Search results for "SHAPE"
showing 10 items of 585 documents
Constraining the magnitude of the Chiral Magnetic Effect with Event Shape Engineering in Pb–Pb collisions at √sNN = 2.76 TeV
2018
In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow v2 reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two- and three-particle correlations in Pb–Pb collisions at sNN=2.76 TeV. The two-particle correlator 〈cos(φα−φβ)〉, calculated for different combinations of charges α and β, is almost independent of v2 (for a given centrality), while the three-particle correlator 〈cos(φα+φβ−2Ψ2)〉 scales almost linearly both with the event v2 and charged-part…
Mixed support for an alignment between phenotypic plasticity and genetic differentiation in damselfly wing shape
2023
The relationship between genetic differentiation and phenotypic plasticity can provide information on whether plasticity generally facilitates or hinders adaptation to environmental change. Here, we studied wing shape variation in a damselfly (Lestes sponsa) across a latitudinal gradient in Europe that differed in time constraints mediated by photoperiod and temperature. We reared damselflies from northern and southern populations in the laboratory using a reciprocal transplant experiment that simulated time-constrained (i.e. northern) and unconstrained (southern) photoperiods and temperatures. After emergence, adult wing shape was analysed using geometric morphometrics. Wings from individu…
Universal natural shapes: From unifying shape description to simple methods for shape analysis and boundary value problems
2012
Gielis curves and surfaces can describe a wide range of natural shapes and they have been used in various studies in biology and physics as descriptive tool. This has stimulated the generalization of widely used computational methods. Here we show that proper normalization of the Levenberg-Marquardt algorithm allows for efficient and robust reconstruction of Gielis curves, including self-intersecting and asymmetric curves, without increasing the overall complexity of the algorithm. Then, we show how complex curves of k-type can be constructed and how solutions to the Dirichlet problem for the Laplace equation on these complex domains can be derived using a semi-Fourier method. In all three …
Recent Progress in FSMA Microactuator Developments
2009
The giant magneto-strain effect is particularly attractive for actuator applications in micro- and nanometer dimensions as it enables contact-less control of large deformations, which can hardly be achieved by other actuation principles in small space. Two different approaches are being pursued to develop ferromagnetic shape memory (FSMA) microactuators based on the magnetically induced reorientation of martensite variants: (1) the fabrication of free-standing epitaxial Ni-Mn-Ga thin film actuators in a bottom-up manner by magnetron sputtering, substrate release and integration technologies and (2) the top-down approach of thickness reduction of bulk Ni-Mn-Ga single crystals to foil specime…
Automatic Generation of Subject-Based Image Transitions
2011
This paper presents a novel approach for the automatic generation of image slideshows. Counter to standard cross-fading, the idea is to operate the image transitions keeping the subject focused in the intermediate frames by automatically identifying him/her and preserving face and facial features alignment. This is done by using a novel Active Shape Model and time-series Image Registration. The final result is an aesthetically appealing slideshow which emphasizes the subject. The results have been evaluated with a users’ response survey. The outcomes show that the proposed slideshow concept is widely preferred by final users w.r.t. standard image transitions.
Spazio, forma, materia, contesto. La lezione perpetua di Távora
2022
Fernando Távora è certamente l’iniziatore, il fondatore e l’ideatore di ciò che è riconosciuta come la Scuola di Architettura di Porto. Una Scuola espressione, oggi, di una palingenesi dell’architettura portoghese contemporanea e, forse, senza esagerazione, di un neo-rinascimento architettonico mondiale a cavallo tra il XX e il XXI secolo. Il magister per eccellenza, colui che traccia il primo solco della strada che sarà, in seguito, percorsa dai Discenti - Alvaro Siza Vieira ed Eduardo Souto de Moura - ma con la visione duplice e antitetica di chi sa che la meta si raggiunge volgendo costantemente lo sguardo in avanti e, nel contempo, indietro, al proprio vissuto formativo e al lascito del…
Semiparametric stochastic frontier models: A generalized additive model approach
2017
Abstract The choice of the functional form of the frontier into a stochastic frontier model is typically neglected in applications and canonical functions are usually considered. This paper introduces a semiparametric approach for stochastic frontier estimation that extends previous works based on pseudo-likelihood estimators allowing flexibility in model selection and capability of imposing monotonicity and concavity constraints. For these purposes the present work introduces a generalized additive framework that moreover permits to model the influence of contextual/environmental factors to the hypothesized production process by the relative extension given by generalized additive models f…
Atlas-Based Evaluation of Hemodynamic in Ascending Thoracic Aortic Aneurysms
2021
Atlas-based analyses of patients with cardiovascular diseases have recently been explored to understand the mechanistic link between shape and pathophysiology. The construction of probabilistic atlases is based on statistical shape modeling (SSM) to assess key anatomic features for a given patient population. Such an approach is relevant to study the complex nature of the ascending thoracic aortic aneurysm (ATAA) as characterized by different patterns of aortic shapes and valve phenotypes. This study was carried out to develop an SSM of the dilated aorta with both bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV), and then assess the computational hemodynamic of virtual models ob…
Core hole screening and decay rates of double core ionized first row hydrides.
2013
Because of the high intensity, X-ray free electron lasers allow one to create and probe double core ionized states in molecules. The decay of these multiple core ionized states crucially determines the evolution of radiation damage in single molecule diffractive imaging experiments. Here we have studied the Auger decay in hydrides of first row elements after single and double core ionization by quantum mechanical ab initio calculations. In our approach the continuum wave function of the emitted Auger electron is expanded into spherical harmonics on a radial grid. The obtained decay rates of double K-shell vacancies were found to be systematically larger than those for the respective single …
Prediction of phase evolutions during friction stir welding of Ti-grade 5 T-joints using finite element modeling
2022
Friction Stir Welding (FSW) is a solid-state welding technology pioneered by The Welding Institute (TWI) in 1991. Originally used to weld aluminum alloys, it is now effectively utilized to weld high-resistance materials as well. The ultimate mechanical characteristics of the joints are inextricably linked to the microstructural evolutions that occur during the process in terms of phase change. It is then crucial, in order to carry out an effective process engineering, to predict the final material microstructure determined by the thermal history that occurred during the process itself. In the paper, a 3D Finite Element Method (FEM) model for the FSW of T-joints is proposed, based on a therm…