Output feedback stabilization of a class of uncertain internally delayed systems

This paper is concerned with the problem of output feedback stabilization of a class of uncertain internally (i.e. in the state) delayed systems, in which only the upper bounds of nonlinear uncertainties are given. The designs of both static and dynamic output feedback controllers are considered. Some sufficient conditions for the stabilization of closed-loop systems are proposed, based upon the use of Lyapunov's stability criteria     

DETERMINATION OF CHEMICAL COMPOSITION OF ANATOLIAN CAROB POD (CERATONIA SILIQUA L.): SUGARS, AMINO AND ORGANIC ACIDS, MINERALS AND PHENOLIC COMPOUNDS

ABSTRACT

Carob pod is the fruit of the carob tree (Ceratonia siliqua L. Fabaceae). The fruit and its products, sold both in large stores and local markets, contribute strongly to the diet of people living in the Mediterranean areas of Europe and Turkey. This study reports the composition of carob pods sampled in West and South Anatolia. Sucrose (437.3 mg/g dry weight), glucose (395.8 mg/g dry weight) and fructose (42.3 mg/g dry weight) were the major sugars identified and quantified in the fruit. Total phenolics (13.51 mg gallic acid equivalents [GAE]/g dry weight), proanthocyanidin (0.36 mg GAE/g dry weight), gallotannins (0.41 catechin equivalents [CE]/g dry weight) and flavanols (3.21 mg CE/g dry weight protein) content of the fruit were also determined. Gallic acid (3.27 mg/g dry weight) was the most abundant phenolic acid present in all three phenolic fractions (free, ester and glycoside) isolated from pods. Aspartic acid (18.25 mg/g dry weight protein) was the predominant amino acid in the pod protein fraction. Eight minerals were quantified in the fruit. Among the analyzed major minerals, K (9.70 mg/g dry weight) was the most abundant element present, and the pods were richer in Ca than in P and Mg. Levels of trace minerals were comparable to other plant species. The data are discussed in terms of the nutritional value of the carob pod.

PRACTICAL APPLICATION

The use of carob fruit and its food products in Turkey has been increasing in recent years. However, knowledge about the composition of carob fruit pod produced in Turkey as well as in Mediterranean countries is lacking. The present work describes a composition scale and the advantages to food technologists and consumers who use the fruit and its fruit products in their diets. The results of the study can also aid in the assessment of adequate compositional information for further studies.

     

INCIDENCE, SURVIVAL AND GROWTH OF LISTERIA MONOCYTOGENES IN READY-TO-USE MIXED VEGETABLE SALADS IN SPAIN

A total of 116 commercial samples of mixed vegetable salads, packaged in plastic bags, were examined for the presence of Listeria monocytogenes during storage at 4C. Commercial products, belonging to 4 different batches, were sampled over a period of one year and stored for 300 h at 4C in the laboratory. Different sets of enrichment and plating media were used to recover organisms, with subsequent identification by Pasco System and serotyping techniques. Out of a total of 70 control (noninoculated) samples, 21 (30%) were observed to contain Listeria monocytogenes, belonging to serotypes 3a and 3b. A study of salad inoculated with 10³ cfu/g Listeria monocytogenes showed that the initial inoculum increased less than tenfold over the experimental period (300 h). During storage of the product, CO₂ reached nearly 30% and O₂ was no longer detected at 60 h, due to the respiration of the vegetables. The pH inside the packages remained around 6. The specific growth rate in the salad was calculated using the Dmodel Program, which gave a rate of 0.003h^-1, a lower figure than that reported by other authors. This study found growth patterns different to those previously reported for salads with separate ingredients. Our results agree with previous reports that modified atmosphere does not greatly inhibit Listeria monocytogenes. This reflects a lower specific growth rate in this food compared to media, and illustrates the difficulty of validating, in complex food systems, mathematic models based on culture media .     

ROBUST ADAPTIVE MODEL PREDICTIVE CONTROL OF A SOLAR PLANT WITH BOUNDED UNCERTAINTIES

This paper presents the application of a robust adaptive control scheme to a distributed collector field of a solar power plant. The major characteristic of a solar power plant is that the primary energy source, solar radiation, cannot be manipulated. Solar radiation varies throughout the day, causing changes in plant dynamics and strong disturbances in the process. The controller uses a robust identification mechanism combined with a finite horizon receding controller to cope with the process dynamics having bounded uncertainties. The controller has been tested using a proven non-linear computer model of the field. Results obtained in the real plant are also shown. © 1997 John Wiley & Sons, Ltd.     

RETENTION OF FRESH ORANGE JUICE FLAVOR AND AROMA IN AN AQUEOUS DISTILLATE FROM VALENCIA ORANGE JUICE1

Freshly squeezed Valencia orange juice, distilled at low temperature and reduced pressure, yielded an aqueous distillate with the necessary balance of volatile flavor and aroma constituents to retain the fresh juice characteristics. Flavor comparisons by an experienced sensory panel determined that orange juice reconstituted by combining the aqueous distillate with the residual juice solids had significantly more fresh juice character than reconstituted commercial frozen concentrated orange juice; commercial not pasteurized single strength orange juice (SSOJ); pasteurized SSOJ, not from concentrate; canned SSOJ, from concentrate; or aseptically packed SSOJ, from concentrate. The panel also found no significant difference in fresh juice characteristics between freshly squeezed orange juice and distillate and residual solids recombined from the same juice sample. Fifty four volatile constituents were identified from the aqueous distillate of freshly squeezed orange juice.     

Heat Pipe Design Through Generalized Extremal Optimization

In this paper, an application of the Generalized Extremal Optimization (GEO) algorithm to the optimization of a heat pipe (HP) for a space application is presented. The GEO algorithm is a generalization of the Extremal Optimization (EO) algorithm, devised to be applied readily to a broad class of design optimization problems regardless of the design space complexity it would face. It is easy to implement, does not make use of derivatives, and can be applied to either unconstrained or constrained problems with continuous, discrete, or integer variables. The GEO algorithm has been tested in a series of test functions and shows to be competitive to other stochastic algorithms, such as the Genetic Algorithm. In this work, it is applied to the problem of minimizing the mass of an HP as a function of a desirable heat transport capability and a given temperature on the condenser. The optimal solutions were obtained for different heat loads, heat sink temperatures, and three working fluids: ammonia, methanol, and ethanol. The present design application highlights the GEO features of being easily implemented and efficient on tackling optimization problems when the objective function presents design variables with strong nonlinear interactions and is subject to multiple constraints.     

Kalman-Bucy filtering for stochastic Volterra models

In this paper a suboptimization procedure is formulated for Volterra-type equations by using the Kalman-Bucy filtering theory. The Volterra-type systems are, in general, of a time-varying and non-convolution nature, but we include the time-invariant and convolution cases