Search results for " RAD"
showing 10 items of 7082 documents
“Magnifying glass” for difficult radiocephalic arteriovenous fistulas
2012
Background: Some uremic patients suffering from diabetes, atherosclerosis or simple by absent or exhausted peripheral vascular bed require bigger effort in creating arteriovenous fistula. Although it is possible to use prosthetic graft for difficult cases, the use of native vessels falls always in the respect of patient’s quality of life. A help for these cases comes from the use of a microsurgical technique for creating vascular access. Patient and Methods: For this study we evaluated the 72 patients underwent microsurgical radiocephalic fistula comparing them to a homogeneous group of 72 patients underwent traditional surgery. The patients were followed up at 1, 2 months and 1 year. Resul…
Micropropagazione di Convolvulus sabatius Viv.
2015
Il genere Convolvulus, appartenente alla famiglia delle Convolvulaceae, comprende circa 250 specie annuali e perenni, molte delle quali sono considerate infestanti. Tuttavia, alcune specie come C. tricolor, C. cneorum e C. sabatius vengono inserite nel settore delle piante ornamentali (Bird, 2004). Specie erbacea perenne, originaria del bacino del mediterraneo, C. sabatius è rinvenibile nella nostra penisola allo stato spontaneo in Liguria, Puglia e Sicilia (Pignatti, 2003). La specie, per il valore estetico dei numerosi fiori azzurro-violetti, il lungo periodo di fioritura (aprile-giugno) e la capacità di adattamento sia ad alte che a basse temperature (la pianta tollera temperature fino a…
Single Event Transients and Pulse Quenching Effects in Bandgap Reference Topologies for Space Applications
2016
An architectural performance comparison of bandgap voltage reference variants, designed in a $0.18~\mu \text {m}$ CMOS process, is performed with respect to single event transients. These are commonly induced in microelectronics in the space radiation environment. Heavy ion tests (Silicon, Krypton, Xenon) are used to explore the analog single-event transients and have revealed pulse quenching mechanisms in analogue circuits. The different topologies are compared, in terms of cross-section, pulse duration and pulse amplitude. The measured results, and the explanations behind the findings, reveal important guidelines for designing analog integrated circuits, which are intended for space appli…
Uusien 5G-teknologioiden energiatehokkuus
2016
Mobiiliverkkojen datamäärän kasvaessa räjähdysmäisesti tarvitaan uutta 5G-teknologiaa lisäämään langattomien verkkojen kapasiteettia. 5G-verkkoja kehitettäessä yksi tärkeä tutkimuskysymys on, kuinka saada niistä energiatehokkaita. Tässä tutkielmassa käydään läpi tieteellistä keskustelua aiheesta. Tieteellisestä keskustelusta keskeisimmiksi teknologioiksi 5G-verkkoihin nousevat muun muassa laitteistotekniikan kehittyminen, millimetriaallot, kognitiivinen radioverkko, massiivinen MIMO ja heterogeeninen verkko. Tarvitaan kuitenkin lisää tutkimusta ja kehitystyötä, jotta uusista 5G-verkoista saadaan riittävän energiatehokkaita. The amount of mobile data will grow radically and that's why we nee…
RADIOPROTECTION IN 2018: AN UPDATE
2018
Fluoroscopically-guided interventional procedures are performed in large numbers in Europe and in the United States. Radiation doses received by interventional radiologists can vary for the same type of procedure and for similar patient doses. Occupational radiation protection is a necessity whenever radiation is used in the practice of medicine. The International Commission on Radiological Protection is engaging against occupational radiation damages, publishing regular recommendations on dose limits. These limits are expressed as effective doses for the whole body and also as equivalent doses for particular regions or tissues of practitioners’ bodies. Shielding and personal protective clo…
Design and realization of a radon chamber as a secondary standard
2010
The air-radon mixture is the most significant source of natural radiation in workplaces and within dwellings. Despite some uncertainty in the risk estimates, it is widely believed that greater the exposure to radon, greater the risk of developing lung cancer. To assess the radiological hazard, accurate measurements of radon concentrations are necessary. A large variety of radon monitoring instruments have been developed in the last years, usually calibrated in radon chambers containing a known radon concentration released within the chamber by a specific solid radium-226 source. Radon calibration chamber has been constructed to test and calibrate radon and radon progeny detectors at various…
A Velocity Estimation Technique for a Monocular Camera Using mmWave FMCW Radars
2021
Perception in terms of object detection, classification, and dynamic estimation (position and velocity) are fundamental functionalities that autonomous agents (unmanned ground vehicles, unmanned aerial vehicles, or robots) have to navigate safely and autonomously. To date, various sensors have been used individually or in combination to achieve this goal. In this paper, we present a novel method for leveraging millimeter wave radar’s (mmW radar’s) ability to accurately measure position and velocity in order to improve and optimize velocity estimation using a monocular camera (using optical flow) and machine learning techniques. The proposed method eliminates ambiguity in optical flow veloci…
Localization of Multi-Class On-Road and Aerial Targets Using mmWave FMCW Radar
2021
mmWave radars play a vital role in autonomous systems, such as unmanned aerial vehicles (UAVs), unmanned surface vehicles (USVs), ground station control and monitoring systems. The challenging task when using mmWave radars is to estimate the accurate angle of arrival (AoA) of the targets, due to the limited number of receivers. In this paper, we present a novel AoA estimation technique, using mmWave FMCW radars operating in the frequency range 77–81 GHz by utilizing the mechanical rotation. Rotating the radar also increases the field of view in both azimuth and elevation. The proposed method estimates the AoA of the targets, using only a single transmitter and receiver. The measurements are…
Classification of Targets Using Statistical Features from Range FFT of mmWave FMCW Radars
2021
Radars with mmWave frequency modulated continuous wave (FMCW) technology accurately estimate the range and velocity of targets in their field of view (FoV). The targeted angle of arrival (AoA) estimation can be improved by increasing receiving antennas or by using multiple-input multiple-output (MIMO). However, obtaining target features such as target type remains challenging. In this paper, we present a novel target classification method based on machine learning and features extracted from a range fast Fourier transform (FFT) profile by using mmWave FMCW radars operating in the frequency range of 77–81 GHz. The measurements are carried out in a variety of realistic situations, including p…
An Exact Solution for the Level-Crossing Rate and the Average Duration of Fades of the Envelope of Sum-of-Cisoids Processes
2012
Authors version of an article published in the journal: Procedia Technology. Also available from the publisher at: http://dx.doi.org/10.1016/j.protcy.2012.03.004 Sum-of-cisoids (SOC) processes provide a physically and numerically appealing framework for the modelling and simulation of a wide class of mobile radio channels. This paper is concerned with the problem of finding a general solution for the level-crossing rate (LCR) and the average duration of fades (ADF) of the envelope of SOC processes. Exact expressions are derived for the LCR and the ADF by taking into account that the inphase component, the quadrature component, and the time derivatives of the inphase and quadrature component…