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Your search keyword '"Figueiredo R."' showing total 923 results
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923 results on '"Figueiredo R."'

203. Brazilian Journal of Chemical Engineering

Author

Figueiredo, R. T., Andrade, Heloysa Martins Carvalho, and Fierro, J. L. G.

Subjects
Catalyst preparation, Copper surface species, Water-gas shift reaction, Copper-zinc-aluminum catalysts, Catalyst characterization, Structure-activity relationship
Abstract

Submitted by Texeira Ana (atanateixeira@gmail.com) on 2012-10-08T18:57:40Z No. of bitstreams: 1 Figueiredo, R.T..pdf: 208808 bytes, checksum: 7134abd8b0c5a25ab4f55d232cde4ea7 (MD5) Made available in DSpace on 2012-10-08T18:57:40Z (GMT). No. of bitstreams: 1 Figueiredo, R.T..pdf: 208808 bytes, checksum: 7134abd8b0c5a25ab4f55d232cde4ea7 (MD5) Previous issue date: 1998-06 Cu-ZnO-Al2O3 catalysts for the low-temperature water-gas shift reaction were prepared using methods of direct and reverse coprecipitation. The catalysts obtained were characterized by DRX, TPR, XPS, N2O chemisorption, Hg-Porosimetry and BET surface area. It was observed that the precipitation sequence of the precursors led to significant differences in values of copper dispersion and consequently in the activity of the catalyst for the water-gas shift reaction. São Paulo

Published
1998
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216. Fractional angular transform: a number-theoretic approach.

Author

Figueiredo, R. B. D. and Lima, J. B.

Subjects
*DISCRETE Fourier transforms, *ERROR correction (Information theory), *CRYPTOGRAPHY, *ALGEBRAIC number theory, *SIGNAL processing
Abstract

In this Letter, the authors introduce a fractional angular number transform (FrANT). The new transform corresponds to a finite field version of the complex-valued discrete fractional angular transform and, therefore, its computation requires integer arithmetic only. Differently from other number-theoretic transforms, the possible lengths of an FrANT do not depend on the algebraic structure where it is defined. This provides more flexibility regarding the application of the transform in communications, cryptography and error correcting codes, for instance. [ABSTRACT FROM AUTHOR]

Published
2019
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230. Model-based orientation-independent 3-D machine vision techniques

Author

De Figueiredo, R. J. P and Kehtarnavaz, N

Subjects
Cybernetics
Abstract

Orientation-dependent techniques for the identification of a three-dimensional object by a machine vision system are represented in parts. In the first part, the data consist of intensity images of polyhedral objects obtained by a single camera, while in the second part, the data consist of range images of curved objects obtained by a laser scanner. In both cases, the attributed graphic representation of the object surface is used to drive the respective algorithm. In this representation, a graph node represents a surface patch and a link represents the adjacency between two patches. The attributes assigned to nodes are moment invariants of the corresponding face for polyhedral objects. For range images, the Gaussian curvature is used as a segmentation criterion for providing symbolic shape attributes. Identification is achieved by an efficient graph-matching algorithm used to match the graph obtained from the data to a subgraph of one of the model graphs stored in the commputer memory.

Published
1988
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239. Power spectral density estimation by spline smoothing in the frequency domain.

Author

De Figueiredo, R. J. P and Thompson, J. R

Subjects
Mathematics
Abstract

An approach, based on a global averaging procedure, is presented for estimating the power spectrum of a second order stationary zero-mean ergodic stochastic process from a finite length record. This estimate is derived by smoothing, with a cubic smoothing spline, the naive estimate of the spectrum obtained by applying Fast Fourier Transform techniques to the raw data. By means of digital computer simulated results, a comparison is made between the features of the present approach and those of more classical techniques of spectral estimation.

Published
1972

240. On the identification of nonlinear dynamical systems

Author

De Figueiredo, R. J. P and Netravali, A. N

Subjects
Electronics
Abstract

Independent noise driven nonlinear dynamic systems identification, performing linear discrete-time scalar measurements

Published
1971

243. Using open building data in the development of exposure datasets for catastrophe risk modelling.

Author

Figueiredo, R. and Martina, M.

Subjects
BUILDING protection, FLOOD damage prevention, EMERGENCY management, OPEN plan (Building), ENVIRONMENTAL risk assessment, ATMOSPHERIC models
Abstract

One of the necessary components to perform catastrophe risk modelling is information on the buildings at risk, such as their spatial location, geometry, height, occupancy type and other characteristics. This is commonly referred to as the exposure model or dataset. When modelling large areas, developing exposure datasets with the relevant information about every individual building is not practicable. Thus, census data at coarse spatial resolutions are often used as the starting point for the creation of such datasets, after which disaggregation to finer resolutions is carried out using different methods, based on proxies such as the population distribution. While these methods can produce acceptable results, they cannot be considered ideal. Nowadays, the availability of open data is increasing and it is possible to obtain information about buildings for some regions. Although this type of information is usually limited and, therefore, insufficient to generate an exposure dataset, it can still be very useful in its elaboration. In this paper, we focus on how open building data can be used to develop a gridded exposure model by disaggregating existing census data at coarser resolutions. Furthermore, we analyse how the selection of the level of spatial resolution can impact the accuracy and precision of the model, and compare the results in terms of affected residential building areas, due to a flood event, between different models. [ABSTRACT FROM AUTHOR]

Published
2015
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245. Mixed inflammatory/regulatory cytokine profile marked by simultaneous raise of interferon-γ and interleukin-10 and low frequency of tumour necrosis factor-α+ monocytes are hallmarks of active human visceral Leishmaniasis due toLeishmania chagasiinfection

Author

Peruhype-Magalhães, V, primary, Martins-Filho, O A, additional, Prata, A, additional, Silva, L De A, additional, Rabello, A, additional, Teixeira-Carvalho, A, additional, Figueiredo, R M, additional, Guimarães-Carvalho, S F, additional, Ferrari, T C A, additional, Van Weyenbergh, J, additional, and Correa-Oliveira, R, additional

Published
2006
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