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Rapid prototyping (RP) has been given focus during dynamic market conditions, as it largely helps to compress product development time. RP contains the potential to achieve environmentally friendlier operations. However, RP processes are not environmentally friendlier, as the possibilities of toxicological health and environmental risks while handling and disposing of raw material remain unresolved. This study aims to select environmentally friendlier processes without compromising required mechanical properties. Some of the RP processes considered in this study are selective laser sintering (SLS), stereo lithography apparatus (SLA), three-dimensional printing (3DP) and laser engineered net shaping (LENS).

A conceptual model comprising 25 criteria (both traditional and environmental) has been developed. An expert team was formed to evaluate the environmental performance of RP processes using the developed conceptual model. Analytic network process–technique for order preference by similarity to an ideal solution-based hybrid methodology has been adopted for this purpose. Further, to overcome ambiguity and subjectivity nature of judgment, fuzzy set concepts have been adopted. Finally, a decision support system has been developed using MATLAB software to mitigate the associated computational difficulty.

The detailed analysis of criterion weights revealed that the expert team has assigned higher importance to environmental criteria over traditional criteria. Based on environmental considerations, ranking has been generated as SLA-SLS-3DP-LENS.

Only point-to-point and discrete fusion-based RP process have been considered in this study to demonstrate the developed conceptual model. Also, expert knowledge has been taken to rate some of the environmental criteria. In the near future, by conducting environmental studies, these criteria can be substituted with real data to improve accuracy of RP process selection.

Reported studies in RP process selection in literature were conducted considering mainly the various traditional criteria. In this study, the environmental criteria have also been considered along with traditional criteria. This study takes the initiative toward sustainability studies in RP processes. Also, detailed inferences have been derived and the results have been compared with the existing studies and this is the novel contribution of this study.

The purpose of this paper is to design novel tunnel field effect transistor (TFET) using graphene nanoribbons (GNRs).

To design the proposed TFET, the bilayer GNRs (BLGNRs) have been used as the channel material. The BLGNR-TFET is designed in QuantumATK, depending on 2-D Poisson’s equation and non-equilibrium Green’s function (NEGF) formalism.

The performance of the proposed BLGNR-TFET is investigated in terms of current and voltage (I-V) characteristics and transconductance. Moreover, the proposed device performance is compared with the monolayer GNR-TFET (MLGNR-TFET). From the simulation results, it is investigated that the BLGNR-TFET shows high current and gain over the MLGNR-TFET.

This paper presents a new technique to design GNR-based TFET for future low power very large-scale integration (VLSI) devices.

There are many investigations in design methodologies, but there are also divergences and convergences as there are so many points of view. This study aims to evaluate to corroborate and deepen other researchers’ findings, dissipate divergences and provide directing to future work on the subject from a methodological and convergent perspective.

This study analyzes the previous reviews (about 15 reviews) and based on the consensus and the classifications provided by these authors, a significant sample of research is analyzed in the design for additive manufacturing (DFAM) theme (approximately 80 articles until June of 2017 and approximately 280–300 articles until February of 2019) through descriptive statistics, to corroborate and deepen the findings of other researchers.

Throughout this work, this paper found statistics indicating that the main areas studied are: multiple objective optimizations, execution of the design, general DFAM and DFAM for functional performance. Among the main conclusions: there is a lack of innovation in the products developed with the methodologies, there is a lack of exhaustivity in the methodologies, there are few efforts to include environmental aspects in the methodologies, many of the methods include economic and cost evaluation, but are not very explicit and broad (sustainability evaluation), it is necessary to consider a greater variety of functions, among other conclusions

The novelty in this study is the methodology. It is very objective, comprehensive and quantitative. The starting point is not the case studies nor the qualitative criteria, but the figures and quantities of methodologies. The main contribution of this review article is to guide future work on the subject from a methodological and convergent perspective and this article provides a broad database with articles containing information on many issues to make decisions: design methodology; optimization; processes, selection of parts and materials; cost and product management; mechanical, electrical and thermal properties; health and environmental impact, etc.

Sustainable manufacturing facilitates the development of products with lower environmental impact. Additive manufacturing (AM) processes are incorporated with sustainable characteristics such as minimum material consumption, energy efficiency and minimum transportation. The purpose of this paper is to report a study on sustainability evaluation of AM process using a grey-based approach.

Sustainable AM process is gaining importance. From this viewpoint, this paper presents the evaluation of sustainability of AM process. The evaluation model includes 3 enablers, 18 criteria and 54 attributes. Grey-based approach is used for sustainability evaluation. Expert inputs are used for computing the grey index. Expert inputs are obtained and they are aggregated at three levels to calculate the overall grey performance index, which indicates sustainability level of AM processes. Furthermore, weaker areas are identified through determination of grey performance importance index (GPII) values.

The calculated grey index is (3.510, 16.177), which implies that AM process is sustainable. Weaker attributes are determined on the basis of the computation of GPII values.

The study has been executed on the basis of the opinion from experts with practical experience. Hence, the inferences are found to be practically feasible. The identified weaker attributes from the study would enable the manufacturers and practitioners to focus more on weaker areas for enhancing the sustainability of AM processes. The study has made an evaluation from sustainability perspective of AM processes, which would enable practitioners to assess AM processes from TBL sustainability orientation.

The development of sustainability evaluation model and application of a grey-based approach for assessment of AM process are the original contributions of this study.

In this study, the tri-bological behaviour of the un-coated and diamond coated tungsten carbide was evaluated using the pin-on-disc test rig. The same was also tested on a lathe machine tool. This paper aims to compare the tri-bological behaviour of coated tungsten carbide pin with un-coated tungsten carbide pin it also correlates the wear obtained from the two machines used.

Experiments were performed using L8 orthogonal array and results obtained on a pin-on-disc test rig under dry sliding process were optimized through a modern optimization technique i.e. genetic algorithm (GA). The response surface methodology model (L8 orthogonal array) formed the basis for the development of the GA model, which defines the conditions of minimum wear, minimum coefficient of friction and minimum surface roughness for the sliding process of the pin-on-disc test rig.

Implementation of the heuristic approach for optimization of input parameters for the combination of tool material used for the turning process. The initial approach involves tri-bological testing considering the same combination. The set of experiments further performed, inferred that the results were similar and that the diamond coating enhances the life of the tool.

Successfully synthesized the diamond coating on tungsten carbide tool material. Implantation of the heuristic approach, i.e. GA to tri-bological tests to identify the optimized level of input variables. Experimentation involves the tri-bological testing whose results were confirmed through performing experiments on the lathe machine tool.

In the present scenario, the demand for additive manufacturing (AM) has increased. Taking into account environmental problems and sustainability, manufacturers are now also considering the environmental and sustainability criteria in their decision-making process. The sustainability concept is known as the triple-bottom line, namely, economic, social and environmental perspectives. Sustainable concept selection in the manufacturing organisation can be considered as the selection of sustainable material, product design, process, method and technology. This study aims to select an appropriate AM process by considering sustainability from various available techniques.

Appropriate sustainable performance indicators for the AM were identified based on literature as well as in discussion with experts and decision-makers. The model addresses all the major dimensions of sustainable concepts of AM such as material/product quality, machine performance, market stability, total cost and ecological values. A hybrid multi-criteria decision-making approach, i.e. stepwise weight assessment ratio analysis and complex proportional assessment methods, have been used to select the best AM technique. While selecting criteria affecting AM machines and processes, criteria based on the sustainable concept are considered.

Among the four selected AM processes, i.e. fused diffusion modelling (FDM), laminated object manufacturing (LOM), stereolithography apparatus (SLA) and selective laser sintering (SLS), the best alternative was found to be FDM.

The present study highlights some limitations in the selection of AM process and methodology used in this research. This study considers only four AM processes, i.e. FDM, LOM, SLA and SLS. Future work may include considering other AM processes and criteria that affect the sustainability of AM.

The present work will help researchers and production managers to decide the best AM alternatives to fabricate desired parts. Hence, AM can help in maximum energy utilisation, optimal consumption of resources, minimum material wastage and reduction of CO₂ emission.

The study considers some important criteria, including energy consumption, eco-friendly and wastage-free production, that help sustainable AM. This study can result in a good economic efficiency of AM industries and, therefore, positively impact customers using green products.

The rotorcraft technology is very interesting area since last few decades due to variety of applications. One of the rotorcrafts is the quadrotor unmanned aerial vehicle (QUAV), which contains four rotors mounted on an airframe with an onboard controller. The QUAV is a highly nonlinear system and underactuated. Its controller design is very challenging task, and the need of controller is to make it autonomous based on mission planning. The purpose of this study is to design a controller for quadrotor UAV for attitude stabilization and trajectory tracking problem in presence of external environmental disturbances such as wind gust.

To address this problem, the model predictive control has been designed for attitude control and feedback linearization control for the position control using the linear parameter varying (LPV) approach. The trajectory tracking problem has been addressed using the circular trajectory and helical trajectory.

The simulation results show the efficient performance with good trajectory tracking even in presence of external disturbances in both the scenarios considered, one for circular trajectory tracking and other for helical trajectory tracking.

The novelty of the work came from using the LPV approach in controller design, which increases the robustness of the controller in presence of external disturbances.

The purpose of this paper is to report the state of art review on sustainable additive manufacturing (AM).

AM processes are becoming environmentally conscious and sustainable. In total, 63 papers are being collected from peer-reviewed journal sources. The review is presented on triple bottom line sustainable aspects, namely, environment, economy and society.

In the environmental dimension, papers on energy consumption, design optimization and life cycle assessment aspects are being collected and presented. The key inferences and insights are being derived from the mentioned perspectives and a framework for sustainable AM is proposed.

The review is limited to journal articles from the study on sustainable AM. Book chapters are being excluded.

The study also discussed various perspectives of sustainable AM and provided insights on sustainable AM to practitioners.

Systematic review on sustainable additive manufacturing is the original contribution of the authors.

Additive manufacturing (AM) technologies have tremendous applications in industries owing to their unique advantages. Sustainable AM (SAM) is gaining significance because of lightweight structures, lattice geometries and customized parts for industrial applications. To facilitate design for SAM, design guidelines from AM and environment viewpoints are to be analyzed. In this context, this paper aims to present the analysis of SAM guidelines.

This work divides 26 identified SAM guidelines into four categories. Grey axiomatic design was used to calculate the weights of guidelines categories. Further, the grey technique for order preference by similarity to ideal solution was used as a solution methodology to prioritize the SAM guidelines.

The top identified guidelines are “Design for reusability” and “Optimize part orientation for build time and roughness.” Implementing proper design guidelines leads to many sustainable benefits such as minimum material consumption, energy consumption and emissions.

This study would facilitate Am product designers to deploy prioritized guidelines for enhancing the effectiveness of the additively manufactured product with sustainability benefits. The prioritized guidelines would guide the AM product designers to take maximum advantage of the AM process by deploying design for AM and design for environment guidelines. This study contributed a structured approach for design engineers and practitioners to deploy guidelines during the early stages of product design to ensure AM feasibility with minimal environmental impact.

The purpose of this study is to rank additive manufacturing (AM) processes for microfabrication using integrated fuzzy analytic hierarchy process (AHP)-technique for order of preference by similarity to ideal solution (TOPSIS).

AM technology selection is formulated as multi-criteria decision-making (MCDM) problem and ranking is obtained using fuzzy AHP-TOPSIS. Five candidate processes considered are laser-induced forward transfer (LIFT), microstereolithography, micro-selective laser sintering (micro-SLS), inkjet, micro 3D printing.

Criteria weights are obtained using fuzzy AHP, and ranking is obtained using fuzzy TOPSIS. The top ranked criteria include material compatibility, geometrical complexity and minimum feature size. The ranking sequence is LIFT > microstereolithography > micro-SLS > inkjet > micro-3D printing.

In the present study, ten criteria and five alternatives are used. In future, additional criteria and alternatives could be considered in line with technological advancements.

The generated ranking enabled the selection of appropriate AM process for microfabrication.

The application of hybrid MCDM approach for ranking AM processes for microfabrication is the contribution of the study.