The use of crack cocaine has given rise to an intense discussion in society. Research has contributed to the characterization of users and the negative consequences of its use. However, few studies have conducted in-depth study of the social and cultural contexts in which crack cocaine is used. Thus, this study seeks to discuss the ritual of crack cocaine use and its social and health consequen...

Stress corrosion cracking (SCC) is now globally recognized by pipeline operators as a significant threat to the safe and efficient operation of their systems. Onshore natural gas, oil and refined products line pipe steels have all been susceptible to this form of environmentally assisted cracking, which can develop as either low or high pH SCC. Over the years, the pipeline industry has develope...

modelling of crack propagation by finite element method under mixed mode conditions is of prime importance in fracture mechanics. this paper describes an application of finite element method to the analysis of mixed mode crack growth in linear elastic fracture mechanics. crack growth process is simulated by an incremental crack-extension analysis based on the maximum principal stress criterion,...

A two-dimensional numerical model of microstructural e ects in brittle fracture is presented, with an aim towards the understanding of toughening mechanisms in polycrystalline materials such as ceramics. Quasi-static crack propagation is modelled using the extended nite element method (X-FEM) and microstructures are simulated within the framework of the Potts model for grain growth. In the X-FE...

Fatigue-crack-growth tests were conducted on compact, C(T), specimens made of D16Cz (clad) aluminum alloy under constant-amplitude loading, a single spike overload, and simulated aircraft spectrum loading. Constant-amplitude tests were conducted to generate crack-growth-rate data from threshold to near fracture over a wide range of stress ratios (R = Pmin/Pmax = 0.1–0.75) using the new compress...

There is a real and increasing need to monitor the presence and growth of cracks in key regions ofplant within the nuclear, gas and chemical industries [1]. A rugged, permanently attached sensor, capable of operating at temperatures in excess of 400° C, would have substantial benefits, since it would reduce the down-time costs incurred through the forced inspection of known or suspected flaws. ...

According to the fact that parameter selection of support vector machine(SVM) for fault diagnosis is difficult, a new method based on bacterial foraging algorithm(BAF) for support vector machine parameter optimization was proposed , then the faster optimization of the parameters C and RBF kernel parameter γ was performed. The crack rotor as the experiment object, firstly, AE signal of rotors wi...