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Tytuł:
Designing Eight-port Antenna Array for Multi-Band MIMO Applications in 5G Smartphones
Autorzy:
Al-Azzawi, Zainab Faydhe
AbdulSattar, Rusul Khalid
Muhsin, Muhannad Y.
Azeez, Mohammed Abdulrazzaq
Salim, Ali J.
Ali, Jawad K
Powiązania:
https://bibliotekanauki.pl/articles/27312953.pdf
Data publikacji:
2023
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
5G communication
compact MIMO antenna
decoupling techniques
fractal geometry
multi-band antenna
Opis:
This article introduces a dual-functional low-profile compact multiple input multiple output (MIMO) antenna array for multi-band communication in 5G smartphones. The proposed eight elements of the antenna array form two different 4 ×4 MIMO systems. The first four elements are placed at the four mobile corners and operate in a single band of 3. 445– 3. 885 GHz for 5G n77 and n 78 applications. The other system, in which four antennas are positioned in the middle of the terminal board, supports two wide bands of 1 . 684– 2. 300 GHz and 4. 432 – 5. 638 for n 2, n 3, n 39, n 65, n 66, n 79 , and WLAN applications. The second iteration of a modified Peano-type fractal geometry served as the design foundation for the proposed antenna element. The system’s ground plane design is based on self-isolated and spatial diversity methods. The single-band MIMO system’s isolation is better than 23 dB. In the dual-band MIMO system that is based on self-isolation, isolation equals approximately 16 dB in the higher band and 10 dB in the lower band. To evaluate performance, radiation-related and total antenna efficiencies, scattering parameters and gains were investigated. Additionally, ECCs have been considered to evaluate MIMO performance. According to the results, such design constitutes a valuable option for MIMO applications in 5G smartphones.
Źródło:
Journal of Telecommunications and Information Technology; 2023, 4; 18--24
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Macromodeling of local power supply system balance forecasting using fractal properties of load and generation schedules
Makromodelowanie prognozowania bilansu lokalnego systemu elektroenergetycznego z wykorzystaniem fraktalnych właściwości planówobciążenia i generacji
Autorzy:
Jarykbassov, Daniyar
Lezhniuk, Petr
Hunko, Iryna
Lysyi, Vladyslav
Dobrovolska, Lyubov
Powiązania:
https://bibliotekanauki.pl/articles/27315445.pdf
Data publikacji:
2023
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
power supply system
urban development
power consumption forecasting
macromodelling
fractal properties
system zasilania
rozwój miast
prognozowanie zużycia energii
makromodelowanie
właściwości fraktalne
Opis:
A method of forecasting the balance of electricity consumption of urban development objects, civil purposes using discrete macromodels is proposed. We consider the power supply system (PSS) of the district, which is characterised by power supply from general-purpose power grids, as well as having its own generation of electricity from renewable energy sources (RES). Such a local electric power system (LES) under certain conditions can be operated as an independent balanced electrical facility. For optimal operation of the LES under these conditions, it is necessary to predict its power consumption schedules. The proposed macromodelling method allows to develop deterministic models of power consumption with the required accuracy on the basis of retrospective information without the use of data preprocessing procedures. The solution to the problem of forecasting electricity consumption schedules is simplified by using only basic or deterministic characteristics in the construction of the model. These include fractal properties of PSS load schedules.
Zaproponowano metodę prognozowania bilansu zużycia energii elektrycznej przez obiekty miejskie o przeznaczeniu cywilnym z wykorzystaniem makromodeli dyskretnych. Rozważany jest system zasilania (SZ) dzielnicy, który charakteryzuje się zasilaniem z sieci ogólnego przeznaczenia, a także posiada własną produkcję energii elektrycznej z odnawialnych źródeł energii (OZE). Taki lokalny system elektroenergetyczny (LES) w pewnych warunkach może być eksploatowany jako niezależny, zrównoważony obiekt elektryczny. Aby zapewnić optymalne działanie LES w takich warunkach, konieczne jest przewidywanie jego harmonogramów poboru mocy. Proponowana metoda makromodelowania pozwala na opracowanie deterministycznych modeli poboru mocy z wymaganą dokładnością na podstawie informacji retrospektywnych bez stosowania procedur wstępnego przetwarzania danych. Rozwiązanie problemu prognozowania planów zużycia energii elektrycznej jest uproszczone poprzez wykorzystanie w konstrukcji modelu jedynie podstawowych lub deterministycznych charakterystyk. Obejmują one fraktalne właściwości harmonogramów obciążenia SZ.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2023, 13, 3; 79--82
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of Square-shaped Bolted Joints Based on Improved Particle Swarm Optimization Algorithm
Autorzy:
Chen, Kui
Yang, Cheng
Zhao, Yongsheng
Niu, Peng
Niu, NaNa
Hongchao, Wu
Powiązania:
https://bibliotekanauki.pl/articles/27312779.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
particle swarm optimization algorithm
bolt connection
bolted joint
fractal theory
Opis:
The bolted joint is widely used in heavy-duty CNC machine tools, which has huge influence on working precision and overall stiffness of CNC machine. The process parameters of group bolt assembly directly affect the stiffness of the connected parts. The dynamic model of bolted joints is established based on the fractal theory, and the overall stiffness of joint surface is calculated. In order to improve the total stiffness of bolted assembly, an improved particle swarm optimization algorithm with combination of time-varying weights and contraction factor is proposed. The input parameters are preloading of bolts, fractal dimension, roughness, and object thickness. The main goal is to maximize the global rigidity. The optimization results show that improved algorithm has better convergence, faster calculation speed, preferable results, and higher optimization performance than standard particle swarm optimization algorithm. Moreover, the global rigidity optimization is achieved.
Źródło:
Eksploatacja i Niezawodność; 2023, 25, 3; art. no. 168487
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of energies on the impact breakage characteristic of magnetite ores
Autorzy:
Si, Liang
Cao, Yijun
Li, Guosheng
Powiązania:
https://bibliotekanauki.pl/articles/2200336.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
fractal dimension
ore breakage characteristic
particle size distribution
mineral liberation
fracture morphology
Opis:
The energy applied during breakage is the key to enhancing the magnetite liberation degree and improving quality. The relationship between energy and liberation properties remains unclear due to various complicated factors affecting mineral liberation. Therefore, this work aims to study the effect of energy on the breakage characteristics of magnetite ores; the impact breakage test was conducted on magnetite particle groups at different energies using a drop weight impact tester; the statistical analysis was performed based on the fractal theory to research the particle size distribution; the fracture morphology and liberation properties of these ores were analyzed using scanning electron microscope and mineral liberation analyzer. Results show that the particle size distribution of magnetite after breakage conforms to the fractal law. The larger the energy, the greater the fractal dimension for this distribution, showing a linear relation between them, which implies that the fractal dimension can evaluate the breakage degree. The fracture morphology of magnetite ores indicates that as the energy increases, the intergranular fracture evolves into transgranular fracture, proving the influence of energy on fracture modes. It is found that the magnetite liberation degree first increases and then decreases with the rising of energy, indicating that the magnetite liberation can be improved at an appropriate amount of energy. The above conclusions provide a theoretical reference for optimizing energy and improving broken product quality.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 1; art. no. 159098
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Psychoacoustic Annoyance on EEG Signals of Tractor Drivers
Autorzy:
Lashgari, Majid
Arab, Mohammad Reza
Nadjafi, Mohsen
Rafiee, Mojtaba
Powiązania:
https://bibliotekanauki.pl/articles/31339953.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
EEG
Higuchi
fractal
tractor
sound.
Opis:
The purpose of this study was to evaluate the psychoacoustic annoyance (PA) that the tractor drivers are exposed to, and investigate its effects on their brain signals during their work activities. To this aim, the sound of a garden tractor was recorded. Each driver’s electroencephalogram (EEG) was then recorded at five different engine speeds. The Higuchi method was used to calculate the fractal dimension of the brain signals. To evaluate the amount of acoustic annoyance that the tractor drivers were exposed to, a psychoacoustic annoyance (PA) model was used. The results showed that as the engine speed increased, the values of PA increased as well. The results also indicated that an increase in the Higuchi’s fractal dimension (HFD) of alpha and beta bands was due to the increase of the engine speed. The regression results also revealed that there was a high correlation between the HFD of fast wave activities and PA, in that, the coefficients of determination were 0.92 and 0.91 for alpha and beta bands, respectively. Hence, a good correlation between the EEG signals and PA can be used to develop a mathematical model which quantifies the human brain response to the external stimuli.
Źródło:
Archives of Acoustics; 2022, 47, 4; 469-477
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fractal Dimension as Robust Estimate of Low Carbon Steels Hardness
Autorzy:
Zając, Krzysztof
Płatek, Karolina
Wachel, Paweł
Łatka, Leszek
Powiązania:
https://bibliotekanauki.pl/articles/2202985.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
fractal dimension
linear regression
robust hardness estimation
image processing
low carbon steel
Opis:
Application of computational methods in engineering and science constantly increases, which is also visible in sector of material science, often with promising results. In following paper, authors would like to propose fractal dimension, a mathematical method of quantifying self-similarity and complexity of spatial patterns, as robust method of hardness estimation of low carbon steels. A dataset of microstructure images and corresponding Vickers hardness measurements of S235JR steel under different delivery conditions was created. Then, three different computational methods for evaluation of materials hardness based on microstructure image were tested. In this paper those methods are called: (i) Otsu-based index, (ii) fractal dimension index and (iii) vision transformer index. The results were compared with method used in literature for similar problems. Comparison showed that fractal dimension performs better than other evaluated methods, in terms of median absolute error, which value was equal to 4.12 HV1, which is significantly lower than results achieved by Otsu-based index and vision transformer index, which were 4.49 HV1 and 5.07 HV1 respectively. Those results can be attributed to the relative robustness of fractal dimension index, when compared to other methods. Robust estimation is preferable, due to the high amount of noise in the dataset, which is a consequence of the nature of used material.
Źródło:
Advances in Science and Technology. Research Journal; 2022, 16, 5; 335--344
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Investing in dividend vs. non-dividend stocks – efficiency assessment using fractal measures
Autorzy:
Buła, Rafał
Jabłoński, Bartłomiej
Powiązania:
https://bibliotekanauki.pl/articles/27313543.pdf
Data publikacji:
2022
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
payout policy
dividend
financial investment
fractal dimension
polityka wypłat
dywidenda
inwestycja finansowa
wymiar fraktalny
Opis:
Purpose: The purpose of the paper is to reveal potential differences in risk and profitability of investment in dividend and non-dividend stocks. Design/methodology/approach: The scientific aim of the paper is achieved by conducting a scrupulous literature analysis. Moreover, the authors use methods of comparative analysis to investigate the characteristics of dividend and non-dividend stocks and reveal similarities and differences. Study of fractal features of chosen stocks and comparisons between abovementioned groups of shares are conducted using the ANOVA methods. Findings: The results of the empirical analyses conducted in this paper prove that dividends paid by US dividend companies grow at significantly lower rate than dividends distributed by Polish dividend stocks. Additionally, rates of return on Polish dividend stocks are more heavily influenced by dividend pay-outs than rates of return on US ones. Taking into account riskiness of investments there are no differences in risk level between dividend and non-dividend stocks in USA and Poland, independently whether the risk measure exploited is stock volatility or its fractal dimension. Research limitations/implications: The research was based on limited number of companies analyzed. As a result, there could be present a bias introduced by the deterministic method of choosing a sample of stocks. It is recommended to enlarge the analyzed set in future research. Practical implications: Knowledge about similarities and differences among dividend and non-dividend companies is highly relevant to investors as well as corporate managements. As a consequence, better financial decisions could be taken leading to increased final wealth. Social implications: Among the social implications of the paper the possible change in investors’ attitude towards dividend and non-dividend companies seems most important. This could influence companies’ boards to adjust their payout policies to satisfy the investors. Finally, the improvement in investor’s needs fulfillment can be achieved. Originality/value: The novelty of the paper is the comparison of dividend and non-dividend stocks taking into account classical and modern risk measures. Moreover, it compares the efficiency of investing in dividend and non-dividend stocks during period 2015-2021, i.e. partially catching the effect of SARS-CoV-2 pandemic filling a gap in our knowledge.
Źródło:
Zeszyty Naukowe. Organizacja i Zarządzanie / Politechnika Śląska; 2022, 160; 109--128
1641-3466
Pojawia się w:
Zeszyty Naukowe. Organizacja i Zarządzanie / Politechnika Śląska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Jak „widzą” niewidomi?
How Do Blind People “See”?
Autorzy:
Chmielecki, Konrad
Powiązania:
https://bibliotekanauki.pl/articles/2130729.pdf
Data publikacji:
2022-09-29
Wydawca:
Akademia Ignatianum w Krakowie
Tematy:
osoby niewidome
podmiot wizualny
reprodukcja
nowa wizualność
społeczne widzenie
zdarzenie wizualne
podmiot fraktalny
bioobrazy
studia kultury wizualnej
The Passing Billa Violi
blind people
visual subject
reproduction
new visuality
social seeing
visual event
fractal subject
biopictures
Visual Culture Studies
Bill Viola’s The Passing
Opis:
Artykuł porusza problematykę nowej widzialności i reprodukcji pola społecznego „widzenia” u osób niewidomych jako „podmiotów wizualnych” w perspektywie studiów kultury wizualnej. Przyjmując założenie, że kultura wizualna pociąga za sobą rozważania na temat ślepoty, niewidzialnego, niewidomego w perspektywie społecznej, autor śledzi, w jaki sposób niewidomi funkcjonują jako podmioty wizualne w społeczeństwie wizualnym, czyli osoby konstytuujące aktywny społecznie środek wzroku (niezależnie od jego biologicznej zdolności widzenia) oraz jako efekt szeregu kategorii podmiotów wzrokowych. W tym kontekście Nicholas Mirzoeff odwołuje się do przykładu niewidomych, którzy na początku ery panoptycznej stali się przedmiotem społecznej troski państwa, co doprowadziło do powstania instytucji państwowych dla niewidomych. Panoptyzm stworzył niewidomych jako „naturalny” cel społeczeństwa, państwa i troski, właśnie dlatego, że „widzenie” i „bycie widzianym” stały się problematyczne w trosce dyscyplinarnego państwa narodowego. W eseju The Question of Cultural Identity Stuart Hall wyróżnia trzy typy podmiotów: oświeceniowy, socjologiczny i postmodernistyczny. Odniesienie do racjonalnego podmiotu dotyczy także osób niewidomych. Mitchell wspomina Optykę René Descartesa, w której filozof uważał wzrok za „rozszerzoną formę dotyku”, porównując go do „kija używanego przez niewidomych” do wzmocnienia ścieżki w realnej przestrzeni. Podobnie w perspektywie podmiotu ponowoczesnego warto przywołać model „widzenia bez patrzenia” Paula Virilia – reprodukcji intensywnej ślepoty, która jest ostatnią formą „industrializacji ślepoty” przez „maszyny widzenia”. Koncepcja podmiotu fraktalnego Jeana Baudrillarda dowodzi, że życie niewidomych jest „społeczną konstrukcją widzenia”. Podmiot wizualny, który znajdujemy w koncepcji bioobrazów W.J.T. Mitchell, prowadzi nas do wniosku, że obrazy można tworzyć tak, jak obrazy przedmiotu, wyczuwając je w wyobraźni. Nicholas Mirzoeff proponuje wprowadzenie terminu „zdarzenie wizualne” zamiast pojęcia „podmiot wizualny”; jest on generowany w interfejsie z technologią wizualną w procesie komunikacji za pośrednictwem komputera, w którym mogą uczestniczyć również osoby niewidome. Wreszcie, The Passing Billa Violi zostało zinterpretowane w kontekście obrazów wewnętrznych. Trudno nie przywołać tej koncepcji, mówiąc o obrazach, które są efektem „widzenia” niewidomych. Obrazy generowane przez „oko umysłu” pochodzą ze snów, wspomnień, obrazów i wyobrażeń, w których widzimy siebie, ale z punktu widzenia obserwatora – osoby niewidomej. Viola przypisuje tę funkcję wewnętrznych obrazów kamerze wideo, która działa jak świadomość, stając się odzwierciedleniem naszego „ja”. Według Violi można opisać dynamikę świadomości, która na jednym końcu umieszcza obrazy zewnętrzne (także postrzegane przez niewidomych) i obrazy wewnętrzne (stany uczuć, emocje, marzenia senne i społeczne skutki „widzenia”).
The paper deals with the issues of new visibility and reproduction of the field of social “seeing” in blind people as “visual subjects” in the perspective of Visual Culture Studies. Taking an assumption that visual culture entails considerations on blindness, the invisible, the unseen, and the unseeable in social perspective, the author tracks the ways in which the blind function as visual subjects in a visual society, i.e., people who are constituted as an active social agent of sight (regardless of his or her biological capacity to see) and as the effect of a series of categories of visual subjects. In this context, Nicholas Mirzoeff refers to the example of the blind, who became an object of social state concern at the beginning of the panoptic era, leading to the establishment of state institutions for the blind. Panopticism created the blind as what has now become a “natural” target of social and state and concern precisely because “seeing” and “being seen” has become problematic in the concern of the disciplinary nation-state. In his essay The Question of Cultural Identity, Stuart Hall distinguishes three types of subjects: the enlightenment, sociological, and postmodern. The reference to the rational subject also applies to the blind. Mitchell mentions René Descartes’s Optics, in which the philosopher considered sight an “extended form of touch,” comparing it to “a staff used by the blind” to strengthen the path in real space. Similarly, in the perspective of the postmodern subject, it is worth recalling Paul Virilio’s model of “sightless vision” – the reproduction of an intense blindness that is the last form of the “industrialisation of the non-gaze” by “the vision machines.” Jean Baudrillard’s concept of the fractal subject proves that the life of the blind is “the social construction of vision.” The visual subject that we find in the concept of biopictures by W.J.T. Mitchell leads us to the conclusion that images can be created in a way like creating images of an object, by feeling them in the imagination of blind people. Nicholas Mirzoeff suggests an introduction to the term “visual event” instead of the concept of “visual subject,” which is generated in an interface with visual technology on computer-mediated communication process, in which blind people can be also participated. Finally, The Passing by Bill Viola has been interpreted in the context of internal images. It is difficult not to recall this concept when talking about pictures that are the result of the blind “seeing.” The images generated by the “mind’s eye” come from dreams, memories, images, and imaginations in which we see ourselves, but from the observer’s point of view as a blind person. Viola assigns this function of internal images to the video camera which acts as a tool of awareness as it becomes a reflection of our “I.” According to Viola, one can describe the dynamics of consciousness, which at one end places external images (also perceived by the blind) and internal images (states of feelings, emotions, dreams, and the social effects of “seeing”).
Źródło:
Perspektywy Kultury; 2022, 38, 3; 387-410
2081-1446
2719-8014
Pojawia się w:
Perspektywy Kultury
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multifractal detrended fluctuation analysis of heart rate variability
Autorzy:
Bębas, Ewelina
Kasperczuk, Anna
Oczeretko, Edward
Bossowski, Artur
Borowska, Marta
Powiązania:
https://bibliotekanauki.pl/chapters/2204804.pdf
Data publikacji:
2022
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
fractal dimension
heart rate variability
ECG
diabetes
children
multifractal detrended fluctuation analysis
multifractal
Opis:
The analysis of heart rate variability can be used to predict cardiovascular state in diabetic children. Studies on HRV are mainly based on RR intervals of the ECG signal and include both linear indices and nonlinear characteristics. The current study aims at applying Multifractal Detrended Fluctuation Analysis to investigate signals of the heart rate variability (HRV) in 50 healthy children (group K), 27 patients suffering from diabetes type 1 without subsequent vascular complications (group A) and 35 patients suffering from diabetes type 1 with subsequent vascular complications (hypertension) (group B). Multifractal features were extracted to quantitatively compare signal complexity between the healthy group and the group of children with diabetes and diabetes with complications. The MFDFA analysis showed the multi-fractional nature of the signals in all groups. The characteristic MFDFA parameters were determined and subjected to statistical analysis. It showed differences in parameters h(1) and h(2) between the control group K and group A. This gives rise to the development of further research in an attempt to distinguish between these groups.
Źródło:
Advances in biomedical engineering; 109-122
9788367185400
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Set of Suffosion Holes Occurring After a Water Supply Failure as a Structure with Fractal Features
Autorzy:
Iwanek, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/2105274.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
water pipe failure
suffosion hole
fractal feature
Opis:
As a result of a buried water pipe unsealing, water often flows from the pipe to the soil surface, washing out the solid particles of soil and creating the so-called suffosion holes. It is a dangerous phenomenon, especially in urbanized areas, where it poses a threat to human safety and the stability of infrastructure. Uncontrolled outflows of water from water pipes belong to the main causes of suffosion in cities, occur in all water networks around the world and are difficult to predict. Therefore, it seems to be important to determine the size of the so-called the protection zone, which is the area around the potential leak where, in the event of a water pipe failure, it would be possible for water to flow in the soil. The analysis of the suffosion holes distribution around the place of leakage may be helpful in determining the size of the protection zone. Previous studies have shown that this distribution is random. Thus, the structure consisting of suffusion holes creates a certain geometric shape, which is difficult to describe using the classical concepts of Euclidean geometry. The study showed that this structure meets the conditions for probabilistic fractals, which means that elements of fractal geometry can be used to determine the size of the protection zone.
Źródło:
Journal of Ecological Engineering; 2022, 23, 6; 164--171
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studies on water transport in quasi two-dimensional porous systems using neutron radiography
Autorzy:
Fijał-Kirejczyk, Izabela M.
Rogante, Massimo
Milczarek, Jacek J.
Żołądek-Nowak, Joanna
Jurkowski, Zdzisław
Żołądek, Jan
Rusinek, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/2105332.pdf
Data publikacji:
2022
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
water transport
drying
fractal
neutron radiography
wettability
wicking
wetting
Opis:
The spontaneous wetting and drying of flat porous samples of linen, cotton and synthetic textiles were studied using dynamic neutron radiography (DNR). The progress of the wetting process of the media was delineated from the obtained neutron dynamical radiography images. The results of the investigation reveal a non-classical behaviour of kinetics of wicking of these materials. The character of the wetting kinetics is discussed in terms of the fractal character of the tortuosity of fabric capillaries.
Źródło:
Nukleonika; 2022, 67, 1; 3--9
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on the effect of coal microscopic pore structure to its spontaneous combustion tendency
Autorzy:
Dong, Xianwei
Li, Gaojing
Dong, Xuanmeng
Wang, Fusheng
Powiązania:
https://bibliotekanauki.pl/articles/2201388.pdf
Data publikacji:
2022
Wydawca:
Główny Instytut Górnictwa
Tematy:
spontaneous combustion tendency
mercury injection
fractal dimension
indicator gases
tendencja do samozapłonu
porozymetria rtęciowa
wymiar fraktalny
gazy wskaźnikowe
Opis:
Coal is a porous medium. Due to the large number of pores in coal and the pore size on its surface, usually ranging from millimeter to nanometer, it is difficult to measure and analyze the microscopic pore structure of coal. In order to investigate the effect of the microscopic pore structure of coal on its spontaneous combustion tendency, coal samples from different coal mines of the Kailuan Group were selected as the research objects, and the data of the microscopic pore distribution of three different coal samples were measured by using mercury injection apparatus. The regression analysis of microscopic pore data of coal samples obtained in the mercury injection experiment shows that the correlation coefficients of the regression curves are all greater than 0.94 and the fitting degree is good, indicating that there is a good correlation between the pressure, mercury intake and pore size of the coal samples, indicating that the fractal dimension of pore distribution is very effective. The fractal dimension is generally between 2 and 3, indicating that the microscopic pores of coal samples have good fractal characteristics and meet the fractal theory to describe the distribution characteristics of microscopic pores in porous media. Through the simulation system of natural combustion of coal, the simulation experiment of temperature rise oxidation of different coal samples (gas coal, fat coal, and coke coal) was carried out, and the curve of the concentration of gas products CO and CO2 in the process of temperature rise and oxidation of coal samples was drawn in the experiment. The experimental results show the relationship between the distribution structure of coal pores and its spontaneous combustion tendency, and the coal with a good distribution dimension has a stronger combustion tendency.
Źródło:
Journal of Sustainable Mining; 2022, 21, 2; 120--127
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asilos distópicos. Dos visiones literarias de la vejez en una sociedad indiferente
Dystopian Nursing Homes. Two Literary Visions of Old Age in an Indifferent Society
Autorzy:
Draus-Kłobucka, Agata
Powiązania:
https://bibliotekanauki.pl/articles/2015092.pdf
Data publikacji:
2021
Wydawca:
Komisja Nauk Filologicznych Polskiej Akademii Nauk, Oddział we Wrocławiu
Tematy:
urban marginalisation
asylum
fractal literature
Hispanic novel
Opis:
The article is dedicated to the problem of urban marginalisation of the elderly reflected in literature. Through an evolutionary comparative approach, the treatment of the subject is shown in an Argentine novel by Ana María Shua, La muerte como efecto secundario, published in 1997, and a Spanish novel from the year 2020, Los ancianos siderales, by Luis Mateo Díez. Both books, concentrated around the issue of residential homes, can be perceived as prose of social denunciation. However, they represent different aesthetics and styles: an epistolary narrative in the form of a long monologue in the Argentine novel, belonging to the current of future anticipation fiction; and a choral literature of fractal aesthetics in the most recent book by the Spanish author, marked by a surrealist and oneiric approach. The article offers a comparison of the images of senectitude in both novels, then of the representations of care homes and, finally, describes the characteristics of the societies that allow and support this abusive system.
Źródło:
Academic Journal of Modern Philology; 2021, 11; 37-56
2299-7164
2353-3218
Pojawia się w:
Academic Journal of Modern Philology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of the Possibility of Using Fractal Analysis to Describe the Surface Aluminum Composites After Turning
Autorzy:
Karolczak, P.
Kowalski, M.
Raszka, K.
Powiązania:
https://bibliotekanauki.pl/articles/2023814.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
surface roughness
fractal analysis
composite materials
diamond
cutting zone lubrication
chropowatość powierzchni
analiza fraktalna
materiały kompozytowe
diament
smarowanie strefy cięcia
Opis:
The description of the characteristics of the surface using standardized roughness parameters can not fully predict its performance properties. One of the tools supporting the assessment of the surface layer of the treated surface may be fractal analysis. This applies both to surfaces with machining traces, which are created under conditions of high randomness and variability of process conditions, and to surfaces with directional traces and their distinct periodicity. The paper presents the results of surface roughness measurements of turned aluminium matrix composites reinforced with ceramic fibers. Carbide and diamond tools were used for turning the tested material. The trials were carried out under dry machining conditions and with minimal lubrication in the cutting zone. Surfaces were measured by the contact method, and surface roughness parameters were calculated by Gaussian filtration. Then, the values of the fractal dimension were calculated using the enclosing box method. On the basis of these calculations, the influence of machining conditions on the values of selected roughness parameters and the box fractal dimension was determined. It was found that the fractal dimension, i.e. the irregularity of the geometric structure of the surface after turning of composites, changes with the change of cutting parameters, the tool and the method of lubricating the cutting zone. Of these factors, the feed has the greatest influence. As it grows, the irregularity of the machined surface structure decreases. In addition, the correlation coefficients between the fractal dimension and the measured roughness parameters were determined. It was noticed that the fractal dimension, in the case of turning aluminum composites, best correlates with the roughness parameters Sa and Ssk and thus describes features similar to these parameters. Therefore, it was assumed that it is possible to use fractal analysis as a supplementary tool for the description of the surface condition of aluminum composites after turning in various machining conditions. On the other hand, the fractal dimension can be treated as an additional tool to describe the surface condition, especially its irregularity, which is not described by other standard roughness parameters.
Źródło:
Advances in Science and Technology. Research Journal; 2021, 15, 4; 49-60
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 190

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