Fluctuations and the Effective Moduli of an Isotropic, Random Aggregate of Identical, Frictionless Spheres

We consider a random aggregate of identical frictionless elastic spheres that has first been subjected to an isotropic compression and then sheared. We assume that the average strain provides a good description of how stress is built up in the initial isotropic compression. However, when calculating the increment in the displacement between a typical pair of contaction particles due to the shearing, we employ force equilibrium for the particles of the pair, assuming that the average strain provides a good approximation for their interactions with their neighbors. The incorporation of these additional degrees of freedom in the displacement of a typical pair relaxes the system, leading to a decrease in the effective moduli of the aggregate. The introduction of simple models for the statistics of the ordinary and conditional averages contributes an additional decrease in moduli. The resulting value of the shear modulus is in far better agreement with that measured in numerical simulations

La religione nei platonici di Cambridge

I platonici di Cambridge sono autori legati da stima e amicizia, ma anche da impegni di studio e di insegnamento a Cambridge: all\u2019Emmanuel College, B. Whichcote (1609-1683), comunemente ritenuto il caposcuola, J. Smith (1616-1652), N. Culverwell (1618-1651), R. Cudworth (1617-1688); al Christ\u2019s College, H. More (1614-1687). Di ispirazione platonica, hanno un atteggiamento molto critico verso l\u2019empirismo baconiano (contro il sapere volto principalmente all\u2019azione rivendicano il valore della contemplazione), il puritanesino (al legalismo religioso e all\u2019arbitrarismo teologico oppongono la religione come interiorit\ue0 e oggettiva moralit\ue0), il meccanicismo cartesiano e il materialismo hobbesiano (li giudicano inadeguati a spiegare il mondo degli esseri viventi e pericolosi in quanto possono aprire la via all\u2019ateismo). Per sensibilit\ue0 e formazione, essi ritengono centrale il tema della religione, sia in se stessa, che nei suoi rapporti con la ragione, con la prassi, con l\u2019antropologia. 1. Religione e ragione. Per i platonici di Cambridge, la religione \ue8 intima comunione con Dio, via del ritorno dell\u2019uomo a Dio. La ragione \ue8 the candle of the Lord, lumen Domini (Whichcote), lume derivato: lumen de lumine, participata similitudo rationis aeternae (Smith). Seguire la ragione \ue8 seguire Dio (Smith), e rifiutare la ragione \ue8 disonorare Dio (Culverwell). La ragione \ue8 vera amica della religione (Smith): \ue8 in grado di confutare l\u2019ateismo e di combattere la superstizione; ha la stessa fonte della religione; \ue8 condizione imprescindibile per la comprensione della rivelazione. Ma la ragione, se \ue8 lumen Domini, non finisce per svalutare la religione? Effettivamente, i platonici di Cambridge, nell\u2019opporsi al fideismo dei puritani, accentuano il valore della ragione, ma lo fanno unicamente in funzione apologetica: la religione \ue8 l\u2019esito pi\uf9 vero della ragione (Whichcote); chi \ue8 guidato dalla religione vive in comunione con la propria ragione (Smith); si pu\uf2 riconoscere Cristo nella natura, nella ragione, come nei doni della grazia (Whichcote). 2. Religione prassi. Per i platonici di Cambridge, la moralit\ue0, gi\ue0 importante per la ragione in ordine alla conoscenza in s\ue9 (l\u2019immoralit\ue0 \ue8 sviante), e soprattutto per la conoscenza di Dio (l\u2019occhio non pu\uf2 contemplare il sole se non \ue8 simile al sole (Smith)), \ue8 essenziale per la religione, che ha come fine la deificazione (th\ue9osis) dell\u2019uomo, la sua assimilazione a Dio attraverso l\u2019esercizio delle virt\uf9, l\u2019adesione attiva al volere divino, l\u2019imitazione di Cristo, modello di santit\ue0. 3. Religione e antropologia. Per i platonici di Cambridge, la ragione \ue8 in certo modo \uabreligiosa\ubb, in quanto vinculum Dei et hominis (Smith). Ma se \ue8 cos\uec, la religione \ue8 naturale, strutturale nell\u2019uomo in quanto essere razionale, per cui la definizione di animal rationale pu\uf2, deve, essere sostituita da animal capax religionis. Niente infatti \ue8 specifico dell\u2019uomo quanto la capacit\ue0 di religione (Whichcote): immagine di Dio, in relazione ontologica e spirituale con Dio, l\u2019uomo \ue8 costitutivamente religioso. Di qui: l\u2019ateismo \ue8 contro ragione e contro natura, \ue8 non liberazione ma alienazione dell\u2019uomo; se Dio non esistesse, niente di peggio della religione (More). I platonici di Cambridge, con le loro posizioni forse hanno favorito dei processi che hanno portato, ad esempio, al razionalismo teologico di Toland o alla dissoluzione della teologia nell\u2019antropologia in Feuerbach: esiti, per la verit\ue0, impropri e non voluti. Ben altri i loro meriti nella storia della filosofia: l\u2019aver conservato una tradizione \uabclassica\ubb di pensiero (platonismo, neoplatonismo, patristica), l\u2019aver dato l\u2019avvio per qualche verso alla \uabfilosofia della religione\ubb, l\u2019aver trattato problemi di sicuro interesse speculativo ed esistenziale

Contact anisotropy and coordination number for a granular assembly:a comparison between DEM simulation and theory

We study an ideal granular aggregate consisting of elastic spherical particles, isotropic in stress and anisotropic in the contact network. Because of the contact anisotropy, a confining pressure applied at zero deviatoric stress, produces shear strain as well as volume strain. Our goal is to predict the coordination number k, the average number of contacts per particle, and the magnitude of the contact anisotropy ɛ, from knowledge of the elastic moduli of the aggregate. We do this through a theoretical model based upon the well known effective medium theory. However, rather than focusing on the moduli, we consider their ratios over the moduli of an equivalent isotropic state. We observe good agreement between numerical simulation and theory

Trascendentalità e ragione argomentativa

This paper is a critical examination of Apel’s and Habermas’ models of human communication. Common to both philosophers is the stress on the relation between normative and empirical aspects of ethics. Although this relation is necessary in every ethical-oriented communication, the author shows that both in Apel and in Habermas it rests rather on a rational procedure stemming from relevant but limited fields - e.g. jurisprudence - than on an ethics of communication of our being in the world

The Speculum phisionomie by Michele Savonarola

The relevance of the environment of the late medieval and Renaissance court, not only as a social and political context but also as an important hermeneutic criterion, is central for the understanding of a number of fifteenth-century scientific-philosophical texts. This central significance of the court environment is especially evident from the perspective of an examination of both speculative and practical results of developments in physiognomy during this period that are reflected in Michele Savonarola’s Speculum phisionomie (1442)

Baroque Chamber Music Concert, December 2, 2014

This is the concert program of the Baroque Chamber Music Concert performance on Tuesday, December 2, 2014 at 6:30 p.m., at Robinson Chapel, 735 Commonwealth Avenue, Boston, Massachusetts. Works performed were Première leçon ténèbre by François Couperin, Sonata No. 2 for Horn and Cello by Frederic Duvernoy, Second Concert by François Couperin, Two Madrigals by Claudio Monteverdi, Fulgebunt justi by Jean de Castro, Sonata in E minor by Georg Philipp Telemann, Cantata, Orphée by Louis-Nicolas Clérambault, Treizème concert by François Couperin, Cantata, Dolce pur d'amor affano by George Frideric Handel, and Scene from L'Incoronazione di Poppea by Claudio Monteverdi. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund

The Influence of Road Gradient in an Integrated Approach of Real Driving Cycles and Emissions Factors Model

Abstract Transport activities contribute significantly to the air pollution and its impact on emissions is a key element in the evaluation of any transport policy or plan. Calculation of emissions has therefore gained institutional importance in the European Community. Recently, the scientific community has assessed evidence that exposure to outdoor air pollution causes lung cancer and increases the risk of bladder cancer. Because air pollution in urban areas is mainly caused by transportation, it is necessary to evaluate pollutant exhaust emissions from vehicles during their real-world use. Nevertheless their evaluation and reduction is a key problem, especially in the cities, that account for more than 50% of world population. To obtain emission factors several methods make use only of vehicle mean velocity, which can be easily obtained by vehicle flow and density in the road. Among them it is worth mentioning COPERT IV, MOBILE, INFRAS, MEET models that are widely used in the practice. In ARTEMIS FP project, a new statistical approach has been developed capable to consider more attributes than the simple mean speed to characterize driving behaviour, not only in the determination of driving cycles but also in the emission modelling. In this context, a meso scale emission model, named KEM, Kinematic Emission Model, able to calculate emission factor was developed. However, it is necessary to consider that the input to this model is, in any case, the driving cycle, and that to develop a quantitative method capable to determine the exact mix of driving cycle, on the basis of road characteristics and traffic management rules, results a very hard job. In addition a particular attention could be given to the slope variability along the streets during each journey performed by the instrumented vehicle. So in this paper we try to develop a second version of KEM model that dealt with the problem of describing and introducing same variables relative to road gradient variability in a quantitatively way. In the context of correlation study between driving cycles/emission/geographical location, we have to solve some problems for the reconstruction of GPS coordinates and altitude, during an experimental campaign realized with an instrumented car

Micromechanical study of elastic moduli of loose granular materials

In micromechanics of the elastic behaviour of granular materials, the macro-scale continuum elastic moduli are expressed in terms of micro-scale parameters, such as coordination number (the average number of contacts per particle) and interparticle contact stiffnesses in normal and tangential directions. It is well-known that mean-field theory gives inaccurate micromechanical predictions of the elastic moduli, especially for loose systems with low coordination number. Improved predictions of the moduli are obtained here for loose two-dimensional, isotropic assemblies. This is achieved by determining approximate displacement and rotation fields from the force and moment equilibrium conditions for small sub-assemblies of various sizes. It is assumed that the outer particles of these sub-assemblies move according to the mean field. From the particle displacement and rotation fields thus obtained, approximate elastic moduli are determined. The resulting predictions are compared with the true moduli, as determined from the discrete element method simulations for low coordination numbers and for various values of the tangential stiffness (at fixed value of the normal stiffness). Using this approach, accurate predictions of the moduli are obtained, especially when larger sub-assemblies are considered. As a step towards an analytical formulation of the present approach, it is investigated whether it is possible to replace the local contact stiffness matrices by a suitable average stiffness matrix. It is found that this generally leads to a deterioration of the accuracy of the predictions. Many micromechanical studies predict that the macroscopic bulk modulus is hardly influenced by the value of the tangential stiffness. It is shown here from the discrete element method simulations of hydrostatic compression that for loose systems, the bulk modulus strongly depends on the stiffness ratio for small stiffness ratios

Dante's Understanding of the Two Ends of Human Desire and the Relationship between Philosophy and Theology

I discuss Dante’s understanding that human existence is “ordered by two final goals” and how this understanding defines philosophy’s and theology’s respective scopes of authority in guiding human conduct. I show that, while Dante devalues the philosophical authority associated with the traditional Aristotelian emphasis on the significance of contemplative activity, he does so in order to highlight philosophy’s ethico-political authority to guide human conduct toward its “earthly beatitude.” Moreover, I argue that, although Dante subordinates earthly beatitude to spiritual beatitude, he nonetheless maintains that philosophy’s authority to reveal a path to spiritual beatitude requires its fundamental independence from theology