Assembly via disassembly: A case in machine perceptual development

First results in the effort of learning about representations of objects is presented. The questions attempted to be answered are: What is innate and what must be derived from the environment. The problem is casted in the framework of disassembly of an object into two parts

How do robots take two parts apart

This research is a natural progression of efforts which begun with the introduction of a new research paradigm in machine perception, called Active Perception. There it was stated that Active Perception is a problem of intelligent control strategies applied to data acquisition processes which will depend on the current state of the data interpretation, including recognition. The disassembly/assembly problem is treated as an Active Perception problem, and a method for autonomous disassembly based on this framework is presented

Exact active subspace Metropolis-Hastings, with applications to the Lorenz-96 system

We consider the application of active subspaces to inform a Metropolis-Hastings algorithm, thereby aggressively reducing the computational dimension of the sampling problem. We show that the original formulation, as proposed by Constantine, Kent, and Bui-Thanh (SIAM J. Sci. Comput., 38(5):A2779-A2805, 2016), possesses asymptotic bias. Using pseudo-marginal arguments, we develop an asymptotically unbiased variant. Our algorithm is applied to a synthetic multimodal target distribution as well as a Bayesian formulation of a parameter inference problem for a Lorenz-96 system

Unified microscopic approach to the interplay of pinned-Wigner-solid and liquid behavior of lowest-Landau-level states in the neighborhood of nu=1/3

Motivated by recent experiments, and using the rotating-and-vibrating electron-molecule (RVEM) theory [Yannouleas and Landman, Phys. Rev. B 66, 115315 (2002); Phys. Rev. A 81, 023609 (2010)], in conjunction with exact diagonalization, we develop a unified microscopic approach for the interplay between liquid fractional-quantum-Hall-effect (FQHE) states and Wigner-solid states in the lowest Landau level (LLL) in the neighborhood of nu=1/3. Liquid characteristics of the FQHE states are associated with the symmetry-conserving rotations and vibrations of the electron molecule. Although the electron densities of the symmetry-conserving LLL states do not exhibit crystalline patterns, the intrinsic crystalline correlations are reflected in the conditional probability distributions and the emergence of cusp yrast states in the LLL spectra. It is shown that away from the exact fractional fillings, weak pinning perturbations (due to weak disorder) may overcome the energy gaps between adjacent global states and generate pinned broken symmetry ground states as a superposition of symmetry-conserving LLL states with different total angular momenta. The electron densities of such mixed states (without good angular momentum quantum numbers) exhibit oscillating patterns that correspond to molecular crystallites. These pinned Wigner crystallites represent finite-size precursors of the bulk Wigner-solid state. It is further shown that the emergence of these molecular crystallites is a consequence of the presence of RVEM components in the symmetry-conserving LLL states. In addition, it is shown that the RVEM approach accounts for the Wigner-solid state in the neighborhood of nu=1, which was also found in the experiments. We utilize results for sizes in a wide range from N=6 to N=29 electrons, and we address the extrapolation to the thermodynamic limit.Comment: 19 pages, 17 figures, 4 tables. For related papers, see http://www.prism.gatech.edu/~ph274cy

Rising Powers in International Development: Building an Agenda for Collaboration

The Institute of Development Studies (IDS) launched the IDS BRICS Initiative in 2011, which aimed to examine the multi-faceted role of the BRICS countries – Brazil, Russia, India, China, and South Africa – as actors in international development. The Initiative was designed to promote learning from the experiences of the BRICS and other rising powers, and to stimulate debate on the implications of these countries’ growing importance for international development policy and practice, an arena where the BRICS have to date received limited attention from academia and policy-makers. An initial consultation process carried out amongst IDS’ wide network of think-tanks, universities and civil society partners in 2011/12 across the BRICS countries showed there was significant interest in engaging in further discussions around this agenda. At the same time, IDS was awarded funding by UKAID, the British Department for International Development (DFID), which meant it was able to increase the scope of the BRICS Initiative and launch a full research programme, titled Rising Powers in International Development (RPID). IDS marked the launch of the programme with a workshop which brought together participants from potential partner institutions in the BRICS countries to discuss an agenda for future collaboration in research, teaching, and policy work, focusing on development theory, development policy, development practice, and development resource flows; through conceptual and methodological framework development and scoping at the country level, in specific sectors, and in “AidLand” more generally. The workshop brought together a diverse group of actors, including researchers and practitioners working in international development in the BRICS and beyond; and provided an opportunity to share and gain new perspectives on the state of the debate of development across the BRICS.DFI