Global stabilization of a class of delay discrete-time nonlinear systems via state and output feedback

This paper deals with stabilization of a class of delay discrete-time nonlinear systems through state and output feedback. We provide an explicit bounded state feedback law as an extension of the Jurdjevic-Quinn method, from nonlinear theory, to this class of systems. Next, we present a useful and systematic approach to design an observer for the same class of systems. Then, we show how the global stabilization problem via dynamic output feedback can be solved by using the two previous results. Finally, numerical examples are given to illustrate the effectiveness of the proposed design method.     

Energy management of a hybrid photovoltaic system

This work describes a new control strategy for active energy flow in a hybrid photovoltaic (PV) system. The method introduces an online energy management by a hierarchical fuzzy controller between energy sources that consist of a photovoltaic panel (PVP), the battery and the load. The fuzzy logic controller has been developed for power splitting between PVP and battery, and it makes decision to choose the switching chain rules and corresponding controller. Simulation test results illustrate improvement in the operation's efficiency of online state of the switches and the battery's state of charge (SOC) has been maintained at a reasonable level. Copyright © 2010 John Wiley & Sons, Ltd.     

Perfume‐containing polyurea microcapsules with undetectable levels of free isocyanates

Core‐shell polyurea microcapsules with a 40% fragrance load were prepared by interfacial polymerization of guanidine and a technical polyisocyanate prepolymer containing mainly the biuret trimer derived from hexamethylene di‐isocyanate (HDI). Residual free polyisocyanates were still present at a level slightly above 100 mg NCO functional group per kg as determined by liquid chromatography hyphenated with tandem mass spectrometry of HDI and of its biuret trimer. This level was decreased by a factor of about 10 when the polymerization process was allowed to proceed for a longer time and by a factor of about 500 when guanidine or NaOH were added to the microcapsule suspension to act as scavengers. In these cases, polyisocyanate conversion was observed to proceed for about one month when the microcapsules were stored at room temperature before reaching a plateau at a level below 1 mg NCO/kg. Overall, ammonia was the most efficient polyisocyanate scavenger as no residual HDI biuret trimer and only less than 2 μg NCO/kg as HDI were detected at the end of the process, a level which had dropped below the limit of detection of 0.25 μg NCO/kg after about 40 days of aging at room temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Usefulness of various biochemical and histochemical characteristics as indices of muscle type in lamb carcasses

Contractile and metabolic characteristics of five different muscles from an homogeneous group of seven lambs were studied. Muscle typing was assessed by measuring myofibrillar ATPase and lactate deshydrogenase activities, myosin (FM1, FM2, FM3, SM1, SM2) and LDH (M₄, M₃H, M₂H₂, MH₃, H₄) isoforms levels as well as fibre types composition (SO, SOG, FOG, FG). On this basis, muscles were classified as slow-twitch oxidative (diaphragm and supraspinatus), intermediate (triceps brachii), fast-twitch oxidative-glycolytic (longissimus dorsi) and fast-twitch glycolytic (tensor fascia latae). Discriminant factor analysis of data revealed that variables enabling a better discrimination of muscles (FG, SM1, FM2, FM1, H₄) exhibited the lowest efficiency to discrimate animals. Furthermore, in contrast to LDH isoforms and fibre type composition subsets of variables, myosin isoforms analysis allowed a quite total identification of muscle classes since, 97·5% of the muscles were well ranged in their respective classes. Although animals were zootechnically similar, animal variability was important and animal effect was essentially detected through changes in the following set of variables: M₃H, MH₃, SO and ATPase.     

Thermomechanical material parameters characterization of the superalloy PN 3601669-7 under low-velocity impacts

This work concerns the characterization of the thermodynamic behavior of the superalloy Airsist 215 (PN 3601669-7) containing cobalt. Such superalloys are used in aeronautical construction, in the hot parts of the turbine. They are frequently used for the production of the paddles. The parts in service are subjected to dynamic solicitations and thermal fluctuations over the course of time. They are responsible for modification and degradation of material properties. This can lead to the appearance of cracks and, in the long term, to the rupture of these parts. In this paper, a preliminary physical study is made on the appearance of the cracks, followed by experiments using shocks at ambient temperature and under a heating situation which simulates combustion. It is found that these dynamic loads have a significant impact on the development of the cracks that appear on the segments of the turbine nozzle. The study is devoted to the elastic shock of Hertz-Boussinesq extended to viscoelastic bodies by direct convolution of Riemann-Stielges. The interest resides in the local convolution and the distribution of stresses in the contact zone. The shock excitation method includes a deduced force in the load and disload phases. This force is an impulse which approaches a Dirac function. The sample can be modeled approximately by a system of one degree of freedom for natural frequency, damping and transfer function. The spectral response of the specified shock allows calculation of the damping. Every point of this spectrum gives the response for the linear system of the transfer function. Then, viscoelastic shock parameters are deduced.     

Biomarkers of meat tenderness: Present knowledge and perspectives in regards to our current understanding of the mechanisms involved

Biomarkers of the meat quality are of prime importance for meat industry, which has to satisfy consumers' expectations and, for them, meat tenderness is and will remain the primary and most important quality attribute. The tenderization of meat starts immediately after animal death with the onset of apoptosis followed by a cooperative action of endogenous proteolytic systems. Before consideration of the biomarkers identified so far, we present here some new features on the apoptotic process. Among them, the most important is the recent discovery of a complex family of serpins capable to inhibit, in a pseudo-irreversible manner, caspases, the major enzymes responsible of cell dismantling during apoptosis. The biomarkers so far identified have been then sorted and grouped according to their common biological functions. All of them refer to a series of biological pathways including glycolytic and oxidative energy production, cell detoxification, protease inhibition and production of Heat Shock Proteins. Some unusual biomarkers are also presented: annexins, galectins and peroxiredoxins. On this basis, a detailed analysis of these metabolic pathways allowed us to identify some domains of interest for future investigations. It was thus emphasized that mitochondria, an important organelle in the production of energy from carbohydrates, lipids and proteins are a central element in the initiation and development of apoptosis. It was therefore stressed forward that, in fact, very little is known about the postmortem fate of these organelles and their multiple associated activities. Other topics discussed here would provide avenues for the future in the context of identifying reliable predictors of the ultimate meat tenderness.     

A weighted mean excess function approach to the estimation of Weibull-type tails

A new class of estimators for the Weibull-tail coefficient is proposed. The estimators are based on linear combinations of log-spacings of the mean excess function evaluated at high levels. The asymptotic distribution of this new class of estimators is derived under some mild conditions on the weight function and a second order condition on the tail behavior. The finite sample properties of some estimators obtained with important special cases of the weight function are examined with a small simulation experiment.     

Implications of payment of fees for psychotherapy.

Considers the question of how the payment of fees by clients for psychotherapy and related psychological services influences therapeutic outcomes. Psychoanalytic theory and cognitive dissonance theory suggest that clients who pay for psychotherapy will benefit more than those who pay nothing. This question and related issues are discussed with reference to observations and experimental studies that have explored how fees influence psychotherapy. Presently, sufficient evidence does not exist either to support or refute most of the hypotheses that have been generated, including the one that clients who pay a fee benefit more than those who pay nothing. Explanations for this void in the research literature and suggestions for expanding the understanding of this domain are provided. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)