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We fabricated high-mesa waveguides consisting of Al 0:1 Ga 0:9 N cladding layers and an AlN/GaN multiple quantum well core layer using inductively coupled plasma dry etching. Suitable conditions for vertically abrupt profiles were determined with an excellent reproducibility by optimizing the ICP power, bias power, gas pressure, and gas component. The etching selectivity of the samples to the SiO 2 mask was 10, which is larger than previously reported values. Light propagation at 1.55 mm in the waveguides was also confirmed.

Laminated composites are increasingly used in aeronautics and the wind energy industry, as well as in the automotive industry. In these applications, the construction and processing need to fulfill the highest requirements regarding weight and mechanical properties. Environmental issues, like fuel consumption and CO2-footprint, set new challenges in producing lightweight parts that meet the highly monitored standards for these branches. In the automotive industry, one main aspect of construction is the impact behavior of structural parts. To verify the quality of parts made from composite materials with little effort, cost and time, non-destructive test methods are increasingly used. A highly recommended non-destructive testing method is thermography analysis. In this work, a prototype for a car’s base plate was produced by using vacuum infusion. For research work, testing specimens were produced with the same multi-layer build up as the prototypes. These specimens were charged with defined loads in impact tests to simulate the effect of stone chips. Afterwards, the impacted specimens were investigated with thermography analysis. The research results in that work will help to understand the possible fields of application and the usage of thermography analysis as the first quick and economic failure detection method for automotive parts.

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14.7Me V neutron capture cross-section measurements with activation technique.

Data from FG5 absolute gravimeters have been analysed using processing software developed by Edinburgh University. The work aims to understand apparent inconsistencies between relative and absolute observations and the variation of absolute gravity estimates outside the 10 nm s -~ to 20 nm . s -~ (10 nm . s -~ = 1 pGal) range expected for FG5 instruments. Data from FG5-103 at Edinburgh, Birkenhead, Teddington and Taunton, FG5-107 at Taunton, FG5-105 at Teddington and FG5-101 at Onsala, Sweden, have been reprocessed. Fitting time-distance pairs to an equation of motion without a vertical gradient of gravity gives an estimate for g at some fraction of the way down the drop. None of the current theories correctly predicts the observed fraction of 0,43, so accurate results can only be found by including the vertical gradient terms to obtain a value of gravity at the top of the drop. Observations of the vertical gradient at some absolute sites have shown it to be nonlinear, so that using the same value in the equation of motion as for datum corrections can lead to significant errors. Solving the full equation of motion should give a constant estimate of gravity for all lengths or starting positions of the drop. This is rarely the case in the samples analysed here and the estimates may vary by up to 250 nm s -~. Systematic site-and instrument-dependent structure in the time-position residuals biases the solution. Removing the stacked residuals produces gravity estimates which are constant and independent of the drop length or starting position. In order to find the gravity offset caused by the system response, the residuals are modelled by a small number of damped sinusoids.

TSR technique can be well used to investigate the response to a short heating pulse in the time domain. As the time, when the heat starts to accumulate above a defect, is characteristic for its depth, this technique is appropriate for creating a 3D map of the sample. A CFRP structure with different number of layers and with Teflon inserts was used to demonstrate this technique. In order to calculate the depth of the artificial delaminations and the thickness of the layers, the starting time of the accumulation is determined for each pixel separately, based on the maximum of the 2nd derivative of the fitted temperature-time function and a 3D map of the structure generated.