## Overview Research Topics

The long term objective of the department is the realization of the IMMI project (Interpretation by Measuring, Modelling and Identification), since 1989. Beside this main project, which covers a broad spectrum of several related activities, also some other independent research topics are at stake.

### Identifying Reflections in High Frequency Structures

The goal of this work is to improve the modeling of Lumped Distributed Structures (LDSs) by obtaining a sensible aaccuracy with a reasonably low number of model parameters while identifying the reflections present.

### Developing wave-based calibration for vector network analyzers

### Current state-of-the-art in RF calibration

Calibration is an essential part of any RF, microwave and millimeter wave measurement process. The accuracy of a bare-bones high-frequency measurement instrument is jeopardized by the influences of non-idealities, cabling and instrument drift....

### Data-driven signal processing using the nuclear norm heuristic

Applications in signal processing and control theory are typically model-based and proceed in two steps. In the 'modeling' step, a mathematical model is built from the measured noisy data. In the 'design' step, the model is used to solve a specific application problem. In this project, we will...

### FRF measurements subject to missing data: quantification of noise, nonlinear distortion, and time-varying effects

Quantifying the level of nonlinear distortions and time-varying effects in frequency response function (FRF) measurements is a first step towards the selection of an appropriate parametric model structure. In this project we tackle this problem in the presence of missing data, which is an...

### Nonparametric identification of linear dynamic errors-in-variables systems

The present work handles the nonparametric identification of linear dynamic systems within an errors-in-variables framework, where the input is arbitrary, and both the input and output disturbing noises are white with unknown variances. Using the property that the frequency response function and...

### Carrier aggregation intermodulation distortions in Advanced Systems

Achieving greater throughput requires increasing bandwidth. However, due to frequency’s scarcity, the necessary bandwidth may not be available in one contiguous band. LTE Advanced use multiple bands for one user: that is carrier aggregation [1]. However power amplifier’s efficiency is only...

### Local bending stiffness identification of beams using simultaneous Fourier-series fitting and shearography

In this project, we present a novel method for the identification of the local bending stiffness of beams. We use shearography to capture measurements of vibrating beams, so the input data for the identification is the modal slope – the differential of the modal shape. The modal slope is fitted...

### Identification of time-varying biomechanical systems

This project aims at extracting models of human joints in a data driven manner. This is done in collaboration with the biomechanics group at the TU Delft, where experimental setups have been instrumented to apply force and position disturbances to joints (ankle, wrist and shoulder). Based on...

### Decoupling noisy multivariate polynomials in nonlinear system identification

In the field of system identification, one special type of nonlinear models are the so-called block-oriented models, and more specifically the Wiener-Hammerstein models. When identifying parallel Wiener-Hammer-stein systems, a multiple-input-multiple-output polynomial should be decoupled, that...

### Identifying parallel Wiener-Hammerstein systems by decomposing Volterra kernels

- To capture the nonlinear effects of the real world, the focus of system identification is shifting from linear to nonlinear dynamical models. Every nonlinear dynamic system with fading memory can be approximated with arbitrary precision by its Volterra kernel description, which generalizes ...

### BLA-based Design and Analysis of VCO-based Sigma-Delta Modulators

Nonlinear system theory is involved. The available theoretical frameworks depend on the assumed system properties and the applied signals. An example is the Volterra theory framework which uses a series expansion of the system’s behaviour around an operating point. This operating point can be...

### Linear parameter-varying modeling and decentralized fault diagnosis for large sets of interacting subsystem

Fault Detection and Isolation (FDI) systems aim at the early detection and localization of faults. They are the key for the establishment of condition-based maintenance on industrial processes, which allows for cost reduction, and a safer and more reliable operation. The research on FDI has been...

### Data driven fast measurements

Measurement techniques have fundamental speed and accuracy limitations. The speed and precision of a measurement device used in monitoring and control tasks determines the quality of the available data, which in turn limits the accuracy of models derived from the data. In this project, we...

### Identification of multiple reflections in high frequency structures

Necessity of identifying reflections is not only an interest for engineers working at high frequencies. Engineers from other societies such as geophysics, mine-field detections and civil engineering are also concerned about the reflections. While in these fields mainly identifying the positions...

### Integration of the Linear Parameter-Varying framework in the design of supply modulated high frequent power amplifiers

Modern power amplifier designs attempt to trade off the power efficiency and the nonlinear distortion of the amplifier. This leads to complex amplifier structures, such as supply modulated amplifies, where the drain supply of the transistor device is modulated in function of the envelope of the...