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Antonopoulos A.,University of Aegean | Renzo M.,University of L'Aquila | Renzo M.,University Paris - Sud | Verikoukis C.,Technical University of Catalonia | Verikoukis C.,University of Barcelona
IEEE Wireless Communications | Year: 2013

The emergence of heterogeneous networks (HetNets) as an enabling paradigm for ubiquitous wireless communication has further reinforced the concept of medium range cooperation among the end users. This trend, along with the need for bidirectional communication, has triggered the design of new Network Coding (NC)-aided Medium Access Control (MAC) protocols that benefit both the throughput and the energy efficiency in the system. However, the vast majority of MAC protocols are usually designed and analyzed under simplified channel models, ignoring the severe effect of realistic physical (PHY) layer conditions on the wireless communication. In this article, we focus on the impact of correlated long-term slow fading (shadowing) on the performance of distributed wireless systems. As a case study, we discuss in detail the performance of a cooperative NC-aided Automatic Repeat reQuest (ARQ) MAC protocol under correlated shadowing conditions. Our results reveal interesting trade-offs between throughput and energy efficiency, highlighting the importance of considering the slow fading effect in the design of cooperative MAC protocols. © 2013 IEEE.

Awan A.J.,KTH Royal Institute of Technology | Brorsson M.,KTH Royal Institute of Technology | Vlassov V.,KTH Royal Institute of Technology | Ayguade E.,Technical University of Catalonia
Proceedings - 2015 IEEE 5th International Conference on Big Data and Cloud Computing, BDCloud 2015 | Year: 2015

In last decade, data analytics have rapidly progressed from traditional disk-based processing to modern in-memory processing. However, little effort has been devoted at enhancing performance at micro-architecture level. This paper characterizes the performance of in-memory data analytics using Apache Spark framework. We use a single node NUMA machine and identify the bottlenecks hampering the scalability of workloads. We also quantify the inefficiencies at micro-architecture level for various data analysis workloads. Through empirical evaluation, we show that spark workloads do not scale linearly beyond twelve threads, due to work time inflation and thread level load imbalance. Further, at the micro-architecture level, we observe memory bound latency to be the major cause of work time inflation. © 2015 IEEE.

Liaison aimed to accelerate development of fog computing technology and proofs of concept BARCELONA, SPAIN--(Marketwired - Oct 26, 2016) - Barcelona Supercomputing Center (BSC) and the OpenFog Consortium (OpenFog) announced today that they will actively collaborate in order to accelerate proof of concepts and technical development of fog computing. Fog computing is the architecture for computing, storage, control and networking that distributes those services closer to end users along the cloud-to-things continuum, and is particularly useful in Internet of Things (IoT), artificial intelligence and 5G applications. The announcement was made at IOT Solutions World Congress, where the OpenFog Consortium is running a technical panel discussion on fog computing. With this agreement, BSC and OpenFog will co-create and co-promote fog computing concepts and architectures and organize joint industry activities to promote fog computing. BSC will have access to OpenFog's testbeds while OpenFog will have access to BSC's supercomputing facilities to help test new concepts and fog computer-based use cases. "To reinforce and continue with our pioneering work on fog computing that started in 2008, we pursue synergies between leading technology companies and academic and scientific community. By collaborating with the OpenFog Consortium, we will be able to contribute to the consolidation of an IoT platform for the interoperability for consumers, business, industry and research. We are looking forward to a constructive and fruitful collaborations with all OpenFog members," says Mario Nemirovsky, Network Processors Manager at BSC. "This collaboration agreement makes sense on so many levels," says Helder Antunes, chairman of the OpenFog Consortium. "Some of our members have already been collaborating with BSC on fog deployments - for example, Cisco, Nebbiolo Technologies and PrismTech's work with BSC right in the city of Barcelona. Now we can accelerate industry adoption by sharing the OpenFog reference architecture with BSC's high performance computing to prove new use case scenarios enabled by fog computing, leading to more rapid exploration of emerging, technically-challenging scenarios in IoT, AI and 5G." Barcelona Supercomputing Center (BSC) is the national supercomputing center in Spain. BSC specializes in high performance computing (HPC), and its mission is two-fold: to provide infrastructure and supercomputing services to European scientists, and to generate knowledge and technology to transfer to business and society. BSC is a Severo Ochoa Center of Excellence and a first level hosting member of the European research infrastructure PRACE (Partnership for Advanced Computing in Europe). BSC also manages the Spanish Supercomputing Network (RES). BSC is a consortium that includes Spanish Government, Catalan Government and Technical University of Catalonia - Barcelona Tech. More information on www.bsc.es The OpenFog Consortium was formed to accelerate the deployment of fog computing technologies through the development of an open architecture that identifies core technologies and capabilities such as distributed computing, networking and storage that will support intelligence at the edge of IoT. The OpenFog Consortium was formed by ARM, Cisco, Dell, Intel, Microsoft Corp, and Princeton University in November 2015, and has members in North America, Europe and Asia. For more information, visit www.openfogconsortium.org and on Twitter @openfog.

Vargas R.,Barcelona Supercomputing Center | Vargas R.,Technical University of Catalonia | Quinones E.,Barcelona Supercomputing Center | Marongiu A.,ETH Zurich
Proceedings -Design, Automation and Test in Europe, DATE | Year: 2015

Next-generation many-core embedded platforms have the chance of intercepting a converging need for high performance and predictability. Programming methodologies for such platforms will have to promote predictability as a first-class design constraint, along with features for massive parallelism exploitation. OpenMP, increasingly adopted in the embedded systems domain, has recently evolved to deal with the programmability of heterogeneous many-cores, with mature support for fine-grained task parallelism. While tasking is potentially very convenient for coding real-time applications modeled as periodic task graphs, OpenMP adopts an execution model completely agnostic to any timing requirement that the target application may have. In this position paper we reason about the suitability of the current OpenMP v4 specification and execution model to provide timing guarantees in many-cores. © 2015 EDAA.

Martin-Vide J.-P.,University of Barcelona | Roca M.,Technical University of Catalonia | Alvarado-Ancieta C.A.,Technical University of Delft
Proceedings of the Institution of Civil Engineers: Water Management | Year: 2010

This paper presents laboratory tests using riprap as a countermeasure for river bend scouring. The bank is a vertical wall in a sharp bend. The riprap is a horizontal apron extended at the toe of this wall. The aims of the tests are to describe the behaviour of riprap in sharp bend flow and to examine how the main flow characteristics are affected by the riprap behaviour. The experimental results show that flexible riprap is able to adapt to bed deformation in river bends by tilting, spreading and paving a transverse slope which ensures that the bank remains protected. Even a blanket located at the initial bed elevation provides efficient protection if it is thick enough. The tests also show that the mainstream velocity and shear stress above the riprap increase after riprap adaptation.

Mendez-Monroy P.E.,National Autonomous University of Mexico | Velasco M.,Technical University Of Catalonia
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2012

Varying time delays, packet loss and variable sampling interval degrade the performance of control loops closed over communication networks, (Networked Control System, NCS), the problem is more complicated with is necessary to detect faults because is possible to confuse a fault with a network imperfection effect. To compensate the negative effects of network and get good fault detection, in this paper we propose a fuzzy observer for networked control systems with synchronization at the actuation node to detect fault. Using the one-shot model has some benefits such as consider delays longer than actuation period instead of consider delays less than sampling period and variable sampling interval. © 2012 IFAC.

Rossignac J.,Georgia Institute of Technology | Vinacua A.,Technical University of Catalonia
ACM Transactions on Graphics | Year: 2011

We propose to measure the quality of an affine motion by its steadiness, which we formulate as the inverse of its Average Relative Acceleration (ARA). Steady affine motions, for which ARA= 0, include translations, rotations, screws, and the golden spiral. To facilitate the design of pleasing in-betweening motions that interpolate between an initial and a final pose (affine transformation), B and C, we propose the Steady Affine Morph (SAM), defined as A t ○ B with A = C ○ B -1. A SAM is affine-invariant and reversible. Itpreserves isometries (i.e., rigidity), similarities, and volume. Its velocity field is stationary both in the global and the local (moving) frames. Given a copy count, n, the series of uniformly sampled poses, A i/n ○ B, of a SAM form a regular pattern which may be easily controlled by changing B, C, or n, and where consecutive poses are related by the same affinity A 1/n. Although a real matrix A t does not always exist, we show that it does for a convex and large subset of orientation-preserving affinities A. Our fast and accurate Extraction of Affinity Roots (EAR) algorithm computes A t, when it exists, using closed-form expressions in two or in three dimensions. We discuss SAM applications to pattern design and animation and to key-frame interpolation. © 2011 ACM.

Gallego J.,Technical University of Catalonia | Salvador J.,Technical University of Catalonia | Casas J.R.,Technical University of Catalonia | Pardas M.,Technical University of Catalonia
Proceedings - International Conference on Image Processing, ICIP | Year: 2011

In this paper we present a novel foreground segmentation and 3D reconstruction system for multi-view scenarios. The system achieves correct 3D object reconstruction even when foreground segmentation presents critical misses in some of the views. We introduce the spatial redundancy of the multi-view data into the foreground segmentation process by combining segmentation and the 3D reconstruction in a two steps workflow. First, the segmentation of the objects in each view uses a monocular, region-based foreground segmentation in a MAP-MRF framework for foreground, background and shadow classes. Next, we compute an iterative volume reconstruction in a 3D tolerance loop, obtaining an iteratively enhanced SfS volume. Foreground segmentation is improved by updating the foreground model of each view at each iteration. The results presented in this paper show the improved foreground segmentation and the reduction of errors in the reconstruction of the volume. © 2011 IEEE.

Lloveras J.,Technical University of Catalonia
Proceedings of the 15th International Conference on Engineering and Product Design Education: Design Education - Growing Our Future, EPDE 2013 | Year: 2013

This paper evaluates the effectiveness of using rounds of questions posed by work groups of an Engineering Project course after their project presentations. Before, students were offered the possibility of putting questions to speakers before the lecturer asked his/her own questions. Unfortunately, student participation was often very low and questions sometimes lacked depth, or were irrelevant or poorly stated. However, question time is a good moment to raise doubts, which can help presenters think about their project. That is, student and lecturer participation can open the minds of presenters to new ideas about their own work. Students' questions may even expand on the lecturer's questions and also create a spirit of positive criticism among students as part of student training. To enhance student participation, a controlled process is followed. Work groups think up and write questions which are later included in their project portfolio. Finally, student questionnaires are used to assess the process. Details of questionnaires and results, as well as an example of a project, are given elsewhere in the paper.

Palou G.,Technical University of Catalonia | Salembier P.,Technical University of Catalonia
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2013

As early stage of video processing, we introduce an iterative trajectory merging algorithm that produces a region-based and hierarchical representation of the video sequence, called the Trajectory Binary Partition Tree (BPT). From this representation, many analysis and graph cut techniques can be used to extract partitions or objects that are useful in the context of specific applications. In order to define trajectories and to create a precise merging algorithm, color and motion cues have to be used. Both types of informations are very useful to characterize objects but present strong differences of behavior in the spatial and the temporal dimensions. On the one hand, scenes and objects are rich in their spatial color distributions, but these distributions are rather stable over time. Object motion, on the other hand, presents simple structures and low spatial variability but may change from frame to frame. The proposed algorithm takes into account this key difference and relies on different models and associated metrics to deal with color and motion information. We show that the proposed algorithm outperforms existing hierarchical video segmentation algorithms and provides more stable and precise regions. © 2013 IEEE.

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