9,394 research outputs found
Evolutionary Networks for Multi-Behavioural Robot Control : A thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Computer Science Massey University, Albany, New Zealand
Artificial Intelligence can be applied to a wide variety of real world problems, with
varying levels of complexity; nonetheless, real world problems often demand for
capabilities that are difficult, if not impossible to achieve using a single Artificial
Intelligence algorithm. This challenge gave rise to the development of hybrid systems
that put together a combination of complementary algorithms. Hybrid approaches
come at a cost however, as they introduce additional complications for the developer,
such as how the algorithms should interact and when the independent algorithms
should be executed. This research introduces a new algorithm called Cascading
Genetic Network Programming (CGNP), which contains significant changes to the
original Genetic Network Programming. This new algorithm has the facility to
include any Artificial Intelligence algorithm into its directed graph network, as either
a judgement or processing node. CGNP introduces a novel ability for a scalable
multiple layer network, of independent instances of the CGNP algorithm itself. This
facilitates problem subdivision, independent optimisation of these underlying layers
and the ability to develop varying levels of complexity, from individual motor control
to high level dynamic role allocation systems. Mechanisms are incorporated to
prevent the child networks from executing beyond their requirement, allowing the
parent to maintain control. The ability to optimise any data within each node
is added, allowing for general purpose node development and therefore allowing
node reuse in a wide variety of applications without modification. The abilities
of the Cascaded Genetic Network Programming algorithm are demonstrated and
proved through the development of a multi-behavioural robot soccer goal keeper, as
a testbed where an individual Artificial Intelligence system may not be sufficient.
The overall role is subdivided into three components and individually optimised
which allow the robot to pursue a target object or location, rotate towards a target
and provide basic functionality for defending a goal. These three components are
then used in a higher level network as independent nodes, to solve the overall multi-
behavioural goal keeper. Experiments show that the resulting controller defends the
goal with a success rate of 91%, after 12 hours training using a population of 400
and 60 generations
Preferential attachment with choice
We consider the degree distributions of preferential attachment random graph
models with choice similar to those considered in recent work by Malyshkin and
Paquette and Krapivsky and Redner. In these models a new vertex chooses
vertices according to a preferential rule and connects to the vertex in the
selection with the th highest degree. For meek choice, where , we show
that both double exponential decay of the degree distribution and
condensation-like behaviour are possible, and provide a criterion to
distinguish between them. For greedy choice, where , we confirm that the
degree distribution asympotically follows a power law with logarithmic
correction when and shows condensation-like behaviour when .Comment: 17 pages, 1 figure. Accepted for publication in Random Structures and
Algorithm
Building an infrastructure for financial stability: an overview
Financial crises ; Bank supervision ; Monetary policy
Preseason Lower Extremity Functional Test Scores Are Not Associated With Lower Quadrant Injury - A Validation Study With Normative Data on 395 Division III Athletes
Background: Preseason performance on the lower extremity functional test (LEFT), a timed series of agility drills, has been previously reported to be associated with future risk of lower quadrant (LQ = low back and lower extremities) injury in Division III (D III) athletes.Validation studies are warranted to confirm or refute initial findings.
Hypothesis/Purpose: The primary purpose of this study was to examine the ability of the LEFT to discriminate injury occurrence in D III athletes, in order to validate or refute prior findings. It was hypothesized that female and male D III athletes slower at completion of the LEFT would be at a greater risk for a non-contact time-loss injury during sport. Secondary purposes of this study are to report other potential risk factors based on athlete demographics and to present normative LEFT data based on sport participation.
Methods: Two hundred and six (females = 104; males = 102) D III collegiate athletes formed a validation sample. Athletes in the validation sample completed a demographic questionnaire and performed the LEFT at the start of their sports preseason. Athletic trainers tracked non-contact time-loss LQ injuries during the season. A secondary analysis of risk based on preseason LEFT performance was conducted for a sample (n = 395) that consisted of subjects in the validation sample (n = 206) as well as athletes from a prior LEFT related study (n = 189).
Study Design: Prospective cohort
Results: Male athletes in the validation sample completed the LEFT [98.6 (± 8.1) seconds] significantly faster than female athletes [113.1 (± 10.4) seconds]. Male athletes, by sport, also completed the LEFT significantly faster than their female counterparts who participated in the same sport. There was no association between preseason LEFT performance and subsequent injury, by sex, in either the validation sample or the combined sample. Females who reported starting primary sport participation by age 10 were two times (OR = 2.4, 95% CI: 1.2, 4.9; p = 0.01) more likely to experience a non-contact time-loss LQ injury than female athletes who started their primary sport at age 11 or older. Males who reported greater than three hours per week of plyometric training during the six-week period prior to the start of the preseason were four times more likely (OR = 4.0, 95% CI: 1.1, 14.0; p = 0.03) to experience a foot or ankle injury than male athletes who performed three or less hours per week.
Conclusions: The LEFT could not be validated as a preseason performance measure to predict future sports injury risk. The data presented in this study may aid rehabilitation professionals when evaluating an injured athlete’s ability to return to sport by comparing their LEFT score to population norms
Development domains for Ethiopia: capturing the geographical context of smallholder development options
"The choices that smallholder farmers are able to make are strongly conditioned by the geographic conditions in which they live. The importance of this fact for rural development strategy is not lost on policy makers. For example, the government of Ethiopia frequently frames policy discussions by broadly different geographical conditions of moisture availability, recognizing moisture reliable, drought prone and pastoralist areas. These conditions are seen as important criteria for determining the nature, extent and priority of development interventions for different parts of the country. There is considerable evidence, however, that other geographical factors also have important implications for rural development options. This paper uses agroecology, access to markets, and population density to define development domains: geographical locations sharing broadly similar rural development constraints and opportunities. Unlike similar efforts conducted elsewhere, this work is unique in that it seeks to move away from a subjective mapping of factors of theorized importance to a more rigorous definition of development domains on the basis of quantitative data on smallholder livelihood strategies. After selecting variables for mapping, we calibrate our definition for domains in such a way that their explanatory power is maximized across a range of livelihood strategies that figure in the current Ethiopian rural development discourse (market engagement, dependence upon agriculture, etc.)." Authors' AbstractSmallholders, Small farmers, Geographic conditions, rural development strategies, Development policy, Agro-ecology, Market access, Livelihoods, Population density,
Economic cycles and bank health
Over the past two decades the United States has experienced substantial increases in the number of bank failures, however, surprisingly few banks have failed during the 2001 recession. This paper explores the relationship between economic cycles and bank health. We find that economic forecasts provide little additional information over bank-specific financial data during prosperous times, possibly because bank problems during these times are likely to be idiosyncratic to individual management decisions. However, economic forecasts become relevant during troubled economic periods, with poor economic conditions hindering a broader set of institutions.Bank failures
Application of the Hilbert-Huang Transform to the Search for Gravitational Waves
We present the application of a novel method of time-series analysis, the
Hilbert-Huang Transform, to the search for gravitational waves. This algorithm
is adaptive and does not impose a basis set on the data, and thus the
time-frequency decomposition it provides is not limited by time-frequency
uncertainty spreading. Because of its high time-frequency resolution it has
important applications to both signal detection and instrumental
characterization. Applications to the data analysis of the ground and space
based gravitational wave detectors, LIGO and LISA, are described
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