Some comments on particle image displacement velocimetry

Laser speckle velocimetry (LSV) or particle image displacement velocimetry, is introduced. This technique provides the simultaneous visualization of the two-dimensional streamline pattern in unsteady flows as well as the quantification of the velocity field over an entire plane. The advantage of this technique is that the velocity field can be measured over an entire plane of the flow field simultaneously, with accuracy and spatial resolution. From this the instantaneous vorticity field can be easily obtained. This constitutes a great asset for the study of a variety of flows that evolve stochastically in both space and time. The basic concept of LSV; methods of data acquisition and reduction, examples of its use, and parameters that affect its utilization are described

The development of laser speckle or particle image displacement velocimetry. Part 1: The role of photographic parameters

One of the difficult problems in experimental fluid dynamics remains the determination of the vorticity field in fluid flows. Recently, a novel velocity measurement technique, commonly known as Laser Speckle or Particle Image Displacement Velocimetry became available. This technique permits the simultaneous visualization of the 2 dimensional streamline pattern in unsteady flows and the quantification of the velocity field. The main advantage of this new technique is that the whole 2 dimensional velocity field can be recorded with great accuracy and spatial resolution, from which the instantaneous vorticity field can be easily obtained. A apparatus used for taking particle displacement images is described. Local coherent illumination by the probe laser beam yielded Young's fringes of good quality at almost every location of the flow field. These fringes were analyzed and the velocity and vorticity fields were derived. Several conclusions drawn are discussed

Unsteady flow past an airfoil pitched at constant rate

The unsteady flow past a NACA 0012 airfoil that is undertaking a constant-rate pitching up motion is investigated experimentally by the PIDV technique in a water towing tank. The Reynolds number is 5000, based upon the airfoil's chord and the free-stream velocity. The airfoil is pitching impulsively from 0 to 30 deg. with a dimensionless pitch rate alpha of 0.131. Instantaneous velocity and associated vorticity data have been acquired over the entire flow field. The primary vortex dominates the flow behavior after it separates from the leading edge of the airfoil. Complete stall emerges after this vortex detaches from the airfoil and triggers the shedding of a counter-rotating vortex near the trailing edge. A parallel computational study using the discrete vortex, random walk approximation has also been conducted. In general, the computational results agree very well with the experiment

Avaliação da produção de biomassa vegetal de quatro espécies visando a melhoria do solo de vegetação secundária na Amazônia Central.

Buscando técnicas inovadoras e sustentáveis para serem usadas na agricultura como forma de deixar o solo mais fértil e recuperar áreas modificadas, o presente trabalho foi realizado. No período de janeiro de 2011 a março de 2012, foram inseridas e monitoradas junto à capoeira no Campo Experimental da Embrapa Amazônia Ocidental km 29, quatro espécies vegetais conhecidas da Amazônia, (Tefrosia candida, Flemingia macrophyla, Bixa orellana e Inga edulis), tais espécies apresentam um grande potencial de acúmulo de biomassa e nutrientes

Where the excess photons and dileptons in SPS nuclear collisions come from?

Recently the first single photon spectra from CERN energy heavy-ion collisions were reported by WA80, while NA34/3 and NA38 have obtained the spectra for dileptons with the mass up to 4-5 GeV. The production rates for photons and dileptons significantly increase when reactions involving the $A_1$ meson are included. However, with the conventional expansion scenario, the absolute yields are still significantly smaller than the observed ones. It may indicate that expansion in the ``mixed state" takes much more time

Potassium Concentration In Blood Of Brazilian Athletes Using Naa

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)In this study the potassium levels in blood were determined in male athletes, age 18 to 26 years, before, during and after the tread mill exercise protocol using Neutron Activation Analyses (NAA). These data are important to check the potassium imbalance in blood during the period of competition preparation. © 2011 American Institute of Physics.1351336339Brazilian Physical Society (SBF),Sao Paulo Research Foundation (FAPESP),Coordenacao Aperfeicoamento Pessoal Ensino Super. (CAPES),Rio de Janeiro Research Foundation (FAPERJ),National Research Council (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Versieck, L., (1988) Anal. Chim. Acta, 204, p. 63Kovacs, L., Zamboni, C.B., Oliveira, L., Salvador, V.L.R., Sato, I.M., Azevedo, M.R., Analysis of serum and whole blood using NAA for clinical investigation (2008) J. Radioanal. Nucl. Chem., 278, pp. 543-545Medeiros, J.A.G., Zamboni, C.B., Zahn, G.S., Oliveira, L.C., Dalaqua Jr., L., Software para realização de análises hematológicas utilizando processo radioanalítico Proceeding of 39° Congresso Brasileiro de Patologia Clinica (SP, Brasil, 2005