Auslegung von Düsen zum Gaseinblasen in Schmelzen

Erörterung der physikalischen Verhältnisse an den Düsenmündungen, Ableitung der Strömungsgesetze unter Berücksichtigung der Reibung, Berechnung der erforderlichen Druckverhältnisse und Rohrquerschnitte. Auslegung, Projektierung und Optimierung von Düsen für die Praxis. Betriebskennlinienumrechnung auf verschiedene Gasarten. Vorgehen bei der Auswertung von Meßergebnissen. Bestimmung von Reibungsbeiwerten. Vergleich der Verhältnisse bei reibungsbehafteter (wirklicher) Strömung und einer gedachten reibungsfreien (isentropen) Strömung.     

Mobile system for extracting spilled hazardous materials from excavated soils

A technique was evaluated for the scrubbing or cleansing of excavated soils contaminated by spilled or released hazardous substances. Laboratory tests were conducted with three separate pollutants (phenol, arsenic trioxide, and polychlorinated biphenyls [PCB's]) and two soils of significantly different character (sand/gravel/silt/clay and organic loam).The tests show that scrubbing of excavated soil on site is an efficient approach for freeing soils of certain contaminants but that the effectiveness depends on the washing fluid (water + additives) and on the soil composition and particle-size distribution. Based on the test results, a full-scale, field-use, prototype system was designed, engineered, fabricated, assembled, and briefly tested under conditions where large (?2.5 cm) objects were removed by a bar screen. The unit is now ready for field demonstrations.The system includes two major soil scrubbing components: a water-knife stripping and soaking unit of novel design for disintegrating the soil fabric (matrix) and solubilizing the contaminant from the larger particles (?2 mm) and an existing, but re-engineered, four-stage countercurrent extractor for freeing the contaminants from smaller particles (<2 mm). The processing rate of the system is 2.3 to 3.8 m₃/hr (4 to 5 yd₃/hr), though the water-knife unit (used alone) can process 11.5 to 13.5 m₃/hr (15 to 18 yd₃/hr). The complete system requires auxiliary equipment, such as the EPA-ORD physical/chemical treatment trailer, to process the wastewater for recycling; under some circumstances, provision must be made to confine and treat released gases and mists. Treatment residues consist of skimmings from froth flotation, fine particles discharged with the used washing fluids, and spent carbon. The principal limiting constraint on the treatability of soils is clay content (high weight-percent), since breaking down and efficiently treating consolidated clays is impractical or not economically attractive. Most inorganic compounds. almost all water soluble or readily oxidizable organic chemicals, and some partially miscible-in-water organics can be treated with water or water plus an additive.During limited laboratory extraction tests, phenol was very efficiently removed from both organic and inorganic soils, whereas PCB and arsenic clung more tenaciously to the soils and were released less readily into the washing fluids. The extent to which the system has practical, cost-effective utility in a particular situation cannot be determined until preliminary, bench-scale lab work has been performed and acceptable limits of residual concentrations in the washed soil are adopted. Laboratory tests show that soil scrubbing has the capability of vastly speeding up the release of chemicals from soils, a process that occurs very slowly under natural leaching conditions.Note that this system requires excavation of the soil, which can subsequently be replaced or transported to a low-grade landfill. In situ washing of contaminated soil, a process in which the contaminated area is isolated for example, by grouting, and then water-flushed with removal of the wash water at a well-point is an alternative. The overall efficiency of the soil washing system is greater than that currently being achieved by in situ methods.Based on the laboratory program, a series of steps (water-knife size reduction; soaking; countercurrent extraction; hydrocyclone separation; and waste fluid treatment for reuse) was selected as the most suitable process sequence for the prototype system. The system was constructed for the U.S. (EPA) and is now being subjected to field evaluation. However, soils rich in humus, organic detritus, and vegetative matter can present special problems in the extraction of certain hazardous substances, which may not partition between the solid and fluid phases to a practical and necessary extent.     

Numerical solution of the obstacle problem by the penalty method

The penalty method is used to compute approximations of the solution of the obstacle problem. By coupling the penalty parameter ε and the discretization parameterh quasi-optimal error estimates in the energy-norm are derived.     

Die Dünnschicht-Chromatographie in der Wachsanalytik: Die Identifizierung der Wachsalkohole und -säuren

Thin-layer Chromatography in the Wax Analysis: The Identification of Wax Alcohols and Acids A thin-layer chromatographic method employing the following conditions has been developed for the separation of wax alcohols and acids. Adsorbent: Kieselgur G; impregnating solution: 0.5 vol% silicon oil + 10 vol% tetradecane in petroleum ether; stationary phase: tetradecane-silicon oil (Bayer PN 1000); C₁₄ to C₂₄: temperature 42° C; mobile phase: 90 vol% acetic acid, which is completely saturated with pure tetradecane at 42° C; C₂₂ to C₄₀: temperature 60° C; mobile phase: 96 vol% acetic acid, which is completely saturated with pure tetradecane at 60° C; detecting agent: 10% aqueous sodium hydroxide solution mixed with an equal volume of 0.1 molar (1.6%) aqueous potassium permanganate solution.     

Bücherschau

Ohne Zusammenfassung VDI     

Correlation between the content of volatile matter and mineral matter in hard coals

If coal is heated to 900 °C, in the absence of air the organic coal substance and the associated mineral matter are decomposed. The analytically determined volatile-matter yield includes the volatile decomposition products of both the coal substance and the minerals. The correlation between mineral matter and ash and the volatile-matter yield is derived, and its accuracy shown by evaluation of test results. Methods are proposed for calculating a value for the volatile matter dmmf for coals of a particular mine. Various formulae for calculating the volatile matter of coals to dmmf basis are critically considered. Finally, a generally applicable equation for calculating dmmf volatile matter is derived which can be used for classification.     

Test of the local effect model using clinical data: tumour control probability for lung tumours after treatment with carbon ion beams

The treatment planning approach used within the heavy ion tumour therapy project at GSI Darmstadt includes a biological optimisation, which is based on a biophysical model, the Local Effect Model (LEM). Here we show that the predictions of the LEM are in good agreement with clinical data obtained at the HIMAC in Chiba for the treatment of non-small-cell lung cancer, and the steep dose response for carbon ions is reproduced correctly. This steeper increase corresponds to an increasing RBE with increasing dose, which apparently is in contradiction to the systematics observed in general for in vitro measurements. A possible explanation of this discrepancy is based on the interindividual variation of photon sensitivity.     

Planung und Ausführung des Ersatzneubaus einer U‐Bahn‐Brücke in Berlin unter hohem Zeitdruck

Design and construction of a new bridge for the Berlin underground to replace an old structure under high time pressure. This paper is about the design and construction of a new bridge for the underground in Berlin. A new structure was necessary due to insufficient stability and serviceability of the old one. The project had to be carried out under high time pressure to avoid a decommissioning of the underground traffic. As a result of this the planning and execution phases were significantly reduced. Besides, the client provided the construction firm with the structural steel to be used for the superstructure, a potential for conflict that would need to be tackled. The project will be described from the design point of view.