A historical review and analysis on MOORA and its fuzzy extensions for different applications

Multi-criteria decision-making (MCDM) methods have been widely used among researchers to provide a trade-off solution between best and worst, considering conflicting criteria and sets of preferences. An efficient and systematic literature review of these methods is needed to maintain their application in distinctive domains. To this end, this paper presents a comprehensive and systematic literature survey on "multi-objective optimization by ratio analysis" (MOORA) method and its fuzzy extensions developed and discussed in recent years. This review includes articles categorized based on the publication name, publishing year, journal name, type of applications, and type of fuzzy extensions. In addition, this review will enhance the understanding of practitioners and decision-makers on the MOORA method, its development, fuzzy hybridization, different application areas, and future work. The study revealed that the MOORA technique was predominantly used with the TOPSIS approach, followed by the AHP and COPRAS methods. Furthermore, 76.28 % use single and hybridization approaches among all MOORA studies, while 23.72 % use MOORA in a fuzzy environment.

Evaluation of Copper-Based Alloy (C93200) Composites Reinforced with Marble Dust Developed by Stir Casting under Vacuum Environment

Copper-based alloy (C93200) composites reinforced with a different weight percentage of marble dust particles (1.5, 3, 4.5, and 6 wt.%) were developed by stir casting method under vacuum environment. By using this type of reinforcement, it was possible to detect a suitable material for bearing applications. The manufactured material was characterized for its mechanical properties using a micro-hardness tester. A universal INSTRON-5967 machine was used to detect the yield and tensile strength. Further the hardness features were measured using a Walter Uhl model machine, whereby the wear characteristics were simulated under the pin-on-disc tribometer under different working conditions in ambient temperature (23 °C). Next, the preference selection index (PSI) technique that considers multi-criteria decision-making was proposed to validate which material was the best candidate. For the selection of material criteria, some specific material intrinsic properties—such as, density, void fraction, hardness resistance along with tensile, compressive, and flexural strength—were proposed and the surface characteristics linked to friction coefficients along wear properties. It was found that the novel composite material containing 4.5 wt.% of marble dust provided the best combination of properties and is a suitable candidate material for bearing applications.

Biocompatibility evaluation and corrosion resistance of tungsten added Co-30Cr-4Mo-1Ni alloy

Biomaterials are continuously being developed to overcome the drawbacks of existing materials and provide improved function in artificial organs. Currently Co-Cr based alloys are used in many medical applications such as hip and knee implants which still require modification to better perform. In this article, therefore, the influence of tungsten allying element on electrochemical corrosion resistance and biocompatibility behaviour of a recently developed Co-30Cr-4Mo-1Ni alloy composition were investigated. The tungsten modified alloys were prepared by using a high temperature vertical vacuum casting technique at five different weight percentages (0-4wt.% tungsten). The electrochemical corrosion behaviour of all the samples under NaCl solution was studied by using potentiodynamic scan method. The corrosion characteristics were investigated in terms of corrosion potential (Ecorr) and corrosion current density (Icorr). From the results of the analysis, it was observed that out of all samples, an alloy with 2wt.% of tungsten in composition (i.e. Co-30Cr-4Mo-1Ni-2W) exhibited better corrosion resistance. Furthermore, histopathological evaluations in subcutaneous tissue were performed in rats according to the standard ISO 10993 to examine the biocompatibility of the prepared samples. The results showed no evidence of inflammatory cell migration, no epidermal necrosis, no vacuolar degeneration of basal cell, no adnexal atrophy and vesicle formation of any samples. The obtained findings indicate that Co-30Cr-4Mo-1Ni-2W can be used in biomedical applications including femoral component of hip and knee implants.