• 제목/요약/키워드: parameter evaluation simulation

검색결과 209건 처리시간 0.025초

Three Stage Estimation for the Mean of a One-Parameter Exponential Family

  • M. AlMahmeed;A. Al-Hessainan;Son, M.S.;H. I. Hamdy
    • Communications for Statistical Applications and Methods
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    • 제5권2호
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    • pp.539-557
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    • 1998
  • This article is concerned with the problem of estimating the mean of a one-parameter exponential family through sequential sampling in three stages under quadratic error loss. This more general framework differs from those considered by Hall (1981) and others. The differences are : (i) the estimator and the final stage sample size are dependent; and (ii) second order approximation of a continuously differentiable function of the final stage sample size permits evaluation of the asymptotic regret through higher order moments. In particular, the asymptotic regret can be expressed as a function of both the skewness $\rho$ and the kurtosis $\beta$ of the underlying distribution. The conditions on $\rho$ and $\beta$ for which negative regret is expected are discussed. Further results concerning the stopping variable N are also presented. We also supplement our theoretical findings wish simulation results to provide a feel for the triple sampling procedure presented in this study.

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탈선 안전성능 향상을 위한 매개변수에 관한 연구 (A study on the parameters to ensure safety against derailment)

  • 황정택;이희성;목진용
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2007년도 춘계학술대회논문집
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    • pp.297-303
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    • 2007
  • Derailment is likely to have a direct connection with human life and must be eliminated. A traveling safety evaluation method based mainly on derailment coefficient has already established. But this method is very difficult because Derailment is caused by multiple factors. To evaluate the derailment factor of running train that runs on the curved track, we make use of mechanism that wheel loads and lateral forces were affected by track and rolling stock parameter. In this paper, deal with a search on the parameter and derailment factor. According to results of computer simulation value of Q/P, running safety is connected with operation velocity, curve radius, cant, track irregularity, suspension stiffness and static wheel load ratio, SMRT train Line No. 5 Bogie is selected to do numerical study considering rolling stock and track condition.

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초내열합금의 대형마찰용접 공정해석 및 평가 (Evaluation and Process Analysis of the Superalloy Friction Welding for Large Shaft)

  • 정호승;김윤환;조종래;박희천;이낙규
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2004년도 추계학술대회논문집
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    • pp.301-304
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    • 2004
  • Friction welding was used to weld the turbine wheel and shaft and have a good welding quality. Friction welding was conducted an the two dissimilar material, Nimonic 80A and SNCrW. The control of friction welding process parameter such as flywheel energy, interface temperature, amount of upset have an effect on the mechanical properties of the welded joint. FE simulation can be a useful tool to optimize the weld geometry and process parameters. Flash shape and thickness weld is consistent with the simulated results. Process analysis was performed by the commercial code DEFORM 2D. Mechanical property of weld joints was evaluated by microstructure, chemical component, tensile, impact, hardness test so on.

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근역장 측정용 프로브의 설계 및 제작 (Probe Design and Fabrication for Measuring Near Field)

  • 김병찬;최형도;이애경;이형수
    • 한국전자파학회논문지
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    • 제13권2호
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    • pp.164-169
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    • 2002
  • 본 논문에서는 300~3000 MHz 의 주파수 영역에서 동작하는 근역장 측정 프로브를 설계하여 제작하였다. 설계 파라미터는 프로브에 대한 등가회로를 이용하여 추출하였으며 S파라미터를 이용한 수치해석을 통해 그 특성을 예측하였다. 제작된 프로브는 3.25 mm 길이의 다이폴 안테나와 제로 바이어스 쇼트키 다이오드, 고저항 전송 선으로 구성되어 있으며 TEM 셀을 이용하여 성능을 확인하였다.

곡선부 주행 중 타오름 탈선의 매개변수 연구 (A Parametric Studies to the Wheel Climb Derailment on the Curved track)

  • 목진용;이승일;이희성;황정택
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2006년도 추계학술대회 논문집
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    • pp.72-79
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    • 2006
  • Derailment is likely to have a direct connection with human life and must be eliminated. A traveling safety evaluation method based mainly on derailment coefficient has already established. But this method is very difficult because Derailment is caused by multiple factors. To evaluate the derailment factor of running train that runs on the curved track, we make use of mechanism that wheel loads and lateral forces were affected by track and rolling stock parameter. In this paper, deal with a search on the parameter and derailment factor. According to results of computer simulation value of Q/P, running safety is connected with operation velocity, curve radius, cant, track irregularity, suspension stiffness and static wheel load ratio, etc.

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적합한 조명시뮬레이션 사용을 위한 주광 시뮬레이션과 Mock-up 실험 비교에 관한 연구 (A Study on the Comparison of the Illuminance Values from Daylight Simulation and Mock-up Experiment for Suitable Application of Lighting Simulation)

  • 김유신;최안섭
    • 조명전기설비학회논문지
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    • 제24권1호
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    • pp.35-44
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    • 2010
  • 주광은 인공광원보다 심리적 안정과 심리적 신체적 건강 측면 등에서 질적으로 우세하며, 작업능률의 향상에 도움을 주는 것으로 알려져 있다. 또한 쾌적한 빛 환경에 대한 재실자들의 요구가 증가하고 있다. 그러나 주광의 양과 질이 항상 일정하지 않아 예측하기가 어렵기 때문에 이러한 주광의 유용성에도 불구하고 건축설계에 주광을 적극적으로 반영하는 경우가 드물다. 본 연구의 목적은 이러한 주광의 성능을 계량화하고 가시화 할 수 있는 다양한 조명시뮬레이션 소프트웨어(Lightscape 3.2, Relux 2007, Radiance 3.9)를 사용함으로 주광을 예측하고, 도출된 결과 값과 Mock-up 실험의 실측값을 비교 분석을 통하여 조명 시뮬레이션 소프트웨어 활용성을 극대화하는 것이다.

잡음에 강인한 음성 인식을 위한 환경 파라미터 보상에 관한 연구 (A Study on Environment Parameter Compensation Method for Robust Speech Recognition)

  • 홍미정;이호웅
    • 한국ITS학회 논문지
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    • 제5권2호
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    • pp.1-10
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    • 2006
  • 본 논문에서는 강인한 음성인식 기술의 하나인 모델 파라미터 변환 기법 중 Carnegie Mellon University(1996)에서 Moreno가 제안한 최신 VTS(Vector Taylor Series) 알고리즘을 이용하여 주어진 잡음 환경에서 실험하였다. 이러한 VTS 알고리즘의 성능평가를 위해서 기존의 잡음 처리 방법 중 CMN(Cepstral Mean Normalization) 기법을 도입하였으며, 데시벨별로 설정한 백색 잡음과 거리잡음을 환경잡음으로 주어졌을 때의 인식률을 비교하였다. 또한 기존 Moreno가 제안한 실험환경의 인식 결과와 본 논문에서의 실험결과를 비교 분석하였다. 인식 알고리즘으로는 실시간 구현이 가능한 이산HMM(Hidden Markov Model)을 사용하였다.

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Parametric identification of the Bouc-Wen model by a modified genetic algorithm: Application to evaluation of metallic dampers

  • Shu, Ganping;Li, Zongjing
    • Earthquakes and Structures
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    • 제13권4호
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    • pp.397-407
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    • 2017
  • With the growing demand for metallic dampers in engineering practice, it is urgent to establish a reasonable approach to evaluating the mechanical performance of metallic dampers under seismic excitations. This paper introduces an effective method for parameter identification of the modified Bouc-Wen model and its application to evaluating the fatigue performance of metallic dampers (MDs). The modified Bouc-Wen model which eliminates the redundant parameter is used to describe the hysteresis behavior of MDs. Relations between the parameters of the modified Bouc-Wen model and the mechanical performance parameters of MDs are studied first. A modified Genetic Algorithm using real-integer hybrid coding with relative fitness as well as adaptive crossover and mutation rates (called RFAGA) is then proposed to identify the parameters of the modified Bouc-Wen model. A reliable approach to evaluating the fatigue performance of the MDs with respect to the Chinese Code for Seismic Design of Buildings (GB 50011-2010) is finally proposed based on the research results. Experimental data are employed to demonstrate the process and verify the effectiveness of the proposed approach. It is shown that the RFAGA is able to converge quickly in the identification process, and the simulation curves based on the identification results fit well with the experimental hysteresis curves. Furthermore, the proposed approach is shown to be a useful tool for evaluating the fatigue performance of MDs with respect to the Chinese Code for Seismic Design of Buildings (GB 50011-2010).

Particle loading as a design parameter for composite radiation shielding

  • Baumann, N.;Diaz, K. Marquez;Simmons-Potter, K.;Potter, B.G. Jr.;Bucay, J.
    • Nuclear Engineering and Technology
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    • 제54권10호
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    • pp.3855-3863
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    • 2022
  • An evaluation of the radiation shielding performance of high-Z-particle-loaded polylactic acid (PLA) composite materials was pursued. Specimens were produced via fused deposition modeling (FDM) using copper-PLA, steel-PLA, and BaSO4-PLA composite filaments containing 82.7, 75.2, and 44.6 wt% particulate phase contents, respectively, and were tested under broad-band flash x-ray conditions at the Sandia National Laboratories HERMES III facility. The experimental results for the mass attenuation coefficients of the composites were found to be in good agreement with GEANT4 simulations carried out using the same exposure conditions and an atomistic mixture as a model for the composite materials. Further simulation studies, focusing on the Cu-PLA composite system, were used to explore a shield design parameter space (in this case, defined by Cu-particle loading and shield areal density) to assess performance under both high-energy photon and electron fluxes over an incident energy range of 0.5-15 MeV. Based on these results, a method is proposed that can assist in the visualization and isolation of shield parameter coordinate sets that optimize performance under targeted radiation characteristics (type, energy). For electron flux shielding, an empirical relationship was found between areal density (AD), electron energy (E), composition and performance. In cases where ${\frac{E}{AD}}{\geq}2MeV{\bullet}cm{\bullet}g^{-1}$, a shield composed of >85 wt% Cu results in optimal performance. In contrast, a shield composed of <10 wt% Cu is anticipated to perform best against electron irradiation when ${\frac{E}{AD}}<2MeV{\bullet}cm{\bullet}g^{-1}$.

복합 모드형 ER엔진마운트의 성능평가 (II) - HILL를 통한 성능 평가 - (Performance Evaluation of a Mixed-Mode Type ER Engine Mount(II)-Performance Evaluation Via HILS-)

  • 최영태;최승복
    • 대한기계학회논문집A
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    • 제24권9호
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    • pp.2151-2158
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    • 2000
  • This paper presents vibration control performance of a passenger vehicle installed with the mixed-mode type ER engine mounts. The performance is evaluated via hardware-in-the-loop-simulation(HILS) method. As a first step, a dynamic model of a vehicle featuring the ER engine mounts is formulated by taking into account the engine excitation forces. A new type of the fuzzy skyhook controller is then established in order to control both engine and body vibrations. This is accomplished by adopting a weighting parameter between two performance criteria which is to be determined from the fuzzy algorithm. Vertical displacement and acceleration of the engine mount obtained from the HILS method are provided in the frequency domain. In addition, vibration control performance between the conventional hydraulic engine mount and the proposed engine mount is compared in the time and frequency domains.