201 research outputs found
Mutual Information Iterated Local Search: A Wrapper-Filter Hybrid for Feature Selection in Brain Computer Interfaces
Brain Computer Interfaces provide a very challenging classification task due to small numbers of instances, large numbers of features, non-stationary problems, and low signal-to-noise ratios. Feature selection (FS) is a promising solution to help mitigate these effects. Wrapper FS methods are typically found to outperform filter FS methods, but reliance on cross-validation accuracies can be misleading due to overfitting. This paper proposes a filter-wrapper hybrid based on Iterated Local Search and Mutual Information, and shows that it can provide more reliable solutions, where the solutions are more able to generalise to unseen data. This study further contributes comparisons over multiple datasets, something that has been uncommon in the literature
Portents of Pluralism: How Hybrid Regimes Affect Democratic Transitions’’
The original studies of "competitive authoritarianism" and "hegemonic authoritarianism"
Reconsidering Presidential Elections in the Middle East
The University Archives has determined that this item is of continuing value to OSU's history.The media can be accessed here: http://streaming.osu.edu/knowledgebank/mershon09/041409.mp4Jason Brownlee is Assistant Professor of Government and Middle Eastern Studies at the University of Texas. He teaches undergraduate courses on U.S. foreign policy and Mideast politics, and graduate seminars on democratization and modern Islamic movements.
Brownlee is author of Authoritarianism in an Age of Democratization (Cambridge University Press, 2007), which examines the historical sources of electoral contestation and regime change during the last 30 years. He has published articles in World Politics, Comparative Politics, and Studies in Comparative International Development. His article "Hereditary Succession in Modern Autocracies" was recognized by the Comparative Democratization section of the American Political Science Association as best article of 2007.
Brownlee is currently dividing his time between two large projects. The first addresses major cases of U.S. occupation abroad, while the second looks comparatively at local challenges to the Egyptian government.Ohio State University. Mershon Center for International Security Studie
Methods And Sources For Underpinning Airport Ground Movement Decision Support Systems
The airport Ground Movement problem is concerned with the allo- cation of routes to aircraft for their travel along taxiways between the runway and the stands. It is important to find high quality solutions to this problem because it has a strong influence on the capacity of an airport and upon the environmental impact. The problem is particularly challenging. It has multiple objectives (such as minimising taxi time and fuel consumption). It also has considerable uncertainty, which arises from the complex operations of an airport. It is an active and topical area of research. A barrier to scientific research in this area is the lack of publicly available realistic data and benchmark problems. The reason for this is often concerned with commercial sensitivities. We have worked with airports and service providers to address this issue, by exploring several sources of freely-available data and developing algorithms for cleaning and processing the data into a more suitable form. The result is a system to generate datasets that are realistic, and that facilitate research with the potential to improve on real-world problems, without the confidentiality and commercial licensing issues usually associated with real airport data. Case studies with several international airports demonstrate the usefulness of the datasets. The algorithms have been implemented within three tools and made freely-available for researchers. A benchmark Ground Movement problem has also been made available, with results for an existing Ground Movement algorithm. It is intended that these contributions will underpin the advance of research in this difficult application area
Seismic anisotropy as a constraint on composition in the lower crust
Our current interpretation of the composition of the middle
and lower crust comes mainly from seismic observations, yet
it remains a challenge to link seismic observations directly to
composition. This is because isotropic seismic properties are
similar across a range of compositions. Taking anisotropy into
account allows for further refinement of our interpretation of
composition provided that anisotropy is characterized for
candidate rock types. This study uses electron backscatter
diffraction (EBSD) measurements of crystallographic
preferred orientation of minerals to calculate seismic
anisotropy in samples of the Pelona-Orocopia-Rand (POR)
schist from the Mojave region of southern California. The
goals of this work are to characterize the seismic anisotropy of
the POR schist and its relationship to observed lower crustal
anisotropy in the region, and to refine predictions of lower
crustal composition based on seismic anisotropy
Exploring the Accuracy - Energy Trade-off in Machine Learning
Machine learning accounts for considerable global electricity demand and resulting environmental impact, as training a large deep-learning model produces 284 000kgs of the greenhouse gas carbon dioxide. In recent years, search-based approaches have begun to explore improving software to consume less energy. Machine learning is a particularly strong candidate for this because it is possible to trade off functionality (accu-racy) against energy consumption, whereas with many programs functionality is simply a pass-or-fail constraint. We use a grid search to explore hyperparameter configurations for a multilayer perceptron on five classification data sets, considering trade-offs of classification accuracy against training or inference energy. On one data set, we show that 77% of energy consumption for inference can saved by reducing accuracy from 94.3% to 93.2%. Energy for training can also be reduced by 30-50% with minimal loss of accuracy. We also find that structural parameters like hidden layer size is a major driver of the energy-accuracy trade-off, but there is some evidence that non-structural hyperparameters influence the trade-off too. We also show that a search-based approach has the potential to identify these trade-offs more efficiently than the grid search
Methods And Sources For Underpinning Airport Ground Movement Decision Support Systems
The airport Ground Movement problem is concerned with the allo- cation of routes to aircraft for their travel along taxiways between the runway and the stands. It is important to find high quality solutions to this problem because it has a strong influence on the capacity of an airport and upon the environmental impact. The problem is particularly challenging. It has multiple objectives (such as minimising taxi time and fuel consumption). It also has considerable uncertainty, which arises from the complex operations of an airport. It is an active and topical area of research. A barrier to scientific research in this area is the lack of publicly available realistic data and benchmark problems. The reason for this is often concerned with commercial sensitivities. We have worked with airports and service providers to address this issue, by exploring several sources of freely-available data and developing algorithms for cleaning and processing the data into a more suitable form. The result is a system to generate datasets that are realistic, and that facilitate research with the potential to improve on real-world problems, without the confidentiality and commercial licensing issues usually associated with real airport data. Case studies with several international airports demonstrate the usefulness of the datasets. The algorithms have been implemented within three tools and made freely-available for researchers. A benchmark Ground Movement problem has also been made available, with results for an existing Ground Movement algorithm. It is intended that these contributions will underpin the advance of research in this difficult application area
Democratization and foreign policy in Southeast Asia: the case of the ASEAN Inter-Parliamentary Myanmar Caucus
This is an Author's Accepted Manuscript of an article published in Cambridge Review of International Affairs Vol. 22, Iss. 3, 2009 as published in the CAMBRIDGE REVIEW OF INTERNATIONAL AFFAIRS, 2009, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/09557570903104008
Kepler Planet-Detection Mission: Introduction and First Results
The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet’s surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-sized Kepler-4b is similar to that of Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest-density planets (~0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets
Kepler Mission Design, Realized Photometric Performance, and Early Science
The Kepler Mission, launched on Mar 6, 2009 was designed with the explicit
capability to detect Earth-size planets in the habitable zone of solar-like
stars using the transit photometry method. Results from just forty-three days
of data along with ground-based follow-up observations have identified five new
transiting planets with measurements of their masses, radii, and orbital
periods. Many aspects of stellar astrophysics also benefit from the unique,
precise, extended and nearly continuous data set for a large number and variety
of stars. Early results for classical variables and eclipsing stars show great
promise. To fully understand the methodology, processes and eventually the
results from the mission, we present the underlying rationale that ultimately
led to the flight and ground system designs used to achieve the exquisite
photometric performance. As an example of the initial photometric results, we
present variability measurements that can be used to distinguish dwarf stars
from red giants.Comment: 16 pages, 5 figures, 1 table 26 Jan revision replaced Subject
headings with keywords from approved lis
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