Iterative Algorithms for Large Scale Wave Front Reconstruction

2001 ◽  
Author(s):  
Luc Gilles ◽  
Curtis R. Vogel ◽  
Brent L. Ellerbroek
Keyword(s):  
Wave Front ◽  
Large Scale ◽  
Iterative Algorithms

scholarly journals Alternating Asymmetric Iterative Algorithm Based on Domain Decomposition for 3D Poisson Problem

Mathematics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 281
Author(s):  
Qiuyan Xu ◽  
Zhiyong Liu
Keyword(s):  
Domain Decomposition ◽  
Iterative Algorithm ◽  
Poisson Equation ◽  
Large Scale ◽  
Linear Equations ◽  
Iterative Algorithms ◽  
Computation Time ◽  
Explicit Method ◽  
Computational Process ◽  
Poisson Problem

Poisson equation is a widely used partial differential equation. It is very important to study its numerical solution. Based on the strategy of domain decomposition, the alternating asymmetric iterative algorithm for 3D Poisson equation is provided. The solution domain is divided into several sub-domains, and eight asymmetric iterative schemes with the relaxation factor for 3D Poisson equation are constructed. When the numbers of iteration are odd or even, the computational process of the presented iterative algorithm are proposed respectively. In the calculation of the inner interfaces, the group explicit method is used, which makes the algorithm to be performed fast and in parallel, and avoids the difficulty of solving large-scale linear equations. Furthermore, the convergence of the algorithm is analyzed theoretically. Finally, by comparing with the numerical experimental results of Jacobi and Gauss Seidel iterative algorithms, it is shown that the alternating asymmetric iterative algorithm based on domain decomposition has shorter computation time, fewer iteration numbers and good parallelism.

Iterative Algorithms to Generate Large Scale Mosaic Images

2015 ◽  
pp. 203-208 ◽  
Author(s):  
Lorenzo Toso ◽  
Stephan Allgeier ◽  
Franz Eberle ◽  
Susanne Maier ◽  
Klaus-Martin Reichert ◽  
...  
Keyword(s):  
Large Scale ◽  
Iterative Algorithms ◽  
Mosaic Images

scholarly journals Mesospheric bores at southern midlatitudes observed by ISS-IMAP/VISI: a first report of an undulating wave front

2018 ◽  
Vol 18 (22) ◽  
pp. 16399-16407 ◽  
Author(s):  
Yuta Hozumi ◽  
Akinori Saito ◽  
Takeshi Sakanoi ◽  
Atsushi Yamazaki ◽  
Keisuke Hosokawa
Keyword(s):  
Wave Front ◽  
Large Scale ◽  
Near Infrared ◽  
Inversion Layer ◽  
Space Station ◽  
Temperature Inversion ◽  
Wide Field ◽  
Broadband Emission ◽  
The Difference ◽  
Spectral Imager

Abstract. Large-scale spatial structures of mesospheric bores were observed by the Visible and near-Infrared Spectral Imager (VISI) of the ISS-IMAP mission (Ionosphere, Mesosphere, upper Atmosphere and Plasmasphere mapping mission from the International Space Station) in the mesospheric O2 airglow at 762 nm wavelength. Two mesospheric bore events in southern midlatitudes are reported in this paper: one event at 48–54∘ S, 10–20∘ E on 9 July 2015 and the other event at 35–43∘ S, 24∘ W–1∘ E on 7 May 2013. For the first event, the temporal evolution of the mesospheric bore was investigated from the difference of two observations in consecutive passes. The estimated eastward speed of the bore is 100 m s−1. The number of trailing waves increased with a rate of 3.5 waves h−1. Anticlockwise rotation with a speed of 20∘ h−1 was also recognized. These parameters are similar to those reported by previous studies based on ground-based measurements, and the similarity supports the validity of VISI observation for mesospheric bores. For the second event, VISI captured a mesospheric bore with a large-scale and undulating wave front. The horizontal extent of the wave front was 2200 km. The long wave front undulated with a wavelength of 1000 km. The undulating wave front is a new feature of mesospheric bores revealed by the wide field of view of VISI. We suggest that nonuniform bore propagating speed due to inhomogeneous background ducting structure might be a cause of the undulation of the wave front. Temperature measurements from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) onboard the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) satellite indicated that bores of both events were ducted in a temperature inversion layer.

A Study of Sparse Matrix Methods on New Hardware

2015 ◽  
Vol 3 (3) ◽  
pp. 1-19
Author(s):  
Athanasios Fevgas ◽  
Konstantis Daloukas ◽  
Panagiota Tsompanopoulou ◽  
Panayiotis Bozanis
Keyword(s):  
Power Systems ◽  
Linear Systems ◽  
Large Scale ◽  
Comprehensive Evaluation ◽  
Sparse Matrix ◽  
Electrical Power ◽  
Iterative Algorithms ◽  
Direct Methods ◽  
Computer Hardware ◽  
Computing Platforms

Modeling of numerous scientific and engineering problems, such as multi-physic problems and analysis of electrical power systems, amounts to the solution of large scale linear systems. The main characteristics of such systems are the large sparsity ratio and the large number of unknowns that can reach thousands or even millions of equations. As a result, efficient solution of sparse large-scale linear systems is of great importance in order to enable analysis of such problems. Direct and iterative algorithms are the prevalent methods for solution of linear systems. Advances in computer hardware provide new challenges and capabilities for sparse solvers. The authors present a comprehensive evaluation of some, state of the art, sparse methods (direct and iterative) using modern computing platforms, aiming to determine the performance boundaries of each solver on different hardware infrastructures. By identifying the potential performance bottlenecks of out-of-core direct methods, the authors present a series of optimizations that increase their efficiency on flash-based systems.

PARALLEL DISTRIBUTED SOLVERS FOR LARGE STABLE GENERALIZED LYAPUNOV EQUATIONS

1999 ◽  
Vol 09 (01) ◽  
pp. 147-158 ◽  
Author(s):  
PETER BENNER ◽  
JOSÉ M. CLAVER ◽  
ENRIQUE S. QUINTANA-ORTI
Keyword(s):  
Large Scale ◽  
Iterative Algorithms ◽  
Direct Methods ◽  
Matrix Equations ◽  
Distributed Architectures ◽  
Matrix Sign Function ◽  
Sign Function ◽  
The Matrix ◽  
Qz Algorithm ◽  
Lyapunov Matrix

In this paper we study the solution of stable generalized Lyapunov matrix equations with large-scale, dense coefficient matrices. Our iterative algorithms, based on the matrix sign function, only require scalable matrix algebra kernels which are highly efficient on parallel distributed architectures. This approach avoids therefore the difficult parallelization of direct methods based on the QZ algorithm. The experimental analtsis reports a remarkable performance of our solvers on an IBM SP2 platform.

Laboratory simulation of large-scale wave front distortions in a turbulent atmosphere

1996 ◽  
Author(s):  
Sergei S. Chesnokov ◽  
I. V. Davletshina ◽  
Alexander V. Koryabin ◽  
Victor I. Shmalhausen
Keyword(s):  
Wave Front ◽  
Turbulent Atmosphere ◽  
Large Scale ◽  
Laboratory Simulation
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