Ermittlung der dynamischen Werkstoffkonstanten von bituminös gebundenen Baustoffen

The evaluation of the dynamical properties of bituminous mixtures An experimental method for the evaluation of the dynamical properties of bituminous mixtures is presented. Because of their viscoelastic behaviour the design of a special testing device was necessary. In this paper the guiding ideas for this testing machine are developed. Moreover, some experimental results and experiences, which could be valuable for calculating the stresses in road constructions, are given.     

Synthesis of palladium nanoparticles using a continuous flow polymeric micro reactor

A continuous flow polymeric micro reactor, fabricated using a negative photo resist SU-8 on a 10 x 10 cm PEEK (polyetheretherketone) substrate by standard UV lithography, was utilized to synthesize palladium nanoparticles. The nanoparticles were characterized by Transmission Electron Microscopy, Selected Area Electron Diffraction and X-ray Diffraction. The Pd nanoparticles synthesized in the micro reactor were found to have a narrower size distribution when compared with those obtained by the conventional batch process.     

Fast branch & bound algorithms for optimal feature selection

A novel search principle for optimal feature subset selection using the Branch & Bound method is introduced. Thanks to a simple mechanism for predicting criterion values, a considerable amount of time can be saved by avoiding many slow criterion evaluations. We propose two implementations of the proposed prediction mechanism that are suitable for use with nonrecursive and recursive criterion forms, respectively. Both algorithms find the optimum usually several times faster than any other known Branch & Bound algorithm. As the algorithm computational efficiency is crucial, due to the exponential nature of the search problem, we also investigate other factors that affect the search performance of all Branch & Bound algorithms. Using a set of synthetic criteria, we show that the speed of the Branch & Bound algorithms strongly depends on the diversity among features, feature stability with respect to different subsets, and criterion function dependence on feature set size. We identify the scenarios where the search is accelerated the most dramatically (finish in linear time), as well as the worst conditions. We verify our conclusions experimentally on three real data sets using traditional probabilistic distance criteria.     

Zum überflutungsverhalten zwei- und dreiphasig betriebener Rührreaktoren

The flooding behaviour of two- and three-phase operating stirred reactors . The present state of research concerning the flooding behaviour of aerated fluids and suspensions is presented. The author's own investigations, undertaken partly on a semi-technical scale (tank diameter D = 1.5 m) show the most important parameters of this undesirable aerated state during the operation of stirred reactors. For a given stirrer speed the superficial gas velocity, the tank size, and the fluid viscosity are important. Solid particles sediment out when flooding is reached. An objective measuring method for determining the occurrence of flooding was adopted.     

The importance of accurate visibility parameterization during atmospheric correction: impact on boreal forest classification

Observation of the Earth's surface from spaceborne platforms is complicated by the various layers of the Earth's atmosphere that reflect, scatter, and attenuate electromagnetic radiation passing through them, thus influencing (upward or downward) the signal strength recorded at the sensor relative to the true quantity of radiance reflected from the observed surfaces. The magnitude and spatial distribution of atmospheric effects is non-stationary and will vary due to numerous factors. While the effect of these factors cannot be eliminated completely, the understanding of radiative transfer physics, atmospheric states, and electromagnetic wave propagation permits much of these effects to be appropriately modelled and minimized. Such corrections for atmospheric effects permit the extraction of more accurate physical properties of surface materials and states from imagery than if atmospheric effects were ignored. Modelling of atmospheric effects with radiative transfer models, however, requires appropriate parameterization. We explore the sensitivity of the important visibility parameter of the popular Atmospheric and Topographic Correction (ATCOR) model for atmospheric correction over boreal forest land cover. Further, we provide a methodology for estimating reasonable values for the visibility parameter in the event that this information is not readily available. Our sensitivity analyses, performed on Landsat 7 Enhanced Thematic Mapper Plus (ETM+) imagery from northern Québec and Ontario, rely on both incremental adjustments to the visibility parameter to assess the degree of atmospheric effect removal and the cascading effect on land-cover classification. We build confidence around our measures using a spatial bootstrapping analysis within each of the two images we analyse. Our analysis demonstrates that exceeding a magnitude of error of approximately 2 km in estimating a visibility parameter values can decrease classification accuracy by nearly 10%. Our assessments of the spatial structure of the mitigated atmospheric component within our scenes, testing for complete spatial randomness, clustering of like values, or evenness in value distributions are inconclusive, but hint towards more clustered results with greater magnitudes of parameterization error.     

Fracture resistance of a doped PZT ceramic for multilayer piezoelectric actuators: Effect of mechanical load and temperature

The fracture resistance behaviour of a doped lead zirconate titanate (PZT) ceramic after combined thermo-mechanical loading is investigated between room temperature (RT) and 400 °C, i.e. above the Curie temperature (T_C). The thermal- and stress-induced depolarisation effects due to domain switching have been assessed by the indentation method on bulk PZTs. This has been extended to multilayered actuators. Experimental findings show a depolarisation effect with the temperature, which is significantly enhanced when combined with mechanical loading. This partial or even full depolarisation of the PZT material below T_C leads to important anisotropy effects in the fracture resistance of the piezo-ceramic, which should be taking into account in the design of multilayer actuators where the direction of crack propagation (i.e. parallel or normal to electrodes) can affect the actuator functionality.