The Experts below are selected from a list of 6996 Experts worldwide ranked by ideXlab platform
E Baron - One of the best experts on this subject based on the ideXlab platform.
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a 3d radiative transfer framework iv spherical and Cylindrical Coordinate systems
2009Co-Authors: P H Hauschildt, E BaronAbstract:Aims. We extend our framework for 3D radiative transfer calculations with a non-local operator splitting methods along (full) characteristics to spherical and Cylindrical Coordinate systems. These Coordinate systems are better suited to a number of physical problems than Cartesian Coordinates. Methods. The scattering problem for line transfer is solved via means of an operator splitting (OS) technique. The formal solution is based on a full characteristics method. The approximate Λ operator is constructed considering nearest neighbors exactly. The code is parallelized over both wavelength and solid angle using the MPI library. Results. We present the results of several test cases with different values of the thermalization parameter for the different Coordinate systems. The results are directly compared to 1D plane parallel tests. The 3D results agree very well with the well-tested 1D calculations. Conclusions. Advances in modern computers will make realistic 3D radiative transfer calculations possible in the near future.
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a 3d radiative transfer framework iv spherical Cylindrical Coordinate systems
2009Co-Authors: P H Hauschildt, E BaronAbstract:We extend our framework for 3D radiative transfer calculations with a non-local operator splitting methods along (full) characteristics to spherical and Cylindrical Coordinate systems. These Coordinate systems are better suited to a number of physical problems than Cartesian Coordinates. The scattering problem for line transfer is solved via means of an operator splitting (OS) technique. The formal solution is based on a full characteristics method. The approximate $\Lambda$ operator is constructed considering nearest neighbors exactly. The code is parallelized over both wavelength and solid angle using the MPI library. We present the results of several test cases with different values of the thermalization parameter for the different Coordinate systems. The results are directly compared to 1D plane parallel tests. The 3D results agree very well with the well-tested 1D calculations.
P H Hauschildt - One of the best experts on this subject based on the ideXlab platform.
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a 3d radiative transfer framework iv spherical and Cylindrical Coordinate systems
2009Co-Authors: P H Hauschildt, E BaronAbstract:Aims. We extend our framework for 3D radiative transfer calculations with a non-local operator splitting methods along (full) characteristics to spherical and Cylindrical Coordinate systems. These Coordinate systems are better suited to a number of physical problems than Cartesian Coordinates. Methods. The scattering problem for line transfer is solved via means of an operator splitting (OS) technique. The formal solution is based on a full characteristics method. The approximate Λ operator is constructed considering nearest neighbors exactly. The code is parallelized over both wavelength and solid angle using the MPI library. Results. We present the results of several test cases with different values of the thermalization parameter for the different Coordinate systems. The results are directly compared to 1D plane parallel tests. The 3D results agree very well with the well-tested 1D calculations. Conclusions. Advances in modern computers will make realistic 3D radiative transfer calculations possible in the near future.
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a 3d radiative transfer framework iv spherical Cylindrical Coordinate systems
2009Co-Authors: P H Hauschildt, E BaronAbstract:We extend our framework for 3D radiative transfer calculations with a non-local operator splitting methods along (full) characteristics to spherical and Cylindrical Coordinate systems. These Coordinate systems are better suited to a number of physical problems than Cartesian Coordinates. The scattering problem for line transfer is solved via means of an operator splitting (OS) technique. The formal solution is based on a full characteristics method. The approximate $\Lambda$ operator is constructed considering nearest neighbors exactly. The code is parallelized over both wavelength and solid angle using the MPI library. We present the results of several test cases with different values of the thermalization parameter for the different Coordinate systems. The results are directly compared to 1D plane parallel tests. The 3D results agree very well with the well-tested 1D calculations.
Achmad Munir - One of the best experts on this subject based on the ideXlab platform.
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Cylindrical Coordinate system-based FDTD method for analysis of THz circular waveguide coated by dielectric material
2016Co-Authors: Antrisha Daneraici Setiawan, Achmad MunirAbstract:This paper presents the analysis of reflectivity and transmissivity for terahertz (THz) circular waveguide coated by dielectric material using Cylindrical Coordinate system-based finite difference time domain (FDTD) method. The analysis is conducted by discretizing a model of THz circular waveguide with the radius of 50μm and the length of 250μm. The scattering parameters in term of reflectivity and transmissivity are extracted from the electric fields obtained at different observation planes. Some scenarios in the analysis of reflectivity and transmissivity are applied by varying the thickness of coated dielectric material inside the circular waveguide compared to the hollow circular waveguide. Others scenarios are carried out by introducing some values of conductivity into the dielectric material. From the results, it is shown that resonant frequencies of circular waveguide coated by dielectric material in transverse electric (TE) mode are lower than the hollow waveguide. It also shows that the circular waveguide coated by dielectric material with the thickness of 7.5μm and the conductivity of 250S/m has better transmissivity than the hollow circular waveguide.
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Scattering parameters extraction of dielectric loaded circular waveguide using Cylindrical Coordinate system-based FDTD method
2015Co-Authors: Ershad Junus Amin, Achmad MunirAbstract:The scattering parameters of circular waveguide loaded with dielectric material is proposed to be extracted using a method of finite-difference time-domain (FDTD) based on Cylindrical Coordinate system. The extraction of scattering parameters, i.e. reflection coefficient (S11) and transmission coefficient (S21), are performed by the electric fields obtained on different observation planes closed to the dielectric material. Some isotropic dielectric material which partially and fully loaded circular waveguide are included in the analysis. To validate the result of FDTD method, another analysis is carried out by using finite element method (FEM) commercialized software. Furthermore, the FDTD method is also applied to analysis a circular waveguide loaded with some anisotropic dielectric material. From the result, it shows that the proposed FDTD method has a good agreement qualitatively compared to the commercialized software with some discrepancy on the extraction result less than 3% for isotropic dielectric material loaded circular waveguide. Meanwhile, there is no result comparison for anisotropic dielectric material loaded circular waveguide due to an inability of commercialized software to perform a simulation in Cylindrical Coordinate system.
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Resonant frequency computation of dielectric material loaded circular waveguide using Cylindrical Coordinate system-based FDTD method
2015Co-Authors: Antrisha Daneraici Setiawan, Hardi Nusantara, Achmad MunirAbstract:In this paper, a Cylindrical Coordinate system-based finite difference time domain (FDTD) method is proposed for resonant frequency computation of dielectric material loaded circular waveguide. The computation is carried out by discretizing a model of circular waveguide resonator which has the radius of 10.12mm and the length of 60mm using FDTD notation and numerically computed to determine its resonant frequency in transverse electric (TE) mode. Some scenarios are applied for loading the waveguide by dielectric materials to analyze its resonant frequency to be compared with the hollow circular waveguide. From the results, it is shown that the TE mode resonant frequency for loaded circular waveguide is lower than of hollow circular waveguide which satisfies the numerical prediction. Meanwhile, from the scenario of circular waveguide partially loaded with dielectric material which is coated from outer region in a certain depth, it is found that the resonant frequency varies depending on the depth of dielectric material or on the volume proportion of dielectric material in the waveguide. The result shows when the proportion of dielectric material is 36% the lower resonant frequency is similar with the waveguide fully loaded with dielectric material.
N. Okiyama - One of the best experts on this subject based on the ideXlab platform.
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A new formulation of visual servoing based on Cylindrical Coordinate system
2005Co-Authors: M. Iwatsuki, N. OkiyamaAbstract:Image-based visual servoing is a flexible and robust technique to control a robot and guide it to a desired position only by using two-dimensional visual data. However, it is well known that the classical visual servoing based on the Cartesian Coordinate system has one crucial problem, that the camera moves backward at infinity, in case that the camera motion from the initial to desired poses is a pure rotation of 1800 around the optical axis. This paper proposes a new formulation of visual servoing, based on a Cylindrical Coordinate system that can shift the position of the origin. The proposed approach can interpret from a pure rotation around an arbitrary axis to the proper camera rotational motion. It is shown that this formulation contains the classical approach based on the Cartesian Coordinate system as an extreme case with the origin located at infinity. Furthermore, we propose a decision method of the origin-shift parameters by estimating a rotational motion from the differences between initial and desired image-plane positions of feature points.
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a new formulation of visual servoing based on Cylindrical Coordinate system with shiftable origin
2002Co-Authors: M. Iwatsuki, N. OkiyamaAbstract:Image-based visual servoing is a flexible and robust technique to control a robot and guide it to a desired position only by using 2D visual data. However, it is well known that the classical visual servoing based on Cartesian Coordinate system has one crucial problem that the camera moves backward at infinity in case that the camera motion from the initial to desired poses is a pure rotation of 180 degrees around the optical axis. This paper proposes a new formulation of visual servoing based on Cylindrical Coordinate system that can shift the position of the origin. The proposed approach can interpret from a pure rotation around an arbitrary axis to the proper camera rotational motion. It is shown that this formulation contains the classical approach based on Cartesian Coordinate system as an extreme case with the origin located at infinity. Furthermore, we propose a decision method of the origin-shift parameters by estimating a rotational motion from the differences between current and desired image-plane positions of feature points.
Antrisha Daneraici Setiawan - One of the best experts on this subject based on the ideXlab platform.
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Cylindrical Coordinate system-based FDTD method for analysis of THz circular waveguide coated by dielectric material
2016Co-Authors: Antrisha Daneraici Setiawan, Achmad MunirAbstract:This paper presents the analysis of reflectivity and transmissivity for terahertz (THz) circular waveguide coated by dielectric material using Cylindrical Coordinate system-based finite difference time domain (FDTD) method. The analysis is conducted by discretizing a model of THz circular waveguide with the radius of 50μm and the length of 250μm. The scattering parameters in term of reflectivity and transmissivity are extracted from the electric fields obtained at different observation planes. Some scenarios in the analysis of reflectivity and transmissivity are applied by varying the thickness of coated dielectric material inside the circular waveguide compared to the hollow circular waveguide. Others scenarios are carried out by introducing some values of conductivity into the dielectric material. From the results, it is shown that resonant frequencies of circular waveguide coated by dielectric material in transverse electric (TE) mode are lower than the hollow waveguide. It also shows that the circular waveguide coated by dielectric material with the thickness of 7.5μm and the conductivity of 250S/m has better transmissivity than the hollow circular waveguide.
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Resonant frequency computation of dielectric material loaded circular waveguide using Cylindrical Coordinate system-based FDTD method
2015Co-Authors: Antrisha Daneraici Setiawan, Hardi Nusantara, Achmad MunirAbstract:In this paper, a Cylindrical Coordinate system-based finite difference time domain (FDTD) method is proposed for resonant frequency computation of dielectric material loaded circular waveguide. The computation is carried out by discretizing a model of circular waveguide resonator which has the radius of 10.12mm and the length of 60mm using FDTD notation and numerically computed to determine its resonant frequency in transverse electric (TE) mode. Some scenarios are applied for loading the waveguide by dielectric materials to analyze its resonant frequency to be compared with the hollow circular waveguide. From the results, it is shown that the TE mode resonant frequency for loaded circular waveguide is lower than of hollow circular waveguide which satisfies the numerical prediction. Meanwhile, from the scenario of circular waveguide partially loaded with dielectric material which is coated from outer region in a certain depth, it is found that the resonant frequency varies depending on the depth of dielectric material or on the volume proportion of dielectric material in the waveguide. The result shows when the proportion of dielectric material is 36% the lower resonant frequency is similar with the waveguide fully loaded with dielectric material.
