1,720,986 research outputs found
Analysis of SoH for lithium battery cells operating under vibration stress
No full textNowadays, the pollutant emissions reduction and the increase in the renewable energy share are key points for a sustainable development. In addition to the industrial and civil sectors, transportation has a crucial role still representing around 25% of the whole green-house gas emission. Despite the electrification of the automotive sector is increasing, several challenges need to be overtaken in order to extend the use of electric sources to the aviation sector, thus requiring investigation on both electrical and mechanical behavior of energy storage devices. This paper presents a preliminary analysis of the state of health (SoH) for 3Ah lithium battery cells operating in vibration stress conditions. The effect of different shaking frequencies applied to the radial and the longitudinal battery axes are investigated. Moreover, both short-term and long-term (aging) tests are conducted. The results showed that no significant effect on capacity fade can be observed. However, a slightly different capacity, calculated for charge and discharge processes, was observed under vibrating tests, thus suggesting that mechanical vibrations can possibly interact with the ion-transfer mechanism
Conception of a Temperature Sensor Based on 100-μm CoFeSiB Ferromagnetic Wire
No full textIn this article, we present the conception of a temperature sensor based on a ferromagnetic microwire having a diameter of about 100~mu ext{m} and a composition of CoFeSiB as 80% Co-Fe and 20% Si-B. We experimentally analyze the influence of the temperature and excitation frequencies on the hysteresis loop of the material. Discussion about how the temperature can act as a measurand through the analysis of the output of the sensor is carried out. Temperature is correlated with the magnetic characteristic of the material, and the results are addressed in light of the recent literature and of the Ising model. All measurements were performed under controlled conditions. An ad hoc setup was developed, and an experimental analysis was carried out to characterize the microwire temperature sensor
On the Effect of Position Uncertainty of the UHF-RFID Reader Trajectory in SAR-based Localization via UAV
No full textIn the Internet-of- Things paradigm, the knowledge of item/people position becomes crucial to develop new services and applications. Autonomous vehicles, robots and drones rep-resent key enablers to implement cutting-edge solutions among with localization of items or people. In this paper, we present the adoption of an Unmanned Aerial Vehicle (UAV) equipped with a Radio Frequency Identification (RFID) system to locate passive RFID tags in outdoor scenario. In particular, we apply a synthetic-aperture-radar approach and we discuss how the position uncertainty of the reader-antenna trajectory affects the tag localization uncertainty
Exploitation of Temperature Effect in 100 μm Ferromagnetic Wire
No full textIn this paper we present a characterization of a ferromagnetic microwire having a diameter of about 100 μm and a composition of CoFeSiB as 80% Co-Fe, 20% Si, B. We experimentally analyze the influence of the temperature and excitation frequencies on the hysteresis loop of the material. In particular, results and discussion about how the temperature can affect the magnetic characteristic of the material are provided. All measurements have been performed under controlled conditions. A suitable setup has been conceived, realized and an experimental campaign with the characterization of the microwire has been accomplished obtaining very promising results
Failure limit analysis for Li-ion batteries using Ragone plot: a preliminary study
No full textIn this paper, a new possible definition of failure zone for Li-ion batteries is proposed. Based on the general concept that a battery can be considered failed when its performance no longer meets the requirements of the application for which it is designed, a new application-dependent failure zone definition is proposed using the Ragone plot of the cell. The results of an experimental campaign to validate the proposal are presented and discussed in the paper
Investigation of a 100 μm Magnetic Wire for Temperature Sensing based on a Time Domain Readout
No full textIn this paper we present an analysis of temperature response of a 100 μm hysteretic wire exploiting a time domain readout. The ferromagnetic wire is composed of 80% Co-Fe, 20% Si, B. The study here conducted investigates the effect of temperature in the microwire with an output measured as time response, which represents an intriguing method to convert the target quantity. The experiments have been accomplished by using a MuMetal® electromagnetic shield with controlled temperature and an acquisition system to process the output. Results here reported evince the suitability of the proposed method which arouses interest for several interesting applications
Comparison of Magnetic Field Sensors for Current Distribution Reconstruction through Barycenter Filament Model
No full textIn this paper we compare different magnetic field sensor technologies that can potentially be used to characterize current distribution in massive conductors. The approach is based on the application of the current barycenter method, introduced by the authors in a previous work, to obtain information about the current distribution in massive conductors fed by pulsed current through the use of an array of search loops placed around the conductor. After briefly recalling the method, this paper analyzes the possible use of different magnetic field sensor technologies (search loops, vector and scalar magnetometers) to compare their performance in the use of the current barycenter reconstruction method. The introduced model error as a function of sensor type, conductor cross-sectional shape, and mutual position between sensors and conductor are analyzed and discussed throughout the paper
Temperature effects and damage detection on CFRP through electrical impedance spectroscopy
No full textCarbon fiber reinforced polymers (CFRPs) are particularly suitable for aerospace applications due to their specific mechanical properties. During their service life, these materials can suffer damage, sometimes difficult to detect, which may compromise their mechanical performances. The variation of the electrical properties of CFRPs is one of the strategies that can be used to monitor such damage. However, multiple variables contribute to this variation. This paper presents a preliminary analysis of the electrical impedance dependence on temperature and on damages outbreaks. The measurements are performed in controlled environment on a wide range of temperature and frequency. In some cases, the measured data show an impedance change due to the damage presence, which is of similar entity with respect to the variations caused by temperature. This may lead to misleading interpretations of impedance measurements in the absence of additional information. Hence the need of a proper temperature monitoring to possibly use electrical impedance spectroscopy analysis is required to unequivocally determine the health status of CFRPs
ORBITER: Phase-Based Localization of RFID Tags via Circular Antenna Trajectory
No full textIn this article we present a method for ultrahigh-frequency (UHF)-radio frequency identification (RFID) tag localization via phase measurements gathered during a circular trajectory of the reader antenna, that is, ORBITER. The localization is pursued by exploiting both the minimum and the variability of the unwrapped phase curve via appropriate mathematical operators. We investigate the sensitivity of the method, by highlighting the conditions for its applicability and the proper choice of the measurement parameters. For the experimental validation, we use a 3-D Cartesian portal for antenna motion along circular trajectories, that allows us to assess the performance and reliability of the method in a controlled environment. Results show that the proposed method achieves good accuracy and robustness in localizing UHF-RFID passive tags. The method finds applications in both indoor and outdoor scenarios
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