Investigating Gasification Processes of Solid Fuels by in situ Gaspotentiometric Oxygen Probes

This paper describes a novel analytical method that applies a gaspotentiometric oxygen probe (GOP) for characterizing gasification behavior of solid fuels. On the basis of GOP signals a developed gasification model enables the determination of fuel‐specific properties, like effective reaction rate constant and overall activation energy. For its experimental validation two coal cokes were converted with four different gasification agents in a lab‐scale fluidized‐bed reactor. The results obtained will be discussed and compared with literature data. As this advantageous in situ measurement technique is fast, inexpensive, and easy to handle, it makes the GOP a predestined tool for monitoring and controlling gasification processes.     

A dipole antenna for interstitial microwave hyperthermia

An improved interstitial microwave antenna design was investigated in static phantom experiments at 915 MHz and different insertion depths. Compared with conventional interstitial antennas, the presented dipole microwave antenna shows heating patterns which are concentrated on the dipole irrespective of the insertion depth. By analogy to interstitial radiotherapy, the microwave antenna allows a high concentration of energy in the target volume with as little damage as possible to the healthy surrounding tissue. The undesired heating of healthy tissue along the feeding line observed with conventional interstitial antennas is avoided. A λ/4 sleeve on the feeding line (which does not radiate microwave energy itself to the surrounding tissue) transforms an open end, i.e. a high impedance at the generator end of the dipole antenna. The current flowing back along the outside of the outer conductor of the feeding line in the direction of the generator is zero at this point. Both dipole sections have the same terminating impedance. Since the λ/4 sleeve is mounted outside the antenna, its mechanical length is not restricted by the mechanical length of the antenna. It can be charged with dielectric materials of low dielectricity constants     

Verhalten des Stahles X 6 CrNi 18 11 unter kombinierter Kriech- und Wechselbeanspruchung bei 823 K

Experimentelle Untersuchung des Kriech- und Wechseldehnverhaltens des austenitischen Stahles X 6 CrNi 18 11 (Werkstoffnummer 1.4948) bei Beanspruchung durch Kriechen und Ermüden. Auswertung der Ergebnisse unter Anwendung der linearen Schadensregel. Vergleich mit Auslegungskriterien nach dem ASME BPVC.     

DSC-untersuchungen an PUR-ionomeren aus zwei makrodiolen

DSC-measurements were carried out with films prepared from dispersions of polyurethane ionomers, which were synthesized from two macrodiols, poly(tetramethylene oxide), poly(propylene oxide) or polyesters. Mixing of the two components was performed before the preparation of the NCO-terminated prepolymer, the chain extension or the dispersing step. Also two latices were mixed, which were synthesized using one macrodiol in each case. Films from latex mixtures always formed a two-phased soft segment. This confirms that the identity of the latex particles was retained during film formation. Mixing of two ionomers before the dispersing step always yielded a two-phased soft segment, independent of the mixibility of the two macrodiols or the respective NCO-terminated prepolymers. This indicates that each type of ionomer forms its own kind of latex particle.     

Experimental identification of friction and its compensation inprecise, position controlled mechanisms

Methodologies developed for experimentally determining accurate models for the nonlinear friction inherent in most mechanisms are presented. Alternative closed-loop controller strategies for decoupling the effect of friction in order to improve positioning accuracy are also given. The identification methodology is novel in the manner in which it extracts the nonlinear friction properties from the closed-loop errors via an iterative signal processing technique. The discussion is based on both theoretical modeling and on a practical position control problem that was substantially resolved in developing the methodologies. The application was a robotic gripper with a highly preloaded rack-and-pinion mechanism. Both measurement and control design methodologies to help systematically circumvent the problems of nonlinear friction in precise, position-controlled mechanisms are given     

Zur partialladung adsorbierter spezies der ti-amalgam/ti+-reaktion

The following paper reports on the partial charge of adsorbed species of the T1-amalgam/T1⁺-reaction. l- and f-coefficients were determined in a broad potential range and at low reactant concentrations and adsorption densities by impedance measurements. The method of evaluation is presented in detail, including a discussion of the relation of (non-equilibrium) partial charge transfer model to Gibbs adsorption thermodynamics.