Search results for "Simulation"
showing 10 items of 5095 documents
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.
Novel nanocrystalline cores for EMI suppression in cables: characterization methodology and performance study
2021
El control de las interferencias electromagnéticas (EMI) en dispositivos electrónicos es un problema cada vez mayor al que se enfrentan los diseñadores para garantizar que los dispositivos cumplan con los requisitos de compatibilidad electromagnética (EMC) para operar simultáneamente sin inferir entre sí. Este hecho se debe a la tendencia hacia una mayor integración de componentes, la reducción del tamaño y grosor de las placas de circuito impreso (PCB) y la miniaturización de las carcasas de los dispositivos. Además, otros factores como el empleo de frecuencias de conmutación más altas en los convertidores de potencia y las velocidades de datos de comunicación en los circuitos digitales. C…
Optimal valves regulation for calibration of pipe networks models
1998
The calibration of a pipe network model is faced by means of a two-steps iterative procedure. The first step of the procedure is the estimation of the parameters in the network simulation model, obtained from a first set of water head measures. The second step of the procedure is the change of the resistances provided by the valves in the network and the acquisition of a new set of measures. The inverse problem is then solved again and the procedure is repeated, until the set of computed parameters converge to stable values. The new resistances are chosen to minimize the sum of the variation coefficients, computed from the Fisher information matrix. The effect of different correlation funct…
Tackling wicked problems in performance management and governance of public health: an empirical analysis of COVID-19 vaccination strategies
2023
PurposePublic health strategies and activities are intrinsically complex. According to the literature, this “wickedness” depends on the different interests and expectations of the stakeholders and the community, the fragmented governance of the related services and the challenges in measuring and assessing public health outcomes. Existent performance measures and management systems for public health are not designed to cope with wickedness since they are mainly focused on inputs and outputs, neglecting broader outcomes because of their long-term impact and the poor accountability of results. This research aims to tackle this shortfall by adopting a dynamic performance management (DPM) appro…
Evaluation des simulations spatiales
2006
The general topic is the evaluation of prospective scenarios for urban planning, especially for the management of urban built up areas. Several models of land-use and land-cover change (LUCC), based on different assumptions, allow producing realistic simulations of urban growth. Three ways can be distinguished for measuring the quality of modelings: 1. The choice of a model and its calibration; 2. The validation (showing if results are realistic); 3. The evaluation (showing if results respect defined planning goals). Measurement methods must be associated to these three steps.
An Automata-Based Cardiac Electrophysiology Simulator to Assess Arrhythmia Inducibility
2022
Personalized cardiac electrophysiology simulations have demonstrated great potential to study cardiac arrhythmias and help in therapy planning of radio-frequency ablation. Its application to analyze vulnerability to ventricular tachycardia and sudden cardiac death in infarcted patients has been recently explored. However, the detailed multi-scale biophysical simulations used in these studies are very demanding in terms of memory and computational resources, which prevents their clinical translation. In this work, we present a fast phenomenological system based on cellular automata (CA) to simulate personalized cardiac electrophysiology. The system is trained on biophysical simulations to re…
Design, Synthesis and Biological Evaluation of Novel Pyrazolo[1,2,4]triazolopyrimidine Derivatives as Potential Anticancer Agents
2021
Three novel pyrazolo-[4,3-e][1,2,4]triazolopyrimidine derivatives (1, 2, and 3) were designed, synthesized, and evaluated for their in vitro biological activity. All three compounds exhibited different levels of cytotoxicity against cervical and breast cancer cell lines. However, compound 1 showed the best antiproliferative activity against all tested tumor cell lines, including HCC1937 and HeLa cells, which express high levels of wild-type epidermal growth factor receptor (EGFR). Western blot analyses demonstrated that compound 1 inhibited the activation of EGFR, protein kinase B (Akt), and extracellular signal-regulated kinase (Erk)1/2 in breast and cervical cancer cells at concentrations…