Search results for " sensor"
showing 10 items of 1714 documents
Fractional Modeling of the AC Large-Signal Frequency Response in Magnetoresistive Current Sensors
2013
Fractional calculus is considered when derivatives and integrals of non-integer order are applied over a specific function. In the electrical and electronic domain, the transfer function dependence of a fractional filter not only by the filter order n, but additionally, of the fractional order α is an example of a great number of systems where its input-output behavior could be more exactly modeled by a fractional behavior. Following this aim, the present work shows the experimental ac large-signal frequency response of a family of electrical current sensors based in different spintronic conduction mechanisms. Using an ac characterization set-up the sensor transimpedance function is obtain…
Preamble Sampling MAC Protocol for Low Power Wireless Sensor Networks with IEEE 802.15.4 Transceivers
2006
In this paper a preamble sampling MAC protocol for low power wireless sensor networks is proposed. The article describes the implementation of the protocol using network nodes equipped with the Chipcon CC2420 802.15.4 transceiver. The power consumption of the transceiver has been measured and the MAC protocol has been adapted to the transceiver properties. The results show the trade-off between power consumption and transmission delay for this algorithm during the communication process.
A Battery-free Asset Monitoring System based on RF Wireless Power Transfer
2020
In the Internet of Things (IoT) era, asset monitoring represents an appealing implementation of Wireless Sensor Networks due to the enormous benefits associated with being able to monitor and record the exact position and transportation conditions of assets, personal objects, and the like. This kind of infrastructure enables the provision of increasingly advanced services, including the ability to measure the movement speed of a monitored asset using relatively inexpensive nodes with sensing capabilities and wireless transmission and reception. These nodes would ideally employ battery-free sensors that do not require any maintenance, but conventional power supply management systems cannot s…
Radiometric Partial Discharge Detection: A Review
2023
One of the most common failures or breakdowns that can occur in high-voltage (HV) equipment is due to partial discharges (PDs). This occurs as a result of inadequate insulation, aging, harsh environmental effects, or manufacturing flaws. PD detection and recognition methods have gained growing attention and have seen great progress in the past decades. Radiometric methods are one of the most investigated detection approaches due to their immunity to electromagnetic interference (EMI) and their capabilities to detect and locate PD activities in different applications such as transformers, cables, etc. Several review articles have been published to classify and categorize these works. Nonethe…
UHF RFID humidity sensor tag based on hygroscopic polymeric load
2012
Passive UHF RFID tags, beside item labelling, are also able to exploit capability of sensing the physical state of the tagged object as well as of the surrounding environment. Here a family of polymer-doped tags are proposed and fully characterized for the detection of ambient humidity. A sensitive chemical species based on PEDOT: PSS is used to dope a properly shaped slot carved into a folded-like patch tag. The sensing capabilities of the radio-sensor are investigated by means of measurements for different quantities of sensitive material and in cyclic exposures. The device could have interesting application in the assessment of the air quality in living and controlled rooms, in the monit…
Model-assisted ultrasonic calibration using intentionally embedded defects for in-process weld inspection
2021
Abstract Automated in-process Non-Destructive Testing (NDT) systems are rapidly gaining traction within the manufacturing industry as they reduce manufacturing time and costs. When considering calibration and verification of such systems, creating defects of known geometry and nature during the deposition of a weld can: (I) help examine the capability of the automated system to detect and characterise defects, (II) be used to form a database of signals associated with different defect types to train intelligent defect classification algorithms, and (III) act as a basis for in-process gain calibration during weld inspection at high temperatures, where the ultrasound beam can be skewed as a r…
Some tests of 3D ultrasonic traveltime tomography on the Eleonora d'Aragona statue (F. Laurana, 1468)
2013
Abstract The use of a non-destructive technique in situ can be a valuable diagnostic tool to support verification of restoration, as well as a monitoring technique in works of art or historical monuments. We present a high resolution 3D ultrasonic tomography to one of the most important statues of the Regional Gallery of Palazzo Abatellis of Palermo, the bust of Eleonora d'Aragona by F. Laurana (1430–1502). This technique allowed to study the structural continuity of the material of the marble. Some tests have been carried out to optimize inversion parameters, such as voxel size and to choose between straight and curved rays. We propose to calculate a minimum lateral resolution using the sa…
WhoSNext: Recommending Twitter Users to Follow Using a Spreading Activation Network Based Approach
2020
The huge number of modern social network users has made the web a fertile ground for the growth and development of a plethora of recommender systems. To date, recommending a new user profile X to a given user U that could be interested in creating a relationship with X has been tackled using techniques based on content analysis, existing friendship relationships and other pieces of information coming from different social networks or websites. In this paper we propose a recommending architecture - called WhoSNext (WSN) - tested on Twitter and which aim is promoting the creation of new relationships among users. As recent researches show, this is an interesting recommendation problem: for a …
Secure, dependable and publicly verifiable distributed data storage in unattended wireless sensor networks
2010
Published version of an article from the journal : Science in China, Series F: Information Sciences. The original publication is available at Spingerlink. http://dx.doi.org/10.1007/s11432-010-0096-7 In unattended wireless sensor networks (UWSNs), sensed data are stored locally or at designated nodes and further accessed by authorized collectors on demand. This paradigm is motivated by certain scenarios where historical or digest data (e.g., average temperature in a day), instead of real-time data, are of interest. The data are not instantly forwarded to a central sink upon sensing, thereby saving communication energy for transmission. Such a paradigm can also improve data survivability by m…
Accelerated Bayesian learning for decentralized two-armed bandit based decision making with applications to the Goore Game
2012
Published version of an article in the journal: Applied Intelligence. Also available from the publisher at: http://dx.doi.org/10.1007/s10489-012-0346-z The two-armed bandit problem is a classical optimization problem where a decision maker sequentially pulls one of two arms attached to a gambling machine, with each pull resulting in a random reward. The reward distributions are unknown, and thus, one must balance between exploiting existing knowledge about the arms, and obtaining new information. Bandit problems are particularly fascinating because a large class of real world problems, including routing, Quality of Service (QoS) control, game playing, and resource allocation, can be solved …