Variety Of Non-metallic Materials Research Articles

Passive imaging at 250 GHz for detection of face presentation attacks.

Face presentation attacks are becoming more efficient since new 3D facial masks are used. Passive terahertz imaging offers specific physical properties that may improve presentation attack detection capabilities. The non-zero transmission capability through a variety of non-metallic materials may provide necessary information for presentation attack detection. The aim of this paper is to present outcomes of a study on face presentation attack detection using passive imaging at 250 GHz. An analysis of presentation attacks for facial recognition systems using custom displayed and printed photographs, 3D-printed and full-face flexible 3D-latex masks, is provided together with spectral characterization of various presentation attack instruments. A set of experiments with various instruments and various sets of clothing is described and discussed. Finally, two presentation attack detection methods are proposed. The first method is based on a threshold corresponding to a difference between mean intensities of selected regions of interests while the second method uses eight different deep learning classifiers to detect presentation attacks. Results of two validation schemes are presented.

Special Issue on Fatigue and Fracture of Non-Metallic Materials and Structures

This Special Issue covers the broad topic of structural integrity of non-metallic materials, and it is concerned with the modelling, assessment and reliability of structural elements of any scale. In particular, the articles being contained in this issue concentrate on the mechanics of fracture and fatigue in relation to applications to a variety of non-metallic materials, including concrete and cementitious composites, rocks, glass, ceramics, bituminous mixtures, composites, polymers, rubber and soft matters, bones and biological materials, advanced and multifunctional materials.

The effects of thin compressive films on indentation fracture toughness measurements

Thin compressive films have been shown to decrease the lengths of radial cracks produced by a Vickers indentation in a variety of non-metallic materials. The intrinsic stress of submicrometre thick films deposited by reactive ion beam sputtering was measured by a cantilever technique. The change in the apparent indentation fracture toughness of the coated material was correlated with film thickness and stress, indentation load, and the nature of the substrate.

Comparative Aluminium Joint Evaluations in Varying Saltwater Exposure Conditions

Abstract The compatibility of aluminium in the presence of a wide variety of nonmetallic materials and corrosive saltwater has been the subject of study at our laboratories for many years. These studies have provided guides for evaluating the durability of aluminium bonded joints since an adhesive is only another form of nonmetallic material. A widely accepted standard test has been ASTM B117 which provides continuous joint exposure to a 5% sodium chloride salt fog. Publications in recent years,′-9 have cited test conditions where the exposure to saltwater has been intermittent rather than continuous. This was consistent with our observation in earlier years of investigating joint durability that continuous immersion in 3–½% sodium chloride solution was the most innocuous of exposures and less aggressive than immersion in deionized or distilled waters. Since 1978, our publications have included exposure results obtained by daily exposures to continuous salt fog for 16 hours followed by drying under ambien...