1,720,982 research outputs found
A System of Systems Approach to Supply Chain Design
No full textThis paper proposes a novel System of Systems (SoSs) framework in order to design and optimise Supply Chains (SCs). In this paper the characteristics of System of Systems and Supply Chains have been discussed and a similarity match has been made between the two. It is interesting to note that although some of these SoSs characteristics are intrinsic in nature of the SCs others such as evolutionary behaviour and self-organization need to be modelled. In this paper, an adaptive supply chain multi-level multi-objective optimisation framework has been proposed in order to have both evolutionary and self-organized behaviour. This framework is capable of performing both local and global optimisation and adaptation to different scenarios
Strategic Planning and Design of Supply Chains: A Literature Review
Full text linkIn this paper, a literature review of the mathematical models for supply chain design is proposed. The research is based on the study and analysis of publications of the last twelve years from the most widespread international journal about operations management and logistics. The aim of the work lies in identifying tendencies in the literature and related open issues about the strategic decisions, economic parameters, constraints and model features considered in the strategic planning and design of supply chains. After a description of the review methodology, comparison parameters and paper exhaustiveness, some guidelines are given in order to support future works in this field
Regression modeling to predict the geometrical features of Ti6Al4V thin sheets butt joints welded by disk laser
No full textThe aim of this work is to investigate the effects of power, welding speed, defocusing on geometric features and on
defects of 1 mm Ti6Al4V laser welded butt joints by a new generation disk laser with 2 kW of maximum power. The
active gain is a Yb:YAG disk instead of traditional Nd:YAG rods. Disk geometry allows to keep the nominal beam
quality also at high power because there is no thermal lensing effect, typical of rod geometry. A three level Box-Behnken
experimental design with three repetitions is carried out for a total of 45 tests. Linear and quadratic regression equations
are developed to relate the input factors to the output variables in order to predict the geometric features of butt joints
Effect of Defocusing on Bead-on-Plate of Ti6Al4V by Yb:YAG Disk Laser
No full textIn this study bead-on-plate tests on 3 mm-thick Ti6Al4V sheets were performed using a Yb:YAG thin disk laser in continuous mode to evaluate the effects of focus position on the bead characteristics. Among the various solid-state lasers, the disk laser has better beam quality than conventional rod geometries thanks to the absence of thermal lensing effect. An experimental plan was conducted using nine focus positions with constant power and welding speed. The beads were characterised in terms of geometry, defects, hardness and microstructure. This work is a preliminary study to select the best values of the focal position for subsequent butt welding tests. Analysing the results obtained, the best value of defocusing was -4 mm because, among full penetrated beads, it showed lower undercut and excessive penetration, lower melted area and smaller grain size in the melted area
A Multi-Objective Optimization for Supply Chain Network Using the Bees Algorithm
Full text linkA supply chain is a complex network which involves the products, services and information flows between suppliers and customers. A typical supply chain is composed of different levels, hence, there is a need to optimize the supply chain by finding the optimum configuration of the network in order to get a good compromise between the multi-objectives such as cost minimization and lead-time minimization. There are several multi-objective optimization methods which have been applied to find the optimum solutions set based on the Pareto front line. In this study, a swarm-based optimization method, namely, the bees algorithm is proposed in dealing with the multi-objective supply chain model to find the optimum configuration of a given supply chain problem which minimizes the total cost and the total lead-time. The supply chain problem utilized in this study is taken from literature and several experiments have been conducted in order to show the performance of the proposed model; in addition, the results have been compared to those achieved by the ant colony optimization method. The results show that the proposed bees algorithm is able to achieve better Pareto solutions for the supply chain problem
DISK LASER WELDING OF Ti6Al4V ALLOY
No full textIn this study butt welding tests on 3 mm-thick Ti6Al4V sheets were performed using a 2-kW Yb:YAG disk laser. Titanium alloys are widely used in the aircraft industry, due to their high strength-to-weight ratio, corrosion resistance, operating temperature and bonding with composite materials (electrochemical compatibility, similar coefficients of thermal expansion). A full factorial experimental plan was conducted using three values of power and three welding speeds to obtaingood-quality butt joints. The joints were characterised in terms of the weld geometry, geometrical defects and porosity by X-ray examinations and the resistance by tensile tests. Vickers microhardness tests were performed from the base metal to the melted zone. The weld with the best geometric characteristics, least geometric defects and porosity content was selected for the tensile tests. Tensile tests have given satisfactory results because the selected specimen broke in the original gauge length, but away from the welds
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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