Mixed polyvalent-monovalent metal coating for carbon-graphite fibers

An improved coating of gasification catalyst for carbon-graphite fibers is provided comprising a mixture of a polyvalent metal such as calcium and a monovalent metal such as lithium. The addition of lithium provides a lighter coating and a more flexible coating when applied to a coating of a carboxyl containing resin such as polyacrylic acid since it reduces the crosslink density. Furthermore, the presence of lithium provides a glass-like substance during combustion which holds the fiber together resulting in slow, even combustion with much reduced evolution of conductive fragments. The coated fibers are utilized as fiber reinforcement for composites

Thermal tracking of meltwater retention in Greenland’s accumulation area

Poorly understood processes controlling retention of meltwater in snow and firn have important implications for Greenland Ice Sheet’s mass balance and flow dynamics. Here we present results from a 3 year (2007-2009) field campaign studying firn thermal profiles and density structure along an 85 km transect of the percolation zone of west Greenland. We installed one or two thermistor strings at 14 study sites, each string having 32 sensors spaced between 0 and 10 m depth. Data from our network of over 500 sensors were collected at 15-60 min intervals for 1-2 years, thereby recording the thermal signature of meltwater infiltration and refreezing during annual melt cycles. We document three types of heating of firn related to different mechanisms of meltwater motion and freezing, including heterogeneous breakthrough events, wetting front advance, and year-round heating from freezing of residual deep pore water. Vertically infiltrating meltwater commonly penetrates through cold firn accumulated over decades, even where ice layers are present at the previous summer surface and where ice layer thickness exceeds several decimeters. The offset between the mean annual air temperature and the 10 m firn temperature reveals the elevation dependency of meltwater retention along our transect. The firn is less than 10 degrees C warmer than the mean annual air temperature at the region where meltwater runoff initiates. During 2007-2009, runoff was limited to elevations lower than about 1500 m with no sharp runoff limit ; rather, the ratio of retention to runoff transitioned from all retention to all runoff across an about 20 km wide zone

An industrial application of the JPL ACTS with energy recovery

The JPL Activated Carbon Treatment System (ACTS) uses sewage solids derived from municipal wastewater treatment systems as a source of organic material for powdered activated carbons (PAC). The PAC is used for the COD removal from wastewater and as a filter aid in the recovery of additional sewage solids

Mapping subglacial surfaces of temperate valley glaciers by two-pass migration of a radio-echo sounding survey

High-resolution maps of the glacier bed are developed through a pseudo-three-dimensional migration of a dense array of radio-echo sounding profiles. Resolution of three-dimensional maps of sub-glacial surfaces is determined by the radio-echo sounding wavelength, data spacing in the field, and migration. Based on synthetic radio-echo sounding profile experiments, the maximum resolution of the final map cannot exceed one half-wavelength. A methodology of field and processing techniques is outlined to develop a maximum-resolution map of the glacier bed. The field and processing techniques valley glacier in south-central Alaska. The field techniques and the processing steps used on the glacier result in a map of 20 m x 20 m resolution

Thermal boundary conditions on western Greenland: Observational constraints and impacts on the modeled thermomechanical state

The surface and basal boundary conditions exert an important control on the thermodynamic state of the Greenland Ice Sheet, but their representation in numerical ice sheet models is poorly constrained due to the lack of observations. Here we investigate a land-terminating sector of western Greenland and (1) quantify differences between new observations and commonly used boundary condition data sets and (2) demonstrate the impact of improved boundary conditions on simulated thermodynamics in a higher-order numerical flow model. We constrain near-surface temperature with measurements from two 20mboreholes in the ablation zone and 10m firn temperature from the percolation zone. We constrain basal heat flux using in situ measurement in a deep bedrock hole at the study area margin and other existing assessments. To assess boundary condition influences on simulated thermal-mechanical processes, we compare model output to multiple full-thickness temperature profiles collected in the ablation zone.Our observation-constrained basal heat flux is 30mW m2 less than commonly used representations. In contract, measured near-surface temperatures are warmed than common surface warmer than common surface temperature data sets by up to 15 degrees C. Application of lower basal heat flux increases a model cold bias compared to the measured temperature profiles and causes frozen basal conditions across the ablation zone. Temperate basal conditions are reestablished by our warmer surface boundary. Warmer surface ice and firn can introduce several times more energy to the modeled ice mass than what is lost at the bed from reduced basal heat flux, indicating that the thermomechanical state of the ice sheet is highly sensitive to near-surface effects

Topographic control of asynchronous glacial advances: A case study from Annapurna, Nepal

Differences in the timing of glacial advances, which are commonly attributed to climatic changes, can be due to variations in valley topography. Cosmogenic 10Be dates from 24 glacial moraine boulders in 5 valleys define two age populations, late-glacial and early Holocene. Moraine ages correlate with paleoglacier valley hypsometries. Moraines in valleys with lower maximum altitudes date to the lateglacial, whereas those in valleys with higher maximum altitudes are early Holocene. Two valleys with similar equilibrium-line altitudes (ELAs), but contrasting ages, are \u3c 5 km apart and share the same aspect, such that spatial differences in climate can be excluded. A glacial mass-balance cellular automata model of these two neighboring valleys predicts that change from a cooler-drier to warmer-wetter climate (as at the Holocene onset) would lead to the glacier in the higher altitude catchment advancing, while the lower one retreats or disappears, even though the ELA only shifted by ~120 m