Microstructural evolution and strain hardening of Fe–24Mn and Fe–30Mn alloys during tensile deformation

High Mn steels demonstrate an exceptional combination of high strength and ductility owing to their sustained high work hardening rate during deformation. In the present work, the microstructural evolution and work hardening of Fe–30Mn and Fe–24Mn alloys during uniaxial tensile testing at 293 K and 77 K were investigated. The Fe–30Mn alloy did not undergo significant strain-induced phase transformations or twinning during deformation at 293 K, whereas these transformations were observed during deformation at 77 K. A modified Kocks–Mecking model was successfully applied to describe the strain hardening behavior of Fe–30Mn at both temperatures, and quantitatively identified the influence of stacking fault energy and strain-induced phase transformations on dynamic recovery. The Fe–24Mn alloy underwent extensive ε martensite transformation during deformation at both test temperatures. An analytical micromechanical model was successfully used to describe the work hardening of Fe–24Mn and permitted the calculation of the ε martensite stress–strain curve and tensile properties.     

Map management for robust long-term visual localization of an autonomous shuttle in changing conditions

Multimedia Tools and Applications - Changes in appearance present a tremendous problem for the visual localization of an autonomous vehicle in outdoor environments. Data association between the...     

Physico-Chemical,antioxidant activities,textural, and sensory properties of yoghurt fortified with different states and rates of pomegranate seeds (Punica granatum L.)

This study examines the effects of incorporating fresh, frozen, osmodehydrated, and dried pomegranate seeds, at different concentrations (5, 10, and 20%) on the physicochemical, antioxidant, textural, and sensory properties of yoghurt. Antioxidant activity, pH, acidity, syneresis, and color of yoghurt were also evaluated during the storage (28 days) at 4°C. The principal component analysis (PCA) was performed to assess the correlations between different yoghurt formulation and their sensory attributes. Data showed that the addition of pomegranate seeds reduced pH and modified the chromatics coordinate (L*, a*, b*, C*, h°) and firmness of the yoghurt samples. In addition, acidity, °Brix, and syneresis increased compared to the control. Thanks to their high anthocyanin content, pomegranate seeds considerably improved the antioxidant activity essentially for yoghurt enriched with frozen seeds. In addition, the supplementation of 20% of frozen seeds into yoghurt was the most appreciated by panelists and improved the sensory properties in comparison to other formulation. According to PCA, taste and appearance were the main criteria for the overall acceptability of yoghurt. After 28 days of storage, the reddish color was reinforced; however, the antioxidant activity of yoghurts was reduced. Overall, it can be concluded that pomegranate seeds can be used as a natural ingredient to develop a novel yoghurt with high nutritional properties.     

Effects of almond gum as texture and sensory quality improver in wheat bread

The aim of this work was to investigate the effect of almond gum as dietary fibre source in enhancing the wheat bread quality. Different amounts of almond gum (2%, 5% and 10% (w/w)) were used in bread formulation. The volume, texture, crust and crumb colour, as well as the sensorial properties, were evaluated and compared to control (without almond gum). The obtained results showed that almond gum addition enhanced significantly the volume of bread. The highest volume was obtained using 2% almond gum concentration with 23.6% increase, compared to control. Using almond gum in bread formulation improved considerably its texture with a notable decrease in hardness by 61.7% and 42.5% when using 2% and 5% almond gum, respectively. The sensory analysis scores showed that the better overall acceptability was found for breads supplemented with 2% almond gum, as compared to control and breads supplemented with 5% or 10% almond gum.     

Purification,structural data and biological properties of polysaccharide from Prunus amygdalus gum

This work demonstrates the efficiency of almond gum polysaccharides (AGPs) as bioactive compounds. AGPs were first extracted using H₂O₂, in the presence of NaOH, at different times and temperatures. The optimal extraction conditions were 4% H₂O₂ and 2 N NaOH, for 7 h at 50 °C, leading to an extraction yield of 58.2% (w/w). After a purification step, the retained AGPs were characterised using high‐performance liquid chromatography showing a molecular weight of 99.3 kDa. The monosaccharide composition of AGPs were assessed using gas chromatography–mass spectrometry. AGPs were found to be a complex heteropolysaccharide with a repeating unit mainly composed of galactose, arabinose, xylose, mannose, rhamnose, and glucuronic acid with the respective ratios: 45:26:7:10:1:11. The acidic nature of the polysaccharide is due to the presence of glucuronic acid. Total antioxidant activity, free radical‐scavenging activity and reducing power assay of AGPs were investigated. The obtained results showed high antioxidant activities of AGPs. Furthermore, beyond 60 mg mL^?1, AGPs exhibited bacterial growth inhibition for five pathogenic strains: Escherichia coli, Staphylococcus aureus, Enterococcus feacalis, Pseudomonas aeruginosa and Salmonella typhimurium.     

Recovery of Hydroxytyrosol Rich Extract from Two‐Phase Chemlali Olive Pomace by Chemical Treatment

Abstract: A very simple method is proposed to produce hydroxytyrosol, a commercially unavailable compound with well‐known biological properties which justify a potential commercial application. The 2‐phase Chemlali olive pomace is selected as substrate for chemical treatment. Different conditions of chemical treatment, including concentration of acid and alkaline solutions, time and temperature, were assayed. A high amount of hydroxytyrosol (1360 mg/kg of fresh 2‐phase olive pomace) was obtained using water bath after treatment at 80 °C for 90 min with 1 M of H₃PO₄. However, treatment of 2‐phase Chemlali olive pomace using autoclave apparatus could produce a large amount of hydroxytyrosol (1993.60 and 1515.88 mg/kg of fresh alperujo, 1 M acid and basic catalyst, respectively). By taking into consideration practical and economic aspects, acid‐catalyzed treatment was more effective using autoclave conditions, whereas the alkali catalyzed conditions were not very suitable. This study could provide useful information for industry to produce the potentially bioactive compound. Practical Application: The 2‐phase Chemlali olive pomace is selected as substrate for chemical treatment. Treatment of “alperujo” using water bath or autoclave apparatus was carried out. A high amount of hydroxytyrosol was obtained using autoclave apparatus.     

On particle size effects: An internal length mean field approach using field dislocation mechanics

A mean field approach including an internal length scale is developed in order to capture the particle size effects on the overall mechanical behavior of particle-reinforced alloys. A generalized self-consistent scheme (with coated particles) is employed, with a new “phase” representing the “layers” where orderly dislocations between the matrix and the particles are present. The thickness of these “layers” is the internal length scale introduced in the model. It is determined dynamically by using a one-dimensional field dislocation mechanics model, where localized geometrically necessary dislocation densities accommodate the lattice incompatibility between matrix and inclusions. The beneficial influence of this scheme, as compared to classical mean field approaches, is shown from comparisons with experimental data on the particle size effects in Al/SiC composites.     

A nanometre-sized porous phase in iron-carbon-boron system

A porous phase is detected in a Fe-0.28 wt.%C-0.1 wt.%B alloy. The porous phase is mainly located at the grain boundary region and the pore size ranges from about 10 nm to 500 nm. The chemical composition of the porous phase is very close to Fe₃(B_0.7C_0.3) with an orthorhombic lattice. The result shows an opportunity to produce bulk steel matrix composites with a porous second phase.     

Three-dimensional modelling of manufacturing tolerancing using the ascendant approach

This paper proposes a three-dimensional approach towards manufacturing tolerancing that uses a strategy to strictly consider the definition of a datum system imposed by ISO standards. This approach, called three-dimensional manufacturing tolerancing (TMT), is based on the small displacement torsor, which describes the possible deviations between machined surfaces and nominal surfaces of the part model. Every requirement of the definition drawing is treated separately with its own calculation model. The iterative ascending analysis allows one to establish the influence of the most recent phase and determine the influential parameters from previous phases. The nominal part model is defined on the datum systems of the requirement, and deviations are expressed with respect to both the machining process and the chosen machine adjustment method. The result takes the form of a formula that yields the variation in characteristics specified in the requirement based on quantifiable parameters identified on the machine.