Ocean waves are a huge, largely untapped energy resource, and the potential for extracting energy from waves is considerable. Research in this area is driven by the need to meet renewable energy targets, but is relatively immature compared to other renewable energy technologies. This review introduces the general status of wave energy and evaluates the device types that represent current wave energy converter (WEC) technology, particularly focusing on work being undertaken within the United Kingdom. The possible power take-off systems are identified, followed by a consideration of some of the control strategies to enhance the efficiency of point absorber-type WECs. There is a lack of convergence on the best method of extracting energy from the waves and, although previous innovation has generally focused on the concept and design of the primary interface, questions arise concerning how best to optimize the powertrain. This article concludes with some suggestions of future developments.

Rotary-wing unmanned aerial vehicles (UAVs) have the ability to operate in confined spaces and to hover over point of interest, but they have limited flight time and endurance. Conventional contact-based charging system for UAVs has been used, but it requires high landing accuracy for proper docking. Instead of the conventional system, autonomous wireless battery charging system for UAVs in outdoor conditions is proposed in this paper. UAVs can be wirelessly charged using the proposed charging system, regardless of yaw angle between UAVs and wireless charging pad, which can further reduce their control complexity for autonomous landing. The increased overall mission time eventually relaxes the limitations on payload and flight time. In this paper, a cost effective automatic recharging solution for UAVs in outdoor environments is proposed using wireless power transfer (WPT). This research proposes a global positioning system (GPS) and vision-based closed-loop target detection and a tracking system for precise landing of quadcopters in outdoor environments. The system uses the onboard camera to detect the shape, color and position of the defined target in image frame. Based on the offset of the target from the center of the image frame, control commands are generated to track and maintain the center position. Commercially available AR.Drone. was used to demonstrate the proposed concept which is equppied with bottom camera and GPS. Experiments and analyses showed good performance, and about 75% average WPT efficiency was achieved in this research.

Woodpecker can be modelled as a low-inertia hammer. It uses the angular momentum of its body, generated by contraction of its leg muscles, to accelerate its head towards the tree, which it is pecking. It appears to peck at a resonant frequency.

Wind blades are the most expensive parts of wind turbines made from fibre-reinforced polymer composites. The blades play a critical role on the energy production, but they are prone to damage like any other composite components. Leading edge (LE) erosion of the wind turbine blades is one of the common damages, causing a reduction in the annual energy production especially in offshore wind turbine farms. This erosion can be caused by rain, sand and flying solid particles. Coating the blade against erosion using appropriate materials can drastically reduce these losses and hence is of great interest. The sol–gel technique is a convenient method to manufacture thin film coatings, which can protect the blades against the rain erosion, while having negligible effect on the weight of the blades. This article provides an extensive review of the liquid erosion mechanism, water erosion testing procedures and the contributing factors to the erosion of the LE of wind turbine blades. Techniques for improving the erosion resistance of the LE using carbon nanotubes and graphene nano-additives are also discussed.

An object-oriented approach to dynamic simulation and analysis of multidomain, multiphysics systems is developed. Lagrangian dynamics and a novel numerical di erentiation technique are used by the simulation engine to develop automatically the equations of motion from energy expressions, which can incorporate multidomain, multiphysics components. The same modelling methodology is used for both forward and inverse dynamic analysis. Di erent methods are presented for the solution of inverse dynamic problems, depending on how the desired motion and the control inputs are de ned. A graphical approach is developed to test for the structural invertibility of a system for a particular choice of control inputs. A multistage inversion technique is introduced for systems where structural non-invertibility is due to a mismatch of the equation orders. The techniques developed for system inversion are demonstrated by simulated examples.