Christian Witte

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The objectives of this research were to develop and evaluate an approach for object-oriented mapping of banana plantations from SPOT-5 imagery, and to compare these results to banana plantations manually delineated from high spatial resolution airborne imagery. Cultivated areas were first identified through large spatial scale mapping using spectral and(More)
Friction is an undesired phenomenon in many drive systems. Feedforward of a suitable estimate of friction is an effective method to compensate the friction-dependent position errors in the steady state. The speed of reconstruction of the real friction is crucial for the grade of improvements which can be achieved for the transient behaviour. A nonlinear(More)
The finite difference method is extended to calculate X-ray absorption fine structure (XAFS) for solid state copper. These extensions include the incorporation of a Monte Carlo frozen phonon technique to simulate the effect of thermal vibrations under a correlated Debye–Waller model, and the inclusion of broadening effects from inelastic processes. Spectra(More)
We show an electrical method to break open living cells amongst a population of different cell types, where cell selection is based upon their shape. We implement the technique on an optoelectronic platform, where light, focused onto a semiconductor surface from a video projector creates a reconfigurable pattern of electrodes. One can choose the area of(More)
In this Letter, we present the size effects on charge conduction in InN nanowires by comprehensive transport studies supported by theoretical analysis. A consistent model for highly degenerate narrow gap semiconductor nanowires is developed. In contrast to common knowledge of InN, there is no evidence of an enhanced surface conduction, however, high(More)
We demonstrate surface acoustic wave (SAW) induced microparticle manipulation in a microstructured disposable glass-polymer composite superstrate, positioned on a piezoelectric substrate with a single, slanted SAW transducer. An excited SAW was coupled from the piezoelectric substrate into the superstrate, which acted as a transversal resonator structure.(More)
An optoelectronic tweezing (OET) device, within an integrated microfluidic channel, is used to precisely select single cells for lysis among dense populations. Cells to be lysed are exposed to higher electrical fields than their neighbours by illuminating a photoconductive film underneath them. Using beam spot sizes as low as 2.5 μm, 100% lysis efficiency(More)
Supporting students with feedback and guidance while they work on networking exercises can be provided in on-campus universities by human course advisors. A shortcoming however is that these advisors are not continuously available for the students, especially when students are working on exercises independently from the university, e.g. at home using a(More)
E-vehicles are expected to become increasingly important in the logistics sector. Global use of delivery vehicles with combustion motors causes a significant percentage of total emissions and is responsible for climate change, shortage of fossil fuels and pollution in urban areas. Simultaneously, cargo volumes are increasing, especially in urban regions due(More)