A multi-channel post-filtering algorithm using the proposed spatial coherence measure is derived. The spatial coherence measure evaluates the similarity between the measured signal fields using power spectral density matrices. In the proposed post-filter, the assumption of homogeneous sound fields is relaxed. Besides, multi-rank signal models can be easily adopted. Under this measure, the bias ...

Abstract: In modern power systems, high-precision power parameter measurement has occupied an important position for power quality in power grids. This paper presents a high-precision intelligent power parameter measurement device, which can collect parallel alternative current parameter values among 0 to 250 V in 3-channel easily and quickly, and improve the measurement accuracy by using the p...

High density (ne ≥ 4× 1018m−3) helium plasma is produced in a linear device for the development of a neutral helium-beam attenuating target. Radially peaked density profile accompanied by one order of density jump is observed for radio frequency input power higher than the threshold power. The threshold power varies with the external magnetic field. The results suggest that the density jump is ...

Wind power generation systems influence power quality in a specific way making important the need for detailed and accurate evaluation of disturbances caused by wind generators. Wind power system can cause suband interharmonic components to appear in the spectrum of voltages and currents. The paper shows different aspects of spectrum estimation in power systems, including the doubly fed inducti...

Material and methods. The research included 45 pig mandibles (n = 45). The specimens were randomly divided into 3 groups (n = 15) according to the laser irradiation mode and wavelength; G1 – 445 nm laser, power: 3 W, continuous wave (CW), distance: 2 mm, power density: 7460 W/cm2, fiber: 320 μm, noncontact mode; G2 – 445 nm laser (power: 2 W, CW, power density: 4970 W/cm2, fiber: 320 μm, contac...

The paper proposes an approach to investigate the fine structure of the voltages circulating in the industrial network within the range of 300 kHz-20 MHz, which serves to do some measurements of real lines in real operating mode. It is shown that the interferences can be divided into basic with spectral density changing slowly with frequency alteration and narrow-band (frequency-pulse). It is...

The input power requirements for accessing H-mode at low density and maintaining it during the density ramp in ITER is addressed by statistical means applied to the international H-mode threshold power database. Following the recent addition of new data, the improvement of existing data and the improvement of selection criteria, a revised scaling law that describes the threshold power required ...

The sleep EEGs of 9 young adult males (age 20-28 years) and 8 middle-aged males (42-56 years) were analyzed by visual scoring and spectral analysis. In the middle-aged subjects power density in the delta, theta and sigma frequencies were attenuated as compared to the young subjects. In both age groups power density in the delta and theta frequencies declined from NREM period 1 to 3. In the sigm...

The levels of maximum power density of GSM signals in the cities of Lagos, Ibadan and Abuja were studied. Measurements were made with a calibrated hand held spectrum analyzer 200m away from 271 base stations, at 1.2m to the ground level. The maximum GSM 900 signal power density was 139.63μW/m in Lagos, 162.49μW/m in Ibadan and 5411.26μW/m in Abuja. Also, the maximum GSM 1800 signal power densit...