• Title, Summary, Keyword: space harmonic analysis

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Analysis of Torque Characteristics for the Single-phase Induction Motor Considering Space Harmonics

  • Kim Byung-Taek;Lee Sung-Ho;Kwon Byung-Il
    • Journal of Electrical Engineering and Technology
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    • v.1 no.3
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    • pp.327-331
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    • 2006
  • This paper presents the analysis method for the torque characteristic of the 1-phase induction motor considering space harmonics in the air gap. The equivalent circuit method is used, where the circuit constants are obtained by classic theory. In addition, the space harmonic components in air gap magneto motive force are analyzed and added to the equivalent circuit to obtain accurate torque characteristics in low speed regions. Each torque component due to the harmonics is calculated and the total torque characteristic is obtained and compared with the measurement result.

Harmonic-Mean-Based Dual-Antenna Selection with Distributed Concatenated Alamouti Codes in Two-Way Relaying Networks

  • Li, Guo;Gong, Feng-Kui;Chen, Xiang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.4
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    • pp.1961-1974
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    • 2019
  • In this letter, a harmonic-mean-based dual-antenna selection scheme at relay node is proposed in two-way relaying networks (TWRNs). With well-designed distributed orthogonal concatenated Alamouti space-time block code (STBC), a dual-antenna selection problem based on the instantaneous achievable sum-rate criterion is formulated. We propose a low-complexity selection algorithm based on the harmonic-mean criterion with linearly complexity $O(N_R)$ rather than the directly exhaustive search with complexity $O(N^2_R)$. From the analysis of network outage performance, we show that the asymptotic diversity gain function of the proposed scheme achieves as $1/{\rho}{^{N_R-1}}$, which demonstrates one degree loss of diversity order compared with the full diversity. This slight performance gap is mainly caused by sacrificing some dual-antenna selection freedom to reduce the algorithm complexity. In addition, our proposed scheme can obtain an extra coding gain because of the combination of the well-designed orthogonal concatenated Alamouti STBC and the corresponding dual-antenna selection algorithm. Compared with the common-used selection algorithms in the state of the art, the proposed scheme can achieve the best performance, which is validated by numerical simulations.

Eliminating the Third Harmonic Effect for Six Phase Permanent Magnet Synchronous Generators in One Phase Open Mode

  • Liu, Jian;Yang, Gui-Jie;Li, Yong;Gao, Hong-Wei;Su, Jian-Yong
    • Journal of Power Electronics
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    • v.14 no.1
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    • pp.92-104
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    • 2014
  • To insure stable operation and eliminate twice torque ripple, a topology for a six phase permanent magnet synchronous generator (SP-PMSG) with a neutral point connected together was analyzed in this paper. By adopting an extended transformation matrix, the mathematic model of the space vector control was established. The voltage and torque equations were deduced while considering the third harmonic flux and inductance. In addition, the suppression third harmonic method and the closed loop control strategy were proposed. A comparison analysis indicates that the cooper loss minimum method and the current magnitude minimum method can meet different application requirements. The voltage compensation amount for each of the methods was deduced which also takes into account the third harmonic effect. A simulation and experimental result comparison validates the consistency through theoretical derivation. It can be seen that all of the two control strategies can meet the requirements of post-fault.

Identification of two common types of forest cover, Pinus densiflora(Pd) and Querqus mongolica(Qm), using the 1st harmonics of a Discrete Fourier Transform

  • Cha, Su-Young;Pi, Ung-Hwan;Yi, Jong-Hyuk;Park, Chong-Hwa
    • Korean Journal of Remote Sensing
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    • v.27 no.3
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    • pp.329-338
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    • 2011
  • The time-series normalized difference vegetation index (NDVI) product has proven to be a powerful tool to investigate the phenological information because it can monitor the change of the forests with very high time-resolution, This study described the application of the DFT analysis over the 9 year MODIS data for the identification of the two types of vegetation cover, Pinus densiflora(Pd) and Querqus mongolica(Qm) which are dominant species of evergreen and broadleaved deciduous forest, respectively, The total number of samples was 5148 reference cycles which consist of 2160 Pd and 2988 Qm. They were extracted from the pixel-based MODIS scenes over the 9 years from 2000 to 2008 of South Korea. The DFT analysis was mainly focused on the 0th and $1^{st}$ harmonic components, each of which represents the mean value and the variation amplitude of the NDVI over the years, respectively. The $0^{th}$ harmonic values of the vegetation Pd and Qm averaged over the 9 years were 0.74 and 0.65, respectively. This implies that Pd has a higher NDVI than Qm. Similarly obtained $1^{st}$ harmonic values of Pd and Qm were 0.19 and 0.27, respectively. This can be intuitively understood considering that the seasonal variation of Qm is much larger than Pd. This distinctive difference of the $1^{st}$ harmonic value has been used to identify evergreen and deciduous forests. Overall agreement between the Fourier analysis-based map and the actal vegetation map has been estimated to be as high as 75%. This study found that the DFT analysis can be a concise and repeatable method to separate and trace the changes of evergreen and deciduous forest using the annual NDVI cycles.

Improved Efficiency Design and Analysis of Single-Sided Linear Induction Motors (편측식 직선형 유도전동기의 효율 향상을 위한 설계 및 특성 해석)

  • Jang, Seok-Myeong;Kwon, Jeong-Ki;Cho, Han-Wook;You, Dae-Joon
    • Proceedings of the KIEE Conference
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    • pp.9-11
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    • 2004
  • In this paper, a new design method to improve efficiency of single-sided linear induction motor(SLIM) is presented. The method utilizes the space harmonic analysis, the equivalent circuit analysis and numerical analysis method. This paper deals with calculation of the design dimension of primary and secondary and the equivalent circuit parameters for SLIM. Finally, analytical results for SLIM designed are verified by FE results.

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A Study on the Harmonic Oscillation of a Physical Pendulum by Using the Internet of Things (사물인터넷을 활용한 물리진자의 조화운동 연구)

  • Kim, Se-Hun
    • New Physics: Sae Mulli
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    • v.68 no.10
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    • pp.1151-1156
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    • 2018
  • We studied scientific experiments by using the Internet of things in the 4th industrial revolution. The experiments on simple harmonic motion were performed with a physical pendulum composed of a metallic ruler and a smartphone. The periodic motion of the physical pendulum was analyzed by using the distance between the axis of rotation and the center of mass of the rigid body. A software app of a smartphone can convert an analog signal to 3D digital acceleration data. The transmitted acceleration data can then be fitted by using a regression analysis. In particular, the phase space and the quality factor of a physical pendulum combined with a smartphone were calculated.

LCL Filter Design Method for Grid-Connected PWM-VSC

  • Majic, Goran;Despalatovic, Marin;Terzic, Bozo
    • Journal of Electrical Engineering and Technology
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    • v.12 no.5
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    • pp.1945-1954
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    • 2017
  • In recent years, several LCL filter design methods for different converter topologies have been published, many of which use analytical expressions to calculate the ideal converter AC voltage harmonic spectrum. This paper presents the LCL filter design methodology but the focus is on presentation and validation of the non-iterative filter design method for a grid-connected three-phase two-level PWM-VSC. The developed method can be adapted for different converter topologies and PWM algorithms. Furthermore, as a starting point for the design procedure, only the range of PWM carrier frequencies is required instead of an exact value. System nonlinearities, usually omitted from analysis have a significant influence on VSC AC voltage harmonic spectrum. In order to achieve better accuracy of the proposed procedure, the system nonlinear model is incorporated into the method. Optimal filter parameters are determined using the novel cost function based on higher frequency losses of the filter. An example of LCL filter design for a 40 kVA grid-connected PWM-VSC has been presented. Obtained results have been used to construct the corresponding laboratory setup and measurements have been performed to verify the proposed method.

Harmonic differential quadrature (HDQ) for axisymmetric bending analysis of thin isotropic circular plates

  • Civalek, Omer;Ulker, Mehmet
    • Structural Engineering and Mechanics
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    • v.17 no.1
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    • pp.1-14
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    • 2004
  • Numerical solution to linear bending analysis of circular plates is obtained by the method of harmonic differential quadrature (HDQ). In the method of differential quadrature (DQ), partial space derivatives of a function appearing in a differential equation are approximated by means of a polynomial expressed as the weighted linear sum of the function values at a preselected grid of discrete points. The method of HDQ that was used in the paper proposes a very simple algebraic formula to determine the weighting coefficients required by differential quadrature approximation without restricting the choice of mesh grids. Applying this concept to the governing differential equation of circular plate gives a set of linear simultaneous equations. Bending moments, stresses values in radial and tangential directions and vertical deflections are found for two different types of load. In the present study, the axisymmetric bending behavior is considered. Both the clamped and the simply supported edges are considered as boundary conditions. The obtained results are compared with existing solutions available from analytical and other numerical results such as finite elements and finite differences methods. A comparison between the HDQ results and the finite difference solutions for one example plate problem is also made. The method presented gives accurate results and is computationally efficient.

Analysis of Harmonic Mean Distance Calculation in Global Illumination Algorithms (전역 조명 알고리즘에서의 조화 평균 거리 계산의 분석)

  • Cha, Deuk-Hyun;Ihm, In-Sung
    • Journal of KIISE:Computing Practices and Letters
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    • v.16 no.2
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    • pp.186-200
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    • 2010
  • In order to render global illumination realistically, we need to accurately compute the direct and indirect illumination that represents the light information incoming through complex light paths. In this process, the indirect illumination at given point is greatly affected by surrounding geometries. Harmonic mean distance is a mathematical tool which is often used as a metric indicating the distance from a surface point to its visible objects in 3D space, and plays a key role in such advanced global illumination algorithms as irradiance/radiance caching and ambient occlusion. In this paper, we analyze the accuracy of harmonic mean distance estimated against various environments in the final gathering and photon mapping methods. Based on the experimental results, we discuss our experiences and future directions that may help develop an effective harmonic mean distance computation method in the future.

ABSTRACT RELATIVE FOURIER TRANSFORMS OVER CANONICAL HOMOGENEOUS SPACES OF SEMI-DIRECT PRODUCT GROUPS WITH ABELIAN NORMAL FACTOR

  • Farashahi, Arash Ghaani
    • Journal of the Korean Mathematical Society
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    • v.54 no.1
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    • pp.117-139
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    • 2017
  • This paper presents a systematic study for theoretical aspects of a unified approach to the abstract relative Fourier transforms over canonical homogeneous spaces of semi-direct product groups with Abelian normal factor. Let H be a locally compact group, K be a locally compact Abelian (LCA) group, and ${\theta}:H{\rightarrow}Aut(K)$ be a continuous homomorphism. Let $G_{\theta}=H{\ltimes}_{\theta}K$ be the semi-direct product of H and K with respect to ${\theta}$ and $G_{\theta}/H$ be the canonical homogeneous space (left coset space) of $G_{\theta}$. We introduce the notions of relative dual homogeneous space and also abstract relative Fourier transform over $G_{\theta}/H$. Then we study theoretical properties of this approach.