Effect of annealing on microstructure and hydrogenation properties of TiFe + X wt% Zr (X = 4, 8)

The effect of annealing on the hydrogenation characteristics of the TiFe alloy was investigated. Pellets of TiFe + X wt% Zr (X = 4, 8) were synthesized by arc melting, using industrial grade Fe (ASTM 10005) and Ti (ASTM B265 grade 1) and annealed at 1173 K for 24 h under argon atmosphere. Crystal structure and lattice parameters were determined by X-ray diffraction (XRD) pattern. Scanning electron microscopy (SEM) image of these alloys showed important differences in the microstructure before and after annealing. The main effect of annealing was to reduce the scale of the secondary phase. Change of composition for the TiFe phase and the secondary phases was relatively limited. Despite the relatively minor changes in crystal structures, the first hydrogenation kinetics was much slower and hydrogen capacity smaller for annealed samples compared to their as-cast counterparts. The mechanism responsible for the degradation of hydrogenation kinetics is still unclear but it may be due to modification in the chemical composition of the interface between the TiFe phase and the secondary phase.     

Photoluminescent nanodiamonds: Comparison of the photoluminescence saturation properties of the NV color center and a cyanine dye at the single emitter level,and study of the color center concentration under different preparation conditions

Nitrogen-Vacancy (NV) color centers in diamond nanoparticles (NanoDiamonds, NDs) have a great number of applications, in particular in quantum information processing and as cellular fluorescent labels. In this work we compare the photoluminescence properties of a single NV color center embedded in a 30 nm diameter nanodiamond to that of a single organic fluorescent molecule. We also study the photoluminescence properties of NDs prepared under different conditions in order to find the optimal parameters to achieve a high fluorescence yield, which is still an open question in the case of nanocrystals compared to bulk diamond. The results of this study are of interest for the applications of small and bright diamond nanoparticles in nanophotonics and biology.     

Fate of 2‐sulphanylethyl acetate and 3‐sulphanylpropyl acetate through beer aging

Sulphanylalkyl alcohols and their corresponding acetates were investigated in 14 commercial Belgian beers. Although it was the major peak at the pulsed‐flame photometric detector, the empyreumatic 2‐sulphanylethyl acetate was found at concentrations below its individual odour threshold, estimated at 40 µg/L (0–4 µg/L in most fresh beers, 5–12 µg/L in three fresh high‐bitter beers). Both the Ehrlich pathway and hop constituents contribute to this content. In 11 of the investigated samples, synthesis of 2SE‐A and 3‐sulphanylpropyl acetate (roasted, burned) continued during the first three months of storage. Although below their individual thresholds, these compounds might interact by synergy with other aged flavours. As yeast was absent from most of the investigated bottles, chemical degradation of precursors is suspected. Copyright © 2012 The Institute of Brewing & Distilling     

Analysis of aged CD-R: From optical HF signal defects to digital errors

This article focuses on the CD-R defects that cause digital errors when decoding the HF signal delivered by the optical pickup of a player. We often remark that the error rate is not correlated with any of the parameters currently used to qualify the HF signal. We develop a more precise analysis of the HF signal than those of the analysers, in order to explain how errors happen in this case. The information is obtained mainly from the complete histogram of the positions of the transitions. We also check particular signal segments such as the beginnings of data frames. Using these analysis tools, we highlight different kinds of defects on aged CD-R. One of them consists in micrometre-sized dark spots, which are localized on the dye layer. More generally, the defects due to ageing cannot be characterised only by the standard parameters given by analysers.     

A Carrier Recovery Loop for Cognitive Radio Applications

The increasing demands for wireless communication, especially in consumer electronics applications, result in substantially and continuously increasing reliability and quality of service (QoS) requirements. This trend creates a need to introduce intelligent functionalities in the wireless devices, which leads to the concept of cognitive radio (CR) technology. In some CR applications such as dynamic spectrum access (DSA), the CR terminal should be able to modify its transmission parameters in order to communicate with an efficient utilization of the spectrum resource. In such a case, the CR terminal would be capable of reconfiguring itself with minimum supplementary information to achieve best performance. In this paper we propose a blind carrier recovery loop with respect to the modulation scheme suited to CR applications. Unlike conventional solutions which use a separate modulation identification device before performing carrier recovery, the introduced loop employs a hierarchical symbol decision to achieve phase lock, and then the S-curve and the variance of a decision directed phase error detector are used to extract an information about the modulation scheme of the incoming signal. After the phase lock with the hierarchical decision, the constellation used in the received signal is detected, and then the true decisions are used to drive the recovery loop. Results obtained with different digital linear modulations (8-PSK, 16-QAM 16-APSK, 64-QAM) indicate that the introduced loop is capable of achieving a real-time modulation scheme detection as well as keeping phase lock for adaptive modulation scheme transmissions.     

Solving a rich vehicle routing and inventory problem using column generation

The livestock collection problem (LCP) is a rich vehicle routing problem (VRP) extended with inventory constraints. The LCP is a complex planning problem taken from the meat industry, and the goal is to construct a set of vehicle routes to collect animals from farms for slaughter at a slaughterhouse. Several constraints dealing with animal welfare are added, some of these lead to a loading problem where the vehicle capacity depends on the loading sequence. In addition, global constraints to handle production and inventory at the slaughterhouse are needed. This paper presents an exact solution method for the LCP, based on column generation, that solves much larger instances to optimality than what has been done before. The algorithm presented here also solves a richer model that is closer to the underlying real-world problem than previously published work on exact methods for this problem is based on.