1,720,961 research outputs found
Lithium-ion battery dataset for data driven models’ development
No full textThis paper provides a novel dataset derived from lithium batteries' charge-discharge tests performed at laboratory scale. The primary goal is to enhance available data resources for the scientific community in the field of batteries reliability assessment, focusing our research on a thorough examination of lithium battery behavior. The dataset prioritizes the evaluation of critical parameters such as State-Of-Health (SOH), Remaining-Useful-Life (RUL) and State-Of-Charge (SOC), pivotal parameters for optimizing battery performance across various industrial applications allowing the development of data driven approaches such as Artificial Intelligence based techniques Moreover, the authors tried to replicate the phenomenon of the capacity regeneration due to the long relaxation times of the battery. By offering this expanded dataset, compatible with the well-known and well-established NASA and CALCE datasets, our aim is to facilitate deeper insights into battery behavior, thereby promoting advancements in Battery Management Systems (BMS). This work is part of a wider research mainly focused on studying the battery RUL using AI methodologies
Performances evaluation and characterization of a novel design of capacitive sensors for in-flight oil-level monitoring aboard helicopters
No full textCapacitive sensing is one of the most used sensing techniques for a large variety of applications. In particular, Capacitive Level Sensors (CLSs) are well suited for avionics, as they provide continuous measurements over the full range of the sensor, high reliability and low maintenance costs. However, industry standard CLSs used nowadays on helicopters show low sensitivity and poor dynamical characteristics. Hence, novel geometries were investigated and the simulation results (already presented in a previous manuscript) were encouraging. Therefore, three prototypes were built and tested. This manuscript is aimed at their experimental validation obtained using a mechatronic testbench with a high-precision positioning system purposely designed and built, able to move the probes in and out of an oil tank. The used oil had well-known electrical characteristics and many different tests were carried out. With the obtained data of capacity vs. oil level, an in-depth analysis of the probes' static (sensitivity, non-linearity, hysteresis) and dynamic (rise time, settling time, final error) behaviors were performed. From the analysis results it can be clearly seen that the novel design featuring a helicoidal slit along the external electrode of the cylindrical probe provides increased sensitivity, improved first-order response and negligible hysteresis phenomenon and non-linearity error
Prediction of Li-Ion Battery State-of-Health Based on Data-Driven Approach
No full textThe problem of State-Of-Health estimation of Li-Ion batteries is becoming of central importance in many critical fields of application. As of now, the majority of literature focuses on developing adequate tools in order to predict the future degradation of the battery capacity. However, in some cases, such algorithms require measuring several parameters as well as the use of several features and complex neural architectures, which make it difficult an implementation on a Battery Management System. This work builds on this gap by introducing a methodology for the estimation of the battery State-Of-Health (SOH) based on the prediction of residuals of an exponential fitting function. The features of the algorithm are only time-related variables, along with the number of endured cycles, which can be easily measured and stored in real-use applications. The proposed method has been tested and validated using a publicly available battery degradation dataset provided by the NASA prognostic research center. Early results are promising and an incentive for further developments
A design strategy for performance improvement of capacitive sensors for in-flight oil-level monitoring aboard helicopters
Full text linkCylindrical capacitors are largely employed in avionic industry as contact submerged probes of level sensors for in-flight oil-level monitoring for many reasons: their high robustness, their long MTBF (Mean Time Between Failure), maintenance-free character, virtually infinite resolution readings and last, relatively low cost. However, the cylindrical capacitors suffer of low sensitivity mainly due to small oil permittivity. This is clearly a disadvantage which collides with the ever-increasing demand for higher static and dynamic performances. To improve that, the approach adopted here consists in tweaking the conventional design of this kind of sensors guided by the study of their limitations in terms of static errors and poor responsiveness caused by phenomena of capillarity, high viscosity, and vibrations. Indeed, sensitivity doubling is proved to be achieved without compromising the indispensable former qualities. This is shown by the results of electrostatic, fluid mechanics, and structural dynamics analyses presented with enough details. Numerical simulations have been carried out and are here presented to confirm results. To summarize, with respect to the conventional capacitive level sensors currently available on the market, the achievements of the proposed design are i) an improved sensitivity that, for engine oils, is greater than , ii) a lower cost even though extra-costs for surface perforation must be accounted for, iii) cancellation of systematic error due to capillary phenomena and iv) improved dynamic response. Also, accurate experimental verifications are being carried out and will be shared in a future paper
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Battery Testing and Discharge Model Validation for Electric Unmanned Aerial Vehicles (UAV)
Full text linkElectrical engines are becoming more common than thermal ones. Therefore, there is an increasing interest in the characterization of batteries and in measuring their state of charge, as an overestimation would cause the vehicle to run out of energy and an underestimation means that the vehicle is running in suboptimal conditions. This is of paramount importance for flying vehicles, as their endurance decreases with the increase in weight. This work aims at finding a novel empirical model for the discharge curve of an arbitrary number of battery pack cells, that uses as few tunable parameters as possible and hence is easy to adapt for every single battery pack needed by the operator. A suitable measurement setup for battery tests, which includes voltage and current sensors, has been developed and described. Tests are performed on both constant and variable power loads to investigate different real-world scenarios that are easy to reproduce. The main achievement of this novel model is indeed the ability to predict discharges at variable power based on a preliminary characterization performed at constant power. This leads to the possibility of rapidly tuning the model for each battery with promising accuracy. The results will show that the predicted discharged capacities of the model have a normalized error below 0.7%
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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