Semi-automatic spline fitting of planar curvilinear profiles in digital images using the Hough transform

We develop a novel method for the recognition of curvilinear profiles in digital images. The proposed method, semi-automatic for both closed and open planar profiles, essentially consists of a preprocessing step exploiting an edge detection algorithm, and a main step involving the Hough transform technique. In the preprocessing step, a Canny edge detection algorithm is applied in order to obtain a reduced point set describing the profile curve to be reconstructed. Also, to identify in the profile possible sharp points like cusps, we additionally use an algorithm to find the approximated tangent vector of every edge point. In the subsequent main step, we then use a piecewisely defined Hough transform to locally recognize from the point set a low-degree piecewise polynomial curve. The final outcome of the algorithm is thus a spline curve approximating the underlined profile image. The output curve consists of polynomial pieces connected G^1 continuously, except in correspondence of the identified cusps, where the order of continu- ity is only C^0 , as expected. To illustrate effectiveness and efficiency of the new profile detection technique we present several numerical results dealing with detection of open and closed profiles in images of dif- ferent type, i.e., medical and photographic image

Nonlocal planar Schrödinger-Poisson systems in the fractional Sobolev limiting case

We study the nonlinear Schrodinger equation for the s-fractional p-Laplacian strongly coupled with the Poisson equation in dimension two and with p =2s, which is the limiting case for the embedding of the fractional Sobolev space Ws,p(R2). We prove existence of solutions by means of a variational approximating procedure for an auxiliary Choquard equation in which the uniformly approximated sign-changing logarithmic kernel competes with the exponential nonlinearity. Qualitative properties of solutions such as symmetry and decay are also established by exploiting a suitable moving planes technique

Mercado de AgroTIC e transferência de tecnologia.

Este capítulo busca analisar o mercado de TIC aplicadas ao setor agropecuário no Brasil e os modelos e formas de disponibilização de tecnologias geradas pela Embrapa Informática Agropecuária com foco em diferentes públicos de interesse. Unidade temática de pesquisa da Empresa Brasileira de Pesquisa Agropecuária (Embrapa), a Embrapa Informática Agropecuária vem desde 1985 desenvolvendo soluções de tecnologia de informação para o setor agropecuário

Planejamento e reengenharia de sistemas de informação com foco no diagrama de implantação.

Este artigo apresenta o processo de documentação da segunda versão do sistema Agritempo, relatando mais especificamente o uso de um diagrama específico da UML com impacto positivo no processo de desenvolvimento e manutenção do sistema

A quasilinear transmission problem with application to Maxwell equations with a divergence-free D-field

Maxwell equations in the absence of free charges require initial data with a divergence-free displacement field D. In materials in which the dependence D=D(E) is nonlinear the quasilinear problem 07 c5D(E)=0 is hence to be solved. In many applications, e.g. in the modelling of wave packets, an approximative asymptotic ansatz of the electric field E is used, which satisfies this divergence condition at t=0 only up to a small residual. We search then for a small correction of the ansatz to enforce 07 c5D(E)=0 at t=0 and choose this correction in the form of a gradient field. In the usual case of a power type nonlinearity in D(E) this leads to the sum of the Laplace and p-Laplace operators. We also allow for the medium to consist of two different materials so that a transmission problem across an interface is produced. We prove the existence of the correction term for a general class of nonlinearities and provide regularity estimates for its derivatives, independent of the L2-norm of the original ansatz. In this way, when applied to the wave packet setting, the correction term is indeed asymptotically smaller than the original ansatz. We also provide numerical experiments to support our analysis

Estudo comparativo de produtos comerciais de geração de interface gráfica multiplataforma.

O objetivo deste documento é registrar um levantamento de produtos de software comerciais multiplataforma destinados á geração de interface gráficas.A demanda que justificou tal trabalho teve origem no projeto ambiente Integrado para o Desenvolvimento e Análise - AIDA (Chaim et al., 1996), em andamento no Centro Nacional de Pesquisa Tecnológica em Informática para a Agricultura (CNPTIA).bitstream/item/76613/1/CNPTIA-COM.TEC.-1-97.pd