Abstract-Shipbuilding industry is one of the hardest metal industries with several chemical and hazardous material exposures. Most of the traditional production processes such as welding, painting, blasting and fiberglass production have direct impacts on workers' health and safety as well as adverse effects on environment. A huge volume of wastes and pollutants is being released during shipbuilding and repairing processes which poses major risk on human health and environmental quality. Thus, this article highlights the current issues and challenges of green shipbuilding and recycling and also encompasses some initiatives and measures. This article is based on a comprehensive literature review related to the issues of green shipbuilding and recycling. The review discussed various aspects of green shipbuilding technology in order to green the industry through ensuring environment protection by reducing environmental pollution in ship manufacturing, service and breaking up. It is found that green shipbuilding and ship recycling contribute to minimize threats on human health, environmental and resource risks by reducing the pollution to air, water and soil; save resources; and improve economic and social benefits. Hence, several initiatives of green shipbuilding and recycling by the International Maritime Organization (IMO) and other shipping industry players have also been discussed.

Bats exhibit a high degree of agility and provide an excellent model system for bioinspired flight. The current study investigates an ascending right turn of a Hipposideros pratti bat and elucidates on the kinematic features and aerodynamic mechanisms used to effectuate the manoeuvre. The wing kinematics captured by a three-dimensional motion capture system is used as the boundary condition for the aerodynamic simulations featuring immersed boundary method. Results indicate that the bat uses roll and yaw rotations of the body to different extents synergistically to generate the centripetal force to initiate and sustain the turn. The turning moments are generated by drawing the wing inside the turn closer to the body, by introducing phase lags in force generation between the wings and redirecting force production to the outer part of the wing outside of the turn. Deceleration in flight speed, an increase in flapping frequency, shortening of the upstroke and thrust generation at the end of the upstroke were observed during the ascending manoeuvre. The bat consumes about 0.67 W power to execute the turning-ascending manoeuvre, which is approximately two times the power consumed by similar bats during level flight. Upon comparison with a similar manoeuvre by a Hipposideros armiger bat (Windes et al . 2020 Bioinspir. Biomim . 16 , abb78d. ( doi:10.1088/1748-3190/abb78d )), some commonalities, as well as differences, were observed in the detailed wing kinematics and aerodynamics.

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The individual effects of aerodynamics and wing inertia on the motion dynamics for maneuvering flight of two species of roundleaf bats, H. armiger and H. pratti bats have been investigated. Comparative studies among a straight flight, two ascending right turns, and a U-turn reveal that inertial forces play an essential and sometimes crucial role in effecting the maneuvers. The maneuvering trajectory of the bat is mostly driven by the aerodynamic forces generated by the wings along the flight path, whereas inertial forces for the most part drive the intra-cycle fluctuations. Inertial forces were also found to contribute non-trivially to the ascending motion of the H. armiger. Similar to translation, while aerodynamic moments account for the general rotational trends in roll, pitch and yaw angles exhibited by the bat body, inertial moments influence intra-cycle fluctuations. In addition, inertial moments play a dominant and crucial role for effecting yaw rotation during maneuvers for the sweeping turns as well as the U-turn. The moment resulting from the Coriolis force is deemed essential in accurate yaw prediction for lateral maneuvers. Finally, as the maneuver gets more complex or extreme such as in a 180° U-turn, the importance of the Coriolis and centrifugal moments increase, with the largest effect of centrifugal moments evidenced in the U-turn.