Intelligent tracking control of a DC motor driver using self-organizing TSK type fuzzy neural networks

[[abstract]]In this paper, a self-organizing Takagi–Sugeno–Kang (TSK) type fuzzy neural network (STFNN) is proposed. The self-organizing approach demonstrates the property of automatically generating and pruning the fuzzy rules of STFNN without the preliminary knowledge. The learning algorithms not only extract the fuzzy rule of STFNN but also adjust the parameters of STFNN. Then, an adaptive self-organizing TSK-type fuzzy network controller (ASTFNC) system which is composed of a neural controller and a robust compensator is proposed. The neural controller uses an STFNN to approximate an ideal controller, and the robust compensator is designed to eliminate the approximation error in the Lyapunov stability sense without occurring chattering phenomena. Moreover, a proportional-integral (PI) type parameter tuning mechanism is derived to speed up the convergence rates of the tracking error. Finally, the proposed ASTFNC system is applied to a DC motor driver on a field-programmable gate array chip for low-cost and high-performance industrial applications. The experimental results verify the system stabilization and favorable tracking performance, and no chattering phenomena can be achieved by the proposed ASTFNC scheme.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

Analysis of shared heritability in common disorders of the brain

Paroxysmal Cerebral Disorder

Testing the robustness of transmission network models to predict ectoparasite loads. One lizard, two ticks and four years

We investigated transmission pathways for two tick species, Bothriocroton hydrosauri and Amblyomma limbatum, among their sleepy lizard (Tiliqua rugosa) hosts in a natural population in South Australia. Our aim was to determine whether a transmission network model continued to predict parasite load patterns effectively under varying ecological conditions. Using GPS loggers we identified the refuge sites used by each lizard on each day. We estimated infectious time windows for ticks that detached from a lizard in a refuge. Time windows were from the time when a detached tick molted and become infective, until the time it died from desiccation while waiting for a new host. Previous research has shown that A. limbatum molts earlier and survives longer than B. hydrosauri. We developed two transmission network models based on these differences in infective time windows for the two tick species. Directed edges were generated in the network if one lizard used a refuge that had previously been used by another lizard within the infectious time window. We used those models to generate values of network node in-strength for each lizard, a measure of how strongly connected an individual is to other lizards in the transmission network, and a prediction of infection risk for each host. The consistent correlations over time between B. hydrosauri infection intensity and network derived infection risk suggest that network models can be robust to environmental variation among years. However, the contrasting lack of consistent correlation in A. limbatum suggests that the utility of the same network models may depend on the specific biology of a parasite species

Where should we meet? Mapping social network interactions of sleepy lizards shows sex-dependent social network structure

Social network analyses allow researchers to describe patterns of social interactions and their consequences in animal societies. Since direct observations in natural settings are often difficult, researchers often use tracking technologies to build proximity-based social networks. However, because both social behaviour (e.g. conspecific attraction) and environmental heterogeneity (e.g. resources attracting individuals independently) affect rates of interaction, identifying the processes that shape social networks is challenging. We tracked sleepy lizards, Tiliqua rugosa, using global positioning system (GPS) telemetry to investigate whether they show conspecific attraction or avoidance beyond any shared space use driven by environmental heterogeneity. Since these lizards have strong pair bonds and nonoverlapping core home ranges, we predicted different interaction rates between inter- and intrasex dyads and compared social network indices among dyad types (maleemale, femaleefemale and intersex) using node-identity permutation tests.We also mapped interactions onto the home ranges (using distance from the centre as an index) and contrasted observed social networks with those expected from a spatially explicit null model. We found that dyad types differed in their interaction patterns. Intersex dyads had stronger connections (higher edge weight) than a null expectation, and stronger than for same-sex dyads. Samesex dyads did not differ in edge weight from the null expectation, but were significantly more common (higher degree). Males had larger home ranges than females and consequently maleemale dyads interacted further away from their home range centres. Moreover, the locations of these interactions also differed from the null expectations more strongly than other dyad types. Hence, we conclude that males predominantly interacted with each other at the peripheries of their home range, presumably reflecting territorial behaviour. By applying a novel analysis technique, we accounted for the nonsocial component of space use and revealed sex-specific interaction patterns and the contribution of conspecific attraction to the social structure in this species. More generally we report how mapping the locations of nonrandom interaction rates provides broad information on the behaviours they represent.Orr Spiegel, Andrew Sih, Stephan T. Leu, C. Michael Bul

Socially interacting or indifferent neighbours? Randomization of movement paths to tease apart social preference and spatial constraints

Understanding how animals interact with their physical and social environment is a major question in ecology, but separating between these factors is often challenging. Observed interaction rates may reflect social behaviour – preferences or avoidance of conspecifics or certain phenotypes. Yet, environmental spatiotemporal heterogeneity also affects individual space use and interaction rates. For instance, clumped and ephemeral resources may force individuals to aggregate independently of sociality. Proximity‐based social networks (PBSNs) are becoming increasingly popular for studying social structures thanks to the parallel improvement of biotracking technologies and network randomization methods. While current methods focus on swapping individual identities among network nodes or in the data streams that underlies the network (e.g. individuals movement paths), we still need better tools to distinguish between the contribution of sociality and other factors towards those interactions. We propose a novel method that randomizes path segments among different time stamps within each individual separately (Part I). Temporal randomization of whole path segments (e.g. full days) retains their original spatial structure while decoupling synchronization among individuals. This allows researchers to compare observed dyadic association rates with those expected by chance given explicit space use of the individuals in each dyad. Further, since environmental changes are commonly much slower than the duration of social interactions, we can differentiate between these two factors (Part II). First, an individual's path is divided into successive time windows (e.g. weeks), and days are randomized within each time window. Then, by exploring how the deviations between randomized and observed networks change as a function of time window length, we can refine our null model to account also for temporal changes in the activity areas. We used biased‐correlated random walk models to simulate populations of socially indifferent or sociable agents for testing our method for both false‐positive and negative errors. Applying the method to a data set of GPS‐tracked sleepy lizards (Tiliqua rugosa) demonstrated its ability to reveal the social organization in free‐ranging animals while accounting for confounding factors of environmental spatiotemporal heterogeneity. We demonstrate that this method is robust to sampling bias and argue that it is applicable for a wide range of systems and tracking techniques, and can be extended to test for preferential phenotypic assortment within PBSNs.Orr Spiegel, Stephan T. Leu, Andrew Sih, C. Michael Bul

Integrating social networks, animal personalities, movement ecology and parasites: a framework with examples from a lizard

Available online 16 October 2017We describe a conceptual framework integrating animal personalities, movement ecology, social networks and parasite transmission. For directly transmitted parasites, parasite transmission depends on social interaction patterns that can be quantified using social network metrics. For indirectly transmitted parasites, the key can be transmission networks that quantify time-lagged contacts (e.g. where potential hosts visit locations used earlier by infected hosts). Social network connections (time-lagged or not) often result from shared space use determined by individual movements in response to key environmental factors. Movement ecology provides a framework for understanding these responses. Finally, individuals with different personalities likely respond differently to environmental factors in ways that influence the movements and space use that underlie network connectivity, which, in turn, affects parasite loads and transmission. We illustrate these key points with recent work on sleepy lizards, Tiliqua rugosa, and their ticks. By GPS tracking of nearly all adult lizards at our site, we found that lizards that more frequently shared the same refuges (where ticks detach and reattach to a new host) used earlier by other lizards tended to indeed have higher tick loads. Higher shared refuge use was associated with greater shared space use, in general. Shared space use with conspecifics was reduced by the lizards' general propensity (quantified by analyses of 279 985 GPS locations for 72 lizards) to avoid conspecifics, but enhanced by their general tendency to prefer areas with more resources and better refuge (in particular, late in the season when food was scarce and conditions were hotter and drier). Both of these tendencies were personality dependent. Less aggressive lizards exhibited both a stronger attraction to areas with more food and better refuge, and a stronger tendency to avoid other lizards. We conclude by discussing implications of our results for the general conceptual framework and suggest future directions.Andrew Sih, Orr Spiegel, Stephanie Godfrey, Stephan Leu, C. Michael Bul

When the going gets tough: behavioural type-dependent space use in the sleepy lizard changes as the season dries

Understanding space use remains a major challenge for animal ecology, with implications for species interactions, disease spread, and conservation. Behavioural type (BT) may shape the space use of individuals within animal populations. Bolder or more aggressive individuals tend to be more exploratory and disperse further. Yet, to date we have limited knowledge on how space use other than dispersal depends on BT. To address this question we studied BT-dependent space-use patterns of sleepy lizards (Tiliqua rugosa) in southern Australia. We combined high-resolution global positioning system (GPS) tracking of 72 free-ranging lizards with repeated behavioural assays, and with a survey of the spatial distributions of their food and refuge resources. Bayesian generalized linear mixed models (GLMM) showed that lizards responded to the spatial distribution of resources at the neighbourhood scale and to the intensity of space use by other conspecifics (showing apparent conspecific avoidance). BT (especially aggressiveness) affected space use by lizards and their response to ecological and social factors, in a seasonally dependent manner. Many of these effects and interactions were stronger later in the season when food became scarce and environmental conditions got tougher. For example, refuge and food availability became more important later in the season and unaggressive lizards were more responsive to these predictors. These findings highlight a commonly overlooked source of heterogeneity in animal space use and improve our mechanistic understanding of processes leading to behaviourally driven disease dynamics and social structure

Endure your parasites: Sleepy Lizard (Tiliqua rugosa) movement is not affected by their ectoparasites

Movement is often used to indicate host vigour, as it has various ecological and evolutionary implications, and has been shown to be affected by parasites. We investigate the relationship between tick load and movement in the Australian Sleepy Lizard (Tiliqua rugosa (Gray, 1825)) using high resolution GPS tracking. This allowed us to track individuals across the entire activity season. We hypothesized that tick load negatively affects host movement (mean distance moved per day). We used a multivariate statistical model informed by the ecology and biology of the host and parasite, their host–parasite relationship, and known host movement patterns. This allowed us to quantify the effects of ticks on lizard movement above and beyond effects of other factors such as time in the activity season, lizard body condition, and stress. We did not find any support for our hypothesis. Instead, our results provide evidence that lizard movement is strongly driven by internal state (sex and body condition independent of tick load) and by external factors (environmental conditions). We suggest that the Sleepy Lizard has largely adapted to natural levels of tick infection in this system. Our results conform to host–parasite arms race theory, which predicts varying impacts of parasites on hosts in natural systems.Patrick L. Taggart, Stephan T. Leu, Orr Spiegel, Stephanie S. Godfrey, Andrew Sih, and C. Michael Bul

Why is social behavior rare in Reptiles? Lessons From Sleepy Lizards

We report on 35. years of research into behavior and ecology of the Australian sleepy lizard, Tiliqua rugosa. We describe the unusually long monogamous pairing period in this lizard before mating takes place each spring, and the long-term persistence of mating pairs, reforming each spring for up to 27. years. We review hypotheses, observations, and experiments and conclude that females drive the pairing, becoming more receptive to males that have provided prolonged attention, because of the advantages they gain through greater awareness of approaching danger. We suggest that long-term pair fidelity has resulted from a higher reproductive efficiency between familiar partners. We then consider the broader social network structure in the sleepy lizard population, suggesting from our analyses that lizards make more contacts with their neighbors, sometimes agonistically, than if they were moving at random. There are few kin-based associations in the networks, but lizards with different personality types have different network positions. The broad social structure of the population is robust to ecological and environmental changes, although various network parameters are adjusted with different climate or habitat conditions. The overall social structure of the sleepy lizard population has an important role in transmission of parasites and pathogens. Finally we consider why this species is one of the very few reptiles for which stable social living has been reported. This may be because reptile social living is relatively under studied. Alternatively, we suggest, many reptile species may be constrained from evolving social structures, because they lack either the necessary cognitive ability or a strong defense against the high risk of pathogen transmission that comes from social living