OBJECTIVES Presentation of a methodological approach using stereo and scanning electron microscope examination for the failure analysis of an alumina all-ceramic premolar crown (Procera AllCeram). METHODS The recovered part of a fractured Procera alumina crown was examined utilizing first a stereomicroscope and second a scanning electron microscope (SEM). The stereomicroscope analysis was per...

Microencapsulated dicyclopentadiene (DCPD) healing agent and Grubbs’ Ru catalyst are incorporated into an epoxy matrix to produce a polymer composite capable of self-healing. The fracture toughness and healing efficiency of this composite are measured using a tapered double-cantilever beam (TDCB) specimen. Both the virgin and healed fracture toughness depend strongly on the size and concentrati...

Gallium arsenide (GaAs) is used in the most demanding semiconductor applications, including medical, aerospace and communication industries, where significant mechanical stresses are experienced during operation. Mechanical from thermal expansion loading can result fracture of GaAs crystals, a leading cause device failure. Unfortunately, underlying mechanisms III-V semiconductors currently not ...

The fracture behaviour of a specific material, semi-crystalline biobased polymer, was here studied. Dynamic tests on strip band specimens were carried out. Fracture surfaces observed at different scales by optical and electron microscopy to describe cracking scenarios. Crack initiation, propagation arrest zones described. Three distinct are highlighted in the initiation zone: zone with conical ...

This paper provides a framework for the extraction of frequent sequences satisfying a given regular expression (RE) constraint. We take advantage of the information contained in the hierarchical representation of an RE by abstract syntax trees (AST). Interestingly, pruning can be based on the anti-monotonicity of the minimal frequency constraint, but also on the RE constraint, even though this ...

the people and nation of central asia: turkmans live in the north of afghanistan and the east of the caspian sea and at some parts of turkmenistan and uzbekistan.iranian turk-mans live in the north east of iran in turkman sahra.they have a special, rich and indige-nous culture. there are many fables and beliefs on the making of turkman carpets. here we recall the tale of “agh-morad”3 . mos...

Fractures strongly influence the permeability of geologic formations, and because most fractures in subsurface are below resolution geophysical methods, predicting spatial evolution fracture networks is important for groundwater resources, oil gas production, geothermal energy. Previous researchers have established that variations lithologic mechanical properties propagation joints layered rock...

We use observations of hydraulic fractures in core, outcrop attributes natural fractures, and analogue models, to address how fracture networks evolve. A slant core from the Wolfcamp Formation—an unconventional shale hydrocarbon reservoir Permian Basin West Texas—collected within 18 m 30 two hydraulically stimulated horizontal wells, provided an opportunity examine directly. In approximately 18...

Natural fractures and discontinuities have significant impact on subsurface flow conditions thus production, of carbonate reservoirs, particularly in low-permeability sediments such as chalk-marl successions characterizing the Lower Cretaceous reservoirs Danish North Sea. Yet diversity distribution are often poorly understood largely underestimated. In heterogeneous, tight natural can enhance p...