175,826 research outputs found
A Comparative Analysis of the Equity Outcomes in Three Sugarcane–Ethanol Systems
No full textThis article identifies equity outcomes associated with three biofuel systems in Brazil, Ethiopia, and Guatemala. Acknowledging that winners and losers are socially and politically generated, the article identifies some of the factors behind the distribution of winners and losers along different stages of three sugarcane–ethanol supply chains. Analyzing the outcomes for equity within each case study reveals an uneven distribution that, we argue, is related to the procedure and structure of the given sugarcane–ethanol system, and the recognition of the impacts on different actors within those structures. Increasing equity in sugarcane–ethanol systems will require greater openness in decision-making processes, in order that multiple voices are taken into account in the promotion, production, and consumption of biofuels—particularly those of smaller and less powerful actors
Nonlinear tracking control for sensorless permanent magnet synchronous motors with uncertainties
No full textThe recent advanced solution in Marino, Tomei, and Verrelli (2013) to the tracking control problem for sensorless IMs with parameter uncertainties is translated on the basis of letter swap connections between the models of (nonsalient-pole surface) permanent magnet synchronous motors (PMSMs) and induction ones (IMs). The (stability proof-based) nonlinear adaptive position/speed tracking control for sensorless PMSMs (with simultaneous estimation of uncertain constant load torque and stator resistance), which is accordingly obtained by exploring and decoding the design paths in Marino et al. (2013) and which surprisingly represents a simple generalization of the controller in Tomei and Verrelli (2011), constitutes an innovative solution to the related open problem. Illustrative experimental results are included
Diasporic identity and orientation to co-development. A survey on foreign students attending the University of Pisa
No full textTomei G. Diasporic identity and orientation to co-development. A survey on foreign students attending the University of Pisa. COMCAD Arbeitspapiere - working papers, 59. Bielefeld: COMCAD - Center on Migration, Citizenship and Development; 2008.Strength of ties and amplitude/frequency of contacts with other natives (living at home and/or abroad), are generally considered the main proxy indicators of a transnational structuration of migrant groups and the principal evidences of a diaspora. Despite of this evidence, there are (at least) other three cultural and sociological conditions that make this outcomes possible or not: (i) belonging of the migrant group members to a wider transnational network, (ii) sharing a common sense of community with its members, (iii) participating with a common project that involve all the community.
The paper discusses the main outputs of an on-line survey between young foreigners attendingthe University of Pisa, with the aim to investigate how "sense of community" (McMillan and Chavis, 1986), "social capital" (Van der Gaag-Snijders, 2004) and co-development orientation between members of the same ethnic groups (living in Italy or abroad), could help researcher to identify, conceptualize and measure everyday and informal transnational relationship becoming to a new definition of the concept of diaspora (Cohen, 1997; Cohen, Vertovec, 1999)
Charles West, Reframing the Feudal Revolution Political and Social Transformation Between Marne and Moselle, c. 800-c. 1100, New York, Cambridge University Press, 2013
No full textRecensione del volume di Charles West, Reframing the Feudal Revolution Political and Social Transformation Between Marne and Moselle, c. 800-c. 1100, New York 2013
I reperti vegetali presenti nella collezione Rosellini al Museo Archeologico di Firenze.
No full textPositive eigenvectors and simple nonlinear maps
No full textFor linear operators L,T and nonlinear maps P, we describe classes of simple maps F = I −PT, F = L−P between Banach and Hilbert spaces, for which no point has more than two preimages. The classes encompass known examples (homeomorphisms, global folds) and the weaker, geometric, hypotheses suggest new ones. The operator L may be the Laplacian with various boundary conditions, as in the original Ambrosetti-Prodi the- orem, or the operators associated with the quantum harmonic oscillator, the hydrogen atom, a spectral fractional Laplacian, elliptic operators in non-divergent form. The maps P include the Nemitskii map P(u) = f(u) but may be non-local, even non-variational. For self-adjoint operators L, we employ familiar results on the nondegeneracy of the ground state. On Banach spaces, we use a variation of the Krein-Rutman theorem
New exponential convergence properties for Bernard-Praly observer and adaptive sensorless control of PMSMs
No full textIt is innovatively established, through a nonlinear Persistency of Excitation (PE) analysis, that the latest Bernard-Praly gradient adaptive observer - for nonsalient-pole surface Permanent Magnet Synchronous Motors (PMSMs) with uncertain flux of the permanent magnet (PM) - owns exponential convergence properties under well-known observability conditions. Such exponential properties can be crucially used to provide a new solution to the long-standing problem of guaranteeing position/speed tracking in sensorless PMSMs, in the presence of uncertain constant parameters such as load torque, PM flux and possibly stator resistance. (C) 2020 Elsevier Ltd. All rights reserved
Global stability for the inner and outer PI control actions in non-salient-pole PMSMs
No full textThe aim of this brief is to positively answer the following question. Is it possible to go beyond the limitations outlined in the very recent paper by Ortega et al. and show that the smooth version of the (maximum-torque-per-ampere) industry standard control scheme for non-salient-pole PMSMs (Permanent Magnet Synchronous Motors) - even including the outer Proportional-Integral control action on the rotor speed regulation error - guarantees global asymptotic (exponential on compact sets) stabilization of the desired equilibrium? The key technical point relies on the repeated use of the Persistency of Excitation Lemma, whereas a remarkable feature of the proposed analysis is constituted by the direct possibility of recovering, as a special case, the recent passivity-based arguments presented by Ortega et al. for non-salient-pole PMSMs. (C) 2020 Elsevier Ltd. All rights reserved
Le carte dell’Archivio di Santa Maria di Pomposa (932-1050), a c. C. Mezzetti, Roma 2016
No full textRecensione del volume Le carte dell’Archivio di Santa Maria di Pomposa (932-1050), a cura di Corinna Mezzetti, Roma 2016
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