3,681 research outputs found
Esperienze di partecipazione attiva delle studentesse e degli studenti al processo di decision-making: lâemozione della democrazia a Scuola-CittĂ Pestalozzi
Scuola-CittĂ Pestalozzi, fin dalla sua origine, ha organizzato la scuola in una comunitĂ educante in cui la partecipazione attiva degli studenti al processo di decision-making è sempre stata al centro del piano dellâofferta formativa. La scuola allâinizio era organizzata come una vera e propria cittĂ in cui a rotazione ogni funzione, dal sindaco al pubblico ministero, dallâassessore al giardiniere, era coperta da studenti e studentesse. Oggi quellâorganizzazione è cambiata, si è trasformata, sono rimasti però i paradigmi pedagogici di quellâesperienza. Il contributo che proponiamo è quello di raccontare le esperienze di oggi rispetto alla partecipazione attiva delle studentesse e degli studenti al processo di decision-
making
Reduction of Torque Ripple in Synchronous Reluctance Machines through Flux Barrier Shift
Synchronous Reluctance (SyR) machines are a viable alternative to other kinds of electrical machines in many fields. The simple rotor structure allows a high efficiency level with low manufacturing costs and higher safety in high-speed operations. However, one of the main problems of the SyR machines is the torque ripple generated by the interaction of the stator and rotor Magneto-Motive Force harmonics. Many design solutions have been proposed to date, but heavy torque ripple reduction has only been achieved with long optimizations runs or with complex machine structures. This paper presents an easy and effective method to reduce torque ripple through flux barrier shift. Two machines were designed in order to compare the proposed design with a state-of-the-art procedure. The machines designed with flux barrier shift presents similar performances to the optimized machine, with a lower design time and a more general design method
A tool to plan photon-in/photon-out experiments: count rates, dips and self-absorption.
A program that helps to plan experiments where the emitted X-rays are detected is presented. The tool is based on the standard formula for fluorescence-detected X-ray absorption spectroscopy and uses tabulated parameters to estimate count rates. The objective is to evaluate the feasibility of an experiment, estimate the influence of self-absorption on the spectral shape and investigate the possibility of range-extended EXAFS. The occurrence of `negative' edges, i.e. a decrease in the detected signal, is discussed
The Sound of Batteries: An Operando Acoustic Emission Study of the LiNiO Cathode in LiâIon Cells
The development of advanced Liâion batteries relies on the implementation of highâcapacity Niârich layered oxide cathode materials, such as NCM and NCA, among others. However, fast performance decay because of intrinsic chemical and structural instabilities hampers their practical application. Hence, thoroughly understanding degradation processes is crucial to overcome current limitations. To monitor instabilities of electrode materials under realistic operating conditions, the application of nondestructive operando techniques is required. While structural changes of crystalline phases can be studied by Xâray diffraction, microstructural changes (e.âg., particle fracture) cannot be easily accessed inâ
situ and are therefore mostly investigated ex situ. Here, we use acoustic emission (AE) measurements to probe a potential nextâgeneration cathode material in realâtime. Specifically, we focus on LiNiO(LNO) and demonstrate that AE events in different frequency ranges can be correlated with the formation of the cathode solidâelectrolyte interphase and the mechanical degradation during electrochemical cycling
Surface Modification Strategies for Improving the Cycling Performance of Ni-Rich Cathode Materials â Surface Modification Strategies for Improving the Cycling Performance of Ni-Rich Cathode Materials
Niârich layered lithium metal oxides are the cathode active materials of choice for highâenergyâdensity Liâion batteries. While the high content of Ni is responsible for the excellent capacity, it is also the source of interfacial instability, limiting the material\u27s lifetime due to a variety of correlated inâ and extrinsic factors. Hence, reconciling the opposing trends of high Ni content and longâterm cycling stability by modifying the material\u27s surface is one of the challenges in the field. Here, we review various studies on surface modification of Niârich (⼠80â%) layered cathode active materials in order to categorize current research efforts. Broadly, the three strategies of coating, surface doping and washing are discussed, each with their advantages and shortcomings. In conclusion, we highlight new directions of research that could bring Niârich layered lithium metal oxide cathodes from the laboratory to the real world
On the Euler-Lagrange equation for a variational problem: the general case II
In this paper we study the existence of a solution in Lloc() to the Euler\u2013Lagrange equation for the variational problem infu+W01()(ID(u)+g(u))dx(01) with D convex closed subset of Rn with non empty interior. By means of a disintegration theorem, we next show that the Euler\u2013Lagrange equation can be reduced to an ODE along characteristics, and we deduce that there exists a solution to Euler\u2013Lagrange different from 0 a.e. and satisfies a uniqueness property. These results prove a conjecture on the existence of variations on vector fields stated in Bertone and Cellina (On the existence of variations)
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