8,858 research outputs found
Liquid Fluidized Beds of Granular Particles
No full textAbstract We suggest a simple model for the dynamics of granular particles in suspension which is suitable for an event driven algorithm, allowing to simulate N = O(106) particles or more. As a first application we consider a dense granular packing which is fluidized by an upward stream of liquid, i.e. a fluidized bed. In the stationary state, when all forces balance, we always observe a well defined interface whose width is approximately independent of packing fraction. We also study the dynamics of expansion and sedimentation after fast and slow changes in flow rate and determine the timescales to reach a stationary state
Dynamics of an intruder in dense granular fluids
No full textWe investigate the dynamics of an intruder pulled by a constant force in a dense two-dimensional granular fluid by means of event-driven molecular dynamics simulations. In a first step, we show how a propagating momentum front develops and compactifies the system when reflected by the boundaries. To be closer to recent experiments (Candelier and Dauchot in Phys Rev 81(1):011304, 2010; Phys Rev 103(12):128001, 2009), we then add a frictional force acting on each particle, proportional to the particle’s velocity. We show how to implement frictional motion in an event-driven simulation. This allows us to carry out extensive numerical simulations aiming at the dependence of the intruder’s velocity on packing fraction and pulling force. We identify a linear relation for small and a nonlinear regime for high pulling forces and investigate the dependence of these regimes on granular temperature
Slow dynamics and precursors of the glass transition in granular fluids
No full textWe use event driven simulations to analyze glassy dynamics as a function of density and energy dissipation in a two-dimensional bidisperse granular fluid under stationary conditions. Clear signatures of a glass transition are identified, such as an increase of relaxation times over several orders of magnitude. As the inelasticity is increased, the glass transition is shifted to higher densities, and the precursors of the transition become less and less pronounced, in agreement with a recent mode-coupling theory. We analyze the long-time tails of the velocity autocorrelation and discuss its consequences for the nonexistence of the diffusion constant in two dimensions
Long-Time Tails and Cage Effect in Driven Granular Fluids
No full textWe study the velocity autocorrelation function of a driven granular fluid in the stationary state in three dimensions. As the critical volume fraction of the glass transition in the corresponding elastic system is approached, we observe pronounced cage effects in the velocity autocorrelation function as well as a strong decrease of the diffusion constant, depending on the inelasticity. At moderate densities the velocity autocorrelation function is shown to decay algebraically in time, like t-3/2, if momentum is conserved locally, and like t-1, if momentum is not conserved by the driving. A simple scaling argument supports the observed long-time tails
Anomalous velocity distributions in active Brownian suspensions
No full textLarge-scale simulations and analytical theory have been combined to obtain the nonequilibrium velocity distribution, f(v), of randomly accelerated particles in suspension. The simulations are based on an event-driven algorithm, generalized to include friction. They reveal strongly anomalous but largely universal distributions, which are independent of volume fraction and collision processes, which suggests a one-particle model should capture all the essential features. We have formulated this one-particle model and solved it analytically in the limit of strong damping, where we find that f(v) decays as 1/v for multiple decades, eventually crossing over to a Gaussian decay for the largest velocities. Many particle simulations and numerical solution of the one-particle model agree for all values of the damping
Andrea Bacová
No full textAndrea Bacová focuses on research and teaching in the field of residential architecture. Her work includes systematic research on residential buildings and their urban context. She actively participates in promoting Slovak architecture and is the author of several publications and exhibitions
Viewer-, Author-, and Ownership in the Work of Andrea Zittel
Full text linkAndrea Zittel invites others to collapse the distinctions between artist, viewer, and collaborator by interacting with her usable works. This thesis explores the process of interacting with Zittel\u27s works, and how it affects viewer-, author- and ownership
The Lettere of Andrea Calmo: authorial artifices and historical reality
No full textopenNonostante l’edizione di Vittorio Rossi del 1888, la raccolta di "ingegnosi cheribizzi" e di "fantastiche fantasie" di Andrea Calmo è ancora avvolta da un certo mistero. L’autore, dissimulando la propria identità dietro alla “maschera” dell’umile pescatore veneziano, è stato in grado di offrire uno spaccato della cultura e della società nella Venezia cinquecentesca.
In particolare, è il quarto libro delle Lettere ad aver suscitato maggiore interesse tra gli studiosi ed i lettori: pubblicato nel 1566, a diversi anni di distanza dai primi tre, questo libro si distingue per il fatto che tutte le epistole sono indirizzate a delle donne immaginarie o realmente esistite.
In questa sede si propone, in primo luogo, uno studio della biografia del Calmo accompagnata da un’analisi del contesto storico-culturale della Venezia cinquecentesca; in secondo luogo, invece, viene proposto un commento di alcune lettere dell’ultimo libro dell’opera calmiana, che cerchi di far luce principalmente sull’aspetto linguistico e contenutistico del testo.Despite Vittorio Rossi's 1888 edition, Andrea Calmo's collection of "ingegnosi cheribizzi" and "fantastiche fantasie" is still shrouded in a certain mystery. The author, dissimulating his own identity behind the "mask" of the humble Venetian fisherman, was able to offer a cross-section of culture and society in sixteenth-century Venice.
In particular, it is the fourth book of the Letters that has aroused greater interest among scholars and readers: published in 1566, several years after the first three, this book stands out for the fact that all the epistles are addressed to women imaginary or actually existed.
Here we propose, first of all, a study of Calmo's biography accompanied by an analysis of the historical-cultural context of sixteenth-century Venice; secondly, however, a commentary on some letters from the last book of Calmo's work is proposed, which seeks to shed light mainly on the linguistic and content aspect of the text
Trusted Tales: Creating Authenticity in Literary Representations from Ex-Yugoslavia
No full textThis research deals with questions of authority and authenticity and how they are expressed, constructed, and appropriated within the Anglophone book market. It considers the body of literature written about ex-Yugoslavia since the 1990s Balkan conflicts by exiled writers from the region which has entered the international literary canon. Books’ routes from original publishers into English translation are discussed through practices of trust, one of the crucial social devices underpinning their exchange. Within these cross-cultural processes, the role of cultural brokers is crucial. Symbolic and cultural resources are specifically mobilised through their powerful author brands.
By exploring authenticity in the context of book publishing, I further look at how ideas and practices of community are employed and negotiated by writers and those who promote their books. My field is multi-sited and fluid, reflecting how different individual and national positions are enacted and performed through strategies ranging from unconscious dispositions to deliberate intentions. This research thus brings together ideas of the author as an authentic, representative voice together with exile as a position that grants them a new lease of relevancy in the post-socialist context.
Although ex-Yugoslav books occupy a ‘high end’ niche of the UK market, constrained by commercial as well as political, cultural, and institutional forces, in public discourse ideas of the ‘free market’ and ‘free speech’ are mobilised to produce various types of modernisation narratives. The (post)socialist production of literature is perceived as having to ‘evolve’ into a capitalist model: this would allow not only healthy competition and consumer choice but guarantee an individual writer ‘free speech’ as a basic human right. Therefore, the most general question this research raises is what kind of foreign literature gets translated into English, under what socio-cultural conditions and which politics of representation it serves within the project of world literature
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