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Sustainable Energy Harvesting Technologies Past Present and Future Part 6

Tham khảo tài liệu 'sustainable energy harvesting technologies past present and future part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Modelling Theory and Applications of the Electromagnetic Vibrational Generator 89 -y . It can be seen from this graph that in practice the generated The power graphs for different acceleration levels of generator C D are plotted in Figure 32 to establish the relation between the generated electrical power and the applied acceleration. According to linear theory the generated electrical power should have a square law relation with the acceleration and an inverse square relation with total damping faaor P- D- w d electrical power did not vary squarely with the variation of the acceleration. This is again due to the variation of parasitic damping factor i.e as a is increased Dp also increases and thus in practice the power has closer to a linear variation with acceleration. The next section will provide the available vibrational sources which are present in the environment since ultimate goal for energy harvester is to generate useful electrical energy from the environment. Fig. 32. Power vs acceleration 2.1 Vibrational sources It is necessary to understand the acceleration and frequency level of different vibration sources. Since the ultimate goals of the energy harvesting device is to generate electricity from ambient sources. An overview of a variety of commonly available vibrations has already been published in several literatures 2 9 . Most of them are classified as low level vibrations which are characterised by higher frequencies and smaller amplitudes such as industrial automotive and structural applications and some of them are characterised by low frequency and high amplitude such as human motions. 2.1.1 Human motion Human motion occurs during physical activities such as walking jogging and running. The electromagnetic vibrational generator could be mounted or attached at different 90 Sustainable Energy Harvesting Technologies - Past Present and Future locations on the human body wired into clothes foot-wear a belt bag rucksack etc to power electronic .