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Research paper thumbnail of Automatic PC disassembly for component recovery

International Journal of Advanced Manufacturing Technology, 2004

In this article, a personal computer disassembly cell is presented. With this cell, a certain deg... more In this article, a personal computer disassembly cell is presented. With this cell, a certain degree of automatism is afforded for the non-destructive disassembly process and for the recycling of these kinds of mass-produced electronic products. Each component of the product can be separated. The disassembly cell is composed of several sub-systems, each of which is dedicated to the planning and execution of one type of task. A computer vision system is employed for the recognition and localisation of the product and of each of its components. The disassembly system proposed here also has a modelling system for the products and each of its components, the information necessary for the planning of tasks, generating the disassembly sequence and planning of the disassembly movements. These systems co-operate with each other to achieve a semi-automatic disassembly of the product.

Research paper thumbnail of Comparative study of vectorial morphological operations in different color spaces

In this paper, we present the results of the extension of the mathematical morphology to color im... more In this paper, we present the results of the extension of the mathematical morphology to color images by treating multichannel data as vectors. The approach presented here uses the HSI and related color spaces (intuitives). A modification of the lexicographical order for vectorial processing is developed. The importance of this new method lies on automatic selection of elements of the HSI and realted color spaces to form an ordering structure. The achievement of the algorithm is realized through the introduction of a weight factor to reduce the high preference of the first component of the classic lexicographical order. Experimental results demonstrate the improvement of this new method.

Research paper thumbnail of Disassembly Planning Based on Precedence Relations among Assemblies

International Journal of Advanced Manufacturing Technology, 2003

An algorithm is presented that is based on a representation method for products, which lets us sh... more An algorithm is presented that is based on a representation method for products, which lets us show, intuitively, the hier-archical relationships among components and/or assemblies of the product. This paper presents an algorithm for establishing a partial non-destructive ...

Research paper thumbnail of On Maximal Curves

Journal of Number Theory, 1997

We study arithmetical and geometrical properties of maximal curves, that is, curves defined over ... more We study arithmetical and geometrical properties of maximal curves, that is, curves defined over the finite field F q 2 whose number of F q 2 -rational points reaches the Hasse-Weil upper bound. Under a hypothesis on non-gaps at a rational point, we prove that maximal curves are F q 2 -isomorphic to y q + y = x m , for some m ∈ Z + . As a consequence we show that a maximal curve of genus g = (q − 1) 2 /4 is F q 2 -isomorphic to the curve y q + y = x (q+1)/2 .

Research paper thumbnail of On maximal curves in characteristic two

Manuscripta Mathematica, 1999

The genus g of an q-maximal curve satisfies g=g 1≔q(q−1)/2 or . Previously, q-maximal curves with... more The genus g of an q-maximal curve satisfies g=g 1≔q(q−1)/2 or . Previously, q-maximal curves with g=g 1 or g=g 2, q odd, have been characterized up to q-isomorphism. Here it is shown that an q-maximal curve with genus g 2, q even, is q-isomorphic to the non-singular model of the plane curve ∑i =1}t y q /2i =x q +1, q=2t , provided that q/2 is a Weierstrass non-gap at some point of the curve.

Research paper thumbnail of The genus of curves over finite fields with many rational points

Manuscripta Mathematica, 1996

We prove the following result which was conjectured by Stichtenoth and Xing: letg be the genus of... more We prove the following result which was conjectured by Stichtenoth and Xing: letg be the genus of a projective, irreducible non-singular algebraic curve over the finite field mathbbFq2\mathbb{F}_{q^2 } mathbbFq2 and whose number of mathbbFq2\mathbb{F}_{q^2 } mathbbFq2 -rational points attains the Hasse-Weil bound; then either 4g≤(q−1)2 or 2g=(q−1)q.

Research paper thumbnail of On Weierstrass points and optimal curves

We use Weierstrass Point Theory and Frobenius orders to prove the uniqueness (up to isomorphism) ... more We use Weierstrass Point Theory and Frobenius orders to prove the uniqueness (up to isomorphism) of some optimal curves.

Research paper thumbnail of On Maximal Curves

Journal of Number Theory, 1997

We study arithmetical and geometrical properties of maximal curves, that is, curves defined over ... more We study arithmetical and geometrical properties of maximal curves, that is, curves defined over the finite field F q 2 whose number of F q 2 -rational points reaches the Hasse-Weil upper bound. Under a hypothesis on non-gaps at a rational point, we prove that maximal curves are F q 2 -isomorphic to y q + y = x m , for some m ∈ Z + . As a consequence we show that a maximal curve of genus g = (q − 1) 2 /4 is F q 2 -isomorphic to the curve y q + y = x (q+1)/2 .

Research paper thumbnail of On maximal curves in characteristic two

Manuscripta Mathematica, 1999

The genus g of an q-maximal curve satisfies g=g 1≔q(q−1)/2 or . Previously, q-maximal curves with... more The genus g of an q-maximal curve satisfies g=g 1≔q(q−1)/2 or . Previously, q-maximal curves with g=g 1 or g=g 2, q odd, have been characterized up to q-isomorphism. Here it is shown that an q-maximal curve with genus g 2, q even, is q-isomorphic to the non-singular model of the plane curve ∑i =1}t y q /2i =x q +1, q=2t , provided that q/2 is a Weierstrass non-gap at some point of the curve.

Research paper thumbnail of The genus of curves over finite fields with many rational points

Manuscripta Mathematica, 1996

We prove the following result which was conjectured by Stichtenoth and Xing: letg be the genus of... more We prove the following result which was conjectured by Stichtenoth and Xing: letg be the genus of a projective, irreducible non-singular algebraic curve over the finite field mathbbFq2\mathbb{F}_{q^2 } mathbbFq2 and whose number of mathbbFq2\mathbb{F}_{q^2 } mathbbFq2 -rational points attains the Hasse-Weil bound; then either 4g≤(q−1)2 or 2g=(q−1)q.

Research paper thumbnail of On Weierstrass points and optimal curves

We use Weierstrass Point Theory and Frobenius orders to prove the uniqueness (up to isomorphism) ... more We use Weierstrass Point Theory and Frobenius orders to prove the uniqueness (up to isomorphism) of some optimal curves.

Research paper thumbnail of Automatic PC disassembly for component recovery

International Journal of Advanced Manufacturing Technology, 2004

In this article, a personal computer disassembly cell is presented. With this cell, a certain deg... more In this article, a personal computer disassembly cell is presented. With this cell, a certain degree of automatism is afforded for the non-destructive disassembly process and for the recycling of these kinds of mass-produced electronic products. Each component of the product can be separated. The disassembly cell is composed of several sub-systems, each of which is dedicated to the planning and execution of one type of task. A computer vision system is employed for the recognition and localisation of the product and of each of its components. The disassembly system proposed here also has a modelling system for the products and each of its components, the information necessary for the planning of tasks, generating the disassembly sequence and planning of the disassembly movements. These systems co-operate with each other to achieve a semi-automatic disassembly of the product.

Research paper thumbnail of Comparative study of vectorial morphological operations in different color spaces

In this paper, we present the results of the extension of the mathematical morphology to color im... more In this paper, we present the results of the extension of the mathematical morphology to color images by treating multichannel data as vectors. The approach presented here uses the HSI and related color spaces (intuitives). A modification of the lexicographical order for vectorial processing is developed. The importance of this new method lies on automatic selection of elements of the HSI and realted color spaces to form an ordering structure. The achievement of the algorithm is realized through the introduction of a weight factor to reduce the high preference of the first component of the classic lexicographical order. Experimental results demonstrate the improvement of this new method.

Research paper thumbnail of Disassembly Planning Based on Precedence Relations among Assemblies

International Journal of Advanced Manufacturing Technology, 2003

An algorithm is presented that is based on a representation method for products, which lets us sh... more An algorithm is presented that is based on a representation method for products, which lets us show, intuitively, the hier-archical relationships among components and/or assemblies of the product. This paper presents an algorithm for establishing a partial non-destructive ...

Research paper thumbnail of On Maximal Curves

Journal of Number Theory, 1997

We study arithmetical and geometrical properties of maximal curves, that is, curves defined over ... more We study arithmetical and geometrical properties of maximal curves, that is, curves defined over the finite field F q 2 whose number of F q 2 -rational points reaches the Hasse-Weil upper bound. Under a hypothesis on non-gaps at a rational point, we prove that maximal curves are F q 2 -isomorphic to y q + y = x m , for some m ∈ Z + . As a consequence we show that a maximal curve of genus g = (q − 1) 2 /4 is F q 2 -isomorphic to the curve y q + y = x (q+1)/2 .

Research paper thumbnail of On maximal curves in characteristic two

Manuscripta Mathematica, 1999

The genus g of an q-maximal curve satisfies g=g 1≔q(q−1)/2 or . Previously, q-maximal curves with... more The genus g of an q-maximal curve satisfies g=g 1≔q(q−1)/2 or . Previously, q-maximal curves with g=g 1 or g=g 2, q odd, have been characterized up to q-isomorphism. Here it is shown that an q-maximal curve with genus g 2, q even, is q-isomorphic to the non-singular model of the plane curve ∑i =1}t y q /2i =x q +1, q=2t , provided that q/2 is a Weierstrass non-gap at some point of the curve.

Research paper thumbnail of The genus of curves over finite fields with many rational points

Manuscripta Mathematica, 1996

We prove the following result which was conjectured by Stichtenoth and Xing: letg be the genus of... more We prove the following result which was conjectured by Stichtenoth and Xing: letg be the genus of a projective, irreducible non-singular algebraic curve over the finite field mathbbFq2\mathbb{F}_{q^2 } mathbbFq2 and whose number of mathbbFq2\mathbb{F}_{q^2 } mathbbFq2 -rational points attains the Hasse-Weil bound; then either 4g≤(q−1)2 or 2g=(q−1)q.

Research paper thumbnail of On Weierstrass points and optimal curves

We use Weierstrass Point Theory and Frobenius orders to prove the uniqueness (up to isomorphism) ... more We use Weierstrass Point Theory and Frobenius orders to prove the uniqueness (up to isomorphism) of some optimal curves.

Research paper thumbnail of On Maximal Curves

Journal of Number Theory, 1997

We study arithmetical and geometrical properties of maximal curves, that is, curves defined over ... more We study arithmetical and geometrical properties of maximal curves, that is, curves defined over the finite field F q 2 whose number of F q 2 -rational points reaches the Hasse-Weil upper bound. Under a hypothesis on non-gaps at a rational point, we prove that maximal curves are F q 2 -isomorphic to y q + y = x m , for some m ∈ Z + . As a consequence we show that a maximal curve of genus g = (q − 1) 2 /4 is F q 2 -isomorphic to the curve y q + y = x (q+1)/2 .

Research paper thumbnail of On maximal curves in characteristic two

Manuscripta Mathematica, 1999

The genus g of an q-maximal curve satisfies g=g 1≔q(q−1)/2 or . Previously, q-maximal curves with... more The genus g of an q-maximal curve satisfies g=g 1≔q(q−1)/2 or . Previously, q-maximal curves with g=g 1 or g=g 2, q odd, have been characterized up to q-isomorphism. Here it is shown that an q-maximal curve with genus g 2, q even, is q-isomorphic to the non-singular model of the plane curve ∑i =1}t y q /2i =x q +1, q=2t , provided that q/2 is a Weierstrass non-gap at some point of the curve.

Research paper thumbnail of The genus of curves over finite fields with many rational points

Manuscripta Mathematica, 1996

We prove the following result which was conjectured by Stichtenoth and Xing: letg be the genus of... more We prove the following result which was conjectured by Stichtenoth and Xing: letg be the genus of a projective, irreducible non-singular algebraic curve over the finite field mathbbFq2\mathbb{F}_{q^2 } mathbbFq2 and whose number of mathbbFq2\mathbb{F}_{q^2 } mathbbFq2 -rational points attains the Hasse-Weil bound; then either 4g≤(q−1)2 or 2g=(q−1)q.

Research paper thumbnail of On Weierstrass points and optimal curves

We use Weierstrass Point Theory and Frobenius orders to prove the uniqueness (up to isomorphism) ... more We use Weierstrass Point Theory and Frobenius orders to prove the uniqueness (up to isomorphism) of some optimal curves.