A Method To Improve Matching Process by Shape Characteristics in Parametric Systems

10 pagesInternational audienceIn current parametric systems, the persistent naming issue (based on edge mappings of intersecting surfaces) is not as fully supported as it should be. Unpredictability and ambiguity of models often happen during design reevaluation within systems. This reference deficiency is widely treated in the literature, especially about non-planar entities during design construction. Although related works ensure the uniqueness of the references to topological entities, they often neglect the shape characteristics of surfaces and give results different from those expected during design reevaluation. We propose in this paper a method to add some additional information about surfaces to improve such works. We compute those information by decomposing surfaces according to hump(s) and/or hollow(s). More precisely, our method use local extremums and inflexion curves to obtain one hump or hollow per sub-surface. The existing matching processes replace every surface with their corresponding subsurfaces, leading to the right edge mappings

A survey on 3D CAD model quality assurance and testing

[EN] A new taxonomy of issues related to CAD model quality is presented, which distinguishes between explicit and procedural models. For each type of model, morphologic, syntactic, and semantic errors are characterized. The taxonomy was validated successfully when used to classify quality testing tools, which are aimed at detecting and repairing data errors that may affect the simplification, interoperability, and reusability of CAD models. The study shows that low semantic level errors that hamper simplification are reasonably covered in explicit representations, although many CAD quality testers are still unaffordable for Small and Medium Enterprises, both in terms of cost and training time. Interoperability has been reasonably solved by standards like STEP AP 203 and AP214, but model reusability is not feasible in explicit representations. Procedural representations are promising, as interactive modeling editors automatically prevent most morphologic errors derived from unsuitable modeling strategies. Interoperability problems between procedural representations are expected to decrease dramatically with STEP AP242. Higher semantic aspects of quality such as assurance of design intent, however, are hardly supported by current CAD quality testers. (C) 2016 Elsevier Ltd. All rights reserved.This work was supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund, through the ANNOTA project (Ref. TIN2013-46036-C3-1-R).González-Lluch, C.; Company, P.; Contero, M.; Camba, J.; Plumed, R. (2017). A survey on 3D CAD model quality assurance and testing. Computer-Aided Design. 83:64-79. https://doi.org/10.1016/j.cad.2016.10.003S64798

Feature-based Product Modelling in a Collaborative Environment

Ph.DDOCTOR OF PHILOSOPH

Encaminhamento baseado no contexto em ICNs móveis

Over the last couple of decades, vehicular ad hoc networks (VANETs) have been at the forefront of research, yet still are afflicted by high network fragmentation, due to their continuous node mobility and geographical dispersion. To address these concerns, a new paradigm was proposed - Information-Centric Networks(ICN), whose focus is the delivery of Content based on names, being ideal to attend to high latency environments. However, the main proposed solutions for content delivery in ICNs do not take into account the type of content nor the various available communication interfaces in each point of the network, a factor which can be deciding in mobile networks. The scope of this dissertation lies on the use of ICNs concepts for the delivery of both urgent and non-urgent information in urban mobile environments. In order to do so, a context-based forwarding strategy was proposed, with a very clear goal: to take advantage of both packet names and Data, and node's neighborhood analysis in order to successfully deliver content into the network in the shortest period of time, and without worsening network congestion. The design, implementation and validation of the proposed strategy was performed using the ndnSIM platform simulator along with real mobility traces from communication infrastructure of the Porto city. The results show that the proposed context-based forwarding strategy for mobile ICN presents a clear improvement in performance in terms of delivery, while maintaining network overhead at a constant. Furthermore, by means of better pathing and through cooperation with caching mechanisms, lower transmission delays can be attained.Nas últimas décadas, as redes veiculares ad hoc (VANETs) estiveram na vanguarda da pesquisa, mas continuam a ser afetadas por alta fragmentação na rede, devido à mobilidade contínua dos nós e a sua dispersão geográfica. Para abordar estes problemas, um novo paradigma foi proposto - Redes Centradas na Informação (ICN), cujo foco é a entrega de Conteúdo com base em nomes, sendo ideal para atender ambientes de alta latência. No entanto, as principais soluções propostas para entrega de conteúdo em ICNs não têm em conta o tipo de conteúdo nem as várias interfaces de comunicação disponíveis em cada ponto da rede, fator que pode ser determinante em redes móveis. O objetivo desta dissertação reside no uso dos conceitos de ICNs para a entrega de informações urgentes e não urgentes em ambientes móveis urbanos. Para isso, foi proposta uma estratégia de encaminhamento baseada em contexto, com um objetivo muito claro: tirar proveito do nome e dados dos pacotes, e da análise de vizinhança dos nós, com vista em fornecer com êxito o conteúdo para a rede no menor período de tempo e sem piorar o congestionamento da rede. O desenho, implementação e validação da estratégia proposta foram realizados usando o simulador ndnSIM, juntamente com traces reais de mobilidade da infraestrutura de comunicação da cidade do Porto. Os resultados mostram que a estratégia de encaminhamento baseada em contexto proposta para o ICN móvel apresenta uma clara melhoria no desempenho em termos de entrega, mantendo a carga da rede constante. Além disso, através da escolha de melhores caminhos e através da cooperação com mecanismos de armazenamento em cache, é possível alcançar atrasos de transmissão mais baixos.Mestrado em Engenharia de Computadores e Telemátic

Constraint-Enabled Design Information Representation for Mechanical Products Over the Internet

Global economy has made manufacturing industry become more distributed than ever before. Product design requires more involvement from various technical disciplines at different locations. In such a geographically and temporally distributed environment, efficient and effective collaboration on design is vital to maintain product quality and organizational competency. Interoperability of design information is one of major barriers for collaborative design. Current standard CAD data formats do not support design collaboration effectively in terms of design information and knowledge capturing, exchange, and integration within the design cycle. Multidisciplinary design constraints cannot be represented and transferred among different groups, and design information cannot be integrated efficiently within a distributed environment. Uncertainty of specification cannot be modeled at early design stages, while constraints for optimization are not embedded in design data. In this work, a design information model, Universal Linkage model, is developed to represent design related information for mechanical products in a distributed form. It incorporates geometric and non-geometric constraints with traditional geometry and topology elements, thus allows more design knowledge sharing in collaborative design. Segments of design data are linked and integrated into a complete product model, thus support lean design information capturing, storage, and query. The model is represented by Directed Hyper Graph and Product Markup Language to preserve extensibility and openness. Incorporating robustness consideration, an Interval Geometric Modeling scheme is presented, in which numerical parameters are represented by interval values. This scheme is able to capture uncertainty and inexactness of design and reduces the chances of conflict in constraint imposition. It provides a unified constraint representation for the process of conceptual design, detailed design, and design optimization. Corresponding interval constraint solving methods are studied

Multiple-view product representation and development using augmented reality technology

Ph.DDOCTOR OF PHILOSOPH