- Biblioteca Digitais de Teses e Dissertações da USP
- Universidade Federal do Rio Grande do Sul
- Elsevier B.V.
- F. Carapau, "One-dimensional viscoelastic fluid model where viscosity and normal stress coeffients depend on the shear rate",Nonlinear Analysis:Real World Applications, Volume 11, Issue 5, pp. 4342-4354, 2010.
- MIT - Massachusetts Institute of Technology
- Université de Montréal
- Universidade de Adelaide
- Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto.
- American Society of Civil Engineers
- Universidade Duke
- Royal Asiatic Society
- Geological Society of London
- Pergamon-Elsevier Ltd
- Journal of the Southern African Institute of Mining and Metallurgy
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Análise dos mecanismos resistentes e das similaridades de efeitos da adição de fibras de aço na resistência e na ductilidade à punção de lajes-cogumelo e ao cisalhamento de vigas de concreto.; Analysis of resistant mechanisms and similarities of the addition effect of steel fibers on strength and ductility to both the punching shear of flat slabs and the shear of concrete beams.
"Distribuição de tensões em testes de cisalhamento e micro-cisalhamento mediante análise de elementos finitos" ; A finite element stress analysis of shear and micro-shear bond strength tests
Análise comparativa entre modelos de predição de norma e dados de ensaios na determinação da resistência ao cisalhamento.; Comparative analysis among standards prediction models and tests data in shear strength determination.
Investigação geofísica e resistência ao cisalhamento de resíduos sólidos urbanos de diferentes idades; Geophysical investigation and shear strength of municipal solid wastes with different landfilling ages
Desenvolvimento de equipamento Ring Shear para avaliação do comportamento de solos a grandes deformações
Effect of fiber orientation on the shear behavior of glass fiber/epoxy composites
One-dimensional viscoelastic fluid model where viscosity and normal stress coeffients depend on the shear rate
Nonlinear Shear and Extensional Flow Dynamics of Wormlike Surfactant Solutions
Quantitative ultrasound imaging during shear wave propagation for application related to breast cancer diagnosis
A generic mechanics approach for predicting shear strength of reinforced concrete beams.
Quantifying the compressive ductility of concrete in RC members through shear friction mechanics.
Desenvolvimento de ferramentas e provetes para o ensaio Thick Adherend Shear Test (TAST).
CFRP SHEAR STRENGTHENING OF REINFORCED CONCRETE T-BEAMS WITH CORRODED SHEAR LINKS
Acoustic Radiation Force Impulse-Driven Shear Wave Velocimetry in Cardiac Tissue
Acoustic radiation force impulses (ARFI) have been used to generated transverse-traveling mechanical waves in various biological tissues. The velocity of these waves is related to a medium's stiffness and thus can offer useful diagnostic information. Consequently, shear wave velocimetry has the potential to investigate cardiac disease states that manifest themselves as changes in tissue stiffness (e.g., ischemia).
The work contained herein focuses on employing ARFI-based shear wave velocimetry techniques, similar to those previously utilized on other organs (e.g., breast, liver), for the investigation of cardiac tissue. To this end, ARFI excitations were used to generate slow-moving (under 3 m/s) mechanical waves in exposed myocardium (with access granted through a thoracotomy); these waves were then tracked with ultrasonic methods. Imaging techniques to increase frame-rate, decrease transducer/tissue heating, and reduce the effects of physiological motion were developed. These techniques, along with two shear wave velocimetry methods (i.e., the Lateral Time-to-Peak and Radon sum transformation algorithms), were utilized to successfully track shear wave propagation through the mid-myocardial layer
The Adaptive Response of Endothelial Cells to Shear Stress Alteration
The adaptive response of vascular endothelial cells to shear stress alteration induced by global hemodynamic changes is an essential component of normal endothelial physiology in vivo; and an understanding of the transient regulation of endothelial phenotype during adaptation will advance our understanding of endothelial biology and yield new insights into the mechanism of atherogenesis. The objective of this study was to characterize the adaptive response of arterial endothelial cells to acute increases in shear stress magnitude and frequency in well-defined in vitro settings. Porcine endothelial cells were preconditioned by a basal level shear stress of ±15dynes/cm^2 at 1 Hz for 24 hours, and an acute increase in shear stress magnitude (30 ±15 dynes/cm^2) or frequency (2 Hz) was then applied. Endothelial permeability to bovine serum albumin was measured and gene expression profiling was performed using microarrays at multiple time points during a period of 6 hours after the shear stress alteration. The instantaneous endothelial permeability was found to increase rapidly in response to the acute increase in shear stress magnitude. Endothelial permeability nearly doubled after 40 minutes exposure to the elevated shear magnitude...
Shear Wave Imaging using Acoustic Radiation Force
Tissue stiffness can be an indicator of various types of ailments. However, no standard diagnostic imaging modality has the capability to depict the stiffness of tissue. To overcome this deficiency, various elasticity imaging methods have been proposed over the past 20 years. A promising technique for elasticity imaging is acoustic radiation force impulse (ARFI) based shear wave imaging. Spatially localized acoustic radiation force excitation is applied impulsively to generate shear waves in tissue and its stiffness is quantified by measuring the shear wave speed (SWS).
The aim of this thesis is to contribute to both the clinical application of ARFI shear wave imaging and its technical development using the latest advancements in ultrasound imaging capabilities.
To achieve the first of these two goals, a pilot imaging study was conducted to evaluate the suitability of ARFI shear wave imaging for the assessment of liver fibrosis using a rodent model of the disease. The stiffness of severely fibrotic rat livers were found to be significantly higher than healthy livers. In addition, liver stiffness was correlated with fibrosis as quantified using collagen content.
Based on these findings, an imaging study was conducted on patients undergoing liver biopsy at the Duke University Medical Center. A robust SWS estimation algorithm was implemented to deal with noisy patient shear wave data using the random sample consensus (RANSAC) approach. RANSAC estimated liver stiffness was found to be higher in severely fibrotic and cirrhotic livers...