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1

Evaluation of the properties of polymer composites with carbon nanotubes in the aspect of their abrasive wear

Krzyżak A., Kosicka E., Szczepaniak R., Szymczak T.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 95, nr 1

5--12

EN

Purpose: Carbon nanotubes are used in composite materials due to the improvement of (including tribological) properties of composites, especially thermoplastic matrix composites. This demonstrates the potential of CNTs and the validity of research on determining the impact of this type of reinforcement on the composite materials under development. Design/methodology/approach: The article presents selected results of research on polymer composites made of C.E.S. R70 resin, C.E.S. H72 hardener with the addition of a physical friction modifier (CNTs) with a percentage by volume of 18.16% and 24.42%, respectively, which also acts as a reinforcement. The produced material was subjected to hardness measurements according to the Shore method and EDS analysis. The study of abrasive wear in reciprocating movement was carried out using the Taber Linear Abraser model 5750 tribotester and a precision weight. The surface topography of the composite material after tribological tests was determined using scanning electron microscopy (SEM). Some of the mentioned tests were carried out on samples made only of resin, used as the matrix of the tested polymer composite. Findings: Carbon nanotubes used in polymer matrix composites, including bisphenol A/F epoxy resin have an influence on the tribological properties of the material. The addition of carbon nanotubes contributed to a 24% increase in the Ra parameter relative to pure resin, to a level corresponding to rough grinding of steel. Research limitations/implications: The results of the tests indicate the need to continue research in order to optimize the composition of composites in terms of operating parameters of friction nodes in broadly understood aviation. Originality/value: The analysed literature did not find any studies on the impact of the addition of carbon nanotubes on epoxy resins based on bisphenol A/F. Due to the wide scope of application of such resins, the properties of such composite materials in which carbon nanotubes are the reinforcing phase have been investigated.

2

Different defuzzification methods in Guimbal Cabri G2 helicopter takeoff possibility evaluation

Mendrek M., Grzesik N., Krzyżak A., Kuźma K.

Transport Problems

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2018

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T. 13, z. 2

27--38

EN

The article discusses the aerodynamic properties of the Guimbal Cabri G2 helicopter. The main considerations concern the helicopters ascending to the altitude under initial conditions, which were assumed in the project and how the change of the defuzzification method affects the work of the fuzzy controller. The authors analyzed the following: the aircraft, the crew and the payload. The authors assessed the altitude and the minimum time of the helicopter climb. In designing and the work simulation process, the authors used Matlab and Simulink software. A comparison of the influence of selected defuzzification methods on the work of the fuzzy controller was made.

3

Analysis of abrasive wear of selected aircraft materials in various abrasion conditions

Krzyżak A., Mucha M., Pindych D., Racinowski D.

Journal of KONES

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2018

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Vol. 25, No. 4

217--222

EN

The use of composite materials is continuously increasing in modern transport. This process is especially noticeable in aviation. The mass percentage of epoxy resin composites in contemporary aircraft constructions is usually higher than 50%, and these materials must meet increasingly demanding requirements. In these circumstances, in addition to mass and strength, it is necessary to predict other properties of the material, such as abrasion resistance. The article presents the analysis of the process of abrasion of carbon fibre reinforced polymers reinforced with various fillers. Straight carbon fibre mats were used for the tests. In addition, powders of pumice, alumina, silicon carbide, and glass microspheres at various concentrations in relation to the matrix were used as fillers. In order to investigate the influence of external factors on the abrasion process, each group of samples was subjected to abrasion under different external conditions: in an insulated environment, in the presence of water and loose abrasives: brown fused alumina (BFA) and white fused alumina (WFA). The measurements were carried out using a precision balance and an electron microscope. The results allow concluding on which kind of filler and in what concentration contributes to improvement of the abrasion resistance of the composite material the most. In addition, it was found that the conditions in which abrasion occurs have a very large impact on the course of this process.

4

Influence of fibre reinforcement on selected mechanical properties of dental composites

Niewczas A. M., Zamościńska J., Krzyżak A., Pieniak D., Walczak A., Bartnik G.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 2

3--10

EN

For splinting or designing adhesive bridges, reconstructive composite structures with increased mechanical properties owing to embedded reinforcement fibres are used. The aim of this article was to determine the influence of glass and aramid fibres on the mechanical strength of composites reinforced with these fibres. Methods: Two polymer-ceramic microhybrid materials: Boston and Herculite were tested. Three types of reinforcement fibres were used: aramid (Podwiązka) with a single layer weave, a single layer weave glass fibre (FSO) and triple layer weave glass fibre (FSO evo). Tests were conducted in accordance with the requirements of ISO 4049:2009. The following material types were chosen for research: Boston, Boston + Podwiązka, Herculite, Herculite + Podwiązka, Herculite + FSO and Herculite + FSO evo. The scope of research included: flexural strength B, bending modulus of elasticity εB and work to failure of the reinforced composite Wfb. Additionally, microscopic observations of fracture occurring in samples were made. Results: In comparison: the Herculite (97.7 MPa) type with the Herculite + FSO evo (177.5 MPa) type was characterized by the highest strength. Fibre reinforcement resulted in decreasing the elasticity modulus: Herculite + reinforcement (6.86 GPa; 6.33 GPa; 6.11 GPa) in comparison with the Herculite (9.84 GPa) and respectively Boston + reinforcement (10.08 GPa) as compared with the Boston (11.81 GPa). Conclusions: Using glass fibres increases flexural strength of the test composites. Using aramid fibres does not change their strength. The elasticity modulus of the reinforced reconstructive structures decreases after application of either type of fibres. However, their resistance to the crack initiation increases.

5

High-resolution computed microtomography for the characterization of a diffusion tensor imaging phantom

Kaczmarek Ł., Wejrzanowski T., Skibiński J., Maksimczuk M., Krzyżak A.

Acta Geophysica

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2017

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Vol. 65, no. 1

259--268

EN

This paper addresses the issue of the quantitative characterization of the structure of the calibration model (phantom) for b-matrix spatial distribution diffusion tensor imaging (BSD-DTI) scanners. The aim of this study was to verify manufacturing assumptions of the structure of materials, since phantoms are used for BSD-DTI calibration directly after manufacturing. Visualization of the phantoms’ structure was achieved through optical microscopy and high-resolution computed microtomography (µCT). Using µCT images, a numerical model of the materials structure was developed for further quantitative analysis. 3D image characterization was performed to determine crucial structural parameters of the phantom: porosity, uniformity and distribution of equivalent diameter of capillary bundles. Additionally calculations of hypothetical flow streamlines were also performed based on the numerical model that was developed. The results obtained in this study can be used in the calibration of DTI-BST measurements. However, it was found that the structure of the phantom exhibits flaws and discrepancies from the assumed geometry which might affect BSD-DTI calibration.

6

Application of polymer composites with plant reinforcement used in machine and aircraft environmental conditions

Krzyżak A., Grzesik N.

Journal of KONES

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2016

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Vol. 23, No. 2

223--230

EN

Plant reinforced composites are more widely introduced in the automotive or construction industry. Due to good thermal and acoustic insulation, low weight, economical and ecological benefits and limitations resulting mostly from low mechanical strength, they are used primarily as elements, which do not carry heavy loads. Yet, they perform decorative and insulating functions. Expanding the spectrum of usage is connected with analysing properties of these materials in various application conditions. The following article presents results of static tensile tests of composites reinforced with jute, linen and cotton used in changeable environmental conditions. The significance of influence exerted by such factors as water, hydraulic oil, technical lubricant and conditions of moderate climate were evaluated. Taking into account the potential possibilities of using composites with natural reinforcement in aircraft construction, e.g. in helicopters, the influence exerted by direct impact of aviation fuel were tested. It was concluded that different application conditions subject to research do not exert an identical influence on tested composites. Statistically significant influence on the change of tensile strength is exerted while application of cotton composites in water. Composites with jute lose their properties during usage in autumn moderate climate and in hydraulic oil. Conversely, composites reinforced with linen react negatively to the environment of technical lubricant and aviation fuel.

7

Comparison of operational availability of public city buses by analysis of variance

Rymarz J., Niewczas A., Krzyżak A.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 3

373--378

EN

This paper analyses the influence of selected factors of operational availability of public city buses from the Municipal Transport Company (MPK) in Lublin based on a case study for two makes of buses: Solaris and Mercedes-Benz. The study investigated changes in operational availability in a function of operating time with a division into two periods of operation: warranty and post-warranty. To evaluate the significance of differences between average operational availability with regards to the above periods, one-way analysis of variance was applied. The results demonstrate that in the warranty period the operational availability of both makes of buses is similar, while the post-warranty period reveals a significant difference, with the operational availability being higher for Mercedes buses. As a result, this method can be of use for investment projects during purchase of new vehicles.

PL

Celem pracy była analiza wpływu wybranych czynników gotowości technicznej autobusów komunikacji miejskiej na przykładzie autobusów marki Solaris i Mercedes-Benz w Miejskim Przedsiębiorstwie Komunikacyjnym (MPK) w Lublinie. Przeprowadzono badania zmian gotowości technicznej w funkcji czasu użytkowania z podziałem na dwa okresy użytkowania: gwarancyjny i pogwarancyjny. Do sprawdzenia istotności różnic średnich wartości gotowości technicznej, w zależności od marki autobusów oraz w zależności od okresów eksploatacji zastosowano jednoczynnikową analizę wariancji. Wykazano, że w okresie gwarancyjnym gotowość techniczna autobusów obu marek jest porównywalna, natomiast w okresie pogwarancyjnym jest istotnie różna, wyższa dla autobusu marki Mercedes. W rezultacie metoda ta może zostać użyta do programu inwestycyjnego podczas zakupu nowych pojazdów.

8

Ocena możliwości wzniesienia się w powietrze śmigłowca Guimbal Cabri G2 z wykorzystaniem rozmytego systemu eksperckiego

Mendrek M., Grzesik N., Krzyżak A.

Autobusy : technika, eksploatacja, systemy transportowe

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2016

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R. 17, nr 12

1212--1216

PL

W artykule omówione zostały możliwości aerodynamiczne śmigłowca Guimbal Cabri G2. Rozważania oscylują wokół pytania na jaką wysokość maszyna będzie w stanie się wznieść biorąc pod uwagę warunki początkowe założone w projekcie. Analizowano masę śmigłowca, masę członków załogi oraz masę bagażu zabieranego przez załogę. Oceniano wysokość i minimalny czas w jakim śmigłowiec będzie się wznosił. Zaprojektowany układ mógłby zostać wykorzystany w praktyce podczas lotów szkoleniowych, rekreacyjnych, wykonywania różnorakich zadań lotniczych oraz znacząco ułatwić proces przygotowania się do lotu załogi, w aspekcie możliwości szybkiej analizy obciążenia masowego śmigłowca. Zaprojektowano rozmyty system ekspercki w oprogramowaniu Matlab oraz przeprowadzono symulację jego działania w programie Simulink.

EN

The article discusses the Guimbal Cabri G2 aerodynamic properties. The main question is what is helicopter rising altitude under initial conditions assumed in the project. The aircraft, crew and baggage weight analysis were the scope. The altitude and the minimum time in which the helicopter ascends were assessed. The designed project can be used in the wide spectrum of the air tasks. It will provide improvements during crew pre-flight preparations in terms of heli-copter weight capacity. Matlab and Simulink software was used in designing and work simulation process.

9

The effect of simulated climatic conditions of ageing on properties of selected polymer composites

Dulebova L., Krzyżak A., Dulebova M.

Zeszyty Naukowe / Wyższa Szkoła Oficerska Sił Powietrznych

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2015

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Nr 3

71--79

EN

Nowadays designers and engineers readily turn to plastics because they offer combinations of properties not available in any other materials. Plastics offer advantages such as lightness, resilience, resistance to corrosion, colour fastness, transparency, ease of processing, etc., and although they have their limitations, their exploitation is limited only by the ingenuity of the designer. Degradation of the polymers under the influence of temperature, light, humidity and oxygen leads to changes in structures such as the increase in crosslinking, reducing the degree of polymerization, oxidation or recrystallization of the molecular chains. The result of the ageing process are reversibly or irreversibly a deterioration of processing and changing of properties. The aim of this paper was the comparison of change of selected properties of polymer composites used for the production of parts in the electrical industry in changing the thermal conditions. Materials ABS, PA6 and PBT were tested and the samples were exposed to different climatic conditions. Static tensile test and 3- point bend test were used for testing and samples were used by injection molding.

PL

Obecnie projektanci i inżynierowie chętnie sięgają po tworzywa sztuczne ze względu na kombinacje właściwości, które oferują, nieosiągalne w przypadku innych materiałów. Tworzywa mają liczne zalety, takie jak: lekkość, sprężystość, odporność na korozję, trwałość koloru, przejrzystość, łatwość obróbki, itd. i mimo swoich ograniczeń, ich zastosowanie jest ograniczone tylko poprzez pomysłowość lub jej brak u projektanta. Degradacja polimerów pod wpływem temperatury, światła, wilgotności i tlenu prowadzi do zmian w strukturze, takich jak wzrost sieciowania, redukcja stopnia polimeryzacji, utlenianie czy też rekrystalizacja łańcuchów molekularnych. Skutki procesu starzenia to odwracalne bądź nieodwracalne pogorszenie przetwarzania i zmiana właściwości. Celem niniejszej pracy było porównanie zmian wybranych właściwości kompozytów polimerowych stosowanych w produkcji części w przemyśle elektrycznym przy zmieniających się warunkach termicznych. Badano materiały ABS, PA6 PBT, których próbki poddani działaniu różnych warunków klimatycznych. W badaniach wykorzystano statyczne próby rozciągania oraz 3-punktowy test giętkości, natomiast próbki były wykorzystane w procesie formowania wtryskowego.

10

Wybrane aspekty niezawodności kompozytów polimerowych wzmocnionych bawełną

Krzyżak A.

Logistyka

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2015

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nr 3

2634--2639, CD 1

PL

Ocena niezawodności elementów budowy maszyn jest ściśle związana z właściwościami materiału, z którego zostały wykonane. W przypadku inżynierskich rozwiązań konstrukcyjnych dotyczy to przede wszystkim właściwości mechanicznych, takich jak wytrzymałość na rozciąganie, wytrzymałość na zginanie czy udarność. Wytrzymałość na zginanie kompozytów bawełnianych niezależnie od metody eksploatacji cechuje duży rozrzut wyników, co wynika z niejednorodności struktury oraz dużego prawdopodobieństwa wystąpienia defektów w postaci pęcherzyków powietrza. Oddziaływanie niskiej temperatury otoczenia powoduje nieznaczny wzrost wytrzymałości na zginanie kompozytów wzmocnionych bawełną. Funkcje rozkładu prawdopodobieństwa wyraźnie wskazują, że największemu uszkodzeniu, przy najniższych siłach obciążenia zewnętrznego ulegają te kompozyty, które były eksploatowane w warunkach jesiennych. Wyniki analizy niezawodności kompozytów ze względu na wytrzymałość pozwalają na oszacowanie prawdopodobieństwa spadku wytrzymałości do wartości określonej różnymi założeniami konstrukcyjnymi oraz względami bezpieczeństwa.

EN

Evaluation of reliability machine construction components is closely related with the properties of the material from which they were made. For engineering constructional solutions, this concerns mainly the mechanical properties such as tensile strength, bending strength and impact strength. Bending strength of composites with the cotton, regardless of the method of operation is characterized by large scatter of results, due to non-uniformity of structure and high probability of existence of defects in the form of air bubbles. The impact of low temperature results in a slight increase in the bending strength of composites reinforced with cotton. The probability distribution functions clearly show that the greatest damage, with the lowest external load forces are those composites that were operated under conditions of autumn. The results of the analysis of the reliability of composites due to the strength allow estimation of the probability of decrease in strength to a value specified different assumptions structural and safety reasons.

11

Significance of pressure solution structures analysis for fluid flow studies – examples from Struga-1 well (Zechstein Main Dolomite; W Poland): first results

Górka J., Świerczewska A., Krzyżak A.

Geology, Geophysics and Environment

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2015

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Vol. 41, no. 1

82--83

EN

The internal structure and composition of pressure solution structures are factors that may influence petroleum generation and migration (Hofmann & Leythaeuser 1995). Pressure solution structures (PSS) i.e. stylolites and solution seams occur frequently in Zechstein carbonates of Poland (Kłapciński 1972). They are common in rocks of the Zechstein Main Dolomite. These rocks are both the source and reservoir rocks (Kotarba et al. 2000). Therefore, defining the role of pressure solution structures in migration of hydrocarbons is a key element of reservoir characterization.The main aim of this study is to determine the role of pressure solution structures in fluid flow in dolomites from the Polish part of the Zechstein Main Dolomite (Ca2). Sixteen samples were collected from the core of the Struga-1 well for mineralogical, microstructural and petrophysical studies. The inflow of oil was obtained from the interval within the range of 2042.5–2058.5 meters (Kotarba et al. 2000). This interval was sampled and it corresponds to an occurrence of carbonates of the Zechstein Main Dolomite. Lithology of the sampled cored interval was described based on macroscopic studies. Standard thin sections were studied using polarization microscopy for identification of mineral composition and microstructures. These studies were supplemented by observations in UV light for identification of organic matter and hydrocarbon inclusions. Chemical staining method was used in identification of carbonate minerals in 6 thin sections by solution of alizarin red and potassium ferricyanide. All thin sections were observed under the cathodoluminescence (CL). PSS were studied in details using the scanning electron microscopy (SEM) with X-ray microanalysis (EDS). Frequency of their occurrence in the core was described by macroscopic and microscopic studies as number of PSS per 1 m and per 1 cm respectively. Nuclear magnetic resonance (NMR) was used to define the value of porosity. These measurements were performed on eight water-saturated samples using the 2MHz Magritek Rock Core and 24MHz Tomography system. The pore size distribution (PSD) of the rock sample was precisely determined by T2CMPG experiments. According to the paleogeographic interpretation of Ca2 basin Struga-1 well is located in a platform depression (flat) (comp. Kotarba et al. 2000). This was a low-energy zone dominated by mudstones, wackestones with numerous bioclasts, e.g. gastropodes, foraminifers and bivalves. Intraclasts were delivered from adjacent high-energy zones (Czekański at al. 2010). In a new interpretation by Kosakowski & Krajewski (2013) the well intersects facies association of the carbonate platform lower slope. The studied rocks are fine crystalline dolomites. Coarser crystals occur only at the lowest part of the studied core. In most of thin sections primary textures are not recognized. In some samples bioclasts replaced by dolomite as well as anhydrite and gypsum are visible. Under the CL the dolomite mosaics show dark orange to brown luminescence. Relicts of calcite are absent or very rare. Anhydrite is observed as patches filling pore spaces. Moldic and intercrystalline porosity is present. Moldic porosity is probably related to dissolution of bioclasts and halite crystals. A few vertical microfractures were noted. Some of them are filled by dolomite, blocky anhydrite, and gypsum and fluorite crystals. However, some microfractures are still open and filled in part by drusy anhydrite and/or gypsum crystals. The effective porosity of dolomite samples varies from 1.59% to 2.69%. Solution seams are horizontally oriented. Their thickness is up to 0.1 mm. Some of the seams form clusters up to 1 mm t hick . In thin sections number of solution seams varies from 0/cm to 8/cm. Dark thicker seams are also visible on the core. They are most frequent in t he middle par t of t he core profile (up to 200/m). Two groups of stylolites are noted: vertically and horizontally oriented. Microscopic studies concerned only horizontal, diagenetic structures. Amplitude of them is diverse reaching 1.2 cm. They occur mostly in the lowest part of the core profile where solution seams are rare. Fluorescence microscopy of polished sections revealed a presence of organic matter. Dark brown to black organic laminae and orange oil inclusions are present inside PSS. Framboidal pyrite was recognized bot h in dolomite and solution seams. Clay minerals are common in solution seams. Based on SEM-EDS analyses fluorite was recognized along stylolites.Thin wavy microfractures are associated with PSS. These microfractures are short (i.e. up to 1 mm), less than 0.01 mm thick. They are oriented parallel to PSS. Relationship between porosity values and quantity of PSS is unclear. Maybe observed microfractures reflect stress anisotropy in the clay seam and stylolite. Summing up, PSS have recorded migration of oil as well as migration of other fluids, which were responsible for fluorite mineralization. Organic matter accumulation in stylolites and solution seams of carbonate rocks was documented among others by Leythaeuser (1995). In the studied rocks, this accumulation is marked by an occurrence of dark laminae probably overmature organic matter. The presented results show that PSS hosted in dolomites from Struga-1 well impacted redistribution of organic matter and migration of fluids.

12

Identification of tectonic microstructures in flysch sandstones of the Outer Carpathians using X-ray nanotomography and nuclear magnetic resonance – first results

Radzik N., Świerczewska A., Krzyżak A.

Geology, Geophysics and Environment

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2015

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Vol. 41, no. 1

127--128

EN

Deformation bands and microfractures occurring in sandstones affect the petrophysical properties of the rock and determine fluid flow. Deformation bands are quasi-tabular structures, up to 5 mm thick that accommodate offsets on the order of a few centimeters (Fossen 2010). Such bands show different petrophysical properties in relation to the surrounding rocks and may function as either a path or a barrier to the migrating fluids (Antonellini et al. 1994, Fossen 2010). High porosity rocks show commonly low permeability due to the presence of deformation bands. Recognition of such relationships is important in petroleum geology, particularly for proper reservoir characterization (e.g. Fossen et al. 2007, Ballas et al. 2012, 2013). The aim of the study is to identify and to characterize deformation bands occurring in flysch sandstones of the Outer Carpathians using X-ray nanotomography and nuclear magnetic resonance (NMR). Moreover, the impact of sample size on obtained results was also studied. For this study, samples of medium-grained arenites showing catalclastic deformation bands have been collected from the lower Krosno Beds of the Silesian Nappe. Permeability of the studied samples measured along deformation bands and in perpendicular direction varies significantly, being 0.13 mD and <0.001 mD, respectively. Analyses were conducted using X-ray nanotomography Nanotom S General Electric. The recorded data were processed and analyzed using ImageJ and myVGL software. The NMR measurements were carried out on water-saturated samples using the 2MHz Magritek Rock Core Analyzer and 24MHz Tomography System. The pore size distribution (PSD) of the rock sample was determined precisely by T2CMPG experiments. The spatial estimation of the deformation bands achieved from T2 spatially resolved measurements. Complementary data regarding to band geometry was registered using three-dimensional Single Point Imaging (SPI) (comp. Zhang & Blümich 2014). Cylindrical plugs38 mm high and 25 mm in diameter were analysed. The same plugs were used for permeability measurements. The X-ray nanotomography measurements were carried out in three resolutions. The first measurement was carried out with a resolution of 4.2 microns, but the resultant images were difficult to interpret. Therefore, successive analyses were performed with a resolution of 20 microns covering the entire volume of the samples. After locating microstructures samples were X-rayed again with a resolution of 2.1 microns. In sections obtained at a resolution of 4.2 microns, fine structure attributable to deformation band reveals parallel grain orientation and higher density compared with the host sandstone. We observed a slight offset along deformation bands. Three-dimensional image of the sample obtained at a resolution of 20 microns determined the geometry of tectonic microstructures. In one of samples, two structures were recognized. One of them was oriented parallel to the axis of the core, the other was inclined at an angle of about 60 degrees. The thickness of deformation band visible in the cylindrical plug was much larger (2 mm) than the thickness of the surface obtained by visualization. This was due to the presence of microfractures, which formed along the deformation band. Measurement with a resolution of 2.1 microns took an upper base of the cylindrical plug. Two thin fractures and one relatively thick fracture (approx. 0.2 mm) were distinguished. This indicates that the deformation band visible on the surface of the core passes into the microfracture within the sample. It was also confirmed by the visualization with a resolution of 20 microns. Determination of porosity and permeability of the sandstone using the X-ray nanotomograph was impossible due to small pore size that the device is not able to register. However, visualization made with a resolution of 20 microns allowed to clarify the reasons for the different measurements of permeability. Increase of the permeability in the direction parallel to the axis of the core is caused by the presence of open microfractures. The NMR results confirmed possibility to visualize geometry of the bands and their influence for the spatial distribution of porosity. The results show that too large sample sizes make impossible to perform the analysis with high resolution. According to Rodrigues et al. (2015) sample dimensions of 15 × 10 × 10 mm are sufficient to determine the porosity of deformation bands. Published results on three-dimensional micro-tomography of deformation bands concern aeolian sandstones showing high mineralogical and textural maturity (Rodrigues et al. 2015). In contrast, studied flysch sandstones show large diversity of their mineral composition. Therefore, visualization of microtectonic deformation hosted in these sandstones is more difficult to interpret.

13

Wpływ napełniaczy ziarnistych na właściwości termoochronne i wytrzymałościowe polimerowych kompozytów aramidowych do zastosowań w konstrukcjach lotniczych

Komorek A., Przybyłek P, Kucharczyk W., Krzyżak A.

Logistyka

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2014

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nr 3

3030--3039

PL

W pracy zaprezentowano wyniki ablacyjnych badań termoochronnych oraz badań wytrzymałościowych epoksydowych laminatów aramidowych w aspekcie wpływ rodzaju napełniacza ziarnistego na wybrane właściwości kompozytu do zastosowań na elementy konstrukcji lotniczych. Jako wzmocnienie użyto 12 warstw tkaniny aramidowej o gramaturze 230 g/m2 rozmieszczonych w osnowie z żywicy epoksydowej Epidian 52 sieciowanej, w temperaturze pokojowej, utwardzaczem PAC. Właściwości osnowy kompozytów modyfikowano poprzez 15% dodatek: węglika krzemu SiC, pyłu węglowego C, mikrobalonów, karborundu Al2O3 montmorylonitu (MMT) oraz proszku wolframu W. Z wykonanych płyt kontrolnych (o wymiarach 200 mm x 150 mm) zostały wycięte próbki do badań ablacyjnych, udarności oraz wytrzymałości na ścinanie między-warstwowe. Jako główny parametr do oszacowania wpływu napełniaczy ziarnistych na ablacyjne właściwości termoochronne przyjęto maksymalną temperaturę tylnej powierzchni ścianki próbki izolującej ts. Ponadto określono względny ablacyjny ubytek masy Ua. Zbadano istotne właściwości mechaniczne: wytrzymałość na ścinanie międzywarstwowe τILSS i udarność KC.

EN

The paper presents the results of ablation thermo-protective studies and strength research of aramid epoxy laminates in terms of the particulate filler type impact on selected properties of composite components for use on aircraft structures. As a reinforcement were used 12 layers of aramid fabrics of a basis weight 230 g/m2 arranged in a matrix of epoxy resin Epidian 52 crosslinked with PAC hardener, at room temperature. Matrix composite properties were modified by the addition of 15% Silicon Carbide SiC, carbon dust C, microballoons, carborundum Al2O3, montmorillonite (MMT), and powder made of tungsten W. Ablative, impact strength and interlaminar shear strength test pieces were cut from the performed composite sheet. As the main parameter to estimate the effect of particulate fillers on ablative thermo-protective properties, the maximum temperature of the rear surface of the wall sample ts was selected. Moreover, the relative ablation weight loss Ua was also specified. Important, mechanical properties of the material were determined: interlaminar shear strength τILSS and toughness KC.

14

Możliwości wykorzystania włókien aramidowych w ablacyjnych osłonach termoochronnych

Kucharczyk W., Nachyła P., Krzyżak A.

Logistyka

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2014

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nr 5

886--894

PL

W artykule przedstawiono wyniki badań procesu ablacji materiałowej epoksydowych laminatów szklano-aramidowych pod kątem możliwości ich zastosowań na termoochronne osłony autonomiczne do zabezpieczania maszyn i urządzeń technicznych oraz budowli i elementów infrastruktury budowlanej w warunkach zagrożenia pożarowego lub krótkotrwałego, intensywnego oddziaływania wysokotemperaturowego strumienia cieplnego. Właściwości termoochronne laminatów modyfikowano zmianą ich składów fazowych. Na materiał osnowy epoksydowej użyto żywice Epidian 601 sieciowaną albo utwardzaczem dwumianowym IDA (53 ns) albo utwardzaczem TFF (27 ns). Wzmocnieniem włóknistym były tkaniny aramidowe: Nomex T993 o gramaturze 720 g/m2 oraz Kevlar o gramaturze 300 g/m2, jak również tkanina szklana o gramaturze 300 g/m2. Badania zostały oparte o statyczne metody planowania doświadczeń. Określono jakościowy i ilościowy wpływ komponentów na termochronne właściwości kompozytów epoksydowych: średnią temperaturę maksymalną tylnej powierzchni ścianki próbki ablacyjnej oraz średni względny ablacyjny (erozyjny) ubytek masy.

EN

The paper presents the results of ablation studies of aramid epoxy laminates in terms of the woven fabrics fillers type influence on selected thermo-protective properties of composite components for use on machines, technical equipments and modern building constructions or in tunnelling designing thermal-protections. As a reinforcement were used layers of Nomex fabrics of a basis weight 720 g/m2 and Kevlar fabrics of a basis weight 300 g/m2, as well as glass fabrics of a basis weight 300 g/m2 – all woven fabrics arranged in a matrix of epoxy resin Epidian 601 crosslinked with hardeners IDA or TFF, at room temperature. The composites were treated with hot combustion gases to determinate the temperature profiles across the studied samples (cubes 10x25x35 mm). Carbonization of the crosslinked matrix was observed. As the main parameter to estimate the quantitative and qualitative effect of aramid fiber fillers on ablative thermo-protective properties, the maximum temperature of the back-side surface of the wall sample ts was determined and compared. Moreover, the relative ablation mass waste Ua was also specified.

15

Web–based framework for breast cancer classification

Bruździński T., Krzyżak A., Fevens T., Jeleń Ł.

Journal of Artificial Intelligence and Soft Computing Research

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2014

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Vol. 4, No. 2

149--162

EN

The aim of this work is to create a web-based system that will assist its users in the cancer diagnosis process by means of automatic classification of cytological images obtained during fine needle aspiration biopsy. This paper contains a description of the study on the quality of the various algorithms used for the segmentation and classification of breast cancer malignancy. The object of the study is to classify the degree of malignancy of breast cancer cases from fine needle aspiration biopsy images into one of the two classes of malignancy, high or intermediate. For that purpose we have compared 3 segmentation methods: k-means, fuzzy c-means and watershed, and based on these segmentations we have constructed a 25–element feature vector. The feature vector was introduced as an input to 8 classifiers and their accuracy was checked. The results show that the highest classification accuracy of 89.02 % was recorded for the multilayer perceptron. Fuzzy c–means proved to be the most accurate segmentation algorithm, but at the same time it is the most computationally intensive among the three studied segmentation methods.

16

The recognition of partially occluded objects with support vector machines, convolutional neural networks and deep belief networks

Chu J. L., Krzyżak A.

Journal of Artificial Intelligence and Soft Computing Research

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2014

|

Vol. 4, No. 1

5--19

EN

Biologically inspired artificial neural networks have been widely used for machine learning tasks such as object recognition. Deep architectures, such as the Convolutional Neural Network, and the Deep Belief Network have recently been implemented successfully for object recognition tasks. We conduct experiments to test the hypothesis that certain primarily generative models such as the Deep Belief Network should perform better on the occluded object recognition task than purely discriminative models such as Convolutional Neural Networks and Support Vector Machines. When the generative models are run in a partially discriminative manner, the data does not support the hypothesis. It is also found that the implementation of Gaussian visible units in a Deep Belief Network trained on occluded image data allows it to also learn to effectively classify non-occluded images.

17

Badanie wpływu podwyższonej temperatury na wytrzymałość na ściskanie drewna sosnowego impregnowanego środkiem ogniochronnym zawierającym SiO2

Ogrodnik P., Pieniak D., Krzyżak A., Walczak A.

Bezpieczeństwo i Technika Pożarnicza

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2014

|

Nr 3

115--122

PL

Cel: Celem artykułu było zaprezentowanie wyników badań doświadczalnych wpływu podwyższonej temperatury na wytrzymałość przy ściskaniu drewna sosnowego impregnowanego środkiem ogniochronnym zawierającym nanocząstki SiO2. Obecnie impregnaty tego typu są coraz częściej stosowane do zabezpieczenia elementów drewnianych. Metody: Próbki sosnowe do badań wytrzymałościowych, o wymiarach 40×40×60mm, zostały podzielone na dwie grupy. Część próbek została poddana impregnacji środkiem ognioochronnym, wodną dyspersją nanocząstek SiO2 o rozmiarach 10-20 nm. Próbki zanurzone w zawiesinie umieszczono w komorze próżniowej na czas 20 min, stosując podciśnienie rzędu (0,7 atm). Następnie próbki impregnowane i nieimpregnowane przetrzymywano przez 10 dni w temperaturze pokojowej. Mikroskopem SEM wykonano zdjęcia impregnowanych i nieimpregnowanych próbek. Przed przystąpieniem do badań wytrzymałościowych próbki zostały poddane obróbce termicznej. Podstawowym urządzeniem na stanowisku do wygrzewania próbek był średniotemperaturowy piec komorowy typu PK 1100/5. Regulowanie pracą pieca odbywało się przy użyciu sterownika programator PSP 1 wraz z komputerem pomiarowym i oprogramowaniem ThermoPro. Próbki były wygrzewane w piecu komorowym aż do osiągnięcia temperatury 250ºC, przetrzymane w zaplanowanej temperaturze przez 10 lub 20 minut, a następnie schładzane do temperatury otoczenia. Badania wytrzymałościowe przeprowadzono na uniwersalnej maszynie wytrzymałościowej Zwick/Roell Z100, badania realizowano ze stałą prędkością przesuwu trawersy wynoszącą 2 mm/min. Wyniki: Przedstawione wyniki badania są ściśle związane z bezpieczeństwem konstrukcji drewnianych poddanych oddziaływaniu podwyższonej temperatury, a także z możliwością stosowania nowoczesnych preparatów ogniochronnych zawierających nanocząstki. W wyniku przeprowadzonych badań można stwierdzić, że szybka dekohezja struktury drewna w warunkach oddziaływania podwyższonych temperatur następuje w zakresie od 220 do 250ºC. Proces degradacji struktury drewna najszybciej postępuje w warstwie wierzchniej, przyczynia się do tego m.in. wysoka izolacyjność cieplna drewna. Wpływ impregnacji środkiem ogniochronnym na bazie krzemionki na wytrzymałość doraźną drewna przy ściskaniu jest jednoznaczny. Obserwowano wyższą wytrzymałość drewna nieimpregnowanego we wszystkich przedziałach temperatur. Wnioski: Impregnacja wodną dyspersją cząstek SiO2 w nieznacznym stopniu pogarsza wytrzymałość na ściskanie drewna. Podsumowując, należy stwierdzić, że impregnacja środkiem ogniochronnym na bazie SiO2 pogarsza właściwości wytrzymałościowe w warunkach drewna pracującego na ściskanie. W badaniach nie wykazano korzystnego wpływu impregnacji na wytrzymałość drewna przy ściskaniu po ekspozycji w podwyższonych temperaturach.

EN

Objective: The aim of the article was to present the results of a study on the influence of high temperatures on the compressive strength of pine timber treated with the flame retardant containing SiO2 particles. Nowadays, this type of retardant is used more and more frequently for the purposes of wooden elements protection. Methods: Samples for strength investigations with dimensions of 40x40x60 mm3 were divided into two groups. Some of the samples were impregnated with the use of the method of aqueous dispersion of SiO2 nanoparticles in 10-20 nm range. Samples were immersed in the liquid and placed in a vacuum chamber for 20 min. at about 0.7 atm. Then, the impregnated and non-impregnated samples were stored for 10 days at room temperature. The impregnated and non-impregnated samples were photographed with the use of SEM microscope. Before the strength tests, the samples were heated. The main instrument of the heating test equipment used to heat the samples was an average-temperature chamber furnace – type PK 1100/5. The temperature in the furnace was controlled by PSP 1 programmer together with a measuring computer and ThermoPro software. The samples were heated up to 250ºC and stored in such temperature for 10 or 20 minutes. Afterwards, the samples were cooled down to the room temperature. Strength tests have been conducted with the use of Zwick/Roell Z100 universal testing machine with crosshead speed of 2 mm/min. Results: The research subject is closely related to the safety of wood constructions under high temperatures as well as the possibility of the usage of modern flame retardants containing nanoparticles. Based on the conducted studies, it may be said that the fast degradation of wood structure occurs in the temperature range from 220 oC to 250ºC. Degradation process of wood is faster in the top layer than in lower layers due to e.g. high thermal insulation of wood. Timber treatment with silica-based fire retardants has a significant impact on compressive strength. In each temperature interval the strength of non-treated timber has been higher than in case of treated timber. Conclusion: Treatment with the aqueous dispersion of SiO2 particles influences on the decrease of compressive strength of timber. To sum up, it should be stated that treatment with silica-based flame retardants has negative influence on the strength of wood under compression. The presented studies do not show positive influence of flame retardant treatment on compressive strength of timber after high temperatures exposure.

18

Odporność na uderzenia laminatów stosowanych na elementy nadwozia pojazdów transportowych

Krzyżak A., Nizio M.

Autobusy : technika, eksploatacja, systemy transportowe

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2014

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R. 15, nr 5

78-82

PL

Powszechnie stosowane na osłony, zderzaki, obudowy maszyn i urządzeń laminaty poliestrowo-szklane z racji pełnionej funkcji są narażone na różnego rodzaju dynamiczne oddziaływanie siły skupionej. Uderzenia często mają charakter powtarzających się cyklicznie zdarzeń. W artykule zaprezentowano wyniki badań dotyczące laminatów poliestrowo-szklanych wzmocnionych matami oraz tkaninami poddanych kilkudziesięciokrotnym uderzeniom. Zastosowano znormalizowaną metodę spadającego grota, metodę stopniowego wyznaczania. Wyniki pomiarów wskazują na dużą odporność na przebicie laminatów wykonanych z tkanin szklanych, równocześnie wskazują na znalezienie rozsądnego kompromisu pomiędzy laminatami o znacznej sztywności, tańszych, wykonanych z mat, a dużą wytrzymałością na uderzenia laminatów o stosunkowo niskiej sztywności przy małej liczbie warstw tkanin, przez to tańszych.

EN

Commonly used on the cover, bumpers, machinery and equipment enclosures polyester-glass laminates because of their function are exposed to various types of dynamic interaction of concentrated force. Strokes often are cyclically repeated events. The article presents the results of research on fi berglass reinforced mats and textiles of glass fi ber treated multiple repeated impacts. Used a standardized method of falling the mainsail, progressive method of selection. The measurement results indicate a high resistance to puncture laminates made from glass fabric, while point to fi nd a reasonable compromise between the laminates of substantial the stiffness, cheaper, made of a mat, and the high impact resistance of laminates with relatively low the stiffness at low number of layers of fabrics.

19

Water absorption of thermoplastic matrix composites with polyamide 6

Krzyżak A., Gąska J., Duleba B.

Zeszyty Naukowe / Akademia Morska w Szczecinie

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2013

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nr 33 (105)

62--68

EN

This paper describes the process of drying of thermoplastic composites warp knows polyamide 6, an engineering polymer material. The results of absorption measurements of pure and polyamide 6 reinforced with cut glass fiber. Composite for injection molding processing conditioned in conditions similar to those prevailing in industrial warehouses and exposed to direct contact with water. Both, in one and in the secondo case of modified natural polyamide 6 cut glass fiber polymer material reduces the susceptibility to moisture absorption. Being the most important for the moisture content in the material has the first 10 hours of exposure of granules to various weather conditions.

20

Comparative study of shape, intensity and texture features and support vector machine for white blood cell classification

Habibzadeh M., Krzyżak A., Fevens T.

Journal of Theoretical and Applied Computer Science

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2013

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Vol. 7, nr 1

20--35

EN

The complete blood count (CBC) is widely used test for counting and categorizing various peripheral particles in the blood. The main goal of the paper is to count and classify white blood cells (leukocytes) in microscopic images into five major categories using features such as shape, intensity and texture features. The first critical step of counting and classification procedure involves segmentation of individual cells in cytological images of thin blood smears. The quality of segmentation has significant impact on the cell type identification, but poor quality, noise, and/or low resolution images make segmentation less reliable. We analyze the performance of our system for three different sets of features and we determine that the best performance is achieved by wavelet features using the Dual-Tree Complex Wavelet Transform (DT-CWT) which is based on multi-resolution characteristics of the image. These features are combined with the Support Vector Machine (SVM) which classifies white blood cells into their five primary types. This approach was validated with experiments conducted on digital normal blood smear images with low resolution.