Francesco Castelli-Dezza

The objective of this study is to assess cross-track generalisation and direct controlled-to-service transfer of wheel-flat classifiers based on three revolution-wise axle-box acceleration indicators: Root Mean Square (RMS), Crest Factor (CF), and Wheel-Flat Index (WFI). Full-scale controlled measurements were analysed across distinct track sections, and cross-track transferability was assessed through nested leave-one-track-out validation of speed-dependent k-nearest neighbour classifiers. Final all-track models were applied without retraining or field-specific adaptation to 403 acquisitions collected during commercial freight operation with a wireless axle-box sensor. The controlled measurements showed that the dynamic manifestation of a fixed wheel-flat is not spatially invariant, while the combined RMS–CF–WFI representation retained useful discrimination across track sections. Cross-track balanced accuracy ranged from 0.841 to 0.980; all-track models achieved mean balanced accuracies of 0.967, 0.937, and 0.931 at 30, 45, and 60 km/h. In service, balanced accuracy was 0.878, specificity 0.984, and binary-decision coverage 0.978 against a manually reviewed signal-based reference. Applicability analysis of the exploratory high-speed extension indicated that speed extrapolation does not necessarily imply feature-space extrapolation, although false-positive acquisitions showed substantial departures from the controlled support. These results support compact, transferable axle-box diagnostics for in-service wheel-flat monitoring.

Early detection of wheelset defects is essential for ensuring railway safety. Wheelset condition monitoring can provide continuous information about the health of the system, thus avoiding time-consuming and expensive operations such as periodic inspections. This work deals with the study of railway wheelset wheel-flat identification features based on vibration signals from axle-box measurements. The aim is to obtain a simple and straightforward solution that can be easily implemented on a complete autonomous on-board sensor for wheelset defect prediction. Numerical simulations, by coupling a multi-body model of a coach with a new approximation of a wheel-flat model, were run in order to estimate the nature of the problem and the technical acquisition characteristics needed for a sensor node to be installed on real trains. Then, experimental campaigns were carried out on a wheelset test bench with defects artificially created to validate the presented methodology based on time domain feature extraction. A signal processing technique, which does not require the aid of any other hardware to obtain the revolution speed, is proposed. The methodology allows clear detection of wheel flats starting from 30 mm, especially at lower speeds. Even when considering the influence of wear, high defect conditions remain easily distinguishable.

This paper investigates the design of stator cooling channels to efficiently take away the heat in the wound field synchronous motor (WFSM) for EV application. The influence of the stator cooling channel on the electromagnetic and thermal performance is compared and analyzed in this paper, including the electromagnetic torque, losses, and temperature rise considering the constraints of the fluid pressure drop. To improve the computational efficiency, the 2-D electromagnetic finite-element method and thermal circuit method are employed for the WFSM. The optimal selection of stator cooling channels is obtained after the sensitivity and correlation analysis by considering an 800 Nm, 3700 rpm WFSM for a heavy-duty vehicle.

This paper presents the research activities and findings of "Intelligent Infrastructure Design for Multifunctional Efficient Farm", which is a multidisciplinary project aimed at mitigating poverty and malnutrition by upgrading farms located in isolated areas. Through improvements in living conditions and infrastructure, this project aims to increase farm productivity, create employment opportunities and promote the local distribution of zero-mile food. Specifically, farms should become multifunctional, energy autonomous, and environmentally sustainable. To achieve these goals, the project focuses on three key interventions: (1) the design of low-cost, low-environmental impact infrastructures to improve connectivity with surrounding cities, where roads and bridges are currently lacking; (2) the development of refrigerated cold rooms to enhance food preservation; and (3) the design of photovoltaic power plants for farm electrification. The methodologies and sizing procedures are based on simplified approaches implementable in free, open-source software; flexibility is ensured so that local technicians can replicate and adapt them to similar contexts by accounting for the needs of the local population, prioritizing the use of locally available materials. The authors considered a farm area of Mpangala village (in the Democratic Republic of the Congo) as a case study to assess the practicality of the developed procedures.

Multilevel converters are a valid solution for improving efficiency and harmonic content in many applications, from low to high power scenarios. Moreover, the number of available switches allows the integration of advanced functionalities in the systems, safety operations included. Thus, a new family of modular multilevel converters for rectifying, inversion and DC/DC operations has been studied in the last years and patented by the Italian Transmission System Operator for possible applications in HVDC conversion stations. Their working principles were validated as well as the expected real behavior was predicted thanks to switching models. A low-voltage prototype has been designed based on their simulations. However, the switching approach is heavy from a computational point of view and time consuming to run. Thus, this work proposes simplified average equivalent circuits for this kind of devices that have been validated versus the switching model. This approach should lead to easier and faster studies of the converter as well as the control design of new power stations.

This work shows a novel solution that allows contactless capacitive signal and power transfers among bodies in relative rotation. After a first presentation of the simple working principles of the system and its features, the proposed capacitive wireless transfer is designed and applied to a real case scenario. Namely, the goal is to use the same capacitive channel for both supplying sensors and a microcontroller, but also to exchange data between the two bodies. The paper shows simplified analytical computations, and the results of finite-elements simulations run during the sizing process. The power transfer capabilities are verified through a simulation involving power components and including estimated non-intentional cross-couplings between the plates of the capacitors.

A simplified procedure for sizing an off-grid photovoltaic plant with battery storage is presented in this paper and applied to the real case-study of a sub-Saharan farm. This work is within the framework of a wider project that deals with the sustainable and ecological transition of rural and remote areas, aiming at giving contributions against poverty and malnutrition. Thus, the objectives of this manuscript are to analyze the peculiarity of this installation and set a suitable simplified procedure for supplying the farm with electrical energy based on the following main steps: a literature review on the available procedures, research on useful standards for load and continuity constraints definitions, an analysis of the available software for photovoltaic plant design. The proposed steps should be easily tunable, adaptable and implementable by local engineers, even those working in other parts of the world, but sharing similar needs for continuity in the power supply with the sub-Saharan farm.