Stochastic porous media, towards a digital meniscus

in Bulletin of the American Physical Society (2022)

STREAMS: A supporting tool for shared mobility services

Scientific Conference (2020, November)

Stress analysis without meshing: Isogeometric boundary-element method

in Proceedings of the Institution of Civil Engineers: Engineering and Computational Mechanics (2013), 166(2), 88-99

The focus of this paper is the description and numerical validation of a computational method where stress analysis can be performed directly from computer-aided design data without mesh generation. The ... [more ▼]

The focus of this paper is the description and numerical validation of a computational method where stress analysis can be performed directly from computer-aided design data without mesh generation. The clear benefit of the approach is that no mesh needs to be generated prior to running the analysis. This is achieved by utilising the isogeometric concept whereby computer-aided design data are used to construct not only the geometry discretisation but also the displacement and traction approximations. In this manner, significant savings can be made in the engineering design and analysis process. This paper also demonstrates that, compared with a standard boundary-element method implementation using quadratic Lagrangian shape functions, superior accuracy is achieved using the present approach for the same number of degrees of freedom. It further illustrates practical applications of the method, comparing against results obtained with a standard boundary-element method and finite-element method for verification. In addition, a propeller is analysed as a sample to show the ability of the present method to handle complex three-dimensional geometries. [less ▲]

Strongly-coupled modelling and analysis of energy harvesting devices

in Applied Mathematics and Mechanics (2016), 16

A monolithic approach is proposed that provides simultaneous modelling and analysis of the harvester, which involves surface- coupled fluid-structure interaction, volume-coupled electro- mechanics and a ... [more ▼]

A monolithic approach is proposed that provides simultaneous modelling and analysis of the harvester, which involves surface- coupled fluid-structure interaction, volume-coupled electro- mechanics and a controlling energy harvesting circuit for applica- tions in energy harvesting. A space-time finite element approximation is used for numerical solution of the weighted residual form of the governing equations of the flow-driven piezoelectric energy harvesting device. This method enables time-domain investigation of different types of structures (plate, shells) subject to exterior/interior flow with varying cross sections, material compositions, and attached electrical circuits with respect to the electrical power output generated. [less ▲]

Structural shape optimization of three dimensional acoustic problems with isogeometric boundary element methods

in Computer Methods in Applied Mechanics and Engineering (2019), 355

The boundary element method (BEM) is a powerful tool in computational acoustics, because the analysis is conducted only on structural surfaces, compared to the finite element method (FEM) which resorts to ... [more ▼]

The boundary element method (BEM) is a powerful tool in computational acoustics, because the analysis is conducted only on structural surfaces, compared to the finite element method (FEM) which resorts to special techniques to truncate infinite domains. The isogeometric boundary element method (IGABEM) is a recent progress in the category of boundary element approaches, which is inspired by the concept of isogeometric analysis (IGA) and employs the spline functions of CAD as basis functions to discretize unknown physical fields. As a boundary representation approach, IGABEM is naturally compatible with CAD and thus can directly perform numerical analysis on CAD models, avoiding the cumbersome meshing procedure in conventional FEM/BEM and eliminating the difficulty of volume parameterization in isogeometric finite element methods. The advantage of tight integration of CAD and numerical analysis in IGABEM renders it particularly attractive in the application of structural shape optimization because (1) the geometry and the analysis can be interacted, (2) remeshing with shape morphing can be avoided, and (3) an optimized solution returns a CAD geometry directly without postprocessing steps. In the present paper, we apply the IGABEM to structural shape optimization of three dimensional exterior acoustic problems, fully exploiting the strength of IGABEM in addressing infinite domain problems and integrating CAD and numerical analysis. We employ the Burton–Miller formulation to overcome fictitious frequency problems, in which hyper-singular integrals are evaluated explicitly. The gradient-based optimizer is adopted and shape sensitivity analysis is conducted with implicit differentiation methods. The design variables are set to be the positions of control points which directly determine the shape of structures. Finally, numerical examples are provided to verify the algorithm. [less ▲]

Student's Perception of a Semantic Search Engine

Scientific Conference (2005)

Supervised learning for a Kraft recovery boiler: a data mining approach with Random Forests.

in Favrat, Daniel; Maréchal, François (Eds.) ECOS 2010 Volume IV (Power plants and Industrial processes) (2011, January 11)

A data mining methodology, the random forests, is applied to predict high pressure steam production from the recovery boiler of a Kraft pulping process. Starting from a large database of raw process data ... [more ▼]

A data mining methodology, the random forests, is applied to predict high pressure steam production from the recovery boiler of a Kraft pulping process. Starting from a large database of raw process data, the goal is to identify the input variables that explain the most significant output variations and to predict the high pressure steam flow. [less ▲]

SUPPORTING INTERDISCIPLINARY SYSTEM DEVELOPMENT THROUGH INTEGRATED FUNCTION MODELLING

Doctoral thesis (2014)

Industry is confronted with ever-changing and increasing demand of customers on global markets for integration of diverse functions into newly developed products and systems. As a consequence, companies ... [more ▼]

Industry is confronted with ever-changing and increasing demand of customers on global markets for integration of diverse functions into newly developed products and systems. As a consequence, companies increasingly often combine different engineering technologies into their products necessitating close collaboration of experts from various disciplines. New types of products, such as Product-Service Systems (PSS), which have become increasingly important in the recent past and combine (multi-disciplinary) products with associated services, extend interdisciplinary system development by including further disciplines. Problems in the (cross-disciplinary) exchange of information between the involved designers are considered one of the central risks posed to the success of interdisciplinary system development. Function modelling is expected to provide suitable means for the integration of different disciplines, as it addresses solution finding early in the design process and results in a first abstract representation of the system under consideration. However, a large variety of different and often incompatible function models can be found in the different disciplines, which hampers shared, cross-disciplinary function modelling. The research project presented in this thesis provides comprehensive insights into central barriers and enablers for cross-disciplinary function modelling in the development of mechatronic systems and PSS. Conducted research comprises comprehensive literature reviews of diverse function models and function modelling approaches proposed in disciplinary and interdisciplinary design approaches. The derived insights are complemented by empirical studies in ten companies active in diverse market areas, such as machine design, automotive, aerospace, and consumer product development. The empirical studies provide compelling insights into the actual application of function modelling in different disciplines and design departments, as well as into specific needs and preferences of practicing designers from different disciplines. A central contribution resulting from this research is the ”Integrated Function Modelling framework”, which is intended to address the identified needs and provide practicing designers with a flexible and generic modelling approach supporting interdisciplinary conceptual design. The project is concluded with an initial evaluation of the developed framework in industry and academia. [less ▲]

Supporting the Knowledge Life Cycle

in Kluwer Academic Publishers (Ed.) Knowledge Intensive CAD (1999)

A Survey of Information Entropy Metrics for Complex Networks

in Entropy (2020)

Information entropy metrics have been applied to a wide range of problems that were abstracted as complex networks. This growing body of research is scattered in multiple disciplines, which makes it ... [more ▼]

Information entropy metrics have been applied to a wide range of problems that were abstracted as complex networks. This growing body of research is scattered in multiple disciplines, which makes it difficult to identify available metrics and understand the context in which they are applicable. In this work, a narrative literature review of information entropy metrics for complex networks is conducted following the PRISMA guidelines. Existing entropy metrics are classified according to three different criteria: whether the metric provides a property of the graph or a graph component (such as the nodes), the chosen probability distribution, and the types of complex networks to which the metrics are applicable. Consequently, this work identifies the areas in need for further development aiming to guide future research efforts. [less ▲]