1,721,139 research outputs found
Application of displacement and contouring measurement to the determination of constitutive equations
No full textMechanical Characterization of orthotropic materials by means of speckle interferometry and simulated annealing
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Investigation on relative merits of different fringe analysis procedures in ESPI measurement on electronic components
No full textA comprehensive ESPI based system for combined measurement of shape and deformation of electronic components
No full textThis paper describes a very simple and reliable procedure for measuring shape and
deformation of electronic components with a single experimental set-up. The procedure is
based on two electronic speckle pattern interferometry (ESPI) techniques referred to as
conventional ESPI and phase shifting ESPI (PS-ESPI). The present research is motivated by
the fact that mismatch in thermal expansion coefficients of the different materials included in
electronic packaging (EP) may cause mechanical failures since thermal stresses will change
sharply through subsequent loading cycles. ESPI is particularly suitable for measurements on
EP since it allows us to perform non–contact testing of non-planar heterogeneous surfaces. It
is apparent that gathering detailed topographic information will certainly help us to measure
accurately surface deformations of EP along with modeling correctly numerical analysis.
As is known, the accuracy of results obtained with ESPI may be significantly improved by
phase shifting techniques (PST). Therefore, this paper compares the relative merits of different
phase-stepping strategies in order to find which strategy will perform the best for the optical
set-up utilized in the experiments. Preliminary investigations on a standard specimen under
three-point-bending served to choose properly the optical set-up and phase-stepping procedure
which yield the best fringe visibility. Four-phases achieved the best fringe visibility and the
minimum number of invalid pixels.These information have been utilized in the experimental campaign on standard and surface
mounted technology (SMT) electronic components. ESPI and PS-ESPI have been used for
analyzing the transient state and the steady state of devices, respectively. From the
experimental results obtained here, it appears possible to measure strains induced by thermal
loading cycles. The experimental set-up, based on the Lendeertz’s interferometer, proved itself
also able to contour specimen surface at a good level of detail. Remarkably, by using the same
set-up for deformation and shape measurements we can preserve the pixel by pixel relationship
between displacements and surface depth which will hold true if correlation between different
exposures is not destroyed.
The results obtained in this research justify using PS-ESPI in order to understand better
failure mechanisms of electronic components. This fact along with the exact knowledge of
object shape may be particularly useful in the different design stages (including FEM modeling
and analysis) of electronics for special applications
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