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Wyszukujesz frazę "diffusion" wg kryterium: Temat


Tytuł:
Analysis of the possibility of shaping the sound diffusion coefficient of diffusers based on acoustic metamaterials
Autorzy:
Rubacha, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/2202416.pdf
Data publikacji:
2022
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
metamaterial
sound diffusion
diffusion coefficient
metamateriał
dyfuzja dźwięku
współczynnik dyfuzji
Opis:
The article presents the analysis of the possibilities of using acoustic metamaterial to build sound diffusers. The diffusers composed of slots loaded with a curved quarter-wave resonator were investigated. Such solutions induce dispersion and the slow sound effect to increase the effective depth of the quarter-wave resonator. The sound diffusion coefficient was calculated with the use of numerical models of diffusers. Next, obtained results were compared with the Schroeder diffuser. In conclusion, it was shown, that acoustic metamaterials affect the frequency band of the diffuser and the effectiveness of the obtained sound diffusers depend on relative width of slits.
Źródło:
Vibrations in Physical Systems; 2022, 33, 2; art. no. 2022210
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sound diffuser made of acoustic metamaterial: numerical and experimental investigation
Autorzy:
Rubacha, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/2146653.pdf
Data publikacji:
2021
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
metamaterial
sound diffusion
diffusion coefficient
metamateriał
dyfuzja dźwięku
współczynnik dyfuzji
Opis:
The use of metamaterials in room acoustics is becoming more and more popular. Their advantage is the possibility of adjusting the parameters of the systems in the desired frequency range and the reduction of dimensions compared to the existing solutions. This paper discusses the numerical design and experimental verification of sound diffuser based on the acoustic metamaterials: a slit with added quart-wave length resonator. The transfer matrix method is used to make a numerical model of the metamaterial cell, which was used to build a model of a diffuser composed of N = 7 cells. Then, the dimensions of the diffuser were optimized to obtain the sound diffusion in a wide frequency range. The sound dispersion coefficient was also calculated using the FEM method. The numerical results were compared with the measurements and it was shown that it is possible to make a broadband sound diffuser with the use of metamaterials.
Źródło:
Vibrations in Physical Systems; 2021, 32, 2; art. no. 2021207
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Alternative methodology to determine effective coefficient of methane diffusion in coal
Autorzy:
Koptoń, Henryk
Powiązania:
https://bibliotekanauki.pl/articles/1839042.pdf
Data publikacji:
2020
Wydawca:
Główny Instytut Górnictwa
Tematy:
mining
coal
sorption
diffusion
methane
diffusion coefficient
górnictwo
węgiel
sorpcja
dyfuzja
metan
współczynnik dyfuzji
Opis:
The article presents the results of research in to the development of an alternative method of determining the effective coefficient of methane diffusion in coal, based on a mathematical model following Fick's second law. The research was conducted based on the recorded courses of methane sorption kinetics in coal samples obtained in laboratory conditions with the precise gravimetric sorption system IGA-001. The value of the coefficient was treated as an element tuning the model in such a way that the average relative error of the ex post was as small as possible. Model verification indicated the correctness of its assumptions. The development of a more accurate methodology to determine the effective coefficient of methane diffusion in coal will enable the verification of the models applied in order to describe the physical and chemical mechanisms of the methane desorption natural phenomenon. It will also pave the way for further research aimed at the determination of: the gas bearing capacity of coal seams, the degree of degassing of seamswhich results from the mining operations being conducted; or to what extent it is possible to degas the deposits.
Źródło:
Journal of Sustainable Mining; 2020, 19, 2; 88-95
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurements of plasma diffusion coefficient in Pilot-PSI device using Katsumata probe
Autorzy:
Solomon, M. L.
Mihaila, I.
Anita, V.
Costin, C.
Popa, G.
van der Meiden, H.
Al, R.
van Rooij, G.
Cardozo, N. L.
Rapp, J.
Ionita, C.
Stärz, R.
Schrittwieser, R.
Powiązania:
https://bibliotekanauki.pl/articles/385269.pdf
Data publikacji:
2009
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
Katsumata probe
magnetized plasma
diffusion coefficient
Opis:
Cross-field transport of particles and energy is a major issue in magnetized fusion-relevant plasmas, due to its relevance for plasma confinement. In this paper Katsumata probe measurements performed in Pilot-PSI linear magnetized plasma device are presented. The plasma diffusion coefficient in perpendicular direction to the magnetic field was estimated from the measurements.
Źródło:
Journal of Automation Mobile Robotics and Intelligent Systems; 2009, 3, 4; 160-162
1897-8649
2080-2145
Pojawia się w:
Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena współczynnika dyfuzji par węglowodorów w gruncie
Prediction of diffusion coefficient of hydrocarbon vapour in soil
Autorzy:
Fąfara, Z.
Powiązania:
https://bibliotekanauki.pl/articles/300210.pdf
Data publikacji:
2010
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
grunt sypki
migracja węglowodorów
dyfuzja par węglowodorów
współczynnik dyfuzji
loose soil
hydrocarbon migration
hydrocarbon vapour diffusion
diffusion coefficient
Opis:
Podczas migracji substancji ropopochodnej w gruncie, w pewnych sytuacjach dyfuzja par węglowodorów może odgrywać istotną rolę, decydując o zasięgu skażenia oraz stwarzając niebezpieczeństwo wybuchu. Z tego względu konieczna jest znajomość prędkości dyfuzji par węglowodorów w przestrzeni porowej gruntu dla właściwej oceny tych zagrożeń. Wykonano pomiary laboratoryjne prędkości dyfuzji par węglowodorów w specjalnie wyselekcjonowanych modelach ośrodka gruntowego. Źródło węglowodorów stanowiła etylina. Stwierdzono, że współczynnik dyfuzji silnie zależy od rodzaju gruntu. Następnie metodami statystycznymi dopasowano zależność regresyjną pozwalającą na ocenę współczynnika dyfuzji par węglowodorów na podstawie parametrów opisujących skład granulometryczny gruntu - powierzchnia właściwa gruntu i średnica efektywna ziaren. Uzyskane równania cechują się bardzo wysokim stopniem dopasowania do danych eksperymentalnych i z powodzeniem mogą być użyte podczas numerycznego modelowania procesu migracji węglowodorów w gruncie.
Diffusion of hydrocarbon vapour can be sometimes very important during numeric modeling of migration of oil contaminations in the soil. It decides on pollution range and zone of danger of explosion. Therefore, acquaintance of diffusion speed of hydrocarbon vapour in soil is indispensable for proper estimate these threats. There are made some laboratory measurements of diffusion speed of hydrocarbon vapour in specially selected models of soil. The ethylene was the hydrocarbon source. As it happens, that the diffusion coefficient is depends on kind of soil very strong. Next it was adjusted the regressive dependence to estimate the diffusion coefficient of hydrocarbon vapour using soil composition parameters - the pore surface and the effective diameter of grains. Get are featured for pilot data equaling very high degree of adjusting and there can be used with success during the numeric modeling process of migration of hydrocarbon in soil.
Źródło:
Wiertnictwo, Nafta, Gaz; 2010, 27, 1--2; 147-154
1507-0042
Pojawia się w:
Wiertnictwo, Nafta, Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shaping optimal zinc coating on the surface of high-quality ductile iron casting. Part II – Technological formula and value of diffusion coefficient
Autorzy:
Kopyciński, D.
Guzik, E.
Szczęsny, A.
Powiązania:
https://bibliotekanauki.pl/articles/352224.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hot-dip galvanizing
ductile iron
surface roughness
diffusion coefficient
Opis:
The completed research presented in the first part of the article has allowed linking the manufacturing technology of ductile iron castings with the process of hot dip galvanizing. On the basis of these data simulations were carried out to examine the behaviour of zinc diffusion coefficient D in the galvanized coating. The adopted model of zinc coating growth helped to explain the cases of excessive growth of the intermetallic phases in this type of coating. The paper analyzes covered the relationship between the roughness and phase composition of the top layer of product and the thickness and kinetics of zinc coating growth referred to individual sub-layers of the intermetallic phases.Roughness and phase composition in the surface layer of product were next related to the diffusion coefficient D examined in respective sublayers of the intermetallic phases.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 1; 391-395
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shaping optimal zinc coating on the surface of high-quality ductile iron casting. Part I – Moulding technologies vs. zinc coating
Autorzy:
Szczęsny, A.
Kopyciński, D.
Guzik, E.
Powiązania:
https://bibliotekanauki.pl/articles/356585.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hot-dip galvanizing
ductile iron
surface roughness
diffusion coefficient
Opis:
Studies have demonstrated that in the process of hot dip galvanizing the decisive influence on the mechanism of zinc coating formation and properties has the quality of the mechanically untreated (raw) surface layer of the galvanized product. The terms “casting surface layer” denote various parameters of the microstructure, including the type of metal matrix, the number of grains and the size of graphite nodules, possible presence of hard spots (the precipitates of eutectic cementite) and parameters of the surface condition. The completed research has allowed linking the manufacturing technology of ductile iron castings with the process of hot dip galvanizing.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 1; 385-390
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculation of electrochemical parameters starting from the polarization curves of ferrocene at glassy carbon electrode
Autorzy:
Neghmouche, N.S.
Lanez, T.
Powiązania:
https://bibliotekanauki.pl/articles/411587.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
cyclic voltammetry
diffusion coefficient
ferrocene
half-wave potential
Randles-Sevcik equation
Opis:
This work is a contribution to the calculation of electrochemical parameters from the polarization curves of ferrocene. The parameters are: The anodic (Epa) and the cathodic (Epc) peak potentials, as well as the corresponding anodic (ipa) and cathodic (ipc) peak currents, were obtained at different scan rates (0.05, 0.10, 0.30, 0.50 V.s-1). The half-wave potentials (E1/2) of the couple in the investigated solvents have been evaluated. The diffusion coefficients (D) have been calculated using the Randles-Sevcik equation.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 4; 37-45
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Hydrazide group on the oxydation of ferrocene at two different electrodes using Rotating Disk Electrode (RDE) in organic medium
Autorzy:
Nacer, S. N.
Lanez, T.
Powiązania:
https://bibliotekanauki.pl/articles/412271.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Rotating Disk Electrode (RDE)
diffusion coefficient
ferrocene derivative
half-wave potential
Opis:
Through this work we adopted Rotating Disk Electrode (RDE) Voltammetry to study the kinetics of oxidation and the effect of hydrazide group on ferrocene in organic medium. Thus, two different electrodes (Pt and Ge) were used in order to determine this latter. According to the ferrocene taken as a witness the hydrazide group related to the ferrocene made oxidation more difficult. This ferrocenic derivative showed an electrochemical stability, a reversible electrochemical system and an electronic attractor effect of these substitutional ferrocene groups. Finally, we calculated some electrochemical parameters which were: the diffusion coefficients (D), the layer thickness in addition to the electron transfer rate.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 7, 1; 1-7
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of Values of Diffusion Coefficient on Results of Diffusion Modelling Driven by Chemical Potential Gradien
Autorzy:
Wróbel, Marek
Burbelko, Andriy
Powiązania:
https://bibliotekanauki.pl/articles/2174626.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
foundry industry
application of information technology
diffusion modelling
Calphad method
chemical potential
diffusion coefficient
przemysł odlewniczy
zastosowanie technologii informatycznej
modelowanie dyfuzyjne
metoda Calphad
potencjał chemiczny
współczynnik dyfuzji
Opis:
In the paper critical role of including the right material parameters, as input values for computer modelling, is stressed. The presented model of diffusion, based on chemical potential gradient, in order to perform calculations, requires a parameter called mobility, which can be calculated using the diffusion coefficient. When analysing the diffusion problem, it is a common practice to assume the diffusion coefficient to be a constant within the range of temperature and chemical composition considered. By doing so the calculations are considerably simplified at the cost of the accuracy of the results. In order to make a reasoned decision, whether this simplification is desirable for particular systems and conditions, its impact on the accuracy of calculations needs to be assessed. The paper presents such evaluation by comparing results of modelling with a constant value of diffusion coefficient to results where the dependency of Di on temperature, chemical composition or both are added. The results show how a given deviation of diffusivity is correlated with the change in the final results. Simulations were performed in a single dimension for the FCC phase in Fe-C, Fe-Si and Fe-Mn systems. Different initial compositions and temperature profiles were used.
Źródło:
Archives of Foundry Engineering; 2022, 22, 3; 81--90
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrochemical properties of N'-ferrocenylmethyl-N'-phenylbenzohydrazide in aqueous and organic mediums
Autorzy:
Nacer, S.N.
Lanez, T.
Powiązania:
https://bibliotekanauki.pl/articles/411788.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
cyclic voltammetry
diffusion coefficient
ferrocene derivative
half-wave potential
Randles-Sevcik equation
Opis:
We carried out a detailed study of the kinetics of oxidation of N'-ferrocenylmethyl-N'-phenylbenzohydrazide (FcX) to ferrocenium ion (FcX+) in aqueous and organic mediums. This study using cyclic (CV) and rotating disk electrode (RDE) voltammetry showed that the FcX/FcX+ redox couple is reversible. The N'-ferrocenylmethyl-N'-phenylbenzohydrazide and ferrocenium ion diffusion coefficients (D) were calculated from these results. In addition, the electron transfer rate constant and the exchange current density for the oxidation of ferrocene were determined. A comparison of the kinetic data obtained from the two electrochemical techniques appears to show that the data from the RDE experiments are more reliable because they are collected under strict mass transport control.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 5; 76-85
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diffusion Coefficient in the Zinc Coating Shaped on the Surface of Cast Iron and Steel Alloys
Autorzy:
Kopyciński, D.
Guzik, E.
Szczęsny, A.
Siekaniec, D.
Powiązania:
https://bibliotekanauki.pl/articles/379933.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hot-dip galvanizing
intermetallic sublayer
diffusion coefficient
cynkowanie zanurzeniowe
podwarstwa międzymetaliczna
współczynnik dyfuzji
Opis:
The article presents the method to assess the diffusion coefficient D in the sub-layer of intermetallic phases formed during hot-dip galvanizing “Armco” iron and ductile cast iron EN-GJS-500-7. Hot-dip galvanizing is one of the most popular forms of long-term protection of Fe-C alloys against corrosion. The process for producing a protective layer of sufficient quality is closely related to diffusion of atoms of zinc and iron. The simulation consist in performed a hot-dip galvanizing in laboratory condition above Fe-C alloys, in the Department of Engineering of Cast Alloys and Composites. Galvanizing time ranged from 15 to 300 seconds. Then metallographic specimens were prepared, intermetallic layers were measured and diffusion coefficient (D) were calculated. It was found that the diffusion coefficient obtained during hot-dip galvanizing “Armco” iron and zinc is about two orders of magnitude less than the coefficient obtained on ductile cast iron EN-GJS-500-7.
Źródło:
Archives of Foundry Engineering; 2015, 15, 2; 43-46
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Small high density lipoprotein subclasses: some of their physico-chemical properties and stability in solution.
Autorzy:
Atmeh, Ragheb
Abd Elrazeq, Issa
Powiązania:
https://bibliotekanauki.pl/articles/1041440.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
small high density lipoproteins
diffusion coefficient
surface charge
molecular shape
coefficient of friction
stability
Opis:
Small high density lipoproteins (SHDL) contribute to the protection from atherosclerosis, but detailed information about their properties is not available yet. We isolated four of the smallest HDL subclasses that contain apoA-I alone, the small lipoprotein A-I (SLpAI), by their separation on gradient polyacrylamide gel followed by electroelution. Their physico-chemical properties were calculated from their displacement in non-denaturing gradient polyacrylamide gel under the effect of electrical potential. The properties are: Stokes' radii 2.96-3.56 nm; molecular masses 42-70 kDa; net negative charge 7.2-13.5; surface charge densities 3139-4069 -esu∙˙cm^(-2); surface potentials 10.6-15.7 -mV; coefficients of friction 5.74-6.90 × 10-8 g∙˙s^(-1); and diffusion coefficients 5.76-6.94 7× 10-7 cm^2∙˙s^(-1). We found that these particles were of low stability as they underwent molecular transformation into larger particles on storage. The estimated dimensions of these particles do not support ellipsoidal shape, therefore, the most probable shape is spherical; consequently, their hydrated characteristics were estimated. We conclude that these particles have high values of negative surface charge and diffusion coefficients, and are of low stability. Their small Stokes' radii were similar to each other and they are spherical and highly hydrated.
Źródło:
Acta Biochimica Polonica; 2005, 52, 2; 515-525
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculation of Diffusion Coefficients for Oxidation of ferrocene derivative synthesized at two different electrodes using Rotating Disk Electrode (RDE)
Autorzy:
Nacer, S.N.
Khelef, A.
Lanez, T.
Powiązania:
https://bibliotekanauki.pl/articles/411798.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Rotating Disk Electrode (RDE)
diffusion coefficient
ferrocene derivative
half-wave potential
Randles-Sevcik equation
Opis:
The electrochemical behavior of N'-Ferrocenylmethyl-N'-Phenylbenzohydrazide synthesized is studied by Rotating Disk Electrode (RDE) Voltammetry to study the kinetics of oxidation and the effect of hydrazide group on ferrocene in organic medium. Thus, two different electrodes (Pt and Gc) were used in ordre to determine this latter. According to the ferrocene taken as a witness the hydrazide group related to the ferrocene made oxydation more difficult. This ferrocenic derivative showed an electrochemical stability, a reversible electrochemical system and an electronic attractor effect of these substitutional ferrocene groups. Finally, we calculated some electrochemical parameters which were: the diffusion coefficients (D), the layer thickness in addition to the electron transfer rate.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 9, 1; 39-47
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wyznaczanie współczynnika dyfuzji kompleksu kobaltu z kwasem di(2-etyloheksylo)fosforowym (D2EHPA) w toluenie z wykorzystaniem hiperspektralnego obrazowania cyfrowego oraz metody elementów skończonych
Determination of diffusion coefficient of cobalt complex with di(2-ethylhexyl)phosphoric acid (D2EHPA) in toluene using Hyperspectral Digital Imaging and Finite Element Method (FEM)
Autorzy:
Stasiak, M.
Bogacki, M.
Górski, Z.
Musielak, G.
Szłapka, M.
Żywek, E.
Powiązania:
https://bibliotekanauki.pl/articles/2072042.pdf
Data publikacji:
2014
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
współczynnik dyfuzji
obrazowanie cyfrowe
metoda elementów skończonych
optymalizacja
diffusion coefficient
digital imaging
finite element method
optimization
Opis:
W pracy zaproponowano metodę wyznaczania współczynnika dyfuzji. Metoda ta polega na określeniu rozkładów przestrzennych stężenia badanych związków w czasie za pomocą hiperspektralnego obrazowania cyfrowego. Następnie otrzymane rozkłady są porównywane z rozwiązaniami numerycznymi równania dyfuzji. Rozwiązania te są otrzymywane za pomocą MES. Współczynnika dyfuzji poszukuje się wykorzystując optymalizacyjne rozwiązanie zagadnienia odwrotnego. W pracy wyznaczono współczynnik dyfuzji wybranego związku w toluenie.
A method for the determination of diffusion coefficient is proposed in the paper. The method deals with finding out the spatial concentration distribution of compounds using hyperspectral digital imaging. Then, the obtained distributions are compared with numerical solutions of diffusion equation. These solutions are obtained by using FEM. The diffusion coefficient is sought applying the optimization solution of inverse problem. The diffusion coefficient of selected compound in toluene was determined.
Źródło:
Inżynieria i Aparatura Chemiczna; 2014, 1; 38--39
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł

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