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Wyniki wyszukiwania dla: DISCRETE FOURIER TRANSFORM
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Fourier transform symmetry and invariance for neurocontrol of NARMA models
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Using phase of short-term Fourier transform for evaluation of spectrogram performance
PublikacjaThe concept of spectrogram performance evaluation which exploits information on phase of short-term Fourier transform (STFT) is presented. A spectrograph which is time-frequency analyzing tool, is compared to a filter bank that demultiplexes a signal. Local group delay (LGD) and channelized instantaneous frequency (CIF) is obtained for each filtered component signal. In presented solution the performance is evaluated using so-called...
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High Performance Liquid chromatography - Fourier Transform Infrared Spectroscopy Coupling: A Comprehensive Review
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Anharmonic Infrared Spectroscopy through the Fourier Transform of Time Correlation Function Formalism in ONETEP
PublikacjaDensity functional theory molecular dynamics (DFT-MD) provides an efficient framework for accurately computing several types of spectra. The major benefit of DFTMD approaches lies in the ability to naturally take into account the effects of temperature and anharmonicity, without having to introduce any ad hoc or a posteriori corrections. Consequently, computational spectroscopy based on DFT-MD approaches plays a pivotal role in...
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Application of Discrete Wavelet Transform in the Analysis of Nonlinear Chemical System
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Application of discrete wavelet transform in the analysis of nonlinear chemical system
PublikacjaW pracy omówiono zastosowanie dyskretnej transformacji falkowej do analizy oscylacji chemicznych. Szczegółowej analizie falkowej poddano rejestry potencjałowe reakcji Biełousowa-Żabotyńskiego. Pozwoliło to zlokalizować trudne do zidentyfikowania przejścia pomiędzy kolejnymi etapami tej złożonej reakcji.
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Application of the Fractional Fourier Transform for dispersion compensation in signals from a fiber-based Fabry-Perot interferometer
PublikacjaOptical methods of measurement do not require contact of a probe and the object under study, and thus have found use in a broad range of applications such as nondestructive testing (NDT), where noninvasive measurement is crucial. Measuring the refractive index of a material can give a valuable insight into its composition. Low‑coherence radiation sources enable measurement of the sample’s properties across a wide spectrum, while...
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Fourier transform infrared spectroscopic and theoretical study of water interactions with glycine and its N-methylated derivatives
PublikacjaZbadano hydratację glicyny i jej metylowych pochodnych: N-metyloglicyny (NMG), N,N-dimetyloglicyny (DMG) i N,N,N-trimetyloglicyny (TMG) przy wykorzystaniu spektroskopii FTIR, z zastosowaniem cząsteczki HDO jako sondy molekularnej. Ilościowa wersja metody widm różnicowych pozwoliła na wyizolowanie widma wody zaburzonej przez substancję rozpuszczoną. Wyniki widmowe zostały skonfrontowane z obliczeniami teoretycznymi w ramach teorii...
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Application of discrete wavelet transform in seismic nonlinear analysis of soil–structure interaction problems
PublikacjaSimulation of soil-structure interaction (SSI) effects is a time-consuming and costly process. However, ignoring the influence of SSI on structural response may lead to inaccurate results, especially in the case of seismic nonlinear analysis. In this paper, wavelet transform methodology has been utilized for investigation of the seismic response of soil-structure systems. For this purpose, different storey outrigger braced buildings...
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Fast Fourier Transform detection and reduction of high-frequency errors from the results of surface topography profile measurements of honed textures
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Assessment of the structural evolution of polyimide-derived carbons obtained by phosphoric acid activation using Fourier transform infrared and Raman spectroscopy
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FDTD-Compatible Green's function based on scalar discrete Green's function and multidimensional Z-transform
PublikacjaIn this contribution, a new formulation of the discrete Green's function (DGF) is presented for the finitedifference time-domain (FDTD) grid. Recently, dyadic DGF has been derived from the impulse response of the discretized scalar wave equation (i.e., scalar DGF) with the use of the multidimensional Z-transform. Its software implementation is straightforward because only elementary functions are involved and a single function...
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In situ study of a composition of outlet gases from biogas fuelled Solid Oxide Fuel Cell performed by the Fourier Transform Infrared Spectroscopy
PublikacjaThe purpose of this study was to develop a method and software based on the Fourier Transform Infrared Spectroscopy for the in-situ, quantitative analysis of the composition of outlet gases from Solid Oxide Fuel Cell (SOFC). The calibration procedure performed at the beginning of the experiment indicated a polynomial dependence between the concentration of a calibrating gas (CO, CO2, CH4) and the corresponding integrated absorbance in...
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Vision-based parking lot occupancy evaluation system using 2D separable discrete wavelet transform
PublikacjaA simple system for rough estimation of the occupancy of an ad-hoc organized parking lot is presented. A reasonably simple microprocessor hardware with a low resolution monochrome video camera observing the parking lot from the location high above the parking surface is capable of running the proposed 2-D separable discrete wavelet transform (DWT)-based algorithm, reporting the percentage of the observed parking area occupied by...
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Fourier-transform infrared spectroscopy (FTIR) spectra of bulk boron and borophene flakes
Dane BadawczeThese data contain Fourier-transform infrared spectroscopy (FTIR) spectra of bulk boron and borophene flakes obtained during ball milling (450 rpm, 6 h, 1 g). Spectra were acquired to investigate the chemical bonds and functional groups on the surface of the pristine boron and borophene flakes.
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FTIR (Fourier-transform infrared spectroscopy) spectra of titanium dioxide coated nickel foams.
Dane BadawczeThis dataset contains FTIR spectra recorded on a JASCO 4200 spectrometer of nickel foams coated with titanium dioxide after heating at 400, 500 and 600 C and after photocatalytic process with NOx.
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Fourier transform infrared spectroscopy (FTIR) of pre- PXBS (0 h) and PXBS during the crosslinking process (24 h–288 h)
Dane BadawczeThe goal of this research was developing biodegradable and biocompatibile xylitol-based copolymers with improved mechanical properties, and investigating the change in their thermal and chemical properties withprogress of the cross-linking process. Using a raw material of natural origin such as xylitol, a prepolymer wasobtained by esterification and...
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Compressible gas density measurement by means of Fourier analysis of interferograms
PublikacjaThis paper describes a method for nonintrusive compressible gas density measurement by means of automated analysis of interferograms using FFT (Fast Fourier Transform), and its implementation using DFT (Discrete Fourier Transform), that does make this measurement technique a fairly valuable and accessible experimental method. The presented approach makes it possible to use the finite fringe setting of the interferometer, thus reducing...
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Comparative analysis of various transformation techniques for voiceless consonants modeling
PublikacjaIn this paper, a comparison of various transformation techniques, namely Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT) and Discrete Walsh Hadamard Transform (DWHT) are performed in the context of their application to voiceless consonant modeling. Speech features based on these transformation techniques are extracted. These features are mean and derivative values of cepstrum coefficients, derived from each transformation....
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Frequency response spectra applied to assess efficiency of the training techniques
PublikacjaThe purpose of the research is to assess the increase of the muscle strength and power. Movement of the human body when the moving one impacts a stationary or moving body is taken under consideration. The waveform produced by an impact is transformed into frequency domain. The acceleration record is transformed as a complex spectrum, by the use of a Discrete Fourier Transformation. In this paper the applications of the discrete...
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Parallel Implementation of the Discrete Green's Function Formulation of the FDTD Method on a Multicore Central Processing Unit
PublikacjaParallel implementation of the discrete Green's function formulation of the finite-difference time-domain (DGF-FDTD) method was developed on a multicore central processing unit. DGF-FDTD avoids computations of the electromagnetic field in free-space cells and does not require domain termination by absorbing boundary conditions. Computed DGF-FDTD solutions are compatible with the FDTD grid enabling the perfect hybridization of FDTD...
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Compressive Sensing Approach to Harmonics Detection in the Ship Electrical Network
PublikacjaThe contribution of this paper is to show the opportunities for using the compressive sensing (CS) technique for detecting harmonics in a frequency sparse signal. The signal in a ship’s electrical network, polluted by harmonic distortions, can be modeled as a superposition of a small number of sinusoids and the discrete Fourier transform (DFT) basis forms its sparse domain. According to the theory of CS, a signal may be reconstructed...
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Time-frequency analysis of acoustic signals using concentrated spectrogram
PublikacjaThe paper presents improved method of time-frequency (TF) analysis of discrete-time signals. The method involves signal's local group delay (LGD) and channelized instantaneous frequency (CIF) to purposely redistribute all Short-time Fourier transform (STFT) lines. Additionally, the energy concentration index (ECI) and some histogram-like statistics are used to evaluate readability of estimated TF distributions of the energy. Recorded...
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СИЛОВОЙ ПРЕОБРАЗОВАТЕЛЬ С АКТИВНЫМ ПОДАВЛЕНИЕМ ВЫСШИХ ГАРМОНИК ДЛЯ СИСТЕМ ЭЛЕКТРОСНАБЖЕНИЯ ЛЕТАТЕЛЬНЫХ АППАРАТОВ (Power converter with active suppression of higher harmonics for aircraft power supply systems)
PublikacjaПредставлены два алгоритма активной фильтрации для силового преобразователя с активным подавлением высших гармоник. Первый алгоритм основан на дискретном преобразовании Фурье: посредством синтезированной системы управления инвертированные измеренные высшие гармоники напряжения поступают на вход инвертора. Второй метод управления основан на алгоритме с использованием принципов самообучения, что значительно снижает потребность в...
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Fourier transforms on Cantor sets: A study in non-Diophantine arithmetic and calculus
PublikacjaFractals equipped with intrinsic arithmetic lead to a natural definition of differentiation, integration, and complex structure. Applying the formalism to the problem of a Fourier transform on fractals we show that the resulting transform has all the required basic properties. As an example we discuss a sawtooth signal on the ternary middle-third Cantor set. The formalism works also for fractals that are not self-similar.
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Model-Free Controller Tuning Based on DFT Processing: Application to Induction Motor Drives
PublikacjaIn this paper, we present a new approach based on discrete Fourier transform (DFT) analysis for controller tuning of the closed-loop system with unknown plant. The DFT analysis is used to process the closed-loop measurements collected online to derive the frequency response of an initial closed-loop system that does not provide a good performance. Based on the closed-loop frequency response data, we propose two methods for tuning PID...
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FTIR spectra and IGC chromatograms for chemically reduced graphene oxide aerogels (rGOA)
Dane BadawczeThe effect of selected synthesis parameters on reduced graphene oxide aerogels properties was investigated using Fourier-transform infrared spectroscopy and dynamic adsorption method (Inverse Gas Chromatography, IGC). Samples were synthesized by sol-gel method by reduction induced self-assembly of graphene oxide. As a reductant l-ascorbic acid was used....
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Application of time-frequency methods for analysis of dynamic silo flow
PublikacjaW artykule przedstawiono możliwość stosowania metod czasowo-częstotliwościowych w analizie dynamicznego przepływu materiału sypkiego w silosie. W pracy omówiono wyniki FT (Fourier Transform), STFT (Short Time Fourier Transform) oraz WT (Wavelet Transform)
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Influence of bio-polyols with different molecular weight on properites of PUR-PIR foams
Dane BadawczeThis work attempts to validate the possibility of replacing petrochemical polyols with previously synthesized bio-polyols and their impact on the structure and properties of rigid polyurethane-polyisocyanurate (PUR-PIR). The influence of bio-polyols addition on foam properties was investigated by mechanical testing, Fourier transform infrared spectroscopy...
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Solvation phenomena in ternary system tetramethylurea-methylacetamide-water: Insights from volumetric, compressibility and FTIR analysis
PublikacjaThe properties of the ternary systems N,N,N’,N’-tetramethylurea - N-methylacetamide - water were investigated using Fourier-transform infrared spectroscopy (FTIR), volumetric and compression measurements. Densities and sound velocities were determined in order to obtain the apparent molar volumes (VΦ) and apparent molar isentropic compressions (ΚS,Φ). These values were then extrapolated to infinite dilution. Additionally, interaction parameters...
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Wavelet Transform Analysis of Temperature Modulated Gas Sensor Response
PublikacjaThe aim of the study was to evaluate whether it is possible to extract the information about the gas concentration despite the influence of humidity. Commercial semiconductor sensor response was examined under the application of a periodic temperature change. The data was collected using measurement protocol for different concentrations of ammonia at specified levels of relative humidity. In this work we focused on the evaluation...
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Valorization of bio-based polyols synthesized via biomass liquefaction
Dane BadawczeAs the properties of polyols have a huge impact on the properties of manufactured polyurethanes, this study aims to determine the influence of polyethylene glycols with different molecular masses on the course of the biomass liquefaction process and bio-polyol properties. The obtained polyols were characterized by rheological studies. To confirm the...
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A New Expression for the 3-D Dyadic FDTD-Compatible Green's Function Based on Multidimensional Z-Transform
PublikacjaIn this letter, a new analytic expression for the time-domain discrete Green's function (DGF) is derived for the 3-D finite-difference time-domain (FDTD) grid. The derivation employs the multidimensional Z-transform and the impulse response of the discretized scalar wave equation (i.e., scalar DGF). The derived DGF expression involves elementary functions only and requires the implementation of a single function in the multiple-precision...
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Dynamic analysis of the impact of the wind spectrum according to the theory of Davenport for lightweight structures of the roof in sports hall Czyzyna in Cracow.
PublikacjaThe main aim of this analysis is to characterize numerical simulations connected with modeling dynamic influence of wind on the lightweight structures of the roof in sports hall – “Czyżyna”. This hall is built in Cracow. The article also involves the proposals of the solutions connected with dynamic influence of the wind – Davenport’s method has been used. These proposals have not been taken into consideration at the detailed engineering...
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Short Term Monitor of Photodegradation Processes in Ranitidine Hydrochloride Observed by FTIR and ATR FTIR
PublikacjaThe effects of degradation of ranitidine hydrochloride exposed to UVB radiation (l = 310 nm) and oxygen in a weathering chamber were studied by Fourier Transform Infrared spectroscopy (FTIR) and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR). ATR-FTIR profile indicated that the degradation was spatially heterogeneous. Significant amounts of photoproducts were detected only in a directly...
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Model dynamic electrochemical impedance spectroscopy (DEIS) results obtained with various DC polarization rates
Dane BadawczeThe dataset contains results of model dynamic electrochemical impedance spectroscopy studies carried out on a setup of 10 diodes in series, which were connected in parallel with a condenser. The impedance data were acquired every 1 s (the analytic window length for Fourier Transform was 1 s). The model system was polarized between 0 and +8 V with DEIS...
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Preliminary Investigation on Auto-Thermal Extrusion of Ground Tire Rubber
PublikacjaGround tire rubber (GTR) was processed using an auto-thermal extrusion as a prerequisite to green reclaiming of waste rubbers. The reclaimed GTR underwent a series of tests: thermogravimetric analysis combined with Fourier-transform infrared spectroscopy (TGA-FTIR), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and static headspace and gas chromatography-mass spectrometry (SHS-GC-MS) in order...
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Using concentrated spectrogram for analysis of audio acoustic signals
PublikacjaThe paper presents results of time-frequency analysis of audio acoustic signals using the method of Concentrated Spectrograph also known as ''Cross-spectral method'' or ''Reassignment method''. Presented algorithm involves signal's local group delay and channelized instantaneous frequency to relevantly redistribute all Short-time Fourier transform lines in time-frequency plain. The main intention of the paper is to compare various...
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Voice command recognition using hybrid genetic algorithm
PublikacjaAbstract: Speech recognition is a process of converting the acoustic signal into a set of words, whereas voice command recognition consists in the correct identification of voice commands, usually single words. Voice command recognition systems are widely used in the military, control systems, electronic devices, such as cellular phones, or by people with disabilities (e.g., for controlling a wheelchair or operating a computer...
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Sources and fate of microplastics in marine and beach sediments of the Southern Baltic Sea—a preliminary study
PublikacjaMicroplastics’ sources and fate in marine bottom and beach sediments of strongly polluted Baltic Sea have been investigated.Microplastics were extracted using sodium chloride. Their qualitative identification was conducted using micro-Fourier-transform infrared spectroscopy (μFT-IR).
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Analysis of radiation and scattering problems with the use of hybrid techniques based on the discrete Green's function formulation of the FDTD method
PublikacjaIn this contribution, simulation scenarios are presented which take advantage of the hybrid techniques based on the discrete Green's function formulation of the finite-difference time-domain (DGF-FDTD) method. DGF-FDTD solutions are compatible with the finite-difference grid and can be applied for perfect hybridization of the FDTD method. The following techniques are considered: (i) DGF-FDTD for antenna simulations, (ii) DGF-based...
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Akcelerator transformacji DCT do kompresji obrazu w sensorach wizyjnych
PublikacjaW komunikacie przedstawiono konfigurowalny cyfrowy akcelerator transformacji DCT przeznaczony dla enkodera wideo standardu H.264. Akcelerator realizuje także odwrotnątransformacjęDCT oraz kwantyzacjęi dekwantyzację. Akcelerator początkowo zaimplementowano w układzie FPGA. Zostałon pomyślnie zweryfikowany, a następnie zaimplementowany w układzie ASIC w technologii UMC 90 nm. Szczegółowe wyniki testów akceleratora ASIC zostały...
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Comment on "Quantitative comparison of analysis methods for spectroscopic optical coherence tomography"
PublikacjaIn a recent paper by Bosschaart et al. [Biomed. Opt. Express 4, 2570 (2013)] various algorithms of time-frequency signal analysis have been tested for their performance in blood analysis with spectroscopic optical coherence tomography sOCT). The measurement of hemoglobin concentration and oxygen saturation based on blood absorption spectra have been considered. Short time Fourier transform (STFT) was found as the best method for...
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THE REPRESENTATION PROBLEM FOR A DIFFUSION EQUATION AND FRACTAL R-L LADDER NETWORKS
PublikacjaThe representation problem is to prove that a discretization in space of the Fourier transform of a diffusion equation with a constant diffusion coefficient can be realized explicitly by an infinite fractal R-L ladder networks. We prove a rigidity theorem: a solution to the representation problem exists if and only if the space discretization is a geometric space scale and the fractal ladder networks is a Oustaloup one. In this...
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Analysis of the chemical composition of MnO-B2O3 glass
Dane BadawczeStructural and thermal properties of xMnO−(100−x)B2O3 (where x = 40, 50 and 60 mol%) glass samples have been investigated with the employment of various techniques. Fourier transform infrared spectroscopy results revealed the influence of MnO on glass matrix. Decrease of B–O bond-related band intensities has been observed. MnO addition was found to...
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FFT spectrum based matching algorithm for activedynamic thermography
PublikacjaIn Active Dynamic thermography (ADT) sequences of consecutive temperature distributions are analyzed. In biomedical applications of ADT, the problems of a patient's movements in front of a thermal camera should be eliminated before data analysis. Complete mechanical stabilization of the patients is impossible due to natural voluntary and involuntary moves caused by pulse breathing, etc. This paper presents a simple and efficient...
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A novel method of local chirp-rate estimation of LFM chirp signals in the time-frequency domain
PublikacjaIn the paper, novel dynamic representations of a complex signal in the time-frequency domain are introduced. The proposed approach is based on using the gradient of the short-time Fourier transform complex phase. A channelized instantaneous complex frequency (CICF) and a complex local group delay (CLGD) are included in the presented signal representations. An application of the newly-introduced distributions is demonstrated by...
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Structural and physico-mechanical properties of natural rubber/GTR composites devulcanized by microwaves: Influence of GTR source and irradiation time
PublikacjaGround tire rubber from car and truck was modified using microwave irradiation at variable time. The irradiated ground tire rubber was used as filler in composites based on natural rubber. The composites, with high content of ground tire rubber, were prepared using an internal batch mixer and subsequently cross-linked at 160℃. The influence of the ground tire rubber source (car/truck) and irradiation time on structure, physico-mechanical...
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Evaluation of the fast impedance spectroscopy method in the laboratory measurement system
PublikacjaIn this paper the method for fast impedancespectroscopy of technical objects with very high impedance(|Zx| ≥ 1 GΩ) is evaluated by means of simulation and practicalexperiment. The method is based on excitation of an object, witha square pulse and measurements of voltage and currentresponses with DAQ card. The object impedance spectrum isobtained with use of continuous Fourier transform. Someimprovements of the method concerned...
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Simple Fractal Calculus from Fractal Arithmetic
PublikacjaNon-Newtonian calculus that starts with elementary non-Diophantine arithmetic operations of a Burgin type is applicable to all fractals whose cardinality is continuum. The resulting definitions of derivatives and integrals are simpler from what one finds in the more traditional literature of the subject, and they often work in the cases where the standard methods fail. As an illustration, we perform a Fourier transform of a real-valued...