Bayesian system identification for structures considering spatial and temporal correlation

The decreasing cost and improved sensor and monitoring system technology (e.g., fiber optics and strain gauges) have led to more measurements in close proximity to each other. When using such spatially dense measurement data in Bayesian system identification strategies, the correlation in the model prediction error can become significant. The...

Explainable Artificial Intelligence to Investigate the Contribution of Design Variables to the Static Characteristics of Bistable Composite Laminates

Material properties, geometrical dimensions, and environmental conditions can greatly influence the characteristics of bistable composite laminates. In the current work, to understand how each input feature contributes to the curvatures of the stable equilibrium shapes of bistable laminates and the snap-through force to change these...

Multi-Frequency Radar Signal Processing for Moving Target Detection

This paper presents algorithms for joint signal processing of data from two radars located on the rooftop of TU Delft: PARSAX, operating in S-band, and MESEWI, operating in X-band [1]. In particular, the problem of data alignment in space (2D map) and time is addressed by observing moving targets of opportunity in the high-resolution mode. After...

The Singular Optics of Random Light: a 2D vectorial investigation

In this thesis, we explore the physics of optical singularities. We investigate them in light waves propagating randomly in a planar nanophotonic chip. With a custom-built nearfield microscope, we map the electromagnetic field resulting from the interference of these light waves. Our technique gives access to the full vectorial and complex...

A Framework for Incorporation of Infeed Uncertainty in Power System Risk-Based Security Assessment

In this paper, a risk-based security assessment methodology is presented, which allows the assessment of operational security of a power system’s future state under uncertainty deriving from varying topology scenarios (contingencies) and forecast errors (loads and renewable infeeds). The methodology models input uncertaintywith a copula function...

An interferometric interpretation of Marchenko redatuming including free-surface multiples

We present an interferometric interpretation of the iterative Marchenko scheme including both free-surface multiples and internal multiples. Cross-correlations are used to illustrate the combination of causal and acausal events that are essential for the process of multiple removal. The first 4 steps in the scheme are discussed in detail, where...

A GPS inspired Terrain Referenced Navigation algorithm

Terrain Referenced Navigation (TRN) refers to a form of localization in which measurements of distances to the terrain surface are matched with a digital elevation map allowing a vehicle to estimate its own position within the map. The main goal of this dissertation is to improve TRN performance through better signal processing. More...

A method to suppress spurious multiples in virtual-source gathers retrieved using seismic interferometry with reflection data

Seismic interferometry applied to surface reflection data (with source and receivers at the surface) allows to retrieve virtual-source gathers at the position of receivers, where no source was shot. As a result of the crosscorrelation of all primary and multiple reflections, the virtual-source gathers contain retrieved physical reflections as...

Quality-factor and reflection-coefficient estimation using reflected surface waves

We propose a method for estimating the reflection coefficient of a subvertical boundary and the the quality factor of the medium between a receiver and the subvertical boundary. The method uses surface waves from transient deterministic sources and is inspired by the occurrence of non-physical arrivals in seismic-interferometry results due to...

Determining changes in CO2 saturation from time-lapse measurements using ghost reflections retrieved by seismic interferometry

One of the targets of time-lapse seismic monitoring of CO2 sequestration is to determine the parts of the reservoir reached by the injected CO2 and to estimate their saturation. Such information could be extracted from the time-lapse measurement using AVO or impedance information. But non-repeatability of the source positions and time-lapse...

Combined sewer overflows in urban areas - interpreting and comparing European CSO monitoring results

Since the initiation of environmental legislation, monitoring campaigns have been done to estimate the characteristic pollutant concentrations of combined sewer overflow water. Such local campaigns are expensive due to the large number of events which should ideally be followed. This study focused on whether available concentration ranges from...

The Quality of Lagged Products and Autoregressive Yule–Walker Models as Autocorrelation Estimates

The sample autocorrelation function is defined by the mean lagged products (LPs) of random observations. It is the inverse Fourier transform of the raw periodogram. Both contain the same information, and the quality of the full-length sample autocorrelation to represent random data is as poor as that of a raw periodogram. The autoregressive (AR)...

Using copulas for modeling stochastic dependence in power system uncertainty analysis

The increasing penetration of renewable generation in power systems necessitates the modeling of this stochastic system infeed in operation and planning studies. The system analysis leads to multivariate uncertainty analysis problems, involving non-Normal correlated random variables. In this context, the modeling of stochastic dependence is...

High dimensional dependence: Copulae, sensitivity, sampling

Energy function behavior in optimization based image sequence stabilization in presence of moving objects

In this paper, we address the registration of two images as an optimization problem within indicated bounds. Our contribution is to identify such situations where the optimum value represents the real transformation parameters between the two images. Consider for example Mean Square Error (MSE) as the energy function: Ideally, a minimum in MSE...

A study on methods to compare measured and calculated modal data

Fokker Space and Systems and the National Aerospace Laboratory NLR performed a study to integrate more systematically the experimental and analytical analysis of the dynamic behaviour of structures. The study focused on the correlation of experimental and analytical data, matrix and parameter updating methods. In this paper an overview will be...

The deterministic power-spectral-density-method for nonlinear systems

The Deterministic Power-Spectral-Density method can be derived from the Design Envelope Analysis of the continuous P.S.D.-method. It provides a method to determine a deterministic function that gives a maximum response equal to the P.S.D.-design load for linear systems. The P.S.D.-design load is undefined for nonlinear systems. In this report a ...

Correlation-Function Techniques: An analysis of their performance and capabilities

The interest in correlation-function techniques shown by a number of groups working at the RWS is mainly due to the two following reasons: 1) Boundary-values determination and 2) Prediction. For these reasons, preliminary studies were undertaken some time ago at RWS. As part of these studies, correlation functions between a number of stations on...