Multi-Wavelength Optical Packet Routing Technologies Based on Superstructured Fiber Bragg Gratings

A WDM compatible Edge-to-Edge Self-Routed optical packet switched network that simplifies the optical processing is proposed. The system employs all-optical packet label generation and recognition using coded superstructured Fiber Bragg gratings.     

Conditional Data Mapping Flip-Flops for Low-Power and High-Performance Systems

This paper introduces a new family of low-power and high-performance flip-flops, namely conditional data mapping flip-flops (CDMFFs), which reduce their dynamic power by mapping their inputs to a configuration that eliminates redundant internal transitions. We present two CDMFFs, having differential and single-ended structures, respectively, and compare them to the state-of-the-art flip-flops. The results indicate that both CDMFFs have the best power-delay product in their groups, respectively. In the aspect of power dissipation, the single-ended and differential CDMFFs consume the least power at data activity less than 50%, and are 31% and 26% less power than the conditional capture flip-flops at 25% data activity, respectively. In the aspect of performance, CDMFFs achieve small data-to-output delays, comparable to those of the transmission-gate pulsed latch and the modified-sense-amplifier flip-flop. In the aspect of timing reliability, CDMFFs have the best internal race immunity among pulse-triggered flip-flops. A post-layout case study is demonstrated with comparison to a transmission-gate flip-flop. The results indicate the single-ended CDMFF has 34% less in data-to-output delay and 28% less in power at 25% data activity, in spite of the 34% increase in size     

An experiment to discover mathematical talent in a primary school in Kampong Air

It is often said that many pupils have hidden talent in mathematics. This hidden ability is rarely seen in a normal classroom teaching and learning situation if the focus of the teacher is on drilling with routine exercises. To allow pupils to display their mathematical talent and to break from mental set and fixation in mathematics, they must be given opportunity to think by themselves with mininum cue or guidance. The pupils could be left entirely on their own to show their mathematical creativity even on mathematical topics which have not been exposed to them. With this approach, five non-routine questions were administered one at a time to a standard 5 class. One out of the 25 pupils in the class consistently exhibited mathematical creativity and talent is answering the questions. Her responses were shown and discussed in this paper.     

Stoichiometric and catalytic deuterium and tritium labeling of "unactivated" organic substrates with cationic Ir(III) complexes

[reaction: see text] Ir(III) complex [Cp(PMe(3))IrMe(CH(2)Cl(2))][BAr(f)] (1) was used to introduce deuterium stoichiometrically into substituted naphthalene/benzene templates and several "drug-like" entities. The exchange process is tolerant of a wide array of functional groups. Labeling of warfarin using subatmospheric pressures of T(2) led to specific activities and total activities rivaling current functional group directed tritium labeling methods. When paired with the appropriate deuterium donor, Cp(PMe(3))Ir(H(3))OTf (4) was found to deuterate a number of organic compounds catalytically.     

Synthesis of functional Δ-1,3,5-oxazaphospholene and 2H-1,4,2-diazaphosphole complexes via catalytic ring expansion reactions of a 2H-azaphosphirene complex

Catalytically-induced ring expansion of 2H-azaphosphirene complex 1 using ferrocenium hexafluorophosphate and acetone (2), diethylketone (3), cyclohexanone (4), benzaldehyde (5) or para-hydroxy-benzaldehyde (6) furnished selectively the Δ³-1,3,5-oxazaphospholene complexes 7-11, whereas with ortho- and para-hydroxy- or ortho- and para-amino-substituted benzonitriles the 2H-1,4,2-diazaphosphole complexes 16-19 were obtained. Two further findings are noteworthy: (1) The significant decreased reaction time in the case of the sterically more demanding carbonyl derivatives 2-4 and (2) the formation of diastereomers in the case of 10 and 11 with a ratio of 8:1 and 9:1, respectively. All products were characterized by NMR, MS and elemental analysis and the configuration of complexes 7 and 10a were determined by X-ray single-crystal diffraction analysis.     

Synthesis of TiO2 based on hydrothermal methods using elevated pressures and microwave conditions

Titanium dioxide (TiO₂), especially in its anatase form, is an effective photocatalyst under ultraviolet (UV) light. The particle size of TiO₂ is a critical factor to determine its photoactivity based on its quantum effectiveness under light irradiations. Thus, nanocrystalline TiO₂ has been widely accepted to significantly enhance this effect. The sol–gel method is generally used to synthesize the anatase form of nanocrystalline TiO₂. In this study, we expanded the synthesis method of TiO₂ to high pressures under direct heating (hydrothermal method) and indirect heating (microwave-assisted method). It was found that pH value is one of the major factors to control nano-sizes of TiO₂ particles, and the neutral condition in all methods is preferable for controlling the sizes of the prepared TiO₂ particles. The microwave-assisted method further improves quality of synthesized nano-size TiO₂ below 10 nm. These results have been confirmed by both the direct size measurement using TEM images and indirect determination using XRD peaks. The collected samples are further analyzed using UV–Vis spectroscopy to identify the particle size-dependent photoreactivity and to confirm the effectiveness of microwave-assisting under neutral conditions. DSC is also a powerful tool to identify the crystalline transition of TiO₂.     

Wireless link prediction and triggering using modified Ornstein–Uhlenbeck jump diffusion process

Through time domain observation, typical wireless signal strength values seems to exhibit some forms of mean-reverting and discontinuous “jumps” behaviour. Motivated by this fact, we propose a wireless link prediction and triggering (LPT) technique using a modified mean-reverting Ornstein–Uhlenbeck (OU) jump diffusion process. The proposed technique which we refer as OU-LPT is an integral component of wireless mesh network monitoring system developed by ICT FP7 CARrier grade wireless MEsh Network project. In particular, we demonstrate how this technique can be applied in the context of wireless mesh networks to support link switching or handover in the event of predicted link degradation or failure. The proposed technique has also been implemented and evaluated in a real-time experimental testbed. The results show that OU-LPT technique can significantly enhance the reliability of wireless links by reducing the rate of false triggers compared to a conventional linear prediction technique and therefore offers a new direction on how wireless link prediction, triggering and switching process can be conducted in the future.     

A viscous approximation for a 2-D steady semiconductor or transonic gas dynamic flow: Existence theorem for potential flow

In this paper we solve a boundary value problem in a two-dimensional domain O for a system of equations of Fluid-Poisson type, that is, a viscous approximation to a potential equation for the velocity coupled with an ordinary differential equation along the streamlines for the density and a Poisson equation for the electric field. A particular case of this system is a viscous approximation of transonic flow models. The general case is a model for semiconductors. We show existence of a density ρ, velocity potential φ, and electric potential Φ in the bounded domain O that are C^1,α(O¯), C^2,α(O¯), and W^2,α(O¯) functions, respectively, such that ρ, φ, Φ, the speed |Δφ|, and the electric field E = ΔΦ are uniformly bounded in the viscous parameter. This is a necessary step in the existing programs in order to show existence of a solution for the transonic flow problem. © 1996 John Wiley & Sons, Inc.