Search results - BazTech

1

Wpływ sposobu przechowywania filamentu ABS, PLA, PET-G na właściwości wyrobów wytwarzanych przyrostowo metodą FDM

Góralski Błażej, Siergiej Joanna

Zarządzanie Przedsiębiorstwem

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2023

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Vol. 26, nr 1

7--11

EN

The subject of the article is the influence of filament moisture on the quality of products manufactured using the additive method using the Fused Deposition Modelling (FDM) method. Three types of thermoplastic polymers were tested: ABS, PLA and PET-G. The polymers were stored in environments with different humidity. The moisture content of the filament was determined as the water content in the material expressed as a percentage by weight. To obtain the expected humidity of the samples, they were conditioned for 7 days in tightly closed containers with constant humidity of 40%, 60% and 80%. After the sample conditioning process was completed, they were removed from the container and subjected to further tests. The influence of filament humidity on selected properties of manufactured products is presented, such as: surface quality of the obtained samples, tensile strength and dimensional repeatability. To sum up, the method of storing the filament affects the moisture content of the filament. The humidity of the filament, in turn, affects the quality of products manufactured using the FDM method, including: on: mechanical properties, dimensional stability, Surface appearance. Therefore, it is important in what conditions the filament is stored before the production process begins.

2

Fractional stochastic differential equations driven by G-Brownian motion with delays

Saci Akram, Redjil Amel, Boutabia Hacene, Kebiri Omar

Probability and Mathematical Statistics

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2023

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Vol. 43, Fasc. 1

1--21

EN

This paper consists of two parts. In part I, existence and uniqueness of solution for fractional stochastic differential equations driven by G-Brownian motion with delays (G-FSDEs for short) is established. In part II, the averaging principle for this type of equations is given. We prove under some assumptions that the solution of G-FSDE can be approximated by solution of its averaged stochastic system in the sense of mean square.

3

Expectation properties of generalized order statistics based on the Gompertz-G family of distributions

Alharbi Yousef F., Fawzy Mohamad A., Athar Haseeb

Operations Research and Decisions

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2023

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Vol. 33, No. 4

1--14

EN

Gompertz-G family of distributions has been considered. The moment properties of generalized order statistics were studied and characterization results have been presented. Further, several examples and special cases were discussed. The results can be applied to many known distributions included in this family.

4

Boundedness of G-Fractional Commutators with G-BMO functions

Elman Ibrahimov, Jafarova Ar. Saadat

Commentationes Mathematicae

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2023

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Vol. 61, No. 1/2

1--14

EN

In this paper we study (Lp,λ,ω p , Lp,λ,ωq )-boundedness of commutators of the Gegenbauer fractional integral Jα G and fractional maximal operator Mα G generated by Gegenbauer differential operator Gλ

5

Evaluation of the Influence of the Cooling Method Used During Grinding on the Operating Properties of Ceramic Grinding Wheels Made with Different Abrasives

Stachurski Wojciech, Dębkowski Ryszard, Rosik Radosław, Święcik Robert, Pawłowski Witold

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 3

1--18

EN

This article presents the results of a study of the performance characteristics of ceramic grinding wheels during peripheral grinding of flat surfaces carried out using different methods of supplying cooling and lubricating fluid (coolant). In the study, T1 type grinding wheels were used, differing in the type of abrasive used in their construction. The abrasive consisted of mixtures with different volume percentages of: 1) grains of conventional white electro-corundum, 2) grains of submicrocrystalline sintered corundum produced by sol-gel technology, 3) microcrystalline sintered ceramic grains with RECERAMAX™ RT microclasters from RECKEL. Specimens made of 145Cr6 tool steel (60±1 HRC) were ground using coolant feeding by flood method and MQL (Minimum Quantity Lubrication) method. During the study, the components of grinding force (Fn, Ft), radial loss of the grinding wheel and roughness of the ground surface were measured, which made it possible to determine the volumetric wear of the grinding wheel Vs, the total grinding power P, and then calculate the grinding indicators G and Ks. The obtained values of the G index indicate that, regardless of the type of grinding wheel used, a higher relative grinding efficiency was obtained during grinding with the delivery of coolant by the MQL method. The highest values of this index were obtained in the case of the grinding process carried out with a grinding wheel containing RECERAMAX™ RT abrasive. The Ks index confirmed the best performance of the mentioned grinding wheel. Since its value also depends on the total grinding power P and the surface roughness parameter Ra, the grinding process carried out with this grinding wheel is additionally characterized by a better quality of the obtained surface and lower energy consumption.

6

Asymptotic analysis of a closed G-network of unreliable nodes

Rusilko Tatiana

Journal of Applied Mathematics and Computational Mechanics

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2022

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Vol. 21, nr 2

91--102

EN

A closed exponential queueing G-network of unreliable multi-server nodes was studied under the asymptotic assumption of a large number of customers. The process of changing the number of functional servers in network nodes was considered as the birth-death process. The process of changing the number of customers at the nodes was considered as a continuous-state Markov process. It was proved that its probability density function satisfies the Fokker-Planck-Kolmogorov equation. The system of differential equations for the first-order and second-order moments of this process was derived. This allows us to predict the expectation, the variance and the pairwise correlation of the number of customers in the G-network nodes both in the transient and steady state.

7

Introduction to Probabilistic Concurrent Systems

Abbes Samy

Fundamenta Informaticae

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2022

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vol. 187 nr 2-4

71--102

EN

The first part of the paper is an introduction to the theory of probabilistic concurrent systems under a partial order semantics. Key definitions and results are given and illustrated on examples. The second part includes contributions. We introduce deterministic concurrent systems as a subclass of concurrent systems. Deterministic concurrent system are “locally commutative” concurrent systems. We prove that irreducible and deterministic concurrent systems have a unique probabilistic dynamics, and we characterize these systems by means of their combinatorial properties.

8

Characterizations of quasi-metric and G-metric completeness involving w-distances and fixed points

Karapınar Erdal, Romaguera Salvador, Tirado Pedro

Demonstratio Mathematica

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2022

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Vol. 55, nr 1

939--951

EN

Involving w-distances we prove a fixed point theorem of Caristi-type in the realm of (non-necessarily T1) quasi-metric spaces. With the help of this result, a characterization of quasi-metric completeness is obtained. Our approach allows us to retrieve several key examples occurring in various fields of mathematics and computer science and that are modeled as non- T1 quasi-metric spaces. As an application, we deduce a characterization of complete G -metric spaces in terms of a weak version of Caristi’s theorem that involves a G-metric version of w-distances.

9

Throwback

Gambarelli Gianfranco

Control and Cybernetics

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2022

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Vol. 51, No. 2

125--130

EN

With this short composition, I’d like to share with you a few events of my scientific life.

10

Approximation models for the evaluation of TCP/AQM networks

Marek Dariusz, Domański Adam, Domańska Joanna, Szyguła Jakub, Czachórski Tadeusz, Klamka Jerzy, Filus Katarzyna

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 4

art. no. e141986

EN

The article proposes a model in which Diffusion Approximation is used to analyse the TCP/AQM transmission mechanism in a multinode computer network. In order to prevent traffic congestion, routers implement AQM (Active Queue Management) algorithms. We investigate the influence of using RED-based AQM mechanisms and the fractional controller PIγ on the transport layer. Additionally, we examine the cases in which the TCP and the UDP flows occur and analyse their mutual influence. Both transport protocols used are independent and work simultaneously. We compare our solution with the Fluid Flow approximation, demonstrating the advantages of Diffusion Approximation.

11

Fixed point sets of smooth G-manifolds pseudo-equivalent to a G-template

Pawałowski Krzysztof M., Pulikowski Jan

Bulletin of the Polish Academy of Sciences. Mathematics

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2022

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Vol. 70, no. 2

173--186

EN

For a finite group G not of prime power order, Oliver (1996) answered the question which manifolds occur as the fixed point sets of smooth actions of G on disks (resp., Euclidean spaces). We extend Oliver’s result to compact (resp., open) smooth G-manifolds M pseudo-equivalent to Y, a finite Z-acyclic G-CW complex such that the fixed point set YG is non-empty, connected, and χ(YG)≡1(modnG), where nG is the Oliver number of G. We prove that the answer to the question above does not depend on the choice of Y. For a finite connected G-CW complex Y such that YG is non-empty and connected, called a G-template, we prove that a compact stably parallelizable manifold F occurs as the fixed point set MG of a compact smooth G-manifold M pseudo-equivalent to Y if and only if χ(F)≡χ(YG)(modnG). Moreover, there exists a compact smooth fixed point free G-manifold pseudo-equivalent to a G-template Y if and only if χ(YG)≡0(modnG). In particular, similarly to actions on disks, there exists a compact smooth fixed point free G-manifold pseudo-equivalent to the real projective space RP2n for an integer n≥1 if and only if G is an Oliver group. Finally, we prove that each finite Oliver group G has a smooth fixed point free action on RP2n itself for some integer n≥1.

12

G-Force Test Stand for the Evaluation of Weapon Component Strength

Gołoś Damian, Jasiński Michał, Zawada Paweł, Noga Janusz

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2021

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Vol. 12, Nr 4 (46)

43--56

EN

This paper discusses the design of a G-force test stand intended to examine of the effects of mechanical loads present during firing of a weapon and applied to the electronic components contained in the 155 mm calibre guided projectile. The G-force test stand is used to develop and test the effects of using high mechanical loads by decelerating a test specimen through the use of a purpose-designed fender assembly. For the purpose of testing, it is irrelevant whether a load is developed by acceleration or deceleration of the test specimen, as a test result obtained by the deceleration of a test specimen is equivalent to a test result obtained by the acceleration of a test specimen, as used in a 155 mm calibre artillery guided projectile. The G-force test stand was used to test and determine the velocities developed by the test specimens and the G-forces applied to them. The maximum velocity to which a test specimen was accelerated was approx. 72 m/s. The test stand was able to propel the test specimens to velocities an order of magnitude higher than the velocities obtained with a Kast and Masset ram. The tests were performed with rubber and copper fender assemblies. The effect of the specific fender used was demonstrated on the trend of the generated G-force. The test stand could develop G-forces in excess of 10,000 with a duration of more than 500 µs.

PL

W niniejszej pracy omówiono konstrukcję stanowiska do badań wpływu przeciążeń występujących podczas wystrzału z armaty na elementy elektroniki umieszczone w pocisku kierowanym kal. 155 mm. Na stanowisku do generacji i badań przeciążeń, wysokie przeciążenie powstaje w wyniku wyhamowania badanej próbki na specjalnie dobranym odbijaczu. Dla celów badawczych nie ma to znaczenia czy przeciążenie powstanie w wyniku rozpędzenia czy też spowolnienia badanej próbki, dlatego wynik badania powstałego na skutek spowolnienia próbki jest tożsamy z wynikiem powstałym na skutek przyśpieszenia próbki, tak jak to ma miejsce w armacie kal. 155 mm. Na stanowisku do generacji i badań przeciążeń przeprowadzono testy, mające na celu zarówno określenie prędkości uzyskiwanych przez badaną próbkę, jak i przeciążeń na nią działających. Maksymalna prędkość do jakiej rozpędzono próbkę wyniosła ok. 72 m/s. Stanowisko pozwala na rozpędzenie badanych elementów do o rząd wyższych prędkości od tych, uzyskiwanych na kafarze Kasta i Masseta. Przeprowadzono badania dla odbijaczy gumowych i miedzianych. Wykazano wpływ zastosowanego odbijacza na kształt charakterystyki uzyskiwanego przeciążenia. Stanowisko pozwala na uzyskiwanie przeciążeń o wartościach powyżej 10000 i czasach trwania powyżej 500 µs.

13

Analysis of welding and sealing joining methods of single-polymer composite materials in a hot air stream

Ewelina Kostecka

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2020

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nr 64 (136)

45--51

EN

This article presents joining methods (welding and sealing) of single-polymer composite materials in a hot air stream. The research material was created using the film-stacking method, which involves pressing successive fractions of polyethylene terephthalate-modified with glycol (PET-G) at defined technological conditions, such as pressure, temperature, and time. Joining method analysis was carried out based on the tensile test results. Analysis of the obtained results showed that the properties of the overlapped weld joint were the best because they were closest to the original materials. In contrast, PET-G welded joint properties were the worst because the PET-G welded joint does not contain fibers, which enhanced the weld; therefore, the fastest breakage of the material was observed at the welding location. For the overlapped weld, the weld itself is more resistant because the joint surface is influenced by friction forces between joined materials.

14

Sondy fluorescencyjne typu „light up” do detekcji i obrazowania G-kwadrupleksów in vitro i in vivo. Cz. 1 i 2

Baranowski Daniel

Wiadomości Chemiczne

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2020

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[Z] 74, 11-12

883--901

EN

G-quadruplexes are non-canonical guanosine rich four stranded nucleic acids structures consisting of at least two or more G-tetrads stabilized by an array of Hoogsteen hydrogend bonds and monovalent cations. The distinguishing feature of the G-quadruplexes is their high thermal stability and structural polymorphism in aqueous media. In parallel, a great number of GQ structures have been extensively surveyed ex vivo by means of biophysical techniques such as nuclear magnetic resonance (NMR) spectroscopy, circular dichroism (CD) spectroscopy, and X-ray crystallography. Accumulating evidence suggesting that G-quadruplexes play essential role in a numerous biological processes in vivo, including DNA replication and transcription, RNA translation as well as genomic maintenance. Consequently, G-quadruplexes has attracted attention as therapeutic targets in cancer or hereditary diseases as well as molecular target in cellular biology. Study on G-quadruplexes:ligand interaction by NMR, CD, UV and fluorescence spectroscopy in vitro or in vivo has become an intensive research work area of many groups in recent years. Nowadays, there are available large amount of organic compounds that selectively bind to G-quadruplexes and their photophysical and kinetic properties were comprehensively characterized but only few of them are endowed with fluorescence properties that could be applicable as fluorescent probes in cellular biology or in vitro detection. Interestingly, the group of these fluorescent probes is characterized by a vast structural diverisity resulting from the different way of interaction with G-quadruplexes as well as G-quadruplex polymorphism. This review focuses on the G-quadruplex-selective light up fluorescent probes that have been employed for in vitro detection as well as cellular imaging along with a summary of the key photophysical, biophysical, and biological properties of reported examples.

15

A remark on the distribution of products of independent normal random variables

Szczepański Jerzy

Science, Technology and Innovation

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2020

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Vol. 10, no. 3

30--37

EN

We present a proof of the explicit formula of the probability density function of the product of normally distributed independent random variables using the multiplicative convolution formula for Meijer G functions.

16

Analysis of artefacts in EEG signal registered during anti-G straining maneuvers

Kołodziej Marcin, Kowalczuk Krzysztof Paweł, Majkowski Andrzej, Tarnowski Paweł, Gaździński Stefan, Rak Remigiusz Jan

Przegląd Elektrotechniczny

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2020

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R. 96, nr 1

124--128

EN

An anti-G straining maneuver (AGSM) is an essential element of training pilots of high-maneuver aircrafts. Electroencephalographic signal (EEG) registered during such maneuvers could be used to detect cerebral ischemia. AGSM involves complicated physical tasks, from stretching certain parts of muscles through adequate breathing. This results in the creation of extremely large muscle artefacts, which significantly disrupt the recorded EEG signals. The presented research concerned EEG signals, recorded during individual AGSM phases, inside an overload centrifuge. The largest artefacts in the EEG band (0.5-300Hz) were observed for the electrodes Fp1, F9, FT9 and EMG1 located on cheek. The signal from the Cz and Pz electrodes appeared to be the least disturbed.

PL

Manewr przeciw-przeciążeniowy (AGSM) jest niezbędnym elementem szkolenia pilotów samolotów wysokomanewrowych. Sygnał elektroencefalograficzny (EEG) zarejestrowany podczas tych manewrów mógłby posłużyć do wykrycia niedokrwienia mózgu. Manewr przeciwprzeciążeniowy, obejmuje skomplikowane zadania fizyczne, od napinania pewnych partii mięśni, poprzez odpowiednie oddychanie. Powoduje to powstanie ekstremalnie dużych artefaktów odmięśniowych, które zakłócają, w sposób znaczący, rejestrowane sygnały EEG. Zaprezentowane badania dotyczyły sygnałów EEG zarejestrowanych podczas wykonywania poszczególnych faz AGSM, we wnętrzu wirówki przeciążeniowej. Największe artefakty w paśmie EEG (0.5-300Hz) zaobserwowano dla elektrod Fp1, F9, FT9 oraz EMG1 ulokowanej na policzku. Najmniej zakłócony okazał się sygnał zarejestrowany z elektrod Cz i Pz.

17

Experimental research on energy-size distribution model of coal particle bed comminution

Zhou Qiang, Guo Qing, Pan Yongtai, Zhu Changyong, Wei Yinghua

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 5

772--783

EN

In order to accurately predict the particle size distribution (PSD) of coal particle bed comminution under different applied pressures, the tests of two kinds of coal with four size fractions under five different applied pressures were carried out by TAW-3000 hydraulic servo testing machine. The Gaudin-Schumann(G-S) distribution is extended by the fractal theory and the JK size-dependent breakage model is discussed. Two mathematical models for predicting PSD of crushing products in coal particle bed comminution are proposed. Results show that the relationship between the mass-specific energy and applied pressure is linear. Because of the protective effect of fine particles, the change of particle size modulus d0 in G-S distribution is not significant, while the distribution parameter α decreases logarithmically with the increase of mass-specific energy. With the decrease of size fraction, the crushability of coal particle bed decreases, and a master curve can be used to fit the comminution characteristics of coal particle bed with different size fractions. The extended G-S distribution model and the JK size-dependent breakage model have better fit the results of coal particle bed comminution. This research provides a useful reference for the mathematical modelling of coal particle bed comminution.

18

Fractional p&q-Laplacian problems with potentials vanishing at infinity

Isernia Teresa

Opuscula Mathematica

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2020

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Vol. 40, no. 1

93--110

EN

In this paper we prove the existence of a positive and a negative ground state weak solution for the following class of fractional p&g-Laplacian problems [formula] where [formula]and [formula] are continuous, positive functions, allowed for vanishing behavior at infinity, ƒ is a continuous function with quasicritical growth and the leading operator [formula] , with t ∈ {p, q}, is the fractional t-Laplacian operator.

19

Time period based COPRAS-G method : application on the Logistics Performance Index

Mercangoz Burcu Adiguzel, Yildirim Bahadır F., Yildirim Sultan Kuzu

LogForum

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2020

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Vol. 16, no. 2

239--250

EN

Background: Logistics is vital for the trades of countries. The inputs such as raw materials and energy that is needed for production and also the outputs of these processes are transported and distributed effectively as a result of an efficient logistics process. In order to measure the logistics performance of countries, The World Bank (WB) is publishing an index entitled Logistics Performance for every two years. Methods: The main value of this study is to provide logistics performance scores of the selected countries for a selected time period. Thus, periodic evaluations can be done for a selected time period. The grey numbers are used for determining a new dataset for a time period and implement to Complex Proportional Assessment of Alternatives (COPRAS) method. 28 European Union (EU) member states plus 5 EU Candidate Countries are ranked by using the COPRAS-Grey (COPRAS-G) method according to their logistics performance scores. In order to see if the ranking calculated by COPRAS-G is representing the past index data, the bilateral comparisons of the rankings are investigated by using the Spearman Rank and Kendall’s Tau Correlation methods. Results: The results showed that the dataset obtained by using grey numbers represent the LPI scores of the countries for the selected time period. Although there are slight differences between the Spearman and Kendall correlation coefficients, the ultimate result is the same. The ranking calculated by COPRAS-G has the strongest relationship with all rankings published by WB. Conclusions: By using the grey numbers combined with the COPRAS-G method, the LPI of Countries can be evaluated for a time period.

PL

Wstęp: Logistyka jest istotną częścią handlu wielu krajów. Wkład w postaci surowców oraz energii jest niezbędny w procesie produkcji, wymaga on jednak najczęściej transportu, tak samo jak i wyroby finalne uzyskanie w procesie produkcji, zrealizowanego w efektywny sposób jako element całego procesu logistycznego. W celu pomiaru tego procesu w różnych krajach, Bank Światowy publikuje w okresach dwuletnich dane dotyczące aktywności logistycznych. Metody: Podstawowym celem tej pracy jest dostarczenie oceny działalności logistycznej wybranych krajów w wybranym okresie czasu. Liczby szare są stosowane do określenia danych dla danego okresu oraz zastosowania metody Complex Proportional Assessment of Alternatives (COPRAS). Stworzono ranking sprawności logistycznej obejmujący 28 państw członkowskich UE oraz 5 państw kandydujących do EU. W celu oszacowania poprawności danych wyliczonych przy pomocy metody COPRAS, wykonano podwójne porównanie otrzymanych rankingów przy użyciu metod Spearman Rank oraz korelacji Kendalla Tau. Wyniki: Uzyskane wyniki pokazują, że dane otrzymane poprzez użyciu liczb szarych reprezentują dane LPI badanych krajów w wybranym okresie. Występujące różnice, ujawnione w postaci współczynników korelacji Spearman i Kendall, nie są istotne. Ranking uzyskany w oparciu o metodę COPRAS-G wykazuje silną korelację ze wszystkimi rankingami publikowanymi przez Bank Światowy. Wnioski: Wskaźnik LPI dla wybranych krajów na założony okres został wyliczony poprzez zastosowanie liczb szarych w połączeniu z metodą COPRAS-G.

20

Kinetics of oxidation of manganese by potassium permanganate and chloride in the Velekinca water treatment plant, Kosovo

Beluli Valdrin M.

Journal of Water and Land Development

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2020

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no. 47

30--37

EN

Our scientific research is based on oxidation reactions and monitoring of chemical reaction kinetics in the Velekinca groundwaters plant in Gjilan municipality, Kosovo. The GW of this plant contains high concentration of manganese so we need to use potassium permanganate (KMnO4) as one of the most power oxidants in the water treatment plant. In our research the high concentration of Mn in groundwaters is 0.22–0.28 mg∙dm–3 and this concentration is not in accordance with the WHO. Chlorine is one of the most common disinfectants used in the water treatment industry because it has a low cost and immediate effect on the destruction of microorganisms, the concentration of chlorine (Cl2) in our research is 0.1–0.32 mg∙dm–3. The speed of chemical reactions in the technology of GW is extremely important because sometimes in the elimination of chemical pollutants using oxidizing agents often form intermediate species. The speed of reactions indicates how fast chemical bonds are formed in the creation of a product, and this depends on the rate of reaction (XA). The focus for the research is to study the potassium permanganate and chlorine gas reactions in water if it forms intermediate products (intermediate species) due to the high speed of reactions. Scientific research conclusion, intermediate species in the oxidation reactions of Mn and water disinfection with Cl2(g) it is impossible to cause a high rate of chemical reactions from the reaction rate (XA = 1%) to the reaction rate (XA = 99%). The maximum speed at the highest XA Cl2 is from 4.405∙10–11 to 8.87∙10–10 mol∙dm–3∙s–1, while at Mn is (2.030–4.034)∙10–7 mol∙dm–3∙s–1.