• Title/Summary/Keyword: Harmonic field

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Study on Generation of Harmonic Voltage using Synchronous Machine with d-axis and q-axis Harmonic Field Windings

  • Mukai, Eiichi;Kakinoki, Toshio;Yamaguchi, Hitoshi;Kimura, Yoshimasa;Fukai, Sumio
    • Journal of international Conference on Electrical Machines and Systems
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    • v.2 no.3
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    • pp.254-259
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    • 2013
  • We examined the generation of harmonic voltage by a synchronous machine adding d-axis and q-axis harmonic field windings in order to reduce the harmonics in a power line. We derived the expressions of the armature voltage in the case of supplying the currents with the frequency nf to the d-axis and q-axis harmonic field windings. We constructed the synchronous machine adding the harmonic windings. In this paper, the expressions and the experimental results on the generation of harmonic voltages by the synchronous machine are presented.

Microwave Incoherent Imaging of a Conducting Cylinder by Using Multi-Frequency Time-Harmonic Field : Part I - Incoherent Intensity Pattern by Using Multi-Frequency Time-Harmonic Field (다중주파수 시간좌화신호를 사용한 도체기중의 초고주파 incoherent 영상:Part I - 다중주파수 시간좌화신호를 사용한 incoherent 전력패턴)

  • 강진섭;라정웅
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.2
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    • pp.47-55
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    • 1996
  • A microwave incoherent imaging method for a conducting cyliner by using multi-frequency tiem-harmonic field is presented in this study. In this paper, an incoherent intensity pattern of th econducting cylinder is obtained by averagin gout the multi-frequency intensities of the coherent field such as the time-harmonic field scattered from this cylinder. This phenomenon is hsown numerically in scattering by a conducting circular cylinder illuminated by the time-harmonic plane wave, and is interpreted analytically by the mutual coherence functon defined as a frequency-averaged intensity of the time-harmonic fields in th frequency domain.

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Study on Generation of Harmonic Voltage using Synchronous Machine with d- and q-axis Harmonic Field Windings - Part 2

  • Mukai, Eiichi;Fukai, Sumio;Kakinoki, Toshio;Yamaguchi, Hitoshi;Kimura, Yoshimasa
    • Journal of international Conference on Electrical Machines and Systems
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    • v.3 no.2
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    • pp.132-138
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    • 2014
  • We investigated the harmonic voltages generated by a synchronous machine adding d-axis and q-axis harmonic field windings to reduce the harmonics in a power line. First, electronic circuits such as a frequency multiplier, band-pass filter, and phase shifter were newly designed and made to carry out the experiment. Next, an experimental circuit, for which an AC voltage of frequency 6f synchronized to the power line voltage of frequency f could be obtained, was constructed to examine the generation of harmonic voltage in more detail. Finally, an experiment involving the generation of harmonic voltage was performed using an experimental synchronous generator with harmonic windings in the d-axis and q-axis. In this paper, the power spectrum and the waveforms of the harmonic voltages in the armature winding are presented. Moreover, the values calculated from theoretical expressions of harmonic voltages in armature winding are compared with the values obtained by the experiment.

On the Property of Harmonic Vector Field on the Sphere S2n+1

  • Han, Dongsoong
    • Honam Mathematical Journal
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    • v.25 no.1
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    • pp.163-172
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    • 2003
  • In this paper we study the property of harmonic vector fields. We call a vector fields ${\xi}$ harmonic if it is a harmonic map from the manifold into its tangent bundle with the Sasaki metric. We show that the characteristic polynomial of operator $A={\nabla}{\xi}\;in\;S^{2n+1}\;is\;(x^2+1)^n$.

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TRANSVERSE HARMONIC FIELDS ON RIEMANNIAN MANIFOLDS

  • Pak, Jin-Suk;Yoo, Hwal-Lan
    • Bulletin of the Korean Mathematical Society
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    • v.29 no.1
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    • pp.73-80
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    • 1992
  • We discuss transverse harmonic fields on compact foliated Riemannian manifolds, and give a necessary and sufficient condition for a transverse field to be a transverse harmonic one and the non-existence of transverse harmonic fields. 1. On a foliated Riemannian manifold, geometric transverse fields, that is, transverse Killing, affine, projective, conformal fields were discussed by Kamber and Tondeur([3]), Molino ([5], [6]), Pak and Yorozu ([7]) and others. If the foliation is one by points, then transverse fields are usual fields on Riemannian manifolds. Thus it is natural to extend well known results concerning those fields on Riemannian manifolds to foliated cases. On the other hand, the following theorem is well known ([1], [10]): If the Ricci operator in a compact Riemannian manifold M is non-negative everywhere, then a harmonic vector field in M has a vanishing covariant derivative. If the Ricci operator in M is positive-definite, then a harmonic vector field other than zero does not exist in M.

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MINIMAL AND HARMONIC REEB VECTOR FIELDS ON TRANS-SASAKIAN 3-MANIFOLDS

  • Wang, Yaning
    • Journal of the Korean Mathematical Society
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    • v.55 no.6
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    • pp.1321-1336
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    • 2018
  • In this paper, we obtain some necessary and sufficient conditions for the Reeb vector field of a trans-Sasakian 3-manifold to be minimal or harmonic. We construct some examples to illustrate main results. As applications of the above results, we obtain some new characteristic conditions under which a compact trans-Sasakian 3-manifold is homothetic to either a Sasakian or cosymplectic 3-manifold.

An algorithm to infer the central location of a solenoid coil for the mapping process based on harmonic analysis (조화해석 기반의 맵핑을 위한 솔레노이드 코일의 중심위치 추론 알고리즘)

  • Lee, Woo-Seung;Ahn, Min-Cheol;Hahn, Seung-Yong;Ko, Tae-Kuk
    • Progress in Superconductivity and Cryogenics
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    • v.14 no.1
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    • pp.14-19
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    • 2012
  • Shimming, active and/or passive, is indispensable for most MR (magnetic resonance) magnets where homogeneous magnetic fields are required within target spaces. Generally, shimming consists of two steps, field mapping and correcting of fields, and they are recursively repeated until the target field homogeneity is reached. Thus, accuracy of the field mapping is crucial for fast and efficient shimming of MR magnets. For an accurate shimming, a "magnetic" center, which is a mathematical origin for harmonic analysis, must be carefully defined, Although the magnetic center is in general identical to the physical center of a magnet, it is not rare that both centers are different particularly in HTS (high temperature superconducting) magnets of which harmonic field errors, especially high orders, are significantly dependent on a location of the magnetic center. This paper presents a new algorithm, based on a field mapping theory with harmonic analysis, to define the best magnetic center of an MR magnet in terms of minimization of pre-shimming field errors. And the proposed algorithm is tested with simulation under gaussian noise environment.

3D Magic Wand: Interface for Mesh Segmentation Using Harmonic Field (3D Magic Wand: 하모닉 필드를 이용한 메쉬 분할 기법)

  • Moon, Ji-Hye;Park, Sanghun;Yoon, Seung-Hyun
    • Journal of the Korea Computer Graphics Society
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    • v.28 no.1
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    • pp.11-19
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    • 2022
  • In this paper we present a new method for interactive segmentation of a triangle mesh by using the concavity-sensitive harmonic field and anisotropic geodesic. The proposed method only requires a single vertex in a desired feature region, while most of existing methods need explicit information on segmentation boundary. From the user-clicked vertex, a candidate region which contains the desired feature region is defined and concavity-senstive harmonic field is constructed on the region by using appropriate boundary constraints. An initial isoline is chosen from the uniformly sampled isolines on the harmonic field and optimal points on the initial isoline are determined as interpolation points. Final segmentation boundary is then constructed by computing anisotropic geodesics passing through the interpolation points. In experimental results, we demonstrate the effectiveness of the proposed method by selecting several features in various 3D models.

On the Generalized of p-harmonic and f-harmonic Maps

  • Remli, Embarka;Cherif, Ahmed Mohammed
    • Kyungpook Mathematical Journal
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    • v.61 no.1
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    • pp.169-179
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    • 2021
  • In this paper, we extend the definition of p-harmonic maps between two Riemannian manifolds. We prove a Liouville type theorem for generalized p-harmonic maps. We present some new properties for the generalized stress p-energy tensor. We also prove that every generalized p-harmonic map from a complete Riemannian manifold into a Riemannian manifold admitting a homothetic vector field satisfying some condition is constant.

Distortion of Magnetic Field and Magnetic Force of a Brushless DC Motor due to Deformed Rubber Magnet (BLDC 모터의 고무 자석 형상 변형으로 인한 자계 변형 및 불평형 자기력 해석)

  • Lee, Chang-Jin;Jang, Gun-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.834-839
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    • 2007
  • This paper investigates the distortion of magnetic field of a brushless DC (BLDC) motor due to deformed rubber magnet. Global or local deformation of rubber magnet in the BLDC motor is mathematically modeled by using the Fourier series. Distorted magnetic field is calculated by using the finite element method, and unbalanced magnetic force are calculated by using the Maxwell stress tensor. The first harmonic deformation in the global deformation of rubber magnet generates the first harmonic driving frequency of the unbalanced magnetic force, and the rest harmonic deformations of rubber magnet except the harmonic deformation with multiple of common divisor of pole and slot introduces the driving frequencies with multiple of slot number ${\pm}1$ to the unbalanced magnetic force. However, the harmonic deformation with multiple of common divisor of pole and slot does not generate unbalanced magnetic force due to the rotational symmetry. When the rubber magnet is locally deformed, the unbalanced magnetic force has the first harmonic driving frequency and the driving frequencies with multiples of slot number ${\pm}1$.

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