Image processing technologies are proposed to quantify crack patterns. On the basis of the technologies, a software “Crack Image Analysis System” (CIAS) has been developed. An image of soil crack network is used as an example to illustrate the image processing technologies and the operations of the CIAS. The quantification of the crack image involves the following three steps: image segmentatio...

We present recent results on the modeling and numerical simulation of reservoir stimulation in Hot Dry Rocks. Our approach is based on a mechanistically faithful yet mathematically sound model, generalizing Griffith's idea of competition between bulk and surface energies. At each time increment, the fracture and displacement configuration of a reservoir is sought as the minimizer of a global en...

This paper develops the extended finite element method (XFEM) to evolve patterns of multiple cracks, in a brittle thin film bonded to an elastic substrate, with a relatively coarse mesh, and without remeshing during evolution. A shear lag model describes the deformation in three dimensions with approximate field equations in two-dimensions. The film is susceptible to subcritical cracking, obeyi...

Crack assessment is an essential process in the maintenance of concrete structures. In general, concrete cracks are inspected by manual visual observation of the surface, which is intrinsically subjective as it depends on the experience of inspectors. Further, it is time-consuming, expensive, and often unsafe when inaccessible structural members are to be assessed. Unmanned aerial vehicle (UAV)...

This paper presents a novel real-time crack identification method to determine the position and depth of a transverse open crack on a rotating shaft. A newly developed wireless sensor capable of being mounted directly on the shaft can be employed to monitor acceleration at different points of a shaft in a rotating coordinate system. The vibration parameters obtained from a Finite Element Model ...

This paper presents a novel real-time crack identification method to determine the position and depth of a transverse open crack on a rotating shaft. A newly developed wireless sensor capable of being mounted directly on the shaft is employed to monitor acceleration at different points of the shaft in a rotating coordinate system. The vibration parameters obtained from the wireless sensors and ...

The object of this work is to calculate the T (transition) matrix for a circular crack in a homogeneous, isotropic, linear elastic medium. The T matrix method is a building block technique for multiple scattering, where the T matrix is calculated for each scatterer separately without prior knowledge of the other scatterers (cracks, inclusions, surfaces, etc.).This means that we solve the scatte...

Denda and Marante [1] have developed the boundary element method for the mixed mode fracture analysis of multiple curvilinear cracks in the general anisotropic solids in two dimensions for which in-plane Mode I, II, and out-of-plane Mode III, of fracture are coupled. They have developed the crack tip singular element (CTSE) to model any curvilinear cracks, including center and edge cracks. The ...

There are many ways that women support their use of crack cocaine, including sex-for-crack bartering and other forms of prostitution. Empirical studies conducted in the mid-1970s and in the mid-1980s in New York City, and in Chicago in the late 1980s to early 1990s are compared, analyzing similarities and differences between the contemporary crack-prostitution scene and previous prostitution sc...