Rice husk can be an interesting source of raw material for obtaining silica, due to its composition, availability and cost. The extraction process of silica from rice husk can be divided in two parts. First some compo...
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Rice husk can be an interesting source of raw material for obtaining silica, due to its composition, availability and cost. The extraction process of silica from rice husk can be divided in two parts. First some components of rice husk are removed by acid leaching, using HCl, H2SO4, or a mixture of them, followed by calcination for burning out carbon compounds. The residue obtained after calcination is composed of about 95% amorphous silica. In this work, silica was produced from rice husk following the steps previously described, using leaching solutions of 10% HCl, 10% H 2SO4 and a mixture of 10% HCl and 10% H2SO 4. Calcination of leached materials was carried out at 600 or 700°C for 3 h. The silica powder obtained presented a mean particle size of 18 μm, around 98% amorphous SiO2 with a specific surface area of about 300 m2/g.
This paper presents SRST, a tool designed to support knowledge management and collaboration activities of the student-supervisor relationship that arise during the development of a graduate thesis. In universities, gr...
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ISBN:
(纸本)142440164X
This paper presents SRST, a tool designed to support knowledge management and collaboration activities of the student-supervisor relationship that arise during the development of a graduate thesis. In universities, graduate students account for the greatest part of the research work force, and are usually in close collaboration with their supervisors. Most student-supervisor interaction can be characterized as a form of knowledge management. SRST unites these concepts in a single and original tool and deals with four of the elements related to a thesis: "ideas", "tasks", "discussions", and "documents"
This work considers an interval extension of fuzzy implications based on the best interval representation of usual fuzzy implications. The related properties of fuzzy implications can be naturally extended and the int...
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ISBN:
(纸本)076952821X
This work considers an interval extension of fuzzy implications based on the best interval representation of usual fuzzy implications. The related properties of fuzzy implications can be naturally extended and the interval representation meets the optimality property and preserves the behaviors of the implications in the interval endpoints. Our discussion mainly focuses on the best interval representation of three important classes of fuzzy implications: S-implications, R-implications and QL-implications. We analyze sufficient and necessary conditions for these three classes of implications as inclusion-monotonic functions in both arguments satisfying the minimal properties of fuzzy implications.
OBF (Orthonormal Basis Function) Fuzzy models have shown to be a promising approach to the areas of nonlinear system identification and control since they exhibit several advantages over those dynamic model topologies...
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ISBN:
(纸本)9780769531960
OBF (Orthonormal Basis Function) Fuzzy models have shown to be a promising approach to the areas of nonlinear system identification and control since they exhibit several advantages over those dynamic model topologies usually adopted in the literature. Although encouraging application results have been obtained, no automatic procedure had yet been developed to optimize the design parameters of these models. This paper elaborates on the use of a genetic algorithm (GA) especially designed for this task, in which a fitness function based on the Akaike information criterion plays a key role by considering both model accuracy and parsimony aspects. The use of linear (actually affine) and nonlinear local models is also investigated. The proposed methodology is evaluated in the modeling of a real nonlinear magnetic levitation system.
In project teams, having an unique vocabulary and a common understanding about terms is essential to the success of the project. This issue especially disturbs a design project, which has a multidisciplinary team and ...
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ISBN:
(纸本)142440164X
In project teams, having an unique vocabulary and a common understanding about terms is essential to the success of the project. This issue especially disturbs a design project, which has a multidisciplinary team and must consist of people with specific and different knowledge, from diverse domains, to execute special activities. Negotiation arises from this context as a process for the construction of consensus. The goal of this work is to present a model of negotiation to obtain the consensus of meanings, based on models of business negotiation, and consequently, deal with conflicts and the multiplicity of understandings of a concept, making this negotiation a way for creating value for all agents involved
In this paper we address the issue of detecting defects in wood using features extracted from grayscale images. The feature set proposed here is based on the concept of texture and it is computed from the co-occurrenc...
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In this paper we address the issue of detecting defects in wood using features extracted from grayscale images. The feature set proposed here is based on the concept of texture and it is computed from the co-occurrence matrices. The features provide measures of properties such as smoothness, coarseness, and regularity. Comparative experiments using a color image based feature set extracted from percentile histograms are carried to demonstrate the efficiency of the proposed feature set. Two different learning paradigms, neural networks and support vector machines, and a feature selection algorithm based on multi-objective genetic algorithms were considered in our experiments. The experimental results show that after feature selection, the grayscale image based feature set achieves very competitive performance for the problem of wood defect detection relative to the color image based features
In this paper we address the issue of detecting defects in wood using features extracted from grayscale images. The feature set proposed here is based on the concept of texture and it is computed from the co-occurrenc...
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This paper presents the proposal and development of a reconfigurable crossbar switch (RCS) architecture for network processors. Its main purpose is to increase the performance, and flexibility for environments with mu...
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This paper presents the proposal and development of a reconfigurable crossbar switch (RCS) architecture for network processors. Its main purpose is to increase the performance, and flexibility for environments with multiprocessors and computer clusters. The results include VHDL simulation of RCS and the use of it in a broadcast function implementation, found in message passing support middleware
As data integration over the Web has become an increasing demand, there is a growing desire to use XML as a standard format for data exchange. For sharing their grammars efficiently, most of the XML documents in use a...
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Chemical reaction networks by which individual cells gather and process information about their chemical environments have been dubbed "signal transduction" networks. Despite this suggestive terminology, the...
Chemical reaction networks by which individual cells gather and process information about their chemical environments have been dubbed "signal transduction" networks. Despite this suggestive terminology, there have been few attempts to analyze chemical signaling systems with the quantitative tools of information theory. Gradient sensing in the social amoeba Dictyostelium discoideum is a well characterized signal transduction system in which a cell estimates the direction of a source of diffusing chemoattractant molecules based on the spatiotemporal sequence of ligand-receptor binding events at the cell membrane. Using Monte Carlo techniques (MCell) we construct a simulation in which a collection of individual ligand particles undergoing Brownian diffusion in a three-dimensional volume interact with receptors on the surface of a static amoeboid cell. Adapting a method for estimation of spike train entropies described by Victor (originally due to Kozachenko and Leonenko), we estimate lower bounds on the mutual information between the transmitted signal (direction of ligand source) and the received signal (spatiotemporal pattern of receptor binding/unbinding events). Hence we provide a quantitative framework for addressing the question: how much could the cell know, and when could it know it? We show that the time course of the mutual information between the cell's surface receptors and the (unknown) gradient direction is consistent with experimentally measured cellular response times. We find that the acquisition of directional information depends strongly on the time constant at which the intracellular response is filtered.
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