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Non-local order parameters as a probe for phase transitions in the extended Fermi-Hubbard model
No full textThe Extended Fermi-Hubbard model is a rather studied Hamiltonian due to both its many applications and a rich phase diagram. Here we prove that all the phase transitions encoded in its one dimensional version are detectable via non-local operators related to charge and spin fluctuations. The main advantage in using them is that, in contrast to usual local operators, their asymptotic average value is finite only in the appropriate gapped phases. This makes them powerful and accurate probes to detect quantum phases. Our results indeed confirm that they are able to properly capture both the nature and the location of the transitions. Relevantly, this happens also for conducting phases with a spin gap, thus providing an order parameter for the identification of superconducting and paired superfluid phases
Study and results of an onboard brake monitoring system for freight wagons
No full textThis paper presents the background study, the development and the tests of a monitoring system for intermodal freight wagon. The prototype of the on-board unit, developed by the research group of Railway Engineering of Politecnico di Torino, was installed and tested on an intermodal freight wagon owned by the company Ambrogio Trasporti S.p.a. as part of the project ITS Cluster Italy 2020. Significant advances have been made in the field of freight train monitoring. In recent years, many companies have presented specific devices with the aim of monitoring the operating conditions of goods wagons. The developed prototype was tested on real track. The main vehicle parameters monitored during the tests were the temperature of brake blocks, the operating pressures of the brake system, and the vehicle accelerations. The measurements allowed the team to verify the effectiveness and reliability of the monitoring system in harsh conditions. The significant amount of measured data were then used to validate a first energetic model useful for subsequently developing monitoring and diagnostic algorithms
NFV service dynamicity with a DevOps approach: insights from a use-case realization
No full textThis experience paper describes the process of leveraging the NFV orchestration platform built in the EU FP7 project UNIFY to deploy a dynamic network service exemplified by an elastic router. Elasticity is realized by scaling dataplane resources as a function of traffic load. To achieve this, the service includes a custom scaling logic and monitoring capabilities. An automated monitoring framework not only triggers elastic scaling, but also a troubleshooting process which detects and analyzes anomalies, pro-actively aiding both dev and ops personnel. Such a DevOps-inspired approach enables a shorter update cycle to the running service. We highlight multiple learnings yielded throughout the prototype realization, focussing on the functional areas of service decomposition and scaling; programmable monitoring; and automated troubleshooting. Such practical insights will contribute to solving challenges such as agile deployment and efficient resource usage in future NFV platforms
Fouling release of UV-cured acrylic coatings: Set-up of an in vitro test with Rhodotorula mucilaginosa
No full textAcrylic coatings were prepared by UV-induced crosslinking of two different diacrylates monomers having the same molecular weight but containing either a polyethyleneoxide chain or an alkylic chain. The fouling behavior of the UV-cured coatings was assessed by a simple set-up, monitoring the growth of Rhodotorula mucilaginosa and the adhesion of the film formed by the pigmented yeast. The effect of the monomers, the photoinitiator and the polymers on the microorganismgrowthwas studied. Themonomers partially inhibited the yeast growth, the coatings showed fouling release activity: yeast could grow on both coatings but with different morphology, they detached easily by washing depending on the type of coating. By examining the physico-chemical and mechanical properties of the polymers, the fouling release behavior was found mostly dependent on the surface tension and the water uptake of the coatings
Vibration control and mitigation in turbomachinery
No full textThe thesis project is directly concerned with safety and reliability as it addresses the problem of High Cycle Fatigue (HCF) failure of turbine blades. Turbine blades can be found in engines used to power aircrafts and electrical generators. Statistics suggest that on average 2.5 HCF events occur on each new design engine. These failures happen suddenly, as resonant vibrations cause cracks which usually propagate very rapidly. Since it is often impossible to avoid the presence and growth of such resonant vibrations, designers frequently incorporate dry friction devices into turbine designs. Typical examples of friction dampers are shrouds, snubbers and underplatform dampers. Despite the continuous effort found in the literature in terms of modeling and optimization strategies, the lack of knowledge on the damping mechanism and on the parameters used to characterize it cause problems at all levels of the life cycle of bladed disks. The design process is uncertain, and therefore lengthy and costly because the knowledge of the dynamic behavior of the system has to be substituted with extensive experimental verifications. Furthermore, the imperfect knowledge of the real life expectancy of components prevents scheduling opportune periodic maintenance leading to potential safety hazard and logistical problems associated with unreliability. The focus of the dissertation is on under-platform dampers and their effect on bladed disks. All numerical models of friction-damped bladed arrays require information of contact parameters. The main goal is to face part of this knowledge limitation through a purposely developed experimental-numerical method. Direct measurements on dampers are used to estimate contact parameters to be used as input to a state-of-the-art numerical model. The numerical model, validated against independent experimental evidence, is proven to be predictive, thus paving the way to the creation of a reliable design and optimization tool
Occupational Safety and Health in highway maintenance yards: An approach suitable to face special criticalities
No full textOn the request of Prosecutor Office, the Authors carried out a research work to define the extent of the Occupational Safety and Health - OS&H criticalities affecting the highway maintenance yards, in normal and special scenarios where hazardous freights are involved. The high number of work related accidents in maintenance/improvement yards, often characterized by dramatic Severity Rates, requires a special Risk Assessment and Management. The paper summarizes the results of a research leading to identify the main parameters directly or indirectly conditioning the design and safety of the highway maintenance yards. We developed a schematization of yard typologies and contexts, upon which a thorough Risk Assessment and Management becomes possible. Moreover, an original Accident Analysis Technique provided precious support to the study, filling the gaps of information on the Standards violations of some accident databases. Finally, the paper discusses some innovative Safety Control measures for different highway scenarios
Effects of carbon black and graphene nano-platelet fillers on the mechanical properties of syntactic foam
No full textMechanical properties of an epoxy based syntactic foams are discussed in this study. Basic syntactic foam, composed of 30% of hollow glass spheres by volume, was modified with a 1% volume fraction addition of graphene nano-platelets (GnP), treated GnPs and carbon black (CB). In treated GnPs the hollow glass spheres and the GnPs were treated with 1-Pyrenecarboxaldehyde in xylene. The flexural, tensile, compressive and Izod properties of the five different combinations of these syntactic foams, both reinforced and not reinforced, were measured and compared with the pristine epoxy. The tests show that the reinforced foams had a higher modulus in all cases. The maximum tensile load decreased with the addition of the GnPs, while it increased when CBs were used. Scanning electron micrographs were used to evaluate the dispersion of the filler in the epoxy matrix and the interaction between matrix and fillers
Utilizzo delle nuove tecnologie per la diffusione della conoscenza - Responsabilizzazione degli utenti attraverso il gioco
No full textNegli ultimi anni il tema del risparmio energetico è al centro di un vivo dibattito a livello europeo. Per raggiungere questo scopo , un metodo molto efficace è rappresentato dalla gamification , che prevede l'utilizzo di elementi e principi legati al mondo del gioco in contesti slegati da esso. Attraverso questo approccio si riesce quindi a instaurare una comunicazione con le giovani generazioni che, utilizzando diverse tecnologie innovative come la Realtà Virtuale e Aumentata, vengono sensibilizzate sul tema del risparmio energetico. Tale metodo è stato applicato nell'ambito del progetto DIMMER, in cui l'approccio al gioco ha assunto una grande importanza all'interno delle attività di disseminazione
Scenari geopolitici e sicurezza energetica. Una metodologia per quantificare il rischio degli approvvigionamenti
No full textLa sicurezza energetica è un tema chiave nell'agenda dei decisori politici e il suo legame con la geopolitica non può essere trascurato. La possibilità di disporre di strumenti scientifici per quantificarla, come la metodologia proposta in questo articolo, diventa una necessità per pianificare scelte e strategie. Diversi scenari geopolitici potrebbero avere un impatto notevole sulla disponibilità di energia, nonché sulle capacità delle imprese energetiche di soddisfare le richieste e competere sul mercato globale
