All-optical XOR in a semiconductor optical amplifier-assisted fiberSagnac gate

All-optical Boolean XOR is demonstrated on a high-speed serial bit stream with a three-optical input fiber Sagnac interferometer switch, which uses a semiconductor optical amplifier. Full duty cycle bit switching has been demonstrated up to 5 GHz with contrast ratio as high as 14.6 dB     

Performance study of gradient correlation for sub-pixel motion estimation in the frequency domain

The authors present a performance study of gradient correlation in the context of the estimation of interframe motion in video sequences. The method is based on the maximisation of the spatial gradient cross-correlation function, which is computed in the frequency domain and therefore can be implemented by fast transformation algorithms. Enhancements to the baseline gradient-correlation algorithm are presented which further improve performance, especially in the presence of noise. A comparative performance study is also presented, which demonstrates that the proposed method outperforms state-of-the-art methods in frequency-domain motion estimation, in the shape of phase correlation, in terms of sub-pixel accuracy for a range of test material and motion scenarios.     

Matrix effect during the application of a rapid method using HS-SPME followed by GC–ECD for the analysis of 2,4,6-TCA in wine and cork soaks

An off-flavor in wine known as ‘cork taint’ is of concern in the wine and cork industry. Cork taint imparts a musty flavor to the wine and is primarily due to the presence of 2,4,6-trichloroanisole [2,4,6-TCA] in cork stoppers. During this study, an instrumental method for 2,4,6-TCA analysis was developed and evaluated using headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled with an electron capture detector (GC–ECD). 2,3,6-Trichlorotoluene [2,3,6-TCT] was assayed as the internal standard. The method was developed in synthetic wine and was applied in commercial wine samples, as well as in cork soaks obtained by the extraction of TCA from cork stoppers and cork barks using synthetic wine. The method performance was evaluated through the estimation of its linearity (R² > 0.99), repeatability (RSD value = 5.72%) and sensitivity (recovery > 86%, LOD = 0.177–0.368 ng/L) in different types of samples. Due to the complexity of the samples used, the study has been especially focused on the matrix effects that were identified causing significant bias to the quantitative analysis of 2,4,6-TCA in cork soaks, where there is a lack of previous studies.     

Streaming Time Series Summarization Using User-Defined Amnesic Functions

The past decade has seen a wealth of research on time series representations. The vast majority of research has concentrated on representations that are calculated in batch mode and represent each value with approximately equal fidelity. However, the increasing deployment of mobile devices and real time sensors has brought home the need for representations that can be incrementally updated, and can approximate the data with fidelity proportional to its age. The latter property allows us to answer queries about the recent past with greater precision, since in many domains recent information is more useful than older information. We call such representations amnesic. While there has been previous work on amnesic representations, the class of amnesic functions possible was dictated by the representation itself. In this work, we introduce a novel representation of time series that can represent arbitrary, user-specified amnesic functions. We propose online algorithms for our representation, and discuss their properties. Finally, we perform an extensive empirical evaluation on 40 datasets, and show that our approach can efficiently maintain a high quality amnesic approximation.     

A review on microcombustion: Fundamentals,devices and applications

Microcombustion research has flourished over the past decade. Yet, most of the commercial potential of microcombustion is still to come. Aside from portable electronics, emerging drivers stem from the energy problem of declining fossil fuel reserves and their large environmental footprint upon combustion. The need to capitalize on underutilized energy sources and renewables further stimulate energy research in microsystems. In this review paper, technological drivers, applications, devices, and fabrication protocols of microburners are presented. Then, a review of homogeneous, catalytic, homogeneous-heterogeneous and heat recirculating microburners is given. Results are presented that interpret literature findings. An outlook of microcombustion research is finally outlined.     

High vs. low temperature reforming for hydrogen production via microtechnology

Hydrogen production from a multifunctional microdevice consisting of thermally coupled catalytic plate combustion and reforming microreactors is simulated for methane and methanol reforming as representatives of a high and a low temperature process, respectively. Both reforming processes are feasible at microscales with high conversions over a wide combustible and reforming stream inlet velocity range, and can be tuned to provide variable power output. Interestingly, in low temperature reforming, the fraction of heat release that is wasted, as “excess enthalpy” in the products, is not significantly lower than in high temperature reforming at the breakthrough limit. Along the breakthrough line, more than 30% higher power efficiency to hydrogen is predicted for the methanol system due to the high CO₂:CO ratio. Finally, matching the reaction zones in the two channels via proper choice of catalyst loadings and channel gap sizes can alleviate hot spots and axial temperature gradients promoted by low conductivity materials.     

Reactive adsorption for the selective dehydration of sugars to furans: Modeling and experiments

5‐hydroxymethylfurfural (HMF) can be produced from the acid‐catalyzed dehydration of fructose, but its yield is limited due to subsequent HMF degradation to side products. A reactive adsorption process is proposed to improve the yield to HMF. Separate experimental single‐component isotherms of fructose, HMF, formic acid, and levulinic acid on carbon BP2000 and reaction kinetics of the fructose dehydration to HMF in aqueous solution of HCl are presented to develop empirical isotherms and kinetic rate constants, respectively. These submodels are subsequently integrated in an adsorptive reactor at a range of temperatures (100–150^°C) with different loadings of adsorbent. It is shown that the adsorbent improves HMF yield compared to the single‐solution phase (adsorbent‐free case). Low temperatures and high‐adsorbent loadings improve HMF yield. Under certain conditions both reactive adsorption and the commonly used reactive extraction can result in a similar improvement in HMF yield. HMF recovery from the solid adsorbent has been identified as a major challenge that can be ameliorated through adsorbent and solvent selection. The framework outlined here can be applied to any aqueous phase chemistry where the desired product is an intermediate in a reaction cascade. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3378–3390, 2013     

Comparison of Ethylene Glycol Steam Reforming Over Pt and NiPt Catalysts on Various Supports

Steam reforming of ethylene glycol (EG) was studied on Pt and NiPt catalysts supported on γ-Al₂O₃, TiO₂, and carbon. On all supports bimetallic NiPt catalysts show higher activity for H₂ production than the corresponding Pt catalysts as predicted from model surface science studies. The kinetic trends are similar for all catalysts (Pt and NiPt) with the H₂ production rate being zero-order and fractional order with respect to water and ethylene glycol, respectively. Slight differences in selectivity to minor products are observed depending both on active metal and support. On γ-Al₂O₃, NiPt shows higher H₂ and less alkane formation than Pt. TiO₂ supported catalysts show increased water-gas shift activity but also increased selectivity to alkane precursors. NiPt/C is identified as an active and selective catalyst for EG reforming.     

Magnetic properties of textured CoPd nanocrystalline thin films

CoPd is an important nanomaterial for magnetic and magneto-optic storage of information. In this work, CoPd alloyed thin films are grown via radio frequency magnetron sputtering on silicon, glass and polyimide substrates in a vacuum chamber with base pressure of 5 x 10(-8) mbar. The films are nanocrystalline with grain size between 4 and 80 nm. The magnetic properties of thoroughly textured CoPd alloyed thin films are compared to random polycrystalline ones. Magnetization hysteresis loops recorded under fields up to 12 kOe via a home-made magneto-optic Kerr-effect magnetometer reveal strong tendency for perpendicular magnetic anisotropy for the textured film. This anisotropy leads to the formation of well-defined stripe or labyrinthine ferromagnetic domains with the local spins oriented perpendicular to the film plane. The domain patterns and the hysteresis loops are simulated with micromagnetic calculations. Finally, an induced magnetic moment of 0.44 microB/atom is measured for Pd via X-ray magnetic circular dichroism and it is separated into spin and orbital magnetic moment contributions.