Structural integrity monitoring of onshore wind turbine concrete foundations

Signs of damage around the bottom flange of the embedded ring were identified in a large number of existing onshore concrete foundations. As a result, the embedded ring experienced excessive vertical displacement. A wireless structural integrity monitoring (SIM) technique was developed and installed in the field to monitor the stability of these turbines by measuring the displacement patterns and subsequently alerting any significant movements of the embedded ring. This was achieved by using wireless displacement sensors located in the bottom of the turbine. A wind turbine was used as a test bed to evaluate the performance of the SIM system under field operating conditions. The results obtained from the sensors and supervisory control and data acquisition (SCADA) showed that the embedded ring exhibited significant vertical movement especially during periods of turbulent wind speed and during shut down and start up events. The measured displacement was variable around the circumference of the foundation as a result of the wind direction and the rotor uplift forces. The excessive vertical movement was observed in the side where the rotor is rotating upwards. The field test demonstrated that the SIM technique offers great potential for improving the reliability and safety of wind turbine foundations

Current characterisation for ultra low power wireless body area networks

The emerging area of body area networks (BAN) imposes challenging requirements on hardware and software to achieve the desired lifetimes for certain devices such as long term medical implants. In this paper, we propose a novel approach to the measurement and characterisation of the energy consumption of BAN devices. The approach uses a low cost energy auditing circuit and addresses the problem of accurately measuring low-level current consumption. This new technique will allow precise and analytical measurements of systems and components in terms of energy. This will help circuit designers minimise power consumption in BAN devices. Software engineers might use this approach to validate and optimise embedded code. Network engineers can optimise network parameters to reduce the power consumption of a single node. Adoption of the proposed technique will aid the development of ultra-low power wireless BANs. Results are presented on current characterisation for two wireless motes