Search results for "High frequency"
showing 10 items of 58 documents
Measurements on partial discharge in on‐site operating power transformer: a case study
2018
This study presents the case study of a substation in-service power transformer referred to the on-site partial discharge (PD) detection and evaluation methods. An original methodology for simultaneous application of three methods is proposed: electrical, acoustic and ultra-high frequency. Transformer is powered by the power grid and no external generator is required according to the proposed methodology. Furthermore, several possibilities of applying these concurrent measurements and benefits of such solution in terms of result interpretation, interference resistance and on-site measurement applicability are indicated. The proposed methodology allows for a fast, accurate and secure PD diag…
Local field potential activity dynamics in response to deep brain stimulation of the subthalamic nucleus in Parkinson's disease
2020
Abstract Local field potentials (LFPs) may afford insight into the mechanisms of action of deep brain stimulation (DBS) and potential feedback signals for adaptive DBS. In Parkinson's disease (PD) DBS of the subthalamic nucleus (STN) suppresses spontaneous activity in the beta band and drives evoked resonant neural activity (ERNA). Here, we investigate how STN LFP activities change over time following the onset and offset of DBS. To this end we recorded LFPs from the STN in 14 PD patients during long (mean: 181.2 s) and short (14.2 s) blocks of continuous stimulation at 130 Hz. LFP activities were evaluated in the temporal and spectral domains. During long stimulation blocks, the frequency …
Redox and autonomic responses to acute exercise-post recovery following Opuntia ficus-indica juice intake in physically active women
2021
Background: The aim of this study was to investigate if the supplementation with Opuntia ficus-indica (OFI) juice may affect plasma redox balance and heart rate variability (HRV) parameters following a maximal effort test, in young physically active women. Methods: A randomized, double blind, placebo controlled and crossover study comprising eight women (23.25 ± 2.95 years, 54.13 ± 9.05 kg, 157.75 ± 0.66 cm and BMI of 21.69 ± 0.66 kg/m2) was carried out. A juice containing OFI diluted in water and a Placebo solution were supplied (170 ml; OFI = 50 ml of OFI juice + 120 ml of water; Placebo = 170 ml beverage without Vitamin C and indicaxanthin). Participants consumed the OFI juice or Placebo…
389 HIGH-FREQUENCY STIMULATION-INDUCED LONG-TERM POTENTIATION (LTP) AND LOW-FREQUENCY STIMULATION-INDUCED DEPOTENTIATION (DE-LTP) OF PAIN PERCEPTION …
2010
Enhanced In Situ Availability of Aphanizomenon Flos-Aquae Constituents Entrapped in Buccal Films for the Treatment of Oxidative Stress-Related Oral D…
2019
In recent years, the key role of oxidative stress in pathogenesis of oral diseases has been emphasized and the use of antioxidant agents has been encouraged. Aphanizomenon flos-aquae (AFA) is a unicellular blue-green alga with antioxidant and anti-inflammatory properties. The aim of this study was the formulation and characterization of mucoadhesive thin layer films loaded with AFA, finalized to the treatment of oxidative stress (OS)-related oral diseases. First, to enhance the bioavailability of AFA constituents, the raw food grade material was appropriately treated by a high frequency homogenization able to disrupt cell walls. Thus, Eudragit®
Passive RFID Strain-Sensor Based on Meander-Line Antennas
2011
The processing of backscattered signals coming from RFID tags is potentially useful to detect the physical state of the tagged object. It is here shown how to design a completely passive UHF RFID sensor for strain monitoring starting from a flexible meander-line dipole whose shape factor and feed section are engineered to achieve the desired sensing resolution and dynamic range. This class of devices is low-cost, promises sub-millimeter resolution and may found interesting applications in the Structural Health Monitoring of damaged structures and vehicles as well as during extreme and adverse events.
High Frequency Model of PV Systems for the Evaluation of Ground Currents
2012
A high frequency model of a photovoltaic (PV) plant is developed and analysed to investigate the common mode (CM) currents circulating through the ground connections of the plant. The modelling method is based on the measurement of the impedance frequency response of photovoltaic module and on a high frequency representation of the power conversion unit. An overall lumped parameters circuit model is obtained and then implemented in PSpice. The CM leakage currents are evaluated by simulation.
Evaluation of ground currents in a PV system with high frequency modeling
2018
In this work a high frequency model of a photovoltaic (PV) plant is identified and implemented aiming to investigate the common mode (CM) currents circulating through the ground connections of the plant. From the identification of the impedance obtained by frequency response of photovoltaic module and by a suitable of the power conversion unit, an equivalent high frequency circuit representation has been developed. The lumped parameters circuit model is implemented in PSpice environment to obtain the CM leakage currents. Harmonics at frequencies multiple of the switching frequency and a strong resonance at about 12 MHz are detected.
Interchannel Interference and Mitigation in Distributed MIMO RF Sensing
2021
In this paper, we analyze and mitigate the cross-channel interference, which is found in multiple-input multiple-output (MIMO) radio frequency (RF) sensing systems. For a millimeter wave (mm-Wave) MIMO system, we present a geometrical three-dimensional (3D) channel model to simulate the time-variant (TV) trajectories of a moving scatterer. We collected RF data using a state-of-the-art radar known as Ancortek SDR-KIT 2400T2R4, which is a frequency-modulated continuous wave (FMCW) MIMO radar system operating in the K-band. The Ancortek radar is currently the only K-band MIMO commercial radar system that offers customized antenna configurations. It is shown that this radar system encounters th…
A Trajectory-Driven SIMO mm-Wave Channel Model for a Moving Point Scatterer
2021
In this paper, we propose a trajectory-based three-dimensional (3D) non-stationary channel model for a millimeter wave (mm-Wave) single-input multiple-output (SIMO) system. The proposed channel model is designed to capture the mobility of a moving point scatterer in an indoor environment. We derive the expression of the time-variant (TV) channel transfer function (CTF). We study the TV Doppler characteristics of the channel, such as the TV Doppler power spectrum and the TV mean Doppler shift. To validate the proposed channel model, we performed a measurement campaign in an indoor environment using a software defined radar operating at 24 GHz. As a moving object, we consider a single swingin…