Stärkebestimmung in Kindermehl

European Food Research and Technology -     

Spirituosen und Essig

European Food Research and Technology -     

Large area pulsed corona discharge in water for disinfection and pollution control

To investigate the efficiency of submerged pulse corona (SPC) discharges in water we built a laboratory scale, parallel-plate reactor that is part of a closed loop water circulation system. A pulsed voltage is applied across the electrodes. One of the electrodes is coated with a porous ceramic layer to create local field enhancements to initiate corona discharges. For energization of the SPC reactor a pulse generator was developed which is based on a capacitor discharge initiated by a semiconductor switch. A pulse transformer, followed by two magnetic pulse compression stages, produces voltage pulses with amplitudes of up to 30 kV at a pulse width of 0.3 μs. Simulation of the circuit behavior leads to good agreement with voltage and current measurements. Details of the pulse generator and first experimental results concerning the efficiency of radical production are presented. Depending on the conductivity of the water to be treated, pulse currents of > 600 A at a voltage of 20 kV to > 30 kV are obtained for electrode sizes of around 50 cm². The efficiency of the radical production is measured in terms of the hydrogen peroxide (H₂O₂) concentration, which is formed by recombination of hydroxyl radicals (OH.) at sufficiently high concentrations downstream of the plasma reactor. At pulse repetition rates of 20 to 100 Hz, H₂O₂ concentrations of several mg/l are produced, at efficiencies in the range of up to ?1 g/kWh.     

Relaxed multiple routing configurations: IP fast reroute for single and correlated failures

Multi-topology routing is an increasingly popular IP network management concept that allows transport of different traffic types over disjoint network paths. The concept is of particular interest for implementation of IP fast reroute (IP FRR). The authors have previously proposed an IP FRR scheme based on multi-topology routing called Multiple Routing Configurations (MRC). MRC supports guaranteed, instantaneous recovery from any single link or node failure in biconnected networks as well as from many combined failures, provided sufficient bandwidth on the surviving links. Furthermore, in MRC different failures result in routing over different network topologies, which gives a good control of the traffic distribution in the networks after a failure     

Automatic 3-D segmentation of internal structures of the head in MR images using a combination of similarity and free-form transformations: Part II, validation on severely atrophied brains

Studies aimed at quantifying neuroanatomical differences between populations require the volume measurements of individual brain structures. If the study contains a large number of images, manual segmentation is not practical. This study tests the hypothesis that a fully automatic, atlas-based segmentation method can be used to quantify atrophy indexes derived from the brain and cerebellum volumes in normal subjects and chronic alcoholics. This is accomplished by registering an atlas volume with a subject volume, first using a global transformation, and then improving the registration using a local transformation. Segmented structures in the atlas volume are then mapped to the corresponding structures in the subject volume using the combined global and local transformations. This technique has been applied to seven normal and seven alcoholic subjects. Three magnetic resonance volumes were obtained for each subject and each volume was segmented automatically, using the atlas-based method. Accuracy was assessed by manually segmenting regions and measuring the similarity between corresponding regions obtained automatically. Repeatability was determined by comparing volume measurements of segmented structures from each acquisition of the same subject. Results demonstrate that the method is accurate, that the results are repeatable, and that it can provide a method for automatic quantification of brain atrophy, even when the degree of atrophy is large.     

A versatile system for the generation and the development of speechcoding strategies in cochlear implants

A signal processor-based (DSP32C) stimulation system for cochlear implants has been developed. This system allows up to 14 stimulation channels (place principle) and conserves the time structure of the acoustic signal (periodicity principle). Any combination of these features is possible; in compressed analogue mode, pulsatile mode, or combinations of both. The system also takes electrical crosstalk into account caused by the electrical properties of the inner ear and compensates for it. Lateral inhibition strategies improve spatial resolution. Finally, the system offers an interface for the generation of quick continuous interleaved sampling strategies (CIS); up to 11000 pulses/s per channel     

Opposite side ERS-1 SAR stereo mapping over rolling topography

Opposite-side radar stereo images have been considered unsuitable for stereo viewing due to illumination differences which limit the ability to identify the same features in the image pair. In some contexts, like a rolling topography (slope less than 10°), the shadow, layover, and foreshortening effects, specific to radar images, will not be overwhelming with an opposite-side stereo pair. This paper reports on some issues of stereo viewing and plotting, as well as on quantitative results of mapping and features extraction from ascending and descending orbit ERS-1 SAR stereo images. Planimetric accuracy of 17 m and altimetric accuracy of 23.9 m have been achieved for lake shorelines and DEM extractions, respectively. Impacts of different parameters on the accuracy are also evaluated     

Theoretical and numerical investigation of flow stability in porous materials applied as volumetric solar receivers

This article reports results of a theoretical analysis as well as a numerical study investigating the occurrence of flow instabilities in porous materials applied as volumetric solar receivers. After a short introduction into the technology of volumetric solar receivers, which are aimed to supply heat for a steam turbine process to generate electricity, the general requirements of materials applied as solar volumetric receivers are reviewed. Finally, the main methods and results of the two studies are reported. In the theoretical analysis it is shown that heat conductivity as well as permeability properties of the porous materials have significant influence on the probability of the occurrence of flow instabilities. The numerical study has been performed to investigate the occurrence of unstable flow in heated ceramic foam materials. In the simulations a constant heat flow of radiation, that is absorbed in a defined volume, and constant permeability coefficients are assumed. Boundary conditions similar to those of the 10 MW Solucar Solar project have been chosen. In a three dimensional, heterogeneous two phase heat transfer model it was possible to simulate local overheating of the porous structure. The parameters heat conductivity, turbulent permeability coefficient and radial dispersion coefficient have been varied systematically. Consequently, for a heat flux density of 1 MW/m² a parameter chart could be generated, showing the possible occurrence of “unstable” or “stable” thermal and fluid mechanical behaviour. These numerical results are beneficial for the design of optimized materials for volumetric receivers.