1,109 research outputs found
Supporting vPLC Networking over TSN with Kubernetes in Industry 4.0
No full textThe shift in the industrial ecosystem from closed and specialized technologies to the open and general-purpose vision of Industry 4.0 faces numerous challenges. The absence of viable solutions to replace Programmable Logic Controllers (PLCs), vital components in control infrastructures, with their virtual equivalent (vPLCs) embodies those difficulties. In this paper, we introduce a framework that aims at truly materializing the integration between Operational (OT) and Information Technologies (IT) by defining an open, general ecosystem around vPLCs. Previous work either could not meet the performance and determinism requirements of the OT or did so by sacrificing the generality of IT. Building on these experiences, our framework provides both flexibility and efficiency by clearly separating the data path for OT and IT communications. To do that, we integrate tools from both domains: techniques to ensure low network performance and variability (TSN), to ease portability (OPC-UA), and to enhance management and deployment (Kubernetes). Experiments on a real testbed show that vPLCs within our framework can meet strict performance requirements and yet provide the same flexibility as cloud-based applications
Tuning ultrafast electron injection dynamics at organic-graphene/metal interfaces
No full textThe properties of novel and prospective 2D materials are dramatically influenced by the interaction with a substrate. For example, the electronic hybridization of silicene states on Ag(111) or graphene ones on Ni(111) disrupts the Dirac fermions of the freestanding layers. This calls for efficient approaches to tune the interaction strength at the interface. Here we focus on the case of graphene functionalized by organic molecules and grown on Ni(111) and on the interfacial charge transfer dynamics. This is investigated by X-ray resonant photoemission spectroscopy, that is able to measure electron transfer rates occurring within few femtoseconds, and by a theoretical framework based on density-functional theory [1,2].
We use 4,4’-bipyridine as the prototypical molecule for these explorations as the energy level alignment of core-excited molecular orbitals allows ultrafast injection (τ=4fs) of electrons from the substrate to the molecule adsorbed on epitaxial graphene/Ni(111), which is characterized by a strong hybridization between C and metal states. We demonstrate that this interface can be decoupled by the addition of a second layer of graphene, where the one in contact with the metal acts as a buffer layer and the one in contact with the molecule is less hybridized with Ni underneath. As a result, the ultrafast injection of electrons from the substrate to the molecule is ∼4 times slower on weakly coupled bilayer graphene than on epitaxial graphene. Through our experiments and calculations, we can attribute this to a difference in the density of states close to the Fermi level between graphene and bilayer graphene. We therefore show how graphene coupling with the substrate influences charge transfer dynamics between organic molecules and graphene interfaces.
[1] G. Fratesi, C. Motta, M. I. Trioni, G. P. Brivio, and D. Sánchez-Portal, J. Phys. Chem. C 118, 8775 (2014)
[2] D. Cvetko, G. Fratesi, G. Kladnik, A. Cossaro, G.P. Brivio, L. Venkataraman, and A. Morgante, Phys. Chem. Chem. Phys. 18, 22140 (2016)
[3] A. Ravikumar, G. Kladnik, M. Müller, A. Cossaro, G. Bavdek, L. Patera, D. Sánchez-Portal, L. Venkataraman, A. Morgante, G. P. Brivio, D. Cvetko, and G. Fratesi, Nanoscale 10, 8014 (2018)
Enhancing the Performance of Industry 4.0 Scenarios via Serverless Processing at the Edge
No full textIndustry 4.0 aims to revolutionize and digitize the manufacturing sector by enabling and facilitating interoperability, solution agility, flexible (re)configuration of production chain(s) while, at the same time, reducing costs by exploiting real time data. These capabilities require to link the plant floor with data flows from/to the enterprise borders and include as core enabling technologies the Internet of Things (IoT), cloud, and edge computing key to move and execute parts of the business logic. The new capabilities might be leveraged in an innovative way, especially in the plant floor to dynamically change the monitoring/control logic of the smart machinery. In our reference scenario, the data flows originating from the plant floor can be processed and filtered locally, creating the basis for a selective Quality of Service (QoS) mechanism allowing for the implementation of reactive services, such as predictive maintenance. To that end, we propose an innovative serverless edge processing solution used for monitoring geo-distributed industrial plants. The proposal is validated in realistic settings, under different operational regimes, exhibiting acceptable performance trends under realistic periodic and variable traffic scenarios
Polygenic eruptions on Alba Patera, Mars
No full textA combination of photogeologic mapping, analysis of Viking Orbiter thermal inertia data, and numerical modelling of eruption conditions has permitted us to construct a new model for the evolution of the martian volcano Alba Patera. Numerous digitate channel networks on the flanks of the volcano are interpreted to be carved by sapping due to the release of non-juvenile water from unconsolidated flank deposits. Using the thermal inertia measurements, we estimate the particle size of these deposits to be 3-10 μm, which, together with theoretical modelling of the disperison of explosively derived volcanic materials, leads us to conclude that the flank deposits on Alba Patera are low-relief pyroclastic flows. The recognition of numerous late-stage summit and sub-terminal lava flows thus makes Alba Patera a unique martian volcano that is transitional between the older pyroclastic-dominated highland paterae and the more recent effusive central-vent volcanoes such as the Tharsis Montes
QoS-Enabled Semantic Routing for Industry 4.0 based on SDN and MOM Integration
No full textIndustry 4.0 environments pose unique challenges for the realization of the communication substrate at the shop floor, due to the strict Quality of Service (QoS) requirements, the high heterogeneity of the employed data exchange protocols, and the different network technologies and addressing schema toward the machines. To address those issues, the paper proposes a distributed support based on a Message Oriented Middleware (MOM) and a Software Defined Network (SDN) control plane that coordinate to enable semantic routing by also allowing traffic differentiation as well as in-network processing at intermediate network nodes. Seminal results, collected in realistic industrial settings, confirm the feasibility of our proposal
A Framework for QoS- Enabled Semantic Routing in Industrial Networks: Overall Architecture and Primary Protocols
No full textThe manufacturing sector represents a notable use case of the Industry 4.0 revolution, heavily stressing the capability of plants to ensure the desired QoS. Currently, manufacturing plants are characterized by an increasing amount of non-mission-critical traffic, in addition to traditional mission-critical safety-related traffic, which is negligible in comparison. Since computing and networking capabilities are no longer as abundant as in the past, there is the need to properly manage available resources. To ensure challenging QoS requirements, we propose a novel protocol suite specifically designed for our QoS-enabled semantic routing framework. Such a framework adopts an architecture that fits the characteristics of modern manufacturing environments and exploits an overlay networking solution providing a semantic routing substrate that operates both at the application and network layers
Cavity light bullets: 3D self-confined structures in a passive nonlinear resonator
No full textWe consider the paraxial model for a nonlinear resonator with a saturable absorber beyond the mean-field limit. We introduce a general stability analysis to evidence modulational-instabilities leading to the destabilization of a homogeneous field profile, eventually causing the formation of 3D structures. Further on, for accessible parametric domains, we show in simulations the phenomenon of total radiation confinement leading to the formation of 3D localized bright structures. Such structures are a direct generalization of 2D Cavity Solitons, recently observed in broad-area VCSELs, but they are confined also in the propagation dimension. At difference from freely propagating light bullets, here the self-organization proceeds from the resonator feedback/dissipation, combined with diffraction and nonlinearity
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