Co-ordinated economic and advance dispatch procedures

The paper deals with the problem of improving co-ordination between the online economic dispatch (ED) function and the very short-term advance dispatch (AD). Both procedures are formulated as optimal dispatching problems, but while a static model is used for the ED function, a dynamic model is employed in AD. The need to account for ramp-rate limits of thermal power generation even in the ED phase is satisfied by adding suitable penalty terms to the objective function of the classical ED problem. These penalties are proportional to the Lagrange multipliers associated with ramp-rate limits that are active at the AD solution. An efficient updating procedure is used to correct the penalization by taking the load forecast errors into account. The proposed co-ordination procedure can provide the snapshot ED with the long range perspective of AD without resorting to heuristic approaches. The procedure is validated by extensive testing carried out both on a small CIGRE test case and on a medium-large scale network representative of the Italian EHV system. Moreover, test results show that the CPU time requirements of the modified ED procedure are still suited to online applications     

Techniques for the mechanical characterisation of civil structures

Broadly speaking, structural defects include all those changes affecting a structure so that its behaviour is no longer in keeping with its intended use characteristics or differs from the behaviour it was originally designed for. In recent years, damage recognition and location methods, relying on the measurement of parameters that are indicative of a structure's mechanical behaviour, have benefitted from the introduction of innovative approaches, which make it possible to process and correlate an unprecedented wealth of measurble data. The aim of this work is to illustrate the basic problems associated with the different methods used for structural identification (parametric and non-parametric, linear and non-linear, with known and unknown inputs, etc.) and to report on some interesting applications for civil structural diagnosis.     

Influence of oxygen contamination on the surface tension of liquid tin

The surface tension of liquid tin has been measured by the sessile-drop technique as a function of temperature, in the range 232 T (°C) 800 and under different atmospheres. It is shown that oxygen strongly affects the surface tension values and that, under nominally very clean conditions, a considerable scatter of experimental results occurs. This scatter can be explained by taking into account kinetic factors, especially those related to the gaseous fluxes around the molten drop. By this procedure, a number of experimental results can be singled out, which corresponds to clean surface conditions. On the basis of these results, the following expression for surface tension politherm is proposed: (mN m^–1 = 581-0.13) (t-232).     

Context relevance assessment and exploitation in mobile recommender systems

In order to generate relevant recommendations, a context-aware recommender system (CARS) not only makes use of user preferences, but also exploits information about the specific contextual situation in which the recommended item will be consumed. For instance, when recommending a holiday destination, a CARS could take into account whether the trip will happen in summer or winter. It is unclear, however, which contextual factors are important and to which degree they influence user ratings. A large amount of data and complex context-aware predictive models must be exploited to understand these relationships. In this paper, we take a new approach for assessing and modeling the relationship between contextual factors and item ratings. Rather than using the traditional approach to data collection, where recommendations are rated with respect to real situations as participants go about their lives as normal, we simulate contextual situations to more easily capture data regarding how the context influences user ratings. To this end, we have designed a methodology whereby users are asked to judge whether a contextual factor (e.g., season) influences the rating given a certain contextual condition (e.g., season is summer). Based on the analyses of these data, we built a context-aware mobile recommender system that utilizes the contextual factors shown to be important. In a subsequent user evaluation, this system was preferred to a similar variant that did not exploit contextual information.     

A Realistic Computer-Simulated Brain Phantom for Evaluation of PET Charactenstics

To evaluate accurately the imaging characteristics of positron emission tomography (PET), a realistic computer-simulated brain phantom was developed. A cross-sectional slice from a human cadaver brain was chosen for its combination of gray matter, white matter, and cerebrospinal fluid (CSF) regions. The slice was photographed and digitized into a gray-level image with a video digitizer, boundary edges were located around cerebral structures in the digitized image, and each structural region was assigned a uniform pixel value dependent on both the cerebral parameter (e.g., blood flow, oxygen uptake, metabolic rate) under investigation and the type of structure (gray matter, white matter, CSF). Line integrals through the regions were generated at various angular and transverse positions according to specific physical characteristics (such as detector line-spread function) of a tomographic scanner configuration to create a set of simulated but realistic projection measurements. The set of projection measurements can be processed with any standard reconstruction program to create a tomographic image to reveal the effects of various PET characteristics. Investigations with this computer-simulated brain phantom have demonstrated its usefulness for examining the interrelations among neuroanatomical structure volume, tomographic spatial resolution, partial volume effect, and nonlinear parameter estimation. Transportability of the simulated phantom and the procedure to other medical imaging environments is described, and limitations of this simulation procedure are discussed.     

What Borromini Might Have Known About Ovals. Ruler and Compass Constructions

This paper is about drawing ovals using a given number of certain parameters. New constructions are displayed, including the case when the symmetry axes are not given. Many of these constructions make use of a recent conjecture by Ragazzo, for which a Euclidean proof is found, thus suggesting it might have been known at the time Borromini chose the ovals for the dome of San Carlo alle Quattro Fontane. A geometric proof of the same conjecture—as well as constructions—in the more general case of eggs and polycentric curves is the subject of the first part of this same research (Mazzotti, a Euclidean approach to eggs and polycentric curves, 2014).     

Chemical and Physical Signals Mediating Conspecific and Heterospecific Aggregation Behavior of First Instar Stink Bugs

We investigated cues that mediate the aggregation behavior of immature pentatomid bugs by using nymphs of six different pentatomid bug species (Nezara viridula, Acrosternum hilare, Chlorochroa ligata, Chlorochroa sayi, Thyanta pallidovirens, and Euschistus conspersus). When first instars of any two species were put together in a Petri dish, they readily formed heterospecific aggregations similar to their natural conspecific aggregations. The chemical profiles of first and second instar nymphs of each species were determined by solvent extraction with pentane, followed by GC-MS analysis. Immature bugs of the different species had some compounds in common, and some that were more species specific. Within a species, there were distinct differences in the profiles of compounds extracted from first and second instars. Bugs did not aggregate around untreated polysulfone beads (1 mm diam) that were glued together in groups approximating bug egg masses, suggesting that tactile cues alone were insufficient to induce aggregation. Furthermore, when tested over a range of doses, groups of polysulfone beads treated with crude whole-body extracts of bugs did not induce or maintain aggregations. However, first instar N. viridula nymphs did respond to beads treated with two of the three major components of bug extracts. 4-Oxo-(E)-2-decenal induced significant aggregations at two doses, whereas tridecane, the major component in extracts from all six species, did not, and (E)-2-decenal was repellent. The repellence of (E)-2-decenal may explain why we and previous researchers were unable to induce aggregations of first instar N. viridula using whole-body extracts.     

Workflows for Heliophysics

In this paper we describe how we have introduced workflows into the working practices of a community for whom the concept of workflows is very new, namely the heliophysics community. Heliophysics is a branch of astrophysics which studies the Sun and the interactions between the Sun and the planets, by tracking solar events as they travel throughout the Solar system. Heliophysics produces two major challenges for workflow technology. Firstly it is a systems science where research is currently developed by many different communities who need reliable data models and metadata to be able to work together. Thus it has major challenges in the semantics of workflows. Secondly, the problem of time is critical in heliophysics; the workflows must take account of the propagation of events outwards from the sun. They have to address the four dimensional nature of space and time in terms of the indexing of data. We discuss how we have built an environment for Heliophysics workflows building on and extending the Taverna workflow system and utilising the myExperiment site for sharing workflows. We also describe how we have integrated the workflows into the existing practices of the communities involved in Heliophysics by developing a web portal which can hide the technical details from the users, who can concentrate on the data from their scientific point of view rather than on the methods used to integrate and process the data. This work has been developed in the EU Framework 7 project HELIO, and is being disseminated to the worldwide Heliophysics community, since Heliophysics requires integration of effort on a global scale.