Robust stabilization of singular systems withH ∞-bounded uncertainty

In this paper the problem of robust stabilizing a linear, time-invariant singular system is studied. The characterization is given in terms ofH -bounded perturbations to the numerator and denominator factors of its normalized left coprime factorization. An optimal stability margin is provided in terms of the definition of the Hankel norm of a singular system. The Hankel norm is computed using two generalized Lyapunov equations.This research was supported by the Defense Advanced Research Projects Agency under contract MDA-972-93-1-0032 and MDA-972-95-3-0016.     

Addition of yogurt to wort for the production of spirits: Evaluation of the spirit aroma over a two-year period

Triggered by the development of lactic acid bacteria (LAB) during the production of Scotch whisky, this study examined the influence of yeast and LAB inoculation on whisky flavor. Four new spirits were produced using the same process. LAB were added as a form of a Greek yogurt's live culture. In each category (barley and rye), one sample was fermented with Greek yogurt while the other was fermented without it. The spirits were matured and analyzed at five different points. Results from gas chromatography-mass spectrometry (GC-MS) analysis showed basic volatile compounds, along with some important extra compounds with yogurt culture. The most obvious differences were observed in the concentration of butanoic acid, a characteristic acid in spirits undergoing lactic acid fermentation: to identify esters such as ethyl butanoate, ethyl isobutanoate, isoamyl butanoate, and 2-phenylethyl butanoate, they are not typical compounds in whisky.     

Functional stability of goats' milk yoghurt supplemented with Pistacia atlantica resin extracts and Saccharomyces boulardii

The present study describes the development of a functional goats' milk yoghurt, using Pistacia atlantica resin extracts and Saccharomyces boulardii, in an attempt to combine the beneficial effects of the milk, extract and probiotic microorganisms. Results demonstrated that Pistacia extracts promoted the survival of lactic acid bacteria and NMR spectra additionally revealed that the functional fatty acids can be retained during the shelf life of yoghurts, alongside with the other bioactive compounds. The organoleptic assessment revealed that there were no significant differences in flavour, body, texture and appearance between the different yoghurts.     

La1−xSrxMyFe1−yO3−δ perovskites as oxygen-carrier materials for chemical-looping reforming

The use of perovskites with the general formula La_1−xSr_xM_yFe_1−yO₃ (M = Ni, Co, Cr, Cu) as oxygen carriers for syngas generation from methane by Chemical Looping Reforming is investigated in the present work. The experimental study concerns the oxidation of a fuel, using the oxygen from a solid oxygen carrier, instead of oxygen from air. Subsequent oxidation of the reduced solid is performed either with gaseous oxygen or with water. In the latter case additional hydrogen is produced, which is very pure and therefore appropriate to be used in fuel cell applications. The performance of the candidate materials is ranked by taking into account the hydrogen and carbon monoxide yields during the fuel oxidation step as well as the amount of oxygen per mole solid (δ) that can be delivered reversibly to the fuel. The effect of the materials composition and of NiO addition is examined. The best performance was obtained with the La_0.7Sr_0.3Cr_0.1Fe_0.9O₃ sample mixed with 5% NiO. The H₂ yield was up to 90%.     

Physicochemical properties of a dressing-type o/w emulsion as influenced by orange pulp fiber incorporation

A low-in-oil dressing-type o/w emulsion incorporating a rich-in-fiber orange pulp commercial product, either in crude form or following comminution, was prepared and the rheological properties and physicochemical stability of the emulsion were studied. Interactions between the adsorbed at the droplet surfaces yolk proteins and the pulp surface constituents, possibly electrostatic in nature, resulted in extensive droplet aggregation. This was reflected in the dramatic increase of emulsion rheological parameter values, derived by applying the power or the Casson equation to shear stress-rate of shear data. Pulp incorporation resulted in an improvement of emulsion stability against creaming while the stability against droplet coalescence was only marginally affected. In addition, the rheological parameter values of the fortified with pulp emulsion exhibited an appreciable increase with storage, especially in the case of emulsions incorporating the crude pulp. These findings are combined with oil droplet or pulp particle size and ζ-potential data to probe the emulsion structure and explain its behavior during aging.