1,721,062 research outputs found
Latent crack path and service life predictions for unnotched concrete under bending by digital speckle correlation method.
No full textMeasurement and analysis of defects in high-performance concrete with three-dimensional micro-computer tomography.
No full textSimulation of fatigue fracture propagation in concrete using a lattice model
No full textThe fracture propagation in concrete under fatigue loading is analysed using a two-dimensional lattice model. A regular triangular lattice model (formed by pin-joined truss elements) accounting for the actual multiphase structure (at the meso-scale level) of the material is developed (an automatic image processing procedure for phase detection is adopted). The properties of each truss in the lattice are assigned according to the phase (coarse aggregate, mortar matrix, air bubble, mortar-aggregate interface) the truss lies over. Under monotonic loading, the trusses are assumed to have a linear elastic behavior in compression, whereas in tension a linear elastic behavior up to a certain peak load is followed by a linear softening branch. Fatigue damage is accounted for by considering a suitable elastic stiffness degradation. Some numerical results related to high-performance concrete specimens under high-cycle bending loading are presented
Investigation on fatigue damage mechanism of modern concrete microstructure by lattice model
No full textEffect of Variation Consentration Ion Nd3+ on the Physical and Optical Properties of TZBN Glasses as a Host Material Glass Laser
Full text linkThis study aims to determine the effect of Nd ionconcentration on the physical and optical
properties of tellurite glass. Tellurite glass used is TZBN (Tellurium Zinc Bismuth Natrium
Oxide), with composition (mol%) 60TeO2-(35-x) ZnO-2Bi2O3-3Na2O, and x(Nd2O3) with
variation of x= 0.5; 1.0; 1.5; 2.0; 2.5 mol% as a doping. Fabrication is done by using the melt
quenching method. The physical properties of glass density was measured using pycnometer.
Absorption spectra of glass be learned using UV-VIS-NIR spectroscopy in the range 400 nm
to 1100 nm. Refractive index values were measured using the method of Brewster angle at a
wavelength of 632.8 nm and 532 nm. The result of characterization shows that the density
index, refractive index and the optical absorption increase as the Nd3+
ions concentration
doped to tellurite glasses.
Keywords : ion Nd3+
concentration , TZBN, glass densit
Real-time detection and analysis of damage in high-performance concrete under cyclic bending.
No full textIn order to quantitatively evaluate the damage
level in high-performance concrete (HPC) with pozzolanic
minerals under constant amplitude cyclic loads, three
methods for real-time damage detection are employed in
the present work, i.e., dynamic modulus instrument, realtime
strain collector, and digital speckle correlative method
(DSCM). Six mechanical parameters at different numbers
of loading cycles are real-time captured by these three
methods. For a maximum applied fatigue stress equal to
70% of the static flexural strength, a cohesive crack is
detected on the specimen surface by the DSCM system from
10% of concrete fatigue life. The nucleation and propagation
of the cohesive crack is reflected by the change of the strain
concentration zone in 2-dimensional strain fields. The
experimental results show that the admixtures of Class F
Fly Ash (FA) and S95 Ground Granulated Blast-furnace Slag
(GGBS) in high proportions increase the strain and cohesivecrack
opening displacement as well as remarkably improve
the fatigue performance of HPC
Fatigue damage of high performance concrete through a 2D mesoscopic lattice model
No full textBased on high-resolution digital images of High Performance Concrete (HPC) microstructures, a two-dimensional mesoscopic lattice model which accounts for fatigue damage is proposed. Fatigue damage is introduced by considering the coupled effects of loading cycles and tensile strain on stiffness degradation of microstructural lattice elements under fatigue loading. The ultimate tensile strain is defined as the failure threshold value for microstructural lattice elements. Further, the effects of the lattice element properties (i.e. size and finite element type) and fatigue loading parameters (i.e. stress levels) on the damage mechanisms of the HPC microstructure are investigated and discussed. It is found that lattice truss elements 1 mm long are satisfactory, giving also their smaller computational requirements in comparison to beam counterparts, to investigate fatigue damage in the HPC microstructure. The numerical results of the present model are consistent with experimental observations
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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