Wolfram Herrmann

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With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests were used to examine the effect of 4 different surface conditioning methods: fine diamond bur, sandblasting, 5%(More)
The effect of 5 different surface conditioning methods on bonding of metal brackets to cast dental alloys was examined. The surface conditioning methods were fine (30-microm) or rough (125-microm) diamond bur, sandblasting (50-microm or 110-microm aluminum oxide [Al2O3]), and silica coating (30-microm silica). Fifty disc-shaped specimens of 5 different(More)
We present measurements of the spatial response of infrared dipole and bow-tie lithographic antennas. Focused 10.6-microm radiation was scanned in two dimensions across the receiving area of each antenna. Deconvolution of the beam profile allowed the spatial response to be measured. The in-plane width of the antenna's spatial response extends approximately(More)
We present measurements on the polarization response of Ni-NiO-Ni diodes coupled to asymmetric spiral antennas. Our data are for the wavelength dependence of the orientation of the major axis of the polarization ellipse over the wavelength range 10.2-10.7 mum. The data are well fit by a two-wire antenna model. We find that the modes excited on the antenna(More)
We present measurements at 10.6 microm that demonstrate electronic tuning of the polarization response of asymmetric-spiral infrared antennas connected to Ni-NiO-Ni diodes. Continuous variation of the bias voltage applied to the diode results in a rotation of the principal axis of the polarization ellipse of the spiral antenna. A 90 degrees tuning range is(More)
The performance data of a PV module are derived from the current-voltage characteristic measured under standard test conditions (STC). For this purpose, test laboratories as well as module production plants employ solar simulators which, depending on type and module size, display a more or less pronounced non-uniform distribution of irradiance in the test(More)
According to several basic principals of hermeneutic theory (theory of understanding natural languages) we describe the major fields of language acquisition in which anomalies of CPL children often can be found. Besides phonation and articulation there are morphological, psychomotoric, onomatopoetic, and isotopic disorders. Also a delay of understanding by(More)
A simulation of shading effects in arrays with different string configurations has been done. Simulation has been performed using as the basic unit the solar cell, modelled in direct bias by the conventional one exponential model, and in reverse bias by an equation previously validated in different types of photovoltaic cells reverse characteristics. The(More)