Reach Probability Estimation of Rare Events in Stochastic Hybrid Systems

This thesis conducts a series of interrelated research studies on reach probability estimation of rare events for stochastic hybrid systems. Chapter 1 explains that the motivation for these studies stems from the need to assess safety and capacity of a design for a future Air Traffic Management (ATM) concept of operations (ConOps). The safety...

Interacting Particle System based estimation of reach probability of General Stochastic Hybrid Systems

For diffusions, a well-developed approach in rare event estimation is to introduce a suitable factorization of the reach probability and then to estimate these factors through simulation of an Interacting Particle System (IPS). This paper studies IPS based reach probability estimation for General Stochastic Hybrid Systems (GSHS). The...

Learning-enabled multi-modal motion prediction in urban environments

Motion prediction is a key factor towards the full deployment of autonomous vehicles. It is fundamental in order to assure safety while navigating through highly interactive complex scenarios. In this work, the framework IAMP (Interaction-Aware Motion Prediction), producing multi-modal probabilistic outputs from the integration of a Dynamic...

ConceptEVA: Concept-Based Interactive Exploration and Customization of Document Summaries

With the most advanced natural language processing and artificial intelligence approaches, effective summarization of long and multi-topic documents - such as academic papers - for readers from different domains still remains a challenge. To address this, we introduce ConceptEVA, a mixed-initiative approach to generate, evaluate, and...

On the application of strong thermoplastic–thermoset interactions for developing advanced aerospace-composite joints

In this study, an aerospace thermosetting composite was co-curing joined by Polyether-ether-ketone (PEEK) and Polyethylenimine (PEI) films, with an aim of developing advanced composite joints. The semi-crystalline PEEK films were surface activated upon a UV-irradiation technique to obtain a strong film–composite interface, while the amorphous...

Wind tunnel tests of a wing at all angles of attack

Tailsitters have complex aerodynamics that make them hard to control throughout the entire flight envelope, especially at very high angle of attack (AoA) and reverse flow conditions. The development of controllers for these vehicles is hampered by the absence of publicly available data on forces and moments experienced in such conditions. In...

Random Assignment Versus Fixed Assignment in Multilevel Importance Splitting for Estimating Stochastic Reach Probabilities

This paper focuses on estimating reach probability of a closed unsafe set by a stochastic process. A well-developed approach is to make use of multi-level MC simulation, which consists of encapsulating the unsafe set by a sequence of increasing closed sets and conducting a sequence of MC simulations to estimate the reach probability of each...

Adsorption of molybdenum on Zr-based MOFs for potential application in the ⁹⁹Mo/^99mTc generator

The potential of the metal–organic framework UiO-66 and its functionalized derivatives for their utilization in the ⁹⁹Mo/^99mTc generator was assessed. Molybdenum adsorption experiments, structure characterization, molecular simulations and column experiments with molybdenum-99 were carried out. The results showed that...

Wheel-Rail Interaction: Enhanced explicit finite element modelling, verification and validation

Nowadays, wheel-rail (W/R) interfaces are suffering from the practical problems (e.g. wear, rolling contact defects) with the increase of train speed and traffic density. For accurate prediction of wear and/or growth of rolling contact defects, rapid determination of detailed contact responses (i.e. contact stresses & strains) using...

Interacting Particle System-based Estimation of Reach Probability for a Generalized Stochastic Hybrid System

This paper studies estimation of reach probability for a generalized stochastic hybrid system (GSHS). For diffusion processes a well-developed approach in reach probability estimation is to introduce a suitable factorization of the reach probability and then to estimate these factors through simulation of an Interacting Particle System (IPS)....

Modelling verification and influence of operational patterns on tribological behaviour of wheel-rail interaction

Verification of the explicit finite element (FE) model with realistic wheel-rail profiles against the CONTACT model, which has not been sufficiently discussed, is performed by comparing the resulting shear stress, slip-adhesion area, etc., obtained from the two models. The follow-up studies using the verified FE model on the influence of the...

Thermospheric mass density variations during geomagnetic storms and a prediction model based on the merging electric field

With the help of four years (2002–2005) of CHAMP accelerometer data we have investigated the dependence of low and mid latitude thermospheric density on the merging electric field, Em, during major magnetic storms. Altogether 30 intensive storm events (Dstmin <?100 nT) are chosen for a statistical study. In order to achieve a good correlation Em...