Meßtechnik zur Charakterisierung von Gas/Flüssigkeits-Reaktoren

Measuring techniques for characterizing gas/liquid reactors . The article considers measuring techniques for the characterization of the phases in gas/liquid reactors. These include the velocity profile and turbulence in the continuous phase as well as holdup, size, and velocity of the dispersed phase. Also, methods for the determination of the specific interfacial area and the volumetric mass transfer coefficients are discussed. Measuring methods have made enormous advances in recent years. In spite of this, there is a lack of reliable methods, especially for use during reactions without disturbing the state of the reactor. It is suspected that probe technique will gradually fall into disuse and more and more attention will be focussed on contractless methods. This calls for further development of ultrasonic methods and methods relying on emission of light.     

Verbesserung des Vakuums in Isoliergefäßen aus Glas

Improving the vacuum would increase the insulation capacity of commercially available glass containers by a factor of about two. To do this, pressures of 10^?4 mbar must be attained. Different approaches were taken to meet this objective. As an alternative to today's commonly practiced sealing method, three possibilities are introduced which eliminate the necessity of pump stub narrowing which causes reduced conductance. Furthermore, depending on the sealing process used, the gases occuring during sealing are either avoided completly or they can at least be reduced by having the chance of exact temperature control resp. by a lower separation temperature. A completly different approach was taken by using Getters, of which a metal hydride on a TiVMn base proved especially suitable. It is activated by heat and can be integrated into the normal production process without any problem. Aside from a shorter pump period, the added advantage here is the containment of the gasses occuring during sealing as well as that of the longterm gasses.     

A device to measure the cross-sectional area of soft connectivetissues

A device has been designed and fabricated to measure the cross-sectional area of soft connective tissues ex vivo. It consists of two displacement transducers; one sensing tissue thickness and the other sensing width. Outputs are recorded (via an analog to digital interface) using a personal computer. Numerical integration of a thickness versus width plot computes cross-sectional area. This plot also provides a quality check of acquired data. This device has been successfully used in biomechanical studies of rabbit patellar tendons, rat medial collateral ligaments, and dissected specimens of human fascia.     

Selbstbestimmung

Ohne Zusammenfassung     

Anwendung von statistischen Prüfverfahren im Bereich der Mischtechnik

Application of statistical testing to mixing. Assessment of the homogeneity of mixtures of solids and determination of the necessary mixing times are performed with the aid of statistical testing methods. The results from the basis for necessary decisions. Since reliable statements are fundamentally impossible in mathematical statistics, all such decisions are, with a certain probability, false, i.e. involve some risk. In studies of mixing, the first kind of error concerns the risk of rejecting a mixture although its homogeneity satisfies requirements, while the second kind of error concerns the risk of accepting a mixture although its homogeneity is insufficient. It is shown that barriers can be introduced for both kinds of error, and how to do this. Both the sample size and the limits of the acceptance range for the sample variance are thus laid down. If no decision is to be made concerning acceptance or rejection of a given mixture, but information is merely required about the mixing quality after a given time then this is accomplished by statement of confidence intervals.