The vast amount of organic carbon stored in soils of the northern circumpolar permafrost region is a potentially vulnerable component of the global carbon cycle. Yet, estimates of the quantity, decomposability, and combustibility of the carbon contained in permafrost-region soils remain highly uncertain, limiting our ability to predict the release of greenhouse gases due to permafrost thawing.
Nearly 80% of all structural failures are due to mechanical fatigue, which often results in catastrophic, dangerous, and costly failure events. However, a comprehensive model to predict fatigue remains an elusive goal. One of the major challenges is that fatigue is intrinsically a multiscale process that is dependent on the macroscale geometry (i.e., shape) of a device as well as its microscale structural features (e.g., the non-metallic inclusions, crystal grains, or voids found in metal alloys). The presented work will develop a novel multiscale method for fatigue prediction by simulating macroscale geometries explicitly while concurrently calculating the simplified local response of microscale inclusions.
The Geospatial Research Laboratory (GRL) providers the warfighter and Nation with superior knowledge of the battlefield through innovative basic and applied research in geospatial and related sciences.
GRL conducts geospatial research, development, technology and evaluation of current and emerging geospatial technologies that will help characterize and measure phenomena within the physical (terrain) and social (cultural) environment encountered by the Army.
A transient Mixing Cell Model (MCM) was developed for assessing groundwater fluxes in complex hydro-geological basins prevailing transient groundwater flow system. It is aimed for complex systems with vague sub-aquifer structure, lack of hydro-geological information.
Climate variability and change has the potential to cause significant impacts on our economic, ecological, social, and cultural resources. Hurricanes Sandy and Irene provide current examples of such random disruptions. In a changing climate, civil infrastructures (such as dams, bridges, and culverts) are increasingly compromised during extreme precipitation events.
Radiogenic helium-4 produced by the alpha-decay of uranium and thorium in the Earth's mantle and crust is degassed to the atmosphere and eventually escapes to outer space. Assuming an equilibrium between production and degassing, the continental crust is estimated to provide about 70% of the total Earth degassing flux.
Water shortages, and the prospect of such shortages, have been repeatedly faced and addressed as population and economic growth placed increasing demands on available water over the past century. Such challenges have been most common in arid areas, but also have been encountered in some more humid portions of the US during times of drought.