1,721,009 research outputs found
A Novel Phase-based Method for UHF-RFID Tag Localization via UAV
No full textThis paper presents a novel phase-based method for UHF-RFID tag localization in outdoor scenario. Phase measurements are acquired during circular trajectories of the reader antenna carried out by an Unmanned Aerial Vehicle (UAV). The standard deviation of such phase samples is employed as input parameter of the positioning method. Localization performance is investigated through a numerical analysis, by considering the uncertainty associated to the measurements of phase samples and reader antenna trajectory in real outdoor scenario
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
Temperature monitoring strategy for microclimate prediction in low-automation greenhouses: a preliminary analysis
No full textClimate control strategies in low-automation greenhouses typically rely on the measurements from a single sensor. Indeed, implementing more complex monitoring devices and sensor networks may increase investment costs without necessarily improving profitability. This paper presents a low cost and low complexity temperature monitoring strategy, which is illustrated in a case study of tomato cultivation during the mid-season in a traditional Mediterranean greenhouse located in Pisa, Italy. The objective is to evaluate the temperature distribution within a portion of the greenhouse and to investigate the representativeness of single-point measurements for assessing the local microclimate. During the experimental campaign, the vertical and horizontal temperature differences reached maximum values of 9.9 °C and 7.3 °C, respectively. The performed temperature measurements appear to be correlated (R2 > 0.95), and this information was exploited for the prediction of the greenhouse temperature in multiple points, resulting in an average RMSE of 1.3 °C, with differences depending on the specific position taken as reference. These findings offer insights into the representativeness of single-point measurements and the optimal positioning of the sensor station within the greenhouse. The inclusion of microclimate heterogeneity in climate control strategies can help minimise the local presence of unfavourable growth conditions, the excess of energy use, and installation and maintenance costs
Analysis of Current Ripple effect on Lithium batteries
No full textThis paper investigates the Lithium battery behavior and possible aging effects in presence of current ripple during the operation. In the context of a research funded project aimed at increasing the safety level of Lithium batteries for the naval propulsion, we present the results of an experimental analysis aimed at investigating the effect of current ripple on cell performances. An ad-hoc experimental setup is developed to test the batteries and the effect of current ripple on battery capacity and cell aging is discussed throughout the paper
A phase-based method for UHF RFID gate access control
No full textThis paper presents a phase-based method for UHF-RFID tag classification in gate access control systems. The proposed system exploits only a single reader antenna and multiple phase samples collecting during the tag motion. Experimental results in real indoor scenario show the method capability to discriminate incoming, outgoing, and passing tag actions. The method can be applied at every identification point equipped with a COTS UHF-RFID system with a software/firmware implementation without requiring additional hardware
Effect and compensation of ADC nonlinearity on magnetic accommodation measurements
No full textIn this paper we analyze how static errors of Analog-to-Digital converters (ADCs) can influence the measurement of magnetic accommodation in soft ferrite core. In a first analysis, the discussion is carried out through a series of simulated ADC INLs applied to simulated signals and experimental data. Possible impacts of the integral nonlinearity (INL) on the reconstruction of the B H trajectory are shown. In a second phase, a real ADC INL is considered to better quantify the impact of real ADC errors on the measurements. An easy to implement procedure based on physical symmetry property of the material is presented and adopted to reduce the INL effect on magnetic accommodation measurements. Finally, a comparison between the proposed approach and a mid-point linearization compensation technique of INL is reported showing the validity of the presented procedure
Current Distribution in Railgun Rails through Barycenter Filament Model
No full textIn this article, we present a novel measurement method to estimate the current distribution in electromagnetic rail launchers. A loop array is magnetically coupled with the railgun to reconstruct the current barycenter position, from which we can argue on the current distribution through the rail cross section. After describing the adopted measurement procedure, we present the results of an experimental analysis performed using the NGL60 rail launcher at the laboratories of the French-German Research Institute of Saint-Louis (ISL). We also compare the experimental results with finite-element simulations, and we show the agreement during the current pulse transient. Finally, we provide a measurement uncertainty analysis performed using Monte Carlo method
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
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