Parametric probabilistic transition systems for system design and analysis

We develop a model of parametric probabilistic transition Systems (PPTSs), where probabilities associated with transitions may be parameters. We show how to find instances of the parameters that satisfy a given property and instances that either maximize or minimize the probability of reaching a certain state. As an application, we model a probabilistic non-repudiation protocol with a PPTS. The theory we develop allows us to find instances that maximize the probability that the protocol ends in a fair state (no participant has an advantage over the others). A preliminary version of this paper was presented at SEFM’04 [LMT04]. 05 April 2006     

Allocating point-to-point connections over point-to-multipoint optical channels

Optical channels are currently able to carry 10 Gbit/s and even 40 Gbit/s traffic flows. However, it is not usual to have such amounts of traffic between any pair of client nodes. This article proposes using point-to-multipoint optical channels for the allocation of point-to-point connections in transparent wavelength-routed optical networks. Specifically, when an optical connection between a source-destination node pair has to be established, the optical signal is also sent to some adjacent nodes by introducing passive optical splitters; in this way a light-tree is built. Then, the already established point-to-multipoint optical channel can be used to groom further point-to-point connections between the same source node and each of the other nodes composing the light-tree. The benefits of this strategy are 2-fold: first, the reduction of optical transmission equipments allowing cost savings with respect to the traditional typical point-to-point approach and, second, the optimization of the optical channels utilization meeting in such a way Traffic Engineering objectives. The merits of proposed approach are evaluated by simulation.     

Time-varying increasing-gain observers for nonlinear systems

A full-order state observer for a class of nonlinear continuous-time systems is presented as generalization of the high-gain observer for having a time-varying gain that is let to be small in the first time instants, increases over time up to its maximum, and then is kept constant. The global stability of the resulting estimation error is proved by means of a Lyapunov functional via a change of coordinate. The design of such an observer is obtained by solving a nonlinear programming problem and using series expansions to set the time-varying gain.     

Buffering-deflection tradeoffs in optical burst switching

A very important issue in optical burst switching (OBS) networks is the excessive burst drop when no suitable network resources are found during path reservation. In this study, a network scenario is evaluated in which AWG-based optical nodes are used as burst router nodes within the optical network. The two classical solutions to solve the burst contentions on the channels outgoing from the node are considered, that is, either based on buffering within the node, or by exploiting deflection routing. A performance evaluation is carried out to evaluate and compare these solutions for different network topologies with different node and traffic parameters. Our main contribution is to set numerical tradeoffs between burst deflection through the network and buffering in the node, so that a guidance in optical network design is provided where node buffering is inherently technologically limited.     

On the Linear Structure of Betting Criterion and the Checking of Coherence

We use imprecise probabilities, based on a concept of generalized coherence, for the management of uncertainty in artificial intelligence. With the aim of reducing the computational difficulties, in the checking of generalized coherence we propose a method which exploits, in the framework of the betting criterion, suitable subsets of the sets of values of the random gains. We give an algorithm in each step of which a linear system with a reduced number of unknowns can be used. Our method improves a procedure already existing in literature and could be integrated with recent approaches of other authors, who exploit suitable logical conditions with the aim of splitting the problem into subproblems. We remark that our approach could be also used in combination with efficient methods like column generation techniques. Finally, to illustrate our method, we give some examples.     

Relative quantification of <Emphasis Type="Italic">Vitis vinifera</Emphasis> L. varieties in musts by microsatellite DNA analysis

Varietal wines are defined as made primarily from a single variety of grape, which is identified on the label. However the inclusion of other varieties in their production is permitted under defined percentages. The fact that different grape varieties/varietal wines present far different economical values can attract fraudulent practices. Thus the development of methods, which allow the quantification of those varieties, is of crucial importance. The first approach to the method for the relative quantification of must containing two varieties based on microsatellite DNA analysis is presented. Quantification was achieved by densitometry measurements of the amplification products of the pooled varieties, obtained with loci VVMD6 and VVMD7, after their separation and staining on polyacrilamide gels. We have found that a good correlation between the proportion of each variety in must and the signal intensity of the alleles are dependent on the variety (varietal effect) and the microsatellite locus used. The relative quantification of musts can be accomplished by the presented method depending on the presence of overlapping alleles, and the composition of the varieties and their relative amounts.     

Diffusion bonding of SU 263

Using a specially constructed apparatus, diffusion bonding of SU 263 alloy was studied in the temperature range of 1123–1323 K and compressive stress of 90% of its yield strength at the corresponding temperatures to determine the relative importance of the process parameters, the mechanism(s) responsible for bonding and the joint characteristics. Bond quality was assessed by optical metallography and lap shear testing. The mechanism of bonding was evaluated by grain growth equation. The experimental results were compared with a model developed by Pilling [Pilling, J., 1988. The kinetics of isostatic diffusion bonding in superplastic materials. Mater. Sci. Eng. 100, 137–144] in which the void closure by creep flow and diffusion are considered. Quantified EPMA line scan analysis was carried out to confirm the bonding mechanism and to determine the composition at the interface.     

Estimation of rheological properties of gelato by FT-NIR spectroscopy

The control of gelato powder mixture production usually is carried out evaluating the gelato liquid phase. The rheological measurements from the present study were conduced on gelato unfrozen liquid phase in order to indirectly evaluate its rheological properties by FT-NIR spectroscopy applied on gelato powders. The calibration set was composed by samples obtained from different recipes having increasing percentage of thickeners, maintaining the proportions of the others compounds constant. After the NIR acquisitions the powders were mixed with warm milk, blended and than settled in order to obtain the unfrozen liquid phase needed for the rheological measurements. For each of the 60 tested recipes three batches with the same thickeners concentration were prepared. The flow curves were obtained with a rotational viscosimeter and were evaluated by using the Ostwald de Waele’s equation and the goodness of fit was evaluated by the R², which was above 0.95. Predictive models of rheological parameters were set up by means of PLS regressions in order to predict the apparent viscosity (η), the consistency coefficient (K) and the flow behaviour index (n) from spectral acquisitions. A high correlation of calibration was found between NIR spectra and apparent viscosity with R² of 0.943. A good correlation was also found between the NIR spectra and the consistency coefficient (K) and flow behaviour index (n), with a determination coefficient (R²) of 0.895 and 0.874, respectively.The good prediction of the models encourages applying them to reduce significantly the time of the powder mixing control during production.