125,390 research outputs found
Il ruolo della spettroscopia di assorbimento di raggi X nello sviluppo di materiali per batterie al litio
No full textIl ruolo della spettroscopia di assorbimento di raggi X nello sviluppo di materiali per batterie al litio
Marco Giorgetti, Mario Berrettoni
Dipartimento di Chimica Fisica ed Inorganica, Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, email [email protected] telefono 051 2093666 fax 051 2093690
Una tra le più interessanti classi di batterie moderne [1] è rappresentata dalle batterie ad intercalazione, dove ioni di piccole dimensioni (quali il litio) sono inseriti, in maniera efficiente e reversibile, in un opportuno materiale. In questo panorama, una sorgente di litio funge da anodo e il materiale ospitante da catodo. La scelta del materiale ospitante caratterizza in maniera determinante il prodotto finito, ossia le proprietà elettrochimiche della batteria stessa. Gli ossidi dei metalli di transizione sono frequentemente utilizzati come catodi per batterie ricaricabili al litio visto le loro particolari proprietà strutturali, a cui si aggiungono bassi costi e relativa abbondanza nella crosta terreste.
Generalmente il processo di intercalazione di litio (che avviene durante la scarica della batteria) può trasformare il materiale o avvenire senza drastici variazioni della struttura ospitante. Durante la fase di de-intercalazione (o rilascio degli ioni litio) il materiale può tornare ad essere una copia identica del materiale di partenza, e quindi il processo è detto reversibile. In caso contrario, il materiale intercala e rilascia ioni litio in maniera irreversibile.
In questo contesto si inserisce la spettroscopia di assorbimento di raggi X. La spettroscopia di assorbimento di raggi X (XAS) è una tecnica che indaga la struttura locale attorno ad un atomo selezionato, detto fotoassorbitore, e può essere applicata a materiali disordinati, amorfi e cristallini [2-4], fornendo informazioni in un intervallo di 4-5 Å attorno all’atomo selezionato. In questa presentazione verrà mostrato come l’utilizzo di questa tecnica possa essere utilizzato per lo studio e lo sviluppo di materiali catodici per batterie secondarie al litio.
In particolare verranno presentati come esempi esplicativi l’applicazione agli ossidi di vanadio come materiale catodico per batterie secondarie. Lo studio verterà sia sui materiali di partenza, che sulla batteria stessa in fase di funzionamento, tramite degli studi in-situ. Lo studio combinato della porzione elettronica (XANES) e strutturale (EXAFS) dello spettro di assorbimento permette l’estrazione di informazioni relative alla reversibilità elettronica e strutturale stessa dei sistemi in esame, ponendo le basi per il la comprensione dell’elettrochimica della batteria stessa.
1. D. Linden, T.B. Reddy, “Handbook of batteries”, McGraw-Hill Professional; 3rd edition, 2001.
2. M. Giorgetti, S. Passerini, W. H. Smyrl, M. Berrettoni Inorg. Chem., 2000, 39 1514.
3. E.Frabetti, G.A. Deluga, W. H. Smyrl, M. Giorgetti, M. Berrettoni J. Phys. Chem. B. 2004, 108, 3765.
4. M. Giorgetti, I. Ascone, M. Berrettoni, P. Conti, S. Zamponi, R. Marassi, J. Biol. Inorg. Chem., 2000, 5, 156
Challenges and recusals of judges and arbitrators in international courts and tribunals/ edited by Chiara Giorgetti.
No full textBased on papers presented at the Annual Meeting of the American Society of International Law in April 2014.Includes bibliographical references and index."Challenges and Recusal of Judges and Arbitrators in International Courts and Tribunals" provides an in-depth analysis of a fundamental control mechanism of international dispute resolution in the context of some of the main international courts and tribunals. The book also assesses specific grounds and standards for challenging judges and arbitrators, and includes both regional and personal perspectives.Introduction / Chiara Giorgetti -- The challenge and recusal of judges at the International Court of Justice / Chiara Giorgetti -- Disqualification of arbitrators under the ICSID Convention and rules / Meg Kinnear and Frauke Nitschke -- The determination of arbitrator challenges by the Secretary-General of the Permanent Court of Arbitration / Sarah Grimmer -- Arbitrator challenges at the Iran-United States Claims Tribunal / Lee M. Caplan -- Challenges of arbitrators, lessons from the ICC / Loretta Malintoppi and Andrea Carlevaris -- Selection and recusal in the WTO dispute settlement system / Gregory J. Spak and Ron Kendler -- Challenges of judges in international criminal courts and tribunals / Makane Moise Mbengue -- Issue conflicts and the reasonable expectation of an open mind : the challenge decision in Devas v. India and its impact / Romain Zamour -- Late-in-the-day arbitrator challenges and resignations : anecdotes and antidotes / Judith Levine -- Repeat arbitrator appointments in international investment disputes / Luke A. Sobota -- Tall and small tales of a challenged arbitrator / Charles N. Brower, Sarah Melikian and Michael P. Daly -- The approach of counsel to challenges in international disputes / Andrew B. Loewenstein -- Challenges to party representatives and counsel before international courts and tribunals / Hansel T. Pham and M. Imad Khan -- Challenges to arbitrators in Asia : the position before the Singapore and Hong Kong courts / Lucy Reed, John Choong and Chan Yong Wei -- Arbitrators challenges in Latin America / Jonathan Hamilton, Francisco X. Jijon and Ernesto E. Corzo.1 online resource (xxi, 428 pages)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Commento agli artt. 83, 91, 92, 96, 137, 153, 296, 297, 300, 305, 327, 330, 345, 353 c.p.c., 81 bis disp. att. c.p.c., 56, co. 1 e c. 2, Legge 69/09; 13L e 73R D.p.r. 1115/02
No full textDispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
An Axiomatic Design Approach for Customer Satisfaction through a Lean Start-up Framework
No full textAbstractValue generation and customer satisfaction are the primary goals for those companies which want to be successful and profitable on the global market. Achieving these objectives is key for a middle-long term successful business model. Missing them may eventually lead to the company's failure, and also it might be a very difficult task to accomplish. Due to its strategic importance, the overall business model, along with the products and services to be delivered, should be assessed iteratively, defining their importance in respect with the customer needs and expectations. This control check is often experience-based rather than rationally guided, even in large and structured organizations. This paper proposes a novel approach to systemically build a customer development model, to verify the agreement between what is offered and the customer needs. The proposed customer model is built through the Axiomatic Design method, together with other tools that are properly tuned for this specific application
Frictional behavior of talc-calcite mixtures
No full textFaults involving phyllosilicates appear weak when compared to the laboratory-derived strength of most crustal rocks. Among phyllosilicates, talc, with very low friction, is one of the weakest minerals involved in various tectonic settings. As the presence of talc has been recently documented in carbonate faults, we performed laboratory friction experiments to better constrain how various amounts of talc
could alter these fault’s frictional properties. We used a biaxial apparatus to systematically shear different mixtures of talc and calcite as powdered gouge at room temperature, normal stresses up to 50 MPa and under different pore fluid saturated conditions, i.e., CaCO3-equilibrated water and silicone oil. We performed slide-hold-slide tests, 1–3000 s, to measure the amount of frictional healing and velocity-stepping tests, 0.1–1000 μm/s, to evaluate frictional stability. We then analyzed microstructures developed during our experiments. Our results show that with the addition of 20% talc the calcite gouge undergoes a 70% reduction in steady state frictional strength, a complete reduction of frictional healing and a transition from velocity-weakening to velocity-strengthening behavior. Microstructural analysis shows that with increasing talc content, deformation mechanisms evolve from distributed cataclastic flow of the granular calcite to localized sliding along talc-rich shear planes, resulting in a fully interconnected network of talc lamellae from 20% talc onward. Our observations indicate that in faults where talc and calcite are present, a low concentration of talc is enough to strongly modify the gouge’s frictional properties and specifically to weaken the fault, reduce its ability to sustain future stress drops, and stabilize slip
X-ray absorption spectroscopy and electrochemistry on biological samples
No full textIn order to study metalloproteins, which change the metal oxidation states during the catalytic cycle, we have developed an electrochemical cell for in situ XAS measurement on biological samples. To be able to use proteins and mutants that are usually available in small quantities the cell was designed to minimise: a) cavity of RVC working electrode and b) cavities for electric contact between RVC working electrode and the other electrodes (counter and reference). The sample volume of 0.4 ml is sufficient for measurements at several applied potentials. We have investigated the reduction of (a) the hydroxocobalamin (from Co(III) to Co(I)) and (b) microperoxidase (from Fe(III) to Fe(II)). We have then determined the correct energy shift of XANES in the two systems. In the case of hydroxocobalamin, reduction from Co(III) to Co(II) produces the most significant structural changes (Giorgetti et al. 1997) The reduction from Co(II) to Co(I) produces mainly electronic effects with no apparent change of the coordination number. Microperoxidase XANES spectrum shifts by 1 eV ±0.5 eV upon oxidation
Coexistence region analysis in cognitive radio networks
No full textWe consider the coexistence between a primary
user (PU) communication and cognitive users (CUs) in realistic
propagation environments characterized by path loss, log-normal
shadowing, and Rayleigh fading. The scenarios considered envisage two situations: the first with one CU, the second with a
cognitive radio network (CRN), composed of several CUs. In the
latter scenario, to account for the spatial distribution of nodes
the CUs are assumed spatially distributed according to a Poisson
point process. In both scenarios, we characterize the statistical
distribution of the interference and, based on this, we evaluate
the outage probability of the PU communication. The outage
probability will then provide the required minimum radius inside
which CUs communication must not be allowed, to prevent PU
outage. Such minimum radius identifies a disk called exclusion
region (ER), and its complement called coexistence region. The
analytical framework developed, which shows the relationship
between the PU outage probability, the ER, and other system
parameters, is helpful for the network designer to understand
interference effects and to enable coexistence
A track-before-detect algorithm for UWB radar sensor networks
No full textPrecise localization and tracking of moving non-collaborative persons and objects using a network of ultra-wideband (UWB) radar nodes has been shown to represent a practical and effective approach. In UWB radar sensor networks (RSNs), existence of strong clutter, weak target echoes, and closely spaced targets are obstacles to achieving a satisfactory tracking performance. Using a track-before-detect (TBD) approach, the waveform obtained by each node during a time period are jointly processed. Both spatial information and temporal relationship between measurements are exploited in generating all possible candidate trajectories and only the best trajectories are selected as the outcome. The effectiveness of the developed TBD technique for UWB RSNs is confirmed by numerical simulations and by two experimental results, both carried out with actual UWB signals. In the first experiment, a human target is tracked by a monostatic radar network with an average localization error of 41.9 cm with no false alarm trajectory in a cluttered outdoor environment. In the second experiment, two targets are detected by a multistatic radar network with localization errors of 25.4 cm and 19.7 cm, a detection rate of the two targets of 88.75%, and no false alarm trajectory
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