Wyniki wyszukiwania - BazTech

1

Wpływ zawartości części lotnych na właściwości sorpcyjne węgli kamiennych w kontekście zagrożenia wyrzutami gazów i skał

Dreger Marcin

Przegląd Geologiczny

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2024

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Vol. 72, nr 1

46--52

EN

The classification of gas and rock outburst hazard based on the volatile content of coalis assessed. The complexity of gas and geodynamic hazards, and of the geological and mining conditions of the Upper Silesian Coal Basin, make it difficult to effectively assess the gas androck outburst. Safe mining operations in coal seams prone to outbursts should be based on specified analyses of gas, geological and mining conditions, and consider the coal characteristics, including the volatile content and sorption properties. An original method for determining the adsorption isotherm is described: it allows for more precise determination of methane pressure, and of the possibility of gas accumulation at higher pressures. A coal classification is developed based on the volatile content(Vdaf) in relation to the possibility of a gas-geodynamic phenomenon.

2

Diffusive solute transport in hollow fiber dialyzers is not affected by variable feed viscosity

Schneditz Daniel, Sauseng Notburga

Biocybernetics and Biomedical Engineering

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2022

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Vol. 42, no. 4

1112--1122

EN

Dialyzer clearance (K) for hemodialysis is usually predicted from the mass transfer area product (K0A) provided in manufacturer data sheets without accounting for elevated feed-viscosity when treating blood. The boundary layer model for mass transport across hollow fiber membranes, however, predicts an increase in mass transfer resistance (1/K0) and a decrease in K with increasing feed-viscosity. The effect of increased feed-side viscosity relative to baseline crystalloid viscosity on small solute K and 1/K0 was therefore examined in commercial high- (HF) and low-flux (LF) dialyzers in lab-bench studies using standard dialysis equipment in the normal operating range. Homogeneous colloid solutions and bovine plasma were used to simulate the range of relative viscosities (ηrel) and oncotic pressures expected under in-vivo conditions. Internal filtration (IF) was quantified by a mathematical model to obtain diffusive transport characteristics (K’, 1/K'0). An up to 5-fold increase in ηrel caused a small increase in K and a small decrease in 1/K0 in HF, but not in LF dialyzers. After correction for a small convective contribution by IF, K’ and 1/K'0 remained constant in both LF and HF dialyzers. Diffusive transport characteristics of commercial HF and LF dialyzers are independent of variable feed-side viscosity. This suggests an insignificant contribution of the feed-side boundary layer resistance in dialyzers optimized for operation in hemodialysis. Increasing the feed-side viscosity, however, increases the convective component of dialyzer solute transport because of IF. Diffusive dialyzer clearance predicted from the dialyzer K0A is independent of elevated feed-viscosity.

3

The Potential of Sisal Fibre as an Additive in Lightweight Foamed Concrete for Thermal Properties Enhancement

Mydin Md Azree Othuman

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 3

89--97

EN

Lightweight foamed concrete (LFC) is extremely permeable, and its thermal properties reduce with rising in the number of voids. In turn, to improve its thermal properties, the solid matrix of LFC can be adjusted by incorporating several natural fibers. The influence of sisal fiber in LFC was not investigated before in the current body of knowledge. Hence, there is some ambiguity considering the mechanism by which and the extent to which the sisal fiber can influence LFC thermal properties. Hence, this study concentrates on distinguishing the potential use of sisal fiber in LFC. The purpose of this research is to determine LFC's thermal characteristics when sisal fiber is added. Casting and testing of densities of 800 kg/m3 and 1600 kg/m3 were done. Various weight fractions were employed pertaining to sisal fiber, i.e., 0.15%, 0.30%, 0.45% and 0.60%. The components of thermal properties, which consist of specific heat, thermal conductivity as well as thermal diffusivity were evaluated. To get comparable results, we fixed the water to cement ratio as 0.45 while keeping constant the cement to sand ratio at 1:1.5. It was seen that optimum results were achieved with the addition of 0.45% of sisal fiber with regard to all the thermal characteristics regarded in this exploration. At 0.45% weight fraction about sisal fiber, maximum compaction was achieved with fibers as well as the cementitious matrix, which ensued in good mix uniformity. Beyond the optimum level pertaining to the presence of sisal fiber, it could be seen that fibers would agglomerate and exhibit non-uniform dispersion, which resulted in a decline with regards to the entire thermal characteristics assessed.

4

Structural and electrical characterization of La3+ substituted PMS-PZT (Zr/Ti:60/40) ceramics

Menasra H., Necira Z., Bounabe K., Abba M., Meklid A., Boutarfaia A.

Materials Science Poland

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2018

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Vol. 36, No. 1

1--6

EN

Pb(1-x)La(x) [(Zr0.6Ti0.4)(1-x) (Mn1/3Sb2/3)(x)]O3 ceramics with x = 0.02, 0.03, 0.04, and 0.05 were synthesized by using a conventional solid state reaction route. The influence of La, Mn, and Sb contents on phase structure, microstructure, and electric properties were investigated. The results of X-ray diffraction (XRD) show that the phase structure of the ceramics transforms from rhombohedral phase to tetragonal phase. However, the minority pyrochlore phase appears on the micrographs of XRD and SEM if the doping concentration is greater than 2 mol%. The grain size of the ceramics gradually increases (from 1.36 μm to 1.57 μm) with increasing doping. The dielectric properties of the ceramics have been measured as a function of temperature in the range of 20 °C to 430 °C at 1 kHz. The results indicate that the transition temperature and the maximum dielectric constant decrease with increasing PL-PMS content in the system. These results clearly show the significance of PL-PMS in controlling the dielectric behavior of the PL-PMS-PZT system.

5

Evaluation of selected thermal properties of components of bonded joint for purposes of active thermography

Fidali M., Kruczek T., Kurpiński M.

Measurement Automation Monitoring

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2017

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Vol. 63, No. 3

102--106

EN

Adhesively bonded joints are widely used in the automotive industry. Different kinds of defects could appear in the bounded joint during its creation. The defects could be detected by use of many destructive and non-destructive methods including active thermography. Application of active thermography requires setting of test parameters. It could be done based on analytical or numerical models which requires material properties of bonded components. In the article presented results of measurements of thermal diffusivity and specific heat of automotive steel and adhesive for purposes of further modelling and estimation of active thermography test parameters.

6

Growth of intermetallic compound between indium-based thermal interface material and copper substrate: molecular dynamics simulations

Fałat T., Płatek B.

Materials Science Poland

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2015

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Vol. 33, No. 2

445--450

EN

The diffusion phenomenon occurring between copper and indium was investigated by molecular dynamics simulations. The calculations were carried out in various temperatures in aging domain with the use of the commercially available Materials Studio v.6. software. The results showed that the intermetallic compound (IMC) growth followed the parabolic law, which indicated this growth to be mainly controlled by volume diffusion. The growth activation energy was estimated at 7.48 kJ.mol(-1).

7

Thermodynamics And Concentration Fluctuations Of Liquid Al-Cu And Al-Zn Alloys

Trybuła M., Jakse N., Gąsior W., Pasturel A.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

649--655

EN

Thermodynamic properties of liquid Al-Cu and Al-Zn alloys are investigated using the free volume model. We also analyse local atomic arrangements and concentration fluctuations in both liquid binary alloys from the determination of the Warren-Cowley short-range order. For liquid Al-Cu alloys, our findings indicate a strong preference for heteroatomic nearest-neighbors bonds on the Cu-rich side and weaker ones in the Al-rich part while for the liquid Al-Zn alloy, a tendency to the phase separation is observed. Basing on Darken’s thermodynamic relationship, diffusivity has been examined for both liquid alloys.

PL

W oparciu o model swobodnej objętości zostały zbadane właściwości termodynamiczne ciekłych stopów Al-Cu i Al-Zn oraz lokalne środowisko atomów w celu obliczenia parametru bliskiego zasięgu Warren-Cowleya. W ciekłych stopach Al-Cu zaobserwowano silną tendencję do tworzenia wiązań hetero-atomowych w obszarze bogatym w Cu, natomiast w obszarze stężeń bogatych w Al znacznie słabszą. W przypadku ciekłych stopów Al-Zn obliczenia wskazują na tendencję do segregacji atomów. Dyfuzja w dyskutowanych stopach została przeanalizowana w oparciu o termodynamiczną definicję podaną przez Darkena.

8

Investigation of the effect of thermal diffusivity coefficient of tool material on electrode-tool wear in the EDM process

Joudivand Sarand M. H., Shabgard M. R.

Archives of Civil and Mechanical Engineering

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2015

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Vol. 15, no. 4

806--821

EN

Tool wear occurrence causes a variety of difficulties including expensive and inaccurate cutting processes. Therefore, it is imperative to determine which parameter has the most influence on tool erosion rate. Since EDM is basically a thermal process, it is mostly affected by thermo physical properties of tool material. This becomes more important in numerically modeling of EDM process which contributes a better understanding of the wear mechanism. This study aimed to examine the effect of thermal diffusivity on tool erosion rate which has not yet been investigated in detail. Therefore, the experiments were conducted using copper alloy, copper-iron alloy, aluminum alloy and graphite as tools and AISI H13 as workpiece. Additionally, numerical simulation of tool wear was performed using Levenberg–Marquardt technique to gain better understanding of tool wear phenomenon. Results revealed that, increase of thermal diffusivity of tool material decreases tool wear rate. It is observed that in the experiments, performed using tool electrodes with low thermal diffusivity coefficient, the increase of wear rate is significantly intensified with increase of current and pulse on-time. Comparative analysis of the experimental and numerical results indicates that the introduced numerical simulation is capable of estimating tool wear rate with 5% average error, approximately.

9

The Thermal Conductivity : Experimental Studies of Thermal Processes in Woodworking

Malujda I., Talaśka K., Dudziak M.

Machine Dynamics Research

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2014

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Vol. 38, No. 1

129-136

EN

During the modeling of thermal processes of woodworking it is need to do thermal conductivity testing. This is accomplished most frequently by using the method based on the theory of established heat conduction. The measurement involves the determination of the heat flux with a constant value flowing through a sample of the test material with specified dimensions. The original construction of the testing device was used to determine the coefficients of thermal conductivity. There were determined the characteristics of thermal conductivity ʎ and diffusivity α as a function of the temperature in the directions of orthotrophy L, T, R of the wood samples. The results of the tests performed for thermal properties of oak wood were presented. They will be used to formulate the constitutive equations describing the process of softening with a full and comprehensive description of the role and influence of the temperature on their effectiveness.

10

Study of hydrogen diffusion in magnesium by the electrochemical permeation method

Gajek A., Flis-Kabulska I., Zakroczymski T., Yang C. H., Chang J. K., Tsai W. T.

Ochrona przed Korozją

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2010

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nr 11

513-516

EN

To directly determine the diffusion coefficient of hydrogen in magnesium at room temperature (30oC), measurements of hydrogen permeation through the membranes consisting of Pd, Mg and Fe sub-layers were carried out by the electrochemical method. The membranes were charged with hydrogen by cathodic polarization in 0.1 M NaOH. Values of the effective diffusion coefficients, characterizing hydrogen transport through the whole membrane, were determined on the basis of the partial build-up and decay permeation transients. Then, knowing the diffusion behaviour of hydrogen in palladium and iron, the diffusion coefficient of hydrogen in magnesium was evaluated -- D = 1.9ź10-12 m2/s.

PL

W celu bezpośredniego wyznaczenia współczynnika dyfuzji wodoru w magnezie w temperaturze pokojowej (30oC), stosując metodę elektrochemiczną przeprowadzono pomiary przenikania wodoru przez membrany składające się z podwarstw Pd, Mg i Fe. Membrany były ładowane wodorem wydzielanym katodowo z 0.1 M NaOH. Na podstawie przebiegów częściowego wzrostu i spadku szybkości przenikania określono wartości efektywnego współczynnika dyfuzji, charakteryzujące transport wodoru przez całą membranę. Następnie, znając dyfuzyjność wodoru w palladzie i żelazie, określono współczynnik dyfuzji wodoru w magnezie -- D = 1,9ź10-12 m2/s.

11

Badanie dyfuzji i absorpcji wodoru w niklu elektrochemiczną metodą przenikania i desorpcji

Pekar O., Zakroczymski T.

Ochrona przed Korozją

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2010

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nr 11

616-618

PL

Stosując elektrochemiczną metodę przenikania i desorpcji wodoru, zbadano dyfuzję i absorpcję wodoru w cienkich membranach niklowych, ładowanych wodorem wydzielanym katodowo w roztworze NaOH. Najpierw, na podstawie przebiegu krzywych wzrostu i spadku szybkości przenikania przez membranę określono współczynnik dyfuzji wodoru. Następnie na podstawie analizy krzywych desorpcji wodoru z obydwu stron membrany określono ilości wodoru dyfuzyjnego i odwracalnie pułapkowanego, jak również rozmieszczenie tych form wodoru w membranie. Najprawdopodobniej wodór pułapkowany odwracalnie pochodził głównie z wodorku niklu, tworzącego się tuż pod powierzchnią membrany.

EN

Diffusion and absorption of hydrogen in thin nickel membranes, cathodically charged with hydrogen in NaOH solution, were studied by the electrochemical permeation and desorption method. First, the diffusion coefficient of hydrogen was determined on the basis of the permeation build-up and decay transients. Then, the analysis of the desorption rate of hydrogen at both sides of the previously charged membrane enabled the determination of amounts of the diffusible and reversibly trapped hydrogen and their distribution in the membrane. Most probably, the reversibly trapped hydrogen originated mainly from nickel hydride forming beneath the membrane surface.

12

Badania warstwy wierzchniej materiału ceramicznego w procesie mikroszlifowania z wykorzystaniem analizy termofalowej

Musiał W., Suszyński Z., Majchrzak P.

Archiwum Technologii Maszyn i Automatyzacji

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2006

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Vol. 26, nr 2

55-66

PL

W artykule przedstawiono wyniki badań warstwy wierzchniej ceramiki korundowej AI2Osub>2 po szlifowaniu, uzyskanej w warunkach plastycznego płynięcia materiału. Zamieszczono wyniki analiz termo fal owych warstwy wierzchniej szlifowanego materiału, umożliwiające wyznaczenie profilu głębokościowego przewodności cieplnej tej warstwy.

EN

This paper presents the investigations results of alumina ceramics (AI2O3 surface layer after grinding obtained in ductile-regime grinding. In the paper there have been shown the results of thermal wave analysis of polished material recast layer, which made possible the determination of depth profile thermal conductivity of worked material surface layer.

13

Ocena rozkładów gęstości i współczynników dyfuzji w biofilmie immobilizowanym na materiale drobnoziarnistym

Tabiś B., Siudzińska R.

Przemysł Chemiczny

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2005

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T. 84, nr 4

250-253

PL

Omówiono sposób określania rozkładów dwóch podstawowych wielkości wpływających na szybkość procesu mikrobiologicznego w biofilmie immobilizowanym na materiale drobnoziarnistym, a mianowicie gęstości biofilmu i współczynników dyfuzji reagentów. Wielkości te w zasadniczym stopniu decydują o wartościach współczynnika efektywności biofilmu, czyli o ogólnej szybkości procesu. Wykorzystano w tym celu opublikowane dane doświadczalne otrzymane w dwufazowym i trójfazowym złożu fluidalnym.

EN

The av. reactant diffusivity and biofilm av. d. data detd. in a series of biofilms varying in thickness enable their distribution patterns to be established as functions of a current coordinate in the biofilm. The resulting equations take on the form related to the geometry of the film-growing substrate and to the functions adopted to describe the av. d. and diffusivity in relation to film thickness. Lin. regression suffices to det. the correlation parameters. The diffusivity and esp. the av. d. varied considerably in the biofilms grown on small spherical particles used in 3-phase fluidization bioreactors. The data reported on Pseudomonas putida microorganisms applied in a 2- and a 3-phase fluidization bioreactor were used to show how the biofilm efficiency and thus the overall process rate was affected.

14

Aluminiowanie stali w proszku z samorzutnego rozpadu wysokoaluminiowego żeliwa

Skrzypek S., Pieniążek J., Binczyk F., Przybyłowicz K., Ratuszek W.

Hutnik, Wiadomości Hutnicze

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2004

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Vol. 71, nr 7-8

425-428

PL

Badania procesu dyfuzyjnego aluminiowania różnych stopów żelaza (stal 45, 1H17, Cr20Al5 i Fe -armco) w stopowym proszku samorozpadowym uzyskanym z samorzutnego rozpadu wysokoaluminiowego żeliwa opisano w prezentowanej pracy. Celem badań było stwierdzenie możliwości zastoswania takiego proszku do celów dyfuzyjnego aluminiowania stali. Badania wykazały, że w odpowiednich warunkach powstaja warstwy wzbogacone w aluminium, tworzące nadstruktury FeAl i Fe3Al. Celem takiejobróbki cieplno - chemicznej jest połączenie własności mechanicznych i antykorozyjnych.

EN

An aluminizing process of different iron alloys (C 45 steel, 1H17 steel, Cr20Al15 (kanthal) and Fe -armco) with application of self - decomposition powder was carried out. The object of study were diffusion layers deposited on steels. Investigation shows that applied conditions of treatment were suitable to form layers enriched witch aluminium. The surface layers consist of FeAl and Fe3Al superlattice. The thermo - chemical process was applied to improve mechanical and corrosion properties.