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Wyświetlanie 1-15 z 24
Tytuł:
Fractal dimensions analysis of branching streamers propagating in mineral oil
Autorzy:
Dang, Viet-Hung
Beroual, Abderrahmane
Rózga, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/2135726.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fractal analysis
lightning impulse voltage
mineral oil
streamers
Opis:
This article deals with the analysis of the fractal dimension of streamers propagating in mineral oil, under lightning impulse voltage, using the box counting method; the method and technique of calculation are described therein. In the considered experimental conditions, the average velocities of recorded streamers are of 2.4 km/s and 1.8 km/s for positive and negative streamers, respectively; these velocities correspond to the 2nd mode of streamers propagation. It is shown that the streamers present the fractal dimension D ; and the higher D is the bushier are the streamers (i.e. with high branch density). The positive streamers can have higher D than the negative ones, if they are bushier.
Źródło:
Archives of Electrical Engineering; 2022, 71, 3; 659--669
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Fractal Analysis Methods for Lift Height Optimization in Magnetic Force Microscopy Measurements
Autorzy:
Bramowicz, M.
Kulesza, S.
Chrostek, T.
Sendrowski, C.
Powiązania:
https://bibliotekanauki.pl/articles/354969.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
lift height optimization
magnetic force microscopy
fractal analysis
Opis:
The paper presents results of a research on simulation of magnetic tip-surface interaction as a function of the lift height in the magnetic force microscopy. As expected, magnetic signal monotonically decays with increasing lift height, but the question aris es, whether or not optimal lift height eventually exists. To estimate such a lift height simple procedure is proposed in the paper based on the minimization of the fractal dimension of the averaged profile of the MFM signal. In this case, the fractal dimension ser ves as a measure of distortion of a pure tip-surface magnetic coupling by various side effects, e.g. thermal noise and contribution of topographic features. Obtained simulation results apparently agree with experimental data.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 3; 1109-1113
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Functional and Fractal Properties of Fe-Al Coatings After Gas Detonation Spraying (GDS)
Autorzy:
Chrostek, T.
Rychlik, K.
Bramowicz, M.
Senderowski, C.
Powiązania:
https://bibliotekanauki.pl/articles/355023.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Fe-Al
intermetallic alloys
GDS
SEM
fractal analysis
Opis:
The paper presents the results and provides an analyse of the geometric structure of Fe-Al protective coatings, gas-treated under specified GDS conditions. The analysis of the surface topography was conducted on the basis of the results obtained from the SEM data. Topographic images were converted to three-dimensional maps, scaling the registered amplitude coordinates of specific gray levels to the relative range of 0÷1. This allowed us to assess the degree of surface development by determining the fractal dimension. At the same time, the generated three-dimensional spectra of the autocorrelation function enabled the researchers to determine the autocorrelation length (Sal) and the degree of anisotropy (Str) of the surfaces, in accordance with ISO 25178. Furthermore, the reconstructed three-dimensional images of the topography allowed us to evaluate the functional properties of the studied surfaces based on the Abbott-Firestone curve (A-F), also known as the bearing area curve. The ordinate describing the height of the profile was replaced by the percentage of surface amplitude in this method, so in effect the shares of the height of the three-dimensional topographic map profiles of various load-bearing properties were determined. In this way, both the relative height of peaks, core and recesses as well as their percentages were subsequently established.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 4; 1993-1999
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Speech and Music – Nonlinear Acoustical Decoding in Neurocognitive Scenario
Autorzy:
Bhaduri, S.
Ghosh, D.
Powiązania:
https://bibliotekanauki.pl/articles/177385.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
speech signal
multifractality
Visibility Graph
Fractal Darwinism
neurocognitive disorders
Opis:
Speech and music signals are multifractal phenomena. The time displacement profile of speech and music signal show strikingly different scaling behaviour. However, a full complexity analysis of their frequency and amplitude has not been made so far. We propose a novel complex network based approach (Visibility Graph) to study the scaling behaviour of frequency wise amplitude variation of speech and music signals over time and then extract their PSVG (Power of Scale freeness of Visibility Graph). From this analysis it emerges that the scaling behaviour of amplitude-profile of music varies a lot from frequency to frequency whereas it’s almost consistent for the speech signal. Our left auditory cortical areas are proposed to be neurocognitively specialised in speech perception and right ones in music. Hence we can conclude that human brain might have adapted to the distinctly different scaling behaviour of speech and music signals and developed different decoding mechanisms, as if following the so called Fractal Darwinism. Using this method, we can capture all non-stationary aspects of the acoustic properties of the source signal to the deepest level, which has huge neurocognitive significance. Further, we propose a novel non-invasive application to detect neurological illness (here autism spectrum disorder, ASD), using the quantitative parameters deduced from the variation of scaling behaviour for speech and music.
Źródło:
Archives of Acoustics; 2018, 43, 4; 593-602
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Using the DDA (Discrete Dipole Approximation) Method in Determining the Extinction Cross Section of Black Carbon
Autorzy:
Skorupski, K.
Powiązania:
https://bibliotekanauki.pl/articles/221846.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
black carbon
discrete dipole approximation
light scattering
fractal-like aggregates
Opis:
BC (Black Carbon), which can be found in the atmosphere, is characterized by a large value of the imaginary part of the complex refractive index and, therefore, might have an impact on the global warming effect. To study the interaction of BC with light often computer simulations are used. One of the methods, which are capable of performing light scattering simulations by any shape, is DDA (Discrete Dipole Approximation). In this work its accuracy was estimated in respect to BC structures using the latest stable version of the ADDA (vr. 1.2) algorithm. As the reference algorithm the GMM (Generalized Multiparticle Mie-Solution) code was used. The study shows that the number of volume elements (dipoles) is the main parameter that defines the quality of results. However, they can be improved by a proper polarizability expression. The most accurate, and least time consuming, simulations were observed for IGT_SO. When an aggregate consists of particles composed of ca. 750 volume elements (dipoles), the averaged relative extinction error should not exceed ca. 4.5%.
Źródło:
Metrology and Measurement Systems; 2015, 22, 1; 153-164
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of emitter sources in the aspect of their fractal features
Autorzy:
Dudczyk, J.
Kawalec, A.
Powiązania:
https://bibliotekanauki.pl/articles/200415.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fractal feature
pattern of radar
signal processing
Specific Emitter Identification (SEI)
Opis:
This article presents the procedure of identification radar emitter sources with the trace distinctive features of original signal with the use of fractal features. It is a specific kind of identification called Specific Emitter Identification, where as a result of using transformations, which change measure points, a transformation attractor was received. The use of linear regression and the Lagrange polynomial interpolation resulted in the estimation of the measurement function. The method analysing properties of the measurement function which has been suggested by the authors caused the extraction of two additional distinctive features. These features extended the vector of basic radar signals’ parameters. The extended vector of radar signals’ features made it possible to identify the copy of radar emitter source.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 3; 623-628
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compact coplanar-fed tree-shaped antenna
Autorzy:
Malinowska, Małgorzata
Kitliński, Marek
Powiązania:
https://bibliotekanauki.pl/articles/226372.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
broadband antenna
fractal antenna
reflection coefficient,
defected ground structure
coplanar waveguide
Opis:
The paper presents the concept of a fully planar tree-shaped antenna with quasi-fractal geometry. The shape of the proposed radiator is based on a multi-resonant structure. Developed planar tree has symmetrical branches with different length and is fed by a coplanar waveguide (CPW) with modified edge of the ground plane. The antenna of size 29 mm x25 mm has been designed on Taconic - RF-35 substrate (er = 3.5, tgde= 0.0018, h = 0.762 mm). The paper shows simulated and measured characteristics of return loss, as well as measured radiation patterns. The proposed antenna could be a good candidate for broadband applications (for instance: wideband imaging for medical application and weather monitoring radars in satellite communication etc.)
Źródło:
International Journal of Electronics and Telecommunications; 2019, 65, 2; 175-180
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Miniaturized Wearable Fractal Patch Antenna for Body Area Network Applications
Autorzy:
Jain, Vikas
Dhaliwal, Balwinder Singh
Powiązania:
https://bibliotekanauki.pl/articles/1844620.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wearable antenna
conformal antenna
biomedical systems
body area networks
fractal antenna
Opis:
This article presents the design of a miniaturized wearable patch antenna to be utilized for the body area network (BAN) applications. To reduce the size of the antenna a crown fractal geometry antenna design technique has been adopted, and which resulted in a size reduction of 26.85%. Further, the polyester cloth has been used as the substrate of the antenna to make the proposed antenna a flexible one, and suitable for wearable biomedical devices. The designed antenna functions for the 2.45 GHz ISM band and has the gain and bandwidth of 4.54 dB and 131 MHz respectively, covering the entire ISM band. The antenna characteristics like return loss (S11), directivity and radiation pattern have been simulated and analyzed. Specific absorption rate (SAR) and front to back ratio (FBR) of the proposed antenna at the human body tissue model (HBTM) in the planer and different bending conditions of the antenna have also simulated and analyzed, and the proposed antenna fulfils the desired design standards.
Źródło:
International Journal of Electronics and Telecommunications; 2021, 67, 2; 149-154
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Aging and Degradation of Human Fingernail Plates Upon Cosmetic Agents
Autorzy:
Kulesza, S.
Bramowicz, M.
Gwoździk, M.
Wilczyński, S.
Goździejewska, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/354662.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Atomic Force Microscopy
Scanning Electron Microscopy
fractal characterization
nanoscale property mapping
Opis:
The knowledge whether and how chemical species react with tissues is important because of protection against harmful factors, diagnose of dermatological diseases, validation of dermatological procedures as well as effectiveness of topical therapies. In presented work the effects of chemical agents on plates of human fingernails were studied using Atomic Force Microscopy and Scanning Electron Microscopy. Apart from that, mapping of the elastic properties of the nails was also carried out. To obtain reliable measures of spatial evolution of the surface variations, recorded images were analyzed in terms of scaling invariance brought by fractal geometry, instead of common though not unique statistical measures.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 1; 181-184
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Delivery-flow routing and scheduling subject to constraints imposed by vehicle flows in fractal-like networks
Autorzy:
Bocewicz, G.
Banaszak, Z.
Nielsen, I.
Powiązania:
https://bibliotekanauki.pl/articles/229533.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
transport network
fractal structure
declarative modeling
multimodal processes
delivery flow
vehicles flow
Opis:
The problems of designing supply networks and traffic flow routing and scheduling are the subject of intensive research. The problems encompass the management of the supply of a variety of goods using multi-modal transportation. This research also takes into account the various constraints related to route topology, the parameters of the available fleet of vehicles, order values, delivery due dates, etc. Assuming that the structure of a supply network, constrained by a transport network topology that determines its behavior, we develop a declarative model which would enable the analysis of the relationships between the structure of a supply network and its potential behavior resulting in a set of desired delivery-flows. The problem in question can be reduced to determining sufficient conditions that ensure smooth flow in a transport network with a fractal structure. The proposed approach, which assumes a recursive, fractal network structure, enables the assessment of alternative delivery routes and associated schedules in polynomial time. An illustrative example showing the quantitative and qualitative relationships between the morphological characteristics of the investigated supply networks and the functional parameters of the assumed delivery-flows is provided.
Źródło:
Archives of Control Sciences; 2017, 27, 2; 135-150
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical exponent analysis applied to surface EMG signals for multifunction myoelectric control
Autorzy:
Phinyomark, A.
Phothisonothai, M.
Phukpattaranont, P.
Limsakul, C.
Powiązania:
https://bibliotekanauki.pl/articles/220544.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
biomedical signal processing
electromyography signal
feature extraction
fractal analysis
human machine interface
pattern classification
Opis:
Based on recent advances in non-linear analysis, the surface electromyography (sEMG) signal has been studied from the viewpoints of self-affinity and complexity. In this study, we examine usage of critical exponent analysis (CE) method, a fractal dimension (FD) estimator, to study properties of the sEMG signal and to deploy these properties to characterize different movements for gesture recognition. SEMG signals were recorded from thirty subjects with seven hand movements and eight muscle channels. Mean values and coefficient of variations of the CE from all experiments show that there are larger variations between hand movement types but there is small variation within the same type. It also shows that the CE feature related to the self-affine property for the sEMG signal extracted from different activities is in the range of 1.855∼2.754. These results have also been evaluated by analysis-of-variance (p-value). Results show that the CE feature is more suitable to use as a learning parameter for a classifier compared with other representative features including root mean square, median frequency and Higuchi's method. Most p-values of the CE feature were less than 0.0001. Thus the FD that is computed by the CE method can be applied to be used as a feature for a wide variety of sEMG applications.
Źródło:
Metrology and Measurement Systems; 2011, 18, 4; 645-658
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of deformation and fragmentation of fractal-like nanoaggregates
Autorzy:
Żywczyk, Łukasz
Moskal, Arkadiusz
Przekop, Rafał
Powiązania:
https://bibliotekanauki.pl/articles/185230.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fractal-like aggregate
discrete element modelling
fragmentation
restructuration
agregat fraktalny
modelowanie elementów dyskretnych
podział
restrukturyzacja
Opis:
Aflexible fractal-like aggregate modelwas used to study deformation and fragmentation of the structure of fractal-like aggregates via their impaction with rigid rough surface.Aggregateswere conveyed one at the time towards a surface under vacuum conditions. The number of primary particles remaining in each fragment, ratio of average fragment radius of gyration after impaction to the average fragment initial radius of gyration and ratio of average coordination number to the initial coordination number were monitored for each individual aggregate. Results demonstrate that depending on the impact velocity, the fractal dimension of the aggregate, the strength of bonds between primary particles, the stiffness of the aggregate structure and the diameter of primary particle composing an aggregate, restructuring or breakage of the aggregate occur. Moreover, in the analysis of the ratio of coordination number of aggregates after impaction to the initial coordination number, three regimes were distinguished: first no deformation at low impact velocities, second restructurisation regime and finally fragmentation regime where partial or total fragmentation of aggregates was observed.
Źródło:
Chemical and Process Engineering; 2019, 40, 4; 377--397
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fractal dimension for the characterization of the porosity of asphalt concretes
Autorzy:
Leonardi, G.
Powiązania:
https://bibliotekanauki.pl/articles/231336.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
geometria fraktalna
porowatość
mieszanka
kruszywo
beton asfaltowy
nawierzchnia
fractal geometry
porosity
mixture
aggregate
asphalt concrete
pavement
Opis:
In the design of asphalt mixtures for paving, the choice of components has a remarkable importance, as requirements of quality and durability must be assured in use, guaranteeing adequate standards of safety and comfort. In this paper, an approach of analysis on the aggregate materials using fractal geometry is proposed. Following an analytical and an experimental approach, it was possible to find a correlation between characteristics of the asphalt concrete (specific gravity and porosity) and the fractal dimension of the aggregate mixtures. The studies revealed that this approach allows to draw the optimal fractal dimension and, consequently, it can be used to choose an appropriate aggregate gradation for the specific application; once the appropriate initial physical parameters are finalized. This fractal approach could be employed for predicting the porosity of mixed asphalt concretes, given as input the fractal characteristics of the aggregate mixtures of the concrete materials.
Źródło:
Archives of Civil Engineering; 2010, 56, 4; 321-333
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wymiar fraktalny polskiego organizmu przestrzennego
Fractal dimension of Polish spatial organism
Autorzy:
Gibas, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2032390.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fractal dimension
living structures
spatial organism
construction categories
wymiar fraktalny
żywa struktura
organizm przestrzenny
kategorie konstrukcji
Opis:
The analysis of the fractal dimension becomes one of the new approach features in spatial research. This approach bases on the perception of space as a living structure, an organism which in its complexity and heterogeneity is a multi-scale creation although holistically perceived. The aim of the authors was to determine the nationwide fractal dimensions for the distinguished construction categories and designation of general regularities in these layout.
Źródło:
Biuletyn Komitetu Przestrzennego Zagospodarowania Kraju PAN; 2018, 272; 359-371
0079-3493
Pojawia się w:
Biuletyn Komitetu Przestrzennego Zagospodarowania Kraju PAN
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the Autocorrelation Function and Fractal Geometry Methods for Analysis of MFM Images
Zastosowanie funkcji autokorelacji oraz geometrii fraktalnej do analizy obrazów struktur domenowych rejestrowanych metodą MFM
Autorzy:
Bramowicz, M.
Kulesza, S.
Czaja, P.
Maziarz, W.
Powiązania:
https://bibliotekanauki.pl/articles/352007.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
atomic force microscopy (AFM)
magnetic force microscopy
magnetic domains
fractal analysis
mikroskopia sił magnetycznych
MFM
analiza fraktalna
Opis:
Presented work is focused on the use of correlation methods for numerical analysis of magnetic stray field over the surface of materials. Obtained results extend our previous findings about application of the autocorrelation function and the fractal analysis for characterization of magnetic surfaces. Several domain images are recorded at various tip-sample gaps (i.e. the lift heights), and then their average widths were extrapolated down to the zero distance in order to estimate the width seen right on the surface. Apart from that, fractal parameters were derived from autocorrelation function, which turned out to be sensitive to the lift height, and might constitute universal measure (the critical lift height), above which the MFM signal became dominated by thermal noises and non-magnetic residual interactions.
Niniejsza praca dotyczy zastosowania metod korelacyjnych do numerycznej analizy obrazów rozkładu pola magnetycznego emitowanego z obszarów spontanicznego namagnesowania. W pracy przedstawiono kontynuację badań nad zastosowaniem funkcji autokorelacji oraz metod analizy fraktalnej w badaniach struktury domenowej oraz charakterystyki emitowanego z nich pola magnetycznego. Wyniki badań wykazują zależność mierzonej metodami mikroskopii sił magnetycznych (MFM) szerokości domen od wysokości skanowania nad badaną powierzchnią, sugerując przeprowadzanie serii pomiarów na różnych wysokościach (h), ich aproksymację z następną ekstrapolacją do powierzchni (h=0). Przeprowadzona analiza fraktalna, wskazuje na możliwość jej aplikacji do charakterystyki zmian sygnału magnetycznego rejestrowanego przez MFM. Pozwala ona również na wyznaczenie wysokości krytycznej (hkr), na której sygnałem dominującym stają się nakładające się na sygnał magnetyczny pozostałości niemagnetycznych interakcji między igłą sondy i badaną powierzchnią, stanowiące rejestrowany przez MFM szum.
Źródło:
Archives of Metallurgy and Materials; 2014, 59, 2; 451-457
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 24

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