Theoretical and Experimental Analysis of a Laser Textured Thrust Bearing

In this article, a laser partially textured thrust bearing is theoretically and experimentally analyzed. An adiabatic model is developed in order to theoretically investigate the performances of the bearing. The bearing sample is partially textured both in radial and circumferential direction using the laser texturing process. The performance of the bearing (fluid film thickness and friction torque) is evaluated on a specially adapted test rig and the experimental results are compared with the theoretical model. A good agreement is found between the theoretical model and the experimental data. Also a comparison between a laser textured bearing and a bearing textured using the photolithographic method is presented.     

In-Operation Monitoring of the Soot Load of Diesel Particulate Filters: Initial Tests

Diesel particulate filters (DPF) are indispensable parts of modern automotive exhaust gas aftertreatment systems due to the stringent emissions legislation. For a fuel-efficient control strategy, it would be beneficial to determine directly and in-operation their actual trapped soot mass. Two novel approaches—based on the electrical conductivity of trapped soot particles—emerged recently. By measuring the electrical resistance between different single walls inside the filter, the soot load is determined with local resolution. The microwave-based technique is a contactless approach that gives an integral value depending on the soot mass in the DPF. We present investigations on loading and regeneration of DPFs in a dynamometer test bench applying both methods. The results are compared with each other and correlated with the differential pressure and the soot mass. Especially the microwave-based technique has a potential for serial application.     

Analysis of defect mechanisms in nonstoichiometric ceria–zirconia by the microwave cavity perturbation method

In this microwave study, the defect chemistry of ceria–zirconia solid solutions (CZO, Ce_1−yZr_yO_2−δ) was investigated at high temperatures by a resonant microwave method. Specifically, the effects of temperature and Zr content on the dielectric properties and defect chemistry mechanisms in CZO were analyzed. Experiments were performed on a series of different CZO powders (y = 0.2, 0.33, 0.50, 0.67). Measurements at 600°C and different oxygen partial pressures (p_O2 = 10⁻²⁶–0.2 bar) confirm a dominant n-type conduction of small-polarons in CZO due to the preferred formation of oxygen vacancies, which is also supported by a multimodal analysis. Polarization losses were found to be negligible in the GHz range. Furthermore, an increased relative permittivity was observed in CZO, which correlates with the concentration of oxygen vacancies in CZO. Our microwave study is the first to provide a comprehensive data set for the dielectric properties of CZO powder sample in a wide range of different conditions. In addition, the connection of dielectric properties to CZO defect chemistry mechanisms is presented. The results are in good agreement with findings in the literature and may contribute to a better understanding of microwave-based state diagnosis of CZO-based materials, as it discussed for three-way catalysts.     

IS QUALITY ENGINEERING AN OXYMORON?

It is my purpose in this editorial to offer some highly personal and likely controversial views on the state of statistics and the quality profession. These views are based on my personal experiences and prejudices-especially those of my 10 years as an independent statistical consultant. I wish to particularly absolve my current employer, Merck and Company, and my colleagues there of any guilt by association. The opinions rendered here are entirely my own and in no way represent Merck's practices or policies, Mea culpa.     

Scale-up von Destillationskolonnen

Scale-up of Distillation Columns. In spite of remarkable advances in the development of computer programs for calculations on distillation columns, it is frequently still impossible to design them without experimental testing. Economic constraints demand use of miniaturised test plant, thus enhancing the importance of laboratory measurements. A system is presented for scale-up of separation which required information from laboratory experiments, includes data from reference columns, and takes account of models of fluid dynamics and mass transfer. The special feature of this approach lies in the free choise of internals, both in the laboratory and in the designed column.     

Sliding friction behaviour of polymer-polymer material combinations

The intermolecular bonding energies of polymeric materials can be employed in the evaluation of sliding under conditions determined predominantly by adhesion. The effect at the interface of these energies can be evaluated by reference to the surface energy and to its polar and dispersion-related components. Wetting angle measurements were used to determine the work of adhesion for a group of polymer-polymer material combinations. An exponential relationship exists between the work of adhesion and the coefficients of friction of these combinations, these coefficients of friction being determined primarily by adhesion.