Multi-Provider Service Chain Embedding With Nestor

Network function (NF) virtualization decouples NFs from the underlying middlebox hardware and promotes their deployment on virtualized network infrastructures. This essentially paves the way for the migration of NFs into clouds (i.e., NF-as-a-Service), achieving a drastic reduction of middlebox investment and operational costs for enterprises. In this context, service chains (expressing middlebox policies in the enterprise network) should be mapped onto datacenter networks, ensuring correctness, resource efficiency, as well as compliance with the provider's policy. The network service embedding (NSE) problem is further exacerbated by two challenging aspects: 1) traffic scaling caused by certain NFs (e.g., caches and WAN optimizers) and 2) NF location dependencies. Traffic scaling requires resource reservations different from the ones specified in the service chain, whereas NF location dependencies, in conjunction with the limited geographic footprint of NF providers (NFPs), raise the need for NSE across multiple NFPs. In this paper, we present a holistic solution to the multi-provider NSE problem. We decompose NSE into: 1) NF-graph partitioning performed by a centralized coordinator and 2) NF-subgraph mapping onto datacenter networks. We present linear programming formulations to derive near-optimal solutions for both problems. We address the challenging aspect of traffic scaling by introducing a new service model that supports demand transformations. We also define topology abstractions for NF-graph partitioning. Furthermore, we discuss the steps required to embed service chains across multiple NFPs, using our NSE orchestrator (Nestor). We perform an evaluation study of multi-provider NSE with emphasis on NF-graph partitioning optimizations tailored to the client and NFPs. Our evaluation results further uncover significant savings in terms of service cost and resource consumption due to the demand transformations. © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works..EU/FP7/T-NOVA/619520DFG/Collaborative Research Center/1053 (MAKI)EU/FP7/T-NOVADFG/CRC/105

Implementing Network Virtualization for a Future Internet

Abstract — The Internet has become an essential communication medium upon which billions of people rely every day. However, necessary evolution of the Internet has been severely limited by reliability constrains and social-economic factors. Experts fear that current growth rates will threaten the future of the Internet as a whole, despite the fact that new core technologies already exist. Network virtualization presents a promising approach to overcome ossification and facilitate service deployment for a future Internet. Exploring this approach, we present a prototype implementation which realizes a subset of the 4WARD virtual network (VNet) architecture, allowing multiple VNets to coexist on top of a shared physical infrastructure. We discuss the functionality of our prototype and demonstrate experimental results to assess its performance. I

Flowstream Architectures

The Internet has seen a proliferation of specialized middlebox devices that carry out crucial network functionality such as load balancing, packet inspection or intrusion detection, amongst others. Traditionally, high performance network devices have been built on custom multi-core, specialized memory hierarchies, architectures which are well suited to packet processing. Recently, commodity PC hardware has experienced a move to multiple multi-core chips, as well as the routine inclusion of multiple memory hierarchies in the so-called NUMA architectures. While a PC architecture is obviously not specifically targeted to network applications, it nevertheless provides high performance cheaply. Furthermore, a few commodity switch technologies have recently emerged offering the possibility to control the switching of flows in a rather fine grained manner. Put together, these new technologies offer a new network commodity platform enabling new flow processing and forwarding at an unprecedented flexibility and low cost

FL learning could contribute to the enhancement of cognitive functions in MCI older adults

The purpose of the current research endeavour was to evaluate if the learning of English as a Foreign Language (EFL) could constitute an effective non-pharmacological intervention for older adults diagnosed with Mild Cognitive Impairment (MCI). Specifically, the focus was on the assessment of the impact of EFL learning on a variety of cognitive and psychological functions. To this aim, a total sample of 241 Greek older adults was recruited from the day care units for patients with dementia of the Greek Association of Alzheimer’s Disease and Related Disorders, in Thessaloniki, Greece. An experimental research design was adopted and two groups were formulated. The intervention group comprised 98 individuals who attended an18-month EFL course and either had no prior knowledge of English or had attended some lessons decades before. The control group included 143 individuals who did not attend any cognitive stimulation programme within the premises of the day care units. A battery of neuropsychological tests, assessing general cognitive functioning, attention, verbal learning, memory, visuo-perceptual ability, executive function, and depression, was administered by the psychologists of the day care units to all of the participants. Neuropsychological data for the intervention group were collected at three time-points (i.e. pre-, mid-, and post-intervention), while neuropsychological data for the control group were collected at two time-points (i.e. pre- and post-research). Hypothesis testing revealed statistically significant differences both within the intervention group and between the intervention and control group across the evaluation time-points

ΜΕΛΕΤΗ ΑΠΟΣΤΑΓΜΑΤΩΝ ΣΤΕΜΦΥΛΩΝ ΚΑΙ ΠΡΟΣΔΙΟΡΙΣΜΟΣ ΚΑΛΙΟΥ ΚΑΙ ΝΑΤΡΙΟΥ ΣΕ ΔΕΙΓΜΑΤΑ ΤΟΥΣ

Η ποιότητα των αποσταγμάτων σταφυλής ή στεμφύλων σταφυλής είναι το αποτέλεσμα συνδυασμού πολλών παραγόντων. Αρχικά η πρώτη ύλη, η καταλληλότητα της οποίας εξαρτάται από την ποικιλία της αμπέλου , τις εδαφοκλιματικές συνθήκες του αμπελώνα, την ηλικία, τις διάφορες καλλιεργητικές φροντίδες , το βαθμό ωριμότητας, την υγιεινή κατάσταση των σταφυλιών, την τεχνική γλευκοποίησης και οινοποίησης, τα στελέχη των ζυμομυκήτων,τις συνθήκες καλλιέργειάς τους, καθώς και τις συνθήκες συντήρησης των οίνων μέχρι την απόσταξη. Η ποιότητα του αποστάγματος εξαρτάται ακόμα από την τεχνική της απόσταξης, η οποία περιλαμβάνει τον τύπο της αποστακτικής συσκευής, τη μεθοδολογία, τον τρόπο διαχωρισμού του αποστάγματος σε τρία μέρη: Κεφαλή, Καρδιά και Ουρά , τις συνθήκες και το χρόνο της απόσταξης. Η εργασία αυτή αναλύει τη διαδικασία της απόσταξης από τον μεσαίωνα έως τα σύγχρονα εργαστήρια, τις κατηγορίες των αποσταγμάτων, τον τρόπο παρασκευής του τσίπουρου( παραδοσιακή-σύγχρονη απόσταξη ,άμβυκας, παρουσία χαλκού κ.α) και τη συστασή του. Κατόπιν αναλύονται δείγματα τσίπουρου (αποστάγματα) της ευρύτερης περιοχής του Τυρνάβου , στα οποία προσδιορίζεται ο αλκοολικός τίτλος και τέλος πραγματοποιείται ποσοτικός προσδιορισμός των ανόργανων στοιχείων καλίου και νατρίου με τη μέθοδο της φασματομετρίας ατομικής απορρόφησης. Στο τέλος της εργασίας, αναφέρονται τα συμπεράσματα που ανέκυψαν απ’ τις αναλύσεις των δειγμάτων.The quality of grape distillates or grape marc is the result of a combination of many factors. Originally the raw material, the suitability of which depends on the variety of the vine, the soil and climate conditions of the vineyard, the age, the various cultivation care, the degree of maturity, the healthy condition of the grapes, the melting and winemaking technique, the yeast strains , Their growing conditions, and the conditions under which the wine is preserved until distilled. The quality of the distillate still depends on the distillation technique, which includes the type of distillation device, the methodology, how the distillate is divided into three parts: Head, Heart and Tail, the conditions and the time of distillation. This paper analyzes the process of distillation from the Middle Ages to the modern laboratories, the categories of distillates, the way of making the tsipouro (traditional-modern distillation, nymph, the presence of copper etc.) and its composition. Then samples of tsipouro (spirits) from the broader area of ​​Tyrnavos are analyzed, in which the alcoholic strength is determined, and quantitative determination of the inorganic elements of potassium and sodium is performed by atomic absorption spectrometry. At the end of the work, the conclusions that emerged from sample analyzes are reported

Identification of dynamic models of Metsovo (Greece) Bridge using ambient vibration measurements

Available methods for structural model updating are employed to develop high fidelity models of the Metsovo bridge using ambient vibration measurements. The Metsovo bridge, the highest bridge of the Egnatia Odos Motorway, is a two-branch balanced cantilever ravine bridge. It has a total length of 357m, a very long central span of 235m, and a height of 110m for the taller pier. Ambient vibration measurements are available during different construction phases of the bridge for both bridge branches, as well as after the completed construction phases of the bridge. Operational modal analysis software is used to obtain the modal characteristics of the bridge for the various sets of vibration measurements. The modal characteristics are then used to update an increasingly complex set of finite element models of the bridge. These models are based on beam and solid elements. A multi-objective structural identification method is used for estimating the parameters of the finite element structural models based on minimising the modal residuals. The method results in multiple Pareto optimal structural models that are consistent with the measured modal data and the modal residuals used to measure the discrepancies between the measured modal values and the modal values predicted by the model. Single objective structural identification methods are also evaluated as special cases of the proposed multi-objective identification method. The effectiveness of the updated models and their predictive capabilities are assessed. In particular, the variability of the Pareto optimal models and their associated response prediction variability are explored. It is demonstrated that the Pareto optimal structural models may vary, depending on the fidelity of the model class employed and the size of measurement errors. The developed high fidelity finite element models are used for checking design assumptions and for carrying out more accurate predictions of structural response

Wpływ miasta na dobowe minima temperatury powietrza w Salonikach

The absolute minimum daily temperatures of three meteorological stations in the region of Thessaloniki are used, that is the meteorological station at the Aristotle's University of Thessaloniki (1950-1995), the meteorological station of the airport Mikra (1960-1995) and the meteorological station of the old military airport of Sedes (1950-1970). The mean monthly, seasonal and annual minimum temperatures have been calculated for all three stations; also the daily differences between temperature data from the stations of the University and the airport Mikra have been calculated, for their common period (1960-1995). Finally, an interpretation of the results has been attempted.Do badań użyto absolutne minima dobowe temperatury powietrza z trzech stacji meteorologicznych w rejonie Salonik: stacji Uniwersytetu im. Arystotelesa (1950-1995), lotniska Mikra (1960-1995) oraz starego lotniska wojskowego Sedes (1950-1970). Obliczono średnie miesięczne, średnie w poszczególnych sezonach oraz średnie roczne minima temperatury. Obliczono także różnice temperatury pomiędzy stacją uniwersytecką a lotniskiem Mikra dla wspólnego okresu (1960-1995). Dokonano próby interpretacji otrzymanych wyników