The stability region of the tubing performance relation curve

The tubing performance relation curve is a measure of well performance in gas well engineering. It describes the two-phase flow inside a well and as such is modeled as a two-phase one dimensional pipe flow. Convention claims that production points on the TPR curve to the right of its minimum are stable. There also exist claims about the region...

The stabilization and destabilization of Brouwer's Rotating Vessel

We beschouwen Brouwers roterende lichaam, een voorbeeld van een mechanisch systeem met het volgende paradoxale gedrag; zonder demping is er stabiliteit, met demping is er sprake van instabiliteit. Met modulatie van de hoeksnelheid wordt er een model afgeleid waarbij we pogen de instabiele gevallen te stabiliseren, hierbij is het meenemen van de...

Stability, Accuracy, and Robustness of the Time Domain Integral Equation Method for Radar Scattering Analysis

The aim of this thesis is to design a computational method that can be used in modern stealth technology. In particular, the computational method should be capable to simulate scattering of ultra-wideband radar signals for military aircraft constructed with ferromagnetic radar absorbent materials. A full-wave boundary element method has been...

Observations of barrier island length explained using an exploratory morphodynamic model

Barrier coasts display a chain of islands, separated by tidal inlets that connect a back-barrier basin to a sea or ocean. Observations show that barrier island length generally decreases for increasing tidal range and increasing basin area. However, this has neither been reproduced in model studies nor explained from the underlying physics. This...

Optimal error estimates of the local discontinuous Galerkin method for surface diffusion of graphs on Cartesian Meshes

In (Xu and Shu in J. Sci. Comput. 40:375–390, 2009), a local discontinuous Galerkin (LDG) method for the surface diffusion of graphs was developed and a rigorous proof for its energy stability was given. Numerical simulation results showed the optimal order of accuracy. In this subsequent paper, we concentrate on analyzing a priori error...

Oscillations and stability of a mass-varying system

In this paper the stability properties of the vibrations of a singular degree of freedom oscillator with a periodically and multi-stepwise time-varying mass are studied. The free vibrations and the vibrations due to two types of forcing are investigated.