3,160 research outputs found
Coulomb Friction Driving Brownian Motors
No full textWe review a family of models recently introduced to describe Brownian motors under the influence of Coulomb friction, or more general non-linear friction laws. It is known that, if the heat bath is modeled as the usual Langevin equation (linear viscosity plus white noise), additional non-linear friction forces are not sufficient to break detailed balance, i.e. cannot produce a motor effect. We discuss two possibile mechanisms to elude this problem. A first possibility, exploited in several models inspired to recent experiments, is to replace the heat bath's white noise by a “collisional noise”, that is the effect of random collisions with an external equilibrium gas of particles. A second possibility is enlarging the phase space, e.g. by adding an external potential which couples velocity to position, as in a Klein—Kramers equation. In both cases, non-linear friction becomes sufficient to achieve a non-equilibrium steady state and, in the presence of an even small spatial asymmetry, a motor effect is produced
Tracce del paesaggio antico nel Suburbio. I laterizi bollati nella raccolta Maruffi (collana editoriale Roma TrE-Press "Villa Maruffi. Materiali e Studi", n. 3)
No full textIl terzo volume dedicato ai materiali e agli studi in corso su Villa Maruffi, mette in evidenza l’interesse per la storia della cultura che scaturisce da questa struttura e dal territorio in cui è compresa, attraverso la raccolta di bolli impressi su laterizi antichi. Dalla contestualizzazione e dall’analisi di questi elementi emerge la testimonianza materiale della fitta trama di ville che caratterizza il suburbio di Roma fin dall’antichità, si seguono le fasi di più intensa edificazione e di declino, ma si possono ricostruire anche altre storie. Quella delle famiglie che ci hanno lasciato il loro marchio di fabbrica, oppure quella dei proprietari che hanno abitato nel tempo le stesse strutture, fino alla fase moderna di scoperta e di ‘estrazione’ dei materiali antichi dai terreni. Storie di persone, di attività, di luoghi, che si rivelano a chi ha la curiosità di guardare con interesse profondo anche le tracce meno appariscenti del nostro passato.
The third volume dedicated to materials and ongoing studies on Villa Maruffi, highlights the interest in the history of culture that flows from this structure and from the territory in which is, through the collection of stamps imprinted on bricks. From the contextualization and the analysis of those elements emerges the witness of the dense network of villas that characterise the suburbs of Rome since antiquity, you follow the most intense phases of construction and decline, but you can reconstruct even more stories. Stories of the families that left their trademark, or of the owners who have inhabited the same structures, until the modern phase of discovery and ' extraction ' of ancient materials from the suburbium of Rome. Stories of people, activities, places, which are revealed to those who have the curiosity to look with deep interest even less obvious traces of our past
Lattice models for granular and active matter fluctuating hydrodynamics
No full textThis thesis investigates the common nature of granular and active systems, which is rooted in their intrinsic out-of-equilibrium behavior, with the aim of finding minimal models able to reproduce and predict the complex collective behavior observed in experiments and simulations. Granular and active matter are among the most studied systems in out-of-equilibrium statistical physics.
The thesis guides readers through the derivation of a fluctuating hydrodynamic description of granular and active matter by means of controlled and transparent mathematical assumptions made on a lattice model. It also shows how a macroscopic description can be provided from microscopic requirements, leading to the prediction of collective states such as cooling, swarming, clustering and the transitions among them. The analytical and numerical results shed new light on the physical connection between the local, microscopic properties of few particles and the macroscopic collective motion of the whole system
A imagem de Alessandro Baricco no Brasil
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Estudos da Tradução, Florianópolis, 2013.Com a intenção de delinear o modo pelo qual o escritor italiano Alessandro Baricco se inseriu no sistema literário brasileiro e os caminhos percorridos pelos seus livros traduzidos, esta dissertação dá voz às experiências tradutórias de seus tradutores. A inserção de Bariccono Brasil tem seu início em 1997, através de uma proposição da Profa. Dra. Roberta Barni à editora Iluminuras da tradução de Oceano Mare. A partir daí, outras sete obras foram publicadas no Brasil, sendo três delas traduzidas por Roberta Barni e as outras quatro por quatro tradutores diferentes. De um lado, considera-se o tradutor como figura principal namediação entre culturas, e, de outro, se analisa a realidade desta figuradentro do sistema literário, sua invisibilidade, seus limites e o exercíciode sua profissão. A pesquisa conta, ainda, com críticas e resenhas referentes ao autor italiano publicadas em jornais consagrados no Brasil, considerando estas como parte constituinte da imagem de Baricco refletida em território nacional. Abstract : Intending to delineate the way the Italian writer Alessandro Baricco has been inserted in the Brazilian literary system and the paths his translated books have followed, this thesis gives voice to the translating experiences of his translators. Baricco's insertion in Brazil began in 1997, through a personal project of Dr. Roberta Barni, with her translation of Oceano Mare. Since then, seven other of his works have been published in Brazil, three of which were translated by Roberta Barni and the other four by four different translators. On the one hand,the translator is considered as the main figure in mediation betweencultures and, on the other, this figure's reality is analyzed within theliterary system: its invisibility, its limits and its professional practice. Criticisms and reviews of this Italian author published in well established Brazilian newspapers are also considered, with the understanding that they are part of Baricco's image reflected here
Optimal Control of an Electromechanical Energy Harvester
No full textMany techniques originally developed in the context of deterministic control theory have recently been applied to the quest for optimal protocols in stochastic processes. Given a system subject to environmental fluctuations, one may ask what is the best way to change its controllable parameters in time in order to maximize, on average, a certain reward function, while steering the system between two pre-assigned states. In this work, we study the problem of optimal control for a wide class of stochastic systems, inspired by a model of an energy harvester. The stochastic noise in this system is due to the mechanical vibrations, while the reward function is the average power extracted from them. We consider the case in which the electrical resistance of the harvester can be changed in time, and we exploit the tools of control theory to work out optimal solutions in a perturbative regime, close to the stationary state. Our results show that it is possible to design protocols that perform better than any possible solution with constant resistance
Introduction to the dynamics of disordered systems. Equilibrium and gradient descent
No full textThis manuscript contains the lecture notes of the short courses given by one of us (F.Z.) at the summer school "Fundamental Problems in Statistical Physics XV", held in Brunico, Italy, in July 2021, and, just before that, at the summer school "Glassy Systems and Inter-Disciplinary Applications", held in Cargese, France, in June 2021. The course was a short introductory overview of the dynamics of disordered systems, focused in particular on the equilibrium dynamics (with the associated glass transition), and on the simplest case of off-equilibrium dynamics, namely the gradient descent dynamics. A few selected topics (and references) are chosen, based on the authors' own taste and competences, and on pedagogical reasons, without aiming at a complete review of the subject
La maturità di Alessandro Fei del Barbiere, in bilico tra Maniera e Riforma
No full textThis article studies the mature career of the Florentine painter Alessandro Fei del Barbiere (1537-1592), beginning with the rediscovery of the 'Ascension' altarpiece formerly in the Albizi Chapel in the destroyed church of San Pier Maggiore, Florence. Studying this painting and others recorded in 1584 by the biographer Raffaello Borghini, such as the two altarpieces for Santa Maria delle Grazie and the Madonna dell'Umiltà in Pistoia, the author reconstructs a body of works showing how in the 1580s Fei gradually went beyond the archaic style of his apprenticeship - he had been trained by Ridolfo del Ghirlandaio and Pierfrancesco Foschi, but was also marked by the Maniera of Vasari - evolving towards naturalism in both mimesis and pictorial handling. In Florence, his development partly parallels that of Santi di Tito and his circle, but Fei was also influenced by a probable sojourn during the early part of that decade in Rome, where he could have been inspired by Girolamo Muziano and the painters working for Pope Gregory XIII. Among other proposals, the author suggests that the artist was responsible for decorating the chancel of Fiesole Cathedral (c. 1584-1589), which consisted of an altarpiece, only rarely discussed by scholars, and a cycle of frescoes hitherto attributed to Nicodemo Ferrucci
Article 8 of the 1970 UNESCO Convention: Penalties or Administrative Sanctions
No full textThe Chapter discusses the origin and implementation of Art. 8 of the 1970 UNESCO Convention on the Means of Prohibiting and Preventing the Illicit Import, Export and Transfer of Ownership of Cultural Property. It compares its provisions with prior and subsequent international hard and soft law, as well as with relevant elements of EU legislation. It presents a comparative overview of different regulatory models implemented at national level by States Parties
Tra socialdemocrazie e Perestrojka. Le relazioni internazionali del Pci attraverso le carte di Alessandro Natta
No full textThis essay reconstructs the foreign policy of the Italian Communist Party during the four
years of Alessandro Natta’s secretariat (1984-1988) through largely original archival documentation,
from the Alessandro Natta Fonds of the Historical Archive of the Chamber of
Deputies. Natta’s papers are also cross-referenced with those kept in the PCI Archive at the
Gramsci Foundation. The author analyses the relationship that the PCI establishes with
Gorbachev’s Perestroika, Deng’s China, and European social democracies during the last
years of the Cold War
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