Numerical and experimental performance study of two-degrees-of-freedom electromagnetic energy harvesters

Energy harvesting is a rising technology able to replace conventional batteries in supplying low-power devices. Researchers are studying the use of energy harvesters in Autonomous Internet of Things (AIoT) systems to create a wireless network of nodes for real-time monitoring of assets. Electromagnetic energy harvesters exploiting ambient vibrations for electric power generation are used in monitoring applications for sensorized industrial vehicles or mechanical systems. This paper shows a design methodology for two-degrees-of-freedom gravitational electromagnetic energy harvesters (2DOF GEMEHs) along with prototype testings. The main purpose of this non-linear two-degrees-of-freedom system is to improve conversion efficiency and bandwidth broadening through the introduction of a second resonance frequency. The proposed harvester devices could be suited for vehicle monitoring and in particular railway monitoring applications. The novelty of the configuration is the use of two magnetic springs and the series connection of two induction coils. The system design achieves long-lasting performances since there are no mechanical parts involved in the dynamics, thus being compatible with low maintenance requirements. 2DOF GEMEHs can have the two resonance frequencies tuned to two fundamental frequencies of the vehicle harvested vibrations for power enhancement. Infreight trains applications the system resonance frequencies may be tuned to the two natural frequencies of the bogie when the railcar is in tare and loaded conditions. The working principle, configuration and analytical model of these devices are described in a detailed way. The numerical modeling approach consists of a combination of FEM analyses in Ansys Maxwell and dynamic simulations in Simulink for evaluation of stiffness and damping characteristics of the system. Experimental laboratory tests on harvester prototypes are compared to numerical results of dynamic simulations for the validation of the proposed model through error estimation. Performance improvements of the 2DOF GEMEH are evaluated through the definition of a merit factor based on output power and bandwidth. The use of a 2DOFsystem is justified by comparing its efficiency respect to the 1DOF configuration, leading to an overall harvesting performance improvement of 10%

Proposal of an Alpine Skiing Kinematic Analysis with the Aid of Miniaturized Monitoring Sensors, a Pilot Study

The recent growth and spread of smart sensor technologies make these connected devices suitable for diagnostic and monitoring in different fields. In particular, these sensors are useful in diagnostics for control of diseases or during rehabilitation. They are also extensively used in the monitoring field, both by non-expert and expert users, to monitor health status and progress during a sports activity. For athletes, these devices could be used to control and enhance their performance. This development has led to the realization of miniaturized sensors that are wearable during different sporting activities without interfering with the movements of the athlete. The use of these sensors, during training or racing, opens new frontiers for the understanding of motions and causes of injuries. This pilot study introduced a motion analysis system to monitor Alpine ski activities during training sessions. Through five inertial measurement units (IMUs), placed on five points of the athletes, it is possible to compute the angle of each joint and evaluate the ski run. Comparing the IMU data, firstly, with a video and then proposing them to an expert coach, it is possible to observe from the data the same mistakes visible in the camera. The aim of this work is to find a tool to support ski coaches during training sessions. Since the evaluation of athletes is now mainly developed with the support of video, we evaluate the use of IMUs to support the evaluation of the coach with more precise data

Tape winding angle influence on subsea cable sheathing fatigue performance

A fundamental component of subsea power cables is the thin galvanized steel tape winded around the dielectric and sheathing layer in order to prevent permanent thermal cycling induced deformation. The pressure state induced by the resistance offered by such tapes against radial reformation reduces the triaxiality ratio of the stress state of the lead sheathing layer. It is known that a reduced triaxiality has a beneficial effect on ductility and fatigue life of metals. In the present work a series of finite element simulations are performed in presence of galvanized steel tapes at three different winding angles and without such reinforcement at all, obtaining a qualitative indication of its effect on the stress state induced in the sheathing layer. Loading conditions as internal pressure related to thermal dielectric expansion and cable bending are modelled. The numerical qualitative results are discussed in connection to a series of full-scale fatigue tests performed on subsea power cables with and without the support of steel tapes. 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/

Effects of Driveline Hybridization on Fuel Economy and Dynamic Performance of Hybrid Telescopic Heavy Vehicles

In this presentation, the effects of hybridization on fuel economy and dynamic performances of vehicles will be discussed. The R&D activity is part of a long term cooperation project between University Politecnico di Torino and the main telescopic producer in Italy Merlo Spa. The simulation and test are performed on the basis of a patented telescopic hybrid solution suitable for handling and agricultural applications. The system offers a method of greatest efficiency and least emissions. Power can split solely to the driveline or partially to driveline and machine hydraulics, and any excess power is back into battery charging. In ‘Full Electric’ mode, only the electric motor provides drive and the diesel engine is turned off. This mode is ideal for indoor working inside buildings or tunnels, or anywhere where noise and exhaust emission must be minimized. and the autonomy is that given by lithium batteries. The effects of hybridization due to combined analytical and simulation approach will also be covered. The analytical approach is based on the energy balance equations and considers all energy paths in the HEVs from the energy sources to wheels, whereas the simulation approach is designed and realized in MATLAB/ SIMULINK environment. Furthermore, in telescopic heavy vehicle, a series of experimental proofs are accomplished to gather up information to compare and analyze the results of analytical and simulation approach to experimental testing. Several tests have been performed first of all in order to identify the model. Secondly to characterize the performance and compare the dynamic performance with the conventional dieselhydraulic machine performed in different condition of a typical cycle for a telehandler application