INTEGRATED APPROACH TO THE SUPERPLASTIC FORMING OF MAGNESIUM ALLOYS

The economical and environmental issues associated with fossil fuels have been urging the automotive industry to cut the fuel consumption and exhaust emission levels, mainly by reducing the weight of vehicles. However, customers increasing demands for safer, more powerful and luxurious vehicles have been adding more weight to the various categories of vehicles, even the smallest ones. Leading car manufacturers have shown that significant weight reduction, yet satisfying the growing demands of customers, would not be feasible without the extensive use of lightweight materials. Magnesium is the lightest constructional metal on earth, offering a great potential for weight-savings. However, magnesium and its alloys exhibit inferior ductility at low temperatures, limiting their practical sheet metal applications. Interestingly, some magnesium alloys exhibit superplastic behaviour at elevated temperatures; mirrored by the extraordinarily large ductility, surpassing that of conventional steels and aluminium alloys. Superplastic forming technique is the process used to form materials of such nature, having the ability to deliver highly-profiled, yet very uniform sheet-metal products, in one single stage. Despite the several attractions, the technique is not widely-used because of a number of issues and obstacles. This study aims at advancing the superplastic forming technique, and offering it as an efficient process for broader utilisation of magnesium alloys for sheet metal applications. The focus is primarily directed to the AZ31 magnesium alloy, since it is commercially available in sheet form, possesses good mechanical properties and high strength/weight ratio. A general multi-axial anisotropic microstructure-based constitutive model that describes the deformation behaviour during superplastic forming is first developed. To calibrate the model for the AZ31 magnesium alloy, systematic uniaxial and biaxial stretching tests are carried out over wide-ranging conditions, using 3 specially-designed fixtures. In a collaborative effort thereafter, the calibrated constitutive model is fed into a FE code in conjunction with a stability criterion, in order to accurately simulate, control and ultimately optimise the superplastic forming process. Special pneumatic bulge forming setup is used to validate some proposed optimisation schemes, by forming sheets into dies of various geometries. Finally, the materials post-superplastic-forming properties are investigated systematically, based on geometrical, mechanical and microstructural measures

MS-TCN: Multi-Stage Temporal Convolutional Network for Action Segmentation

Temporally locating and classifying action segments in long untrimmed videos is of particular interest to many applications like surveillance and robotics. While traditional approaches follow a two-step pipeline, by generating frame-wise probabilities and then feeding them to high-level temporal models, recent approaches use temporal convolutions to directly classify the video frames. In this paper, we introduce a multi-stage architecture for the temporal action segmentation task. Each stage features a set of dilated temporal convolutions to generate an initial prediction that is refined by the next one. This architecture is trained using a combination of a classification loss and a proposed smoothing loss that penalizes over-segmentation errors. Extensive evaluation shows the effectiveness of the proposed model in capturing long-range dependencies and recognizing action segments. Our model achieves state-of-the-art results on three challenging datasets: 50Salads, Georgia Tech Egocentric Activities (GTEA), and the Breakfast dataset.Comment: CVPR 2019 Camera Read

Do different marketing practices pre-suppose different frames of reference? An exploratory study

Purpose: The role of managerial assumptions in the formulation of organizational strategies has been well recognized by previous studies, yet in marketing literature, the effect of such imperative on marketing practice choice tends to be ignored. Therefore, this paper aims to empirically investigate how management assumptions fit with the choice of marketing practices, and how such fit affects performance. Design/methodology/approach: A model is developed and tested using survey methodology, and the data are analyzed using the partial least square (PLS) approach. Findings: The results show that different marketing practices were coupled with different frames of reference, resulting in viable matching profiles. Research limitations/implications: Given the novelty of the approach adopted in this study, conclusions about association and not causation are drawn. In addition, the study is restricted to Qatar which may reduce the generalizability of its findings and conclusions. Practical implications: The findings will help managers to examine carefully the internal logic of their marketing-related profiling, where coherent variables will enhance performance. Originality/value: To one’s knowledge, this paper reports a work in an area not previously researched. In addition, this study is one of the rare papers that examines unobserved heterogeneity using the PLS-structural equation modeling (SEM) in the field of marketing. © 2018, Allam Abu Farha and Said Elbanna.Scopu