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Sustainable Energy Harvesting Technologies Past Present and Future Part 4

Tham khảo tài liệu 'sustainable energy harvesting technologies past present and future part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Vibration Energy Harvesting Machinery Vibration Human Movement and Flow Induced Vibration 49 The electrical tuning method realizes resonant frequency tuning by adjusting electrical loads. This method consumes little energy as it does not involve any change in mechanical properties. In addition it is much easier to implement than mechanical methods. However this method normally has a small tuning range. The suitability of different tuning approaches depends on the application but in general terms the key factors for evaluating a tuning mechanism are energy consumed by the tuning mechanism should be as small as possible and must not exceed the energy produced by the energy harvester the mechanism should achieve a sufficient operational frequency range the tuning mechanism should achieve a suitable degree of frequency resolution the strategy applied should not increase the damping over the entire operational frequency range. Energy harvesting from human movement is another important area in vibration energy harvesting. As human movement is random linear energy harvesters are not suitable for this application. Broadband non-linear or non-resonant devices are preferred. At the moment the most common locations on human body for the energy harvesters are feet and upper body due to large displacement or force produced during movement. Up to date some reported energy harvesters successfully produced useful amount of electrical energy for portable electronic devices. However consideration needs to be taken to improve design of the energy harvesters so that they will not cause discomfort for human body. Furthermore another potential solution to energy harvesting from human movement is to print active materials on fabrics such as jackets and trousers so that electrical energy can be generated while human body is moving. Energy harvesters from flow-induced vibration as an alternative to turbine generators have drawn more and more attention. Useful amount of energy has been .