Hellenic Aerospace Industry

About: Hellenic Aerospace Industry is a company organization based out in Athens, Greece. It is known for research contribution in the topics: Structural health monitoring & Optical fiber. The organization has 63 authors who have published 114 publications receiving 1816 citations. The organization is also known as: Elliniki Aeroporiki Viomichania.

Computer-aided tumor detection in endoscopic video using color wavelet features

Abstract: We present an approach to the detection of tumors in colonoscopic video. It is based on a new color feature extraction scheme to represent the different regions in the frame sequence. This scheme is built on the wavelet decomposition. The features named as color wavelet covariance (CWC) are based on the covariances of second-order textural measures and an optimum subset of them is proposed after the application of a selection algorithm. The proposed approach is supported by a linear discriminant analysis (LDA) procedure for the characterization of the image regions along the video frames. The whole methodology has been applied on real data sets of color colonoscopic videos. The performance in the detection of abnormal colonic regions corresponding to adenomatous polyps has been estimated high, reaching 97% specificity and 90% sensitivity.

A comparative study on the microstructure and surface property evaluation of coatings produced from nanostructured and conventional WC–Co powders HVOF-sprayed on Al7075

Abstract: Conventional and nanostructured WC-12 wt.% Co powders were HVOF sprayed on Al7075-T6. The nanocoatings presented slightly less microporosity, higher microhardness, higher fracture toughness but higher decarburization, than the conventional ones. The nanocoatings exhibited greater resistance to general corrosion and localized corrosion in 3.5% NaCl than their conventional counterparts. Other than an occasional removal of WC nanoparticles, corrosion modes appeared similar for both types of coatings, characterized by selective dissolution of Co, formation of protective surface films and crevice corrosion along interlayer boundaries. Both types of coatings exhibited high dry sliding wear resistance. Nevertheless, the wear performance of the nanocoatings was even superior than that of their conventional counterparts. Main wear modes included plastic deformation of binder, oxidative wear leading to the formation of lubricating oxides and adhesive wear leading to the formation of alumina-rich surface depositions (from the Al 2 O 3 counter balls). Coating of Al7075 with nano WC–12Co was proved effective in terms of microstructural features, corrosion and wear behaviour.