Investigation of C-O stretching band of CD3OH: Assignments of far-infrared laser lines

We have investigated the high-resolution Fourier transform spectrum of the C-O stretching fundamental band of CD3OH in order to assign far-infrared (FIR) laser transitions. The absorption spectrum was analyzed by means of the ''Ritz'' program, which calculates the energy level values directly from the Rydberg-Ritz combination principle. We have also used the ''LaseRitz'' program to facilitate the assignment of the FIR laser lines. As a consequence we could determine 12 new assignments, confirming 4 previously proposed ones and predicting new FIR laser emissions. (C) 1997 Academic Press.

Design of a fuzzy controller with simplified architecture

This work presents the design of a fuzzy controller with simplified architecture. This architecture tries to minimize the time processing used in? the several stages of hazy modeling of systems and processes. The basic procedures of fuzzification and defuzzification are simplified to the maximum while the inference procedures are computed in private way. Therefore, the simplified architecture allows a fast and easy configuration of the fuzzy controller.All rules that define the control actions are determined by inference procedures and the defuzzification is made automatically using a simplified algorithm. The fuzzy controller operation is standardized and the control actions are previously calculated For general-purpose application? ann results, the industrial systems of fluid pow cona ol will be considered.

Application of a new reverse Monte Carlo algorithm to polyatomic molecular systems. I. Liquid water

Using a new reverse Monte Carlo algorithm, we present simulations that reproduce very well several structural and thermodynamic properties of liquid water. Both Monte Carlo, molecular dynamics simulations and experimental radial distribution functions used as input are accurately reproduced using a small number of molecules and no external constraints. Ad hoc energy and hydrogen bond analysis show the physical consistency and limitations of the generated RMC configurations. (C) 2001 American Institute of Physics.

Screening Brazilian C gasoline quality: Application of the SIMCA chemometric method to gas chromatographic data

A total of 2400 samples of commercial Brazilian C gasoline were collected over a 6-month period from different gas stations in the São Paulo state, Brazil, and analysed with respect to 12 physicochemical parameters according to regulation 309 of the Brazilian Government Petroleum, Natural Gas and Biofuels Agency (ANP). The percentages (v/v) of hydrocarbons (olefins, aromatics and saturated) were also determined. Hierarchical cluster analysis (HCA) was employed to select 150 representative samples that exhibited least similarity on the basis of their physicochemical parameters and hydrocarbon compositions. The chromatographic profiles of the selected samples were measured by gas chromatography with flame ionisation detection and analysed using soft independent modelling of class analogy (SIMCA) method in order to create a classification scheme to identify conform gasolines according to ANP 309 regulation. Following the optimisation of the SIMCA algorithm, it was possible to classify correctly 96% of the commercial gasoline samples present in the training set of 100. In order to check the quality of the model, an external group of 50 gasoline samples (the prediction set) were analysed and the developed SIMCA model classified 94% of these correctly. The developed chemometric method is recommended for screening commercial gasoline quality and detection of potential adulteration. (c) 2007 Elsevier B.V. All rights reserved.

Mnltiloop Controller and Reference Generator for a Dynamic Voltage Restorer Implementation

This paper deals with the design and analysis of a Dynamic Voltage Restorer output voltage control. Such control is based on a multiloop strategy, with an inner current PID regulator and an outer P+Resonant voltage controller. The inner regulator is applied on the output inductor current. It will be also demonstrated how the load current behavior may influence in the DVR output voltage, which. justifies the need for the resonant controller. Additionally, it will be discussed the application of a modified algorithm for the identification of the DVR voltage references, which is based on a previously presented positive sequence detector. Since the studied three-phase DVR is assumed to be based on three identical H-bridge converters, all the analysis and design procedures were realized by means of single-phase equivalent circuits. The discussions and conclusions are supported by theoretical calculations, nonlinear simulations and some experimental results.

Three- phase four-wire circuits interpretation by means of different power theories

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

An evolutionary algorithm for the one-dimensional cutting stock problem

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Location and contract pricing of distributed generation using a genetic algorithm

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Combined (13)C NMR and DFT/GIAO studies of the polyketides Aurasperone A and Fonsecinone A

Structural characterization by NMR spectroscopy and DFT calculations was performed for two dimeric naptho-gamma-pyrones, the polyketides Aurasperone A and Fonsecinone A. Experimental data ((13)C NMR chemical shifts and interatomic geometries) were found to be in reasonable agreement with theoretical ones, obtained at B3LYP level for three different basis sets (6-31G/6-31G(d)/6-31G(d,p)). Additionally, the dipolar moments calculation allowed explaining the different solubility for these molecules. The (13)C NMR theoretical chemical shifts were calculated with the GIAO method and the solvent effects were taken into account by means of the PCM approximation. In this work, the DFT/GIAO methodology shows to be a reliable tool in the assignment of experimental NMR chemical shifts of similar molecules. (C) 2008 Wiley Periodicals, Inc. Int J Quantum Chem 108: 2408-2416, 2008.

Optical and dielectric relaxor behaviour of Ba(Zr0.25Ti0.75)O-3 ceramic explained by means of distorted clusters

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Analysis of biodiesel and frying vegetable oils by means of FTIR photoacoustic spectroscopy

Fourier Transform Infrared Photoacoustic Spectroscopy was used to determine the mid-infrared vibrational modes of biodiesel and vegetable oils. Our results indicate that this method can contribute significantly to the biodiesel wash process during the sample preparation. Besides, by analyzing the spectra of vegetable oils used to fry snacks we could to monitor the degradation in function of the fried time.

The dielectric suppress and the control of semiconductor non-Ohmic feature of CaCu3Ti4O12 by means of tin doping

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preconcentration of heavy metals ions from aqueous solutions by means of cellulose phosphate: An application in water analysis

Cellulose phosphate (CELLPHOS) was studied as a collector for analytical preconcentration of traces of Cd(II), Cr(III), Cu(II) and Ni(II) from aqueous sample solution. It has been proved that using chromatographic columns packed with CELLPHOS for preconcentration and 1.0 mol 1 -1 HCl for elution the adsorbed analytes are quantitatively enriched. An enrichment factor of 20 (100 ml sample, 5 ml concentrate) was achieved by this separation procedure, which was applied to a series of water analyses (river, sea, bog water).

Combining genetic algorithm and simulated annealing: A molecular geometry optimization study

We introduce a new hybrid approach to determine the ground state geometry of molecular systems. Firstly, we compared the ability of genetic algorithm (GA) and simulated annealing (SA) to find the lowest energy geometry of silicon clusters with six and 10 atoms. This comparison showed that GA exhibits fast initial convergence, but its performance deteriorates as it approaches the desired global extreme. Interestingly, SA showed a complementary convergence pattern, in addition to high accuracy. Our new procedure combines selected features from GA and SA to achieve weak dependence on initial parameters, parallel search strategy, fast convergence and high accuracy. This hybrid algorithm outperforms GA and SA by one order of magnitude for small silicon clusters (Si6 and Si10). Next, we applied the hybrid method to study the geometry of a 20-atom silicon cluster. It was able to find an original geometry, apparently lower in energy than those previously described in literature. In principle, our procedure can be applied successfully to any molecular system. © 1998 Elsevier Science B.V.