Marking Estimation of Petri Nets With Silent Transitions

In this paper, we deal with the problem of estimating the marking of a labeled Petri net system based on the observation of transitions labels. In particular, we assume that a certain number of transitions are labeled with the empty string , while unique labels taken from a given alphabet are assigned to each of the other transitions. Transitions labeled with the empty string are called silent because their firing cannot be observed. Under some technical assumptions on the structure of the unobservable subnet, we formally prove that the set of markings consistent with the observed word can be represented by a linear system with a fixed structure that does not depend on the length of the observed word.     

Experience with model-based performance, reliability, and adaptability assessment of a complex industrial architecture

In this paper, we report on our experience with the application of validated models to assess performance, reliability, and adaptability of a complex mission critical system that is being developed to dynamically monitor and control the position of an oil-drilling platform. We present real-time modeling results that show that all tasks are schedulable. We performed stochastic analysis of the distribution of task execution time as a function of the number of system interfaces. We report on the variability of task execution times for the expected system configurations. In addition, we have executed a system library for an important task inside the performance model simulator. We report on the measured algorithm convergence as a function of the number of vessel thrusters. We have also studied the system architecture adaptability by comparing the documented system architecture and the implemented source code. We report on the adaptability findings and the recommendations we were able to provide to the system’s architect. Finally, we have developed models of hardware and software reliability. We report on hardware and software reliability results based on the evaluation of the system architecture.     

On Nonparametric Residual Variance Estimation

In this paper, the problem of residual variance estimation is examined. The problem is analyzed in a general setting which covers non-additive heteroscedastic noise under non-iid sampling. To address the estimation problem, we suggest a method based on nearest neighbor graphs and we discuss its convergence properties under the assumption of a Hölder continuous regression function. The universality of the estimator makes it an ideal tool in problems with only little prior knowledge available.     

Nitrate estimation in the denitrifying post-filtration unit of a municipal wastewater treatment plant: the Viikinm?ki case

In this work we present and discuss the design of an array of soft-sensors to estimate the nitrate concentration in the denitrifying post-filtration unit at the Viikinm?ki wastewater treatment plant in Helsinki (Finland). The developed sensors aim at supporting the existing hardware analyzers by providing a reliable back-up system in case of malfunction of the instruments. In the attempt to design easy to implement and interpretable sensors, computationally light linear models have been considered. However, due to the intrinsic nonlinearity of the process, also nonlinear but still computationally affordable models have been considered for comparison. The experimental results demonstrate the potential of the developed soft-sensors and the possibility for an on-line implementation in the plant's control system as alternative monitoring devices.     

Astringency sub-qualities of red wines and the influence of wine–saliva aggregates

Astringency is a sensory attribute, related to the quality and mouthfeel of red wines. However, the origin of astringency sub-qualities, such as the typical drying astringency found in immature grapes, is still unknown. Astringency of red wines with similar tannin content but different astringency sub-qualities, from different harvest dates, is studied. Astringency was characterised in terms of friction coefficient, polyphenol content, sensory analysis and tannin/salivary–proteins aggregates characterisation. A different evolution during ripening was found for both Cabernet Sauvignon and Carménère, and tannin–protein aggregates showed differences in size, shape and surface. The velvety sub-quality appears to be related to aggregates with low precipitation, and with specific surface characteristics as roundness and Feret diameter. Results from this work propose an effect of aggregates on sensory perception and opens the possibility to explore their effect on oral lubrication.     

Inhibition of colon adenocarcinoma cell proliferation by flavonols is linked to a G2/M cell cycle block and reduction in cyclin D1 expression

The moderate consumption of red wine has been proposed to reduce the incidence of colorectal cancer. Its anti-cancer action my in part be mediated by the actions of polyphenols on colon cancer epithelial cells. We show that a red wine phenolic (50 μg/ml) extract devoid of anthocyanins (removed to reflect polyphenol bioavailability to the large intestine) and the major red wine flavonols quercetin, myricetin, laricitrin and syringetin (50 μM) are capable of inhibiting the proliferation of colorectal epithelial adenocarcinoma cells. This anti-proliferative activity was partly mediated by the direct cytotoxic actions of flavonols and also their ability to cause a significant cell cycle blockage in G2/M. The anti-proliferative effects induced by flavonols were preceded, in most cases, by a strong and significant reduction of cyclooxygenase-2 (COX-2) and cyclin D1 expression. These results indicate that the observed inverse correlation between colon cancer and a moderate red wine intake may be partly mediated by the actions of red wine flavonols on the growth of cancer cells.     

Bed Sediment Characteristics in the Paraná and Paraguay Rivers

ABSTRACT

This paper presents a granulometric characterization of the Paraná and Paraguay rivers bed sediments. Samples obtained along 2,900 km of the thalweg of those rivers form the basis of this study. The main results and other features of the study are as follows: a) the bed sediment of both rivers is composed mainly of medium to fine well-sorted sands, with sizes in the Paraná slightly higher than those in the Paraguay river; b) the variations of mean diameters for both rivers are well correlated with the energy slopes. The correlation coefficient in the Paraguay river increases notably if the discharge and width/depth relationship variations along the channel are included in the regression; and, c) the origin of the transported sands could be related to the geologic characteristics of the Paraná river basin. An explanation is also suggested for the different bed sediment texture found in the Paraná de las Palmas and Paraná Guazú rivers in the lower delta. The explanation is based on the geomorphic processes that built that region of the Paraná river.     

Optimal control of continuous-time switched affine systems

This paper deals with optimal control of switched piecewise affine autonomous systems, where the objective is to minimize a performance index over an infinite time horizon. We assume that the switching sequence has a finite length, and that the decision variables are the switching instants and the sequence of operating modes. We present two different approaches for solving such an optimal control problem. The first approach iterates between a procedure that finds an optimal switching sequence of modes, and a procedure that finds the optimal switching instants. The second approach is inspired by dynamic programming and identifies the regions of the state space where an optimal mode switch should occur, therefore providing a state feedback control law.