• Energy Research

Today, as railways increase their capacity and speeds, it is more important than ever to be completely aware of the state of vehicles fleet‟s condition to ensure the highest quality and safety standards, as well as being able to maintain the costs as low as possible. Operation of a modern, dynamic and efficient railway demands a real time, accurate and reliable evaluation of the infrastructure assets, including signal networks and diagnostic systems able to acquire functional parameters. In the conventional system, measurement data are reliably collected using coaxial wires for communication between sensors and the repository. As sensors grow in size, the cost of the monitoring system can grow. Recently, auto-powered wireless sensor has been considered as an alternative tool for economical and accurate realization of structural health monitoring system, being provided by the following essential features: on-board micro-processor, sensing capability, wireless communication, auto-powered battery, and low cost. In this work, an original harvester device is designed to supply wireless sensor system battery using train bogie energy. Piezoelectric materials have in here considered due to their established ability to directly convert applied strain energy into usable electric energy and their relatively simple modelling into an integrated system. The mechanical and electrical properties of the system are studied according to the project specifications. The numerical formulation is implemented with in-house code using commercial software tool and then experimentally validated through a proof of concept setup using an excitation signal by a real application scenario.

Morphing technology is increasingly emerging as a novel and alternative approach for performing the controlled re-entry and precise landing of space vehicles by using adaptive aeroshell structure designs. This work is intended as a preliminary conceptual design of an innovative shape-changing mechanism for the controlled re-entry and safe recovery of CubeSat class systems aimed at recovering payloads and data from LEO at low cost for post flight inspections and experimentations. Such an adaptive and mechanically deployable aeroshell consists of a multi-hinge assembly based on a set of finger-like articulations having two-modal capabilities. The deployable surface can be modulated by a single translational actuator in order to adapt the lift-to-drag ratio for guided entry. Furthermore, once deployed, the system can activate eight small movable aerodynamic flaps that can be individually morphed via an SMA-based actuation to enhance the capsule maneuverability during the re-entry trajectory, by using exclusively aerodynamic forces to guarantee additional precision in landing. Multi-body simulations on retraction/deployment of the system are addressed to investigate the most critical aspects for actual implementation of the concept. Additionally, the morphing behavior and the control effect of the shape memory alloy actuation are preliminary assessed through parametric analysis. This paper is framed within a scientific cooperation between Italy and Brazil in the framework of the SPLASH project, funded in part for the Italian side by a grant from the Italian Ministry of Foreign Affairs and International Cooperation (MAECI), and by CONFAP through the involved State Funding Agencies (FAPs) for the Brazilian side.

Magneto-rheological fluids, or MRF, have been known for a long time in the technological and scientific community [...]