131 research outputs found
Cognition-Based Networks: A New Perspective on Network Optimization Using Learning and Distributed Intelligence
IEEE Access
Volume 3, 2015, Article number 7217798, Pages 1512-1530
Open Access
Cognition-based networks: A new perspective on network optimization using learning and distributed intelligence (Article)
Zorzi, M.a , Zanella, A.a, Testolin, A.b, De Filippo De Grazia, M.b, Zorzi, M.bc
a Department of Information Engineering, University of Padua, Padua, Italy
b Department of General Psychology, University of Padua, Padua, Italy
c IRCCS San Camillo Foundation, Venice-Lido, Italy
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Abstract
In response to the new challenges in the design and operation of communication networks, and taking inspiration from how living beings deal with complexity and scalability, in this paper we introduce an innovative system concept called COgnition-BAsed NETworkS (COBANETS). The proposed approach develops around the systematic application of advanced machine learning techniques and, in particular, unsupervised deep learning and probabilistic generative models for system-wide learning, modeling, optimization, and data representation. Moreover, in COBANETS, we propose to combine this learning architecture with the emerging network virtualization paradigms, which make it possible to actuate automatic optimization and reconfiguration strategies at the system level, thus fully unleashing the potential of the learning approach. Compared with the past and current research efforts in this area, the technical approach outlined in this paper is deeply interdisciplinary and more comprehensive, calling for the synergic combination of expertise of computer scientists, communications and networking engineers, and cognitive scientists, with the ultimate aim of breaking new ground through a profound rethinking of how the modern understanding of cognition can be used in the management and optimization of telecommunication network
A QUIC Implementation for ns-3
Quick UDP Internet Connections (QUIC) is a recently proposed transport
protocol, currently being standardized by the Internet Engineering Task Force
(IETF). It aims at overcoming some of the shortcomings of TCP, while
maintaining the logic related to flow and congestion control, retransmissions
and acknowledgments. It supports multiplexing of multiple application layer
streams in the same connection, a more refined selective acknowledgment scheme,
and low-latency connection establishment. It also integrates cryptographic
functionalities in the protocol design. Moreover, QUIC is deployed at the
application layer, and encapsulates its packets in UDP datagrams. Given the
widespread interest in the new QUIC features, we believe that it is important
to provide to the networking community an implementation in a controllable and
isolated environment, i.e., a network simulator such as ns-3, in which it is
possible to test QUIC's performance and understand design choices and possible
limitations. Therefore, in this paper we present a native implementation of
QUIC for ns-3, describing the features we implemented, the main assumptions and
differences with respect to the QUIC Internet Drafts, and a set of examples.Comment: 8 pages, 4 figures. Please cite it as A. De Biasio, F. Chiariotti, M.
Polese, A. Zanella, M. Zorzi, "A QUIC Implementation for ns-3", Proceedings
of the Workshop on ns-3 (WNS3 '19), Firenze, Italy, 201
Model development and validation for a tank in tank water thermal storage for domestic application
5noThe hot water tanks are the typical thermal storage systems in Solar Domestic Hot Water (SDHW) plants. In this paper a new model for ESP-r has been developed, in order to simulate a tank in tank heat storage. The tank in tank system is made up of two tanks in which the smaller, storing potable hot water, is contained in a larger buffer filled with heating-circuit water. The developed model is an enhanced version of a component already available in ESP-r. Experimental results are used to identify some parameters and to perform the validation of the developed code.openopenPadovan, Roberta; Manzan, Marco; Zandegiacomo De Zorzi, Ezio ; GullĂŹ, Giuseppe; Frazzica, AndreaPadovan, Roberta; Manzan, Marco; ZANDEGIACOMO DE ZORZI, Ezio; GullĂŹ, Giuseppe; Frazzica, Andre
Templating porphyrin anisotropy via magnetically aligned carbon nanotubes
The preparation and characterisation of a novel threeâdimensional organic material consisting of porphyrin arrays on carbon nanotubes embedded in an organogel is reported. Firstly, the porphyrin array was prepared through metalâligand coordination of a ditopic ligand (1,2âbis(4âpyridyl)ethane) and two bisâZn(II) porphyrins, linked through a pyrene core, and was studied through UVâVis, NMR and diffusion spectroscopies. Secondly, the porphyrin supramolecular architecture was adsorbed on pristine carbon nanotubes, greatly improving the dispersibility of the latter in organic solvents. The hybrid material was characterised by means of UVâVis spectroscopy, microscopic techniques and thermogravimetric analysis. Finally, by exploiting the anisotropic magnetic susceptibility of carbon nanotubes, the hybrid material was aligned under a magnetic field, the organisation of which could be maintained by inâ
situ gelation. The resultant hybrid organogel exhibited notable optical anisotropy, suggesting an anisotropic arrangement of the porphyrinâCNTs architectures in the macroscopic material
Energy-Efficient Design for RIS-assisted UAV communications in beyond-5G Networks
EC/H2020/813999/EU//WINDMILLThe usage of Reconfigurable Intelligent Surfaces (RIS) in conjunction with Unmanned Ariel Vehicles (UAVs) is being investigated as a way to provide energy-efficient communication to ground users in dense urban areas. In this paper, we devise an optimization scenario to reduce overall energy consumption in the network while guaranteeing certain Quality of Service (QoS) to the ground users in the area. Due to the complex nature of the optimization problem, we provide a joint UAV trajectory and RIS phase decision to minimize transmission power of the UAV and Base Station (BS) that yields good performance with lower complexity. So, the proposed method uses a Successive Convex Approximation (SCA) to iteratively determine a joint optimal solution for UAV Trajectory, RIS phase and BS and UAV Transmission Power. The simulation results show the algorithm provides a minimum guaranteed rate while minimising transmission power of UAV and BS.Peer reviewe
Pd/PdO functionalization of SnO2 nanowires and ZnO nanotetrapods
Tin oxide (SnO2) and zinc oxide (ZnO) nanostructures are widely studied because of their peculiar physical and chemical properties and the large number of possible application fields. Among these application, nanostructure-based chemoresistive gas sensing devices are very promising because they are considered faster and more stable than traditional thin or thick film sensors. Metallic oxide gas sensors are usually very sensitive towards a large number of gases and volatile organic compounds (VOCs), but unfortunately their response is characterized by very low selectivity (the capability to distinguish among different gases). Selectivity enhancements by adding palladium/palladium oxide (Pd/PdO) nanoparticles to traditional film-based gas sensors are widely reported in literature and they are generally obtained by co-deposition or co-synthesis techniques (in sputtering, sol-gel, etc). SnO2 nanowires and ZnO nanotetrapods have been grown on large areas by a combination of metal evaporation and controlled oxidation. Unfortunately Pd and PdO nanoparticles cannot be directly obtained in the same growth process used for the synthesis of SnO2 or ZnO nanostructures, because the large difference in evaporation rates of these different metals and oxides excludes the chance of preforming a co-evaporation process. So, a MOCVD (Metal Organic Chemical Vapour Deposition) process has been chosen in order to deposit Pd/PdO nanoparticles on the surface of oxide nanostructures. Palladium acetylacetonate, Pd(acac)2, has been evaporated and thermally decomposed, in presence of a co-reagent gas, on the substrates with SnO2 and ZnO nanostructures in different experimental conditions and, then, the obtained samples has been annealed in air and/or hydrogen in order to remove carbon residual and/or change the oxidation state of palladium nanoparticles. Samples morphology, structure and composition have been studied by means of SEM and TEM microscopy, EDS microanalysis and X-Ray diffraction. The different results, obtained as a function of the synthesis and annealing parameters, are discussed aiming the attention to the experimental conditions that allowed the authors to obtain an optimal "spotted" coverage of oxide nanostructures, which is required for the gas sensing application
Potential of thermal storage for hot potable water distribution in cruise ships
Hot potable water preparation in ships requires lots of energy from the power plant; this is particularly true in modern cruise ships with a high demand of potable water for people, restaurants, spa and pools. Usually the required amount of hot water is instantly produced using a number of different energy sources available on board. However, the use of direct heaters on peak demand conditions increases fuel consumption and greenhouse gas emissions. This is especially important in the case of ship in port configuration, due to the reduced number of active engines and therefore the reduced amount of waste heat from the cooling line usually employed for this task.
This paper investigates possible solutions to size a hot water thermal storage in order to compensate the mismatch between heat generation during cruise and heat required during ship in port configuration. The performances of different solutions are compared using dynamic thermal simulations of the shipâs hot water distribution system with different regimes and time dependent heat requirements. Moreover it will be introduced the use of PCM materials with the aim to further improve systemâs performance
Potential of thermal storage for hot potable water distribution in cruise ships
Hot potable water preparation in ships requires lots of energy from the power plant; this is particularly true in modern cruise ships with a high demand of potable water for people, restaurants, spa and pools. Usually the required amount of hot water is instantly produced using a number of different energy sources available on board. However, the use of direct heaters on peak demand conditions increases fuel consumption and greenhouse gas emissions. This is especially important in the case of ship in port configuration, due to the reduced number of active engines and therefore the reduced amount of waste heat from the cooling line usually employed for this task.
This paper investigates possible solutions to size a hot water thermal storage in order to compensate the mismatch between heat generation during cruise and heat required during ship in port configuration. The performances of different solutions are compared using dynamic thermal simulations of the ship\u2019s hot water distribution system with different regimes and time dependent heat requirements. Moreover it will be introduced the use of PCM materials with the aim to further improve system\u2019s performance
Reliability of forced internal rotation and active internal rotation to assess lateral instability of the biceps pulley
Purpose: the aim of this study was to investigate the relationship between positive painful forced internal rotation (FIR) and lateral pulley instability in the presence of a pre-diagnosed posterosuperior cuff tear. The same investigation was conducted for painful active internal rotation (AIR).
Methods: a multicenter prospective study was conducted in a series of patients scheduled to undergo arthroscopic posterosuperior cuff repair. Pain was assessed using a visual analog scale (VAS) and the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH) was administered. The VAS score at rest, DASH score, and presence/absence of pain on FIR and AIR were recorded and their relationships with lesions of the lateral pulley, cuff tear patterns and shape of lesions were analyzed.
Results: the study population consisted of 115 patients (mean age: 55.1 years) recruited from 12 centers. The dominant arm was affected in 72 cases (62.6%). The average anteroposterior extension of the lesion was 1.61 cm. The mean preoperative VAS and DASH scores were 6.1 and 41.8, respectively. FIR and AIR were positive in 94 (81.7%) and 85 (73.9%) cases, respectively. The lateral pulley was compromised in 50 cases (43.4%). Cuff tears were partial articular in 35 patients (30.4%), complete in 61 (53%), and partial bursal in 19 (16.5%). No statistical correlation between positive FIR or AIR and lateral pulley lesions was detected. Positive FIR and AIR were statistically associated with complete lesions. Negative FIR was associated with the presence of partial articular tears.
Conclusions: painful FIR in the presence of a postero-superior cuff tear does not indicate lateral pulley instability. When a cuff tear is suspected, positive FIR and AIR are suggestive of full-thickness tear patterns while a negative FIR suggests a partial articular lesion.
Level of evidence: level I, validating cohort study with good reference standards
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