Distributed object‐oriented switching system software platform design

Key technologies are presented and evaluated for establishing a distributed object‐oriented switching system platform. This platform is based on CORBA, which can enhance software productivity and system scalability and is thus widely used in the information technology field. Conditions and requirements specific to switching systems, such as very high‐performance and non‐stop operation, are analysed and mapped to the main elements of CORBA. How to deploy and bind objects so as to minimize the processing load is clarified. Mechanisms that guarantee system reliability (saving calls in service when a system failure occurs and avoiding the spread of faults) are also presented. Evaluation of the number of dynamic program steps for systems using fully compliant CORBA, improved CORBA, and a proprietary high‐speed object‐request broker (ORB) shows that constructing a communication switching system by using the high‐speed ORB approach is sufficient, but CORBA‐compliant approaches should be used to provide an interoperable interface for communicating with external compliant systems. Copyright © 2001 John Wiley & Sons, Ltd.     

Effects of TiN Buffer Layer Thickness on GaN Growth

Smooth GaN layers were successfully grown on metallic TiN buffer layers by metalorganic chemical vapor deposition (MOCVD). One important factor in controlling GaN layer smoothness was the TiN layer thickness. We investigated systematically the effects of this thickness, and found an optimal thickness of 5 nm, at which the smallest average grain size (20 nm) and smoothest surface were obtained. The TiN layers increased surface coverage with GaN hexagons at an early stage of GaN growth, indicating that enhancing the GaN nucleation is essential for smooth GaN layer growth, and small grain size and smooth surface are needed to enhance GaN nucleation. Further reduction in TiN layer thickness to 2 nm decreased the surface coverage with GaN hexagons, and a high density of grooves and holes were observed in the surface of the 2-μm-thick GaN layers. Defect structures in the GaN layers grown on the TiN layers were remarkably changed on reduction of TiN layer thickness from 5 nm to 2 nm. GaN growth was found to be sensitive to the TiN layer thickness between 2 nm and 5 nm.     

High‐resolution and high‐brightness full‐colour “Silicon Display” for augmented and mixed reality

High‐brightness micro‐LED display bonded onto silicon backplane has been successfully demonstrated. The 0.38‐inch full‐colour active matrix LED microdisplay system consists of 352 × 198 pixels. Each pixel is 24 μm square composed of red, green, and blue (RGB) subpixels corresponding to a pixel resolution of 1053 ppi. Quantum‐dot materials are formed on III‐nitride blue micro‐LED array to convert blue light into red and green for full‐colour operation. We have confirmed that this microdisplay, which we call “Silicon Display” has wide colour gamut exceeding 120% of sRGB. We describe the advantage of this colour‐converting approach for the full‐colour micro‐LEDs. Progress toward higher resolution is also described. Brightness of more than 30 000 cd/m² has been confirmed at a driving current density of 4 A/cm² for 3000 ppi blue monochrome micro‐LED prepared for full‐colour Silicon Display. We believe our “Silicon Display” is ideally suited for near‐to‐eye displays for augmented and mixed reality.     

Hierarchical Three-Dimensional Layer-by-Layer Assembly of Carbon Nanotube Wafers for Integrated Nanoelectronic Devices

We report a general approach to overcome the enormous obstacle of the integration of CNTs into devices by bonding single-walled carbon nanotubes (SWNTs) films to arbitrary substrates and transferring them into densified and lithographically processable "CNT wafers". Our approach allows hierarchical layer-by-layer assembly of SWNTs into organized three-dimensional structures, for example, bidirectional islands, crossbar arrays with and without contacts on Si, and flexible substrates. These organized SWNT structures can be integrated with low-power resistive random-access memory.     

Effect of organic loading rate on continuous hydrogen production from food waste in submerged anaerobic membrane bioreactor

The characteristics of hydrogen fermentation in a membrane bioreactor (HF-MBR) fed with food waste were investigated at thermophilic condition. The HF-MBR was operated at three different organic loading rates (OLRs) of 70.2, 89.4 and 125.4 kg-COD/m³/day. Biogas production rate increased from 22.4 to 32.8 and 62.5 l/day with OLR. The maximum Hydrogen yield and production rate were 111.1 mL-H₂/g-VS _added and 10.7 l-H₂/L/day at an OLR of 125.4 kg-COD/m³/day. The total carbohydrate degradation was better than 96% throughout the experimental runs. Continuous H₂ production from food waste with CH₄-free biogas was successfully sustained in the HF-MBR for 90 days. The microbial community was dominated by Clostridium sp. strain Z6. The H₂ production was significantly improved by shortening the retention time and increasing the OLRs. The HF-MBR showed an H₂ production capacity at the high OLRs due to its higher cell retention.     

Epitaxial growth of GaN layers on metallic TiN buffer layers

To improve GaN light-emitting diode light emission, we produced metal organic chemical vapor deposition (MOCVD)-grown, continuous, flat GaN layers on metallic TiN buffer layers deposited on sapphire substrates. Three important conditions were found: (a) the sapphire substrate surface plane should be (1120), (b) the TiN layer surface plane should be (111), and (c) the TiN buffer layer nitrogen content should be higher than that of stoichiometric TiN. Reduction of TiN layer thickness reduced TiN buffer layer surface roughness. Threading dislocation density in GaN layers grown on TiN buffer layers was much lower than that in GaN layers grown on AlN.     

Hydrogen and methane potential based on the nature of food waste materials in a two-stage thermophilic fermentation process

The purpose of this study is to investigate the biological H₂ and CH₄ potential based on the nature of organic waste materials in a two-stage thermophilic fermentation process. Three varieties of actual waste specifically potato, kitchen garbage and bean curd manufacturing waste (okara) were selected. The production rates for H₂ and CH₄ were as follows: potato, 2.1 and 1.2 l/l/d; garbage, 1.7 and 1.5 l/l/d; okara, 0.4 and 1.4 l/l/d in the continuous processes. The H₂ and CH₄ yields were 20–85 ml H₂/g VS_added and 329–364 ml CH₄/g VS_added, respectively. The H₂ yield increased and the CH₄ yield decreased in the order of potato, kitchen garbage and okara. The H₂ yield was shown to be not only dependent on the proportion of carbohydrate but also on the hydrolysis pH of the organic waste, which was influenced by the nature of the organic waste materials. Higher yields of H₂ or CH₄ were obtained when the hydrolysis pH of the organic waste was close to the optimum pH range of H₂-producing bacteria or methanogenic archaea in the two-stage fermentation processes.     

Highly sensitive real-time PCR assay for quantification of toxic cyanobacteria based on microcystin synthetase A gene

The presence of cyanobacterial bloom in water supply reservoirs can cause potential health hazards. In this study, we aimed at the quantification of microcystin-producing cyanobacteria based on the microcystin synthetase A (mcyA) gene using real-time PCR. To perform a highly sensitive real-time PCR assay, the novel primer MSR-2R was designed and a coprecipitation DNA extraction method was used in this study. Cyanobacterial cells could be collected efficiently by coprecipitation with other bacteria suspended in solution even in the case of low concentrations of cyanobacteria. The detection limit of the method was found to be 8.8 cells per reaction. When cyanobacterial growth was monitored in pure culture, the cell concentration determined by real-time PCR positively correlated with the cell concentration determined from direct microscopic count. Furthermore, we could detect and quantify the mcyA gene in lake water samples using real-time PCR. It was concluded that the quantification of the mcyA gene based on real-time PCR is a powerful tool for the rapid quantification of microcystin-producing cyanobacteria in environmental samples.     

水生植物床预处理富营养化水源水中试研究

水生植物床是一种无基质型人工湿地系统 ,利用植物根系吸收、过滤及共生生物的降解作用对水质进行净化。中试研究考察了水生植物床预处理富营养化水源水的效果。结果表明在原水水质为NH3-N 0 75～ 1 6 1mg/L ,浊度 15～ 113NTU ,UV2 54 0 0 4 2～ 0 135cm- 1的条件下 ,NH3-N ,浊度及UV2 54 的平均去除率分别为 30 % ,90 %和 8 8% ;对藻类和CODMn的平均去除率呈季节性变化 ,夏秋季原水藻密度 7 5× 10 5～ 5 14× 10 7个 /L ,CODMn6 4 2～ 15 37mg/L时 ,去除率分别达到90 %和 2 0 %以上 ;冬季原水Chl- a 7～ 2 9 6 μg/L ,CODMn5 35～ 9 2 3mg/L时去除率分别为 85 3%和 11%。