Zum Magnesiumabbrand in Eisenschmelzen

Erläuterung der Problematik des Magnesiumabbrands beim Bereithalten magnesiumbehandelter Gußeisen-Schmelzen. Diskussion von Messungen des zeitlichen Verlaufs des Magnesiumabbrandes. Theoretische Überlegungen zur Deutung der Messungen durch Verdampfung, geschwindigkeitsbestimmenden Transport zur Tiegelwand oder einen geschwindigkeitsbestimmenden Vorgang 1. Ordnung in der Tiegelwand. Schlußfolgerungen für die Praxis.     

Image data compression based on non-negative incoherent imaging systems

Channel and memory capacities are limited and expensive resources in optical communication. In this work we propose several approaches to reduce the required capacity by using the a priori knowledge about the optical system used to capture the spatial information. The a priori knowledge is related to the triangularlike shape of the optical transfer function and to its spectral symmetry. In our work we will demonstrate a reduction in memory capacity required for the same image quality or a resolution enhancement for the same physical memory capacity. We will also present a nearly all-optical implementation of these techniques.     

Rotational temperature of oxygen molecules in DC glow discharge in O2-Ar mixtures sustained in discharge tube made from Pyrex glass

The active DC glow discharge sustained in pure O₂ and O₂-Ar mixtures with Ar/O₂ concentration ratios up to 50% has been studied in a Pyrex discharge tube for pressures up to 500 Pa and for discharge currents up to 40 mA. The electric field strength and emission spectra parameters of the discharge were studied by means of the double-probe method and optical emission spectroscopy.The electric field strength was found to increase with the pressure and decrease with the discharge current, which is typical for DC glow discharges. Considering O₂-Ar mixtures, the values of electric field strength decreased with Ar/O₂ ratio.We have focused on the emitted radiation. The rotational temperature T_rot of molecular oxygen was determined from the well-resolved atmospheric A-band at 760 nm. The increase of the rotational temperature with increasing deposited power has been observed for all studied Ar/O₂ ratios. Moreover, it has been found that values of T_rot are independent of the mixture composition.     

Characterization of ageing behaviour of environmentally acceptable lubricants based on trimethylolpropane esters

Large amounts of lubricants having strong environmental effects are released into the environment. This has led to the development of so‐called ‘environmentally acceptable’ lubricants based on synthetic and/or native esters. The aquatic toxicity of these lubricants is low and they are readily biodegradable. However, the biodegradation rate can be reduced after application. The aim of this study is to understand the lower biodegradation rate and the processes occurring during application. The changes are quantified using elemental analyses, high performance liquid chromatography with evaporative light scattering detector and mass spectrometer, as well as a combined screening method consisting of Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and electrospray ionization mass spectrometry. The results of chemical analyses indicate that the main components are cracked, and double bonds of the main components are eliminated by oxidation causing polymerization effects. The intensity of these effects is dependent on the kind of use and the presence of additives. These modifications are responsible for the changes in the ecological and technical characteristics. Copyright © 2006 John Wiley & Sons, Ltd.     

Documentation services: an expanding future

The sophistication of documentation services has much increased in recent years with the advent of computerised retrieval systems. Here the author shows how this has also opened up the potential for better international information transfer by harmonising different data bases, a task already started within CIB. Mr. Stern is director of Byggdok, the Swedish Institute for Building Documentation, and is also a member of the CIB Board.     

Cytochemical characteristics of the golgi apparatus

Lectinocytochemistry provides a useful tool for localizing subcompartments of the complex reticular apparatus of Golgi. The technique is based on interactions of lectins with glycoconjugates present in the limiting membranes and luminal spaces of Golgi elements. Application of a series of lectins of different sugar specificities permits a differentiation between Golgi subcompartments containing glycoconjugates with different oligosaccharide side chains. These may be (a) different glycoconjugates or (b) glycoconjugates at different stages during synthesis or repair of their glycans. The lectinocytochemical studies with mannose-, glucose-, N-acetyl-glucosamine-, N-acetylgalactosamine-, galactose-, fucose-, and sialic acid-recognizing lectins revealed predominating patterns that labeled distinct, i.e., cis, medial, trans, and transmost, regions of the Golgi apparatus. A further refinement could be achieved by differential lectin-inhibition that enables a dissection of lectin binding reactions on the basis of their binding affinities. High-affinity binding reactions showed that subcompartments are not necessarily confined to one single Golgi subregion and may change their position from one to another subregion. Some of the patterns observed may be interpreted in relation to certain steps during synthesis and modifications of glycans.     

Holography in phase space

Holography is reformulated by using the framework of phase-space optics. The Leith-Upatnieks off-axis reference hologram is compared with precursors, namely, single-sideband holography. The phase-space representation of complex amplitudes focuses on similarities between different holographic recording schemes and is particularly useful for investigating the degree of freedom and the space-bandwidth product of optical signals and systems. This allows one to include computer-generated holography and recent developments in digital holography in the discussion.     

APPLICATION OF CHROMATIC MONITORING AS A PLASMA DIAGNOSTIC TECHNIQUE

This paper describes the application of chromatic monitoring of both laboratory and industrial plasmas. The light emitted from the nitrogen plasma generated in the different plasma sources was measured with an imaging spectrograph. The emission spectra were reduced to data points representing the chromatic coordinates of these spectra. The data compression makes this method attractive for monitoring plasma parameter changes. The aim of this work was to test the possibility of application of chromatic monitoring for plasma processing.     

Study of rotational temperature of oxygen molecules in H and T forms of DC glow discharge sustained in pure oxygen

The active DC glow discharge sustained in pure oxygen has been studied in a Silica discharge tube by means of optical emission spectroscopy and double-probe diagnostics for pressures 600, 750 and 1000 Pa and for discharge currents up to 40 mA. Two different forms of positive column of the discharge (high-gradient H form and low-gradient T form) were observed. Our investigation was focused on the variations of the rotational temperature T_rot determined from emission spectra of molecular oxygen (atmospheric A-band at 760 nm) in the dependence on the discharge current and on the pressure with respect to the existence of the two forms of the discharge. An increase of the rotational temperature with increasing discharge current has been observed. Moreover, higher values of T_rot were found in the H form compared with the T form.