• Title/Summary/Keyword: Parameter

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Catchment Responses in Time and Space to Parameter Uncertainty in Distributed Rainfall-Runoff Modeling (분포형 강우-유출 모형의 매개변수 불확실성에 대한 시.공간적 유역 응답)

  • Lee, Gi-Ha;Takara, Kaoru;Tachikawa, Yasuto;Sayama, Takahiro
    • Proceedings of the Korea Water Resources Association Conference
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    • 2009.05a
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    • pp.2215-2219
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    • 2009
  • For model calibration in rainfall-runoff modeling, streamflow data at a specific outlet is obviously required but is not sufficient to identify parameters of a model since numerous parameter combinations can result in very similar model performance measures (i.e. objective functions) and indistinguishable simulated hydrographs. This phenomenon has been called 'equifinality' due to inherent parameter uncertainty involved in rainfall-runoff modeling. This study aims to investigate catchment responses in time and space to various uncertain parameter sets in distributed rainfall-runoff modeling. Seven plausible (or behavioral) parameter sets, which guarantee identically-good model performances, were sampled using deterministic and stochastic optimization methods entitled SCE and SCEM, respectively. Then, we applied them to a computational tracer method linked with a distributed rainfall-runoff model in order to trace and visualize potential origins of streamflow at a catchment outlet. The results showed that all hydrograph simulations based on the plausible parameter sets were performed equally well while internal catchment responses to them showed totally different aspects; different parameter values led to different distributions with respect to the streamflow origins in space and time despite identical simulated hydrographs. Additional information provided by the computational tracer method may be utilized as a complementary constraint for filtering out non-physical parameter set(s) (or reducing parameter uncertainty) in distributed rainfall-runoff modeling.

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Evaluation of Multi-criteria Performances of the TOPMODEL Simulations in a Small Forest Catchment based on the Concept of Equifinality of the Multiple Parameter Sets

  • Choi, Hyung Tae;Kim, Kyongha;Jun, Jae-Hong;Yoo, Jae-Yun;Jeong, Yong-Ho
    • Journal of Korean Society of Forest Science
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    • v.95 no.5
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    • pp.569-579
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    • 2006
  • This study focuses on the application of multi-criteria performance measures based on the concept of equifinality to the calibration of the rainfall-runoff model TOPMODEL in a small deciduous forest catchment. The performance of each parameter set was evaluated by six performance measures, individually, and each set was identified as a behavioral or non-behavioral parameter set by a given behavioral acceptance threshold. Many behavioral parameter sets were scattered throughout the parameter space, and the range of model behavior and the sensitivity for each parameter varied considerably between the different performance measures. Sensitivity was very high in some parameters, and varied depending on the kind of performance measure as well. Compatibilities of behavioral parameter sets between different performance measures also varied, and very few parameter sets were selected to be used in making god predictions for all performance measures. Since different behavioral parameter sets with different likelihood weights were obtained for each performance measure, the decision on which performance measure to be used may be very important to achieve the goal of study. Therefore, one or more suitable performance measures should be selected depending on the environment and the goal of a study, and this may lead to decrease model uncertainty.

AMLEs for Rayleigh Distribution Based on Progressive Type-II Censored Data

  • Seo, Eun-Hyung;Kang, Suk-Bok
    • Communications for Statistical Applications and Methods
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    • v.14 no.2
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    • pp.329-344
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    • 2007
  • In this paper, we shall propose the AMLEs of the scale parameter and the location parameter in the two-parameter Rayleigh distribution based on progressive Type-II censored samples when one parameter is known. We also propose the AMLEs of the two parameters in the Rayleigh distribution based on progressive Type-II censored samples when two parameters are unknown. We simulate the mean squared errors of the proposed estimators through Monte Carlo simulation for various censoring schemes.

EXISTENCE OF OPTIMAL SOLUTION AND OPTIMALITY CONDITION FOR PARAMETER IDENTIFICATION OF AN ECOLOGICAL SPECIES SYSTEM

  • LI CHUNFA;FENG ENMIN
    • Journal of applied mathematics & informatics
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    • v.18 no.1_2
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    • pp.273-286
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    • 2005
  • Parameter identification problem of a three species (predator, mutualist-prey, and mutualist) ecological system with reaction-diffusion phenomenon is investigated in this paper. The mathematical model of the parameter identification problem is constructed and continuous dependence of the solution for the direct problem on the parameters identified is obtained. Finally, the existence of optimal solution and an optimality necessary condition for the parameter identification problem are given.

The Parameter Estimation of DC-DC Converter by System Identification Method (시스템 식별 기법을 이용한 DC-DC 컨버터 파라메터 추정)

  • Jeon, Jin-Hong;Kim, Tae-Jin;Kim, Kwang-Su;Kim, Kwang-Hwa
    • Proceedings of the KIEE Conference
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    • 2003.11c
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    • pp.503-506
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    • 2003
  • In this paper, we present the results of parameter estimation for do-dc converter model by system identification. The parameter estimation for dc-dc converter aims at the diagnosis of its operating status. we applied the system identification method for parameter estimation. For verification of estimated parameter, we compare bode plot of estimated system transfer function and measurement results of HP4194 instrument.

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Research for parameter estimation method by basis of Real vehicle data (실차 데이터 기반 차량 파라미터 추정을 위한 기법 연구)

  • Hong T.W.;Park K.;Heo S.J.;Park L.H.;Lee K.W.;Cho Y.J.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1091-1094
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    • 2005
  • This paper formulates the parameter estimation of cornering behavior of a vehicle. Especially some vehicle parameter is very important on stability control of chassis by ECU, but some parameter is so hard to get by sensor which parameter is included the nonlinear characteristic of tire cornering force. So we need to deduce that parameter from used signal and numerical method. In this study, we propose a estimation method and present the simulation by parameter estimation technique.

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Radative Effect on the Conjugate Mixed Convection-Conduction Heat Transfer along a Vertical Circular Cylindrical Fin (연직 원통윈에서의 혼합대류-전도 복합열전달에 미치는 복사효과)

  • 최상경;여문수;손병진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.5
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    • pp.1706-1716
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    • 1991
  • 본 연구에서는 혼합대류하는 연직원통휜 열전달에 미치는 복사효과에 Rossel- and 근사해법을 도입한 층류 경계층방정식과 휜 전도방정식을 동시에 해석하여 복사 -전도매개변수(radiation-conduction parameter) M, 대류-전도 매개변수(convectionc- onduction parameter) N$_{c}$, 부력매개변수(buoyancy force parameter) R$_{i}$ 그 리고 횡곡률 매개변수(transverse curvature parameter) .lambda.를 계산 파라미터로 하여 휜 최적설계의 기본이 되는 총열전단률, 무차원 국소등가열전달계수, 무차원 국소열플 럭스 및 휜온도분포를 계산할 수 있는 일반성있는 algorithm을 개발하고 휜 성능에 관 한 결과들을 제공함으로써, 좀 더 완전한 복사 열플럭스를 도입한, 다음 연구를 위한 범용의 기초자료를 얻는데 본 연구의 목적이 있다.

Effects of the Grinding Conditions on the Machining Elasticity Parameter

  • Kim, Kang
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.3
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    • pp.62-67
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    • 2003
  • The grinding force generated during the grinding process causes an elastic deformation of the workpiece, grinding wheel, and machine system. Thus, the true depth of cut is always smaller than the apparent depth of cut. This is known as machining elasticity phenomenon. The machining elasticity parameter is defined as a ratio between the true depth of cut and the apparent depth of cut. It is an important factor to understand the material removal mechanism of the grinding process. To increase productivity, the value of this machining elasticity parameter must be large. Therefore, it is essential to know the characteristics of this parameter. The objective of this research is to study the effect of the major grinding conditions, such as table speed, depth of cut, on this parameter experimentally, Through this research, it is found that this parameter value is increasing when the table speed is decreasing or the depth of cut is increasing. Also, this parameter value depends on the grinding mode (up grinding, down grinding).

ON THE EXISTENCE OF THE TWEEDIE POWER PARAMETER IMPLICIT ESTIMATOR

  • Ghribi, Abdelaziz;Hassin, Aymen;Masmoudi, Afif
    • Bulletin of the Korean Mathematical Society
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    • v.59 no.4
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    • pp.979-991
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    • 2022
  • A special class of exponential dispersion models is the class of Tweedie distributions. This class is very significant in statistical modeling as it includes a number of familiar distributions such as Gaussian, Gamma and compound Poisson. A Tweedie distribution has a power parameter p, a mean m and a dispersion parameter 𝜙. The value of the power parameter lies in identifying the corresponding distribution of the Tweedie family. The basic objective of this research work resides in investigating the existence of the implicit estimator of the power parameter of the Tweedie distribution. A necessary and sufficient condition on the mean parameter m, suggesting that the implicit estimator of the power parameter p exists, was established and we provided some asymptotic properties of this estimator.