1,158 research outputs found
Green buildings and design for adaptation: strategies for renovation of the built environment
The recent EU Directives 2010/31 and 2012/27 provide standards of nearly zero energy buildings for new constructions, aiming at a better quality of the built environment through the adoption of high-performance solutions. In the near future, cities are expected to be the main engine of development while bearing the impact of population growth: new challenges such as increasing energy efficiency, reducing maintenance costs of buildings and infrastructures, facing the effects of climate change and adjusting on-going and future impacts, require smart and sustainable approaches. To improve the capability of adaptation to dynamics of transformation, buildings and districts have to increase their resilience, assumed as ‘the capacity to adapt to changing conditions and to maintain or regain functionality and vitality in the face of stress or disturbance’ (Wilson A., Building Resilience in Boston, Boston Society of Architects, 2013). This paper describes the research methodology, developed by the Department of Architecture, a research unit of Technology for Architecture, to perform the assessment of resilience of existing buildings, as well as the outcomes of its application within Bologna urban context. This methodology focuses on the design for adaptation of social housing buildings, aiming at predicting their expected main impacts (energy consumption, emissions, efficiency, urban quality and environmental sustainability) and at developing models for renovation
Aristotle, Eleaticism, and Zeno’s Grains of Millet
This paper explores how Aristotle rejects some Eleatic tenets in general and some of Zeno’s views in particular that apparently threaten the Aristotelian “science of nature.” According to Zeno, it is impossible for a thing to traverse what is infinite or to come in contact with infinite things in a finite time. Aristotle takes the Zenonian view to be wrong by resorting to his distinction between potentiality and actuality and to his theory of mathematical proportions as applied to the motive power and the moved object (Ph. VII.5). He states that some minimal parts of certain magnitudes (i.e., continuous quantities) are perceived, but only in potentiality, not in actuality. This being so, Zeno’s view that a single grain of millet makes no sound on falling, but a thousand grains make a sound must be rejected. If Zeno’s paradoxes were true, there would be no motion, but if there is no motion, there is no nature, and hence, there cannot be a science of nature. What Aristotle noted in the millet seed paradox, I hold, is that it apparently casts doubt on his theory of mathematical proportions, i.e., the theory of proportions that holds between the moving power and the object moved, and the extent of the change and the time taken. This approach explains why Aristotle establishes an analogy between the millet seed paradox, on the one hand, and the argument of the stone being worn away by the drop of water (Ph. 253b15–16) and the hauled ship, on the other
Electron-phonon interaction in Graphite Intercalation Compounds
Motivated by the recent discovery of superconductivity in Ca- and
Yb-intercalated graphite (CaC and YbC) and from the ongoing debate
on the nature and role of the interlayer state in this class of compounds, in
this work we critically study the electron-phonon properties of a simple model
based on primitive graphite. We show that this model captures an essential
feature of the electron-phonon properties of the Graphite Intercalation
Compounds (GICs), namely, the existence of a strong dormant electron-phonon
interaction between interlayer and electrons, for which we
provide a simple geometrical explanation in terms of NMTO Wannier-like
functions. Our findings correct the oversimplified view that
nearly-free-electron states cannot interact with the surrounding lattice, and
explain the empirical correlation between the filling of the interlayer band
and the occurrence of superconductivity in Graphite-Intercalation Compounds.Comment: 13 pages, 12 figures, submitted to Phys. Rev.
Experimental tests to recover the photovoltaic power by battery system
The uncertainty and variability of the Renewable Energy Sources (RES) power plants within the power grid is an open issue. The
present study focuses on the use of batteries to overcome the limitations associated with the photovoltaic inverter operation,
trying to maximize the global energy produced. A set of switches, was placed between a few photovoltaic modules and a
commercial inverter, capable to change configuration of the plant dynamically. Such system stores the power that the inverter is
not able to let into the grid inside batteries. At the base of this optimization, there is the achievement of two main configurations
in which the batteries and the photovoltaic modules are electrically connected in an appropriate manner as a function of inverter
efficiency and thus solar radiation. A control board and the relative program, to change the configuration, was designed and
implemented, based on the value of the measured radiation, current, batteries voltage, and calculated inverter efficiency. Finally
from the cost and impact analysis we can say that, today the technology of lithium batteries, for this application, is still too
expensive in comparison with lead-acid batteries
The role of the dopant in the superconductivity of diamond
We present an {\it ab initio} study of the recently discovered
superconductivity of boron doped diamond within the framework of a
phonon-mediated pairing mechanism. The role of the dopant, in substitutional
position, is unconventional in that half of the coupling parameter
originates in strongly localized defect-related vibrational modes, yielding a
very peaked Eliashberg function. The electron-phonon
coupling potential is found to be extremely large and T is limited by the
low value of the density of states at the Fermi level
The challenge of unravelling magnetic properties in LaFeAsO
First principles calculations of magnetic and, to a lesser extent, electronic
properties of the novel LaFeAsO-based superconductors show substantial apparent
controversy, as opposed to most weakly or strongly correlated materials. Not
only do different reports disagree about quantitative values, there is also a
schism in terms of interpreting the basic physics of the magnetic interactions
in this system. In this paper, we present a systematic analysis using four
different first principles methods and show that while there is an unusual
sensitivity to computational details, well-converged full-potential
all-electron results are fully consistent among themselves. What makes results
so sensitive and the system so different from simple local magnetic moments
interacting via basic superexchange mechanisms is the itinerant character of
the calculated magnetic ground state, where very soft magnetic moments and
long-range interactions are characterized by a particular structure in the
reciprocal (as opposed to real) space. Therefore, unravelling the magnetic
interactions in their full richness remains a challenging, but utterly
important task
Effect of Pressure on Superconducting Ca-intercalated Graphite CaC
The pressure effect on the superconducting transition temperature () of
the newly-discovered Ca-intercalated graphite compound CaC has been
investigated up to 16 kbar. is found to increase under pressure
with a large relative ratio / of +0.4 %/kbar. Using
first-principles calculations, we show that the large and positive effect of
pressure on can be explained in the scope of electron-phonon theory due
to the presence of a soft phonon branch associated to in-plane vibrations of Ca
atoms. Implications of the present findings on the current debate about the
superconducting mechanism in graphite intercalation compounds are discussed.Comment: 6 pages, 5 figs, final PRB versio
The Redevelopment of The Heritage of Social Housing in Italy: Survey and Assessment Instruments. The Case Study of Pilastro Neighborhood in Bologna
Abstract The increasing importance of social housing in order to deal with the emergency caused by the pressing demand, places in the foreground the need to redevelop the existing public housing heritage. The paper proposes the deepening of one case study, the Pilastro neighborhood, a significant example of social housing high density settlement, situated in the outskirts of Bologna in order to brought out the technical, functional and social factors, on which the level of quality of the settlement and the phenomena of social uneasiness depend. It also highlighted some factors that may pose a resistance to the measures of improvement
"PROXIMITY" AS A DESIGN STRATEGY FOR SUSTAINABLE, COLLABORATIVE AND INCLUSIVE URBAN PUBLIC SPACES
Public spaces at neighbourhood scale represent the main scenario of citizens’ life, nodes that define an archipelago of places with a key role in promoting and fostering the enhancement and maintenance of the built environment through mutual collaboration. This network of open and built spaces traces the reference infrastructure of urban planning and redevelopment models, based on proximity as device for physical and social relationship, central in the post-pandemic city debate.
“The city of proximity” is the first focus addressed by the Atelier of Urban Innovation Lab in Bologna: an exhibition and laboratory space for comparison and co-design of public space, housed inside the City Hall of the Italian metropolitan city of Bologna and co-curated by the Department of Architecture, University of Bologna and the city agency Foundation for the Urban Innovation.
The Atelier explores urban dynamics and contemporary challenges using analogue and digital tools investigating the potential of the ecosystem defining the realm of the everyday dynamics – for instance, squares, courtyards, markets, libraries, urban gardens, playgrounds, sport equipment, etc. In addition to the physical transformations linked to the concept of proximity, the design process, the actors involved and the results obtained are considered relevant.
This paper, framing the topic on transition city issues, addresses the potential, transversal andrecurrent features of neighborhood spaces with the aim of acknowledging replicable strategies and design practices for collaborative cities based on new form of citizen democracy that encourage the reactivation of places, community creation, resilience to climate change and sustainable mobility, as
experimented by the lab-like environment of Urban Innovation Lab Bologna
“El alma es, en cierto modo, todas las cosas existentes” (Aristóteles, De anima 431b21): Una discusión crítica del De anima a propósito de una edición y traducción reciente
José Manuel García Valverde, Aristóteles. Sobre el alma, Madrid: CSIC, 2019, 398 pp., 28.85 €, ISBN 978-84-00-10552-
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