The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
G Hariharan - One of the best experts on this subject based on the ideXlab platform.
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an efficient wavelet based Approximation Method to water quality assessment model in a uniform channel
Ain Shams Engineering Journal, 2014Co-Authors: G HariharanAbstract:Abstract In this paper, we have developed an efficient shifted second kind Chebyshev wavelets based Approximation Method to water quality assessment model problem. The governing equation of the uniform flow model is one-dimensional convection diffusion equation (CDE) with variable coefficients. This water quality model requires the calculation of the substance dispersion given the water velocity in the channel. To the best of our knowledge, until now there is no rigorous wavelet solution has been reported for the water quality model problem. The shifted second kind Chebyshev wavelet Method (CWM) for assessment of the chemical oxygen demand (COD) in a river is considered. Some numerical examples are presented to demonstrate the validity and applicability of the Method.
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an efficient legendre wavelet based Approximation Method for a few newell whitehead and allen cahn equations
The Journal of Membrane Biology, 2014Co-Authors: G HariharanAbstract:In this paper, a wavelet-based Approximation Method is introduced for solving the Newell–Whitehead (NW) and Allen–Cahn (AC) equations. To the best of our knowledge, until now there is no rigorous Legendre wavelets solution has been reported for the NW and AC equations. The highest derivative in the differential equation is expanded into Legendre series, this Approximation is integrated while the boundary conditions are applied using integration constants. With the help of Legendre wavelets operational matrices, the aforesaid equations are converted into an algebraic system. Block pulse functions are used to investigate the Legendre wavelets coefficient vectors of nonlinear terms. The convergence of the proposed Methods is proved. Finally, we have given some numerical examples to demonstrate the validity and applicability of the Method.
Shyuli Chiou - One of the best experts on this subject based on the ideXlab platform.
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a new wls chebyshev Approximation Method for the design of fir digital filters with arbitrary complex frequency response
Signal Processing, 1992Co-Authors: Chongyung Chi, Shyuli ChiouAbstract:Abstract In this paper, motivated by Chi-Kou's weighted least-squares (WLS) Chebyshev Approximation Method for the design of FIR filters with linear phase, we propose a new self-initiated iterative WLS Chebyshev Approximation Method for the design of FIR digital filters with arbitrary complex frequency response and real filter coefficients. The proposed Method not only inherits all the advantages of Chi-Kou's Method but also is computationally more efficient than Chi-Kou's Method for the case of linear phase FIR filter design. On the other hand, contrast to Chit-Mason's time-domain least mean square (LMS) Approximation Methods, the proposed Method is a frequency-domain WLS Method based on similar philosophies. Several design examples are provided to demonstrate the good performance of the proposed Method.
S.-l. Chiou - One of the best experts on this subject based on the ideXlab platform.
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A new iterative WLS Chebyshev Approximation Method for the design of two-dimensional FIR digital filters
1993 IEEE International Symposium on Circuits and Systems, 1993Co-Authors: S.-l. ChiouAbstract:Based on Chi-Chiou's weighted least-squares (WLS) Chebyshev Approximation Method for the design of one-dimensional (1-D) finite impulse response (FIR) digital filters with arbitrary complex frequency response, a new iterative WLS Chebyshev Approximation Method is proposed for the design of two-dimensional (2-D) FIR digital filters with arbitrary complex frequency response. Several design examples are provided to show the good performance of the proposed Approximation Method.
Ungi Jong - One of the best experts on this subject based on the ideXlab platform.
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influence of halide composition on the structural electronic and optical properties of mixedch3nh3pb i1 xbrx 3perovskites calculated using the virtual crystal Approximation Method
Physical Review B, 2016Co-Authors: Ungi Jong, Choljun Yu, Jinsong Ri, Gukchol RiAbstract:Extensive studies have demonstrated the promising capability of the organic-inorganic hybrid halide perovskite ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbI}}_{3}$ in solar cells with a high power conversion efficiency exceeding 20%. However, the intrinsic as well as extrinsic instabilities of this material remain the major challenge to the commercialization of perovskite-based solar cells. Mixing halides is expected to resolve this problem. Here, we investigate the effect of chemical substitution in the position of the halogen atom on the structural, electronic, and optical properties of mixed halide perovskites ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}\mathrm{Pb}{({\mathrm{I}}_{1\ensuremath{-}x}{\mathrm{Br}}_{x})}_{3}$ with a pseudocubic phase using the virtual crystal Approximation Method within density functional theory. With an increase of Br content $x$ from 0.0 to 1.0, the lattice constant decreases in proportion to $x$ with the function of $a(x)=6.420\ensuremath{-}0.333x$ (\AA{}), while the band gap and the exciton binding energy increase with the quadratic function of ${E}_{g}(x)=1.542+0.374x+0.185{x}^{2}$ (eV) and the linear function of ${E}_{b}(x)=0.045+0.057x$ (eV), respectively. The photoabsorption coefficients are also calculated, showing a blueshift of the absorption onsets for higher Br contents. We calculate the phase decomposition energy of these materials and analyze the electronic charge density difference to estimate the material stability. Based on the calculated results, we suggest that the best match between efficiency and stability can be achieved at $x\ensuremath{\approx}0.2$ in ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}\mathrm{Pb}{({\mathrm{I}}_{1\ensuremath{-}x}{\mathrm{Br}}_{x})}_{3}$ perovskites.
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influence of halide composition on the structural electronic and optical properties of mixed ch 3 nh 3 pb i 1 x br x 3 perovskites calculated using the virtual crystal Approximation Method
Physical Review B, 2016Co-Authors: Ungi Jong, Namhyok KimAbstract:Extensive studies have demonstrated the promising capability of the organic-inorganic hybrid halide perovskite ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbI}}_{3}$ in solar cells with a high power conversion efficiency exceeding 20%. However, the intrinsic as well as extrinsic instabilities of this material remain the major challenge to the commercialization of perovskite-based solar cells. Mixing halides is expected to resolve this problem. Here, we investigate the effect of chemical substitution in the position of the halogen atom on the structural, electronic, and optical properties of mixed halide perovskites ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}\mathrm{Pb}{({\mathrm{I}}_{1\ensuremath{-}x}{\mathrm{Br}}_{x})}_{3}$ with a pseudocubic phase using the virtual crystal Approximation Method within density functional theory. With an increase of Br content $x$ from 0.0 to 1.0, the lattice constant decreases in proportion to $x$ with the function of $a(x)=6.420\ensuremath{-}0.333x$ (\AA{}), while the band gap and the exciton binding energy increase with the quadratic function of ${E}_{g}(x)=1.542+0.374x+0.185{x}^{2}$ (eV) and the linear function of ${E}_{b}(x)=0.045+0.057x$ (eV), respectively. The photoabsorption coefficients are also calculated, showing a blueshift of the absorption onsets for higher Br contents. We calculate the phase decomposition energy of these materials and analyze the electronic charge density difference to estimate the material stability. Based on the calculated results, we suggest that the best match between efficiency and stability can be achieved at $x\ensuremath{\approx}0.2$ in ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}\mathrm{Pb}{({\mathrm{I}}_{1\ensuremath{-}x}{\mathrm{Br}}_{x})}_{3}$ perovskites.
Chongyung Chi - One of the best experts on this subject based on the ideXlab platform.
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a new wls chebyshev Approximation Method for the design of fir digital filters with arbitrary complex frequency response
Signal Processing, 1992Co-Authors: Chongyung Chi, Shyuli ChiouAbstract:Abstract In this paper, motivated by Chi-Kou's weighted least-squares (WLS) Chebyshev Approximation Method for the design of FIR filters with linear phase, we propose a new self-initiated iterative WLS Chebyshev Approximation Method for the design of FIR digital filters with arbitrary complex frequency response and real filter coefficients. The proposed Method not only inherits all the advantages of Chi-Kou's Method but also is computationally more efficient than Chi-Kou's Method for the case of linear phase FIR filter design. On the other hand, contrast to Chit-Mason's time-domain least mean square (LMS) Approximation Methods, the proposed Method is a frequency-domain WLS Method based on similar philosophies. Several design examples are provided to demonstrate the good performance of the proposed Method.