Encontrados 6 documentos, a visualizar página 1 de 1
Enriching MATLAB with aspect-oriented features for developing embedded systems
Cardoso, João M. P.; Fernandes, João M.; Monteiro, Miguel Pessoa; Carvalho, Tiago; Nobre, RicardoThis article presents an approach to enrich the MATLAB language with aspect-oriented modularity features, enabling developers to experiment different implementation characteristics and to acquire runtime data and traces without polluting their base MATLAB code. We propose a language through which programmers configure the low-level data representation of variables and expressions. Examples include specifically-...
A Methodology to Design FPGA-based PID Controllers
Lima, João M. G.; Menotti, Ricardo; Cardoso, João M. P.; Marques, EduardoThis paper presents a methodology to implement PID (Proportional, Integral, Derivative) controllers in FPGAs (Field-Programmable Gate Arrays) using fixed-point numerical representation. The Matlab/Simulink environment is used for modeling, simulation and evaluation the performance provided by different fixed-point representations using a given control process. A static bit-width analyzer is used to give a speci...
Dead-time analysis of digital spectrometers
Cardoso, João M.; Simões, J. Basílio; Correia, Carlos M. B. A.This paper studies the impact that the outcome of new digital architectures has brought to dead time of spectrometers. Special emphasis is given to the performance comparison between conventional spectrometers and the most important architectures usually adopted in the digital solutions. Dead-time analysis is accomplished through a dedicated numerical simulation application developed with the purpose of optimiz...
Energy linearity response of CZT detectors to X-rays in the region of the Zn, C...
Freitas, E. D. C.; Cardoso, João M.; Fernandes, L. M. P.; Lopes, J. A. M.; Veloso, J. F. C. A.; Santos, J. M. F. dosThe response of a cadmium zinc telluride (CZT) detector to X-rays with energies around the Zn, Cd and Te K-absorption edges was investigated. The energy non-linearity in the detector response at the K-edges is less than 0.1%, within the experimental errors. No abrupt variation in both the w-value and the detector energy resolution was observed at the K-edges, a behaviour consistent with the absence of intrinsic...
CdZnTe spectra improvement through digital pulse amplitude correction using the...
Cardoso, João M.; Simões, J. Basílio; Menezes, Tiago; Correia, Carlos M. B. A.This paper presents innovative algorithms for optimum filtering, rise-time discrimination and proper correction of solid-state detector pulses based on digital pulse processing (DPP) techniques and on a Linear Sliding Method. These techniques allow a significant improvement on the spectral resolution by taking into account both the electronic noise and the pulse rise time fluctuations mainly due to the incomple...
A mixed analog-digital pulse spectrometer
Cardoso, João M. R.; Basílio Simões, J.; Correia, Carlos M. B. A.This paper presents and discusses some applications and advantages of a hybrid spectrometer system that contains a high performance Pulse-Height Analyzer (PHA) and a Digital Pulse Processor (DPP). This mixed analog-digital system, based on a TMS320C31 Digital Signal Processor (DSP), is implemented in a single board to be hosted in the Personal Computer's ISA bus. Beyond the independent use of the PHA and the DP...
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