Micro Displacement and Strain Detection for Crack Prediction on Concrete Surface Using Optical Nondestructive Evaluation Methods

Continuous inspection of the concrete structures is important for extending the operating life span of nuclear power plants. Restricted physical accessibility to the nuclear plant structures, due to concerns of radiation, presents a unique challenge to the conventional visual inspection and contact-type nondestructive evaluation (NDE) technologies. Digital image correlation (DIC) is an optical NDE method that can measure the structural parameters such as displacement and strain. However, it is highly challenging to accurately detect micro displacement on the concrete surface because of weathering and change in illumination conditions. Usually, an artificial speckle pattern with good contrast to the object surface is needed for calibration and tracking, but it is difficult to apply in the field. In order to be able to detect micro surface strain for crack prediction in outdoor environment, a DIC-based NDE technology is developed to significantly improve the measurement accuracy by incorporating the orientation code matching (OCM) technique, a robust and accurate template matching algorithm. Concrete specimens were built and tested under four-point bending. Using the remotely measured images, the OCM incorporated DIC method successfully predicted concrete cracks before they emerged on the surface. The experiments also demonstrated the robustness of the method against the optical noise including weathering and change in illumination conditions

Micro Displacement and Strain Detection for Crack Prediction on Concrete Surface Using Optical Nondestructive Evaluation Methods

Continuous inspection of the concrete structures is important for extending the operating life span of nuclear power plants. Restricted physical accessibility to the nuclear plant structures, due to concerns of radiation, presents a unique challenge to the conventional visual inspection and contact-type nondestructive evaluation (NDE) technologies. Digital image correlation (DIC) is an optical NDE method that can measure the structural parameters such as displacement and strain. However, it is highly challenging to accurately detect micro displacement on the concrete surface because of weathering and change in illumination conditions. Usually, an artificial speckle pattern with good contrast to the object surface is needed for calibration and tracking, but it is difficult to apply in the field. In order to be able to detect micro surface strain for crack prediction in outdoor environment, a DIC-based NDE technology is developed to significantly improve the measurement accuracy by incorporating the orientation code matching (OCM) technique, a robust and accurate template matching algorithm. Concrete specimens were built and tested under four-point bending. Using the remotely measured images, the OCM incorporated DIC method successfully predicted concrete cracks before they emerged on the surface. The experiments also demonstrated the robustness of the method against the optical noise including weathering and change in illumination conditions

De-personifying Collaert's Four Continents: European descriptions of continental diversity, 1585–1625

Adriaen Collaert's personifications of the four continents are typical examples of how continents and their respective cultures were represented in the art and literature of Europe in the early-modern period. For example, Asia is the exotic double to Europe, possessing an ‘otherness’ upon which European identity has been juxtaposed. Such personifications of continents and broader tropes of ‘the other’ and ‘the exotic’ have greatly influenced the historiography of the idea of Europe. However, the creation of art and literature characterised by these tropes reflects only part of the European understanding of the wider world. This article will explore how travellers – such as missionaries, merchants and ambassadors – in Europe's encounters with non-European societies presented a complex picture of the world sought to offer practical guidance and knowledge. How travellers’ accounts and personifications interacted is important for understanding the European experience of other continents. In considering how travellers presented their knowledge of continents, it is possible to analyse both how early-modern Europeans viewed other continents and question how useful artistic representation of ‘other’ continents are for understanding how they viewed their own

Numerical studies on supersonic spray combustion in high-temperature shear flows in a scramjet combustor

Numerical simulation is applied to detail the combustion characteristics of n-decane sprays in highly compressible vortices formed in a supersonic mixing layer. The multi-phase reacting flow is modeled, in which the shear flow is solved Eulerianly by means of direct numerical simulation, and the motions of individual sub-grid point-mass fuel droplets are tracked Lagrangianly. Spray combustion behaviors are studied under different ambient pressures. Results indicate that ignition kernels are formed at high-strain vortex braids, where the scalar dissipation rates are high. The flame kernels are then strongly strained, associated with the rotation of the shearing vortex, and propagate to envelop the local vortex. It is observed that the flammable mixtures entrained in the vortex are burned from the edge to the core of the vortex until the reactants are completely consumed. As the ambient pressure increases, the high-temperature region expands so that the behaviors of spray flames are strongly changed. An overall analysis of the combustion field indicates that the time-averaged temperature increases, and the fluctuating pressure decreases, resulting in a more stable spray combustion under higher pressures, primarily due to the acceleration of the chemical reaction

The Challenge of World Literary History

In much of its history from the 19th century to the last decade of the 20th, comparative literature remains largely Euro-centered, and the rise of world literature today offers an opportunity to transcend Eurocentrism and introduce many of the yet unknown canonical works from non-Western and “minor” European literatures to a global readership. We need a world literary map to show what the world looks like in terms of literary traditions and their important works, and therefore a world history of literature is the necessary first step towards a better understanding of what is world literature.Non UBCUnreviewedFacult