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

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

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

Accumulation of polychlorinated biphenyls (PCBs) in navigation channels, harbors and industrial areas of the Bahia Blanca Estuary, Argentina

The usage and production of polychlorinated biphenyls (PCBs) was banned in Argentina in 2002, approximately twenty to thirty years later than in other countries. A total of 29 sediment samples (up to 14 m deep) were analyzed for a mix of seven individual PCBs in a time series for over more than one year in twelve selected locations, including harbors, recreational docks and several industrialized coastal locations in Bahia Blanca Estuary, Argentina, South America. The GC/ECD results showed the dominance of three chlorinated compounds: CB180, CB52 and CB101, which showed a strong reduction with distance from the urban area. The principal components analysis differentiates light and heavy congeners variation, settling several hypotheses and the classification of sampling sites to determine the PCB burden. Considering literature reports, the present results were evaluated in the international PCB context, diminishing the scarcity of PCB data from the Southern Hemisphere and prompting the need of future monitoring approaches.Fil: Arias, Andres Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Bahia Blanca. Instituto Argentino de Oceanografia (i); Argentina;Fil: Vazquez-Botello, A.. Instituto de Ciencias Nucleares. Universidad Nacional Autónoma de México; México;Fil: Diaz, Gilberto. Universidad Tecnologica Nacional; Argentina;Fil: Marcovecchio, Jorge Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Bahia Blanca. Instituto Argentino de Oceanografia (i); Argentina

Unveiling the evolutionary state of three B supergiant stars: PU Gem, ϵ\epsilon CMa and η\eta CMa

We aim to combine asteroseismology, spectroscopy, and evolutionary models to establish a comprehensive picture of the evolution of Galactic blue supergiant stars (BSG). To start such an investigation, we selected three BSG candidates for our analysis: HD 42087 (PU Gem), HD 52089 ($\epsilon$ CMa) and HD 58350 ($\eta$ CMa). These stars show pulsations and were suspected to be in an evolutionary stage either preceding or succeding the red supergiant (RSG) stage. For our analysis, we utilized the 2-min cadence TESS data to study the photometric variability and obtained new spectroscopic observations at the CASLEO observatory. We calculated CMFGEN non-LTE radiative transfer models and derived stellar and wind parameters using the iterative spectral analysis pipeline XTGRID. The spectral modeling was limited to changing only the effective temperature, surface gravity, CNO abundances, and mass-loss rates. Finally, we compared the derived metal abundances with predictions from Geneva stellar evolution models. The frequency spectra of all three stars show either stochastic oscillations, nonradial strange modes, or a rotational splitting. We conclude that the rather short sectoral observing windows of TESS prevent establishing a reliable mode identification of low frequencies connected to mass-loss variabilities. The spectral analysis confirmed gradual changes in the mass-loss rates and the derived CNO abundances comply with the values reported in the literature. We were able to achieve a quantitative match with stellar evolution models for the stellar masses and luminosities. However, the spectroscopic surface abundances turned out to be inconsistent with theoretical predictions. The stars show N enrichment, typical for CNO cycle processed material, but the abundance ratios do not reflect the associated levels of C and O depletion.Comment: 29 pages, 18 figures, Accepted for publication in Galaxie

Testing postcombustion CO2 capture with CaO in a 1.7 MWt pilot facility

AbstractCalcium looping, CaL, is a new and rapidly developing technology that makes use of CaO as a high temperature regenerable sorbent of CO2. Previous theoretical and lab scale studies have shown that this technology could lead to a substantial reduction in the cost of CO2 capture and energy penalties because heat can be effectively recovered from this high temperature solid looping system. We report in this paper on the first results from a pilot plant designed to demonstrate the viability of postcombustion capture of CO2 using CaL under conditions comparable to those expected in a large scale plant. The pilot includes two interconnected circulating fluidized bed reactors of 15 m height: a CO2 absorber (carbonator) able to treat up to 2400kg/h (equivalent to about 1.7 MWth), and an oxy-fired CFB calciner with a firing power between 1-3 MWth. CO2 capture efficiencies over 90% have been experimentally observed, including continuous operation with highly cycled solids in the system (i.e. with modest CO2 carrying capacities). SO2 capture is shown to be extremely high, with concentrations of SO2 well below 10 ppmv at the exit of the carbonator. Closure of carbon and sulfur balances is satisfactory. These results should be valuable base for model validation and scaling up purposes in future stages of the EU FP7 “CaOling” project, under which this investigation has been carried out

Biochemical characterization of recombinant Candida albicans mannosyltransferases Mnt1, Mnt2 and Mnt5 reveals new functions in O- and N-mannan biosynthesis

Peer reviewedPublisher PD

Self-care in individuals who recycle garbage (recyclers) of Medellín, Colombia, 2005

ABSTRACT: To understand the conceptions, attitudes and practices about self-care among informal recyclers in Medellín. Methodology: a qualitative study from the perspective of recyclers not belonging to any guild in Medellín in 2005 was developed. A total amount of 52 interviews with previous informed consent were applied, plus non-participant observation and field diary. Results: self-care is understood as the constant protection of the body in order to avoid the occurrence of diseases. It includes aspects of hygiene, diet, medical consultation, proper use of leisure time and utilization of instruments for personal protection, such as gloves, face masks, caps, and ear plugs among other devices. Discussion: disease prevention goes beyond biological aspects and becomes part of a social dimension for people in which the most important features are the consequences for themselves, their labor team and their families. Recyclers have knowledge on prevention and practices that promote health and well-being, but the latter are not applied because they diminish their job performance, or they do not consider them to be necessary, do not feel like executing them nor they lack the economic resources to assume them. Autocare practices of recyclers are mainly supported by the primacy of the team history than by the scientific knowledge concerning it.RESUMEN: Comprender las concepciones, actitudes y prácticas sobre autocuidado en los recicladores informales de Medellín. Metodología: se realizó un estudio cualitativo desde la perspectiva de los recuperadores no agremiados de Medellín en el 2005. Se aplicaron 52 entrevistas, con previo consentimiento informado, observación no participante y diario de campo. Resultados: el autocuidado se concibe como la protección del cuerpo con el fin de evitar la ocurrencia de enfermedad; incluye aspectos de higiene, dieta, consulta médica, uso del tiempo libre y utilización de instrumentos de protección personal, como guantes, tapabocas, cachucha, tapaoídos y otros. Discusión: la prevención de la enfermedad trasciende el plano biológico y se posiciona en una dimensión social para la persona, en que lo más importante son las consecuencias que puede generar para sí misma, su grupo de trabajo y su familia. Los recuperadores poseen saberes sobre la prevención y las prácticas que promueven la salud y el bienestar, pero estas últimas no son aplicadas porque disminuyen su rendimiento, no las consideran necesarias, no depende de ellos ejecutarlas o carecen de los recursos económicos. Las prácticas de autocuidado del recuperador se sustentan más por la primacía de la historia del grupo que por el saber científico

Zerovalent bismuth nanoparticles inhibit Streptococcus mutans growth and formation of biofilm

Background and methods: Despite continuous efforts, the increasing prevalence of resistance among pathogenic bacteria to common antibiotics has become one of the most significant concerns in modern medicine. Nanostructured materials are used in many fields, including biological sciences and medicine. While some bismuth derivatives has been used in medicine to treat vomiting, nausea, diarrhea, and stomach pain, the biocidal activity of zerovalent bismuth nanoparticles has not yet been studied. The objective of this investigation was to analyze the antimicrobial activity of bismuth nanoparticles against oral bacteria and their antibiofilm capabilities. Results: Our results showed that stable colloidal bismuth nanoparticles had 69% antimicrobial activity against Streptococcus mutans growth and achieved complete inhibition of biofilm formation. These results are similar to those obtained with chlorhexidine, the most commonly used oral antiseptic agent. The minimal inhibitory concentration of bismuth nanoparticles that interfered with S. mutans growth was 0.5 mM. Conclusion: These results suggest that zerovalent bismuth nanoparticles could be an interesting antimicrobial agent to be incorporated into an oral antiseptic preparation

Variational collocation for systems of coupled anharmonic oscillators

We have applied a collocation approach to obtain the numerical solution to the stationary Schr\"odinger equation for systems of coupled oscillators. The dependence of the discretized Hamiltonian on scale and angle parameters is exploited to obtain optimal convergence to the exact results. A careful comparison with results taken from the literature is performed, showing the advantages of the present approach.Comment: 14 pages, 10 table