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1

A linearization-based hybrid approach for 3D reconstruction of objects in a single image

Kotan Muhammed, Öz Cemil, Kahraman Abdulgani

International Journal of Applied Mathematics and Computer Science

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2021

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Vol. 31, no. 3

501--513

EN

The shape-from-shading (SFS) technique uses the pattern of shading in images in order to obtain 3D view information. By virtue of their ease of implementation, linearization-based SFS algorithms are frequently used in the literature. In this study, Fourier coefficients of central differences obtained from gray-level images are employed, and two basic linearization-based algorithms are combined. By using the functionally generated surfaces and 3D reconstruction datasets, the hybrid algorithm is compared with linearization-based approaches. Five different evaluation metrics are applied on recovered depth maps and the corresponding gray-level images. The results on defective sample surfaces are also included to show the effect of the algorithm on surface reconstruction. The proposed method can prevent erroneous estimates on object boundaries and produce satisfactory 3D reconstruction results in a low number of iterations.

2

Multi-objective optimization of WEDM process parameters of Ti49.4-Ni50.6 shape memory alloy for orthopaedic implant application

Takale A. M., Chougule N. K.

Archives of Materials Science and Engineering

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2018

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Vol. 93, nr 1

12--31

EN

Purpose: This paper focuses on the investigation on the effect of process parameters such as pulse on time (Ton), pulse off time (Toff), spark gap set voltage (SV), wire feed (WF) and wire tension (WT) on the responses such as the material removal rate (MRR), surface roughness (SR), kerf width (KW) and dimensional deviations (DD) of Ti49.4Ni50.6 (at.%) shape memory alloy (SMA) machined by WEDM. Ti-Ni SMA has fascinating properties and biocompatibility, it is considered for the present work. Design/methodology/approach: As per the Taguchi technique, L18 orthogonal array experiments on WEDM have been performed. The signals to noise (S/N) ratio plots are analysed to determine the influence of process parameters. Analysis has been tested through analysis of variance (ANOVA). SEM images are taken to confirm the results offering better surface quality. Findings: It was observed that pulse on time is the most significant factor for MRR and SR with the contribution of 35.69% and 59.02% respectively. The SV is a significant factor for KW and DD with contributions of 47.35% and 30.03% at 95% confidence level. A multi-response optimization has been carried out using grey relational analysis (GRA) to determine the optimum combination of process parameters. It is shown that, through GRA the optimal machining parameter setting such as A2B1C3D2E1 i.e. (pulse on time of 115 machine unit, pulse off time of 20 machine unit, spark gap set voltage of 90 V, wire feed of 6 m/min and wire tension of 3 machine unit) has been observed for maximum MRR and minimum SR, KW and DD. Young’s modulus checked for biocompatibility. Research limitations/implications: Heat treatment process like annealing is found to be most suitable to recover shape memory effect of WEDMed samples.

3

Synthesis and characterization of cross-linked poly(esterurethane)s for elastomeric bearings

Oprea S.

Polimery

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2010

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T. 55, nr 9

634-640

EN

Cross-linked poly(esterurethane) elastomers (PEURs) have been synthesized in a two-step synthesis. In the first step poly(ethylene adipate) diol was reacted with 4,4'-diphenyl-methane diisocyanate, then the obtained prepolymers were chain extended with bifunctional precursor (1,3-propane diol or 1,5-pentane diol) chains and a trifunctional cross-linker (glycerine) at stoichiometric ratios, resulting in a series of cross-linked products with various hard segment (HS) of various structure and content. Their thermal and mechanical properties were determined. Due to phase separation and cross-linked hard segments, propane diol based polyurethane exhibited high mechanical properties. The replacement of propane diol with pentane diol had a negative effect on these mechanical properties. The described cross-linked PEURs possessed strain/shape recovery properties.

PL

Usieciowane elastomeryczne poli(estrouretany) (PEUR) otrzymywano w wyniku dwuetapowego procesu obejmującego syntezę prepolimeru w reakcji diolu na podstawie poli(adypinianu etylenu) (PEA, c. cz. 2000) z 4,4'-diizocyjanodifenylometanem (MDI) i następnie przedłużanie łańcucha tego prepolimeru z zastosowaniem 1,3-propanodiolu (D) bądź 1,5-pentanodiolu (PD) z jednoczesnym sieciowaniem przy użyciu gliceryny (Gly) (tabela 1). Uzyskano w ten sposób próbki PEUR (D1-D3 oraz PD1-PD3) różniące się zawartością oraz budową segmentów "twardych" i twardością (tabela 2). Scharakteryzowano widma IR tych produktów (rys. 2 i 3), ich właściwości cieplne (rys. 4, tabela 3) oraz przebieg krzywych rozciągania (rys. 5). Szczegółowo przeanalizowano zachowanie się PEUR w próbach odkształcania pod wpływem sił ścinających (warunki quasi-statyczne, amplituda 5 lub 50 kN, rys. 7-10). Zastąpienie D przez PD znacznie pogarsza właściwości mechaniczne produktów. Opisywane usieciowanie PEUR poddane działaniu naprężeń odkształcających mają zdolność powrotu do pierwotnego kształtu.

4

Effect of wheel velocity on texture formation and shape memory in Cu-Al-Ni based melt-spun ribbons

Goryczka T.

Archives of Metallurgy and Materials

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2009

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Vol. 54, iss. 3

755-763

EN

The Cu-Al-Ni-Mn and Cu-Al-Ni-Ti shape memory alloys were melt-spun from 1250C applying different combination of the wheel velocity (from 12 m/s up to 26 m/s). The texture consists mainly of the <100> fibre component and two sheet components orientation: {100}<001> or/and {100}<011> in the Cu-Al-Ni-Mn ribbons. In a case of the Cu-Al-Ni-Ti ribbons spun with 12m/s or 19m/s only <100> fibre component and sheet texture {100}<011> were observed. However, increase of the wheel velocity up to 26m/s causes formation of the <111> and {111}<112> textural components. The grains orientation significantly influenced the shape recovery measured as a change of elongation under constant load during thermal cycling. The maximum of recoverable strain under constant tensile load was 5,8% and 6,2% for Cu-Al-Ni-Mn and Cu-Al-Ni-Ti alloy, respectively.

PL

Stopy Cu-Al-Ni-Mn oraz Cu-Al-Ni-Ti wykazujące efekt pamięci kształtu wytworzono metodą szybkiego schładzania z fazy ciekłej w układzie pojedynczego bębna chłodzącego. Odlano serie taśm z temperatury 1250C stosując różne szybkości obrotowe bębna od 12m/s do 26m/s. Tekstura w tasmach stopu Cu-Al-Ni-Mn składała się ze składowej osiowej < 100 > oraz dwóch składników tekstury pełnej: {100}<001> i {100}<011>. W przypadku taśm stopu Cu-Al-Ni-Ti odlewanych stosując obroty bębna 12m/s i 19m/s stwierdzono obecność tylko dwóch składowych tekstury <100> oraz {100}<011>. Jednakże zwiększenie obrotów bębna do 26m/s spowodowało uformowanie składowych <111> oraz {111}<112>. Orientacja ziaren znaczaco wpłynęła na odzysk kształtu zmierzony jako wydłużenie w trakcie zmian temperatury przy stałym obciążeniu rozciągającym. Najwyższa wartość wydłużenia, jaka uzyskano w taśmach stopu Cu-Al-Ni-Mn to 5,8% natomiast 6,2% w taśmach Cu-Al-Ni-Ti.