Force Percolation Transition of Jammed Granular Systems

The mechanical and transport properties of jammed materials originate from an underlying per- colating network of contact forces between the grains. Using extensive simulations we investigate the force-percolation transition of this network, where two particles are considered as linked if their interparticle force overcomes a threshold. We show that this transition belongs to the random percolation universality class, thus ruling out the existence of long-range correlations between the forces. Through a combined size and pressure scaling for the percolative quantities, we show that the continuous force percolation transition evolves into the discontinuous jamming transition in the zero pressure limit, as the size of the critical region scales with the pressure.Comment: 5 pages, 5 figure

A [3]-catenane non-autonomous molecular motor model: geometric phase, no-pumping theorem, and energy transduction

We study a model of synthetic molecular motor - a [3]-catenane consisting of two small macrocycles mechanically interlocked with a bigger one - subjected to a time-dependent driving using stochastic thermodynamics. The model presents nontrivial features due to the two interacting small macrocycles, but is simple enough to be treated analytically in limiting regimes. Among the results obtained, we find a mapping into an equivalent [2]-catenane that reveals the implications of the no-pumping theorem stating that to generate net motion of the small macrocycles, both energies and barriers need to change. In the adiabatic limit (slow driving), we fully characterize the motor's dynamics and show that the net motion of the small macrocycles is expressed as a surface integral in parameter space which corrects previous erroneous results. We also analyze the performance of the motor subjected to a step-wise driving protocols in absence and in presence of an applied load. Optimization strategies for generating large currents and maximizing free-energy transduction are proposed. This simple model provides interesting clues into the working principles of non-autonomous molecular motors and their optimization.Comment: 14 pages, 5 figure

A Novel Method for Online Detection of Faults Affecting Execution-Time in Multicore-Based Systems

This article proposes a bounded interference method, based on statistical evaluations, for online detection and tolerance of any fault capable of causing a deadline miss. The proposed method requires data that can be gathered during the profiling and worst-case execution time (WCET) analysis phase. This article describes the method, its application, and then it presents an avionic mixed-criticality use case for experimental evaluation, considering both dual-core and quad-core platforms. Results show that faults that can cause a timing violation are correctly identified while other faults that do not introduce a significant temporal interference can be tolerated to avoid high recovery overheads

A chemical reaction network implementation of a Maxwell demon

We study an autonomous model of a Maxwell demon that works by rectifying thermal fluctuations of chemical reactions. It constitutes the chemical analog of a recently studied electronic demon. We characterize its scaling behavior in the macroscopic limit, its performances, and the impact of potential internal delays. We obtain analytical expressions for all quantities of interest, namely, the generated reverse chemical current, the output power, the transduction efficiency, and the correlations between the numbers of molecules. Due to a bound on the nonequilibrium response of its chemical reaction network, we find that, contrary to the electronic case, there is no way for the Maxwell demon to generate a finite output in the macroscopic limit. Finally, we analyze the information thermodynamics of the Maxwell demon from a bipartite perspective. In the limit of a fast demon, the information flow is obtained, its pattern in the state space is discussed, and the behavior of the partial efficiencies related to the measurement and the feedback processes is examined.Comment: 16 pages, 3 figure

Analisi socio-demografica della Sardegna (secc. XIX-XXI): approcci micro e macro

In the two last centuries many socio-demographic variables (such as mortality, fertility and remarriage) in Sardinia have shown a quite singular pattern, if compared to those observed for the rest of Italy. In this work the analysis of these phenomena is carried out both at micro and macro level, taking into account their effects on social and economic context. Based on the rich set of individual data referring to the community of Alghero, the micro approach aims to explain how demographic, cultural, environmental and economic factors influenced stillbirth and infant mortality rates as well as propensity to remarriage for the years 1866-1925. In order to highlight territorial differentials still present in Sardinia, the macro approach focuses on the estimation of municipal indicators of fertility and mortality in the second half of 20th century. From this starting point, a forecast of the population and the main demographic indicators of the Sardinian municipalities is proposed

Maturity Models in Industrial Internet: a Review

The introduction of assembly lines in industrial plants marked the beginning of the third industrial revolution. The support of information technology has enabled continuous progresses, up to the digitalisation of the processes. In this context, the further innovation characterised by the introduction of Cyber-Physical Systems and other enabling technologies has allowed the fourth industrial revolution. Proposed by the German government, Industry 4.0 appealed to both researchers and practitioners. Since the appearance of the term Industry 4.0, the linked-term Industrial Internet has been introduced to indicate the technology stack and knowledge management required by Industry 4.0. Industrial Internet makes a factory smart by applying advanced information and communication systems and future-oriented technologies, as well as new principles of knowledge management. Undeniably, such a system introduces greater complexity in terms of technologies, knowledge and socio-cultural aspects. Companies are often unprepared to deal with innovation issues, because they lack knowledge and competences and they are not culturally prepared for the relative novelties, but especially because they lack the necessary technological pre-requisites to develop the appropriate technology stack. From this perspective, different models of maturity have been developed, both in academic and technical environments, to support companies in understanding their position within the paradigm of the Industrial Internet. Starting from a quantitative review of the maturity models designed in the general literature, this article develops a qualitative review of the models applied in Industry 4.0, characterising all relevant models and proposing future perspectives to improve existing models and develop new ones