Search results for "Computer aid"
showing 10 items of 105 documents
Multi-objective optimization of nitinol stent design.
2017
Nitinol stents continuously experience loadings due to pulsatile pressure, thus a given stent design should possess an adequate fatigue strength and, at the same time, it should guarantee a sufficient vessel scaffolding. The present study proposes an optimization framework aiming at increasing the fatigue life reducing the maximum strut strain along the structure through a local modification of the strut profile.The adopted computational framework relies on nonlinear structural finite element analysis combined with a Multi Objective Genetic Algorithm, based on Kriging response surfaces. In particular, such an approach is used to investigate the design optimization of planar stent cell.The r…
A comparative review of CASE shells: A preliminary framework and research outcomes
1993
Abstract Because of rigidity and weak support of the user's native methods and methodologies in existing CASE tools, there is a growing need for customizable CASE tools (CASE shells). The nature of CASE shells is different from ordinary CASE tools supporting a fixed set of methods. With CASE shells, organizations can define tools to support their own methods, instead of choosing a tool that supports them. Existing CASE shells have different features and architectural principles that make them appropriate for different tasks. Obviously, a framework for comparing them is needed. In this paper we develop one such framework. It takes into account different tasks in customization and the effecti…
Electric conduction in solids: a pedagogical approach supported by laboratory measurements and computer modelling environments
2008
In this paper we present a pedagogic approach aimed at modeling electric conduction in semiconductors, built by using NetLogo, a programmable modeling environment for building and exploring multi‐agent systems. ‘Virtual experiments’ are implemented to confront predictions of different microscopic models with real measurements of electric properties of matter, such as resistivity. The relations between these electric properties and other physical variables, like temperature, are, then, analyzed.
HEMT for low-noise microwaves: CAD-oriented performance evaluation
1995
This paper shows how a graphic processing of low-noise HEMT's small signal parameters, allows evaluating and comparing the actual performance obtainable in front-end applications. HEMT's tradeoff charts which solve tradeoffs among the basic low-noise amplifier performance are reported. Figures of merit for microwave low-noise HEMT which represent a fast way of evaluating HEMT in actual working conditions and of selecting the proper transistor, are defined. As an example, the tradeoff charts and the figures of merit of two HEMT's (Fujitsu FHR02FH, Sony 2SK677) and a pseudomorphic-HEMT (Celeritek CFB001-03) are reported and compared with the data sheets. © 1995, IEEE. All rights reserved.
A Functional Framework for Evaluating Method Engineering Environments: the case of Maestro II/ Decamerone and MetaEdit+
1996
CASE environments with method customisation capabilities and Computer Aided Method Engineering (CAME) environments have emerged during the last few years. While many research papers discuss the principles of method engineering and suggest requirements for new environments, we do not have critical evaluations of CAME environments using a wider method engineering framework. The aims of this study are twofold: 1) to build a preliminary framework for comparative studies of CAME environments, and 2) to increase the knowledge of the ‘state of the art’ in CAME by evaluating two CAME environments. We adapt a functional framework — originally built for CASE technology — to examine the following two …
Fast automated design of waveguide filters using aggressive space mapping with a new segmentation strategy and a hybrid optimization algorithm
2005
Waveguide filters are key elements present in many microwave and millimeter-wave communication systems. In recent times, ever-increasing efforts are being devoted to the development of automated computer-aided design (CAD) tools of such devices. In this paper, a novel CAD tool based on modal analysis methods, which improves the efficiency and robustness of the classical aggressive space-mapping technique, is presented for those purposes. The use of a new segmentation strategy and the hybridization of a specific combination of several well-known optimization algorithms is proposed. The CAD tool has been successfully validated with the practical design of several H-plane coupled cavity filter…
Efficient Analysis and Design Strategies for Evanescent Mode Ridge Waveguide Filters
2006
In this paper, a research on the compromises arisen in the design of traditional evanescent mode waveguide filters is carried out. As a result, clear design methodologies for optimizing length, losses, power handling and spurious-free out-of-band response are developed. In addition, an efficient and very accurate modal analysis tool for this kind of structures is presented. Several filters have been designed according to the different strategies proposed, and a prototype has been finally manufactured. Measurements and filter dimensions validate the proposed design procedures.
High Level Planning of Reconfigurable Enterprises: a Game Theoretic Approach
2006
Reconfigurable Enterprises (REs) represent production networks made of different and geographically dispersed plants that, in case of unpredictable market changes, can be reconfigured in order to gather a specific production objective. However, REs effectiveness and efficiency depend on the extent to which global performance is obtained. Basically two approaches are available to reach coordination: centralised or decentralised planning tools. In this paper, the authors propose a novel cooperative game theoretical approach for distributed production planning at high level of a RE; the proposed approach has been benchmarked in front of both a distributed one, based on negotiation, and a centr…
An Application of Ant Colony Optimization to Decision Making on Affective Virtual Entities
2007
Learning is a never ending activity for humans; it takes place everywhere and even when we do not realize. However, current learning environments make students deal with lectures, mostly associated with low control of the situation and implicit motivation. In contrast, previous researches have shown that sports, games or hobbies are activities that make people reach optimal experiences where self-motivation, control of the situation, high level of concentration and enjoyment are present. Some current efforts to design next generation of learning environments make use of ubiquitous systems to encourage students to perform learning activities everywhere and at anytime. However, those approach…
Yacht performance monitoring in real sailing conditions
2019
Abstract In this paper a multi-method approach is used to setup and validate a monitoring system applied to a small sailing boat during real sailing conditions. This monitoring system is able to transform the data coming from some typical devices installed on board into information about the deformed state of the boat. GPS, Wind Data Logger and cameras have been installed on the boat to measure its route and speed, the apparent wind velocity and direction and the positions of the crew members. These data are processed to determine the equilibrium of the boat and estimate the loads applied on it. Then, a CAD/FEM model calculates the effects of these loads on the boat shape. The resulting def…