Density Measurements of Single Granules Using the Atomic Force Microscope

The density of single spray-dried granules has been determined with a new method based on atomic force microscopy (AFM). Spherical granules with a well-defined diameter are attached to the AFM cantilever, which acts as a beam-type spring, and the mass of a granule is estimated from the shift in the resonant frequency. The error of the measurements associated with the method was estimated to vary between 1% and 5%, depending on the size and shape of the granule. Density measurements of spray-dried WC–Co granules are presented, and the effect of a polymeric binder and dispersant on the consolidation during drying is discussed.     

Field test of superheater corrosion in a CFB waste boiler: Part I – Metal loss characteristics

The corrosion was investigated on a superheater test coil in a CFB waste boiler. The alloys ranged from ferritic steel T22 to nickel‐based Alloy 65 and the metal temperatures were between 460 and 540°C. The thickness of the deposit was alloy and temperature dependent. The low‐alloyed steels developed thick deposits at all temperatures while the deposit thickness increased with the temperature on the high‐alloyed steels and the nickel‐based alloy. The corrosion attack was alloy dependent and related to the deposit crest. The nickel‐based Alloy 65 was preferentially attacked directly under the crest of the deposit while the other alloys were preferentially attacked at the edge. The corrosion rate increased with temperature for X20, Alloy 304L, Alloy 310 and Alloy 825; decreased on Alloy 65; and was bell shaped on T22 and Alloy 28. Alloy 310 suffered from severe pitting corrosion in a line following the edge of the deposit crest. The best overall corrosion resistant alloy was Alloy 28.     

A 250-Mbit/s ring local computer network using 1.3-µm single-mode optical fibers

A 250-Mbit/s three-station fiber-optic ring local computer network was built and successfully demonstrated. A conventional token protocol was employed for bus arbitration to maximize the bus efficiency under high loading conditions, and a non-return-to-zero (NRS) data encoding format was selected for simplicity and maximum utilization of the ECL-circuit bandwidth.     

IEEE Standard 1057, Crame/spl acute/r-Rao bound and the parsimony principle

This paper deals with some fundamental properties of the sine-wave-fit algorithm included in IEEE Standards 1057 and 1241. Asymptotic Crame/spl acute/r-Rao bounds (CRBs) for three and four model parameters are derived under the Gaussian assumption. Further, the sine-wave-fitting properties of the algorithm are analyzed by the parsimony principle. A decision criterion whether to use the three- or four-parameter model is derived. It is shown that a three-parameter sine-wave fit produces a better fit than the four-parameter fit if the frequency is known to be within an interval related to the number of samples and the signal-to-noise ratio. By a numerical analysis, the theoretical results are shown to be also valid for the uniform noise model of quantization.     

Influence of load on the tribological conditions in piston ring and cylinder liner contacts in a medium-speed diesel engine

The present work is an attempt to determine the oil film thickness in a medium-speed four-stroke diesel engine with a cylinder diameter of 200 mm. Experimental research on this topic was found necessary due to the limited amount of published information available with reference to engines of the present size. The experimental part of the study was carried out as firing engine tests, with an instrumented piston, equipped with telemetric data transmission, and an instrumented cylinder liner in a 6-in-line test engine. The study was carried out for different parts of the four-stroke working cycle and for different levels of engine power output. The results were compared with the results of computer simulations, carried out using a commercial software package. The conclusions of the study comprise aspects on the formation and development of the oil film between the rings and the liner under a set of load levels together with the periodical fluctuation during different strokes of the working cycle.     

The effects of selected aldehydes, ketones and carboxylic acids on off-flavours in water

The effects of selected aldehydes, ketones and carboxylic acids on the development of off‐flavours in water were studied. Combinations of hexanal, octanal, 2‐octanone, 5‐nonanone, hexanoic acid and nonanoic acid were rated by the off‐flavour intensities they created in water at concentrations just at or below the threshold value of each analyte. Two different sensory panels evaluated the off‐flavours induced by different combinations of the analytes. The observations of the two panels agreed well. From these studies, it could be concluded that aldehydes play an important role in the development of off‐flavours intensities in water. There were synergistic effects between aldehydes and ketones, as well as between aldehydes and carboxylic acids. Small amounts of aldehydes and carboxylic acids – well below their respective threshold values – caused an increase in the off‐flavour intensity. No synergism between ketones and carboxylic acids could be observed.     

An approach to evaluate the energy performance of buildings based on incomplete monthly data

The energy performance of buildings has become increasingly important in the general strive to reduce the overall energy use, which is manifested in the Energy Performance of Buildings Directive launched by the European Union. An important first step is of course to identify and address buildings that have an energy saving potential. In order to achieve this, robust methods for evaluation as well as reliable energy key figures are needed.     

The effects of short-term parenteral nutrition on human liver protein and amino acid metabolism during laparoscopic surgery

Almost 2000 bovine milk fats were analysed by gas chromatography to investigate the influence of typical barn and pasture feeding of cows on trans-C18:2 isomers (with at least one trans double bond) including the conjugated linoleic acid cis delta9, trans delta11 (c9,t11) as well as the cis delta9, cis delta12 linoleic acid. Moreover, small cow herds were used to determine the influence of pasture Feeding with young and older grass as well as the impact of an energy deficit or the variation of quantity and technical treatment of fed rape-seed on the content of C18:2 isomers in milk fat. The contents of trans-C18:2 (w/o c9,t11) and c9,t11 in 1756 milk fats on average amounted to 0.63% resp. 0.75%. These contents increased from barn feeding, in winter with 0.46% resp. 0.45% over the transiton period in spring and late autumn with 0.66% resp. 0.76% to pasture feeding in summer with 0.87% resp. 1.20%. Milk fat samples from bulk milk obtained weekly during one year from 4 large West German milk collection areas confirmed and completed the data found for the 1756 milk fats. The percentage of linoleic acid with a mean value of 1.24 (n = 1756) varied irregularly during the different feeding periods. The content of the conjugated linoleic acid c9,t11 could be raised considerably up to triple the normal amount by different changes in feeding. However, the content of trans-C18:1 fatty acids was strongly increased as well, respectively.