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Sonetti G.,Polytechnic University of Turin | Lombardi P.,Polytechnic University of Turin | Chelleri L.,Gran Sasso Science Institute GSSI
Sustainability (Switzerland) | Year: 2016

Campus greening is often the first step universities take towards sustainability. However, the diffusion of sustainability reporting methodologies and rankings is still at an early stage, and is biased in mainly measuring energy efficiency indicators while omitting basic features enabling meaningful comparisons among centers or addressing social (users) aspects related to long term sustainability transitions. This paper aims to introduce a critical perspective on sustainability university frameworks through: (i) a review of current Campus Sustainability Assessments (CSAs); (ii) performing and comparing the results obtained from the application of two internationally recognized CSAs (namely, Green Metric and ISCN) to two case studies (the Politecnico di Torino, in Italy, and the Hokkaido University, In Japan) and, finally, (iii) proposing a new CSA approach that encompasses clusters of homogeneous campus typologies for meaningful comparisons and university rankings. The proposed clusters regard universities' morphological structures (campuses nested within city centers versus outside of a city compact ones), climatic zones and functions. At the micro scale, the paper introduces the need for indicators beyond measuring pure energy efficiency, but which are attentive to local and societal constraints and provide long-term tracking of outcomes. This, better than a sheer record of sustainability priority actions, can help in building homogenous university case studies to find similar and scalable success strategies and practices, and also in self-monitoring progress toward achieving truly sustainable university campuses. © 2016 by the authors. Source

Guglielmi N.,University of LAquila | Guglielmi N.,Gran Sasso Science Institute GSSI | Laglia L.,University of LAquila | Protasov V.,Moscow State University
Foundations of Computational Mathematics | Year: 2015

We present a new approach for constructing polytope Lyapunov functions for continuous-time linear switching systems (LSS). This allows us to decide the stability of LSS and to compute the Lyapunov exponent with a good precision in relatively high dimensions. The same technique is also extended for stabilizability of positive systems by evaluating a polytope concave Lyapunov function (“antinorm”) in the cone. The method is based on a suitable discretization of the underlying continuous system and provides both a lower and an upper bound for the Lyapunov exponent. The absolute error in the Lyapunov exponent computation is estimated from above and proved to be linear in the dwell time. The practical efficiency of the new method is demonstrated in several examples and in the list of numerical experiments with randomly generated matrices of dimensions up to 10 (for general linear systems) and up to 100 (for positive systems). The development of the method is based on several theoretical results proved in the paper: the existence of monotone invariant norms and antinorms for positively irreducible systems, the equivalence of all contractive norms for stable systems and the linear convergence theorem. © 2015 SFoCM Source

Baruah S.,University of North Carolina at Chapel Hill | Bonifaci V.,CNR Institute for System Analysis and Computer Science Antonio Ruberti | D'Angelo G.,Gran Sasso Science Institute GSSI | Li H.,Google | And 3 more authors.
Journal of the ACM | Year: 2015

Systems in many safety-critical application domains are subject to certification requirements. For any given system, however, it may be the case that only a subset of its functionality is safety-critical and hence subject to certification; the rest of the functionality is non-safety-critical and does not need to be certified, or is certified to lower levels of assurance. The certification-cognizant runtime scheduling of such mixedcriticality systems is considered. An algorithm called EDF-VD (for Earliest Deadline First with Virtual Deadlines) is presented: this algorithm can schedule systems for which any number of criticality levels are defined. Efficient implementations of EDF-VD, as well as associated schedulability tests for determining whether a task system can be correctly scheduled using EDF-VD, are presented. For up to 13 criticality levels, analyses of EDF-VD, based on metrics such as processor speedup factor and utilization bounds, are derived, and conditions under which EDF-VD is optimal with respect to these metrics are identified. Finally, two extensions of EDF-VD are discussed that enhance its applicability. The extensions are aimed at scheduling a wider range of task sets, while preserving the favorable worst-case resource usage guarantees of the basic algorithm. © 2015 ACM. Source

D'Emidio M.,Gran Sasso Science Institute GSSI | D'Emidio M.,University of LAquila | Frigioni D.,University of LAquila | Navarra A.,University of Perugia
Electronic Notes in Theoretical Computer Science | Year: 2016

In this paper, we consider the distributed setting of computational mobile entities, called robots, that have to perform tasks without global coordination. Depending on the environment as well as on the robots' capabilities, tasks might be accomplished or not. In particular, we focus on the well-known scenario where the robots reside on the nodes of a graph and operate in Look-Compute-Move cycles. In one cycle, a robot perceives the current configuration in terms of robots positions (Look), decides whether to move toward some edge of the graph (Compute), and in the positive case it performs an instantaneous move along the computed edge (Move). We then compare two basic models: in the first model robots are fully synchronous, while in the second one robots are asynchronous and lights-enhanced, that is, each robot is equipped with a constant number of lights visible to all other robots. The question whether one model is more powerful than the other in terms of computable tasks has been considered in [Das et al., Int.'l Conf. on Distributed Computing Systems, 2012] but for robots moving on the Euclidean plane rather than on a graph. We provide two different tasks, and show that on graphs one task can be solved in the fully synchronous model but not in the asynchronous lights-enhanced model, while for the other task the converse holds. Hence we can assert that the fully synchronous model and the asynchronous lights-enhanced model are incomparable on graphs. This opens challenging directions in order to understand which peculiarities make the models so different. © 2016 The Authors. Published by Elsevier B.V. Source

Evoli C.,Gran Sasso Science Institute GSSI | Evoli C.,University of Hamburg | Gaggero D.,International School for Advanced Studies | Grasso D.,University of Pisa
Journal of Cosmology and Astroparticle Physics | Year: 2015

We present a novel determination of the astrophysical uncertainties associated to the secondary antiproton flux originating from cosmic-ray spallation on the interstellar gas. We select a set of propagation models compatible with the recent B/C data from PAMELA, and find those providing minimal and maximal antiproton fluxes in different energy ranges. We use this result to determine the most conservative bounds on relevant Dark Matter (DM) annihilation channels: we find that the recent claim of a DM interpretation of a gamma-ray excess in the Galactic Center region cannot be ruled out by current antiproton data. Finally, we discuss the impact of the recently released preliminary data from AMS-02. In particular, we provide a reference model compatible with proton, helium and B/C spectra from this experiment. Remarkably, the main propagation parameters of this model are in agreement with the best fit presented in our earlier statistical analyses. We also show that the antiproton-to-proton ratio does not exhibit any significant anomaly at high energy with respect to our predictions. © 2015 IOP Publishing Ltd and Sissa Medialab srl . Source

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