Support vector machines for surrogate modeling of electronic circuits

In electronic circuit design, preliminary analyses of the circuit performances are generally carried out using time-consuming simulations. These analyses should be performed as fast as possible because of the strict temporal constraints on the industrial sector time to market. On the other hand, there is the need of precision and reliability of the analyses. For these reasons, there is more and more interest toward surrogate models able to approximate the behavior of a device with a high precision making use of a limited set of samples. Using suitable surrogate models instead of simulations, it is possible to perform a reliable analysis in less time. In this work, we are going to analyze how the surrogate models given by the support vector machine (SVM) perform when they are used to approximate the behavior of industrial circuits that will be employed in consumer electronics. The SVM is also compared to the surrogate models given by the response surface methodology using a commercial software currently adopted for this kind of applications.     

Formal verification of wastewater treatment processes using events detected from continuous signals by means of artificial neural networks. Case study: SBR plant

This paper proposes a modular architecture for the analysis and the validation of wastewater treatment processes. An algorithm using neural networks is used to extract the relevant qualitative patterns, such as “apexes”, “knees” and “steps”, from the signals acquired in the reaction tanks. These patterns, which show changes in the signals trend, are mapped to events in the process and logged using an appropriate XML format. The logs, in turn, are considered traces of the execution of a manufacturing process and validated using tools commonly applied for the Verification of Business Processes. The system has been applied to the data collected from a Sequencing Batch Reactor (SBR) for municipal wastewater treatment, equipped with probes for the on-line acquisition of signals such as pH, oxidation--reduction potential (ORP) and dissolved oxygen (DO). A SBR has turned out to be a suitable case study since the commonly acknowledged criteria for monitoring the biological processes (nitrification and denitrification) can be expressed in the form or qualitative constraints, which are easily translated into formal rules. The process logs, hence, are matched against these rules, which act as filters and quality classifiers.     

Astronomy and Etruscan Ritual: The Case of the Ara della Regina in Tarquinia

The ancient town of Tarquinia is the key place of the Etruscan system of beliefs, since its foundations were credited to Tarchon, descendant of the Greek hero Herakles, founder of the Etruscan League, and discloser of the sacred texts of the Etrusca Disciplina. These were said to come from the infant oracle Tages, who sprang out from the terrain in front of Tarchon while he was ploughing a field. In order to gain a better understanding of the relationship between the archaeological records and the Etruscan symbolic world we investigate here on different orientations and on their possible symbolic meaning at the Ara della Regina, the sanctuary of Tarquinia. The main base appears to be related to the sun rising a decades before the spring equinox, while the Archaic altar, probably representing Tarchon’s cenotaph, was orientated to the setting of the constellation Herakles.     

Experimental validation of a simple approximation to determine the linewidth of a laser from its frequency noise spectrum

Laser frequency fluctuations can be characterized either comprehensively by the frequency noise spectrum or in a simple but incomplete manner by the laser linewidth. A formal relation exists to calculate the linewidth from the frequency noise spectrum, but it is laborious to apply in practice. We recently proposed a much simpler geometrical approximation applicable to any arbitrary frequency noise spectrum. Here we present an experimental validation of this approximation using laser sources of different spectral characteristics. For each of them, we measured both the frequency noise spectrum to calculate the approximate linewidth and the actual linewidth directly. We observe a very good agreement between the approximate and directly measured linewidths over a broad range of values (from kilohertz to megahertz) and for significantly different laser line shapes.     

Occurrence of ochratoxin A in raw ham muscle,salami and dry-cured ham from pigs fed with contaminated diet

Pork meat-derived products can contribute to the overall ochratoxin A intake, either by carry-over effect, or by environmental mould population cross-contamination. In order to assess the role of these different contamination routes, a study was carried out with pigs challenged orally with OTA contaminated feed at subchronical level. After slaughtering, thighs and minced meat from control and treated groups were transformed into dry-cured hams and salami, respectively, which were analysed for OTA determination after ripening. From collected data, the carry-over in muscle was generally low, whereas a significant contribution to the OTA contamination in dry-cured hams was due to toxinogenic mould population growing on their surface during ripening. Finally, a survey of different types of dry-cured ham (n = 110), from the Italian market, was performed, showing the occurrence of OTA on the surface portion in 84 out of 110 samples with a median value of 0.53 μg/kg and in the inner core in 32 out of 110 samples with a median value lower than 0.1 μg/kg.     

Preparation and Characterization of Nanostructured TiO2/Epoxy Polymeric Films

Summary: Titania‐containing coatings were prepared by cationic photopolymerization of an epoxy resin either by dispersion of preformed TiO₂ nanoparticles or by their in‐situ generation through a sol‐gel dual‐cure process. The kinetics of photopolymerization was evaluated by real‐time FT‐IR, studying the effect of the TiO₂ concentration. The properties of cured films were investigated, showing an increase of hydrophilicity on the surface of the coatings with increasing TiO₂ content. TEM analysis demonstrated that it is possible to achieve a significantly better control of the dispersion of the inorganic particles within the organic matrix by in‐situ generation of TiO₂, thus completely avoiding macroscopic phase separation and obtaining homogeneous, transparent coatings.

Bright‐field TEM micrograph for TIP20 dual‐cured film.     

Efficient autonomic cloud computing using online discrete event simulation

Interest is growing in open source tools that let organizations build IaaS clouds using their own internal infrastructures, alone or in conjunction with external ones. A key component in such private/hybrid clouds is virtual infrastructure management, i.e., the dynamic orchestration of virtual machines, based on the understanding and prediction of performance at scale, with uncertain workloads and frequent node failures. Part of the research community is trying to solve this and other IaaS problems looking to Autonomic Computing techniques, that can provide, for example, better management of energy consumption, quality of service (QoS), and unpredictable system behaviors. In this context, we first recall the main features of the NAM framework devoted to the design of distributed autonomic systems. Then we illustrate the organization and policies of a NAM-based Workload Manager, focusing on one of its components, the Capacity Planner. We show that, when it is not possible to obtain optimal energy-aware plans analytically, sub-optimal plans can be autonomically obtained using online discrete event simulation. Specifically, the proposed approach allows to cope with a broader range of working conditions and types of workloads.