Sigillo di Ateneo


Inglese
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Pagina personale di Marco MAIOLI

Dipartimento di Scienze Fisiche, Informatiche e Matematiche
Dipartimento di Scienze Fisiche, Informatiche e Matematiche sede ex-Matematica

D.N. Boccaccini, M. Maioli, M. Cannio, I. Dlouhy, M. Romagnoli, C. Leonelli, A.R. Boccaccini ( 2012 ) - A lifetime prediction method based on Cumulative Flaw Length Theory - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 32[6] - pp. da 1175 a 1186 ISSN: 0955-2219 [Articolo su rivista - Articolo su rivista]
Abstract

Ultrasonic pulse velocity testing (UPVT) was carried out to perform non-destructive quality control of refractory plates. Used in conjunction with fracture mechanics, ultrasonic velocity measurements have proved a powerful technique for detecting, positioning and sizing internal voids and cracks in the samples, originated from the manufacturing process. Two cordierite-mullite refractory compositions exhibiting different microstructure and crack propagation behaviour were characterized through their lifetime during which they were subjected to thermal shock loading. In this paper, a new statistical method is proposed which allows to estimate the lifetime when the stress state that will be applied in service (loading) and the scattering of the ultrasonic velocity data in the as-received state are known. Since this lifetime prediction method is based on a non-destructive technique, it could be implemented into a code in an automatic quality control device for continuous lifetime estimation. The correlation between crack propagation behaviour and thermal shock resistance is discussed and semi-empirical models were developed to predict the service life of refractory plates from the measured values of ultrasonic velocities on as-received samples.

D.N. Boccaccini, M. Maioli, M. Cannio, I. Dlouhy, M. Romagnoli, C. Leonelli, A.R. Boccaccini ( 2011 ) - A lifetime prediction method based on Cumulative Flaw Length Theory - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 32(6) - pp. da 1175 a 1186 ISSN: 0955-2219 [Articolo su rivista - Articolo su rivista]
Abstract

Ultrasonic pulse velocity testing (UPVT) was carried out to perform non-destructive quality control of refractory plates. Used in conjunction with fracture mechanics, ultrasonic velocity measurements have proved a powerful technique for detecting, positioning and sizing internal voids and cracks in the samples, originated from the manufacturing process. Two cordierite-mullite refractory compositions exhibiting different microstructure and crack propagation behaviour were characterized through their lifetime during which they were subjected to thermal shock loading. In this paper, a new statistical method is proposed which allows to estimate the lifetime when the stress state that will be applied in service (loading) and the scattering of the ultrasonic velocity data in the as-received state are known. Since this lifetime prediction method is based on a non-destructive technique, it could be implemented into a code in an automatic quality control device for continuous lifetime estimation. The correlation between crack propagation behaviour and thermal shock resistance is discussed and semi-empirical models were developed to predict the service life of refractory plates from the measured values of ultrasonic velocities on as-received samples.

Vincenzo Grecchi, Marco Maioli, Andre' Martinez ( 2010 ) - The top resonances of the cubic oscillator - JOURNAL OF PHYSICS. A, MATHEMATICAL AND THEORETICAL - n. volume 43 - pp. da 474027 ISSN: 1751-8121 [Articolo su rivista - Articolo su rivista]
Abstract

We study the top resonance states of the cubic anharmonic oscillator H(\beta)= p^2+x^2+i\sqrt{\beta}x^3 for \beta on the complexplane cut along the negative semiaxis. In particular, by the semiclassical scaling and semiclassical methods, we prove that the top resonance states do not belong to to L^2(R).

D.N. Boccaccini, M. Maioli, M. Cannio, M. Romagnoli, P. Veronesi, C. Leonelli, A.R. Boccaccini ( 2009 ) - A statistical approach for the assessment of reliability in ceramic materials from ultrasonic velocity measurement: Cumulative Flaw Length Theory - ENGINEERING FRACTURE MECHANICS - n. volume 76 - pp. da 1750 a 1759 ISSN: 0013-7944 [Articolo su rivista - Articolo su rivista]
Abstract

A primary objective of statistical fracture approach is to predict the probability of failure of a component for an arbitrary stress state when the failure statistics are known. This study introduces the fundamentals and application of a new approach to characterize the mechanical behaviour of high temperature ceramic materials, including refractory materials, by coupling non-destructive methods, in particular ultrasonic velocity measurement, and the Batdorf statistical fracture theory. A new approach, termed Cumulative Flaw Length Theory (CFLT), has been developed for the case of macroscopically homogeneous isotropic materials containing randomly oriented microcracks uniformly distributed in a location subjected to non-uniform multiaxial stresses. A function representing the number of cracks per unit volume is estimated based on the histograms of ultrasonic velocity measurements. This function is used without additional assumptions to determine the probability of fracture under an arbitrary stress condition. Two different cordierite-mullite high temperature ceramic materials were characterized under the assumptions of this theory to provide experimental evidence to support the model.

Vincenzo Grecchi, Marco Maioli, Andre' Martinez ( 2009 ) - Pade' summability of the cubic oscillator - JOURNAL OF PHYSICS. A, MATHEMATICAL AND THEORETICAL - n. volume 42 - pp. da 425208 a 425224 ISSN: 1751-8113 [Articolo su rivista - Articolo su rivista]
Abstract

We prove the Pade (Stieltjes) summability of the perturbation series of anyenergy level En,1(β), n \in N, of the cubic anharmonic oscillator, H1(β) =p^2 +x^2 +i√βx^3, as suggested by the numerical studies of Bender andWeniger.At the same time, we give a simple proof of the positivity of every levelof the PT -symmetric Hamiltonian H1(β) for positive β (Bessis–Zinn Justinconjecture). The n zeros, of a state ψ_n,1(β), stable at β = 0, are confinedfor β on the cut complex plane, and are related to the level En,1(β) by theBohr–Sommerfeld quantization rule (semiclassical phase-integral condition).We also prove the absence of non-perturbative eigenvalues and the simplicityof the spectrum of our Hamiltonians.

Vincenzo Grecchi, Marco Maioli ( 2009 ) - Stability of the molecular structure - ATTI DEL SEMINARIO MATEMATICO E FISICO DEL'UNIVERSITA DI MODENA E REGGIO EMILIA - n. volume 56 - pp. da 47 a 58 ISSN: 1825-1269 [Articolo su rivista - Articolo su rivista]
Abstract

We prove the stability of the molecular structure given by a bidimensional nonlinear model for a stochastic perturbation. In particular, for a small stochastic perturbation, the racemisation effect doesn't happen when during the validity timew of the model

M. MAIOLI; KAROLY MICSKEI; CLAUDIA ZUCCHI; LUCIANO CAGLIOTI; GYULA PALYI ( 2008 ) - Evolution of chirality in consecutive asymmetric autocatalytic reaction cycles - Baltzer Science Publishers BV:PO Box 221, 1400 AE Bussum Netherlands:011 31 35 6954250, EMAIL: publish@baltzer.nl, INTERNET: http://www.baltzer.nl, Fax: 011 31 35 6954258 ) - JOURNAL OF MATHEMATICAL CHEMISTRY - n. volume 43 - pp. da 1505 a 1515 ISSN: 0259-9791 [Articolo su rivista - Articolo su rivista]
Abstract

Closed algebraic formulae were deduced for the description of the quantitative evolution of chirality in consecutive asymmetric autocatalytic reaction cycles. These formulae enable the estimation of the initial enantiometric excesses in the very first cycles of absolute enantioselective syntheses performed by Soai-autocatalysis. The initial (statistical) excesses in the homogeneous variant of the Soai- autocatalysis show normal (Gaussian) distribution, corresponding to the "coin-tossing" model of an achiral-to-chiral transformation.

L Caglioti, B Barabas, F Faglioni, N Florini, P Lazzeretti, M Maioli, K Micskei, K Rabai, F Taddei, C Zucchi, G Palyi, ( 2008 ) - On the track of absolute enantioselective catalysis - CHIMICA OGGI-CHEMISTRY TODAY - n. volume 26 - pp. da 30 a 32 ISSN: 0392-839X [Articolo su rivista - Articolo su rivista]
Abstract

The main goal of this communication is to show the utility of empirical approaches combined with mathematical methods in the research regarding the molecular basis of biological chirality. Preparative results (enantiomeric excesses, e.e.) obtained in asymmetric autocatalysis with (AAC) and without (AES) chiral additive were analyzed. Statistical calculations show, that AES (absolute enantioselective synthesis) experiments yield two independent groups of results with prevalence of the R- or S-enantiomer. These are distributed asymmetrically in a second-order beta distribution. Empirical calculations both on AAC and EAS enable to identify the very low (statistical) e. e.-s amplified by AES. These initial e. e.-s show normal distribution. Possible molecular-level reasons of these results were controlled by quantum chemical MO calculations and compatible mechanism(s) are discussed.

G. Bosi, P. Berti, M. Maioli, F. Costantini, M. Bandini Mazzanti ( 2007 ) - Applicazioni morfobiometriche in campo archeocarpologico: primi dati su Papaver somniferum nell’Alto Medioevo di Ferrara - ATTI DELLA SOCIETÀ DEI NATURALISTI E MATEMATICI DI MODENA - n. volume 137 (2006) - pp. da 373 a 387 ISSN: 0365-7027 [Contributo in Atti di convegno - Relazione in Rivista di Atti di Convegno]
Abstract

Viene presentata la caratterizzazione morfo-biometrica di due campioni archeobotanici di semi di Papaver somniferum L., provenienti dallo scavo archeologico di Corso Porta Reno - Via Vaspergolo (FE), da strati del Periodo II (prima metà XI secolo d.C.), fase con un assetto che rimanda al casale o casale suburbano. I semi del deposito archeologico ferrarese sono molto simili a quelli attuali commerciali, in particolare i semi dell’US 2659, ed hanno caratteri morfobiometrici in accordo con quelli riportati nella letteratura per le forme di P. somniferum subsp. somniferum a seme grande. E’ quindi plausibile che essi possano appartenere a P. somniferum subsp. somniferum, pur tenendo conto della difficoltà di discriminare su basi carpologiche la forma spontanea (P. somniferum subsp. setigerum) da quella che comprende le forme coltivate (P. somniferum subsp. somniferum). I dati archeomorfo-biometrici su questi semi altomedievali di P. somniferum costituiscono un piccolo tassello, che potrà contribuire a comporre la storia del papavero domestico e dei suoi rapporti con l’uomo nel territorio italiano.

B. Barabas, L. Caglioti, F. Faglioni, N. Florini, P. Lazzeretti, M.Maioli, K. Micskei, G. Rabai, F. Taddei, C. Zucchi, G. Palyi ( 2007 ) - On the traces of absolute enantioselective synthesis - COMPUTATION IN MODERN SCIENCE AND ENGINEERING VOL 2, PTS A AND B Book Series: AIP CONFERENCE PROCEEDINGS - AIP CONFERENCE PROCEEDINGS - n. volume 2 - pp. da 1150 a 1152 ISSN: 0094-243X [Abstract su rivista - Abstract in Rivista]
Abstract

The main goal of this communication is to show the utility of empirical approaches combined with mathematical methods in the research regarding the molecular basis of biological chirality. Preparative results (enantiomeric excesses, e.e.) obtained in asymmetric autocatalysis with (AAC) and without (AES) chiral additive were analyzed. Statistical calculations show, that AES (absolute enantioselective synthesis) experiments yield two independent groups of results with prevalence of the R- or S-enantiomer. These are distributed asymmetrically in a second-order beta distribution. Empirical calculations both on AAC and EAS enable to identify the very low (statistical) e.e.-s amplified by AES. These initial e.e.-s show normal distribution. Possible molecular-level reasons of these results were controlled by quantum chemical MO calculations and compatible mechanism(s) are discussed.

D.N.Boccaccini; M. Maioli; M. Cannio; P. Veronesi, M. Romagnoli; C. Leonelli ( 2007 ) - UNATEORIA STATISTICA PER VALUTARE L’AFFIDABILITÀ DI MATERIALI CERAMICI BASATA SU MISURE DI VELOCITÀ ULTRASONICA: CUMULATIVE FLAW LENGTH THEORY - Atti del Convegno IGF XIX Milano 2007 - Gruppo Italiano Frattura Cassino ITA) - pp. da 127 a 133 ISBN: 9788895940250 [Contributo in Atti di convegno - Relazione in Volume di Atti di Convegno]
Abstract

Uno dei principali obiettivi della teoria statistica della frattura è prevedere la probabilità di rottura per uno stress arbitrario, quando è nota la statistica di rottura. E’ stata sviluppata una nuova teoria “Cumulative Flaw Lenght Theory(CFLT)” per il caso di materiali omogenei isotropici a livello macroscopico contenenti microcricche con orientazioni random distribuite uniformemente sotto stress poliassiali. La funzione rappresentante il numero di cricche per unità di volume è basata su istogrammi relativi a misure di velocità ultrasoniche. Questa funzione è usata senza ulteriori assunzioni per determinare la probabilità di rottura in condizioni arbitrarie di stress. Questa teoria può essere facilmente incorporata in un modello a elementi finiti per prevedere la probabilità di rottura di una struttura sottoposta a stress. Inoltre il confronto della teoria con programmi esistenti usati per prevedere la probabilità di rottura di materiali ceramici e che sono basati su parametri determinati mediante prove distruttive, ad es. three point bending strenght, sottolinea il vantaggio di previsionibasate su tecniche non distruttive. Questo fatto ne permette l’impiego non solo in fase di design, ma anche per il monitoraggio dell’aumento di probabilità di rottura durante la vita in servizio. Una certa varietà di fratture introdotte durante le fasi iniziali dei metodi tradizionali di processo può portare a una affidabilità non accettabile dei materiali ceramici impiegati ad alta temperatura. Le impurezze presenti nelle materie prime (polveri, leganti..) e agglomerati formati durante il processo di formatura delle polveri sono esempi di difetti che influenzano la resistenza. Tali fratture non solo limitano la resistenza dei materiali ma incrementano lo scattering dei dati portando a affidabilità bassa (basso modulo di Weibull). La Cumulative Flaw Lenght Theory permette di valutare la funzione densità delle cricche e la probabilità di rottura a partire da dati di misura di velocità a ultrasuoni in materiali ceramici. Un nuovo metodo statistico è proposto che, basato su risultati ottenuti dalla CFLT per i campioni come ricevuti permette di valutare il vita in servizio quando il materiale è sottoposto a stress. Due diversi ceramici refrattari a base di cordierite mullite sono stati caratterizzati nell’assunzione che la teoria fosse validata in campo sperimentale. I modelli empirici di vita in servizio sono stati ottenuti considerando il numero di cicli termici sostenuti/sopportati da un numero di campioni. La buona correlazione ottenuta tra le curve teoriche e le curve ottenute con dati sperimentali mette in risalto la validità del metodo proposto.

BELA BARABAS; LUCIANO CAGLIOTI; CLAUDIA ZUCCHI; M. MAIOLI; KAROLY MICSKEI; GYULA PALYI ( 2007 ) - Violation of Distribution Symmetry in Statistical Evaluation of Absolute Enantioselective Synthesis - JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL - n. volume 111 - pp. da 11506 a 11510 ISSN: 1520-6106 [Articolo su rivista - Articolo su rivista]
Abstract

Enantiometric excesses obtained in absolute enantioselective synthesis by chiral autocatalysis (Soai-reaction) were statistically analyzed. Two sets of parallel experiments, which were performed under chemically different conditions, are available. The former group shows some interesting tendencies, but does not give conclusive statistical results. The sample of 84 parallel experiments, providing 39 R- and 45 S-excesses have shown that these data represent two distinct, non-symmetric sets with different non-Gaussian distributions. Clear S preference was found.

G. Bosi, P. Berti, M. Maioli, S. Santoro, M. Bandini Mazzanti ( 2006 ) - Caratteri morfologici distintivi e biometria di semi di Cucumis melo L. da siti medievali a Ferrara (\ - Riassunti 101° Congresso SBI - Seconda Università degli Studi di Napoli Napoli ITA) - n. volume \ - pp. da 275 a 275 ISBN: NON PRESENTE [Abstract in Atti di convegno - Abstract in Volume di Atti di Convegno ]
Abstract

Caratteri morfologici distintivi e biometria di semi di Cucumis melo L. da siti medievali a Ferrara

Micskei K; Maioli M; Zucchi C; Caglioti L; Palyi G ( 2006 ) - Generalization possibilities of autocatalytic absolute enantioselective synthesis - TETRAHEDRON-ASYMMETRY - n. volume 17 - pp. da 2960 a 2962 ISSN: 0957-4166 [Articolo su rivista - Articolo su rivista]
Abstract

A simple empirical formula enables the quantitative description of chiral autocatalysis. This formula was used for the prediction of the number of consecutive autocatalytic reaction cycles needed to obtain a high enantiomeric excess without chiral auxiliary or an asymmetric physical field (absolute enantioselective synthesis). The results show, that even less selective Soai-type systems can be used for absolute enantioselective synthesis, which, therefore, appears to be a fairly general phenomenon. (c) 2006 Published by Elsevier Ltd.

D. Lodi; M. Maioli; A. Sacchetti ( 2005 ) - Dynamical localization for two-level systems periodically driven - JOURNAL OF PHYSICS. A, MATHEMATICAL AND GENERAL - n. volume 38 [Articolo su rivista - Articolo su rivista]
Abstract

Here, we consider a two-level system driven by an external periodic field. We show that the coherent destruction of tunnelling, as proved by Grossmann and co-workers (1991 Phys. Rev. Lett. 67 516; 1992 Europhys. Lett. 18 571) in the case of a monochromatic field, also appears for any periodic driving field given by an even regular function with zero mean value and satisfying a technical condition on the zeros of this function.

M. Maioli; A. Sacchetti ( 2005 ) - Two level systems driven by a stochastic perturbation - JOURNAL OF STATISTICAL PHYSICS - n. volume 119 - pp. da 1383 a 1396 ISSN: 0022-4715 [Articolo su rivista - Articolo su rivista]
Abstract

Here we consider a two level system driven by an external harmonic field whose amplitude is perturbed by a white noise term. In the limit of small splitting, dynamical localization, i.e. coherent destruction of tunneling, is proved for times of the order of 1/epsilon, where epsilon is the two-level splitting. The same type of localization is proved if the driving field is simply the white noise.

M. Maioli; A. Sacchetti ( 2004 ) - Gevrey formal power series of Wannier-Stark ladders - JOURNAL OF PHYSICS. A, MATHEMATICAL AND GENERAL - n. volume 37 - pp. da 2371 a 2383 ISSN: 0305-4470 [Articolo su rivista - Articolo su rivista]
Abstract

We consider time-independent Schrodinger equations in one dimension with both periodic and Stark potentials. By means of an iterative procedure we obtain a formal power series for the Wannier-Stark ladders. In the case of strongly singular periodic potentials we prove that such a formal power series is of Gevrey type.

E. Franchini; M. Maioli ( 2003 ) - Feynman integrals with point interactions - COMPUTERS & MATHEMATICS WITH APPLICATIONS - n. volume 46 - pp. da 685 a 694 ISSN: 0898-1221 [Articolo su rivista - Articolo su rivista]
Abstract

A Feynman-Kac formula for Schrodinger operators including a one-center point inter action in R-3 plus a bounded potential is proved. Functional integration methods on similar Kac´s averages with point interactions allow us to construct bounded self-adjoint semigroups in L-2(R-3), with bounded below Schrodinger generators, when V+ is an element of L-loc(2) and V- belongs to a large class of L-2 + L-infinity potentials. Moreover, a pointwise bound on the range of the semigroup is given.

E. Franchini, M. Maioli ( 2003 ) - On Feynman integrals with point interactions - COMPUTERS & MATHEMATICS WITH APPLICATIONS - n. volume 46 - pp. da 685 a 694 ISSN: 0097-4943 [Articolo su rivista - Articolo su rivista]
Abstract

A Feynman-Kac formula for Schrodinger operators including a one-center point interaction in R^3 plus a bounded potential is proved. Functional integration methods on similar Kac's averages with point interactions allow us to construct bounded self-adjoint semigroups in L^2(R^3), with bounded below Schrodinger generators, when V^+ \in L_loc^2 and V^- belongs to a large class of L^2 + L^-8 potentials. Moreover, a pointwise bound on the range of the semigroup is given.

Maioli M; Sacchetti A ( 1998 ) - Absence of the absolutely continuous spectrum for Stark-Bloch operators with strongly singular periodic potentials - JOURNAL OF PHYSICS. A, MATHEMATICAL AND GENERAL - n. volume 31 - pp. da 1115 a 1119 ISSN: 0305-4470 [Articolo su rivista - Articolo su rivista]
Abstract

We correct here the proof of the boundedness of the coupling term X given by us in a previous paper (1995 J. Phys. A: Math. Gen. 28 1101-6).

Caliceti E; Grecchi V; Maioli M ( 1996 ) - Double wells: Nevanlinna analyticity, distributional borel sum and asymptotics - COMMUNICATIONS IN MATHEMATICAL PHYSICS - n. volume 176 - pp. da 1 a 22 ISSN: 0010-3616 [Articolo su rivista - Articolo su rivista]
Abstract

We consider the energy levels of a Stark family, in the parameter j, of quartic double wells with perturbation parameter g: H(g, j) = p(2) + x(2)(1 - gx)(2) - j (gx - 1/2). For non-even j (and for the symmetric case j = 0) we prove analyticity in the full Nevanlinna disk Rg(-2) > R(-1) of the g(2)-plane, as predicted by Crutchfield. By means of an approximation we give a heuristic estimate of the asymptotic small g behaviour, showing the relation between the avoided crossings and the failure of the usual perturbation series.

V. GRECCHI; M. MAIOLI; A. SACCHETTI ( 1994 ) - STARK LADDERS OF RESONANCES - WANNIER LADDERS AND PERTURBATION-THEORY - COMMUNICATIONS IN MATHEMATICAL PHYSICS - n. volume 159 - pp. da 605 a 618 ISSN: 0010-3616 [Articolo su rivista - Articolo su rivista]
Abstract

Let H-B be any fixed one-dimensional Bloch Hamiltonian with only the first m gaps open and H-F = H-B + Fx be the corresponding Stark Hamiltonian. For any positive F small enough H-F has only m ladders of sharp resonances given by the analytic translation method, the decoupled band approximation and the regular perturbation theory. This way, the Wannier conjecture becomes a definite regular perturbation theory for the Stark ladders as eigenvalues of the translated Hamiltonian.

GRECCHI V; MAIOLI M; SACCHETTI A ( 1993 ) - WANNIER LADDERS AND PERTURBATION-THEORY - JOURNAL OF PHYSICS. A, MATHEMATICAL AND GENERAL - n. volume 26 [Articolo su rivista - Articolo su rivista]
Abstract

Following Avron we consider the Stark effect for Bloch electrons in the case of a finite number of gaps. We prove that the ladders of resonances are given by the Wannier decoupled-band approximation and the perturbation theory. The Fermi golden rule yields the width behaviour of Buslaev and Dmitrieva.

M. MAIOLI, A. SACCHETTI ( 1992 ) - Strong asymptotic expansion for the exponential anharmonic oscillator - Seminario Matematico e Fisico, Unniversita di Modena ) - ATTI DEL SEMINARIO MATEMATICO E FISICO DELL'UNIVERSITA' DI MODENA - n. volume XL - pp. da 25 a 30 ISSN: 0041-8986 [Articolo su rivista - Articolo su rivista]
Abstract