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In recent years, many alloys as well as composites of aluminium were developed for enhanced material performance. AA 6061 is an aluminium alloy that has extensive applications due to its superior material characteristics. It is a popular choice of matrix for aluminium matrix composite (AMC) fabrication. This study provides a review on AA 6061 aluminium alloy matrix composites produced through the stir-casting process. It focusses on conventional stir-casting fabrication, process parameters, various reinforcements used, and the mechanical properties of the AA 6061 composites. Several research studies indicated that the stir-casting method is widely used and suitable for fabricating AA 6061 composites with reinforcements such as SiC, B4C, Al2O3, TiC, as well as other inorganic, organic, hybrid, and nanomaterials. The majority of the studies showed that an increase in the reinforcement content enhanced the mechanical and tribological properties of the composites. Furthermore, hybrid composites showed better material properties than single reinforcement composites. The usage of industrial and agricultural residues in hybrid composites is also reported. Future studies could focus on the fabrication of AA 6061 nanocomposites through stir casting and their material characterisation, since they have great potential as advanced materials.

Sustainable development is now the focus of researchers and organizations worldwide. Several concepts, such as reverse logistics (RLs) and closed-loop supply chains, have been introduced to encourage sustainability in supply chains. RLs refers to the set of activities needed by consumers to collect the product used for reuse, repair, remanufacturing, recycling, or disposal of the used product. There are various processes involved in RL, and one of them is collection systems. Collection refers to a company obtaining custody of specific items. We review the literature on RLs collection systems. A bibliometric analysis was conducted to provide better insight into the field and establish any trends. Firstly, we present the classification methods used in the field, based on available review papers. Secondly, we evaluate literature from several fields that are related to either the problem setting or the technical features. Different perspectives are presented and classified. This method facilitates the identification of manuscripts related to the reader’s specific interests. Throughout the literature review, trends in measuring the performance of collection systems are identified, and directions for future research are identified and presented.

Electric discharge machining (EDM) is a material removal process that is especially useful for difficult-to-cut materials with complex shapes and is widely used in aerospace, automotive, surgical tools among other fields. EDM is one of the most efficient manufacturing processes and is used to achieve highly accurate production. It is a non-contact thermal energy process used to machine electrically conductive components irrespective of the material’s mechanical properties. Studies related to the EDM have shown that the process performance can be considerably improved by properly selecting the process material and operating parameters. This paper reviews research studies on the application of EDM to different grades of stainless steel materials and describes experimental and theoretical studies of EDM that have attempted to improve the process performance, by considering material removal rate, surface quality and tool wear rate, amongst others. In addition, this paper examines evaluation models and techniques used to determine the EDM process conditions. This review also presents a discussion on developments in EDM and outlines the likely trend for future research.

Society seeks greater development by building infrastructures in the cities. In order to achieve that, on many occasions, there has been inadequate use of natural resources, leading to adverse consequences such as the increase of greenhouse gases (GHGs), which are known to be one of the main polluting agents that accelerate climate change.Environmental care is important to business management; therefore, through its protection and continuous improvement, it seeks to contribute to the optimization of the economic performance of the country.The feasibility of an "Environmental Management Plan" was studied. It aims at making the El Jardín headquarters at UNAB environmentally sustainable by proposing three projects: solar panels, rainwater harvesting, and a green roof system. The economic, social and environmental result of the plan was evaluated; and it was posed to develop a transversal program of environmental culture for the "UNAB" community.The analysis showed that 40m 3 harvested rainwater can save up to 11% of consumption. The assembly and implementation of 282 solar panels can decrease 9.39% of total consumption. Similarly, 208 m 2 of green roof can lower the energy consumption by 702.67 kWh. The projects were agreed to be environmentally and socially viable, but they were not found financially and economically favorable.To sum up, a program of environmental culture is posed aiming at strengthening the knowledge and environmental awareness of the university community. The implementation of the proposed Environmental Management Plan would contribute to the environmental sustainability of the UNAB.

Electrical discharge machining (EDM) is an advanced machining method which removes metal by a series of recurring electrical discharges between an electrode and a conductive workpiece, submerged in a dielectric fluid. Even though EDM techniques are widely used to cut hard materials, low efficiency and high tool wear remain remarkable challenges in this process. Various studies, such as mixing different powders to dielectric fluids, are progressing to improve their efficiency. This paper reviews advances in the powder-mixed EDM process. Furthermore, studies about various powders used for the process and its comparison are carried out. This review looks at the objectives of achieving a more efficient metal removal rate, reduction in tool wear, and improved surface quality of the powder-mixed EDM process. Moreover, this paper helps researchers select suitable powders which are exhibiting better results and identifying different aspects of powder-mixed dielectric fluid of EDM.

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