Search results for "Restitution"
showing 10 items of 50 documents
Analysis of microsphere oblique impact with planar surfaces based on the independent friction-restitution approach
2020
The independent friction restitution closure (IFR) previously applied to describe planar oblique impact of a homogeneous sphere on an infinitely massive rough plane is applied here to microsphere collisions and is extended to describe horizontal launch experiments. The model provides analytical solutions of the motion equations based on a unique set of values of the coefficients of normal and tangential restitution and friction. Comparison with experimental data in literature for the impact of microspheres of diameter <100 mu m yields a satisfactory agreement between experimentation and theory.
Analysis of rolling friction effects on oblique rebound by redefining tangential restitution and friction
2019
The planar oblique impact of a homogeneous sphere on an infinitely massive rough plane is described assuming that normal and tangential restitution mechanisms operate independently of friction, and that frictional effects include not only the usual Coulomb model but also rolling friction effects. This formulation extends early models including rolling friction effects in the description of impact events to include the independent friction restitution closure. The model yields velocity-independent equations for postimpact linear and angular velocities in four impact regimes, namely, sliding plus rolling, sliding nonrolling, stick plus rolling, and stick nonrolling whose predictions are compa…
Independent friction-restitution modeling of two-disk collisions
2021
[EN] The oblique collisions between two axisymmetric disks moving on a flat horizontal surface are described in terms of impact modeling based on the assumption that normal and tangential restitution mechanisms operate independently of friction. Describing these mechanisms in terms of the usual Coulomb formulation, the model allows for an interpretation of some ¿anomalous¿ experimental data reported in the literature. These experimental data, corresponding to the variation of the coefficients of friction and tangential restitution with the impact angle, remained unexplained in classic formulations, are understood within the framework of the independent friction-restitution closure. Experime…
Unjust enrichment e restitution nel quadro delle fonti obbligatorie inglesi
2020
Il lavoro, muovendo dall’intento di trovare il filo conduttore del «law of obligations» inglese ed in particolare delle sue fonti, si occupa dell’evoluzione storica della terza fonte, che si affianca a tort e contract. Essa è stata variamente denominata nel tempo: per un lungo periodo si è utilizzata l’espressione mutuata dalle fonti romane «quasi contract». Solo nel terzo decennio inoltrato del ventesimo secolo, e per merito della dottrina statunitense e dell’omonimo Restatement, si iniziò a parlare di «restitution». Il termine, riferito genericamente alle retrocessioni di ricchezze trasferite in presenza di «unjust factors», iniziò a divenire familiare, anche in giurisprudenza, grazie all…
Traveling material↔semiotic environments of disability, rehabilitation, and physical activity.
2020
In this article, we apply narrative dialogism and new materialism to health research. We examine how material↔semiotic environments (MSEs) affect the rehabilitation process of Patrick, a man who exercised with the aim to recover from spinal cord injury. The MSEs are considered embedded subcases within the overall holistic case of Patrick. Three MSEs were identified: the hospital gym, the personal gym, and the adapted gym. These are examined using the analytical lens of assemblages. First, the mutually affecting components of each MSE are described. Second, a larger environmental assemblage is identified, which is termed exercise-is-restitution assemblage. This composite assemblage illumina…
Riannodare il passato e il presente con la restituzione prospettica: ricostruzione della perduta chiesa delle Stimmate di Palermo da foto d’archivio
2020
La restituzione prospettica appartiene di diritto al corpus disciplinare della geometria descrittiva, come problema inverso della prospettiva. In passato tale tecnica è stata utilizzata ben poche volte per la ricostruzione da immagini fotografiche di architetture e opere d’arte perdute; gli strumenti digitali per la rappresentazione offrono però l’opportunità di recuperare la restituzione prospettica come strumento efficace per la ricostruzione di monumenti perduti ritratti in foto d’epoca. Il caso studio prescelto è la chiesa delle Stimmate di Palermo, demolita alla fine del XIX secolo per la costruzione del Teatro Massimo. La chiesa ad aula era delimitata da pareti con nicchie arcuate poc…
La ricostruzione da immagini con tecniche di restituzione prospettica
2018
Il contributo è incentrato sulla ricostruzione di opere di architettura perdute da fotografie attraverso l’uso di tecniche di restituzione prospettica. Una breve introduzione illustra le ragioni che relegano la restituzione prospettica a un ruolo secondario nel contesto delle ricostruzioni virtuali; il paragrafo successivo illustra i risultati di un test sul confronto fra restituzione prospettica da singolo fotogramma e restituzione SfM. Il paragrafo conclusivo descrive la ricostruzione virtuale di una chiesa di Palermo, demolita nella prima metà del XX secolo e documentata da poche foto d’epoca. The paper focuses the 3D reconstruction of buildings that were destroyed during the World War I…
A 3D reworking of the urban transformations of Palermo in recent history for a hypothesis of a "City Museum" based on digital visualizations
2021
The objective that drives this research is given by a multitude of information which, in addition to the contribution of technology, allows us to study, analyze, verify and remodel the sites, monuments and evolutions of the city through graphic processes of perspective restitution that start from the analysis of historical photos. The drawing methods, the digital graphic rendering and through the aid of geometric techniques, contribute to the reconstruction of projects and architectures that are now lost, this is possible thanks to the methods of perspective, axonometry and three-dimensional restitution. This remarkable photographic heritage belonging to Palermo, but also to any other city …
PERSPECTIVE RESTITUTION FROM VIEW CAMERAS PHOTOS
2022
Abstract. The paper aims at discussing the accuracy of perspective restitution from view camera photos; view cameras are non-standard cameras frequently used in the past century for on field shooting of buildings and urban sites; this is why the reconstruction of lost buildings often deals with photos taken with a view camera. The case study chosen for the proposed experiment is an urban complex built in Palermo in the ‘50s. The site features a very regular layout with surfaces at right angle, that supports the graphic reconstruction of photos’ inner and outer orientation. The site has been surveyed with a laser scanner; the point cloud provided the metric information needed for the evaluat…
Dalla Fotografia alla ricostruzione: Porta Maqueda a Palermo
2022
The reconstruction of gone, or never built buildings has ever been one of the preferred subjects of digital representation. Many researches have focused the reconstruction of buildings that were modified by human actions, as wars or demolitions, or by natural causes as earthquakes or decay. Many buildings, destroyed or reshaped from the second half of the 19th century have been photographed before they vanished; when no drawing or document are available, the memory of the architecture layout of these buildings is entrusted to few period photos. Digital representation makes the reconstruction of gone buildings from period photos possible. Descriptive Geometry provides the conceptual and oper…