437 research outputs found

    An experimental study of the feasibility of phase‐based video magnification for damage detection and localisation in operational deflection shapes

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    Optical measurements from high‐speed, high‐definition video recordings can be used to define the full‐field dynamics of a structure. By comparing the dynamic responses resulting from both damaged and undamaged elements, structural health monitoring can be carried out, similarly as with mounted transducers. Unlike the physical sensors, which provide point‐wise measurements and a limited number of output channels, high‐quality video recording allows very spatially dense information. Moreover, video acquisition is a noncontact technique. This guarantees that any anomaly in the dynamic behaviour can be more easily correlated to damage and not to added mass or stiffness due to the installed sensors. However, in real‐life scenarios, the vibrations due to environmental input are often so small that they are indistinguishable from measurement noise if conventional image‐based techniques are applied. In order to improve the signal‐to‐noise ratio in low‐amplitude measurements, phase‐based motion magnification has been recently proposed. This study intends to show that model‐based structural health monitoring can be performed on modal data and time histories processed with phase‐based motion magnification, whereas unamplified vibrations would be too small for being successfully exploited. All the experiments were performed on a multidamaged box beam with different damage sizes and angles

    Unified Inverse Depth Parametrization for Monocular SLAM

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    3D Real-Time Reconstruction using the Cloud

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    This work presents a 3D real-time reconstruction based on a visual SLAM (Simultaneous Localization and Mapping) approach using a RGBD camera. The proposed system aims to create a 3D model of an environment using a low-power computer and Amazon EC2 (Elastic Compute Cloud) server for computation offloading

    The Rosario dataset: Multisensor data for localization and mapping in agricultural environments

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    In this paper we present the Rosario dataset, a collection of sensor data for autonomous mobile robotics in agricultural scenes. The dataset is motivated by the lack of realistic sensor readings gathered by a mobile robot in such environments. It consists of six sequences recorded in soybean fields showing real and challenging cases: highly repetitive scenes, reflection, and burned images caused by direct sunlight and rough terrain among others. The dataset was conceived in order to provide a benchmark and contribute to the agricultural simultaneous localization and mapping (SLAM)/odometry and sensor fusion research. It contains synchronized readings of several sensors: wheel odometry, inertial measurement unit (IMU), stereo camera, and a Global Positioning System real-time kinematics (GPS-RTK) system. The dataset is publicly available from http://www.cifasis-conicet.gov.ar/robot/

    MULTI OPTICAL TRANSITION RADIATION SYSTEM FOR ATF2 ∗

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    In this paper we describe the design, installation and first calibration tests of a Multi Optical Transition Radiation System in the beam diagnostic section of the Extraction (EXT) line of ATF2, close to the multi wire scanner system. This system will be a valuable tool for measuring beam sizes and emittances coming from the ATF Damping Ring. With an optical resolution of about 2μm an original OTR design (OTR1X) located after the septum at the entrance of the EXT line demonstrated the ability to measure a5.5μm beam size in one beam pulse and to take many fast measurements. This gives the OTR the ability to measure the beam emittance with high statistics, giving a low error and a good understanding of emittance jitter. Furthermore the nearby wire scanners will be a definitive test of the OTR as a beam emittance diagnostic device. The multi-OTR system design proposed here is based on the existing OTR1X

    A step ahead on efficient microwave heating for kaolinite

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    [EN] The thermal evolution of kaolin clay under microwave radiation shows an unexpected large heating rate up to 500 degrees C/min for temperatures > 650 degrees C. Such heating rate is associated with a resistivity drop of > 10(3) Omega.m observed after the dehydroxylation process of the kaolin structure. The high efficiency of the microwave heating effect is correlated with the presence of surface carriers that absorbs microwaves electromagnetic field. The layered structure of the clay-based materials allows the appearance of charge carriers at the surface of the crystal lattice that is electromagnetically activated. This effect represents a breakthrough in the efficient use of microwaves energy in order to produce efficient thermal treatments in large volume of non-metallic minerals with a drastic reduction of the greenhouse gasses for mass production industries.The authors express their thanks to the project MAT-2017-86450-C4-1-R from the Spanis Goverment for the financial support.Reinosa, JJ.; García-Baños, B.; Catalá Civera, JM.; Fernández Lozano, JF. (2019). A step ahead on efficient microwave heating for kaolinite. Applied Clay Science. 168:237-243. https://doi.org/10.1016/j.clay.2018.11.001S23724316

    Fine grained pointing recognition for natural drone guidance

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    Human action recognition systems are typically focused on identifying different actions, rather than fine grained variations of the same action. This work explores strategies to identify different pointing directions in order to build a natural interaction system to guide autonomous systems such as drones. Commanding a drone with hand-held panels or tablets is common practice but intuitive user-drone interfaces might have significant benefits. The system proposed in this work just requires the user to provide occasional high-level navigation commands by pointing the drone towards the desired motion direction. Due to the lack of data on these settings, we present a new benchmarking video dataset to validate our framework and facilitate future research on the area. Our results show good accuracy for pointing direction recognition, while running at interactive rates and exhibiting robustness to variability in user appearance, viewpoint, camera distance and scenery

    Twisted One-Dimensional Charge Transfer and Related Y-Shaped Chromophores with a 4 H-Pyranylidene Donor: Synthesis and Optical Properties

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    Three series of push-pull derivatives bearing 4H-pyranylidene as electron donor group and a variety of acceptors were designed. On one hand, one-dimensional chromophores with a thiophene ring (series 1H) or 5-dimethylaminothiophene moiety (series 1N) as an auxiliary donor, non-coplanar with the p-conjugated system, were synthesized. On the other hand, related two-dimensional (2D) Y-shaped chromophores (series 2) were also prepared to compare how the diverse architectures affect the electrochemical, linear, and second-order nonlinear optical (NLO) properties. The presence of the 5-dimethylaminothiophene moiety in the exocyclic C= C bond of the pyranylidene unit gives rise to oxidation potentials rarely low, and the protonation (with an excess of trifluoroacetic acid) of its derivatives results in the apparition of a new blue-shifted band in the UV-visible spectra. The analysis of the properties of derivatives with and without the additional thiophene ring shows that this auxiliary donor leads to a higher NLO response, accompanied by an enhanced transparency. Y-shaped chromophores of series 2 present a blue-shifted absorption, higher molar extinction coefficients, and higher Eox values compared to their linear twisted counterparts. As concerns NLO properties, 2D Y-shaped architecture gives rise to somewhat lower µß values (except for thiobarbiturate derivatives)

    Preface

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    In the Iberian Peninsula, five official languages co-exist: Basque, Catalan,Galician, Portuguese and Spanish. Fostering multi-linguality and establishingstrong links among the linguistic resources developed for each language of theregion is essential. Additionally, a lack of published resources in some of theselanguages exists. Such lack propitiates a strong inter-relation between themand higher resourced languages, such as English and Spanish.In order to favour the intra-relation among the peninsular languages as wellas the inter-relation between them and foreign languages, different purposemultilingual NLP tools need to be developed.Interesting topics to beresearched include, among others, analysis of parallel and comparable corpora,development of multilingual resources, and language analysis in bilingualenvironments and within dialectal variations.With the aim of solving these tasks, statistical, linguistic and hybrid ap-proaches are proposed. Therefore, the workshop addresses researchers fromdifferent fields of natural language processing/computational linguistics: textmining, machine learning, pattern recognition, information retrieval andmachine translation.The research in this proceedings includes work in all of the official languages ofthe Iberian Peninsula. Moreover, interactions with English are also included.Wikipedia has shown to be an interesting resource for different tasks and hasbeen analysed or exploited in some contributions.Most of the regions of the Peninsula are represented by the authors of thecontributions. The distribution is as follows: Basque Country (2 authors),Catalonia (7 authors), Galicia (4 authors), Portugal (2 authors) and Valencia(5 authors). Interestingly, those regions where Spanish is the only officiallanguage are not represented. It is worth noting that authors working beyondthe Peninsula have also contributed to this workshop, including: Argentina (3authors), Finland (1 author), France (2 authors), Mexico (1 author), Singapore(1 author), and USA (6 authors)
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