• 제목/요약/키워드: nonlinear sequence

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OFDM통신 시스템의 PAPR저감을 위한 Dummy Sequence를 삽입하는 새로운 SLM 기법 (A New SLM Method using Dummy Sequence Insertion far the PAPR Reduction of the OFDM Communication System)

  • 이재은;허근재;김상우;유흥균
    • 한국전자파학회논문지
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    • 제15권4호
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    • pp.379-386
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    • 2004
  • OFDM(orthogonal frequency division multiplexing) 통신 방식은 무선 고속 데이터 전송에 적합한 방식이다. 하지만 높은 PAPR(peak-to-average power ratio)의 발생으로 HPA(high power amplifier)에서 비선형 왜곡된다. 따라서 본 논문에서는 이 문제점을 개선시키기 위한 PAPR 저감 방법으로 dummy sequence를 삽입하는 새로운 방식의 SLM 기법(dummy sequence insertion - selected mapping: DSI-SLM)을 제안한다. 이 DSI-SLM 기법은 각각의 브렌치에 서로 다른 위상 factor를 곱하는 대신 각각에 일정비율의 부반송파에 dummy 시퀀스를 삽입하여 IFFT 후 가장 낮은 PAPR을 갖는 브렌치의 데이터를 전송한다. 이 방식들에 사용된 dummy 시퀀스는 송신단의 PAPR 저감만을 위해 사용하며 위상 회전 부가 정보 전송 및 복원 과정이 필요치 않아 기존 SLM에 비해 계산량 및 복잡도를 감소시킬 수 있다. 또한 PTS 방식에서 최적의 rotation factor를 찾기 위한 peak value optimization에 의한 계산량 증가 및 송신기의 시간 지연 문제 등을 해결할 수 있다.

디젤 기관(機關)의 계통식별(系統識別) -연료주입율(燃料注入率) 대(對) 매연반응(煤煙反應)- (System Identification of a Diesel Engine -Throttle-Smoke Response-)

  • 조한근
    • Journal of Biosystems Engineering
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    • 제16권2호
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    • pp.111-117
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    • 1991
  • An empirical model for diesel engine control was obtained using a system identification method. A pseudo-random binary sequence was used as an input signal. Spectral anaylsis was used to find the frequency response of system. Model parameters of transfer functions were obtained using nonlinear regression.

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ROBUST TEST BASED ON NONLINEAR REGRESSION QUANTILE ESTIMATORS

  • CHOI, SEUNG-HOE;KIM, KYUNG-JOONG;LEE, MYUNG-SOOK
    • 대한수학회논문집
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    • 제20권1호
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    • pp.145-159
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    • 2005
  • In this paper we consider the problem of testing statistical hypotheses for unknown parameters in nonlinear regression models and propose three asymptotically equivalent tests based on regression quantiles estimators, which are Wald test, Lagrange Multiplier test and Likelihood Ratio test. We also derive the asymptotic distributions of the three test statistics both under the null hypotheses and under a sequence of local alternatives and verify that the asymptotic relative efficiency of the proposed test statistics with classical test based on least squares depends on the error distributions of the regression models. We give some examples to illustrate that the test based on the regression quantiles estimators performs better than the test based on the least squares estimators of the least absolute deviation estimators when the disturbance has asymmetric and heavy-tailed distribution.

A NEW PROJECTION ALGORITHM FOR SOLVING A SYSTEM OF NONLINEAR EQUATIONS WITH CONVEX CONSTRAINTS

  • Zheng, Lian
    • 대한수학회보
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    • 제50권3호
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    • pp.823-832
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    • 2013
  • We present a new algorithm for solving a system of nonlinear equations with convex constraints which combines proximal point and projection methodologies. Compared with the existing projection methods for solving the problem, we use a different system of linear equations to obtain the proximal point; and moreover, at the step of getting next iterate, our projection way and projection region are also different. Based on the Armijo-type line search procedure, a new hyperplane is introduced. Using the separate property of hyperplane, the new algorithm is proved to be globally convergent under much weaker assumptions than monotone or more generally pseudomonotone. We study the convergence rate of the iterative sequence under very mild error bound conditions.

CONVERGENCE AND STABILITY OF THREE-STEP ITERATIVE SCHEME WITH ERRORS FOR COMPLETELY GENERALIZED STRONGLY NONLINEAR QUASIVARIATIONAL INEQUALITIES

  • ZHANG FENGRONG;GAO HAIYAN;LIU ZEQING;KANG SHIN MIN
    • Journal of applied mathematics & informatics
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    • 제20권1_2호
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    • pp.465-478
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    • 2006
  • In this paper, we introduce a new class of completely generalized strongly nonlinear quasivariational inequalities and establish its equivalence with a class of fixed point problems by using the resolvent operator technique. Utilizing this equivalence, we develop a three-step iterative scheme with errors, obtain a few existence theorems of solutions for the completely generalized non-linear strongly quasivariational inequality involving relaxed monotone, relaxed Lipschitz, strongly monotone and generalized pseudocontractive mappings and prove some convergence and stability results of the sequence generated by the three-step iterative scheme with errors. Our results include several previously known results as special cases.

A Practical Method for Identification of Nonlinear Chemical Processes by use of Volterra Kernel Model

  • Numata, Motoki;Kashiwagi, Hiroshi;Harada, Hiroshi
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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    • pp.145-148
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    • 1999
  • It is known that Volterra kernel models can represent a wide variety of nonlinear chemical processes. Also, it is necessary for Volterra model identification to excite the process to be identified with a signal having wide range of frequency spectrum and high enough amplitude of input signals. Kashiwagi[4 ∼ 7] has recently shown a method for measuring Volterra kernels up to third order using pseudorandom M-sequence signals. However, in practice, since it is not always possible to apply such input sequences to the actual chemical plants. Even when we can apply such a pseudorandom signal to the process, it takes much time to obtain higher order Volterra kernels. Considering these problems, the authors propose here a new method for practical identification of Volterra kernels by use of approximate open differential equation (ODE) model and simple plant test. Simulation results are shown for verifying the usefulness of our method of identification of nonlinear chemical processes.

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ANALYSIS OF THE VLASOV-POISSON EQUATION BY USING A VISCOSITY TERM

  • Choi, Boo-Yong;Kang, Sun-Bu;Lee, Moon-Shik
    • 충청수학회지
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    • 제26권3호
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    • pp.501-516
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    • 2013
  • The well-known Vlasov-Poisson equation describes plasma physics as nonlinear first-order partial differential equations. Because of the nonlinear condition from the self consistency of the Vlasov-Poisson equation, many problems occur: the existence, the numerical solution, the convergence of the numerical solution, and so on. To solve the problems, a viscosity term (a second-order partial differential equation) is added. In a viscosity term, the Vlasov-Poisson equation changes into a parabolic equation like the Fokker-Planck equation. Therefore, the Schauder fixed point theorem and the classical results on parabolic equations can be used for analyzing the Vlasov-Poisson equation. The sequence and the convergence results are obtained from linearizing the Vlasove-Poisson equation by using a fixed point theorem and Gronwall's inequality. In numerical experiments, an implicit first-order scheme is used. The numerical results are tested using the changed viscosity terms.

SOLVING NONLINEAR ASSET LIABILITY MANAGEMENT PROBLEMS WITH A PRIMAL-DUAL INTERIOR POINT NONMONOTONE TRUST REGION METHOD

  • Gu, Nengzhu;Zhao, Yan
    • Journal of applied mathematics & informatics
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    • 제27권5_6호
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    • pp.981-1000
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    • 2009
  • This paper considers asset liability management problems when their deterministic equivalent formulations are general nonlinear optimization problems. The presented approach uses a nonmonotone trust region strategy for solving a sequence of unconstrained subproblems parameterized by a scalar parameter. The objective function of each unconstrained subproblem is an augmented penalty-barrier function that involves both primal and dual variables. Each subproblem is solved approximately. The algorithm does not restrict a monotonic decrease of the objective function value at each iteration. If a trial step is not accepted, the algorithm performs a non monotone line search to find a new acceptable point instead of resolving the subproblem. We prove that the algorithm globally converges to a point satisfying the second-order necessary optimality conditions.

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ON THE CONVERGENCE OF INEXACT TWO-STEP NEWTON-TYPE METHODS USING RECURRENT FUNCTIONS

  • Argyros, Ioannis K.;Hilou, Said
    • East Asian mathematical journal
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    • 제27권3호
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    • pp.319-337
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    • 2011
  • We approximate a locally unique solution of a nonlinear equation in a Banach space setting using an inexact two-step Newton-type method. It turn out that under our new idea of recurrent functions, our semilocal analysis provides tighter error bounds than before, and in many interesting cases, weaker sufficient convergence conditions. Applications including the solution of nonlinear Chandrasekhar-type integral equations appearing in radiative transfer and two point boundary value problems are also provided in this study.

Spatial and Statistical Properties of Electric Current Density in the Nonlinear Force-Free Model of Active Region 12158

  • 강지혜
    • 천문학회보
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    • 제41권1호
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    • pp.46.1-46.1
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    • 2016
  • The formation process of a current sheet is important for solar flare from a viewpoint of a space weather prediction. We therefore derive the temporal development of the spatial and statistical distribution of electric current density distributed in a flare-producing active region to describe the formation of a current sheet. We derive time sequence distribution of electric current density by applying a nonlinear force-free approximation reconstruction to Active Region 12158 that produces an X1.6-class flare. The time sequence maps of photospheric vector magnetic field used for reconstruction are captured by a Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamic Observatory (SDO) on 10th September, 2014. The spatial distribution of electric current density in NLFFF model well reproduce observed sigmoidal structure at the preflare phase, although a layer of high current density shrinks at the postflare phase. A double power-law profile of electric current density is found in statistical analysis. This may be expected to use an indicator of the occurrence of a solar flare.

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