Umbilical Deployment Device

The landing scheme for NASA's next-generation Mars rover will encompass a novel landing technique (see figure). The rover will be lowered from a rocket-powered descent stage and then placed onto the surface while hanging from three bridles. Communication between the rover and descent stage will be maintained through an electrical umbilical cable, which will be deployed in parallel with structural bridles. The -inch (13-mm) umbilical cable contains a Kevlar rope core, around which wires are wrapped to create a cable. This cable is helically coiled between two concentric truncated cones. It is deployed by pulling one end of the cable from the cone. A retractable mechanism maintains tension on the cable after deployment. A break-tie tethers the umbilical end attached to the rover even after the cable is cut after touchdown. This break-tie allows the descent stage to develop some velocity away from the rover prior to the cable releasing from the rover deck, then breaks away once the cable is fully extended. The descent stage pulls the cable up so that recontact is not made. The packaging and deployment technique can store a long length of cable in a relatively small volume while maintaining compliance with the minimum bend radius requirement for the cable being deployed. While the packaging technique could be implemented without the use of break-ties, they were needed in this design due to the vibratory environment and the retraction required by the cable. The break-ties used created a series of load-spikes in the deployment signature. The load spikes during the deployment of the initial three coils of umbilical showed no increase between the different temperature trials. The cold deployment did show an increased load requirement for cable extraction in the region where no break-ties were used. This increase in cable drag was superimposed on the loads required to rupture the last set of break-ties, and as such, these loads saw significant increase when compared to their ambient counterparts. While the loads showed spikes of high magnitude, they were of short duration. Because of this, neither the deployment of the rover, nor the motion of the descent stage, would be adversely affected. In addition, the umbilical was found to have a maximum of 1.2 percent chance for recontact with the ultra-high frequency antenna due to the large margin of safety built in

Mass Loading Measurements in Amargosa Valley

This work will be conducted under Task DRI-FI-001, “Mass Loading Measurements in Amargosa Valley.” The objective of this task is to measure, with known accuracy, the levels of atmospheric mass loading (mass concentration of suspended particulates) accompanying soil surface disturbing activities in Amargosa Valley. Mass loading is used in the biosphere model to calculate inhalation exposure for the human receptor, the maximally reasonably exposed individual (RMEI). The mass loading currently used in the biosphere model is based on literature data from the analog sites rather than on site-specific conditions. This work is subject to the Nevada System of Higher Education (NSHE, previously UCCSN) QA program requirements

Developing a Robust Geologic Conceptual Model Using Pseudo 3-D P-Wave Seismic Reflection Data

As part of a multiscale hydrogeophysical and modeling study, a pseudo three-dimensional (3-D) seismic surveywas conducted over a contaminant plume at P area, Savannah River site (South Carolina), to enhance the existing geologicmodel by resolving uncertainties in the lithostratigraphic sequence. The geometry of the dissolved phase trichloroethylene plume, based on initial site characterization, appears to be confined to a narrow corridor within the Eocene sand overlying a clay unit approximately 25m(82 ft) below land surface. Processing the seismic data as a 3-D data volume instead of a series of closely spaced two-dimensional lines allowed for better interpretation of the target horizons, the lower clay, and the sand above the clay. Calibrating the seismic data with existing borehole geophysical logs, core data as well as vertical seismic profiling (VSP) data allowed the seismic data to be inverted from two-way travel-time to depth, thereby facilitating full integration of the seismic data into a solid earth model that is the basic part of a site conceptual model. The outcome was the production of realistic horizon surface maps that show that two channel complexes are located on the section, which are not present in the conceptual model, and that the upper and middle clays are not laterally continuous as previously thought. The geometry of the primary channel has been transposed over the map view of the plume to investigate potential relationships between the shape of the plume and the presence of the channel

Structural and Stratigraphic Control on the Migration of a Contaminant Plume at the P Reactor Area, Savannah River Site, South Carolina

Geophysical methods, including a shallow seismic reflection (SSR) survey, surface and borehole ground-penetrating radar (GPR) data, and electrical resistivity imaging (ERI), were conducted at the Savannah River site (SRS), South Carolina, to investigate the shallow stratigraphy, hydrogeophysical zonation, and the applicability and performance of these geophysical techniques for hydrogeological characterization in contaminant areas. The study site is the P Reactor area located within the upper Atlantic coastal plain, with clastic sediments ranging from Late Cretaceous to Miocene in age. The target of this research was the delineation and prediction of migration pathways of a trichloroethylene (TCE) contaminant plume that originates from the northwest section of the reactor facility and discharges into the nearby Steel Creek. This contaminant plume has been migrating in an east-to-west direction and narrowing away from the source in an area where the general stratigraphy along with the groundwater flow dips to the southeast. Here, we present the results from a stratigraphic and hydrogeophysical characterization of the site using the SSR, GPR, and ERI methods. Although detailed stratigraphic layers were identified in the upper approximately 50 m (164 ft), other major findings include (1) the discovery of a shallow (∼23 m [75 ft] from the ground surface) inverse fault, (2) the detection of a paleochannel system that was previously reported but that seems to be controlled by the reactivation of the interpreted fault, and (3) the finding that the hydraulic gradient seems to have a convergence of groundwater flow near the area. The interpreted fault at the study site appears to be of upper Eocene age and may be associated with other known reactivated faults within the Dunbarton Triassic Basin. The coincident use of the SSR and ERI methods in conjunction with the complementary 50-, 100-, and 200-MHz GPR antennas allowed us to generate a detailed geologic model of the shallow subsurface, suggesting that the migration of the TCE plume is constrained by (1) the paleochannel system with respect to its migration direction, (2) the presence of an inverse fault that may also contribute to the paleochannel growth and structural evolution, and (3) the local groundwater flow volume with respect to its longer and narrower shape away from the source updip stratigraphic bedding

Homophily in the Digital World: A LiveJournal Case Study

Special issue on Social Computing in Blogosphere (IC)</p

Silo Storage Preconceptual Design

The National Nuclear Security Administration (NNSA) has a need to develop and field a low-cost option for the long-term storage of a variety of radiological material. The storage option’s primary requirement is to provide both environmental and physical protection of the materials. Design criteria for this effort require a low initial cost and minimum maintenance over a 50-year design life. In 1999, Argonne National Laboratory-West was tasked with developing a dry silo storage option for the BN-350 Spent Fuel in Aktau Kazakhstan. Argon’s design consisted of a carbon steel cylinder approximately 16 ft long, 18 in. outside diameter and 0.375 in. wall thickness. The carbon steel silo was protected from corrosion by a duplex coating system consisting of zinc and epoxy. Although the study indicated that the duplex coating design would provide a design life well in excess of the required 50 years, the review board was concerned because of the novelty of the design and the lack of historical use. In 2012, NNSA tasked Idaho National Laboratory (INL) with reinvestigating the silo storage concept and development of alternative corrosion protection strategies. The 2012 study, “Silo Storage Concepts, Cathodic Protection Options Study” (INL/EST-12-26627), concludes that the option which best fits the design criterion is a passive cathotic protection scheme, consisting of a carbon steel tube coated with zinc or a zinc-aluminum alloy encapsulated in either concrete or a cement grout. The hot dipped zinc coating option was considered most efficient, but the flame-sprayed option could be used if a thicker zinc coating was determined to be necessary

Resist materials for 157-nm microlithography: an update

Fluorocarbon polymers and siloxane-based polymers have been identified as promising resist candidates for 157 nm material design because of their relatively high transparency at this wavelength. This paper reports our recent progress toward developing 157 nm resist materials based on the first of these two polymer systems. In addition to the 2-hydroxyhexafluoropropyl group, (alpha) -trifluoromethyl carboxylic acids have been identified as surprisingly transparent acidic functional groups. Polymers based on these groups have been prepared and preliminary imaging studies at 157 nm are described. 2-Trifluoromethyl-bicyclo[2,2,1] heptane-2-carboxylic acid methyl ester derived from methyl 2-(trifluoromethyl)acrylate was also prepared and gas-phase VUV measurements showed substantially improved transparency over norbornane. This appears to be a general characteristic of norbornane-bearing geminal electron-withdrawing substituents on the 2 carbon bridge. Unfortunately, neither the NiII nor PdII catalysts polymerize these transparent norbornene monomers by vinyl addition. However, several new approaches to incorporating these transparent monomers into functional polymers have been investigated. The first involved the synthesis of tricyclononene (TCN) monomers that move the bulky electron withdrawing groups further away from the site of addition. The hydrogenated geminally substituted TCN monomer still has far better transparency at 157 nm than norbornane. The second approach involved copolymerizing the norbornene monomers with carbon monoxide. The third approach involved free-radical polymerization of norbornene monomers with tetrafluoroethylene and/or other electron-deficient comonomers. All these approaches provided new materials with encouraging absorbance at 157 nm. The lithographic performance of some of these polymers is discussed

Comparing Ecoregional Classifications for Natural Areas Management in the Klamath Region, USA

We compared three existing ecoregional classification schemes (Bailey, Omernik, and World Wildlife Fund) with two derived schemes (Omernik Revised and Climate Zones) to explore their effectiveness in explaining species distributions and to better understand natural resource geography in the Klamath Region, USA. We analyzed presence/absence data derived from digital distribution maps for trees, amphibians, large mammals, small mammals, migrant birds, and resident birds using three statistical analyses of classification accuracy (Analysis of Similarity, Canonical Analysis of Principal Coordinates, and Classification Strength). The classifications were roughly comparable in classification accuracy, with Omernik Revised showing the best overall performance. Trees showed the strongest fidelity to the classifications, and large mammals showed the weakest fidelity. We discuss the implications for regional biogeography and describe how intermediate resolution ecoregional classifications may be appropriate for use as natural areas management domains.Keywords: World Wildlife Fund ecoregions, Klamath Region, Omernik ecoregions, management domains, Bailey ecoregion