Anomalously large radial transport levels in fusion devices is commonly believed to be the cause of small-scale edge localized electrostatic drift wave turbulence. We review the basic drift wave instability mechanism and show how poloidally elongated structures can self-consistently emerge from the small-scale turbulent motions through envelope modulation governed by the cubic nonlinear ...

The storm index SYM-H, the solar wind velocity v, and interplanetary magnetic field Bz show no signatures of low-dimensional dynamics in quiet periods, but tests for determinism in the time series indicate that SYM-H exhibits a significant low-dimensional component during storm time, suggesting that self-organization takes place during magnetic storms. Even though our analysis yields no discernible ...

In this thesis, the concept of an emissive probe has been used to obtain the plasma potential in the low temperature plasma experiment NJORD. An emissive probe is a probe concept in which a wire is heated strong enough to emit a Richardson current. The probe is then swept through several voltage biases and thus, an I-V trace obtained. With the current from the emission and the collected current, ...

The purpose of this study was to extract, evaluate and select different multi-frequency polarimetric SAR and multi-spectral optical features to demonstrate the benefit of multi-sensor data fusion for forest applications. Multi-frequency fully Polarimetric SAR data at P-, L- and C-band and multi-spectral Landsat TM data acquired over the Nezer forest in France were used for demonstration. The scene ...

Synthetic aperture focusing is known to increase both the lateral resolution and signal-to-noise level of pulse-echo ultrasonic images. In this paper, the use of synthetic aperture imaging for detection and sizing of pitting in a plate is considered. It is assumed that a water layer is present between the transducer and the plate, and that the pitting is on the back side of the plate, seen from the ...

In this thesis we present a new semi-supervised classification technique based on the Kernel Entropy Component Analysis (KECA) transformation and the least absolute shrinkage selection operator (LASSO). The latter is a constrained version of the least squares classifier. Traditional supervised classification techniques only use a limited set of labeled data to train the classifier, thus leaving ...

We present an analysis of relatively strong Polar Mesospheric Winter Echoes (PMWE) under artificial electron heating that changes the PMWE intensity. A major purpose is to find reliable estimates of the relaxation time of the heater modified PMWE to their undisturbed state during the heater switch-off phase; the implications regarding charge/discharge mechanisms; and to exploit the diagnostic potential ...

Icing on wind turbines are known to lower their performance, but the exact relationship between wind, ice and power production is not known. In this thesis power loss due to icing on turbine blades at Aapua wind park is investigated for the winter season 2009-2010. The total loss is found to be 30%, whereof 25% is concluded being due to icing. Three different methods are presented to estimate ...

A widespread bottom-simulating reflection (BSR) defining the base of the gas hydrate stability zone (BGHSZ) exists on seismic data from the western Svalbard margin, including the Vestnesa Ridge, which is a mounded and elongated sediment drift NW of Svalbard to the north of the Molloy Transform. The BSR stretches from the continental slope to within few km of the mid-oceanic ridge system thereby ...