Goran Gregov

Autonomous solutions for powering wireless sensor nodes in rivers

There is an evident need for monitoring pollutants and/or other conditions in river flows via wireless sensor networks. In a typical wireless sensor network topography, a series of sensor nodes is to be deployed in the environment, all wirelessly connected to each other and/or their gateways. Each sensor node is composed of active electronic devices that have to be constantly powered. In general, batteries can be used for this purpose, but problems may occur when they have to be replaced. In the case of large networks, when sensor nodes can be placed in hardly accessible locations, energy harvesting can thus be a viable powering solution. The possibility to use three different small-scale river flow energy harvesting principles is hence thoroughly studied in this work: a miniaturized underwater turbine, a so-called ‘piezoelectric eel’ and a hybrid turbine solution coupled with a rigid piezoelectric beam. The first two concepts are then validated experimentally in laboratory as well as in real river conditions. The concept of the miniaturised hydro-generator is finally embedded into the actual wireless sensor node system and its functionality is confirmed.

Comparison between 3D FEM and Standard ISO Tooth Root Stresses

The paper deals with the discussion how nominal spur tooth root stress of thin-rimmed gear determined in accordance with the standard ISO 6336-3:2006, method B, agrees with the results of the 3D FEM stress analysis. The procedure proposed by standard ISO for the tooth root stress calculation doesn’t identify the stress behaviour related to mutual affects of characteristic thin-rimmed gear geometrical parameters. Therefore, the 3D FEM analysis of tooth root stress has been performed for gear structures with middle and offset web with various rim and web thickness. The rim thickness has covered and slightly overcome the backup ratio defined by ISO procedure, while the web thickness has covered the range of practical interest.