Northern Barbados accretionary prism: Structure, deformation, and fluid flow interpreted from 3D seismic and well-log data

We reanalyzed 3D seismic reflection and logging-while-drilling data from the toe of the northern Barbados accretionary prism to interpret structure, deformation, and fluid flow related to subduction processes. The seafloor amplitude and coherence reveal an abrupt change in the thrust orientation from NNE at the thrust front and north and NNW about 5 km west of the thrust front. These thrust sets are separated by a triangular-shaped quiet area, which may represent a zone of low strength. The northeast-trending band of strong negative amplitude and high coherence in the décollement, known to be an interval of arrested consolidation, overlaps the quiet area, suggesting that the arrested consolidation may be related to the lack of thrust imbrication, and thus, vertical drainage for fluid in the accretionary prism. Fractal analysis of the décollement and top of the subducting oceanic basement indicates that the relief of the décollement correlates with the topography of the oceanic basement. Differential compaction of the underthrust sediment overlying the rugged oceanic basement, together with the basement faults that penetrate into the décollement probably caused relief or even faulting in the décollement

Development of Navigation Control Algorithm for AGV Using D* Search Algorithm

In this paper, we present a navigation control algorithm for Automatic Guided Vehicles (AGV) that move in industrial environments including static and moving obstacles using D* algorithm. This algorithm has ability to get paths planning in unknown, partially known and changing environments efficiently. To apply the D* search algorithm, the grid map represent the known environment is generated. By using the laser scanner LMS-151 and laser navigation sensor NAV-200, the grid map is updated according to the changing of environment and obstacles. When the AGV finds some new map information such as new unknown obstacles, it adds the information to its map and re-plans a new shortest path from its current coordinates to the given goal coordinates. It repeats the process until it reaches the goal coordinates. This algorithm is verified through simulation and experiment. The simulation and experimental results show that the algorithm can be used to move the AGV successfully to reach the goal position while it avoids unknown moving and static obstacles. [Keywords— navigation control algorithm; Automatic Guided Vehicles (AGV); D* search algorithm

The Rich Mid-Infrared Environments of Two Highly-Obscured X-ray Binaries: Spitzer Observations of IGR J16318-4848 and GX 301-2

We present the results of Spitzer mid-infrared spectroscopic observations of two highly-obscured massive X-ray binaries: IGR J16318-4848 and GX301-2. Our observations reveal for the first time the extremely rich mid-infrared environments of this type of source, including multiple continuum emission components (a hot component with T > 700 K and a warm component with T ~ 180 K) with apparent silicate absorption features, numerous HI recombination lines, many forbidden ionic lines of low ionization potentials, and pure rotational H2 lines. This indicates that both sources have hot and warm circumstellar dust, ionized stellar winds, extended low-density ionized regions, and photo-dissociated regions. It appears difficult to attribute the total optical extinction of both sources to the hot and warm dust components, which suggests that there could be an otherwise observable colder dust component responsible for the most of the optical extinction and silicate absorption features. The observed mid-infrared spectra are similar to those from Luminous Blue Variables, indicating that the highly-obscured massive X-ray binaries may represent a previously unknown evolutionary phase of X-ray binaries with early-type optical companions. Our results highlight the importance and utility of mid-infrared spectroscopy to investigate highly-obscured X-ray binaries.Comment: To appear in ApJ Letter

Planar Tunneling Spectroscopy of Samarium Hexaboride(SmB6)

As a well-known Kondo insulator originating from strong correlation, SmB6 has attracted much interest because of its surface states being potentially topological. In order to investigate this, we apply the technique of planar tunneling spectroscopy since it can detect the surface density of states (DOS). To acquire stable and clean tunneling spectra, we prepare SmB6 single crystal surfaces by polishing against alumina lapping film. Both (001) and (011) surfaces are studied using this method for comparison. With further ion-beam cleaning/etching under vacuum, tunnel junctions are formed by sputter deposition of Al (with approximate thickness between 2 5 nm) and subsequent plasma oxidation. Then two insulating strips are painted on the surface leaving a narrow conducting area at the center. Finally several silver counter-electrodes are deposited on the top using thermal evaporator. The junctions are defined by the intersections of the silver and the aluminum oxide barrier. Differential conductance is measured over wide ranges of temperature and magnetic field. Interesting features are detected at low temperature. For example, the overall asymmetric shape of conductance over the bias range from 300mV to 300mV, the multiple humps at negative bias voltage which do not evolve linearly with temperature, and the suppressed, linear conductance near zero bias. The asymmetric conductance is possibly a sign of Fano resonance in Kondo insulator, indicating that it might be conceivable to measure the bulk DOS using planar tunneling. The linear conductance at low bias, on the other hand, might be due to surface states. The gap feature of the spectra start to appear at around 50 K and the overall wavy background shape can sustain at around 100 K. *The work at UIUC is supported by the NSF DMR 12-06766.Ope

Planar Tunneling Spectroscopy of Samarium Hexaboride(SmB6)

As a well-known Kondo insulator originating from strong correlation, SmB6 has attracted much interest because of its surface states being potentially topological. In order to investigate this, we apply the technique of planar tunneling spectroscopy since it can detect the surface density of states (DOS). To acquire stable and clean tunneling spectra, we prepare SmB6 single crystal surfaces by polishing against alumina lapping film. Both (001) and (011) surfaces are studied using this method for comparison. With further ion-beam cleaning/etching under vacuum, tunnel junctions are formed by sputter deposition of Al (with approximate thickness between 2 5 nm) and subsequent plasma oxidation. Then two insulating strips are painted on the surface leaving a narrow conducting area at the center. Finally several silver counter-electrodes are deposited on the top using thermal evaporator. The junctions are defined by the intersections of the silver and the aluminum oxide barrier. Differential conductance is measured over wide ranges of temperature and magnetic field. Interesting features are detected at low temperature. For example, the overall asymmetric shape of conductance over the bias range from 300mV to 300mV, the multiple humps at negative bias voltage which do not evolve linearly with temperature, and the suppressed, linear conductance near zero bias. The asymmetric conductance is possibly a sign of Fano resonance in Kondo insulator, indicating that it might be conceivable to measure the bulk DOS using planar tunneling. The linear conductance at low bias, on the other hand, might be due to surface states. The gap feature of the spectra start to appear at around 50 K and the overall wavy background shape can sustain at around 100 K. *The work at UIUC is supported by the NSF DMR 12-06766.Ope

IRAS 15099-5856: Remarkable Mid-Infrared Source with Prominent Crystalline Silicate Emission Embedded in the Supernova Remnant MSH15-52

We report new mid-infrared observations of the remarkable object IRAS 15099-5856 using the space telescopes AKARI and Spitzer, which demonstrate the presence of prominent crystalline silicate emission in this bright source. IRAS 15099-5856 has a complex morphology with a bright central compact source (IRS1) surrounded by knots, spurs, and several extended (~4') arc-like filaments. The source is seen only at >= 10 um. The Spitzer MIR spectrum of IRS1 shows prominent emission features from Mg-rich crystalline silicates, strong [Ne II] 12.81 um and several other faint ionic lines. We model the MIR spectrum as thermal emission from dust and compare with the Herbig Be star HD 100546 and the luminous blue variable R71, which show very similar MIR spectra. Molecular line observations reveal two molecular clouds around the source, but no associated dense molecular cores. We suggest that IRS1 is heated by UV radiation from the adjacent O star Muzzio 10 and that its crystalline silicates most likely originated in a mass outflow from the progenitor of the supernova remnant (SNR) MSH 15-52. IRS1, which is embedded in the SNR, could have been shielded from the SN blast wave if the progenitor was in a close binary system with Muzzio 10. If MSH15-52 is a remnant of Type Ib/c supernova (SN Ib/c), as has been previously proposed, this would confirm the binary model for SN Ib/c. IRS1 and the associated structures may be the relics of massive star death, as shaped by the supernova explosion, the pulsar wind and the intense ionizing radiation of the embedded O star.Comment: 25 pages, 7 figures, Fig. 5 revised. Accepted for publication in Ap