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1

Experimental study of nano-composite materials on vibration responses

Mobark Haidal Faisal Helal, Fahdel Essam Z., Hussein Mustafa Turki, Mohamad Barhm

Diagnostyka

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2023

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Vol. 24, No. 3

art. no. 2023312

EN

This paper present of experimental and numerical study of nano Al2O3 cantilever beam for forced vibration, addressing an unexplored area in the existing literature. The proposed nano composite cantilever beam is modeled with hole and crack. The study is based on history loading calculation and composite morphology a global parameter, the transverse crack in nano composite cantilever beam was studied and analyzed experimentally using a four-channel dynamic signal acquisition (NI 9234) module for making high-accuracy measurements and its ideal for vibration applications. The relationship between the dispersion and interaction of the alumina nanoparticles within the cantilever beam and morphology of the solid, hole and crack composite has been identified. Furthermore, the influence of particles Al2O3 at different concentrations (0%, 1%, 3% and 4%) have been studied respectively. Supporting results proved that the crack and hole depth increases with increases of history loading. Nanoparticles dispersed within the specimen can increase energy dissipation during vibration, leading to improved damping characteristics. For future work, it is recommended to utilize statistical frequency domain input, such as Power Spectral Density (PSD), for assessing the structural response instead of employing time history loading.

2

Rapid design exploration of low pass highly efficient single loop single bit sigma delta (ΣΔ) modulators

Krishna S. Vamsee, Reddy P. Sudhakara, Reddy S. Chandra Mohan

Computer Assisted Methods in Engineering and Science

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2023

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Vol. 30, no. 1

27--39

EN

A rapid design and verification of sigma delta modulators are presented at the systemlevel with high accuracy and computational efficiency. Sigma delta analog to digital converters showcased an excellent choice for low bandwidth applications from near DC tohigh bandwidth standard 5G applications. The conceptualization of the graphical userinterface (GUI) in the efficient selection of integrator weights has been proposed, whichsolves various tradeoffs between various abstraction levels. The sigma delta modulator of the 5th order is designed and simulated using the proposed design methodology of calculating integrator weights for targeted specifications. The efficiency of design explorationand optimum selection of integrator coefficients has been investigated on single loop architectures. Power and performance of the selected modulator has been verified in the timedomain behavioral simulation. The discrete time circuit technique has been adopted fordesign of distributed feedback, feed forward architectures and comparison of performancemetrics done between selected architectures. A huge design space is computed for the bestdesign parameters that offers ultra-low power and high performance. The proposed virtual instruments supported the methodology for designing delta sigma modulators at thesystem level achieving SNDR of 122 dB over a bandwidth of 5 kHz at a clock frequencyof 1 MHz.

3

A machine learning approach to epileptic seizure prediction using Electroencephalogram (EEG) Signal

Savadkoohi Marzieh, Oladunni Timothy, Thompson Lara

Biocybernetics and Biomedical Engineering

|

2020

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Vol. 40, no. 3

1328--1341

EN

This study investigates the properties of the brain electrical activity from different recording regions and physiological states for seizure detection. Neurophysiologists will find the work useful in the timely and accurate detection of epileptic seizures of their patients. We explored the best way to detect meaningful patterns from an epileptic Electroencephalogram (EEG). Signals used in this work are 23.6 s segments of 100 single channel surface EEG recordings collected with the sampling rate of 173.61 Hz. The recorded signals are from five healthy volunteers with eyes closed and eyes open, and intracranial EEG recordings from five epilepsy patients during the seizure-free interval as well as epileptic seizures. Feature engineering was done using; i) feature extraction of each EEG wave in time, frequency and time-frequency domains via Butterworth filter, Fourier Transform and Wavelet Transform respectively and, ii) feature selection with T-test, and Sequential Forward Floating Selection (SFFS). SVM and KNN learning algorithms were applied to classify preprocessed EEG signal. Performance comparison was based on Accuracy, Sensitivity and Specificity. Our experiments showed that SVM has a slight edge over KNN.

4

Minimalizacja wahań napięcia źródła stratnego w stanie nieustalonym - rozwiązanie w dziedzinie czasowej

Siwczyński M., Drwal A., Żaba S.

Przegląd Elektrotechniczny

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2017

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R. 93, nr 9

54--57

PL

W artykule rozwiązano zadanie minimalizacji zmian sygnału napięcia wewnątrz stratnego źródła energii elektrycznej w stanie nieustalonym (zmodulowanym) przy użyciu rachunku operatorowego. Określono sposób deformacji operatorów rozwiązujących poprzez tzw. poprawkę modulacyjną oraz wyznaczono ich rozkłady czasowe. Przedstawiono przykład obliczeniowy z siłą elektromotoryczną e(t,t’), okresową względem zmiennej t, zmodulowaną według czasu t’, zawierającą operator impedancji wewnętrznej typu RL.

EN

In the paper was solved the task of minimizing changes the voltage signal inside the lossy electrical power source in a transient state (modulated) by using the operational calculus. A deformation of the solving operators by the so-called modulation amendment was described and their time distributions was determined. The calculation example with the electromotive force e(t,t’), periodical respect to the variable t and modulated by time t', which contains an internal impedance operator type RL was presented.

5

Minimalizacja wahań napięcia źródła stratnego – rozwiązanie zagadnienia w dziedzinie czasu

Siwczyński M., Drwal A.

Przegląd Elektrotechniczny

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2017

|

R. 93, nr 6

76--78

PL

W artykule opisano proces minimalizacji normy kwadratowej sygnału napięcia wewnątrz stratnego źródła energii elektrycznej używając do tego celu dziedziny czasowej zamiast częściej stosowanej dziedziny widmowej. Wyniki wyprowadzono za pomocą metod analizy funkcjonalnej, by w szczególnym przypadku przejść do sygnałów i operatorów okresowych opisujących stan ustalony źródła energii. Zwrócono uwagę na fakt, że podejście czasowe jest szczególnie przydatne w przypadkach szybkozmiennych sygnałów zajmujących stosunkowo szerokie pasmo częstotliwości.

EN

This article describes the process of minimize the squared norm of a voltage signal within a lossy electrical power source in the time domain instead of the often used spectral domain. The results obtained by functional analysis, in the particular case are transferred to the periodic signals and operators that describe the steady-state power source. It was noted that the time approach is particularly useful in cases of rapidly changing signals occupying a relatively wide frequency range.

6

Pomiar charakterystyki anteny dookólnej z zastosowaniem oknowania w dziedzinie czasu

Piasecki P.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

|

2016

|

nr 6

269—272, CD

PL

W niniejszym artykule opisano metodę pomiarową charakterystyki promieniowania anteny dookólnej z zastosowaniem przetwarzania danych w dziedzinie czasu. Rozważono niezbędne założenia, które muszą zostać spełnione w celu poprawności uzyskania wyników pomiarowych z zastosowaniem oknowania w dziedzinie czasu. Wykonano odpowiednie obliczenia pozwalające określić poszczególne odbicia widoczne w dziedzinie czasu. Ponadto wykonano pomiary badanej anteny w komorze bezodbiciowej oraz pomieszczeniu biurowym. Dokonano analizy porównawczej uzyskanych wyników, co pozwoliło określić poprawność przedstawionej metody pomiarowej.

EN

In this paper the ability to measure a radiation pattern of antennas, especially omnidirectional antennas, without necessity of using an anechoic chamber is presented. For this purpose, the time domain technique is used and the influence of this solution on an antenna radiation pattern is shown. Also some theoretical dependencies are introduced. Moreover, difference between radiation patterns obtained in an anechoic chamber and office room with using postprocessing in the time domain are presented.

7

Time and frequency domain analysis of partial discharges using electrical method

Kunicki M., Cichoń A.

Measurement Automation Monitoring

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2016

|

Vol. 62, No. 2

72--77

EN

Partial discharge (PD) measurement results with particular consideration of time domain and frequency domain analysis of pulses generated by PD model sources are presented in the paper. Three different PD generation model sources are selected for the research: surface type, point to point and multi-point to plate. All measurements are proceeded under laboratory conditions using electrical method of a PD detection, according to the IEC60270 standard. Various amplitude and power density spectrum descriptors are proposed, as well as PD source type identification abilities on grounds of the selected descriptors are considerated. Electrical power transformers on-line PD detection and evaluation systems improvement and development are the main purpose of the presented research. Laboratory experiment results gives a solid base for further research focused on verification of the proposed methodology on a real life apparatus.

8

Combination of criteria for controller parameterisation in the time and frequency domain by simulation-based optimisation

Hipp K., Uhrig M., Hellmich A., Schlegel H., Neugebauer R.

Journal of Machine Engineering

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2016

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Vol. 16, No. 4

70--81

EN

The position controller cascade is widely used in standard industrial controllers. Its controller parameterisation is commonly performed by either applying basic tuning rules or by carrying out not comprehensible design automatisms.In this paper an alternative approach to parameterise the cascade in one step is presented. It bases on established methods within the field of optimisation research specifically the so-called simulation-based optimisation (SBO), which can also handle non-linear models and various constrains. Own research showed, that criteria in the time domain as well as in the frequency domain are suitable optimisation criteria. However, both types have individual advantages and disadvantages. Therefore, in this research, selected representatives from both types were combined as new multi-objective optimisation criteria and investigated according to their performance. Investigations were performed for a test rig model (third order transfer function plus dead time and friction).The paper presents fundamentals of the SBO and a description of the optimisation criteria, obtained results as well as their verification on the test rig. Also, the derived controller parameterisations are compared to the integrated tuning automatism.

9

Analytical time-domain model for tool point dynamics in turning

Berglind L., Ziegert J.

Journal of Machine Engineering

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2014

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Vol. 14, No. 4

75--94

EN

An analytical time domain solution is developed to model the dynamic response of a tool during a simple turning operation. The time domain solution developed in this paper relies on the superposition principal under the linear assumption to construct the time response of single mode, single degree of freedom cutting tool. The results from the analytical solution are compared with those generated using numerical time domain simulations and it is found that the two solutions converge as the time step used in the numerical simulation decreases.

10

New Textiles Designed for Anti-Radar Camouflage

Redlich G., Obersztyn E., Olejnik M, Fortuniak K, Bartczak A, Szugajew L, Jarzemski J.

Fibres & Textiles in Eastern Europe

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2014

|

Vol. 22, no. 1 (103)

34--42

EN

This paper presents newly designed textiles (woven and knitted fabrics) for camouflage against radar, with a particular emphasis on the conductive yarns applied and their distribution throughout the structure of the goods. The levels obtained for the coefficients of re- flection and the transmission of electromagnetic waves have been discussed for woven and knitted fabrics, both raw and those subjected to finishing treatment. These parameters were determined using two methods: waveguide applicators and in the space in a semi-anechoic chamber within the time domain. The issues this publication covers are an integral part of research on developing textile products featuring a broad spectrum of masking, i.e. within the visible (VIS), near infrared (IR), and that of the subject - the anti-radar band. The first two types of camouflage were discussed in an earlier publication entitled “Assessment and Verification of the Functionality of New, Multi-component, Camouflage Materials” (Fibres & Textiles in Eastern Europe 2013; 21, 5(101): 73-79).

PL

W artykule przedstawiono nowoopracowane konstrukcje włókiennicze (tkaniny, dzianiny) maskujące przeciwradiolokacyjnie, ze szczególnym uwzględnieniem zastosowanych przędz konduktywnych oraz ich rozkładu w strukturze wyrobów. Omówiono poziomy uzyskanych wartości współczynników odbicia i transmisji fal elektromagnetycznych, zarówno dla tkanin i dzianin surowych, jak i poddanych obróbce wykańczalniczej. Parametry te były wyznaczane z zastosowaniem dwóch metod tj. z wykorzystaniem aplikatorów falowodowych oraz w przestrzeni w komorze bezechowej w domenie czasu. Zagadnienia ujęte w niniejszej publikacji stanowią integralną część badań nad opracowaniem wyrobów włókienniczych o szerokim spektrum maskowania, tj. w zakresie widzialnym (VIS), bliskiej podczerwieni (IR) oraz przedmiotowym czyli przeciwradiolokacyjnym. Dwa pierwsze rodzaje maskowania zostały przedstawione we wcześniejszej publikacji pt. „Assessment and verification of functionality of new, multi-component, masking materials ”(Fibres & Textiles in Eastern Europe 2013; 21, 5(101): 73-79).

11

The wave transformer – analysis and application of time digital filters and the integral-derivative operators of ½ order

Siwczyński M., Drwal A., Żaba S.

Archives of Electrical Engineering

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2013

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Vol. 62, nr 3

497--504

EN

In this paper the way of modeling phenomena occurring during the voltage and current waves passing through a point connection of two lines, with different wave impedance operators, is presented. This connection point is called „the wave transformer”. The analyzes and the resulting formulas concern not the frequency domain, but the time domain. The appropriate transition matrices of waves through the wave transformer are defined. This matrices are the convolution integral-derivative operators of fractional order (the digital filters). For a lossless line the wave transition matrices through the wave transformer become number type instead of operator type. All matrix multiplications occurring in the formulas should be understood in convolution way.

12

L1-impulses method as an alternative method of harmonic components in the power theory of discrete time systems

Siwczyński M., Drwal A., Żaba S.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2012

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Vol. 60, nr 1

111-117

EN

The article presents the basic mathematical theory of the operational calculus of the L1-impulses in the discrete time domain. It presents the isomorphism between the rational function set of complex variable and the exponential L1 impulses set of positive and negative time domain. The paper shows how for any factorization of the rational function consisting of casual and noncasual parts can be directly obtained the N – periodic version of the original signal using for the individual components of the L1 impulses N – copy formula. It is done by the distribution of the convolution – the type admitance operator Y of electrical circuit to the two commutative convolution operators and on this basis is obtained the distribution of electrical circuit current to two components: the active current and the reactive current in the discrete time domain using the cyclic convolutions. The distribution of current in the time domain for signals significantly different from the sinusoidal is much more favorable than the distribution in the frequency domain.

13

Rozkład admitancji odbiornika na składową czynną i bierną w dziedzinie czasu

Siwczyński M., Drwala A., Żaba S.

Wiadomości Elektrotechniczne

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2011

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R. 79, nr 10

36-39

PL

Przedstawiono nowy sposób rozkładu admitancji odbiornika na składową czynną i bierną w dziedzinie czasu. Opisany rozkład z dziedziny czasu można uzyskać dla transmisji z biegunami rzeczywistymi, zespolonymi i urojonymi. Rozkład admitancji indukuje rozkład prądu na składową czynną i bierną w dziedzinie czasu przy użyciu splotów cyklicznych.

EN

The paper presents a new method of decomposition of load admittance into active and reactive components in the time domain. Described decomposition in the time domain may be obtained for transmission with real, complex and imaginary poles. Decomposition of admittance implies decomposition of current into real and reactive components in time domain using cyclic convolutions.

14

Rozkłady: prąd aktywny, prąd rozrzutu, prąd bierny w dziedzinie czasu - podstawy matematyczne, metoda operatorowa

Siwczyński M.

Przegląd Elektrotechniczny

|

2011

|

R. 87, nr 4

134-141

PL

W artykule podano podstawy matematyczne rachunku operatorowego L-impulsów i sygnałów okresowych. Takie podejście umożliwia identyfikację zjawisk energetycznych w obwodach elektrycznych bezpośrednio w dziedzinie czasu. W szczególności dotyczy to kwestii rozkładu prądu odbiornika na składowe fizyczne.

EN

In the article the mathematical theory of the operational calculus of the L- impulses and periodical signals are presented. Was shown that this approach makes identification of power phenomena in electrical circuit in the time domain: the distribution of current to physical components in special case.

15

Rozkłady: prąd aktywny, prąd rozrzutu, prąd bierny w dziedzinie czasu - podstawy matematyczne, metoda splotowa

Siwczyński M.

Przegląd Elektrotechniczny

|

2011

|

R. 87, nr 3

254-257

PL

W artykule podano podstawy matematyczne rachunku operatorowego L 1-impulsów i sygnałów okresowych z zastosowaniem splotu cyklicznego. Takie podejście umożliwia identyfikację zjawisk energetycznych w obwodach elektrycznych bezpośrednio w dziedzinie czasu. W szczególności dotyczy to kwestii rozkładu prądu odbiornika na składowe fizyczne.

EN

In the article the mathematical theory ot the operational calculus of the L 1-impulses and periodical signals are presented. The cyclic convolution were used. Was shown that this approach makes identification of power phenomena in electrical circuit in the time domain: the distribution of current to physical components in special case.

16

Rozkłady: prąd aktywny, prąd rozrzutu, prąd bierny w dziedzinie czasu dyskretnego

Siwczyński M.

Przegląd Elektrotechniczny

|

2010

|

R. 86, nr 7

338-341

PL

W artykule pokazano, że dziedzina czasu dyskretnego ujawnia wszystkie zjawiska energetyczne w obwodach elektrycznych, tj. rozkład prądu obwodu na prąd aktywny, prąd bierny i prąd rozrzutu.

EN

In the article was shown that the discrete-time domain approach makes identification of power phenomena in electrical circuit: the current distribution to physical components: active current, reactive current, scattered current.

17

Rozkłady: prąd aktywny, prąd rozrzutu, prąd bierny w dziedzinie czasu – obwody jednofazowe

Siwczyński M.

Przegląd Elektrotechniczny

|

2010

|

R. 86, nr 6

196-201

PL

W artykule tym pokazano, że zarówno dziedzina częstotliwościowa jak i czasowa ujawnia wszystkie zjawiska energetyczne w obwodach elektrycznych, tj. rozkład prądu obwodu na prąd aktywny, prąd bierny i prąd rozrzutu.

EN

In the article was shown that the frequency domain and the time domain approach too makes identification of power phenomena in electrical circuit: the current distribution to physical components: active current, reactive current, scattered current.

18

Rozkłady: prąd aktywny, prąd rozrzutu, prąd bierny, prąd niesymetrii w dziedzinie czasu - obwody trójfazowe

Siwczyński M.

Przegląd Elektrotechniczny

|

2010

|

R. 86, nr 8

210-213

PL

W artykule pokazano, że dziedzina czasu ujawnia wszystkie zjawiska energetyczne także w obwodach trójfazowych, tj. rozkład prądu odbiornika na prąd aktywny, prąd bierny i prąd rozrzutu i prąd niesymetrii.

EN

In the article was shown that the time domain approach makes identification of power phenomena in three phase electrical circuits: the current distribution to physical components: active current, reactive current, scattered current and asymmetrical current.

19

GMAW process stability evaluation through acoustic emission by time and frequency domain analysis

Huanca Cayo E., Absi Alfaro S. C.

Journal of Achievements in Materials and Manufacturing Engineering

|

2009

|

Vol. 34, nr 2

157-164

EN

Purpose: In the present work was made the comparative analysis in time domain and frequency domain to the acoustical pressure generate by the electric arc to determinate which of the two analysis methods is better to evaluates the stability in GMAW process. Design/methodology/approach: Welds had been made with the parameters adjusted to get the highest stability. In these conditions, were simulated instabilities that had been generated by the grease presence in the weld trajectory. In both experimental groups was acquired the acoustical pressure signal produced by electric arc to made analysis based in time domain and frequency domain. Findings: After this comparative study we conclude that the acoustical evaluation of the stability on the GMAW process presents more clarity for the analysis based in the time domain that the frequency domain. Research limitations/implications: In the gotten results, the time domain analysis method could represent adequately the stability and the instability of the process. The stability characterizes for the continuity and minim variation of the statistical parameters, but in the presence of instabilities, these parameters present chaotic changes. In the frequency domain method the variations are imperceptible for steady and unstable regions, but it presents little definite variations in the amplitude of determined bands of frequencies. Originality/value: The stability evaluation in welding is crucial because it is responsible in the weld quality. The non contact methods as the acoustical method have a potentiality extraordinary to monitoring and detect instabilities in welding. The acoustical sensing has the capacity to make an on-line monitoring of the weld process.

20

Methods for vehicle vibration analysis in time domain

Gerlici J., Lack T.

Prace Naukowe Politechniki Warszawskiej. Transport

|

2007

|

z. 63

71-81

EN

Simulation computations, mainly supported by computational technique, are used for the vehicle vibration analysis. The procedures and methods are used for the forced oscillation of a mechanical system solution. The vehicle model has been created for this purpose. A kinematical excitation and accelerations act on the model. We can search a response from a harmonic excitation via the solution in a complex, or a real form, or we can analyse the vehicle vibration in the time domain. It is useful to use the HHT method [3] as a special variant of the Newmark method. The procedures may be performed with the DELTA programme [2].

PL

Obliczenia symulacyjne, wspomagane głownie przez technikę obliczeniową, wykorzystano do analizy drgań pojazdu. Procedury i metody wykorzystuje się do rozwiązania drgań wymuszonych układu mechanicznego. W tym celu zbudowano model pojazdu. Na model oddziaływują wymuszenia kinematyczne i przyspieszenia. Odpowiedzi na wymuszenia harmoniczne można poszukać poprzez rozwiązania w postaci zespolonej lub rzeczywistej lub można analizować drgania pojazdu w dziedzinie czasu. Użyteczne jest wykorzystanie metody HHT [3] jako szczególnej odmiany metody Newmarka. Procedury można poprowadzić wykorzystując program DELTA [2].