Heteropolyacid-based materials as heterogeneous photocatalysts

Heteropolyacids (HPAs) that are often used as heteropolyanions are cheap and stable compounds that have been extensively used as acid and oxidation catalysts as a result of their strong Brønsted acidity and ability to undergo multielectron-transfer reactions. HPAs, which are very soluble in water and polar solvents, have been also used as homogeneous photocatalysts for the oxidation of organic substrates in the presence of oxygen, but their use in heterogeneous systems is by far desirable. Dispersing HPAs onto solid supports with high surface area is useful to increase their specific surface area and hence (photo)catalytic activity. Moreover, owing to the high energy gap between the HOMO and LUMO positions of the HPAs, these compounds are activated only by UV light. Consequently, only less than 5 % of the solar light can be used in photocatalytic reactions, which restricts the practical application of HPAs. This microreview is oriented to describe the reported literature on the use of HPA-based materials as heterogeneous photocatalysts for environmental purposes, that is, for the complete or partial oxidation or reduction of organic molecules

Improved pitch modelling for low bit-rate speech coders

During the last several years, there has been a dramatic growth of digital services, such as digital wireless and wireline communications, satellite communications and digital voice storage systems. Such services require the use of high-quality low bit-rate coders to e-ciently code the speech signal before transmission or storage. The majority of such coders employ algorithms that are based on Code-Excited Linear Prediction (CELP). The goal of this thesis is to improve the quality of CELP coded speech, while keeping the basic coding format intact. The quality improvement is focused on voiced speech segments. A Pitch Pulse Averaging (PPA) algorithm has been developed to enhance the periodicity ofsuch segments, where during steady state voicing the pitch pulse waveforms in the excitation signal evolve slowly in time. The PPA algorithm extracts a number of such pitch pulsewaveforms from the past excitation, aligns them, and then averages them to produce a new pitch pulse waveform with reduced noise. The PPA algorithm has been simulated and tested on a oating point C-simulation of the G.729 8 kbps CS-ACELP coder. Objective tests veri ed that the algorithm contribute

Management of crystalline lens dislocation into the anterior chamber in a victim of domestic violence

A 53-year-old woman presented with a right eye injury due to domestic violence. The crystalline lens in that eye was completely dislocated into the anterior chamber, fixated by the cornea and the iris. Fundoscopy showed a mild vitreous haemorrhage and a giant retinal tear. A modified lensectomy with a fragmatome was performed. During this procedure the capsule was preserved first to minimise the risk of corneal damage and second to reduce vitreous traction, which would repair the giant retinal tear. © 2011 The Authors. Clinical and Experimental Optometry © 2011 Optometrists Association Australia

Experience with fault injection experiments for FMEA

Failure Modes and Effects Analysis (FMEA) is a widely used system and software safety analysis technique that systematically identifies failure modes of system components and explores whether these failure modes might lead to potential hazards. In practice, FMEA is typically a labor-intensive team-based exercise, with little tool support. This article presents our experience with automating parts of the FMEA process, using a model checker to automate the search for system-level consequences of component failures. The idea is to inject runtime faults into a model based on the system specification and check if the resulting model violates safety requirements, specified as temporal logical formulas. This enables the safety engineer to identify if a component failure, or combination of multiple failures, can lead to a specified hazard condition. If so, the model checker produces an example of the events leading up to the hazard occurrence which the analyst can use to identify the relevant failure propagation pathways and co-effectors. The process is applied on three medium-sized case studies modeled with Behavior Trees. Performance metrics for SAL model checking are presented. Copyright (C) 2011 John Wiley & Sons, Ltd