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See detailHybrid Cellular Genetic Algorithm for Global Trajectory Optimization Problem
Danoy, Grégoire UL; Gaspar Pinto, Frederico; Dorronsoro, Bernabé UL et al

in International Conference on Metaheuristics and Nature Inspired Computing (2010)

Detailed reference viewed: 73 (5 UL)
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See detailA Hybrid Cognitive Transceiver Architecture: Sensing-Throughput Tradeoff
Sharma, Shree Krishna UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in Proceedings of 9th International Conference on Cognitive Radio Oriented Wireless Networks (2014, June)

Spectrum Sensing (SS) and underlay have been considered as two important techniques for enabling the spectral coexistence of the licensed and unlicensed wireless communication systems. The SS only ... [more ▼]

Spectrum Sensing (SS) and underlay have been considered as two important techniques for enabling the spectral coexistence of the licensed and unlicensed wireless communication systems. The SS only approach ignores the interference tolerance capability of the Primary Users (PUs) while assuming the bursty PU traffic whereas the possibility of having secondary transmission with full power is neglected in an underlay based approach. To address this, it’s crucial to investigate suitable hybrid spectrum awareness and transmission strategies which can overcome the aforementioned drawbacks and achieve higher secondary throughput while protecting the PUs. In this context, we propose a hybrid cognitive transceiver which combines the SS approach with the power control based underlay approach. Furthermore, we evaluate the performance of the proposed hybrid approach considering both periodic sensing and simultaneous sensing/transmission schemes. Moreover, sensing-throughput tradeoff for the proposed hybrid approach is investigated and the performance is compared with the conventional SS only approaches in terms of the achievable throughput. It is shown that the proposed scheme can achieve a significant improvement in the secondary throughput over the conventional approaches while respecting the interference constraints of the PUs. [less ▲]

Detailed reference viewed: 158 (4 UL)
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See detailA hybrid CPU-GPU parallelization scheme of variable neighborhood search for inventory optimization problems
Antoniadis, Nikolaos UL; Sifaleras, Angelo

in Electronic Notes in Discrete Mathematics (2017), 58

In this paper, we study various parallelization schemes for the Variable Neighborhood Search (VNS) metaheuristic on a CPU-GPU system via OpenMP and OpenACC. A hybrid parallel VNS method is applied to ... [more ▼]

In this paper, we study various parallelization schemes for the Variable Neighborhood Search (VNS) metaheuristic on a CPU-GPU system via OpenMP and OpenACC. A hybrid parallel VNS method is applied to recent benchmark problem instances for the multi-product dynamic lot sizing problem with product returns and recovery, which appears in reverse logistics and is known to be NP-hard. We report our findings regarding these parallelization approaches and present promising computational results. [less ▲]

Detailed reference viewed: 37 (6 UL)
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See detail"Hybrid Histories". Versuch einer kritischen Standortbestimmung der Mediengeschichte
Fickers, Andreas UL

in Annali dell'Istituto Storico Italo-Germanico in Trento = Jahrbuch des Italienisch-Deutschen Historischen Instituts in Trient (2018), 44(1), 117-132

This article aims at offering a historiographical sketch of the emergence and development of media history as a sub-discipline of historical research. By retracing important disciplinary traditions and by ... [more ▼]

This article aims at offering a historiographical sketch of the emergence and development of media history as a sub-discipline of historical research. By retracing important disciplinary traditions and by reflecting on the impact that various "turns" in humanities had on media historical scholarship, the author identifies central concepts, methodological approaches, and thematic focal points that characterize the field. Finally, new challenges of doing media history in the digital age - such as transmedia storytelling and media convergence are discussed. [less ▲]

Detailed reference viewed: 127 (13 UL)
See detail"Hybrid Histories": per una collocazione critica della storia dei media
Fickers, Andreas UL

in Cornelissen, Christoph; D'Ottavio, Gabriele (Eds.) Germania e Italia. Sguardi incrociati sulla storiografia (2019)

This article reflects on the history of media history, e.g. its main topics, methodologies and conceptual approaches. It ends on a series of ideas how to develop the field in the age of digital tools and ... [more ▼]

This article reflects on the history of media history, e.g. its main topics, methodologies and conceptual approaches. It ends on a series of ideas how to develop the field in the age of digital tools and technologies. [less ▲]

Detailed reference viewed: 38 (4 UL)
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See detailHybrid Histories: Historicizing the Home Movie Dispositif
van der Heijden, Tim UL

in Aasman, Susan; Fickers, Andreas; Wachelder, Joseph (Eds.) Materializing Memories: Dispositifs, Generations, Amateurs (2018)

In media historiography, there have generally been two approaches to historicize past media technologies and their practices. Whereas media historians generally focus on historical changes by maintaining ... [more ▼]

In media historiography, there have generally been two approaches to historicize past media technologies and their practices. Whereas media historians generally focus on historical changes by maintaining a diachronic perspective on how media technologies and practices develop over time, media archaeologists commonly adopt a synchronic perspective in (re)constructing parallel or alternative histories. This chapter aims to explore and propose a third approach to media historiography, which departs from the notion of “hybridity”: the intermingling and co-existence of old and new media technologies, user practices, and discourses as evolving in an ongoing process. Building on some of the empirical and conceptual results of my research on the home movie as a twentieth-century family memory practice, I develop the argument that a “hybrid media historiography” enables one to grasp the complex interrelations and dynamics between media technologies, user practices, and discourses in more precise and comprehensive ways by maintaining both a diachronic and synchronic perspective in studying media transitions. By looking specifically at how the transition from amateur film to home video gradually constituted a new home movie dispositif in the 1970s and 1980s, I will underline the heuristic potential of hybridity as analytical lens in media historical research. [less ▲]

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See detailHybrid Histories: Technologies of Memory and the Cultural Dynamics of Home Movies, 1895-2005
van der Heijden, Tim UL

Doctoral thesis (2018)

This dissertation analyses the cultural dynamics of home movies in the twentieth century. It investigates how various generations have recorded their family memories on film, video and digital media, and ... [more ▼]

This dissertation analyses the cultural dynamics of home movies in the twentieth century. It investigates how various generations have recorded their family memories on film, video and digital media, and, more specifically, how changes in these “technologies of memory” have shaped new forms of home movie making and screening. Covering the period from the invention of the film camera in the late nineteenth century, the introduction of 9.5mm, 16mm, 8mm small-gauges and Super 8 film technologies for amateurs, via home video to digital media technologies, this study addresses the complex interrelations between the materiality of film, video and digital media technologies, their social usages and cultural meanings from a long-term historical perspective. Focusing on specific periods of transition, it becomes clear that different media technologies, user practices and discourses not only succeed each other in time, but also increasingly interrelate, interact or even transform each other. Maintaining both a diachronic and a synchronic perspective on media transitions, this dissertation proposes an alternative form of media historiography that rethinks media histories beyond the frameworks of change and continuity by perceiving hybridity as a constant factor in media historical development. [less ▲]

Detailed reference viewed: 212 (19 UL)
See detailHybrid Histories: Technologies of Memory and the Cultural Dynamics of Home Movies, 1895-2005 (presentation)
van der Heijden, Tim UL

Scientific Conference (2018, May 25)

In this presentation, I will present my PhD dissertation on the cultural dynamics of home movies in the twentieth century. In my research, I have investigated how various generations have recorded their ... [more ▼]

In this presentation, I will present my PhD dissertation on the cultural dynamics of home movies in the twentieth century. In my research, I have investigated how various generations have recorded their memories on film, video and digital media, and, more specifically, how changes in these “technologies of memory” have shaped new forms of home movie making and screening. Covering the period from the invention of the film camera in the late nineteenth century, the introduction of 9.5mm, 16mm, 8mm small-gauges and Super 8 film technologies for amateurs, via home video to digital media technologies, this study addresses the complex interrelations between the materiality of film, video and digital media technologies, their social usages and cultural meanings from a long-term historical perspective. Focusing on specific periods of transition, it becomes clear that different media technologies, user practices and discourses not only succeed each other in time, but also increasingly interrelate, interact or even transform each other. Maintaining both a diachronic and a synchronic perspective on media transitions, I propose an alternative form of media historiography that rethinks media histories beyond the frameworks of change and continuity by perceiving hybridity as a constant factor in media historical development. [less ▲]

Detailed reference viewed: 49 (5 UL)
See detailHybrid Histories: Versuch einer kritischen Standortbestimmung der Mediengeschichte
Fickers, Andreas UL

Presentation (2017, November 23)

Detailed reference viewed: 29 (0 UL)
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See detailHybrid lattice-continuum approach for medical simulations
Bui, Huu Phuoc; Bordas, Stéphane UL

Presentation (2015, May)

For problems in which discontinuities are dominant such as fracture of quasi-brittle materials or cutting of soft tissues, discrete approach is a more suitable than the continuum one since discontinuities ... [more ▼]

For problems in which discontinuities are dominant such as fracture of quasi-brittle materials or cutting of soft tissues, discrete approach is a more suitable than the continuum one since discontinuities can be represented naturally. Lattice models are the good candidate, especially when the mesostructure of the studied material needs to be modeled explicitly. Indeed, the outcome of cutting, tearing, needle insertion and similar operations on soft tissues is significantly affected by the microstructure of the material. In this contribution, a master/slave approach is used in order to couple finite elements and lattice approach in a multi-domain and multiscale framework. [less ▲]

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See detailA Hybrid Machine Learning and Schedulability Method for the Verification of TSN Networks
Mai, Tieu Long UL; Navet, Nicolas UL; Migge, Jörn

in 15th IEEE International Workshop on Factory Communication Systems (WFCS2019) (2019, March)

Machine learning (ML), and supervised learning in particular, can be used to learn what makes it hard for a network to be feasible and try to predict whether a network configuration will be feasible ... [more ▼]

Machine learning (ML), and supervised learning in particular, can be used to learn what makes it hard for a network to be feasible and try to predict whether a network configuration will be feasible without executing a conventional schedulability analysis. A disadvantage of ML-based timing verification with respect to schedulability analysis is the possibility of "false positives": configurations deemed feasible while they are not. In this work, in order to minimize the rate of false positives, we propose the use of a measure of the uncertainty of the prediction to drop it when the uncertainty is too high, and rely instead on schedulability analysis. In this hybrid verification strategy, the clear-cut decisions are taken by ML, while the more difficult ones are taken by a conventional schedulability analysis. Importantly, the trade-off achieved between prediction accuracy and computing time can be controlled. We apply this hybrid verification method to Ethernet TSN networks and obtain, for instance in the case of priority scheduling with 8 traffic classes, a 99% prediction accuracy with a speedup factor of 5.7 with respect to conventional schedulability analysis and a reduction of 46% of the false positives compared to ML alone. [less ▲]

Detailed reference viewed: 203 (25 UL)
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See detailHybrid mesh/particle meshless method for geological flows with discontinuous transport properties
Bourantas, Georgios UL; Lavier, Luc; Claus, Susanne et al

Scientific Conference (2015, April 12)

Geodynamic modeling is an important branch of Earth Sciences. Direct observation of geodynamic processes is limited in both time and space, while on the other hand numerical methods are capable of ... [more ▼]

Geodynamic modeling is an important branch of Earth Sciences. Direct observation of geodynamic processes is limited in both time and space, while on the other hand numerical methods are capable of simulating millions of years in a matter of days on a desktop computer. The model equations can be reduced to a set of Partial Differential Equations with possibly discontinuous coefficients, governing mass, momentum and heat transfer over the domain. Some of the major challenges associated with such simulations are (1) geological time scales, which require long (in physical time) simulations using small time steps; (2) the presence of localization zones over which large gradients are present and which are much smaller than the overall physical dimensions of the computational domain and require much more refined discretization than for the rest of the domain, much like in fracture or shear band mechanics. An added difficulty is that such structures in the solution may appear after long periods of stagnant behaviour; (3) the definition of boundary conditions, material parameters and that of a suitable computational domain in terms of size; (4) a posteriori error estimation, sensitivity analysis and discretization adaptivity for the resulting coupled problem, including error propagation between different unknown fields. Consequently, it is arguable that any suitable numerical methods aimed at the solution of such problems on a large scale must be able to (i) provide ease of discretization refinement, including possible partition of unity enrichment; (ii) offer a large stability domain, so that “large” time steps can be chosen; (iii) ease of parallelization and good scalability. Our approach is to rely on “meshless” methods based on a point collocation strategy for the discretization of the set of PDEs. The method is hybrid Eulerian/Lagrangian, which enables to switch easily between stagnant periods and periods of localization. Mass and momentum equations are solved using a meshless point collocation Eulerian method, while energy equation are solved using a set of particles, distributed over the spatial domain, with the solution interpolated back to the Eulerian grid at every time step. This hybrid approach allows for the accurate calculation of fine thermal structures, through the ease of adaptivity offered by the flexibility of the particle method. The approximation space is constructed using the Discretization Correction Particle Strength Exchange (DC PSE) method. The proposed scheme gives the capability of solving flow equations (Stokes flow) in fully irregular geometries while particles, “sprinkled” in the spatial domain, are used to solve convection-diffusion problems avoiding the oscillation produced in the Eulerian approach. The resulting algebraic linear systems were solved using direct solvers. Our hybrid approach can capture sharp variations of stresses and thermal gradients in problems with a strongly variable viscosity and thermal conductivity as demonstrated through various benchmarking test cases such as the development of Rayleigh-Taylor instabilities, viscous heating and flows with non-Newtonian rheology. [less ▲]

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See detailHybrid mesh/particle meshless method for modeling geological flows with discontinuous transport properties
Bourantas, Georgios UL; Lavier, Luc; van Dam, Tonie UL et al

E-print/Working paper (2016)

In the present paper, we introduce the Finite Difference Method-Meshless Method (FDM-MM) in the context of geodynamical simulations. The proposed numerical scheme relies on the well-established FD method ... [more ▼]

In the present paper, we introduce the Finite Difference Method-Meshless Method (FDM-MM) in the context of geodynamical simulations. The proposed numerical scheme relies on the well-established FD method along with the newly developed “meshless” method and, is considered as a hybrid Eulerian/Lagrangian scheme. Mass, momentum, and energy equations are solved using an FDM method, while material properties are distributed over a set of markers (particles), which represent the spatial domain, with the solution interpolated back to the Eulerian grid. The proposed scheme is capable of solving flow equations (Stokes flow) in uniform geometries with particles, “sprinkled” in the spatial domain and is used to solve convection- diffusion problems avoiding the oscillation produced in the Eulerian approach. The resulting algebraic linear systems were solved using direct solvers. Our hybrid approach can capture sharp variations of stresses and thermal gradients in problems with a strongly variable viscosity and thermal conductivity as demonstrated through various benchmarking test cases. The present hybrid approach allows for the accurate calculation of fine thermal structures, offering local type adaptivity through the flexibility of the particle method. [less ▲]

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See detailA hybrid metal–dielectric zero mode waveguide for enhanced single molecule detection
Zambrana-Puyalto, Xavier; Ponzellini, Paolo; Maccaferri, Nicolò UL et al

in Chemical Communications (2019)

We fabricated hybrid metal–dielectric nanoslots and measured their optical response at three different wavelengths. The nanostructure is fabricated on a bilayer film formed by the sequential deposition of ... [more ▼]

We fabricated hybrid metal–dielectric nanoslots and measured their optical response at three different wavelengths. The nanostructure is fabricated on a bilayer film formed by the sequential deposition of silicon and gold on a transparent substrate. The optical characterization is done via fluorescence spectroscopy measurements. We characterized the fluorescence enhancement, as well as the lifetime and the detection volume reduction for each wavelength. We observe that the hybrid metal–dielectric nanoslots behave as enhanced zero mode waveguides in the near-infrared spectral region. Their detection volume is such that they can perform enhanced single-molecule detection at tens of μM. We compared their behavior with that of a golden ZMW, and we demonstrated that the dielectric silicon layer improves both the optical performance and the stability of the device. [less ▲]

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See detailHybrid mobility model with pheromones for UAV detection task
Kieffer, Emmanuel UL; Danoy, Grégoire UL; Bouvry, Pascal UL et al

in Hybrid mobility model with pheromones for UAV detection task (2016)

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See detailHybrid MPI+OpenMP Implementation of eXtended Discrete Element Method
Mainassara Chekaraou, Abdoul Wahid UL; Rousset, Alban UL; Besseron, Xavier UL et al

in Proc. of the 9th Workshop on Applications for Multi-Core Architectures (WAMCA'18), part of 30th Intl. Symp. on Computer Architecture and High Performance Computing (SBAC-PAD 2018) (2018, September)

The Extended Discrete Element Method (XDEM) is a novel and innovative numerical simulation technique that ex- tends classical Discrete Element Method (DEM) (which simulates the motion of granular material ... [more ▼]

The Extended Discrete Element Method (XDEM) is a novel and innovative numerical simulation technique that ex- tends classical Discrete Element Method (DEM) (which simulates the motion of granular material), by additional properties such as the chemical composition, thermodynamic state, stress/strain for each particle. It has been applied successfully to numerous industries involving the processing of granular materials such as sand, rock, wood or coke [16], [17]. In this context, computational simulation with (X)DEM has become a more and more essential tool for researchers and scientific engineers to set up and explore their experimental processes. However, increasing the size or the accuracy of a model requires the use of High Performance Computing (HPC) platforms over a parallelized implementation to accommodate the growing needs in terms of memory and computation time. In practice, such a parallelization is traditionally obtained using either MPI (distributed memory computing), OpenMP (shared memory computing) or hybrid approaches combining both of them. In this paper, we present the results of our effort to implement an OpenMP version of XDEM allowing hybrid MPI+OpenMP simulations (XDEM being already parallelized with MPI). Far from the basic OpenMP paradigm and recommendations (which simply summarizes by decorating the main computation loops with a set of OpenMP pragma), the OpenMP parallelization of XDEM required a fundamental code re-factoring and careful tuning in order to reach good performance. There are two main reasons for those difficulties. Firstly, XDEM is a legacy code devel- oped for more than 10 years, initially focused on accuracy rather than performance. Secondly, the particles in a DEM simulation are highly dynamic: they can be added, deleted and interaction relations can change at any timestep of the simulation. Thus this article details the multiple layers of optimization applied, such as a deep data structure profiling and reorganization, the usage of fast multithreaded memory allocators and of advanced process/thread-to-core pinning techniques. Experimental results evaluate the benefit of each optimization individually and validate the implementation using a real-world application executed on the HPC platform of the University of Luxembourg. Finally, we present our Hybrid MPI+OpenMP results with a 15%-20% performance gain and how it overcomes scalability limits (by increasing the number of compute cores without dropping of performances) of XDEM-based pure MPI simulations. [less ▲]

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See detailHybrid Ni/SiO2/Au dimer arrays for high-resolution refractive index sensing
Pourjamal, Sara; Kataja, Mikko; Maccaferri, Nicolò UL et al

in Nanophotonics (2018), 7(5), 905-912

We introduce a novel magnetoplasmonic sensor concept for sensitive detection of refractive index changes. The sensor consists of a periodic array of Ni/SiO2/Au direr nanodisks. Combined effects of near ... [more ▼]

We introduce a novel magnetoplasmonic sensor concept for sensitive detection of refractive index changes. The sensor consists of a periodic array of Ni/SiO2/Au direr nanodisks. Combined effects of near-field interactions between the Ni and Au disks within the individual dimers and far-field diffractive coupling between the dimers of the array produce narrow linewidth features in the magneto-optical Faraday spectrum. We associate these features with the excitation of surface lattice resonances and show that they exhibit a spectral shift when the refractive index of the surrounding environment is varied. Because the resonances are sharp, refractive index changes are accurately detected by tracking the wavelength where the Faraday signal crosses 0. Compared to random distributions of pure Ni nanodisks or Ni/SiO2/Au dimers or periodic arrays of Ni nanodisks, the sensing figure of merit of the hybrid magnetoplasmonic array is more than one order of magnitude larger. [less ▲]

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See detailA hybrid particle-mesh method for incompressible active polar viscous gels
Ramaswamy, Rajesh; Bourantas, Georgios UL; Jülicher, Frank et al

in Journal of Computational Physics (2015), 291

We present a hybrid particle-mesh method for numerically solving the hydrodynamic equations of incompressible active polar viscous gels. These equations model the dynamics of polar active agents, embedded ... [more ▼]

We present a hybrid particle-mesh method for numerically solving the hydrodynamic equations of incompressible active polar viscous gels. These equations model the dynamics of polar active agents, embedded in a viscous medium, in which stresses are induced through constant consumption of energy. The numerical method is based on Lagrangian particles and staggered Cartesian finite-difference meshes. We show that the method is second-order and first-order accurate with respect to grid and time-step sizes, respectively. Using the present method, we simulate the hydrodynamics in rectangular geometries, of a passive liquid crystal, of an active polar film and of active gels with topological defects in polarization. We show the emergence of spontaneous flow due to Fréedericksz transition, and transformation in the nature of topological defects by tuning the activity of the system. [less ▲]

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See detailHybrid plasmonic lattices with tunable magneto-optical activity
Kataja, Mikko; Pourjamal, Sara; Maccaferri, Nicolò UL et al

in Optics Express (2016), 24(4), 3652-3662

We report on the optical and magneto-optical response of hybrid plasmonic lattices that consist of pure nickel and gold nanoparticles in a checkerboard arrangement. Diffractive far-field coupling between ... [more ▼]

We report on the optical and magneto-optical response of hybrid plasmonic lattices that consist of pure nickel and gold nanoparticles in a checkerboard arrangement. Diffractive far-field coupling between the individual emitters of the lattices results in the excitation of two orthogonal surface lattice resonance modes. Local analyses of the radiation fields indicate that both the nickel and gold nanoparticles contribute to these collective resonances and, thereby, to the magneto-optical activity of the hybrid arrays. The strong effect of noble metal nanoparticles on the magneto-optical response of hybrid lattices opens up new avenues for the realization of sensitive and tunable magneto-plasmonic nanostructures. [less ▲]

Detailed reference viewed: 68 (2 UL)