Time resolved PIV measurements of the unsteady wake migration in a LPT blade passage: effect of the wake passing frequency

A time resolved Particle Image Velocimetry (TR-PIV) system has been employed to investigate the unsteady propagation of upstream wakes in a low-pressure turbine cascade. Data are obtained in the steady state condition and for two passing wake reduced frequencies. The study is focused on the identification and split of the different dynamics responsible for deterministic and random oscillations, thus loss generation. A very large data set has been collected: for each condition, about 9000 instantaneous flow fields have been acquired at up to 2kHz in order to resolve with great detail the vortex shedding phenomenon characterizing the separation at steady condition as well as the propagation of the coherent structures induced by the incoming wake. Instantaneous vector maps, phase averaged velocity fields and Proper Orthogonal Decomposition (POD) have been used for the in depth characterization of the different phenomena. The paper takes advantage of the properties of POD that reduces the data set to a low number of modes that represent the most energetic dynamics of the system. It is clearly shown that the phase averaged flow field can be represented by a few number of POD modes related to the wake passing event for the unsteady cases. POD is also able to capture flow features affecting the instantaneous flow field not directly related to the wake passage (i.e. the vortex shedding phenomenon induced by the intermittent separation developing between adjacent wakes), that are smeared out in the phase averaged results. Once recognized the POD modes most involved in the unsteady flow field, a procedure for the quantification of the different contributions to the overall amount of losses is proposed

Slice Isolation for 5G Transport Networks

Network slicing plays a key role in the 5G ecosystem for vertical industries to introduce new services. However, one widely-recognized challenge of network slicing is to provide traffic isolation and concurrently satisfy diverse performance requirements, e.g., bandwidth and latency. In this work, we showcase the capability to retain these two goals at the same time, via extending the 5Growth baseline architecture and designing a new data-plane pipeline, i.e., virtual queue, over the P4 switch. To demonstrate the effectiveness of our approach, a proof-of-concept is presented serving different service requests over a mixed data path, including P4 switches and Open vSwitches (OvSs)

Performance isolation for network slices in Industry 4.0: The 5Growth approach

Network slicing plays a key role in the 5G ecosystem for verticals to introduce new use cases in the industrial sector, i.e., Industry 4.0. However, a widely recognized challenge of network slicing is to provide traffic isolation and concurrently satisfy diverse performance requirements, e.g., bandwidth and latency. Such challenge becomes even more important when serving a large number of network traffic flows under a resource-limited condition between distributed sites, e.g., factory floor and remote office. In this work, we present the capability to retain these two goals at the same time, by applying the virtual queue notion over a priority queuing based pipeline in P4 switch over software-defined networks. To examine the effectiveness of our approach, a proof-of-concept is setup to serve different requests of Industry 4.0 use cases over a mixed data path, including P4 switch and Open vSwitch, for a large number of network flows.This work was supported in part by the EU H2020 5GROWTH Project under Grant 856709

L'INQUADRAMENTO SINTASSONOMICO DEI BOSCHI A QUERCUS CERRIS ED OSTRYA CARPINIFOLIA DEL FLYSCH NELL'APPENNINO MARCHIGIANO SETTENTRIONALE

SYNTAXONOMY OF QUERCUS CERRIS AND OSTRYA CARPINIFOLIA WOODS IN THE NORTHERN APENNINES OF THE MARCHE REGION (ITALY). The AA. discuss the syntaxonomy of Quercus cerris and Ostrya carpinifolia woods in the northern Apennines of Marche region (Pesaro-Urbino province), with special reference to communities growing on flysch soils. According to cluster analysis by average linkage, the following types are recognized: a) Aceri (obtusati)-Quercetum cerris (Ubaldi 1979) em, colline-submontane association, including mixed woods with Quercus cerris, Ostrya carpinifolia, Acer obtusatum and Fraxinus ornus; b) Seslerio (italicae) Ostryetum (Ubaldi 1974) em., including Ostrya carpinifolia woods on little deep soils of marl-calcareous flysch; this type lies in the montane belt, in the Cephalanthero-Fagetum zone; c) Ostrya carpinifolia Fagus sylvatica-Calamagrostis varia community; mountain woods near to Cephalanthero-Fagetum sociology; d) Arisaro (proboscidei)-Carpinetum ass. nova, including Quercus cerris-Carpinus betulus-Fagus sylvatica woods, occurring in the Aceri (obtusati)-Quercetum cerris belt. These types may be included in a Orno-Ostryon, floristically delimited by Lilium croceum, Laburnum anagyroides, Ostrya carpinifolia and Acer obtusatum. Compared to Orno-Ostryon of yugoslav Authors, and particularly to Ostryo-Carpinion orientalis, it is more mesophilous and near to Capinion betuli. According to our present knowledges, this Orno-Ostryon lies in the Central and Northern Apennines and in the Centrai Pre-Alps too. For this vegetation Ubaldi(1981) has suggested the name Laburno-Ostryon carpinifoliae

Distinction phytosociologique entre Ostryo-Carpinion et Quercion ilicis en Italie

Since Ostryo-Carpinion orientalis and Quercion ilicis oak-woods are in contact, both in Italy and Balkan peninsula, they show strong floristic connexions. The problem of their phytosociological distinction in Italy is approached by a comparison based on synoptical columns. Species which enable floristic distinction between these alliances are pointed out.Les chênaies de l'Ostryo-Carpinion orientalis et du Quercion ilicis entrent en contact en Italie et dans la péninsule balkanique, donnant lieu à de fortes interconnexions floristiques. Le problème de la distinction phytosociologique entre ces deux alliances en Italie a été abordé à l’aide d’une comparaison de colonnes synoptiques. Les espèces qui permettent le mieux de séparer les groupements de l’un et de l’autre syntaxon sont mises en évidence. On remarque aussi que la physionomie n’est pas toujours significative pour distinguer les deux types de chênaies, et il arrive que des chênaies sclérophylles ou mixtes sont attribuables à l'Ostryo-Carpinion et vice versa des chênaies caducifoliées au Quercion ilicis.Ubaldi Davide, Zanotti Anna L. Distinction phytosociologique entre Ostryo-Carpinion et Quercion ilicis en Italie. In: Ecologia mediterranea, tome 20 n°3-4, 1994. pp. 137-149

POD Analysis of the Unsteady Behavior of a Laminar Separation Bubble

Particle Image Velocimetry (PIV) measurements have been performed in order to analyze the unsteady flow field developing along the separated flow region of a laminar separation bubble. Data have been post-processed by means of Proper Orthogonal Decomposition (POD) to improve the understanding of the physics of this complex phenomenon. The paper shows that the first two POD modes of the normal to the wall velocity component are coupled. Thus, they are representative of a vortex shedding phenomenon which is identified to be induced by Kelvin\u2013Helmholtz instability. The POD allows the phase identification of each PIV image within the vortex shedding cycle. The computed eigenvectors are used to sort the experimental snapshots and then reconstruct a phase-averaged velocity field which highlighted the motion of vortices shed close to the bubble maximum displacement. Moreover, other sources of deterministic fluctuations characterized by frequencies which are different from the one induced by the Kelvin\u2013 Helmholtz instability are also revealed. Indeed, the most energetic POD mode of the streamwise velocity component is not related to the shedding frequency, while it describes large velocity fluctuations in the shear layer region upstream of the bubble maximum displacement, where the turbulent activity is not yet present. The POD decomposition presented here identifies the large scale structures within the flow, thus separately accounts for both coherent and stochastic contributions to the overall energy of the velocity fluctuations