Harmonics

Geomagnetic induced currents are generated on the power system by solar storms and solar flare, which causes damages to power transformer. GIC (DC) current when enter the power grid through the neutral point of transformer causes saturation of the transformer and the transformer gets damaged hence a novel hardware model was fabricated and the effects were analyzed. A software simulation was done using MATLAB and the effects on power transformer were observed to be increase in reactive power consumption and fluctuating harmonics in neutral current and the excitations current. Were analyzed which has got significance in the practical field to give warnings before the occurrence of the damage to the transformer and the subsequent interruption of power supply.

Abstract Harmonic terminations effects in microwave power amplifiers on its power and linearity performances are discussed. By a simplified theoretical approach, useful guidelines are inferred to obtain both high efficiency and low intermodulation. The concepts ...

Automatic knowledge extraction from music signals is a key component for most music organization and music information retrieval systems. In this paper, we consider the problem of instrument modelling and instrument classification from the rough audio data. Existing systems for automatic instrument classification operate normally on a relatively large number of features, from which those related to the spectrum of

In this paper, a novel joint carrier and sampling frequency offset estimation scheme for multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra wideband (UWB) system is introduced. We investigate the relationship between carrier and sampling frequency offset when they have a common error source and derive the joint estimation scheme. The proposed scheme consists of two stages. In the first stage, a robust estimation of the frequency offset is carried out using preamble symbols. In the second stage, pilot subcarriers within OFDM symbols is used to track the phase distortion caused by the presence of estimation error, if any, in the first stage. Extensive simulation is carried out and the results show that when coupled with the appropriate compensation algorithms, the proposed scheme is effective in limiting the MB-OFDM system performance degradation due to frequency offset to within 0.5 dB.

This paper deals with the possible adverse harmonic conditions associated with the connection of shunt compensating capacitors to certain network buses. It takes into account both the daily profile of the voltage background harmonics and the frequency dependence of the network's input impedance at these buses. These two factors will be incorporated in four established standards and recommendations used for assessing the severity of the harmonic pollution in the network. The presented approach is applied to a case study with available measurements for the variation of the different voltage harmonics during the day and a given impedance frequency spectrum. The results of several parameter studies are presented and discussed.

Using conventional broadcasting, if we want to support a 120-minute popular movie every 10 minutes, we need 12 video channels. Assuming the set-top box at the client end can buffer portions of the playing video on a disk, pyramid broadcasting schemes can reduce the bandwidth requirements to 5.7 channels. We present a new scheme which only needs 3.2 channels. For a movie with length D minutes, if we want to reduce the viewer waiting time to D/N minutes, we only need to allocate H(N) video channels to broadcast the movie periodically, where H(N) is the harmonic number of N, H(N)=1+1/2+…+1/N. In order to support video-on-demand service for a popular movie, the new scheme greatly reduces the bandwidth requirements

Abstract—The use of power electronic circuits in a wide range of applications has resulted in distorted current waveforms in the power system. This results in nonsinusoidal voltage drops across the transformers and transmission line impedances, resulting in a nonsinusoidal ...

The harmonic content of the short circuit current during single-phase to earth fault is discussed in networks with compensated neutrals. Different methods to decrease the harmonics in the fault current are compared based on computer simulations.

A filosofia antiga da música grega desenvolveu-se em conexão com a matemática e a acústica desde o pitagorismo, que, por sua vez, desenrolou-se em um contexto ritualístico, mágico e simbólico. O modelo de harmonia universal da ciência pitagórica fez com que ela se expandisse em muitas direções, da astronomia à medicina. A obra de Platão reelaborou parte do pensamento musical pitagórico e examinou também a influência da música no ethos humano, tema aprofundado por Aristóteles.  O surgimento da abordagem aristoxeniana provocou uma reorganização do campo da investigação musical, criando um domínio específico da música.

"En este trabajo se emplearon pulsos láser ultracortos (110 fs, 1 kHz; hasta1.1 mJ/pulso) para el micro-perforado de acero. El procesado con estos pulsos permitió obtener agujeros circulares, con medidas precisas y sin alteración mecánica ni química apreciable de las zonas adyacentes. Los agujeros se realizaron utilizando el sistema de trepanado óptico (Helical Drilling Optics,HDO) de la empresa TGSW-Stuttgart, el cual permitió generar estructuras no sólo de gran profundidad sino además de diámetro variable, gracias a que se pudo variar hasta tres parámetros de proceso simultáneamente (velocidad de rotación del haz, inclinación y descentrado del haz respecto del eje óptico)mientras se ejecutaba el procesado. En el presente trabajo se estudió principalmente la influencia de la longitud de onda del láser, en la geometría de las micro-perforaciones. Para ello se realizó la micro-perforación con pulsos láser con la longitud de onda fundamental (λ= 790nm) y la del segundo armónico(λ= 395nm), se utilizó un conjunto específico de elementos ópticos para la HDO en cada caso y se compararon los resultados obtenidos lo cual arrojó que no hay ventajas notables al usar el segundo armónico. Se mencionan deficiencias en el dispositivo experimental que impidieron evaluar la influencia de la longitud de onda con total precisión"

Poco ci è noto riguardo al canto bizantino di epoca giustinianea e nessuno ha ancora letto il trattato del De Musica di Boezio come una fonte circa il canto bizantino. In che modo e quanto l'autore aveva conosciuto della cultura musicale dell'Oriente? Quanto essa fu importante quale fonte d'ispirazione, nel tempo in cui aveva tradotto i trattati greci della scienza matematica “armoniche”? Osservando le tradizioni liturgiche latine, ma anche la teoria musicale in Europa fino a oggi, la questione sarà dunque quanto le scelte di Boezio avevano condizionato il “futuro” sapere della teoria musicale.