468 research outputs found
Direct torque control for dual three-phase induction motor drives
No full textA direct torque control (DTC) strategy for dual three-phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees. The DTC strategy is based on a predictive algorithm and is implemented in a synchronous reference frame aligned with the machine stator flux vector. The advantages of the discussed control strategy are constant inverter switching frequency, good transient and steady-state performance, and low distortion of machine currents with respect to direct self-control (DSC) and other DTC schemes with variable switching frequency. Experimental results are presented for a 10-kW DTC dual three-phase induction motor drive prototype
- Il profumo nell'esegesi latina medievale del Cantico dei Cantici
No full textLe notazioni sul profumo nell'esegesi del cantico dei cantici sono nei primi secoli del Medioevo prevalentemente allegoriche, ma a poco a poco e soprattutto con Bernardo di Clairvaux e con Alano di Lilla sembrano recuperare una forma di esegesi letterale che alla fine serve soprattutto a descrivere il corpo perfetto di Maria, madre di Gesu
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Sub-GeV Dark Matter Shining at Future MeV γ -Ray Telescopes
No full textWe propose a novel framework where light (sub-GeV) dark matter (DM) is detectable with future MeV γ-ray telescopes without conflicting with cosmic microwave background (CMB) data. The stable DM particle χ has a very low thermal relic abundance due to its large pair-annihilation cross section. The DM number density is stored in a slightly heavier, metastable partner ψ with suppressed pair-annihilation rates, that does not perturb the CMB, and whose late-time decays ψ→χ fill the Universe with χ DM particles. We provide explicit, model-independent realizations for this framework, and discuss constraints on late-time decays, and thus on parameters of this setup, from CMB, big bang nucleosynthesis, and large scale structure
Le determinanti della nascita e del successo degli spin-off della ricerca pubblica
No full textThis paper deals with the factors and conditions determining the birth and successful entry of research-based spinoffs from public organisations. This subject has become very critical within the Italian industrial policy
debate as during the last decade the amount of these new science-based firms rapidly increased all over
the country. A large body of literature analyses this entrepreneurial process and outlines which
conditions are critical in order to support researchers, public research organisations and policy-makers
in launching successfully new science-based ventures. In the present work, these factors are
distinguished in two main types: internal resources of the rising new firm and conditions of the
external environment in which the spin-off emerges. Critical implications for academic managers,
researchers and policy-makers are drawn by the analysis of the two types of factors
Does corporate ownership structure affect firms’environmental performance? Evidence in the European energy industry
No full textThe present paper aims to explore the mutual influence existing between corporate ownership structure and firms’ environmental performance.
The attention is focused on the energy industry, that represents one of the industries with the highest environmental impact and that, in the last few years, has been forced to increase efforts towards green issues.
In particular, the introduction of vertical unbundling in electricity and gas markets provides the opportunity to concentrate the attention on European energy companies operating in service activities, in which it is possible to better understand firms’ environmental performance.
The study, performing a linear regression model, examines the explanatory power of corporate governance issues, in particular firms’ ownership structure, as potential determinants of companies’ environmental performance.
The results show, in particular, that firms with more diffuse ownership present the worst environmental performance, while greater stakes held by institutional investors or by the State do not seem to be related with firms’ green performance
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