Search results for "Numerical"
showing 10 items of 2002 documents
Cognitive Reasoning and Inferences through Psychologically based Personalised Modelling of Emotions Using Associative Classifiers
2014
The development of Microsoft Kinect opened up the research field of computational emotions to a wide range of applications, such as learning environments, which are excellent candidates to trial computational emotions based algorithms but were never feasible for given consumer technologies. Whilst Kinect is accessible and affordable technology it comes with its' own additional challenges such as the limited number of extracted Action Units (AUs). This paper presents a new approach that attempts at finding patterns of interaction between AUs and each other on one hand and patterns that link the related AUs to a given emotion. In doing so, this paper presents the ground work necessary to reac…
Numerical modeling of blood flow in the internal jugular vein with the use of computational fluid mechanics software.
2021
ObjectivesTo determine the site and nature of altered hemodynamics in pathological internal jugular veins.MethodWith the use of computational fluid mechanics software we simulated blood flow in 3 D models of the internal jugular veins that exhibited different morphologies, including nozzle-like strictures in their upper parts and valves in the lower parts.ResultsIn a majority of models with nozzle-like strictures, especially those positioned asymmetrically, abnormal flow pattern was revealed, with significant flow separation and regions with reversed flow. Abnormal valves had no significant impact on flow in a case of already altered flow evoked by stricture in upper part of the vein.Conclu…
Inference of Spatiotemporal Processes over Graphs via Kernel Kriged Kalman Filtering
2018
Inference of space-time signals evolving over graphs emerges naturally in a number of network science related applications. A frequently encountered challenge pertains to reconstructing such dynamic processes given their values over a subset of vertices and time instants. The present paper develops a graph-aware kernel-based kriged Kalman filtering approach that leverages the spatio-temporal dynamics to allow for efficient online reconstruction, while also coping with dynamically evolving network topologies. Laplacian kernels are employed to perform kriging over the graph when spatial second-order statistics are unknown, as is often the case. Numerical tests with synthetic and real data ill…
Shakedown of elastic—plastic solids with frictionless unilateral contact boundary conditions
1997
Abstract Elastic perfectly plastic solids (or structures) in frictionless unilateral contact with a rigid obstacle and subjected to quasi-statically variable loads within a given domain are considered. In the hypothesis that the structure undergoes small displacements and complies with a d -stability requisite herein introduced, a Melantype shakedown theorem is presented. This theorem is conceptually similar to the classical one; namely, it requires that the unilateral-contact elastic stress response to the loads and to some initial plastic strains be plastically admissible everywhere in the body and for all load conditions. A method for evaluating the shakedown load boundary is also discus…
Accuracy of stereotactic coordinate transformation using a localisation frame and computed tomographic imaging
1999
The accuracy of coordinate transformation from a CT image to a stereotactic frame was investigated for stereotactic systems using a localisation frame and matrix-based coordinate transformation. The main source of error influencing calculation was input data, due to inaccurate calculation of the centres of the rods of the localisation frame in the CT image, and the propagation of this input error during subsequent matrix calculation. Systemic errors during matrix calculation do not exist, and rounding off errors were of subordinate importance compared to the input data error. The influence of input data error on coordinate transformation was studied by geometric methods, computer simulation…
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.
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.
Experimental Investigations and Numerical Analysis for Improving Knowledge of Incremental Sheet Forming Process for Sheet Metal Parts
2009
The paper is related to the analysis of shape distortions and springback effects arising in Single Point Incremental Forming. An experimental set up has been designed and manufactured to carry single point incremental forming on small size sheet metal parts. The experimental set up is mounted on 3-axes CNC milling machine tool and the forming tool is attached and move with the spindle. Experiments have been carried out on sheet metal parts to obtain tronconical shapes. The forming strategy associated to the movement of the forming tool has been also investigated. The experiments indicate that shape distortions arising in the corners of the tronconical shape are clearly related to forming st…
A Qualitative-Quantitative Approach to V-Belt Mechanics
1996
A simplified formulation is adopted for the theoretical problem of tension distribution and radial penetration of a V-belt along the pulley groove. The trajectory portrait of the second order differential system describing the belt behavior is carefully analyzed and asymptotic approximations for the tension solutions are derived which are well suited for design purposes.
Helical Shift Mechanics of Rubber V-Belt Variators
2011
A very common configuration of V-belt variators for motorcycles considers the correction of the belt tensioning depending on the resistant torque by means of suitable helical-shaped tracks allowing the driven half-pulleys to close/open. The theoretical model for belt-pulley coupling is rather complex for this configuration, where one half-pulley may run in advance and the other one behind with respect to the belt, and requires the repeated numerical solution of a strongly nonlinear differential system by a sort of shooting technique, until all the operating conditions are fulfilled (angular contact extent, torque, and axial force). After solving the full equations, the present study develop…