Search results for "Solver"

A brief overview on the numerical behavior of an implicit meshless method and an outlook to future challenges

2015

In this paper recent results on a leapfrog ADI meshless formulation are reported and some future challenges are addressed. The method benefits from the elimination of the meshing task from the pre-processing stage in space and it is unconditionally stable in time. Further improvements come from the ease of implementation, which makes computer codes very flexible in contrast to mesh based solver ones. The method requires only nodes at scattered locations and a function and its derivatives are approximated by means of a kernel representation. A perceived obstacle in the implicit formulation is in the second order differentiations which sometimes are eccesively sensitive to the node configurat…

A Simple Software-based Resolver To Digital Conversion System

2022

In this paper, a software-based resolver to digital converter (RDC) is proposed. The hardware signal conditioning circuit is realized using common electronic components, while the algorithm can be implemented either using a microcontroller or an FPGA. Its validation and performance analysis has been carried out using an interior permanent magnet synchronous machine drive and, with comparative purposes, an LTN Servotechnik 1024 ppr incremental encoder. Tests show that the proposed RDC is characterized by a good dynamic response and precision, moreover, due to low computational demand, it can be successfully adopted without significant extra cost.

A fast BEM for the analysis of plates with bonded piezoelectric patches

2010

In this paper a fast boundary element method for the elastodynamic analysis of 3D structures with bonded piezoelectric patches is presented. The elastodynamic analysis is performed in the Laplace domain and the time history of the relevant quantities is obtained by inverse Laplace transform. The bonded patches are modelled using a semi-analytical state-space variational approach. The computational features of the technique, in terms of required storage memory and solution time, are improved by a fast solver based on the use of hierarchical matrices. The presented numerical results show the potential of the technique in the study of structural health monitoring (SHM) systems.

An improved five-parameter model for photovoltaic modules

2010

This paper presents a new five-parameter model capable of analytically describing the I–V characteristic of a photovoltaic module for each generic condition of operative temperature and solar irradiance. The parameters of the equivalent electrical circuit are extracted by solving a system of equations based on data commonly issued by manufacturers in standard rating conditions with a trial and error process. The procedure, which does not require any special equations solver, can be easily coded into a short software routine using simple languages and finds the solution of the system of equations with the desired accuracy without needing to be guided towards solutions starting from fitted in…

Beyond the BEM Solution of the M/EEG Forward Problem: a Meshfree Approach

2014

A multidimensional hydrodynamic code for structure evolution in cosmology

1996

A cosmological multidimensional hydrodynamic code is described and tested. This code is based on modern high-resolution shock-capturing techniques. It can make use of a linear or a parabolic cell reconstruction as well as an approximate Riemann solver. The code has been specifically designed for cosmological applications. Two tests including shocks have been considered: the first one is a standard shock tube and the second test involves a spherically symmetric shock. Various additional cosmological tests are also presented. In this way, the performance of the code is proved. The usefulness of the code is discussed; in particular, this powerful tool is expected to be useful in order to study…

Dynamic network identification from non-stationary vector autoregressive time series

2018

Learning the dynamics of complex systems features a large number of applications in data science. Graph-based modeling and inference underpins the most prominent family of approaches to learn complex dynamics due to their ability to capture the intrinsic sparsity of direct interactions in such systems. They also provide the user with interpretable graphs that unveil behavioral patterns and changes. To cope with the time-varying nature of interactions, this paper develops an estimation criterion and a solver to learn the parameters of a time-varying vector autoregressive model supported on a network of time series. The notion of local breakpoint is proposed to accommodate changes at individu…

How can I signal my quality to emerge from the crowd? A study in the crowdsourcing context

2022

Crowdsourcing contests are characterized by an intensive level of competition because of the extensive number of solvers that voluntarily self-select to participate in such contests. This study aims at understanding how solvers can signal their quality attributes through the community functionalities, i.e. the online profile and the discussion blog of the crowdsourcing platform, to improve their chances of winning crowdsourcing contests. Drawing on signaling theory, we hypothesize that signaling their skills and capabilities by crafting profiles rich in personal and professional information and by participating actively within the discussion blog by posting and commenting, solvers can influ…

A marching in space and time solver for the complete 2D shallow water equations. Application to real test cases.

2006

Solving Graph Coloring Problems Using Learning Automata

2008

The graph coloring problem (GCP) is a widely studied combinatorial optimization problem with numerous applications, including time tabling, frequency assignment, and register allocation. The growing need for more efficient algorithms has led to the development of several GCP solvers. In this paper, we introduce the first GCP solver that is based on Learning Automata (LA). We enhance traditional Random Walk with LA-based learning capability, encoding the GCP as a Boolean satisfiability problem (SAT). Extensive experiments demonstrate that the LA significantly improve the performance of RW, thus laying the foundation for novel LA-based solutions to the GCP.