Ranade R.,University of Michigan |
Ranade R.,Indian Institute of Technology Bombay |
Li Prof. V.C.,University of Michigan |
Stults M.D.,Tuan and Robinson Structural Engineers Inc. |
And 8 more authors.
ACI Materials Journal | Year: 2013
A new fiber-reinforced cementitious composite-high-strength, high-ductility concrete (HSHDC)-has been developed at the University of Michigan, Ann Arbor, in collaboration with the U.S. Army Engineer Research and Development Center, Vicksburg, MS. The micromechanics-based design of HSHDC resulted in a unique combination of ultra-high compressive strength (166 MPa [24 ksi]), tensile ductility (3.4%), and high specific energy absorption under direct tension (greater than 300 kJ/m3 [6270 lb-ft/ft3]). The material design approach and mechanical property characterization of HSHDC under direct tension, split tension, third-point flexure, and uniaxial compression loading, along with its density and fresh properties, are reported in this paper. Copyright © 2013, American Concrete Institute.
Loffredo E.,University of Bari |
Palazzo A.J.,ERDC |
Senesi N.,University of Bari |
Clapp C.E.,University of Minnesota |
Bashore T.L.,HQ ACC A3A
Soil Science | Year: 2010
Slickspot peppergrass (Lepidium papilliferum) is a biennial, or possibly perennial, endemic plant growing in the Southern Idaho high desert in visually distinct small-scale depressions in soils that collect water (so-called slickspots). Lepidium papilliferum establishes seed banks not germinating the first year but remaining dormant and viable for several years. Humic acids (HA) are universally considered to be the most important, abundant, and biologically and chemically active fractions of soil organic matter and are known to affect plant growth by various mechanisms, depending on their origin, nature, and concentration. The effects of HA in slickspot soils and how they relate to the possibility of being a factor in restoring native plants is only partially known. Thus, the objective of this study was to identify and evaluate the effects of HA isolated from three different layers within the soil profile (silt, vesicular, and clay) from inside a representative slickspot on the germination and early growth of slickspot peppergrass. Furthermore, these effects were tentatively related to the chemical, physicochemical, compositional, structural, and functional characteristics of the HA. Results of statistical analysis showed that both the type and concentration of the three HA examined exert a highly significant or significant effect on the germination and early growth of slickspot peppergrass as a function of the soil depth from which the HA originated in the slickspot. In particular, germination seemed to be enhanced, especially at higher concentrations, by the less hydrophobic HA, rich in oxygen and total sugars, present in the bottom clay soil layer, whereas root growth and shoot growth were positively influenced by the more hydrophobic and probably more polycondensed HA, rich in C, H, N, and phenolic OH present in the top layer rich in silt. Copyright © 2010 by Lippincott Williams & Wilkins.
Military Engineer | Year: 2012
Survivability researchers from the US Army Corps of Engineers Engineering Research and Development Center (ERDC) were continuously developing and improving protective technologies with the goal of saving valuable lives of soldiers engaged in military operations. A live-fire demonstration was held at Fort Polk, La., to test rapidly deployable protective structures for deployed troops, focusing specifically on small Combat Outposts (COP) of 300 or fewer personnel. Researchers expected to increase protection without increasing the logistics or equipment necessary to deploy the protection. Specific technologies tested included variations of the Modular Protective System, a combination of a lightweight space frame and composite armor panels that was used to construct perimeter walls, tactical operations centers, elevated guard towers and a protected mortar pit, and its corresponding overhead cover.
Sharp M.K.,ERDC |
Seda-Sanabria Y.,USACE HQ 3E67 |
Matheu E.E.,45 Murray Lane
Applied Mechanics and Materials | Year: 2011
This paper describes collaborative research efforts conducted between the U.S. Army Corps of Engineers (USACE) and the U.S. Department of Homeland Security (DHS). The USACE, through its U.S. Army Engineer Research and Development Center (ERDC), has focused efforts on the development of a collaborative research program to address technical gaps related to risk and blast mitigation for dams. These research efforts involve experimental and analytical tasks designed to improve blast damage prediction capabilities for dams, navigation locks, and levee systems resulting from vehicle and waterborne delivery scenarios. The outcomes from these efforts can inform USACE's priorities, which include refining the current understanding of the effects of potential attacks, the vulnerabilities and weaknesses of its critical assets to various threat conditions, and the local and regional consequences of those attacks in order to develop appropriate protective measures and recovery technologies. © (2011) Trans Tech Publications.
Fowler A.,RIEGL LMS |
GIM International | Year: 2013
A team of scientists recently completed a research visit to Helheim Glacier in Southeast Greenland. The purpose of their research was to characterize the behavior of the glacier using the latest technology in round-based remote sensing, a long-range Terrestrial Laser Scanner (TLS). Retreat, acceleration and thinning of tidewater outlet glaciers around the margins of the Greenland Ice Sheet have continually been observed over the last two decades. On previous trips to Helheim Glacier, they have performed precarious on-ice high-resolution GNSS surveys, and installed climate stations and time-lapse cameras to capture multi-temporal images of the glacier's behavior. Along with these visual and spatial glimpses into the workings of the glacier, researcher David Finnegan from CRREL has previously utilized TLS in an attempt to determine flow velocities at numerous glaciers around the world, albeit with limited success.