FIELD ORIENTED CONTROL OF IPM DRIVES FOR FLUX WEAKENING APPLICATIONS

Interior Permanent Magnet (IPM) drives are adapted to flux-weakening, then to constant power operation over a wide speed range. Most of the control strategies for IPM motor drives are based on the control of the current vector. Flux-weakening is obtained by proper current references, that are calculated according to the magnetic model of the motor. This approach needs the accurate characterization of the motor and it is sensitive to the inaccuracy and the variation of the model parameters. Moreover, in the case of a variable dc-link, an additional voltage loop is necessary to correct the current references values at different dc-link voltage levels. The direct control of the flux vector, in the stator flux oriented frame, is proposed here, with the aim of obtaining the constant voltage operation of the IPM motor drive in the flux weakening range by means of a very simple control algorithm. The proposed direct flux control is tested on an IPM motor drive designed for traction. The exploitation of the maximum torque in all the operating speed range is demonstrated. The control is also capable to adapt its flux and current set-points to different dc-link voltage levels with no need of additional voltage regulators. Discrete-time simulation and experimental results are presented and compared showing good accordance

Jet propulsion without inertia

A body immersed in a highly viscous fluid can locomote by drawing in and expelling fluid through pores at its surface. We consider this mechanism of jet propulsion without inertia in the case of spheroidal bodies, and derive both the swimming velocity and the hydrodynamic efficiency. Elementary examples are presented, and exact axisymmetric solutions for spherical, prolate spheroidal, and oblate spheroidal body shapes are provided. In each case, entirely and partially porous (i.e. jetting) surfaces are considered, and the optimal jetting flow profiles at the surface for maximizing the hydrodynamic efficiency are determined computationally. The maximal efficiency which may be achieved by a sphere using such jet propulsion is 12.5%, a significant improvement upon traditional flagella-based means of locomotion at zero Reynolds number. Unlike other swimming mechanisms which rely on the presentation of a small cross section in the direction of motion, the efficiency of a jetting body at low Reynolds number increases as the body becomes more oblate, and limits to approximately 162% in the case of a flat plate swimming along its axis of symmetry. Our results are discussed in the light of slime extrusion mechanisms occurring in many cyanobacteria

A new search for anomalous neutrino oscillations at the CERN-PS

The LSND experiment has observed a 3.8 sigma excess of anti-nu_e events from an anti-nu_mu beam coming from pions at rest. If confirmed, the LSND anomaly would imply new physics beyond the standard model, presumably in the form of some additional sterile neutrinos. The MiniBooNE experiment at FNAL-Booster has further searched for the LSND anomaly. Above 475 MeV, the nu_e result is excluding the LSND anomaly to about 1.6 sigma but it introduces an unexplained, new 3.0 sigma anomaly at lower energies, down to 200 MeV. The nu_e data have so far an insufficient statistics to be conclusive with LSND's anti-nu_e. The present proposal at the CERN-PS is based on two strictly identical LAr-TPC detectors in the near and far positions, respectively at 127 and 850 m from the neutrino (or antineutrino) target and focussing horn, observing the electron-neutrino signal. This project will benefit from the already developed technology of ICARUS T600, well tested on surface in Pavia, without the need of any major R&D activity and without the added problems of an underground experiment (CNGS-2). The superior quality of the Liquid Argon imaging TPC and its unique electron - pi-zero discrimination allow full rejection of the NC background, without efficiency loss for electron neutrino detection. In two years of exposure, the far detector mass of 600 tons and a reasonable utilization of the CERN-PS with the refurbished previous TT7 beam line will allow to collect about 10^6 charged current events, largely adequate to settle definitely the LSND anomaly.Comment: 23 pages, 17 figures, added watermark, better referencin

A Bayesian framework for describing and predicting the stochastic demand of home care patients

Home care providers are complex structures which include medical, paramedical and social services delivered to patients at their domicile. High randomness affects the service delivery, mainly in terms of unplanned changes in patients’ conditions, which make the amount of required visits highly uncertain. Hence, each reliable and robust resource planning should include the estimation of the future demand for visits from the assisted patients. In this paper, we propose a Bayesian framework to represent the patients’ demand evolution along with the time and to predict it in future periods. Patients’ demand evolution is described by means of a generalized linear mixed model, whose posterior densities of parameters are obtained through Markov chain Monte Carlo simulation. Moreover, prediction of patients’ demands is given in terms of their posterior predictive probabilities. In the literature, the stochastic description of home care patients’ demand is only marginally addressed and no Bayesian approaches exist to the best of our knowledge. Results from the application to a relevant real case show the applicability of the proposed model in the practice and validate the approach, since parameter densities in accordance to clinical evidences and low prediction errors are found

Growth and dissection of a fold and thrust belt: the geological record of the High Agri Valley, Italy

We present a 130 km2 wide geological map for the NE side of the fault-bounded High Agri Valley Southern Italy, that formed in the Quaternary in response to extensional tectonics dissecting the folds and thrusts of the Lucanian Apennine. To prepare the map, at 1:25,000 scale, we integrated information obtained through field surveys and the review of pre-existing geological data. Our work describes a number of significant map-scale structures, which can be related to well-constrained tectonic episodes. The new geological map provides important constraints that can be used to distinguish ancient structures from those that were active during the Quaternary, allowing a more detailed reconstruction of the processes that operate during the development of a post-orogenic trough. We expect that the new map will be used for different types of geological investigations, including studies of inversion tectonics, active tectonics, geosite mapping, 3D modelling of geological structures. © 2020, © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of Journal of Maps

Flujo en tubos a presión

382 p."El objetivo general de esta obra es explicar el fundamento y desarrollar habilidades para el cálculo de tubos y de redes de tubos a presión en régimen permanente, principalmente como texto universitario a nivel licenciatura. La idea de su elaboración surge de la inquietud de facilitar al alumno un material de estudio claro, completo y didáctico, especialmente para su uso en el curso de hidraúlica de la UAM Azcapotzalco. Cubre la primera parte de ese curso pero también es útil para el de mecánica de fluidos.Este libro será útil también como material de consulta en otros cursos en los que se ocupa el tema, tales como turbomaquinaria, instalaciones industriales, abastecimiento de agua, instalaciones en edificios, etcétera.

Temporal control of Wnt signaling is required for habenular neuron diversity and brain asymmetry

Precise temporal coordination of signaling processes is pivotal for cellular differentiation during embryonic development. A vast number of secreted molecules are produced and released by cells and tissues, and travel in the extracellular space. Whether they induce a signaling pathway and instruct cell fate, however, depends on a complex network of regulatory mechanisms, which are often not well understood. The conserved bilateral left-right asymmetrically formed habenulae of the zebrafish are an excellent model for investigating how signaling control facilitates the generation of defined neuronal populations. Wnt signaling is required for habenular neuron type specification, asymmetry and axonal connectivity. The temporal regulation of this pathway and the players involved have, however, remained unclear. We find that tightly regulated temporal restriction of Wnt signaling activity in habenular precursor cells is crucial for the diversity and asymmetry of habenular neuron populations. We suggest a feedback mechanism whereby the tumor suppressor Wnt inhibitory factor Wif1 controls the Wnt dynamics in the environment of habenular precursor cells. This mechanism might be common to other cell types, including tumor cells

Free electron lifetime achievements in Liquid Argon Imaging TPC

A key feature for the success of the liquid Argon imaging TPC (LAr-TPC) technology is the industrial purification against electro-negative impurities, especially Oxygen and Nitrogen remnants, which have to be continuously kept at an exceptionally low level by filtering and recirculating liquid Argon. Improved purification techniques have been applied to a 120 liters LAr-TPC test facility in the INFN-LNL laboratory. Through-going muon tracks have been used to determine the free electron lifetime in liquid Argon against electro-negative impurities. The short path length here observed (30 cm) is compensated by the high accuracy in the observation of the specific ionization of cosmic ray muons at sea level as a function of the drift distance. A free electron lifetime of (21.4+7.3-4.3) ms, namely > 15.8 ms at 90 % C.L. has been observed over several weeks under stable conditions, corresponding to a residual Oxygen equivalent of about 15 ppt (part per trillion). At 500 V/cm, the free electron speed is 1.5 m/ms. In a LAr-TPC a free electron lifetime in excess of 15 ms corresponds for instance to an attenuation of less than 15 % after a drift path of 5 m, opening the way to the operation of the LAr-TPC with exceptionally long drift distances.Comment: 15 pages, 10 figures; Accepted for publication in JINS