Implementing the Omega failure detector in the crash-recovery failure model

Unreliable failure detectors are mechanisms providing information about process failures, that allow to solve several problems in asynchronous systems, e.g., Consensus. A particular failure detector, Omega, provides an eventual leader election functionality. This paper addresses the implementation of Omega in the crash-recovery failure model. We first propose an algorithm assuming that processes are reachable from the correct process that crashes and recovers a minimum number of times. Then, we propose two algorithms which assume only that processes are reachable from some correct process. Besides this, one of the algorithms requires the membership to be known a priori, while the other two do not.     

A new algorithm to compute conjectured supply function equilibrium in electricity markets

Several types of market equilibria approaches, such as Cournot, Conjectural Variation (CVE), Supply Function (SFE) or Conjectured Supply Function (CSFE) have been used to model electricity markets for the medium and long term. Among them, CSFE has been proposed as a generalization of the classic Cournot. It computes the equilibrium considering the reaction of the competitors against changes in their strategy, combining several characteristics of both CVE and SFE. Unlike linear SFE approaches, strategies are linearized only at the equilibrium point, using their first-order Taylor approximation. But to solve CSFE, the slope or the intercept of the linear approximations must be given, which has been proved to be very restrictive.This paper proposes a new algorithm to compute CSFE. Unlike previous approaches, the main contribution is that the competitors’ strategies for each generator are initially unknown (both slope and intercept) and endogenously computed by this new iterative algorithm.To show the applicability of the proposed approach, it has been applied to several case examples where its qualitative behavior has been analyzed in detail.     

Catalytic performance of silica-aluminas synthesised with the help of chitosan biopolymer

Mesoporous amorphous silica-aluminas were synthesised with standard aluminium and silicon sources by means of the formation of inorganic–organic composites with the addition of chitosan biopolymer, and compared to analogous catalysts synthesised conventionally. Some catalysts were subjected to hydrothermal treatment. The resulting specific surface areas were from 480 to 573 m²/g in the untreated samples and 300–430 m²/g in the hydrotreated catalysts, average pore sizes ranging from 32 to 100 Å with sharp, unimodal distributions. The chitosan materials showed higher specific surface areas and larger pore sizes than those of their non-chitosan counterparts. The most important differences in the acidic properties were in the relationships between tetrahedral and octahedral aluminium atoms, the chitosan materials having higher relative amounts of tetrahedral aluminium than the conventional silica-aluminas. Evidences of stabilization in the physical and chemical properties were observed in the chitosan-containing catalysts. The catalytic performance was evaluated with the conversion of tri-isopropylbenzene at 400 °C, to assess activity and accessibility, and cyclohexene at 300 °C, to assess hydrogen transfer properties. The highest activity and accessibility was observed in the hydrotreated, chitosan-containing catalyst, while hydrogen transfer capabilities were similar to those of medium unit cell sizes, equilibrium commercial FCC catalysts.     

Dehydrogenase Enzymes Associated to Glycolysis in Beef Carcasses Stored at 0 °C

After the death of an animal, cell metabolism is controlled locally. The post-mortem oxygen depletion increases the glycolytic activity and lactate production. However, many mechanisms of post-mortem metabolic regulation have not been fully investigated in beef carcasses. In this work, we studied the post-mortem glycolytic behavior (including lactate dehydrogenase) and three dehydrogenase associated to glycolysis (glycerophosphate dehydrogenase, glucose 6-phosphate dehydrogenase, and glycerol dehydrogenase) by using cytochemistry techniques in three fast-twitch muscles (M. longissimus dorsi, M. semimembranosus, and M. cutaneus trunci) of carcasses stored at 0 °C. Our results indicate that glycolysis depends on the type of muscle. The post-mortem glycolytic flux and lactate dehydrogenase activity of M. cutaneus trunci was the lowest of the three muscles studied. Of the other dehydrogenases analyzed, only glycerophosphate and glycerol dehydrogenase showed clear cytochemical reaction. Glucose 6-phosphate dehydrogenase was not used by muscles very much. The glycerophosphate dehydrogenase was the strongest enzymatic activity correlated to the post-mortem glycolytic flux. In addition, a relationship between glycerophosphate dehydrogenase and glycerol dehydrogenase was detected by using a multiple regression model. This phenomenon was studied by using bioinformatics tools, suggesting that glycerophosphate dehydrogenase could oxidize the glycerol in bovine fast-twitch muscles.     

A non-destructive digital imaging method to predict immobilized yeast-biomass

In food fermentation, many types of immobilization systems are used, such as hydrogel entrapment, where alginate is the main biopolymer. One of the important problems in industrial processes is the quantifications of biomass, since the traditional system of direct cell counting cannot be used. In this study, a simple digital imaging method to determine the biomass of yeasts immobilized into alginate capsules was developed. Important evidence of the yeasts growing inside the alginate was the change in the surface color of the capsule. Digital images were taken with different biomass concentration, and the RGB-analysis showed significant differences in the blue field. The histogram of the blue channel was used to develop a PLS multivariate calibration to predict biomass concentration. The method was validated in primary beer fermentation with good efficiency.     

The implementation methodology of the real effects in a NOI nanostructure,aided by simulation and modelling

The SOI transistors permanently offer new candidates as nanodevices. The nothing on insulator NOI transistor was recently derived from the nano SOI–MOSFET family. Their output characteristics were theoretical modelled with an exponential law, validated by simulations. The transfer characteristics presented sometimes increasing and others times decreasing monotony. This phenomenon was put directly into a relationship with the gate tunnelling breakdown. This paper has three final targets: the breakdown limitation through the back-gate terminal, the real effects including in the NOI transistor architecture – like interface charges or metal-semiconductor work function and quantum effects corrections in simulations, in order to produce a better correlation between simulations and a real behaviour. These simulations represent a milestone in the NOI nanotransistor manufacturing, establishing some parameters that link the device to the real work regime.     

Determination of the refractive index and thickness of holographic silver halide materials by use of polarized reflectances

A method to determine the refractive index and thickness of silver halide emulsions used in holography is presented. The emulsions are in the form of a layer of film deposited on a thick glass plate. The experimental reflectances of p-polarized light are measured as a function of the incident angles, and the values of refractive index, thickness, and extinction coefficient of the emulsion are obtained by using the theoretical equation for reflectance. As examples, five commercial holographic silver halide emulsions are analyzed. The procedure to obtain the measurements and the numerical analysis of the experimental data are simple, and agreement of the calculated reflectances, by use of the thickness and refractive index obtained, with the measured reflectances is satisfactory.     

Useful network transformations and reconfigurable analogue filters using the complementary transformation

In this paper it is shown that some of the useful network transformations, such as low pass (LP) to band pass (BP), LP to high pass (HP) and HP to BP can be obtained by means of the complementary transformation (CT). Furthermore, because the CT is a topological one (i.e. the component values remain unchanged, but their position within the circuit changes), it is suitable to realize reconfigurable analogue filter arrays. As an example, a full list of the obtainable GIC‐based filters, along with their design equations, is also presented. Copyright © 2001 John Wiley & Sons, Ltd.