Machining operations of aluminum structural parts are typically carried out under high feeds and high cutting speeds. Under these conditions, high thermomechanical loads are exerted on the workpiece, which may result in changes in the subsurface material. Residual stresses can be one of the machining induced changes and can lead to considerable rejection rates caused by part distortion. Due to their significant economic importance, it is essential to understand the influence of the machining process on the residual stresses in aluminum. This paper presents the influence of the machining parameters as well as the cutting edge geometry on residual stress of workpieces made out of a forged aluminum alloy.

Abstract:The objective of this study was to assess the effectiveness and safety of levosulpiride in patients with dysmotility-like functional dyspepsia including nonerosive reflux esophagitis in conditions of daily practice. The study was conducted as a prospective, open-label, multicenter design in 342 patients with dysmotility-like functional dyspepsia (n=279) and nonerosive reflux disease (n=63), who received levosulpiride 25 mg 3 times daily orally for 4 weeks. Individual symptoms (pain/discomfort, fullness, bloating, early satiety, pyrosis, regurgitation, and nausea/vomiting) and a global symptom score were assessed at 15, 30, and 60 days after starting treatment. Adverse events also were recorded. There were 151 men and 191 women (mean age 38.8 years) who referred dyspeptic symptoms for a mean of 10.2 (10.7) months. A total of 66.4% patients were treated with 75 mg/day levosulpiride and 33.6% with 50 mg/day. At the 15-day visit, a decrease greater than 50% in the global symptom score was observed. The frequency and intensity of individual symptoms showed a statistically significant decrease (p<0.001) at all visits compared with baseline. At the 30-day visit, all symptoms had almost disappeared, a trend that was maintained until the last visit. Treatment with levosulpiride was well tolerated and only 40 adverse events were recorded (galactorrhea 26.7%, somnolence 17.8%, fatigue 11.1%, headache 11.5%) and no patient had to abandon the study due to side effects. In conclusion, levosulpiride is an effective and safe drug in the treatment of dysmotility-like functional dyspepsia and non-erosive reflux disease.

The residual stresses induced during shaping and machining play an important role in determining the integrity and durability of metal components. An important issue of producing safety critical components is to find the machining parameters that create compressive surface stresses or minimise tensile surface stresses. In this paper, a systematic data-driven fuzzy modelling methodology is proposed, which allows constructing transparent fuzzy models considering both accuracy and interpretability attributes of fuzzy systems. The new method employs a hierarchical optimisation structure to improve the modelling efficiency, where two learning mechanisms cooperate together: NSGA-II is used to improve the model's structure while the gradient descent method is used to optimise the numerical parameters. This hybrid approach is then successfully applied to the problem that concerns the prediction of machining induced residual stresses in aerospace aluminium alloys. Based on the developed reliable prediction models, NSGA-II is further applied to the multiobjective optimal design of aluminium alloys in a 'reverse-engineering' fashion. It is revealed that the optimal machining regimes to minimise the residual stress and the machining cost simultaneously can be successfully located.

In this study, a hydrogen generation photocatalyst based on bismuth titanate (Bi2Ti2O7 - BTO) modified with manganese (Mn) has been developed. Mn of varying weight percent was added to construct a modified BTO catalyst (Mn_BTO), in order to enhance the opto-electronic and photocatalytic hydrogen generation capabilities of the pristine BTO. The structural, morphological, and optical properties of the photocatalysts were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-visible spectrophotometry. The XRD, SEM, and TEM analyses indicate the formation of the pyrochlore BTO phase with particles of dimensions 30 ± 10 nm. The UV-visible study revealed a reduction in the bandgap of Mn_BTO and enhanced absorption in the visible range, compared to the pristine BTO. The catalyst was optimized for maximum hydrogen generation from a water-methanol (sacrificial electron donor) system in a slurry reactor. The photocatalytic hydrogen evolution studies indicate that the Mn_BTO with up to 1 wt% Mn facilitates an optimal 140% increase in the hydrogen yield. The role of formic acid and formaldehyde as additives in photocatalytic hydrogen evolution has also been examined. The effect of Mn content, mechanistic overview, and reusability of the catalyst are discussed.

Machining operations of aluminum structural parts are typically carried out under high feeds and high cutting speeds. These cutting conditions exert thermal and mechanical loads on the workpiece, which cause changes in the subsurface material. Residual stresses belong to the machining induced changes and can lead to considerable rejection rates as a consequence of part distortion. Due to the significant economic importance, it is essential to investigate the influence of the machining process on the residual stresses in aluminum. This paper presents the influence of cutting parameters and tool geometry on the level of residual stress in workpieces out of forged aluminum alloys.