Automated analyser for monitoring trace amounts of volatile chloro-organic compounds in recirculated industrial water

An automated analyser of volatile chloro-organic compounds in water was constructed and tested using standard mixtures of dichloromethane and dichloroethane. It was based on continuous, countercurrent gas stripping of the liquid sample followed by periodic trapping of the analytes on two traps alternately connected to the bubbler outlet, and thermal desorption. When one trap performed adsorption, the other underwent desorption and cooling. Analytes were detected by an ECD detector. Integration, calibration, calculations and overall operating cycle control was performed by a microcomputer. The instrument guarantees a 0.02 ppm Cl (w/w) detection limit, a 0-2 ppm detection range and 2 months of autonomous operation. Results are reported every 13 min.     

On Local Structural Stability of Differential 1-Forms and Nonlinear Hypersurface Systems on a Manifold with Boundary

In this paper we consider smooth differential 1-forms and smooth nonlinear control-affine systems with (n−1)-inputs evolving on an n-dimensional manifold with boundary. These systems are called hypersurface systems under the additional assumption that the drift vector field and control vector fields span the tangent space to the manifold. We locally classify all structurally stable differential 1-forms on a manifold with boundary. We give complete local classification of structurally stable hypersurface systems on a manifold with boundary under static state feedback defined by diffeomorphisms, which preserve the manifold together with its boundary. Date received: March 30, 2000. Date revised: October 30, 2000.     

Thermal elongations in steam turbines with welded rotors made of advanced materials at supercritical steam parameters

This paper presents research results obtained for supercritical steam turbines. The analysis aims to develop data, knowledge bases and procedures to support the operational control of these turbines. The control involves thermal and strength states of the main components. The thermal states and axial elongation in turbine rotors and casings are modeled, and the results are analyzed. The components under investigation are made of more than one material.     

Investigation of foam‐active polypeptides during beer fermentation

During ale fermentation there was an accumulation of total and hydrophobic polypeptides in the foam relative to the wort. Comparisons were made not only of the total and hydrophobic polypeptide contents but also of the molecular weights of these polypeptides present in wort, partially fermented wort and its concomitant foam. Wort, fermented wort and foam fractions had very similar polypeptide compositions with a major group having molecular weights of 40–43 kDa. Material of molecular weight in the range of 5–17 kDa and at 66 kDa was also detected. The polypeptides accumulated in foam displayed both hydrophobic and non‐hydrophobic character. The presence of yeast polypeptides in foam was confirmed. Comparison was also made between the fermentations of 10°Plato and 15°Plato wort. The results of the work may contribute to a better understanding of the mechanism of foam formation during beer fermentation, leading to reduced foaming and enabling an increase in the working capacities of fermenters. Copyright © 2004 Society of Chemical Industry     

Electron backscatter diffraction analysis of microstructural evolution in hot-deformed 6xxx series aluminum alloys

The electron backscatter diffraction (EBSD) technique is used to analyze the crystallographic grain orientation of deformed microstructures for 6xxx series aluminum alloy extrusions. In a partially extruded billet of aluminum, deformation zones with different crystallographic characteristics can be seen. Using compression testing performed on a Gleeble thermal-mechanical simulator under various conditions, the formation of different deformation zones is simulated. The EBSD technique is used to characterize samples deformed in compression testing to analyze the different deformation zones present in the extrusion process. Metal-flow analysis using EBSD is also applied to study the influence of different die designs on the surface texture of an extrudate. Microstructures from a profile that was formed with different die designs are examined. Analysis of a longitudinal weld present in typical hollow profiles is performed to determine the effect of metal-flow conditions on the resultant texture in the extrudate. The texture (or microtexture) measured from individual grains can be correlated to the orientation changes that occur during deformation.     

Acquisition of hierarchy-structured probabilistic decision tables and rules from data

Abstract: The paper is concerned with the creation of predictive models from data within the framework of the variable precision rough set model. It is focused on two aspects of the model derivation: computation of uncertain, in general, rules from information contained in probabilistic decision tables and forming hierarchies of decision tables with the objective of reduction or elimination of decision boundaries in the resulting classifiers. A new technique of creation of a linearly structured hierarchy of decision tables is introduced and compared to tree‐structured hierarchy. It is argued that the linearly structured hierarchy has significant advantages over tree‐structured hierarchy.     

Non-linear effect of 18-crown-6 in propylene oxide polymerization with potassium glycidoxide used as the inimer

A new initiating system containing potassium glycidoxide as the inimer and 18-crown-6 as the activator was used for propylene oxide polymerization. It was found that the rate of the reaction increased together with the crown ether concentration in a rather unexpected way. Two maxima of that parameter were found in the case of crown ether : inimer molar ratio equal to 3:1 and 6:1. On the other hand, the molecular weight of polymers showed two minima in those conditions. The heterogeneity of the reaction mixture and interactions between species present in the system could be responsible for the phenomena observed. The polydispersity of the polymers obtained was equal to about 1.2 and it was independent of the crown ether concentration.     

Experimental Studies and Thermodynamic Assessment of Ternary Cu-Pd-Sn Phase Relations Focusing on the Sn-Rich Alloys

Recently, Pd surface finishes over Cu substrates have been widely used in microelectronic packaging to prevent pad oxidation before soldering and to improve the bondability with Cu wires. The interfacial reactions between these newly developed Pd-based substrates and Pb-free solders, particularly Sn-based solders, are of practical importance. To completely understand interfacial reactions and phase transformation phenomena, phase equilibrium information on solders, intermetallics, and substrate materials are required. In this study, the phase equilibria of the Cu-Pd-Sn ternary system at 200°C was investigated by scanning electron microscopy, electron probe microanalysis, and electron backscatter diffraction. Particular emphasis was placed on the Sn-rich corner of the isothermal section. To analyze the experimental results, a thermodynamic assessment was performed using the computer coupling of phase diagrams and thermochemistry method.     

Problems and Solutions in 3-D Analysis of Phase Biological Objects by Optical Diffraction Tomography

Optical Diffraction Tomography is a technique for retrieving a 3-dimensional refractive index distribution from phase objects without destroying the structure of the samples. In the article we discuss the selection and implementation of full and limited angle version of tomographic reconstruction processes together with the analysis of different methods for gathering projections. We present two efficient implementations of full and limited angle tomographic systems including total processing paths and providing the examplary results of 3-D refractive index determination measurements of biological samples.