Search results for "LESS"
showing 10 items of 2452 documents
Light-induced anomalous Hall effect in massless Dirac fermion systems and topological insulators with dissipation
2019
Employing the quantum Liouville equation with phenomenological dissipation, we investigate the transport properties of massless and massive Dirac fermion systems that mimics graphene and topological insulators, respectively. The massless Dirac fermion system does not show an intrinsic Hall effect, but it shows a Hall current under the presence of circularly-polarized laser fields as a nature of a optically-driven nonequilibrium state. Based on the microscopic analysis, we find that the light-induced Hall effect mainly originates from the imbalance of photocarrier distribution in momentum space although the emergent Floquet–Berry curvature also has a non-zero contribution. We further compute…
A novel technique for the CMRR improvement in a portable ECG system
2017
This paper presents a new technique to improve the quality of the ECG signals, increasing the Common Mode Rejection Ratio (CMRR). We developed a portable wireless Bluetooth ECG system able to acquire 12 leads, communicating with Smartphones and PCs. Many experiments have been made for measuring CMRR decay due to the difference on skin-electrodes impedances, the asymmetries of the amplifiers input stages and external components. Using some digital potentiometers, the system is able to compensate for these, increasing the CMRR of about 18 dB.
Bluetooth Base Station Minimal Deployment for High Definition Positioning
2005
This paper discusses our approach to the problem of arranging a Bluetooth based positioning system capable of providing people coordinates in a given area with an accuracy as high as possible. Our strategy focuses on optimizing the disposition of a minimal number of available Bluetooth base stations in a subset of locations which are the only ones permitted by site characteristics and constraints. We used a genetic algorithm to this purpose and a layout chromosome whose best evolution suggested us how to deploy a minimal set of Bluetooth base stations. As a case study, we discuss our experiments and results which deal with a late middle age castle in Sicily where we carried out many trials.
A hybrid storage system for wireless sensor nodes powered with energy harvesting
2019
With the recent development of Internet of Things (IoT) and Wireless Sensor Networks (WSN), research and industry have been increasingly focusing on the opportumty of collecting the energy arising from the environment. The Energy Harvesting provides the possibility to supply devices which are placed out of reach or in hazardous spots, e.g. the Wireless Sensor Nodes. Among the different parts belonging to an Energy Harvesting system, the power management network represents a challenging topic. In this paper a Hybrid Energy Storage System (HESS) usable for a WSN powered with Energy Harvesting, based on a battery-capacitor integration, is presented. The experimental results concerning the asse…
Compliance of IEEE 802.22 WRAN for field area network in smart grid
2016
Distributed power system network is going to be complex, and it will require high-speed, reliable and secure communication systems for managing intermittent generation with coordination of centralised power generation, including load control. Cognitive Radio (CR) is highly favourable for providing communications in Smart Grid by using spectrum resources opportunistically. The IEEE 802.22 Wireless Regional Area Network (WRAN) having the capabilities of CR use vacant channels opportunistically in the frequency range of 54 MHz to 862 MHz occupied by TV band. A comprehensive review of using IEEE 802.22 for Field Area Network in power system network using spectrum sensing (CR based communication…
A low power protocol to broadcast real-time data traffic in a clustered ad hoc network
2002
Energy saving is an extremely important design criteria for mobile ad hoc networks. We present the intra-cluster data-dissemination protocol (Icdp). The Icdp is used to group nodes around a special one, called the cluster leader (CL). The CL centralizes the power management mechanism and acts as a proxy for data transfer between the cluster and the rest of the nodes in the region. When a cluster node enables the power management it goes into "sleep" mode, to minimize power consumption. The CL buffers data frames for power saving stations and delivers them on the stations' request. We periodically distribute the cluster leader role among all the nodes inside the cluster, to not overload a si…
Strategies and Techniques for Powering Wireless Sensor Nodes through Energy Harvesting and Wireless Power Transfer
2019
The continuous development of internet of things (IoT) infrastructure and applications is paving the way for advanced and innovative ideas and solutions, some of which are pushing the limits of state-of-the-art technology. The increasing demand for Wireless Sensor Nodes (WSNs) able to collect and transmit data through wireless communication channels, while often positioned in locations that are difficult to access, is driving research into innovative solutions involving energy harvesting (EH) and wireless power transfer (WPT) to eventually allow battery-free sensor nodes. Due to the pervasiveness of radio frequency (RF) energy, RF EH and WPT are key technologies with the potential to power …
An Energy Autonomous and Battery-Free Measurement System for Ambient Light Power with Time Domain Readout Measurement
2021
Internet of Things (IoT) provides more and more adequate infrastructures for many applications and advanced services. This context promotes the ability to satisfy the growing demand for innovative measuring systems, in- creasingly popular with intelligent nodes, totally wireless, easy to install that require the least possible maintenance. This paper aims to contribute to the state-of-the-art with an energy-autonomous and battery-free measurement platform designed to measure the ambient light power when its level exceeds the Limit of Detection (LoD) threshold. The proposed system consists of a single photovoltaic transducer to harvest energy and simultaneously detect ambient light. The resu…
Precarietà, flessibilità e teoria del capitale umano
2018
A partire da un punto di vista in debito con le analisi di Foucault, si cercherà di inquadrare la questione della precarietà all’interno della più ampia prospettiva dell’egemonia del neoliberalismo. In particolare, dopo aver descritto alcune delle peculiarità delle forme di vita precarie, ci si soffermerà sul programma di ricerca sul capitale umano, con il quale la riflessione pedagogica non può non aprire un confronto. A tal proposito, alla fine dell’articolo, verranno prese brevemente in esame alcune potenziali alternative al dispositivo teorico del capitale umano.
A Low-level Simulation Study of Prioritization in IEEE 802.11e Contention-based Networks
2006
This work deals with the performance evaluation of the IEEE 802.11e EDCA proposal for service prioritization in Wireless LANs. A large amount of study has been carried out in the scientific community to evaluate the performance of the EDCA proposal, mainly in terms of throughput and access delay differentiation. However, we argue that further performance insights are needed in order to fully understand the principles behind the EDCA prioritization mechanisms. To this purpose, rather than limit our investigation on throughput and delay performance figures, we take a closer look to their operation also in terms of low-level performance metrics (such as probability of accessing specific channe…