A Numerical Approximation Scheme for Large-Scale Optimal Switching Problems with Reaction Delays

2018 ◽  
Author(s):  
Magnus Perninge
Keyword(s):  
Large Scale ◽  
Numerical Approximation ◽  
Approximation Scheme ◽  
Optimal Switching

scholarly journals PFASST-ER: combining the parallel full approximation scheme in space and time with parallelization across the method

2020 ◽  
Vol 23 (1-4) ◽  
Author(s):  
Ruth Schöbel ◽  
Robert Speck
Keyword(s):  
High Performance ◽  
Large Scale ◽  
Approximation Scheme ◽  
Reaction Diffusion ◽  
Multiple Time ◽  
Time Step ◽  
Computing Systems ◽  
Space And Time ◽  
Quasi Newton ◽  
Spectral Deferred Correction

AbstractTo extend prevailing scaling limits when solving time-dependent partial differential equations, the parallel full approximation scheme in space and time (PFASST) has been shown to be a promising parallel-in-time integrator. Similar to space–time multigrid, PFASST is able to compute multiple time-steps simultaneously and is therefore in particular suitable for large-scale applications on high performance computing systems. In this work we couple PFASST with a parallel spectral deferred correction (SDC) method, forming an unprecedented doubly time-parallel integrator. While PFASST provides global, large-scale “parallelization across the step”, the inner parallel SDC method allows integrating each individual time-step “parallel across the method” using a diagonalized local Quasi-Newton solver. This new method, which we call “PFASST with Enhanced concuRrency” (PFASST-ER), therefore exposes even more temporal concurrency. For two challenging nonlinear reaction-diffusion problems, we show that PFASST-ER works more efficiently than the classical variants of PFASST and can use more processors than time-steps.

scholarly journals Water ow on vegetated hill. 1D shallow water equation type model

2015 ◽  
Vol 23 (3) ◽  
pp. 83-96 ◽  
Author(s):  
Stelian Ion ◽  
Dorin Marinescu ◽  
Anca Veronica Ion ◽  
Stefan Gicu Cruceanu ◽  
Virgil Iordache
Keyword(s):  
Mathematical Model ◽  
Shallow Water ◽  
Numerical Approximation ◽  
Approximation Scheme ◽  
Shallow Water Equation ◽  
Simplified Model ◽  
Type Model ◽  
Curvature Radius ◽  
Geometrical Properties ◽  
Mathematical Properties

Abstract A mathematical model for the water ow on a hill covered by variable distributed vegetation is proposed in this article. The model takes into account the variation of the geometrical properties of the terrain surface, but it assumes that the surface exhibits large curvature radius. After describing some theoretical properties for this model, we introduce a simplified model and a well-balanced numerical approximation scheme for it. Some mathematical properties with physical relevance are discussed and finally, some numerical results are presented.

scholarly journals On the calculation of steady-state loss probabilities in the GI/G/2/0 queue

1994 ◽  
Vol 7 (3) ◽  
pp. 397-410 ◽  
Author(s):  
Igor N. Kovalenko ◽  
J. Ben Atkinson
Keyword(s):  
Steady State ◽  
Discrete Time ◽  
Continuous Time ◽  
Numerical Approximation ◽  
Approximation Scheme ◽  
Loss Probability ◽  
Loss Probabilities ◽  
Continuous Time Systems ◽  
Alternative Approach ◽  
Time Systems

This paper considers methods for calculating the steady-state loss probability in the GI/G/2/0 queue. A previous study analyzed this queue in discrete time and this led to an efficient, numerical approximation scheme for continuous-time systems. The primary aim of the present work is to provide an alternative approach by analyzing the GI/ME/2/0 queue; i.e., assuming that the service time can be represented by a matrix-exponential distribution. An efficient computational scheme based on this method is developed and some numerical examples are studied. Some comparisons are made with the discrete-time approach, and the two methods are seen to be complementary.

scholarly journals A structured model for the spread of Mycobacterium marinum: Foundations for a numerical approximation scheme

2014 ◽  
Vol 11 (4) ◽  
pp. 679-721 ◽  
Author(s):  
Azmy S. Ackleh ◽  
◽  
Mark L. Delcambre ◽  
Karyn L. Sutton ◽  
Don G. Ennis ◽  
...  
Keyword(s):  
Numerical Approximation ◽  
Approximation Scheme ◽  
Mycobacterium Marinum ◽  
Structured Model

An O(n3) algorithm for sorting signed genomes by reversals, transpositions, transreversals and block-interchanges

2016 ◽  
Vol 14 (01) ◽  
pp. 1640002 ◽  
Author(s):  
Shuzhi Yu ◽  
Fanchang Hao ◽  
Hon Wai Leong
Keyword(s):  
Approximation Algorithm ◽  
Large Scale ◽  
Genome Rearrangement ◽  
Approximation Scheme ◽  
Running Time ◽  
Breakpoint Graph ◽  
Signed Permutations ◽  
Comparison Results ◽  
Bridge Structures ◽  
Species Evolution

We consider the problem of sorting signed permutations by reversals, transpositions, transreversals, and block-interchanges. The problem arises in the study of species evolution via large-scale genome rearrangement operations. Recently, Hao et al. gave a 2-approximation scheme called genome sorting by bridges (GSB) for solving this problem. Their result extended and unified the results of (i) He and Chen — a 2-approximation algorithm allowing reversals, transpositions, and block-interchanges (by also allowing transversals) and (ii) Hartman and Sharan — a 1.5-approximation algorithm allowing reversals, transpositions, and transversals (by also allowing block-interchanges). The GSB result is based on introduction of three bridge structures in the breakpoint graph, the L-bridge, T-bridge, and X-bridge that models goodreversal, transposition/transreversal, and block-interchange, respectively. However, the paper by Hao et al. focused on proving the 2-approximation GSB scheme and only mention a straightforward [Formula: see text] algorithm. In this paper, we give an [Formula: see text] algorithm for implementing the GSB scheme. The key idea behind our faster GSB algorithm is to represent cycles in the breakpoint graph by their canonical sequences, which greatly simplifies the search for these bridge structures. We also give some comparison results (running time and computed distances) against the original GSB implementation.

scholarly journals Design a New DC-DC Converter for a Grid Connected Photovoltaic System

2021 ◽  
Vol 23 (1) ◽  
pp. 79-86
Author(s):  
Hassen Kaddour ◽  
Abderrahmane Dib
Keyword(s):  
Optimal Control ◽  
Control System ◽  
Power Factor ◽  
High Performance ◽  
Large Scale ◽  
Reactive Power ◽  
Boost Converter ◽  
Photovoltaic System ◽  
Optimal Switching ◽  
Svm Model

This paper presents a recent technique for photovoltaic grid connected systems based on the use of the (DPC-SVM) to select the optimal switching states to apply to the inverter, where the extended reactive power is used instead of reactive power. This technique allows achieving an optimal control of the inverter which manifests in controlling the converters using an MPPT algorithm instead of controlling each part separately. This yields to a reduced global control system on a large scale. In this context, we suggest a DC-DC boost converter circuit to ensure better behavior of the system. The FMV technique is used to inject specific harmonics in order to eliminate or minimize the undesired harmonics. The SVM model has also been developed for optimal control of the inverter to prove the high performance of the proposed method. All the results are analyzed theoretically. The simulation has shown that this strategy gives satisfactory performances, improvement of the power factor and a reduction of the THD by 37%.

Sign in / Sign up

Export Citation Format

Share Document