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As for uncertainties of ranging and direction angle in the ultrasonic sensor measurement, an ultrasonic distance measurement model is first proposed for representing these uncertainties through analyzing the working principle of the ultrasonic sensor, which can be adopted to detect the contour of wall plan and cylinder. Moreover, the Dezert–Smarandache Theory (DSmT) method is employed to fuse the uncertainty data measured by using the ultrasonic sensor. Next, extended Hough transform (EHT) and least-squares method (LSM) are combined to identify the environmental contour. Then, the measurement uncertainty of the ultrasonic sensor is analyzed for setting the threshold Th used for distinguishing line and cylinder, and the detection range of the cylinder radius is estimated. Finally, we build an indoor environment and design the ultrasonic sensor hardware system to detect the indoor environment for experimental verification. The indoor environment contour obtained in the experimental results is consistent with the real environment, which illustrates the feasibility and effectiveness of the proposed method. The proposed method has certain reference value for research of simultaneous localization and mapping (SLAM) of the mobile robot.

Surface-enhanced Raman scattering (SERS) has been widely reported to improve the sensitivity of Raman spectra. Ordinarily, the laser is focused on the sample to measure the Raman spectrum. The size of the focused light spot is comparable with that of micro-nano structures, and the number of micro-nano structures contained in the light spot area (defined as duty cycle) will severely affect the spectrum intensity. In this study, flower-like silver nanostructures were fabricated with a soft lyotropic liquid crystal template in order to investigate the effect of duty cycle. They were observed under a scanning electron microscope, and their spectrum enhancement factor was computed with the obtained Raman spectrum. Then, their duty cycles were measured using a SERS substrate at different locations. A formula was derived to represent the relation between the duty cycle of the nanoflowers and the Raman spectral intensity. This work could promote the actual applications of SERS in high-sensitivity spectrum testing.

Successful remediation of organics and heavy metals compound pollution is challenging, and their removal using conventional techniques is often difficult. This study developed an enhanced electrokinetics technology to decontaminate a hydrocarbon–heavy metal co-contaminated soil by applying biostimulation and selective membranes (cationic and anionic). A 30-day experiment was conducted in the laboratory to remediate the soil co-contaminated with total petroleum hydrocarbon (TPH) (9075 mg/kg) and Ni (446.6 mg/kg). The results demonstrated that the addition of anion- and cation-exchange membranes maintained soil pH stability. BioEK remediation under pH control improved microbial growth, microbial degradation of petroleum and reduced biological toxicity. Microbial action immobilized metals (e.g., reduction in exchangeable Ni and the increase in residual Ni). The degradation rate of TPH in contaminated soil was linearly correlated with the increase in TPH degradation population (P

The deposited W layers formed on the W plate by hydrogen plasma sputtering were exposed to deuterium plasma in EAST together with bare W plate. In TDS measurement, the deuterium release was clearly observed from the deposited W layer in addition to the release of hydrogen which was incorporated during the sputtering-deposition processes. On the other hand, the release of hydrogen isotope was not detected from the bare W plate. This suggests that the formation of deposited W layers increases tritium inventory in the plasma confinement vessel. Although the thermocouple contacting to the backside of the W plate did not indicate a remarkable temperature rise, deuterium release peaks from the W layer were close to that from the W layer irradiated by 2keV D2+ at 573K. It was found by glow discharge optical emission spectrometry analysis that retained deuterium in the W layer has a peak at the depth of 50nm and gradually decreases toward the W substrate. From X-ray photoelectron spectroscopy analysis, it was evaluated that W oxide existed just at the surface and W atoms in the bulk of deposited W layer were not oxidized. These data suggest that hydrogen isotopes are not retained in W oxide but grain boundaries. Keywords: Deuterium retention, Deposited tungsten, EAST

Application of lithium (Li) or silicon (Si) wall coating in the Experimental Advanced Superconducting Tokamak (EAST) has proven to be an effective method to reduce fuel recycling and control impurity level, and also to improve the plasma performance. In 2014, the upper graphite divertor in EAST was upgraded into a full tungsten (W) one with ITER-like actively water-cooled monoblock structure. Note that there is still large surface area of first wall covered by graphite tiles, including the lower divertor, NBI shine through armor, the outboard guard limiters, etc. In 2016 spring campaign, both Li and Si were used to coat the first wall in experimental sequences that lasted more than one month each. The spectroscopic observation reveals that compared to Si coating, Li coating more effectively suppresses in-vessel impurities, thus mitigating the W source in upper divertor. This is further quantified by a reduction of the effective W sputtering yield calculation. Carbon (C) impurity is suggested as the main impurity governing W sputtering, and correlates inverselywith the wall coating evolution during both one-day experiments and the whole campaign. The impurity concentration increases measurably after every vacuum vessel exposure to air during the campaign; substantial time is required for impurities to return to baseline levels. Real-time Li aerosol injection into the upper divertor effectively reduces the W sputtering by cooling the edge plasma and dissipating the power flux to divertor target, consequently providing an active tool for radiation divertor control. Keywords: Lithium and silicon coating, Tungsten erosion, Impurity concentration, Spectroscopic diagnosis

Minority carrier lifetime and diffusion length are important parameters for GaN based material and devices. In this work, we obtained the minority carrier lifetime and diffusion length of p-GaN through the photoluminescence lifetime of the band edge peak, and analyzed the recombination behavior of carriers. Besides, the dependence of photoluminescence lifetime of GaN: Mg grown by MOCVD on annealing temperature (TA) and Mg concentration ([Mg]) has been investigated through Time-resolved Photoluminescence (TRPL) measurements. We increased the activated Mg acceptors ratio by increasing TA, analyzed the fast and slow decay of carrier recombination, and compared the effects of annealing on the lifetime of GaN band-edge emission with different Mg concentrations. And it is found that the minority carrier lifetime in p-GaN is not only related to Mg concentration, but also related to the activated Mg acceptors concentration / hole concentration. Meanwhile, we compared heteroepitaxial p-GaN with homoepitaxial p-GaN, and further analyzed the influence of dislocation as non-radiative recombination centers (NRCs) on carrier lifetime and recombination behavior.

Molten salt electrodeposition is a promising technology to manufacture the first wall of a fusion reactor. Deuterium (D) retention behavior in molten salt electrodeposition tungsten (W) coatings has been investigated by D-plasma exposure in the EAST tokamak and D-ion implantation in an ion beam facility. Tokamak exposure experiments demonstrate that coatings prepared with lower current density exhibit less D retention and milder surface damage. Deuterium-ion implantation experiments indicate the D retention in the molten salt electrodeposition W is less than that in vacuum plasma spraying W and polycrystalline W.

The ITER-like tungsten divertor with toroidally symmetric 1 mm × 1 mm chamfers on monoblock tiles has been installed in EAST in 2014. Hot spots were experimentally observed mostly along the toridial facing gaps between two columns of W/Cu monoblock units, which are often aggravated by installation misalignment. These hot spots can significantly degrade the power handling capability of W divertor and need to be alleviated. A numerical optimization model for tile chamfering design is built based on the finite element method (FEM), in which the numerical experiments are designed by the uniform table. The calculation results in ANSYS for these experiments are then processed employing the code Design and Analysis of Computer Experiments (DACE) in which the Kriging method is adopted to reconstruct a response surface. The optimum geometry can be derived from the minimum point on the surface. The results show that, under 200 MW/m2 parallel heat flux with an inclination angle of 3° with respect to tile surface, the maximum temperature on W tile with a 0.5 mm misalignment can be decreased to 2084 °C by adopting an optimized single-sided chamfer, 1.8 times lower than 1 mm × 1 mm symmetrically chamfered tile. The optimum chamfering geometry has a strong dependence on the inclination angle of plasma flux to tile surface. As a result, the monoblock tiles in a flat cassette module need to be chamfered differently to adapt to the varied inclination angles.

We suggest a thermal rectification structure where a semi-infinite InSb plate and a semi-infinite 3C–SiC plate coated by black phosphorus (BP) sheets are separated by a nanoscale vacuum gap. To obtain high and tunable thermal rectification efficiency, we employ the temperature-dependent dielectric properties of both InSb and 3C–SiC, and introduce BP sheets with in-plane anisotropy into the structure. Based on fluctuational electrodynamics, the near-field radiative heat transfer and the rectification efficiency are calculated. It is found that the rectification efficiency varies very sensitively with the emitter's temperature, the chemical potential and the number of BP layers, thus opening up possibilities to control the rectification efficiency through these parameters. Higher rectification efficiencies are obtained under some certain conditions, and the origins of the thermal rectification effect are elucidated in some detail. The obtained results might be helpful in designing a BP-based high-efficiency thermal diode.

We present a study of the optical propagation properties of one-dimensional (1D) MoS2/metal photonic crystals (PCs) formed by periodic stacking of alternating MoS2 and metal layers in ambient air atmosphere. The propagation properties of light moving in such a structure are solved using the transfer matrix method. The optical properties of the MoS2/metal PCs are obtained analytically as a function of the materials used, the thicknesses of the layers, and the number of units. Among Ag, Al, Ni, and Fe, Ag was the most suitable metal for constructing PCs in the visible light range. The transmission spectra of the MoS2/Ag PCs exhibited periodic oscillation, with 1, 2 photonic band gaps (PBGs) in the 400–800 nm range when the thickness of the Ag film was 1–2 nm, and the optimum number of periodic units, N, was 10-20. Beyond this range, the transmittance of the structures monotonically decreased with increasing wavelength. The periodic oscillation properties of transmittance in MoS2/Ag 1D PCs can be used in sensors and detectors and as real-time monitors for biological and medical technology fields.

In this paper, we will experimentally investigate the power threshold (PL-H) in upper single null plasmas with an ITER-like tungsten divertor under different ∇B drift directions on EAST [F. Ding et al., Commissioning and PSI Behavior of the ITER-Like W/Cu Divertor in EAST 22nd PSI, Rome (2016)]. The power threshold for the low (L) to high (H) confinement mode has a clear and positive toroidal magnetic field, BT, dependence when the ∇ B drift points toward the primary X-point (Bx∇B↑). A factor of 2-3 increase in PL-H is observed for the ∇B drift away from the primary X-point (Bx∇B↓). The edge and core impurities quantified by spectroscopy measurements show comparable levels for the transitions for both drift directions. On the other hand, it is found that the divertor Dα emission just prior to the L-H transition is lower for Bx∇B↑, compared with that for Bx∇B↓. The upper in-out divertor asymmetry, as manifested by particle fluxes measured by the divertor triple Langmuir probe, is most marked for Bx∇B↓, and with significantly more particle flux to the outer divertor. The reversing field increases the particle flux into the upper inner and lower outer divertor, reducing the in-out asymmetry. One important distinction between the two field directions has been observed, with respect to the amplitude of the scrape-off layer (SOL) parallel flow. A dedicated experiment under similar target plasma conditions shows a lower SOL density and thus a steeper density gradient slightly inside the separatrix, where a lower PL-H is found for the Bx∇B↑, compared to that for Bx∇B↓. We, therefore, conclude that the fielddependent SOL plasma conditions play an important role in the transition physics.

The ITER beryllium (Be) first wall (FW) panels are shaped to protect leading edges between neighbouring panels arising from assembly tolerances. This departure from a perfectly cylindrical surface automatically leads to magnetically shadowed regions where eroded Be can be re-deposited, together with co-deposition of tritium fuel. To provide a benchmark for a series of erosion/re-deposition simulation studies performed for the ITER FW panels, dedicated experiments have been performed on the EAST tokamak using a specially designed, instrumented test limiter acting as a proxy for the FW panel geometry. Carbon coated molybdenum plates forming the limiter front surface were exposed to the outer midplane boundary plasma of helium discharges using the new Material and Plasma Evaluation System (MAPES). Net erosion and deposition patterns are estimated using ion beam analysis to measure the carbon layer thickness variation across the surface after exposure. The highest erosion of about 0.8??m is found near the midplane, where the surface is closest to the plasma separatrix. No net deposition above the measurement detection limit was found on the proxy wall element, even in shadowed regions. The measured 2D surface erosion distribution has been modelled with the 3D Monte Carlo code ERO, using the local plasma parameter measurements together with a diffusive transport assumption. Excellent agreement between the experimentally observed net erosion and the modelled erosion profile has been obtained.