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This paper reviews the advancements in wall-climbing robots, focusing on optimizing adsorption and introducing novel suction techniques. Wall-climbing robots have garnered significant attention due to their potential in hazardous operations and their ability to navigate various wall surfaces without compromising mobility. One such innovation includes a robot designed for smooth wall surfaces, integrating a vacuum adsorption system and adhesion belts. This design enhances the robot’s flexibility and steerability, with an in-depth analysis of its attachment mechanism for climbing tasks. Key parameters such as the required adsorption force and motor torque for stable climbing have been derived, with the robot’s prototype demonstrating high stability and adaptability across different wall surfaces. Another pivotal study delves into the modelling and experimental analysis of suction pressure in the suction chamber, emphasizing the role of different chamber contours. A novel addition of a bottom restrictor at the chamber’s base has been introduced, with its design and performance analysed using 3D modelling and computational fluid dynamics. The restrictor’s impact on the robot’s adhesion efficiency has been experimentally assessed, showcasing promising results on non-plastered brick walls. Through these studies, the paper underscores the continuous evolution and potential of wall-climbing robots in diverse applications.

Machining hard materials with 45–48 HRC is difficult in turning operation because of the improvident cutting parameter selections for the operation. The OHNS (AISI/SAE-01–48HRC) steel is mainly preferred for the production of shafts, gears, cams, and press tools. The OHNS material was turned at a dry state using VP-coated carbide inserts. The seventeen experimental trials were designed by central composite design (CCD) with different levels of cutting parameters, like feed rate, cutting speed, and depth of cut. Design Expert-11 software desirability approach and TOPSIS (Technique for Order Preference by Simulating the Ideal Solution) were used to analyse the experimental results to obtain a single optimal solution that defines better results on metal removal rate (MRR) and surface finish (Ra). RSM solution with 81.3% desirability, the cutting speed of 60 m/min, feed rate of 0.08 mm/rev, and depth of cut 1 mm as the optimal cutting parameters; similarly, TOPSIS algorithm calculation identifies the cutting parameter combinations, such as 40 m/min cutting speed, 0.09 mm/rev feed rate, and 1 mm depth cut to enrich the quality of the machined steel; however, the desirability approach cutting parameter setting is better for the surface finish achievement, while TOPSIS solution is better to obtain significant MRR. The confirmation test results validated for the predicted values of both approaches; as such, the experimental results were maintained better convenience than the predicted one. For the optimum cutting parameter combinations, an MRR of 22.032 gm/min and surface roughness of 0.781 μm were obtained at 60 m/min cutting speed, 0.08 mm/rev feed rate, and 1 mm depth of cut. [ABSTRACT FROM AUTHOR]

This article demonstrates recent innovative cascade annulation methods for preparing functionalized carbazoles and their related polyaromatic heterocyclic compounds enabled by Lewis acid catalysts. Highly substituted carbazole scaffolds were synthesized via Lewis acid mediated Friedel-Crafts arylation, electrocyclization, intramolecular cyclization, cycloaddition, C-N bond-formations, aromatization and cascade domino reactions, metal-catalyzed, iodine catalyzed reactions and multi-component reactions. This review article mainly focuses on Lewis acid-mediated recent synthetic methods to access a variety of electron-rich and electron-poor functional groups substituted carbazole frameworks in one-pot reactions. Polyaromatic carbazole and their related nitrogen-based heterocyclic compounds were found in several synthetic applications in pharma industries, energy devices, and materials sciences. Moreover, the review paper briefly summarised new synthetic strategies of carbazole preparation approaches will assist academic and pharma industries in identifying innovative protocols for producing poly-functionalized carbazoles and related highly complex heterocyclic compounds and discovering active pharmaceutical drugs or carbazole-based alkaloids and natural products., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)