Search results for "OPERATION"

Evaluation and elimination of the blank bias error using the H-point standard additions method (HPSAM) in the simultaneous spectrophotometric determi…

1997

Abstract The aim of this report is to demonstrate the usefulness of the HPSAM in all instances where the determination of two analytes requires the use of an absorbent reagent, particularly when it does not present a constant analytical signal because of its consumption. This problem can be treated as a ternary mixture by the HPSAM method and then, the fundamentals of the method for resolving these kind of mixtures can be applied. The method can calculate the concentration of one species from spectral data at two wavelengths where the two other species present the same absorbance relationship. These wavelength pairs are easily found, and can be selected to give the most precise results. The…

A chemometric study of the simultaneous determination of calcium and magnesium in natural waters

1999

A method for the simultaneous spectrophotometric determination of calcium and magnesium in mineral waters with an FIA system is tested. The method is based on the reaction between the analytes and arsenazo(III) at pH 8.5. The calculations of the amounts of both analytes in the samples are carried out with the H-point standard addition method (HPSAM) for ternary mixtures, and with a partial least squares (PLS) model after a proper variable selection. The results obtained for the determination of calcium were comparable using both methods. The employment of the HPSAM brings to our attention the influence of the calcium concentration in the sample to the development of the reaction between mag…

Development of the H-point standard additions method for analyte determinations in unknown matrix

1993

Abstract The development of the H-point standard additions method is proposed in order to obtain the unbiased analyte concentration when the matrix of the sample is completely unknown. A spectral region where the interferent behaviour can be considered linear at three wavelengths must be chosen. The method uses the analytical signal data at these three wavelengths, usually situated in the maxima region of the analyte. Two procedures are proposed in order to know and to locate this behaviour for the unknown interferent. Several binary and ternary mixtures of phenol, 4-chlorophenol and 4-chloro-3-methylphenol as representative examples have been assayed, with accurate (less than 3% relative e…

An Application of Analytic Network Process in the Planning Process: The Case of an Urban Transformation in Palermo (Italy)

2014

The primary objective of this study is to test the multicriteria analysis application in favor of a selection process among alternative transformations of an urban area in the city of Palermo. The choice is referred to as a strategyoriented one aiming to create “new urban centralities” able to redraw all urban structures that start to activate renewal processes within the existing city. The application of multicriteria analysis technique, such as the Analytic Network Process (ANP) - BOCR model, is due to the need to represent the complexity of the decision problem characterized by interrelations among several elements described by many indicators from different levels. The case study is als…

TiO2 photocatalysts prepared by thermohydrolysis of TiCl4 in aqueous solutions

2010

Abstract Nanostructured TiO 2 photocatalysts were synthesized by thermohydrolysis of TiCl 4 at 100 °C in various aqueous solutions. Anatase or rutile, binary mixtures of anatase and rutile or anatase and brookite, and ternary mixtures of anatase, brookite and rutile were obtained depending on the hydrolysis solution. The most efficient catalysts consisted of ternary mixtures of the three polymorphic TiO 2 phases.

Highly Active Photocatalytic TiO2 Powders Obtained by Thermohydrolysis of TiCl4 in Water

2009

Highly active photocatalytic TiO2 samples were synthesized by thermohydrolysis of TiCl4 in water at 100 °C. Rutile, binary mixtures of anatase and rutile or anatase and brookite or ternary mixtures of anatase, brookite, and rutile were obtained depending on the TiCl4/H2O ratio. Rietveld refinements were employed to evaluate the crystalline phases and composition of the mixtures. The effect of the aging time on the phase composition was also studied. The band gap values of the samples were obtained by the diffuse reflectance spectra. The position of the flat band potentials of anatase, brookite, and rutile was determined measuring the photovoltage as a function of the suspension pH. From the…

An environment based approach for the ant colony convergence

2020

Abstract Ant colony optimization (ACO) algorithms are a bio inspired solutions which have been very successful in combinatorial problem solving, also known as NP-hard problems, including transportation system optimization. As opposed to exact methods, which could give the best results of a tested problem, this meta-heuristics is based on the stochastic logic but not on theoretical mathematics demonstration (or only on certain well defined applications). According to this, the weak point of this meta-heuristics is his convergence, its termination condition. We can finds many different termination criteria in the scientific literature, yet most of them are costly in resources and unsuitable f…

Relationship between anthropometric parameters, physiological responses, routes and competition results in formula windsurfing

2012

Formula windsurfing is faster than the Olympic version, due to anumber of unique differences. This study was designed to identify the importance of anthropometric and cardiac factors on the final result of the European Formula Windsurf Championships (2007). We selected 45 competitors (30 amateurs and 15 professionals) of 30±9.77 years of age, a height of 182.6±0.06 cm, a weight of 81.67±7.35 kg and a BMIof 24.7±2.1 kg. They were divided into three groups (PG: 15; TG: 45and GPSG: 12). We followed the recommendations of Carter and Marfell-Jones for the anthropometric measurements. The route, speed, distance and heart rate were recorded using an FRWD W600 GPS (Global Positioning System) unit. …

Addressing Dendritic Cells for Anticancer Immunity

2014

Scenario optimization asset and liability modelling for individual investors

2006

We develop a scenario optimization model for asset and liability management of individual investors. The individual has a given level of initial wealth and a target goal to be reached within some time horizon. The individual must determine an asset allocation strategy so that the portfolio growth rate will be sufficient to reach the target. A scenario optimization model is formulated which maximizes the upside potential of the portfolio, with limits on the downside risk. Both upside and downside are measured vis- `a-vis the goal. The stochastic behavior of asset returns is captured through bootstrap simulation, and the simulation is embedded in the model to determine the optimal portfolio. …