Experimental Analysis of the Aluminium Melting Process in Industrial Cold Crucible Furnaces

Metals and Materials International - One of the promising technology that guarantee the high-purity of the processed metal is induction skull melting. The quality of the melting process within such...     

Decoupling and iterative approaches to the control of discrete linear repetitive processes

This paper reports new results on the analysis and control of discrete linear repetitive processes which are a distinct class of 2D discrete linear systems of both systems theoretic and applications interest. In particular, we first propose an extension to the basic state-space model to include a coupling term previously neglected but which arises in some applications and then proceed to show how computationally efficient control laws can be designed for this new model.     

The Influence of Polyhedral Oligomeric Silsequioxanes on Domain Microstructure in Polyurethane Elastomers

The influence of polyhedral oligomeric silsequioxanes (POSS) as covalently bound hybrid physical property modifiers on the segmental dynamics and morphology of segmented polyurethane elastomers has been studied by solid-state magic sandwich echo nuclear magnetic resonance (MSE-NMR), differential scanning calorimetry (DSC) and atomic force microscopy (AFM). A model system has been synthesized which incorporates diol functionalized POSS over a range of loadings into the hard-block of a methylene di-isocyanate - butane diol - poly(tetramethylene glycol) (MDI-BDO-PTMG) segmented PU elastomer. MSE-NMR has been employed to probe the segmental dynamics of the PU system as a function of POSS loading and it has been demonstrated that low levels of POSS as a substitute chain extender, both rigidify the hard-block phase of the PU and significantly alter both the phase morphology, mixing and structure of the inter-phase domains. These observations are supported by more classical AFM and DSC morphological characterization of the POSS-PU hybrid systems which show significant re-structuring of the phase domain structure of the PU and ordering of the crystalline hard-block domains. This work demonstrates the application of a multi-scaled experimental approach towards understanding the effects of three-dimensional, nano-scale cage moieties on the already complex phase structure of segmented polyurethanes. Through these efforts, new insight has been gained into the mechanisms by which low levels of a nano-material such as a cubic sesquioxane, can impact the phase separation and segmental dynamics of block ter-polymer polyurethanes.     

Fractionation analysis of manganese and zinc in tea infusions by two-column solid phase extraction and flame atomic absorption spectrometry

The fractionation pattern of Mn and Zn in the infusions of black and green teas was studied using the Amberlite XAD7 and the Dowex 50Wx4 sorbents connected in a series, after the thorough examination of the sorption and the desorption characteristics of the resins applied. Under the optimized conditions, the one step two column approach developed enabled to distinguish three different operationally defined classes of the metal species, namely the polyphenolic, the cationic and the residual metal fractions. The results indicate that Mn and Zn in tea infusions are predominantly present in the form of the cationic species (up to 80% or more, especially in the green teas). Both metals are also attached to the polyphenolic compounds and possibly to other macromolecules.     

Interaction of maize zein with wheat gluten in composite dough and bread as determined by confocal laser scanning microscopy

Protein body-free maize zein, when mixed at 35 degrees C (above its glass transition temperature range), significantly (p < 0.01) improved the rheological and leavening properties of sorghum-wheat composite flour dough, resulting in improved loaf volume. Confocal laser scanning microscopy was used to observe the structure of zein fibrils and the interaction between zein and gluten proteins in the composite dough and bread systems. Autofluorescence and immunolocalization techniques were used to locate gluten and zein, respectively. Optical sections were collected every 0.4 microm through the samples and digitally processed to produce reconstructed three-dimensional images. Results showed that zein fibrils form an outer layer that intermittently coats the gluten networks, thereby strengthening them. This type of microstructure is able to withstand the pressure exerted by gas cell expansion during yeast fermentation to increase loaf volume.     

Output feedback control of discrete linear repetitive processes

Repetitive processes are a distinct class of 2D systems (i.e. information propagation in two independent directions) of both systems theoretic and applications interest. They cannot be controlled by direct extension of existing techniques from either standard (termed 1D here) or 2D systems theory. Here, we give new results on the relatively open problem of the design of physically based control laws using an LMI setting. These results are for the sub-class of the so-called discrete linear repetitive processes which arise in applications areas such as iterative learning control.