Due to the 'soft-field' nature of electrical capacitance tomography, it is necessary to employ an iterative approach for image reconstruction in order to obtain good-quality images. In an iterative algorithm i...
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Due to the 'soft-field' nature of electrical capacitance tomography, it is necessary to employ an iterative approach for image reconstruction in order to obtain good-quality images. In an iterative algorithm it is important to determine the gain factor, i.e., the step length approaching the converging point, because it may either cause divergence or slow down the iterative process. Usually the step length is fixed. In this communication, a method to determine the optimal step length is derived for an iterative algorithm. The efficiency of the method has been demonstrated experimentally.
In this article, we introduce and study the following functional equation arising in dynamic programming of multistage decision processes: [image omitted] In order to solve the functional equation, we suggest some ite...
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In this article, we introduce and study the following functional equation arising in dynamic programming of multistage decision processes: [image omitted] In order to solve the functional equation, we suggest some iterative algorithms. Under certain conditions we give a few sufficient conditions ensuring both the existence and uniqueness of solution for the functional equation and the convergence of these iterative algorithms with respect to the solution. We investigate also properties of nonpositive solutions and nonnegative solutions for several functional equations which are special cases of the above mentioned functional equation. To illustrate the results presented in this article, we construct eight nontrivial examples.
The strong H-tensors have important applications in many areas of science and engineering, e.g., the determination of positive definiteness for an even-order homogeneous polynomial form in the real field. In this pape...
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The strong H-tensors have important applications in many areas of science and engineering, e.g., the determination of positive definiteness for an even-order homogeneous polynomial form in the real field. In this paper, we propose two iterative algorithms with non-parameter for identifying strong H-tensors, which overcome the drawback of choosing the best value of parameter ? in some existing algorithms given by Li et al. and Liu et al. (J. Comput. Appl. Math., 255, 1-14, 2014 and Comput. Appl. Math. 36, 1623-1635, 2017). Some numerical experiments are performed to illustrate the feasibility and effectiveness of our algorithms.
Most iterative techniques for solving the symmetric positive-definite systemAx=b involve approximating the matrixA by another symmetric positive-definite matrixM and then solving a system of the formMz=d at each itera...
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Most iterative techniques for solving the symmetric positive-definite systemAx=b involve approximating the matrixA by another symmetric positive-definite matrixM and then solving a system of the formMz=d at each iteration. On a vector machine such as the CDC-STAR-100, the solution of this new system can be very time consuming. If, however, an approximationM−1 can be given toA−1, the solutionz=M−1d can be computed rapidly by matrix multiplication, a fast operation on the STAR. Approximations using the Neumann expansion of the inverse ofA give reasonable forms forM−1 and are presented. Computational results using the conjugate gradient method for the “5-point” matrixA are given.
In this paper, we introduce and discuss a new system of generalized nonlinear mixed quasivariational inclusions with -monotone operators in Hilbert spaces, which includes several systems of variational inequalities an...
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In this paper, we introduce and discuss a new system of generalized nonlinear mixed quasivariational inclusions with -monotone operators in Hilbert spaces, which includes several systems of variational inequalities and variational inclusions as special cases. By employing the resolvent operator technique associated with -monotone operators, we suggest two iterative algorithms for computing the approximate solutions of the system of generalized nonlinear mixed quasivariational inclusions. Under certain conditions, we obtain the existence of solutions for the system of generalized nonlinear mixed quasivariational inclusions and prove the convergence of the iterative sequences generated by the iterative algorithms. The results presented in this paper extend, improve and unify many known results in recent literature.
This paper investigates an iterative algorithm to control weighting coefficients of transmit/receive spatial filters in a frequency-division duplex (FDD) based eigen-mode space division multiplexing (E-SDM/FDD) system...
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ISBN:
(纸本)9781479958320
This paper investigates an iterative algorithm to control weighting coefficients of transmit/receive spatial filters in a frequency-division duplex (FDD) based eigen-mode space division multiplexing (E-SDM/FDD) system. In this system, weighting matrices of transmit/receive spatial filters are optimized using an iterative algorithm that minimizes the mean square error (MSE) of the virtual received signal, where the receiver feeds back relative channel characteristic information of the forward-link to the transmitter. This paper also presents an alternative feedback control method for optimizing the weighting coefficients of the transmit spatial filter in presence of feedback bit errors;the receiver determines the weighting coefficients at the transmitter and sends back relative information of them to the transmitter. This method will be able to mitigate the performance degradation caused by the feedback bit error. Simulation results of bit error rate (BER) performance proves the effectiveness of the proposed algorithm in the E-SDM/FDD 4 x 2 MIMO systems.
This paper proposes a new iterative fuzzy clustering (IFC) algorithm to impute missing values of datasets. The information provided by fuzzy clustering is used to update the imputed values through iterations. The perf...
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ISBN:
(纸本)9781509060344
This paper proposes a new iterative fuzzy clustering (IFC) algorithm to impute missing values of datasets. The information provided by fuzzy clustering is used to update the imputed values through iterations. The performance of the IFC algorithm is examined by conducting experiments on three commonly used datasets and a case study on a city mobility database. Experimental results show that the IFC algorithm not only works well for datasets with a small number of missing values but also provides an effective imputation result for datasets where the proportion of missing data is high.
The subaperture stitching interferometry is a technique suitable for testing high numerical-aperture optics, large-diameter spherical lenses and aspheric optics. In the stitching process, each subaperture has to be pl...
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ISBN:
(纸本)9781628417418
The subaperture stitching interferometry is a technique suitable for testing high numerical-aperture optics, large-diameter spherical lenses and aspheric optics. In the stitching process, each subaperture has to be placed at its correct position in a global coordinate, and the positioning precision would affect the accuracy of stitching result. However, the mechanical limitations in the alignment process as well as vibrations during the measurement would induce inevitable subaperture position uncertainties. In our previous study, a rotational scanning subaperture stitching interferometer has been constructed. This paper provides an iterative algorithm to correct the subaperture position without altering the interferometer configuration. Each subaperture is first placed at its geometric position estimated according to the F number of reference lens, the measurement zenithal angle and the number of pixels along the width of subaperture. By using the concept of differentiation, a shift compensator along the radial direction of the global coordinate is added into the stitching algorithm. The algorithm includes two kinds of compensators: one for the geometric null with four compensators of piston, two directional tilts and defocus, and the other for the position correction with the shift compensator. These compensators are computed iteratively to minimize the phase differences in the overlapped regions of subapertures in a least-squares sense. The simulation results demonstrate that the proposed method works to the position accuracy of 0.001 pixels for both the single-ring and multiple-ring configurations. Experimental verifications with the single-ring and multiple-ring data also show the effectiveness of the algorithm.
The conventional iterative Foruier transform algorithm proposed by Fienup which reconstruct the phase from the modulus is improved. Stagnation from which the conventional algorithm often suffers doses not occur in the...
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ISBN:
(纸本)081944121X
The conventional iterative Foruier transform algorithm proposed by Fienup which reconstruct the phase from the modulus is improved. Stagnation from which the conventional algorithm often suffers doses not occur in the improved algorithm.
This paper proposes a method for solving the monostatic radar cross section of the target with the iterative solution of the method of moments. In this method, the randomized algorithm is adapted to enhance the comput...
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ISBN:
(纸本)9780996007894
This paper proposes a method for solving the monostatic radar cross section of the target with the iterative solution of the method of moments. In this method, the randomized algorithm is adapted to enhance the computational efficiency of the matrix solution step by compressing the impedance matrix and the excitation matrix. The results of calculation examples show that the method is efficient and reliable.
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