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Search Results: 1 - 10 of 190039 matches for " G. Meneghetti "
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Utilizzo della tensione di picco per la verifica a fatica dei giunti saldati d’angolo con il metodo degli elementi finiti
G. Meneghetti
Frattura ed Integrità Strutturale , 2009,
Abstract: In questo lavoro viene applicato il metodo della tensione di picco per l’analisi della resistenza a fatica di giunti saldati con cordone d’angolo limitatamente al caso di rottura al piede del cordone di saldatura. Il metodo è un’applicazione ingegneristica dell’approccio locale basato sul fattore di intensificazione delle tensioni per intagli (Notch-Stress Intensity Factor, N-SIF) di modo I, che assimila il profilo del piede del cordone di saldatura ad un intaglio a V con raggio di raccordo pari a zero. Inoltre si basa sull’utilizzo della tensione di picco singolare calcolata al piede del cordone mediante un’analisi agli elementi finiti lineare elastica con elementi aventi una prefissata dimensione, assunta pari a 1 mm in questo lavoro. La relativa semplicità di utilizzo e la robustezza del metodo lo rendono adatto all’applicazione in ambito industriale.
Analysis of the fatigue strength under two load levels of a stainless steel based on energy dissipation
B. Atzori,G. Meneghetti,M. Ricotta
Frattura ed Integrità Strutturale , 2011,
Abstract: In this paper the fatigue behaviour of a stainless steel AISI 304L is analysed. In the first part of the work the results obtained under constant amplitude fatigue are presented and synthesised in terms of both stress amplitude and energy released to the surroundings as heat by a unit volume of material per cycle, Q. Then some specimens have been fatigued in variable amplitude, two different load level tests: the first level was set higher while the second was lower than the constant amplitude fatigue limit. The Q values, evaluated during the second part of the fatigue test, have been compared with those calculated under constant amplitude fatigue at the same load level. The comparison allowed us to notice that the Q parameter is sensitive to the fatigue damage accumulated by the material during the first part of the fatigue test.
Resistenza a fatica di strutture in leghe di alluminio: normative a confronto e verifica sperimentale
B. Atzori,G. Meneghetti,B. Rossi
Frattura ed Integrità Strutturale , 2009,
Abstract: Le problematiche relative all’utilizzo delle normative nell’ambito della progettazione a fatica di strutture in leghe di alluminio sono state di recente affrontate in numerosi lavori che hanno messo in luce sia le difficoltà legate al passaggio da normative oramai obsolete ad altre di nuova concezione, ma di caratteristiche e struttura completamente diverse, che la sostanziale carenza anche all’interno delle più recenti normative europee, quale l’Eurocodice 9, di molti risultati e metodi sviluppati in anni di ricerca scientifica e ormai indiscutibilmente consolidati. Il presente lavoro si propone di approfondire entrambe le tematiche tramite il confronto tra risultati sperimentali tratti da letteratura e le corrispondenti curve di resistenza proposte rispettivamente dalla normativa italiana UNI 8634, di recente ritirata, e dall’Eurocodice 9. In questo modo verranno messe in luce le differenze tra i valori di resistenza proposti dalle due norme e verrà illustrata sia la corrispondenza a volte poco soddisfacente con i risultati sperimentali che le conseguenze dovute alla mancata applicazione di assodati risultati teorici.
Analysis of the fatigue strength under two load levels of a stainless steel based on energy dissipation
Atzori B.,Meneghetti G.,Ricotta M.
EPJ Web of Conferences , 2010, DOI: 10.1051/epjconf/20100638009
Abstract: In this paper the fatigue behaviour of a stainless steel AISI 304L is analysed. In the first part of the work the results obtained under constant amplitude fatigue are presented and synthesised in terms of both stress amplitude and energy released to the surroundings as heat by a unit volume of material per cycle, Q. Then some specimens have been fatigued in variable amplitude, two different load level tests: the first level was set higher while the second was lower than the constant amplitude fatigue limit. The Q values, evaluated during the second part of the fatigue test, have been compared with those calculated under constant amplitude fatigue at the same load level. The comparison allowed us to notice that the Q parameter is sensitive to the fatigue damage accumulated by the material during the first part of the fatigue test.
Strong lensing in the MareNostrum Universe II: scaling relations and optical depths
C. Fedeli,M. Meneghetti,S. Gottloeber,G. Yepes
Physics , 2010, DOI: 10.1051/0004-6361/201014962
Abstract: The strong lensing events that are observed in compact clusters of galaxies can, both statistically and individually, return important clues about the structural properties of the most massive structures in the Universe. Substantial work is ongoing in order to understand the degree of similarity between the lensing cluster population and the population of clusters as a whole, with members of the former being likely more massive, compact, and substructured than members of the latter. In this work we exploit synthetic clusters extracted from the {\sc MareNostrum Universe} cosmological simulation in order to estimate the correlation between the strong lensing efficiency and other bulk properties of lensing clusters, such as the virial mass and the bolometric X-ray luminosity. We found that a positive correlation exist between all these quantities, with the substantial scatter being smaller for the luminosity-cross section relation. We additionally used the relation between the lensing efficiency and the virial mass in order to construct a synthetic optical depth that agrees well with the true one, while being extremely faster to be evaluated. We finally estimated what fraction of the total giant arc abundance is recovered when galaxy clusters are selected according to their dynamical activity or their X-ray luminosity. Our results show that there is a high probability for high-redshift strong lensing clusters to be substantially far away from dynamical equilibrium, and that $30-40\%$ of the total amount of giant arcs are lost if looking only at very X-ray luminous objects.
The Intuitive and the Logical in the Mathematical Knowledge: analysis of a pedagogical proposal from a viewpoint of new philosophical approaches and in the educational context of mathematics O Intuitivo e o Lógico no Conhecimento Matemático: análise de uma proposta pedagógica em rela o a abordagens filosóficas atuais e ao contexto educacional da matemática
Renata Meneghetti
Bolema: Boletim de Educa??o Matemática , 2009,
Abstract: In this paper we consider the Meneghetti & Bicudo’s proposal (2003) about the constitution of the mathematical knowledge and analyze it with respect to the following two focuses: under the conceptions of the mathematical knowledge after the mathematical fundamentalist crises and in the educational context of mathematics. The investigation of the first focus is done analyzing news claims to the mathematical philosophy. The investigation of the second focus is done firstly by a theoretical reflection and, soon after that, by focalizing the implementation of the proposal in the process of development of the didactic materials to teaching and learning of Mathematics. Finally, we present the main results of the application of one of those materials. Keywords: Mathematical Knowledge. Intuitive Aspect. Logical Aspect. Philosophy of Mathematics. Mathematics Education. Pedagogical Proposal. Este trabalho tem por objetivo retomar a proposta apresentada em Meneghetti & Bicudo (2003), referente à constitui o do saber matemático, e analisá-la sob dois enfoques: em rela o às concep es de conhecimento matemático após crise fundamentalista da matemática e ao contexto educacional da matemática. A investiga o do primeiro enfoque foi feita analisando atuais reivindica es para a filosófica da matemática e a do segundo se deu, primeiramente, por meio de uma reflex o teórica e, em seguida, focalizando a implementa o da proposta no processo de elabora o de materiais didáticos para o ensino e aprendizagem da matemática. Finaliza-se a pesquisa apresentado os principais resultados da aplica o de um desses materiais. Palavras-chave: Conhecimento Matemático. Aspecto Intuitivo. Aspecto Lógico. Filosofia da Matemática. Educa o Matemática. Proposta Pedagógica.
Dynamic modulation of electron correlation by intramolecular modes in charge transfer compounds
M. Meneghetti
Physics , 1999, DOI: 10.1103/PhysRevB.60.15472
Abstract: Electron-phonon and electron-electron interactions are in competition in determining the properties of molecular charge transfer conductors and superconductors. The direct influence of phonons on the electron-electron interaction was not before considered and in the present work the coupling of intramolecular modes to electron-electron interaction (U-vib interaction) is investigated.The effect of this coupling on the frequency of the normal modes of a dimer model is obtained and it is shown that frequency shifts of the Raman active modes are directly related to this coupling. The results are used to obtain the values of the U-vib coupling constants of intramolecular modes of a representative molecule of charge transfer conductors, like tetramethyltetratiafulvalene. Consequences of this coupling on the electron pairing are also suggested.
Mineral composition and growth of babycorn under swine wastewater combined with chemical fertilization Composi o mineral e crescimento do minimilho sob água residuária de suinocultura combinada com aduba o química
Adriana M. Meneghetti,Lúcia H. P. Nóbrega,Silvio C. Sampaio,Rafael G. Ferques
Revista Brasileira de Engenharia Agrícola e Ambiental , 2012, DOI: 10.1590/s1415-43662012001100008
Abstract: The objective of this study was to evaluate the application of wastewater from swine manure (ARS) and chemical fertilization on foliar concentrations of macronutrients and micronutrients, and its relationship with the growth of babycorn. An experiment was conducted in completely randomized design with eight treatments and three replications in 4 x 2 factorial arrangement, which consisted of the application of four doses of swine wastewater (0, 40, 80 and 120 kg N ha-1) and two levels of chemical fertilization (0 and 40 kg ha-1). The results indicated that the increase in fertilization using swine wastewater manure resulted in significant differences for babycorn's foliar concentrations of N and P, promoting levels below the adequate for N and K, appropriate levels of Cu, Zn, Mn and Fe, and levels above the adequate for P, Ca, Mg and S. For growth variables, results indicated significant differences and the increased use of fertilizer with swine wastewater promoted higher plant height, leaf area, leaf area index, number of leaves per plant and absolute growth rate. Objetivou-se, com este trabalho, avaliar a aplica o de águas residuárias de suinocultura (ARS) e aduba o química sobre os teores foliares de macronutrientes e micronutrientes e sua rela o com o crescimento do minimilho. Conduziu-se um experimento em delineamento inteiramente casualizado, com oito tratamentos e três repeti es dispostos em esquema fatorial 4 x 2, os quais consistiram da aplica o de quatro doses de água residuária de suinocultura (0, 40, 80 e 120 kg ha-1 de N) e duas doses de aduba o química (0 e 40 kg ha-1). Os resultados indicaram que o incremento na aduba o com uso de águas residuárias de suinocultura favoreceu diferen as significativas para as concentra es foliares no minimilho para N e P, proporcionou teores abaixo dos adequados para N e K, teores adequados de Cu, Zn, Mn e Fe e teores acima dos adequados para P, Ca, Mg e S. Para as variáveis de crescimento os resultados indicaram que houve diferen as significativas e que o incremento da aduba o com uso de ARS proporcionou maiores estaturas de plantas, área foliar, índice de área foliar, número de folhas por planta e taxa de crescimento absoluto.
Comparison of an X-ray selected sample of massive lensing clusters with the MareNostrum Universe LCDM simulation
M. Meneghetti,C. Fedeli,A. Zitrin,M. Bartelmann,T. Broadhurst,S. Gottloeber,L. Moscardini,G. Yepes
Physics , 2011, DOI: 10.1051/0004-6361/201016040
Abstract: A long-standing problem of strong lensing by galaxy clusters regards the observed high rate of giant gravitational arcs as compared to the predictions in the framework of the "standard" cosmological model. Recently, few other inconsistencies between theoretical expectations and observations have been claimed which regard the large size of the Einstein rings and the high concentrations of few clusters with strong lensing features. All of these problems consistently indicate that observed galaxy clusters may be gravitational lenses stronger than expected. We use clusters extracted from the MareNostrum Universe to build up mock catalogs of galaxy clusters selected through their X-ray flux. We use these objects to estimate the probability distributions of lensing cross sections, Einstein rings, and concentrations for the sample of 12 MACS clusters at $z>0.5$ presented in Ebeling et al. (2007) and discussed in Zitrin et al. (2010). We find that simulated clusters produce $\sim 50%$ less arcs than observed clusters do. The medians of the distributions of the Einstein ring sizes differ by $\sim 25%$ between simulations and observations. We estimate that, due to cluster triaxiality and orientation biases affecting the lenses with the largest cross sections, the concentrations of the individual MACS clusters inferred from the lensing analysis should be up to a factor of $\sim 2$ larger than expected from the $\Lambda$CDM model. The arc statistics, the Einstein ring, and the concentration problems in strong lensing clusters are mitigated but not solved on the basis of our analysis. Nevertheless, due to the lack of redshifts for most of the multiple image systems used for modeling the MACS clusters, the results of this work will need to be verified with additional data. The upcoming CLASH program will provide an ideal sample for extending our comparison (abridged).
Pragmatismo e os pragmáticos nos estudos organizacionais
Meneghetti, Francis Kanashiro;
Cadernos EBAPE.BR , 2007, DOI: 10.1590/S1679-39512007000100005
Abstract: the main objective of this theoretical essay is to analyze the main contributions that pragmatism has offered toorganizational studies and, more specifically, evaluate whether the theoretical contributions by such philosophers as charles pierce and john dewey allow us to regard pragmatism as common sense, science, or theoryof knowledge. this paper also examines the contributions - possibilities and limitations - of pragmatism as scientific knowledge in order to understand the path of pragmatism in organizational studies. the likely conclusion is that to be pragmatic is not to conceive of studies articulated in the epistemological field of pragmatism. the pragmatic individual sees in the usefulness and in the need for action the tension point that casts a doubt in the veracity of the assumptions of pragmatism as a science. what takes place in organizational studies is the conversion of pragmatism as scientific knowledge into irrational subordination to function and practical action, mainly in the fields of economy, politics, science, culture, education, and so on.
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