There are many numerical algorithms for solving the fractional-order differential equations (FODEs). The numerical algorithms are very different, and it is difficult to compare their performances. To solve this proble...
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ISBN:
(纸本)9781509046577
There are many numerical algorithms for solving the fractional-order differential equations (FODEs). The numerical algorithms are very different, and it is difficult to compare their performances. To solve this problem, some different FODEs with the known analytical solution are designed and proposed, they could be used as the benchmark problems for testing the numerical algorithms. A Simulink block diagram scheme is proposed for solving these benchmark problems, and the computing errors and the running times are reported. These benchmark problems and the solutions are constituted as a framework, and the numerical algorithms for solving the FODEs could be compared in the same framework. The comparing result could assess which algorithm is better to a concrete FODE.
Demands for high-power converters are increasing rapidly. Nevertheless, due to their complex structures and multi-time-scale features, accurate and efficient simulation of such systems has long been a huge obstacle. A...
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ISBN:
(纸本)9781728103952
Demands for high-power converters are increasing rapidly. Nevertheless, due to their complex structures and multi-time-scale features, accurate and efficient simulation of such systems has long been a huge obstacle. Aiming at improving the unacceptably slow simulation speed of high-power converters, this paper improves Discrete State Event-Driven (DSED) approach by implementing a decoupling method. Taking a 10kV 1MW electric energy router as an example, this paper evaluates the effectiveness of DSED with the proposed decoupling method in high-power applications. In the studied case, compared with commercially available tool for power electronics simulation, PLECS (R), DSED can achieve an up to 1000-fold improvement in simulation speed under the same accuracy: PLECS (R) takes 6 hours while DSED only takes 18 seconds. DSED provides a powerful simulation tool for analysis, design and control of high-power converters.
The periodic QZ algorithm (pQZ) is required in many applications, including periodic linear systems, cyclic matrices and matrix pencils, and some structured eigenproblems. The implicit double pQZ step is the essential...
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ISBN:
(纸本)9781728106991
The periodic QZ algorithm (pQZ) is required in many applications, including periodic linear systems, cyclic matrices and matrix pencils, and some structured eigenproblems. The implicit double pQZ step is the essential part of this algorithm, since it determines its convergence rate. The pQZ step acts on a formal matrix product already reduced to the Hessenberg-triangular form. Each pQZ step starts with an initial transformation aimed to make the first column of the identity matrix and of the Wilkinson double-shift polynomial parallel. This transformation is found in an implicit manner, without evaluating the formal matrix product and the polynomial. This paper presents in detail the computation of the initial transformation in the periodic QZ step, and summarizes the benefits obtained using a new such approach for solving skew-Hamiltonian/Hamiltonian eigenproblems. The previous convergence failures are avoided and the number of iterations necessary to converge can be significantly reduced.
Vibration problems of pipelines made of composite materials conveying pulsating flow of gas and fluid are investigated in the paper. A dynamic model of motion of pipelines conveying pulsating fluid flow supported by a...
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Vibration problems of pipelines made of composite materials conveying pulsating flow of gas and fluid are investigated in the paper. A dynamic model of motion of pipelines conveying pulsating fluid flow supported by a Hetenyi's base is developed taking into account the viscosity properties of the structure material, axial forces, internal pressure and Winkler's viscoelastic base. To describe the processes of viscoelastic material strain, the Boltzmann-Volterra integral model with weakly singular hereditary kernels is used. Using the Bubnov-Galerkin method, the problem is reduced to the study of a system of ordinary integro-differential equations (IDE). A computational algorithm is developed based on the elimination of the features of IDE with weakly singular kernels, followed by the use of quadrature formulas. The effect of rheological parameters of the pipeline material, flow rate and base parameters on the vibration of a viscoelastic pipeline conveying pulsating fluid is analyzed. The convergence analysis of the approximate solution of the Bubnov-Galerkin method is carried out. It was revealed that the viscosity parameters of the material and the pipeline base lead to a significant change in the critical flow rate. It was stated that an increase in excitation coefficient of pulsating flow and the parameter of internal pressure leads to a decrease in the critical flow rate. It is shown that an increase in the singularity parameter, the Winkler base parameter, the rigidity parameter of the continuous base layer and the Reynolds number increases the critical flow rate.
Simulating the steam Injection process of pressurized decompression tanks is a challenging engineering problem due to the large amount of computational resource requirements and its complex physical model. This study ...
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ISBN:
(纸本)9781728109459
Simulating the steam Injection process of pressurized decompression tanks is a challenging engineering problem due to the large amount of computational resource requirements and its complex physical model. This study is a necessary algorithmic study to perform a 3D numerical simulation from the PRT (Pressurizer Relief Tank) to the transient dumping process in a chamber containing a tank. Parallel simulation was performed by the open source CFD tool OpenFOAM based on the numerical algorithm we discussed. The results show that the simulation results are in accordance with the basic physical laws, and the results reflect the pressure and temperature of the entire pressure relief tank in detail, which can provide guidance for the safe design of the reactor coolant system.
The next generation of the public domain Storm Water Management Model (SWMM) code needs to be able to effectively use parallelization of 1000 + threads for high-resolution simulation of large urban drainage systems. W...
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ISBN:
(纸本)9783319998671;9783319998664
The next generation of the public domain Storm Water Management Model (SWMM) code needs to be able to effectively use parallelization of 1000 + threads for high-resolution simulation of large urban drainage systems. We propose a new explicit solution technique using a "no-neighbour" finite-volume algorithm. A no-neighbour algorithm is strictly limited in the design of its time/space discretization stencil to limit the communication bandwidth issues that typically cause codes to lose efficiency when applied over large numbers of parallel threads. Returning SWMM to an explicit solver creates a number of challenges for implementing the solution technique, but also raises some new possibilities for how the model can be used. In this work, we briefly describe the proposed algorithm and examine its performance in simulating a steep urban stream.
This paper is devoted to the numerical scheme for the impulsive differential equations. The main idea of this method is, for the first time, to establish a broken reproducing kernel space that can be used in pulse mod...
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This paper is devoted to the numerical scheme for the impulsive differential equations. The main idea of this method is, for the first time, to establish a broken reproducing kernel space that can be used in pulse models. Then the uniform convergence of the numerical solution is proved, and the time consuming Schmidt orthogonalization process is avoided. The proposed method is proved to be stable and have the second-order convergence. The algorithm is proved to be feasible and effective through some numerical examples.
Statistical bivariate numerical modeling is a method to infer an empirical relationship between unpaired sets of data based on statistical distributions matching. In the present paper, a novel efficient numerical algo...
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Statistical bivariate numerical modeling is a method to infer an empirical relationship between unpaired sets of data based on statistical distributions matching. In the present paper, a novel efficient numerical algorithm is proposed to perform bivariate numerical modeling. The algorithm is then applied to correlate glomerular filtration rate to serum creatinine concentration. Glomerular filtration rate is adopted in clinical nephrology as an indicator of kidney function and is relevant for assessing progression of renal disease. As direct measurement of glomerular filtration rate is highly impractical, there is considerable interest in developing numerical algorithms to estimate glomerular filtration rate from parameters which are easier to obtain, such as demographic and 'bedside' assays data.
In the earlier paper of Friedman et al. a simplified model of plaque growth involving LDL and HDL cholesterols, macrophages and foam cells is considered and they satisfy a coupled system of PDEs with a free boundary. ...
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In the earlier paper of Friedman et al. a simplified model of plaque growth involving LDL and HDL cholesterols, macrophages and foam cells is considered and they satisfy a coupled system of PDEs with a free boundary. The paper adds some control function to that model, allowing the controlled growth of LDL, HDL and plaque. Next, the new dual dynamic programming approach for free boundary problem is developed to formulate sufficient optimality conditions for the optimal steering of drugs. Finally an approximate optimality and numerical calculations are presented. (C) 2018 Published by Elsevier Inc.
In this paper, a new algorithm is presented to solve the impulsive delay initial value problems. This is the first time to propose the simplified reproducing kernel method (SRKM for short) to solve the impulsive delay...
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In this paper, a new algorithm is presented to solve the impulsive delay initial value problems. This is the first time to propose the simplified reproducing kernel method (SRKM for short) to solve the impulsive delay differential equations. Then the uniform convergence of the numerical solution is proved, and the time consuming Schmidt orthogonalization process is avoided. The proposed method is proved to be stable and is not less than second order convergence. The algorithm is employed successfully in some numerical examples. (C) 2018 Elsevier Ltd. All rights reserved.
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