Wake and wind farm aerodynamics of vertical axis wind turbines

The development of offshore wind energy, especially the steps towards deep water and/or higher density wind farms, revives the prospects of vertical axis wind turbines (VAWTs). Because VAWTs may reduce the cost of floating structures, there is a potential to lower energy costs. However, VAWTs are often assumed to be less efficient and less...

Wake scaling of actuator discs in different aspect ratios

The wake recovery from planar porous actuators that surrogate the effect of wind turbines is investigated, focusing on rectangular shapes for vertical axis wind turbines (VAWTs). We proposed an effective mixing diameter D∗ to scale the streamwise momentum recovery for actuators of arbitrary shape. The length-scale D∗ is given by the ratio...

A ship collision avoidance system for human-machine cooperation during collision avoidance

Maritime Autonomous Surface Ships (MASS) attract increasing attention in recent years. Researchers aim at developing fully autonomous systems that replace the role of human operators. Studies either focus on supporting conflict/collision detection (for manned ships) or solving conflict automatically (for unmanned ships). The cooperation...

Actuation System Design for a 3 DoF Contactless Wafer Stage

Silicon wafers are getting bigger and bigger in the production line, aiming for faster manufacturing, lower cost and higher yield. The handling/transportation technique is becoming more and more critical during the production. As the wafer is being handled with physical contact there is always risk of damage and contemination coming from the...