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Abstract

This overview paper presents and compares different methods traditionally used for estimating damped sinusoid parameters. Firstly, direct nonlinear least squares fitting the signal model in the time and frequency domains are described. Next, possible applications of the Hilbert transform for signal demodulation are presented. Then, a wide range of autoregressive modelling methods, valid for damped sinusoids, are discussed, in which frequency and damping are estimated from calculated signal linear self-prediction coefficients. These methods aim at solving, directly or using least squares, a matrix linear equation in which signal or its autocorrelation function samples are used. The Prony, Steiglitz-McBride, Kumaresan-Tufts, Total Least Squares, Matrix Pencil, Yule-Walker and Pisarenko methods are taken into account. Finally, the interpolated discrete Fourier transform is presented with examples of Bertocco, Yoshida, and Agrež algorithms. The Matlab codes of all the discussed methods are given. The second part of the paper presents simulation results, compared with the Cramér-Rao lower bound and commented. All tested methods are compared with respect to their accuracy (systematic errors), noise robustness, required signal length, and computational complexity.
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Abstract

In this paper it is shown that M class PMU (Phasor Measurement Unit) reference model for phasor estimation recommended by the IEEE Standard C37.118.1 with the Amendment 1 is not compliant with the Standard. The reference filter preserves only the limits for TVE (total vector error), and exceeds FE (frequency error) and RFE (rate of frequency error) limits. As a remedy we propose new filters for phasor estimation for M class PMU that are fully compliant with the Standard requirements. The proposed filters are designed: 1) by the window method; 2) as flat-top windows; or as 3) optimal min-max filters. The results for all Standard compliance tests are presented, confirming good performance of the proposed filters. The proposed filters are fixed at the nominal frequency, i.e. frequency tracking and adaptive filter tuning are not required, therefore they are well suited for application in lowcost popular PMUs.
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Abstract

Introduction: The prolongation of the life of men results in the growing number of people suffering from benign prostatic hyperplasia (BPH). In 2010, BPH concerned more than 200 million men in the whole world, which at that time made up 6% of the population of men at large. Currently, the population of men in the world amounts about three billion six hundred million. The modern surgical treatment of BPH consists of minimally invasive techniques, including laser systems. Aim: Evaluation of the eff ectiveness of photoselective vaporization of the prostate (PVP) on the basis of subjective parameters assessed by patients using IPSS and QoL questionnaires as well as objective parameters obtained from results of urodynamic tests. Material and Methods: Between 2012 and 2015, 120 patients with benign prostatic hyperplasia were included in the study and underwent PVP. Finally, 77 patients were included in the study. In all patients, IPSS and QoL sheets were carried out 1, 6 and 12 months, and urodynamic tests 12 months after the surgical treatment. Results: The statistically signifi cant change in the value of each parameter assessed: decrease in the IPSS, QoL, PVR, Pmax, Pop, the degree of obstruction according to Schäfer and ICS nomogram, and an increase in the values of Qmax and Qave. Conclusions: Photoselective vaporization of the prostate is an eff ective method of therapy in patients with benign prostatic hyperplasia.
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Abstract

Recently, a new class of ceramic foams with porosity levels up to 90% has been developed as a result of the association of the gelcasting process and aeration of the ceramic suspension. This paper presents and discusses original results advertising sound absorbing capabilities of such foams. The authors man- ufactured three types of alumina foams in order to investigate three porosity levels, namely: 72, 88, and 90%. The microstructure of foams was examined and typical dimensions and average sizes of cells (pores) and cell-linking windows were found for each porosity case. Then, the acoustic absorption coefficient was measured in a wide frequency range for several samples of various thickness cut out from the foams. The results were discussed and compared with the acoustic absorption of typical polyurethane foams proving that the alumina foams with high porosity of 88-90% have excellent sound absorbing properties competitive with the quality of sound absorbing PU foams of higher porosity.
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