Ensaios não-destrutivos de propagação de ondas em toras e madeira serrada de Pinus. taeda L.

In this paper it was evaluated the influence of the relative position of logs on the trees, the type of wood (juvenile and mature wood and pith) and the dimension of sawed wood elements on the velocity of propagation of stress waves into the material on condition. P. taeda L wood (43 years old trees) from Horto Florestal of Manduri (latitude 230 00’ south, longitude 400 19’ west and altitude de 700 m) São Paulo State, Brazil were used, considering its easy growth rings visualization and the better ju regions definition. Six trees were randomly chosen in the plantation. Trees were sawed into 4 logs (2,5 m long each. In each log it was delimited the central board (80mm tick) region and the lateral boards (25mm tick) regions, cons right hand. It were evaluated relation between velocity of stress waves on logs and the correspondent lumber (central and lateral boards), on green condition, on the three main region of the elements (mature wood results obtained revealed the concordance between velocities of stress waves in the material before and after the its mechanical processing. It was also revealed statistical differences between the velocity of stress waves at juvenile wood, mature wood and pith regions. Keywords: stress wave method, velocity 17 destrutivos de propagação da propagação de ondas de tensão em toras e madeira serrada de taeda L. Hernando Alfonso Lara Palma - Universidade Estadual Paulista Faculdade de Ciências Agronômicas – FCA/UNESP – Botucatu - SP, e-mail: awballarin@fca.unesp.br Luiz Antonio Vasques Hellmeister - Universidade Estadual Paulista - Faculdade de Arquitetura, FAAC/UNESP – Bauru - SP, e-mail: hellmeister@faac.unesp.br Este trabalho teve como objetivo analisar a influência do tipo de lenho, da posição da tora ao longo do fuste e das dimensões das peças desdobradas, na velocidade de as de tensão (Stress wave method), na condição de madeira verde. P. taeda L., originária de árvores de plantio do Horto Florestal de SP., com idade aproximada de 43 anos, pela facilidade de identificação dos anéis imento e demarcação das regiões de madeira adulta e madeira juvenil. Foram amostradas 6 árvores distintas, escolhidas ao acaso do talhão selecionado. De cada árvore foram retiradas 4 toras com comprimento de 2,5 m cada. Foram demarcadas nas toras a ha central (8 cm de espessura) e 4 tábuas laterais (espessura comercial de 2,5 cm), sendo duas à esquerda e duas à direita da prancha central. Foram avaliadas as relações existentes entre as velocidades de propagação das ondas de tensão na madeira íntegra (toras) e desdobrada (pranchas e tábuas), na condição de madeira verde, nas três regiões distintas do lenho: medula, madeira adulta e madeira juvenil. A análise comparativa dos resultados revelou a concordância entre as velocidades antes e após o desdobr madeira. Houve diferenciação estatisticamente significativa entre as velocidades de propagação das ondas de tensão nos lenhos adulto, juvenil e na medula. -destrutivos, método das ondas de tensão, Pinus taeda stress wave tests on green logs and lumber of Pinus taeda In this paper it was evaluated the influence of the relative position of logs on the trees, the type of wood (juvenile and mature wood and pith) and the dimension of sawed wood elements on the velocity of propagation of stress waves into the material on L wood (43 years old trees) from Horto Florestal of Manduri (latitude 19’ west and altitude de 700 m) São Paulo State, Brazil were used, considering its easy growth rings visualization and the better juvenile and mature wood regions definition. Six trees were randomly chosen in the plantation. Trees were sawed into 4 logs (2,5 m long each. In each log it was delimited the central board (80mm tick) region and the lateral boards (25mm tick) regions, considering 2 boards on the left and 2 at the right hand. It were evaluated relation between velocity of stress waves on logs and the correspondent lumber (central and lateral boards), on green condition, on the three main region of the elements (mature wood, juvenile wood and pith). Comparative analyses of results obtained revealed the concordance between velocities of stress waves in the material before and after the its mechanical processing. It was also revealed statistical differences ty of stress waves at juvenile wood, mature wood and pith regions

Localizador de faltas por ondas viajantes em linhas de transmissão

It is important to ensure smoothly operation of a transmission line, sending energy to the consumption centers with minimal interruptions and safer. With this necessity, the fault location techniques have grown, in order to mitigate the impact of the fault and its correction can be more quickly and accurately. This paper presents a comparison between two different techniques of fault location, the fault location by impedance method, which uses the line parameters, the impedance per distance, voltage and current signals, and the other is the traveling wave method, which uses only a very fast analysis of time, synchronization and length between the line ends, do not using voltage and current values, but the temporal perception of the fault. Using travelling waves fault detection makes the previous knowledge of line parameters obsolete, which helps a lot network technicians and engineers with a quick and easy analysis. The methods are simulated in ATP Draw software, so both algorithms can be evaluated for their effectively and accuracy

A Decomposition and Noise Removal Method Combining Diffusion Equation and Wave Atoms for Textured Images

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

On the energy transported by exact plane gravitational-wave solutions

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

A square-wave voltammetric method for analysing the colour marker quinizarine in petrol and diesel fuels

This work presents an electroanalytical method based on square-wave voltammetry (SWV) for the determination of quinizarine (QNZ) in a mixture of Britton-Robinson buffer 0.08 mol L-1 with 30% of acetonitrile. The QNZ was oxidized at glassy carbon electrode in and the well-defined peak at +0.45 V vs. Ag/AgCl can be used for its determination as colour marker in fuel samples. All parameters were optimized and analytical curves can be constructed for QNZ concentrations ranging from 2.0 x 10(-6) mol L-1 to 1.4 x 10(-5) mol L-1, using f = 60 Hz and E-sw = 25 mV. The method offers a limit detection of 4.12 x 10(-7) mol L-1 and a standard deviation of 4.5% when six measurements of 1.25 x 10(-5) mol L-1 are compared. The method was successfully applied for determining QNZ in gasoline and diesel oil and the obtained results showed good agreement with those reported previously. (c) 2006 Elsevier Ltd. All rights reserved.

A note on the controllability for the wave equation in nonsmooth plane domains

We study exact boundary controllability for a two-dimensional wave equation in a region which is an angular sector of a circle or an angular sector of an annular region. The control, of Neumann type, acts on the curved part of the boundary, while in the straight part we impose homogeneous Dirichlet boundary condition. The initial state has finite energy and the control is square integrable. (c) 2005 Elsevier B.V. All rights reserved.

Incommensurate spin-density-wave and metal-insulator transition in the one-dimensional periodic Anderson model

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

Comparison of fracture surface and plane section analysis for ceramic grain size characterisation

A method has been developed to obtain quantitative information about grain size and shape from fractured surfaces of ceramic materials. One elaborated a routine to split intergranular and transgranular grains facets of ceramic fracture surfaces by digital image processing. A commercial ceramic (ALCOA A-16, Al2O3-1.5% of CrO) was used to test the proposed method. Microstructural measurements of grain shape and size taken from fracture surfaces have been compared through descriptive statistics of distributions, with the corresponding measurements from polished and etched surfaces. The agreement between results, with the expected bias on grain size values from fractures, obtained for both types of surfaces allowed to infer that this new technique can be used to extract the relevant microstructural information from fractured surfaces, thus minimising the time consuming steps of sample preparation. (C) 2003 Elsevier Ltd. All rights reserved.

A high dynamic range method for the direct readout of a dynamic phase change in homodyne interferometers

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

Dynamic stationary response of reinforced plates by the boundary element method

A direct version of the boundary element method (BEM) is developed to model the stationary dynamic response of reinforced plate structures, such as reinforced panels in buildings, automobiles, and airplanes. The dynamic stationary fundamental solutions of thin plates and plane stress state are used to transform the governing partial differential equations into boundary integral equations (BIEs). Two sets of uncoupled BIEs are formulated, respectively, for the in-plane state ( membrane) and for the out-of-plane state ( bending). These uncoupled systems are joined to formamacro-element, in which membrane and bending effects are present. The association of these macro-elements is able to simulate thin-walled structures, including reinforced plate structures. In the present formulation, the BIE is discretized by continuous and/or discontinuous linear elements. Four displacement integral equations are written for every boundary node. Modal data, that is, natural frequencies and the corresponding mode shapes of reinforced plates, are obtained from information contained in the frequency response functions (FRFs). A specific example is presented to illustrate the versatility of the proposed methodology. Different configurations of the reinforcements are used to simulate simply supported and clamped boundary conditions for the plate structures. The procedure is validated by comparison with results determined by the finite element method (FEM).

On exact boundary controllability for linearly coupled wave equations

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

On asymptotic solutions of integrable wave equations

Asymptotic 'soliton train' solutions of integrable wave equations described by inverse scattering transform method with second-order scalar eigenvalue problem are considered. It is shown that if asymptotic solution can be presented as a modulated one-phase nonlinear periodic wavetrain, then the corresponding Baker-Akhiezer function transforms into quasiclassical eigenfunction of the linear spectral problem in weak dispersion limit for initially smooth pulses. In this quasiclassical limit the corresponding eigenvalues can be calculated with the use of the Bohr Sommerfeld quantization rule. The asymptotic distributions of solitons parameters obtained in this way specify the solution of the Whitham equations. (C) 2001 Elsevier B.V. B.V. All rights reserved.

On the extended applications of Homogenous Balance Method

In this paper, we study the travelling wave reductions for certain (2 + 1)- and (3 + 1)-dimensional physically important nonlinear evolutionary equations by using the recently proposed Homogenous Balance Method (HBM). Through this analysis we explore certain new solutions for the equations we have studied. (C) 2001 Published by Elsevier B.V.

Spatially-antisymmetric localization of matter wave in a bichromatic optical lattice

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