Wyniki wyszukiwania - Biblioteka Nauki

1

An Inverse Method to Obtain Porosity, Fibre Diameter and Density of Fibrous Sound Absorbing Materials

100%

Alba J. , del Rey R. , Ramis J. , Arenas J. P.

Archives of Acoustics

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2011

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tom Vol. 36, No. 3

561-574

EN

Characterization of sound absorbing materials is essential to predict its acoustic behaviour. The most commonly used models to do so consider the flow resistivity, porosity, and average fibre diameter as parameters to determine the acoustic impedance and sound absorbing coefficient. Besides direct experimental techniques, numerical approaches appear to be an alternative to estimate the material's parameters. In this work an inverse numerical method to obtain some parameters of a fibrous material is presented. Using measurements of the normal incidence sound absorption coefficient and then using the model proposed by Voronina, subsequent application of basic minimization techniques allows one to obtain the porosity, average fibre diameter and density of a sound absorbing material. The numerical results agree fairly well with the experimental data.

2

Use of burshtyn TPP ash for the production of expanded gas concrete

100%

Koshlak H.

Journal of New Technologies in Environmental Science

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2021

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tom Vol. 5, nr 2

82--88

EN

Production of not autoclave porous concrete, including small enterprises, industry of wall materials, which is now the most dynamically developing. One of the main problems in the production of gas concrete and concrete products is a comprehensive savings of cement, while ensuring high quality designs. Technology of gas concrete to date has at its disposal wide range of techniques that allow in specific conditions to reduce the specific consumption of cement without compromising technical properties of concrete. In recent years, for this purpose proposed in plasticized concrete mixtures using active mineral fillers. In this area gained considerable practical experience of application additives ash - removal, slags, carbonaceous materials, silica sand. Classical technology of these concrete based mainly on cement and unground sand. The use of TPP ash for cellular concrete is recommended by most of normative documents. The greatest effect is achieved by using high calcium ash.

3

Charakterystyka strukturalna złoża materiałów porowatych o mikrometrycznych wymiarach ziaren

100%

Vogt E. , Buczek B.

Inżynieria Chemiczna i Procesowa

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2006

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tom T. 27, z. 2

421-430

PL

Wyznaczano porowatość cząstki oraz porowatość złoża materiałów o mikrometrycznych wymiarach ziaren 0-100 mim. Do badań zastosowano pomiary densymetryczne. Uzyskane wartości gęstości pozornej materiałów o mikrometrycznym rozdrobnieniu porównano z wynikami otrzymanymi metodami: porównawczą, rtęciową oraz miareczkowania dla próbek tego samego materiału, ale o grubszych ziarnach (40-315 (mim). Zastosowanie metody porównawczej do oznaczania gęstości pozornej materiałów o mikrometrycznch wymiarach ziaren umożliwia obliczanie porowatości cząstki i złoża.

EN

The particle porosity and bed porosity of fine powders with the range of the grain size 0-100 (mim have been investigated. The densymetric measurements were used during the research. Obtained values of apparent density of micrometric fine materials were compared to apparent densities of the same type of material samples but with the range of the grain size 40-315 mim. Using of the comparative method to measure of the apparent density of micrometric fine materials makes possible the calculation of particle porosity as well as bed porosity.

4

Thermal fracture of a model of ceramic catalysator

100%

Wesołowski Z.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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1998

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tom Vol. 46, nr 2

177-186

EN

Grains in form of circles are connected by elastic joints. Grains expand thermally, but do not deform elastically. The joints deform elastically, but do not expand thermally. The special situation is considered when the composite consists of only two kinds of grains, first kind with larger and the second kind with smaller expansion coefficient. The grains are randomly distributed in the specimen. All joints are equal. The specimen is free of external load. The uniform temperature increases from zero and leads to internal stresses. If the stress exceeds some fixed limits the joint breaks down and for all later instants the stress equals zero. The number of damaged joints and thermal stresses is calculated as a function of the proportion of the two kinds of grains.

5

Determination of limit pore size distributions of porous materials from mercury intrusion curves

100%

Cieszko M. , Kempiński M.

Engineering Transactions

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2006

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tom Vol. 54, iss. 2

143-158

EN

The application of the capillary and chain models of pore architecture are proposed in the paper for determination of limit pore size distributions of porous materials based on the mercury intrusion curves. They estimate the range of pore sizes in the investigated material. It is proved that for a given pore size distribution, the capillary model of pore architecture, commonly used in the mercury porosimetry, and its chain model, are two limit cases of the network model of pore architecture, considered in the paper as a proper model for most real porous materials. For both limit pore architectures, the expressions describing capillary potential curves have been derived that are the basis for the procedure of determination of two limit pore size distributions. This procedure has been illustrated by determining the limit distributions for porous materials made of sintered glass beads.

6

Computer modelling of pentoxifylline release from a cylinder-shaped hydroxylapatite carrier

100%

Mietła A. , Mycek B. , Wanat I. , Wąs J. , Zima A.

Bio-Algorithms and Med-Systems

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2012

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tom Vol. 8, no. 1

89--109

EN

The main objective of this article is to present the basic stages of creating a computer simulation of medication release from an undegraded carrier. Additionally, an innovative approach was presented to the construction of a porous material used for making the carrier for the medication. The programme presented here is based on Cellular Automata, used as a tool for modelling physical, chemical and biological phenomena which change in time. The results of in-silico calculations have been compared with empirical results.

7

Porous material effect on gearbox vibration and acoustic behavior

100%

Letaief M. R. , Walha L. , Taktak M. , Chaari F. , Haddar M.

Journal of Theoretical and Applied Mechanics

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2017

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tom Vol. 55 nr 4

1381--1395

EN

In this paper, we define a resolution method to study the effect of a porous material on vibro-acoustic behavior of a geared transmission. A porous plate is coupled with the gearbox housing cover. The developed model depends on the gearbox characteristic and poroelastic parameters of the porous material. To study the acoustic effect of the housing cover, the acoustic transmission loss is computed by simulating numerically the elastic-porous coupled plate model, and the numerical implementation is performed by directly programming the mixed displacement-pressure formulation. To study the vibration effect, the bearing displacement is computed using a two-stage gear system dynamical model and used as the gearbox cover excitation. Numerical implementation is performed by direct programming of the Leclaire formulation.

8

Model przepływu powietrza w ośrodku porowatym z uwzględnieniem wewnętrznych źródeł ciepła

100%

Skotniczy P.

Prace Instytutu Mechaniki Górotworu PAN

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2008

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tom Vol. 10, no. 1-4

103--113

PL

W artykule przedstawiono eksperymentalną metodę wyznaczania współczynnika przepuszczalności K oraz jej numeryczną weryfikację. Pomiary wykonano na specjalnie przygotowanym do tego celu stanowisku pomiarowym, ośrodek porowaty stanowiło złoże uformowane z kulek szklanych (ballotyna) o rozmiarze 5 mm. Do wyznaczenia wartości współczynnika K oraz współczynnika oporu kwadratowego zastosowano równanie Forchheimera. Przedstawione wyniki pomiarów mają posłużyć za podstawę do przeprowadzenia szeroko zakrojonej serii eksperymentów mających na celu określenie wpływu obecności źródła temperatury wewnątrz złoża porowatego na sposób wymiany masy w układzie materiał porowaty-powietrze.

EN

Presented paper discuses, an experimental method in prediction of K coefficient as well as its numerical verification. The measurements has been taken using specialized test bed, where porous bed was configured with 5 mm diameter glass balls. For determination of K coefficient as well as quadratic drag coefficient the Forchheimer equation has been used. Presented data are base for the further experiments concerning mass and heat exchange in porous bed – air complex.

9

Porous biomaterial for orthopaedic implants based on titanium alloy

100%

Seremak T. , Serbiński W. , Zieliński A.

Advances in Materials Science

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2011

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tom Vol. 11, nr 1(27)

27-34

EN

Titanium and its alloys are widely used as biomaterials for orthopaedic applications. Research connected with their best corrosion and wear resistance, biocompatibility and bioactivity are still being conducted. The current research is also focused on the design and manufacturing of the porous materials based on e.g. Ti-13Nb-13Zr alloy, which can be applied for implants. One of the most effective manufacturing methods of the porous materials are powder metallurgy techniques. The aim of the presented work was the design of powder preparation procedure and design a parameters of pressing and sintering processes in order to obtain the porous structure from Ti-13Nb-13Zr alloy. Investigation results of the microstructure morphology, pore size and porosity of the obtained porous material on the base Ti-13Nb-13Zr alloy in dependence of the pressing and sintering parameters are also shown and discussed.

10

Response surfaces in the numerical homogenization of non-linear porous materials

100%

Beluch W. , Hatłas M.

Engineering Transactions

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2019

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tom Vol. 67, iss. 2

213--226

EN

The paper deals with the numerical homogenization of structures made of non-linear porous material. Material non-linearity causes a significant increase in computational costs for numerical homogenization procedure. An application of the response surface methodology allows a significant reduction of the computational effort providing good approximation precision. Finite element method commercial software is employed to solve the boundary-value problem in both scales. Due to the significant reduction in computing time, the proposed attitude may be applied for different optimization and identification tasks for inhomogeneous, non-linear media, especially with the use of global optimization methods.

11

Effects of viscoelastic and porous materials on sound transmission of multilayer systems

100%

Felhi H. , Trabelsi H. , Taktak M. , Chaabane M. , Haddar M.

Journal of Theoretical and Applied Mechanics

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2018

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tom Vol. 56 nr 4

961--976

EN

Multilayer structures allow obtaining good performance in acoustic insulation to eliminate unwanted noise in the medium and high frequencies in many applications such as building and transport industry. In this paper, the sound transmission of multilayer systems is studied using the Transfer Matrix Method (TMM). The studied multi-layered panels include elastic, viscoelastic and porous materials. Several configurations of multilayer systems are studied, and their corresponding transmission loss T L is computed. Also, the effects of porous material characteristics are studied to evaluate the impact of each parameter.

12

Preparation and physicochemical characterisation of ceramic supports for suported liquid membranes

100%

Cichowska-Kopczynska I. , Joskowska M. , Wojciechowska A. , Aranowski R.

Physicochemical Problems of Mineral Processing

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2013

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tom Vol. 49, iss. 1

287--300

EN

Supported liquids membranes are very promising products. They have been intensively inves-tigated in last two decades and widely used in many technologies especially in gas separation and purifi-cation processes. A key aspect in obtaining satisfying effectiveness and long membrane lifetime is a proper choice of ionic liquid and polymeric or ceramic support. Properties of both affect the processes of obtaining useful supported ionic liquid membranes. In comparison to polymeric membranes, ceramic ones are slightly thicker, however they are thermally and mechanically more stable. Our research was aimed at sintering fine glass particles of 500 to 45 μm in size in order to prepare porous membranes which can be used as supports for liquid membranes. Dextrin and borax were used as pore-making agents. The membranes, as disks 35 mm in diameter and 3 mm of thickness, were prepared. The porosity was determined using absorption method. It was found, that the porosity could be controlled by changing the applied pressure from 1 to 5 MPa, particle size distribution, sintering temperature, type and amount of pore-enhancing agents.

13

Wąsko-przedziałowe pomiary sorpcyjne współczynnika dyfuzji cegły ceramicznej, silikatowej i betonu komórkowego

88%

Garbalińska H. , Garbasz B.

Fizyka Budowli w Teorii i Praktyce

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2007

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tom T. 2

35-40

PL

Referat poświęcony jest ocenie możliwości wykorzystania metod niestacjonarnych do wyznaczania współczynnika dyfuzji materiałów porowatych. Do oceny skuteczności tej metodyki wytypowano trzy popularne materiały porowate: cegłę ceramiczną, ceglę silikatową i beton komórkowy. Obliczenia przeprowadzono w odniesieniu do pomiarów sorpcyjnych, które dotyczyły pięciu wąskich, sąsiadujących ze sobą przedziałów wilgotności sorpcyjnej.

EN

The paper is devoted to the assessment of the possibility of using non-stationary methods to the determination of diffusivity of porous materials. For the purpose of the evaluation of the efficiency of this method three popular construction materials have been selected: ceramic brick, silica brick and cellular concrete. The calculations have been conducted with reference to the sorption measurements that concerned five narrow ranges of sorption humidity which are adjacent to one another.

14

An Inverse Method to Obtain Porosity, Fibre Diameter and Density of Fibrous Sound Absorbing Materials

88%

Alba J. , del Rey R. , Ramis J. , Arenas J.

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15

Experimental and Numerical Study of Photo Voltaic Thermal Phase Change Material Heat Transfer Augmentation with Encapsulation of Embedded Material/Fins

88%

Kameswara Rao D. , Reddy K. S. , Subba Rao V. V.

Ecological Engineering & Environmental Technology

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2022

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tom Vol. 23, iss. 4

149--161

EN

Nonconventional energy sources like natural gas, coal, fossil fuels and petroleum are using extensively, leads to clean energy / renewable energy importance. Power generation with burning of fossil fuels can be changed using solar energy input source. Solar radiation incident on Photo voltaic Thermal (PVT) panel raises its temperaturę which tends to decrease the electrical output. Heat enhancement in Photo voltaic Thermal (PVT) panel can be reduced by attaching Phase Change Material (PCM) container on rear side of PV panel which increases the PVT efficiency. Novel technique and promising media for better thermal energy storage using PCM with fins, porous materials. Thermal conductivity of PCMs was low creates problem for energy storage and rate of retrieval. Improvement of thermal conductivity in PCMs and heat transfer enhancement can be done efficiently with the help of fins and porous materials of different designs. Present study provides optimum design of PCM container depth, fin height along with length of fin. Enhancement of heat transfer in Photo voltaic Thermal- Phase Change Material (PVT-PCM) will done by addition of Nano particles (Tio2, Sio2 and Al etc.)of high thermal conductivity along with PCM. Porous materials / fins can be made with metallic based materials nickel, copper, aluminum and carbon materials like graphite. These porous materials gave good results and efficient in heat transfer / thermal conductivity enhancement by 50–600 times than the conventional one. This paper gives the recommendations and conclusions to discuss research gap in this area PCM heat transfer enhancement to reduce the PVT panel temperature.

16

Effect of Liner Characteristics on the Acoustic Performance of Duct Systems

88%

Othmani C. , Hentati T. , Taktak M. , Elnady T. , Fakhfakh T. , Haddar M.

Archives of Acoustics

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2015

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tom Vol. 40, No. 1

117--127

EN

Porous materials are used in many vibro-acoustic applications. Different models describe their performance according to material’s intrinsic characteristics. In this paper, an evaluation of the effect of the porous and geometrical parameters of a liner on the acoustic power attenuation of an axisymmetric lined duct was performed using multimodal scattering matrix. The studied liner is composed by a porous material covered by a perforated plate. Empirical and phenomenal models are used to calculate the acoustic impedance of the studied liner. The later is used as an input to evaluate the duct attenuation. By varying the values of each parameter, its influence is observed, discussed and deduced.

17

Analysis of the occurrence of natural convection in a bed of bars in vertical temperature gradient conditions

75%

Wyczółkowski R. , Musiał D.

Archives of Thermodynamics

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2013

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tom Vol. 34, no. 1

71--83

EN

The reason for undertaking this study was to determine the possible involvement of natural convection in the global heat transfer, that occurs in the heated steel rods bed. This problem is related to the setting of the effective thermal conductivity of the bars bed. This value is one of the boundary conditions for heating modeling of steel rods bundles during heat treatment. The aim of this study was to determine for which geometry of the bed bars, there will be no free convection. To analyze the problem the Rayleigh criterion was used. It was assumed that for the value of the number Ra < 1700 convection in the bed bars does not occur. For analysis, the results of measurements of the temperature distribution in the unidirectionally heated beds of bars were used. It has been shown, that for obtained, during the test, differences of temperature between the surfaces of adjacent rods, convection can occur only when the diameter of the rod exceeds 18 mm.

18

Application of selective and porous materials for the removal of biogenic compounds and indicator bacteria from domestic wastewater

75%

Dacewicz E.

Acta Scientiarum Polonorum. Formatio Circumiectus

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2018

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tom 17

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nr 2

EN

In the paper we present the evaluation of the effectiveness of the removal of biogenic compounds and indicator bacteria from domestic sewage in a vertical flow filter with a variety of fillings. The research was carried out on expanded clay, zeolite, calcined siliceous limestone, and crushed PET flakes. Based on the study of raw and treated wastewater, the effectiveness of removal of ammonium nitrogen, orthophosphates, Escherichia coli, and coliform bacteria was determined according to the selectivity, porosity and grain size of the fill. In the case of removing biogenic compounds, the most effective fillers were found to be of natural porous selective materials, such as zeolite and calcined siliceous limestone. They produced a very high removal rate of ammonium and orthophosphate, amounting to 75.34%, and over 79%, respectively. It has been demonstrated that the filter that was filled with natural porous material of fine particle size (the zeolite) was the most suitable for the removal of indicator bacteria. A very high degree of the Escherichia coli (99.98%) and coliform bacteria (99.94%) reduction was obtained.

PL

W artykule przedstawiono ocenę skuteczności usuwania związków biogennych oraz bakterii wskaźnikowych ze ścieków bytowych w filtrach pionowych o zróżnicowanym wypełnieniu. Analizie poddano keramzyt, zeolit, wyprażaną opokę oraz rozdrobnione płatki PET. W oparciu o badania ścieków surowych i oczyszczonych określono efektywność usuwania azotu amonowego, ortofosforanów oraz bakterii Escherichia coli i bakterii grupy coli w zależności od selektywności, porowatości oraz wielkości uziarnienia wypełnienia. W przypadku usuwania związków biogennych najskuteczniejszym wypełnieniem okazały się naturalne materiały selektywne porowate, tj. zeolit i wyprażana opoka. Stwierdzono na nich bardzo wysoki stopień usunięcia odpowiednio jonów amonowych na poziomie 75,34% oraz ortofosforanowych powyżej 79%. Wykazano, że filtr zasypany naturalnym materiałem porowatym o drobnym uziarnieniu okazał się najbardziej odpowiedni do usunięcia bakterii wskaźnikowych. Stopień eliminacji bakterii grupy coli wyniósł 99,94%, a bakterii Escherichia coli 99,98%.

19

Numeryczne wyznaczenie rozkładów ciśnień i prędkości powietrza w zwałowisku górniczym i jego otoczeniu dla założonej porowatości

75%

Skotniczy P.

Prace Instytutu Mechaniki Górotworu PAN

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2006

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tom Vol. 8, no. 1-4

105--115

PL

W artykule omówiono przypadek niestacjonarnego przepływu powietrza wokół zwałowiska odpadów pogórniczych w aspekcie napowietrzania porowatego materiału zwałowiska. Prezentowany przypadek obejmuje analizę niestacjonarnych rozkładów ciśnień statycznych na powierzchni zwałowiska, analizę śladu turbulentnego za zwałowiskiem jak również rozkład prędkości powietrza wewnątrz zwałowiska. W zastosowanym w obliczeniach profilu prędkości uwzględniono atmosferyczną warstwę przyścienną.

EN

Presented paper discuses case of transient air flow around coal waste dump in terms of infiltration of porous material. In The analysis of the fluctuation of static pressure, velocity field outside and inside the dump as well as turbulent wake behavior is talked about. The atmospheric boundary layer was introduced into applied turbulent velocity profile as an inlet boundary condition.

20

Evaluation of the Effect of Uncertainties on the Acoustic Behavior of a Porous Material Located in a Duct Element Using the Monte Carlo Method

75%

Hannachi H. , Trabelsi H. , Kani M. , Taktak M. , Chaabane M. , Haddar M.

Archives of Acoustics

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2023

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tom Vol. 48, No. 1

81--91

EN

When studying porous materials, most acoustical and geometrical parameters can be affected by the presence of uncertainties, which can reduce the robustness of models and techniques using these parameters. Hence, there is a need to evaluate the effect of these uncertainties in the case of modeling acoustic problems. Among these evaluation methods, the Monte Carlo simulation is considered a benchmark for studying the propagation of uncertainties in theoretical models. In the present study, this method is applied to a theoretical model predicting the acoustic behavior of a porous material located in a duct element to evaluate the impact of each input error on the computation of the acoustic proprieties such as the reflection and transmission coefficients as well as the acoustic power attenuation and the transmission loss of the studied element. Two analyses are conducted; the first one leads to the evaluation of the impacts of error propagation of each acoustic parameter (resistivity, porosity, tortuosity, and viscous and thermal length) through the model using a Monte Carlo simulation. The second analysis presents the effect of propagating the uncertainties of all parameters together. After the simulation of the uncertainties, the 95% confidence intervals and the maximum and minimum errors of each parameter are computed. The obtained results showed that the resistivity and length of the porous material have a great influence on the acoustic outputs of the studied model (transmission and reflection coefficients, transmission loss, and acoustic power attenuation). At the same time, the other physical parameters have a small impact. In addition, the acoustic power attenuation is the acoustic quantity least impacted by the input uncertainties.