Monitoring of mining induced subsidence through measurement of ground strains with Fiber Bragg Grating sensors
In this paper the application of Fiber Bragg Grating based sensors for the monitoring of mining induced subsidence phenomena is illustrated. A high number of sensors were installed in the pavement of a major highway thanks to the use of Bragg Grating arrays encapsulated in composite rods. The sensors and the associated demodulation equipment provide continuous measurements and allow the immediate implementation of safety measures by the authorities responsible for the highway.
Mine Induced Subsidence: Effects on Engineered Structures
The influence of mine subsidence on engineered structures is a growing concern of the United States coal industry. This book contains a collection of case histories of the control and effects of mine induced subsidence on engineered structures. These papers review structural damage and reconstruction in areas of underground coal mining, subsidence effects and damage to highways and other transportation facilities, and subsidence causes and effects over abandoned mine lands. In addition, the analysis of subsidence stabilization techniques, control by grouting, and abatement projects are presented.
Mass Loss History of Evolved Stars
We provide high-resolution maps of the circumstellar dust shells of several dozen Asymptotic Giant Branch (AGB) stars using data from the Spitzer space telescope Multiband Imaging Photometer (MIPS) imaged at 70μm. AGB stars are the major contributors of chemical elements such as carbon, oxygen and silicon, which are essential to the existence of life in the universe, through mass loss processes that take place at the surface of the star. We probe the spatial distribution of cold (∼40 K) dust grains in order to trace the history of mass loss from the observed radial density variation in these shells. Our images illustrate that different morphologies may evolve because AGB stars can already interact with the interstellar medium (ISM) that surrounds them even at these early stages of the AGB mass loss history. Relative motion of the star as well as the ISM with respect to the local environment may be of particular importance for shell structure evolution.