Search results for "Geometric"
showing 10 items of 652 documents
Scaling behavior of topologically constrained polymer rings in a melt
2014
Large scale molecular dynamics simulations on graphic processing units (GPUs) are employed to study the scaling behavior of ring polymers with various topological constraints in melts. Typical sizes of rings containing $3_1$, $5_1$ knots and catenanes made up of two unknotted rings scale like $N^{1/3}$ in the limit of large ring sizes $N$. This is consistent with the crumpled globule model and similar findings for unknotted rings. For small ring lengths knots occupy a significant fraction of the ring. The scaling of typical ring sizes for small $N$ thus depends on the particular knot type and the exponent is generally larger than 0.4.
An Optimized Architecture for CGA Operations and Its Application to a Simulated Robotic Arm
2022
Conformal geometric algebra (CGA) is a new geometric computation tool that is attracting growing attention in many research fields, such as computer graphics, robotics, and computer vision. Regarding the robotic applications, new approaches based on CGA have been proposed to efficiently solve problems as the inverse kinematics and grasping of a robotic arm. The hardware acceleration of CGA operations is required to meet real-time performance requirements in embedded robotic platforms. In this paper, we present a novel embedded coprocessor for accelerating CGA operations in robotic tasks. Two robotic algorithms, namely, inverse kinematics and grasping of a human-arm-like kinematics chain, ar…
Implementation and evaluation of medical imaging techniques based on conformal geometric algebra
2020
Medical imaging tasks, such as segmentation, 3D modeling, and registration of medical images, involve complex geometric problems, usually solved by standard linear algebra and matrix calculations. In the last few decades, conformal geometric algebra (CGA) has emerged as a new approach to geometric computing that offers a simple and efficient representation of geometric objects and transformations. However, the practical use of CGA-based methods for big data image processing in medical imaging requires fast and efficient implementations of CGA operations to meet both real-time processing constraints and accuracy requirements. The purpose of this study is to present a novel implementation of …
Construction stages of cable-stayed bridges with composite deck
2012
A cable-stayed bridge is built by following a construction sequence of different subsequent stages that imply changes of the geometric configuration, restraints and consequently stress and strain patterns. A study is presented about stay stressing sequences in cable-stayed bridges with composite deck for the case of construction made by the cantilever method. Initial cable forces are found through partial elastic schemes of construction stages. Different stay stressing procedures are implemented and a comparison between them is proposed in order to evaluate the differences in terms of deformed shape and internal force distribution of the deck and the pylon. Results can be useful to give pra…
Geometry and quasisymmetric parametrization of Semmes spaces
2011
We consider decomposition spaces R 3 /G that are manifold factors and admit defining sequences consisting of cubes-with-handles of finite type. Metrics on R 3 /G constructed via modular embeddings of R 3 /G into a Euclidean space promote the controlled topology to a controlled geometry. The quasisymmetric parametrizability of the metric space R 3 /G×R m by R 3+m for any m ≥ 0 imposes quantitative topological constraints, in terms of the circulation and the growth of the cubes-with-handles, on the defining sequences for R 3 /G. We give a necessary condition and a sufficient condition for the existence of such a parametrization. The necessary condition answers negatively a question of Heinone…
Intorno alla rappresentazione per l'architettura con l'assonometria diretta
2023
Si propongono dei procedimenti grafici, rapidi e concreti, basati su fondamenti scientifici consolidati, per disegnare in assonometria (obliqua ed ortogonale) le geometrie essenziali dell’architettura e del design. Le assonometrie illustrate comprendono progetti di architettura e di design, poliedri, volte, elementi costruttivi, strutture elicoidali e quadriche. Il disegno assonometrico viene indirizzato alla ricerca grafica significativa ed alla efficace comunicazione percettiva, mediante osservazioni sull’orientamento delle strutture geometriche e suggerimenti relativi alla funzionale riduzione proiettiva delle dimensioni, in base alle finalità della rappresentazione. Il procedimento asso…
Modelli interoperabili per Cultural Heritage Recording. Le cupole a torrini di Sicilia e Castiglia.
La ricerca indaga l’origine e l’evoluzione di uno specifico modello di cupola su tamburo a pianta circolare o poligonale, con contrafforti cilindrici sull’asse dei piloni della crociera. Sei casi studio in Spagna e in Sicilia sono stati studiati attraverso il riesame delle fonti storiche e sono state analizzate le matrici geometriche sottese al progetto; i casi studio ancora esistenti sono stati rilevati con metodi laser scanning e fotogrammetrici. I modelli tridimensionali sono stati utilizzati per una verifica del contributo statico offerto dai torrini alla stabilità delle strutture. The research work is focused on the origin and the modifications of a peculiar dome on tambour having a ci…
Visual scale factor for speed perception rendering in car driving simulation
2010
Speed perception is an important task that the driver must perform continuously to control his/her vehicle. It appears that many factors influence this perception: height of the point of view, field of view, realism of the environment, but also realism of audio and proprioceptive rendering. If some high-performance car driving simulators are able to render motion satisfactorily according to all these criteria, it is not always the case. As a result, speed perception is thus often under estimated, leading into producing higher speeds than in real conditions. Perceptual validity is then not good enough to study driver's behavior. To solve this problem, a technique has recently seen the light,…