Dificuldades na construção de gráficos de funções

This study describes about graduation s students difficulties of to draw functions graph. Specifically, we intend to observe their abilities evolution, as well as their difficulties during Calculus I subject in engineering course. For that, we show them publications about the elaboration of graphs and its difficulties in obstacle terms and some researches witch contain this subject and that it was done during postgraduate studies in mathematical education. It shows by research methodology aspects related to French didatic s mathematic and some theories of cognitive psychology considering the high value between theoretical-methodological relation that was evidenced in both theoretical conceptions about ways to understand and teach mathematic. This methodology is based on didactic engineering purpose, that consist in preliminaries analysis, conception and didactic sequence analysis prior, trials by application followed analysis up and conclusion. We had also used pedagogicals actions and analysis of results achieved, to classify types of errors made by the 2005 s students during second semester, from conceptions related to the episthemologic and didactics obstacles

Powder Diffraction of Components Subject to Corrosion in Fuse Cutouts with CeramicInsulation

Aiming identification of the components most affected by corrosion under saline environment conditions, we have carried out X-ray diffraction measurements in ceramic and bond materials, all in the powder form. The ceramic is analyzed before and after thermal annealing at 1000 degrees C, showing the same DRX peaks, although better defined after annealing. Identification suggests the presence of Al(6)Si(2)O(13) (Mullite) and SiO(2) (Quartz). Analysis of the junction (bond) material shows similar peaks, but a metallic preponderance is observed. Thermal annealing of the junction is done at much lower temperature, because it melts in the range 135 degrees C-170 degrees C, when a whitish smoke begins to show up along with strong sulfur odor.

A neural system to robust Nonlinear optimization subject to disjoint and constrained sets

The ability of neural networks to realize some complex nonlinear function makes them attractive for system identification. This paper describes a novel method using artificial neural networks to solve robust parameter estimation problems for nonlinear models with unknown-but-bounded errors and uncertainties. More specifically, a modified Hopfield network is developed and its internal parameters are computed using the valid-subspace technique. These parameters guarantee the network convergence to the equilibrium points. A solution for the robust estimation problem with unknown-but-bounded error corresponds to an equilibrium point of the network. Simulation results are presented as an illustration of the proposed approach.

Attitude stability of artificial satellites subject to gravity gradient torque

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Nutritional composition, phenolic compounds, nitrate content in eatable vegetables obtained by conventional and certified organic grown culture subject to thermal treatment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Richards growth model and viability indicators for populations subject to interventions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Filmes na formação de futuros professores: educar o olhar

Neste artigo, trago parte de minha experiência como professora de futuros professores de Matemática quando ministrei a disciplina Didática, no ano de 2010. Socializo aqui algumas das práticas instituídas nesse contexto e que resgatam a potencialidade dos filmes e da escrita no processo formativo dos alunos. Problematizo a importância de assistir juntos a um filme, já que essa experiência estética possibilita promover o conhecimento, o sentimento e a ação. Trago a voz dos meus alunos, documentada nos registros semanais elaborados por eles, para dizer das marcas que os filmes deixaram no percurso formativo de cada um como futuros professores de Matemática. Ao resgatar essa prática, enfatizo a importância de educar o olhar na busca pela constituição de um professor comprometido com uma educação e uma sociedade mais justa e democrática.

Adaptive control charts: A Markovian approach for processes subject to independent disturbances

Recent studies have shown that adaptive X control charts are quicker than traditional X charts in detecting small to moderate shifts in a process. In this article, we propose a joint statistical design of adaptive X and R charts having all design parameters varying adaptively. The process is subjected to two independent assignable causes. One cause changes the process mean and the other changes the process variance. However, the occurrence of one kind of assignable cause does not preclude the occurrence of the other. It is assumed that the quality characteristic is normally distributed and the time that the process remains in control has exponential distribution. Performance measures of these adaptive control charts are obtained through a Markov chain approach. (c) 2005 Elsevier B.V. All rights reserved.

Stability analysis of the attitude of artificial satellites subject to gravity gradient torque

Using a canonical formulation, the stability of the rotational motion of artificial satellites is analyzed considering perturbations due to the gravity gradient torque. Here Andoyer's variables are used to describe the rotational motion. One of the approaches that allow the analysis of the stability of Hamiltonian systems needs the reduction of the Hamiltonian to a normal form. Firstly equilibrium points are found. Using generalized coordinates, the Hamiltonian is expanded in the neighborhood of the linearly stable equilibrium points. In a next step a canonical linear transformation is used to diagonalize the matrix associated to the linear part of the system. The quadratic part of the Hamiltonian is normalized. Based in a Lie-Hori algorithm a semi-analytic process for normalization is applied and the Hamiltonian is normalized up to the fourth order. Once the Hamiltonian is normalized up to order four, the analysis of stability of the equilibrium point is performed using the theorem of Kovalev and Savichenko. This semi-analytical approach was applied considering some data sets of hypothetical satellites. For the considered satellites it was observed few cases of stable motion. This work contributes for space missions where the maintenance of spacecraft attitude stability is required.

Intestinal colonization of a human subject by vancomycin-resistant Enterococcus faecium

Objective: To study the ability of two strains of vancomycin-resistant Enterococcus faecium to colonize the human intestine. Methods: A single human subject ingested separately two strains of vancomycin-resistant E. faecium isolated from a pig and a chicken. The feces were cultured on selective medium. Prior to ingestion no vancomycin-resistant cocci were present in the feces. Ingestion of 10 4-10 5 CFU resulted in either no colonization or isolation only after enrichment. Ingestion of 10 7 CFU of one strain resulted in colonization for a period of nearly 3 weeks, with fecal counts at times in excess of 10 6 CFU/g. Ingestion of similar numbers of the other strain and reingestion of the first strain resulted in excretion in the feces for much shorter periods. When the fecal count of the ingested strains was greater than 10 4-10 5 CFU/g, the strains were isolated from swabs taken from perianal skin. Conclusions: Vancomycin-resistant E. faecium strains from pigs and poultry a re able to colonize the human gut and the perianal skin.

Stochastic Stability for Markovian Jump Linear Systems Subject to a Crucial Failure Event

This paper is concerned with the stability of discrete-time linear systems subject to random jumps in the parameters, described by an underlying finite-state Markov chain. In the model studied, a stopping time τ Δ is associated with the occurrence of a crucial failure after which the system is brought to a halt for maintenance. The usual stochastic stability concepts and associated results are not indicated, since they are tailored to pure infinite horizon problems. Using the concept named stochastic τ-stability, equivalent conditions to ensure the stochastic stability of the system until the occurrence of τ Δ is obtained. In addition, an intermediary and mixed case for which τ represents the minimum between the occurrence of a fix number N of failures and the occurrence of a crucial failure τ Δ is also considered. Necessary and sufficient conditions to ensure the stochastic τ-stability are provided in this setting that are auxiliary to the main result.

Co-operativism and popular participation: new considerations regarding an old subject

Includes bibliography