Modelling a Moore-Spiegel Electronic Circuit: the imperfect model scenario

The goal of this thesis is to investigate model imperfection in the context of forecasting. We focus on an electronic circuit built in a laboratory and then enclosed to reduce environmental effects. The non-dimensionalised model equations, obtained by applying Kirchhoff’s current and voltage laws, are the Moore-Spiegel Equations [47], but they exhibit a large disparity with the circuit. At parameter values used in the circuit, they yield a periodic trajectory whilst the circuit exhibits chaotic behaviour. Therefore, alternative models for the circuit are sought.\ud \ud The models we consider are local and global prediction models constructed from data. We acknowledge that all our models have errors and then seek to quantify how these errors are distributed across the circuit attractor. To this end, q-pling times of initial uncertainties are computed for the various models. A q-pling time is the time for an initial uncertainty to increase by a factor of q [67], where q is a real number. Whereas it is expected that different models should have different q-pling time distributions, it is found that the diversity in our models can be increased by constructing them in different coordinate spaces.\ud \ud To forecast the future dynamics of the circuit using any of the models, we make probabilistic forecasts [8]. The question of how to choose the spread of the initial ensemble is addressed by the use of skill scores [8, 9]. Finally, the diversity in our models is exploited by combining probabilistic forecasts from them so as to minimise some skill score. It is found that the skill of combined not-so-good models can be increased by combining\ud them as discussed in this thesis

The Use of a Building Information Model to Support Seismic Analysis: Application to the National Palace of Sintra, Portugal

This work presents an application of a Building Information Model (BIM) to the National Palace of Sintra, Portugal, a large and complex building composed of different unreinforced masonry buildings that is included in the Cultural Landscape of Sintra, classified under the UNESCO World Heritage list in 1995. The developed H-BIM (Heritage Building Information Modelling) model has the ability to provide the geometric information of the structure of the building, together with its descriptive attributes, such as the mechanical characterization of the building materials, as inputs to the seismic structural analysis. The results of such analyses are also stored as attributes within the H-BIM model, providing an integrated platform usable by the building management. Geometric data was acquired using a Faro FocusS70, together with a Topcon Falcon 8+ UAV. The methodology applied in the construction of the H-BIM model was implemented with Autodesk Revit® software. Since the Palace is very complex, its seismic behaviour was studied for the different building units, considering the effect of the adjacent ones, and performing nonlinear static analyses through 3Muri software

ASSESSMENT OF PALATABILITY ATTRIBUTE OF Gluteaus Medius STEAKS (BEEF TOP SIRLOIN BUTT)

ABSTRACT: Beef top sirloin butts (n = 48

Recurrence analysis of a Moore-Spiegel electronic circuit

An electronic circuit that simulates theMoore-Spiegel equations [Moore and Spiegel, 1966] is presented. To compare the data measured from the circuit with the numerical solution to the equations, and assess the extent to which the circuit behaviour deviates from the model equations, parameter regimes are explored in each case. After going through a comparison of the two and performing a bifurcation analysis, we unravel the structure revealed by the circuit data. In this study, recurrence plots [Eckmann, Kamphorst and Ruelle, 1987] are used to assess dynamical changes such as mode transitions and nonstationarity. Their diagnostic power is coupled with that of space time separation plots [Provenzale, Smith, Vio and Murante, 1992]. The quality of recurrence plots obtained from multi channel measurements is compared with that obtained by embedding a scalar signal into higher dimensions. The effect of nonstationarity on the time delay computed by the mutual information technique [Fraser and Swinney, 1986] is addressed

Why do dolphins form mixed-species associations in the Azores ?

Mixed-species associations are temporary associations between individuals of different species that are often observed in birds, primates and cetaceans. They have been interpreted as a strategy to reduce predation risk, enhance foraging success and/or provide a social advantage. In the archipelago of the Azores, four species of dolphins are commonly involved in mixed-species associations: the common dolphin, Delphinus delphis, the bottlenose dolphin, Tursiops truncatus, the striped dolphin, Stenella coeruleoalba, and the spotted dolphin, Stenella frontalis. In order to understand the reasons why dolphins associate, we analysed field data collected since 1999 by research scientists and trained observers placed onboard fishing vessels. In total, 113 mixed-species groups were observed out of 5720 sightings. The temporal distribution, habitat (water depth, distance to the coast), behaviour (i.e. feeding, travelling, socializing), size and composition of mixed-species groups were compared with those of single-species groups. Results did not support the predation avoidance hypothesis and gave little support to the social advantage hypothesis. The foraging advantage hypothesis was the most convincing. However, the benefits of mixed-species associations appeared to depend on the species. Associations were likely to be opportunistic in the larger bottlenose dolphin, while there seemed to be some evolutionary constraints favouring associations in the rarer striped dolphin. Comparison with previous studies suggests that the formation of mixed-species groups depends on several environmental factors, and therefore may constitute an adaptive response