Real-time quality control of data from Sea-Wing underwater glider installed with Glider Payload CTD sensor

Profiles observed by Sea-Wing underwater gliders are widely applied in scientific research. However, the quality control (QC) of these data has received little attention. The mismatch between the temperature probe and conductivity cell response times generates erroneous salinities, especially across a strong thermocline. A sensor drift may occur owing to biofouling and biocide leakage into the conductivity cell when a glider has operated for several months. It is therefore critical to design a mature real-time QC procedure and develop a toolbox for the QC of Sea-Wing glider data. On the basis of temperature and salinity profiles observed by several Sea-Wing gliders each installed with a Sea-Bird Glider Payload CTD sensor, a real-time QC method including a thermal lag correction, Argo-equivalent real-time QC tests, and a simple post-processing procedure is proposed. The method can also be adopted for Petrel gliders.</p

Influence of substrate surface defects on the homoepitaxial growth of GaN (0001) by metalorganic vapor phase epitaxy

Surface morphology of homoepitaxial GaN (0001) grown by metalorganic vapor phase epitaxy was studied. Selective growth was observed on the homoepitaxial GaN layer grown on as received GaN substrate and was attributed to the existence of substrate surface defects. The steps were pinned by defects and meandered. Due to the pinning effect, the step pattern developed to a wavy surface with a strip-like feature along the [11 ($) over bar0] direction during the subsequent growth of a thick n-GaN layer. Because of the surface undulations, the emission of InGaN/GaN multiple quantum wells grown on the n-GaN layer was inhomogeneous. The surface defects on GaN substrate could be removed by dry etching and the homoepitaxial layer on the etched substrate showed a smooth morphology and straight atomic steps. As a result, the emission of the InGaN/GaN MQWs became homogeneous. (C) 2015 Elsevier B.V. All rights reserved

Injection current dependences of electroluminescence transition energy in InGaN/GaN multiple quantum wells light emitting diodes under pulsed current conditions

Injection current dependences of electroluminescence transition energy in blue InGaN/GaN multiple quantum wells light emitting diodes (LEDs) with different quantum barrier thicknesses under pulsed current conditions have been analyzed taking into account the related effects including deformation caused by lattice strain, quantum confined Stark effects due to polarization field partly screened by carriers, band gap renormalization, Stokes-like shift due to compositional fluctuations which are supposed to be random alloy fluctuations in the sub-nanometer scale, band filling effect (Burstein-Moss shift), and quantum levels in finite triangular wells. The bandgap renormalization and band filling effect occurring at high concentrations oppose one another, however, the renormalization effect dominates in the concentration range studied, since the band filling effect arising from the filling in the tail states in the valence band of quantum wells is much smaller than the case in the bulk materials. In order to correlate the carrier densities with current densities, the nonradiative recombination rates were deduced experimentally by curve-fitting to the external quantum efficiencies. The transition energies in LEDs both with 15 nm quantum barriers and 5 nm quantum barriers, calculated using full strengths of theoretical macroscopic polarization given by Barnardini and Fiorentini [Phys. Status Solidi B 216, 391 (1999)] are in excellent accordance with experimental results. The LED with 5 nm barriers has been shown to exhibit a higher transition energy and a smaller blue shift than those of LED with 15 nm barriers, which is mainly caused by the smaller internal polarization field in the quantum wells. (C) 2015 AIP Publishing LLC

High-efficiency InGaN-based LEDs grown on patterned sapphire substrates

<p>GaN films grown on PSS are investigated by XRD, CL, SEM and TEM. There are low threading dislocations (TDs) with larger fill factor, which results in better electrostatic discharge (ESD) yield of LEDs. The effect of growth rate on dislocations in GaN films grown on PSS is investigated by TEM. It is found that dislocations density decreases as the growth rates decrease. And the performance of InGaN-based LEDs on different PSS is analyzed. The performance of LEDs grown on different PSS is determined by slanted angle and fill factor simultaneously. (</p

The bionic actuation and experimental study of a heart simulator

Static heart phantom cannot provide a realistic human heart&#39;s information under movement state and the medical image lacking of intuitionism is unable to provide a real operation training environment. In order to create a lifelike heart beating environment realistically, a unique air pressure cavity is designed between the heart phantom&#39;s fibrous pericardium and artificial myocardium. Based on Windkessel model, a novel actuation circuit is also designed to pump air into/out off the cavity to drive the artificial myocardium contraction and relaxation at certain rhythm. The simulator&#39;s output flow testing experiment was carried out to evaluate its performance. Results showed that its output blood flow curves showed as periodical pulsation. It is much similar to the pulse output characteristic of human heart. When the heart simulator operated at a rate of 75 beats per minute, its cardiac output was 5L and stroke volume was about 66mL. The results indicated that the heart simulator can highly simulate the heart beating process. Besides, the blood flow changes of the heart simulator were conformed to the human physiological parameters

The bionic actuation and experimental study of a heart simulator

Static heart phantom cannot provide a realistic human heart&#39;s information under movement state and the medical image lacking of intuitionism is unable to provide a real operation training environment. In order to create a lifelike heart beating environment realistically, a unique air pressure cavity is designed between the heart phantom&#39;s fibrous pericardium and artificial myocardium. Based on Windkessel model, a novel actuation circuit is also designed to pump air into/out off the cavity to drive the artificial myocardium contraction and relaxation at certain rhythm. The simulator&#39;s output flow testing experiment was carried out to evaluate its performance. Results showed that its output blood flow curves showed as periodical pulsation. It is much similar to the pulse output characteristic of human heart. When the heart simulator operated at a rate of 75 beats per minute, its cardiac output was 5L and stroke volume was about 66mL. The results indicated that the heart simulator can highly simulate the heart beating process. Besides, the blood flow changes of the heart simulator were conformed to the human physiological parameters

Low threshold continuous-wave lasing of yellow-green InGaN-QD vertical-cavity surface-emitting lasers

Low threshold continuous-wave (CW) lasing of current injected InGaN quantum dot (QD) vertical-cavity surface-emitting lasers (VCSELs) was achieved at room temperature. The VCSEL was fabricated by metal bonding technique on a copper substrate to improve the heat dissipation ability of the device. For the first time, lasing was obtained at yellow-green wavelength of 560.4 nm with a low threshold of 0.61 mA, corresponding to a current density of 0.78 kA/cm(2). A high degree of polarization of 94% were measured. Despite the operation in the range of "green gap" of GaN-based devices, single longitudinal mode laser emission was clearly achieved due to the high quality of active region based on InGaN QDs and the excellent thermal design of the VCSELs. (C)2016 Optical Society of Americ

Conductivity enhancement in AlGaN:Mg by suppressing the incorporation of carbon impurity

Growth conditions were explored to suppress the carbon impurity incorporation in AlGaN:Mg grown at low temperatures. Electrical properties of Al0.07Ga0.93N:Mg samples with various carbon concentrations were investigated by Hall measurements. A clear correlation between carbon concentration and electrical conductivity has been found. By reducing the carbon concentration from 2 x 10(18) to 5 x 10(16) cm(-3), the resistivity of p-Al0.07Ga0.93N decreases from 7.4 to 2.2 Omega.cm. From the results of the analysis of the charge neutrality equation, we found that the carbon concentration is close to the compensating donor concentration in the AlGaN:Mg samples, which suggests that carbon acts as the main compensating donor in AlGaN:Mg. (C) 2015 The Japan Society of Applied Physic