626 research outputs found
Mirko Breyer, Publisher from Križevci
Full text linkU tekstu se donosi kratak prikaz života i djela križevačkog nakladnika Mirka Breyera. Mirko Breyer bio je pr\>ak hrvatske bibliografije, bibliofil, knjižar-nakladnik i antikvar. Obilježio je početak dvadesetog stoljeća svojim kulturnim radom. Autor donosi dio objavljene i dio neobjavljene građe o Mirku Breyeru.The text is a short overview of the life and work of a Križevci publisher Mirko Breyer. Mirko Breyer was a pioneer of Croation bibliography, a bibliophile, bookseller, publisher and antiquarian. He marked the beginning of the 20th century with his cultural work. The author presents parts of published as well as unpublished material on Mirko Breyer, with his bibliography
Fluctuating hydrodynamics model for homogeneous and heterogeneous vapor bubble nucleation
Full text linkAt the molecular scale, even in conditions of thermodynamic equilibrium, the fluids do not exhibit a deterministic behavior. Going down below the micrometer scale, the effects of thermal fluctuations play a dominant role in the dynamics of the system, calling for a suitable description of thermal fluctuations. These models not only play an important role in physics of fluids, but a deep understanding of these phenomena is necessary for the progress of some of the latest nanotechnology. For instance the modeling of thermal fluctuations is crucial in the design of flow micro-devices, in the study of biological systems, such as lipid membranes, in the theory of Brownian engines and in the development of artificial molecular motor prototypes. Another problem with a huge technological impact is the phenomenon of nucleation – the precursor of the phase transition in metastable systems – in this context related to bubble formation in liquid-vapor phase transition. Vapor bubbles form in liquids by two main mechanisms: boiling, by increasing the tempe- rature over the boiling threshold, and cavitation, by reducing the pressure below the vapor pressure threshold. The liquid can be held in these metastable states (overheating and tensile conditions, respectively) for a long time without forming bubbles. Bubble nucleation is indeed an activated process, requiring a significant amount of energy to overcome the free energy barrier and bring the liquid from the metastable conditions to the thermodynami- cally stable state where vapor is observed. Depending on the thermodynamic conditions, the nucleation time may be exceedingly long, the so-called "rare- event" issue. Nowadays molecular dynamics is the unique tool to investigate such thermally activated processes. However, its computational cost limits its application to small systems (less than few tenth of nanometers) and to very short times, preventing the study of hydrodynamic interactions. The latter effects are crucial to understand the cavitation phenomenon in its entirety, starting from the vapor embryos nucleation up to the macroscopic motion.
In this thesis a continuum diffuse interface model of the two-phase fluid has been embedded with thermal fluctuations in the context of the so-called Fluctuating Hydrodynamics (FH) and has been exploited to address cavitation. This model provides a set of partial stochastic differential equations, whose deterministic part is represented by the capillary Navier-Stokes equations and reproducing the Einstein-Boltzmann probability distribution for the macroscopic fields. This mesoscale approach enables the description of the liquid-vapor transition in extended systems and the evaluation of bub- ble nucleation rates in different metastable conditions by means of numerical simulations. Such model is expected to have a huge impact on the understanding of the nucleation dynamics since, by reducing the computational cost by orders of magnitude, it allows the unique possibility of investigating systems of realistic dimensions on macroscopic time scales. In addition, after the nucleating phase, the deterministic equations have been used to address the collapse of a cavitation nanobubble near a solid boundary, showing an unprecedented description of interfacial flows that naturally takes into account topology modification and phase changes (both vapor/liquid and vapor/supercritical fluid transformations)
Nuove agnizioni per il Gallo cedrone di Montale
No full textL'articolo propone nuove fonti (da Foscolo, d'Annunzio e Linati) utili alla comprensione e all'esegesi di uno dei testi pià ermetici della "Bufera e altro" di Montale, "Il gallo cedrone". In particolare, tale analisi consente di confermare la stabile presenza del riferimento dannunziano nella terza raccolta del poeta ligure
Diffuse interface modeling of laser-induced nano/micro cavitation bubbles
Full text linkIn the present work, a diffuse interface model has been used to numerically investigate the laser-induced cavitation of nano/microbubbles. The mesoscale approach is able to describe the cavitation process in its entirety, starting from the vapor bubble formation due to the focused laser energy deposition, up to its macroscopic motion.In particular, the simulations show a complete and detailed description of the bubble formation and the subsequent breakdown wave emission with a precise estimation of the energy partition between the shockwave radiating in the liquid and the internal energy of the bubble. The scaling of the ratio between the energy stored in the bubble at its maximum radius and the one deposited by the laser is found in agreement with experimental observation on macroscopic bubbles
Thermally activated vapor bubble nucleation: The Landau-Lifshitz--Van der Waals approach
Full text linkVapor bubbles are formed in liquids by two mechanisms: evaporation (temperature above the boiling threshold) and cavitation (pressure below the vapor pressure). The liquid resists in these metastable (overheating and tensile, respectively) states for a long time since bubble nucleation is an activated process that needs to surmount the free energy barrier separating the liquid and the vapor states. The bubble nucleation rate is difficult to assess and, typically, only for extremely small systems treated at an atomistic level of detail. In this work a powerful approach, based on a continuum diffuse interface modeling of the two-phase fluid embedded with thermal fluctuations (fluctuating hydrodynamics), is exploited to study the nucleation process in homogeneous conditions, evaluating the bubble nucleation rates and following the long-term dynamics of the metastable system, up to the bubble coalescence and expansion stages. In comparison with more classical approaches, this methodology allows us on the one hand to deal with much larger systems observed for a much longer time than possible with even the most advanced atomistic models. On the other, it extends continuum formulations to thermally activated processes, impossible to deal with in a purely determinist setting
Urban Geoscience: The Challenge of Street Geology
Full text linkBeyond the human-related conception, Urban Science is a broad concept that includes and concerns various interconnected issues linked to Natural, Engineering, Human, Social, and Computational Sciences. Natural Science is represented by issues linked to GeoScience and BioScience. GeoScience issues concern (i) the physical-environmental aspects linked to (a) design, planning, and expansion of the urban environment; (b) urban management interventions; (c) prevention and (d) mitigation of natural and human-induced risks; (e) defense against natural and human-induced risks and (ii) cultural aspects linked to (a) educational purposes and (b) promoting, enhancing, and disseminating scientific as well as territorial and environmental knowledge and awareness. Geoscience is represented also by Street Geology, a silent geology mainly present in historical centers of urban areas, but not only, and that can be used as an educational tool, an opportunity for broader discussions on geological-environmental and socio-cultural issues. Look, see, understand, and take awareness are four steps that give voice to street geology. This paper highlights some aspects of GeoScience in two different urban areas, located in Southern Italy, represented by (a) the Longobard Walls of Benevento (BN) and (b) the 1794 Vesuvius’ lava flow in Torre del Greco (NA)
Cavitation over solid surfaces: microbubble collapse, shock waves, and elastic response
Full text linkWe discuss the interaction of the strongly nonlinear fluid motion induced by the collapse of a vapor microbubble over a planar surface and the elastic dynamics of the underlying solid. The fluid is described using an extension of the Navier-Stokes equations endowed with distributed capillary stresses in the context of a diffuse interface approach. The collapse of the bubble is triggered by overpressure in the liquid and leads to an intense jet that pierces the bubble, changing the bubble topology from spheroidal to toroidal, and impinges the solid wall inducing an intense and strongly localized load. Moreover, at bubble collapse, a compression wave is launched into the liquid surrounding the bubble. By propagating along the solid surface, the compression wave combined with the liquid jet excites the dynamics of the elastic solid, producing a complex system of waves, including, longitudinal, transversal, and Rayleigh waves, propagating in the solid. It is conjectured that the intense deformation of the solid induced by the strongly localized liquid jet may lead to the plastic deformation of the solid producing the surface pitting observed in many applications subject to cavitation induced material damage
Professor Mirko Škampa - personality portrait
Full text linkBakalářská práce se zabývá osobností Mirko Škampy. Obsahuje stručný životopis, přehled jeho nejvýznamnějších absolventů a osobní rozhovor s pedagogem. Velkou část práce autor věnuje analýze některých cvičení z jeho metodické publikace – Škola hry na violoncello.The goal of the thesis is to present the personality of Mirko Škampa. It includes a brief biography, an overview of his most famous graduates and an personal interveiw with professor Škampa. The author of this thesis devotes its great part to analyse of some exercises from his methodics – School of cello playing for kids
Il linguaggio del comico nei fumetti di Leo Ortolani
No full textIl contributo esamina l'interazione tra testo e disegno in alcuni fumetti di Leo Ortolani, dedicando particolare attenzione al modo in cui sono costruite specifiche sequenze di vignette
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