Flat space compressible fluid as holographic dual of black hole with curved horizon

We consider the fluid dual of $(d+2)$-dimensional vacuum Einstein equation either with or without a cosmological constant. The background solutions admit black hole event horizons and the spatial sections of the horizons are conformally flat. Therefore, a $d$-dimensional flat Euclidean space $\mathbb{E}^d$ is contained in the conformal class of the spatial section of the black hole horizon. A compressible, forced, stationary and viscous fluid system can be constructed on the product (Newtonian) spacetime $\mathbb{R}\times\mathbb{E}^d$ as the lowest order fluctuation modes around such black hole background. This construction provides the first example of holographic duality which is beyond the class of bulk/boundary correspondence.Comment: 14 pages. V3: error corrections. To appear in JHE

Fluids and vortex from constrained fluctuations around C-metric black hole

By foliating the four-dimensional C-metric black hole spacetime, we consider a kind of initial-value-like formulation of the vacuum Einstein's equation, the holographic initial data is a double consisting of the induced metric and the Brown-York energy momentum tensor on an arbitrary initial hypersurface. Then by perturbing the initial data that generates the background spacetime, it is shown that, in an appropriate limit, the fluctuation modes are governed by the continuity equation and the compressible Navier-Stokes equation which describe the momentum transport in non-relativistic viscous fluid on a flat Newtonian space. It turns out that the flat space fluid behaves as a pure vortex and the viscosity to entropy ratio is subjected to the black hole acceleration.Comment: 19 pages, LaTeX. v2: added a new reference. v3: major revisio

Experiment of Diffuse Reflection Laser Ranging to Space Debris and Data Analysis

Space debris has been posing a serious threat to human space activities and is needed to be measured and cataloged. As a new technology of space target surveillance, the measurement accuracy of DRLR (Diffuse Reflection Laser Ranging) is much higher than that of microwave radar and electro-optical measurement. Based on laser ranging data of space debris from DRLR system collected at SHAO (Shanghai Astronomical Observatory) in March-April 2013, the characteristics and precision of the laser ranging data are analyzed and its applications in OD (Orbit Determination) of space debris are discussed in this paper, which is implemented for the first time in China. The experiment indicates that the precision of laser ranging data can reach 39cm-228cm. When the data is sufficient enough (4 arcs of 3 days), the orbit accuracy of space debris can be up to 50m.Comment: 11 pages, 8 figure

Deposition and transport of graphene oxide in saturated and unsaturated porous media

In this work, sand and bubble column experiments were conducted to explore the deposition mechanisms of graphene oxide (GO) particles in porous media with various combinations of moisture content and ionic strength. Sand column experimental results indicated that retention and transport of GO in porous media were strongly dependent on solution ionic strength. Particularly, GO showed high mobility under low ionic strength conditions in both saturated and unsaturated porous media. Increasing ionic strength dramatically increased the retention of GO particles in porous media, mainly through secondary-minimum deposition as indicated in the XDLVO interaction energy profiles. Recovery rates of GO in unsaturated sand columns were lower than that in saturated columns under the same ionic strength conditions, suggesting moisture content also played an important role in the retention of GO in porous media. Findings from the bubble column experiments showed that the GO did not attach to the air–water interface, which is consistent with the XDLVO predictions. Additional retention mechanisms, such as film straining, thus could be responsible to the reduced mobility of GO in unsaturated porous media. The experimental data of GO transport through saturated and unsaturated porous media could be accurately simulated by an advection–dispersion-reaction model