316 research outputs found

    Analysis and design of current regulators using complex vectors

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    Evaluation of saliency tracking as an alternative for health monitoring in PMSM-drives under nonstationary conditions

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    This paper evaluates the capability of saliency tracking to assess the health condition of permanent magnet synchronous motor (PMSM) drives operating under nonstationary conditions. The evaluated scheme is based on saliency tracking methods, which are associated to the accurate sensorless control of AC drives without zero speed limitations. In this work two representative saliency tracking architectures are evaluated: High Frequency (HF) injection, and PWM transient excitation. Although a monitoring approach based on HF injection was previously reported, a comparative study to evaluate the most representative saliency tracking schemes to assess health condition in drives was still missing. The aim of this work is to fill out this gap by evaluating and comparing two saliency-based monitoring schemes (one based on HF-injection and the other based on PWM transient excitation) to evaluate their performance in the presence of inter-turn winding faults. Simulation and experimental results are presented which confirm that both schemes offer excellent detection capabilities and that are suitable for drives operating under nonstationary conditions including standstill operation. Significant differences are also found for instance, PWM transient excitation offers improved accuracy since the approach is not affected by the inverter nonlinearities and is suitable for full-speed range applications. The main drawback here is complexity and the hardware requirements. Schemes based on HF-injection proved to be very simple and provide comparable results; however a good performance is only guaranteed for the zero-to-medium speed range applications which limit their applicability

    Growing Tungsten Nanophases on Carbon Spheres Doped with Nitrogen. Behaviour as Electro-Catalysts for Oxygen Reduction Reaction

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    This research was funded by the Junta de Andalucia [grant numbers RNM172 and P18-RTJ-2974].This work shows the preparation of carbon nanospheres with a high superficial nitrogen content (7 wt.%), obtained by a simple hydrothermal method, from pyrocatechol and formaldehyde, around which tungsten nanophases have been formed. One of these nanophases is tungsten carbide, whose electro-catalytic behavior in the ORR has been evaluated together with the presence of nitrogen surface groups. Both current and potential kinetic density values improve considerably with the presence of tungsten, despite the significant nitrogen loss detected during the carbonization treatment. However, the synergetic effect that the WC has with other electro-catalytic metals in this reaction cannot be easily evaluated with the nitrogen in these materials, since both contents vary in opposite ways. Nevertheless, all the prepared materials carried out oxygen electro-reduction by a mixed pathway of two and four electrons, showing remarkable electro-catalytic behavior.Junta de Andalucia RNM172 P18-RTJ-297

    Comparison of Saliency-Based Sensorless Control Techniques for AC Machines

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    Differential Estrogenic Effects of the Persistent Organochlorine Pesticides Dieldrin, Endosulfan, and Lindane in Primary Neuronal Cultures

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    The organochlorine chemicals endosulfan, dieldrin, and ghexachlorocyclohexane (lindane) are persistent pesticides to which people are exposed mainly via diet. Their antagonism of the g-aminobutyric acid-A (GABAA) receptor makes them convulsants. They are also endocrine disruptors because of their interaction with the estrogen receptor (ER). Here, we study the effects of dieldrin, endosulfan, and lindane on ERs in primary cultures of cortical neurons (CN) and cerebellar granule cells (CGC). All the compounds tested inhibited the binding of [3H]-estradiol to the ER in both CN and CGC, with dieldrin in CGC showing the highest affinity.We also determined the effects of the pesticides on protein kinase B (Akt) and extracellular-regulated kinase 1 and 2 (ERK1/2) phosphorylation. Dieldrin and endosulfan increased Akt phosphorylation in CN, which was inhibited by the ERb antagonist 4-[2-phenyl-5,7- bis(trifluoromethyl)pyrazolo[1,5-a]pyrimidin-3-yl]phenol. Instead, Akt and ERK1/2 phosphorylation induced by dieldrin in CGC was mediated by multiple activation of ERa, ERb, and G protein– coupled receptor 30. Lindane did not activate these pathways, but it inhibited estradiol-mediated Akt and ERK1/2 activation. In CN, all the chemicals activated ERK1/2 through a mechanism involving GABAA and glutamate receptors. Long-term exposure to these pesticides reduced the levels of ERa, but not of ERb. Moreover, extracts of CN treated with endosulfan, dieldrin, or lindane induced cell proliferation in MCF-7 human breast cancer–derived cells, whereas only extracts of CGC treated with dieldrin induced MCF-7 cell proliferation. Overall, the observed alterations on ER-mediated signaling and ER levels in neurons might contribute to the neurotoxicity of these organochlorine pesticides.Ministry of Health(FIS 061212, FIS 10/0453); CIBERESP (AA08-001); Generalitat de Catalunya (2009/SGR/214); Consejerı ´a de Innovacio´n, Ciencia y Empresa de la Junta de Andalucı´a (P09-CTS-5488).Peer reviewe

    Osteogenic differentiation of human dental pulp stem cells in decellularised adipose tissue solid foams

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    3D cell culture systems based on biological scaffold materials obtainable from both animal and human tissues constitute very interesting tools for cell therapy and personalised medicine applications. The white adipose tissue (AT) extracellular matrix (ECM) is a very promising biomaterial for tissue engineering due to its easy accessibility, malleability and proven biological activity. In the present study, human dental pulp stem cells (hDPSCs) were combined in vitro with ECM scaffolds from porcine and human decellularised adipose tissues (pDAT, hDAT) processed as 3D solid foams, to investigate their effects on the osteogenic differentiation capacity and bone matrix production of hDPSCs, compared to single-protein-based 3D solid foams of collagen type I and conventional 2D tissue-culture-treated polystyrene plates. pDAT solid foams supported the osteogenic differentiation of hDPSCs to similar levels to collagen type I, as assessed by alkaline phosphatase and alizarin red stainings, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) and osteocalcin/bone gamma-carboxyglutamate protein (BGLAP) immunostaining. Interestingly, hDAT solid foams showed a markedly lower capacity to sustain hDPSC osteogenic differentiation and matrix calcification and a higher capacity to support adipogenesis, as assessed by RT-qPCR and oil red O staining. White ATs from both human and porcine origins are relatively abundant and available sources of raw material to obtain high quality ECM-derived biomedical products. These biomaterials could have promising applications in tissue engineering and personalised clinical therapy for the healing and regeneration of lesions involving not only a loss of calcified bone but also its associated soft non-calcified tissues.This research was supported by the Basque Government (ELKARTEK program PLAKA KK2019-00093; to NB), MICINN retos I+D+i (PID2019- 104766RB-C21, to JRP) and UPV/EHU (PPGA20/22; to FU, GI). The authors would like to thank the staff members of the SGIKER services of the UPV/EHU: Lipidomic service (Beatriz Abad) and Analytical Microscopy (Ricardo Andrade, Alejandro Díez-Torre and Irene Fernández) for their technical assistance

    Comparing different methods to retrieve cloud top height from Meteosat satellite data

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    Cloud parameters such as the Cloud Top Height (CTH), Cloud Top Temperature (CTT), emissivity, particle size and optical depth have always been matter of interest for the atmospheric community. Particularly the CTH provides information leading to better understand the cloud radiative effects. Although there are many meteorological satellites providing the CTH, there are other sensors, not devoted to this purpose, that give some information from which this crucial parameter can be estimated. In this contribution we will describe three different methodologies to retrieve the CTH. The first technique is based on stereo-vision algorithms and requires two different views of the same scene and does not need of extra atmospheric information. In the second one, brightness temperatures in two IR spectral bands are converted to real cloud temperature by means of the proposed algorithms. From the CTT, the CTH is estimated using temperature vertical profiles (measured or modeled). The third technique retrieves the CTH from the output parameters of post event simulations performed by a Numerical Weather Prediction (NWP) model that in this work will be the mesoscale model WRF (Weather Research Forecast). This article presents a preliminary work, in which the heights retrieved by the three methodologies applied to the geostationary satellite Meteosat 10 are compared with the heights given by MODIS sensor installed on the polar satellite AQUA. This promising results show that valuable information about CTH can be retrieved from Meteosat which provide high frequency and large scale data useful for weather and climate research
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