Wyniki wyszukiwania - Biblioteka Nauki

1

An Overview of ATmega AVR Microcontrollers Used in Scientific Research and Industrial Applications

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Kunikowski W. , Czerwiński E. , Olejnik P. , Awrejcewicz J.

Pomiary Automatyka Robotyka

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2015

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tom R. 19, nr 1

15--19

EN

Nowadays, microcontrollers are commonly used in many fields of industrial applications previously dominated by other devices. Their strengths such as: processing power, low cost, and small sizes enable them to become substitutes for industrial PLC controllers, analog electronic circuits, and many more. In first part of this article an overview of the Atmel AVR microprocessor family can be found, alongside with many scientific and industrial applications. Second part of this article contains a detailed description of two implementations of ATmega644PA microprocessor. First one is a controller with PID regulation that supports a DC motor driver. Second one is a differential equation solver with 4-th order Runge-Kutta method implemented. It is used for solving a torsion pendulum dynamics. Finally, some general conclusions regarding the two presented implementations are made.

PL

W dzisiejszych czasach mikrokontrolery są często używane w miejscach poprzednio zdominowanych przez inne układy logiczne. Argumenty przemawiające za stosowaniem tych układów, takie jak: moc obliczeniowa, niski koszt i małe rozmiary, pozwalają na zastępowanie nimi przemysłowych sterowników PLC i innych elektronicznych układów analogowych. W pierwszej części artykułu przedstawiono przegląd dostępnych mikroprocesorów Atmel AVR, uwzględniając przykłady naukowych i przemysłowych zastosowań. Druga część zawiera szczegółowy opis dwóch implementacji procesora ATmega644PA, przeprowadzonych przez autorów pracy. Pierwsza przedstawia regulator PID silnika prądu stałego obciążonego zmiennym momentem. Kolejna przedstawia implementację metody Runge-Kutty czwartego rzędu, stosowanej często do rozwiązywania równań różniczkowych. Algorytm został zastosowany do rozwiązania zadania dynamiki ruchu obrotowego wahadła torsyjnego na mikrokontrolerze.

2

Modeling and parameter identification of vibrations of a double torsion pendulum with friction

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Czerwiński E. , Olejnik P. , Awrejcewicz J.

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tom Vol. 9, no. 4

204--212

EN

The purpose of this paper is to investigate a double torsion pendulum with planar frictional contact. The single torsion pendulum with one-degree-of-freedom is an angular equivalent of the linear harmonic oscillator. The second degree of freedom has been obtained by adding a free body to the inverted single torsion pendulum. The free body’s angular displacement is caused by frictional forces appearing in the interface (contact zone) between the free body and the pendulum column’s head kinematically excited at its base by a mechanism with torsion spiral spring. An experimental station has been set up and run to find most unknown parameters of the pendulum from the time series of state variables taken as inputs to the Nelder-Mead method of identification. The obtained results proved significant usability of the identification method in the case of numerical simulation of the pendulum’s dynamical model. It has not been satisfactorily proved in the case of time characteristics coming from a real system that exhibits also some unrecognized physical effects.

3

Application of the compress sensing theory for improvement of the TOF resolution in a novel J-PET instrument

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Raczyński L. , Moskal P. , Kowalski P. , Wiślicki W. , Bednarski T. , Białas P. , Czerwiński E. , Gajos A. , Kapłon Ł. , Kochanowski A. , Korcyl G. , Kowal J. , Kozik T. , Krzemień W. , Kubicz E. , Niedźwiecki S. , Pałka M. , Rudy Z. , Salabura P. , Gupta-Sharma N. , Silarski M. , Słomski A. , Smyrski J. , Strzelecki A. , Wieczorek A. , Zieliński M. , Zoń N.

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2016

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tom Vol. 61, No. 1

35--39

EN

Nowadays, in positron emission tomography (PET) systems, a time of fl ight (TOF) information is used to improve the image reconstruction process. In TOF-PET, fast detectors are able to measure the difference in the arrival time of the two gamma rays, with the precision enabling to shorten signifi cantly a range along the line-of-response (LOR) where the annihilation occurred. In the new concept, called J-PET scanner, gamma rays are detected in plastic scintillators. In a single strip of J-PET system, time values are obtained by probing signals in the amplitude domain. Owing to compressive sensing (CS) theory, information about the shape and amplitude of the signals is recovered. In this paper, we demonstrate that based on the acquired signals parameters, a better signal normalization may be provided in order to improve the TOF resolution. The procedure was tested using large sample of data registered by a dedicated detection setup enabling sampling of signals with 50-ps intervals. Experimental setup provided irradiation of a chosen position in the plastic scintillator strip with annihilation gamma quanta.

4

3D PET image reconstruction based on the maximum likelihood estimation method (MLEM) algorithm

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Słomski A. , Rudy Z. , Bednarski T. , Białas P. , Czerwiński E. , Kapłon Ł. , Kochanowski A. , Korcyl G. , Kowal J. , Kowalski P. , Kozik T. , Krzemień W. , Molenda M. , Moskal P. , Niedźwiecki S. , Pałka M. , Pawlik M. , Raczyński L. , Salabura P. , Gupta-Sharma N. , Silarski M. , Smyrski J. , Strzelecki A. , Wiślicki W. , Zieliński M. , Zoń N.

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tom Vol. 10, no. 1

1--7

EN

A positron emission tomography (PET) scan does not measure an image directly. Instead, a PET scan measures a sinogram at the boundary of the field-of-view that consists of measurements of the sums of all the counts along the lines connecting the two detectors. Because there is a multitude of detectors built in a typical PET structure, there are many possible detector pairs that pertain to the measurement. The problem is how to turn this measurement into an image (this is called imaging). Significant improvement in PET image quality was achieved with the introduction of iterative reconstruction techniques. This was realized approximately 20 years ago (with the advent of new powerful computing processors). However, three-dimensional imaging still remains a challenge. The purpose of the image reconstruction algorithm is to process this imperfect count data for a large number (many millions) of lines of response and millions of detected photons to produce an image showing the distribution of the labeled molecules in space.

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PALS investigations of free volumes thermal expansion of J-PET plastic scintillator synthesized in polystyrene matrix

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Wieczorek A. , Zgardzińska B. , Jasińska B. , Gorgol M. , Bednarski T. , Białas P. , Czerwiński E. , Gajos A. , Kamińska D. , Kapłon Ł. , Kochanowski A. , Korcyl G. , Kowalski P. , Kozik T. , Krzemień W. , Kubicz E. , Niedźwiecki S. , Pałka M. , Raczyński L. , Rudy Z. , Rundel O. , Sharma N. G. , Silarski M. , Silarski A. , Strzelecki A. , Wiślicki W. , Zieliński M. , Moskal P.

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tom Vol. 60, No. 4, part 1

777--781

EN

The polystyrene doped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenyl)benzoxazole as a wavelength shifter prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260, 283, and 370 K were found in the material. In the o-Ps intensity dependence on temperature, the significant hysteresis is observed. Heated to 370 K, the material exhibits the o-Ps intensity variations in time.

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Processing optimization with parallel computing for the J-PET scanner

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Krzemień W. , Bała M. , Bednarski T. , Białas P. , Czerwiński E. , Gajos A. , Gorgol M. , Jasińska B. , Kamińska D. , Kapłon Ł. , Korcyl G. , Kowalski P. , Kozik T. , Kubicz E. , Niedźwiecki S. , Pałka M. , Raczyński L. , Rudy Z. , Rundel O. , Sharma N. G. , Silarski M. , Słomski A. , Stola K. , Strzelecki A. , Trybek D. , Wieczorek A. , Wiślicki W. , Zieliński M. , Zgardzińska B. , Moskal P.

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tom Vol. 60, No. 4, part 1

745--748

EN

The Jagiellonian Positron Emission Tomograph (J-PET) collaboration is developing a prototype time of flight (TOF)-positron emission tomograph (PET) detector based on long polymer scintillators. This novel approach exploits the excellent time properties of the plastic scintillators, which permit very precise time measurements. The very fast fi eld programmable gate array (FPGA)-based front-end electronics and the data acquisition system, as well as low- and high-level reconstruction algorithms were specially developed to be used with the J-PET scanner. The TOF-PET data processing and reconstruction are time and resource demanding operations, especially in the case of a large acceptance detector that works in triggerless data acquisition mode. In this article, we discuss the parallel computing methods applied to optimize the data processing for the J-PET detector. We begin with general concepts of parallel computing and then we discuss several applications of those techniques in the J-PET data processing.