576 research outputs found

    A Novel PMSM Hybrid Sensorless Control Strategy for EV Applications Based on PLL and HFI

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    In this paper, a novel hybrid sensorless control strategy for Permanent Magnet Synchronous Machine (PMSM) drives applied to Electric Vehicles (EV) is presented. This sensorless strategy covers the EV full speed range and also has speed reversal capability. It combines a High Frequency Injection (HFI) technique for low and zero speeds, and a Phase-Locked Loop (PLL) for the medium and high speed regions. A solution to achieve smooth transitions between the PLL and the HFI strategies is also proposed, allowing to correctly detect the rotor position polarity when HFI takes part. Wide speed and torque four-quadrant simulation results are provided, which validate the proposed sensorless strategy for being further implemented in EV.Peer ReviewedPostprint (author's final draft

    IPMSM torque control strategies based on LUTs and VCT feedback for robust control under machine parameter variations

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    In recent years, Interior Permanent Magnet Synchronous Machines (IPMSMs) have attracted a considerable attention in the scientific community and industry for Electric and Hybrid Electric Vehicle (HEV) propulsion systems. Lookup Table (LUT) based Field Oriented Control (FOC) strategies are widely used for IPMSM torque control. However, LUTs strongly depend on machine parameters. Deviations of these parameters due to machine ageing, temperature or manufacturing inaccuracies can lead to control instabilities in the field weakening region. In this paper, two novel hybrid IPMSM control strategies combining the usage of LUTs and Voltage Constraint Tracking (VCT) feedbacks are proposed in order to overcome the aforementioned controllability issues. Simulation results that demonstrate the validity of the proposed approaches are presented.Postprint (author's final draft

    Fair Routing in Delay Tolerant Networks

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    Abstract—The typical state-of-the-art routing algorithms for delay tolerant networks are based on best next hop hill-climbing heuristics in order to achieve throughput and efficiency. The combination of these heuristics and the social network structure leads the routing to direct most of the traffic through a small subset of good users. For instance, in the SimBet algorithm, the top 10 % of users carry out 54 % of all the forwards and 85 % of all the handovers. This unfair load distribution is not sustainable as it can quickly deplete constraint resources in heavily utilized mobile devices (e.g. storage, battery, budget, etc.). Moreover, because a small number of users carry a significant amount of the traffic, the system is not robust to random failures and attacks. To overcome these inefficiencies, this paper introduces Fair-Route, a routing algorithm for delay tolerant networks inspired by the social processes of perceived interaction strength, where messages are preferably forwarded to users that have a stronger social relation with the target of the message; and assortativity, that limits the exchange of messages to those users with similar ”social status”. We compare the performance of FairRoute to the state-of-the-art algorithms by extensive simulations on the MIT reality mining dataset. The results show that our algorithm outperforms existing algorithms in the de facto benchmark of throughput vs. forwards. Furthermore, it distributes better the load; the top 10 % carry out 26 % of the forwards and 28 % of the handovers without any loss in performance. I

    Improved timed-mating, non-invasive method using fewer unproven female rats with pregnancy validation via early body mass increases

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    For studies requiring accurate conception-timing, reliable, efficient methods of detecting oestrus reduce time and costs, whilst improving welfare. Standard methods use vaginal cytology to stage cycle, and breeders are paired–up using approximately five proven females with proven males to achieve at least one conception on a specific day. We describe an alternative, fast, consistent, non-invasive method of timed-mating using detection of lordosis behaviour in Wistar and Lister-Hooded rats that used unproven females with high success rates. Rats under reverse-lighting had body masses recorded pre-mating, day (d) 3-4, d8, d10 and d18 of pregnancy. Using only the presence of the oestrus dance to time-mate females for 24-hrs, 89% Wistar and 88% Lister-Hooded rats successfully conceived. We did not observe behavioural oestrus in Sprague-Dawleys without males present. Significant body mass increases following mating distinguished pregnant from non-pregnant rats, as early as d4 of pregnancy (10% ± 1.0 increase cf 3% ± 1.2). The pattern of increases throughout gestation was similar for all pregnant rats until late pregnancy, when there were smaller increases for primi- and multiparous rats (32% ± 2.5; 25% ± 2.4), whereas nulliparous rats had highest gains (38% ± 1.5). This method demonstrated a distinct refinement of the previous timed-mating common practice used, as disturbance of females was minimised. Only the number required of nulli-, primi- or multiparous rats were mated, and body mass increases validated pregnancy status. This new breeding-management method is now established practice for two strains of rat and resulted in a reduction in animal use

    Effects of subcutaneous LPS injection on gestational length and intrauterine and neonatal mortality in mice

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    BACKGROUND Infection during pregnancy can predispose offspring to develop various psychiatric disorders such as depression in later life. In order to investigate the potential mechanisms underlying these associations, animal models of maternal infection have been employed. As such, lipopolysaccharide (LPS) has been commonly used to mimic a bacterial infection in pregnant mice. OBJECTIVE The original aim of our study was to investigate the effects of different doses of subcutaneous LPS administration on affective behavior in adult mouse offspring. In the present paper, however, we report that subcutaneous LPS administration has a profound impact on gestational length, litter size, and perinatal mortality in the offspring, even at a relatively low dose. METHODS Pregnant mice were randomly divided into 3 groups, receiving either a high (2 mg/kg) or a low (0.5 mg/kg) dose of LPS or phosphate-buffered saline by means of subcutaneous injection. Subsequently, the effects on gestational length, litter size, and perinatal mortality in the offspring were assessed. RESULTS After subcutaneous injection with a high dose of LPS, we observed a significant decrease in gestational length and an increase in neonatal mortality. When the low dose was administered, a tendency towards a reduced litter size was observed, most likely reflecting increased intrauterine mortality in response to prenatal maternal LPS exposure. CONCLUSIONS We showed that subcutaneous administration of 2 mg/kg LPS to pregnant mice in the last phase of gestation should be avoided because of high offspring mortality rates, whereas subcutaneous injection of 0.5 mg/kg LPS seems to result in reabsorption of the fetuses

    Somatic and Vicarious Pain are Represented by Dissociable Multivariate Brain Patterns

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    Understanding how humans represent others’ pain is critical for understanding pro-social behavior. ‘Shared experience’ theories propose common brain representations for somatic and vicarious pain, but other evidence suggests that specialized circuits are required to experience others’ suffering. Combining functional neuroimaging with multivariate pattern analyses, we identified dissociable patterns that predicted somatic (high versus low: 100%) and vicarious (high versus low: 100%) pain intensity in out-of-sample individuals. Critically, each pattern was at chance in predicting the other experience, demonstrating separate modifiability of both patterns. Somatotopy (upper versus lower limb: 93% accuracy for both conditions) was also distinct, located in somatosensory versus mentalizing-related circuits for somatic and vicarious pain, respectively. Two additional studies demonstrated the generalizability of the somatic pain pattern (which was originally developed on thermal pain) to mechanical and electrical pain, and also demonstrated the replicability of the somatic/vicarious dissociation. These findings suggest possible mechanisms underlying limitations in feeling others’ pain, and present new, more specific, brain targets for studying pain empathy

    Investigación en metodologías de aprendizaje para grupos ARA en la materia de arquitectura de computadores

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    La enseñanza en inglés es uno de los retos a los que se está enfrentando actualmente la universidad española. La Universidad de Alicante ofrece a través de los grupos de Alto Rendimiento Académico (ARA) parte de la docencia de los estudios de grado en inglés. El objetivo principal de esta red es la de consolidar y ampliar la investigación realizada en metodologías de aprendizaje para grupos ARA en la materia de arquitectura de computadores. En consecuencia, se pretende ampliar los materiales docentes en inglés en relación con la enseñanza de asignaturas relacionadas con la materia en estos grupos de alto rendimiento. Estas asignaturas son impartidas por varios miembros de la red en diferentes cursos de los Grados de Ingeniería Informática y de Ingeniería en Sonido e Imagen en Telecomunicación. Como caso práctico, se ha continuado con la investigación en la asignatura Arquitectura de Computadores del Grado de Ingeniería Informática. Para ello, se han elaborado nuevos materiales para prácticas que permiten la participación activa y el trabajo en equipo. Cada uno de los materiales propuestos está diseñado dentro del marco metodológico implementado en la asignatura, relacionado con la consecución de objetivos y competencias, y con la evaluación de la misma

    El proceso de enseñanza-aprendizaje en la formación interuniversitaria: una experiencia a nivel de máster universitario

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    La incorporación del EEES provocó una infinidad de desafíos y retos a las Universidades que a día de hoy aún están siendo solucionados. Además, ha conllevado nuevas oportunidades para la formación de estudiantes pero también para las Universidades. Entre ellas, la formación interuniversitaria entre estados miembro de la UE. El EEES permite unificar a través del sistema ECTS la carga de trabajo de los estudiantes facilitando la propuesta de planes de estudios interuniversitarios. Sin embargo, surgen desafíos a la hora de llevarlos a la práctica. Independientemente de los retos en la propuesta de los planes de estudio, es necesario implementar procesos de enseñanza-aprendizaje que salven la distancia en el espacio físico entre el alumnado y el profesorado. En este artículo se presenta la experiencia docente de la asignatura e-home del Máster Machine Learning and Data Mining de la Universidad de Alicante y la Universidad Jean Monnet (Francia). En este caso, se combina la formación en aula presencial con formación en aula virtual a través de videoconferencia. La evaluación del método de enseñanza-aprendizaje propuesto utiliza la propia experiencia docente y encuestas realizadas a los alumnos para poner de manifiesto la ruptura de barreras espaciales y un éxito a nivel docente

    HRFlexToT: A High Dynamic Range ASIC for Time-of-Flight Positron Emission Tomography

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    Time-of-Flight positron emission tomography scanners demand fast and efficient photo sensors and scintillators coupled to fast readout electronics. This article presents the high resolution flexible Time-over-Threshold (HRFlexToT), a 16-channel application-specific-integrated circuit for silicon photomultipliers (SiPM) anode readout manufactured using XFAB 0.18- \mu \text{m} CMOS technology. The main features of the HRFlexToT are a linear Time-over-Threshold with an extended dynamic range (10 bits) for energy measurement, low power consumption (≈ 3.5 mW/ch), and an excellent timing response. The experimental measurements show an energy linearity error of ≈ 3% and an energy resolution of about 12% at 511 keV. Single-photon time resolution measurements performed using an Fondazione Bruno Kessler (FBK) SiPM NUV-HD ( 4 \times 4 mm2 pixel, 40- \mu \text{m} cell) and a Hamamatsu SiPM S13360-3050CS are around 142 and 167 ps full width at half maximum (FWHM), respectively. Coincidence time resolution (CTR) measurements with small cross-section pixelated crystals (LSO:Ce,Ca 0.4%, 2 \times 2 \times 5 mm3) coupled to the same Hamamatsu S13360-3050CS and FBK NUV-HD sensors yield a CTR of 117 ps and 119 ps, respectively. Measurements performed with a large cross-section monolithic crystal (LFS crystal measuring 25 \times 25 \times 20 mm3) and a Hamamatsu SiPM array S13361-6050NE-04 show a CTR of 324 ps FWHM after time-walk and time-skew correction
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