Automated keratometry at low cost

Describes an automatic optical system that is attached to a slit lamp in order to provide automatic keratometry at low cost. The system consists of projecting a light ring as a target onto the patient's cornea as well as analysis of the deformation of the target in order to obtain the radius of curvature and the axis of the associated astigmatism. The reflected image of the target is displayed on a PC monitor, while dedicated software performs the analysis of the image, which provides the corneal keratometry     

Degradation Kinetics of Anthocyanin in Blueberry Juice during Thermal Treatment

ABSTRACT: The kinetics of anthocyanin degradation in blueberry juice during thermal treatment at 40, 50, 60, 70, and 80 °C were investigated in the present study. Anthocyanin degradation was analyzed up to the level of 50% retention using a pH differential method. The degradation of anthocyanin at each temperature level followed a first-order kinetic model, and the values of half-life time (t_1/2) at temperatures of 40, 50, 60, 70, and 80 °C were found to be 180.5, 42.3, 25.3, 8.6, and 5.1 h, respectively. The activation energy value of the degradation of the 8.9 ° Brix blueberry juice during heating was 80.4 kJ·mol⁻¹. The thermodynamic functions of activation (ΔG, ΔH, and ΔS) have been determined as central to understanding blueberry degradation.     

Durability of Blended Cement Pastes Containing Ceramic Waste as a Pozzolanic Addition

Durability is one of the focal points of recent research on the behavior of new blended cement matrices in aggressive environments. The material selected for this study was ceramic waste (CW) rejected by Spanish manufacturers, primarily for reasons such as unsuitable kiln temperature or dimensional or mechanical failure. The resistance of CW‐containing cement pastes to three aggressive environments (SO₄^2?, Cl^?, and substitute seawater) was tested using the Koch–Steinegger method in this in‐depth analysis of the effect of CW on the chemical resistance of new blended matrices. The samples were also tested for performance in freeze–thaw cycles. The reaction mechanism was analyzed using X‐ray diffraction (XRD), pore‐size distribution, scanning electron microscopy (SEM), and backscattered electron images (BSE) with energy‐dispersive X‐ray (EDX) techniques. The results showed that CW contributed to cement resistance to such media; this enhancement of its mechanical properties was the result of the pozzolanic reaction induced by the addition of CW.     

Mass transfer kinetics during osmotic dehydration of bananas (Musa sapientum,shum.)

Osmotic dehydration is used widely to partially remove water from plant tissues by immersion in a hypertonic solution. In this work, the influence of temperature (25–55 °C), sugar concentration (30–60%) and salt concentration (0–10%) of the osmotic solution was investigated during osmotic dehydration of banana (Musa sapientum, shum.). Mass transfer kinetics were modelled according to Peleg’s equation. Kinetic parameters were evaluated using response surface methodology. Peleg’s equation showed to be suitable for modelling the water removal and solute uptake. Initial rate of water loss and water concentration at equilibrium were influenced by linear factors of the three independent variables. Initial rate of sucrose uptake and sucrose uptake at equilibrium were affected by all factors and interactions. Initial rate of salt uptake and salt concentration at equilibrium showed a positive correlation with temperature and NaCl concentration and a negative correlation with sucrose concentration.     

Shedding light on catalytic ignition: coverage changes during CO oxidation on Pd(110)

Catalytic ignition or ‘light-off’ has been studied for a reaction of importance in automobile exhaust emissions, namely, CO oxidation over Pd, a metal which has become an important component of car catalysts. We present kinetic and spectroscopic studies to show that light-off is associated with a step change in surface composition of reactants as the surface is heated. Fast XPS using synchrotron radiation of high brightness reveals that the surface is dominated by CO at low temperature and the coverage suddenly switches during light-off to an oxygen-atom-dominated situation. This revised version was published online in August 2006 with corrections to the Cover Date.     

A universal architecture for designing efficient modulo 2/sup n/+1 multipliers

This paper proposes a simple and universal architecture for designing efficient modified Booth multipliers modulo (2/sup n/+1). The proposed architecture is comprehensive, providing modulo (2/sup n/+1) multipliers with similar performance and cost both for the ordinary and for the diminished-1 number representations. The performance and the efficiency of the proposed multipliers are evaluated and compared with the earlier fastest modulo (2/sup n/+1) multipliers, based on a simple gate-count and gate-delay model and on experimental results obtained from CMOS implementations. These results show that the proposed approach leads on average to approximately 10% faster multipliers than the fastest known structures for the diminished-1 representation based on the modified Booth recoding. Moreover, they also show that the proposed architecture is the only one taking advantage of this recoding to obtain faster multipliers with a significant reduction in hardware. With the used figures of merit, the proposed diminished-1 multipliers are on average 10% and 25% more efficient than the known most efficient modulo (2/sup n/+1) multipliers for Booth recoded and nonrecoded multipliers, respectively.     

Fast solutions for UC problems by a new metaheuristic approach

Due to its combinatorial nature, the Unit Commitment problem has for long been an important research challenge, with several optimization techniques, from exact to heuristic methods, having been proposed to deal with it.

In line with one current trend of research, metaheuristic approaches have been studied and some interesting results have already been achieved and published. However, a successful utilization of these methodologies in practice, when embedded in Energy Management Systems, is still constrained by the reluctance of industrial partners in using techniques whose performance highly depends on a correct parameter tuning. Therefore, the application of metaheuristics to the Unit Commitment problem does still justify further research.

In this paper we propose a new search strategy, for Local Search based metaheuristics, that tries to overcome this issue. The approach has been tested in a set of instances, leading to very good results in terms of solution cost, when compared either to the classical Lagrangian Relaxation or to other metaheuristics. It also drastically reduced the computation times. Furthermore, the approach proved to be robust, always leading to good results independently of the metaheuristic parameters used.     

Influence of the inherent metal species on the graphitization of methane-based carbon nanofibers

Carbon nanofibers (CNFs) containing different proportions of Ni and Si were produced from methane decomposition in a fluidized bed reactor with a nickel–copper based catalyst. They were subjected to heat treatment in the temperature interval 1800–2800 °C for the purpose of studying the influence of the inherent metal species on their ability to graphitize. The participation of Ni and Si species on the graphitization of the methane-based CNFs through the formation of a nickel silicide phase as an intermediate state which further promotes the production of silicon carbide was inferred. Moreover, since silicon carbide was observed by X-ray diffraction after the heat treatment of the CNFs at temperatures ?2400 °C, the formation of graphite at the expense of the carbide decomposition seems to be a plausible mechanism to explain the catalytic graphitization of these CNFs. Because of this effect, carbon materials with crystalline parameters in the range of synthetic graphites which are currently employed in energy applications were prepared in this work. A progressive improvement of the degree of the structural order of the materials prepared with increasing Si/Ni weight ratio in the CNFs was observed.