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1

Non-contact eddy current conductivity measurements as an effective tool for evaluating aluminum alloys in aircraft

Uchanin Valentyn

Transactions on Aerospace Research

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2024

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Nr 3 (276)

43--57

EN

Aluminum alloys (AAs) are pivotal materials in modern aircraft due to their superior mechanical properties and low weight. The structural integrity of these alloys, crucial for aircraft safety, heavily depends on heat treatment processes that alter their mechanical characteristics. Nondestructive evaluation (NDE) techniques, such as eddy current (EC) conductivity measurements, play a vital role in assessing these alloys throughout their lifecycle. EC methods enable the measurement of electrical conductivity, a structure-sensitive parameter that correlates with mechanical properties affected by heat treatments and operational stresses. This paper reviews the application of EC conductivity measurements in the aerospace industry, focusing on their role in assessing AA structural integrity. It discusses how EC methods can penetrate non-conductive coatings, crucial for in-service measurements without surface removal. Recent developments include a novel small-size EC probe and signal processing algorithms aimed at enhancing sensitivity to conductivity changes through dielectric coatings, up to 0.5 mm thick, commonly found in aircraft structures. Key findings include analyses of specific electrical conductivity (SEC) changes in AAs due to heat treatment deviations and long-term operational stresses, crucial for predicting residual life and maintaining safety standards. Case studies on aircraft wing skins and helicopter rotor blades demonstrate the practical application of EC conductivity meters in identifying critical damage zones. The methodology proves effective in evaluating localized degradation based on SEC distributions, thereby enhancing maintenance efficiency and aircraft safety. Overall, this research underscores the significance of EC conductivity measurements in advancing NDE practices for AAs in aircraft applications. The methodologies and findings presented aim to improve safety, durability assessment, and maintenance efficiency in the aerospace industry.

2

Insights Into Estimation of Sand Permeability: From Empirical Relations to Microstructure-based Methods

Bodak Bartłomiej, Sobótka Maciej

Studia Geotechnica et Mechanica

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2024

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Vol. 46, nr 1

1--20

EN

This study evaluates various methods for estimating soil permeability using microtomographyderived data and compares them to the conventional laboratory approaches. Different methods, including measurement in custom-designed permeameter at micro- CT-compatible scale, empirical equations, simulated sifting, semi-theoretical equations, pore-network modeling, and lattice-Boltzmann simulations, were applied to samples of sandy soils with distinct microstructural properties. The empirical equations showed varied results, highly dependent on the method chosen. The simulated sifting method was able to adequately estimate the granulometric properties of the soil, allowing the use of empirical permeability formulations for substantially small samples. Semi-theoretical equations based on the microstructural properties presented reasonable agreement for some samples. The pore-network modeling approach demonstrated computational efficiency but lacked accuracy. The lattice-Boltzmann method required significant computational resources but did not provide substantially closer alignment with the measured hydraulic properties of some samples. None of the simulations was able to properly determine the permeability of silty and organically contaminated sand. The study highlights the complexity of permeability estimation, emphasizing the need for choosing volumes of interest, resolution of micro-CT scans, and methods that match specific soil characteristics and available computational resources.

3

Environmental Variables Significance for Ecological Status Assessment in the Bulgarian Eastern Continental Shallow Lakes

Doychev Dimitar, Gartsiyanova Kristina, Taneva Lidiya

Journal of Ecological Engineering

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2024

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Vol. 25, nr 10

16--30

EN

Eastern Continental shallow lakes are specific with their higher nutrient concentration compared to other lentic water bodies with similar specifications. Nonetheless, their phytoplankton and macrophyte assessment systems used more often than others within state monitoring programs, are weakly influenced by nutrient concentrations, unlike all other lake types in Europe. In this study, we used all available data for Eastern Continental shallow lakes on the Black Sea coast of Bulgaria from the state monitoring for 14 years (2008–2021). The goal was to find how environmental variables influence the ecological status assessment by phytoplankton and macrophyte-related indices. Likewise, it was important to understand the studied parameter’s interrelations within Dourankoulak Lake and the lake complex Shabla-Ezerets. The most important environmental parameters were determined with principal component analysis since it helps find the hidden relationships. Afterwards, those variables were used for univariate linear regression testing because of its simplicity and reliability. The aim was to find the best-suited parameters for the ecological status explanation by different biological indices, which can be used for further predictions of the ecosystem condition. In addition, nitrogen–phosphorus dependency, where possible was investigated, confirming conclusions from mesocosms studies from water bodies with similar characteristics. The algae group index or the so-called “Catalán Index”, in its original form of representing results and considering its ecological quality ratio values, was influenced by conductivity concentrations the most in Ezeretsko Lake and weaker at Dourankoulak Lake. Nutrient relationship with biological quality elements was not found, confirming results on a European level. In Shablensko Lake a dose-dependent relation between nitrates and phosphates was found, which shows that augmenting the quantity of nitrogen is related to the increasing concentration of phosphates.

4

Analiza doświadczeń z pilotażowego monitoringu partycypacyjnego na Wiśle w Krakowie

Grela Agnieszka, Baran-Gurgul Katarzyna, Pamuła Justyna, Godyń Izabela, Biały Piotr, Grela Damian, Oramus Marek

Gospodarka Wodna

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2024

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Nr 12

22--28

PL

Monitoring ciągły w Polsce od kilku lat realizowany jest w 35 przekrojach na Odrze (od 2023r.) oraz 3 przekrojach na Wiśle (od 2024r.). T-Mobile Polska, we współpracy ze Stowarzyszeniem Lepszy Kraków i firma Cortineq, przeprowadziła pomiary jakości wody przy stopniu wodnym Dąbie na Wiśle w Krakowie, wykorzystując specjalistyczną boję pomiarową. Monitoring objął w sposób ciągły śledzenie pięciu wskaźników jakości wody. Analiza wyników pomiarów uwzględnia zmienność obserwowanych wskaźników oraz badanie zależności między nimi.

EN

For the last several years, a constant monitoring has been carried out in Poland in 35 Oder River sections (since 2023) and in 3 Vistula sections (since 2024). T Mobile Polska, in cooperation with the Lepszy Kraków (Better Cracow) Association and the Cortineq Company, led the water quality measurements at the Dąbie barrage on the Vistula River in Cracow, using a specialised measurement buoy. The buoy constantly tracked five water quality indicators. The analysis of the measurement results takes into consideration the changeability of the observed indicator and the relationships between them.

5

Copper Beam Electron Alloying with Ti Powder

Smolarczyk Paulina, Krupiński M., Węglowski Marek, Pakieła Wojciech, Śliwiński Piotr

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 1

88--93

EN

The paper presents the effect of electron beam alloying on the surface of a copper flat bar (M1Ez4) with titanium powder. Due to the quality of the surface after alloying and the obtained properties, the parameters used were given which met the assumed conditions to the greatest extent. The microstructure and mechanical properties as well as the chemical composition of surface-modified electron-beam copper show improved mechanical properties, i.e. hardness and abrasion resistance. This article uses research techniques using scanning electron microscopy and analysis of chemical composition in micro-areas (EDS). In order to examine the properties of the material after electron beam modification, hardness measurements were performed at low loads (HV0.1), abrasion resistance was tested, and conductivity was also measured. As a result of modifying the chemical and phase composition of M1E copper using an electron beam, the hardness increased by 46%, while the conductivity decreased by 16% due to the formation of intermetallic phases during solidification.

6

Development and Analysis of Current Collectors for Proton Exchange Membrane Fuel Cells

Jose Aneesh, Bekal Sudesh, Shanubhogue U. Deepika, Gurukrishna K.

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no. 6

331--340

EN

Hydrogen fuel cells are gaining popularity in power-consuming devices due to their zero-emission characteristics. However, ohmic resistance, which arises from the resistance to electron flow through the electrodes and external circuit, can cause reduced efficiency and voltage drops in a fuel cell. This research aims to develop current collector plates for proton exchange membrane fuel cells with optimal design, high electrical conductivity, and thermal conductivity to mitigate ohmic resistance. Six different designs and five different materials—copper, brass, aluminum, stainless steel 316, and stainless steel 304—were considered for this purpose. The study involved experimental electrical conductivity and fuel cell performance tests to identify the best material and design for the current collector. Results indicated that brass and copper exhibited the least resistivity and favorable material characteristics. Consequently, all six current collector plate designs were developed using brass and copper with various machining and finishing processes. Performance testing on a fuel cell test station revealed that brass current collector plate design 5, featuring open ratios, demonstrated superior performance. Ultimately, the optimum design and material selection of the current collector plates have led to the development of fuel cells with reduced ohmic resistance and improved overall performance.

7

Imprints of graphene nanocomposites towards energy storage potential of lithium ion batteries—state of the art and perspectives

Kausar Ayesha, Ahmad Ishaq

Advances in Materials Science

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2024

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Vol. 24, nr 2(80)

35--60

EN

This state-of-the-art article is designed to cover essential aspects of graphene based nanomaterials for energy storage purposes. Graphene is, a unique nanocarbon, one atom thick nanosheet made up of sp2 hybridized carbon atoms. Graphene has been focused for various technical energy related devices and systems owing to remarkable structure and properties. In energy storage applications, graphene has been applied for varying devices like supercapacitors, fuel cell and batteries. Important utilization of graphene and derived nanocomposites have been observed for lithium (Li) ion batteries. In this context, graphene has been found to offer superior surface area, electron conduction, electrochemical properties, charge or energy density, reversible capacity, rate capacity, cyclic stability, charge-discharge behavior, and other progressive characteristics for effectual energy or charge storage. In addition, graphene derived nanomaterials have been researched for structural, morphological, mechanical, thermal, and other physical characteristics. Hence, graphene and nanocomposites have been reported as efficient Li ion battery electrode or electrolyte material. Future progress on designing new efficient graphene derived nanocomposites and three dimensional graphene based nanomaterials may overcome the challenges towards the formation of high performance battery electrode or electrolyte materials.

8

Wpływ domieszki na wybrane parametry elektryczne i strukturalne materiałów organicznych dla ogniw słonecznych trzeciej generacji

Iwan Agnieszka, Bogdanowicz Krzysztof, Przybył Wojciech

Przegląd Elektrotechniczny

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2023

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R. 99, nr 10

233--236

PL

W artykule omówiono wpływ domieszki i techniki wytwarzania warstw na parametry elektrochemiczne i elektryczne materiałów organicznych dla ogniw słonecznych trzeciej generacji. Warstwy wytworzono poprzez zastosowanie techniki nanoszenia wirowego, warstwy rozciągającej i nanoszenia natryskowego. W oparciu o badania własne przeanalizowano wpływ zastosowanego materiału, domieszki, rozpuszczalnika oraz parametrów technicznych na jakość powierzchni wytworzonych warstw poprzez zastosowanie kamery termowizyjnej.

EN

The article discusses the effect of the doping and the layers preparation technique on the electrochemical and electrical parameters of organic materials for third generation solar cells. The layers were prepared using a spin coating, Doctor-blade and spray techniques. Based on own research, the influence of the applied material, admixture, solvent and technical parameters on the surface quality of the produced layers was analyzed by a thermal imaging camera.

9

Badania wpływu promieniowania elektromagnetycznego na komponenty matryc biosensora

Kłos-Witkowska Aleksandra, Martsenyuk Vasyl

Pomiary Automatyka Robotyka

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2023

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R. 27, nr 4

57--63

PL

W pracy za pomocą zmian przewodności zbadano zmiany konformacyjne proteiny BSA oraz jej kompleksów (BSA-Au oraz BSA-NAA) pod wpływem promieniowania UV oraz MF aplikowanego frakcyjnie w dawkach (3 × 10 min oraz 6 × 10 min) oraz w sposób ciągły (30 min, 60 min). Wykonano analizę porównawczą wpływu promieniowania UV i mikrofalowego w dawkach ciągłych i frakcyjnych na BSA, BSA-Au, BSA-NAA oraz przeanalizowano czułość na pole elektromagnetyczne z zakresu UV i MF dla badanych substancji. Udowodniono efekt przyspieszonych zmian konformacyjnych pod wpływem pola elektromagnetycznego z zakresu UV i MF. Wykazano wpływ czynników na stabilność BSA i jej kompleksów zależny od: rodzaju czynnika, sposobu jego aplikacji oraz czasu ekspozycji. Najbardziej czuły na pole elektromagnetyczne okazał się kompleks BSA-Au.

EN

In this study, the conformational changes of BSA protein and its complexes (BSA-Au and BSA-NAA) under UV and MF radiation applied in fractional doses (3 × 10 min and 6 × 10 min) and continuously (30 min, 60 min) were investigated by means of conductivity changes. A comparative analysis of the effect of UV and microwave radiation in continuous and fractional doses on BSA, BSA-Au, BSA-NAA was performed, and the sensitivity to UV and MF electromagnetic fields of the tested substances was analysed. The effect of accelerated conformational changes under the influence of UV and MF electromagnetic field was proved. The influence of the factors on the stability of BSA and its complexes was shown to depend on: the type of agent, the method of its application and the exposure time. The most sensitive to the electromagnetic field turned out to be the complex BSA-Au.

10

Research on New Al-Ag-Mo Alloys Dedicated to Wire Applications in Overhead Power Lines

Grzebinoga Justyna, Mamala Andrzej, Ściężor Wojciech, Kowal Radosław

Journal of Casting & Materials Engineering

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2023

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Vol. 7, no. 1

9--14

EN

The latest research work in the field of electric power systems focuses on the development of new wire materials which will allow the increase of the transmission capacity of power lines currently in use. The reason for this research was the often limited possibilities of continuous and failure-free transmission of electricity. In this paper, the authors present research on a new aluminium-based alloy dedicated for use as a conductive braid in the HTLS cable group. There are many technical solutions for this group of cables on the market, although they are solutions with a number of disadvantages, ranging from their high price, various operational shortcomings, complicated installation techniques, and ending with the risk of monopolistic practices, which is related to the inability to attract several competitive suppliers. The main aim of the research was to develop a new alloy based on aluminium with the addition of silver and molybdenum dedicated for use in special overhead power cables. Experimental research on new materials focused on obtaining the necessary knowledge to produce an overhead wire from these alloys with higher current carrying capacity in relation to the currently used conventional wire materials based on aluminium.

11

Konduktancja połączeń spawanych torów prądowych szynoprzewodów aluminiowych

Cybulko Piotr, Węgrzyn Tomasz, Szczucka-Lasota Bożena, Krzysztoforski Michał, Döring Adam

Wiadomości Elektrotechniczne

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2022

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R. 90, nr 9

28--30

PL

Systemy dystrybucji energii elektrycznej oparte na szynoprzewodach znajdują zastosowanie m.in. w obiektach przemysłowych wykorzystujących instalacje elektryczne o różnych mocach. Wymagania dotyczące zasilania są realizowane przy użyciu różnych grup szynoprzewodów. Rodzaj używanych połączeń toru prądowego w szynoprzewodach wpływa na przewodność elektryczną połączeń i określa warunki, w jakich można korzystać z szynoprzewodów. W tym artykule przedstawiono wpływ typu procesu spawania złączy w szynoprzewodach aluminiowych pod kątem ich przewodności elektrycznej.

EN

Electricity distribution systems based on busducts are used, among others, in industrial facilities using electrical installations with different capacities. The power requirements are realised by using different groups of busducts. The type of current path connections used in busducts influences the electrical conductivity of the connections and determines the conditions under which busduckts can be used. In this paper, the influence of the type of welding process for joints in aluminium busducts on their electrical conductivity is analysed.

12

Organiczna warstwa transportująca ładunki dodatnie w polimerowych i perowskitowych ogniwach słonecznych – wybrane aspekty materiałowe i techniczne

Iwan Agnieszka, Bogdanowicz Krzysztof A., Przybył Wojciech

Przegląd Elektrotechniczny

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2022

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R. 98, nr 9

178--181

PL

W artykule omówiono wpływ organicznej warstwy transportującej ładunki dodatnie (HTM) na parametry elektrochemiczne i elektryczne polimerowych i perowskitowych ogniw słonecznych. W oparciu o badania własne przeanalizowano wpływ budowy chemicznej polimerów czy związków małocząsteczkowych stosowanych jako HTM na sprawność ogniw słonecznych trzeciej generacji. Najwyższą sprawność otrzymano dla ogniw perowskitowych na bazie iminy (PCE = 14,4%), zaś najwyższą wartość przewodnictwa dla PEDOT:PSS w roztworze wodnym (1,03 × 10-3 S/cm).

EN

The article discusses the influence of the organic hole layer (HTM) on the electrochemical and electrical parameters of polymer and perovskite solar cells. Based on our own research, the influence of the chemical structure of polymers or low molecular weight compounds used as HTM on the efficiency of third generation solar cells was analyzed. The highest efficiency was obtained for imine-based perovskite cells (PCE = 14.4%) and the highest conductivity value for PEDOT:PSS in aqueous solution (1.03 × 10-3 S/cm).

13

Charakteryzacja wielokanałowego transportu nośników ładunku dla epitaksjalnych struktur półprzewodnikowych

Wróbel Jarosław, Złotnik Sebastian, Boguski Jacek, Kojdecki Marek, Wróbel Jerzy

Przegląd Elektrotechniczny

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2022

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R. 98, nr 9

228--230

PL

W pracy zwrócono uwagę na potrzebę rozwoju technik do precyzyjnego parametryzowania wielokanałowego transportu nośników ładunku, mających fundamentalne znaczenie dla efektywnego projektowania przyrządów półprzewodnikowych. Przedstawiono aktualny stan rozwoju tych technik pomiarowych w Wojskowej Akademii Technicznej, oraz przykładowe rezultaty dla struktur półprzewodnikowych, otrzymywanych techniką epitaksji z wiązek molekularnych (MBE).

EN

The paper highlights the need to develop techniques for the precise parameterization of multi-channel charge carrier transport, which are of fundamental importance for the effective design of semiconductor devices. The current state of development of these measurement techniques at the Military University of Technology is presented, as well as exemplary results for semiconductor structures obtained by molecular beam epitaxy (MBE).

14

Mathematical simulation of a microelectronic transducer with frequency output for measuring the induction of the magnetic field

Osadchuk Alexander. V., Osadchuk Iaroslav A., Martyniuk Volodymyr V., Krylik Lyudmila. V., Evseeva Maria V.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2022

|

T. 12, nr 2

43--49

EN

A new magnetically sensitive element based on the synthesized semiconductor material has been developed. A method for the synthesis of a complex compound has been developed tetrakis-μ3-(methoxo) (methanol)-pentakis (acetylacetonate) (tricuprum (II), neodymium (III)) methanol (I). Conducted properties have been studied complex compound in compressed form in the temperature range 273 - 493 K. In the developed magnetoresistor when changing the induction of the magnetic field from 10-3 to 200 mT, the resistivity varies from 3.12∙10-5 Ohm to 1.25∙10-2 Ohm∙m. On the basis of the developed magnetically sensitive resistive element the circuit solution of the frequency transducer of a magnetic field is offered. The frequency transducer of the magnetic field is a hybrid integrated circuit consisting of a bipolar transistor and a gate transistor. The frequency of generation of the developed transducer increases the most in the range from 10-3 T to 0.2 T, and at a supply voltage of 5.0 V varies from 250 kHz to 600 kHz, and in the whole range of changes in magnetic field induction varies from 250 kHz to 750 kHz. The sensitivity of the developed device with frequency output for measuring the induction of the magnetic field is from 400 Hz/mT to 800 Hz/mT.

PL

Opracowano nowy element czuły magnetycznie oparty na zsyntetyzowanym materiale półprzewodnikowym. Opracowano metodę syntezy związku złożonego tetrakis-μ3-(methoxo)(metanol)-pentakis(acetyloacetonian)(tricuprum (II), neodym (III)) metanol (I). Badano właściwości przewodzące związku złożonego w postaci sprasowanej, w zakresie temperatur 273–493 K. W opracowanym magnetooporniku przy zmianie indukcji pola magnetycznego od 10-3 do 200 mT rezystywność zmienia się od 3,12∙10-5 Ohm do 1,25∙10-2 Ohm∙m. Na podstawie opracowanego magnetycznie czułego elementu rezystancyjnego zaproponowano rozwiązanie układu przetwornika pola magnetycznego na częstotliwość. Przetwornik ten jest hybrydowym układem scalonym składającym się z tranzystora bipolarnego i tranzystora bramkowego. Częstotliwość generacji opracowanego przetwornika wzrasta najbardziej w zakresie od 10-3 T do 0,2 T i przy napięciu zasilania 5,0 V zmienia się od 250 kHz do 600 kHz, zaś w całym zakresie zmian indukcji pola magnetycznego zmienia się od 250 kHz do 750 kHz. Czułość opracowanego urządzenia z wyjściem częstotliwościowym do pomiaru indukcji pola magnetycznego wynosi od 400 Hz/mT do 800 Hz/mT.

15

Wpływ procesu aktywacji na właściwości bentonitów

Ryłko Kinga, Skorupa Natalia, Sobczyk Natalia, Lenar Nikola

Analit

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2022

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Nr 12

36--48

PL

Bentonit, pod względem geologicznym, zaliczany od jest do skał pochodzenia wulkanicznego. Jest to ił wykazujący silne pęcznienie oraz cechujący się unikalnymi właściwościami fizycznymi. Parametry te wynikają z wysokiej zawartości montmorylonitu (minerał ilasty należący do grupy smektytu). Podczas aktywacji zachodzi proces kontrolowanej wymiany jonów. Wspomniane jony wapnia, znajdujące się początkowo w międzypakietowej przestrzeni montmorylonitu, zastępowane są jonami sodu, które wprowadza się z aktywatorem. Proces aktywacji bentonitu powoduje polepszenie jego właściwości - zwiększoną zdolność pęcznienia czy też podwyższoną zdolność wiązania. W niniejszym artykule skupiono się na zbadaniu podstawowych właściwości bentonitów oraz ich zmiany pod wpływem procesu aktywacji. Badania pH, przeprowadzone przy użyciu elektrody szklanej, wykazały, że stężenia jonów wodorowych były znacznie wyższe i stabilniejsze w czasie w przypadku bentonitu aktywowanego. Na podstawie otrzymanych wyników przewodnictwa mierzonego metodą konduktometrii można zaobserwować wzrost jego wartości wraz z upływem czasu. Tendencja ta była obserwowalna w przypadkach obu bentonitów, z tą różnicą, że wartości przewodnictwa bentonitu aktywowanego przyjmowały kilkukrotnie wyższe wartości w porównaniu z tym niepoddanym aktywacji. Analiza otrzymanych wartości wykazała, że bentonit aktywowany pęczniał 4-krotnie bardziej niż ten nieaktywowany. Zarówno współczynnik pęcznienia, jak i zawartość wody wyznaczone zostały eksperymentalnie. Po usunięciu, w procesie suszenia, wody adsorpcyjnej oraz międzypakietowej, bentonit aktywowany zawierał dwa razy mniej wody niż ten niepoddany aktywacji węglanem sodu.

EN

Bentonite is classified as a rock of volcanic origin. It is a clay that shows strong swelling and has unique physical properties. These parameters are caused by the high content of montmorillonite (a clay mineral belonging to the smectite group). During activation, a process of controlled ion exchange takes place. The calcium ions, initially located in the inter-pack space of montmorillonite, are replaced by sodium ions with activator. The activation process of bentonite results in an improvement of its properties - increased swelling capacity or binding capacity. This article focuses on the examination of the basic properties of bentonites and their changes under the effect of the activation process. Studies of pH, conducted using a glass electrode, showed that the concentration of hydrogen ions was much higher and more stable over time for the activated bentonite. The results obtained after conductometric measurements show the incensement of conductivity with time. This trend was visible in the cases of both bentonites, with the difference that the conductivity values of the activated bentonite assumed significantly higher compared to values obtained to inactivated one. Analysis of the obtained values showed that the activated bentonite swelled 4 times more the inactivated one. Values of swelling coefficient and water content were determined experimentally. After removal of adsorption and inter-pack water (during the drying process), the activated bentonite contained twice less water than the one not activated by adding sodium carbonate.

16

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.

17

An experimental study on the complex resistivity of fractured rock under different saturation conditions

Pan Baozhi, Ruhan A., Guo Yuhang, Zhang Lihua, Wei Boyang, Zhou Weiyi

Acta Geophysica

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2022

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Vol. 70, no 3

1061--1081

EN

The fracture can be a good channel for oil and gas migration, which has a great influence on the permeability of the reservoir. Therefore, it is of major significance to identify fractures and determine the characterization parameters and physical proper ties of fractured reservoirs. In this study, homogeneous sandstone was used to simulate different artificially fractured rocks. The fractured rock samples had different fracture widths, fracture numbers, and fracture dip angles. In addition, the complex impedance and weights of the rock samples were measured during the process of natural evaporation, and the relationships between the water saturation and the complex resistivity values at different frequencies were examined. The frequency range is 100 Hz–10 kHz. It was found that the influence effects of frequency on the resistivity, dielectric constant, and loss factor had differed among the homogeneous samples and the fractured rock sample. The fracturing had led to the resistivity index and the water saturation curves separating under the different frequencies, and the degree of the dielectric constant index and water saturation curve separation became larger. Furthermore, the influencing effects of the fracture widths, fracture numbers, and fracture dip angles mainly occurred in terms of three aspects. The first was the slope of the resistivity index and water saturation curves (IR–Sw). The second was the slope of the dielectric constant index and water saturation curves (Iε–Sw), and the third was the loss tangent D and water saturation Sw curves.

18

Analysis of a Method for Measuring Deposit Impedance Parameters Using Charge Amplifier and Lock-in Voltmeter

Wiśniewski Dariusz R.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2021

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nr 24(1)

67--81

EN

Methods for measuring deposit parameters are often based on a capacitance or conductivity measurement aimed at estimating, e.g. deposit moisture content. In practice, these methods fail for materials with a low degree of homogeneity, a diverse porous structure or high conductivity, e.g. due to a high water content. This article demonstrates an approach that enables a more precise estimation of the parameters of any deposit. The presented method involves the use of a measuring system in a charge amplifier configuration and the application of a technique using lock-in detection or a lock-in voltmeter to determine resistance and capacitance parameters of a deposit based on signals received from the measuring system. This method can be successfully used wherever the test deposit material is highly heterogeneous and contains both dielectric and conductive materials. The article presents an example of a solution to a measuring system using two planar electrodes that can be dimensioned depending on the deposit dimensions. It is followed by a presentation of a method for converting the signal from the measuring system into impedance parameters of the deposit using a lock-in voltmeter. The analysis of the operation of the entire measuring system was modelled in Matlab/Simulink, and the operation results were presented.

19

Applying Electrical Impedance Tomography Techniques for Detection of Decay Inside Trees

Kieu Duy Thong, Vu Hong Duong, Nguyen Thi Thu Hang, Nguyen Thu Thuy

Inżynieria Mineralna

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2021

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no. 2

31--40

EN

Trees play a critical role in creating green spaces in public areas such as streets, parks, schools, offices. Over time, the trees often get pests and diseases, and then rotten trees can break. To care for and conserve the trees, it is necessary to determine the condition inside the trunk, especially the possibility of having a hollow or not. Wood decay, modifications of moisture and ion content, density due to biotic and abiotic stress agents of water extremity, salinity, and infection strongly change (di-) electrical properties of wood. Hence, we propose to use electrical impedance tomography to detect the change in electrical properties inside the trees that can link to wood decay. In electrical impedance tomography, an array of electrodes is attached around the tree trunk, and small alternating currents are injected via these electrodes, so the resulting voltages are measured. Processing the data, we can construct the spatial distribution of impedance (or resistivity) of the object. In this work, we will present the preliminary results of our group research. We will show theoretical forward modeling results, followed by laboratory experiments and real data application. The results illustrate that electrical impedance tomography can be useful to define several decay scenarios inside the trees.

20

Frequency domain electromagnetic and electrical resistivity geophysical investigation of tar sands deposits in the Ijebu Waterside area, Eastern Dahomey Basin, southwestern Nigeria

Osinowo Olawale Olakunle, Okechukwu Ifeayinchukwu

Geology, Geophysics and Environment

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2021

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Vol. 47, no. 4

217--226

EN

The use of electromagnetic conductivity and electrical resistivity geophysical techniques has been employed in this study to investigate the occurrence, thickness, and spatial distribution of bitumen deposit around Makun-Omi in the Ijebu Waterside area of southwestern Nigeria. Subsurface apparent conductivity distribution data obtained using Geonic 34-3 equipment along fifteen traverses which sounded from different depths of 7.5, 15, 30 and 60 m at inter-coil separation of 10, 20 and 40 m in vertical and horizontal coupling modes and ground resistivity distribution measurements, obtained using Geopulse Tiger Allied resistivity meter at fourteen Vertical Electrical Sounding (VES) stations, were processed and employed to characterize the subsurface in terms of tar sands distribution. The conductivity and resistivity distribution in the form of a 3D earth model, iso-depth maps, 2D sections generated from the processed conductivity and resistivity data indicate relatively low conductivity <20 mS/m and high resistivity >1300 Ωm values around tar/bitumen impregnated sands which mostly occurred in the southern part of the study area. Clearly defined conductivity and resistivity anomalies which delineate the lateral and vertical occurrence of tar impregnated sands underscore the efficacy of integrating electromagnetic and electrical resistivity geophysical techniques to identify occurrence of economic deposits of tar sands in parts of southwestern Nigeria.