Telerobotic controller development

To meet NASA's space station's needs and growth, a modular and generic approach to robotic control which provides near-term implementation with low development cost and capability for growth into more autonomous systems was developed. The method uses a vision based robotic controller and compliant hand integrated with the Remote Manipulator System arm on the Orbiter. A description of the hardware and its system integration is presented

Modeling Agglomeration of Dust Particles in Plasma

The charge on an aggregate immersed in a plasma environment distributes itself over the aggregate's surface; this can be approximated theoretically by assuming a multipole distribution. The dipole-dipole (or higher order) charge interactions between fractal aggregates lead to rotations of the grains as they interact. Other properties of the dust grains also influence the agglomeration process, such as the monomer shape (spherical or ellipsoidal) or the presence of magnetic material. Finally, the plasma and grain properties also determine the morphology of the resultant aggregates. Porous and fluffy aggregates are more strongly coupled to the gas, leading to reduced collisional velocities, and greater collisional cross sections. These factors in turn can determine the growth rate of the aggregates and evolution of the dust cloud. This paper gives an overview of the numerical and experimental methods used to study dust agglomeration at CASPER and highlights some recent results

Parametric Excitation and Squeezing in a Many-Body Spin System

We demonstrate a new method to coherently excite and control the quantum spin states of an atomic Bose gas using parametric excitation of the collective spin by time varying the relative strength of the Zeeman and spin-dependent collisional interaction energies at multiples of the natural frequency of the system. Compared to the usual single-particle quantum control techniques used to excite atomic spins (e.g. Rabi oscillations using rf or microwave fields), the method demonstrated here is intrinsically many-body, requiring inter-particle interactions. While parametric excitation of a classical system is ineffective from the ground state, we show that in our quantum system, parametric excitation from the quantum ground state leads to the generation of quantum squeezed states

Dynamic stabilization of a quantum many-body spin system

We demonstrate dynamic stabilization of an unstable strongly interacting quantum many-body system by periodic manipulation of the phase of the collective states. The experiment employs a spin-1 atomic Bose condensate initialized to an unstable (hyperbolic) fixed point of the spin-nematic phase space, where subsequent free evolution gives rise to squeezing and quantum spin mixing. To stabilize the system, periodic microwave pulses are applied that manipulate the spin-nematic many-body fluctuations and limit their growth. The range of pulse periods and phase shifts for which the condensate can be stabilized is measured and the resulting stability diagram compares well with a linear stability analysis of the problem.Comment: Main text 6 pages, 4 figures; Supplement 5 pages, 1 figur

Child Well-being in the Pacific Rim

This study extends previous efforts to compare the well-being of children using multi-dimensional indicators derived from sample survey and administrative series to thirteen countries in the Pacific Rim. The framework for the analysis of child well-being is to organise 46 indicators into 21 components and organise the components into 6 domains: material situation, health, education, subjective well-being, living environment, as well as risk and safety. Overall, Japan, Singapore and Taiwan have the highest child well-being and Thailand, Indonesia and the Philippines the lowest. However, there are substantial variations between the domains. Japan and Korea perform best on the material well-being of children and also do well on health and education but they have the lowest subjective well-being among their children by some margin. There is a relationship between child well-being and GDP per capita but children in China have higher well-being than you would expect given their GDP and children in Australia have lower well-being. The analysis is constrained by missing data particularly that the Health Behaviour of School-Aged Children Survey is not undertaken in any of these countries

Non-deterministic density classification with diffusive probabilistic cellular automata

We present a probabilistic cellular automaton (CA) with two absorbing states which performs classification of binary strings in a non-deterministic sense. In a system evolving under this CA rule, empty sites become occupied with a probability proportional to the number of occupied sites in the neighborhood, while occupied sites become empty with a probability proportional to the number of empty sites in the neighborhood. The probability that all sites become eventually occupied is equal to the density of occupied sites in the initial string.Comment: 4 pages, 4 figure