Thermisch induzierter Abbau von Disaccharid-Amadori-Verbindungen in quasi wasserfreiem Reaktionsmilieu

Ohne Zusammenfassung     

Hydrierende Vergasung von Kohle – Neuere Betriebsergebnisse

Hydrogasification of coal – recent operational results . The Rheinische Braunkohlenwerke AG has built and has been operating a semi-technical pilot plant for hydrogasification of coal in a fluidized bed. The objective is to develop a coal gasification process with hydrogen for producing directly substitute natural gas. Between 1976 and 1981, the semitechnical pilot plant having a capacity of 100 kg C/h was operated for about 22,900 h under test conditions, more than 9,500 h of which were under gasification conditions. During this time, approximately 1,400 metric tons of dry coal were gasified. The longest coherent operational phase under gasification conditions was 748 h in which 86.4 metric tons of dry lignite were gasified. Carbon gasification rates up to 82% and methane contents in the dry raw gas (free of N₂) up to 48 vol.-% were obtained. A detailed evaluation of the test results provided information on the influence of additional parameters on the efficiency dates of the gasifier and a considerable refining of the results obtained previously. Moreover, several components were tested for which no operational experience had previously been gained; these were newly developed devices, e. g. the inclined tube for feeding coal into the fluidized bed. Within the framework of scale-up work to large-scale coal gasification plants, a pilot plant having a capacity of approximately 6 t C/h will be commissioned in late 1982.     

Fluidized Bed Air Drying: Experimental Study and Model Development

The presented study describes the processes and mechanisms of batch fluidized bed drying. The influencing factors of hot air drying are theoretically and experimentally examined, in order to present the relations between temperature and humidity profiles and all other drying parameters. A physical model is presented to facilitate the calculation of the drying processes under defined conditions. Three succeeding drying stages are therefore modeled. Mass and energy balances including all components taking part in the process are formulated. The model clarities the drying process under the assumption of pure heat transfer mechanisms. It does not contain adaptive parameters and takes into account an inactive bypass fraction of the fluidization and drying medium. The evaluation of the model was successful for two fluidized bed plants with nominal widths of 100 mm and 400 mm. The experiments showed sufficient accuracy and transferability of the model to equipment of application‐oriented dimensions.     

Innovative User Interfaces in Automation Engineering by Application of Usability Engineering Methods Shown by the Example of a Three-Dimensional Plant Representation

This article is the first of 3 that focus on user-centered design and usability in the field of industrial process control. This article starts with an introduction to this special domain and sets out the need for user-centered design of innovative user interfaces. The MediaPlant research project is then introduced. This project aims to generate innovative user interface solutions for process control. The usability engineering methods presented are well known in relation to office application software and were applied in the course of the project to (a) evaluate the potential and application fields of innovative multimedia technology and 3-dimensional information presentation (described at the end of this article), (b) define innovative user interface building blocks for process control that can be applied across sectors (described in the second article, Komischke & Burmester [this issue]) and (c) develop human-centered user interfaces for controlling paper recycling plants (described in the third article, Epstein & Beu [this issue]).     

High-resolution venography of the brain using magnetic resonance imaging

The purpose of this study was to evaluate a non-flow related magnetic resonance imaging method to visualize small veins independent of arteries in the human brain. A long TE, high-resolution 3D gradient echo MR acquisition was used to highlight venous information. The method is based on the paramagnetic property of deoxyhemoglobin and the resulting phase difference between veins and brain parenchyma at long echo times. The MR magnitude images were masked with a phase mask filter to enhance small structure visibility.. Venous information down to sub-pixel vessel diameters of several hundred microns is visible. Venous data are displayed in an angiographic manner using a minimum intensity projection algorithm. Both superficial veins and deep white matter veins are visible. The method has been successfully applied in volunteers. Preliminary results in patients with cerebral arteriovenous malformations indicate its potential in clinical applications. The proposed method is easy to implement and does not require administration of a contrast agent or application of specially designed rf pulses to highlight the veins. Rather it exploits the intrinsic magnetic properties (BOLD-effect) and the prolonged T ^_2* of venous blood. The method may be of diagnostic potential in the assessment of arteriovenous malformations or other vascular venous lesions. © 1998 Elsevier Science B.V. All rights reserved.     

Real-time scheduling for energy harvesting sensor nodes

Energy harvesting has recently emerged as a feasible option to increase the operating time of sensor networks. If each node of the network, however, is powered by a fluctuating energy source, common power management solutions have to be reconceived. This holds in particular if real-time responsiveness of a given application has to be guaranteed. Task scheduling at the single nodes should account for the properties of the energy source, capacity of the energy storage as well as deadlines of the single tasks. We show that conventional scheduling algorithms (like e.g. EDF) are not suitable for this scenario. Based on this motivation, we have constructed optimal scheduling algorithms that jointly handle constraints from both energy and time domain. Further we present an admittance test that decides for arbitrary task sets, whether they can be scheduled without deadline violations. To this end, we introduce the concept of energy variability characterization curves (EVCC) which nicely captures the dynamics of various energy sources. Simulation results show that our algorithms allow significant reductions of the battery size compared to Earliest Deadline First scheduling.