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Publications

2009

Practical Approach of Modeling and Parameters Estimation for Omnidirectional Mobile Robots

Authors
Conceicao, AS; Moreira, AP; Costa, PJ;

Publication
IEEE-ASME TRANSACTIONS ON MECHATRONICS

Abstract
This paper presents a nonlinear modeling approach for omnidirectional mobile robots. Three experimental methods of estimation of the parameters related to dynamic equations of the robot's model ire developed. The estimation methods are based on least-squares methods to obtain the viscous friction coefficients, the coulomb friction coefficients, and the moment of inertia of the robot. Simulation results and real results of navigation are provided to demonstrate the performance of the proposed modeling approach.

2009

The Diversity Present in 5140 Human Mitochondrial Genomes

Authors
Pereira, L; Freitas, F; Fernandes, V; Pereira, JB; Costa, MD; Costa, S; Maximo, V; Macaulay, V; Rocha, R; Samuels, DC;

Publication
AMERICAN JOURNAL OF HUMAN GENETICS

Abstract
We analyzed the current status (as of the end of August 2008) of human mitochondrial genomes deposited in GenBank, amounting to 5140 complete or coding-region sequences, in order to present an overall picture of the diversity present in the mitochondrial DNA of the global human population. To perform this task, we developed mtDNA-GeneSyn, a computer tool that identifies and exhaustedly classifies the diversity present in large genetic data sets. The diversity observed in the 5140 human mitochondrial genomes was compared with all possible transitions and transversions from the standard human mitochondrial reference genome. This comparison showed that tRNA and rRNA secondary structures have a large effect in limiting the diversity of the human mitochondrial sequences, whereas for the protein-coding genes there is a bias toward less variation at the second codon positions. The analysis of the observed amino acid variations showed a tolerance of variations that convert between the amino acids V, 1, A, M, and T. This defines a group of amino acids with similar chemical properties that can interconvert by a single transition.

2009

E-business Maturity and Information Technology in Portuguese SMEs

Authors
Goncalves, RM; Santos, SS; Morais, EP;

Publication
KNOWLEDGE MANAGEMENT AND INNOVATION IN ADVANCING ECONOMIES-ANALYSES & SOLUTIONS, VOLS 1-3

Abstract
The latest technological advances made over recent times led to a profound market change, characterized by increased competition. In order 10 be competitive, organizations have been forced to adapt themselves to this new reality, seeking innovative solutions permitting them to achieve lower costs, greater productivity and differentiation from competition. This work focuses the e-business maturity stages of Portuguese small and medium enterprises (SMEs). Our goal is to identify in which e-business maturity stage they are and explore the relationship between their e-business maturity and the technology they use.

2009

Robust and Real-time Teaching of Industrial Robots for Mass Customisation Manufacturing Using Stereoscopic Vision

Authors
Malheiros, P; Costa, P; Moreira, AP; Ferreira, M;

Publication
IECON: 2009 35TH ANNUAL CONFERENCE OF IEEE INDUSTRIAL ELECTRONICS, VOLS 1-6

Abstract
In this paper a method to control and teach industrial robots in real-time by human demonstration is presented. It aims to decrease down-times for reconfigurations and programming costs, particularly in a mass customisation manufacturing scenario. This system uses high-intensity visual markers that make it sufficiently robust for industrial environments not requiring special lighting. An automated camera calibration method was implemented which enables any non-skilled user a quick and easy configuration of the system. The teaching of the robot is achieved by recording the detected points and replaying them to the manipulator, therefore this is a "teaching-by-showing" method. The final program that the robot is uploaded with is a smooth trajectory calculated using all the recorded points, which are analised and grouped into different motion segments according to position and speed.

2009

On the divergence of evolutionary research paths in the past 50 years: a comprehensive bibliometric account

Authors
Silva, ST; Teixeira, AAC;

Publication
JOURNAL OF EVOLUTIONARY ECONOMICS

Abstract
In the last two decades, there has been a noticeable increase in published research on evolutionary economics. The general perception is that formalization lags behind appreciative work. Notwithstanding, this general reading has yet to be supported by real data analysis. This work presents a survey on evolutionary economics, aimed at exploring the main research paths and contributions using bibliometric methods. The documentation is based on an extensive review of the abstracts from articles published in all economic journals over the past 50 years gathered from the Econlit database. Evolutionary contributions have apparently not converged to an integrated approach. Two rather extreme main research strands emerged: 'History of Economic Thought and Methodology' and 'Games'. Whereas formal approaches have a reasonable and increasing share of published papers, purely empirical-related works are relatively scarce, representing a meagre and stagnant percentage of published works. This highlights the need to redirect the evolutionary research agenda.

2009

On the "concentration-driven" methylene blue dimerization

Authors
Tafulo, PAR; Queiros, RB; Gonzalez Aguilar, G;

Publication
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

Abstract
In this work a theoretical and experimental analysis of the spectrum of methylene blue is made in order to clarify the nature of the shoulder appearing at similar to 620 nm. This shoulder has been several times attributed to the existence of an hypothetical methylene blue chiller. The results here obtained do not agree with the existence of such a dimeric specie, and point out differences in the ionic strength of the solution as the phenomenon responsible for the variations observed in these spectra.

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