1,721,118 research outputs found
La navigation dans l'Égypte antique
No full textCarlini A., Vivielle Jean-Baptiste Adolphe. La navigation dans l'Égypte antique. In: Journal des savants, Novembre 1927. pp. 385-393
Cimiteri nella natura, come natura, come città. Cemeteries in nature, as nature, as a city.
No full textCimiteri nella natura, come natura, come città.
I luoghi di sepoltura sono destinati a diffondere e proteggere il sentimento di lutto legato alla perdita e ad indicarne, attraverso una rappresentazione simbolica, una via possibile di consolazione e di un sereno ricordo, essi sono testimoni delle diverse identità culturali e religiose: la memoria custodisce e rassicura.
Il tema continua a segnare la nostra esistenza: le immagini delle città ci raccontano ancora di luoghi destinati al ricordo; essi testimoniano anche l’incapacità della nostra cultura di ri-comporre un dialogo consapevole con la morte.
Le trasformazioni sociali in atto ci impongono una riflessione sui luoghi di sepoltura: c'è urgenza di nuove spazialità destinate a rappresentare il luogo della comprensione e del dialogo religioso e civile tra le diverse forme di spiritualità
On the Synthesis of Cams with Roller or Irregular Followers
No full textThe paper extends the theory for plate cam geometry design for regular and irregular-surface follower system. Analytical description of cam profiles for general cam-follower system is obtained using the envelope theory. Usually during the analysis of cam geometry, it is common consider cam as the fixed member and to define the cam surface as envelope curve formed by inverting the follower from the initial position of the cam. The analytical description of cam geometry is show to be a non linear algebraic equation. This analytical approach constitutes a single variable, single nonlinear algebraic equation problem which may be avoided only for roller follower systems. On the other cases the problem can be solved by any reliable nonlinear equation solver.
The results of the examples demonstrated in this paper show that the cam geometry can be significantly changed by choosing different types of follower for the same required motion. It is common to identify radius of curvature along the cam profile as fundamental parameter for cam design. Starting from the analytical description of the radius of curvature of cam profile, an algebraic relation between radius of curvature of cam, system geometry, cam revolution speed and follower position, velocity and acceleration is derived. This relation makes possible to obtain follower acceleration as function of the radius of curvature of cam. This relation can be used during follower motion design as control tool on radius of curvature of cam. Also, it can be used as comparison tool between different follower profiles or mechanisms geometry. Some examples are reported.
For practical engineering design, this implies that the geometry of cams can be adjusted by selecting the follower profile so as to satisfy the design requirements. The development of this geometric analysis tool enables the search for optimal geometric design of general follower cam system
Ellipses and Ovals in the Physical Space of St Peter’s Square in Rome
No full textWe discuss the spatial and perceptive implications of the geometry at urban scale of St. Peter’s square in Rome. The case study of Bernini's project for the colonnade makes explicit the relation between the geometry of the plan and the spatial development. We will show that the geometry of the circle affects intentionally the perception of the walking visitor. There is an ambiguity of use between the terms ellipse and oval, especially in touristic literature and some school textbooks. The specific mathematical properties, of one curve respect to the other, were well known at the time and were obviously intentionally exploited in the design of the square along with the colonnade. We also report of a “geometric flash mob”, we organized in occasion of the 2015 European Researcher’s Night
Astratto e materico per una matematica inclusiva. Esperienza di ricerca, didattica e museografia
No full textEsponiamo l'esperienza di un lungo percorso attraverso didattica universitaria, ricerca, elaborazione di lavori degli studenti, e poi mostre internazionali di divulgazione scientifica, didattica nelle scuole, passeggiate scientifiche in città, tutte attraverso un unico tema. Un percorso le cui tappe si sono certamente nutrite una con l'altra; tutte, vertono attorno al tema della ripetizione di pattern grafici in arabeschi o motivi ornamentali ed al suo trattamento matematico, che ha trovato un assetto completo solo agli inizi del Novecento. Ad accompagnare l'immaginario scientifico, una costante attualizzazione dell'uso e del concetto di patrimonio culturale
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