2,795 research outputs found
Unified model of lithium-ion battery and electrochemical storage system
No full textNowadays, energy storage systems are of paramount importance in sectors such as renewable energy production and sustainable mobility because of the energy crisis and climate change issues. Although there are various types of energy storage systems, electrochemical devices such as electric double layer capacitors (EDLCs), lithium-ion capacitors (LiCs), and lithium-ion batteries (LiBs) are the most common because of their high efficiency and flexibility. In particular, LiBs are broadly employed in many applications and preferred in the mobility sector, where there is a need for high energy and high power. To ensure good operating conditions for a battery and limit its degradation, it is important to have a precise model of the device. The literature contains numerous equivalent circuit models capable of predicting the electrical behavior of an LiB in the time or frequency domain. In most of them, the battery impedance is in series with a voltage source modeling the open circuit voltage of the battery for simulation in the time domain. This study demonstrated that an extension of a model composed exclusively of passive elements from the literature for EDLCs and LiCs would also be suitable for LiBs, resulting in a unified model for these types of electrochemical storage systems. This model uses the finite space Warburg impedance, which, in addition to the diffusion process of lithium\lithium ions in the electrodes\electrolyte, makes it possible to consider the main capacitance of the battery. Finally, experimental tests were performed to validate the proposed model
Open-Circuit Voltage Variation in LiCoO<sub>2</sub> Battery Cycled in Different States of Charge Regions
No full textCurrently, the urgent needs of sustainable mobility and green energy generation are driving governments and researchers to explore innovative energy storage systems. Concurrently, lithium-ion batteries are one of the most extensively employed technologies. The challenges of battery modeling and parameter estimation are crucial for building reliable battery management systems that ensure optimal battery performance. State of charge (SOC) estimation is particularly critical for predicting the available capacity in the battery. Many methods for SOC estimation rely on the knowledge of the open-circuit voltage (OCV) curve. Another significant consideration is understanding how these curves evolve with battery degradation. In the literature, the effect of cycle aging on the OCV is primarily addressed through the look-up tables and correction factors applied to the OCV curve for fresh cells. However, the variation law of the OCV curve as a function of the battery cycling is not well-characterized. Building upon a simple analytical function with five parameters proposed in the prior research to model the OCV as a function of the absolute state of discharge, this study investigates the dependency of these parameters on the moved charge, serving as an indicator of the cycling level. Specifically, the analysis focuses on the impact of cycle aging in the low-, medium-, and high-SOC regions. Three different cycle aging tests were conducted in these SOC intervals, followed by the extensive experimental verification of the proposed model. The results were promising, with mean relative errors lower than 0.2% for the low- and high-SOC cycling regions and 0.34% for the medium-SOC cycling region. Finally, capacity estimation was enabled by the model, achieving relative error values lower than 1% for all the tests
Calendar Aging Effect on the Open Circuit Voltage of Lithium-Ion Battery
No full textIn recent years, lithium-ion batteries (LiBs) have gained a lot of importance due to the increasing use of renewable energy sources and electric vehicles. To ensure that batteries work properly and limit their degradation, the battery management system needs accurate battery models capable of precisely predicting their parameters. Among them, the state of charge (SOC) estimation is one of the most important, as it enables the prediction of the battery's available energy and prevents it from operating beyond its safety limits. A common method for SOC estimation involves utilizing the relationship between the state of charge and the open circuit voltage (OCV). On the other hand, the latter changes with battery aging. In a previous work, the authors studied a simple function to model the OCV curve, which was expressed as a function of the absolute state of discharge, q, instead of SOC. They also analyzed how the parameters of such a curve changed with the cycle aging. In the present work, a similar analysis was carried out considering the calendar aging effect. Three different LiB cells were stored at three different SOC levels (low, medium, and high levels) for around 1000 days, and an analysis of the change in the OCV-q curve model parameters with the calendar aging was performed
Discorso pedagogico e prospettiva sistemico-relazionale
No full textStarting with a few thoughts about the current pedagogical debate expressed within the work, the contribution of Luigi Pati, highlights the importance of relational systems perspective in the pedagogical discourse. The author proposes an analysis and historical evolution of the General Theory of Systems (TGS), illustrating the importance of the same in the action and in the educational relationship between educator and student
Sobre Luigi Ferrajoli y el constitucionalismo
No full textIn this paper, the author poses several general questions on Luigi Ferrajoli’s paper. Firstly, he writes on Ferrajoli’s construction of a theory that comprehensively infers, still always in a deductive way, the scope of a complex set of primitive terms and definitions. Secondly, the author questions his way to understand and particularly to reconstruct the so-called «constitutional paradigm». Thirdly, the author writes about Ferrajoli’s approach to the concepts of «validity» and «enforcement» of rules. Fourthly, he discusses Ferrajoli’s definition of garantist constitutionalism, particularly his conception of this sort of constitutionalism as an improvement or complement to legal positivism -inasmuch as constitutionalism respects both the being of the Law and its normative or ideal (must be) dimension. Finally, he revises the objections that Ferrajoli addressed to constitutionalism (the thesis of the separation between Law and morality, the distinction between principles and rules and the criticism of the weighting) introducing new arguments.El autor plantea una serie de objeciones al texto de Luigi Ferrajoli. En primer lugar, se refiere a la construcción por parte de Ferrajoli de una teoría que infiere de un modo exhaustivo, pero siempre deductivamente, el alcance de un complejo conjunto de términos primitivos y definiciones. En segundo lugar, el autor duda sobre la forma de ver y, sobre todo, de reconstruir el llamado «paradigma constitucional». En tercer lugar, el autor objeta el tratamiento que Ferrajoli hace de los conceptos de «validez» y «vigor» de las normas. En cuarto lugar, hace referencia a la definición que Ferrajoli realiza del constitucionalismo garantista, en concreto a la consideración de éste como mejora o complemento del positivismo jurídico que se logra gracias a que el constitucionalismo observa no sólo el «ser» sino el «deber ser» del Derecho. Finalmente, repasa las críticas que Ferrajoli realiza al constitucionalismo (la tesis de la separación entre Derecho y moral, la distinción entre principios y reglas y la crítica a la ponderación), expresando sus diferencias
Six Characters in Search of an Author (Text)
No full textSix Characters in Search of an Author (Sei personaggi in cerca d’autore) is an Italian three-act play written by Luigi Pirandello in 1921, considered as one of the earliest examples of absurdist theatre. It’s a play within a play that deals with perceptions of reality and illusion, and plays with the ideas of identity and relative truths
Luigi Pirandello: In Search of an Author
No full textIn 1925 Luigi Pirandello brought his troupe to England as part of a worldwide tour. This classic program re-creates one day in London as "The Einstein of the Theater" watches his plays and, away from the footlights, confronts the paradoxical nature of his life. Portions of Six Characters in Search of an Author; Henry IV; Right You Are, If You Think You Are; and The Rules of the Game are meticulously staged, using actors' accounts, period descriptions, and Pirandello's own comments. Plus, biographical notes written by Pirandello himself provide a new angle on the inner torment that animates his work, while playwright Julian Mitchell and novelist Leonardo Sciascia critically analyze the action as it unfolds. (60 minutes, color
Organizing Chamber Music as Culture
No full textIn this paper Luigi Maria Sicca suggests on the one hand that organization theory offers an interpretation of the reality of arts producing organizations and on the other that the empirical analysis of these realities can supply new input for organization theory. As a practical example of artistic production the Author refers to an international chamber music festival. Close inspection of chamber music will reveal characteristics that apply to any type of organization. Sicca begins by looking at the nature of arts management and the arts manager. L.M.Sicca goes on to analyse the characteristics of the production process in the performing arts, which can be seen as communication taking place on three levels: between audience and performers (concept of “prosumer”); within the performing group (“listening ability”); between the author of the written text and the performer/interpreter (“concept of value”). Luigi Maria Sicca finishes by showing how in a symbolic-cultural framework the features identified in the paper can feed back into organization studies
L'educazione per la conquista dell'identità personale
No full textThe essay argues the need to pay attention to the educational growth and welfare of the individual personality that has relations in a certain context. The author reflects on the strategies through which the environment can facilitate or not the process of individual humanization
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