On the Uncertainty of Space Debris Trajectory Predictions

The goal of the research is to improve space situational awareness (SSA) for space debris objects, and to make space operations more sustainable and remain possible in the future. Vital to this awareness is understanding which objects are present, through space surveillance and tracking (SST), and where these objects will be in the future,...

Establishing the Influence of Methanol Fuelled Power Propulsion and Energy Systems on Ship Design

The adoption of alternative energy carriers is one of the key ways to meet the increasingly stricter emission regulations faced by shipping vessels from the international maritime organisation (IMO) and European Commission. To support this objective, this study examines the challenges and uncertainties associated with implementing a methanol...

Uncertainty Propagation in Bilinear and Polynomial System for Probabilistic Threshold Detection

Uncertainty can be defined as imperfect or unknown information arising in a stochastic environment. Due to the very limited knowledge, it is difficult to propagate and quantify various uncertainties affecting the system to its next step. As a result, it has been a challenge to consider multiple uncertainties affecting the system in various...

Effect of instrumentation position and direction inaccuracy on the calculation of virtual point transformed FRFs

This work comprises research in the field of Experimental Dynamics. This technique is currently used in the automotive area and is used to enhances the current state of FEM with the inclusive of test- based models. Building test-based models for EDS (Experimental Dynamic Substructuring) requires very accurate measurement, and this thesis...

Generating nested quadrature rules with positive weights based on arbitrary sample sets

For the purpose of uncertainty propagation a new quadrature rule technique is proposed that has positive weights, has high degree, and is constructed using only samples that describe the probability distribution of the uncertain parameters. Moreover, nodes can be added to the quadrature rule, resulting in a sequence of nested rules. The rule...

Holistically improving screening decisions under uncertainty in aircraft conceptual design and technology assessment: Insights on bottom-up uncertainty quantification and propagation and integrated socio-technical group decision making

In the highly uncertain environment of conceptual aircraft design and technology assessment and selection, making good decisions is of utmost importance. Aiming to contribute to improving decision quality, the problem was researched from both a technical as well as a socio-psychological perspective. In the technical perspective, the uncertainty...

Uncertainty quantification in particle image velocimetry

Particle image velocimetry (PIV) has become the chief experimental technique for velocity field measurements in fluid flows. The technique yields quantitative visualizations of the instantaneous flow patterns, which are typically used to support the development of phenomenological models for complex flows or for validation of numerical...

Quantifying coastline change uncertainty using a multi-model aggregation approach

Evolution of coastline position under the influence of natural and anthropogenic processes is directly linked to the development of seaside societies. In the context of coastal zone management, process-based morphodynamic models are often used topredict coastline evolution and support the decision-making process...

A dynamic emulator for physically based flow simulators under varying rainfall and parametric conditions

This work presents a method to emulate the flow dynamics of physically based hydrodynamic simulators under variations of time-dependent rainfall and parametric scenarios. Although surrogate modelling is often employed to deal with the computational burden of this type of simulators, common techniques used for model emulation as polynomial...

Towards effective emission regulations: A numerical and experimental study on flow measurement uncertainty in stacks

Accurate measurement of emissions (i.e. volume flow rate multiplied by concentration) is vital to the control and reduction of air pollution. We quantify the uncertainty of flow measurements by S-type pitot tubes in narrow exhaust stacks (diameter < 0.5 m) in support of recent European Union (EU) regulations for emissions from medium-size...

Statistical Impact Prediction of Space Debris: The Uncertainty Propagation Approach

Due to the increasing number of space debris objects in orbit around Earth, the need increases for accurate predictions of impact time and location. These predictions are inherently statistical due to the large number of uncertainties in predicting the atmospheric decay and entry trajectories of these objects. Currently, Monte Carlo methods are...

PIV uncertainty propagation

This paper discusses the propagation of the instantaneous uncertainty of PIV measurements to statistical and instantaneous quantities of interest derived from the velocity field. The expression of the uncertainty of vorticity, velocity divergence, mean value and Reynolds stresses is derived. It is shown that the uncertainty of vorticity and...

Improved Non-Intrusive Uncertainty Propagation in Complex Fluid Flow Problems

The problem of non-intrusive uncertainty quantification is studied, with a focus on two computational fluid dynamics cases. A collocation method using quadrature or cubature rules is applied, where the simulations are selected deterministically. A one-dimensional quadrature rule is proposed which is nested, symmetric, and has positive weights....

Efficient uncertainty quantification in computational fluid dynamics

When modeling physical systems, several sources of uncertainty are present. For example, variability in boundary conditions like free stream velocity or ambient pressure are always present. Furthermore, uncertainties in geometry arise from production tolerances, wear or unknown deformations under loading. Uncertainties in computational fluid...