نتایج جستجو برای: harmonic

تعداد نتایج: 47514  

Abstract. In this paper we define and verify a subclass of harmonic univalent functions involving the argument of complex-value functions of the form f = h + ¯g and investigate some properties of this subclass e.g. necessary and sufficient coefficient bounds, extreme points, distortion bounds and Hadamard product.Abstract. In this paper we define and verify a subclass of harmonic univalent func...

Journal: :the modares journal of electrical engineering 2011
ali enshaee rahmatolah hooshmand

detection & classification of power quality (pq) disturbances are the most important problems in distribution systems. in this paper, a new approach for the detection and classification of single and combined pq disturbances is proposed which utilizes fuzzy logic and particle swarm optimization (pso) algorithms. in this approach, first suitable features of the waveform of pq disturbances ar...

Abdipour, Mirzavand, Mohammadi, Sedghi, Shayegh,

A direct conversion modulator-demodulator with even harmonic mixers with emphasis on noise analysis is presented. The circuits consist of even harmonic mixers (EHMs) realized with antiparallel diode pairs (APDPs). We evaluate the different levels of I/Q imbalances and DC offsets and use signal space concepts to analyze the bit error rate (BER) of the proposed transceiver using M-ary QAM schemes...

2007
Joe Pater

Loss of restrictiveness through arithmetic: Concern is well-founded here. As we have shown, however, recourse to the full-blown power of numerical optimization is not required. . . In Optimality Theory, constraints are ranked, not weighted: harmonic evaluation involves the abstract algebra of order relations rather than numerical adjudication between quantities. ∗This research would not have be...

An exact study on temperature field in a hollow cylinder of finite length which is influenced by a surrounding with harmonic boundary condition is presented. To simulate an idealized situation, it is supposed that the cylinder is homogeneous and isotropic with physical properties independent of temperature and time. Here we impose a harmonic boundary condition on the external surface of the fin...

This paper proposes an improved control method based on modified Delta-Sigma Modulator (DSM) to enhance transient response and improve harmonic contents of buck DC-DC converter. The main advantages of the proposed method are improving the output voltage frequency spectrum, correction of the output voltage harmonic contents and sideband harmonics, reduction of switching noise peaks at the output...

K. Mohammadi, S. H. Hosseini,

Nowadays with increasing use of numerous nonlinear loads, voltage and current harmonics in power systems are one of the most important problems power engineers encounter. Many of these nonlinear loads, because of their dynamic natures, inject time-varying harmonics into power system. Common techniques applied for harmonics measurement and assessment such as FFT have significant errors in presen...

ژورنال: ژئوفیزیک ایران 2018

Surface nuclear magnetic resonance (surface-NMR) method is a well-known tool for determining the water-bearing layers and subsurface resistivity structure. Harmonic interference is an inevitable interference in surface-NMR measurements. Accurate estimation of harmonic interference parameters (i.e., fundamental frequency, phase and amplitude) leads to better retrieval of power-line harmonics and...

Flashover of polluted insulators in contaminated areas is one of the most important factors influencing the operation of transmission and distribution lines and finally line outages. Therefore, it is essential to prevent and detect flashover in the insulators. Hence, utilizing the insulator status monitoring systems and predicting their functions have absorbed a lot of attention over the recent...

2013
Jen-Hao Teng Rong-Ceng Leou

The harmonic impact caused by wind turbines should be carefully investigated before wind turbines are interconnected. However, the harmonic currents of wind turbines are not easily predicted due to the variations of wind speed. If the harmonic current outputs can be predicted accurately, the harmonic impact of wind turbines and wind farms for power grids can be analyzed efficiently. Therefore, ...

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