• Title/Summary/Keyword: Gaussian

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An Adaptive Noise Detection and Modified Gaussian Noise Removal Using Local Statistics for Impulse Noise Image (국부 통계 특성을 이용한 임펄스 노이즈 영상의 적응적 노이즈 검출 및 변형된 형태의 Gaussian 노이즈 제거 기법)

  • Nguyen, Tuan-Anh;Song, Won-Seon;Hong, Min-Cheol
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2009.11a
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    • pp.179-181
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    • 2009
  • In this paper, we propose an adaptive noise detection and modified Gaussian removal algorithm using local statistics for impulse noise. In order to determine constraints for noise detection, the local mean, variance, and maximum values are used. In addition, a modified Gaussian filter that integrates the tuning parameter to remove the detected noises. Experimental results show that our method is significantly better than a number of existing techniques in terms of image restoration and noise detection.

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Determination of Degraded Fiber Properties of Laminated CFRP Flat Plates Using the Bivariate Gaussian Distribution Function (이변량 Gaussian 분포함수를 적용한 CFRP 적층 평판의 보강섬유 물성저하 규명)

  • Kim, Gyu-Dong;Lee, Sang-Youl
    • Composites Research
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    • v.29 no.5
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    • pp.299-305
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    • 2016
  • This paper presents a method to detect the fiber property variation of laminated CFRP plates using the bivariate Gaussian distribution function. Five unknown parameters are considered to determine the fiber damage distribution, which is a modified form of the bivariate Gaussian distribution function. To solve the inverse problem using the combined computational method, this study uses several natural frequencies and mode shapes in a structure as the measured data. The numerical examples show that the proposed technique is a feasible and practical method which can prove the location of a damaged region as well as inspect the distribution of deteriorated stiffness of CFRP plates for different fiber angles and layup sequences.

Non-Gaussian wind features over complex terrain under atmospheric turbulent boundary layers: A case study

  • Hongtao, Shen;Weicheng, Hu;Qingshan, Yang;Fucheng, Yang;Kunpeng, Guo;Tong, Zhou;Guowei, Qian;Qinggen, Xu;Ziting, Yuan
    • Wind and Structures
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    • v.35 no.6
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    • pp.419-430
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    • 2022
  • In wind-resistant designs, wind velocity is assumed to be a Gaussian process; however, local complex topography may result in strong non-Gaussian wind features. This study investigates the non-Gaussian wind features over complex terrain under atmospheric turbulent boundary layers by the large eddy simulation (LES) model, and the turbulent inlet of LES is generated by the consistent discretizing random flow generation (CDRFG) method. The performance of LES is validated by two different complex terrains in Changsha and Mianyang, China, and the results are compared with wind tunnel tests and onsite measurements, respectively. Furthermore, the non-Gaussian parameters, such as skewness, kurtosis, probability curves, and gust factors, are analyzed in-depth. The results show that the LES method is in good agreement with both mean and turbulent wind fields from wind tunnel tests and onsite measurements. Wind fields in complex terrain mostly exhibit a left-skewed Gaussian process, and it changes from a softening Gaussian process to a hardening Gaussian process as the height increases. A reduction in the gust factors of about 2.0%-15.0% can be found by taking into account the non-Gaussian features, except for a 4.4% increase near the ground in steep terrain. This study can provide a reference for the assessment of extreme wind loads on structures in complex terrain.

Pitch Contour Conversion Using Slanted Gaussian Normalization Based on Accentual Phrases

  • Lee, Ki-Young;Bae, Myung-Jin;Lee, Ho-Young;Kim, Jong-Kuk
    • Speech Sciences
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    • v.11 no.1
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    • pp.31-42
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    • 2004
  • This paper presents methods using Gaussian normalization for converting pitch contours based on prosodic phrases along with experimental tests on the Korean database of 16 declarative sentences and the first sentences of the story of 'The Three Little Pigs'. We propose a new conversion method using Gaussian normalization to the pitch deviation of pitch contour subtracted by partial declination lines: by using partial declination lines for each accentual phrase of pitch contour, we avoid the problem that a Gaussian normalization using average values and standard deviations of intonational phrase tends to lose individual local variability and thus cannot modify individual characteristics of pitch contour from a source speaker to a target speaker. From the results of the experiments, we show that this slanted Gaussian normalization using these declination lines subtracted from pitch contour of accentual phrases can modify pitch contour more accurately than other methods using Gaussian normalization.

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Pollutant Dispersion Analysis Using the Gaussian Puff Model with the Numerical Flowfield Information (유동장 수치해석이 포함된 퍼프모델을 이용한 오염물질의 확산 해석)

  • Jung Y. R.;Park W. G.;Park O. H.
    • Journal of computational fluids engineering
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    • v.4 no.3
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    • pp.12-20
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    • 1999
  • The computations of the flowfield and pollutant dispersion over a flat plate and the Russian hills of various slopes are described. The Gaussian plume and the puff model have been used to calculate concentration of pollutant. The Reynolds-averaged unsteady incompressible Navier-Stokes equation with low Reynolds κ-ε model has been used to calculate the flowfield. The flow data of a flat plate and the Russian hills from Navier-Stokes equation solutions has been used as the input data for the puff model. The computational results of flowfield agree well with experimental results of both a flat plate and Russian hills. The concentration prediction by the Gaussian plume model and the Gaussian puff model also agrees flirty well with experiments.

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CONDITIONAL TRANSFORM WITH RESPECT TO THE GAUSSIAN PROCESS INVOLVING THE CONDITIONAL CONVOLUTION PRODUCT AND THE FIRST VARIATION

  • Chung, Hyun Soo;Lee, Il Yong;Chang, Seung Jun
    • Bulletin of the Korean Mathematical Society
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    • v.51 no.6
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    • pp.1561-1577
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    • 2014
  • In this paper, we define a conditional transform with respect to the Gaussian process, the conditional convolution product and the first variation of functionals via the Gaussian process. We then examine various relationships of the conditional transform with respect to the Gaussian process, the conditional convolution product and the first variation for functionals F in $S_{\alpha}$ [5, 8].

Analysis of Sodium Spray Fire Using Gaussian Droplet Size Distribution (Gaussian 액적 크기 분포 함수를 이용한 분무형 화재 현상 해석)

  • Kim, B.H.;Hahn, D.H.;Suh, S.H.
    • Transactions of the Korean hydrogen and new energy society
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    • v.15 no.1
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    • pp.72-81
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    • 2004
  • Study on the analysis of sodium spray fire using Gaussian drop size distribution, which redistributes a droplet spectrum with given mean diameter if its size classes with critical diameter(D>8mm) occur, was carried out. In this case, the oversized droplets were reduced to a stable diameter. Results calculated by the code using Gaussian drop size distribution were in better agreement with AI experimental results than those of NACOM and SPRAY code. The effect of variance on pressure in the test cell appeared greatly by introducing Gaussian function, which could represent various sodium droplet size distribution. The increase of the variance with mean droplet size resulted had an important effect upon the pressure in the test cell.

Random number sensitivity in simulation of wind loads

  • Kumar, K. Suresh
    • Wind and Structures
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    • v.3 no.1
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    • pp.1-10
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    • 2000
  • Recently, an efficient and practical method has been developed for the generation of univariate non-Gaussian wind pressure time histories on low building roofs; this methodology requires intermittent exponential random numbers for the simulation. On the other hand, the conventional spectral representation scheme with random phase is found suitable for the generation of univariate Gaussian wind pressure time histories on low building roofs; this simulation scheme requires uniform random numbers. The dependency of these simulation methodologies on the random number generator is one of the items affecting the accuracy of the simultion result; therefore, an attempt has been made to investigate the issue. This note presents the observed sensitivity of random number sets in repetitive simulations of Gaussian and non-Gaussian wind pressures.

Solving Time-dependent Schrödinger Equation Using Gaussian Wave Packet Dynamics

  • Lee, Min-Ho;Byun, Chang Woo;Choi, Nark Nyul;Kim, Dae-Soung
    • Journal of the Korean Physical Society
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    • v.73 no.9
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    • pp.1269-1278
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    • 2018
  • Using the thawed Gaussian wave packets [E. J. Heller, J. Chem. Phys. 62, 1544 (1975)] and the adaptive reinitialization technique employing the frame operator [L. M. Andersson et al., J. Phys. A: Math. Gen. 35, 7787 (2002)], a trajectory-based Gaussian wave packet method is introduced that can be applied to scattering and time-dependent problems. This method does not require either the numerical multidimensional integrals for potential operators or the inversion of nearly-singular matrices representing the overlap of overcomplete Gaussian basis functions. We demonstrate a possibility that the method can be a promising candidate for the time-dependent $Schr{\ddot{o}}dinger$ equation solver by applying to tunneling, high-order harmonic generation, and above-threshold ionization problems in one-dimensional model systems. Although the efficiency of the method is confirmed in one-dimensional systems, it can be easily extended to higher dimensional systems.