Higher Institute on Territorial Systems for Innovation
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Highly performing ionic liquid enriched hybrid RSDs
No full textA simple two terminal planar resistive switching device (RSD) is fabricated with a 10 mm active gap. The active hybrid matrix is based on a PEO, Ionic Liquid and Silver Nitrate formulation which represents a perfect polymeric medium for the growth of a conducting filament, whose creation/destruction is due to the migration of silver ions within the matrix. Two different device configurations are compared based on the electrode symmetry. The first case includes a planar symmetric device with electron beam evaporated gold electrodes, while the second is based on a planar asymmetrical device with sputtered platinum and electron beam evaporated silver electrodes. The asymmetric device exhibits a continuous resistive switching up to 500 cycles by maintaining an outstanding on/off ratio of 104 throughout the test without any compromise in its retention. The fabrication of reliable soft (hybrid) materials is of paramount importance for the development of next generation wearable devices that must be stretchable and flexible; planar microelectronic systems, better than stacked ones, are compatible with high throughput production technologies such as printing, where uniformity is controlled on a higher scale in comparison to standard lithographic processes. The present work provides clear-cut evidence of the conducting filament formation/dissolution during the resistive switching process of a soft material. A detailed explanation is given on the formation and rupture of the same
Magnetite-epoxy nanocomposites obtained by the reactive suspension method: Microstructural, thermo-mechanical and magnetic properties
No full textMagnetite nanoparticles are prepared by non-hydrolytic sol-gel process in the presence of iron(III)-acetylacetonate as precursor and 2-ethyl-1,3-hexanediol as reactive solvent; the nanoparticle size is affected by the precursor-to-solvent ratio. The suspensions, mixed with bisphenol-A diglycidyl ether, are cured in the presence of ytterbium(III) trifluoromethanesulfonate as cationic initiator. The chain-growth polymerization results in a three-dimensional network where the diol, acting at the same time as reactive solvent and suspending medium, is covalently linked to the epoxy network according to the "activated monomer" mechanism. The filler induces stiffening because of hydrodynamic effects and of a better cross-linking ability in the nanocomposite. Magnetite nanoparticles form aggregates whose size and shape depend on concentration. Isothermal magnetization loops and FC/ZFC DC susceptibility curves indicate that all nanocomposites are dominated by interparticle magnetic interactions resulting in a collective response whose details depend on nanoparticle concentration and degree of aggregation
An Experimental Investigation of the Dynamics of a Blade with Two Under-Platform Dampers
No full textSeveral experimental apparatus have been designed in the past to evaluate the effectiveness of under-platform dampers. Most of these experimental setups allow to measure the overall damper efficiency in terms of reduction of vibration amplitude in turbine blades. The experimental data collected with these test rigs do not increase the knowledge about the damper dynamics and therefore the uncertainty on the damper behavior remains a big issue. In this paper a different approach to evaluate the damper-blade interaction has been put forward. A test rig has been purposely designed to accommodate a single blade and two under-platform dampers. One side of each damper is in contact with a ground support specifically designed to measure two independent forces on the damper. In this way both the normal and the tangential force components in the damper-blade contact can be inferred. Damper kinematics is rebuilt by using the relative displacement measured between damper and blade. This paper describes the concept behind the new approach, shows the details of the new test rig and discuss the blade frequency response from a new point of view
2017 Emerging Scholar Award-Spaces & Flows: Eighth International Conference on Urban and ExtraUrban Studies
No full textFor each conference, a small number of Emerging Scholar Awards are given to outstanding graduate students and emerging scholars who have an active academic interest in the conference area. The Award with its accompanying responsibilities provides a strong professional development opportunity for early career academics. The 2017 Emerging Scholar Awardees are listed below
Transient thermal analysis of a lithium-ion battery pack comparing different cooling solutions for automotive applications
No full textThis paper presents a computational modeling approach to characterize the internal temperature distribution within a Li-Ion battery pack. In the mathematical formulation both entropy-based and irreversible-based heat generation have been considered; combined with CFD software in order to simulate the temperature distribution and evolution in a battery pack. A prismatic Li-ion phosphate battery is tested under constant current discharge/charge rates of 1C, 2C, 5C and 8C. Model parameters (in particular, the entropic heat coefficient and the internal resistance) needed for the calibration of the model are determined using experimentation. The model is then used to simulate two different strategies for the thermal control of a battery pack in case of car application: an air-cooling and a liquid-cooling strategy. The simulation has highlighted the pros and cons of the two strategies, allowing a good understanding of the needs during the process of battery pack design and production
Learning from Nature: using bioinspired approaches and natural materials to make porous bioceramics
No full textEnergy-efficient Traffic Allocation in SDN-based Backhaul Networks: Theory and Implementation
No full text5G networks are expected to be highly energy efficient, with a 10 times lower consumption than today's systems. An effective way to achieve such a goal is to act on the backhaul network by controlling the nodes operational state and the allocation of traffic flows. To this end, in this paper we formulate energy-efficient flow routing on the backhaul network as an optimization problem. In light of its complexity, which impairs the solution in large-scale scenarios, we then propose a heuristic approach. Our scheme, named EMMA, aims to both turn off idle nodes and concentrate traffic on the smallest possible set of links, which in its turn increases the number of idle nodes. We implement EMMA on top of ONOS and derive experimental results by emulating the network through Mininet. Our results show that EMMA provides excellent energy saving performance, which closely approaches the optimum. In larger network scenarios, the gain in energy consumption that EMMA provides with respect to the simple benchmark where all nodes are active, is extremely high under medium-low traffic load