A Closed‐Form Solution of Linear Spectral Transformation for Robust Speech Recognition

The maximum likelihood linear spectral transformation (ML‐LST) using a numerical iteration method has been previously proposed for robust speech recognition. The numerical iteration method is not appropriate for real‐time applications due to its computational complexity. In order to reduce the computational cost, the objective function of the ML‐LST is approximated and a closed‐form solution is proposed in this paper. It is shown experimentally that the proposed closed‐form solution for the ML‐LST can provide rapid speaker and environment adaptation for robust speech recognition.     

Interference Mitigation Using Uplink Power Control for Two-Tier Femtocell Networks

This paper proposes two interference mitigation strategies that adjust the maximum transmit power of femtocell users to suppress the cross-tier interference at a macrocell base station (BS). The open-loop and the closed-loop control suppress the cross-tier interference less than a fixed threshold and an adaptive threshold based on the noise and interference (NI) level at the macrocell BS, respectively. Simulation results show that both schemes effectively compensate the uplink throughput degradation of the macrocell BS due to the cross-tier interference and that the closed-loop control provides better femtocell throughput than the open-loop control at a minimal cost of macrocell throughput.     

Highly efficient pure white phosphorescent organic light-emitting diodes using a deep blue phosphorescent emitting material

A high efficiency pure white phosphorescent organic light-emitting diode was developed by combining a deep blue emitting phosphorescent dopant material with red/green phosphorescent emitting materials. A simple stack structure of blue/red:green was used and tris((3,5-difluoro-4-cyanophenyl)pyridine) iridium was used as a deep blue emitting phosphorescent dopant. A pure white emission with a color coordinate of (0.29, 0.31) and a very high current efficiency of 28 cd/A was obtained after managing the device architecture of the all phosphorescent white devices.     

Improved device performances in polymer light-emitting diodes using a stamp transfer printing process

The device performances of spin-coated and stamp transfer printed devices were compared. There was little difference of morphology between the spin-coated and stamp transfer printed devices. However, the stamp transfer printing process was better than the spin-coating process in terms of current density, light-emitting efficiency and lifetime. In particular, the lifetime of the stamp transfer printed device was doubled compared with that of the spin-coated device.     

High efficiency red phosphorescent organic light-emitting diodes using a spirobenzofluorene type phosphine oxide as a host material

High efficiency red phosphorescent organic light-emitting diodes have been developed using a spirobenzofluorene type phosphine oxide (SPPO2) as a host material. The SPPO2 had a high glass transition temperature of 119 °C and a smooth surface morphology with a surface roughness less than 1 nm. The red device with the SPPO2 as a host showed a quantum efficiency of 14.3% with a current efficiency of 20.4 cd/A.     

Hole injection improvement by doping of organic material in copper phthalocyanine

Hole injection properties of copper phthalocyanine (CuPc) layer doped with hexaazatriphenylene–hexacarbonitrile (HAT) were studied by changing the doping concentration of HAT. Hole injection efficiency of CuPc layer was improved by doping of HAT as a p-dopant and a maximum current density was obtained at a HAT doping concentration of 10%. The use of HAT doped CuPc layer as a hole injection layer improved the current efficiency of green phosphorescent organic light-emitting diodes.     

Effect of Ni<Superscript>2+</Superscript>, V<Superscript>4+</Superscript> and Mo<Superscript>6+</Superscript> concentration on iron oxidation by <Emphasis Type="Italic">Acidithiobacillus ferrooxidans</Emphasis>

The ferrous oxidation ability of Acidithiobacillus ferrooxidans was studied in the presence of Ni²⁺, V⁴⁺ and Mo⁶⁺ in 9 K media in order to implement the culture in the bioleaching of spent catalyst. The rate of iron oxidation decreased with increasing concentration of metal ions, but the rate of inhibition was metal-ion dependent. The tolerance limit was critical at a concentration of 25 g/L Ni²⁺, 5 g/L V⁴⁺ and 0.03 g/L Mo⁶⁺. The growth rate of microorganisms was negligible at concentrations of 6 g/L V⁴⁺ and 0.04 g/L Mo⁶⁺. Levels and degree of toxicity of these ions have been quantified in terms of a toxicity index (TI). The toxicity order of metal ions was found to be Mo⁶⁺>V⁴⁺>Ni²⁺. The significance and relevance of multi-metal ion tolerance in Acidithiobacillus ferrooxidans has been highlighted with respect to bioleaching of spent refinery catalyst.     

Smart packaging: sensors for monitoring of food quality and safety

The development of chemical sensors and biosensors over several decades has been investigated resulting in novel and very interesting sensor devices with great promise for many areas of applications including food technology. The incorporation of such sensors into the food packaging technology has resulted what we call smart or intelligent packaging. These are truly integrated and interdisciplinary systems that invoke expertise from the fields of chemistry, biochemistry, physics and electronics as well as food science and technology. Smart packaging utilises chemical sensor or biosensor to monitor the quality & safety of food from the producers to the costumers. This technology can result in a variety of sensor designs that are suitable for monitoring of food quality and safety, such as freshness, pathogens, leakage, carbon dioxide, oxygen, pH, time or temperature. Thus, this technology is needed as on-line quality control and safety in term of consumers, authorities and food producers, and has great potential in the development of new sensing systems integrated in the food packaging, which are beyond the existing conventional technologies, like control of weight, volume, colour and appearance.     

Performance improvement of a horizontal zigzag type mist eliminator using slit plates

Journal of Mechanical Science and Technology - In this study, the performance of a zigzag type mist eliminator with drainage channels was improved using slit plates. The collection efficiency of...