Covariance bounds for discrete-time linear systems with time-varying parameter uncertainty

This paper deals with the computation of upper bounds for the state covariance matrix of discrete-time linear systems subject to stochastic excitation and additive time-varying uncertainty in the system dynamic matrix. Such upper bounds are obtained as the stabilizing solutions of suitable H ∞ -type Riccati equations. A necessary and sufficient condition for the existence of such solutions is given in terms of the H ∞ -norm of a suitable transfer function. As for the computation of the optimal bound, it is demonstrated that the bounds are a convex function of a scalar parameter, so that efficient numerical schemes can be worked out.     

Connectionism and functionalism: the importance of being a subsymbolist

Abstract

In recent years the development of connectionist theories and of various subsymbolic approaches to the study of the mind, and the renewed interest in the relations between the study of the mind and the neuroscience have had significant repercussions on the philosophical foundations of artificial intelligence and cognitive science, and on important questions of the philosophy of mind. Various approaches to the problem of mental representations have been formulated, in some sense alternative to classic approaches of artificial intelligence and cognitive science. We suggest that the problem of modelling the reference of mental symbols from a cognitive point of view requires the abandonment of a purely symbolic approach, and the adoption of a subsymbolic level of representation. Some philosophical consequences of a subsymbolic level of this kind are discussed. After distinguishing between the problem of reference and that of intentionality (which cannot be solved positing a subsymbolic level of representation), we shall see how a subsymbolic approach can be compatible with a functionalist view of the mind, in the wider sense. Finally, some consequences of subsymbolic models of reference regarding the problem of the inverted spectrum are described.     

Generating graphical applications from state-transition visual specifications

In graphical applications, visual representations are mostly used in an ad hoc fashion with little or no underlying formal support. Due to this, no common methodology for handling visual and diagrammatic representations has emerged and formal techniques for their support are underdeveloped. Usually, a programmer develops a graphical application by applying a general-purpose visual programming environment and ad hoc implementing the application requirements. Then, big efforts are often required when the application has to be successively modified or extended. In this paper, we present a finite-automaton-based formalism for the specification of rapid application development (RAD) visual applications, which provides a formal basis in the visual application generation. A prototype tool, based on this approach, has been developed and it is currently being experimented on a variety of case studies.     

CHANGES IN FREE FATTY ACID AND DIACYLGLYCEROL COMPOUNDS IN SHORT-RIPENING DRY-CURED SAUSAGE

A study on lipolysis of Southern Italy short-ripened dry-cured sausages manufactured without and with starters was carried out. Samples were submitted to microbiological and chemical analysis during drying and ripening, whereas sensory analysis was performed at the end of the ripening. The starters, addition caused the inhibition of the Enterobacteriaceae. An increase of free fatty acids (FFAs) and diacylglycerols (DAGs) during the ripening was observed. The addition of starter did not affect FFA and DAG release. The DAG profile including 1,2- and 1,3-isomers was analyzed for the first time in dry-cured sausages. Oleic, linoleic and palmitic acids, and 1,2-, 1,3-palmitinolein, 1,2- and 1,3-diolein were the most abundant compounds in FFA and DAG, respectively. A decrease in the concentration of some 1,2-DAG and an increase of 1,3-OO and 1,3-OP species during the process was observed. Finally, the addition of starter cultures slightly influenced the sensory properties of sausages.

PRACTICAL APPLICATIONS

In this work the development and application of an analytical method for the determination of free fatty acids (FFAs) and diacylglycerols (DAGs) in sausages was achieved. DAGs are intermediate products of hydrolysis and also constitute a substrate for hydrolysis reactions leading to FFA release. These latter compounds undergo a series of reactions leading to the formation of low-molecular-weight products responsible for sensory properties of dry-cured sausages. Therefore, the assessment of these lipolysis products is a useful tool for evaluating the ripening process of dry-cured sausages.     

Regulatory Pricing Rules to Neutralize Network Dominance

This paper evaluates the effectiveness of several pricing rulesintended to promote entry into a network industry dominatedby an incumbent carrier. Drawing on the work of Cournot andHotelling, we develop a model of competition between two interconnectednetworks. In a symmetric equilibrium, the price of cross-networkcalls exceeds the price of internal calls. This ‘callingcircle discount’ tends to ‘tip’ the industryto a monopoly equilibrium as would a network externality. Byequalizing charges for terminating calls, reciprocity eliminatesdifferences between internal and cross-network prices and makesmonopoly less likely. Imputation counteracts an incentive bythe dominant network to ‘price squeeze’ a rivalby eliminating differences in the wholesale price of terminationand the implicit price for internal use. By increasing profitsof rival networks and increasing their subscribers‘ surplus,imputation supports additional entry. Finally, an unbundlingrule reduces termination fees charged by a dominant networkthat was engaging in pure bundling. Again, entry will be facilitatedas rival networks offer potential subscribers a more attractiverate schedule.     

EFFECT OF PROCESS VARIABLES ON THE QUALITY OF SWORDFISH FILLETS FLAVORED WITH SMOKE CONDENSATE

An alternative technique to traditional smoking of swordfish was evaluated. Fillets were dry salted and/or brine salted in 30% NaCl, and smoked by dipping in smoke condensate solution at different concentrations. Chemical (water‐phase salt, pH, total volatile basic nitrogen, lipid oxidation), microbiological (total mesophilic count and fecal coliforms count) and sensory analyses were carried out in order to establish which technique gave the best results in terms of sensory quality. The different salting techniques gave different water‐phase salt contents, which influenced the microbial growth and the production of volatile bases. The smoke condensate concentration was ineffective toward microbial growth, but it was a differentiating factor for sensory panel. The dry‐salted product smoked with 5% smoke condensate was preferred because it maintained the natural taste of fish, coupled with a pleasant flavor of smoke.