, Andreas in Energy Conversion and Management (2023), 284 Piezoelectric energy harvesters (PEHs) are a promising alternative to conventional electrochemical batteries with the advantage of being self-powered and maintenance-free, but their application is ... [more ▼] Piezoelectric energy harvesters (PEHs) are a promising alternative to conventional electrochemical batteries with the advantage of being self-powered and maintenance-free, but their application is severely restricted by the low electric power output. It has been reported that the power output of PEHs can be enhanced by well-designed electrode coverage. A common design criterion for beam-like PEHs is based on the strain node to avoid electrode charge cancellation. This criterion, however, is not feasible for PEHs subject to complex spatio-temporal excitation patterns, where strain nodes change their position. This work proposes a new design criterion for optimal electrode coverage of beam-like PEHs based on the closed-form solution of the circuit equation that expresses voltage as a function of the beam’s dynamic response, specifically the cross-section rotation. The new criterion maximizes the averaged curvature of the beam segment covered by the electrode using data on the instantaneous rotation field. The improved physical significance and reliability of the presented criterion are discussed. The associated electrode optimization procedure is then exemplified for PEHs driven by fluid flow, which helps to realize a complex excitation pattern. Two numerical studies, both including a variety of combinations of fluid densities and inlet velocities, are performed to demonstrate that an optimal electrode configuration can be obtained with the proposed criterion. Comparison of different electrode configurations in above studies finally leads to useful conclusions on the power output and electrode configuration. [less ▲] Detailed reference viewed: 39 (0 UL)Optimal Management of Electrified and Cooperative Bus Systems Viti, Francesco ; Rinaldi, Marco ; in Transportation Systems for Smart, Sustainable, Inclusive and Secure Cities (2020) Detailed reference viewed: 64 (2 UL)Optimal multi-line bus dispatching at terminals with electric charging scheduling constraints Rinaldi, Marco ; ; et al Scientific Conference (2018, July) We consider the problem of optimally determining the sequence of electric and conventional internal combustion buses departing from a multi-line bus terminal, considering both service constraints ... [more ▼] We consider the problem of optimally determining the sequence of electric and conventional internal combustion buses departing from a multi-line bus terminal, considering both service constraints (schedule adherence) and energy constraints (electric bus charging status, bus recharging scheduling in capacitated facilities). The problem is formulated as a Mixed Integer Linear Program, with the objective of minimizing the total operational cost for the bus lines in question. System dynamics are captured by twenty sets of constraints, ranging from scheduling adherence to discharge-recharge dynamics. Individual operational costs at the bus level (cost of running an electric / non electric bus per km, cost of recharging) and at the trip level (penalty due to failed schedule adherence) are fully parametrised, allowing for extensive sensitivity analysis. We investigate a real-life case study based in the city of Luxembourg, where two charging stations have been installed in the central station’s bus terminal. Through the model we investigate: i) the minimum amount of electric buses necessary to perform a day’s schedule for two currently partially electrified lines, without resorting to conventional internal combustion alternatives; ii) the impact of electrifying two additional lines, specifically considering the trade-offs related to either adding new buses or new charging stations at the bus terminal. [less ▲] Detailed reference viewed: 178 (10 UL)Optimal output consensus control and outlier detection Thunberg, Johan ; in Proceedings of the 19th International Symposium on Mathematical Theory of Networks and Systems (2010) In this paper we study the output consensus problem for systems of agents with linear continuous time invariant dynamics, and derive control laws that minimize a conical combination of the energies of the ... [more ▼] In this paper we study the output consensus problem for systems of agents with linear continuous time invariant dynamics, and derive control laws that minimize a conical combination of the energies of the agents control signals, while only using local information. We show that the optimal control requires the connectivity graph to be complete and in general requires measurements of the state errors. We identify the cases where the optimal control is only based on output errors, and show that in the infinite time horizon case, the optimal control can always be expressed as a dynamic control that is only based on the output errors. We also give a Lemma for the position of the equilibrium point for a large class of agent dynamics. As a second part of this paper we consider the problem of outlier detection, in which an agent wants to deduce if an other agent is using the consensus controller, or if it is an outlier that uses a different controller. We introduce the outlier detection equation. [less ▲] Detailed reference viewed: 45 (0 UL)Optimal output consensus control for systems of agents with continuous linear dynamics Thunberg, Johan ; in Proceedings of 18th IFAC World Congress (2011) In this paper we study the output consensus problem for systems of agents with linear continuous, time invariant dynamics. We derive control laws with minimal energy that solves the problem, while using ... [more ▼] In this paper we study the output consensus problem for systems of agents with linear continuous, time invariant dynamics. We derive control laws with minimal energy that solves the problem, while using only relative information. Instead of considering a fixed communication topology for the agents, and derive the optimal control for that topology, we derive the optimal control law for any communication topology between the agents. We show that the optimal control uses only relative information but requires the connectivity graph to be complete and in general requires measurements of the state errors. We identify the cases where the optimal control is only based on output errors, and show that in the infinite time horizon case, the optimal controller can always be expressed as a dynamic controller that is only based on the output errors. Regarding the theoretic contributions of this paper, the control laws are derived using methods from linear vector space optimization and are given in closed form. To the authors knowledge these methods have not been used within this context before. [less ▲] Detailed reference viewed: 91 (0 UL)Optimal positioning of surveillance UGVs ; ; Thunberg, Johan in Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (2008) Unmanned ground vehicles (UGVs) equipped with surveillance cameras present a flexible complement to the numerous stationary sensors being used in security applications today. However, to take full ... [more ▼] Unmanned ground vehicles (UGVs) equipped with surveillance cameras present a flexible complement to the numerous stationary sensors being used in security applications today. However, to take full advantage of the flexibility and speed offered by a group of UGV platforms, a fast way to compute desired camera locations that cover or surround a set of buildings e.g., in response to an alarm, is needed. In this paper we focus on two problems. The first is how to create a line-of-sight perimeter around a given set of buildings with a minimal number of UGVs. The second problem is how to find UGV positions such that a given set of walls are covered by the cameras while taking constraints in terms of zoom, range, resolution and field of view into account. For the first problem we propose a polynomial time algorithm and for the second problem we extend our previous work to include zoom cameras and furthermore provide a theoretical analysis of the approach itself. A number of examples are presented to illustrate the two algorithms. [less ▲] Detailed reference viewed: 121 (0 UL)Optimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms ; ; et al in Sensors (2013), 13(11), 14984-15005 This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization ... [more ▼] This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach. [less ▲] Detailed reference viewed: 144 (6 UL)Optimal strategy for multiple-phase estimation under practical measurement with multimode NOON states Ur Rehman, Junaid ; ; et al in Physical Review. A. (2022), 106 Detailed reference viewed: 26 (0 UL)Optimierung der Tragfähigkeit von antibiotikabeladenen PMMA-hüftinterimsprothesen Thielen, Thomas Doctoral thesis (2009) Detailed reference viewed: 98 (19 UL)Optimising time-series experimental design for modelling of circadian rhythms: the value of transient data Mombaerts, Laurent ; Mauroy, Alexandre ; Goncalves, Jorge in IFAC-PapersOnLine (2016, October) Circadian clocks consist of complex networks that coordinate the daily cycle of most organisms. In light/dark cycles, the clock is synchronized (or entrained) by the environment, which corresponds to a ... [more ▼] Circadian clocks consist of complex networks that coordinate the daily cycle of most organisms. In light/dark cycles, the clock is synchronized (or entrained) by the environment, which corresponds to a constant rephasing of the oscillations and leads to a steady state regime. Some circadian clocks are endogenous oscillators with rhythms of about 24-hours that persist in constant light or constant darkness. This operating mechanism with and without entrainment provides flexibility and robustness to the clock against perturbations. Most of the clock-oriented experiments are performed under constant photoperiodic regime, overlooking the transitory regime that takes place between light/dark cycles and constant light or darkness. This paper provides a comparative analysis of the informative potential of the transient time-series data with the other regimes for clock modelling. Realistic data were simulated from 2 experimentally validated plant circadian clock models and sliced into several time windows. These windows represent the different regimes that take place before, meanwhile and after the switch to constant light. Then, a network inference tool was used over each window and its capability of retrieving the ground-truth of the network was compared for each window. The results suggest that including the transient data to the network inference technique significally improves its performance. [less ▲] Detailed reference viewed: 204 (21 UL)An Optimization-Based Iterative Learning Method for Anticipatory Network Traffic Control ; ; Viti, Francesco et al in Proceedings of the 16th COTA International Conference of Transportation Professionals (2016) Detailed reference viewed: 127 (3 UL)Orchestrating clinical simulations with FEniCS ; ; Hale, Jack Scientific Conference (2016, May) Detailed reference viewed: 88 (5 UL)Overcoming Design Fixation: Design-by-Analogy Studies and Non-Intuitive Findings Moreno Grandas, Diana Paola ; ; et al in Artificial Intelligence for Engineering Design, Analysis and Manufacturing – AIEDAM (2016), 20(2), 185-199 Design fixation is a phenomenon with important significance to many fields of design due to the potential negative impacts it may have in design outcomes, especially during the ideation stage of the ... [more ▼] Design fixation is a phenomenon with important significance to many fields of design due to the potential negative impacts it may have in design outcomes, especially during the ideation stage of the design process. The present study aims to provide a framework for understanding, or at least probing, design fixation by presenting a review of existing defixation approaches, as well as metrics that have been employed to understand and account for design fixation. This study also describes the results of two design by analogy (DbA) methods, WordTree and SCAMPER, to overcome design fixation in an experiment that involved 97 knowledge-domain experts. The study outcomes are at least twofold: a common framework of metrics and approaches to overcome design fixation in a wide range of design problems and nonintuitive results for DbA approaches in design fixation and other related creativity metrics. The application of WordTree and SCAMPER shows that both methods yield increased novelty compared to a control, where the SCAMPER results are significantly higher than WordTree. It is also found that WordTree mitigates design fixation whereas SCAMPER appears to be ineffective for this purpose but effective to generate an increased quantity of novel ideas. These results demonstrate that both DbA methods provide defixation capabilities and enhance designers’ creativity during idea generation. [less ▲] Detailed reference viewed: 166 (0 UL)An overview of descriptive studies in relation to a general design research methodology Blessing, Lucienne ; in Frankenberger, E. (Ed.) Designers - the Key to Successful Product Development (1998) Detailed reference viewed: 158 (0 UL) |
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