• Title/Summary/Keyword: inverse approach

Search Result 458, Processing Time 0.024 seconds

AN ITERATIVE DISTRIBUTED SOURCE METHOD FOR THE DIVERGENCE OF SOURCE CURRENT IN EEG INVERSE PROBLEM

  • Choi, Jong-Ho;Lee, Chnag-Ock;Jung, Hyun-Kyo
    • Journal of the Korean Society for Industrial and Applied Mathematics
    • /
    • v.12 no.3
    • /
    • pp.191-199
    • /
    • 2008
  • This paper proposes a new method for the inverse problem of the three-dimensional reconstruction of the electrical activity of the brain from electroencephalography (EEG). Compared to conventional direct methods using additional parameters, the proposed approach solves the EEG inverse problem iteratively without any parameter. We describe the Lagrangian corresponding to the minimization problem and suggest the numerical inverse algorithm. The restriction of influence space and the lead field matrix reduce the computational cost in this approach. The reconstructed divergence of primary current converges to a reasonable distribution for three dimensional sphere head model.

  • PDF

A Study on Design Approach of Inverse Cam Mechanism (Inverse Cam Mechanism 설계에 관한 연구)

  • 김도현;신중호;김종수;김상진
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2002.10a
    • /
    • pp.916-919
    • /
    • 2002
  • Cam mechanism is one of the common devices used in lots of automatic machinery. This paper introduces to an inverse cam mechanism. The inverse cam mechanism has a reverse structure as compared with common cam mechanism. For shape design of the inverse cam the approach used in this paper is an instant velocity center method that find the contact point between cam and roller at any contact time. And a computer program is developed for shape design and simulation by visual $C^{++}$ language. As the results, this paper presents two examples for the shape design of the inverse cam mechanism in order to prove the accuracy of the design procedures.

  • PDF

Nonlinear Forecasting of Daily Runoff Using Inverse Approach Method (가역접근법을 이용한 일유출량 자료의 비선형 예측)

  • Lee, Bae-Sung;Jeong, Dong-Kug;Jung, Tae-Sung;Lee, Sang-Jin
    • Journal of Korea Water Resources Association
    • /
    • v.39 no.3 s.164
    • /
    • pp.253-259
    • /
    • 2006
  • In almost all previous hydrological studies, the standard approach adopted for nonlinear time series analysis is to perform system characterization first followed by forecasting. However, a practical inverse approach for forecasting nonlinear hydrological time series was proposed recently To investigate the applicability standard approach method and inverse approach, this study used a theoretical time series (Mackey-Glass time series) and daily streamflows of the Bear River in Idaho. To predict a theoretical time series and daily streamflow, this study used local approximation method. From chaos analysis, chaotic characteristics are found in daily streamflow of the Bear River in Idaho. Resulting from 1, 3 and 5-day prediction, inverse approach method is shown to be better than the standard approach for a theoretical chaotic time series and daily streamflow.

A comparison of inverse transform and composition methods of data simulation from the Lindley distribution

  • Okwuokenye, Macaulay;Peace, Karl E.
    • Communications for Statistical Applications and Methods
    • /
    • v.23 no.6
    • /
    • pp.517-529
    • /
    • 2016
  • This study compares the inverse transform and the composition methods for generating data from the Lindley distribution. The expression for the inverse of the distribution function for the Lindley distribution does not exist in closed form. Hence, authors of many empirical studies on the Lindley distribution used methods for generating Lindley variates other than the inverse transform. We generated data from the Lindley distribution using the inverse transform approach by obtaining the Lindley variates numerically; we also generated data from this distribution using the composition approach. Following the generation of the Lindley variates using these two methods, we compare some statistical properties of the estimates of the Lindley model parameters based on the generated data. We conclude that the two methods produce similar results.

Iterative projection of sliced inverse regression with fused approach

  • Han, Hyoseon;Cho, Youyoung;Yoo, Jae Keun
    • Communications for Statistical Applications and Methods
    • /
    • v.28 no.2
    • /
    • pp.205-215
    • /
    • 2021
  • Sufficient dimension reduction is useful dimension reduction tool in regression, and sliced inverse regression (Li, 1991) is one of the most popular sufficient dimension reduction methodologies. In spite of its popularity, it is known to be sensitive to the number of slices. To overcome this shortcoming, the so-called fused sliced inverse regression is proposed by Cook and Zhang (2014). Unfortunately, the two existing methods do not have the direction application to large p-small n regression, in which the dimension reduction is desperately needed. In this paper, we newly propose seeded sliced inverse regression and seeded fused sliced inverse regression to overcome this deficit by adopting iterative projection approach (Cook et al., 2007). Numerical studies are presented to study their asymptotic estimation behaviors, and real data analysis confirms their practical usefulness in high-dimensional data analysis.

Design of Inverse Optimal TS Fuzzy Controllers (역최적 TS 퍼지 제어기의 설계)

  • 임채환;곽기호;박주영
    • Proceedings of the Korean Institute of Intelligent Systems Conference
    • /
    • 2001.12a
    • /
    • pp.137-140
    • /
    • 2001
  • In this paper, we design 75(Takagi-Sugeno) fuzzy controllers for the systems that can be represented by the 75 fuzzy model. We use inverse optimal approach in which the cost function is determined later than the Lyapunov function and its corresponding control input satisfying the design requirements such as stability and decay rate. The obtained design procedure is in the form of solving LMI(Linear Matrix Inequalities), thus very efficient in practice.

  • PDF

Self-Tuning Pole-Placement Control Of Robotic Manipulators With An Inverse Modela (로보트 매니퓰레이터의 역모델을 갖는 자기동조 극배치 제어)

  • 이은옥;양해원
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1988.10a
    • /
    • pp.50-53
    • /
    • 1988
  • This paper presents an approach to the position control of a robot manipulator by using a self-tuning pole-placement controller with an inverse model. The linearized independent difference equations of manipulator motion are obtained, and the parameters of these models are estimated on line. The controller is composed of two parts, the primary controller obtains desired torques by using an inverse model and the secondary controller computes variational torques on the basis of induced perturbation equations by minimizing a quadratic criterion with a closed-loop pole-placement. Simulation is performed to demonstrate the effectiveness of this approach.

  • PDF

Kinematic/Inverse Kinematic Analysis of Captive Trajectory Simulation System with Functional Redundancy (기능적 여유자유도를 가지는 CTS 시스템의 기구학/역기구학 해석)

  • Lee, Do Kwan;Lee, Sang Jeong
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.26 no.3
    • /
    • pp.263-271
    • /
    • 2017
  • A captive trajectory simulation (CTS) system is used to investigate the separation behavior of the store model by moving the model to an arbitrary pose and position based on aerodynamic data. A CTS system operated inside a wind tunnel is designed to match the structure of the wind tunnel facility. As a result, each CTS system has different kinematic structure, and inverse kinematic analysis of the system is necessary. In this study, kinematic/inverse kinematic analysis for the CTS system with functional redundancy is performed. Inverse kinematic analysis with combined numerical and analytical approach is especially proposed. The suggested approach utilizes the redundancy to improve the safety of the system, and has advantages in real time analysis.

Nonlinearity Compensation in the Secondary Path of Active Noise Control Systems Using An Inverse Adaptive Volterra Filtering (역 적응 볼테라 필터링을 이용한 능동 소음 제어 시스템의 2차 경로 비선형 특성 적응 보상)

  • Jeong I.S.;Lee I.H.;Nam S.W.
    • The Transactions of the Korean Institute of Electrical Engineers D
    • /
    • v.53 no.12
    • /
    • pp.827-833
    • /
    • 2004
  • In active noise control (ANC) systems, the error-reduction performance of the conventional Filtered-X Least Mean Square (FXLMS) algorithm may be affected by nonlinear distortions in the secondary path such as in the power amplifiers, loudspeakers and transducers. In this paper, a nonlinear FXLMS algorithm with high error-reduction performance is proposed to compensate for undesirable nonlinearities in the secondary-path of ANC systems by employing the inverse Volterra filtering approach. In particular, the proposed approach is based on the utilization of the conventional P-th order inverse approach to nonlinearity compensation in the secondary path of ANC systems. Finally, the simulation results showed that the proposed approach yields a better nonlinearity compensation performance for the ANC systems with a nonlinear secondary path than the conventional FXLMS.

Analysis of Nested Case-Control Study Designs: Revisiting the Inverse Probability Weighting Method

  • Kim, Ryung S.
    • Communications for Statistical Applications and Methods
    • /
    • v.20 no.6
    • /
    • pp.455-466
    • /
    • 2013
  • In nested case-control studies, the most common way to make inference under a proportional hazards model is the conditional logistic approach of Thomas (1977). Inclusion probability methods are more efficient than the conditional logistic approach of Thomas; however, the epidemiology research community has not accepted the methods as a replacement of the Thomas' method. This paper promotes the inverse probability weighting method originally proposed by Samuelsen (1997) in combination with an approximate jackknife standard error that can be easily computed using existing software. Simulation studies demonstrate that this approach yields valid type 1 errors and greater powers than the conditional logistic approach in nested case-control designs across various sample sizes and magnitudes of the hazard ratios. A generalization of the method is also made to incorporate additional matching and the stratified Cox model. The proposed method is illustrated with data from a cohort of children with Wilm's tumor to study the association between histological signatures and relapses.