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The use of batteries and other electrochemical devices in modern power systems is rapidly increasing, with stricter requirements in terms of cost, efficiency and reliability. Innovative monitoring solutions are therefore urged to allow a successful development of a wide range of emerging applications, including electric vehicles and large-scale energy storage to support renewable energy generation...
Frequency-domain current signature analysis for fault detection on induction machines typically requires a very fine frequency resolution to distinguish between spectral components that differ from each other by multiples of the (usually very low) slip frequency. It is well known that if such a high resolution is not achieved, significant leakage errors may arise and misleading diagnostic information...
This paper proposes a new design solution for high-current shunt resistors aiming at optimizing the frequency response in a specified frequency range. It is based on a solid cylindrical shunt, whose sensing circuit runs through a straight hole drilled in the shunt itself. Compared to other solutions proposed in the literature, typically based on coaxial or cage configurations, this approach allows...
A serious failure of a power transmission line can generate substantial financial losses due to the power outage. Consequently, utilities have a clear incentive to assess the actual condition of strategically important transmission lines, with the aim to minimize the risk of failures, enhance the maintenance practices and plan the development of the transmission network. This work focuses on the analysis...
PEM fuel cell (FC) operation is likely to be characterized by voltage dips on time scales shorter than 1 s, arising from temporary flooding of gas channels or porous layers, particularly when the FC is operated at high humidity levels. If supercapacitors are employed together with the FC as energy storage systems, they can make up for the temporary lack of energy produced by the FC. However, the steep...
Water flooding is one of the main causes of performance degradation for polymer electrolyte membrane (PEM) fuel cells and its prompt detection is therefore important to guarantee optimal fuel cell operation. This paper aims at comparing the most common methods for flooding diagnosis, which are based on electrical or gas pressure measurements. Some critical issues about them are discussed, highlighting...
This paper aims at testing the applicability of a previously proposed diagnostic method for PEM fuel cells, which exploits the ripple produced by switch-mode converters to monitor the fuel cell state of health. A low-voltage DC/DC boost converter has been designed for this purpose, suitable to be directly connected to a single cell. This paper shows how the cell response to the converter current ripple...
The power produced by a solar panel depends on several parameters. In order to optimize the production, the ability to operate in the Maximum Power Point (MPP) condition is requested. The ability to identify and reach the MPP condition is therefore critical to an efficient conversion of the photovoltaic energy. In this paper, several computational intelligence paradigms are challenged in the task...
In recent years, DC/DC converters have become more and more widespread due to the development of new DC energy sources. This has led to intensive studies of DC/DC converters and new configurations have been proposed in the literature. In particular, there are very interesting high efficiency configurations. The current fed, DC/DC push-pull converter with two input inductances was thoroughly analyzed...
National and international structural design codes requires several final checks on the built structure. The aim is to verify that the structural characteristics of the building are compliance with the design. It is clear that for this purpose non-destructive testing methods are preferred. The authors have previously presented a method for the characterization of slabs made of steel fiber reinforced...
In the technical literature many models capable of representing the behavior of the induction machine have been presented. The traditional Park model is very easy to be implemented but it does not take into account the flux density space harmonics. It is well known that it can be modified in order to consider stator and rotor asymmetries. However for some applications such as the study and the development...
The approach to the maintenance of devices and systems has strongly changed in the last years, thanks to the availability of more and more sophisticated technologies. In particular, when the servicing involves very critical processes, a new interesting strategy is represented by the Condition Based Maintenance (CBM). It is based on the continuous observation of some physical parameters which permits...
SFRC, steel fiber reinforced concrete, is a widely employed material in building construction. The fibers assure a better mechanical behavior with respect to plain concrete. Testing the material "on the site" represents a very important goal. In particular, there is a strong need to have a reliable measurement method available which allows assessing information about size, orientation and...
Power quality represents a crucial issue in low voltage distribution networks. Welding equipments are among the most polluting loads because of their strong nonlinear behavior and their highly intermittent working cycle with a degree of randomness which causes the phenomenon of voltage flicker. The usual approach to the flicker mitigation consists in the introduction of static VAr compensators connected...
The employment of inverter-fed induction machines in industrial plants is growing thanks to the continuously decreasing costs related to power electronics devices and microcontrollers. It is well known that a sudden failure in an asynchronous machine employed in a continuous process may cause severe profit losses: the possibility to early detect incipient faults is vital in order to avoid this scenario...
Steel fiber reinforced concrete (SFRC) is a composite material which is becoming more and more widely employed in building construction, due to its improved resistance to cracking and crack propagation with respect to plain concrete. Its mechanical behavior strongly depends on the choice of the properties of the fibers and their volume fraction in the concrete mixture. As any material employed in...
In modern industrial applications, because of the increasing requirements in term of quality and efficiency, the employment of an effective maintenance strategy is becoming crucial. As a consequence, the service activity is moving towards the development of diagnostics and prognostics techniques aiming to minimize the impact of the failures on the production. In previous papers two simple diagnostic...
The target of this work is to design and test an on-board diagnostic device able to detect a rotor fault in a small cage rotor inverter-fed induction machine. In particular, the system computes the values of two indexes introduced by the authors in previous work. The capability of the aforementioned indexes to detect rotor asymmetries in open loop asynchronous AC drive systems has been previously...
Steel fiber reinforced concrete structural elements represent very interesting materials which employment has led to tangible advantages in construction technologies over the last decades. The behaviour of this kind of materials is strictly related to the fiber dispersion inside the cementitious matrix. For this reason, in the last years different non destructive measurement methods have been proposed,...
The linear model of the dynamic low-frequency loudspeaker is widely used nowadays, and it is well known how to assess its parameters from simple measurements. However, this is a small-signal model which well represents the behavior of a loudspeaker only when slight diaphragm displacements are considered. In many cases it is important to have a more accurate model which takes into account the nonlinear...
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