• Title/Summary/Keyword: nonzero power

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INSERTION PROPERTY OF NONZERO POWERS AT ZERO PRODUCTS

  • Kim, Dong Hwa
    • Communications of the Korean Mathematical Society
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    • v.33 no.2
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    • pp.371-378
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    • 2018
  • This article concerns a ring property which is seated between IFP and IPFP rings. We study the insertion property of nonzero powers at zero products, introducing the concept of strongly IPFP ring. The structure of strongly IPFP rings is investigated in relation with nearly seated ring properties and ring extensions.

Structure of System Matrix of one Machine System with Controllers (저차모델계통의 계통행렬의 구조)

  • 권세혁
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.39 no.11
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    • pp.1146-1152
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    • 1990
  • Direct calculation algorithm for the nonzero elements of system matrix is suggested for a single machine connected to the infinite bus. Excitation system and power system stabilizer are included. When the system matrix is partitioned into 15 nonzero blocks, we can identify the location of nonzero elements and formula for each element. No matrix inversion and multiplication are necessary. Sensitivity coefficients with respect to controller parameters are suggested based on the structure of system matrix.

Clock Scheduling and Cell Library Information Utilization for Power Supply Noise Reduction

  • Kim, Yoo-Seong;Han, Sang-Woo;Kim, Ju-Ho
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.9 no.1
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    • pp.29-36
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    • 2009
  • Power supply noise is fundamentally caused by large current peaks. Since large current peaks are induced by simultaneous switching of many circuit elements, power supply noise can be minimized by deliberate clock scheduling which utilizes nonzero clock skew. In this paper, nonzero skew clock scheduling is used to avoid the large peak current and consequently reduce power supply noise. While previous approaches require extra characterization efforts to acquire current waveform of a circuit, we approximate it only with existing cell library information to be easily adapted to conventional design flow. A simulated annealing based algorithm is performed, and the peak current values are estimated for feasible clock schedules found by the algorithm. The clock schedule with the minimum peak current is selected for a solution. Experimental results on ISCAS89 benchmark circuits show that the proposed method can effectively reduce the peak current.

Model Predictive Power Control of a PWM Rectifier for Electromagnetic Transmitters

  • Zhang, Jialin;Zhang, Yiming;Guo, Bing;Gao, Junxia
    • Journal of Power Electronics
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    • v.18 no.3
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    • pp.789-801
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    • 2018
  • Model predictive direct power control (MPDPC) is a widely recognized high-performance control strategy for a three-phase grid-connected pulse width modulation (PWM) rectifier. Unlike those of conventional grid-connected PWM rectifiers, the active and reactive powers of permanent magnet synchronous generator (PMSG)-connected PWM rectifiers, which are used in electromagnetic transmitters, cannot be calculated as the product of voltage and current because the back electromotive force (EMF) of the generator cannot be measured directly. In this study, the predictive power model of the rectifier is obtained by analyzing the relationship among flux, back EMF, active/reactive power, converter voltage, and stator current of the generator. The concept of duty cycle control in the proposed MPDPC is introduced by allocating a fraction of the control period for a nonzero vector and rest time for a zero vector. When nonzero vectors and their duration in the predefined cost function are simultaneously evaluated, the global power ripple minimization is obtained. Simulation and experimental results prove that the proposed MPDPC strategy with duty cycle control for the PMSG-connected PWM rectifier can achieve better control performance than the conventional MPDPC-SVM with grid-connected PWM rectifier.

A GENERALIZATION OF LOCAL SYMMETRIC AND SKEW-SYMMETRIC SPLITTING ITERATION METHODS FOR GENERALIZED SADDLE POINT PROBLEMS

  • Li, Jian-Lei;Luo, Dang;Zhang, Zhi-Jiang
    • Journal of applied mathematics & informatics
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    • v.29 no.5_6
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    • pp.1167-1178
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    • 2011
  • In this paper, we further investigate the local Hermitian and skew-Hermitian splitting (LHSS) iteration method and the modified LHSS (MLHSS) iteration method for solving generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. When A is non-symmetric positive definite, the convergence conditions are obtained, which generalize some results of Jiang and Cao [M.-Q. Jiang and Y. Cao, On local Hermitian and Skew-Hermitian splitting iteration methods for generalized saddle point problems, J. Comput. Appl. Math., 2009(231): 973-982] for the generalized saddle point problems to generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. Numerical experiments show the effectiveness of the iterative methods.

Analysis of Large Power System by Small Digital Computer (소형 digital computer를 이용한 대전력계통의 해석)

  • 박영문;정재길
    • 전기의세계
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    • v.23 no.1
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    • pp.61-68
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    • 1974
  • This paper attempts to develop the algorithms and computer program for load flow solution and faults analysis of large power system by small digital computer. The Conventional methods for load flow solution and fault analysis of large power system require too much amount of computer memory space and computing time. Therefore, this paper describes the methad for reducing the computer memory space and computing time as follows. (1) Load Flow Solution; This method is to store each primitive impedance of lines along with a list of bus numbers corresponding to the both terminals of lines, and to store only nonzero element of bus admittance matrix. (2) Faults Analysis: This method is to partition a large power system into several groups of subsystems, form individual bus impedance matrix, store them in the storage, and assemble the only required portion of them to original total system by algorithm.

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Application of the cooperative two-person nonzero-sum game for water resources development in the Tumen river basin (두만강 유역의 합리적인 수자원 개발방안 도출을 위한 2인 비영합 협력게임 적용)

  • Park, Wan-Soo;Lee, Sang-Eun;Park, Hee-Kyung
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.1
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    • pp.63-72
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    • 2010
  • This study aims to make a decision about the rational option for a multipurpose dams development of the Tumen river basin so that the adjoining countries will effectively deal with the chronic problems and fully satisfy the fast growing demand of water and power. It has been thus far investigated that the interests between North Korea and China closely depend on the selected option, and they are not well compatible with each other. These situations are defined in terms of the cooperative two-person nonzero-sum game. The Nash bargaining model is then applied to contemplate the rational option, considering two scenarios of economic growth of the North Korea. After analyzing the model, it was expected that 1) two multipurpose dams must be cooperatively developed, and 2) their benefits should be allocated according to demand of each country. The authors finally suggest that a cooperative organisation be established to effectively manage the dams beyond the border of the countries.

REDUCED PROPERTY OVER IDEMPOTENTS

  • Kwak, Tai Keun;Lee, Yang;Seo, Young Joo
    • Korean Journal of Mathematics
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    • v.29 no.3
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    • pp.483-492
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    • 2021
  • This article concerns the property that for any element a in a ring, if a2n = an for some n ≥ 2 then a2 = a. The class of rings with this property is large, but there also exist many kinds of rings without that, for example, rings of characteristic ≠2 and finite fields of characteristic ≥ 3. Rings with such a property is called reduced-over-idempotent. The study of reduced-over-idempotent rings is based on the fact that the characteristic is 2 and every nonzero non-identity element generates an infinite multiplicative semigroup without identity. It is proved that the reduced-over-idempotent property pass to polynomial rings, and we provide power series rings with a partial affirmative argument. It is also proved that every finitely generated subring of a locally finite reduced-over-idempotent ring is isomorphic to a finite direct product of copies of the prime field {0, 1}. A method to construct reduced-over-idempotent fields is also provided.

Theoretical Investigation on Collinear Phase Matching Stimulated Polariton Scattering Generating THz Waves with a KTP Crystal

  • Tan, Lian;Yuan, Bin;Li, Yongjun;Wang, Silei;Zhang, Hongtao;Bing, Pibin;Yao, Jianquan;Li, Zhongyang
    • Current Optics and Photonics
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    • v.3 no.4
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    • pp.342-349
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    • 2019
  • We present a theoretical research concerning terahertz (THz) wave generation with $KTiOPO_4$ (KTP) by collinear phase matching (CPM) stimulated polariton scattering (SPS). Both CPM and corresponding nonzero nonlinear coefficients can be simultaneously realized with $s{\rightarrow}f+f$ in yz plane, $s{\rightarrow}f+s$ with ${\theta}$ < ${\Omega}$ in xz plane and $s{\rightarrow}f+f$ with ${\theta}$ < ${\Omega}$ in xz plane. The effective nonlinear coefficients including electronic nonlinearities and ionic nonlinearities are calculated. Based on the parameter values of refractive indices, absorption coefficients and effective nonlinear coefficients, we simulate THz wave intensities generated with CPM SPS by solving coupled wave equations and give the relationship among the maximum THz wave intensity, optimal crystal length and the angle ${\theta}$. The calculation results demonstrate that CPM SPS with KTP can generate THz waves with high intensities and quantum conversion efficiencies.

Technique of Common Mode Voltage and Conducted EMI Reduction using Nonzero-vector State in SVPWM Method (SVPWM방식에서의 영벡터 제거에 의한 커먼모드 전압 및 전도성 EMI 저감 기법)

  • Hahm Nyon-Kun;Kim Lee-Hun;Jeon Kee-Young;Chun Kwang-Su;Won Chung-Yuen;Han Kyung-Hee
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.5
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    • pp.507-515
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    • 2004
  • With the advent of fast power devices, the high dv/dt voltage produced by PWM inverts have been found to cause EMI noise, shaft voltage and bearing current. This paper describes the application of newly developed Conducted EMI reduction SVPWM technique in induction motor drives. The newly developed common mode voltage reduction SVPWM technique don't use any zero-vector states for inverter control, hence it can restrict the common mode voltage more than conventional PWM technique. The validity of the proposed technique by software approach is verified through simulation and experimental results.