Search results for "Simulation."
showing 10 items of 4779 documents
A Rule-Based Method to Model Myocardial Fiber Orientation for Simulating Ventricular Outflow Tract Arrhythmias
2017
Comunicació presentada a: FIMH 2017 9th International Conference, celebrada a Toronto, Canadà, de l'11 al 13 de juny de 2017. Myocardial fiber orientation determines the propagation of electrical waves in the heart and the contraction of cardiac tissue. One common approach for assigning fiber orientation to cardiac anatomi- cal models are Rule-Based Methods (RBM). However, RBM have been developed to assimilate data mostly from the Left Ventricle. In conse- quence, fiber information from RBM does not match with histological data in other areas of the heart, having a negative impact in cardiac simulations beyond the LV. In this work, we present a RBM where fiber orientation is separately mode…
Large-eddy simulations of turbulent flow with heat transfer in simple and complex geometries using Harwell-FLOW3D
1996
Abstract Large-eddy simulation (LES) results are presented and discussed for the turbulent flow with heat transfer in different geometrical configurations, including a plane channel, a channel bearing transverse square ribs on one of the walls, and a crossed-corrugated air heater. They were obtained using the computational fluid dynamics (CFD) code Harwell-FLOW3D (Release 2), finite-volume grids having up to 423 nodes, and the Smagorinsky subgrid model with several variants regarding near-wall damping and wall boundary conditions. The first problem (plane turbulent Poiseuille flow with heat transfer) was mainly used as a benchmark to investigate the influence of numerical methods (pressure-…
Influence of online shopping information dependency and innovativeness on internet shopping adoption
2008
PurposeThe paper's purpose is to analyse the influence of online shopping information dependency and innovativeness on the acceptance of internet shopping.Design/methodology/approachThe impact of online shopping information dependency, domain‐specific innovativeness and technology acceptance model (TAM) variables on future shopping intention has been tested through structural equation modelling techniques. The sample consisted of 465 Spanish consumers who had never purchased online.FindingsData analysis shows that consumer innovativeness and online shopping information dependency have a direct and positive influence on future online shopping intention and that the basic TAM hypotheses are f…
IMPROVING CNC MACHINE TOOLS ACCURACY USING MODELING AND COMPUTER SIMULATION TECHNIQUES
2007
Abstract The position was one of the first parameters that required the introduction of automatic control process. One of the most representative applications is represented by the feed drives of the computer numerically controlled (CNC) machine tools. Today, it is possible to use computer simulation techniques in analysing and synthesising position control systems. Thus, the behaviour of the CNC machine tools feed drives can be treated much more realistically. It is the purpose of this paper to show how simulation can be used to accurately represent, predict and improve the performance of a CNC machine tool feed servo drives.
Combined Endo- and Exoscopic Semi-robotic Manipulator System for Image Guided Operations
2006
This paper describes the development of a robotic assistance system for image guided operations. To minimize operation time, a multimodal user interface enables freehand robotic manipulation of an extracorporeal stereoscopic digital camera (exoscope) and an endoscope. The surgeon thereby wears a head-mounted unit with a binocular display, a head tracker, a microphone and earphones. Different view positioning and adjustment modes can be selected by voice and controlled by head rotation while pressing a miniature confirmation button with a finger. Initial studies focused on the evaluation and optimization of the intuitiveness, comfort and precision of different modes of operation, including a…
Robust technique for 3D shape reconstruction
2017
Abstract In this paper a robust and simple scheme is presented for three dimensional (3D) shape reconstruction of real object. A novel composite pattern technique is proposed for projecting the light pattern on the object of interest. The proposed scheme reduces the number of patterns by combining the primary color coded channels into one composite format. Our approach uses both spatial and temporal intensity variation for calibration and construction phase. Gamma calibration is considered with the propose scheme. High quality depth map is obtained from the linear light reflected by the shape of object without complex calculations. Experimental results demonstrated that proposed technique i…
Computer-Aided Simulation of Die Filling Processes
1989
Summary A numerical method for analysing the filling of axisymmetrical dies of complex shape is proposed. The method, which is a further development of a LP finite element model, is able to take into account the contact conditions directly in the mathematical formulation of the problem. In such a way the solution of the die filling process is obtained by solving a LP problem, avoiding problems of numerical convergence and the heavier calculations requested by other iterative methods.
Using a neural network for qualitative and quantitative predictions of weld integrity in solid bonding dominated processes
2014
Solid-state bonding occurs in several manufacturing processes, as Friction Stir Welding, Porthole Die Extrusion and Roll Bonding. Proper conditions of pressure, temperature, strain and strain rate are needed in order to get effective bonding in the final component. In the paper, a neural network is set up, trained and used to predict the bonding occurrence starting from the results of specific numerical models developed for each process. The Plata-Piwnik criterion was used in order to define a quantitative parameter taking into account the effectiveness of the bonding. Excellent predictive capability of the network is obtained for each process.
Finite-element simulation of residual stress induced by split-sleeve cold-expansion process of holes
2008
A three-dimensional finite-element simulation was conducted for a split-sleeve cold-expansion process in order to determine the residual stress field around an expanded hole. The commercial FEA software DEFORM-3D™, a Lagrangian implicit code designed for metal forming processes, was used to model the cold-expansion process of a fastener hole. The results show a through-thickness residual stress field in good agreement with the analytical solution developed by Guo. Moreover, the simulation has highlighted the effect of the split sleeve and the plate thickness on the residual stress field. © 2007 Elsevier B.V. All rights reserved.
Analytical bonding criteria for joint integrity prediction in friction stir welding of aluminum alloys
2014
Abstract In this study, two bonding criteria, previously used for porthole die extrusion, are applied to FSW starting from the local value of the main field variables calculated through a specifically developed 3D numerical model of the process. Their applicability and effectiveness have been assessed through an experimental and numerical campaign carried out with the main process parameters varying in a wide range. The pressure–time–flow criterion was demonstrated to be better suited for FSW processes when large welding speed is used.