Wyniki wyszukiwania - BazTech

1

Cross-Entropy Based Image Thresholding

Malik M., Spurek P., Tabor J.

Schedae Informaticae

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2015

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Vol. 24

21--29

EN

This paper presents a novel global thresholding algorithm for the binarization of documents and gray-scale images using Cross-Entropy Clustering. In the first step, a gray-level histogram is constructed, and the Gaussian densities are fitted. The thresholds are then determined as the cross-points of the Gaussian densities. This approach automatically detects the number of components (the upper limit of Gaussian densities is required).

2

Surface modification of the AZ91 magnesium alloy

Strzelecka M., Iwaszko J., Malik M., Tomczyński S.

Archives of Civil and Mechanical Engineering

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2015

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Vol. 15, no. 4

854--861

EN

The main purpose of the study was to modify the surface layer of the AZ91 magnesium alloys with the use of the GTAW (Gas Tungsten Arc Welding) method. The remelting process was conducted with the use of an AC current with the concurrent cooling of the magnesium alloy in the liquid nitrogen bath. The assessment of the effectiveness of the treatment carried out with the use of the GTAW method was based on the analysis of the surface layer structure, and the investigation of hardness and the resistance to abrasion wear. Besides, the investigations of the corrosion resistance were carried out. The analysis of the treatment parameters combined with a macroscopic assessment and the structural changes in the surface layers allowed to distinguish some correlations attesting to the possibility of the remelting zone geometry shaping. The found structural effects of treatment such as significant refinement of the structure and its homogenization, as well as the positive results of corrosion investigations and mechanical tests proved that it is possible to achieve the intended research objectives and effectively modify magnesium alloys by the welding method.

3

Characteristic of Carbon Nanotubes Modified with Cobalt, Copper and Bromine

Zygoń P., Peszke J., Gwoździk M., Nitkiewicz Z., Malik M.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 2

675--679

EN

The paper presents results of studies on carbon nanotubes - as received, after cleaning and also after modification. Functional groups as well as metal nanoparticles have been attached, originating from cobalt sulphate, copper acetate and a mixture of hydrogen bromide and bromide. The surface studies on an atomic forces microscope (AFM), X-ray studies (phase composition analysis, crystallite sizes determination) as well as Raman spectroscopy studies were carried out on such nanotubes. The surface topography studies have shown that after the modification the diameter and length of nanotubes change. Also the surface development changes, which has been determined through roughness parameter measurements. The change of intensity, of crystallite size and of half-value width of main reflections originating from carbon for nanotubes modified in various ways have been determined using the X-ray analysis.

PL

W pracy przedstawiono wyniki badań nanorurek węglowych w stanie surowym, po oczyszczeniu jak również po modyfikacji. Zostały przyłączone grupy funkcyjne oraz nanocząstki metali, pochodzące od siarczanu kobaltu, octanu miedzi i mieszaniny bromowodoru z bromem. Dla takich nanorurek przeprowadzono badania powierzchni na mikroskopie sił atomowych (AFM), badania rentgenograficzne (analiza składu fazowego, określenie wielkości krystalitów) oraz badania spektroskopowe Raniana. Badania topografii powierzchni wykazały, że po modyfikacji nanorurek zmienia się ich średnica i długość. Zmienia się również rozwinięcie powierzchni co zostało wyznaczone za pomocą określenia parametru chropowatości. Za pomocą analizy rentgenograficznej określono zmianę intensywności, wielkości krystalitów oraz szerokości połówkowej refleksów głównych pochodzących od węgla dla nanorurek różnie modyfikowanych.

4

Zgrzewanie materiałów niejednorodnych w rozjazdach kolejowych

Tasak E., Ziewiec A., Lech S., Malik M., Kubic J.

Przegląd Spawalnictwa

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2013

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R. 85, nr 11

41--47

PL

W pracy przedstawiono wyniki badań wpływu parametrów zgrzewania na właściwości i strukturę złączy zgrzewanych stali szynowej z rozjazdem kolejowym ze staliwa wysokomanganowego (Hadfielda). Jako przekładki zastosowano staliwa austenityczne Cr-Ni o różnej stabilności austenitu. Wyniki badań wykazały, że zastosowanie staliwa austenitycznego o metastabilnej strukturze zapewnia lepsze umocnienie przekładki podczas eksploatacji. Duży wzrost twardości jest wynikiem umocnienia dyslokacyjnego oraz przemiany austenitu w martenzyt. Ponadto wykazano, że zbyt wysoka temperatura w obszarze zgrzewania i nieusunięcie nadtopionych powierzchni łączonych elementów prowadzi do powstania struktury martenzytycznej i tym samym obniżenia właściwości plastycznych złączy zgrzewanych.

EN

The paper presents the results of the welding parameters influence on the properties and structure of the rail steel and high-manganese (Hadfield) cast steel railway crossover welded joints). As the spacers used steel Cr-Ni austenitic steels with different austenite stability. The results showed that the use of metastable austenitic steel structure provides a better appreciation of slip during use. Large hardness increase is due to dislocation strengthening and transformation of austenite to martensite. Also shown that too high temperature in the welding area and melted surface remedy of joined elements leads to a martensitic structure and thus reduce the plastic properties of welded joints.

5

Two-Layer Structures of Ultra-Thin Metal Hexacyanoferrate Films: Charge Trapping Possibility of Application to Corrosion Protection

Miecznikowski K., Chojak M., Steplowska W., Makowski O., Kulesza P., Adamczyk L., Malik M., Gałkowski M., Bala H.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 9

1183-1193

EN

The possibility of fabrication of ultra-thin films of metal hexacyanoferrates, Prussian Blue, PB, and nickel hexacyanoferrate, NiHCNFe, by multiple sequential attachment of metal cations (self-assembled on 4-aminobenzoic acid monolayer) and hexacyanoferrate anions, has been demonstrated. These films can form a bilayer arrangement on glassy carbon when PB and NiHCNFe are deposited as inner and outer films, respectively. To avoid mixing of the NiHCNFe and PB redox sites, we introduce an polymer interlayer from poly(4-vinylpyridine) and Nafion. Since the outer NiHCNFe film is physically separated from the electrode surface, and it undergoes redox reactions at potentials characteristic of the inner PB film, an effect of the reversible charge state trapping (bistable switching) is observed. Astable bilayer structure can also be deposited on stainless steel. The whole concept may be of importance to corrosion protection since charge accumulated in the oxidized bilayer film tends to stabilize corrosion potential within passive range.