• Title, Summary, Keyword: Homogeneous Model

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The Likelihood for a Two-Dimensional Poisson Exceedance Point Process Model

  • Yun, Seok-Hoon
    • Communications for Statistical Applications and Methods
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    • v.15 no.5
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    • pp.793-798
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    • 2008
  • Extreme value inference deals with fitting the generalized extreme value distribution model and the generalized Pareto distribution model, which are recently combined to give a single model, namely a two-dimensional non-homogeneous Poisson exceedance point process model. In this paper, we extend the two-dimensional non-homogeneous Poisson process model to include non-stationary effect or dependence on covariates and then derive the likelihood for the extended model.

Prediction of Emissions and Knocking in a Homogeneous GDI Engine by Quasidimensional model (유사차원해석을 이용한 균일혼합기 GDI 엔진에서의 배기 및 노킹 예측)

  • Lee, Jaeseo;Huh, Kang Y.
    • 한국연소학회:학술대회논문집
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    • pp.107-109
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    • 2012
  • A quasidimensional model is developed with the surrogate mechanism of isooctane and n-heptane to predict knock and emissions of a homogeneous GDI engine. It is composed of unburned and burned zone with the latter divided into multiple zones of equal mass to resolve temperature stratification. Validation is performed against measured pressure traces, NOx and CO emissions at different load and rpm conditions. Comparison is made between the empirical knock model and predictions by the chemistry model in this work.

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The prediction of the critical factor of safety of homogeneous finite slopes subjected to earthquake forces using neural networks and multiple regressions

  • Erzin, Yusuf;Cetin, T.
    • Geomechanics and Engineering
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    • v.6 no.1
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    • pp.1-15
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    • 2014
  • In this study, artificial neural network (ANN) and multiple regression (MR) models were developed to predict the critical factor of safety ($F_s$) of the homogeneous finite slopes subjected to earthquake forces. To achieve this, the values of $F_s$ in 5184 nos. of homogeneous finite slopes having different slope, soil and earthquake parameters were calculated by using the Simplified Bishop method and the minimum (critical) $F_s$ for each of the case was determined and used in the development of the ANN and MR models. The results obtained from both the models were compared with those obtained from the calculations. It is found that the ANN model exhibits more reliable predictions than the MR model. Moreover, several performance indices such as the determination coefficient, variance account for, mean absolute error, root mean square error, and the scaled percent error were computed. Also, the receiver operating curves were drawn, and the areas under the curves (AUC) were calculated to assess the prediction capacity of the ANN and MR models developed. The performance level attained in the ANN model shows that the ANN model developed can be used for predicting the critical $F_s$ of the homogeneous finite slopes subjected to earthquake forces.

Volume Haptic Rendering Algorithm for Realistic Modeling (실감형 모델링을 위한 볼륨 햅틱 렌더링 알고리즘)

  • Jung, Ji-Chan;Park, Joon-Young
    • Korean Journal of Computational Design and Engineering
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    • v.15 no.2
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    • pp.136-143
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    • 2010
  • Realistic Modeling is to maximize the reality of the environment in which perception is made by virtual environment or remote control using two or more senses of human. Especially, the field of haptic rendering, which provides reality through interaction of visual and tactual sense in realistic model, has brought attention. Haptic rendering calculates the force caused by model deformation during interaction with a virtual model and returns it to the user. Deformable model in the haptic rendering has more complexity than a rigid body because the deformation is calculated inside as well as the outside the model. For this model, Gibson suggested the 3D ChainMail algorithm using volumetric data. However, in case of the deformable model with non-homogeneous materials, there were some discordances between visual and tactual sense information when calculating the force-feedback in real time. Therefore, we propose an algorithm for the Volume Haptic Rendering of non-homogeneous deformable object that reflects the force-feedback consistently in real time, depending on visual information (the amount of deformation), without any post-processing.

Study of viscoelastic model for harmonic waves in non-homogeneous viscoelastic filaments

  • Kakar, Rajneesh;Kaur, Kanwaljeet;Gupta, Kishan Chand
    • Interaction and multiscale mechanics
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    • v.6 no.1
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    • pp.31-50
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    • 2013
  • A five parameter viscoelastic model is developed to study harmonic waves propagating in the non-homogeneous viscoelastic filaments of varying density. The constitutive relation for five parameter model is first developed and then it is applied for harmonic waves in the specimen. In this study, it is assumed that density, rigidity and viscosity of the specimen i.e., rod are space dependent. The specimen is non-homogeneous, initially unstressed and at rest. The method of non-linear partial differential equation has been used for finding the dispersion equation of harmonic waves in the rods. A simple method is presented for reflections at the free end of the finite non-homogeneous viscoelastic rods. The harmonic wave propagation in viscoelastic rod is also presented numerically with MATLAB.

Quasidimensional Simulation with Multi-zone Combustion Model for Homogeneous GDI Engine Emissions and Knocking (균일혼합기 가솔린 직분사 엔진의 다중 영역 유사차원 해석을 통한 배기 및 노킹 예측)

  • Lee, Jaeseo;Huh, Kang Y.;Kwon, Hyuckmo;Park, Jae In
    • Journal of the Korean Society of Combustion
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    • v.18 no.1
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    • pp.7-12
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    • 2013
  • A quasidimensional program is developed for a four stroke cycle homogeneous GDI (Gasoline Direct Injection) engine. It includes models for spray, burning rate and chemistry to predict knock and emissions. With early injection a homogeneous GDI engine goes through spark ignited, turbulent premixed combustion as in PFI (Port Fuel Injection) engines. The cylinder charge is divided into unburned and burned zone with the latter divided into multiple zones of equal mass to resolve temperature stratification. Validation is performed against measured pressure traces, NOx and CO emissions at different load and RPM conditions. Comparison is made between an empirical knock model and predictions by the chemistry model in this work.

Effect of Compression Ratio on the Combustion Characteristics of a Thermodynamics-Based Homogeneous Charge Compression Ignition Engine

  • Han, Sung Bin
    • Journal of Energy Engineering
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    • v.24 no.3
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    • pp.61-66
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    • 2015
  • Homogeneous charge compression ignition (HCCI) engine combines the combustion characteristics of a compression ignition engine and a spark ignition engine. HCCI engines take advantage of the high compression ratio and heat release rate and thus exhibit high efficiency found in compression ignition engines. In modern research, simulation has be come a powerful tool as it saves time and also economical when compared to experimental study. Engine simulation has been developed to predict the performance of a homogeneous charge compression ignition engine. The effects of compression ratio, cylinder pressure, rate of pressure rise, flame temperature, rate of heat release, and mass fraction burned were simulated. The simulation and analysis show several meaningful results. The objective of the present study is to develop a combustion characteristics model for a homogeneous charge compression ignition engine running with isooctane as a fuel and effect of compression ratio.

HOMOGENEOUS SUBMERSIONS OF 3-DIMENSIONAL GEOMETRIES

  • Lee, Kyung-Bai;Park, Joon-Sang
    • Bulletin of the Korean Mathematical Society
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    • v.49 no.5
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    • pp.1101-1129
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    • 2012
  • We study the geometry of the images of 1-dimensional homogeneous submersions for each of the model spaces X of the eight 3-dimensional geometries. In particular, We shall calculate the group of isometries and the curvatures of the base surfaces for each of the model spaces of 3-dimensional geometries, with respect to every closed subgroup of the isometries of X acting freely.

Nonlinear Analysis for the Prediction of Lateral Behavior of Single Piles in Non-homogeneous Sandy Soil (비균질 사질토 지반에서 단일말뚝의 수평거동 예측을 위한 비선형 해석기법)

  • 김영수;김병탁;허노영
    • Journal of the Korean Geotechnical Society
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    • v.16 no.4
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    • pp.5-16
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    • 2000
  • THe purpose of this paper is to suggest the analytical method which can predict lateral nonlinear behavior in non-homogeneous soil using the coefficient of soil resistance and ultimate soil resistance. Those parameters are obtained through back analysis on the base of the results of a series of model tests.Analytical method of Chang is more or less difficult to predict nonlinear behavior in non-homogeneous sol. So, in this study, for the prediction of nonlinear behavior the compositive analytical method which apply the p - y curve to Chang model is suggested. Also, the program is developed to predict nonlinear behavior using the compositive analytical method and it can be used to calculated the deflection, bending moment and soil reaction with DFM in non-homogeneous soil. To establish applicability of the suggested analytical method, the results of model tests and field tests and Pentagon2D finite element program are compared with those of the compositive analytical method. In the analysis values of the coefficient of soil reaction and ultimate soil resistance are also applied to the case of non-homogeneous soil. Lateral defection calculated using the compositive analytical method has been found to be in good agreement with values measured in field and model load tests.

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Two model comparisons of software reliability analysis for Burr type XII distribution

  • An, Jeong-Hyang
    • Journal of the Korean Data and Information Science Society
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    • v.23 no.4
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    • pp.815-823
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    • 2012
  • In this paper reliability growth model in which the operating time between successive failure is a continuous random variable is proposed. This model is for Burr type XII distribution with two parameters which is discussed in two versions: the order statistics and non-homogeneous Poisson process. The two software reliability measures are obtained. The performance for two versions of the suggested model is tested on real data set by U-plot and Y-plot using Kolmogorov distance.