63 research outputs found

    Destination Tag Routing Techniques Based on a State Model for the IADM Network

    Get PDF
    A state model is proposed for solving the problem of routing and rerouting messages in the Inverse Augmented Data Manipulator (IADM) network. Using this model, necessary and sufficient conditions for the reroutability of messages are established, and then destination tag schemes are derived. These schemes are simpler, more efficient and require less complex hardware than previously proposed routing schemes. Two destination tag schemes are proposed. For one of the schemes, rerouting is totally transparent to the sender of the message and any blocked link of a given type can be avoided. Compared with previous works that deal with the same type of blockage, the timeXspace complexity is reduced from O(logN) to O(1). For the other scheme, rerouting is possible for any type of link blockage. A universal rerouting algorithm is constructed based on the second scheme, which finds a blockage-free path for any combination of multiple blockages if there exists such a path, and indicates absence of such a path if there exists none. In addition, the state model is used to derive constructively a lower bound on the number of subgraphs which are isomorphic to the Indirect Binary N-Cube network in the IADM network. This knowledge can be used to characterize properties of the IADM networks and for permutation routing in the IADM networks

    The brain dynamics of architectural affordances during transition.

    Full text link
    Action is a medium of collecting sensory information about the environment, which in turn is shaped by architectural affordances. Affordances characterize the fit between the physical structure of the body and capacities for movement and interaction with the environment, thus relying on sensorimotor processes associated with exploring the surroundings. Central to sensorimotor brain dynamics, the attentional mechanisms directing the gating function of sensory signals share neuronal resources with motor-related processes necessary to inferring the external causes of sensory signals. Such a predictive coding approach suggests that sensorimotor dynamics are sensitive to architectural affordances that support or suppress specific kinds of actions for an individual. However, how architectural affordances relate to the attentional mechanisms underlying the gating function for sensory signals remains unknown. Here we demonstrate that event-related desynchronization of alpha-band oscillations in parieto-occipital and medio-temporal regions covary with the architectural affordances. Source-level time-frequency analysis of data recorded in a motor-priming Mobile Brain/Body Imaging experiment revealed strong event-related desynchronization of the alpha band to originate from the posterior cingulate complex, the parahippocampal region as well as the occipital cortex. Our results firstly contribute to the understanding of how the brain resolves architectural affordances relevant to behaviour. Second, our results indicate that the alpha-band originating from the occipital cortex and parahippocampal region covaries with the architectural affordances before participants interact with the environment, whereas during the interaction, the posterior cingulate cortex and motor areas dynamically reflect the affordable behaviour. We conclude that the sensorimotor dynamics reflect behaviour-relevant features in the designed environment

    The brain dynamics of architectural affordances during transition

    Get PDF

    Resilience in Transportation Networks

    Full text link
    The functionality of transportation networks is greatly challenged by risk factors such as increasing climate-related hazards, rising population exposure, and greater city vulnerability. Inevitably, the transportation network cannot withstand the impact of an overwhelming disaster, which results in rapid declines in the performance of road net-work. As a next step, the authorities need to restore the performance of the road net-work to an acceptable state as soon as possible and rebalance the conflict between the capacity of the road network and travel demand. Resilience is defined as the process of system performance degradation followed by recovery. To improve the transportation network resilience and maintain regular traffic, it is crucial to identify which factors are related to the resilience and investigate how these factors impact resilience. In this thesis, four factors, i.e., road networks, evacuees, disruption types and au-thorities, are identified to analyze resilience mechanisms. Firstly, the change in vehicle speed during a disaster is used as a measure of resilience, and we analyze the quantita-tive relationship between resilience and the structural characteristics and properties of the road network in multiple disruptions in multiple cities. The results show that the connectivity of the road network, the predictability of disruption, and the population density affect the resilience of the road network in different ways. Secondly, as the road connectivity plays a crucial role during the evacuation pe-riod and considering more frequent and extensive bushfires, we explore a practical and challenging problem: are bushfire fatalities related to road network characteristics? Con-nectivity index (CI), a composite metric that takes into account redundancy, connectivi-ty, and population exposure is designed. The statistical analysis of real-world data sug-gests that CI is significantly negatively correlated with historical bushfire fatalities. This parsimonious and simple graph-theoretic measure can provide planners a useful metric to reduce vulnerability and increase resilience among areas that are prone to bushfires. Finally, a modelling framework for optimizing road network pre-disaster invest-ment strategy under different disaster damage levels is proposed. A bi-level multi-objective optimization model is formulated, in which the upper-level aims to maximize the capacity-based functionality and robustness of the road network, and the lower-level is the user equilibrium problem. To efficiently solve the model, the Shapley value is used to select candidate edges and obtain a near-optimal project order. For more reality, the heterogeneity of road segments to hazards and the correlation of road segments in dif-ferent hazard phases are considered. Realistic speed data is used to explore the depend-ency between different disaster states with copula functions. The numerical results illus-trate that the investment strategy is significantly influenced by the road edge character-istics and the level of disaster damage. Critical sections that can significantly improve the overall functionality of the network are identified. Overall, the core contribution of this thesis is to provide insights into the evalua-tion and analysis of resilience in transportation networks, as well as develop modelling frameworks to promote resilience. The results of this work can provide a theoretical ba-sis for road network design, pre-disaster investment and post-disaster emergency rescue

    MOX Lead Assembly Fabrication at the Savannah River Site

    Full text link

    Timbral Learning for Musical Robots

    Get PDF
    abstract: The tradition of building musical robots and automata is thousands of years old. Despite this rich history, even today musical robots do not play with as much nuance and subtlety as human musicians. In particular, most instruments allow the player to manipulate timbre while playing; if a violinist is told to sustain an E, they will select which string to play it on, how much bow pressure and velocity to use, whether to use the entire bow or only the portion near the tip or the frog, how close to the bridge or fingerboard to contact the string, whether or not to use a mute, and so forth. Each one of these choices affects the resulting timbre, and navigating this timbre space is part of the art of playing the instrument. Nonetheless, this type of timbral nuance has been largely ignored in the design of musical robots. Therefore, this dissertation introduces a suite of techniques that deal with timbral nuance in musical robots. Chapter 1 provides the motivating ideas and introduces Kiki, a robot designed by the author to explore timbral nuance. Chapter 2 provides a long history of musical robots, establishing the under-researched nature of timbral nuance. Chapter 3 is a comprehensive treatment of dynamic timbre production in percussion robots and, using Kiki as a case-study, provides a variety of techniques for designing striking mechanisms that produce a range of timbres similar to those produced by human players. Chapter 4 introduces a machine-learning algorithm for recognizing timbres, so that a robot can transcribe timbres played by a human during live performance. Chapter 5 introduces a technique that allows a robot to learn how to produce isolated instances of particular timbres by listening to a human play an examples of those timbres. The 6th and final chapter introduces a method that allows a robot to learn the musical context of different timbres; this is done in realtime during interactive improvisation between a human and robot, wherein the robot builds a statistical model of which timbres the human plays in which contexts, and uses this to inform its own playing.Dissertation/ThesisDoctoral Dissertation Media Arts and Sciences 201

    Genetic analysis of bipolar disorder and alcohol use disorder

    Get PDF
    Includes bibliographical referencesBackground: Mental health disorders represent a major public health problem in most countries around the world. In South Africa, the lifetime prevalence of psychiatric disorders is 30.3%, with substance-use disorders and mood disorders being the second and third most prevalent classes of lifetime disorders, respectively. Bipolar disorder (BD) has a lifetime prevalence of 1.4% and alcohol use disorder (AUD) a lifetime prevalence of 30.3%, and they are frequently comorbid. Both of these disorders have a relatively high heritability, yet the exact genetic basis of each remains unknown. Genetic variants within the hypothalamic-pituitary-adrenal (HPA)-axis and glutamatergic pathways have previously been implicated in both phenotypes. The aim of this project was to investigate the aetiology of BD and AUD, using high-throughput genomic technologies, bioinformatics, brain-imaging and environmental measures. An additional aim was to assess the genetic aetiology of BD-AUD comorbidity. Methods: For the genetic analysis underlying BD, a South African 'Afrikaner' family was investigated. Whole-genome sequencing (WGS) and whole-genome linkage analysis was performed for individuals with BD Type I (BDI) and unaffected family members using the Illumina HiSeq2000 and Affymetrix Axiom TM Genome-wide CEU 1 Array, respectively. For the AUD analysis, two groups were investigated; a South African adolescent group comprising 80 individuals with AUD and 80 controls, and a group of 8123 individuals from the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort. The South African group of adolescents were genotyped using the Illumina Infinium iSelect custom 6000 BeadChip, childhood trauma data was obtained and brain magnetic resonance images were collected for a subset of this group. Genotype data on HPA-axis genes were obtained from a previous study for the ALSPAC cohort. The fourth group of individuals investigated in this thesis comprised 233 individuals with BD-AUD comorbidity from the Systemic Treatment Enhancement Program for BD (STEP-BD). Genotype data for genes from the glutamatergic and HPA-axis pathways were obtained from a previous study conducted on these individuals. Results: The chromosomal regions 6p25, 10p14-10p15.1, 11q23-11q25, and 13q21-22 scored the highest LOD scores for BD and the most over-represented pathway in the affected family members was the T-cell receptor signalling pathway. In the South African adolescent group, circadian rhythm genes were associated with AUD and childhood trauma predicted alcohol use in adolescence. The gene-imaging analysis identified a SNP in the glutamate receptor, ionotropic, N-methyl D-aspartate 2B (GRIN2B) gene as being associated with brain volume in the left orbitofrontal cortex and posterior cingulate. HPA-axis genes did not show an association with AUD and no significant gene x environment interactions were detected for AUD in the ALSPAC cohort. Single variants in the glutamatergic genes and HPA-axis were not associated with BD-AUD comorbidity. However, from the gene-based analysis, the glutamatergic gene PRKCI was associated with BD-AUD comorbidity. Conclusions: It appears that disruption in immune-related genes may contribute to the development of BD in an Afrikaner family. No significant gene x environment interactions were detected for adolescent AUD. The circadian pathway and childhood trauma may play a role in the development of adolescent AUD. Differential brain volume and BD-AUD comorbidity may be characterised by variation in the glutamatergic pathway. These pathways and the interactions between them should be further investigated in BD and AUD
    • …
    corecore