Mathematical Modeling and Parameter Identification of a Planar Servo-Pneumatic Test Facility. Part II: Experimental Identification

The main objective of this paper is the identification of the inertia parameters of a rigid body under planar motion using a planar servo-pneumatic test facility designed for vibration tests. The hardware realization of the test facility used is discussed. The pneumatic components as well as the mechanical components of the test facility are described by linear and by nonlinear mathematical models, derived in Part I [1] of this paper. These model equations are used as identification hypotheses in the identification process. A comparison of time histories obtained by computer simulations of the nonlinear test facility model and by laboratory experiments shows that this nonlinear test facility model provides a realistic identification hypothesis for the estimation experiments. Based on different model hypotheses the inertia parameters of the test table and of the payload have been successfully identified from laboratory experiments. The relative estimation errors of the identified parameters are less than 10%.     

Bestimmung von Argon neben Stickstoff und Sauerstoff in pulvermetallurgisch hergestellten Werkstoffen mit einem modifizierten Tr?gergas-Hei?extraktionsger?t

Summary The modification of a commercial carrier-gas fusion instrument for the simultaneous determination of argon is described. In order to separate argon from nitrogen, a gas-chromatographic column with molecular sieve was incorporated between the absorption traps for H₂O and CO₂ and the thermal conductivity detector. A computing integrator was used for the evaluation of the detector signals. The calibration was done by introduction of defined volumes of dry air into the carrier-gas line. The conditions for the liberation of argon from samples of ODS-alloys and the separation from the other extracted gases were optimized. Results of analysis of powders and compact samples were compared with the results obtained by means of a vacuum-fusion instrument. In the concentration range 25 to 50 g/g argon the relative standard deviations were 1.5 to 3% (six determinations). With powders of 3 to 5 g/g relative standard deviations of about 8% were achieved. The limit of detection for 1 g samples was found to be ca. 0.5 g/g.     

Synthesis and comparative structural investigation of crystalline and liquid-crystalline phases of low molecular mass compounds and side group polymers I. Low molecular mass compounds

Low molecular mass compounds and analogous side group polymers with a thermotropic phase behaviour crystalline-smectic liquid-crystalline-isotropic have been synthesized for a comparative structural study. As characteristic features of the compounds a biphenyl group has been chosen for the mesogenic core and alkoxy parts of various lengths as terminal and spacer groups. The phase behaviour has been studied with differential calorimetric (DSC) measurements and polarization microscopic observations. The low molecular mass compounds form crystalline phases at room temperature and exhibit predominantly mosaic textures in the polarization microscope at elevated temperatures indicating high order of the packing of the molecules. The arrangements of the molecules in the crystalline and liquid-crystalline phase can best be described as layered structures according to X-ray diffraction measurements. A structural analysis of a solution grown single crystal provides valuable information on the conformation and packing of the compounds investigated in this study.     

On particle coalescence in latex films (II)

Particle coalescence in latex films is investigated by measuring the smearing out process of perdeuterated nPBMA latex particles in a matrix of protonated nPBMA using SANS. It is found that—at least in this system—there is massive interdiffusion of material of different latex particles. Diffusion constants for 70 °C and 90 °C tempering temperatures are determined. In addition, the effect of molecular mass, crosslinking and incompatibility of the matrix material is investigated. As expected, the interdiffusion decreases with increasing molecular mass, but, surprisingly, dense crosslinking of the matrix latex particles accelerates the smearing out process. Increasing incompatibility lowers the rate of the smearing out process.Dedicated to Professor Dr. Helmut Dörfel on the occasion of his 60th birthday.     

General theorems on rates of convergence in distribution of random variables II. Applications to the stable limit laws and weak law of large numbers

This part is concerned with the applications of the general limit theorems with rates of Part I, achieved by specializing the limiting r.v. X. This leads to new convergence theorems with higher order rates in the one- and multi-dimensional case for the stable limit law, for the central limit theorem, and the weak law of large numbers.