41 research outputs found
The Orthonormalized Generalized Finite Element Method-OGFEM: Efficient and stable reduction of approximation errors through multiple orthonormalized enriched basis functions
No full textAn extension of the Generalized Finite Element Method (GFEM) is proposed with which we efficiently reduce approximation errors. The new method constructs a stiffness matrix with a conditioning that is significantly better than the Stable Generalized Finite Element Method (SGFEM) and the Finite Element Method (FEM). Accordingly, the risk of a severe loss of accuracy in the computed solution, which burdens the GFEM, is prevented. Furthermore, the computational cost of the inversion of the associated stiffness matrix is significantly reduced. The GFEM employs a set of enriched basis functions which is chosen to improve the rate at which the approximation converges to the exact solution. The stiffness matrix constructed from these basis functions is often ill-conditioned and the accuracy of the solution cannot be guaranteed. We prevent this by orthonormalizing the basis functions and refer to the method as the Orthonormalized Generalized Finite Element Method (OGFEM). Because the OGFEM has the flexibility to orthonormalize either a part or all of the basis functions, the method can be considered as a generalization of the GFEM. The method is applicable with single or multiple global and/or local enrichment functions. Problems in blending elements are avoided by a modification of the enrichment functions. The method is demonstrated for the one-dimensional modified Helmholtz and Poisson equations and compared with the FEM, GFEM and SGFEM
Modelling risk in high hazard operations: Integrating technical, organisational and cultural factors
No full textRecent disasters in high hazard industries such as Oil and Gas Exploration (The Deepwater Horizon) and Petrochemical production (Texas City) have been found to have causes that range from direct technical failures through organizational shortcomings right up to weak regulation and inappropriate company cultures. Risk models have generally concentrated upon technical failures, which are easier to construct and for which there is more concrete data. The primary causes, as identified by the US Chemical Safety Board for Texas City and the Presidential Commission for the Deepwater Horizon, lie firmly rooted in the culture of the organization and determine the way in which individuals go about risky activities. Modelling human activities, especially collectively rather than individual human errors as is done in most human models, is a quite different proposition, in which complex interactions between different individuals and levels change over time as success and failure alter the pattern of payoffs. This paper examines the development of an integrated model for risk in a real-time environment for the hydrocarbon industry. It is based originally on the CATS model for commercial aviation safety, that first attempted to address some of these problems in a relatively simple way. Aviation is, however, a relatively simple activity, with large numbers of common components in a constrained environment. The Oil and Gas industry is significantly more diverse, covering the gamut from exploration, drilling, production, transport, refining and chemical production, each with its own potential for large scale disaster, but in the case of an integrated oil company all run by individuals within a common company culture. Other papers will cover the details of specific issues; this paper covers the integration of the model as a whole.Values and TechnologyTechnology, Policy and Managemen
‘Ladder’-based safety culture assessments inversely predict safety outcomes
No full textThere is little empirical evidence on the predictive value of safety culture assessments (SCAs) in relation to how accident-prone an organisation might be. Recently, Antonsen not just demonstrated how a quantitative SCA mispredicted future safety outcomes, but actually showed an inverse relationship between the assessment and subsequent critical incident investigation findings. To add to our understanding, this article presents research on whether a SCA has a predictive capacity for safety outcomes. Like in Antonsen's research, an opportunity emerged when a helicopter taxiing accident, resulting in a rotor strike occurred for a helicopter squadron that had just undergone a SCA. The assessment used ‘culture ladder’ rubrics for its findings, which allowed us to look for specific features in the subsequent independent accident investigation (in which the researchers were not involved). As with Antonsen's findings, our research shows that a ‘ladder’-based assessment has little predictive value. Any predictive value it has is in the inverse of the assessment findings. For instance, where the SCA showed that the safety culture was very mature regarding finding a balance between safety and the mission at hand or the breaking of rules, the accident investigation pointed these out as the causes of the accident.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Values Technology and Innovatio
On the minimization of round-off errors induced by the generalized finite element method (poster)
No full textStructural EngineeringCivil Engineering and Geoscience
The quality of the post academic course ‘management of safety, health and environment (MoSHE) of Delft University of Technology
No full textObjective This article discusses the rise of European postgraduate courses in safety science and the content and quality of the Management of Safety Health and Environment (MoSHE) course of Delft University of Technology. Materials and methods Literature search, document analysis, interviews. Results The different MoSHE years show a varied picture of this post academic program. In the Netherlands the course is unique with a central focus on risk management and sustainability, supported by scientific developments in the areas of safety, health, environment, organizational science and psychology. In all year-groups the quality of the course was assessed with a short questionnaire, collecting opinions of course members on individual presentations and the course as a whole. Quality of the course was regularly discussed through the contacts of the course coordinator with module leaders, and at meetings of course committees, and leading to changes in content of modules. After MoSHE 1 (1989), 14 (2008), and 17 (2012) the courses’ structure, organization and content was changed radically. Only, the quality system of the course remained implicit. Using the model of the European Foundation for Quality Management a first set-up for a quality system is presented. Over the years the academic nature of the program has changed substantially. This is one of the challenges for the future to find a balance between the domains taught and between an academic approach and practical skills. The course could benefit from a greater input of process safety and safety in high-tech-high-hazard sectors.Safety and Security Scienc
Exploring the role of cross-cultural friendships in the internationalization of higher education in Canada: A case study
No full textPoste
Warning citizens; influencing self-reliance in emergencies
No full textAn important part of the response to an emergency is making sure that people are able to take themselves and others to a place of safety. To make people aware that there is an emergency, there are three steps that have to be taken: there has to be a warning that something is going on, people have to perceive and process that warning, and finally, people have to perform the self-reliant behaviour that will get them to a safe place. Self-reliance can be increased when people are motivated to comply with instructions that are given in an emergency. This thesis is about finding out what factors influence self-reliance in an emergency and how these influencing factors can be investigated so that the total effectiveness of a warning system can be determined. The research question is: How can the way in which a new or existing warning system effectively influences citizens’ self-reliance in an emergency be investigated? A model was constructed which shows the steps of warning information processing in which self-reliance can be influenced. This model is called the contextual human information processing model, as it shows the influences on self-reliance in terms of the interactions between cognition, affective states and situational variables. The model looks at issues inside (HIP, Personal characteristics and behaviour) and outside (situational characteristics and warning) the human. The model produces a list of influencing factors that have to be investigated when determining the effectiveness of a warning system.Safety ScienceTechnology, Policy and Managemen
Using the Participatory Value Evaluation methodology to discover influences of risk acceptance on preferences for risk mitigation: A case-study on gas induced earthquakes in Groningen
No full textRecent years the Netherlands have been shocked by a series of earthquakes. Normally an earthquake would be considered as a natural hazard, however extracting gas induces these earthquakes. Whenever a hazard is induced, it is perceived as man-made and therefore controllable. This leads to differences in risk acceptance in relation to natural hazards. When ambiguity about risks exists, a participatory strategy should be used with involvement of the local community. In cases of induced hazards, low trust between local communities and authorities exists, leading to ineffective risk mitigation. The first step of improving mitigation measures is finding out whether differences in risk acceptance lead to differences in mitigation measure preferences. In this paper this research objective is carried out by gathering data in the earthquake area in Groningen with the Participatory Value Evaluation (PVE) method. Next the data is analysed using factor analysis and logistic regression. Based on the results is concluded that citizens with lower trust in authorities prefer measures that directly target the consequences of the induced hazard. While citizens with more trust in authorities and more belief in the benefits of the activity causing the hazard are more open for measures that target the indirect consequences of the hazard. During this research, assumptions were made to construct the context of the PVE method. To improve the validity of this research it is suggested to repeat the research with different variables.Complex Systems Engineering and Management (CoSEM
Seeking answers: Understanding the academic performance of international students through an intercultural lens
No full textPowerpoin
Exploring the role of cross-cultural friendships in the internationalization of higher education in Canada: A case study
No full textPoste
