Comparison between constant force and constant rate of feed in materialographic cut-off machines: Surface quality in relation to cutting speed, force, and rate of feed

With the precision cutting of materialographic samples, it is of the utmost importance that the cut surface exhibits as little deformation as possible. A number of factors influence the quality of the cut surface: type of cut-off wheel, rate of feed (mm/s), force (N), and specific pressure in the cut (N/mm²). In this study, cutting tests were carried out and two cutting principles, constant force and constant rate of feed, were compared. The resultant cut surfaces were examined using both light optical microscopy and atomic force microscopy, with the corresponding surface roughness measured on a profile meter. This study shows that when cutting workpieces of varying shape, the most uniform surface is obtained by using a constant rate of feed. Also, a constant rate of feed, combined with a high cutting speed, will produce surfaces with the least and most uniform deformation.     

Langzeitverhalten feuerverzinkter Stahlrohre in Trinkwasser unterschiedlichen pH-Wertes und unterschiedlicher Strömungsgeschwindigkeit

Long term performance of galvanized steel tubes in drinking water with different pH-value and flow velocity A 10 years' test program on galvanized steel tubes exposed to Berlin drinking water produced evidence that an undisturbed operation can only be guaranteed as long as the inner surface of the tubes is coated by metallic zinc. The zinc loss with time strongly depends on the pH-value and can be expressed by the mathematical equation . Due to the typical shape of the logarithmical function and its dependence on the pH-value a small increase of pH-value leads to an over-proportional increase in life-time of the zinc coating. pH = 7 leads to a total zinc loss within two years, whereas in the case of pH = 8 a zinc coating of 25–40 μm is still present after 10 year's time.     

Characterisation of structured hydrolysis catalysts for urea-SCR

In the current study the performance of different substrates with respect to pressure drop, mixing between catalyst channels and urea conversion efficiency were measured. An increase of the volumetric conversion efficiency was found when structured substrates were applied. Also the use of solid-urea aerosol was compared to the AdBlue technology and found to be a promising alternative.     

Temporärer Korrosionsschutz von Spannstählen mit filmbildenden Mitteln

Temporary corrosion protection of prestressing steels with film forming coatings Prestressing steels may be subjected to corrosive conditions during the manufacturing process at building sites. Due to this a risk of hydrogen induced stress corrosion cracking of the steels may arise. Electrochemical investigations and constant load tests have been carried out to show the suitability of different film forming coatings to be applied as temporary corrosion protection measures. The results indicated the applicability of two agents involved in the investigations without any risk for post tensioning purposes.     

The determination of maintenance strategies for plants subject to breakdown

When plant components fail the opportunity may be taken during the ensuing shut down to carry out maintenance on other components which have not yet failed. The choice of components for this opportunity maintenance depends on the probability distributions of their residual operating lives which may, in turn, be influenced by the process operating conditions. Three methods are described for determining the strategy of opportunity maintenance which will maximize the overall performance of the plant. The problem posed in the form of a stochastic decision tree is treated by a branch and bound procedure using first a Monte Carlo simulation and secondly multidimensional numerical integration formulae to account for the stochastic variables. The third method treats the problem as a Markov decision process. This proves to have computational advantages particularly when treating broad component life time distributions and long planning periods. Furthermore, the dynamic programming nature of the Markov procedure yields maintenance strategies for all defined states of the system from a single computational run.     

Margin-based first-order rule learning

We present a new margin-based approach to first-order rule learning. The approach addresses many of the prominent challenges in first-order rule learning, such as the computational complexity of optimization and capacity control. Optimizing the mean of the margin minus its variance, we obtain an algorithm linear in the number of examples and a handle for capacity control based on error bounds. A useful parameter in the optimization problem tunes how evenly the weights are spread among the rules. Moreover, the search strategy for including new rules can be adjusted flexibly, to perform variants of propositionalization or relational learning. The implementation of the system includes plugins for logical queries, graphs and mathematical terms. In extensive experiments, we found that, at least on the most commonly used toxicological datasets, overfitting is hardly an issue. In another batch of experiments, a comparison with margin-based ILP approaches using kernels turns out to be favorable. Finally, an experiment shows how many features are needed by propositionalization and relational learning approaches to reach a certain predictive performance. Editors: Stephen Muggleton, Ramon Otero, Simon Colton.     

INDUSTRIAL THROUGH-AIR DRYING OF NONWOVENS AND PAPER BASIC PRINCIPLES AND APPLICATIONS

The requirements for drying and thermobonding equipment working on the basis of the hot air flow-through system vary considerably due to the large variety of nonwovens qualities, production methods and required production speeds. It is therefore necessary to construct diverse drying systems in order to be able to offer appropriate machines for the desired purposes. Optimum heat and mass transfer from the penetrating air to the permeable material to be dried is ensured by through-air drying

Following Hans Fleissner's invention of the through-air system for drying of textiles and its practical application in the perforated drum dryer for more than 50 years a second engineering breakthrough for the paper and nonwovens industry has been achieved by Gerold Fleissner with the high-tech through-air drum

This paper presents various possibilities of air flow through the material and provide criteria to facilitate selection of the proper drying system