The Northern Long-eared Myotis (Myotis septentrionalis) is known to hibernate in mines and caves, often using cracks within these hibernacula as roost sites. We hypothesized that M. septentrionalis might use deep cracks in rock outcrops for hibernation as well. To test this hypothesis, we placed acoustical bat detectors near rock outcrops away from any known mines or caves during winter in Nebr...

Automated systems for road crack detection are extremely important in road maintenance for vehicle safety and traveler’s comfort. Emerging cracks in roads need to be detected and accordingly repaired as early as possible to avoid further damage thus reducing rehabilitation cost. In this paper, a robust method for Gabor filter parameters optimization for automatic road crack detection is discuss...

An advanced, waveform based acoustic emission (AE) system was used to study the initiation of transverse matrix cracking in cross-ply graphite/epoxy (gr/ep) composites. The AE signals were detected with broad band, high fidelity sensors, and digitized for analysis. Plate wave propagation analysis was used to discriminate noise signals from those generated by cracks. The noise signals were confi...

Measurement and analysis of cracks on the surface of reinforced concrete can be an effective key for diagnosing quake-proofness of a construction or measuring material fatigue. The conventional method of diagnosis is to analyze cracks using a sketch manually produced by inspection engineers, however it takes a fairly long time and lacks quantitative objectivity. This paper proposes an automatic...

Reinforced carbon/carbon (RCC) is used to protect the wing leading edge and nose cap of the Space Shuttle Orbiter on re-entry. It is composed of a lay-up of carbon/carbon fabric protected by a SiC conversion coating. Due to the thermal expansion mismatch of the carbon/carbon and the SiC, the SiC cracks on cool-down from the processing temperature. The cracks act as pathways for oxidation of the...

We have developed a low frequency theory for scattering from surface cracks. For the case of halfpenny shaped surface cracks, we are able to relate the reflection coefficient of a Rayleigh wave incident on the crack with the crack size as well as the fracture stress of a sample with the crack in it. Comparisons of the theoretical predictions for the fracture stress with the actual fracture stre...

MAX phase materials are emerging as attractive engineering materials in applications where the material is exposed to severe thermal and mechanical conditions in an oxidative environment. The Ti2AlC MAX phase possesses attractive thermomechanical properties even beyond a temperature of 1000 K. An attractive feature of this material is its capacity for the autonomous healing of cracks when opera...

LiNi1/3Mn1/3Co1/3O2-layered cathode is often fabricated in the form of secondary particles, consisting of densely packed primary particles. This offers advantages for high energy density and alleviation of cathode side reactions/corrosions, but introduces drawbacks such as intergranular cracking. Here, we report unexpected observations on the nucleation and growth of intragranular cracks in a c...

OBJECTIVE In this study, we aimed to evaluate and compare the dentinal walls of root-end cavities for the presence of cracks after cavity preparation using US retrotips and Er: YAG laser. MATERIALS AND METHODS Fifty single-rooted teeth were prepared by Protaper NiTi rotary system and obturated by lateral condensation. Three milimeters of root-end was resected. Twenty teeth were prepared with ...

The phenomenon of ageing structures has focused attention on the problem of multiple-site damage (MSD) and wide spread fatigue damage (WFD). In isolation each ̄aw or crack may be safe. However, the cumulative e€ect of multiple, interacting cracks may signi®cantly degrade the damage tolerance of the structure. This paper presents an overview of a new ®nite element alternating technique algorithm...