Performance enhancement of GaN SB-MOSFET on Si substrate using two-step growth method

We have grown high quality GaN layers on (1 1 1)-oriented silicon substrate using a two-step growth method and fabricated high-performance normally-off n-channel GaN Schottky-barrier MOSFET (SB-MOSFET). Indium-tin-oxide (ITO) was used as Schottky-barrier contact for source and drain (S/D) because the work function of ITO is close to the electron affinity of GaN. Due to enhanced crystalline quality and reduced surface roughness of GaN layer grown by two-step process, the fabricated device exhibited much improved performances: sufficiently high threshold voltage of 3.75 V, subthreshold slope of 171 mV/dec, low specific on-resistance of 9.98 mΩ cm², and very high field-effect mobility of 271 cm²/V s. This is the highest mobility value among the GaN MOSFETs ever reported so far.     

The New Electricity Market of Singapore: Regulatory framework,market power and competition

This study examines whether the New Electricity Market of Singapore (NEMS) is functioning at a workable level of competition. The generation market of the NEMS appears highly concentrated by a four-firm concentration ratio or the Herfindahl–Hirschman Index. However, other measures of market power present that the NEMS is working at close to a competitive market. First, there seems to be a number of effective competitors in the market. Second, Supply Margin Assessment and Residual Supply Index support that the market is competitive though there are some possibilities in which the largest generator or a few large generators jointly could still have market power. Third, the Lerner Index of the NEMS shows that the generation market is fairly competitive and the Lerner Index adjusted with an industry level price elasticity of demand implies that there has not been much exercise of market power. Finally, vesting contracts—a contractual obligation of a specified quantity of electricity supply to the market—have appeared to be a strong and effective tool to mitigate market power in the NEMS. The vesting contracts are considered the force behind the lowering in the average Uniform Singapore Electricity Price and the Lerner Index in 2004.     

Improved design method for bent pile structures (cast-in-drilled-hole shafts) based on nonlinear characteristics

A fundamental study of bent pile structures subjected to combined loads in multi-layered soil is conducted using in situ load tests and a load transfer approach. The emphasis is on quantifying an improved design method developed by considering the pile’s plastic hinge and the column–pile interaction. An analytical model is developed that takes into account the nonlinear behaviour of materials for different soil–pile conditions. A framework for determining an optimized column–pile diameter ratio on basis of theoretical analysis is proposed through the relation between the column–pile diameter ratio and lateral crack load ratio. Based on the measured results, an optimized limit depth for a minimum steel reinforcement ratio is defined as the relationship between the bending moments and the crack moments of the concrete pile. An optimized limit depth for a minimum steel reinforcement ratio proportionally decreases as pile length increases, and beyond that the limit depth converges at a constant value (?0.3).     

A New Robust Watermark Embedding into Wavelet DC Components

In this paper, we propose a non‐blind watermarking method that embeds a pseudo‐random sequence (watermarks) into wavelet DC components. The DC area is not suitable for embedding because of severe visual degradation. We overcome the degradation problem by embedding watermarks into visually insensitive locations. We compare our experimental results with respect to JPEG compression with Cox's popular correlation‐based method. We also compare the robustness of our technique with other methods registered in CheckMark. This study reveals that the proposed method simultaneously provides good fidelity in quality as well as robustness against external attacks     

Antiperovskite Sr3MN and Ba3MN (M = Sb or Bi) as promising photovoltaic absorbers for thin-film solar cells: A first-principles study

Although lead halide perovskites (LHPs) have emerged as interesting photovoltaic (PV) absorbers for thin-film solar cells, the toxicity of Pb and poor materials stability have hindered the commercialization of solar cells using LHPs. Herein, using density functional theory (DFT) calculations, we suggest antiperovskite nitrides Sr₃MN and Ba₃MN (M = Sb or Bi) as potential Pb-free PV absorbers for thin-film solar cells. State-of-the-art DFT calculations based on the GW approximation show that these compounds have direct bandgaps suitable for PV applications. In addition, they exhibit significant absorption coefficients over 10⁵ cm⁻¹ for the visible light. By calculating spectroscopic limited maximum efficiency, we demonstrate that the film thicknesses of several hundred nanometers are enough for Sr₃MN and Ba₃MN to generate high-power conversion efficiencies over 20%. The analysis of the electron and hole effective masses reveals that these compounds have efficient carrier-diffusion paths allowing for the facile extraction of photocarriers. Lastly, we investigate the band alignments of the materials to help the design of thin-film solar cells.     

A Metadata Design for Augmented Broadcasting and Testbed System Implementation

Augmented reality (AR) is a popular service in mobile devices, and many AR applications can be downloaded from app stores. As TV broadcasting has continued to integrate with the Internet, it has become an area in which the AR concept is able to reside, although in a simple form, such as an advertisement placed in the static region of a scene. There are some restrictions against TV broadcasting realizing AR since TVs are fixed devices and typically do not have GPS, geomagnetic, or acceleration sensors, which are standard equipment in mobile devices. However, the desire to experience AR on a large TV screen has triggered research and development for an ideal AR business model and service type. This paper introduces several use cases for augmented broadcasting services and also presents an augmented broadcasting metadata scheme designed for a broadcasting environment. We also verify some of the use cases and an augmented broadcasting metadata scheme in an implemented augmented broadcasting system based on a hybrid TV platform.