Retinal DOG Filters: Effects of the Discretization Process

Author(s):  
Adrián Arias ◽  
Eduardo Sánchez ◽  
Luis Martínez
2019 ◽  
Vol 9 (10) ◽  
pp. 2013 ◽  
Author(s):  
Piotr Okoniewski ◽  
Jacek Piskorowski

This paper presents a concept for digital infinite impulse response (IIR) lowpass filter with reduced transient response. The proposed digital filtering structure is based on an analog oscillatory system. In order to design the considered digital filter, the analog prototype is subjected to a discretization process and, then, the parameters describing the dynamical properties of the oscillatory system are temporarily varied in time, so as to suppress the transient response of the designed filter. An optimization method, aimed at reducing the settling time by proper parameter manipulation, is presented. Simulation results, along with a real-life application proving the usefulness of the proposed concept, are also shown and discussed.


2019 ◽  
Vol 9 (21) ◽  
pp. 4570
Author(s):  
Katarzyna Wiechetek ◽  
Jacek Piskorowski

This paper presents a concept of the non-stationary filtering network with reduced transient response consisting of the first-order digital elements with time-varying parameters. The digital filter section is based on the analog system. In order to design the filtering network, the analog prototype was subjected to the discretization process. The time constant and the gain factor were then temporarily varied in time in order to suppress the transient response of the designed filtering structure. The optimization method, based on the Particle Swarm Optimization (PSO) algorithm which is aimed at reducing the settling time by a proper parameter manipulation, is presented. Simulation results proving the usefulness of the proposed concept are also shown and discussed.


2009 ◽  
Vol 147-149 ◽  
pp. 107-112 ◽  
Author(s):  
Roman Trochimczuk ◽  
Marek Gawrysiak

In the work the new concept of polar positioning system, alternative for Cartesian one, is presented. The mathematical model which allows calculation of the rotation angle of polar positioning system is considered. The Cartesian coordinates of formed points of object structure, received after discretization process of object are the inputs data to calculation. Output data however are rotation angles i.e. both working arm and rotation table angles. The influence of the stiffness of mechanical parts on the precision of instrument positioning and productivity of the presented polar device is defined.


Author(s):  
Danang Adi Pratama ◽  
Maharani Abu Bakar ◽  
Mustafa Man ◽  
M. Mashuri

Conventionally, partial differential equations (PDE) problems are solved numerically through discretization process by using finite difference approximations. The algebraic systems generated by this process are then finalized by using an iterative method. Recently, scientists invented a short cut approach, without discretization process, to solve the PDE problems, namely by using machine learning (ML). This is potential to make scientific machine learning as a new sub-field of research. Thus, given the interest in developing ML for solving PDEs, it makes an abundance of an easy-to-use methods that allows researchers to quickly set up and solve problems. In this review paper, we discussed at least three methods for solving high dimensional of PDEs, namely PyDEns, NeuroDiffEq, and Nangs, which are all based on artificial neural networks (ANNs). ANN is one of the methods under ML which proven to be a universal estimator function. Comparison of numerical results presented in solving the classical PDEs such as heat, wave, and Poisson equations, to look at the accuracy and efficiency of the methods. The results showed that the NeuroDiffEq and Nangs algorithms performed better to solve higher dimensional of PDEs than the PyDEns.


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