Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Peer Reviewed
See detailApproche neuronale dynamique pour la prédiction de polluants atmosphériques: application à l'industrie papetière.
Sainlez, Matthieu UL; Heyen, Georges; Lumen, Philippe

Scientific Conference (2011, May 27)

Detailed reference viewed: 32 (2 UL)
Full Text
Peer Reviewed
See detailThe Arabidopsis circadian clock incorporates a cADPR-based feedback loop
Dodd, A. N.; Gardner, M. J.; Hotta, C. T. et al

in SCIENCE (2007), 318(5857), 1789-1792

Transcriptional feedback loops are a feature of circadian clocks in both animals and plants. We show that the plant circadian clock also incorporates the cytosolic signaling molecule cyclic adenosine ... [more ▼]

Transcriptional feedback loops are a feature of circadian clocks in both animals and plants. We show that the plant circadian clock also incorporates the cytosolic signaling molecule cyclic adenosine diphosphate ribose (cADPR). cADPR modulates the circadian oscillator’s transcriptional feedback loops and drives circadian oscillations of Ca2+ release. The effects of antagonists of cADPR signaling, manipulation of cADPR synthesis, and mathematical simulation of the interaction of cADPR with the circadian clock indicate that cADPR forms a feedback loop within the plant circadian clock. [less ▲]

Detailed reference viewed: 157 (14 UL)
Full Text
Peer Reviewed
See detailArchitecture tradeoffs of integrating a mesh generator to partition of unity enriched object-oriented finite element software
Dunant, C.; Nguyen, V. P.; Belgasmia, M. et al

in European Journal of Computational Mechanics (2007), 16(2), 237-258

We explore the tradeoffs of using an internal mesher in a XFEM code. We show that it allows an efficient enrichement detection scheme, while retaining the ability to have welladapted meshes. We provide ... [more ▼]

We explore the tradeoffs of using an internal mesher in a XFEM code. We show that it allows an efficient enrichement detection scheme, while retaining the ability to have welladapted meshes. We provide benchmarks highlighting the considerable gains which can be expected from a well designed architecture. The efficiency of the proposed algorithm is shown by solving fracture mechanics problems of densely micro-cracked bodies including adaptive mesh refinement. [less ▲]

Detailed reference viewed: 113 (0 UL)
Full Text
See detailARL – Akademie für RaumePostwachstum und Raumentwicklung – Denkanstöße für Wissenschaft und Praxis.
Best, Benjamin; Brückner, Heike; Hülz, Martina et al

Report (2021)

This position paper, drawn up by members of the ARL’s Working Group on Post-Growth Economies (2016 – 2020), situates the international post-growth debate and discusses its relevance for spatial ... [more ▼]

This position paper, drawn up by members of the ARL’s Working Group on Post-Growth Economies (2016 – 2020), situates the international post-growth debate and discusses its relevance for spatial development and spatial science research. In addition to sectoral approaches and findings, the authors make concrete proposals for post-growth focuses in planning, research and teaching, distinguishing between changes that can be achieved in the short term and measures designed for the medium to long term. [less ▲]

Detailed reference viewed: 74 (1 UL)
Full Text
Peer Reviewed
See detailArtificial neural network to predict the weld status in laser welding of copper to aluminum
Mathivanan, Karthik UL; Plapper, Peter UL

in Procedia CIRP (2021)

Laser welding of copper to aluminum is challenging due to the formation of complex intermetallic phases. More Al (~18.5 at. %) can be dissolved in Cu, in contrast to Cu (~2.5 at. %) in Al. Therefore ... [more ▼]

Laser welding of copper to aluminum is challenging due to the formation of complex intermetallic phases. More Al (~18.5 at. %) can be dissolved in Cu, in contrast to Cu (~2.5 at. %) in Al. Therefore, welding from copper side, large melting of Al can be achieved. However optimum Cu and Al must be melted for a strong joint. Finding the right amount is difficult and time consuming by tradition analysis technique like inspection by weld cross-sections. Considering the speed of the welding process and complexity of analysis involving with metallography cross-sections, alternative rapid method to qualify the welds are necessary. The acoustic emission during laser welding can give proportional information of the Al, Cu melted. With such an approach the weld status can be obtained in real time. In this paper the acoustic welding signal using an airborne sensor in the audible range of 20 Hz to 20 kHz, is correlated to the weld strength and material mixing (Al, Cu melt). Finally, the weld status is predicted by an artificial neural network based on the acquired signal. [less ▲]

Detailed reference viewed: 48 (3 UL)
Full Text
Peer Reviewed
See detailAssessing Equity in Carsharing Systems: the case of Munich, Germany
Giorgione, Giulio; Viti, Francesco UL

in Transportation Research Procedia (2021)

Detailed reference viewed: 30 (1 UL)
Full Text
Peer Reviewed
See detailAssessing geographical effects in spatial diffusion processes: The case of euro coins
Le Texier, Marion UL; Caruso, Geoffrey UL

in Computers, Environment and Urban Systems (2017), 61

We examine how geographical structures impact diffusion processes within a regional system. From the example of euro coin diffusion across countries, we show how the relative position and population ... [more ▼]

We examine how geographical structures impact diffusion processes within a regional system. From the example of euro coin diffusion across countries, we show how the relative position and population endowment of regions impact our understanding of interregional mobility, beyond simple spatial interaction effects. The mix of coins of different origins is a complex but unique trace of the movement of individuals within a common currency area, potentially revealing a new facet of European integration. We simulate an individual-based dynamic model where agents move and exchange coins across regions. We analyse the convergence towards a homogeneous mix of coins through time for a series of different theoretical spatial systems. This sensitivity analysis demonstrates the impact of the regularity and aggregation levels, or centrality/periphery effects, on spatial diffusion dynamics. We then calibrate the model against empirical data for the regions of 5 European countries and provide estimates of mobility rates, distance decay and population attractiveness factors, affecting the diffusion of coins, hence international movements and European integration. [less ▲]

Detailed reference viewed: 222 (9 UL)
Full Text
Peer Reviewed
See detailAssessing partial observability in network sensor location problems
Viti, Francesco UL; Rinaldi, Marco; Francesco, Corman et al

in Transportation Research. Part B : Methodological (2014), 70

The quality of information on a network is crucial for different transportation planning and management applications. Problems focusing on where to strategically extract this information can be broadly ... [more ▼]

The quality of information on a network is crucial for different transportation planning and management applications. Problems focusing on where to strategically extract this information can be broadly subdivided into observability problems, which rely on the topological properties of the network, and flow-estimation problems, where (prior) information on observed flows is needed to identify optimal sensor locations. This paper contributes mainly to the first category: more specifically, it presents a new methodology and an intuitive metric able to quantify the quality of a solution in case of partial observability, i.e. when not all flow variables are observed or can be uniquely determined from the observed flows. This methodology is based on existing approaches that can efficiently find solutions for full observability (i.e., the set of sensors needed to make the system fully determined), and exploits only the algebraic relations between link, route and origin-destination flow variables to quantify the information contained in any arbitrary subset of these variables. The new metric allows, through its adoption within simple search algorithms, to efficiently select sensor locations when the number of available sensors is limited by, for example, budget constraints and is less than the number needed to guarantee full observability. The chosen positions aim at selecting those locations that contain the largest information content on the whole network. This is an important contribution in this field, since even in small sized networks the solution for full observability requires an exceedingly large amount of sensors. The assessment of partial observability solutions, based on explicit route enumeration, allows one to categorize families of full observability solutions, and shows that these contain different information potential. This way, it is possible to rank solutions requiring a lower number of sensors while containing the same information content. We tested this new methodology both on toy networks, in order to analyse the properties of the metric and illustrate its logic, and to explain and test heuristic search algorithms for optimal sensor positioning on a real-sized network. Analysis of partial observability solutions shows that the basic search algorithms succeed in finding the links that contain the largest deal of information in a network. [less ▲]

Detailed reference viewed: 162 (10 UL)
Full Text
Peer Reviewed
See detailASSESSING PROFIT MAXIMIZATION AND FLEET MANAGEMENT IN A MULTIMODAL NETWORK DESIGN PROBLEM
Bandiera, Claudia UL; Connors, Richard UL; Viti, Francesco UL

in Proceedings of the 25th International Conference of Hong Kong Society for Transportation Studies, HKSTS 2021: Sustainable Mobility (2021, December)

Detailed reference viewed: 39 (8 UL)
Full Text
Peer Reviewed
See detailAssessing the consistency between observed and modelled route choices through GPS data
Hadjidimitriou, Selini N.; Dell'Amico, Mauro; Cantelmo, Guido UL et al

in Proceedings of the MT-ITS Conference (2015, June)

Detailed reference viewed: 116 (2 UL)
Full Text
Peer Reviewed
See detailAssessing the effect of route information on network observability applied to sensor location problems
Rinaldi, Marco; Corman, Francesco; Viti, Francesco UL

in Transportation Research Procedia (2015), 10

Detailed reference viewed: 115 (10 UL)
Full Text
Peer Reviewed
See detailAssessing the performance of coordinated predictive control strategies on urban-motorway networks
Rinaldi, Marco UL; Viti, Francesco UL

in IFAC-PapersOnLine (2018, July), 51(9), 285-290

Coordination and integration of different traffic control policies have been of considerable interest in research in the last decades and, recently, have been object of large scale implementation trials ... [more ▼]

Coordination and integration of different traffic control policies have been of considerable interest in research in the last decades and, recently, have been object of large scale implementation trials. In the setting of peri-urban motorway systems, coordination of various kinds of controllers must however be accompanied by accurate prediction of both propagation of flows and queues in the network, as well as the users’ response in terms of route choice. In this paper, we showcase through a real-life case study how coordination and prediction are both essential when performing hybrid urban-motorway control. Simulation results of a Model Predictive Control application are compared to simpler local control approaches, and the impact of coordinated intersection control and, additionally, Ramp Metering is evaluated. [less ▲]

Detailed reference viewed: 88 (1 UL)
Full Text
Peer Reviewed
See detailAssessing the robustness of decentralized gathering: a multi‐agent approach on micro‐biological systems
Proverbio, Daniele UL; Gallo, Luca; Passalacqua, Barbara et al

in Swarm Intelligence (2020), 14

Adopting a multi-agent systems paradigm, we developed, tested and exploited a computational testbed that simulates gathering features of the social amoeba Dictyostelium discoideum. It features a tailored ... [more ▼]

Adopting a multi-agent systems paradigm, we developed, tested and exploited a computational testbed that simulates gathering features of the social amoeba Dictyostelium discoideum. It features a tailored design and implementation to manage discrete simulations with autonomous agents on a microscopic scale, thus focusing on their social behavior and mutual interactions. Hence, we could assess the behavioral conditions under which decentralized gathering could occur. We investigated the dependence of the model dynamics on the main physical variables, namely density and number of amoebas, gaining indications that the process strongly depends on both. This result integrates previous researches, where density is identified as the sole relevant variable. We determined a high-density and high-numerosity region where assuming a scale-free behavior is safe. We also estimated the systematic uncertainties arising from a number of amoebas off the scale-free region, when coping with limited computational resources. Finally, we probed the robustness of the simulated gathering process against both extrinsic and intrinsic noise sources. [less ▲]

Detailed reference viewed: 140 (5 UL)
Full Text
Peer Reviewed
See detailAssessing Two-way and One-way Carsharing: an Agent-Based Simulation Approach
Giorgione, Giulio UL; Bolzani, Luca UL; Viti, Francesco UL

in Transportation Research Procedia (2020), 52

Detailed reference viewed: 79 (14 UL)
Full Text
See detailAssessment of implicit and explicit algorithms in numerical simulation of granular matter
Samiei, Kasra UL

Doctoral thesis (2012)

The objectives of this dissertation are to investigate and demonstrate the potentials of implicit integration methods in predicting the dynamics of granular media and to describe the granular dynamics on ... [more ▼]

The objectives of this dissertation are to investigate and demonstrate the potentials of implicit integration methods in predicting the dynamics of granular media and to describe the granular dynamics on forward and backward acting grates by discrete element method. Traditionally, explicit integration methods are employed within the context of Discrete Element Method. Generally, explicit equations are simpler to solve than the implicit ones but they require a small time step to be utilized. In this study, an implicit Numerov integration scheme is employed to integrate the equations of motion. The implicit method is verified in different test cases starting from simple cases to more complicated cases including hundreds of particles. Comparing the results with the results of the explicit method, it is shown that the implicit method exhibits a distinguished advantage only at very large time steps. Taking into account the overhead of solving non-linear equations at each time step, it is concluded that implicit methods are computationally too expensive for their limited gains. Addressing the second objective of this study, the residence time distribution of granular particles on forward and backward acting grates are numerically predicted. Very good agreement between the predictions and the available experimental results is achieved. It can be concluded that the Discrete Element Method is highly capable of predicting the dynamics of solid fuel particles on grate systems. Future work shall include coupling of the method with computational fluid dynamics in order to account for thermal conversion of the fuel particles. [less ▲]

Detailed reference viewed: 215 (4 UL)
Full Text
Peer Reviewed
See detailAttack-tolerant Control and Observer-based Trajectory Tracking for Cyber-Physical Systems
Bezzaoucha, Souad UL; Voos, Holger UL; Darouach, Mohamed

in European Journal of Control (2018)

In the present paper, a model-based fault/attack tolerant scheme is proposed to cope with cyber-threats on Cyber-Physicals Systems. A common scheme based on observers is designed and a state feedback ... [more ▼]

In the present paper, a model-based fault/attack tolerant scheme is proposed to cope with cyber-threats on Cyber-Physicals Systems. A common scheme based on observers is designed and a state feedback control based on an aperiodic event-triggered framework is given with control synthesis and condition on the switching time. Classical fault tolerant control with Bi-linear Matrix Inequality () approaches are used to achieve novel and better security strategy based on an event-triggered control implementation. The purpose of using the event-based implementation would be to reduce (limit) the total number of transmissions to only instances when the networked control system (NCS) needs attention. Simulation results on a real-time laboratory three tank system are given to show the attack-tolerant control ability despite data deception attacks on both actuators and sensors. A detection/isolation scheme based on residual observers bank is also proposed. [less ▲]

Detailed reference viewed: 317 (10 UL)
Full Text
Peer Reviewed
See detailAttitude consensus using networks of uncalibrated cameras
Thunberg, Johan UL; Hu, X.

in The proceedings of the 33rd Chinese Control Conference (2014)

This paper addresses the problem of consensus on SO(3) for networks of uncalibrated cameras. Under the assumption of a pinhole camera model, we prove convergence to the consensus manifold for two types of ... [more ▼]

This paper addresses the problem of consensus on SO(3) for networks of uncalibrated cameras. Under the assumption of a pinhole camera model, we prove convergence to the consensus manifold for two types of kinematic control laws, when only conjugate rotation matrices KRK-1 are available among the agents. In these conjugate rotations, the rotation matrices are distorted by the (unknown) intrinsic parameters of the cameras. For the conjugate rotations, we introduce distorted versions of well known local parameterizations of SO(3) and show consensus by using three types of control laws. The control laws are similar to the standard consensus protocol used for systems of agents with single integrator dynamics, where pairwise differences between the states of neighboring agents are used. By considering the restriction to the planar case (when all the rotations have the same rotational axes), we weaken the assumptions on the cameras in the system and consider networks where the camera matrices differ between agents. [less ▲]

Detailed reference viewed: 98 (0 UL)
Full Text
Peer Reviewed
See detailAugmented Reality in Manual Assembly Processes
Kolla, Sri Sudha Vijay Keshav UL; Sanchez, Andre UL; Minoufekr, Meysam UL et al

in Kolla, Sri Sudha Vijay Keshav; Sanchez, Andre; Minoufekr, Meysam (Eds.) et al Augmented Reality in Manual Assembly Processes (2020, September 23)

Augmented Reality (AR) is a novel technology that projects virtual information on the real world environment. With the increased use of Industry 4.0 technologies in manufacturing, AR has gained momentum ... [more ▼]

Augmented Reality (AR) is a novel technology that projects virtual information on the real world environment. With the increased use of Industry 4.0 technologies in manufacturing, AR has gained momentum across various stages of product life cycle. AR can benefit production operators in many manufacturing tasks such as quality inspection, work instructions for manual assembly, maintenance, and in training. This research presents not only a typical architecture of an AR system but also both its software and hardware functions. The architecture is then applied to display virtual assembly instructions in the form of 3D animations on to the real world environment. The chosen assembly task in this research is to assemble a planetary gearbox system. The assembly instructions are displayed on a mobile device targeting a static tracker placed in the assembly environment. [less ▲]

Detailed reference viewed: 148 (20 UL)
Full Text
See detailAutomated optimisation of stem cell-derived neuronal cell culture in three dimensional microfluidic device
Kane, Khalid UL

Doctoral thesis (2019)

This dissertation is a compilation of publications and manuscripts that aim 1) to integrate an automated platform optimised for long term in vitro cell culture maintenance for Parkinson’s disease, long ... [more ▼]

This dissertation is a compilation of publications and manuscripts that aim 1) to integrate an automated platform optimised for long term in vitro cell culture maintenance for Parkinson’s disease, long term live cell imaging and the handling of many cell lines, 2) to combine physics principles with imaging techniques to optimise the seeding of Matrigel embedded human neuroepithelial stem cells into a three-dimensional microfluidic device, and 3) to combine engineering principles with cell biology to optimise the design of a three-dimensional microfluidic system based on phaseguide technology. In the first publication manuscript, we investigated Matrigel as a surrogate extracellular matrix in three-dimensional cell culture systems, including microfluidic cell culture. The study aimed at understanding and characterising the properties of Matrigel. Using classical rheological measurements of Matrigel (viscosity versus shear rate) in combination with fluorescence microscopy and fluorescent beads for particle image velocimetry measurements (velocity profiles), the shear rates experienced by cells in a microfluidic device for three-dimensional cell culture was characterised. We discussed how the result of which helped to mechanically optimise the use of Matrigel in microfluidic systems to minimise the shear stress experienced by cells during seeding in a microchannel. The second manuscript proposes a methodology to passively control the flow of media in a three-dimensional microfluidic channel. We used the fluid dynamic concept of similitude to dynamically replicate cerebral blood flow in a rectangular cross-sectional microchannel. This similarity model of a target cell type and a simple fluid flow mathematical prediction model was used to iterate the most optimum dimensions within some manufacturing constraints to adapt the design of the OrganoPlate, a cell culture plate fully compatible with laboratory automation, which allowed its re-dimension to achieve over 24h of flow for the culture of human neuroepithelial stem cells into midbrain specific dopaminergic neurons. In the third publication manuscript, we propose an automated cell culture platform optimised for long-term maintenance and monitoring of different cells in three-dimensional microfluidic cell culture devices. The system uses Standard in Laboratory Automation or SiLA, an open source standardisation which allows rapid software integration of laboratory automation hardware. The automation platform can be flexibly adapted to various experimental protocols and features time-lapse imaging microscopy for quality control and electrophysiology monitoring to assess cellular activity. It was biologically validated by differentiating Parkinson’s disease patient derived human neuroepithelial stem cells into midbrain specific dopaminergic neurons. This system is the first example of an automated Organ-on-a-Chip culture and has the potential to enable a versatile array of in vitro experiments for patient-specific disease modelling. Finally, the fourth manuscript initiates the assessment of the neuronal activity of induced pluripotent stem cell derived neurons from Parkinson’s Disease patients with LRRK2-G2019S mutations and isogenic controls. A novel image analysis pipeline that combined semi-automated neuronal segmentation and quantification of calcium transient properties was developed and used to analyse neuronal firing activity. It was found that LRRK2-G2019S mutants have shortened inter-spike intervals and an increased rate of spontaneous calcium transient induction than control cell lines. [less ▲]

Detailed reference viewed: 124 (8 UL)