OBJECTIVE Animal data suggest that cocaine has an immunosuppressive effect, but no human studies have been conducted to assess the relation of cocaine use with human papillomavirus (HPV) infection, the viral cause of cervical cancer. Since both cocaine use and HPV infection are common among HIV-positive women, we sought to determine whether use of cocaine and/or crack influences the natural his...

Inspections play an essential role in the damage tolerance approach to control fatigue damage. In this paper a method is presented to optimize the cost-effectiveness of inspection scheduling for single and multiple inspections during the expected lifetime. Detailed results are given for a surface-breaking crack of depth a in a cyclic tension field. The original crack depth is treated as a rando...

In order to monitor the crack tip propagation of aluminum alloy, this study investigates the variation of the spectrum characteristics of a fiber Bragg grating (FBG), combined with an analysis of the spectrum simulation. The results identify the location of the subordinate peak as significantly associated with the strain distribution along the grating, corresponding to the different plastic zon...

Solar cell is known as a sustainable and environment friendly source of energy in nature. It converts sunlight directly into electricity with zero emission and also without side-effects on the environment. But, solar cells have optical and mechanical defects which include the type of micro crack, the size of crack, and the noise from electrical or electromechanical interference during the image...

Thermal fatigue in the mixing zones of pressurized water reactor pipings can potentially lead to the appearance of crack networks. Ultrasonic detection and characterization of a propagated defect in such a network is then a challenge. To study the influence of these secondary crack networks on the ultrasonic inspection of a propagated defect, a mock-up was produced. The innovative manufacturing...

This paper presents a methodology for assessing the confidence and the predictive capability of prognosis models, using the application of fatigue crack growth analysis. Structures with complicated geometry and multi-axial variable amplitude loading conditions are considered. Several models – finite element model, crack growth model, retardation model, surrogate model, etc. – are efficiently co...

A numerical technique for modeling fatigue crack propagation of multiple coplanar cracks is presented. The proposed method couples the extended finite element method (X-FEM) [Int. J. Numer. Meth. Engng. 48 (11) (2000) 1549] to the fast marching method (FMM) [Level Set Methods & Fast Marching Methods: Evolving Interfaces in Computational Geometry, Fluid Mechanics, Computer Vision, and Materials ...

Reliable early-stage damage detection requires continuous monitoring over large areas of structure, and with sensors of high spatial resolution. Technologies based on Large Area Electronics (LAE) can enable direct sensing and can be scaled to the level required for Structural Health Monitoring (SHM) of civil structures and infrastructure. Sensing sheets based on LAE contain dense arrangements o...

Widely used 1-D guided wave phased arrays can only scan within 0°~180° range due to the intrinsic structural limitation. To overcome this limitation, multiple installations are unavoidable. However, by using 2-D configuration phased arrays, large structural interrogation can be conducted from a single location with a single scanning covering the entire 0°~360° range through omnidirectional beam...