Results 81 to 90 of about 410,519 (339)

Classification of curves on de Sitter plane

Pracì Mìžnarodnogo Geometričnogo Centru, 2020
In 1917, de Sitter used the modified Einstein equation and proposed a model of the Universe without physical matter, but with a cosmological constant. De Sitter geometry, as well as Minkowski geometry, is maximally symmetrical.
Irina Streltsova
doaj   +1 more source

Projective planes, Severi varieties and spheres [PDF]

Surveys in Differential Geometry VIII, Papers in Honor of Calabi, Lawson, Siu and Uhlenbeck (International Press, Somerville, MA, 2003) 1-27., 2002
A classical result asserts that the complex projective plane modulo complex conjugation is the 4-dimensional sphere. We generalize this result in two directions by considering the projective planes over the normed real division algebras and by considering the complexifications of these four projective planes.
arxiv  

Effects of cardiac motion on dose distribution during stereotactic arrhythmia radioablation treatment: A simulation and phantom study

Journal of Applied Clinical Medical Physics, EarlyView.
Abstract Purpose Cardiac motion may degrade dose distribution during stereotactic arrhythmia radioablation using the CyberKnife system, a robotic radiosurgery system. This study evaluated the dose distribution changes using a self‐made cardiac dynamic platform that mimics cardiac motion. Methods The cardiac dynamic platform was operated with amplitudes
Takayuki Miyachi, Takeshi Kamomae, Fumitaka Kawabata, Kuniyasu Okudaira, Mariko Kawamura, Shunichi Ishihara, Shinji Naganawa   +6 more
wiley   +1 more source

A Variational Beam Model for Failure of Cellular and Truss‐Based Architected Materials

Advanced Engineering Materials, EarlyView., 2023
Herein, a versatile and efficient beam modeling framework is developed to predict the nonlinear response and failure of cellular, truss‐based, and woven architected materials. It enables the exploration of their design space and the optimization of their mechanical behavior in the nonlinear regime. A variational formulation of a beam model is presented
Konstantinos Karapiperis, Kaoutar Radi, Zifan Wang, Dennis M. Kochmann   +3 more
wiley   +1 more source

Evolutes of plane curves and null curves in Minkowski $3$-space [PDF]

arXiv, 2016
We use the isotropic projection of Laguerre geometry in order to establish a correspondence between plane curves and null curves in the Minkowski $3$-space. We describe the geometry of null curves (Cartan frame, pseudo-arc parameter, pseudo-torsion, pairs of associated curves) in terms of the curvature of the corresponding plane curves.
arxiv  

Evaluation of the dose reduction effect of crystalline lens exposure in cone‐beam computed tomography with bismuth eye shield for image‐guided radiation therapy: An anthropomorphic phantom study

Journal of Applied Clinical Medical Physics, EarlyView.
Abstract This study aimed to evaluate the dose‐exposure reduction effect of a crystalline lens with a bismuth eye shield using cone‐beam computed tomography (CBCT) for head image‐guided radiation therapy. The ocular surface dose of the head phantom (THRA‐1) is defined as a crystalline lens exposure dose and is measured using a radiophotoluminescence ...
Tatsuya Yoshida, Koji Sasaki, Yoshiyuki Kawasaki, Tomoki Hayakawa, Toshiyuki Kawadai, Takako Shibasaki   +5 more
wiley   +1 more source

Topology Optimization of Lattice Support Structure for Cantilever Beams Fabricated Via Laser Powder Bed Fusion

Advanced Engineering Materials, EarlyView., 2023
A numerical scheme is presented to design a lattice support for metallic components additively built via laser powder bed fusion. Results show that thermal‐induced distortion can be respectively reduced by 69%, 58%, and 50% in comparison to a uniform lattice, a fully solid support, and a truss‐based lattice support.
Jiazheng Hu, Marjan Molavi‐Zarandi, Damiano Pasini   +2 more
wiley   +1 more source

TEACHING BASIC ELEMENTS IN DESCRIPTIVE GEOMETRY – LINE INTERSECTING A PLANE

Journal of Industrial Design and Engineering Graphics
The paper presents applications developed for teaching descriptive geometry. The aim of the applications presented is the understanding of the basic elements of the descriptive geometry – the relative positions of a straight line and a plane and they ...
Ramona CLINCIU, Mihaela Rodica CLINCIU
doaj   +2 more sources

Gluing two affine Yangians of 𝔤𝔩1

Journal of High Energy Physics, 2019
We construct a four-parameter family of affine Yangian algebras by gluing two copies of the affine Yangian of 𝔤𝔩1. Our construction allows for gluing operators with arbitrary (integer or half integer) conformal dimension and arbitrary (bosonic or ...
Wei Li, Pietro Longhi
doaj   +1 more source

Varieties of planes on intersections of three quadrics [PDF]

arXiv, 2019
We study the geometry of spaces of planes on smooth complete intersections of three quadrics, with a view toward rationality questions.
arxiv