Network slicing to enable scalability and flexibility in 5G mobile networks

We argue for network slicing as an efficient solution that addresses the diverse requirements of 5G mobile networks, thus provid-ing the necessary flexibility and scalability associated with future network implementations. We elaborate on the challenges that emerge when we design 5G networks based on network slicing. We focus on the architectural aspects associated with the coexistence of dedicated as well as shared slices in the network. In particular, we analyze the realization options of a flexible radio access network with focus on network slicing and their impact on the design of 5G mobile networks. In addition to the technical study, this paper provides an investigation of the revenue potential of network slicing, where the applications that originate from such concept and the profit capabilities from the network operator's perspective are put forward.This work has been performed in the framework of the H2020-ICT-2014-2 project 5G NORMA

Application of a tribocorrosion test protocol to detect the surface state behaviour of AlCuFeCr and AlMg complex metallic alloys

edition: Biotribology - Bridging Engineering and Medicinestatus: publishe

Tribo-electrochemical characterization of metallic biomaterials for total joint replacement

Knee and hip joint replacement implants involve a sliding contact between the femoral component and the tibial or acetabular component immersed in body fluids, thus making the metallic parts susceptible to tribocorrosion. Micro-motions occur at points of fixation leading to debris and ion release by fretting corrosion. beta-Titanium alloys are potential biomaterials for joint prostheses due to their biocompatibility and compatibility with the mechanical properties of bone. The biotribocorrosion behavior of Ti-29Nb-13Ta-4.6Zr was studied in Hank's balanced salt solution at open circuit potential and at an applied potential in the passive region. Reciprocating sliding tribocorrosion tests were carried out against technical grade ultra high molecular weight polyethylene, while fretting corrosion tests were carried out against alumina. The wear of the alloy is insignificant when sliding against polyethylene. However, depassivation does take place, but the tested alloy showed an ability to recover its passive state during sliding. The abrasivity of the alloy depends on the electrochemical conditions of the contact, while the wear of polyethylene proceeds through third body formation and material transfer. Under fretting corrosion conditions recovery of the passive state was also achieved. In a fretting contact wear of the alloy proceeds through plastic deformation of the bulk material and wear resistance depends on the electrochemical conditions. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

A methodology for the assessment of the tribocorrosion of passivating metallic materials

International audienceThe synergism between mechanical friction and corrosion may lead to an acceleration of the degradation of materials in sliding contacts exposed to the environment. Electrochemical measurements and sliding tests are proposed as a protocol suitable to decouple the material losses originating from the active material and the passive film, and to identify their electrochemical or mechanical nature. The corrosion resistance of a material, its ability to react onto chemical or mechanical attack, its susceptibility to tribocorrosion and the effect of a passive surface film on the coefficient of friction are evaluated. The proposed tribo-electrochemical protocol allows to evaluate the potential and risks of applying newly developed materials in sliding contacts, and to support the selection and implementation of materials in industry in applications where corrosion and wear are potential degradation processes. This protocol extends the existing Standard Guide ASTM G 119-04 'Determining Synergism between wear and Corrosion' for passivating metallic materials

Tribocorrosion behavior of beta titanium alloys in physiological solutions containing synovial components

In this work, the tribocorrosion behavior of Ti-12.5Mo, Ti-13Nb-13Zr and Ti-29Nb-13Ta-4.6Zr beta titanium alloys which are candidate biomaterials for joint prostheses is studied against ultra high molecular weight polyethylene in Hank's balanced salt solution. Ti-6Al-4Fe alpha+beta titanium alloy is also tested for comparison. Experiments were carried out at open circuit potential and at a passive applied potential using a pin-on-flat reciprocating sliding tribo-electrochemical apparatus. The potential, anodic current and friction coefficient were measured in situ as a function of time. The beta alloys exhibited a tendency to repassivate during sliding at passive and open circuit potential. The predominant wear mechanism of the metal-polyethylene pairs was 3 body wear, exhibited by the transfer of polyethylene to all titanium alloys. Polyethylene showed a comparatively low wear against beta titanium alloys. The effect of the addition of synovial fluid constituents, namely bovine serum albumin, hyaluronic acid and dipalmitoyphosphatidylcholine on the tribocorrosion of Ti-29Nb-13Ta-4.6Zr alloy was also studied. The presence of additives affected the friction coefficient, induced an increase of the wear volume, and a modification of the dominant wear mechanism which was identified as abrasion without transfer of polyethylene. (C) 2010 Elsevier B.V. All rights reserved

Assessment of the surface state behaviour of Al71Cu10Fe9Cr10 and Al3Mg2 complex metallic alloys in sliding contacts

International audienceElectrochemical measurements and friction measurements during continuous and intermittent unidirectional sliding tests are used to monitor and to evaluate the surface characteristics of two types of metallic materials characterized by a huge unit cell, namely Al71Cu10Fe9Cr10 and Al3Mg2. The modification of the surface characteristics results from the periodic mechanical removal of a surface film during sliding, and the subsequent (electro)chemical re-growth of a surface film in-between successive sliding contacts. Al71Cu10Fe9Cr10 and Al3Mg2 materials were tested in a phosphate buffer solution pH 7 at 25 degrees C to compare their depassivation and subsequent repassivation behaviour. The Al3Mg2 material was also tested in a 0.1 M KOH solution pH 13 and 25 degrees C to reveal the role of constituting metallic elements on the surface film formation. The effect of film formation and removal on the coefficient of friction recorded during unidirectional sliding is discussed

On the fate of oxygen in a spent fuel emplacement drift in Opalinus Clay

Persistence of aerobic conditions after backfilling of a spent fuel emplacement drift is of high relevance for the selection of canister material and canister design, as well as for the prediction of the onset of H2 production. This paper presents the results of the O2 monitoring during the backfilling and early heating phases of the Full-scale Emplacement Experiment at the Mont Terri underground laboratory (Switzerland), as well as the first results of laboratory experiments and 3D reactive transport modelling which aim at identifying the processes controlling O2 concentrations. The monitoring shows the disappearance of gaseous O2 and onset of anaerobic corrosion in sections not affected by O2 inflow from the access tunnel within weeks after backfilling, and even before closure of the drift for the deepest parts of the experiment. The laboratory experiments show that O2 can significantly adsorb on granular bentonite exposed to high temperatures and might in principle also adsorb at ambient temperature and relative humidity as low as 55%. Thus, gas sorption should be considered in the balance of O2 in the experiment. These results are consistent with the numerical model indicating that the excavation damaged zone but also the bentonite backfill are the main sinks for O2, whereas corrosion of metallic components seems to play a negligible role. Previous studies estimated the duration of aerobic conditions in an emplacement drift between a few years and several decades; our results show that anaerobic conditions may be reached within a few weeks up to maximum a few months after closure of an emplacement drift for spent fuel

Assessment of the surface state behaviour of Al₇₁Cu₁₀Fe₉Cr₁₀ and Al₃Mg₂ complex metallic alloys in sliding contacts

Electrochemical measurements and friction measurements during continuous and intermittent unidirectional sliding tests are used to monitor and to evaluate the surface characteristics of two types of metallic materials characterized by a huge unit cell, namely Al₇₁Cu₁₀Fe₉Cr₁₀ and Al₃Mg₂. The modification of the surface characteristics results from the periodic mechanical removal of a surface film during sliding, and the subsequent (electro)chemical re-growth of a surface film in-between successive sliding contacts. Al₇₁Cu₁₀Fe₉Cr₁₀ and Al₃Mg₂ materials were tested in a phosphate buffer solution pH 7 at 25 °C to compare their depassivation and subsequent repassivation behaviour. The Al₃Mg₂ material was also tested in a 0.1 M KOH solution pH 13 and 25 °C to reveal the role of constituting metallic elements on the surface film formation. The effect of film formation and removal on the coefficient of friction recorded during unidirectional sliding is discussed.status: publishe

Simulating Bandwidth-Limited Worms, One Graph to Rule Them All? 1,2

Due to ethical and practical limitations, simulations are the de facto approach to measure and predict the propagation of malicious code on the Internet. A crucial part of every simulation is the network graph that is used to perform the experiments. Though recent evidence brought to light the nature of many technological and socio-technical networks such as the web links, the physical connectivity of the Internet and the e-mail correspondents, we argue that the interpretation of these findings has to be strongly correlated with specific malware properties. Furthermore, we question whether these graphs are accurate enough to model the fastest spreading type of malicious activity, bandwidth-limited worms. Finally, we propose some workarounds, by introducing a new Bandwidth-Aware Graphs Generation Algorithm, in order to generate specially crafted network graphs for the simulation of this type of malicious activity