Wyniki wyszukiwania - BazTech

1

Dwuwymiarowa analiza korelacyjna

Czarnecki Mirosław Antoni

Wiadomości Chemiczne

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2023

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[Z] 77, 7-8

775--800

EN

This review provides fundamental information on theoretical and practical aspects of two-dimensional correlation spectroscopy (2DCOS). At first, is shown a brief development of this method since its introduction by Isao Noda in 1986. In the next part is explained the general idea of 2DCOS, and details of determination of the synchronous and asynchronous spectra from the experimental data. Next section includes comprehensive description of the properties and the rules for interpretation of the 2D correlation spectra. The most common problems with interpretation of 2DCOS spectra, and the ways of improving results of correlation analysis by a proper data pre-treatment are widely discussed. In addition, some of the most important modifications of this method like moving-window analysis and PCMW2D are described. Finally, the usefulness of the power spectra is presented. It has been shown that 2D correlation analysis is a versatile and powerful tool for data analysis and provides information not readily accessible from the original data set.

2

Comparison of the efficiency of time and frequency domain descriptors for the classification of selected wind instruments

Tyburek Krzysztof, Namli Ömer Bora

Studia i Materiały Informatyki Stosowanej

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2022

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T. 14, nr 3

13--19

EN

By analyzing the physical features of the time domain and the frequency domainof the audio signal, it is possible to determine its source and use appropriate algorithms to automatically classify of it. The issue of sound indexing deals with the analysis ofdifferent classes and sources -including signals from musical instruments. By calculating the values of descriptors and classifying them, we obtain information about the type of instrument and its structure -most often the material from which it was made. During the conducted research, it turned out that a different composition of the feature vector is implemented to describe brass instruments and a different one for wooden instruments. In this case, the key feature may be harmonic highs in the frequency domain. The conducted experiments concern an attempt to parameterize wind instruments (aerophones) in order to compare the classification effectiveness of time and spectral descriptors. Sounds from a tube, a flute and a soprano saxophone were used for research. The sample population for each instrument was 21.

PL

Analizując fizyczne cechy domeny czasu i domeny częstotliwości sygnału audio można okreslić jego źródło i przy pomocy własciwych algorytmów dokonac jego automatycznej klasyfikacji. Kwestia indeksacji dźwięku dotyczy analizy różnych klas i źródeł –także sygnałów wywodzących się z instrumentów muzycznych. Obliczając wartości deskryptorów i dokonując ich klasyfikacji uzyskujemy informację o typie instrumentu oraz jego budowie -najczęściej materiału, z którego zostal wykonany. Podczas prowadzonych badań okazało się, że różna kompozycja wektora cech jest implementowana do opisu instrumentów blaszanych oraz inna dla instrumentów drewnianych. W tym przypadku cechą kluczową mogą być składowe wyże harmoniczne w postaci częstotliwościowej dźwieku. Przeprowadzone eksperymenty dotyczą próby parametryzacji instrumentów dętych (aerofonów) w celu porównania skuteczności klasyfikacyjnej deskryptorów czasowych i widmowych. Do badań przeznaczono dźwieki pochodzace z tuby, fletu oraz saksofonu sopranowego. Populacja próbek dla każdego instrumentu wynosiła 21.

3

Detection of SSVEP based on empirical mode decomposition and power spectrum peaks analysis

Antelis Javier M., Rivera Camilo A., Galvis Eduard, Ruiz-Olaya Andres F.

Biocybernetics and Biomedical Engineering

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2020

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Vol. 40, no. 3

1010--1021

EN

Steady-state visual evoked potential (SSVEP) based brain–computer interfaces have been widely studied because these systems have potential to restore capabilities of communication and control of disable people. Identifying target frequency using SSVEP signals is still a great challenge due to the poor signal-to-noise ratio of these signals. Commonly, this task is carried out with detection algorithms such as bank of frequency-selective filters and canonical correlation analysis. This work proposes a novel method for the detection of SSVEP that combines the empirical mode decomposition (EMD) and a power spectral peak analysis (PSPA). The proposed EMD+PSPA method was evaluated with two EEG datasets, and was compared with the widely used FB and CCA. The first dataset is freely available and consists of three flickering light sources; the second dataset was constructed and consists of six flickering light sources. The results showed that proposed method was able to detect SSVEP with high accuracy (93.67 ± 9.97 and 78.19 ± 23.20 for the two datasets). Furthermore, the detection accuracy results achieved with the first dataset showed that EMD+PSPA provided the highest detection accuracy (DA) in the largest number of participants (three out of five), and that the average DA across all participant was 93.67 ± 9.97 which is 7% and 4% more than the average DA achieved with FB and CCA, respectively.

4

Vibration model applied in failure mode detection of shock absorbers

Słoniewski J.

Modelowanie Inżynierskie

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2018

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T. 38, nr 69

68--75

EN

The aim of this paper is to demonstrate a simulation model of an end-of-line shock absorber quality testing process, based on the rod-assembly acceleration measurements and with the use of a production tester equipped with a pneumatic excitation system. The proposed method applies a nonparametric power spectrum model, which represents a vibration pattern of a shock absorber excited with the use of a pneumatic actuator. The simulation results are shown in the paper along with the discussion ionr how to achieve the required failure mode detection performance. The paper provides numerical and experimental case studies to show the application scope of the proposed end-of-line shock absorber quality testing method and its performance.

PL

W artykule przedstawiono model symulacyjny procesu kontroli jakości amortyzatora przez pomiar przyspieszenia drgań zespołu goleni amortyzatora w trakcie wymuszenia realizowanego pneumatycznie na urządzeniu przemysłowym. Metoda wykorzystuje nieparametryczny model bazujący na widmowym rozkłdzie gęstości mocy, przedstawiającym charakterystykę drganiową badanego amortyzatora w trakcie wymuszenia realizowanego za pomocą siłownika pneumatycznego. W artykule przedstawiono wyniki symulacji. W dyskusji przedstawiono możliwości detekcji uszkodzeń. Artykuł przedstawia numeryczną i eksperymentalną analizę przypadku pokazując zakres stosowalności metody w procesie kontroli jakości oraz jej praktyczne zastosowanie.

5

Power spectrum analysis for determination of the number of Vertical Axis Wind Turbine blades

Anweiler S., Fedak W., Gancarski W., Ulbrich R.

Journal of Mechanical and Energy Engineering

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2017

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Vol. 1, No 2

153--161

EN

Technology of wind exploitation has been applied widely all over the world and has already reached the level in which manufacturers want to maximize the yield with the minimum investment outlays. The main objective of this paper is the determination of the optimal number of blades in the Cup-Bladed Vertical Axis Wind Turbine. Optimizing the size of the Vertical Axis Wind Turbine allow the reduction of costs and increase the output. The target is the maximum power of the rotor. The optimum number of Vertical Axis Wind Turbine blades evaluation is based on analysis of a single blade simulation and its superposition for the whole rotor. The simulation of working blade was done in MatLab environment. Power spectrum graphs were prepared and compared throughout superposition of individual blades in the Vertical Axis Wind Turbine rotor. Some wind tunnel measurements of the hydrodynamic force according to pitch angle of the blade are also shown. The major result of this research is the Vertical Axis Wind Turbine kmax ratiopower characteristic. On the basis of the analysis of the power spectra, optimum number of the blades was specified for the analysed rotor. Power spectrum analysis of wind turbine enabled the specification of the optimal number of blades, and can be used regarding investment outlays and power output of the Vertical Axis Wind Turbine.

6

Accurate Establishment of Error Models for the Satellite Gravity Gradiometry Recovery and Requirements Analysis for the Future GOCE Follow-On Mission

Zheng W., Wang Z., Ding Y., Li Z.

Acta Geophysica

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2016

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Vol. 64, no. 3

732--754

EN

Firstly, the new single and combined error models applied to estimate the cumulative geoid height error are efficiently produced by the dominating error sources consisting of the gravity gradient of the satellite-equipped gradiometer and the orbital position of the space-borne GPS/GLONASS receiver using the power spectral principle. At degree 250, the cumulative geoid height error is 1.769 × 10–1 m based on the new combined error model, which preferably accords with a recovery accuracy of 1.760 × 10–1 m from the GOCE-only Earth gravity field model GO_CONS_GCF_2_TIM_R2 released in Germany. Therefore, the new combined error model of the cumulative geoid height is correct and reliable in this study. Secondly, the requirements analysis for the future GOCE Follow-On satellite system is carried out in respect of the preferred design of the matching measurement accuracy of key payloads comprising the gravity gradient and orbital position and the optimal selection of the orbital altitude of the satellite. We recommend the gravity gradient with an accuracy of 10–13-10–15 /s2 , the orbital position with a precision of 1-0.1 cm and the orbital altitude of 200-250 km in the future GOCE Follow-On mission.

7

Influence of junction temperature on the spectral power distribution of Light Emitting Diodes

Budzyński Ł

Challenges of Modern Technology

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2015

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Vol. 6, no. 4

3--7

EN

This article describes electrical method for measuring junction temperature of high power LEDs. Measurement system consisting of a temperature controller and a thermostatic chamber was designed and constructed. A number of studies of LEDs in a typical thermal conditions that exist in luminaries were performed. Basing on these results, influence of junction temperature on luminous flux and spectral power distribution of LED was determined. Obtained results allow to optimize the construction of LED lighting fixtures, in the ambient temperature range from 0°C to 100°C, especially in the aspect of improving the photometric properties of the luminaire.

8

Model sygnałów sejsmometrycznych zarejestrowanych na terenach górniczych

Marcak H.

WUG : bezpieczeństwo pracy i ochrona środowiska w górnictwie

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2005

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nr 6

33-35

PL

Widmo mocy, które jest estymacją periodycznych własności zapisów sejsmometrycznych zawiera również informację o strukturze sejsmicznych sygnałów pomiarowych. W pracy zaproponowano model sygnału, który może być opisany dwoma parametrami. Pokazano, że można estymować te parametry ze współczynników wielomianu stopnia drugiego aproksymującego niskoczęstotliwościową część widma mocy, obliczonego z wyników pomiarów przyspieszenia drgań cząstek gruntu. Interpretacja wyników rejestracji przyspieszenia, wywołanego wstrząsem górniczym powstałym w Lubińskim Zagłębiu Miedziowym, pozwoliła pokazać znaczenie tak estymowanych parametrów w ocenie ryzyka powstania uszkodzeń w budowlach na skutek drgań wywołanych wstrząsami górniczymi.

EN

Power spectrum, which is an estimation of periodic properties of seismic signals, includes also information related to structure of seismic records. The model of signal shownin the paper, can be described with two parameters, estimated from first two coefficients of second order polynomial, approximating low-frequency part of power spectrum, calculated from recorded acceleration of ground particles vibrations. Interpretations of recorded acceleration of ground particles vibrations in Lubin Copper Basin, allowed to show efficiency of estimated parameters, in assessment of the risk of destructions appearance in buildings in result of seismic vibrations, caused by mining shocks.

9

Dynamic load power distribution in mechanical systems.

Kaźmierczak H.

Zagadnienia Eksploatacji Maszyn

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2001

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Vol. 36, nr 3

127-141

EN

The analytical model of the mechanical system described allows building the spatial model of the dynamic load power distribution in the multi-input-multi-output system. The model allows determining the dissipation power distribution in the individual subsystems and transmitted powers from every subsystem, where the external excitation force has been applied, onto remaining subsystems. The most important is the possibility of determination of dissipated powers in every subsystem. It becomes the basis for construction of holistic models of dynamic loads and in consequence of diagnostic models of machines.

PL

Artykuł zawiera opis holistycznego modelu rozpływu mocy obciążeń w systemach mechanicznych, który uwzględnia ewolucyjny proces destrukcji elementów systemu. Z pomocą modelu rozpływu mocy obciążeń można badać obiekty w pięciowymiarowej czasoprzestrzeni, charakteryzowanej jako przestrzeń procesów fizycznych, w której oprócz trzech składowych przestrzennych każdego punktu w modelu dyskretnym systemu występuje czas dynamiczny procesów drganiowych oraz czas ewolucji stanu dynamicznego systemu (czas ewolucji). Ewolucyjny proces destrukcji technicznej obiektu w funkcji czasu eksploatacji odzwierciedla się poprzez wzrost odpowiednich elementów macierzy rozpływu mocy (pulsacja mocy obciążeń).