Representation of SO(3) Group by a Maximally Entangled State

A representation of the SO(3) group is mapped into a maximally entangled two qubit state according to literatures. To show the evolution of the entangled state, a model is set up on an maximally entangled electron pair, two electrons of which pass independently through a rotating magnetic field. It is found that the evolution path of the entangled state in the SO(3) sphere breaks an odd or even number of times, corresponding to the double connectedness of the SO(3) group. An odd number of breaks leads to an additional $\pi$ phase to the entangled state, but an even number of breaks does not. A scheme to trace the evolution of the entangled state is proposed by means of entangled photon pairs and Kerr medium, allowing observation of the additional $\pi$ phase.Comment: 4 pages, 3 figure

Assessing Ageing Condition of Mineral Oil-Paper Insulation by Polarization/Depolarization Current

Accurately assessing the ageing status of oil-paper insulation in transformer is essential and important. Polarization and Depolarization Current (PDC) technique is effective in assessing the condition of oil-paper insulation system. Though the PDC behaviour of mineral oil-paper insulation has been widely investigated, there is no report about how to make the quantitative analysis of mineral oil-paper insulation ageing condition by PDC. The PDC characteristics of mineral oil-paper insulation samples were investigated over the ageing period at 110°C. A new method for assessing the ageing condition of mineral oil-paper insulation by calculating the depolarization charge quantity was proposed. Results show that the depolarization charge quantity of mineral oil-paper insulation sample is very sensitive to its ageing condition. The stable depolarization charge quantity could be used to predict the ageing condition of mineral oil-paper insulation

Localized Control of Curie Temperature in Perovskite Oxide Film by Capping-layer- induced Octahedral Distortion

With reduced dimensionality, it is often easier to modify the properties of ultra-thin films than their bulk counterparts. Strain engineering, usually achieved by choosing appropriate substrates, has been proven effective in controlling the properties of perovskite oxide films. An emerging alternative route for developing new multifunctional perovskite is by modification of the oxygen octahedral structure. Here we report the control of structural oxygen octahedral rotation in ultra-thin perovskite SrRuO3 films by the deposition of a SrTiO3 capping layer, which can be lithographically patterned to achieve local control. Using a scanning Sagnac magnetic microscope, we show increase in the Curie temperature of SrRuO3 due to the suppression octahedral rotations revealed by the synchrotron x-ray diffraction. This capping-layer-based technique may open new possibilities for developing functional oxide materials.Comment: Main-text 5 pages, SI 6 pages. To appear in Physical Review Letter

Two novel aggregation-based algebraic multigrid methods

In the last two decades, substantial effort has been devoted to solve large systems of linear equations with algebraic multigrid (AMG) method. Usually, these systems arise from discretizing partial differential equations (PDE) which we encounter in engineering problems. The main principle of this methodology focuses on the elimination of the so-called algebraic smooth error after the smoother has been applied. Smoothed aggregation style multigrid is a particular class of AMG method whose coarsening process differs from the classic AMG. It is also a very popular and effective iterative solver and preconditioner for many problems. In this paper, we present two kinds of novel methods which both focus on the modification of the aggregation algorithm, and both lead a better performance while apply to several problems, such as Helmholtz equation

A comparison of the local spiral structure from Gaia DR2 and VLBI maser parallaxes

Context. The Gaia mission has released the second data set (Gaia DR2), which contains parallaxes and proper motions for a large number of massive, young stars. Aims. We investigate the spiral structure in the solar neighborhood revealed by Gaia DR2 and compare it with that depicted by VLBI maser parallaxes. Methods. We examined three samples with different constraints on parallax uncertainty and distance errors and stellar spectral types: (1) all OB stars with parallax errors of less than 10%; (2) only O-type stars with 0.1 mas errors imposed and with parallax distance errors of less than 0.2 kpc; and (3) only O-type stars with 0.05 mas errors imposed and with parallax distance errors of less than 0.3 kpc. Results. In spite of the significant distance uncertainties for stars in DR2 beyond 1.4 kpc, the spiral structure in the solar neighborhood demonstrated by Gaia agrees well with that illustrated by VLBI maser results. The O-type stars available from DR2 extend the spiral arm models determined from VLBI maser parallaxes into the fourth Galactic quadrant, and suggest the existence of a new spur between the Local and Sagittarius arms.Comment: 4 pages, 3 figures, 1 table, accepted for publication in A&

Waste management in Cange, Haiti

Our goal is to create a self-sustained waste management system in order to improve the sanitation and environmental health in Cange, Haiti. Cange currently has no waste management system; garbage is either piled in ravines or burned. We have divided Cange\u27s waste into three waste streams for treatment: organics, plastics, and other. The organics will be primarily treated with municipal scale composting windrows and the finished compost will be sold to surrounding farms. The plan for the plastic materials is to work with merchants to minimize the need and use of disposable plastic, repurpose used plastic waste into other marketable items (e.g., woven bags, construction blocks, etc.), and to recycle them at a newly formed micro-recycling facility. Other materials are expected to be mainly construction debris, which is already widely repurposed by the community, so it will be collected in a central refuse pile. In conclusion, we believe this system will effectively process the waste in a beneficial manner to the community